Degradation of parathyroid hormone and fragment production by the isolated perfused dog kidney. The effect of glomerular filtration rate and perfusate CA++ concentrations.

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The renal degradation of intact bovine parathyroid hormone (b-PTH 1-84) was studied with the isolated perfused dog kidney. Disappearance of b-PTH 1-84 from the perfusate occurred concomitantly with the appearance of smaller molecular weight forms of immunoreactive parathyroid hormone (PTH). These smaller molecular weight PTH fragments included both carboxyl and amino terminal regions of the PTH peptide. Perfusate from kidneys with lower glomerular filtration rates (GFR) contained b-PTH 1-84 for longer periods of time than kidneys with higher GFRs, and perfusate from kidneys with lower GFRs demonstrated greater accumulation of carboxyl terminal PTH fragments. Perfusate containing high Ca++ concentrations retarded, and perfusate with low Ca++ concentrations accelerated the rate of degradation of b-PTH 1-84 by the kidney. These studies, therefore document the production of PTH fragments during the course of intact hormone degradation by the kidney. They also demonstrate renal clearance of the PTH fragments produced and define the effects of glomerular filtration rate and calcium concentrations on degradation of intact hormone and the clearance of PTH fragments.

Authors

K A Hruska, K Martin, P Mennes, A Greenwalt, C Anderson, S Klahr, E Slatopolsky

Pharmacologic and Hemodynamic Influences on the Rate of Isovolumic Left Ventricular Relaxation in the Normal Conscious Dog

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We studied the effects of acute pharmacologic and hemodynamic interventions on isovolumic left ventricular relaxation in 19 conscious dogs using micromanometer tip catheters. Isoproterenol (11 studies) augmented peak rate of rise of left ventricular pressure [(+) dP/dt] by 1,275±227 (SE) mm Hg/s (P < 0.001) and dP/dt at an isopressure point of 35 mm Hg during isovolumic relaxation [(−) dP/dt35] by 435±80 mm Hg/s (P < 0.001). Peak (−) dP/dt decreased by 467±89 mm Hg/s (P < 0.002). The time constant, T, derived from the logarithmic fall of pressure during isovolumic relaxation, shortened from 20±2.8 to 14.9±1.8 ms (P < 0.003). Calcium (11 studies) increased peak (+) dP/dt and (−) dP/dt35 (both P < 0.0001); peak (−) dP/dt was unchanged. T shortened from 20.4±1.8 to 17.3±1.5 ms (P < 0.002). Volume (13 studies) did not affect either dP/dt or T. Phenylephrine (13 studies) augmented peak (−) dP/dt, but reduced (−) dP/dt35 (both P < 0.01); T lengthened from 22.1±1.5 to 32.5±1.5 ms (P < 0.01). In 15 studies, rapid atrial pacing increased peak (+) dP/dt and (−) dP/dt35 (both P < 0.01). In the first post-pacing beat, peak (−) dP/dt and (−) dP/dt35 decreased (both P < 0.01), although peak (+) dP/dt increased further. T paralleled values of (−) dP/dt35. In five dogs, beta adrenergic blockade had no significant effect on any variable after calcium, volume, or phenylephrine infusion or during or after atrial pacing when the pre-and post-propranolol states were compared.

Authors

Joel S. Karliner, Martin M. Lewinter, Felix Mahler, Robert Engler, Robert A. O'Rourke

Thyroid Dysfunction in Chronic Renal Failure: A STUDY OF THE PITUITARY-THYROID AXIS AND PERIPHERAL TURNOVER KINETICS OF THYROXINE AND TRIIODOTHYRONINE

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Thyroid function was evaluated in 46 patients with end-stage kidney disease and 42 normal subjects. Patients were studied before and after the institution of maintenance hemodialysis (HD) and after renal transplantation (RT). Serum total triiodothyronine concentrations (TT3, ng/100 ml, mean±SD) were 63±17 and 83±22 in the non-HD and HD groups, respectively. Values from normal subjects were 128±25 and from RT patients 134±20. The TT3 was in the hypothyroid range (<78 ng/100 ml; 2 SD below normal mean) in 80% of non-HD and 43% of HD patients. Mean serum total thyroxine concentration (TT4), although within the normal range, was lower than the control value. T4-binding globulin capacity was also slightly lower but the difference was not statistically significant. Among patients whose TT4 was 1 SD below the normal mean, the free T4 index was equally depressed, suggesting that factors other than decreased binding capacity might be responsible for the low TT4. In addition, there was a 37% incidence of goiter. Mean serum thyroid-stimulating hormone (TSH) was not elevated and the TSH response to thyrotropin-releasing hormone (TRH) was distinctly blunted, suggesting the possibility of pituitary dysfunction as well. In vivo 125I-l-T4 and 131I-l-T3 kinetics during 0.2 mg/day of l-T4 replacement showed marked reduction in T3 turnover rate in the uremic patients, both before and during HD; the values (μg T3/day, mean±SD) for the different groups were as follows: normal, 33.8±6.1; non-HD, 13.5±2.6; HD, 12.9±3.1; and RT, 30.3±7.1. The low T3 turnover rate was due to impaired extrathyroidal conversion of T4 to T3. The mean percent±SD of metabolized T4 converted to T3 was 37.2±5.8 in normal subjects, 15.7±3.1 in non-HD, 12.8±1.7 in HD, and 34.0±14.7 in RT patients. In contrast, thyroidal T3 secretion rate was not different between the control and the three patient groups. Thus, it appears that uremia affects thyroid function at several levels: (a) subnormal pituitary TSH response to TRH; (b) possible intrathyroidal abnormalities as suggested by slightly decreased TT4 and high incidence of goiter; and (c) abnormal peripheral generation of T3 from T4. Restoration of renal function with RT resulted in normalization of all parameters of thyroid function with the exception of blunted or absent TSH response to TRH. The latter may be a direct consequence of glucocorticoid administration.

