2-n-Butyl-3-(4'-diethylaminoethoxy-3',5'-diiodobenzoyl)-benzofurane (amiodarone), a drug used in arrythmias and angina pectoris, contains 75 mg of organic iodine/200 mg active substance. Four studies were performed to test its effect on thyroid hormone metabolism: (a) nine male subjects were treated with 400 mg of amiodarone for 28 days; (b) five male subjects received, for the same period of time, 150 mg of iodine in the form of Lugol's solution; (c) five subjects received 300 mug L-thyroxine (T4) for 16 days; from the 10th to the 16th day, 400 mg of amiodarone was added; and (d) five euthyroid subjects received 300 mug L-T4 for 16 days. The changes in serum thyroid-stimulating hormone (TSH), serum total T4, 3,5,3'-triiodothyronine (T3), free T3, and 3,5',3'-triiodothyronine (reverse T3, rT3) were measured, and the pituitary reserve in TSH was evaluated by a thyrotropin-releasing hormone (TRH) test. The results show that amiodarone induced a decrease in serum T3 (28+/-5.1 ng/100 ml, mean+/-SEM, P less than 0.0S and 82.7+/-9.3 ng rT3/100 ml, P less than 0.01). The control study with an equal amount of inorganic iodine did not induce these opposite changes but slightly lowered serum rT3, T3, and T4. In the third study, serum rT3 increased as under amiodarone treatment, thereby proving that these changes were peripheral. It is suggested that amiodarone changes thyroid hormone metabolism, possibly by reducing deiodination of T4 to T3 and inducing a preferential production of rT3. Amiodarone also increased the response of TSH to TRH. The maximal increment of serum TSH above base line was 32+/-4.5 muU/ml under treatment and 20+/-3 muU/ml before treatment (P less than 0.01). During this test, the serum T3 increase was more pronounced than during the control period (83+/-13 and 47+/-7.4 ng/100 ml, P less than 0.05).
A Burger, D Dinichert, P Nicod, M Jenny, T Lemarchand-Béraud, M B Vallotton
The steady state kinetics of lead metabolism were studied in five healthy men with stable isotope tracers. Subjects lived in a metabolic unit and ate constant low lead diets. Their intake was supplemented each day with 79--204 mug of enriched lead-204 as nitrate which was ingested with meals for 1--124 days. The concentration and isotopic composition of lead was determined serially in blood, urine, feces, and diet and less commonly in hair, nails, sweat, bone, and alimentary tract secretions by isotopic dilution, mass spectrometric analysis. The data suggest a three compartmental model for lead metabolism. The first compartment encompasses blood and is 1.5--2.2 times larger than the blood mass. It contains approximately 1.7--2.0 mg of lead and has a mean life of 35 days. This pool is in direct communication with ingested lead, urinary lead, and pools two and three. The second compartment is largely composed of soft tissue, contains about 0.3--0.9 mg of lead, and has a mean life of approximately 40 days. This pool gives rise to lead in hair, nails, sweat, and salivary, gastric, pancreatic, and biliary secretions. Pool three resides primarily in the skeleton, contains the vast quantity of body lead, and has a very slow mean life. Bones appear to differ in their rates of lead turnover. Within the relatively small changes in blood lead observed in the present study, the transfer coefficients between the pools remained constant.
M B Rabinowitz, G W Wetherill, J D Kopple
In vivo studies have shown a major role for the alveolar macrophage in the killing of inhaled bacteria. This contrasted with earlier work which showed a preservation of phagocytic properties but a loss of bactericidal capacity when alveolar macrophages were studied in vitro. Recently, alveolar lining material (ALM) from rats has been shown to enhance the in vitro bactericidal capacity of alveolar macrophages from homologous animals against Staphylococcus aureus. Utilizing a similar system, we have confirmed that rat alveolar macrophages do not kill S. aureus in vitro unless the bacteria have been incubated with rat ALM (R-ALM) before phagocytosis. In addition, human ALM (H-ALM) from 7 of 11 patients assayed showed an enhancement of bactericidal capacity by rat alveolar macrophages which was not significantly different from the results utilizing R-ALM. H-ALM from the other four patients gave results which differed significantly from results with H-ALM from the first seven patients and R-ALM (P less than 0.001). Preliminary results suggest that the factor enhancing the bactericidal capacity of rat alveolar macrophages is present in the lipid fraction of the ALM. Further characterization of the ALM is warranted in an effort to explain the enhancement of the bactericidal capacity of alveolar macrophages by most, but not all, H-ALM tested.
J A Juers, R M Rogers, J B McCurdy, W W Cook
Although the systemic and local immune response to the O antigen of Escherichia coli has been well characterized, little information is available on the immune response to K anigen. Experimental hematogenous pyelonephritis was produced with Escherichia coli 06 K13 H1 and the serum and local (intrarenal) antibody response to O and K antigens was determined with the enzyme-linked immunosorbent assay. Both local and serum antibody responses to the K antigen were significantly less than that to the O antigen. The K antigen induced low titer IgM and IgG antibody responses in fewer than one-half of the animals and did not induce a local IgA response in any animal. In contrast, the O antigen induced local antibody responses in each of the immunoglobulin classes in all animals from day 9 of infection. Similarly, the serum IgM and IgG antibody titers to the K antigen were significantly less than those evoked in response to the O component of the Escherichia coli. No serum IgA anti-K antibodies were detected. These observations helf clarify the roles of these two antigens in pyelonephritis. Although the K antigen of Escherichia coli functions as a virulence factor in upper urinary tract infections, this antigen does not elicit a significant immune response, whereas the O antigen does induce a significant antibody response which could be of protective or diagnostic benefit.
