Showing papers by "University of Texas Southwestern Medical Center published in 1970"

Effect of Anterior Pituitary Perfusion and Intraventricular Injection of Catecholamines and Indoleamines on LH Release

Abstract: The median eminence, pituitary stalk and anterior pituitary as well as the adjacent diencephalon were exposed through a parapharyngeal approach to enable us to visualize these structures directly and to inject isotonic salt solutions containing dopamine, epinephrine, norepinephrine, serotonin or melatonin into the third ventricle, a stalk portal vessel or the basilar artery of anesthetized male rats. The rate of LH release in these animals was evaluated from the changes in the concentration of serum LH as determined by radioimmunoassay. Within 10 min after 1.25 μg of dopamine hydrochloride was injected into the third ventricle, the serum LH concentration had increased 4-fold. After 20 min, the serum LH level had increased 9-fold. At 30 and 60 min after the injection, there was a moderate decline followed by a steady rise for at least 1 hr. At the end of the 120-min observation period, the serum LH level was 20 times greater than that of the control animals which received an isotonic salt solution only. Fo...

Production of Highly Purified Choleragen and Choleragenoid

Abstract: It is now generally accepted that the diarrhea of cholera is brought about by the action of an exoenterotoxin elaborated by cholera vibrios in the small bowel. This development, while significant of itself, raises a number of questions that must be resolved before it can be applied to the problem of the disease in man. The questions of primary importance are: (7) can effective antitoxic immunity be elicited in man, and, if so, does it offer any significant advantage over currently used antibacterial immunity or any improvements that may be anticipated in that area [1-3]; (2) by what means, at the cellular and subcellular levels, does the enterotoxin cause the outpouring of fluid and electrolytes; and {3) how can this process, once initiated, be attenuated or completely halted short of its natural progression. In order to provide answers to these and other questions, it seems evident that one must first have sufficient amounts of toxin purified to such a degree that it will serve the purpose of the desired study. In order that field

The intranuclear metabolism of testosterone in the accessory organs of reproduction.

Abstract: Publisher Summary This chapter discusses the intranuclear metabolism of testosterone in the accessory organs of reproduction. Testosterone is taken up by nuclei of the accessory organs of male reproduction. Within these nuclei, testosterone may undergo at least two fates; it may either be bound to a protein of the chromatin or it may be reduced to dihydrotestosterone prior to or as a step in the binding process. The implications of these events in regard to the mechanism of action of the hormone are unclear. On the one hand, it is possible that specific testosterone metabolites may have different effects within a single target tissue. It seems more likely, however, that the various metabolites have different binding affinities for the same binding site(s) and that any differences in the effects of different metabolites can, as a consequence, be explained in qualitative terms. The physiological meaning of dihydrotestosterone formation is also uncertain. On the basis of the remarkable growth-promoting effects of dihydrotestosterone on prostate both in vivo and in organ culture, the correlation between the rate of dihydrotestosterone formation in skin of man and the known growth response of the skin to testosterone, and the striking relation between prostatic growth in different species and the rate of this conversion, it is tempting to speculate that dihydrotestosterone formation may have some special relation to the growth-promoting effects of testosterone.

Regulation of cholesterol biosynthesis in normal and malignant tissues.

Abstract: Publisher Summary This chapter discusses the major biochemical and subcellular characteristics of the systems that regulate cholesterol synthesis in the liver and in the intestine. The rate of cholesterol synthesis in the livers of higher animals is controlled primarily by a sensitive negative feedback system, and to a lesser extent, by caloric intake. Bile acids do not play a direct role in regulation of cholesterol synthesis in the liver. Cholesterol synthesis in the intestine of higher animals has been shown to be controlled by a similar feedback control mechanism; however, the feedback inhibitor consists of bile acids rather than cholesterol. Phylogenetic studies indicate that, in contrast to the case in higher animals, in nonmammalian vertebrates, cholesterol synthesis in the intestine is regulated by cholesterol itself. The most striking defect in the control of cholesterol synthesis so far observed involves the consistent loss of the cholesterol feedback system in all hepatomas.

Thyroid peroxidase and thyroxine biosynthesis.

