Issue published January 1, 1974

T he secretion of androgens and estrogens by normal and abnormal testes was compared by determining the concentrations of dehydroepiandrosterone (DHEA), androstenedione (Δ₄A), testosterone (T), estrone (E₁), and 17β-estradiol (E₂) in peripheral and spermatic venous plasma samples from 14 normal men and 5 men with unilateral testicular atrophy. Four normal men and one patient with unilateral atrophy of the testis were given human chorionic gonadotropin (HCG) before surgery. Plasma estrogens were determined by radioimmunoassay; plasma androgens were measured by the double-isotope dilution derivative technique. Peripheral concentrations of these steroids before and after HCG were similar in both the normal men and the patients with unilateral testicular atrophy. In normal men, the mean ±SE spermatic venous concentrations were DHEA, 73.1±11.7 ng/ml; Δ₄A, 30.7±7.9 ng/ml; T, 751±114 ng/ml; E₁, 306±55 pg/ml; and E₂, 1298±216 pg/ml. Three of four subjects with unilateral testicular atrophy had greatly diminished spermatic venous levels of androgens and estrogens. HCG treatment increased the testicular secretion of DHEA and T fivefold, Δ₄A threefold, E₁ sixfold, and E₂ eightfold in normal men. In the single subject with an atrophic testis who received HCG, the spermatic venous concentrations of androgens and estrogens were much less than in normal men similarly treated. We conclude that: (a) E₁ is secreted by the human testis, but testicular secretion of E₁ accounts for less than 5% of E₁ production in normal men; (b) HCG stimulation produces increases in spermatic venous estrogens equal to or greater than the changes in androgens, including testosterone; and (c) strikingly decreased secretion of androgen and estrogen by unilateral atrophic human tests cannot be appreciated by analyses of peripheral steroid concentrations.

A n experimental model was designed to study the ability of antibiotics to enter the pericardial compartment. Noninfected and infected pericardial fluid and serum antibiotic activities were determined in adult mongrel dogs before and at intervals after antibiotic administration. After the administration of penicillin G, methicillin, cephaloridine, streptomycin, or gentamicin, clinically adequate antibiotic levels in the noninfected pericardial fluid were obtained within 1 h, and these levels approached or exceeded the serum levels within 2-4 h. Antibiotic levels obtained from infected dog pericardial fluids were higher than those from noninfected animals. Patients' serum and pericardial fluid antibiotic levels were measured after penicillin G, penicillin V, cephalothin, and gentamicin administration. We have found, both in the canine and human studies, that pericardial antibiotic levels taken at least 2 h after antibiotic administration are almost identical to those in the blood.

H istamine, beta-adrenergic amines, and prostaglandins inhibited hemolytic plaque formation by splenic leukocytes from immunized mice. The same agents had previously been shown to prevent both the IgE-mediated release of histamine from human basophils and the immunologically specific cytolytic activity of murine lymphocytes, through stimulation of the production of cyclic AMP in leukocytes. We therefore tested the hypothesis that cyclic AMP might mediate an inhibitory effect of these drugs by comparing the ability of these agents to inhibit plaque formation with their effects on cyclic AMP accumulation in leukocytes. In splenic cells from three mouse strains, the dose-dependent effects of these agents of cyclic AMP correlated with their inhibition of plaque formation. Beta- but not alpha-adrenergic agonists were effective in both systems, and the effects of isoproterenol were inhibited by propranolol. Histamine was approximately equipotent with isoproterenol in both systems. Two prostaglandins (E₁ and E₂) were effective in both systems, but prostaglandin F_2α was not. Dibutyryl cyclic AMP, a lipid-soluble analog of the endogenous nucleotide, inhibited plaque formation by cells of all three strains. Theophylline, an inhibitor of cyclic AMP degradation, inhibited plaque formation slightly, but potentiated the effects of histamine, isoproterenol, and the prostaglandins on both cyclic AMP accumulation and plaque formation. Finally, cholera enterotoxin, a potent activator of adenyl cyclase, produced a delayed inhibition of plaque formation and a parallel increase in leukocyte cyclic AMP content; both effects of the toxin were blocked by canine antitoxin. These results suggest that leukocyte cyclic AMP may act as a “second messenger” to suppress plaque formation in vitro. The inhibitory effects of hormones and cyclic AMP on plaque formation are strikingly similar to their effects on in vitro models of immediate and cell-mediated hypersensitivity. The physiologic significance of these findings is not yet known.

S pleen cells from mice immunized with sheep red cells were separated by differential adherence to insolubilized histamine, catecholamines, and prostaglandins. The hormones were insolubilized by linking them to Sepharose beads through a protein carrier. We measured hemolytic plaque formation (per million splenic leukocytes) of cells which passed through columns of hormone-carrier-Sepharose beads (i.e., those cells that failed to bind). As compared with control (no column) cells, the number of plaque-forming cells was substantially reduced by passage through histamine, epinephrine, isoproterenol, and prostaglandin-E₂ columns. Plaque-forming cells were not significantly reduced by passage through carrier Sepharose (another control) or norepinephrine- and prostaglandin-F_2α-carrier Sepharose columns. Thus, the ability of an insolubilized hormone preparation to subtract plaque-forming cells roughly correlated with the presence of pharmacologic receptors for the corresponding free hormones, as judged by stimulation of cyclic AMP accumulation in the same cells, reported previously. Both 19S and 7S plaque-forming cells were subtracted by columns prepared from pharmacologically active hormones, but none of the insolubilized hormones stimulated accumulation of intracellular cyclic AMP. The cell membrane phenomenon that allows adherence to a given hormone-carrier-bead column may be identical with the cell receptor.

T he red cells of patients with hereditary erythroblastic multinuclearity with a positive acidified serum test (HEMPAS), a form of congenital dyserythropoietic anemia, and the cells of patients with paroxysmal nocturnal hemoglobinuria (PNH) are lysed more readily than normal cells by certain antibodies, notably cold agglutinins (anti-I) and complement. With some but not other examples of anti-I, HEMPAS and PNH cells adsorbed more antibody than normal cells. Equal quantities of adsorbed antibody bound equal quantities of the first component of complement (C1) to normal, PNH, and HEMPAS cells. However, for a given quantity of bound antibody and C1, much more of the fourth component of complement (C4) was bound to HEMPAS cells than to normal cells. This resulted in the binding of proportionately larger quantities of the third component of complement (C3) to these cells. The same amount of bound C3 was found on the membranes of normal and HEMPAS cells for a given degree of lysis. Hence, the marked increase in lysis of HEMPAS cells is due to the increased adsorption of antibody and/or increased binding of C4.PNH cells bound the same amount of C4 per bound C1 as normal cells but bound more C3 than normal cells. However, the mean concentration of C3 on the membrane of PNH cells was one-third to one-fifth that on normal cells for a given degree of lysis. Hence, the increased lysis of PNH cells is due to the increased binding of C3 and increased hemolytic effectiveness of the bound C3.