J W Smith, B Kaijser
The administration of two different doses of indomethacin, 9 and 18 mg/kg, to two different groups of rabbits was followed 6 h later by a significant decrease in plasma renin activity, and these levels were not increased by hemorrhage. The administration of 2 mg/kg of indomethacin did not alter the basal levels of plasma renin activity, but it was effective in diminishing the peripheral increase of renin produced by hemorrhage. Similar effects were obtained in other groups of rabbits treated with 9 mg/kg of meclofenamate or 18 mg or aspirin. The lowering effect of indomethacin on plasma renin activity is not specifically related to hemorrhage because it also prevented the increase in plasma renin activity elicited by 5 mg/kg of furosemide. Further studies showed that indomethacin did not exert any significant effect in vivo on the plasma level of renin substrate or on the generation of angiotensin from normal plasma by exogenous renin. And indomethacin did not interfere with the binding capacity of anti-angiotensin I for angiotensin I in the radioimmunoassay reaction or with the in vitro formation of angiotensin from hog renin-nephrectomized rabbit plasma reaction. The results thus indicate that the lowering effect of indomethacin on plasma renin activity is due to the interference with renal renin release. That this effect may be related to the blockade of prostaglandin synthesis is suggested by the similar effect exhibited by other blockers of prostaglandin synthesis.
J C Romero, C L Dunlap, C G Strong
Human peripheral blood leukocytes were studied for the presence and the regulatory properties of the pathway of de novo synthesis of purine nucleotides. The cells were found to incorporate the labeled precursors formate and glycine into purines. The rate of [14C]-formate incorporation was decreased by several compounds known to inhibit purine synthesis by affecting the activity by glutamine phosphoribosylpyrophosphate (PRPP) amidotransferase, the first committed enzyme in the pathway, either through decreasing the availability of PRPP, a substrate for this enzyme, or through exerting inhibition on this enzyme. PRPP availability in the leukocyte was found to be limiting for purine synthesis. Increased PRPP availability resulting from activation of PRPP synthetase by increasing inorganic phosphate (Pi) concentration caused acceleration of purine synthesis. On the other hand, no clear-cut evidence was obtained for the availability of ribose-5-phosphate in the leukocyte being rate limiting at physiological extracellular Pi concentration for PRPP generation, and thus for purine synthesis. However, the addition of methylene blue, which accelerates the oxidative pentose shunt that produces ribose-5-phosphate, resulted in acceleration of PRPP generation and of purine synthesis only when PRPP synthetase was largely activated at high Pi concentration. These results may be taken to suggest that ribose-5-phosphate availability is indeed not limiting for PRPP generation under physiological conditions. Purine synthesis de novo was accelerated more than 13-fold in the leukocytes of two gouty patients affected with partial deficiency of hypoxanthine-guanine phosphoribosyltransferase, but was normal in the leukocytes of an obligate heterozygote for this enzyme abnormality. The results domonstrate in peripheral human leukocytes the presence of the complete pathway of de novo synthesis of purine nucleotides and the manifestation in these cells of the biochemical consequences of hypoxanthine-guanine phosphoribosyltransferase deficiency, i.e., increased availability of PRPP and acceleration of purine synthesis de novo. The results indicate the usefulness of leukocytes as a model tissue for the study of purine metabolism in man.
S Brosh, P Boer, B Kupfer, A de Vries, O Sperling
Absorption of labeled simple 3′,5′,9′-3H pteroylmonoglutamate, ([3H]PG-1) and conjugated pteroyl-μ[14C]glutamyl-γ-hexaglutamate, ([14C]PG-7) folates was assessed in six patients with tropical sprue, before and after 6 mo of treatment, utilizing jejunal perfusion and urinary recovery techniques. Degradation products of [14C]PG-7 which were produced during perfusion were identified by DEAE-cellulose column chromatography. Jejunal mucosal activities of folate conjugase, lactase, sucrase, and maltase were measured in every patient. Malabsorption of both [3H]PG-1 and [14C]PG-7 was found in every untreated patient, with significant improvement after therapy. The urinary excretion of 3H and 14C paralleled the luminal disappearance of both isotopes. The chromatographic patterns of intraluminal degradation products of [14C]PG-7 obtained during perfusion did not differ from those previously found in normal subjects and were similar in studies performed before and after treatment. The activity of folate conjugase was increased in the mucosa of the untreated patients when compared to the post-treatment levels while the activities of mucosal lactase, sucrase, and maltase were originally low and increased significantly after therapy. These observations suggest that folate conjugase originates at a different mucosal locus than the brush border disaccharidases, and are consistent with previous evidence that folate conjugase is an intracellular enzyme. The present studies have demonstrated unequivocal malabsorption of both simple and conjugated folates in tropical sprue. In tropical sprue, folate malabsorption is the reflection of impaired folate transport and not of impaired hydrolysis.
José J. Corcino, Ann M. Reisenauer, Charles H. Halsted
Rapid hemodialysis of uremic animals may induce a syndrome characterized by increased cerebrospinal fluid (CSF) pressure, grand mal seizures, and electroencephalographic abnormalities. There is a fall in pH and bicarbonate concentration in CSF, and brain osmolality exceeds that of plasma, resulting in a net movement of water into the brain. This syndrome has been called experimental dialysis disequilibrium syndrome. The fall in pH of CSF may be secondary to a fall of intracellular pH (pHi) in brain. Since changes in pHi can alter intracellular osmolality in other tissues, it was decided to investigate brain pHi in uremia, and the effects of hemodialysis. Brain pHi was measured by evaluating the distribution of 14C-labeled dimethadione in brain relative to CSF, while extracellular space was calculated as the 35504=/4 space relative to CSF. In animals with acute renal failure, brain (cerebral cortex) pHi was 7.06+/-0.02 (+/-SE) while that in CSF was 7.31+/-0.02, both values not different from normal. After rapid hemodialysis (100 min) of uremic animals, plasma creatinine fell from 11.8 to 5.9 mg/dl. Brain pHi was 6.89+/-0.02 and CSF pH and 7.19+/-0.02, both values significantly lower than in uremic animals (P less than 0.01), and there was a 12% increase in brain water content. After slow hemodialysis (210 min), brain pHi (7.01+/-0.02) and pH in CSF (7.27+/-0.02) were both significantly greater than values observed after rapid hemodialysis (P less than 0.01), and brain water content was normal. None of the above maneuvers had any effect on pHi of skeletal muscle or subcortical white matter. The data show that rapid hemodialysis of uremic dogs is accompanied by a significant fall in pH of CSF and pHi in cerebral cortex. Accompanying the fall in brain pHi is cerebral edema.
