Adductor spastic dysphonia: heterogeneity of physiologic and phonatory characteristics

Physiologic and phonatory characteristics of 23 subjects with adductor spastic dysphonia were studied, including examination of the laryngeal appearance by fiberoptic nasoendoscopy, neurologic examination, and measurement of phonatory airflow and speaking fundamental frequency. These characteristics displayed considerable heterogeneity among the subjects investigated. Three patterns of laryngeal appearance during phonation were observed: vocal fold adduction, associated ventricular fold constriction, and approximation of the laryngeal inlet. Eight of 13 subjects demonstrated some neurologic abnormality. For the majority of subjects, the airflow demonstrated marked variability during sustained phonation; for different subjects, this variability was observed to be associated with either an oscillatory or irregular airflow pattern. The modal speaking fundamental frequency for the women and men with adductor spastic dysphonia was not significantly different from that for age- and sex-matched controls.

Action of long-chain fatty acids in vitro on Ca2+-stimulatable, Mg2+-dependent ATPase activity in human red cell membranes

Human red cell membrane Ca2+-stimulatable, Mg2+-dependent adenosine triphosphatase (Ca2+-ATPase) activity and its response to thyroid hormone have been studied following exposure of membranes in vitro to specific long-chain fatty acids. Basal enzyme activity (no added thyroid hormone) was significantly decreased by additions of 10(-9)-10(-4) M-stearic (18:0) and oleic (18:1 cis-9) acids. Methyl oleate and elaidic (18:1 trans-9), palmitic (16:0) and lauric (12:0) acids at 10(-6) and 10(-4) M were not inhibitory, nor were arachidonic (20:4) and linolenic (18:3) acids. Myristic acid (14:0) was inhibitory only at 10(-4) M. Thus, chain length of 18 carbon atoms and anionic charge were the principal determinants of inhibitory activity. Introduction of a cis-9 double bond (oleic acid) did not alter the inhibitory activity of the 18-carbon moiety (stearic acid), but the trans-9 elaidic acid did not cause enzyme inhibition. While the predominant effect of fatty acids on erythrocyte Ca2+-ATPase in situ is inhibition of basal activity, elaidic, linoleic (18:2) and palmitoleic (16:1) acids at 10(-6) and 10(-4) M stimulated the enzyme. Methyl elaidate was not stimulatory. These structure-activity relationships differ from those described for fatty acids and purified red cell Ca2+-ATPase reconstituted in liposomes. Thyroid hormone stimulation of Ca2+-ATPase was significantly decreased by stearic and oleic acids (10(-9)-10(-4) M), but also by elaidic, linoleic, palmitoleic and myristic acids. Arachidonic, palmitic and lauric acids were ineffective, as were the methyl esters of oleic and elaidic acids. Thus, inhibition of the iodothyronine effect on Ca2+-ATPase by fatty acids has similar, but not identical, structure-activity relationships to those for basal enzyme activity. To examine mechanisms for these fatty acid effects, we studied the action of oleic and stearic acids on responsiveness of the enzyme to purified calmodulin, the Ca2+-binding activator protein for Ca2+-ATPase. Oleic and stearic acids (10(-9)-10(-4) M) progressively inhibited, but did not abolish, enzyme stimulation by calmodulin (10(-9) M). Double-reciprocal analysis of the effect of oleic acid on calmodulin stimulation indicated noncompetitive inhibition. Addition of calmodulin to membranes in the presence of equimolar oleic acid restored basal enzyme activity. Oleic acid also reduced 125I-calmodulin binding to membranes, but had no effect on the binding of [125I]T4 by ghosts. The mechanism of the decrease by long chain fatty acids of Ca2+-ATPase activity in situ in human red cell ghosts thus is calmodulin-dependent and involves reduction in membrane binding of calmodulin.

Water excretion in the elderly

Osmoreceptor sensitivity is enhanced in healthy elderly subjects and AVP secretion is increased, relative to that of younger subjects, when plasma osmolality rises. Increased AVP secretion/unit increase in plasma tonicity reflects a decrease in collecting tubule sensitivity to AVP by an as yet unknown mechanism in the aged kidney. This change in sensitivity is not completely offset by increased ADH release, so that maximum Uosm achievable under hydropenic conditions (concentrating ability) is reduced in the elderly. CH2O in older subjects decreases in proportion to the fall in GFR; thus, CH2O is intact in older subjects with preserved GFR. In subjects with age-related reductions in GFR, minimal Uosm achievable is usually less than 100 mOsm per kg H2O and thus usually sufficient to meet the demands of solute-free water intake so that plasma hypo-osmolarity does not result. Increasing exposure of the elderly to pharmacologic agents that reduce CH2O is primarily responsible for the impression that aged patients are at increased risk for hyponatremia.

Laryngeal motoneurone activity in the rabbit during asphyxic gasping

Unitary activity was recorded from 44 recurrent laryngeal nerve (RLN) and 18 external laryngeal nerve (ELN) motoneurones in anaesthetized, paralysed rabbits during the development of periods of severe asphyxia caused by temporarily interrupting artificial ventilation. Ventilation was only recommenced when a simultaneously recorded phrenic neurogram showed the animal had attempted several gasps. Inspiratory-phased fibres (17 RLN, 14 ELN) displayed brief high frequency discharges with each gasp. Some inspiratory-phased ELN motoneurones (6/14) also displayed longer tonic discharges after each of the first few gasps. In the expiratory intervals immediately following each gasp many expiratory-phased fibres (13/21 RLN, 2/4 ELN) were active and 7 RLN fibres discharged a long train of impulses with a decrementing discharge pattern. In 3 anaesthetized rabbits, breathing spontaneously through a tracheostomy, a constant airflow was directed up through the larynx; successive gasps were associated with wide swings in translaryngeal pressure which were confirmed visually as reflecting rapid dilation of the glottis during gasps and intense constriction in the intervals between gasps.

Competition of milrinone, a non-iodinated cardiac inotropic agent, with thyroid hormone for binding sites on human serum prealbumin (TBPA)

Milrinone [2-methyl-5-cyano-(3,4'-bipyridin)-6(1H)-one] is a positive cardiac inotropic agent recently shown to have thyromimetic activity in vitro in a rabbit myocardial membrane Ca2+-ATPase system [K. M. Mylotte et al., Proc. natn. Acad. Sci. U.S.A. 82, 7974 (1985)]. In the present studies, milrinone was examined for activity as an inhibitor of iodothyronine binding by human serum thyroid hormone transport proteins, thyroxine-binding globulin (TBG), prealbumin (TBPA) and albumin. Polyacrylamide gel electrophoresis at pH 9.0 of sera equilibrated with [125I]thyroxine showed that milrinone competed with L-thyroxine (T4) for binding sites on TBPA (10 and 100 microM milrinone caused 61 and 73% reductions, respectively, in T4 binding to TBPA, P less than 0.01); T4 displaced from TBPA was bound by TBG and albumin. Comparable reductions in T4 binding to TBPA were observed in electrophoretic studies conducted at pH 7.4. Binding of triiodo-L-thyronine (T3) to TBPA was electrophoretically confirmed and shown to be decreased in the presence of milrinone. Electrophoresis of purified TBPA also demonstrated that [14C]milrinone co-migrated with this transport protein and that milrinone displaced tracer T4 from TBPA. Amrinone, the 2-H-5-NH2 analog of milrinone, had less than 5% of the activity of milrinone as an inhibitor of T4 binding in electrophoretic studies. Scatchard analysis of T4 and milrinone binding to purified TBPA, measured by equilibrium dialysis, showed two classes of binding sites, with association constants, respectively, of 6.1 X 10(7) M-1 and 1.6 X 10(6) M-1 for T4, and 1.7 X 10(6) M-1 and 8.9 X 10(2) M-1 for milrinone. Computer graphic modeling of the binding of milrinone to the T4 site in the crystal structure of TBPA showed that milrinone best occupied this site when the substituted bipyridine ring overlapped the phenolic ring of T4. In this orientation the 5-cyano group, which has an electronegativity similar to that of iodine, occupied the same volume as the 5'-iodine of T4. The 5-amino group of amrinone lacks these characteristics. In this orientation, the keto function of milrinone overlapped the T4 4'-hydroxyl and could participate in similar intermolecular interactions. Thus, milrinone, a non-iodinated bipyridine, and thyroid hormone share structural and biochemical homologies and compete for the same binding site on TBPA.

