Issue published January 1, 1970

R adioiodinated protein solutions, 20 nl in volume, were injected into surface proximal and distal convoluted tubules of the rat kidney. The unabsorbed fraction was collected in ureteral urine, and the percentage recovered was expressed as a function of the injection site. Recovery increased progressively from more distal sites of injection indicating absorption along the proximal tubule of human serum albumin, insulin, and ribonuclease. Fractional absorption of albumin along the proximal tubule varied from 0 to 20% of the injected load, and was similar when the injectate concentration was 20, 40, or 100 mg/100 ml. Fractional absorption along the proximal tubule of insulin and ribonuclease, smaller proteins, was 30 to 50% of the injected load, and was similar with insulin concentrations of 0.09 mg/100 ml and 40 mg/100 ml and ribonuclease concentration of 40 mg/100 ml. In addition to this constant fractional absorption of each protein in the proximal tubule, smaller amounts were absorbed when injections were made in distal convoluted tubules.

T he clearance of plasma protein-bound heme, its sites of removal, and the reutilization of hemeiron were studied by radioisotopic techniques in normal human subjects and in patients with intravascular hemolysis.In normal subjects, injected heme-⁵⁹Fe was bound immediately by albumin and the β₁-globulin, hemopexin. Its clearance from the plasma was descr bed by a single exponential equation, and the half-life in plasma was 7-8 hr. Removal was largely by the liver. Iron reutilization began promptly, and half the injected heme-iron was incorporated into circulating red cells within one cell life-span.In patients with intravascular hemolysis, hemopexin was depleted, and injected heme was bound solely to albumin. Plasma clearance was described by a double exponential equation of the form: y = Ae^-k₁t + Be^-k₂t. The half-lives of the two components averaged 3.9 and 22.2 hr, respectively. Removal was by the liver in at least some of the patients, and iron reutilization was variable, depending on the state of body iron stores. When hemopex'n was depleted in a normal subject by repeated heme injection, clearance mimicked that observed in the patients.

T he hyperviscosity syndrome is an uncommon complication in IgG myeloma. Its occurrence has been ascribed to the presence in the serum of high molecular weight polymers of the IgG proteins. Three patients with IgG myeloma and the clinical hyperviscosity syndrome were investigated, none of whom had IgG polymers in the serum by analytical ultracentrifugation. Relative serum viscosity in these patients ranged from 10 to 17.4 (normal 1.4-1.8). The total serum proteins ranged from 14 to 19 g/100 ml of which 10 to 17 g/100 ml was IgG globulin. Physicochemical studies of two of the isolated myeloma proteins indicated that they were of normal molecular weight (near 158,000 and 162,000). Protein Ca had a normal molecular radius (52.2 A) and configuration, (intrinsic viscosity of 5.5 cc/g, frictional ratio 1.48), but was present in very high concentration in the serum. Protein Pur had an increased molecular radius (58.2 A) and was asymmetrical (intrinsic viscosity 10.2 cc/g, frictional ratio 1.63). These results indicate that the concentration and molecular configuration of the myeloma protein are important determinants of the presence or absence of the hyperviscosity syndrome.

T he effect of water restriction and ammonium chloride acidosis on the course of Escherichia coli pyelonephritis was determined in the nonobstructed kidney of the rat. To alter the chemical composition of the renal medulla, water intake was reduced in rats to one-half the normal daily intake. Water restriction increased the incidence of coliform pyelonephritis. Systemic acidosis, produced by giving a 300 mM solution of ammonium chloride, increased urinary osmolality to values comparable to water restriction and also predisposed to pyelonephritis. However, when rats were fed the same solution of ammonium chloride but were allowed access to tap water ad lib., urinary osmolality values were comparable to those observed in normal animals, and susceptibility to pyelonephritis was reduced or eliminated despite a degree of systemic acidosis similar to that observed in rats fed ammonium chloride solution without access to tap water. These results suggest that water diuresis may overcome the inactivation of complement produced by ammonium chloride acidosis and that renal medullary hypertonicity, produced by either water restriction or ammonium chloride acidosis, is a major determinant of this tissue's unique susceptibility to infection.