A I Arieff, R Guisado, S G Massry, V C Lazarowitz
The effects of digitalis glycosides on myocardial oxygen supply and demand are of particular interest in the presence of obstructive coronary artery disease, but have not been measured previously in man. We assessed the effects of ouabain (0.015 mg/kg body weight) on hemodynamic, volumetric, and metabolic parameters in 11 patients with severe chronic coronary artery disease without clinical congestive heart failure. Because the protocol was long and involved interventions which might affect the determinations, we also studied in nine patients using an identical protocol except that ouabain administration was omitted. Left ventricular end-diastolic pressure and left ventricular end-diastolic volume fell in each patient given ouabain, even though they were initially elevated in only two patients. Left ventricular end-diastolic pressure fell from 11.5+/-1.4 (mean+/-SE) to 5.6+/-0.9 mm Hg (P less than 0.001) and left ventricular end-diastolic volume fell from 100+/-17 to 82+/-12 ml/m2 (P less than 0.01) 1 h after ouabain infusion was completed. The maximum velocity of contractile element shortening increased from 1.68+/-0.11 ml/s to 2.18+/-0.21 muscle-lengths/s (P less than 0.05) and is consistent with an increase in contractility. No significant change in these parameters occurred in the control patients. No significant change in myocardial oxygen consumption occurred after ouabain administration but this may be related to a greater decrease in mean arterial pressure in the ouabain patients than in the control patients. We conclude that in patients with chronic coronary artery disease who are not in clinical congestive heart failure left ventricular end-diastolic volume falls after ouabain administration even when it is initially normal. Though this fall would be associated with a decrease in wall tension, and, therefore, of myocardial oxygen consumption, it may not be of sufficient magnitude to prevent a net increase in myocardial oxygen consumption. Nevertheless, compensatory mechanisms prevent a deterioration of resting myocardial metabolism.
H DeMots, S H Rahimtoola, E L Kremkau, W Bennett, D Mahler
To examine whether abnormal pancreatic alpha-cell function found in human diabetes mellitus may represent a selective insensitivity to glucose, plasma glucagon responses to hyperglycemia and elevation of plasma free fatty acid levels (both known suppressors of glucagon secretion) were compared in juvenile-onset, insulin-requiring diabetic subjects, and in normal nondiabetic subjects. In the latter, both elevation of plasma free fatty acid levels induced by heparin administration of hyperglycemia produced by intravenous infusion of glucose resulted in a comparable 30--40% suppression of circulating glucagon levels (P less than 0.01). In the diabetic subjects, glucagon suppression by hyperglycemia (less than 20%) was less than that occurring in normal subjects (P less than 0.01), even when accompanied by infusion of supraphysiologic amounts of insulin. However, suppression of glucagon levels by elevation of plasma free fatty acids in the diabetic group was similar to that found in normal subjects and of comparable magnitude to that due to hyperglycemia in the normal subjects. These results thus demonstrate a selective impairment of the diabetic alpha-cell response to glucose and provide further evidence for the presence of an abnormal alpha-cell glucoreceptor in human diabetes mellitus.
J E Gerich, M Langlois, C Noacco, M Lorenzi, J H Karam, P H Korsham
Particle-free extracts prepared from kidney cortex of rat catalyze the formation of ammonia via the purine nucleotide cycle. The cycle generates ammonia and fumarate from aspartate, using catalytic amounts of inosine monophosphate, adenylosuccinate, and adenosine monophosphate. The specific activities of the enzymes of the cycle are 1.27+/-0.27 nmol/mg protein per min (SE) for adenoylosuccinate synthetase, 1.38+/-0.16 for adenylosuccinase, and 44.0+/-3.3 for AMP deaminase. Compared with controls, extracts prepared from kidneys of rats fed ammonium chloride for 2 days show a 60% increase in adenylosuccinate synthetase and a threefold increase in adenylosuccinase activity, and a greater and more rapid synthesis of ammonia and adenine nucleotide from aspartate and inosine monophosphate. Extracts prepared from kidneys of rats fed a potassium-deficient diet show a twofold increase in adenylosuccinate synthetase and a threefold increase in adenylosuccinase activity. In such extracts the rate of synthesis of ammonia and adenine nucleotide from aspartate and inosine monophosphate is also increased. These results show that the reactions of the purine nucleotide cycle are present and can operate in extracts of kidney cortex. The operational capacity of the cycle is accelerated by ammonium chloride feeding and potassium depletion, conditions known to increase renal ammonia excretion. Extracts of kidney cortex convert inosine monophosphate to uric acid. This is prevented by addition of allopurinol of 1-pyrophosphoryl ribose 5-phosphate to the reaction mixture.
R T Bogusky, L M Lowenstein, J M Lowenstein
Renal micropuncture and clearance experiments were carried out in rats to study the effect of parathyroid hormone (PTH) on renal tubular HCO-/3 reabsorption. The rats were studied during an initial period of parathyroid deficiency (acute thyroidparathyroidectomy, TPTX) and during infusion of large amounts of bovine PTH. Under normal acid-base conditions, PTH administration to TPTX rats caused a significant rise in proximal tubular fluid HCO-/3 concentration (TFHCO-/3), a decrease in fluid reabsorption, and a fall in proximal HCO-/3 reabsorption from 94.0 to 88.2% (P less than 0.01). In control experiments with mannitol infusion, a comparable reduction in proximal fluid reabsorption occurred without any significant effect on intraluminal HCO-/3 concentration. During acute intravenous HCO-/3 loading, PTH inhibited proximal HCO-/3 reabsorption. However, no change in whole kidney HCO-/3 reabsorption was observed in these experiments or in the animals studied under normal acid-base conditions. The findings are consistent with the view that PTH inhibits proximal tubular HCO-/3 reabsorption with normal or high filtered loads of HCO-/3, but distal segments of the nephron are able to reabsorb the excess delivered from the proximal tubule. Measurements of urinary ammonium and titratable acid indicate that net acid excretion (NH+/4 + TA -- HCO-/3) increases significantly after PTH administration. These results do not provide support for the view that PTH excess causes metabolic acidosis by reducing renal acid excretion.