G lucagon (0.04-0.09 mg/kg/min) was given intravenously for either 2 or 3 min to eight patients with fasting-induced hypoglycemia. One child had hepatic phosphorylase deficiency, two children had glucose-6-phosphatase deficiency, two children had debrancher enzyme (amylo-1,6-glucosidase) deficiency, and two children and one adult had decreased hepatic fructose-1,6-diphosphatase (FDPase) activity. Liver biopsy specimens were obtained before and immediately after the glucagon infusion. The glucagon caused a significant increase in the activity of FDPase (from 50±10.0 to 72±11.7 nmol/mg protein/min) and a significant decrease in the activities of phosphofructokinase (PFK) (from 92±6.1 to 41±8.1 nmol/mg protein/min) and pyruvate kinase (PK) (from 309±39.4 to 165±23.9 nmol/mg protein/min). The glucagon infusion also caused a significant increase in hepatic cyclic AMP concentrations (from 41±2.6 to 233±35.6 pmol/mg protein). Two patients with debrancher enzyme deficiency who had biopsy specimens taken 5 min after the glucagon infusion had persistence of enzyme and cyclic AMP changes for at least 5 min. One child with glucose-6-phosphatase deficiency was given intravenous glucose (150 mg/kg/min) for a period of 5 min after the glucagon infusion and biopsy. The plasma insulin concentration increased from 8 to 152 μU/ml and blood glucose increased from 72 to 204 mg/100 ml. A third liver biopsy specimen was obtained immediately after the glucose infusion and showed that the glucagon-induced effects on PFK and FDPase were completely reversed. The glucagon infusion caused an increase in hepatic cyclic AMP concentration from 38 to 431 pmol/mg protein but the glucose infusion caused only a slight decrease in hepatic cyclic AMP concentration (from 431 to 384 pmol/mg protein), which did not appear to be sufficient to account for the changes in enzyme activities. Hepatic glucose-6-phosphatase and fructose-1,6-diphosphate aldolase activities were not altered by either the glucagon or the glucose infusion in any patients. Cyclic AMP (0.05 mmol/kg) was injected into the portal vein of adult rats and caused enzyme changes similar to those seen with glucagon administration in humans. Our findings suggest that rapid changes in the activities of PFK, PK, and FDPase are important in the regulation of hepatic glycolysis and gluconeogenesis, respectively, in humans and that cyclic AMP may mediate the glucagon- but probably not the glucose-insulin-induced changes in enzyme activities.

C alcium, phosphorus, sodium, carbonate, magnesium, and hydroxyproline were measured in iliaccrest biopsies of 22 normal volunteers and 24 selected patients with renal osteodystrophy. Histologic classification revealed that 10 were mildly abnormal, 8 osteomalacic, and 6 osteofibrotic. Bone density measurements were performed on an additional 12 normal, 11 mildly abnormal, 6 osteomalacic, and 10 osteofibrotic subjects. The results revealed an increase in magnesium and adecrease in carbonate apparent in the minimal and osteomalacic lesions and a much greater change in osteofibrosis. The bone density was decreased in patients with osteofibrosis. These observations would appear to be explained by postulation of an impairment of the normal maturational process of bone whereby there is an increase in amorphous calcium phosphate and a decrease in apatite crystal. The data suggest that the maturational defect is present as soon as any abnormality can be identified histologically, is present to the same degree in osteomalacia, and is most severe in osteofibrosis. In comparison of two sets of six patients matched for age and duration of dialysis, neither acidosis nor vitamin D therapy appeared to influence the severity of the maturational defect.

A n inactive mutant form of red cell carbonic anhydrase B is described in three members of a large kindred who manifest infantile renal tubular acidosis and nerve deafness. A combination of enzymatic and immunologic investigations permitted its detection, despite the fact that both antigenic and electrophoretic properties of the mutant were identical to those of the normal form.

C onsiderable controversy exists over the purported role of obesity in causing hyperglycemia, hyperlipemia, hyperinsulinemia, and insulin resistance; and the potential beneficial effects of weight reduction remain incompletely defined. Hypertriglyceridemia is one of the metabolic abnormalities proposed to accompany obesity, and in order to help explain the mechanisms leading to this abnormality we have proposed the following sequential hypothesis: insulin resistance → hyperinsulinemia → accelerated hepatic triglyceride(TG) production → elevated plasma TG concentrations. To test this hypothesis and to gain insight into both the possible role of obesity in causing the above metabolic abnormalities and the potential benefit of weight reduction we studied the effects of weight loss on various aspects of carbohydrate and lipid metabolism in a group of 36 normal and hyperlipoproteinemic subjects. Only weak to absent correlations (r = 0.03 — 0.46) were noted between obesity and the metabolic variables measured. This points out that in our study group obesity cannot be the sole, or even the major, cause of these abnormalities in the first place. Further, we have observed marked decreases after weight reduction in fasting plasma TG (mean value: pre-weight reduction, 319 mg/100 ml; post-weight reduction, 180 mg/100 ml) and cholesterol (mean values: pre-weight reduction, 282 mg/100 ml; post-weight reduction, 223 mg/100 ml) levels, with a direct relationship between the magnitude of the fall in plasma lipid values and the height of the initial plasma TG level. We have also noted significant decreases after weight reduction in the insulin and glucose responses during the oral glucose tolerance test (37% decrease and 12% decrease, respectively). Insulin and glucose responses to liquid food before and after weight reduction were also measured and the overall post-weight reduction decrease in insulin response was 48% while the glucose response was relatively unchanged. In a subgroup of patients we studied both the degree of cellular insulin resistance and the rate of hepatic very low density (VLDL) TG production before and after weight reduction. These subjects demonstrated significant decreases after weight reduction in both degree of insulin resistance (33% decrease) and VLDL-TG production rates (40% decrease). Thus, weight reduction has lowered each of the antecedent variables (insulin resistance, hyperinsulinemia, and VLDL-TG production) that according to the above hypothesis lead to hypertriglyceridemia, and we believe the overall scheme is greatly strengthened. Furthermore, the consistent decreases in plasma TG and cholesterol levels seen in all subjects lead us to conclude that weight reduction is an important therapeutic modality for patients with endogenous hypertriglyceridemia.