Action of erythropoietin in vitro on rabbit reticulocyte membrane Ca2+-ATPase activity

The mechanism of action of erythropoietin is thought to require specific interaction with the target cell surface and involve alteration of cellular calcium metabolism. Using the rabbit reticulocyte membrane as a model of the immature red cell membrane, we investigated the effects of human recombinant erythropoietin on membrane Ca2+-ATPase (calcium pump) activity in vitro. Erythropoietin in a concentration range of 0.025 to 3.0 U/ml progressively decreased membrane Ca2+-ATPase activity by up to 64% (P less than 0.01). These concentrations have been shown by others to stimulate in vitro erythroid growth. The action of erythropoietin on reticulocyte Ca2+-ATPase required an incubation time of 1 h before enzyme assay for maximum effect and was neutralized by antierythropoietin antiserum. Other nonhemopoietic growth factors (epidermal growth factor, insulin) had no effect in this assay. Ca2+-ATPase activity of membranes prepared from rabbit mature red blood cells was not inhibited by erythropoietin. The novel effect of erythropoietin on reticulocyte membrane Ca2+-ATPase activity is a mechanism by which erythropoietin can influence cellular Ca2+ metabolism.

Hypodontia and hyperdontia of permanent teeth in Hong Kong schoolchildren

This study was performed to determine the prevalence of hypodontia and hyperdontia of permanent teeth amongst Southern Chinese children in Hong Kong. The sample consisted of 1093 12-yr-old children on whom a panoramic radiograph was taken. The prevalence of congenitally missing teeth (third molars excluded) was 6.1% in boys, 7.7% in girls, and 6.9% for both sexes combined. On the average, each child was missing 1.5 teeth. The most commonly absent tooth was the mandibular incisor, affecting 58.7% of the children with hypodontia. Thirty children (2.7%) had supernumerary teeth, with a male:female ratio of 6.5:1; in four cases the tooth had erupted. Three children had fourth molars and one case of a supplemental premolar was recorded (all unerupted). Four cases of a maxillary supernumerary tooth and hypodontia in the mandible were seen.

Characteristics of calmodulin binding to purified human lymphocyte plasma membranes

We have explored the role of calmodulin in plasma membrane-related phenomena in lymphocyte activation by measurement of [125I]calmodulin binding to highly purified plasma membrane of human peripheral blood lymphocytes. Calcium-dependent calmodulin binding to lymphocyte membrane was found to reach equilibrium within 5 min of incubation at 37 degrees C and to be saturable and specific. A single class of high affinity-binding sites was identified, with a dissociation constant (Kd) of 1 to 3 X 10(-8) M and a total binding capacity (Bt) of 1 to 2 pmol/mg membrane protein. The free calcium concentration necessary for half-maximal binding was 100 to 300 nM. This was strikingly similar to the cytoplasmic-free calcium activity [Ca2+]i measured by the Quin-2 fluorescence technique, particularly after stimulation with phytomitogens. Calmodulin binding was inhibitable by trifluoperazine (TFP), W-7, and chloropramazine, all of which are calmodulin antagonists. The concentration of TFP that caused 50% inhibition of lymphocyte proliferative responses to phytomitogens was found to be identical to the concentration of TFP which causes 50% inhibition of calmodulin binding to lymphocyte plasma membrane. SDS-polyacrylamide gel electrophoresis followed by gel overlay and autoradiography with iodinated calmodulin revealed five calcium-dependent, TFP-inhibitable, calmodulin-binding polypeptides.

Characteristics of calmodulin binding to purified human lymphocyte plasma membranes

We have explored the role of calmodulin in plasma membrane-related phenomena in lymphocyte activation by measurement of [125I]calmodulin binding to highly purified plasma membrane of human peripheral blood lymphocytes. Calcium-dependent calmodulin binding to lymphocyte membrane was found to reach equilibrium within 5 min of incubation at 37 degrees C and to be saturable and specific. A single class of high affinity-binding sites was identified, with a dissociation constant (Kd) of 1 to 3 X 10(-8) M and a total binding capacity (Bt) of 1 to 2 pmol/mg membrane protein. The free calcium concentration necessary for half-maximal binding was 100 to 300 nM. This was strikingly similar to the cytoplasmic-free calcium activity [Ca2+]i measured by the Quin-2 fluorescence technique, particularly after stimulation with phytomitogens. Calmodulin binding was inhibitable by trifluoperazine (TFP), W-7, and chloropramazine, all of which are calmodulin antagonists. The concentration of TFP that caused 50% inhibition of lymphocyte proliferative responses to phytomitogens was found to be identical to the concentration of TFP which causes 50% inhibition of calmodulin binding to lymphocyte plasma membrane. SDS-polyacrylamide gel electrophoresis followed by gel overlay and autoradiography with iodinated calmodulin revealed five calcium-dependent, TFP-inhibitable, calmodulin-binding polypeptides.

Quantitative analysis of laryngeal mechanosensitivity in the cat and rabbit

1. Single afferent fibres in the internal branch of the superior laryngeal nerve which responded to light touch or gentle probing of discrete areas of the exposed epithelium of the opened larynx were identified in anaesthetized, paralysed cats (148 fibres) and rabbits (58 fibres). 2. A quantitative examination of the sensitivity of these laryngeal mechanoreceptors to both static (step indentations) and dynamic (vibratory) forms of mechanical stimulation was undertaken using a servo-controlled mechanical stimulator. 3. In both species two predominant classes of mechanoreceptors were observed (Boushey, Richardson, Widdicombe & Wise, 1974). One class was distinguished by a regular and continuous pattern of activity at a frequency of 10-70 Hz (tonic fibres, sixty-six in cat, thirty-five in rabbit). The other class was silent or (more rarely) irregularly active at a very low frequency (silent fibres, eighty-two in cat, twenty-three in rabbit). 4. The location of the receptive fields was determined by manual probing. Inter-species and regional variations in receptive field location were observed for the two fibre groups. 5. Conduction velocity was measured for twenty-one tonic and seven silent fibres in the rabbit by a pre-triggered averaging technique. The results obtained (tonic: range 10.8-30.0, mean +/- S.E. of mean 21.4 +/- 1.2 m/s; silent: 14.8-28.6, 20.4 +/- 1.8 m/s) were characteristic of group III afferent fibres but were not significantly different for the two classes. 6. Both classes of receptor showed a response at the onset of a step indentation of the region of the mucosa that corresponded to their receptive field. Subsequent to this brief initial response the behaviour of the two classes diverged markedly. Tonic fibres were invariably slowly adapting whereas most (forty-four out of fifty-five in cat; twenty-two out of twenty-three in rabbit) silent fibres were rapidly adapting, at least for smaller indentation amplitudes. 7. Receptors of both classes were readily entrained to discharge at the same frequency as the probe stimulator (1:1 entrainment) when this was made to vibrate upon the receptive area for test periods of 0.5 or 1.0 s. Tuning curves were constructed of the minimum amplitudes required to elicit 1:1 entrainment throughout an entire test period at various frequencies. 8. Individual fibres in the two classes could be entrained at frequencies up to 400 Hz or more at sensitive (e.g. less than 100 microns) vibratory amplitudes. However, all fibres were less sensitive at these higher frequencies than at some lower point on the frequency scale.(ABSTRACT TRUNCATED AT 400 WORDS)