N Bank, H S Aynediian
Maximum specific 5alpha-dihydrotestosterone (DHT) binding activity (Bmax) had been measured in intact confluent monolayers representing fibroblast strains derived form nongenital and genital (labium majus) skin of normal individuals and of 11 patients fulfilling the clinicogenetic criteria of complete testicular feminization (TF). Nine labium majus strains from adult females had a mean Bmax value three times greater than that of seven nongenital strains from adult females (33 vs. 11 fmol/mg cell protein). The Bmax results for 13 adult nongenital strains varied from 5.6 to 23.3 fmol/mg protein; the values for males and females had very similar means and ranges. The variation could not be correlated with the chronologic age of adult skin explant donors or with the in vitro age (mean population doubling level) of the cultures assayed. The Bmax activities of three nongenital strains from normal infants (two male, one female) did not exceed 5 fmol/mg protein. Seven of eight nongenital TF strains had Bmax values below 2 fmol/mg protein; the value for the eighth coincided with the lower limit of normal adults. The lower limit of DHT binding in normal labium majus strains was 15 fmol/mg protein. Three of five labial strains from patients with TF had Bmax values close to zero; the other two fell between 10 and 15 fmol/mg protein. It is apparant that labial skin fibroblast strains from clinically homogeneous patients with TF had highly variable degrees of DHT binding deficiency, and that they permit a more reliable diagnosis of severe and intermediate degrees of DHT binding deficiency than do strains of nongenital skin fibroblasts.
M Kaufman, C Straisfeld, L Pinsky
Aldosterone stimulates not only Na+ absorption but also urinary acidification. In this investigation the effects of aldosterone on H+ transport are examined in vitro in turtle bladder, a urinary membrane in which several of the factors controlling H+ transport have been defined. H+ transport was increased in bladder halves exposed to aldosterone compared to control halves. Stimulation of H+ secretion was observed as early as 1 h after addition of aldosterone and occurred before that of Na+ transport. In bladders depleted of endogenous substrate addition of glucose increased H+ transport more in aldosterone-treated halves (10.0+/-1.3 nmol/min) than in control halves (6.8+/-2.3). Addition of pyruvate failed to increase H+ transport (--0.3+/-0.7) in control halves but caused significant increments (2.4+/-0.5) in aldosterone-treated halves. In aldosterone-treated bladders glucose caused larger increments (16.5+/-2.7) in H+ transport than pyruvate (9.3+/-2.0) when halves of the same bladders were compared. Na+ transport, however, was equally increased by the two substrates. Despite the differences in time course and substrate requirements between the stimulation of H+ and Na+ transport, both increases were abolished by actinomycin-D. To examine the effect of aldosterone on the force of the H+ pump, protonmotive force, the pH gradient that would nullify the transport rate was determined with and without aldosterone. Aldosterone did not alter protonmotive force but significantly increased the slope of the H+ transport rate on the applied pH gradient. It is concluded that aldosterone stimulates H+ transport independently of Na+ transport. It increases the responsiveness of the transport rate to glucose and to a lesser extent pyruvate, an effect probably secondary to the increased transport rate. Equivalent circuit analysis indicates that aldosterone facilitates the flow of protons through the active transport pathway but does not increase the force of the pump.
Q Al-Awqati, L H Norby, A Mueller, P R Steinmetz
The relative contributions of Ca++, phosphorus, and parathyroid hormone (PTH) on insulin secretion were evaluated in three groups of dogs. Dogs were studied with glucose infusions (group I) or standard intravenous glucose tolerance tests (IVGTT) (group II) before and after the development of diet-induced hypophosphatemia. Mean serum phosphorus levels for both groups fell from 4.1 to 1.1 mg/100 ml. Animals in group I demonstrated a fall in glucose disappearance rates (Kg) from 5.3+/-0.6% min to 3.5+/-0.5% after induction of hypophosphatemia (P less than 0.001). Mean insulin response was significantly greater in the hypophosphatemic animals than in controls in this group. In group II animals, mean insulin areas obtained during the IVGTT increased from 1,426+/-223 to 2,561+/-141 muU/ml/60 min after induction of hypophosphatemia, and were unaffected by Ca++ or PTH administration. Ca++ administration, but not hypophosphatemia or PTH infusion, increased significantly the mean insulin response to tolbutamide. Secondary hyperparathyroidism was induced by dietary manipulation in four dogs (group III). Mean PTH values increased from 71.4+/-2.1 to 3,012+/-372 pg/ml (P less than 0.001). Mean insulin response to an IVGTT was similar to group III animals, but increased from 1,352+/-128 to 1,894+/-360 muU/ml/60 min after the excessive dietary phosphorus was reduced for 3 mo, and plasma phosphorus fell from 3.2+/-0.1 to 2.8+/-0.3 mg/100 ml. PTH values decreased to 647+/-53 pg/ml. The insulin response to tolbutamide was comparable to that in group II animals, but increased significantly after calcium administration. Immunoreactive insulin disappearance rates were unaffected by hypophosphatemia or diet-induced secondary hyperparathyroidism. These data demonstrate that hypophosphatemia is associated with an augmented glucose-stimulated insulin release, without any effect on tolbutamide-stimulated insulin release. Hypercalcemia produces an augmented tolbutamide-stimulated insulin release with no apparent effect on glucose-stimulated insulin release. Finally, PTH does not appear to be an insulin antagonist and has no apparent effect on either glucose- or tolbutamide-stimulated insulin release in animals with dietary-induced secondary hyperparathyroidism.
