Tips on orienting new OR staff. OR roundtable.
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Costs and Cost Analysis↗
Biomedical subjects
J Teague
Publications and source records attributed to J Teague.
Attenuation of insulin secretion by insulin-like growth factor 1 is mediated through activation of phosphodiesterase 3B.
Both insulin and insulin-like growth factor 1 (IGF-1) are known to reduce glucose-dependent insulin secretion from the beta cells of pancreatic islets. In this paper we show that the mechanism by which IGF-1 mediates this effect is in large part through activation of a specific cyclic nucleotide phosphodiesterase, phosphodiesterase 3B (PDE3B). More specifically, in both isolated pancreatic islets and insulin-secreting HIT-T15 cells, IGF-1 inhibits insulin secretion that has been increased by glucose and glucagonlike peptide 1 (GLP-1). Moreover, IGF-1 decreases cAMP levels in parallel to the reduction of insulin secretion. Insulin secretion stimulated by cAMP analogs that activate protein kinase A and also are substrates for PDE3B is also inhibited by IGF-1. However, IGF-1 does not inhibit insulin secretion stimulated by nonhydrolyzable cAMP analogs. In addition, selective inhibitors of PDE3B completely block the ability of IGF-1 to inhibit insulin secretion. Finally, PDE3B activity measured in vitro after immunoprecipitation from cells treated with IGF-1 is higher than the activity from control cells. Taken together with the fact that pancreatic beta cells express little or no insulin receptor but large amounts of IGF-1 receptor, these data strongly suggest a new regulatory feedback loop model for the control of insulin secretion. In this model, increased insulin secretion in vivo will stimulate IGF-1 synthesis by the liver, and the secreted IGF-1 in turn feedback inhibits insulin secretion from the beta cells through an IGF-1 receptor-mediated pathway. This pathway is likely to be particularly important when levels of both glucose and secretagogues such as GLP-1 are elevated.
Animals↗
A metric map of humans: 23,500 loci in 850 bands.
High-resolution maps integrated with the enhanced location data base software (LDB+) give improved estimates of genetic parameters and reveal characteristics of cytogenetic bands. Chiasma interference is intermediate between Kosambi and Carter-Falconer levels, as in Drosophila and the mouse. The autosomal genetic map is 2832 and 4348 centimorgans in males and females, respectively. Telomeric T-bands are strikingly associated with male recombination and gene density. Position and centromeric heterochromatin have large effects, but nontelomeric R-bands are not significantly different from G-bands. Several possible reasons are discussed. These regularities validate the maps, despite their high resolution and inevitable local errors. No other approach has been demonstrated to integrate such a large number of loci, which are increasing at about 45% per year. The maps and the data and software from which they are constructed are available through the Internet (http:@cedar.genetics.soton.ac.uk/public_html). Successive versions of this location data base may also be accessed on CD-ROM.
Chromosome Banding↗
Linkage map integration.
The algorithms that drive the map+ program for locus-oriented linkage mapping are presented. They depend on the enhanced location database program ldb+ to specify an initial comprehensive map that includes all loci in the summary lod file. Subsequently the map may be edited or order constrained and is automatically improved by estimating the location of each locus conditional on the remainder, beginning with the most discrepant loci. Operating characteristics permit rapid and accurate construction of linkage maps with several hundred loci. The map+ program also performs nondisjunction mapping with tests of nonstandard recombination. We have released map+ on Internet as a source program in the C language together with the location database that now includes the LODSOURCE database. The anonymous ftp is cedar.genetics.soton.ac.uk and the World Wide Web address is http://cedar.genetics.soton.ac.uk/public_html.
Algorithms↗
The reproductive and neural toxicities of acrylamide and three analogues in Swiss mice, evaluated using the continuous breeding protocol.