Authors

Victoria Sy Lim, Victor S. Fang, Adrian I. Katz, Samuel Refetoff

Platelet Membrane Defects in Glanzmann's Thrombasthenia: EVIDENCE FOR DECREASED AMOUNTS OF TWO MAJOR GLYCOPROTEINS

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Platelets from patients with Glanzmann's thrombasthenia have a distinct molecular alteration of the plasma membrane surface, namely decreased amounts of a major glycoprotein designated as IIb (apparent mol wt 142,000). To identify other possible surface defects of thrombasthenic platelets, we labeled the membrane polypeptides of normal and thrombasthenic platelets by two different techniques: lactoperoxidase-catalyzed iodination and galactose oxidase oxidation, followed by reduction with tritiated sodium borohydride. Labeling patterns were determined after the polypeptides were separated by two-dimensional polyacrylamide gel electrophoresis. Before the second dimension was run, platelet samples were incubated with a reducing agent, β-mercapto-ethanol, to cleave the disulfide bonds of certain glycoproteins; the resulting changes in electrophoretic mobility permitted better resolution of individual molecules. Comparison of the labeled polypeptides of normal and thrombasthenic samples after reduction indicated decreased labeling of two major glycoproteins in thrombasthenic platelets: IIb and III (apparent mol wt 114,000). The relative proportions of radioactivity incorporated by these polypeptides were about 60 and 80% less than control values, respectively. With either Coomassie Blue or periodic acid-Schiff's reagent, glycoprotein III stained much less intensely in thrombasthenic compared to normal samples, indicating that the observed labeling deficit was caused by a decreased concentration of the molecule rather than steric inaccessibility on the membrane surface. Analysis of normal plasma membranes by affinity chromatography showed that glycoprotein IIb has receptors for lectin from Lens culinaris, the common lentil, whereas III does not. We conclude that a characteristic feature of Glanzmann's thrombasthenia is a decreased concentration of two discrete glycoproteins in the platelet plasma membrane.

Authors

David R. Phillips, Patricia Poh Agin

Pathogenesis of alcohol-induced accumulation of protein in the liver.

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Alcohol feeding to rats produced hepatomegaly, associated with enlargement of the hepatocytes. The increase in liver dry weight was accounted for not only by fat but also by protein accumulation, primarily in microsomes and cytosol, with a selective increase in export proteins: concentrations of both immunoreactive albumin and transferrin were augmented in liver microsomes and cytosol of ethanol-fed rats. To investigate the mechanism of this protein accumulation, [14C]leucine was injected intravenously and its incorporation into both liver and serum proteins was measured after various time intervals. Rates of synthesis and export were assessed from protein labeling and specific activities of leucyl-tRNA. Synthesis of liver protein and proalbumin were enhanced by chronic ethanol feeding, but this was not associated with a corresponding rise in serum albumin output. Actually, there was a significant retention of the label in liver albumin and transferrin with delayed appearance in the serum of ethanol-fed rats. This indicated that, regardless of the changes in synthesis, the export of protein from the liver into the plasma was impaired. This alteration in export was associated with a decreased amount of polymerized tubulin in the liver of ethanol-treated animals. Thus, both enhanced protein synthesis and defective export contribute to the ethanol-induced accumulation of liver protein, and the decrease in liver microtubules represents a possible site for impairment of protein export.

Authors

E Baraona, M A Leo, S A Borowsky, C S Lieber

Concentration of l-Thyroxine and l-Triiodothyronine Specifically Bound to Nuclear Receptors in Rat Liver and Kidney: QUANTITATIVE EVIDENCE FAVORING A MAJOR ROLE OF T₃ IN THYROID HORMONE ACTION

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To estimate the relative contribution of l-triiodothyronine (T3) and l-thyroxine (T4) to thyroidal effects, we have measured the concentration of iodothyronine bound to specific hepatic nuclear receptor sites by three different techniques: (a) specific radioimmunoassay after separation of T3 and T4 by preparative paper chromatography; (b) in vivo kinetic approaches as reported previously; and (c) isotopic equilibration. By these three methods, receptor concentration of T3 and T4 in liver was 0.51±0.19 (SD) and 0.08±0.06; 0.52±0.12 and 0.08±0.02; and 0.50±0.13 and 0.10±0.03 pmol/mg DNA, respectively. The percentage contribution of T3 and T4 to total receptor iodothyronine was thus 86.8±9.0 and 13.2±9.4; 86.3±3.5 and 13.7±3.5; and 83.7±5.6 and 16.3±5.6%, respectively. In kidney, specifically bound nuclear T3 and T4 were estimated both by isotopic equilibration and by in vivo kinetic techniques to be 0.28±0.11 and 0.03±0.01 pmol/mg DNA, respectively. Thus, T3 constituted 89.4±3.2% of total receptor iodothyronine in this tissue. No other iodothyronines or analogs were bound to the nuclear sites in either tissue. Kidney and liver nuclear T3 concentrations also were identical to values previously reported with in vivo kinetic techniques. Other studies from this laboratory have suggested that thyroid effect is related to the molar concentration of iodothyronine bound to specific nuclear sites, that the sites are similar in various tissues, and that iodothyronine in plasma is in equilibrium with nuclear T3. If these relationships are assumed, T3 contributes between 85 and 90% of thyroidal effects in the euthyroid rat. The remaining 10-15% of thyroidal effect appears to result from the intrinsic activity of T4.