1 54 of 255 individual human renal biopsies studied by immunofluorescence contained varying combinations of immunoglobulins (Ig), complement (C) components C1q, C3, C4, C5, C6, C8, C3 proactivator (C3PA), and/or properdin. 10 patients had linear deposits of Ig in glomeruli characteristic of antiglomerular basement membrane (GBM) antibodies; nine patients had C3 deposits (minimal in three) with generally lesser amounts of C1q, C4, C5, C6, and/or C8. 118 of the patients had granular deposits of Ig, suggesting immune complex glomerulonephritis; 114 of these had deposits of C3, usually accompanied by C1q, C4, C5, and/or C6. These observations indicate that the entire C sequence is deposited in glomeruli in most Ig-mediated glomerulonephritides. However, certain cases of anti-GBM glomerulonephritis with few or no C deposits may utilize pathways of injury independent of C.21 patients had granular C3 deposits without detectable Ig. C5, C6, and C8 were present in the majority of these patients while C1q was absent and scant C4 was observed in only two patients. The presence of only late-acting C components in the absence of Ig, C1q, and C4 suggests selective, possible nonimmune activation of the alternate C pathway. Finally, five patients had granular deposits of C3, C5, C6, and/or C8 diffusely in all or most glomeruli with a lesser number of glomeruli having additional focal granular deposits of Ig, C1q, and C4. This observation suggests that at least two patterns of C activation can occur simulatenously, possibly triggered by antecedent immune complex deposition and then perpetuated by an as yet undetermined mechanism.

T he cellular uptake of N-acetyl-α-D-glucosaminidase, the deficient enzyme in Sanfilippo B disease, and the intracellular fate and metabolic effect of this enzyme have been investigated in Sanfilippo B and normal fibroblasts. For both genotypes the uptake is highly efficient (up to 0.025 mU/h/mg cell protein), specific and constant over a period of at least 6 days. It is probable that the enzyme protein is taken up by adsorptive pinocytosis. The enzymatic activity as well as the biological activity towards ³⁵SO₄-labeled mucopolysaccharides persist in Sanfilippo B cells with a half-life of 34 h, indicating the intralysosomal localization of the pinocytosed enzyme.The data obtained are discussed with regard to a possible enzyme replacement therapy. For Sanfilippo B disease the doses used in the past are considered to be insufficient to cause measurable effects.

E xplants of human adipose tissue were maintained in culture for 1 wk in different glucose concentrations with or without the addition of insulin. After this period of time the explants were carefully washed and then subjected to short-term incubations in the same glucose concentration and in the absence of insulin. With this experimental design the influence of long-term exposure to insulin and different glucose concentrations on adipose tissue metabolism could be studied.The results of these studies show that an increase in the glucose concentration of the culture medium enhanced the basal as well as the catecholamine-stimulated lipolysis in the short-term incubations. The presence of insulin in the culture medium enhanced the lipolytic process as well. Analogous results were obtained with the cellular rate of glucose conversion to triglycerides in the short-term incubations. The stimulating effects of insulin and glucose were most pronounced in the larger adipose cells possibly due to their enlarged surface areas.The data suggest that the metabolism of adipose tissue as revealed by short-term studies may be profoundly influenced by the antecedent biochemical environment.

T he response of lymphocytes from young and old persons to phytohemagglutinin, pokeweed mitogen, or allogeneic lymphocytes has been measured. Lymphocytes from old persons incorporated significantly less tritiated thymidine as compared with lymphocytes from young persons when cultured with plant mitogens or allogeneic cells. The difference in observed lymphocyte reactivity could not be attributed to differences in culture conditions required for maximal transformation of lymphocytes from old or young subjects. The same percentage of thymus-derived and bone marrow-derived lymphocytes was found in the blood from old and young persons. The relationship of these findings to the decline of immunologic competence with age is discussed.

A n experimental model of postischemic, acute renal failure has been developed in Wistar rats with surface glomeruli, thereby making possible a direct assessment of the mechanisms responsible for the fall in glomerular filtration rate that characterizes this disorder. Whole kidney and cortical single nephron filtration rates were reduced proportionately, on average by approximately 40%, after 3 h of nearly complete occlusion of the ipsilateral renal artery. The possibility of a significant transtubular leak of inulin was excluded. This decline in filtration rate occurred in the absence of measured changes in mean arterial pressure, mean glomerular transcapillary hydrostatic pressure, or net ultrafiltration pressure at afferent and efferent ends of the glomerular capillary. Net ultrafiltration pressure at the efferent end of the capillary approached zero both before and after ischemic injury, demonstrating that filtration pressure equilibrium was achieved throughout this study. Single nephron filtration fraction remained unchanged, indicating that the fall in filtration rate was accompanied by a proportional decline in glomerular plasma flow. The results indicate that the fall in filtration rate was solely the consequence of this fall in glomerular plasma flow. Since filtration rate per nephron is equal to the product of the ultrafiltration coefficient and mean ultrafiltration pressure, this product must also have fallen in proportion to the decline in glomerular plasma flow. Evidence is presented to indicate that a change in ultrafiltration coefficient is not required to account for the observed fall in filtration rate. The reduction in glomerular plasma flow, occuring in the absence of a concomitant decline in mean glomerular capillary hydrostatic pressure, resulted from large and proportional increases in afferent and efferent arteriolar resistances. These resistance changes appear to play a fundamental role in the pathogenesis of this form of acute renal failure.

W e studied the acute renal metabolic response in rats made acidotic by a single oral dose of ammonium chloride. Cortical slices from acutely (2-h) acidotic rats utilized more glutamine and produced more ammonia and glucose from glutamine than slices from normal animals. When cortical slices from normal rats were pretreated in vitro with plasma isolated from acutely acidotic rats, they achieved similar increases in glutamine utilization, ammonia formation, and gluconeogenesis from glutamine. We did not observe such stimulation in normal cortical slices pretreated in a low pH-low bicarbonate medium. Our data show that a nondialysable factor is present in plasma from acutely acidotic rats that may be responsible for the early increase in the urinary ammonia observed in such animals.

A cetazolamide, an inhibitor of the enzyme carbonic anhydrase, increased the urinary excretion of cyclic AMP in normal and parathyroidectomized rats. The increase was greater in rats with intact parathyroid glands than in parathyroidectomized rats. This rise in the urinary excretion of cyclic AMP was not due to an increase in urine flow or a change in urine pH. Furosemide caused an increase in urine flow, but did not affect the excretion of cyclic AMP or phosphate. Alkalinization of the urine with bicarbonate did not increase the urinary excretion of phosphate or cyclic AMP. Acetazolamide increased the productionof cyclic AMP by rat renal cortical slices in vitro. This effect was dose-dependent. Acetazolamide also stimulated the activity of renal cortical adenyl cyclase in a dose-dependent manner but had no effect on the activity of cyclic nucleotide phosphodiesterase. The pattern of urinary excretion of cyclic AMP and phosphate after administration of acetazolamide was similar to that observed in rats given parathyroid hormone. It is suggested that acetazolamide stimulates the renal production of cyclic AMP by activating adenyl cyclase and that this may be the mechanism by which this inhibitor of carbonic anhydrase produces phosphaturia.

