Studies on the mechanism of thyroid hormone stimulation in vitro of human red cell Ca2+-ATPase activity

The stimulation in vitro of human red blood cell Ca2+-ATPase activity by thyroxine (T4) and triiodothyronine (T3) in physiological concentrations is shown to depend upon binding of iodothyronines to red cell membranes. Calmodulin enhances the activity of thyroid hormone in this model system but there is no direct interaction of calmodulin and hormone.

Factors moderating the effect of oral sulfonylureas on free water clearance

The effects of the antidiuretic agent chlorpropamide and the diuretic agent tolazamide on solute-free water clearance (CH2O) were compared in noninsulin-dependent diabetic patients undergoing water diuresis. Hyperglycemia (fasting serum glucose above 200 mg/dl) obscured the effects of these two sulfonylureas on CH2O. Thiazide or ethacrynic acid enhancement of chlorpropamide antidiuresis was also blunted by hyperglycemia and attendant osmotic diuresis. Thus, the low incidence of symptomatic hyponatremia during chlorpropamide treatment of diabetic patients may be explained by persistent hyperglycemia in such patients.

Comparison of pituitary-thyroid function in patients with endstage renal disease and in age- and sex-matched controls

The response to i.v. bolus thyrotropin-releasing hormone (TRH) of 14 dialysis patients with end-stage renal disease (ESRD) was compared to the response of 14 age- and sex-matched renal clinic patients (controls) with normal renal function (serum creatinine concentrations less than 1.2 mg/dl). The mean basal serum levels of thyrotropin (TSH) were similar in the two groups. There was no difference between the two groups in the mean maximal increase in TSH after TRH (6.3 microU/ml and 7.2 microU/ml in ESRD and control groups, respectively); The rate of fall in TSH from 60 to 90 min after TRH was slower in the ESRD group than in the controls. The mean increase in serum triiodothyronine (T3) concentration after TRH was similar in both groups (25.4 ng/dl, ESRD; 18.4 ng/dl, controls). As previously reported, basal serum T3 content was subnormal in the ESRD patients. Serum thyroxine (T4) concentrations were comparable in control and ESRD groups and did not change significantly during the 90-min TRH test in either group. We conclude that ESRD patients, clinically stable on dialysis, have normal pituitary TRH responsiveness and normal thyroidal response to endogenous TSH secretion, as compared with an age- and sex-matched group of patients with normal renal function. The results of this study support the contention that ESRD patients are eumetabolic.

Relationship of phosphate administration to serum and red cell phosphate concentration, erythrocyte 2,3-diphosphoglycerate (2,3-DPG) and blood P50 in the hyperglycemic dog

In vitro studies indicate that acute increases in intracellular phosphate concentration decrease red blood cell 2,3-diphosphoglycerate levels (G. Momsen, B. Vestergaard-Bogind, Arch Biochem Biophys 190:67, 1978). We have examined the relationship in vivo of serum phosphate concentration, red cell phosphate, 2,3-DPG and blood P50 in hyperglycemic dogs infused alternately with phosphate or chloride (control) solutions. During the 8-hr insulin infusion, serum phosphate (Pi) fell 40% in the chloride-treated animals and rose 71% in the phosphate-treated dogs (P less than 0.001, phosphate vs. control). RBC Pi concentration declined in the controls and rose significantly in the phosphate-infused dogs (P less than 0.02). Serum Pi and RBC Pi were correlated in the phosphate-managed animals (r = 0.76, P less than 0.02), but not in the controls. RBC 2,3-DPG failed to rise in either group during insulin infusion and regression analysis showed a negative correlation between serum Pi and 2,3-DPG (r = -0.90, P less than 0.005) and between RBC Pi concentration and 2,3-DPG (r = -0.84, P less than 0.02). P50 failed to change in either group during insulin treatment and for up to 24 hr after initiation of the 8-hr infusion of insulin.