Authors

Martin I. Surks, Jack H. Oppenheimer

Anabolic actions of reduced and S-carbamidomethylated human growth hormone and its plasmin digest in man.

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Six children aged 12-15 yr, deficient in endogenous growth hormone, were each treated, after a 7-day control period, for 7 days with 0.0168, 0.052, and 0.168 U/kg body wt3/4 human growth (hGH) (doses A, B, and C, respectively) in separate metabolic balance studies. Doses B and C caused a dose-related retention of N, P, K, Na, and Cl in ratios of 1/0.069/4.5/7.5/5.6. These ratios indicate increments in masses of protoplasm/extracellular fluid (ECF)/bone in ratios of 1/2.0/ less than 0.001. Three of the children were also treated with doses A, B, and C of reduced and carbamidomethylated hGH (RCAM-hGH). Doses B and C caused 1.2-2.8 times as much retention of N, P, and K, and 0.3-0.5 times as much retention of Na and Cl, as did the corresponding doses of hGH. The plasmin digest of RCAM-hGH gave results generally similar to RCAM-hGH. For RCAM-hGH and its plasmin digest, N, P, K, Na, and Cl were retained in ratios of about 1/0.14/5.4/2.2/2.1, indicating increments of protoplasm/ECF/bone of about 1/0.8/0.05. These findings indicate that reduction and carbamidomethylation alter the anabolic actions of hGH in man in both quantitative and qualitative manner. RCAM-hGH is more potent in stimulating enlargement of protoplasm and bone, and less potent in stimulating expansion of ECF, than is the native hormone. The profile of anabolic actions of RCAM-hGH in man does not appear to be further altered by digestion with plasmin.

Authors

S B Heymsfield, R A Bethel, E C Hall, J B Mills, M H Moseley, J L Kostyo, D Rudman

Prekallikrein deficiency in a kindred with kininogen deficiency and Fitzgerald trait clotting defect. Evidence that high molecular weight kininogen and prekallikrein exist as a complex in normal human plasma.

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Abstract

Plasma from an individual with a hereditary deficiency of kininogens is deficient in kininogen antigens; heterozygous relatives are partially deficient in plasma kininogen antigens. In addition, plasma from the proband is partially deficient in functional and antigenic properties of a plasma prekallikrein, and the relatives heterozygous for kininogen deficiency are also partially deficient in the plasma prekallikrein. It is possible that the defects are both inherited and that the inheritance of a deficiency of prekallikrein is genetically linked to the inheritance of a deficiency of kininogen. Alternatively, it is possible that the deficiency of prekallikrein may be due to its hypercatabolism which could be a consequence of a deficiency of high molecular weight kininogen that may stabilize the prekallikrein in plasma. Evidence to support this possibility is presented by the fact that prekallikrein and high molecular weight kininogen apparently exist as a complex in normal plasma, because monospecific antiserum to kininogen removed both high molecular weight kininogen and prekallikrein from plasma, and vice versa. Moreover, prekallikrein was not adsorbed from kininogen-deficient plasma by antiserum to kininogen unless high molecular weight kininogen was first added to the plasma. Low molecular weight kininogen did not participate in these reactions.

Authors

V H Donaldson, J Kleniewski, H Saito, J K Sayed

Purification of High Molecular Weight Kininogen and the Role of This Agent in Blood Coagulation

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Recent studies of individuals with high molecular weight (HMW) kininogen deficiency established the importance of this plasma protein for in vitro initiation of blood coagulation. In the present study, HMW-kininogen was highly purified from human plasma by monitoring its clot-promoting activity, using Fitzgerald trait plasma as a substrate. This preparation of HMW-kininogen revealed a single band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (mol wt: 120,000) and released 1% of its weight as bradykinin upon incubation with plasma kallikrein. HMW-kininogen specifically repaired impaired surface-mediated plasma reactions of Fitzgerald trait plasma, but did not affect those of Hageman trait and Fletcher trait plasma. Kinin release from HMW-kininogen by trypsin, but not by plasma kallikrein, resulted in total loss of clot-promoting activity. No inhibitors of coagulation were found when all kinin activity was removed from HMW-kininogen by trypsin. The roles of HMW-kininogen, Hageman factor (HF, Factor XII), plasma prekallikrein (Fletcher factor), and plasma thromboplastin antecedent (PTA, Factor XI) in blood coagulation were studied in a purified system. HMW-kininogen was absolutely required for activation of PTA by HF and ellagic acid. The yield of activated PTA was proportional to the amount of HF, HMW-kininogen, and PTA in the mixtures, suggesting that, to activate PTA, these three proteins might form a complex in the presence of ellagic acid. No fragmentation of HF was found under these conditions. In contrast to HF, HF-fragments (mol wt: 30,000) activated PTA in the absence of HMW-kininogen and ellagic acid. Thus, it appears that in the present study PTA was activated in two distinct ways. Which pathway is the major one in whole plasma remains to be determined.