T he bactericidal and phagocytic capacities of monocytes for E. coli, Staphylococcus, Salmonella, and Listeria, and factors that influence these functions were evaluated and compared with those of the polymorphonuclear leukocytes of 30 normal human subjects. Monocytes killed a significantly smaller proportion of each of the bacterial species than did neutrophils from the same individuals. Whereas the neutrophils of all individuals demonstrated the ability to kill significant numbers of the four bacterial species, there was a marked variation in the effect of monocytes of different individuals on the growth curves of these same bacteria. When the bactericidal capacity of an individual's monocytes to more than one species of bacteria was examined in the same experiment, a significant difference in the effect of monocytes on the growth curve of one bacterial species as opposed to another was noted in 4 of 17 subjects. The bactericidal ability of monocytes of single individuals was consistent on different days in 9 of the 11 subjects whose monocytes were examined more than once against the same bacteria.Studies were performed to determine if the lesser bactericidal capability of monocytes was due to a difference in the ability of monocytes and neutrophils to phagocytize or to a difference in the ability of these cells to kill ingested bacteria or both. The results demonstrated that monocytes phagocytize bacteria significantly less well than neutrophils, but the intracellular killing capacity of both cell types is equal. Addition of phenylbutazone to cell suspensions completely inhibited intracellular killing by both monocytes and neutrophils, suggesting the possibility that the bactericidal mechanisms in both cell types might be similar.Monocyte killing of E. coli, Salmonella, and Listeria, but not of Staphylococcus, was significantly diminished in heat-inactivated autologous serum. Neither increasing the concentration of autologous serum from 10% to 25% nor replacement of autologous serum with pooled human serum had any effect on monocyte killing of any of the four bacteria.These studies demonstrate that peripheral blood monocytes are less bactericidal for the four bacterial species than neutrophils, solely because monocytes are less phagocytic. A baseline for further study of factors that influence monocyte function and for study of this cell in selected patient populations is provided.

M icropuncture studies were performed in the dog to examine the relationship between sodium and phosphate transport in the proximal tubule. In hydropenic, thyroparathyroidectomized animals, administration of parathyroid extract, saline, or acetazolamide resulted in a fall in proximal tubule fluid-to-plasma (TF/P) inulin ratio as well as a rise in tubule fluid-to-plasma ultrafilterable (TF/UF) phosphate ratio. A correlation was found between the changes in fractional reabsorption of sodium and phosphate but the phosphate changes were generally greater than those of sodium. Also, a high distal phosphate delivery in the face of low fractional excretion of phosphate in the urine in thyroparathyroidectomized dogs suggests significant phosphate reabsorption in the distal nephron. On the other hand, calcium chloride infusion to saline-loaded, normal dogs to suppress endogenous parathyroid hormone reduced proximal TF/UF phosphate without change in TF/P inulin, while both parameters remained unchanged in saline-loaded, thyroparathyroidectomized dogs after calcium infusion. An increase in proximal TF/UF phosphate associated with unchanged TF/P inulin was also demonstrated by administration of highly purified parathyroid hormone to saline-loaded, thyroparathyroidectomized dogs. It was concluded that although proximal tubule phosphate transport is generally closely related to that of sodium, the two can dissociate under certain experimental conditions, especially under the influence of parathyroid hormone. These observations also indicate that the effect of parathyroid hormone on proximal tubule phosphate transport is not solely dependent upon its effect on sodium transport.

T hree kinds of plasmin were found to be generated when plasminogen or [¹²⁵I]plasminogen was incubated at 32°C for longer than 20 min in urokinase and 50% glycerol. Each plasmin was then separated by G-200 or G-75 Sephadex filtration, and its physicochemical properties were determined. The molecular weights of the three plasmins as determined by G-200 Sephadex filtration were 125,000±5,000(SD), 63,000±2,000(SD), and 31,500±1,000(SD), and those by sodium dodecyl sulfate(SDS)-polyacrylamide electrophoresis were 130,000±5,000(SD), 64,000±3,000(SD), and 32,000±1,500(SD). It was also found that during the incubation of the smallest plasmin in SDS and beta-mercaptoethanol it was further split into two smaller pieces of about 16,000 mol wt and that polymer proteins of 95,000±2,000(SD) and 48,000±1,500(SD) mol wt were formed. Despite these differences in the molecular size of the three plasmins, the specific activity of each plasmin was closely similar and in case of human plasmins averaged 29±0.9(SD) CTA units/mg plasmin and in case of canine plasmins 8.5±0.54(SD) CTA units/mg plasmin. Then, using human plasmin of the smallest size (mol wt 31,500), the total plasma antiplasmin capacity was determined in 20 normal human plasma, which averaged 7.8±2(SD) CTA units of plasmin per milliliter plasma. Studies were next made of the affinity of human [¹²⁵I]-plasmin of the smallest size with albumin, gamma globulin, α₂-macroglobulin, α₁-antitrypsin, fibrinogen, and fibrin. The results were 0%, 0%, 14.6±0.5(SD)%, 17.6±0.6(SD)%, 21±0.5(SD)%, and 20.5±0.6(SD)%, respectively, of [¹²⁵I]plasmin available and were unaltered when the amount of [¹²⁵I]plasmin was increased to twice and four times the original amount. Finally, the plasma disappearance half-life of canine [¹²⁵I]plasmin of the smallest size was studied in five healthy dogs, which averaged 14.2±0.63(SD) h. These results support the concept that the combination between plasmin and plasmin inhibitors is reversible and indicate that fibrinogen and fibrin have greater affinities than α₂-macroglobulin or α₁-antitrypsin.

P reviously, in an attempt to understand the mechanisms involved in the regulation of plasma cyclic nucleotides, we measured concentrations of adenosine 3′,5′-monophosphate (cAMP) and guanosine 3′,5′-monophosphate (cGMP) in plasma from selected blood vessels of anesthetized dogs. The observation that the renal venous plasma concentrations of both cyclic nucleotides were less than arterial concentrations suggested that the kidney might be an important site for the elimination of these compounds from plasma and prompted further investigation of the renal handling of these compounds.Tracer doses of either [³H]cAMP or [³H]cGMP were administered to anesthetized dogs by constant intravenous infusion, and metabolic clearance rates were determined. Concentrations of endogenous cyclic nucleotide and of cyclic nucleotide radioactivity were measured in aortic and renal venous plasma as well as in urine. Renal venous plasma [³H]cGMP was 39% and [³H]cAMP was 65% of the concentration in arterial plasma. Endogenous cyclic nucleotide levels showed a similar relationship. The plasma clearance rates (PCR) were 271±27 ml/min (mean±SE) for cGMP and 261±17 for cAMP. The total kidney clearance (calculated as the renal plasma flow × renal cyclic nucleotide extraction ratio) accounted for 52±4% and 30±2% of the PCR for cGMP and cAMP, respectively. Only about two-thirds of the total kidney clearance of each cyclic nucleotide could be accounted for by urinary excretion, the remainder presumably being the result of renal metabolism.The urinary clearances of ³H-labeled cGMP (40.9±4.2 ml/min) and endogenous cGMP (45.0±2.3 ml/min) were not significantly different from each other. Both were approximately 50% greater than the glomerular filtration rate, which was 27.1±2.0 ml/min, indicating that a significant amount of urinary cGMP is derived from plasma by tubular secretion.In contrast, the urinary clearances of ³H-labeled cAMP (23.7±1.9 ml/min) and endogenous cAMP (27.2±2.6 ml/min) were nearly equal both to each other and to the glomerular filtration rate, which was 24.6±1.7 ml/min. Thus, in the dog, glomerular filtration of plasma cAMP appears to be responsible for most of the cAMP found in urine. Renla production of cAMP, which in humans contributes from a third to a half of the urinary cAMP, was quantitatively of minor importance in the dog.Thus, under the conditions of these experiments in dogs, renal elimination appears to be responsible for half of the PCR of cGMP and about a third of the PCR of cAMP. About a third of the renal elimination of both cyclic nucleotides appears to be due to metabolic degradation within the kidney, and the balance is due to excretion in the urine.