Thyroid hormone stimulation in vitro of red blood cell Ca2+-ATPase activity: interspecies variation

In vitro susceptibility to thyroid hormone stimulation of membrane-associated Ca2+-ATPase activity has been examined in red blood cells from rat, rabbit, dog, monkey, and man. Monkey and human red cell Ca2+-ATPase activities responded comparably to 10(-10)M T4 or T3. Basal and thyroid hormone-stimulated Ca2+-ATPase activity in rabbit erythrocytes was four-fold higher than in primate red cells. Rat and dog red cell Ca2+-ATPase did not respond to iodothyronines in vitro.

Exclusion of fluid lipid during compression of monolayers of mixtures of dipalmitoylphosphatidylcholine with some other phosphatidylcholines

Monolayers composed of dipalmitoylphosphatidylcholine and one of four fluid phosphatidylcholines have been studied for their ability to attain low minimum surface tension during compression at two different speeds. The minimum surface tension depended on the compression rate and the proportions of the fluid and rigid lipid in the monolayer. The type of fluid lipid used in the monolayer also affected the minimum surface tension.

Lipid fluidity in lung surfactant: monolayers of saturated and unsaturated lecithins

Monolayers of saturated or unsaturated lecithins (PCs) could be compressed to near-zero surface tension (gamma) when they were below the gel-to-liquid crystalline transition temperature (Tc) of the PC, whereas, when above Tc, they collapsed at gamma of 15-23 mN X m-1. Thus PCs with ordered, but not necessarily saturated, chains are required to achieve low gamma. At 37 degrees C the minimum gamma reached by monolayers containing dipalmitoyl PC (DPPC; Tc = 41 degrees C) plus 1-stearoyl-2-oleoyl PC (SOPC; Tc = 6 degrees C) depended on the proportions of the two lipids and the compression rate. When compressed at 1 cm2 X s-1, monolayers of mixtures containing less than 50% SOPC were capable of achieving gamma less than 9 mN X m-1. When the proportion of unsaturated lecithin was high (70%), compression at 1 cm2 X s-1 was insufficient to form a monolayer capable of reaching a very low surface tension. Exclusion of fluid lipid during compression could account for these observations.

Partition of thyroid hormone among erythrocyte cytosol, erythrocyte membrane and human plasma binding sites

The partition of thyroid hormone among binding sites on plasma proteins, erythrocyte (RBC) membranes and cytoplasmic proteins has been examined in the context of recent direct estimates of intracellular RBC thyroid hormone content. Isotopic T3 and T4 uptakes by washed RBCs are identical (greater than 80% of tracer at 4 hr), but RBC binding when RBCs are suspended in plasma favors T3 (10% uptake vs. 2.5% for T4). The RBC cytosol: plasma T3 ratio is 1 : 21.

Gel to liquid-crystalline transition temperatures of water dispersions of two pairs of positional isomers of unsaturated mixed-acid phosphatidylcholines

The gel to liquid-crystalline phase transition temperatures of dispersions of mixed-acid sn-1,2-lecithins which contain one unsaturated and one saturated fatty acid have been studied by differential scanning calorimetry. The temperature for 1-oleoyl-2-palmitoyl-sn-glycero-3-phosphocholine (containing no reversed isomer) was -9.3 degrees C while that for 2-oleoyl-1-palmitoyl-sn-glycero-3-phosphocholine (containing 8% of the reversed isomer) was -2.6 degrees C. The temperature for 2-oleoyl-1-stearoyl-sn-glycero-3-phosphocholine (containing 6% of the reversed isomer) was 6.3 degrees C while that for 1-oleoyl-2-stearoyl-sn-glycero-3-phosphocholine (containing 18% of the reversed isomer) was 8.6 degrees C. The differences in transition temperatures for the isomers of a pair containing the same two acids were consistent with those observed for positional isomers of saturated mixed-acid lecithins in that the isomer of the pair which had the longer fatty acid in the sn-1 position had the lower temperature. The phase transition temperatures of pairs of isomers containing palmitate and oleate at the sn-1 and -2 positions were different by at least 6.7 degrees C, while those containing stearate and oleate were different by at least 2.3 degrees C. Differences in the chain lengths of the fatty acids at the two positions of the glycerol appear to predominate over differences in the depths of the double bonds in the bilayer in determining the transition temperatures.