Donor age-dependent decline in response of human red cell Ca2+-ATPase activity to thyroid hormone in vitro

The effect of increasing donor age on the susceptibility of human red blood cell Ca2+-ATPase activity to stimulation in vitro by thyroid hormone was studied in 26 normal subjects, aged 15-81 yr. Basal enzyme activity (no added thyroid hormone) was unaffected by donor age. Group analysis, young (less than or equal to 50 yr) vs. elderly (greater than 60 yr old), revealed a 23% decrease in responsiveness of the enzyme to L-T4 (P less than 0.001). Regression analysis confirmed an age-dependent decline in thyroid hormone stimulability of Ca2+-ATPase [r = -0.42 (T4 effect) and -0.38 (T3 effect); P less than 0.01]. Red cell membrane Na,K-ATPase activity was not affected by donor age. Plasma T4 and T3 concentrations in these normal subjects also did not change with age. Possible contributions of the following mechanisms to this age-correlated change in enzyme activity were examined: altered responsiveness to calmodulin of membrane Ca2+-ATPase; membrane content of endogenous calmodulin, endogenous plasma T4 and T3 concentrations, and plasma glucose concentrations. Calmodulin responsiveness is required for iodothyronine action on the enzyme, but the calmodulin responsiveness of cells from elderly donors was not significantly different from that of cells from younger donors (P greater than 0.10). There was no relationship between membrane immunoassayable calmodulin and donor age or membrane calmodulin and Ca2+-ATPase activity. There were positive correlations between donor plasma T4 level and basal enzyme activity (P less than 0.05) and between donor plasma T3 concentration and hormone-responsive Ca2+-ATPase (P less than 0.01), but these did not contribute to the age effect. Plasma glucose previously was found to modulate red cell Ca2+-ATPase activity, but did not correlate with decreased hormone responsiveness of the enzyme in elderly donors. In conclusion, we found that the susceptibility of human red cell Ca2+-ATPase to in vitro thyroid hormone stimulation declined significantly with advancing donor age. Several possible calmodulin-dependent mechanisms for this age-dependent change were excluded, and thus, we postulate that the altered hormone sensitivity of the enzyme is membrane phospholipid mediated.

Pharmacodynamics and pharmacokinetics of high-dose sufentanil in infants and children undergoing cardiac surgery

The pharmacodynamic and pharmacokinetic profiles of high-dose sufentanil (15 micrograms/kg) and oxygen were determined in 20 infants and children undergoing repair of congenital heart defects. Sufentanil provided marked hemodynamic stability after an infusion and during the stress periods of incision and sternotomy. Two patients required supplemental nitrous oxide because of an increase in blood pressure greater than 20% of baseline. Mean plasma catecholamine concentrations varied widely among patients and increased, although not significantly, during intraoperative stress. Pharmacokinetic data best fit a two-compartment model. In infants younger than 10 months (group 1) and children older than 10 months (group 2) who were not surface-cooled, elimination half-lives were similar (mean +/- SD, 53 +/- 15 min vs 55 +/- 10 min) as were clearance values (27.5 +/- 9.3 vs 18.1 +/- 10.7 ml X kg-1 X min-1). However, the volumes of distribution were significantly smaller in group 1 compared with group 2 (1.6 +/- 0.46 vs 3.0 +/- 1.3 L/kg). In infants younger than 10 months who were surface-cooled (group 3) elimination half-life was longer (120 +/- 36 min) and volume of distribution larger (3.7 +/- 1.1 L/kg), but clearance rate was similar (21.5 +/- 5.0 ml X kg-1 X min-1) compared with age- and weight-matched infants (group 1).

Bepridil and cetiedil reversibly inhibit thyroid hormone stimulation in vitro of human red cell Ca2+-ATPase activity

Thyroid hormone (10(-11) to 10(-10) M) stimulates plasma membrane Ca2+-ATPase activity in vitro in various tissues, including the human red cell (RBC), by a calmodulin-requiring mechanism. Bepridil and cetiedil are Ca2+ antagonists with an intracellular (calmodulin-antagonist) site of action, as well as an effect on the calcium channel in excitable tissues. We have studied the actions of bepridil and cetiedil on Ca2+-ATPase in a channel-free membrane (RBC) to determine effectiveness of these agents as inhibitors of thyroid hormone action on the enzyme. Dose-response studies showed that thyroid hormone stimulation of Ca2+-ATPase activity in vitro was significantly inhibited by as little as 2 x 10(-5) M bepridil and cetiedil. IC50 values of bepridil and cetiedil for thyroid hormone response of the enzyme were 5 x 10(-5) and 2 x 10(-5) M, respectively, whereas IC50s of these agents for enzyme activity in the absence of thyroid hormone were both 10(-4) M. Progressive addition of purified rat testis calmodulin in vitro (10-150 ng calmodulin/mg membrane protein) restored hormone responsiveness in the presence of bepridil and cetiedil. Binding of labeled thyroid hormone by RBC membranes was unaffected by bepridil and cetiedil (up to 2 x 10(-4) M). Thus, bepridil and cetiedil are Ca2+ antagonists that reversibly inhibit thyroid hormone action on human RBC Ca2+-ATPase by a calmodulin-dependent mechanism. Thyroid hormone effect on Ca2+-ATPase is more susceptible to bepridil and cetiedil inhibition than is basal enzyme activity.

Modulation of 3-hydroxy-3-methylglutaryl-CoA reductase by changes in microsomal cholesterol content or phospholipid composition

Microsomal preparations from normal human skin fibroblasts were used to investigate the role of free cholesterol in the endoplasmic reticulum in the control of cholesterol biosynthesis by regulation of 3-hydroxy-3-methylglutaryl-coenzyme A reductase (NADPH) [(S)-mevalonate:NADP+ oxidoreductase (CoA-acylating), EC 1.1.1.34]. Controlled changes in the cholesterol/phospholipid ratio of microsomes were introduced either in intact cells by incubating fibroblast cultures with whole serum or lipoprotein-deficient serum or by enrichment or depletion of cholesterol in microsomal preparations by incubating microsomes with cholesterol-rich or cholesterol-poor egg phosphatidylcholine unilamellar vesicles. Cholesterol enrichment resulted in suppression of reductase activity and increased ESR order parameters for 12-nitroxystearate in the microsomal preparations. Conversely, cholesterol depletion caused an activation of reductase and a decrease in order parameter. Enrichment of microsomal preparations with a "nonfluid" lipid, dipalmitoyl phosphatidylcholine, also suppressed enzyme activity and increased membrane order. The effect was reversed by subsequent enrichment of the microsomes with fluid egg phosphatidylcholine. Our findings suggest that cholesterol may regulate its own biosynthesis, at least in part, by suppression of hydroxymethylglutaryl-CoA reductase mediated through changes in membrane fluidity as measured by ESR order parameter.

Repression and the inaccessibility of affective memories

The fundamental assumption that repression involves an inaccessibility to affective memories has not been directly addressed in empirical research. In the present study we examined three groups of subjects (repressors, low anxious, and high anxious) under six conditions of recall (general, happy, sad, anger, fear, and wonder). Subjects were asked to recall personal experiences from childhood and to rate their current mood and the affective intensity of the memories. The results indicated that repressors recalled significantly fewer negative memories than did low-anxious and high-anxious subjects and, furthermore, that they were substantially older at the time of the earliest negative memory recalled. Compared with low-anxious subjects, repressors also recalled fewer positive affective memories as well. This pattern of findings is consistent with the hypothesis that repression involves an inaccessibility to negative emotional memories and indicates further that repression is associated in some way with the suppression or inhibition of emotional experiences in general. The concept of repression as a process involving limited access to negative affective memories appears to be valid.