T he metabolism of radioactive testosterone simultaneously administered intravenously and either orally or percutaneously has been studied in seven patients with the syndrome of testicular feminization and compared with that of normal males and females. This investigation was carried out in order to determine the relative contribution to urinary 17-oxo and 17β-hydroxy androstane steroids of labeled testosterone, according to its mode of administration. In normal males the yields of urinary 5α-androstane-3α,17β-diol (androstanediol) originating from either an intravenous or a percutaneous dose of testosterone were respectively 3 and 6 times higher than those arising from an oral dose which perfuses the liver directly. These data indicate that in normal males, testosterone might be 5α-hydrogenated outside the liver. By contrast in patient with feminizing testes, because the contribution to androstanediol of radioactive testosterone is identical whatever its mode of administration, the extrahepatic 5α-reduction of this substrate seems very unlikely.The metabolic abnormalities observed in patients with testicular feminization syndrome may be reproduced in normal males by estrogen treatment. Nevertheless, the sensitivity of the patients to estrogen seems to be 10 times greater than that of normal males. This sensitivity was appreciated from the reduction of radioactive testosterone intravenously injected to urinary 17β-hydroxy-5α-androstan-3-one and androstanediol and also from the level of plasma binding for testosterone. This level was significantly higher (P < 0.05) in patients with feminizing testes than in normal males. The level increased dramatically after administration of a low dose of estrogen whereas this effect was not observed in normal males under the same experimental conditions.In light of these results the defect of extrahepatic 5α-reduction of testosterone observed in patients with feminizing testes does not necessarily reflect an enzymatic impairment but might be related to an abnormal synthesis of plasma binding protein(s) under the effect of circulating estrogens so that an abnormally small amount of unbound testosterone may be available in target cells for 5α-reduction.

I n order to investigate the electrophysiology of the human internal anal sphincter and two current concepts of sphincter function, simultaneous manometric and electrical recordings were made from circular smooth muscle of the internal anal sphincter in the resting state and during reflexly induced sphincter relaxation. Three groups were studied: seven normal subjects, 25 patients with functional bowel disease, and seven patients with external sphincter paralysis due to spinal cord lesions. In the resting state slow waves of alternating potential (basic electrical rhythm or BER) were recorded in all subjects. Two types of waves were present, a constant sinusoidal pattern or a spindleshaped pattern. Either pattern was consistent for a given individual. Frequency of BER in the internal sphincter was higher than that recorded in any other gastrointestinal muscle. Our findings indicate that the BER recorded from the internal anal sphincter originates in this muscle. This activity may represent a specialized feature of sphincteric muscle since BER cannot be recorded from isolated nonsphincteric circular muscle.Reproduction of the two patterns of BER by an electronic model suggests that BER, as recorded by this technique, results from a summation of a number of electrically active cells in contact with the recording electrodes. Inhibition of BER occurred when sphincter relaxation was reflexly induced by rectal distension. Both inhibition of BER and degree of sphincter relaxation were proportional to the strength of rectal stimulation, suggesting that strength of stimulus determines the number of active cells which are inhibited.The associations of high frequency of BER with high resting pressure, and of inhibition of BER with sphincter relaxation suggests that maintenance of sphincter tone is an active process that is governed by BER.

T he synthesis of immunoglobulins by cells infiltrating the labial salivary glands has been studied by radioimmunoelectrophoresis in 20 patients with Sjögren's syndrome (SS) and in 14 control patients with related disorders. The patients with SS were producing significantly greater quantities of IgG, IgM, and IgA. Synthesis of IgG and IgM correlated with the degree of lymphoid infiltration but not with serum immunoglobulin concentration. Patients with SS and rheumatoid arthritis (RA) showed greater synthesis of IgG and IgM than those with uncomplicated RA. The only extensive lymphoid infiltration was seen in patients with SS. One patient with SS and primary macroglobulinemia was synthesizing the paraprotein in the lip biopsy as well as in the bone marrow. These results establish the immunologic competence of the infiltrating lymphoid cells and suggest their origin from an extrasalivary source.

