Prolonged negative feedback suppression after estradiol administration: proposed mechanism of eugonadal secondary amenorrhea

The finding of normal gonadotropin and estradiol levels in eugonadal women with secondary amenorrhea suggests a disordered feedback relationship of the hypothalamic-pituitary-ovarian axis. To identify possible defects in negative and positive feedback, we compared the effects of five daily injections of 17 beta-estradiol (E2) in 13 normal women and 11 eugonadal patients with absent cyclic menses. The suppression phase of negative feedback was normal, as LH and FSH were similarly lowered in both groups on day 3. Continued LH (P less than 0.01) and FSH (P less than 0.02) inhibition on day 10 of the protocol, 5 days after the last E2 injection, indicated a defect in the recovery phase of negative feedback in the 11 amenorrheic women. In the 4 patients studied gonadotropin suppression persisted for 3 weeks, E2 did not blunt pituitary responsiveness to GnRH in the amenorrheic women, suggesting a central nervous system site for prolonged gonadotropin inhibition. Nine normal but only 2 amenorrheic women X2 = 4.15; P less than 0.05) exhibited a positive feedback increase in LH on days 4-6. We propose that a defect in the recovery phase of negative feedback to E2 rather than absent positive feedback may be the dominant physiological abnormality which causes secondary amenorrhea by preventing early follicular phase gonadotropin increments and follicular maturation.

Diuretic effect of a combined preparation of frusemide and slow-release potassium chloride

An open randomized crossover study was carried out in 10 healthy volunteers to compare the diuretic effect of a single tablet combining 40 mg frusemide and a slow-release formulation of 600 mg potassium chloride with that of the two agents given in separate tablets. The results showed that both treatments had a similar effect on urinary volume and on sodium and potassium excretion, but the hourly urinary volumes during the first 6 hours suggested that the diuretic action of the combined formulation occurred slightly earlier after administration.

An in vitro system for studying insulin release: effects of glucose and glucose-6-phosphate

1. Investigation of the ionic requirements of the in vitro insulin release system, which consists of cod islet plasma membrane and rabbit islet granules incubated at pH 6.5, showed that the presence of Ca(2+) was obligatory for the system to operate.2. Glucose-initiated insulin release was as effective in the presence of beta-gamma-methylene ATP, as it was in the presence of ATP. This analogue of ATP is a substrate neither for adenylate cyclase nor for any known animal membrane proteases. The effect of ATP on glucose mediated release is allosteric.3. Glucose (16 mM)-initiated insulin release was slower than that induced by glucose-6-phosphate (4 mM); 150 and 120 sec, respectively.4. The lag found with glucose-mediated insulin release was dependent upon glucose concentration. The lower the glucose concentration, the longer the lag. With 1 mM glucose the lag extended to 30 min.5. Once insulin release was initiated, the rate and amount of insulin release was independent of the glucose concentration.6. Pre-incubation of membranes with Ca(2+), glucose and ATP prior to the addition of granules, abolished the extended lag that had been obtained with 1 mM glucose. Events in the plasma membrane are the major contributor to the generation of the extended lag.7. The glucose analogue 5'thio-D-glucose, although not able to release insulin, was shown to compete with glucose for the glucoreceptor. By increasing the ratio of analogue to glucose the lag time increased. Thus, the lag time is dependent upon the ;effective' external glucose concentration.8. The max. amount of insulin released by 4 ng of membrane in the presence of glucose (16 mM) was 300 ng. The fact that membranes became refractory to glucose after this max. amount of insulin was released showed that recycling of release sites was not taking place in vitro and that granule: granule interactions were not occurring.9. The 120 sec lag before glucose-6-phosphate-initiated release was independent of glucose-6-phosphate concentration. The rate of insulin release with glucose-6-phosphate was concentration dependent.10. Glucose-6-phosphate did not cause further insulin release from a membrane that had released the max. amount of insulin it was capable of in the presence of glucose. The addition of tolbutamide (10 mM) to such a membrane did cause insulin release. This suggests that glucose and glucose-6-phosphate share a final common pathway.11. Adrenaline and somatostatin did not inhibit glucose-mediated insulin release.

