Morphometric changes in the prepubertal female rat thyroid gland following acute exposure to 2,2'',4,4''-tetrachlorobiphenyl and Aroclor 1242

Rabbit polyclonal antibodies were raised against the C-terminal fragment (amino acid residues 318-451) of human gamma-tubulin. These antibodies were used to stain cultured cells of various tissues (epithelium, nervous tissue, fibroblasts) from different animals (human, monkey, pig, rat, kangaroo rat, mouse, hamster, chicken, triton). The antibodies specifically stained centrioles in the interphase and mitotic cells of mammals, but not birds (chicken) or amphibians (newt). In the interphase cells, centrioles were stained as a pair of dots (or as a double dot) in 96-97% of the cells. The distances between the maternal and filial centrioles varied in different cultures. Procentrioles were stained in certain cells, but with less intensity than mature centrioles. In mitotic cells, the antibodies revealed two spots corresponding to two mitotic poles. The spots in mitosis were significantly larger than the interphase dots, but the staining was more faint. In spontaneous tripolar mitoses, only two poles were stained. Thus, it was shown that, on the one hand, gamma-tubulin is associated with centrioles irrespective of whether or not they serve as the microtubule organizing centres and, on the other hand, gamma-tubulin might not be an essential component of the microtubule organizing centres.     

Subchronic toxicity of PCB 105 (2,3,3'',4,4''-pentachlorobiphenyl) in rats

Increases in the intracellular free calcium concentration are of great importance to the initiation of development in deuterostomes. Their involvement has not yet been clearly defined in protostomes. We used endogenous ligands (IP3, cADPR, ryanodine and NAADP) and pharmacological agents (thapsigargin [Tg], thimerosal, caffeine and heparin) to study smooth endoplasmic reticulum Ca2+ pump and release mechanisms in eggs of an annelid, Chaetopterus. Oocyte homogenates effectively sequestered Ca2+ and released it in response to IP3 in a concentration-dependent manner. Repeated additions of IP3 were unable to cause further release. Heparin inhibited Ca2+ release in response to IP3. The homogenates also released Ca2+ in response to thimerosal, and this release was sensitive to heparin. Two antibodies to IP3 receptors recognized an appropriate band in Chaetopterus egg lysates. These results indicate that the oocytes possess type-1 IP3-gated Ca2+ channels. Neither calcium itself, nor strontium, cADPR, ryanodine, caffeine nor NAADP released appreciable Ca2+. At low concentrations, Tg caused a slow release of Ca2+; at higher concentrations, it elicited a rapid release. Release of Ca2+ by Tg activated development. Since one theory of fertilization invokes the introduction of a Ca2+ releasing soluble protein into the egg upon sperm-egg fusion, we also tested whether soluble extracts of Chaetopterus sperm could stimulate Ca2+ release in Chaetopterus egg homogenates. There was no Ca2+ release when the sperm extract was added to the homogenate; however, homogenates exposed to sperm extract became refractory to IP3. Thus, Ca2+ release at fertilization in these oocytes occurs through IP3-gated channels.     

Reproductive success of female rainbow trout (Oncorhynchus mykiss) in response to graded dietary ascorbyl monophosphate levels

Ascorbic acid is an essential nutrient in rainbow trout diets and has been shown to play an important role in fish reproduction. Recommended dietary levels are based on immature fish, and the specific requirements for brood stock are unknown. To establish the optimum dietary level for mature rainbow trout, six graded levels of ascorbyl-2-monophosphate were fed to groups of female fish over a period of 10 mo until spawning. Increasing dietary levels of ascorbyl monophosphate resulted in significantly increased ascorbic acid concentrations in liver, kidney, ovaries, and ovulated eggs. Liver and egg concentrations were saturable at 109.3 and 266.6 micrograms ascorbic acid/g tissue, respectively. Tissue saturation levels of 83.7% and 91.2%, respectively, were reached at the highest dietary level (870 mg ascorbyl monophosphate/kg diet) tested. Both fecundity and embryo survival increased significantly with dietary ascorbyl monophosphate levels. The results indicated that the present National Research Council recommended dietary level of 50 mg ascorbic acid/kg diet for rainbow trout is inadequate for brood stock fish. An amount 8 times higher is necessary to optimize tissue ascorbic acid levels and achieve maximum reproductive success.     