A cute myocardial infarction causes depression of left ventricular function, but the capacity of the ventricle to recover from such an injury remains unknown. This problem was explored by measuring left ventricular function in eight intact conscious dogs before, 1 hr after, and again 6-8 days after myocardial infarction. Acute myocardial infarction was produced using a technique which entails gradual inflation over an average period of 1 hr of a balloon cuff previously implanted around the left anterior descending coronary artery. Occurrence of anterior wall infarction was detected electrocardiographically and later confirmed by postmortem examination. Left ventricular function was evaluated from the relationship between left ventricular developed pressure (left ventricular peak systolic pressure minus left ventricular end-diastolic pressure) and left ventricular end-diastolic pressure during transient aortic occlusion with a balloon catheter. Left ventricular function curves were obtained by plotting left ventricular-developed pressure at increasing left ventricular end-diastolic pressures up to 50 mm Hg. Acute myocardial infarction caused marked depression of left ventricular function measured 1 hr after onset of infarction, but 1 wk later all eight animals showed improvement with return of function toward the control levels. A small but significant descending limb was noted at left ventricular end-diastolic pressures above 35 mm Hg. Quantitatively, the descending limb was similar before, 1 hr after, and 1 wk after myocardial infarction. Hemodynamic data revealed evidence of left ventricular failure in all animals, but variability in individual hemodynamic parameters was noted. The data indicate that the marked depression of left ventricular function observed immediately after experimental acute myocardial infarction undergoes considerable resolution within 1 wk, but that functional recovery remains incomplete.

P reparations of right ventricular papillary muscle and false tendon (Purkinje fiber) were obtained from dog hearts, placed in a bath perfused with Tyrode solution, and observed both under control conditions and during exposure to lidocaine in concentrations from 1 × 10^-7 to 5 × 10^-4 mole/liter. Transmembrane voltages were recorded from both ventricular muscle (VM) and Purkinje fibers (PF) of spontaneously beating and electrically driven preparations. Low concentrations (1 × 10^-6 and 1 × 10^-5 mole/liter) attenuated or abolished phase 4 (diastolic) depolarization and spontaneous firing in PF without decreasing their diastolic excitability. Concentrations of 1 × 10^-5 mole/liter produced maximal shortening of both action potential duration (APD) and effective refractory period (ERP) and made the ERP long relative to APD; the latter alteration was more prominent in VM. At concentrations ≤ 1 × 10^-5 mole/liter, lidocaine either caused a slight increase or no change in peak maximum rate of phase 0 depolarization (V_max) and membrane responsiveness, the relationship between transmembrane activation voltage (MAV) and V_max of the resultant action potential; these concentrations had no significant effect on resting potential (RP) in VM, maximal diastolic transmembrane voltage (DTMV_max) in PF, or action potential amplitude in either fiber type.High (toxic) concentrations (≥ 1 × 10^-4 mole/liter) did not cause further shortening of APD or ERP in either VM or PF but did produce a decrease in peak V_max of phase 0 and membrane responsiveness. In most cases, these concentrations also caused a decrease in RP or DTMV_max and action potential amplitude, with progression to bizarre action potential depolarization and inexcitability. These properties of lidocaine are strikingly different from those of quinidine or procaine amide. The mechanisms responsible for lidocaine's in vivo antiarrhythmic action are discussed.

A method has been devised which is free of many of the shortcomings of serial epithyroid counting techniques as an index of the rate of thyroid hormone secretion. By means of this method, the effect of treatment with Lugol's iodine on the rate of thyroidal secretion of thyroxine (T₄) has been assessed in eight patients with thyrotoxicosis due to diffuse or multinodular goiter. The technique involves administration of a tracer dose of inorganic ¹²⁵I followed several days later by an intravenous tracer dose of ¹³¹I-labeled T₄. Serial observations of serum protein-bound (PB) ¹²⁵I and ¹³¹I are accompanied by frequent measurements of endogenous serum T₄ (T₄-¹²⁷I) concentration. Regardless of whether or not its administration was anteceded and accompanied by the administration of large doses of methimazole, iodine induced a rapid decrease in serum T₄-¹²⁷I concentration which could not be explained by an increase in the peripheral turnover of T₄, as judged from the metabolism of the ¹³¹I-labeled hormone. Hence, the decreased serum T₄ concentration could only have resulted from decreased secretion of the hormone by the gland. Analyses of specific activity relationships between PB¹²⁵I or T₄-¹²⁷I and PB¹³¹I made possible estimations of the extent to which iodine had decreased the rate of secretion of T₄. From such analysis, and in view of other considerations, it is concluded that the rapid decrease in T₄ secretion induced by iodine is not the result of an acute, sustained inhibition of T₄ synthesis, but rather results from an abrupt decrease in the fractional rate of thyroidal T₄ release.