Authors

Hidehiko Saito

Small Airways in Idiopathic Pulmonary Fibrosis: COMPARISON OF MORPHOLOGIC AND PHYSIOLOGIC OBSERVATIONS

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Abstract

18 patients with idiopathic pulmonary fibrosis were studied to determine if they had morphologic evidence of small airways disease and if physiologic testing could predict morphologic findings. In the presence of normal airway function by standard physiologic studies (forced expiratory volume in 1 s/forced vital capacity and airway resistance by plethysmography), dynamic compliance, maximum expiratory flow-volume curves, and maximum flowstatic recoil curves were measured to detect physiologic alterations consistent with small airways abnormalities. These physiologic data were then compared with estimates of small airways diameter made in lung biopsy specimens.

Authors

Jack D. Fulmer, William C. Roberts, Edwyna R. von Gal, Ronald G. Crystal

Circulating Immune Complexes after Renal Transplantation: CORRELATION OF INCREASED ¹²⁵I-C1_q BINDING ACTIVITY WITH ACUTE REJECTION CHARACTERIZED BY FIBRIN DEPOSITION IN THE KIDNEY

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To assess the role of circulating immune complexes in the pathogenesis of acute rejection, sera were measured for such complexes by the 125I-C1q binding assay in 45 normal subjects, 24 allografted patients undergoing acute rejection, and in 11 allografted patients in a quiescent phase. Increased C1q-binding activity (C1q-BA) was detected in 14 patients with acute rejection, 9 of whom had renal biopsies showing fibrin deposition in the vasculature together with cellular infiltrates in the tubulo-interstitial structures; renal histology was not available in the other 5 patients. The other 10 patients with acute rejection, whose biopsies showed only cellular infiltrates, and the 11 patients in a quiescent phase posttransplantation did not have increased levels of serum C1q-BA.

Authors

Yuet M. Ooi, Boon S. Ooi, Enrique H. Vallota, Martin R. First, Victor E. Pollak

On the Mechanism of Polyuria in Potassium Depletion: THE ROLE OF POLYDIPSIA

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The association of potassium (K) depletion with polyuria and a concentrating defect is established, but the extent to which these defects could be secondary to an effect of low K on water intake has not been systematically investigated. To determine whether hypokalemia has a primary effect to increase thirst and whether any resultant polyuria and polydipsia contribute to the concentrating defect, we studied three groups of rats kept in metabolic cages for 15 days. The groups were set up as follows: group 1, normal diets and ad lib. fluids (n = 12); group 2, K-deficient diet on ad lib. fluids (n = 12); and group 3, K-deficient diet and fluid intake matched to group 1 (n = 14). Daily urine flow and urinary osmolality of groups 1 and 3 were not significantly different throughout the study. In contrast, as of day 6, group 2 rats consistently had a higher fluid intake (P < 0.0025), higher urine flow (P < 0.001), and lower urinary osmolality (P < 0.001) than the other two groups. These alterations in fluid intake and urine flow preceded a defect in maximal concentrating ability. On day 7, maximal urinary osmolality was 2,599±138 msmol/kg in rats on K-deficient intake and 2,567±142 msmol/kg in controls. To determine whether this primary polydipsia is itself responsible for the development of the concentrating defect, the three groups of rats were dehydrated on day 15. Despite different levels of fluid intake, maximal urinary osmolality was impaired equally in groups 2 and 3 (1,703 and 1,511 msmol/kg, respectively), as compared to rats in group 1 (2,414 msmol/kg), P < 0.001. We therefore conclude that K depletion stimulates thirst, and the resultant increase in water intake is largely responsible for the observed polyuria. After 15 days of a K-deficient diet, the impaired maximal urinary concentration in hypokalemia, however, was not related to increased water intake, since fluid restriction did not abolish the renal concentrating defect.

Authors

Tomas Berl, Stuart L. Linas, Gary A. Aisenbrey, Robert J. Anderson

Phytohemagglutinin Response in Systemic Lupus Erythematosus: RECONSTITUTION EXPERIMENTS USING HIGHLY PURIFIED LYMPHOCYTE SUBPOPULATIONS AND MONOCYTES