Effect of histamine on electrical and ion transport properties of tracheal epithelium

Previously we showed that the active transport of Cl-toward and Na+ away from the tracheal lumen creates an electrical potential difference (lumen negative) across the canine tracheal epithelium in vitro. The present study examined the effect of histamine on the electrical properties and ion transport of the canine tracheal epithelium in vitro. In six pairs of membranes, under short-circuit conditions, histamine (10(-4) M) significantly increased the net flux toward the lumen of Cl- from 1.7 +- 0.5 SE to 2.4 +- 0.6 microneq/cm2-h and Na+ from -0.4 +- 0.3 to 0.2 +- 0.3 microneq/cm2-h. The response to histamine was inhibited by diphenhydramine (10(-6) M), an H1-receptor antagonist, but not by burimamide (10(-4) M), an H2-receptor antagonist. These results are consistent with the hypothesis that an H1-type receptor mediates the increase of ion flux toward the lumen due to histamine. Increased ion flux toward the lumen may mediate water secretion into the airway lumen and have important effects on the physical properties of the liquid through which the respiratory cilia beat.

Interaction patterns between psychiatric aides and patients

The present study investigated the manner in which psychiatric aides used their time when not involved in staff meetings or off-ward activities. Aides' behaviors on two shifts were observed during times they had the greatest likelihood of interacting with patients. It was found that aides were most likely to be observed in the Nursing Station on both shifts. Aides typically had a specific purpose for interacting with patients when they were on the wards. It was concluded that increased structuring of patient-aide interactions was necessary along with more stringent guidelines regarding the use of the Nursing Station.

An approach to a molecular understanding of exocytotic insulin release

By the use of an in vitro insulin releasing system, new insights into the meechanisms underlying the insulin exocytotic process have been gained. It is proposed that insulin release is initiated by glucose interacting with a glucoreceptor on the plasma membrane. Some properties of this receptor are discussed. It is postulated that after initiation of secretion, continued insulin release is under the control of phosphorylated intermediates of glucose metabolism, i.e. glucose-6-phosphate and phosphoenol pyruvate, operating via a membrane-bound protein kinase. The initiation of insulin release by glucose, and the augmentation of this initiation by the above mentioned intermediates, is viewed as a modified cascade system. The cascade theory of insulin secretion is postulated as an alternative to the threshold distribution hypothesis of insulin secretion. The action of tolbutamide in relation to the two pool theory of insulin secretion is discussed.

Effect of acetylcholine on Cl- and Na+ fluxes across dog tracheal epithelium in vitro

Electrical potential difference is generated across canine tracheal epithelium by active transport of Cl- toward and Na+ away from the lumen. The present study examines the effects of acetylcholine on short-circuit current, potential difference, resistance, and fluxes of 36Cl and 24Na measured across pieces of canine tracheal epithelium mounted in Ussing-type chambers. Under short-circuit conditions, acetylcholine (5 X 10(-5) M) increased significantly net ion flux toward the lumen of Cl- (n equals 7) from +1.7 +/- SE 0.5 TO +3.3 +/- SE 0.5 mueq/cm2 - h, and of Na+ (n equals 7) from -0.8 +/- SE 0.2 to +0.5 +/- SE 0.2 mueq/cm2 - h. Under open-circuit conditions, acetylcholine (5 X 10(-5) M) increased significantly the unidirectional flux of Cl- (n equals 6) toward the lumen from 4.7 +/- SE 1.3 to 5.9 +/- SE 1.4 mueq/cm2 - h, while the other measured fluxes did not change significantly, suggesting that net Cl- flux had increased toward the lumen. Atropine sulfate (10(-8) M) prevented the response to acetylcholine (5 X 10(-5) M). The increased ion flux due to acetylcholine may mediate water secretion into the airway lumen, and this secretion may have important effects on the physical properties of the liquid through which the respiratory cilia beat.