I n order to determine the sites of net production and removal of the cyclic nucleotides in plasma, various blood vessels were catheterized in 17 anesthetized dogs and arterial and venous concentrations of adenosine 3′,5′-monophosphate (cAMP) and guanosine 3′,5′-monophosphate (cGMP) were measured by radioimmunoassay.Aortic cAMP was 30±2 nM (mean±SE) and cGMP was 13±1 nM. There were no significant differences for either cyclic nucleotide between the concentration in the aorta and that in the inferior vena cava, coronary sinus, hepatic vein, and femoral vein. The concentration of cAMP in renal venous plasma was 25% lower than in aortic plasma, and renal venous cGMP was 51% lower than in the aorta. The pulmonary arterial concentrations of cAMP and cGMP were slightly lower than in the aorta. The concentration of cGMP in the superior mesenteric vein plasma was 83% greater than in aortic plasma; the concentration of cAMP in this vessel was only 16% greater than that in the aorta. Superior vena cava concentrations of both cyclic nucleotides were slightly greater than arterial concentrations.The results suggest that: (a) the kidneys are a major site of removal of both cyclic nucleotides from plasma. (b) The lungs may be a site of net addition of both cyclic nucleotides to plasma. (c) The small intestine is a site of net production of both cyclic nucleotides, particularly cGMP. (d) The liver probably removes cyclic nucleotides from plasma. (e) Since no other organs or regions studied added detectable net amounts of cyclic nucleotides to plasma, and since the turnover of these compounds in plasma is known to be rapid, the production of plasma cyclic nucleotides under basal conditions may well be the result of small net contributions may well be the result of small net contributions from many tissues or bidirectional fluxes between tissues and plasma, or both.

L ymphocyte heterogeneity was studied in peripheral blood and salivary gland lesions in 24 patients with Sjögren's syndrome. Peripheral blood B cells, measured by immunofluorescence with specific antiserum to immunoglobulins or by rosette assay with complementcoated erythrocytes, were increased in most patients. Peripheral blood T cells, measured by immunofluorescence with rabbit antiserum to human thymocytes or by rosette assay with sheep erythrocytes, were reduced in eight patients. Three had associated rheumatoid arthritis, two had a generalized lymphoproliferative disorder, and one each had scleroderma, systemic lupus erythematosus, and neuropathy.The salivary gland lymphocytic infiltrates present in labial biopsy specimens were compared in 10 patients using an indirect immunofluorescent method with anti-human T cell serum and a quantitative focus-scoring method. In general, there was a correlation between the number of T cells and the extent of the infiltrate. Striking accumulations of T cells were present in some patients, but clusters of presumed B cells were also seen. These results indicate an increase in peripheral blood B cells in most patients, a decrease in T cells in some, and a mixed T and B cell infiltrate in the salivary gland lesions.

T he effect of glucagon (50 ng/kg/min) on arterial glycerol concentration and net splanchnic production of total ketones and glucose was studied after an overnight fast in four normal and five insulin-dependent diabetic men. Brachial artery and hepatic vein catheters were inserted and splanchnic blood flow determined using indocyanine green. The glucagon infusion resulted in a mean circulating plasma level of 4,420 pg/ml.In the normal subjects, the glucagon infusion resulted in stimulation of insulin secretion indicated by rising levels of immunoreactive insulin and C-peptide immunoreactivity. Arterial glycerol concentration (an index of lipolysis) declined markedly and net splanchnic total ketone production was virtually abolished. In contrast, the diabetic subjects secreted no insulin (no rise in C-peptide immunoreactivity) in response to glucagon. Arterial glycerol and net splanchnic total ketone production in these subjects rose significantly (P=<0.05) when compared with the results in four diabetics who received a saline infusion after undergoing the same catheterization procedure.Net splanchnic glucose production rose markedly during glucagon stimulation in the normals and diabetics despite the marked rise in insulin in the normals. Thus, the same level of circulating insulin which markedly suppressed lipolysis and ketogenesis in the normals failed to inhibit the glucagon-mediated increase in net splanchnic glucose production.It is concluded (a) that glucagon at high concentration is capable of stimulating lipolysis and ketogenesis in insulin-deficient diabetic man; (b) that insulin, mole for mole, has more antilipolytic activity in man than glucagon has lipolytic activity; and (c) that glucagon, on a molar basis, has greater stimulatory activity than insulin has inhibitory activity on hepatic glucose release.

G lucagon activates hepatic adenylate cyclase, thereby increasing acutely the liver content of cyclic AMP (cAMP) as well as the release of cAMP into the hepatic vein. Insulin, on the other hand, antagonizes this glucagon-mediated cAMP production, thus providing a hypothetical mechanism through which insulin might correct some of the metabolic abnormalities of diabetes.To study this hormonal interaction in man, net splanchnic cAMP production (NScAMPP) was investigated in normal and insulin-dependent diabetic men under basal conditions and in response to intravenous glucagon, 50 ng/kg/min for 2 h.In normals (n=19), basal hepatic vein cAMP concentration was 23.6±1.1 nM and NScAMPP was 1.7±0.6 nmol/min. Glucagon stimulated NScAMPP in four normal subjects to a peak of 99.6±43 nmol/min at 25 min with a subsequent fall to 12.4±5.1 nmol/min by 90 min despite continuing glucagon infusion. Endogenous insulin secretion was stimulated as indicated by rising levels of immunoreactive insulin and C-peptide (connecting peptide) immunoreactivity, raising the possibility that endogenous insulin might be responsible for the fall in NScAMPP that followed the initial spike.In the diabetics (n=8), basal hepatic vein cAMP concentration was 24.7±1.2 nM and NScAMPP was undetectable. Glucagon stimulated NScAMPP in five diabetics to a peak of 169.9±42.6 with a subsequent fall to 17.4±3.9 nmol/min by 90 min even though endogenous insulin secretion was not stimulated (no rise in C-peptide immunoreactivity). Although the mean increase in NScAMPP was greater in the diabetics, the two groups did not differ significantly.Conclusions. In normal resting man the liver is a significant source of circulating cAMP. Diabetics do not release abnormally large amounts of hepatic cAMP under basal conditions. Glucagon markedly enhances hepatic cAMP release with a spike-decline pattern in both normal and diabetic men. The decline in hepatic cAMP release despite continuing glucagon stimulation is due to factors other than a stimulation of insulin secretion.