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The phytohemagglutinin (PHA) response of lymphocytes from untreated patients with systemic lupus erythematosus (SLE) was studied using highly purified subpopulations of cells involved in the transformation response: T lymphocytes, B lymphocytes, and monocytes. Cell transformation was quantitated using both tritiated thymidine ([3H]-TdR) incorporation into DNA and cytofluorographic determination of cellular DNA content. Dose-response curves using six concentrations of PHA and five concentrations of cells over 0-5 days revealed a decrease in [3H]TdR by stimulated lymphocytes from some SLE patients. This decrease in [3H]TdR was paralleled by a decreased percentage of cells in S, G2, and M phases of the cell cycle. However, abnormal response occurred entirely in those SLE patients who were hypocomplementemic. The etiology of the impaired response was further examined. Lymphocyte receptors for concanavalin A were studied using cytofluorography of lymphocytes stained with fluorescein-conjugated concanavalin A. The frequency distribution of concanavalin A receptors was similar in the normocomplementemic and hypocomplementemic lupus patients and in normals. The latex phagocytic activity of lupus macrophages was similar to normals when allogeneic normal plasma was used in the culture medium. Phagocytic activity became abnormal in the presence of SLE plasma. However, there was no difference in the [3H]TdR response or the percentage of cells in S, G2, and M phases when T lymphocytes from the hypocomplementemic patients were stimulated on either autologous or normal allogeneic monocyte monolayers. Likewise, normal lymphocytes incorporated similar amounts of [3H]TdR and had similar percentages of cells in S, G2, and M phases whether their T lymphocytes were stimulated on autologous or SLE monocyte monolayers. Highly purified subpopulations of B and T lymphocytes were obtained by density sedimentation or Fenwal Leuko-Pak passage of lymphocyte populations. The response to PHA by lymphocytes from the hypocomplementemic lupus patients could be seen to involve at least two abnormalities. One, in reference to normal lymphocytes, SLE T lymphocytes plus monocytes had an impaired response; two, SLE B lymphocytes plus SLE T lymphocytes plus SLE monocytes had an impaired response. Two patients in the hypocomplementemic group were treated with steroids. 5 days after steroid treatment was initiated, the percentage of cells in S, G2, and M phases and the [3H]TdR response of PHA-stimulated lymphocytes returned to normal. The normalization of the [3H]TdR response was explained both by a return of purified T cells plus monocytes, purified B cells plus monocytes, and whole lymphocyte populations to normal responsiveness. These studies suggest that a steroid-correctable defect exists in T and B lymphocytes in SLE.

Authors

Peter D. Utsinger, William J. Yount

Role of 1,25-Dihydroxyvitamin D₃ on Intestinal Phosphate Absorption in Rats with a Normal Vitamin D Supply

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Abstract

In vitamin D-deficient rats, impaired intestinal phosphorus (P) absorption can be corrected by 1,25-dihydroxyvitamin D3[1,25-(OH)2D3]. In the present study, it was investigated whether changes in 1,25-(OH)2D3 production can influence intestinal P transport also in animals with a normal supply of vitamin D. The intestinal P absorption was evaluated in rats using both the in situ duodenal loop technique and the determination of the overall gastrointestinal absorption under three conditions known to influence the production of 1,25-(OH)2D3: (a) variation in dietary P, (b) thyroparathyroidectomy (TPTX) with or without administration of parathyroid hormone (PTH), and (c) treatment with disodium ethane-1-hydroxy-1,1-diphosphonate (EHDP). In all circumstances changes in duodenal absorption paralleled the changes in the overall fractional absorption. (a) Lowering dietary P stimulated P absorption. (b) TPTX decreased P absorption. This effect was corrected either by the administration of PTH or by the administration of 1,25-(OH)2D3. (c) EHDP, when given at a dose known to inhibit 1,25-(OH)2D3 formation, decreased the duodenal P absorption in both intact and TPTX animals. This effect was corrected by 1,25-(OH)2D3. In the TPTX-EHDP-treated animals, the administration of PTH did not rectify the low duodenal P absorption. These results support the thesis that, in rats with normal vitamin D supply, variations in the endogenous production of 1,25-(OH)2D3 change the rate of P absorption. However, these changes are in such magnitude that they are of relatively small importance when compared to the effect of variation in the dietary intake of P. These results also strongly suggest that the action of PTH on duodenal P transport is mediated by its effect on 1,25-(OH)2D3 production, inasmuch as the effect of the hormone is abolished after blocking the renal 1-hydroxylation with EHDP.

Authors

R. Rizzoli, H. Fleisch, J-P. Bonjour

Estimation of Somatomedin-C Levels in Normals and Patients with Pituitary Disease by Radioimmunoassay

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Abstract

The development of a radioimmunoassay for somatomedin-C has for the first time made it possible to discriminate between serum concentrations of a single peptide or closely related group of peptides and the net somatomedin activity measured by less specific bioassay and radioreceptor techniques. Antibodies to human somatomedin-C were raised in rabbits using a somatomedin-C ovalbumin complex as the antigen. A variety of peptide hormones at concentrations up to 1 μM are not recognized by the antibody. Insulin at concentrations >0.1 μM cross reacts in a non-parallel fashion; purified somatomedin-A is only 3% as active as somatomedin-C; and radiolabeled cloned rat liver multiplication stimulating activity does not bind to the antibody. Immunoreactive somatomedin-C can also be quantitated in the sera of a variety of subhuman species.

Authors

Richard W. Furlanetto, Louis E. Underwood, Judson J. Van Wyk, A. Joseph D'Ercole

A critical assessment of the roles of circulating hydrogen ion and lactate in the production of exercise-induced asthma.

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To evaluate the roles of circulating hydrogen ion and lactate in the production of exercise-induced asthma, two experiments were performed. In the first, we exercised six asthmatic subjects to exhaustion on a bicycle ergometer while recording arterial pH at periodic intervals. Multiple aspects of pulmonary mechanics were measured before and after the work load. After recovery, the identical procedures were repeated, but sufficient quantities of sodium bicarbonate were infused to keep the pH at the pre-exercise level. In both experiments, statistically identical attacks of asthma were induced. To study the effect of lactate, five subjects were exercised on several occasions in order to determine the lowest level of work, and hence arterial lactate, that was reproducibly associated with an acute asthma attack. When this was known, sufficient quantities of sodium lactate were infused into the resting subjects so as to equal or exceed the amount produced with exercise. Pulmonary mechanics were not altered with this intervention. These findings demonstrate that lactic acidemia is not the cause of exercise-induced asthma.