Method for reliably recording geniculate spikes during paradoxical sleep in the cat

A simple procedure is described which allows an investigator to implant electrodes which will reliably record phasic spikes in the lateral geniculate nucleus during paradoxical sleep. This procedure relies on recording photically evoked activity during the implantation of the geniculate electrode and the fact that the distribution of such activity and phasic spikes during paradoxical sleep overlap within the lateral geniculate nucleus. The largest geniculate spikes were recorded during paradoxical sleep when an electrode recorded a large initially positive photically evoked potential and was positioned in the optic tract just ventral to the lateral geniculate nucleus.

New fibreglass casting system in orthopaedic practice

The composition, manufacture and application of a new fibreglass casting system for use in orthopaedic practice are described. The performance of the first 51 fibreglass casts used in routine fracture work is reviewed. The advantages (the cast is waterprof, extremely light and strong) and the disadvantages (an ultraviolet light source is required to cure the cast and the fiberglass tape is rather expensive) are evaluated.

An in Vitro system for studying insulin release caused by secretory granules-plasma membrane interaction: definition of the system

1. An in vitro system is described in which insulin beta-granule-plasma membrane interaction can be studied. 2. The system shows an absolute requirement for physiological amounts of Ca2+ (2 muM) in order for insulin release to proceed. 3. ATP (5 muM) is abot to augment the Ca2+ effect. 4. Glucose (17 mM) alone does not cause insulin release but in the presence of Ca2+ is as effective as ATP. 5. When glucose, ATP and Ca2+ are added together a positive cooperative effect is produced with over 85% of the total insulin, added in the form of beta-granules, being released into the medium in 10 min. 6. The system responds to tolbutamide, in the presence of Ca2+ and ATP, by releasing insulin. 7. Diazoxide, a potent insulin inhibitor in vivo, demonstrates a similar activity in vitro. 8. Various control experiments utilizing alternative membranes, granules, nucleotides, sugars and phosphorylated intermediates of metabolism have all reinforced the specificity of the release mechanisms. 9. These results demonstrate that the in vitro system mimics responses found in the intact organism and can be utilized to dissect the mechanisms associated with exocytosis of insulin granules. 10. Preliminary experiments utilizing adrenaline granules-adrenal plasma membranes and pituitary granules-pituitary plasma membranes suggest that the in vitro system can be extended to all granule secreting processes.

Nonketotic diabetes mellitus: insulin deficiency or insulin resistance?

Ninety-five nonobese, nonketotic subjects were divided into five groups (one normal and four with varying degrees of glucose intolerance) according to their plasma glucose responses during an oral glucose tolerance test. These five groups were then compared on the basis of their insulin response during the oral glucose tolerance test and on the ability of exogenously infused insulin to limit hyperglycemia during a continuous infusion of glucose and insulin, while endogenous insulin was inhibited by the infusion of epinephrine and propranolol. The mean plasma insulin response of patients with either borderline abnormalities of glucose tolerance or chemical diabetes was equal to or greater than that of normal subjects at all points during the glucose tolerance test. Thus, the glucose tolerance of these two patient groups cannot be attributed to lack of insulin. On the other hand, the mean insulin response of patients with moderate fasting hyperglycemia (plasma glucose of 110 to 150 mg/100 ml) was somewhat attenuated, and patients with severe fasting hyperglycemia (plasma glucose greater than 150 mg/100 ml) had unequivocal insulin deficiency. In contrast, all four patient groups with abnormal carbohydrate metabolism were more resistant than normal subjects to the action of insulin. These results indicate that there is a very complex relationship between insulin deficiency and insulin resistance in patients currently classified as having nonketotic diabetes. Patients with either borderline abnormal glucose tolerance or chemical diabetes are more resistant to insulin than normal subjects, and are not insulin deficient. In these patients it seems reasonable to assume that their glucose intolerance is a direct function of their insulin resistance. Patients with severe fasting hyperglycemia are suffering from both insulin deficiency and insulin resistance, and the relationship between these two variables in the genesis of hyperglycemia in these subjects remains obscure. It seems apparent from these studies that nonketotic diabetes mellitus can no longer be considered to be a simple function of insulin lack, and that in order to understand this syndrome we will need to increase our knowledge of the relationship between insulin deficiency and insulin resistance in these patients.