Abstract: Publisher Summary This chapter primarily discusses the results obtained in the preparations of purified thyroid peroxidase. Two different preparations of thyroid peroxidase were used for the studies described in the chapter. The first preparation, referred to in this chapter as Prep. I, was isolated by a procedure. The second one is more highly purified preparation, isolated by a modified procedure described and is referred to as Prep. II. In a study described in the chapter, the specific activity of Prep. II was about five times greater than that of Prep. I. The molecular weight of thyroid peroxidase was determined by filtration through a calibrated column of Biogel P-100. The proteins of known molecular weight used to calibrate the column were myoglobulin (17,800), ovalbumin (45,000), and bovine serum albumin (67,000). Each of these proteins was separately applied to the column and eluted; the elution volume was determined on the basis of measurement of absorbance at 280 mμ. The elution volume of thyroid peroxidase was then determined, based on its iodide peroxidase activity. A plot of effluent volume against log molecular weight for the marker proteins yielded a straight line, and the molecular weight of thyroid peroxidase determined from this standard curve was 62,000. This is in very close agreement with the value of 64,000 reported in another study for a different preparation of the enzyme. The molecular weight of a sample of purified horseradish peroxidase (Calbiochem) determined on the same column was 42,000, in close agreement with the reported value of 40,000.

Mono- and Indolamines and Control of LH Secretion

Abstract: To determine the effect of biogenic amines on LH release in rats, blood samples were drawn by cardiac puncture in etheranesthetized animals bearing chronic cannulae in the third ventricle (3rd V) immediately before and 15 min after intraventricular injection of various drugs. In the interim between removal of the 2 blood samples the rats recovered from anesthesia. Plasma LH was measured by radioimmunoassay. Serotonin (5-HT) did not alter plasma LH levels significantly at any stage of 4-day estrous cycles. Norepinephrine (NE) also failed to produce over-all significant changes in plasma LH although there were some positive responses. Dopamine (DA) raised LH to levels as high as 8- or 10-fold above controls (p<.01) in rats on the 2nd day of diestrus (D2) or in proestrus (P). DA proved to be less effective in Dl or estrus (E). In normal males DA raised plasma LH in 5 out of 9 animals (p<.02), whereas NE was ineffective. The effect of DA in D2 and P rats could be blocked by simultaneous 3rd V injection of 30 ...

Further Cytophysiologic Evidence for the Identity of the Cells That Produce Adrenocorticotrophic Hormone1

Abstract: To provide further evidence for the identification of the cell type responsible for the production of adrenocorticotrophin (ACTH), the effects of acute and chronic administration of cortisol on the cells of the pituitaries of intact and adrenalectomized rats were studied by electron microscopy. Hypertrophied ACTH-cells, previously described as adrenalectomy-cells, were scarce in controls and became more numerous after adrenalectomy. Adrenalectomy-cells are characterized by their secretory granules, which are dense, sparse, and measure 200 μn or more in maximal diameter, and by the irregularity of their cell outlines, determined by their interior position in the cell cords and their tendency to send processes of cytoplasm around neighboring cells toward the capillaries. Normal ACTH-cells are identified by similar criteria, although they are less voluminous and their cell outlines tend to be less complex and varied. Acute administration of cortisol caused a striking accumulation of secretory granules in bot...

Water, sodium chloride, and food intake induced by injections of cholinergic and adrenergic drugs into the third ventricle of the rat brain.

Abstract: SummaryThe effects of microinjection of adrenergic and cholinergic drugs and hypertonic saline into the third ventricle on the intake of water, hypertonic salt (NaCl) solution, and food were studied. Carbachol induced a dramatic, rapid, 15-fold increase in water intake, whereas none of the other drugs were active. Both carbachol and isoproterenol evoked large increases in salt intake. Again, all other drugs failed to produce significant effects. Food intake was increased by the following adrenergic compounds: epinephrine, norepinephrine, metaraminol, isoproterenol, and dopamine. Carbachol was also effective in augmenting food intake but the effect was delayed. Hypertonic saline produced a delayed increase in both water and food intake but did not alter salt intake. The results are interpreted to mean that a cholinergic synapse lies in the pathways which mediate water intake, whereas both cholinergic and adrenergic synapses may be involved in the mediation of salt and food intake.

Relationship of Plasma Digitoxin and Digoxin to Cardiac Response Following Intravenous Digitalization in Man

Abstract: The value of plasma digitalis determinations will depend upon the accuracy with which they mirror the myocardial effects of digitalis. Ten volunteers received 0.8 mg of digitoxin intravenously, and after 2 hours the mean plasma digitoxin level was 45.6 ± 6 mµg/ml but declined over 4 to 6 hours during plasma-tissue equilibration. The cardiac response, as indicated by decreases in the left ventricular ejection time index (LVETI) and Q-S2 intervals ( P < 0.01), was present at 2 hours and reached maximum at 4 to 6 hours. Subsequently, plasma level, LVETI, and Q-S2 changed in the same direction during slow excretion. Six subjects received 1.0 mg of digoxin intravenously. Mean plasma digoxin at 30 min was 6.8 ± 0.3 mµg/ml; it fell after 3 to 4 hours to levels usually seen during maintenance digoxin administration (<3 mµg/ml) and then declined more slowly. Correlation of individual digoxin levels with ΔLVETI values during the first 4 hours was significant ( P < 0.01). The half-life (T½) for the dominant slope of the plasma curve was 30.5 hours by plasma determinations and 29 hours by LVETI determination. Plasma levels of digitoxin and digoxin were related to their cardiac effects under the conditions studied. Prior to plasma-tissue equilibration, plasma determinations of digoxin and digitoxin will be higher than levels seen during maintenance administration of these drugs.