Authors

R H Strauss, R H Ingram Jr, E R McFadden Jr

Intestinal Assimilation of a Tetrapeptide in the Rat: OBLIGATE FUNCTION OF BRUSH BORDER AMINOPEPTIDASE

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The small intestine is capable of taking up peptide nutrients of two or three amino acid residues, but the mechanism of intestinal assimilation of larger oligopeptides has not been established. The amino-oligopeptidase of the intestinal brush border possesses high specificity for oligopeptides having bulky side chains and is a candidate for a crucial role in the overall assimilation of dietary protein.

Authors

Kenneth W. Smithson, Gary M. Gray

Eosinophilopoietin: A CIRCULATING LOW MOLECULAR WEIGHT PEPTIDE-LIKE SUBSTANCE WHICH STIMULATES THE PRODUCTION OF EOSINOPHILS IN MICE

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Abstract

In earlier studies, methods were developed to raise specific antibodies in rabbits against purified suspensions of mouse or human eosinophils. On administration of antieosinophil serum (AES) to mice, the mature eosinophils in tissues, peripheral blood, and bone marrow were depleted, while the immature eosinophil pool in the bone marrow was observed to proliferate. The current investigations explore the generation of eosinophilopoietic factors during AES-induced eosinophilopenia. Mice received three injections of AES, one every other day. As the peripheral eosinophil counts started to recover after the last AES injection, the serum was collected and transferred to normal animals. Within 2 days the recipients showed an increase in peripheral blood as well as in bone marrow eosinophils. The rise in bone marrow eosinophils was due to newly formed cells as evidenced by increased uptake of [3H]thymidine. The generation of eosinophilopoietic activity was specifically related to depletion of eosinophils but not neutrophils. The eosinophilopoietic activity was: (a) dependent on the volume of serum transferred, (b) lost on dialysis, and (c) largely heat labile. The activity eluted as a low molecular weight substance on G-25 Sephadex and was digested by pronase but not by trypsin. Active fractions collected from G-25 columns were not chemotactic for the eosinophils in vitro. Thus, specific depletion of mature eosinophils generates a low molecular weight peptide which stimulates eosinophilopoiesis in vivo. It is suggested that this substance be named eosinophilopoietin.

Authors

Adel A. F. Mahmoud, Marta K. Stone, Robert W. Kellermeyer

The Mitogenic Effect of the Lymphocytosis Promoting Factor from Bordetella Pertussis on Human Lymphocytes

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Abstract

The purified lymphocytosis promoting factor (LPF) from Bordetella pertussis was found to be a potent mitogen for peripheral blood lymphocytes (PBL) from normal adults as well as for cord blood lymphocytes. Proliferation occurred in autologous plasma or fetal calf serum, regardless of previous exposure to pertussis infection or immunization. Only one adult human serum, from a physician constantly working with B. pertussis, inhibited the mitogenic response to LPF and this serum was shown to contain precipitating antibody against LPF. The proliferative effect of LPF was characteristic of a “nonspecific” mitogen and not of antigen stimulation of sensitized cells.

Authors

J. H. Morse, A. S. Kong, J. Lindenbaum, S. I. Morse

Bile acid excretion: the alternate pathway in the hamster.

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The quantitative significance of renal excretion of bile acid ester sulfates as an alternate excretory pathway was evaluated in hamsters. After bile duct ligation, total serum bile acid fell from a mean level of 454 microgram/ml at 24 h to 64 microgram/ml by 96 h. During this period the bulk of the bile acid pool could be accounted for as esterified bile acids in urine. Renal pedicle ligation of animals with bile duct obstruction led to retention of the bile acid ester sulfates in serum. Thioacetamide hepatotoxicity diminished ester sulfation of bile acids causing diminished renal secretion with relatively greater retention of nonesterified bile acids in serum. We conclude that secretion of esterified bile acids by the kidney is an efficient alternate pathway for maintaining bile acid excretion in obstructive biliary tract disease. Coexistent hepatocellular disease diminishes ester sulfation and the effectiveness of the alternate pathway in maintaining bile acid excretion.

Authors

R Galeazzi, N B Javitt

Regulation of Mammary and Adipose Tissue Lipoprotein Lipase and Blood Triacylglycerol in Rats during Late Pregnancy: EFFECT OF PROSTAGLANDINS

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The effects of several prostaglandins on lipoprotein lipase activity of mammary gland and adipose tissue and serum triacylglycerol were studied during late pregnancy in rats. Prostaglandins were injected twice daily for 2 days before and once on the day of analysis. In rats pregnant 20 days, prostaglandin F2α (PGF2α) increased the activity of lipoprotein lipase in mammary gland fourfold, reduced the activity in adipose tissue about 60%, and decreased serum concentration of triacylglycerol 50%. PGF2α also reduced serum concentration of progesterone 90% and increased that of prolactin fivefold, but had no effect on serum concentrations of either immuno-reactive insulin or 17β-estradiol. Injections of 13,14-dihydro-15-keto PGF2α, a metabolite of PGF2α, had similar effects in rats pregnant 20 days, whereas prostaglandins E1 and E2 did not. In rats pregnant 16 days, PGF2α did not affect lipoprotein lipase activity in the tissues or the concentration of triacylglycerol and prolactin in serum, although it decreased serum progesterone 80%.