Acrylamide is a known genetic, reproductive, and neural toxicant, although it is not known if one effect is predominant. The toxicities of several structural analogues of acrylamide have been incompletely characterized, and the relative sensitivity of the second generation is not known. The present studies were designed to explore the relationship between neurotoxicity and reproductive toxicity, to further characterize the toxicities of three acrylamide analogues, and to evaluate the relative sensitivity of a second generation to these compounds. For the F0 generation, male and female Swiss CD-1 mice were provided drinking water containing acrylamide (ACR; 3, 10, 30 ppm), N,N'-methylenebisacrylamide (MBA; 10, 30, 60 ppm), N-(hydroxymethyl)acrylamide (HMA; 60, 180, 360 ppm), or methacrylamide (MACR; 24, 80, 240 ppm) during and after a 14-week cohabitation. The last litter was reared and dosed after weaning until mating at 74 +/- 10 days of age with the same level of compound given to the parents Neurotoxicity was assessed at several times in both generations by measuring forelimb and hindlimb grip strength. In the F0 generation, ACR caused an 11% decrease in pup number without measurable neurotoxicity; female fertility was not affected. Although both generations consumed the same amount of ACR, there were larger changes in the fertility-related endpoints in the F1 mice than in the F0's, with no concomitant change in organ weights or sperm parameters. In F0 mice, MBA reduced the number of live pups and their adjusted weight, with no neurotoxicity and no change in F0 female reproduction. MBA caused greater adverse effects in the second generation, concomitant with increased consumption. In the F0 generation, HMA caused the largest decrease in pup number during cohabitation (26%) together with a small effect on grip strength. Female reproduction was not affected. The second generation consumed more HMA and showed slightly greater toxic effects. In both generations, MACR was negative for both neurotoxicity and reproductive toxicity. Dominant-lethal studies showed that the fertility effects for ACR, MBA, and HMA could be explained by a male-mediated increase in postimplantation loss. These studies found that dominant lethality occurred without structural effects on the reproductive system in the presence of only minor effects on grip strength and without detectable neural histopathology. Female reproduction was not significantly affected by these compounds at the doses used. Thus, these data confirm the male as the affected gender and that the reproductive toxicity was greater than motoneuron toxicity when measured as grip strength.
Acrylamide↗
Contribution of L- and non-L-type calcium channels to voltage-gated calcium current and glucose-dependent insulin secretion in HIT-T15 cells.
The pharmacological properties of voltage-gated Ca current and glucose-dependent insulin secretion were determined using the HIT insulinoma line to understand the role of Ca channels in stimulus-secretion coupling. The L-type Ca channel antagonist nimodipine inhibited a maximum of 50-55% of the peak Ca current, suggesting that L- and non-L-type channels contribute to Ca current. The L-agonist BAY K 8644 increased Ca current by 155%, whereas the N-channel blocker omega-conotoxin MVIIA reversibly blocked 35% of the peak Ca current. Total block with nimodipine and MVIIA was additive. Conotoxin MVIIC did not affect HIT Ca current. Prolonged depolarizations elicited rapidly and slowly inactivating Ca currents. Nimodipine partially inhibited transient current, but fully inhibited slowly inactivating current, suggesting that the former is mediated by L- and N-channels, and the latter is mediated by L-channels. Like slowly inactivating Ca current, glucose-dependent insulin secretion was fully inhibited by nimodipine and insensitive to MVIIA. BAY K potentiated secretion and antagonized nimodipine block. These results suggest that persistent Ca current is mediated by L-channels and is strongly coupled to insulin secretion, whereas transient Ca current is mediated by L- and N-channels and is weakly coupled. Sustained Ca influx may be preferentially coupled because glucose persistently depolarizes HIT cells and inactivates more transient Ca channel pathways.
3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
Novel, rapid optical immunoassay technique for detection of group A streptococci from pharyngeal specimens: comparison with standard culture methods.
A novel immunoassay system based on the changes in the reflection of light, termed an optical immunoassay (OIA), was utilized to directly detect group A streptococcal (GAS) carbohydrate antigen from clinical specimens. In two studies, a total of 1,275 throat swabs were tested for the presence of this antigen with the Strep A OIA rapid detection system and the results were compared with those of standard culture methods. In both studies, the Strep A OIA yielded more positive results than plating of the throat swab onto a selective agar, Trypticase soy agar containing sheep blood, or an enriched broth. In one study, the sensitivity and specificity of Strep A OIA compared with those of the broth-enriched culture were 97.4 and 95.6%, respectively. In a second study a sensitivity of 98.9% and a specificity of 98.6% were achieved. It was also shown that the carbohydrate antigen could be detected in the absence of viable GAS organisms. The Strep A OIA is an easily interpretable method and was shown to be more sensitive than routine culture methods for detecting GAS infections directly from throat swabs.
Antigens, Bacterial↗
Regulation of glutamic acid decarboxylase diabetes autoantigen expression in highly purified isolated islets from Macaca nemestrina.