H R Harter, J V Santiago, W E Rutherford, E Slatopolsky, S Klahr
The effect of estrogen on the synthesis of plasma very low density lipoproteins (VLDL) in the cockerel was studied both in vivo and in vitro. Synthesis was studied by immunoprecipitation techniques with antisera prepared against VLDL and a major VLDL protein. VLDL were isolated from the plasma of white Leghorn hens and estrogen-treated white Leghorn cockerels by ultracentrifugal flotation at d 1.006 g/ml. After delipidation, the lipid-free proteins (apoproteins) were fractionated on Sephadex G-150 and DEAE-cellulose. Both the hen and the estrogen-treated cockerel VLDL were shown to contain an identical apoprotein with a mol wt of approximately 12,000; the apoprotein is designated fraction B. Reduction and S-carboxy-methylation of fraction B resulted in a reduction of the molecular weight by approximately one-half, indicating a dimer-monomer relationship. Antiserum prepared to the hen VLDL dimer protein gave precipitin lines of complete identity to both the hen and cockerel dimer, monomer, VLDL, apoVLDL, low density lipoproteins, and plasma; no precipitin line was formed with either hen or cockerel high density lipoproteins. After a single subcutaneous injection of diethylstilbestrol into the cockerel, plasma VLDL protein, cholesterol, and triglyceride increased, reaching a maximum 24--48 h after hormone administration. Liver slices from similarly treated animals were incubated in vitro in culture medium in the presence of [3H]lysine for 2 h. Immunoprecipitable radioactivity in VLDL increased within 2 h of diethylstilbestrol treatment and reached a maximum at 24 h; VLDL radioactivity returned to base-line levels by 72 h. At the peak of induction, newly synthesized VLDL represented 11% of the total soluble protein synthesized. When actinomycin-D (5 mg/kg) was administered simultaneously with estrogen, the induction of VLDL synthesis was totally inhibited. To determine whether the effect of estrogen on VLDL synthesis was mediated at the level of transcription, partially-purified cockerel liver mRNA was prepared from estrogen-treated animals and the mRNA activity for fraction B was quantitated in a wheat germ translation system. Fraction B mRNA was found to increase from a low base-line value to a maximum 16-24 h after estrogen treatment, returning towards baseline values at 30 h. At the peak of induction, fraction B constituted 12% of the total protein synthesized. The kinetics of induction of fraction B mRNA activity in the cell-free translation system is very similar to that observed in liver slice experiments. This finding suggests that estrogen stimulates VLDL synthesis, at least partially, by enhancing the accumulation of the mRNA for one of their major apoproteins.
L Chan, R L Jackson, B W O'Malley, A R Means
The mechanism of hydroxy fatty acid-induced secretion was investigated in perfused hamster small intestine in vivo. Sodium ricinoleate at an 8-mM concentration resulted in not only secretion of water and sodium, but an increase in intestinal clearance of inulin and a 16,000 mol wt dextran as well. A concentration of ricinoleate (2 mM) which did not affect water transport, however, did not alter intestinal permeability. Ricinoleate-induced intestinal secretion was also accompanied by increased mucosal cell exfoliation as measured by the appearance of DNA in the perfusate and by apparent injury to epithelial cell membranes as judged by measurement of sucrase activity and phospholipid in cell-free aliquots of luminal fluid. Light and electron microscopic studies demonstrated substantial mucosal architectural changes with 8 mM ricinoleate with villus shortening and injury to epithelial cells at the villus tips. In contrast, cholera enterotoxin caused marked secretion of sodium and water, presumably by a cyclic AMP mechanism, but did not alter inulin clearance or enhance DNA or sucrase appearance in the lumen. These studies suggest that at least a component of ricinoleate-induced intestinal secretion is related to structural alterations of the mucosa.
W S Cline, V Lorenzsonn, L Benz, P Bass, W A Olsen
To see whether antihistamines could prevent and reverse histamine-induced pulmonary edema and increased lung vascular permeability, we compared the effects of a 4-h intravenous infusion of 4 mug/kg per min histamine phosphate on pulmonary hemodynamics, lung lymph flow, lymph and plasma protein content, arterial blood gases, hematocrit, and lung water with the effects of an identical histamine infusion given during an infusion of diphenhydramine or metiamide on the same variables in unanesthetized sheep. Histamine caused lymph flow to increase from 6.0+/-0.5 to 27.0+/-5.5 (SEM) ml/h (P less than 0.05), lymph; plasma globulin concentration ratio to increase from 0.62+/-0.01 to 0.67+/-0.02 (P less than 0.05), left atrial pressure to fall from 1+/-1 to -3+/-1 cm H2O (P less than 0.05), and lung lymph clearance of eight protein fractions ranging from 36 to 96 A molecular radius to increase significantly. Histamine also caused increases in lung water, pulmonary vascular resistance, arterial PCO2, pH, and hematocrit, and decreases in cardiac output and arterial PO2. Diphenhydramine (3 mg/kg before histamine followed by 1.5 mg/kg per h intravenous infusion) completely prevented the histamine effect on hematocrit, lung lymph flow, lymph protein clearance, and lung water content, and reduced histamine effects on arterial blood gases and pH. 6 mg/kg diphenhydramine given at the peak histamine response caused lymph flow and lymph: plasma protein concentration ratios to fall. Metiamide (10 mg/kg per h) did not affect the histamine lymph response. We conclude that diphenhydramine can prevent histamine-induced pulmonary edema and can prevent and reverse increased lung vascular permeability caused by histamine, and that histamine effects on lung vascular permeability are H1 actions.