T he importance of antigen site density has been studied by means of a model passive hemagglutination system using human red cells coupled with sulfanilic acid groups. Relative site numbers were estimated from the covalent linkage of sulfanilic acid-³⁵S to red cell membrane protein and the effective antigen site number was determined with ¹²⁵I-labeled rabbit IgG antisulfanilic acid.Cells which had fewer than 20,000 antigen sites per cell were not agglutinated. As greater numbers of sulfanilic groups were coupled to the red cells, the agglutination titers increased to maximum values with red fanilic groups were coupled to the red cells, the agglutination titers of purified IgM antibody were 10-20 times greater than IgG antibody when preparations with the same protein concentration were compared, but this difference was not noted when IgG antibody was measured by antiglobulin reactions.These findings emphasize the need to consider differences in antigen site density when comparing blood group systems. They are consistent with the hypothesis that those blood group antigens which have a very low site number will not be detected by IgG antibodies in saline hemagglutination determinations.

T he specificity and mechanism of altered intestinal transport of diabetic rats was studied with an everted ring technique. Increased intracellular accumulation of amino acids, as well as galactose and 3-O-methylglucose, was demonstrated in diabetes. The greater accumulation by diabetic intestine could not be attributed to a direct effect of the agent used to induce diabetes or to an alteration in food consumption. Although the changes were related to the severity of diabetes and could be reversed with treatment with insulin, they could not be modified by addition of insulin in vitro. The changes could not be induced in control intestine either with hyperglycemia from glucose infusion or preincubation with glucose in vitro.Although the higher concentration gradients of amino acids, galactose, and 3-O-methylglucose could result from increased energy utilization by diabetic intestine, an alteration of cell membrane function, as well, is suggested by the demonstration with kinetic studies of increased influx with an increase in V_max.

A cute exposures to hemp dust, in healthy subjects as well as hemp workers with byssinosis, resulted in two different responses. Men with symptoms (chest tightness, coughing, and wheezing) after exposure showed decreases of forced expiratory volumes (FEV_1.0), flow rates on maximum expiratory flow-volume (MEFV) curves, and of vital capacity (VC), while airway conductance (Gaw: TGV ratio) did not decrease significantly (“flow rate response”). Men without symptoms after exposure showed no changes of VC, FEV_1.0, and MEFV curves, but had a significantly decreased airway conductance (“conductance response”). The flow rate response is attributed to a pharmacological bronchoconstrictor effect of hemp dust on small airways, the conductance response to a mechanical or reflex effect of hemp dust on large airways. Both responses were abolished by a bronchodilator drug. The type of response reflects a difference between individuals and is not related to age, smoking habits, or prior exposure history. Men with normal control function data had either a flow rate or a conductance response. All men with abnormal control data had a flow rate response.Long-term hemp dust exposure causes irreversible obstructive lung disease, in particular among men who respond to acute dust exposure with symptoms and flow rate decreases. The detection of this response, with FEV_1.0 measurements and MEFV curves, is essential in the study of byssinosis. Decreases of airway conductance after dust exposure have no consistent relation to the development of clinical symptoms. The relative value of measurements of maximum expiratory flow rates and of airway conductance in other lung diseases needs to be reassessed.