Repression and the inaccessibility of affective memories

The fundamental assumption that repression involves an inaccessibility to affective memories has not been directly addressed in empirical research. In the present study we examined three groups of subjects (repressors, low anxious, and high anxious) under six conditions of recall (general, happy, sad, anger, fear, and wonder). Subjects were asked to recall personal experiences from childhood and to rate their current mood and the affective intensity of the memories. The results indicated that repressors recalled significantly fewer negative memories than did low-anxious and high-anxious subjects and, furthermore, that they were substantially older at the time of the earliest negative memory recalled. Compared with low-anxious subjects, repressors also recalled fewer positive affective memories as well. This pattern of findings is consistent with the hypothesis that repression involves an inaccessibility to negative emotional memories and indicates further that repression is associated in some way with the suppression or inhibition of emotional experiences in general. The concept of repression as a process involving limited access to negative affective memories appears to be valid.

Structure-activity relationships of sex steroid analogs determined in vitro in a thyroid hormone-responsive membrane Ca2+-ATPase model

Physiological concentrations of L-T4 were found previously to stimulate Ca2+-ATPase activity in vitro in reticulocyte membranes from female rabbits and to inhibit this enzyme in reticulocyte membranes from males. In these previous studies, preincubation of intact cells or ghosts with testosterone (5 X 10(-11) M) converted female-source reticulocyte membranes to male-type responsiveness to thyroid hormone (inhibition of Ca2+-ATPase activity). Preincubation of reticulocyte membranes with 17 beta-estradiol (5 X 10(-11) M) converted male-source membranes to female-type responsiveness (stimulation by L-T4 of membrane Ca2+-ATPase activity). Using this sex steroid-sensitive thyroid hormone-dependent membrane enzyme system, we investigated the structure-activity relationships of analogs of sex steroids and unrelated steroids. 5 beta-Androstanes were active compared to testosterone in assays using female-source membranes, while 5 alpha-androstanes were less active. Within the 5 beta-androstanes, activity was dependent on at least one hydroxyl group at the C3- or C17-position. Nongonadal steroids tested were less active, establishing specificity of the sex steroid effect in assays using female-source membranes. Assayed in male-source membranes, estrone and 3-hydroxy-1,3,5-(10)7-estratraen-17-one (equilin) were active compared for estrogen effect with 17 beta-estradiol, while estriol was less active. The activities of hydrocortisone and aldosterone were 76% and 71%, respectively, in this system. These structure-activity relationships are distinct from those described for gonadal steroid-cytoplasmic binding proteins or nuclear interactions, and represent a novel sex steroid-thyroid hormone effect on activity of a membrane enzyme.

Differential effect of common snack foods on caloric intake, growth and obesity in weanling male and female rats with hypothalamic obesity

In order to see whether weanling normophagic rats with hypothalamic obesity (VMNL rats) become hyperphagic and more obese than when fed lab chow, and to see in addition whether there is a possible sex difference in whatever response is found, male and female VMNL rats were fed lab chow for 14 days after lesion production and then, for the following 42 days, they received Hostess HoHos, potato chips, marshmallows and french fries in addition to lab chow. At termination, body weights were similar among the groups, but VMNL rats were fatter and shorter than controls. Also, female VMNL rats were fatter and shorter than male VMNL rats and layed down more fat per unit of food energy. Total caloric intake was greater in controls than in VMNL rats and in males than in females. However, the females showed a decrease in intake and the males an increase over time. Males ate more lab chow and french fries than females. Lab chow was the only food that VMNL rats ate more of than controls. The VMNL rats ate less french fries, HoHos and potato chips than controls, but similar amounts of marshmallows. There was no sex difference in macronutrient intake and per cent macronutrient intake. Moreover, controls ate as much carbohydrate and less per cent carbohydrate than VMNL rats, more fat than VMNL rats, but normal per cent fat and normal protein and per cent protein. Sex X lesion interactions indicated that female VMNL rats ate more per cent carbohydrate than female controls and male VMNL rats, ate more protein than male controls. The greater degree of obesity in the females despite the lower caloric intake may be due to enhanced food energy utilization. The data also show that weanling VMNL rats do not exhibit the great preference for palatable diets that have been reported for mature rats with ventromedial hypothalamic area lesions and that the only sex difference in intake is with french fries, which have neither the highest fat nor the highest carbohydrate content of the foods tested.

Differential activities of tolbutamide, tolazamide, and glyburide in vitro on rabbit myocardial membrane Ca2+-transporting ATPase activity

At clinically achievable concentrations (10(-9) to 5 X 10(-6) M), tolbutamide and tolazamide are in vitro inhibitors of Ca2+-transporting ATPase activity in sarcolemma-enriched rabbit myocardial membranes (sulfonylurea IC50, 10(-7) M). Thyroid hormone stimulation of this calcium pump-associated enzyme in vitro has been previously reported; in our study, this hormonal action was shown to be inhibited by tolbutamide and tolazamide. In contrast to these two sulfonylureas, glyburide (up to 5 X 10(-6) M) had no effect on basal or thyroid hormone-stimulable Ca2+-ATPase activity in vitro. Studies of binding of radiolabeled purified calmodulin to heart membranes showed that tolbutamide and tolazamide inhibited this interaction, whereas glyburide had no effect on calmodulin binding. Addition of purified calmodulin (5-40 ng/micrograms membrane protein) to myocardial membranes incubated with 10(-7) M tolbutamide or tolazamide restored Ca2+-ATPase activity and thyroid hormone responsiveness of the enzyme. Inhibition by tolbutamide and tolazamide of myocardial sarcolemmal Ca2+-ATPase is a mechanism by which these two sulfonylureas may at least transiently raise resting sarcoplasmic Ca2+ concentration. This effect of sulfonylureas on Ca2+-ATPase is not expressed in the presence of the benzamide side chain of glyburide. The inhibitory action of certain sulfonylureas on Ca2+-ATPase is mediated by interference of the agents with the binding of calmodulin to cardiac membranes.

Respiratory muscle activity during asphyxic apnoea and opisthotonus in the rabbit

The behaviour of submandibular, cervical, thoracic and abdominal respiratory muscles was examined in the pentobarbitone-urethane-anaesthetized rabbit during progressive asphyxia induced by rebreathing. During asphyxic hyperpnoea the external intercostal, interchondral and scalene inspiratory activities augmented until succeeded by the apnoeic period, in which all were inhibited with the diaphragm. Likewise, the genioglossus, sternohyoid and thyrohyoid muscles exhibited inspiratory augmentation during asphyxic hyperpnoea until the onset of apnoeic inhibition. However, late in the apnoea these muscles, together with the sternothyroid, sternomastoid and digastric muscles, generated an augmenting tonic discharge associated with an intense abdominal constriction, and with the extension of the limbs characteristic of opisthotonus. This intense tonic activity, which was never expressed by the diaphragm and thoracic inspiratory muscles, was immediately interrupted or terminated by the subsequent inspiratory efforts of gasping respiration, during which the abdominal muscles were inhibited but all the submandibular, cervical and thoracic inspiratory muscles greatly participated. The mylohyoid muscles presented augmenting expiratory activity during asphyxic hyperpnoea which declined during the apnoea. These muscles, however, did not exhibit the intense tonic discharge expressed by the expiratory abdominal and inspiratory submandibular and cervical muscles in late apnoea and were not active in gasping.