K L Brigham, R E Bowers, P J Owen
The occurrence of a deficiency of adenosine deaminase (ADA) activity in some patients with severe combined immunodeficiency suggests a possible relationship between the activity of ADA and the aberration of the immune system. To help delineate the function of ADA in the immune response we have examined its role in monocyte maturation. When incubated in vitro, peripheral blood monocytes transformed, within 3 days, to macrophagea as assessed by phase-contrast microscopy and an increase in the specific activity of the lysosomal enzyme acid phosphatase. The specific activity of ADA increased as much as ninefold, reaching a peak after the 1st day in culture, while the activities of other enzymes involved in the purine salvage pathway were not altered. Sucrose density ultracentrifugation of extracts prepared immediately after the isolation of monocytes revealed the presence of two forms of ADA with molecular weights of approximately 30,000 and 110,000. The increase in ADA specific activity during monocyte cultivation correlated with an increase in the activity of the smaller molecular species. A specific inhibitor ADA, erythro-9-(2-hydroxy-3-nonyl) adenine, prevented the increase in acid phosphatase activity, as well as the morphological changes associated with the monocyte maturation. These data suggest a role for ADA in monocyte to macrophage maturation. In view of the central role of macrophages in immune function, this observation may relate to the association of combined immunodeficiency and a deficiency of this enzyme.
D Fischer, M B Van der Weyden, R Snyderman, W N Kelley
IgE antibodies are usually thought to induce only immediate skin reactions. We have shown that the intradermal injection of a number of different allergens can produce a prolonged inflammatory reaction after the immediate wheal and flare in most sensitive subjects. This late inflammatory response occurs 6-12 h after challenge and is characterized by diffuse edema, erythema, pruritus, and heat. Both immediate and late responses can also be seen after passive sensitization of skin sites in nonatopic subjects. That IgE is involved in inducing the reaction was shown by the abolition of both immediate and late responses by passive transfer tests in the following experiments: (a) heating atopic serum at 56degreesC for 4 h, (b) removing IgE from the atopic serum by a solid phase anti-IgE immunoabsorbent, and (c) competitively inhibiting the binding of IgE antibodies to cells by an IgE myeloma protein. In addition, both responses were induced by affinity chromatography-purified IgE antibody, followed by antigenic challenge. Very similar lesions could also be induced by intradermal injection of Compound 48/80, thus suggesting a central role in the reaction for the mast cell or basophil. Histologically, the late phase is characterized by edema and a mixed cellular infiltration, predominantly lymphocytic but also containing eosinophils, neutrophils and basophils. Direct immunofluorescent staining did not show deposition of immunoglobulins or complement components, except IgM in 2 of 15 and C3 in 1 of 15 patients. This finding indicates that the late phase does not depend on the deposition of immune complexes. The results of the study suggest that IgE-allergen interaction on the surfaces of mast cells or on infiltrating basophils causes both immediate and late cutaneous responses.
G O Solley, G J Gleich, R E Jordon, A L Schroeter
The objects of these experiments were to determine to what extent oleic acid, removed from plasma by forearm muscles, was oxidized immediately, and to search for evidence of an intramuscular lipid pool which may be composed to triglycerides synthesized from plasma free fatty acids and which may supply substantial portions of lipid substrates for oxidation by muscle. To these ends (1-14C]oleic acid was infused at constant rate into the brachial artery of seven healthy young men at rest in the postabsorptive state. Results were: (1) muscle respiratory quotient (0.76) implied that about 80% of the oxygen consumed was for the oxidation of lipid. (2) Muscle free fatty acid uptake, had it been oxidized directly, could account for more than 100% of observed oxygen uptake. (3) There was a lag of at least 30 min before 14CO2 appeared in forearm venous blood. (4) 14CO2 release from forearm muscle tended to reach an apparent plateau after 3 h of infusion of [14C]oleic acid. (5) During the time of plateau 14CO2 release, oleic acid extracted from plasma could account for only 20% of oxygen consumption; most of the oleic acid taken up was not oxidized directly. (6) 14CO2 release persisted at a high level during the 1-3 h follow-up period after the infusion ended. (7) Neither the delay in initial appearance of 14CO2 nor its continued release after cessation of infusion was due to delay and distribution in a forearm CO2 pool, since intra-arterial infusion of NaH14CO3 in additional subjects demonstrated much more rapid distribution of 14CO2 in the forearm. Results show that most, if not all, free fatty acids taken up by resting muscle are not oxidized directly, but probably enter an intramuscular pool which has a slow turnover during resting metabolism and is the immediate source of oxidized lipid substrate.
G R Dagenais, R G Tancredi, K L Zierler
To study the antibody response to human platelet transfusions, nine thrombocytopenia patients with bone marrow failure were given 6 U (3X10(11)) of random platelet concentrates twice a week. Before transfusion, none of the patients had preexisting antibodies detectable with lymphocytotoxicity, platelet aggregation, or capillary leukoagglutination techniques. After receiving 18-78 U of platelets, they became refractory to further transfusions of random platelets and alloantibodies were detectable. Two patterns of antibody response could be identified. In three patients, the sera were not lymphocytotoxic with a panel of standard cells in which all the known HLA antigens in the first and second series were represented at least once. Yet, they caused platelet aggregation with 30, 24, and 60%, respectively, of a donor population studied. The aggregating activities were inhibited by antihuman IgG but not by antihuman IgA or antihuman IgM antiserum. The aggregating antibodies could be absorbed out with donor platelets but not lymphocytes or granulocytes. Antibodies from two of these patients aggregated platelets of their respective siblings matched for both HLA haplotypes. Transfusion of platelets from these two siblings did not increase the platelet count while platelets obtained from aggregation-negative donors did. The sera from the remaining six patients were lymphocytotoxic with 15-100% of the panel of standard cells. They also had aggregating antibodies, which could be absorbed out by both platelets and lymphocytes, suggesting that they were HLA antibodies. These data suggest that the development of platelet-specific antibodies may play an important role in the immunological rejection of isologous platelets, and should be considered in the selection of donors for patients who are refractory to platelets from random donors.