T he latent capacity of human platelets for oxidizing several important energy-yielding substrates has been revealed by hypoosmolaric incubation conditions.The data show that the human platelet has a considerable capacity to oxidize both glucose and long-chain fatty acids. Long-chain fatty acids appear to rank favorably with glucose as a potential energy substrate. In a number of mammalian tissues, (—)-carnitine serves to regulate the rate at which long-chain fatty acids are oxidized. Evidence was obtained which suggests that (—)-carnitine functions in a similar role in the platelet.After storage of human platelets at 4°C for 24 hr, the oxidative capacity for glucose was reduced by approximately 25% and for long-chain fatty acids by almost 50%. Investigation of the component parts of the metabolic pathways indicated that a marked decrease in the capacity of the Krebs cycle could be responsible for the decrement in energy substrate oxidation.

T he metabolic fate of ¹⁴C-labeled fatty acids which have been incubated with human platelets, has been traced. The following has been shown. (a) Intact platelets have a considerable capacity to oxidize fatty acids. (b) When tracer amounts of four of the most common fatty acids in normal plasma were incubated with platelets, each showed a distinctive pattern of uptake among neutral lipids and phospholipids. With regard to the latter, it was shown that these distribution patterns were, in most cases, similar to those of the fatty acids found in natural platelet phospholipids. (c) By increasing the time of incubation or the amount of added oleic acid, the distribution of oleic acid uptake between lecithin and other phosphoglycerides was altered so that a larger share was incorporated into the latter. (d) The effects of added lysolecithin or lysoethanolamine phosphoglycerides on oleic acid incorporation into platelet phosphoglycerides are quite variable. At low concentrations, added lysolecithin functions chiefly as a reaction partner for oleic acid. Added adenosine triphosphate and CoASH augment the incorporation of oleic acid into lecithin over a wide range of added lysolecithin (12.5-500 μmoles/liter). At higher concentrations of added lysolecithin, in the absence of ATP and CoASH, oleic acid incorporation into lecithin is considerably reduced. Also, added lysolecithin and lysoethanolamine phosphoglycerides, in the absence of ATP and CoASH, are able, at certain concentrations, to stimulate oleic acid incorporation into all except the serine phosphoglycerides. (e) Platelets appear to have a de novo pathway for renewal of lecithin.

W ashed human platelets are capable of depositing 1-4 as well as probable 1-6 glucosyl linkages onto preexistent glycogen primer. They are also capable of degrading (glycogenolysis) newly synthesized 1-4 as well as probable 1-6 glucosyl linkages. A higher rate of glycogen synthesis was found in platelet suspensions containing lower concentrations of platelets. This was shown to result from decreased glycogen degradation and consequent increased residual glycogen primer in low platelet suspensions. The increased glycogen content of low platelet suspensions was not a result of platelet washing, removal of platelets from plasma, or release of platelet metabolites into the media. The enzyme glycogen synthetase was found to be present at a rate of 5.2 μmoles of uridine diphosphate (UDP) glucose incorporated into glycogen per gram platelets per hour at 37°C. The K_m for UDP glucose was 6.6 mmoles/liter. At optimum concentration of glucose 6-phosphate, the K_m was reduced 4.6 fold and V_max was increased 4.3-fold.Human platelets contain the glyconeogenic pathway. They incorporate pyruvate-¹⁴C and citrate-¹⁴C into platelet glycogen and contain an apparent fructose-1,6-diphosphatase. The apparent fructose-1,6-diphosphatase was activated by adenosine monophosphate (AMP) and adenosine diphosphate (ADP), inhibited by adenosine triphosphate (ATP), and shown to be rate limiting for glyconeogenesis at physiologic concentration of adenine nucleotide.