Effects of maternal exposure to chlorinated diphenyl ethers on thyroid hormone concentrations in maternal and juvenile rats

Polychlorinated diphenyl ethers (PCDEs) are industrial byproducts and widespread environmental contaminants. Their structural similarity to PCBs suggests that they may exhibit subtle effects on both adult and juvenile mammals. We examined the effects of 3 PCDEs (2,2',4,5,6'-pentachlorodiphenyl ether, 2',3,4,6'-tetrachlorodiphenyl ether, and 2,2',4,4',5,5'-hexachlorodiphenyl ether) on maternal rat thyroid levels shortly after exposure, and on the thyroid levels of 16 day old juvenile rats that had been prenatally exposed. Both 2,2',4,5, 6'-pentachlorodiphenyl ether and 2',3,4,6'-tetrachlorodiphenyl ether depressed thyroxine (T4) levels in the maternal females as well as in both sexes of juvenile rats. 2,2',4,4',5,5'-hexachlorodiphenyl ether did not alter T4 levels in the pregnant females, but depressed juvenile T4 levels. None of the congeners studied significantly altered T3 levels. Effects on thyroid hormones did not correlate with the congeners' induction of cytochrome P450.     

Energy metabolism and protein balance in growing rats housed in 18 degree C or 28 degree C environments and fed different levels of dietary protein

A study was performed to investigate the effect of environmental temperature and increasing levels of protein in the diet on visceral organ size, digestibility, protein balance and energy metabolism in rats. Thirty-six male Wistar rats, initial body weight 77-80 g, were used in a factorial design consisting of three levels of dietary protein and two environmental temperatures of either 18 or 28 degrees C. Three fish meal-based diets were prepared to contain 91, 171 and 262 g protein (N X 6.25/kg diet). Gas-exchange measurements were made and urine and feces were quantitatively collected. The weights of the visceral organs from rats housed at 18 degrees C were greater (P < 0.05) than those of rats housed at 28 degrees C. The digestibilities of dry matter and protein were not affected by environmental temperature, whereas fat and energy digestibilities were higher (P < 0.05) at 18 degrees C than at 28 degrees C. As the level of protein was increased, the digestibilities of protein, energy and fat increased (P < 0.05). Protein intake and protein retention were higher at 18 degrees C (P < 0.05) than at 28 degrees C and increased (P < 0.05) as dietary protein concentration increased. Apparent biological value was lower (P < 0.05) at 18 degrees C than at 28 degrees C and decreased (P < 0.05) as dietary protein level increased. Heat production as a percentage of metabolizable energy was higher (P < 0.05) for the low protein diet than for the medium and high protein diets. The efficiency of energy utilization was depressed (P < 0.05) for the high protein diet when rats were kept at 28 degrees C. The results suggest that thermogenesis was induced when low protein was fed. The increase in thermogenesis may have been important in regulating energy balance and maintaining a constant body temperature in a cold environment.     

Effects of the antiestrogenic environmental pollutant 3,3',4,4', 5-pentachlorobiphenyl (PCB #126) in rat bone and uterus: diverging effects in ovariectomized and intact animals

The purpose of this study was to compare effects on rat bone and uterus of estrogen depletion and exposure to the coplanar PCB-congener 3,3',4,4',5-pentachlorobiphenyl (PCB #126) which exhibits anti-estrogenic properties. Half of the rats were ovariectomized (n = 20) and the other half were sham-operated. Ten of the ovariectomized rats and ten of the sham operated were exposed to PCB #126 (ip injections) for 3 months (total dose: 384 microgram/kg body wt). The remaining control rats were injected with corn oil (vehicle). The rats were killed and the tibiae and uteri were dissected. The left tibia was used for measurements of weight, length, and bone mineral density and the right for histomorphometrical analysis. The uteri were analyzed with respect to estrogen receptor content. PCB #126 exposure did not affect bone mineral density or trabecular bone volume of tibia in sham-operated rats. In ovariectomized rats PCB #126 exposure resulted in a decreased length and an increased bone mineral density of tibia. An obvious PCB #126 induced increase in osteoid surface was observed in sham-operated rats. The cortical thickness and the organic content of the tibia were also increased in these rats. In estrogen deprived tissue like the uteri of ovariectomized rats, PCB #126 showed weak estrogen agonistic activity. The observed effects of PCB #126 on bone and uterine tissues differed between ovariectomized and sham-operated rats.     