Active transport of Na+ and Cl- across the canine tracheal epithelium in vitro

The flow of water across the tracheobronchial epithelium is likely to be an important determinant of the efficiency of mucociliary clearance. Because bulk water flow has been shown to be coupled to net ion flux in several epithelia, experiments were performed to determine whether ions are transported actively by the canine tracheal epithelium. Electrical potential difference, short circuit current, and the unidirectional fluxes of positive sodium ions (Na+) and negative chloride ions (Cl-) were measured using an in vitro preparation of the posterior membranous portion of canine trachea. The values of the electrical parameters were potential difference, 30.7 +/- 2.7 mV (SE; n = 30), lumen negative to submucosa; short circuit current, 108 +/- 8 muA per cm2 (SE; n = 30). Bidirectional fluxes of Na+ and Cl- were measured both with and without continuous short circuiting of the epithelium. Under short circuit conditions there was a unidirectional flux of Cl- toward the lumen of 7.4 +/- 1.2 muEq per cm2 per hour (SE; n = 6) and toward the submucosa of 4.7 +/- 1.1 muEq per cm2 per hour (SE; n = 6), resulting in a calculated net flux of Cl- of 2.7 +/- 0.6 muEq per cm2 per hour toward the lumen. The unidirectional flux of Na+ toward the lumen was 1.3 +/- 0.5 muEq per cm2 per hour (SE; n = 8) and toward the submucosa was 2.1 +/- 0.7 muEq per cm2 per hour (SE; n = 8). This resulted in a calculated net flux of Na+ of 0.8 +/- 0.2 muEq per cm2 per hour toward the submucosa. These fluxes are consistent with active transport and together they account for the entire short circuit current. Under open circuit conditions, the calculated net fluxes of Cl- and Na+ were not significantly different from zero.

Model for extrusion of insulin beta granules

Considerable controversy surrounds the mechanisms of insulin secretion. This hypothesis attempts to explain the events which may lead to insulin extrusion through the beta-cell membrane. The role of various effectors of insulin secretion on the activities of membrane-bound enzymes is discussed. Glucose, without effect on these enzymes, did induce insulin secretion from insulin granules and plasma membranes in vitro. The model proposes a mechanism whereby glucose may trigger first-phase insulin secretion; reinforcing mechanisms, such as raised levels of cyclic adenosine monophosphate, could augment subsequent secretion.

The glycolate pathway and photosynthetic competence in euglena

The development of glycolate pathway enzymes has been determined in relation to photosynthetic competence during the regreening of Euglena cultures. Phosphoglycolate phosphatase and glycolate dehydrogenase rapidly reached maximal levels of activity but the complete development of ribulose 1,5-diphosphate carboxylase and concomitant photosynthetic carbon dioxide fixation were not attained until 72 hours of illumination. Specific inhibitors of protein synthesis showed that the formation of ribulose 1,5-diphosphate carboxylase in both division-synchronized and regreening cultures was prevented by both cycloheximide and d-threo-chloramphenicol, whereas phosphoglycolate phosphatase formation was only inhibited by d-threo-chloramphenicol but not by l-threo-chloramphenicol or cycloheximide. Since cycloheximide prevented ribulose diphosphate carboxylase synthesis and photosynthetic carbon dioxide fixation without affecting phosphoglycolate phosphatase synthesis during regreening, it was concluded that photosynthetic competence was not necessary for the development of the glycolate pathway enzymes. The inhibition of phosphoglycolate phosphatase synthesis by d-threo-chloramphenicol but not by l-threo-chloramphenicol or cycloheximide shows that the enzyme was synthesized exclusively on chloroplast ribosomes, whereas protein synthesis on both chloroplast and cytoplasmic ribosomes was required for the formation of ribulose 1,5-diphosphate carboxylase. Although light is required for the development of both Calvin cycle and glycolate pathway enzymes during regreening it is concluded that the two pathways are not coordinately regulated.