T he influence of fatty acids on ileal absorption of water, electrolytes, glucose, and taurocholate was examined in Thirty-Vella fistulas in five mongrel dogs. Fatty acid absorption also was measured. Segments of terminal ileum were perfused at steady state with isotonic electrolyte solutions containing 11.2 mM glucose, 4.5 mM taurocholate, and 0.1-5.0 mM fatty acid. Three C₁₈ fatty acids, oleic acid, 10(9)-hydroxystearic acid, and ricinoleic acid, completely inhibited water absorption at 5 mM. Sodium, chloride, and potassium absorptions were inhibited in parallel with absorption of water. Differences between the potencies of C₁₈ fatty acids were apparent when lesser concentrations were perfused. Dodecanoic and decanoic acids were as effective as C₁₈ fatty acids at 5 mM but octanoic and hexanoic acids were ineffective. The polar group of C₁₈ fatty acids was modified by conjugating oleic and ricinoleic acids with taurine. When these compounds and a substituted C₁₈ fatty acid, p-n-decylbenzenesulfonate, were perfused, water absorption was also inhibited. Short-chain fatty acids (C₃ and C₄) and their hydroxylated derivatives were ineffective at 5 mM. When water absorption was inhibited, absorption of glucose and taurocholate was decreased. We speculate that the phenomenon of inhibition of water and electrolyte absorption by fatty acids may be relevant to steatorrhea and diarrhea in man.

W e have previously shown that the erythroagglutinating phytohemagglutinin (E-PHA) from Phaseolus vulgaris binds to the surface of intact human platelets and that adenylate cyclase activity in the particulate fraction of E-PHA-treated platelets is lower than in comparable controls. We now find that E-PHA induces release of [¹⁴C]serotonin from platelets. Release follows binding of E-PHA, and a haptenic inhibitor of E-PHA binding prevents induction of release. E-PHA does not produce platelet lysis and has little effect on [¹⁴C]serotonin uptake. Platelets possess approximately 300,000 receptor sites of E-PHA per cell, and we estimate that about 15% of these sites must be occupied by E-PHA to initiate the release reaction. Prior incubation of platelets with prostaglandin E₁, theophylline, or dibutyryl cyclic AMP prevents E-PHA-induced release, although these agents have little effect on E-PHA binding to platelets. Thrombin and E-PHA produce different rates and extents of serotonin release. Thrombin (1 U/ml) causes release of 75-85% of platelet [¹⁴C]-serotonin, with half-maximal release occurring less than 0.5 min after thrombin addition. E-PHA, however, induces release of only 30-60% of platelet serotonin at a 10-fold slower rate. In addition, utilizing electron microscopy, we have observed striking differences in the morphological changes that occur in platelets exposed to E-PHA as compared with thrombin. Thus, the platelet release reaction may be triggered in part by binding of E-PHA to the cell surface, but this reaction only partially resembles that produced by thrombin.

R ecent studies have demonstrated that the water diuresis associated with intravenous infusion of norepinephrine is mediated primarly by suppression of antidiuretic hormone (ADH) release. To investigate whether the increase in cerebral perfusion pressure with intravenous norepinephrine (0.5 μg/kg/min) is directly responsible for suppression of ADH release, the carotid circulation of dogs was pump-perfused bilaterally to selectively increase cerebral perfusion pressure. In six experiments cerebral perfusion pressure was increased from a mean of 125 to 151 mm Hg and then returned to 120 mm Hg. This maneuver was not associated with a reversible increase in renal water excretion. The possibility was also examined that norepinephrine exerts a direct central effect to suppress ADH release. In 12 experiments norepinephrine was infused into the carotid artery in a subpressor dose (0.12 μg/kg/min) estimated to equal the amount of the catecholamine reaching the cerebral circulation with intravenous norepinephrine. The urinary osmolality (Uosm) was not significantly altered with intracarotid norepinephrine (932 to 959 mosmol/kg H₂O. The possibility was also examined that changes in autonomic neural tone from arterial baroreceptors is responsible for suppression of ADH release with intravenous norepinephrine. In sham-operated animals intravenous norepinephrine diminished Uosm from 1,034 to 205 mosmol/kg H₂O (P<0.001) whereas in animals with denervated arterial baroreceptors intravenous norepinephrine was not associated with a significant alteration in Uosm (1,233 to 1,232 mosmol/kg) H₂O. These different effects on urinary osmolality occurred in the absence of differences in plasma osmolality and volume status. The results therefore indicate that norepinephrine primarily suppresses ADH release by altering autonomic baroreceptor tone rather than by a direct central or pressor effect of the catecholamine. This same mechanism may be the primary pathway for other nonosmotic influences on ADH release.

U nsaturated vitamin B₁₂-binding capacity (UBBC) of human serum is not reproducibly measurable because it increases variably in vitro in relation to time, temperature, and, in the case of plasma, anticoagulant present before removal of cells. This variable increase proved to be due to variable release in vitro of transcobalamin III (TC III) from granulocytes. UBBC increase was greatest (up to fourfold normal levels) in the presence of lithium, which is the heparin salt used in many laboratories doing UBBC studies. In vitro increase was least when blood was collected in EDTA at 0°C and immediately centrifuges at 0°C (T₀ sample); results equivalent to T₀ were obtained at room temperature even after several hours delay when 47 mM fluoride was present; either cold temperature or 47 mM fluoride appeared to prevent TC III release from granulocytes. The measured levels of the three transcobalamins with T₀ methods of collection, which presumably reflect most closely the in vivo circulating levels, suggest that TC I and TC III in normal plasms are of the same order of magnitude and together normally comprise less than 10% of the UBBC.Approximately 90% of the UBBC content of sonicates of peripheral blood granulocytes and of bone marrow aspirates of normal individuals appears to be TC III, with the rest being TC I. Thus, normal myelocytes, like normal granulocytes, appear to contain mainly TC III. No TC II was present in any of the sonicates.The general practice in most laboratories has been to determine serum UBBC. Because in vitro increments of up to 119% were found to occur in serum, this practice should be replaced by collection using methods that prevent such increments. Blood collected in EDTA-47 mM NaF had a stable, reproducible UBBC with no significant in vitro increment with time.EDTA-NaF UBBC was 640±168 (range 380-921 pg B₁₂ bound/ml plasma) for 12 normal adult men and 809±232 (range 505-1208) for normal adult women. It presumably approximates circulating UBBC and is substantially below the serum UBBC mean of 935±262 (range 611-1506 for the same 12 men) and 1273±355 (range 811-2306 for the same 10 women).