Pituitary and peripheral thyroid hormone responses to thyrotropin-releasing hormone during sustained sleep deprivation in freely moving rats

Sleep deprivation is associated with poor cognitive ability and impaired physical health, but the ways in which the brain and body become compromised are not understood. In sleep-deprived rats, plasma total T4 and T3 concentrations decline progressively to 78% and 47% below baseline values, respectively, brown adipose tissue 5'-deiodinase type II activity increases 100-fold, and serum TSH values are unknown. The progressive decline in plasma thyroid hormones is associated with a deep negative energy balance despite normal or increased food intake and malnutrition-like symptoms that eventuate in hypothermia and lethal systemic infections. The purpose of the present experiment was to evaluate the probable causes of the low plasma total T4 during sleep deprivation by measuring the free hormone concentration to minimize binding irregularities and by challenging the pituitary-thyroid axis with iv TRH to determine both 1) the pituitary release of TSH and 2) the thyroidal response of free T4 (FT4) and free T3 (FT3) release to the TSH increment. Sleep-deprived rats were awake 91% of the total time compared with 63% of the total time in yoked control rats and 50% of the total time during the baseline period. Cage control comparison rats were permitted to sleep normally. Sustained sleep deprivation resulted in a decline from baseline in plasma FT4 of 73 +/- 6% and FT3 of 45 +/- 12%, which were similar to the declines in total hormone concentrations observed previously; nonstimulated TSH was unchanged. In the yoked and cage control groups, FT4 also declined, but much less than that of the sleep-deprived group. The relative changes in free compared with total hormone concentrations over the study were also less parallel than those in the sleep-deprived group. The plasma TSH response to TRH was similar in all groups across experimental days. The plasma FT4 and FT3 concentrations in sleep-deprived rats increased after TRH-stimulated TSH release to an extent comparable to control values. Taken together, low basal FT4 and FT3 hormone concentrations and unchanged TSH and thyroidal responses to TRH suggest a pituitary or hypothalamic contribution to the hypothyroxinemia during sleep deprivation.     

Sex differences in investigatory and grooming behaviors of laboratory rats (Rattus norvegicus) following exposure to novelty.

Prior research suggested that during exposure to novel stimuli, rodent investigation and self-grooming behaviors may be sexually dimorphic and interact with ambient illumination. To test this notion we compared the behavior of adult male and female groups of Long-Evans hooded rats in normal room lighting (860 lx) and in very dim, red light (0.2 lx) following exposure to a novel juvenile conspecific. Illuminance level had little or no effect, but investigatory and subsequent self-grooming behaviors of males were substantially greater than those of females, and females engaged in greater ambulatory activity than did males. In a second experiment adult males and females were exposed to a novel inanimate object. No reliable sex differences were observed. We conclude that social novelty, as provided by exposure to a juvenile conspecific, stimulates greater investigation and postinvestigatory self-grooming than exposure to a novel inanimate object and that exposure to novel conspecifics presents a useful method for the investigation of sex differences, gonadal hormone effects, and interactions of hormones with neurotransmitter systems governing motor control systems. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Postnatal exposure to chlorinated dioxins and related chemicals on thyroid hormone status in Japanese breast-fed infants

Effects of postnatal exposure to polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and coplanar polychlorinated biphenyls (Co-PCBs) on thyroid hormone status were studied in the peripheral blood of 36 breast-fed Japanese infants. Estimated total intakes of these chemicals in toxic equivalent quantity (TEQ) converted into 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) from the breast milk significantly and negatively correlated with the levels of triiodothyronine (T3) and thyroxine (T4) in the blood of breast-fed babies. Therefore, exposure to background levels of the highly toxic organochlorine chemicals through the breast milk may cause some effects on thyroid hormone status in Japanese infants.     

Brain and plasma levels of cocaine and benzoylecgonine in lead-expose and cadmium-exposed rats following acute or chronic intraperitoneal administration of cocaine

We have cloned a full length cDNA coding for the activin type IIB receptor (GactRIIB) from the goldfish ovary. GactRIIB shares 73 and 70% amino acid identity in the extracellular domain, and 78 and 80% identity in the intracellular domain with the type IIB receptors of the mouse and Xenopus respectively. The intracellular domain of GactRIIB contains two serine kinase consensus sequences, DFKSRN and GTRRYMAPE, in agreement with the reports in other vertebrates that serine/threonine phosphorylation is involved in activin signal transduction. The identity of GactRIIB was confirmed by transient expression in the COS cells followed by activin binding. Iodinated human activin A bound to the GactRIIB-transfected cells and the binding could be completely inhibited by unlabeled activin. Affinity labeling revealed a band of about 85 kDa, which is in agreement with the reported type II receptors in other vertebrates. Together with the fact that activin is expressed in the goldfish ovary, the cloning of activin receptors from the ovary suggests paracrine and autocrine roles for activin in the goldfish ovarian functions.     