Microbiological Systems in Organic Synthesis: Preparative-Scale Resolution of ( R S )-Glaucine by Fusarium solani and Stereospecific Oxidation of ( R )-(−)-Glaucine by Aspergillus flavipes

The destructive resolution of (6a R , S )-glaucine (Ic) was accomplished by oxidation of the (6a S )-(+)-enantiomer (Ia), using Fusarium solani ATCC 12823 to yield the unnatural alkaloid (6a R )-(−)-glaucine (Ib). Eighteen cultures were examined for their ability to metabolize the (6a R )-(−)-enantiomer (Ib), and Aspergillus flavipes ATCC 1030 was found to catalyze the stereoselective oxidation of this substrate to didehydroglaucine. Thus, it has been demonstrated that “ R ” and “ S ” organisms exist with regard to the oxidation of aporphines to didehydroaporphines.

Rehabilitation after total laryngectomy

The process of speech acquisition after laryngectomy is described with emphasis on the three principal types of alaryngeal voice (oesophageal, artificial larynx and surgically facilitated voice). Current views on the use of the artificial larynx and factors that may interfere with alaryngeal speech development are discussed. The availability of laryngectomy rehabilitative services in some major centres is surveyed.

Mechanism of hydroxylation of biphenyl by Cunninghamella echinulata

The hydroxylation of [U-2H]biphenyl and [2,2',3,3',5,5',6,6'-2H]biphenyl by Cunninghamella echinulata A.T.C.C. 9244 has been studied. G.l.c.-mass-spectrometry analyses indicate the lack of an isotope effect during the hydroxylation of the perdeuterated substrate. Both g.l.c.-mass spectrometry and 1H n.m.r. were used to definitively demonstrate the presence of a 1,2-hydride-shift during the microbiological hydroxylation of [2,2',3,3',5,5',6,6'-2H]biphenyl.

Microbial transformation of N-methylcolchiceinamide

Seventy-seven microorganisms were examined for their ability to metabolize the antineoplastic agent N-methylcolchiceinamide, an analog of colchicine. Five streptomycetes exhibited significant metabolism, and Streptomyces griseus NRRL B-599 completely converted the substrate to three metabolites. In preparative-scale studies, N-dealkylation resulted in the production of colchiceinamide, the major metabolite (65%), which was characterized by chemical, spectroscopic, and chromatographic comparisons with the standard compound. Two phenolic metabolites resulting from )-dealkylation were also isolated and identified as 2 and 3-O-demethyl-N-methylcolchiceinamide.

Water metabolism in diabetes mellitus

Transcellular shifts of water and changes in the physiology of water excretion are common in diabetes mellitus and its treatment. Recent evidence indicates that hyperglycemia in diabetic patients, but not in normal subjects, is characterized by elevations of circulating levels of arginine vasopressin (AVP; antidiuretic hormone, ADH). The role and importance of these observations remain to be defined since elevations of plasma AVP levels do not decrease water excretion in diabetic patients. Certain oral sulfonylureas, notably chlorpropamide and tolbutamide, are known to decrease renal free water clearance (CH2O), whereas insulin increases CH2O; the insulin and tolbutamide effects may be clinically trivial, whereas that of chlorpropamide is important. The hyponatremic effect of chlorpropamide may be exaggerated in diabetic patients by concomitant diuretic therapy. Euglycemia during chlorpropamide therapy appears to allow full expression of the action of chlorpropamide on CH2O; hyperglycemia with attendant osmotic diuresis protects chlorpropamide-treated patients against hyponatremia. Inhibition of prostaglandin synthesis with nonsteroidal anti-inflammatory agents enhances expression of the ADH effect on the kidney, but it does not appear to potentiate chlorpropamide hyponatremia. Two other oral sulfonylurea agents, tolazamide and glyburide, increase CH2O. Diazoxide is an antihypertensive thiazide which is antidiuretic as well as hyperglycemic. Thus, abnormalities of water metabolism are common in diabetes mellitus. Whether certain of these abnormalities are clinically important depends upon the presence of the osmotic diuresis of hyperglycemia and the pharmacology of diabetic management.