Studies of isolated synovial lining cells of rheumatoid and nonrheumatoid synovial membranes

Abstract: Synovial membranes from patients with rheumatoid arthritis and other arthritides were digested with tryps.n to produce suspensions of synovial cells. The cells were stained by the direct fluorescent antibody technique for IgG, IgM and the β1c (C3) component of complement, using fluorescein and rhodamine isothiocyanate-labeled antisera. A characteristic diffuse staining pattern for IgG and β1c was observed in the cytoplasm of the phagocytic lining cells of rheumatoid synovium. In seropositive patients, inclusions containing IgG, IgM, and β1c were also stained in these cells. The role of these immunoglobulins, localized in the lining cells, is discussed in relation to rheumatoid inflammation.

Depression of cardiac function by streptomycin and other antimicrobial agents

Abstract: Signs of toxicity of the eighth cranial nerve in a patient receiving streptomycin who also had persistent hypotension after cardiac surgery led to investigation of the effects of streptomycin and other antibiotic agents on cardiac function. In 18 open chest dogs, there was a dose-dependent depression of cardiovascular function as a result of the intravenous administration of streptomycin in doses of 2.5, 10 and 40 mg/kg. Similar depressions were demonstrated after administration of tetracycline, kanamycin, vancomycin, erythromycin and colymycin. In 4 intact dogs given streptomycin, 2 g intramuscularly, cardiac output decreased 26 percent and mean arterial pressure decreased 22 percent 1 hour after administration. The average level of streptomycin in the blood at 1 hour was 35 μg/ml, within the usual therapeutic range for patients. In the isolated perfused cat heart, streptomycin, tetracycline, kanamycin, vancomycin and chloramphenicol caused a profound decrease in contractile force. These data should not be extrapolated directly to clinical situations since most of the experiments did not parallel precisely the usual form of antibiotic administration. In the presence of infection, antibiotic drugs are among the most effective agents available. However, the physician must be aware of the potential for cardiac depression, especially in patients with an already compromised cardiac status or with impaired renal function.

Factors influencing the inhibitory effect of carbon monoxide on cytochrome P-450-catalyzed mixed function oxidation reactions.

Abstract: Liver microsomal reactions under conditions of high rates of electron flux were more CO sensitive, and the Warburg partition coefficient for CO and O/sub 2/ with cytochrome P-450 was increased.

Effects of a Quantitated Physical Training Program on Middle-Aged Sedentary Men

Abstract: The effects of a 15-week quantitated training program were evaluated in nine men, 32 to 59 years old. All had been blind for 10 years or more but were otherwise in good health. They were sedentary with a stable activity pattern. Training sessions were held three times per week and consisted of four 3-minute exercise periods on a bicycle ergometer, each followed by a rest period of equal duration. Heart rates at the end of the fourth exercise period averaged 27 beats below individual maximal heart rates. Maximal oxygen uptake increased from 24.0 to 28.5 ml/kg x min or by 19%. Total heart volume and mean serum cholesterol decreased significantly, and psychological tests showed improvement. Five subjects continued exercising at the same intensity but only once weekly for another 14-week period. Mean maximal oxygen uptake decreased to 6% above the control level. Four subjects who discontinued training after 15 weeks were retested at the same time and had a mean value 5% below control maximal oxygen uptake.

Mitochondrial Mineralization in Human Myocardium

Abstract: The purpose of this study was to determine the precise localization of intracellular myocardial mineralization after vascular surgery in two patients. By light microscopy the calcification was represented by discrete basophilic granules. Alizarin red S and von Kossa preparations confirmed the presence of calcium salts. Myocardial tissue from the paraffin blocks and formalin-fixed autopsy tissue were examined by means of the electron microscope; the principal site of mineralization was within mitochondria. The crystalline appearance of the intramitochondrial deposits suggested the presence of hydroxyapatite. The exact mechanism involved in this deposition is not known.