Authors

Peter M. Spooner, Mary M. Garrison, Robert O. Scow

Absence of the Eighth Component of Complement in Association with Systemic Lupus Erythematosus-Like Disease

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Abstract

A 56-yr-old black woman with absence of the eighth component of complement and a disease compatible with systemic lupus erythematosus is described. Her disease is characterized by the presence of photosensitive “malar” rash, alopecia, polyarthritis, and nephrotic syndrome.

Authors

Hugo E. Jasin

Deficiency of Carnitine in Cachectic Cirrhotic Patients

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Abstract

Carnitine is synthesized from lysine and methionine. In the rat, inadequate intake of either of these essential amino acids causes carnitine depletion. Inasmuch as protein deficiency is common in the hospital population, we have investigated the possible occurrence of nosocomial carnitine deficiency. Fasting serum carnitine concentration was measured in 16 normal and 247 patients in 16 disease groups. Normal range of carnitine was 55-103 μM. Only the cirrhotic group showed significant (P < 0.05) hypocarnitinemia. 14 of 36 hospitalized cirrhotics had subnormal values for serum carnitine. The creatinine/height index, midarm muscle circumference, and triceps skin-fold thickness indicated protein-calorie starvation in the 14 hypocarnitinemic liver patients. In six of the hypocarnitinemic cirrhotics (average serum level 50% of normal), spontaneous dietary intakes of carnitine, lysine, and methionine were measured and found to be only 5-15% as great as in six normocarnitinemic, healthy controls. When these six cirrhotic and six normal subjects were given the same lysine-rich, methionine-rich, and carnitine-free nutritional intake, the normals maintained normal serum carnitine levels and excreted 100 μmol/day, whereas the cirrhotics' serum level fell to 25% of normal, and urinary excretion declined to 15 μmol/day.

Authors

Daniel Rudman, Charles W. Sewell, Joseph D. Ansley

Sites and Mechanisms of Localization of Technetium-99m Phosphorus Radiopharmaceuticals in Acute Myocardial Infarcts and other Tissues

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Abstract

This study was performed to elucidate the localization at the cellular level of technetium-99m phosphorus (99mTc-P) radiopharmaceuticals in acute myocardial infarcts and the mechanisms responsible for 99mTc-P uptake in acute myocardial infarcts and other tissues. In 20 dogs with proximal left anterior descending coronary arterial ligation for 1-3 days, elevated calcium levels were measured at all sites of increased 99mTc-P uptake (acute myocardial infarcts, necrotic thoracotomy muscle, lactating breast, and normal bone); however, a consistent linear relationship between 99mTc-P and calcium levels was not observed. A strong correlation (r = 0.95 and 0.99, n = 2 dogs) was demonstrated between levels of 3H-diphosphonate and 99mTc-P in infarcted myocardium. Autoradiographic studies with 3H-diphosphonate revealed extensive labeling in the infarct periphery which contained necrotic muscle cells with features of severe calcium overloading, including widespread hypercontraction as well as more selective formation of mitochondrial calcific deposits. Autoradiography also demonstrated labeling of a small population of damaged border zone muscle cells which exhibited prominent accumulation of lipid droplets and focal, early mitochondrial calcification. Cell fractionation studies revealed major localization of both 99mTc-P and calcium in the soluble supernate and membrane-debris fractions of infarcted myocardium and less than 2% of total 99mTc-P and calcium in the mitochondrial fractions; however, electron microscopic examination showed that mitochondria with calcific deposits were not preserved in the mitochondrial fractions. In vitro studies evaluating the role of serum protein binding on tissue uptake of 99mTc-P agents demonstrated that, in spite of significant complexing with serum proteins, serum 99mTc-P activity retained the ability to adsorp to calcium hydroxyapatite and amorphous calcium phosphate. In vivo studies showed that concentration of human serum albumin (labeled with iodine-131) in infarcted myocardium reached a maximum of only 3.8 times normal after a circulation time of 96 h, whereas 99mTc-P uptake was at least 10 times normal after a circulation time as short as 1 h. It is concluded that: (a) 99mTc-P uptake in acutely infarcted myocardium, and possibly other types of soft tissue damage, is limited to necrotic and severely injured cells; (b) concentration of 99mTc-P results from selective adsorption of 99mTc-P with various forms of tissue calcium stores, including amorphous calcium phosphate, crystalline hydroxyapatite, and calcium complexed with myofibrils and other macromolecules, possibly supplemented by calcium-independent complexing with organic macromolecules; and (c) lack of a linear relationship between 99mTc-P and tissue calcium levels mainly results from local differences in composition and physicochemical properties of tissue calcium stores and from local variations in levels of blood flow for delivery of 99mTc-P agents.

Authors

L. Maximilian Buja, Andrew J. Tofe, Padmakar V. Kulkarni, Amal Mukherjee, Robert W. Parkey, Marion D. Francis, Frederick J. Bonte, James T. Willerson

Purine Nucleoside Phosphorylase Deficiency: EVIDENCE FOR MOLECULAR HETEROGENEITY IN TWO FAMILIES WITH ENZYME-DEFICIENT MEMBERS

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Abstract

Purine-nucleoside phosphorylase (NP) deficiency is associated with severely defective thymus-derived (T)-cell and normally functioning bone marrow-derived (B)-cell immunity. In this study, two unrelated families with a total of three NP deficient members were investigated.