Differential scanning calorimetric studies of the thermotropic phase behavior of membranes composed of dipalmitoyllecithin and mixed-acid unsaturated lecithins

The lecithins 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and 1-stearoyl-2-oleoyl-sn-glycero-3-phosphocholine (SOPC) have been synthesized by reacylation of the appropriate lysolecithins with fatty acid anhydrides. These lecithins have been used to make model membranes in mixtures with dipalmitoyllecithin (DPPC), and phase diagrams of the two bilayer systems have been constructed. These diagrams show that there is essentially no gel-state miscibility in the POPC-DPPC bilayers at any composition, and that SOPC-DPPC bilayers show gel-state immiscibility at DPPC concentrations of less than 50 mol%, and partial miscibility above 50 mol% DPPC. Analysis of the POPC-DPPC phase diagram on the assumption of athermal solution in the liquid-crystalline phase shows that the two lipids mix nearly randomly above the phase transition. The liquidus curve of SOPC-DPPC bilayers showed deviations from calculated ideal behaviour, which indicated that there is a small excess tendency for the formation of pairs of like molecules in SOPC-DPPC bilayers in the liquid-crystalline phase. Thus, in the liquid-crystalline phase, SOPC and DPPC do not pack quite as well as do POPC and DPPC.

Convenient synthesis of (S)-(+)-apomorphine from (R)-(-)-apomorphine

A method was devised for preparing (S)-(+)-apomorphine from (R)-(-)-apomorphine. Dehydrogenation of the dimethyl ether of (R)-(-)-apomorphine with 10% palladium-on-carbon followed by reduction with sodium cyanoborohydride under acidic conditions resulted in quantitative racemization to give (R,S)-apomorphine dimethyl ether, which then was resolved with (-)-tartaric acid. Ether cleavage of (S)-(+)-apomorphine dimethyl ether (-)-tartrate with hydriodic acid in acetic anhydride yielded (S)-(+)-apomorphine, which was isolated as the hydrochloride salt in 99% enantiomeric excess.

A computer-assisted examination resource

A computer program (MICHELE) has been written to facilitate preparation by medical faculty of reference examination questions based on a 'core curriculum'. Questions may be used by faculty to test student command of coursework and by students at their initiative to assess their progress. Students may also use the program to direct their future studies according to computer-generated suggestions. MICHELE is a medical-instructional, computer-handled evaluation and learning enhancement system which consists of access, executive, author-instruction, student and statistics subsystems. These subsystems guarantee security of the data base, generate examinations according to category, difficulty and format (true--false, multiple choice, case history), generate practice sessions for students and student self-tests, and analyze the individual and cumulative results of examination and self-test sessions. The program is directed primarily toward evaluation of performance and instruction in the clinical disciplines; in this setting it is desirable to develop a sequence of unique, equally weighted examinations throughout the academic year and, at the same time, encourage mastery of core material encompassed in the data base. MICHELE is written in CDC FORTRAN IV and utilizes an indexed sequential file organization for the data.

Interaction of thyroid hormone and hemoglobin. I. Nature of the interaction and effect of hemoglobin on thyroid hormone radioimmunoassay

