This study was performed to investigate whether the malabsorption of fat in the blind loop syndrome is due to the presence of free bile acids or to a deficiency of conjugated bile salts produced by bacterial degradation of normal bile salts, as well as to learn something of the mechanisms by which bile salts might regulate fat absorption. In the everted gut sac of the rat in vitro, conjugated bile salts were necessary for maximal rates of fatty acid esterification to triglycerides, whereas free bile acids inhibited this process even in the presence of physiologically normal or higher concentrations of conjugated bile salts. In contrast, in the living animal the addition of similar or higher concentrations of free bile acids to infusions of fatty acids in taurocholate micellar solutions produced no reduction in the amount of fatty acid absorbed into lymph or the amount of fatty acid esterified into lymph triglyceride. Both in vitro and in the living animal, reduction in the conjugated bile salt concentration reduced both the rate of fatty acid uptake by the intestine and the esterification into triglycerides. It is concluded that the steatorrhea of the blind loop syndrome or other conditions in which upper intestinal stasis allows bacterial proliferation is not due to presence of increased gut luminal concentrations of free bile acids, but rather is a consequence of lowered concentrations of conjugated bile salts.
Michael L. Clark, Heidemarie C. Lanz, John R. Senior
The nature of the disappearance of radioiodinated human growth hormone (HGH) from plasma has been reexamined. The metabolic clearance rate (MCR) was determined both from single injection and constant infusion studies. After single injection of highly purified radioiodinated HGH, the disappearance curve remained multiexponential during the period of study (4 hr). The shape of the curve was independent of the growth hormone preparation used. Similar disappearance curves were obtained with unlabeled HGH.
Donald P. Cameron, Henry G. Burger, Kevin J. Catt, Alison Doig
Diaphragm activity during carbon dioxide breathing and total chest compliance during diaphragm relaxation were measured in eight obese subjects: four with normal blood gases and four with hypercapnia and hypoxemia. Whereas there were no significant differences in the values of total chest compliance between the two groups, there were marked differences in diaphragm activity. The increase in integrated electrical activity in the diaphragm, per millimeter increment in carbon dioxide tension in the arterial blood, averaged 66 units (range: 48-90) in the obese-normal subjects and 17 units (range: 12-22) in the obese-hypoventilation subjects. These results suggest that an incapacity to increase the activity in the respiratory muscles, to levels necessary to overcome the load caused by obesity, plays a major role in the genesis of respiratory failure in obese subjects.
Ruy V. Lourenço
Incorporation of 75selenomethionine (75SeM) has been used to study platelet production in rabbits. Radioactivity of platelets was low after the intravenous administration of 75SeM and rose to a maximum approximately 3 days after administration. Platelet radioactivity was independent of concurrent plasma levels. The life span of rabbit platelets, as estimated with this technique, was 4-5 days. In vivo reutilization of 75SeM previously incorporated into plasma proteins was not detected. In vitro incorporation of 75SeM by platelets in platelet-rich plasma was not demonstrated.
Bruce L. Evatt, Jack Levin
An abnormal unstable hemoglobin, hemoglobin Philly, was found in three members of a family, each of whom had evidence of a chronic hemolytic state. The presence of the mutant protein was suggested by the rapid appearance of inclusion bodies upon incubation of erythrocytes with brilliant cresyl blue and by the increased heat precipitability of the hemoglobin. However, no abnormal hemoglobin could be demonstrated by electrophoresis or column chromatography. Sulfhydryl titration of the hemolysates with p-mercuribenzoate indicated that there was an average of four reactive sulfhydryl groups per hemoglobin molecule instead of the usual two. The total number of hemoglobin sulfhydryl groups was normal; six groups were measured when denatured globin was reacted with 5,5′-dithiobis[2-nitrobenzoic acid]. This indicated that the increased sulfhydryl reactivity was due to an increased availability to p-mercuribenzoate of the usually unreactive hemoglobin cysteines at β112 and α104. After treatment for ½ hr with 4-5 moles of p-mercuribenzoate per mole of hemoglobin, electrophoresis revealed that 30-35% of the hemoglobin had been dissociated into α- and β-chains. Normal hemolysates revealed negligible splitting after 72 hr of similar treatment. The α- and β-chains of hemoglobin Philly were separated from the unsplit hemoglobin A by carboxymethyl cellulose chromatography. Fingerprint and amino acid analyses revealed that tyrosine β35 was replaced by phenylalanine. In hemoglobin Philly there is loss of the normal hydrogen bond between the tyrosine hydroxyl group and the carboxyl group of aspartic acid α126 at the α1β1 contact. This shifts the equilibrium from hemoglobin tetramers toward monomers, exposing the β112 and α104 cysteines. In the cell, precipitation of the unstable monomers may contribute to erythrocyte destruction.