Bilirubin diffusion through lipid membranes

The possibility that bilirubin can diffuse through lipid bilayers is investigated with liposomes prepared from dipalmitoylphosphatidylcholine (DPPC), egg phosphatidylcholine (egg PC) with 22 mole percent cholesterol, and a lipid extract preparation from N115 neuroblastoma cells. Liposomes were prepared with internalized bilirubin and bovine or human serum albumin, and bilirubin efflux into an exogenous solution of human serum albumin was measured. Efflux from DPPC liposomes was significantly higher above the phase transition temperature than below it. This change was dependent on the lipid undergoing a phase transition and could not be accounted for by 6 K change in temperature. Maximum bilirubin efflux from egg PC-cholesterol liposomes was found to depend on the relative internal and external albumin pools, suggesting an equilibrium distribution of bilirubin between them. These observations demonstrate that bilirubin can diffuse freely through these lipid membranes.

Incorporation and modification of exogenous phosphatidylcholines by mycoplasmas

The uptake and modification of exogenous phosphatidylcholine (PC) by several Mycoplasma and Spiroplasma species was investigated. While in most Mycoplasma species and in all Spiroplasma species tested the PC appears to be incorporated unchanged from the growth medium, the PC of M. gallisepticum, M. pulmonis, and M. pneumoniae was disaturated PC, apparently formed by modification of 1-saturated-2-unsaturated PC from the growth medium. The modification of the exogenous PC by M. gallisepticum was inhibited by chloramphenicol under conditions that did not affect de novo synthesis of phosphatidylglycerol. A low activity of an endogenous phospholipase A was detected in native M. gallisepticum membranes. The activity was markedly stimulated by treating the membranes with low concentrations of the nonionic detergents. The PC modification was affected by the fatty acid composition of the exogenous PC species. Diunsaturated, 1-saturated-2-unsaturated, and 1-unsaturated-2-saturated PCs were modified to various extents, whereas the disaturated dipalmitoyl PC (DPPC) was not. Both modified and unmodified PCs were incorporated by the cells, but the unmodified DPPC was incorporated at a lower rate and to a lesser extent. The possibility that the incorporation of DPPC into M. gallisepticum cells is associated with the formation of intracytoplasmic membranes is discussed.

Coronavirus IBV: removal of spike glycopolypeptide S1 by urea abolishes infectivity and haemagglutination but not attachment to cells

Urea has been used to remove the S1 spike glycopolypeptide from avian infectious bronchitis virus (IBV) strains M41 and Beaudette, without removing the S2 spike-anchoring glycopolypeptide. Reduction of the pH to 2.9 did not cause release of S1 although some S1 was released spontaneously from IBV Beaudette at pH 7.4. Virus that lacked S1 was no longer infectious or able to cause haemagglutination (HA). However, radiolabelled IBV that lacked S1 attached to erythrocytes and chick kidney cells to the same or similar extent as did intact virus. Treatment of IBV with a phospholipase C preparation, required to make IBV cause HA, did not increase binding of IBV to erythrocytes. The results indicate that while the attachment to cells of virus that lacks S1 is qualitatively different from that of intact virus, the decline in infectivity is the consequence of the loss of some other spike function.

Coronavirus IBV: virus retaining spike glycopolypeptide S2 but not S1 is unable to induce virus-neutralizing or haemagglutination-inhibiting antibody, or induce chicken tracheal protection

Avian infectious bronchitis coronavirus (IBV) inactivated by beta-propiolactone induced partial protection of the trachea in up to 40% of chickens following one intramuscular inoculation 4 to 6 weeks prior to challenge. Retention of an intact tracheal ciliated epithelium 4 days after challenge was the criterion of protection. There was no correlation between protection and serum titres of virus-neutralizing (VN) and haemagglutination-inhibiting (HI) antibody, which were maximal at about 4 weeks after inoculation. Virus from which the S1 but not the S2 (spike-anchoring) spike glycopolypeptide had been removed by urea did not induce protection or VN or HI antibody. Four intramuscular inoculations of monomeric S1 induced VN and HI antibody in two and four chickens respectively. These results indicate that VN and HI antibodies are induced primarily by S1, that intact spikes are a major requirement for the induction of protective immunity and that this property is probably associated with S1.

Abnormal expression of the calmodulin gene in muscle from the dystrophic chicken

Compared to that of genetically-related normal chickens, pectoralis muscle from the dystrophic chicken contained increased calmodulin measured by radioimmunoassay. Determined by the dot blot procedure, expression of the calmodulin gene was enhanced in muscle from affected animals. The bioactivity of the gene product was normal. Together with previous studies reporting increased cell Ca2+ content in dystrophic muscle, the current findings of increased sarcoplasmic calmodulin suggest the latter is a cellular response to defective Ca2+ transport at the level of cell efflux or intracellular organelle (sarcoplasmic reticulum) uptake.

Aporphines 65: chemical, microbial synthesis and characterization by gas chromatography/mass spectrometry of (R)-(-)-10-hydroxy 11-methoxy-N-n-propylnoraporphine, a potential metabolite of N-n-propylnorapomorphine

The title compound has been synthesized by a multistep sequence from (R)(-)-morphine, and compared with the product obtained by microbial O-demethylation of (R)- and (S)-10,11-dimethoxy-N-n-propylnoraporphine (N-n-propylnorapomorphine dimethyl ether). The comparison was based on an analysis of the trifluoroacetyl derivatives of the microbial products and the synthesized compounds using gas chromatography/mass spectrometry in the electron impact mode. Examination by gas chromatography/electron impact/mass spectrometry of the trifluoroacetyl derivatives of 11-hydroxy-10-methoxyaporphine (apocodeine, 3) and 10-methoxy-11-hydroxyaporphine (isoapocodeine, 5) has revealed their excellent chromatographic resolution, and the preferential loss of the methyl group as in 3 [M-15]+ or the trifluoroacetyl group from the 10-position of the aporphine ring as in 5 [M-97]+. Characteristic fragmentations of these isomeric aporphines were used to confirm their structures and were compared with the spectra of authentic synthetic samples.

Coronavirus IBV glycopolypeptides: locational studies using proteases and saponin, a membrane permeabilizer

[35S]methionine-labelled avian infectious bronchitis virus (IBV) (strain 41) and its purified protein components and virions of IBV-Beaudette were incubated with 10 proteases. Several proteases hydrolysed all or some of the membrane glycopolypeptide (M; Mr 30K) and removed about 1.3K of peptide from the amino-(N-)-terminus plus both glycans, as determined by SDS-polyacrylamide gel electrophoresis. N-terminal analysis of [3H]isoleucine-labelled M after hydrolysis by bromelain revealed that the first nine residues had been removed. After the virions had been permeabilised with saponin, a further 2.5K decrease in molecular weight was produced and this was shown to be from the carboxy-(C-)terminus. When considered with the hydropathicity plot analysis of the amino acid sequence of M (Boursnell, M.E.G. et al., 1984, Virus Res. 1, 303-313) these results suggest that as few as 9-20 N-terminal amino acid residues may protrude at the outer membrane surface and that there is a highly protease sensitive sequence of an estimated 20-25 residues at the C-terminus of M exposed in the lumen of the virion. S2 but not S1 was cleaved to a major glycopolypeptide of approximately 71K by several proteases, and to 76K by trypsin. N-terminal sequencing of the 71K glycopolypeptide revealed that it had the same N-terminus as intact S2. After hydrolysis in the presence and absence of saponin it was concluded that S2 is very sensitive to hydrolysis near its carboxy terminus at residues close to the outer membrane surface.