Gel filtration of human RBC lysate incubated with labeled T4 or T3 revealed co-elution of a major iodothyronine-binding fraction (R-2) and hemoglobin. Solutions of purified human hemoglobin and T3 also showed co-elution of hormone and hemoglobin. Because hematin and protoporphyrin were shown to bind labeled T3, the oxygen-binding site on hemoglobin was excluded as the site of iodothyronine-hemoglobin interaction. Analysis of hormone binding by heme and globin moieties showed T3 binding to be limited to the heme fraction. Addition of excess unlabeled T3 to hemoglobin or heme incubated with labeled T3 indicated 75% to 90% of hormone binding was poorly dissociable. These observations suggested that the presence of hemoglobin in RBC lysate or in serum could influence the measurement of T4 and T3 by specific RIA. Subsequent studies of the addition to serum of human hemoglobin revealed a significant reduction in T3 and T4 detectable by RIA in the presence of this protein. The effect was influenced by the concentration of hemoglobin and by duration and temperature of incubations of hemoglobin and serum prior to RIA. Incubated for 5 days at 4 degrees C, 14 sera containing 10 gm/dl hemoglobin showed a mean decrease in T3 concentration of 40% compared to sera incubated in the absence of hemoglobin (160.1 to 93.9 ng/dl, p less than 0.001); detectable serum T4 fell by 50% in 13 sera incubated under the same conditions (5.40 micrograms/dl without hemoglobin to 2.55 micrograms/dl in the presence of hemoglobin, p less than 0.001). Hemoglobin concentrations in serum as low as 0.1 and 0.5 gm/dl affected the RIAs significantly. Thus a major fraction of thyroid hormone binding in human RBC cytoplasm is accounted for by an interaction with hemoglobin. This interaction in serum or RBC lysates is a significant variable affecting iodothyronine determinations.

Estimation of intracellular free triiodothyronine in man

T3 RIA and measurements of dialyzable fraction T3 (DFT3) have been applied to human erythrocyte (RBC) cytoplasm in order to quantitate the intracellular free T3 (FT3) concentration in man. Mean intracellular T3, DFT3, and FT3 in RBCs from four normal subjects were, respectively, 12 ng/dl, 1.25%, and 0.15 mg/dl. These values were 10%, 450%, and 44% of those of T3, DFT3, and FT3 in plasma obtained from the same subjects. In RBCs from four hyperthyroid subjects, the mean cytosol DFT3 was slightly increased compared to euthyroid RBCs. Because intracellular T3 concentration was increased 8-fold, however, the cytosol FT3 was frankly elevated relative to euthyroid state cells. Thus, intracellular T3 and FT3 measurements have been shown to be feasible in the human RBC and confirm that increases in extracellular free T3 in fact accompanied by elevations of intracellular free hormone.

Binding of thyroid hormone by human erythrocyte cytosol proteins

Gel filtration (G-100, 0.01 M Tris, pH 7.4) of post-100,000 x g supernatant from lysate of washed human erythrocytes (RBC) revealed 3 fractions (R-1, R-2, R-3) which bound labeled T3 and T4. Major peak R-2 emerged with the mehoglobin fraction (A560 nm) and binding by this fraction was partially dissociable; the dissociable site bound D-T4, but not tetraidothyroacetic acid or reverse T3. Non-dissociable binding characterized peaks R-1 and R-3. R-1, R-2, and R-3 were pronase-digestible and R-1 binding was acid-unstable (pH 6.8 vs. 7.4). Evidence developed herein and elsewhere indicates that hemoglobin, itself, accounts for the binding within fraction R-2. Intact RBCs maintained for 72 hr at 4C in buffer enriched with T3 or T4 showed progressive incorporation with time of iodothyronines into the hemoglobin fraction.

N-demethylation of lergotrile by Streptomyces platensis

Thirty-eight microorganisms were screened for their ability to produce metabolites of the semisynthetic alkaloid, lergotrile. A total of five microorganisms were found to biotransform lergotrile, and N-desmethyl lergotrile was detected as the principal metabolite with most organisms. Streptomyces platensis (NRRL 2364) appeared to form the metabolite in highest yield, and a preparative-scale conversion was accomplished with a recovered yield of 50%. Structure proof was accomplished with comparative thin-layer chromatography, mixed melting point, mass spectrometry, and remethylation to lergotrile.