T he class of immunoglobulin M (IgM) characterized by high molecular weight proteins with a sedimentation coefficient of 19S, includes a smaller molecular form with an S_20,[unk] of approximately 7. The synthetic origin of the 7S IgM was investigated by biosynthetic studies on bone marrow cells from three patients with macroglobulinemia whose sera contained 7S IgM and 19S IgM. Labeled 7S IgM and 19S IgM were identified in extracellular culture fluids by radioimmunochemical techniques. The separation of the two molecular forms of IgM by density-gradient ultracentrifugation of the culture fluids before radioimmunochemical analyses permitted the identification of both the labeled 7S IgM and 19S IgM. One patient's serum contained two separate and distinct 19S IgM proteins as well as 7S IgM. The use of specific isolated carrier IgM proteins permitted the radioimmunochemical detection of labeled 7S IgM and both 19S IgM proteins. The introduction of cycloheximide into a culture system effects the cessation of protein synthesis. The analyses of culture fluids harvested at timed intervals after the addition of cycloheximide revealed not only the stability of 19S IgM to intracellular proteolysis, but also provided evidence for a possible precursor-product relationship between the 7S IgM and the 19S IgM. The demonstration that the labeled 7S IgM is neither an in vitro breakdown product of 19S IgM nor a resultant of 19S IgM intracellular catabolism substantiated the synthetic origin of 7S IgM in human sera.

T he ability of peripheral blood lymphocytes to respond to phytohemagglutinin (PHA) in vitro was studied in patients with Down's syndrome. The response was measured by the increase in DNA polymerase activity and the rate of incorporation of tritiated thymidine by the cultured lymphocytes. These activities were significantly lower in PHA-stimulated lymphocytes from patients with Down's syndrome compared with age- and sex-matched, mentally retarded patients without Down's syndrome from the same institution and the normal healthy volunteers. The impairment in response to PHA does not seem to be related to the presence of Australia antigen in patients with Down's syndrome or to institutionalization itself. In contrast to DNA polymerase activity and thymidine-³H uptake, there was no significant difference in the percentage of blast transformation in the three groups studied. The poor response of the lymphocytes from patients with Down's syndrome to a mitogenic stimulus could reflect an impairment of cellular immune functions in these patients which may be one of the factors contributing to the vulnerability of these patients to repeated or persistent infections.

P ulmonary blood volume was determined by the radiocardiographic technique in 49 patients coming to cardiac catheterization. Since this method has not been directly compared with the more commonly used double injection of dye. 25 comparisons were carried out in 13 patients of the series. Agreement was good over a range of 4.5-21.1 heart cycles since there was no statistically significant difference between transit time values measured by the two methods.The relation of pulmonary blood volume to other hemodynamic factors in these 49 patients, with and without cardiac or pulmonary disease, was evaluated by means of multiple regression analysis. The analysis carried out for mean transit time indicates that this parameter varies predominately with flow. Pulmonary blood volume, in this series of resting recumbent individuals, varies to a significant degree only with total blood volume and with pulmonary venous pressure. No parameters of vascular distensibility, such as pulmonary vascular resistance, were found to affect the volume of blood in the lungs.The fact that variations in pulmonary blood volume among the subjects could be described by a multiple regression equation linear with respect to total blood volume and pulmonary venous pressure indicates that these variations are the result of passive distention of components of the vascular bed.

T he site, nature, magnitude, and duration of fluid and electrolyte loss into the small intestine during the acute and recovery phase of human cholera was defined in 27 Indian patients. 11 subjects without cholera served as controls. The marker perfusion technique employed was shown, in preliminary experiments, to measure accurately jejunal and ileal fluid and electrolyte transmucosal transport rates under conditions of cholera diarrhea. Fluid loss into the lumen occurred from jejunal and ileal mucosa. The fluid was isotonic in both regions. Bicarbonate concentration was significantly higher in ileal than jejunal fluid during all phases of the disease. Bicarbonate concentration in both regions was significantly higher in acute cholera than during convalescence. Fluid loss into the intestinal lumen ranged from 0.07 to 10.9 ml/hr per cm. Losses were significantly greater from jejunum than ileum. Net ileal absorption was recorded in five of 10 acute cholera studies. During the acute phase of the disease, net jejunal fluid transport showed a positive correlation with fasting intestinal flow rate and stool output. Stool output was also positively correlated with jejunal fasting intestinal flow rates. Recovery of normal fluid and electrolyte absorptive function was usually complete in both jejunum and ileum by the sixth day after admission.These findings in human cholera validate the animal models of choleraic diarrhea and suggest that similar measurements of small intestinal secretory function in other nonspecific diarrheal diseases using the marker perfusion technique may be rewarding.