Effects of hyperthyroidism and hypothyroidism on human red blood cell Ca2+-ATPase activity

Erythrocyte Ca2+-ATPase activity was measured in membrane ghosts from hyperthyroid and hypothyroid patients and compared with that in normal subjects. Basal enzyme activity was significantly increased in the hyperthyroid group and decreased in the hypothyroid group. In vitro responsiveness of the enzyme to calmodulin, the activator protein for Ca2+-ATPase, and to T4 was decreased in both hyper- and hypothyroid ghosts. Although the membrane content of endogenous calmodulin was low in hypothyroidism, this is an unlikely explanation for the low basal activity of Ca2+-ATPase. A limited number of patients from each group were restudied when they were euthyroid after 8 or more months of treatment. Basal, T4-stimulated, and calmodulin-stimulated Ca2+-ATPase activities returned to normal, with the exception of calmodulin responsiveness in the membranes from previously hypothyroid patients. This decreased responsiveness may have been a reflection of either increased patient age or underlying chronic (non-thyroidal) illness. This study provides clinical confirmation of previously reported in vitro studies suggesting that the set-point of Ca2+-ATPase activity is, in part, a function of endogenous thyroid hormone levels.

Coronavirus IBV: partial amino terminal sequencing of spike polypeptide S2 identifies the sequence Arg-Arg-Phe-Arg-Arg at the cleavage site of the spike precursor propolypeptide of IBV strains Beaudette and M41

The spike protein of avian infectious bronchitis coronavirus comprises two glycopolypeptides S1 and S2 derived by cleavage of a proglycopolypeptide So, the nucleotide sequence of which has recently been determined for the Beaudette strain (Binns, M.M. et al., 1985, J. Gen. Virol. 66, 719-726). The order of the two glycopolypeptides within So is aminoterminus(N)-S1-S2-carboxyterminus(C). To locate the N-terminus of S2 we have performed partial amino acid sequencing on S2 from IBV-Beaudette labelled with [3H]serine and from the related strain labelled with [3H]valine, leucine and isoleucine. The residues identified and their positions relative to the N-terminus of S2 were: serine, 13; valine, 6, 12; leucine, none in the first 20 residues; isoleucine, 2, 19. These results identified the N-terminus of S2 of IBV-Beaudette as serine, 520 residues from the N-terminus of S1, excluding the signal sequence. Immediately to the N-terminal side of residue 520 So has the sequence Arg-Arg-Phe-Arg-Arg; similar basic connecting peptides are a feature of several other virus spike glycoproteins. It was deduced that for IBV-Beaudette S1 comprises 519 residues (Mr 57.0K) or 514 residues (56.2K) if the connecting peptide was to be removed by carboxypeptidase-like activity in vivo while S2 has 625 residues (69.2K). Nucleotide sequencing of the cleavage region of the So gene of IBV-M41 revealed the same connecting peptide as IBV-Beaudette and that the first 20 N-terminal residues of S2 of IBV-M41 were identical to those of the Beaudette strain. IBV-Beaudette grown in Vero cells had some uncleaved So; this was cleavable by 10 micrograms/ml of trypsin and of chymotrypsin. Partial N-terminal analysis of S1 from IBV-M41 identified leucine and valine residues at positions 2 and 9 respectively from the N-terminus. This confirms the identification, made by Binns et al. (1985), of the N-terminus of S1 and the end of the signal sequence of the IBV-Beaudette spike propolypeptide. N-terminal sequencing of [3H]leucine-labelled IBV-Beaudette membrane (M) polypeptide showed leucine residues at positions 8, 16 and 22 from the N-terminus; these results confirm the open reading frame identified by M.E.G. Boursnell et al. (1984, Virus Res. 1, 303-313) in the nucleotide sequence of M. The N-terminus of the nucleocapsid (N) polypeptide appeared to be blocked.

Clinical pharmacokinetics of the newer intravenous anaesthetic agents

In the last 15 years the role of opioids in anaesthesia management has undergone dramatic change. Initially used as premedicants, or adjuvants to inhalation anaesthetic agents or as analgesics for postoperative pain relief, narcotics have now evolved into primary anaesthetic agents, primarily because of their ability to maintain cardiovascular stability especially in patients with compromised myocardial function. Sufentanil, alfentanil, and lofentanil are 3 new synthetic congeners of fentanyl. Sufentanil and alfentanil afford not only the haemodynamic stability but also the desirable anaesthetic properties of analgesia, and unconsciousness. Their major advantage lies in their pharmacokinetic behaviour; a rapid onset of action and short elimination half-life, allowing for greater flexibility in anaesthetic management. Sufentanil's pharmacokinetic profile is consistent with a 2-compartment model. Its elimination half-life is 149 minutes and its clearance is 11.3 ml/min/kg. Alfentanil's pharmacokinetic profile has been described by both 2- and 3-compartment models. Its distribution and redistribution are rapid, with an elimination half-life of 83 to 137 minutes and a clearance of 4.37 to 6.47 ml/min/kg in adult patients. Lofentanil, however, is an extremely long-acting narcotic analgesic. Presently, its use is justified only when prolonged mechanical ventilation is anticipated. Etomidate, a carboxylated imidazole, is rapidly distributed within a central compartment and then to peripheral compartments; its slow distribution and terminal elimination half-lives are 28 and 273 to 330 minutes, respectively, and its clearance (11.6 to 25 ml/min/kg) is equal to its hepatic plasma flow. Its ability to maintain cardiovascular stability in patients with compromised myocardial function make it a useful induction agent. However, reports of increased mortality and inhibition of steroidogenesis in patients receiving either single injections or constant infusions have created controversies regarding its use. Minaxolone is a water-soluble steroid whose pharmacokinetic profile is consistent with a 2-compartment model. Distribution is rapid with a mean half-life of 2.1 minutes and an elimination half-life of 47 minutes. There do not appear to be any cumulative effects. Plasma levels on recovery were similar in those patients receiving single bolus or continuous infusions. Midazolam and flunitrazepam are two new benzodiazepines. As a class of drugs, benzodiazepines provide the pharmacological properties of anxiolysis, sedation, hypnosis, muscle relaxation, amnesia and anticonvulsant activity.(ABSTRACT TRUNCATED AT 400 WORDS)

Urinary diluting capacity in elderly diabetic subjects

Urinary concentrating ability declines with normal human aging but diluting capacity has been less well studied as a function of age. We studied free water clearance (CH2O) in a group of Type II diabetic patients, aged 47 to 70 years. Conventional water load testing in sulfonylurea-treated diabetic patients revealed preservation of diluting capacity (ability to achieve Uosm less than 100 mOsm/kg) in subjects greater than 60 years of age. Tolazamide permitted expression of normal CH2O; chlorpropamide administration predictably reduced CH2O relative to tolazamide by 58% in subjects greater than 60 years. Free water clearance (CH2O) and glomerular filtration rate (GFR) were comparable in elderly subjects (greater than 60 years) and those less than or equal to 60 years. Normal CH2O in these diabetic patients was explained by persistently normal GFR in the study group. Osmolar clearance (Cosm) was insignificantly lower in diabetics greater than 60 years. Thus, a fall in CH2O in elderly diabetic patients is not a factor contributing to clinical hypoosmolar states encountered in this population.

Microbial models of mammalian metabolism: stereospecificity of ketone reduction with pentoxifylline

The absolute configuration of pentoxifylline alcohol produced by the microbial reduction of pentoxifylline using Rhodotorula rubra (ATCC 20129) was determined by O.R.D. spectroscopy and p.m.r. studies on the R-(+)-alpha-methoxy-alpha-(trifluoromethyl) phenylacetate (MTPA) ester. The development of a reverse-phase h.p.l.c. method for resolving the diastereomeric R-(+)-MTPA esters of racemic pentoxifylline alcohol and assignment of the elution order, allowed for the determination of the stereochemical purity of pentoxifylline alcohol produced by 13 microbial cultures shown previously to reduce pentoxifylline. A marked preference for S-alcohol production was observed with five organisms exhibiting complete stereoselectivity towards S-alcohol generation, and two producing the racemic alcohol.