A mechanism for secretory IgA-mediated inhibition of the cell penetration and intracellular development of Eimeria tenella

The ability of Eimeria tenella sporozoites to develop normally in cultured chick kidney cells was used as an indicator of the anticoccidial effects of sera and extracts of caecal contents or tissue. Pre-treatment of sporozoites with normal serum globulin enhanced the frequency of intracellular development but pre-treatment in balanced salt solution, without protein, damaged sporozoites so that most had lost the ability to differentiate, even when they were able to invade host cells. The same inhibitory effect was seen when sporozoites were incubated in extracts of caecal contents from non-immunized chickens, although parasitic development was unaffected when sporozoites were pretreated in similar extracts of mucosae. Extracts of immune caecal contents impaired both cell penetration and subsequent development. These results show that sporozoites can lose the ability to differentiate before the ability to penetrate cells and provide evidence of a possible synergism between non-specific factors and secretory antibodies in anticoccidial immunity.

The role of secretory IgA in anti-coccidial immunity in the chicken

The serological and secretory immune responses of the chicken to infection with Eimeria tenella were evaluated in terms of various anti-coccidial activities. Serological responses were detected in the forms of precipitating, sporozoite neutralizing, anti-merozoite and anti-schizont antibodies. Similarly, anti-schizont and sporozoite neutralizing activities were found in caecal contents (containing mainly IgA) from infected birds and these also had the capacity to damage second generation merozoites. Moreover, the functional importance of IgA could be implied from the substantial predominance of IgA synthesizing cells in the intestinal immunocyte response as revealed by immunohistology. This was reflected in the immunoglobulin profile of caecal contents, for primary and secondary infection resulted in elevated levels of IgA whilst IgG and IgM generally remained extremely low or were usually undetectable. Taken with the well established lack of correlation between serum antibody and protection, these results suggest that the intestinal secretory IgA system plays an essential role in the protective immune response to E. tenella.

Adrenal hemorrhage in the adult

Bilateral adrenal gland hemorrhage was found in 22 of 2,000 (1.1%) consecutive general hospital autopsies. Clinical features of these 22 patients with diffuse or focal bilateral adrenal hemorrhage have been analyzed and compared with previous series. In our experience, patients with this postmortem finding rarely manifest features of adrenocortical insufficiency and appear instead to die as a consequence of concomitant overwhelming illness, such as septicemia, body surface burns or cardiovascular catastrophe. Two-thirds of the current series had impaired renal function at the time of adrenal hemorrhage and three patients had pituitary gland necrosis. Experimental and clinical observations indicate that the "stressed" adrenal gland--under substantive endogenous or exogenous ACTH stimulation--is unusually susceptible to hemorrhage. While our own experience indicates that bilateral adrenal hemorrhage can infrequently be implicated as a factor contributing to patients' death, the possibility of adrenocortical insufficiency must be considered in patients at risk for adrenal hemorrhage. Such patients are those who are azotemic and have bacteremia, burns, or recent cardiovascular catastrophe, particularly when the latter is managed with anticoagulant administration. In these patients, unexplained clinical deterioration or the appearance of findings consistent with adrenocortical insufficiency mandate measurement of serum cortisol concentration and institution of stress-level corticosteroid replacement therapy until a diagnosis of acute adrenocortical insufficiency can be established or refuted.

Computerized surveillance of diabetic patient/health care delivery system interfaces

DIASURV is a computerized surveillance program developed to monitor the interaction of a large cohort of diabetic patients with a tertiary care institution. The input of this simple program consists of a file of diabetic patients, the daily census of hospital inpatients, and the daily census of hospital outpatients. Written in COBOL, the program consists of edit and file-maintenance components and inpatient and outpatient search components. The output is a daily listing of all inpatient (x- = 60) and outpatient transactions (x- = 20) for the cohort of 1,800 patients. The output also summarizes previous exposures of patients to specific bedside and classroom activities in diabetes education. DIASURV has a variety of applications in terms of organization of teaching efforts and facilitated access to a limited amount of patient management information.