Follicular development and hormonal levels following highly purified or recombinant follicle-stimulating hormone administration in ovulatory women and WHO group II anovulatory infertile patients

PURPOSE: Our purpose was to compare ovarian performance and hormonal levels, after ovulation induction, in both normal ovulatory women undergoing intrauterine insemination (group 1) and World Health Organization (WHO) group II anovulatory infertile patients (group 2), using two different gonadotropin drugs. METHODS: Patients (n = 20 per group) were treated during consecutive cycles, using the same stimulation protocol, with highly purified urinary FSH (HP-FSH) in the first treatment study cycle and recombinant FSH (rFSH) in the second one. Patients in group 1 were treated according to a late low-dose technique, and WHO group II anovulatory patients (group 2) received chronic low-dose FSH therapy. RESULTS: Compared with HP-FSH, treatment with rFSH in group 2 required significantly less ampules of drug to induce follicular development but resulted in significantly higher plasma levels of estradiol and inhibin A on the day of human chorionic gonadotropin injection. No differences were found when both treatment modalities were compared in group 1. CONCLUSIONS: rFSH is more efficacious than urinary HP-FSH for ovulation induction in WHO group II anovulatory infertile patients as assessed by follicular development, hormonal levels, and the amount of FSH required.     

Behavioral and neuroanatomical effects of prenatal, postnatal, or combined exposure to ethanol in weanling rats.

Separate and combined effects of prenatal and postnatal exposure to ethanol on activity, emotionality, learning, and hippocampal neuroanatomy were examined in infant rats. Neonatal rats from mothers that were fed either a liquid ethanol (E) or control (C) diet were artificially reared on either 3% ethanol (E) or isocaloric maltose/dextrin (C). Pups in 4 treatment groups (EE, EC, CE, and CC) were compared. Differences in activity and emotionality were slight. Ethanol affected both the partial reinforcement acquisition effect and the partial reinforcement extinction effect. Hippocampal cell density (compared with Group CC) showed a 12% reduction in CA1 pyramidal cells and an 11% reduction in mature granule cells in Groups EC and EE; the CA4 area (compared with Group CC) was significantly larger after postnatal exposure (Groups CE and EE). Significant positive correlations were found between rate of extinction after partial reinforcement (PRF) training and CA1 pyramidal cell density in Groups CC and CE. A significant negative correlation was found between extinction rate after PRF training and CA4 area in Group EE. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Fatigue crack propagation in iron and Fe-Mo solid solution alloys (77 to 296 K)

Fatigue crack propagation data were obtained for iron and Fe-Mo solid solution alloys through the ductile-brittle transition temperature (77 to 296 K). The fatigue crack growth rates were found to decrease with decreasing temperature for each alloy and to decrease with increasing solute content at 296 K but to increase with solute content at 77 K. These results are discussed in terms of the wide range of mechanical properties observed for the materials. It is shown that the fatigue crack growth rates are inversely proportional to a plastic work term and the square of a characteristic stress approximated by the yield or ultimate stress. Formerly Research Assistant at Materials Science and Engineering Department and Materials Research Center, Northwestern University, Evanston, Ill. This paper is based on a thesis submitted by L. H. Burck in partial fulfillment of the requirements of the degree of Doctor of Philosophy at Northwestern University.     