Milrinone and thyroid hormone stimulate myocardial membrane Ca2+-ATPase activity and share structural homologies

We have recently shown that thyroid hormone in physiological concentrations stimulates sarcolemma-enriched rabbit-myocardial-membrane Ca2+-ATPase in vitro. In this study, milrinone [2-methyl-5-cyano-(3,4'-bipyridin)-6(1H)-one], a cardiac inotropic agent, was thyromimetic in the same system. At clinically achievable concentrations (50-500 nM), milrinone significantly stimulated membrane Ca2+-ATPase in vitro. This action was antagonized by W-7 [N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide], an agent that also blocks thyroid hormone action on the Ca2+-ATPase, at concentrations as low as 5 microM. Progressive additions of milrinone to membranes incubated with a fixed concentration of thyroxine (0.10 nM) or triiodothyronine resulted in a progressive obliteration of the thyroid hormone effect on Ca2+-ATPase. Amrinone [5-amino-(3,4'-bipyridin)-6(1H)-one], the parent bipyridine of milrinone, had no effect on myocardial Ca2+-ATPase activity. X-ray crystallographic analysis of milrinone and amrinone revealed structural homologies between the phenolic ring of thyroxine and the substituted ring of milrinone, whereas amrinone did not share these homologies. The mechanism(s) of the inotropic actions of thyroxine and of milrinone is not clearly understood, but these observations implicate Ca2+-ATPase, a calcium pump-associated enzyme, as one mediator of the effects on the heart of these two compounds.

Calmodulin in interferon preparations: effect of interferon on calmodulin bioactivity

Heat-stable calmodulin immunoreactivity and bioactivity were detected in crude preparations of various types of human, murine and chicken interferons (IFNs). Calmodulin containing HuIFN-alpha was retained on a trifluorophenothiazine-Sepharose column. The two activities were separated by serial elutions with 50 microM Ca2+ (HuIFN-alpha) followed by 2 mM EGTA (calmodulin). While maintaining its full antiviral activity, calmodulin free HuIFN-alpha inhibited enhancement of Ca2+-ATPase activity in vitro by authentic purified eukaryote calmodulin. These results indicate that IFNs are calmodulin-binding proteins and that the secretion of both IFNs and calmodulin occurs from IFN-induced cells.

Sulindac oxidation/reduction by microbial cultures; microbial models of mammalian metabolism

The oxidation and reduction of the sulphoxide moiety of the anti-inflammatory agent sulindac was investigated to explore microbial systems exhibiting parallels of known mammalian metabolism. Of 24 cultures initially screened, four catalysed the expected reactions in analytical studies. Arthrobacter species (ATCC 19140) and Sporobolomyces pararoseus (ATCC 11386) produced sulindac sulphide, Aspergillus alliaceus (NRRL 315) produced sulindac sulphone, and Nocardia corallina (ATCC 19070) produced both the sulphide and sulphone. Preparative-scale production and full structural elucidation of metabolites was accomplished for sulindac sulphide with Arthrobacter species, and sulindac sulphone with A. alliaceus and N. corallina. N. corallina also exhibited an aeration-dependent, reversible reduction of sulindac to the sulphide, and further oxidation to the sulphone. This organism thus parallels the composite of major phase-I redox transformations of this drug observed in mammals.

The effect of in vivo glucose administration on human erythrocyte Ca2+-ATPase activity and on enzyme responsiveness in vitro to thyroid hormone and calmodulin

To characterize endogenous control mechanisms for human erythrocyte membrane Ca2+-ATPase ("calcium pump") activity, we studied the effect of changes in blood glucose concentration in vivo within the physiologic range on Ca2+-ATPase activity in red cells. Red cells obtained in the course of induced hyperglycemia were also studied to determine susceptibility of membrane Ca2+-ATPase to stimulation in vitro by thyroid hormone and calmodulin, both of which have been shown previously to enhance Ca2+-ATPase activity. Oral glucose administration (75 g) to eight healthy, adult subjects induced predictable increases in concentrations of blood glucose and immunoreactive insulin. Basal levels of activity of Ca2+-ATPase in red cells obtained after glucose ingestion fell 55% (P less than 0.025) by 30 min after glucose with recovery of enzyme activity to levels not significantly different from basal by 60 min. Activity of red cell Ca2+-ATPase at time zero was significantly stimulated in vitro by thyroxine (T4, 10(-10) M), triiodo-L-thyronine (T3, 10(-10) M), and calmodulin (100 ng/mg membrane protein). In vivo glucose administration led to depression of red cell enzyme responsiveness in vitro to T4 and T3; recovery from this effect did not occur by 120 min after oral administration of glucose. Calmodulin responsiveness of the enzyme in vitro was less significantly reduced in red cells obtained after glucose ingestion. Intravenous (i.v.) glucose administration (20 g) to five subjects also led to decreased basal enzyme activity (61% of fasting level at 20 min). A significant decrease in response of enzyme to T4 was achieved by 8 min after glucose administration (P less than 0.02), with recovery by 60 min.(ABSTRACT TRUNCATED AT 250 WORDS)

Stereospecific microbiological 10-O-demethylation of R-(-)-10,11-dimethoxyaporphines

The microbiological O-dealkylation of (+) and (-) 10,11-dimethoxyaporphine and the corresponding N-n-propyl analog 10,11-dimethoxy-N-n-propylnoraporphine utilizing the fungus Cunninghamella elegans (ATCC 9245) was found to proceed with regioselectivity for the 10-position, and with a high degree of substrate stereospecificity for the 6a R(-)enantiomer. Only the (R) 10-demethylated products were isolated i.e. (R) iosapocodeine and (R) N-n-propylnor-isoapocodeine. The products were confirmed by comparison with their GC/MS spectra.

Diagnosis of hyperparathyroidism

Availability of immunoassays for specific regions of the parathyroid hormone (PTH) molecule allows discrimination with a high level of surety between primary hyperparathyroidism and tumoral hypercalcemic states associated with circulating PTH-like substances. Assay for intact, N-terminal PTH currently has the highest discriminant function. Prostaglandin-dependent and osteoclast-activating factor-mediated hypercalcemic states associated with neoplasia have suppressed serum PTH levels. PTH-like substances are detected by immunoassays, but in the intact, N-terminal system they are seen as normal-range or low values. The frequency with which any tumor produces only authentic PTH is very low. The serum chloride:phosphate ratio has limited clinical utility in distinguishing tumoral hypercalcemia from hyperparathyroid hypercalcemia, and measurements of nephrogenous cyclic AMP do not distinguish between the effects of circulating authentic PTH and PTH-like substances elaborated by tumors. Additional measures that, in the future, may help to distinguish between parathyroid and tumoral hypercalcemias include quantitative bone biopsy histomorphometry and in vitro bioassays for PTH activity in the separate plasma fractions, obtained by gel filtration, in which PTH and PTH-like substances are found.

Respiration of mitochondria from the gonads of the sea urchin, Strongylocentrotus droebachiensis: the effects of petroleum fractions on oxygen consumption

The respiration of mitochondria from gonads of Strongylocentrotus droebachiensis has been studied in the presence of 2-oxoglutarate, glutamate and succinate. The rate of oxygen consumption increased with temperature between 4 and 20 degrees C. Removal of gametes from ripe gonads was necessary to obtain good respiring mitochondria. Equilibration of respiration media with various petroleum fractions reduced the rate of oxygen consumption and the coupling of O2 consumption to ADP utilization. Lighter fractions (leaded gasolines, unleaded gasoline and related fractions) were more deleterious than medium fractions (kerosene and fuel oil). Heavy fraction (bunker C, vacuum bottoms and crude oil) were least deleterious. Tetraethyl lead contributed to the toxicity of the leaded fractions.