Authors

William R. A. Osborne, Shi-Han Chen, Eloise R. Giblett, W. Douglas Biggar, Arthur A. Ammann, C. Ronald Scott

A Role for Prostaglandin E in Defective Insulin Secretion and Carbohydrate Intolerance in Diabetes Mellitus

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Abstract

Prostaglandin E2 (PGE2) infusion in normal humans inhibited acute insulin responses to a glucose (5 g i.v.) pulse (response before PGE2 = 593 ± 104%; during PGE2 = 312±55%; mean±SE, mean change 3-5 min insulin,% basal, P < 0.005). This effect was associated with a decrease in glucose disappearance rates (KG before PGE2 = 0.73±0.07; during PGE2 = 0.49±0.06%/min, P < 0.025). Acute insulin responses to arginine (2 g i.v.) were not affected by PGE2 (response before PGE2 = 592±164%; during PGE2 = 590±118%; P = NS). Infusion of sodium salicylate (SS), an inhibitor of endogenous prostaglandin synthesis, augmented acute insulin responses to glucose in normals (response before SS = 313±62%; during SS = 660±86%; P < 0.001). In adult-onset diabetes with fasting hyperglycemia, SS restored absent acute insulin responses to glucose (20 g i.v.) pulses (response before SS = 5±6%; during SS = 97±24%; P < 0.005). This was accompanied by a fourfold augmentation in second phase insulin secretion (second phase before SS = 1,696±430%; during SS = 5,176±682%; change 10-60 min insulin, μU/ml·min,% basal, P < 0.001) and by acceleration of glucose disappearance rates (KG before SS = 0.56±0.06; during SS = 1.02±0.17%/min, P < 0.005). These findings uniquely demonstrate that (a) PGE2 inhibits glucose-induced acute insulin responses and decreases glucose disposal in nondiabetic humans and (b) SS restores acute insulin responses, augments second phase insulin secretion, and accelerates glucose disposal in hyperglycemic, adultonset diabetics. It is hypothesized that endogenous PGE synthesis may play a role in defective insulin secretion and glucose intolerance in diabetes mellitus.

Authors

R. Paul Robertson, Mei Chen

Stimulation of Surfactant Production by Oxytocin-Induced Labor in the Rabbit

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Abstract

The respiratory distress syndrome is believed to be due to insufficient surfactant. It is known that there is a greater incidence of the respiratory distress syndrome among infants delivered by cesarean section before labor than among those delivered after labor at the same gestational age. The purpose of this study was to determine the effect of labor on the production of pulmonary surfactant.

Authors

Seamus A. Rooney, Laurice I. Gobran, Theresa S. Wai-Lee

Release of immunoreactive somatostatin from the pancreas in response to glucose, amino acids, pancreozymin-cholecystokinin, and tolbutamide.

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Abstract

The effects of glucose, amino acids, pancreozymin-cholecystokinin, and tolbutamide upon the release of immunoreactive somatostatin (IRS) from the isolated perfused pancreas were studied. In seven experiments in which glucose was perfused either at a concentration of 100 or 350 mg/dl or at 25 mg/dl, IRS levels were significantly greater at the higher glucose concentrations. In three dose-response experiments in which the perfusing glucose concentration was increased at 30-min intervals from an initial concentration of 25 mg/dl to a final concentration of 300 mg/dl, progressive increases in IRS release were noted at glucose concentrations of 100 mg/dl and above. Perfusion of a 20 mM mixture of 10 amino acids also elicited a prompt and significant biphasic IRS rise in each of six experiments. In five experiments, 20 mM leucine evoked a similar response in mean IRS. Perfusion with 0.075 Ivy U/ml of pancreozymin-cholecystokinin, with or without the presence of a 1 mM 10-amino acid mixture, elicited a prompt rise in IRS with a pattern resembling that of insulin in a total of six experiments. Tolbutamide (0.75 mg/min) also stimulated IRS release in five of six challenges. The IRS responses to nutrients and to pancreozymin and their similarity to the insulin responses raise the possibility that, like insulin, pancreatic somatostatin may have an endocrine role related to nutrient homeostasis.

Authors

E Ipp, R E Dobbs, A Arimura, W Vale, V Harris, R H Unger

Bicarbonate transport by rabbit cortical collecting tubules. Effect of acid and alkali loads in vivo on transport in vitro.

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Abstract

Rabbit cortical collecting tubules were perfused in vitro to investigate the control of bicarbonate transport. Bicarbonate was measured by microcalorimetry as total CO2. The perfusate and bath were identical solutions containing 25 mM bicarbonate at pH 7.4. The mean pH of the urine in the bladders of untreated rabbits at the time they were killed was 7.4. Their individual tubules, studied in vitro, either absorbed or secreted bicarbonate, and, combining the results, there was on the average no significant net transport. When the rabbits were treated with NH4Cl the day before the experiment, their urine was acidic and their tubules studied in vitro absorbed bicarbonate (i.e., there was net lumen-to-bath transport). In contrast, when the rabbits were treated with NaHCO3, their urine was significantly more alkaline, and their tubules studied in vitro generally secreted bicarbonate (i.e., net bath-to-lumen transport). Thus, the direction of bicarbonate transport by cortical collecting tubules studied under standard conditions in vitro correlated with the urine pH and was determined by the preceding treatment of the animals in vivo with acidifying or alkalinizing salts. These results demonstrate a previously unrecognized mechanism which contributes to the control of urinary bicarbonate excretion.

Authors

T D McKinney, M B Burg