Regiospecific synthesis of isoapocodeine from 10,11-dimethoxyaporphine by using Cunninghamella elegans

A preparative-scale regiospecific conversion of 10,11-dimethoxyaporphine to isoapocodeine was conducted with Cunninghamella elegans ATCC 9245. This biotransformation proceeded quantitatively in suspensions and was pH dependent. The influence of antioxidants on the conversion was studied. Attempts to preserve the activity of isolated C. elegans cells by a number of methods were unsuccessful.

Physical characteristics of insulin receptors on renal cell membranes

Certain physical characteristics of the insulin-kidney-membrane interaction in dog renal cortex have been defined. Two classes of binding sites were identified: the high-affinity-low-capacity site had a Ka of 1.3 × 109 M1 and a capacity of 43 fmols per milligram membrane protein. The lower-affinity site Ka was 3.7×107 M-1. Saturabili t y of receptor sites could not be demonstrated at any insulin concentration. At 21° C, binding of insulin was maximal after 60 minutes of incubation, with a t1/2of <1.0 minute. Specific binding of 125I-insulin was proportional to protein concentration when the fraction of insulin bound was not excessive. Proinsulin and desoctapeptide insulin displaced labeled insulin in proportion to their known biologic activities (insulin>proinsulin>desoctapep-tide insulin). Arginine vasopressin and glucagon did not compete with native (labeled) insulin for binding sites. The kinetic properties of the kidney insulin-receptor sites are similar to those previously reported for liver and fat cell receptors.

A comparison of specific binding of 125I-insulin to kidney and liver membranes in the presence of various cation concentrations showed no enhancement of binding in either tissue by NaCl as high as 2 M and KC1 up to 50 mM. In contrast, 25 mM CaCl2 caused an increase in specific binding from 3.8 to 7.7 fmols 125I-insulin per milligram protein in kidney and from 1.0 to 2.1 fmols per milligram protein in liver. MgCl2 (10 mM) increased binding of insulin from 3.5 to 7.3 fmols per milligram in kidney and from 1.0 to 2.1 fmols per milligram in liver. EDTA (2mM) had no intrinsic effect on binding but reversed (by 50 per cent) the Ca2+ -mediated enhancement of binding. Divalent cations appeared to influence both high and low affinity sites.

125I-insulin degradation occurred as a function of total insulin concentration in the kidney membrane system and reduced the amount of “bindable” free hormone. The process was not saturable below 10-6 M insulin. Degradation effects influenced calculated equilibrium constants to a minimal degree.

Serum total and free thyroxine and triiodothyronine during dynamic muscular exercise in man

The effect of strenuous dynamic muscular exercise on serum-free thyroxine (FT4) and free triiodothyronine (FT3) concentrations has been studied in 10 healthy subjects. In the course of 7.8-19 min of treadmill exercise (protocol of R. A. Bruce), the group showed a mean increase in serum albumin concentration of 11.4% (P less than 0.01). Five subjects demonstrated an increase in FT4 concentrations (x = +54%) and five showed decreased FT4 (x = -36%). The difference in FT4 concentrations was accounted for primarily by acute alterations in dialyzable fraction T4 (DFT4) rather than total serum T4. Mean changes in DFT4 were statistically significant (P less than 0.02) when increased FT4 and decreased FT4 groups were compared. Acute exercise was accompanied by a 9% decrease in dialyzable fraction T3 (DFT3) (P less than 0.02) in the 10 subjects, but the concomitant decrease in FT3 concentration was not significant. Changes in DFT4 and DFT3 and FT4 and FT3 concentrations were not correlated. Trends in double product (heart rate times blood pressure) with maximal exercise and in double-product recovery after exercise suggested that increased FT4 concentrations developed in subjects who were physically better trained.

Microbial transformations of natural antitumor agents. 3. Conversion of thalicarpine to (+)-hernandalinol by Streptomyces punipalus

Microbial transformation studies were conducted with the antitumor alkaloid thalicarpine. Streptomyces punipalus (NRRL 3529) converted thalicarpine to (+)-hernandalinol, the structure of which was determined spectroscopically and by synthesis from the known alkaloid hernandaline. This unusual biotransformation reaction most likely occurs by oxidative cleavage of the isoquinoline ring from thalicarpine through the intermediate hernandaline, which then undergoes further reduction to hernandalinol.