T his study was designed to determine the effect of in vivo hydrocortisone on subpopulations of lymphoid cells in normal humans. Subjects received a single intravenous dose of either 100 mg or 400 mg of hydrocortisone, and blood was drawn at hourly intervals for 6 h, and then again at 10 and 24 h after injection. Profound decreases in absolute numbers of circulating lymphocytes and monocytes occurred at 4-6 h after both 100 mg and 400 mg of hydrocortisone. Counts returned to normal by 24 h. The relative proportion of circulating thymus-derived lymphocytes as measured by the sheep red blood cell rosette assay decreased maximally by 4 h and returned to base line 24 h after hydrocortisone. There was a selective depletion of functional subpopulations of lymphocytes as represented by differential effects on in vitro stimulation with various mitogens and antigens. Phytohaemagglutinin response was relatively unaffected, while responses to concanavalin A were significantly diminished. Responses to pokeweed mitogen were unaffected by 100 mg of hydrocortisone, but greatly diminished by 400 mg of hydrocortisone. In vitro responses to the antigens streptokinase-streptodornase and tetanus toxoid were markedly diminished by in vivo hydrocortisone. Reconstitution of monocyte-depleted cultures with autologous monocytes partially corrected the diminished response to antigens. This transient selective depletion of monocytes and subsets of human lymphocytes by a single dose of hydrocortisone is most compatible with a redistribution of these cells out of the circulation into other body compartments.

A new radioisotope method to measure iron absorption from the whole diet was used in this study. The method is based on the concept that food iron is absorbed from two pools, the heme iron pool and the nonheme iron pool, which can be especially labeled with two radioiron isotopes given as hemoglobin and as an iron salt. The purpose of this study was to test the accuracy of this two-pool extrinsic tag method.The meals served were composed as an average of 6 wk consumption in the present material of 32 young enlisted men. The mean and total heme and nonheme iron absorption in all the 32 young men was 1.01±0.11. This figure agrees well with the mean daily losses expected for this group of subjects (1.0 mg). The conclusion can therefore be made that there are no major systematic errors of the present method to measure the total iron absorption from a mixed diet.In one series a comparison was made of the absorption of heme and nonheme iron from the meals. A significant correlation between the absorption of the two kinds of iron was found. However, a much greater fraction of the heme iron was absorbed (37%) than of the nonheme iron (5%).The absorption both from breakfast and lunch was in two series found to give a good prediction of the total daily nonheme iron absorption. One series was designed to compare the effect of two levels of iron fortification. There was a significant increase in iron absorption when the level of iron fortification of the meals was increased.

R enal failure of 4 wk duration in rats led to parathyroid enlargement, increased bone resorption, and decreased tubular reabsorption of phosphate by the remnant kidney. The degree of hyperparathyroidism was influenced by each of the three dietary factors investigated. In the first study increasing calcium intake reduced the size of the parathyroids by increasing calcium and reducing phosphate absorption. In the second study phosphate intake was linearly related to parathyroid gland size in the uremic animals and associated with rising plasma phosphate levels. In the last study acidosis led directly to increased bone resorption but small parathyroid glands associated with elevated ionized calcium levels. Alkalosis lowered the serum ionized calcium and led to parathyroid enlargement and the expected associated findings. It was shown that parathyroid weight reflected both metabolic activity as judged by amino acid uptake, and the content of immunoassayable parathyroid hormone. In all studies gland weight was inversely related to serum ionized calcium.

T o evaluate whether immunological enhancement plays a role in adaptation to renal allografts, we studied sera from transplant recipients to determine whether those which suppressed mixed leukocyte culture (MLC) responses in vitro contained alloantibodies reactive with donor cells. Sera from five of nine renal transplant recipients consistently and specifically suppressed autologous autologous MLC responses to donor cells without impairing the blastogenic responses to third-party leukocytes, soluble antigens, or nonspecific mitogenic agents. In three of the five cases the suppressive activity of the serum was striking; in two cases the effect was less marked but still readily demonstrable in studies designed to evaluate the dose of serum which provided optimal suppression of MLC responses. Serum from one of the recipients nonspecifically suppressed blastogenic activity both to donor cells and other stimuli. No alloantibody reactive with donor leukocytes was found in any of the sera which exhibited suppressive activity in MLC, whereas in one patient, serum which contained antibody reactive with donor cells did not suppress MLC response to that donor. These findings suggest that, if the serum factors which suppress MLC responses in vitro are enhancing antibodies, they are not detectable even with very sensitive techniques either because they are present in very low concentrations, belong to immunoglobulin classes other than IgA, IgG, or IgM, or are complexed with donor antigen in such a way that their ability to react with fresh donor cells in vitro is blocked.

T he functional and morphologic pattern of superficial nephron development was studied in guinea pigs ranging in age between 2 h and 38 days. Concomitent measurements of total kidney function and glomerular counts were also performed.Superficial nephron glomerular filtration rate was found to increase from 0.92 to 19.32 nl/min. The filtration rate of the entire kidney rose from 0.19 to 1.31 ml/min. During the first 15 days of life the average rate of increase in glomerular filtration rate per nephron (0.48 nl/min·day), obtained by dividing the increase in total kidney glomerular filtration rate by glomerular number, was more than twice the observed rate of increase in the superficial nephrons (0.21 nl/min·day). During the remainder of the first month, the increase in superficial nephron glomerular filtration rate (0.97 nl/min·day) was greater than the average increase for all nephrons (0.71 nl/min·day). Thus, the initial increase in total kidney glomerular filtration rate was primarily a consequence of the activity of the deep nephrons, whereas during the ensuing period the superficial nephrons appeared to be the sole contributors to the change in total kidney glomerular filtration rate.The increase in superficial nephron glomerular filtration rate was found to correlate closely with the increase in proximal tubular length. Functional glomerulotubular balance was maintained throughout the entire period of renal maturation.