Facilitation of group desensitization of test anxiety

To enhance the effects of group desensitization in the treatment of test anxiety, a modified desensitization procedure was used, calling for pairing a stimulus (tone) with relaxation training, then presenting the stimulus while Ss completed the test-anxiety hierarchy. 60 college freshmen with high test anxiety were divided into 4 groups of 15 Ss each. One group received the modified group-desensitization procedure while a second group received conventional group desensitization. Two control conditions were included: presentation of a tone while completing the test-anxiety hierarchy, and an attention-placebo condition. The modified desensitization procedure was more effective than conventional desensitization and the control conditions.

The Effect of Light on the Synthesis of Mitochondrial Enzymes in Division-synchronized Euglena Cultures

The development of the mitochondrial enzymes fumarase and succinate dehydrogenase has been followed in Euglena cultures division-synchronized by 14-hour light periods alternating with 12-hour dark periods. The activity of both enzymes was unaltered over the light phase, doubled in early dark phase, and thereafter remained constant over the rest of the cycle. The increase in enzyme activity in early dark phase probably represented de novo enzyme synthesis because it was prevented by the addition of cycloheximide at a concentration known to inhibit protein synthesis on Euglena cytoplasmic ribosomes.When division-synchronized cultures were darkened in early light phase, a doubling of both fumarase and succinate dehydrogenase activity resulted, showing that light was repressing enzyme synthesis. The addition of acetate did not have a similar effect to darkening cultures: enzyme activity being unaltered over the light phase of the cycle. Enzyme expression was also unaffected by the addition of 3-(3,4 dichlorophenyl)-1,1-dimethylurea, a potent inhibitor of photosynthetic carbon dioxide fixation. The addition of 6-methylpurine (an inhibitor of transcription) at the beginning of the light phase inhibited enzyme increase in early dark phase, but when added at a later stage of the light phase (hour 8), increase in enzyme activity in early dark phase was unaffected. We concluded that transcription for these enzymes occurs in early light phase but light exerts a post-transcriptional control so that enzyme synthesis does not result until cells enter the dark phase of the cell cycle.

Malate dehydrogenase isoenzymes in division synchronized cultures of euglena

Sucrose density gradient centrifugation of broken cell suspensions of autotrophically grown Euglena gracilis Klebs. has allowed the separation of chloroplasts, mitochondria, and peroxisomes. Chlorophyll was taken as a marker for chloroplasts, fumarase and succinate dehydrogenase for mitochondria, and glycolate oxidoreductase for peroxisomes. Peaks of malate dehydrogenase (l-malate-NAD oxidoreductase, EC 1.1.1.37) activity were found in the mitochondrial and peroxisomal fractions. Acrylamide gel electrophoresis showed specific isoenzymes in the mitochondrial and peroxisomal fractions and a third isoenzyme in the supernatant. The mitochondrial isoenzyme which had a Km (oxaloacetate) of 30mum was inhibited by oxaloacetate concentrations above 0.17 mm, an inhibition of 50% being given by 0.9 mm oxaloacetate. The peroxisomal isoenzyme had a Km (oxaloacetate) of 24 mum, was inhibited by oxaloacetate concentrations above 0.13 mm, 50% inhibition being given by 0.25 mm oxaloacetate. Malate dehydrogenase activity in the supernatant did not show inhibition by increasing oxaloacetate concentration, the Km (oxaloacetate) being 91 mum.In division synchronized cultures of Euglena, all three isoenzymes of malate dehydrogenase were synthesized over the light phase of the cycle. Darkening light phase cultures did not affect malate dehydrogenase activity. The addition to cultures of cycloheximide at a concentration previously shown to inhibit protein synthesis on Euglena cytoplasmic ribosomes completely inhibited increase in malate dehydrogenase activity over the cell cycle. Malate dehydrogenase activity was unaffected by the addition of chloramphenicol in amounts known to inhibit preferentially protein synthesis on 70S ribosomes.