Ronald F. Rieder, Frank A. Oski, J. B. Clegg
Toxemia was induced in 13 of 20 pregnant ewes by the stress of a change in environment and food deprivation late in pregnancy. Of the toxemic ewes, eight developed prominent neurological findings with convulsions, motor weakness, and blindness, whereas five ewes developed azotemia without neurological signs. Proteinuria and azotemia occurred in all but one of the toxemic animals. Seven animals did not develop clinical or laboratory evidence of toxemia. Hypertension did not occur with the onset of toxemia but all toxemic animals showed glomerular changes by light and electron microscopy. These abnormalities, which were similar to those seen in human preeclampsia, included endothelial cell swelling, focal reduplication of the basement membrane, and fusion of the epithelial cell foot processes. The toxemia could not be attributed to changes in hematocrit, plasma glucose, Na, Cl, CO2, K, Ca, fibrinogen, arterial pH, lactate, or pyruvate concentrations. Cardiac output fell only in ewes with prominent neurological signs. Plasma renin rose strikingly in animals developing toxemia, without change in substrate concentration. In contrast to human and other species, sheep uterus and amniotic fluid contained no detectable quantities of renin.
Thomas F. Ferris, Peter B. Herdson, Michael S. Dunnill, M. Radcliffe Lee
Chromatographic, ultracentrifugal, and related studies of the fibrinogen of a patient with a congenital disorder of fibrinogen (fibrinogen “Baltimore” have provided evidence of structural differences from normal.
M. W. Mosesson, E. A. Beck
The mechanism responsible for the hyperdynamic circulatory state in hyperthyroidism has not been defined. Although certain cardiac manifestations resemble those caused by excessive adrenergic stimulation, recent evidence suggests that thyroid hormone exerts an effect on the heart that is independent of the adrenergic system. Since the inotropic and chronotropic effects of norepinephrine appear to be mediated by activation of adenyl cyclase, the possibility that thyroxine and triiodothyronine are also capable of activating adenyl cyclase was examined in the particulate fraction of cat heart homogenates.