Glucocorticoids increase retinoid-X receptor alpha (RXRalpha) expression and enhance thyroid hormone action in primary cultured rat hepatocytes

A dynamic model of glucose overflow metabolism in batch and fed-batch cultivations of Escherichia coli W3110 under fully aerobic conditions is presented. Simulation based on the model describes cell growth, respiration, and acetate formation as well as acetate reconsumption during batch cultures, the transition of batch to fed-batch culture, and fed-batch cultures. E. coli excreted acetate only when specific glucose uptake exceeded a critical rate corresponding to a maximum respiration rate. In batch cultures where the glucose uptake was unlimited, the overflow acetate made up to 9. 0 +/- 1.0% carbon/carbon of the glucose consumed. The applicability of the model to dynamic situations was tested by challenging the model with glucose and acetate pulses added during the fed-batch part of the cultures. In the presence of a glucose feed, E. coli utilized acetate 3 times faster than in the absence of glucose. The cells showed no significant difference in maximum specific uptake rate of endogenous acetate produced by glucose overflow and exogenous acetate added to the culture, the value being 0.12-0.18 g g-1 h-1 during the entire fed-batch culture period. Acetate inhibited the specific growth rate according to a noncompetitive model, with the inhibition constant (ki) being 9 g of acetate/L. This was due to the reduced rate of glucose uptake rather than the reduced yield of biomass.     

Influence of environmental temperature on in vivo energy expenditure in vitro ouabain-sensitive respiration in duodenal mucosa and liver in rats fed different levels of dietary fiber or protein

Seventy two Wistar rats were used in two repeat studies to investigate the effect of environmental temperature (18 degrees C or 28 degrees C) and increasing levels of dietary fibre (low, 68 g/kg DM; medium 110 g/kg DM; high, 157 g/kg DM) or protein (low, 91 g/kg DM; medium, 171 g/kg DM; high, 262 g/kg DM) on digestive tract, visceral organ size, energy metabolism, and respiration attributable to Na+,K(+)-ATPase activity in duodenal mucosa and liver. Total and ouabain-sensitive (a measure of Na+,K(+)-ATPase activity) O2 consumption in vitro of tissues were measured polarographically using a Clark-style YSI biological O2 monitor. Whole body heat production (in vivo) was measured using open-circuit respiration chambers. The weight of the visceral organs was higher in rats housed at 18 degrees C than at 28 degrees C. The empty weight of the small intestine, caecum, and colon increased as the level of dietary fibre increased (P 0.05). Heat production as a proportion of metabolizable energy was higher (P < 0.05) at 18 degrees C than at 28 degrees C in the first experiment but this difference was significant in the second experiment. Rats fed the low protein diet had significantly higher (P > 0.05) heat production than those fed medium or high protein diets. Compared to 28 degrees C, environmental temperature of 18 degrees C caused an increased total and ouabain-sensitive O2 consumption in duodenal mucosa. There was no significant effect of environmental temperature on total and ouabain-sensitive O2 consumption in the liver. However, ouabain-sensitive O2 consumption in liver was significantly higher (P 0.05) when rats were fed a low protein diet compared to the medium or high protein diet. Total and ouabain-sensitive O2 consumption increased in duodenal mucosa of rats fed low level of dietary fibre compared to the medium or high dietary fibre diets. The in vitro results corresponded with the whole animal energy expenditure and O2 consumption in vivo.     

Effects of lead exposure on GnRH and LH secretion in male rats: response to castration and alpha-methyl-p-tyrosine (AMPT) challenge

Duchenne and Becker muscular dystrophies are X-linked genetic disorders characterized by dystrophin gene defects. We have studied 250 families with Duchenne and Becker muscular dystrophies (D/BMD) by molecular genetic methods since 1992. Nineteen exons of the dystrophin gene were analyzed for deletion. In families with no deletion, linkage analysis was performed to follow the inheritance of mutant alleles in the affected families. Twenty of these families requested prenatal diagnosis. Six mothers were found to be non-carriers (99% accuracy), thus fetuses were examined in the remaining 14. Two fetuses were affected and terminated. We report our experience and our current clinical practice in providing prenatal studies for D/BMD.     

Changes in mood and hormone levels after rapid-rate transcranial magnetic stimulation (rTMS) of the prefrontal cortex

A person's reality and definition of self are socially constructed; ethnicity is integrally involved in this process. Clinical work is successful if the client constructs a self with a sense of positive self-esteem and empowerment. The profession views social workers' use of self as important in successful clinical work, especially with clients ethnically different from themselves. This article provides a framework adapted from a constructivist perspective for the clinician's skillful use of self in therapeutic discourse. The framework consists of five stances the clinician can use in transcending the discomfort he or she may experience in a cross-cultural clinical situation. Use of these stances facilitates clients' ethnic validation, which is essential to positive therapeutic outcomes. This article uses case examples to illustrate the use of the framework.