Macaca nemestrina, which may have larger and more numerous pancreatic islets than other species, was used for large scale islet isolation by ductal collagenase perfusion and Ficoll gradient centrifugation. The average yield was 51,000 islet equivalents per pancreas, or 8,750 islets equivalents per g. The average purity was 91%, often exceeding 95%. These are the highest reported size, purity, and yield per g of any nonautomated primate islet series. Perifusion with glucose, arginine, and isobutylmethylxanthine showed appropriate biphasic insulin secretion. Unlike that in the rat, human islet glutamic acid decarboxylase (GAD) isoform expression is restricted. However, glycemic regulation of GAD expression has been shown only in rats. We, therefore, tested hypotheses that M. nemestrina islets also have restricted GAD expression, that GAD expression in primates is stimulated by glucose, and that this stimulation remains restricted to the 64,000 mol wt (GAD65) isoform. Immunoprecipitation of labeled islet extracts showed that GAD65 expression increased 16.7 +/- 0.6-fold during high glucose in vitro culture. After controlling for observed increases in protein synthesis, specific glucose stimulation was still 4.2 +/- 0.2-fold. Specific antisera revealed no GAD67 expression under basal conditions, and isoform restriction was maintained during stimulation. Increased GAD65 synthesis thus accounts for glucose stimulation of 64K expression. These time- and concentration-dependent effects of glucose suggest that hyperglycemia increases autoantigenicity and may accelerate beta-cell destruction in primates, supporting a role for beta-cell rest in insulin-dependent diabetes mellitus prevention.
Animals↗
Reproductive toxicity assessment by continuous breeding in Sprague-Dawley rats: a comparison of two study designs.
The protocol for Reproductive Assessment by Continuous Breeding (RACB) studies was originally designed to use mice as the test species. However, rats are commonly used for reproductive toxicity research and could be used in the basic RACB design. One of the studies reported below evaluated a standard murine RACB design using rats, which rears the fifth litter to test second generation fertility. The second design tested the logistics and feasibility of rearing the second litter for second generation fertility testing. The standard fifth litter design (L5) was modified slightly for rats by increasing the time allowed for gestation and delivery. Compared to rats rearing their second litter (L2), rats in this L5 design had more litters per pair during continuous breeding and maintained this fertility better over time, as evidenced by producing more pups per litter during the crossover mating segment. Both L2 and L5 rats gave sufficient pups to conduct the second generation fertility evaluation. In addition, the L5 design was easier to conduct and produced pups from gametes exposed to chemical throughout spermatogenesis, making it the preferred design for using rats in Continuous Breeding studies.
Animals↗
Phasic effects of glucose, p-hydroxymercuribenzoate, and lysophosphatidylcholine on insulin secretion from HIT cells.
Monolayer cultures of HIT cells were superfused to examine phasic insulin secretion. A biphasic pattern of insulin secretion was observed when cells were stimulated with a constant glucose concentration as low as 0.28 mM, with increasing stimulation at 0.56, 1.7, and 5.6 mM glucose. Higher glucose concentrations did not increase insulin secretion. In the absence of glucose, p-hydroxymercuribenzoate (15, 30, and 50 microM), which blocks the reacylation of lysophospholipids with arachidonic acid, also evoked a concentration-dependent biphasic release of insulin. Lysophosphatidylcholine (50, 75, and 100 micrograms/ml) also caused a concentration-dependent biphasic release of insulin in the absence of glucose. These observations were similar to those previously reported for superfused monolayer culture of rat islet cells and suggest that the HIT cell is a beta-cell line that may be valuable in the further examination of the relationships among glucose, phospholipid metabolism, and insulin secretion. The data are consistent with the hypothesis that glucose-stimulated release of lysophospholipids may be important in initiation of the biphasic pattern of glucose-stimulated insulin release.
Animals↗
Reproductive effects of four phthalic acid esters in the mouse.
These studies compared the reproductive toxicity of four phthalates by a continuous breeding protocol. Mice were given diets with diethyl phthalate (DEP) (0.0, 0.25, 1.25, or 2.5%), di-n-butyl phthalate (DBP) (0.0, 0.03, 0.3, or 1.0%), di-n-hexyl phthalate (DHP) (0.0, 0.3, 0.6, or 1.2%), or di(2-ethylhexyl) phthalate (DEHP) (0.0, 0.01, 0.1, or 0.3%). Both male and female CD-1 mice were dosed for 7 days prior to and during a 98-day cohabitation period. Reproductive function was evaluated during the cohabitation period by measuring the numbers of litters per pair and of live pups per litter, pup weight, and offspring survival. There was no apparent effect on reproductive function in the animals exposed to DEP, despite significant effects on body weight gain and liver weight. DBP exposure resulted in a reduction in the numbers of litters per pair and of live pups per litter and in the proportion of pups born alive at the 1.0% amount, but not at lower dose levels. A crossover mating trial demonstrated that female mice, but not males, were affected by DBP, as shown by significant decreases in the percentage of fertile pairs, the number of live pups per litter, the proportion of pups born alive, and live pup weight. DHP in the diet resulted in dose-related adverse effects on the numbers of litters per pair and of live pups per litter and proportion of pups born alive at 0.3, 0.6, and 1.2% DHP in the diet. A crossover mating study demonstrated that both sexes were affected. DEHP (at 0.1 and 0.3%) caused dose-dependent decreases in fertility and in the number and the proportion of pups born alive. A crossover mating trial showed that both sexes were affected by exposure to DEHP. These data demonstrate the ability of the continuous breeding protocol to discriminate the qualitative and quantitative reproductive effects of the more and less active congeners as well as the large differences in reproductive toxicity attributable to subtle changes in the alkyl substitution of phthalate esters.