Gerald S. Levey, Stephen E. Epstein
Measurements of serum thyrotropin (TSH) concentrations were conducted in maternal and fetal blood during labor and delivery and the early postnatal and neonatal periods. Mean TSH concentration was significantly higher in cord blood (9.5 μU/ml) than maternal blood (3.9 μU/ml), a finding suggesting a fetal-maternal TSH gradient at term. Serum TSH concentration in the newborn increased rapidly to mean levels of 60 μU/ml at 10 min and 86 μU/ml at 30 min of age. Between 30 min and 3-4 hr serum levels decreased rapidly, then fell more gradually to a mean concentration of 13 μU/ml at 48 hr. The half-time of the decrease in serum TSH concentration between 30 and 90 min was 77 min, a value slightly greater than the half-time of disappearance of radioiodinated TSH measured in adults. This indicates that the early high rate of TSH secretion in the newborn ceases by 30 min, and that the rapid rise and fall in serum TSH concentrations may represent release of stored pituitary TSH. A more chronic TSH hypersecretion persisted throughout the first 24-48 hr of extrauterine life. Measurements of serum PBI concentrations were conducted in a separate group of maternal and cord blood samples and in the newborn infants during the first 48 hr of extrauterine life to relate the TSH and serum hormonal iodine concentration changes. Serum protein-bound iodine (PBI) concentrations were similar in maternal and cord blood, increased significantly by 4 hr of age in the newborn, and peaked at about 24 hr, presumably in response to the TSH hypersecretion. The pattern of TSH hypersecretion was similar in infants delivered vaginally and by caesarean section. Maternal serum TSH concentrations were stable throughout the perinatal period. Warming the infants at 99-103°F during the first 3 hr of life did not prevent the early, acute release of thyrotropin. Cooling of warm infants at room temperature (72-78°F) between 3 and 4 hr resulted in a decrease in mean rectal temperature of 3.3°F and produced a significant increment in serum TSH concentration. These data suggest that the mechanism of the early, acute release of thyrotropin in the newborn may involve a potent stimulus other than cooling. However, the increase in serum TSH stimulated by delayed (3-4 hr) cooling indicates that neonatal hyperthyroxinemia is, at least, augmented by extrauterine cooling. Thus, cold exposure is capable of increasing TSH secretion in humans.
D. A. Fisher, W. D. Odell
Bilirubin metabolism was studied in dog and monkey fetuses. Bilirubin-3H was administered to fetal animals in utero by prolonged intravenous infusion. Fetal plasma disappearance, hepatic uptake, biliary excretion, and placental transfer of bilirubin-3H were measured.
Ralph B. Bernstein, Miles J. Novy, George J. Piasecki, Roger Lester, Benjamin T. Jackson
With the advent of electronic computers that operate in the time-sharing mode, it has become possible to develop an automated system that can assist a physician in solving clinical problems. In the present study a teletype terminal has been linked to a time-sharing computer which has been programmed to evaluate clinical and laboratory information concerning patients with acid-base disorders. The program checks the data for evidence of internal consistency and requests additional information as needed to solve the acid-base aspects of the clinical problem. If sufficient information is provided, the program generates an evaluation note designed to review with the physician the pathophysiology of the disorder and to assist him in its management. If the input data are incomplete, the program draws the most useful conclusions possible based on the data provided, specifies the limitations which pertain to these conclusions, suggests further studies designed to circumvent these limitations, and while awaiting the results, suggests appropriate interim therapeutic measures. The time required to enter a patient's data and to print the evaluation note is approximately 4 min; the cost is comparable to that of many laboratory tests.
Howard L. Bleich
Prospective studies in a population of American Indian children during an outbreak of acute nephritis associated with the Type 49 Group A streptococcus permitted a comparison of attack rates of renal complications after infection at different sites and at different ages. Acute nephritis or unexplained hematuria developed in 10 of 42 children (23.8%) with Type 49 streptococcal skin infection, in 2 of 44 (4.5%) with Type 49 throat infection, and in 3 of 16 (18.8%) with simultaneous Type 49 infection at both sites. The higher attack rate of nephritis and hematuria in children with pyoderma indicates that skin lesions played a direct and quantitatively greater role than respiratory infection in the pathogenesis of acute nephritis during this outbreak. Skin infections with the Type 49 strain were followed by evidence of renal complications more often in children younger than 6.5 yr (9 of 21 or 43%) than in older children (1 of 21 or 5%). Attack rates of renal complications after Type 49 skin infection were approximately equal in males and females.