Microbial transformations of natural antitumor agents. IV. Formation of N-(2)-nor-d-tetrandrine by Cunninghamella blakesleeana (ATCC 8688a)

Microbial transformation experiments have been conducted with the antitumor alkaloid, d-tetrandrine. The alkaloid is selectively demethylated at the N-(2)-position by Cunninghamella blakesleeana ATCC 8688a. The biotransformation reaction is highly selective and uncomplicated by side-product formation. N-demethylation of the alkaloid using methylchloroformate is not regio-specific. Procedures used in screening microorganisms for their abilities to yield metabolites of d-tetrandrine are evaluated.

Thyroid function and metabolic state in chronic renal failure

Thirty-eight patients with chronic renal insufficiency who were in a dialysis program underwent studies of thyroid function and metabolic status. Mean values for serum total and free thyroxine (T4) concentrations and thyroxine-binding globulin capacity were within normal limits. Although mean serum total triiodothyronine (T3) concentration was normal, 43% of the group had low serum T3 and 54% had low serum free T3 concentrations. Serum thyrotrophin (TSH) concentrations were normal in all but four subjects who had very slight elevations. Metabolic status was assessed by various metabolic tests; mean values for each of these tests were normal, and the clinical index scores indicated that all patients were euthyroid. Results of metabolic testing were similar in patients with low and those with normal serum T3 concentrations. Low serum T3 measurements did not accurately reflect metabolic state in patients with chronic renal failure, whereas serum free T4 and TSH concentrations were reliable indicators of thyroid state.

Changes in serum thyrotropin (TSH) in man during halofenate administration

Halofenate, a serum lipid-lowering agent which inhibits binding of thyroid hormone to thyroxine-binding globulin (TBG), was administered daily for 14 days to 8 hypothyroid subjects with elevated TSH concentrations as a result of incomplete thyroxine (T4) therapy. Drug administration resulted in mean increases in serum dialyzable fraction T4 (DFT4) of 52% over pretreatment levels (P less than 0.01) and in dialyzable fraction triiodothyronine (DFT3) of 26% in 7 subjects, (P less than 0.01). During halofenate treatment in these 7 subjects, serum TSH concentrations decreased significantly (mean = 39%, P less than 0.01) when DFT4 and DFT3 were increased by halofenate. In only two subjects was there a convincing temporal relationship between increased serum absolute free T4 (AFT4) and decreased serum TSH concentrations. Contrary to what would be predicted from the "free hormone hypothesis", changes in serum TSH concentration in these hypothyroid patients appeared to relate primarily to changes in the free fraction of circulating T4 and T3 (DFT4, DFT3), rather than to alterations in AFT4 or AFT3. Halofenate did not alter serum TBG binding capacity. An eighth subject did not show increased DFT4 and DFT3 during halofenate treatment despite achievement of therapeutic serum levels of the agent; in this patient, serum TSH levels rose progressively throughout the period of inadequate T4 replacement and halofenate administration. In hypothyroid patients, short-term halofenate use suggests that the pituitary-thyroid hormone feedback circuit can respond to increases in serum DFT4 and DFT3 in the absence of detactable increases in absolute free hormone concentrations.

Formation of indole-3-carboxylic acid by Chromobacterium violaceum

l-Tryptophan is converted to indole-3-carboxylic acid by growing cultures and resting cell suspensions of Chromobacterium violaceum

Serum beta -- lipoproteins: studies in a patient and in guinea pigs after the ingestion of organophosphorus compounds

A patient admitted to this hospital with Parathion poisoning had a marked reduction in serum cholinesterase activity and concentration of low density lipoprotein. The enzyme and the lipoprotein levels returned to normal with clinical recovery. Guinea pigs treated with phospholine iodide showed depressed levels of serum cholinesterase and beta-lipoprotein. It is suggested that the decrease in beta-lipoproteins is due to the decrease in cholinesterase activity.