Animals↗
A medical evaluation of the use of qat in North Yemen.
The data presented in this paper examine the frequent statements that the regular use of the drug qat by the people of North Yemen is harmful to their health. The research strategy employed performance of blind physical examinations as well as extensive interviews with 335 females and 371 males in and around the cities of Sanaa, Taiz and Hodeida who had been selected using a quota sample. The sample was classified into heavy, light and non-chewers of the qat plant, and systematic comparisons were made. In general, few diseases or conditions occurred with enough frequency to permit detailed analysis and fewer yet were associated with qat-use. Where associations occurred, differences by sex were often strong. Conditions most strongly associated with use by both sexes were histories of gastritis and insomnia, and the general body system groupings of gastrointestinal disorders. In males the strongest associations were with the histories of anorexia, constipation, insomnia and headaches, as well as the general history of respiratory difficulties. In females strong associations were seen between qat-use and the diagnosis of acute gastritis, and histories of jaundice, bronchitis and hepatic diseases. When effects of age and residence were corrected for by Mantel-Haenszel odds ratios on these items, some of the associations were diminished even further. In general, remarkably few of the allegations regarding the direct effects of qat-use on health by Western visitors to Yemen were supported by this study.
Adolescent↗
Qat use in North Yemen and the problem of addiction: a study in medical anthropology.
Travelers to North Yemen nearly invariably report that Yemeni people are universally addicted to the drug qat and that the problems of the country are related to this. On the other hand, the majority of Yemenis claim that qat is not only harmless, but that it has many virtues. After describing the chemistry of the drug and the customs of use, this paper addresses the question of the concept of addiction in terms of data gathered during an extensive field study of qat use. Questions of latency, tolerance and availability are discussed, while particular attention and data are devoted to an examination of the "analgesic hypothesis." It is concluded that a more complex theory is needed to deal with drug "dependencies" and that social and cultural perspectives must be added to concepts of the physiological and psychological effects of drugs if progress is to be made toward understanding institutional drug use such as is found with regard to qat.
Anthropology↗
Fibroblast monolayer cultures in scintillation counting vials: metabolic and growth experiments using radioisotopes and a microfluoremetric DNA assay.
We have developed a simple technique for the investigation of cellular metabolism and growth in cultured human fibroblasts which facilitates experiments using up to 3 x 10(5) cells in each of 100 or more culture vessels. The method has been used to study cell growth, glucose utilization and oxidation, and protein, RNA and DNA sysnthesis. The use of radiolabeled substrates in tracer experiments is simplified since transfer of cell material is not required. Methods for measuring both total cellular protein and DNA have been adapted to this culture system. Although we have used this tecnique for fibroblast cultures, it also can be easily applied to experiments on any other type of cell that can be grown in a monolayer.
Carbon Radioisotopes↗
Monolayer cell culture of human pancreatic beta cell tumor: effect of glucose and somatostatin on insulin release.
A human pancreatic beta cell tumor was maintained in monolayer cell culture for 80 days. The culture was terminated because of bacterial infection. Probably because extensive trypsin-collagenase dissociation was unnecessary, the dissociated cells attached much more quickly to the surface of the culture flask than do rat pancreatic cells obtained by enzymatic dissociation. Insulin release not only oscillated widely during the first 40 days of culture but also showed a decline from 380 mU the first week to about 50 mU/week the seventh week. For some unknown reason fibroblast overgrowth was not a major problem. Reduction of the medium glucose concentration from 16.5 mM to 5.5 mM did not alter insulin release rate. At glucose concentration of 16.5 mM, somatostatin 1.0 mug/ml reduced insulin release by 40%. From our previously reported studies on the effect of somatostatin on insulin release by monolayer cell cultures of rat endocrine pancreas, we conclude that the constant release of insulin by the tumor cells is relatively nonstimulated. We have confirmed that monolayer cultures of human pancreatic beta cell tumor do not represent a good model for normal human beta cell function because of the major shortcoming of an apparent inability to recognize glucose as a secretogogue.
Adenoma, Islet Cell↗
Case studies in development of masculinity and feminity in male children.
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Child↗