Bascom F. Anthony, Edward L. Kaplan, Lewis W. Wannamaker, Franklin W. Briese, S. Stephen Chapman
A physical model of calcium absorption was developed from analysis of data obtained on 23 subjects, including 13 patients having a variety of abnormalities of calcium metabolism. The model was tested and found consistent in all subjects studied. This technique provides a quantitative description of the rate of entry of oral dose of 47Ca into the circulation as a function of time by analysis of serum or forearm radioactivity in response to intravenous and oral administration of 47Ca. The kinetics of the absorption process as proposed by the model are characterized by an initial delay phase of 15-20 min, by a maximal rate of absorption at 40-60 min after ingestion, and by 95% completion of the absorption within 2½ hr. Partial identification of the physiological counterparts of the model was possible by introduction of the isotope at various levels of the gut. Although the region of the duodenum was found to have the greatest rate of absorption per unit length in normal subjects, it was least responsive to stimulation by parathyroid hormone and suppression by calcium loading. Furthermore, the response of the gut to parathyroid hormone was delayed, whereas the suppression of absorption by intravenous or oral calcium loading was rapid and dramatic. The implications of these observations are discussed.
Stanley J. Birge, William A. Peck, Mones Berman, G. Donald Whedon
Short-circuit current and transepithelial potential difference were measured in toad hemibladders mounted as sacs on glass cannulae. When sac volume was changed by adding or removing fluid, short circuit current responded by increasing or decreasing during the ensuing half-hour. The time course of the response and its magnitude indicated that it was not artefactual. Furthermore, net sodium flux responded similarly. Sac volume, and thus bladder surface area, could be varied from 0.03 to 0.4 cm2/mg wet weight. The mean response to either decreases or increases was 10 μA/cm2. Everted hemibladders, however, responded less. Neither hydrostatic pressure, nor increased chloride conductance, nor increased access of oxygen or glucose to the mucosa was responsible for the response. Tissue conductance did vary markedly with volume, and may have played a role, but sodium conductance did not vary with volume in a consistent manner. The results indicate the existence of an intrinsic mechanism in this tissue which alters sodium transport in response to stretch.
The characteristics of degradation of reticulocyte ribonucleic acid (RNA) and ribosomes were studied in a whole erythroid cell lysate system. The process followed Michaelis-Menten kinetics, and indicated that RNA degradation in the erythroid cell is mediated by an enzyme previously isolated from reticulocyte hemolysates. Erythroid cell RNase activity had a temperature optimum of 50°C, a pH optimum of 7.0, was not energy dependent, was heat labile at physiologic pH, and was inhibited by Mg++, Ca++, and exposure to bentonite and deoxycholate. Free sulfhydryl groups were not essential for RNase activity. Of the substrates occurring naturally within the erythroid cell, isolated ribosomal RNA was most susceptible to the action of the enzyme, intact ribosomes least susceptible, and transfer RNA intermediate between them. Natural substrates were degraded completely to nucleotides in cell lysates. Competitive inhibition studies indicate that one enzyme system is capable of degrading both RNA and ribosomes, although the existence of more than one enzyme has not been excluded. Erythroid cell lysates quickly broke down polyribosomes into single ribosomes. The more rapid degradation of ribosomes, as compared with transfer RNA, which occurs in vivo, as opposed to findings in vitro, suggests that there is a special intracellular mechanism responsible for ribosome degradation in the maturing erythroid cell.
Edward R. Burka
A spontaneously occurring rat adrenocortical carcinoma which produces corticosterone was maintained by transplantation. The carcinoma appeared to utilize corticosterone biosynthetic steps similar to those of the normal adrenal, but the tumor produced only about 1-10% as much corticosterone per unit tissue weight as nontumorous adrenal glands. The tumor demonstrated little or no increase in corticosterone production in response to adrenocorticotropic hormone (ACTH) either in vivo or in vitro.
R. L. Ney, N. J. Hochella, D. G. Grahame-Smith, R. N. Dexter, R. W. Butcher
Human tissues and cells from pre- and postnatal life were cultivated and studied for plasminogen activator activity. Cultures were obtained from kidney, renal blood vessels, ureter, bladder, lung, and heart. Local activator activity of cells was demonstrated by histochemical techniques. Activator released by cells into the supernatant culture media was assayed by fibrin plate techniques and was investigated for immunological identity using specific antisera to an activator of human origin, urokinase (UK).