On the location and size of laryngeal motoneurons in the cat and rabbit

Motoneurons supplying the posterior crico-arytenoid (PCA), thyro-arytenoid (TA), lateral crico-arytenoid (LCA), and crico-thyroid (CT) laryngeal muscles were localized in the cat, the rabbit, and the 6-week-old kitten by using the technique of intramuscular injection of horseradish peroxidase. Each muscle was found to be innervated by a single, ipsilateral pool of motoneurons, a result which was reliably established only after controlling adventitious spread of the label to nontarget muscles by prior denervation of adjacent musculature. The laryngeal motoneuron column extended in the nucleus ambiguus for a distance of 5-6 mm caudally from the facial nucleus. CT motoneurons were located in the rostral third of this column while the PCA, TA, and LCA motoneurons were located more caudally. These results are in general agreement with earlier degeneration studies (Lawn, '66a; Szentágothai, '43). Although labelled cells were widely dispersed in the nucleus, particularly in the adult cat, a limited amount of topographical structure could still be discerned in the arrangement of recurrent laryngeal nerve motoneurons. In the cat, the PCA pool was located in the ventral part of the recurrent laryngeal nerve representation and did not extend as far caudally as the TA or LCA pools; the LCA pool was located in the caudal and dorsomedial part of the recurrent laryngeal nerve pool; TA motoneurons appeared to overlap the PCA and LCA pools on all three anatomical planes. TA motoneurons were more numerous than PCA or LCA motoneurons, the numbers of cells in the three pools being estimated at 170, 111, and 112, respectively. In the cat bilateral labelling of different pools pointed to certain differences in morphology between cells from these pools and also suggested a functional basis for such differences. The mean soma diameter for the PCA and CT motoneurons was each significantly smaller than that for the TA and LCA motoneurons. The rabbit data were similar. The findings on motoneuron morphology are considered in relation to anatomical and physiological characteristics known to have been established for individual laryngeal muscles and with which they appear to be consistent.

Interaction of thyroid hormone and sex steroids at the rabbit reticulocyte membrane in vitro: control by 17 beta-estradiol and testosterone of thyroid hormone-responsive Ca2+-ATPase activity

Physiological concentrations (10(-10) M) of L-thyroxine and triiodo-L-thyronine were found in vitro to enhance Ca2+-ATPase activity in reticulocyte-enriched red cell membranes from female rabbits and to inhibit this enzyme in the male reticulocyte. Cross-incubation experiments with reticulocyte-enriched red cells and plasma from the opposite sex demonstrated that this sex-specific membrane response to thyroid hormone was transferable by plasma. Similar experiments with intact reticulocytes exposed to physiological concentrations (10(-11) M) of testosterone and 17 beta-estradiol indicated that the plasma factors were the sex steroids. That is, incubation in vitro with testosterone converted female-source reticulocytes to male-type responsiveness to thyroid hormone (inhibition of Ca2+-ATPase activity); incubation with estradiol converted male-source reticulocyte-enriched red cells to female-type responsiveness (stimulation by iodothyronines of membrane Ca2+-ATPase activity). Similar results were obtained when reticulocyte ghosts were incubated with testosterone and 17 beta-estradiol prior to determination of membrane enzyme activity. Etiocholanolone (5 beta-androstan-3 alpha-ol-17-one) and testosterone were equipotent, but 5 alpha-dihydrotestosterone had little activity in this system. Estrone and estradiol were equipotent, but estriol had no permissive effect on the stimulation by iodothyronine of reticulocyte membrane Ca2+-ATPase activity. Expression of thyroid hormone action in vitro on Ca2+-ATPase activity in the rabbit reticulocyte is determined at the membrane level by testosterone and estrogen. The structure-activity relationships of the sex steroids for this membrane action are different than those reported for nuclear actions of the steroids.

Two cholesterol pools in Acholeplasma laidlawii membranes

Cholesterol exchange kinetics between [14C]cholesterol-labeled Acholeplasma laidlawii and Mycoplasma gallisepticum cells and phosphatidylcholine-cholesterol vesicles followed a biphasic curve, with faster exchange rates for A. laidlawii. The same biphasic curve was obtained with isolated membranes. Cholesterol exchange between lipid vesicles and A. laidlawii cells depleted of phospholipids by phospholipase A2, fitted a monophasic linear curve. The data support the hypothesis that the biphasic cholesterol exchange kinetics do not result from the transbilayer distribution of cholesterol, but reflect the presence in the membrane of two cholesterol pools associated with lipids of high and low affinity for cholesterol.

Estimation of a physiologic replacement dose of levothyroxine in elderly patients with hypothyroidism

We gave graded doses of levothyroxine sodium to 11 elderly hypothyroid subjects (mean age, 66.1 years). The daily levothyroxine sodium dose was initially 75 micrograms or less, and was increased by 25 micrograms every six weeks. Serum total thyroxine, total triiodothyronine, and basal thyrotropin levels were measured at the start of the study and at the end of each six-week dose period. A protirelin (thyrotropin-releasing hormone) test was performed when the thyrotropin level returned to normal. Mean daily levothyroxine sodium doses that normalized serum thyrotropin levels and protirelin test were 110 +/- 8 micrograms and 113 +/- 9 micrograms, respectively. Serial basal thyrotropin determinations during stepwise increments in levothyroxine dose indicated physiologic hormone replacement. As determined in our elderly patients, levothyroxine replacement dose was a third less than that formerly recommended.

Uptake and transbilayer distribution of phosphatidylcholines in Mycoplasma gallisepticum and their effect on cell morphology

Mycoplasma gallisepticum cells grown in a serum-free medium incorporated large amounts of egg-phosphatidylcholine (Egg-PC), dioleoylphosphatidylcholine (DOPC) or dipalmitoylphosphatidylcholine (DPPC) added to the growth medium. Egg-PC and DOPC were incorporated at a high rate and to a large extent and were modified by the organisms, whereas DPPC was incorporated at a lower rate and to a lesser extent and was not modified by the cells. The lactoperoxidase-mediated radioiodination applied to study the transbilayer distribution of phosphatidylcholine (PC) in the membranes revealed that the PC in cells grown with DOPC is almost equally distributed in the outer and inner leaflets of M. gallisepticum membranes, while the PC in DPPC-grown cells is preferentially located in the outer leaflet and that in Egg-PC-grown cells is found in the inner leaflet. Thus, in Egg-PC- or DPPC-grown cells the equilibrium in structure and properties between the inner and outer leaflets is disturbed, resulting in dramatic effects on the morphology of M. gallisepticum cells.

Microbial models of mammalian metabolism: microbial reduction and oxidation of pentoxifylline

Fourteen microorganisms, including fungi, yeasts, and bacteria, were screened for their ability to metabolize the xanthine drug pentoxifylline. Thirteen cultures either reduced the drug to the alcohol metabolite or oxidatively cleaved the ketonic side chain to homologous carboxylic acid metabolites. The alcohol metabolite was the predominant or sole metabolite in all organisms, with conversions ranging from 6 to 91%. Preparative-scale production of the alcohol metabolite with Rhodotorula rubra (ATCC 20129) allowed for the isolation of this product with a 40% yield. Two organisms also produced the carboxylic acid metabolites at low levels (2 to 10%). The routes of metabolism in microbial cultures are the same as those reported in mammalian systems.