Acute Effects of Ethanol Ingestion on the Response to Submaximal and Maximal Exercise in Man

Abstract: The acute effects of ingestion of ethanol on the response to submaximal and maximal exercise were studied by noninvasive technics in a group of eight healthy men, ages 21 to 33 (series I). Cardiac output (dye-dilution technic) and intra-arterial pressures were measured in a separate series of experiments in a subgroup of four subjects (series II). Mean concentration of ethanol in the blood at the end of the experiment was 156 mg/100 ml in series I and 125 mg/100 ml in series II. Heart rates at rest and during submaximal exercise were higher after ingestion of ethanol, but there was no effect on stroke volume. After ingestion of ethanol cardiac output at rest and during submaximal exercise increased, and total A-V difference and total peripheral resistance decreased. The circulatory response to maximal work was not affected by ethanol. Maximal oxygen uptake did not change. Pulmonary ventilation was not altered during submaximal exercise but was reduced during maximal work. These findings are in agreement w...

Prolactin-inhibiting activity in hypophysial stalk blood and elevation by dopamine

Abstract: Des moities d'hypophyse incubees dans du plasma de la tige hypophysaire secretent moins de prolactine que les moities complementaires incubees dans du plasma de sang peripherique. Les glandes incubees dans du plasma de la tige hypophysaire de rats traites a la dopamine secretent moins de prolactine que celles incubees dans le plasma des rats temoins. L'activite inhibitrice de la prolactine dans le plasma de la tige hypophysaire peut Etre le resultat d'un facteur particulier, et la secretion de ce facteur serait gouvernee par un mecanisme «dopaminergique».

Action of dopamine to induce release of FSH-releasing factor (FRF) from hypothalamic tissue in vitro.

Abstract: After a 30-min preincubation period, anterior pituitaries alone or anterior pituitaries + stalk median eminence fragments were incubated for 6 hr in medium 199. Media were assayed for FSH concentration by the method of Steelman and Pohley. Incubation of anterior pituitaries in the presence of stalk median eminence tissue resulted in a slight increase in FSH release. If the combined stalk median eminence + anterior pituitary tissue was incubated with 1–5 μg/ml of serotonin, epinephrine or norepinephrine, basal release of FSH was unaltered. When dopamine was added to the incubation medium in doses of 2.5–5 μg/ml, FSH release was significantly increased (p < .01), and a dose-response relationship was observed. Dopamine in similar doses failed to alter FSH release from anterior pituitaries incubated alone. Dopamine, epinephrine, norepinephrine or serotonin at doses of 5 μg/ml did not alter the FSHreleasing action of partially purified ovine FRF. The response to dopamine was completely inhibited by 20 μg/ml of...

Monospecific Equine Antiserum Against Cholera Exo-Enterotoxin

Abstract: mouse footedema. Theserum was foundtobeuseful forassaying toxin antigen incrude andrefined products byinvitro testssuchas radial immunodiffusion, Lf,andquantitative precipitin titrations. Basedupon experimental observations, theserum was defined ascontaining 1,000 fl3cculating units ofanticholera toxin antibody perml.A flocculating dose, orLf,ofcholeragen approximates 1 MAg,andthatofcholeragenoid is0.625 ,lg. Formalin toxoids behavedlike theparent toxin inthese tests. Theserum contains approximately 2.2 mg ofantibody protein perml,whichappearstobelargely, ifnotentirely, of theIg(T) type. Itissuggested thatthis serum,whichisavailable inconsiderable supply, beconsidered foruseasa reference cholera antitoxin. Thehorse developed symptomsofanaphylactic shockduring immunization, suggesting theneedfor caution inprojected studies on toxoid-induced immunity inman. Thecholera exo-enterotoxin, which wasdesignated choleragen, hasbeenisolated andpurified inthis laboratory along witha natural toxoid whichwecall choleragenoid (5,6).Results ofa variety oflaboratory studies havegiven rise tothe hopethat anantitoxic cholera vaccine mayelicit better andlonger lasting immunity tocholera thanthat afforded byconventional, killed cellular vaccines. A field study totest this hypothesis with aFormalin toxoid iscurrently under active consideration. Ifhistory repeats itself, itmaybepossible to apply, incholera research, theclassical immunological techniques which haveproven souseful in other toxin-mediated diseases, suchasdiphtheria andtetanus. Accordingly, we undertook the preparation ofalarge quantity ofamonospecific equine antitoxic serumwhichmight serveasan international reference forfuture immunological studies incholera. Sucha serumcould beespecially useful asareagent foranalyzing thetoxin antigen content ofimmunizing preparations by radial immunodiffusion (5), Lf,andquantitative precipitin procedures. Theresults ofthepresent study indicate that this isindeed thecase. MATERIALSAND METHODS