Maria B. Bernik, Hau C. Kwaan
Bicarbonate reabsorption is classically regarded as a rate-limited process characterized by saturation kinetics. The tubular maximum (Tm), however, varies with glomerular filtration rate. Thus bicarbonate reabsorption, in common with sodium reabsorption, is characterized by glomerulo-tubular balance. The examination of bicarbonate reabsorption is accomplished using the bicarbonate titration technique; however, this method in its traditional form leads to marked expansion of extracellular fluid (ECF) volume. The possibility exists, therefore, that glomerulo-tubular balance for bicarbonate is altered by the volume expansion and thus that the classic pattern of reabsorption may actually reflect inhibited bicarbonate reabsorptive capacity. The present studies were performed in rats to examine this possibility. Bicarbonate titration studies were performed in two groups of animals: (a) those in which ECF volume expansion was minimized; and (b) those in which ECF volume expansion was exaggerated. In the first group, no Tm for bicarbonate was observed either in the majority of individual rats studied or in a group plot for all rats studied despite the fact that plasma bicarbonate concentrations were increased to values in excess of 60 mEq/liter. In the second group, a clear Tm was demonstrated both in individual animals and in group data and there was a lowered threshold for the excretion of bicarbonate. The data thus lend support to the view that the “normal” Tm for bicarbonate may actually represent an inhibited level of bicarbonate reabsorption induced by ECF volume expansion.
Mabel L. Purkerson, Herbert Lubowitz, Rose W. White, Neal S. Bricker
After severe thermal injury, the adrenal medulla and the sympathetic nerves can be partially or totally depleted of their adrenaline (epinephrine) and noradrenaline (norepinephrine). The purpose of this paper is to elucidate the rate at which dopamine-2-14C, a precursor of noradrenaline, is synthesized into noradrenaline and noradrenaline metabolic products, thereby giving some indication as to dopamine's utilization, turnover, and possible use in treating such noradrenaline-adrenaline depletions. Three burned subjects, 3 wk postburn, were infused with 104.6 μc (872 μg) of dopamine-2-14C for 4 hr. Urine was collected at various hourly intervals for the 1st day, and thereafter for 4 days, assayed, and compared with the metabolism of dopamine in normal subjects. Methods for separating, identifying, and counting radioactivity of the various metabolic products of dopamine are described. Normally 87.6 ±3.1% of the total radioactivity is recovered within 24 hr after an infusion of dopamine-2-14C, but in the three severely burned patients, this value was increased to 93.1, 97.3, and 97.5% in 24 hr. There was a marked decrease in the percentage of radioactivity recovered as noradrenaline in all collection periods, and in contrast to normal subjects, no radioactive noradrenaline was recovered after 24 hr. Concomitantly, there was an increase in radioactivity recovered as metabolic products of noradrenaline, reflecting a compensatory shift toward noradrenaline synthesis and utilization at the expense of the dopamine metabolic products. The results indicate that in the burned patients the infused dopamine-2-14C was rapidly synthesized into noradrenaline and then rapidly released and metabolized. From these results it seems evident that dopamine would be a useful adjunct in the treatment of sympathico-adrenal medullary depletion in burns.
McC. Goodall, Harold Alton
Absorption of calcium was measured by direct intubation and perfusion of the small intestine in 10 volunteer normal adult subjects, two adults with celiac-sprue, and one with a parathyroid adenoma. A total of 60 studies were completed using one of two different levels, duodenojejunum or ileum. Solutions containing stable calcium, radiocalcium47, and a nonabsorbable dilution-concentration marker, polyethylene glycol, were infused at a uniform rate via the proximal lumen of a triple-lumen polyvinyl tube. The mixed intraluminal contents were continuously sampled by siphonage from two distal sites, 10 and 60 cm below the point of infusion. Unidirectional flux rates, lumen to blood and blood to lumen, and net absorption of calcium for the 50 cm segment of small intestine between the two collection sites were calculated from the measured changes in concentration of stable calcium, calcium-47, and polyethylene glycol.
Ronald H. Wensel, Clayton Rich, Arthur C. Brown, Wade Volwiler