Anaesthetic, cardiovascular and respiratory effects of a new steroidal agent CT 1341: a comparison with other intravenous anaesthetic drugs in the unrestrained cat

1. The anaesthetic, cardiovascular, respiratory and adverse effects produced by the intravenous injection of CT 1341, thiopentone, methohexitone, pentobarbitone, propanidid and ketamine have been compared in unrestrained cats prepared with chronically implanted venous and arterial cannulae. Aortic blood pressure and heart rates were monitored before, during and after loss of consciousness.2. CT 1341 produced rapid induction of anaesthesia followed by moderately rapid recovery, was active over a wide range of doses and caused minimal respiratory depression and few adverse effects. It caused an initial short-lasting tachycardia and fall in aortic blood pressure succeeded by a secondary depressor response.3. The safety margin was narrower with the barbiturate drugs than with CT 1341, and large doses induced apnoea and respiratory depression. Small doses of methohexitone elicited excitatory effects and large doses caused severe respiratory and circulatory depression, and recovery from anaesthesia was protracted.4. Propanidid induced short-lasting light anaesthesia. The safety margin was narrowest with this drug and induction was associated with adverse circulatory, respiratory and other effects.5. Ketamine was active over a wide range of doses but exhibited qualitatively different properties from the other anaesthetics. Induction was slower after small doses and these produced circulatory stimulation, catatonia and bizarre behavioural effects. Large doses caused respiratory and circulatory depression and recovery was protracted.6. It is concluded that CT 1341 has a wider therapeutic latitude, produces less respiratory depression and has other advantages over the currently used intravenous anaesthetics.

Insulin release from mouse islets. Effect of glucose and hormones on adenylate cyclase

The adenylate cyclase system of normal mouse islets was characterized. The pH optimum of the system was 7.6. The enzyme preparation contained particulate phosphodiesterase activity. This could be removed by treatment with 0.4% (v/v) Triton X-100 or inhibited by 8mm-theophylline in the presence of 2mm-cyclic AMP (adenosine 3':5'-cyclic monophosphate). ATP at 0.32mm produced one-half maximal enzyme activity. The enzyme was stimulated in the presence of F(-) and strongly inhibited by Ca(2+). The isolated enzyme retained hormonal sensitivity and was stimulated by glucagon, pancreozymin and secretin at physiological concentrations. Glucose at 17mm, 8mm and 2mm had no direct effect on the activity of the enzyme; neither did galactose at the same concentrations. Groups of islets incubated in 17mm- or 2mm-glucose for 5 or 15min and then homogenized and assayed for adenylate cyclase activity showed no differences in adenylate cyclase activity. The results suggest that the mechanism of glucose-mediated insulin release is not via the adenylate cyclase system. Hormones, however, could mediate insulin secretion via their effects on the adenylate cyclase system.

Effects of prednisolone in an experimental model of arthritis in the rabbit

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Gram-negative bacilli in burns

In a period of two years, 865 strains of Gram-negative bacilli other than Pseudomonas aeruginosa isolated from burns were identified by a range of tests. The commonest species were Proteus mirabilis, Escherichia coli, and Enterobacter cloacae. Many strains of Klebsiella aerogenes, Enterobacter aerogenes, and Bacterium anitratum were also found.A large proportion of the strains were tested for sensitivity to nalidixic acid, ampicillin, kanamycin, chloramphenicol, tetracycline, and carbenicillin, and smaller numbers of strains were tested for sensitivity to cephaloridine, polymyxin, streptomycin, sulphadiazine, sulfamylon, and trimethoprim. The proportion of strains sensitive and resistant to different antibacterial agents varied widely with species of bacteria. A large proportion of the strains of E. coli and P. mirabilis were resistant to ampicillin, which was much used in treatment; resistance appeared least often towards nalidixic acid, kanamycin, trimethoprim, and gentamicin. Multiple resistance occurred less often among strains of E. coli than among Klebsiella spp, Enterobacter spp, and P. mirabilis. Phage and serological typing of Ps. aeruginosa showed that most infections of burns with this organism were due to strains previously found in other patients in the same ward. Taken with other evidence, this supported the view that most infections with Ps. aeruginosa were not acquired from the patient's own flora but from sources in the hospital environment.