K K Wu, J S Thompson, J A Koepke, J C Hoak, R Flink
Specific localization of purified antibody against cardiac myosin has been demonstrated in areas of altered myocardial membrane permeability after experimental myocardial infarction. Intravenously administered radioiodine-labeled antimyosin was selectively localized in infarcted myocardium of seven dogs 24 h after coronary occlusion. The mean ratio (+/-SE) of antimyosin antibody in infarcted to normal myocardium in the center of the infarct was 4.2+/-0.4 for endocardial and 2.9+/-0.3 for epicardial layers. By utilizing (Fab')2 fragments of antimyosin obtained by pepsin digestion of purified antibody, the ratio of uptake was increased in eight dogs to 6.1+/-0.6 in the endocardial and 3.3+/-0.4 in the epicardial layers at the infarct center 24 h after occlusion. These ratios were further increased in the infarct center to 13.8+/-1.2 in the endocardial and 7.3+/-0.8 in the epicardial layers when eight dogs were sacrificed 72 h after coronary occlusion. The specificity of antimyosin (Fab')2 localization in infarcted myocardium was demonstrated in four dogs by simultaneous intravenous administration of 125I-labeled antimyosin (Fab')2 and 131I-labeled normal rabbit gamma globulin (Fab')2. Nonspecific trapping of normal rabbit IgG (Fab')2 was observed to be about 38% of total antimyosin (Fab')2 uptake in the central zone of infarction. Regional blood flow was related to antimyosin (Fab')2 uptake in infarcted myocardium by utilizing simultaneous administration of 85Sr-labeled microspheres. An inverse exponential relationship between antimyosin (Fab')2 uptake and regional blood flow was observed (r=0.85). The specific localization of antimyosin antibody or its (Fab')2 components in infarcted myocardium suggests a conceptually new approach to myocardial infarct localization and sizing.
B A Khaw, G A Beller, E Haber, T W Smith
Work performance on a treadmill has been evaluated in normal and iron-deficient rats. Anemia was removed as a variable by adjusting the hemoglobin of all animals to the same concentration. At a hemoglobin compatible with normal work performance, iron-deficient animals showed a marked impairment of running ability as compared to control animals. Iron therapy corrected the disability within 4 days. Concentrations of the cytochrome pigments and myoglobin, and rates of oxidative phosphorylation with pyruvate-malate, succinate, and alpha-glycerophosphate as substrates were all reduced in mitochondrial preparations from skeletal muscle of iron-deficient rats, but only the rate of phosphorylation with alpha-glycerophosphate as substrate increased significantly and in parallel with the recovery in work performance of the iron-deficient rats treated with iron dextran.
C A Finch, L R Miller, A R Inamdar, R Person, K Seiler, B Mackler
In 10 patients with classic renal tubular acidosis in whom correction of acidosis was sustained with orally administered potassium bicarbonate, renal conservation of sodium was evaluated when dietary intake of sodium was restricted to 9--13 meq/day. In five patients, renal conservation of sodium was impaired by at least one criterion of impairment. In the remaining patients, renal conservation of sodium appeared to be relatively well-maintained, but an impairment could not be excluded. In each of six patients studied during induced water diuresis, including two in whom renal conservation of sodium was not unequivocally impaired, the minimal urinary concentrations of sodium were inappropriately high and the urinary excretion rates of sodium were flow-dependent. These results provide direct evidence that an abnormality in renal transport of sodium can occur in classic renal tubular acidosis, and compel a reconsideration of the pathophysiology of disordered renal transport of sodium in this disorder. The results indicate that in at least some patients with classic renal tubular acidosis impaired renal conservation of sodium is not exclusively a reversible consequence of the renal acidification defect. These findings raise the question whether renal transport of sodium is unimpaired in any patients with classic renal tubular acidosis. In the presently studied patients, the impairment in renal conservation of sodium appeared to be in part the consequence of an impaired ability of the vasopressin-responsive segments of the distal nephron to generate and maintain appropriately steep transepithelial sodium concentration gradients.
A Sebastian, E McSherry, R C Morris Jr
The changes in levels of glycosaminoglycans (GAGs) of the intima and media of the human artery in atherosclerosis were determined by a recently introduced two-dimensional electrophoresis technique that permits direct measurments of each of these macromolecules. To identify the arterial GAGs, they were fractionated by chromatography on a DEAE-Sephadex A-25 column, and the resulting three fractions (hyaluronic acid [HA], heparan sulfate [HS], and the partially separated chondroitin sulfates B [CSB] and C [CSC]) were analyzed for their electrophoretic mobilities by this electrophoretic method, for their digestability by highly specific hydrolases (leech hyaluronidase, heparinase, and chondroitinases ABC and AC) and for their iduronic acid content. From these studies we concluded that normal and atherosclerotic human aortas contain CSB, CSC, HA, and HS. Further, we demonstrated that CSB is a hybrid consisting of approximately 40% CSA and 60% CSB and that CSC appears to be a polymer consisting essentially of glucuronic acid and N-acetylgalactosamine-6-sulfate. Classical CSA as well as chondroitin (CH) were not present in detectable amounts. In the relatively normal intima, the mean concentrations of the GAGs were found to be 4.7, 20.9, 1.3, and 5.1 mg/g of dry, defatted, decalcified tissue for CSB, CSC, HA, and HS, respectively. With the progression of atherosclerosis, there was a pronounced decrease in the total GAG content (from 32 to 18 mg) associated with a decrease in the CSC and HS levels but without a change in the HA concentrations. Of particular interest, however, was the increase in the CSB level. In the media whose total GAG content averaged approximately 20 mg, no significant changes in these GAG levels were noted with the progression of the disease except for that of CSC. These findings may be important in explaining the increased lipoprotein and collagen deposition in the diseased aorta.