T he coronary vasoconstrictor properties of digitals were evaluated in 61 anesthetized, openchest dogs after coronary sinus cannulation and under conditions of a constant heart rate (atrioventricular pacing) and near-constant blood pressure. The contribution of alpha adrenergic receptor stimulation to the digitalis-induced increase in coronary vascular resistance (CVR) was examined. With Na pentobarbital anesthesia (16 dogs), intravenous acetylstrophanthidin (0.5 mg) caused a significant (P<0.05) rise in CVR from 1 through 9 min after injection. The peak increase was +11±2% SE of the control of 1.8±0.2 mm Hg/cm³/min. The mean time to peak effect was 3 min, and to recovery was 21 min. Prior alpha adrenergic receptor blockade with phenoxybenzamine in 11 animals reduced (P<0.05) the acetylstrophanthidin-induced peak of CVR and substantially decreased (P<0.05) the time to recovery (5 min). Intravenous digoxin (1.0 mg) with Na pentobarbital anesthesia (five dogs) had no significant effect on CVR. However, with chloralose and urethane anesthesia (nine dogs) the same dose of digoxin produced a significant rise in CVR from 3 through 30 min. The peak increase was +20±3% of control (1.4±0.1 mm Hg/cm³/min). One-third the dose of intravenous digoxin (0.35 mg) produced a 9.5±1.0% increase in CVR (five additional dogs). Myocardial oxygen consumption did not change significantly in nine dogs after intravenous digoxin. In 10 additional dogs pretreated with phenoxy-benzamine and in 7 dogs pretreated with mecamylamine, the increase in CVR did not occur after 1.0 mg of intravenous digoxin. Thus there is a coronary vasoconstrictor effect of intravenous acetylstrophanthidin and digoxin, of rapid onset, which is mediated through alpha adrenergic receptor stimulation.

S elective release of inflammatory materials from leukocyte lysosomes is reduced by compounds which increase cyclic 3′,5′-adenosine monophosphate (cAMP) levels in suspensions of human leukocytes and is augmented by agents which increase cyclic 3′,5′-guanosine monophosphate (cGMP) levels in these cell suspensions. Lysosomal enzymes are released in the absence of phagocytosis when cytochalasin B (5 μg/ml) converts polymorphonuclear leukocytes (PMN) to secretory cells: lysosomes merge directly with the plasma membrane upon encounter of PMN with zymosan, and cells selectively extrude substantial proportions of lysosomal, but not cytoplasmic enzymes. β-Adrenergic stimulation of human leukocytes produced a dose-related reduction in β-glucuronidase release (blocked by 10^-6 M propranolol) whereas α-adrenergic stimulation (phenylephrine plus propranolol) was ineffective. In contrast, the cholinergic agonist carbamylcholine chloride enhanced enzyme secretion, an effect blocked by 10^-6 M atropine. Incubation of cells with exogenous cAMP or with agents that increase endogenous cAMP levels (prostaglandin E1, histamine, isoproterenol, and cholera enterotoxin) reduced extrusion of lysosomal enzymes; in contrast, exogenous cGMP and carbamylcholine chloride (which increases endogenous cGMP levels), increased β-glucuronidase release. Whereas colchicine (5 × 10^-4 M), a drug which impairs microtubule integrity, reduced selective enzyme release, deuterium oxide, which favors microtubule assembly, enhanced selective release of lyosomal enzymes. The data suggest that granule movement and acid hydrolase release from leukocyte lysosomes requires intact microtubules and may be modulated by adrenergic and cholinergic agents which appear to provoke changes in concentrations of cyclic nucleotides.

E lectrical ventricular defibrillation of heavy subjects (over 100 kg body weight) is uncommon for the human or any animal species. This paper reports trans-chest ventricular defibrillation of subjects ranging in weight from 2.3 to 340 kg using conventional defibrillation current (heavily damped sine wave) of 0.3-30 ms duration. It was found that a body weight-to-electrical-shock strength relationship exists and can be expressed in terms of either electrical energy or peak current. For the duration of current pulse used clinically (3-10 ms), the relationship between energy requirement and body weight is expressed by the equation U = 0.73 W^1.52, where U is the energy in W·s and W is the body weight in kilograms. The current relationship is I = 1.87 W^0.88 where I is the peak current in amperes and W is the body weight in kilograms. The energy dose is somewhat more species and weight dependent and ranges from 0.5 to 10 W·s/kg (0.23-4.5 W·s/lb). The data obtained indicate that the peak current dose is virtually species and weight independent and is therefore a better indicator than energy for electrical defibrillation with precordial electrodes. In the duration range of 3-10 ms, the electrical dose is very nearly 1 A/kg of body weight (0.45 A/lb).

E xamination of 13 members of a Filipino family revealed that 6 had erythrocytosis inherited as a simple autosomal dominant trait. Application of several electrophoretic and chromatographic tests failed to reveal the presence of an abnormal hemoglobin in hemolysates from affected individuals. However, measurements of oxygen dissociation curves using whole bloods, dialyzed hemolysates, and 2,3-diphosphoglyceric acid-stripped hemolysates clearly showed that affected persons had an abnormal hemoglobin characterized by a high affinity for oxygen. Compositional analyses of all tryptic peptides from the β-chains of the proband revealed a valyl-methionyl ambiguity in βT12a. Blockage of lysyl residues and subsequent tryptic hydrolysis at arginyl residues permitted the isolation of fragments containing residues 105 through 146. Automatic sequence analysis of the fragments demonstrated the presence of both valine and methionine in nearly equal proportions at position β109. This new hemoglobin variant is designated Hb San Diego (β109(G11) Val→Met).

T he three-dimensional structure of deoxyhemoglobin San Diego has been solved to 3.5 Å resolution using mixed crystals of the variant hemoglobin and hemoglobin A. The site of the amino acid replacement can be clearly located in the difference electron density map and is consistent with the chemical result (β109 Val→Met) discussed in the preceding paper. The abnormally high oxygen affinity and impaired cooperativity appear to result from perturbations of the α₁β₁-subunit interface.

I n a cell-free system prepared from guinea pig gastric mucosa, histamine and Nα-methyl-histamine produced dose-dependent stimulation of cyclic AMP formation and 1,4-methylhistamine had a minimal stimulatory effect. N-methyl-N′-(2-[5-methylimidazole-4-yl-methylthio]-ethyl) -thiourea (metiamide), a new H2 receptor inhibitor, selectively blocked the stimulation of adenylate cyclase by histamine and its active methyl derivative but had no substantial effect on the basal adenylate cyclase activity or adenylate cyclase stimulated by sodium fluoride. Metiamide inhibited the histamine stimulation of adenylate cyclase at 1/100 the concentration of the histamine. Histamine, its methyl derivatives, and metiamide did not influence the activity of cyclic AMP phosphodiesterase from gastric mucosa. Therefore, histamine stimulates gastric mucosal adenylate cyclase via interaction with the H2 receptor without influencing cyclic AMP breakdown, and N-methylation of histamine on the side chain preserves or even increases its stimulating ability. On the other hand, N-methylation in the ring nearly abolishes the ability of histamine to interact with the H2 receptor.

C hanges in the plasma free fatty acids of a pancreatectomized subject and in free fatty acids and insulin in 10 normal subjects in response to the in vivo infusion of epinephrine alone, epinephrine plus phentolamine, and epinephrine plus propranolol indicate that both alpha and beta adrenergic receptors are present in human adipose tissue. Under the experimental conditions used, adipose tissue appeared to be more responsive to epinephrine than did the cardiovascular system.