R L Stevens, M Colombo, J J Gonzales, W Hollander, K Schmid
The relationship between right duct lymph flow and extravascular lung water was studied in 3 normal dogs and 15 dogs with pulmonary edema induced by alpha-naphthylthiourea (ANTU). Right duct lymph was collected in a pouch created by ligating jugular, subclavian, and brachiocephalic veins. Extravascular lung water was measured in vivo by double indicator dilution and post-mortem by weighting lungs before and after drying. Cardiac output, pulmonary artery and pulmonary artery wedge pressures, and the concentration of protein and electrolytes in plasma and right duct lymph were determined. Eight lungs were examined by light and electron microscopy. There was a direct relationship between right duct lymph flow (RDLF in milliters per hour per gram dry lung) and extravascular lung water (Qwl in milliliters per gram dry lung) which was best described by the equation RDLF=0.75-0.26 Qwl+0.03 (Qwl).2 Dogs with severe ANTU-induced edema had extensive lung capillary endothelial destruction but only mild interstitial swelling and no visible damage to type I alveolar epithelial cells. Cardiac output, pulmonary artery and wedge pressures, and protein and electrolyte concentrations did not correlate with either extravascular water or right duct flow. Thus, in ANTU-induced pulmonary edema right duct lymph flow was directly related to extravascular lung water with the highest flows occurring with severe edema. The absence of a rapid increase in lymph flow with small increases in extravascular water may be due to early sequestration of fluid in the alveolar space. Hemodynamic changes did not account for changes in lung water or lymph flow. The pulmonary interstitial factors relating increased extravascular water to lymph drainage remain to be determined.
M B Pine, P M Beach, T S Cottrell, M Scola, G M Turino
The effects of intraduodenal glycerol, fatty acid (FA) chain length and FA loads, and bile acid (BA) concentrations on pancreatic and gallbladder function were investigated in 31 healthy volunteers by a perfusion method. FA absorption rates in the duodenum and proximal jejunum were measured simultaneously. Pancreatic and gallbladder responses were augmented by increasing FA chain length and FA loads until the "maximal" secretory capacity of the pancreas and gallbladder emptying was attained. Glycerol had no effect. Raising BA concentrations above the critical micellar concentration accelerated FA absorption rates but decreased the magnitude of pancreatic and gallbladder responses to FA. Higher BA concentrations exerted an opposite effect, slowing FA absorption and increasing pancreatic and gallbladder responses. Indeed, a significant, inverse correlation was found between FA absorption and pancreatic and gallbladder responses to FA, suggesting a relationship between the length of intestine exposed to FA and the amount of cholecystokinin (and/or other neurohormonal factors) released, which stimulates pancreatic secretion and gallbladder contraction.
J R Malagelada, E P DiMagno, W H Summerskill, V L Go
The experiments reported in this paper were designed to evaluate some of the characteristics of anion transport processes during fluid absorption from superficial proximal straight tubules isolated from rabbit kidney. We measured net chemical C1- flux during fluid absorption from tubules perfused and bathed with Krebs-Ringer buffers containing 113.6 mM C1-, 10 mM acetate, and 25 mM HCO-/3 at pH 7.4; assessed the effects of carbonic anhydrase inhibitors on net fluid absorption in the presence and absence of CO2; and evaluated the influx and efflux coefficients for [14C]-acetate transport at 37degreesC, at 21degreesC, and in the presence of carbonic anhydrase inhibitors. The experimental data shown that, for this nephron segment, net C1- flux accompanies approximately 27.5% of net Na+ absorption; and net C1- absorption may be accounted for by a passive transport process, primarily diffusional in nature. Fluid absorption in this nephron segment is reduced 40-60% by carbonic anhydrase inhibitors, but only when the tubules are exposed to 95% O2-5% CO2 rather than 100% O2. Thus, it seems probably that approximately half of Na+ absorption in these tubules may be rationalized in terms of a carbonic anhydrase-dependent CO2 hydration process. In addition, there may occur in these isolated proximal tubules an acetazolamide-insensitive moiety of HCO-/3 absorption comparable to that observed for proximal tubules in vivo. Finally, we provide evidence that net efflux of luminal acetate is due to metabolic energy-dependent processes other than CO2 hydration and may, under appropriate conditions, account for approximately one-fourth of net Na+ absorption.
J A Schafer, T E Andreoli
This study reports the isolation and partial characterization of vitamin D and 25-hydroxyvitamin D binding protein (DBP), the specific transport protein for vitamin D and its 25-hydroxy metabolite in human plasma. DBP was labeled by the addition of a tracer amount of 3H-labeled 25-OH-D3 to the original plasma used for protein fractionation. Previous experiments have shown that such 25-OH-D3 added in vitro binds to the same protein normally responsible for the transport of endogenous 25-OH-D and of vitamin D. The isolation of human DBP was achieved by an extensive sequence of procedures which resulted in a final yield of only approximately 4 mg of purified DBP from a starting volume of 34 liters of plasma. Purified DBP was homogeneous in the analytical ultracentrifuge and showed a single band of protein on analytical polyacrylamide gel electrophoresis. DBP had a sedimentation constant of 3.49s and a mol wt of approximately 52,000. The molecular weight was assessed by sedimentation equilibrium analysis and also by sodium dodecyl sulfate-disc-gel electrophoresis and by gel filtration on a standardized column of Sephadex G-150. The amino acid composition of DBP was determined and was generally consistent with the estimated extinction coefficient (E1cm1% at 280 nm) of about 9.1. The isoelectric point of DBP was estimated as 4.8 from isoelectric focusing experiments. Direct study of the binding capacity of the purified DBP for added 25-OH-D3 showed that the isolated DBP had a high affinity for 25-OH-D3, with an apparent maximum binding capacity of one molecule of 25-OH-D3 per molecule of protein.
M Imawari, K Kida, D S Goodman
In purified lymphocytes from the peripheral blood of healthy human subjects who had ingested therapeutic doses of aspirin, there was a significant decrease in resting cyclic AMP levels as well as a partial inhibition of the rise in cyclic AMP with isoproterenol or prostaglandin E1. These changes were seen as early as 30 min after aspirin ingestion and did not appear to result from aspirin effects on lymphocyte recovery, purity, viability, or relative number of thymus- or bone marrow-derived lymphocytes. In contrast, the direct addition of aspirin to suspensions of purified peripheral lymphocytes did not significantly alter their cyclic AMP levels. However, an effect of aspirin could be obtained in vitro if aspirin was added to unprocessed whole blood during the dextran sedimentation phase of the cell purification. Thus the effect of aspirin on lymphocyte cyclic AMP metabolism, may be indirect, through other cells present in the peripheral blood.
D E Snider, C W Parker