Immunocytochemical study of anti-Müllerian hormone in sheep ovarian follicles during fetal and post-natal development

Anti-Müllerian hormone (AMH) was detected in perinatal and postnatal sheep ovaries, using avidin-biotin immunohistochemistry with a monoclonal antibody specific for ruminant AMH. Immunoreactivity was limited to granulosa cells, and was influenced both by the degree of follicular development, and by the age of the animal. In the fetus, only the most advanced follicles exhibited a faint immunoreactivity at 120 days gestation, and no reaction was observed in younger animals. Immediately before and after birth, primordial follicles were still negative, but a faint reaction was elicited in young growing follicles, increasing with follicle size. Strong immunoreactivity was visible in antral follicles, especially in the innermost granulosa cell layers, close to the oocyte and lining the antral cavity.     

Tumor necrosis factor induces acute phase proteins in rats

Inoculation of WAG rats with recombinant mouse tumor necrosis factor results in a rapid and marked increase in several acute phase proteins in the serum (haptoglobin, alpha 1 acid glycoprotein, alpha 2 macroglobulin) and in the plasma (fibrinogen). We conclude that TNF may play an important role in the inflammatory response in vivo and possibly in the pathogenesis of inflammatory disorders.     

Purified bovine AMH induces a characteristic freemartin effect in fetal rat prospective ovaries exposed to it in vitro

To determine whether anti-Müllerian hormone (AMH) is responsible for the gonadal lesions observed in bovine genetic females united by placental anastomoses to male twins (freemartins), prospective ovaries of fetal rats were exposed to purified bovine AMH in vitro. In cultures initiated at 14 days p.c. and maintained 3 to 10 days, AMH consistently induced a characteristic 'freemartin effect', namely reduction of gonadal volume, germ cell depletion and differentiation, in the gonadal blastema, of epithelial cells with large clear cytoplasm linked by interdigitations, resembling rat fetal Sertoli cells. These cells tend to become polarized and form cords, delineated by a continuous basal membrane containing laminin and fibronectin. Such structures, resembling developing seminiferous cords, were not detected in control ovarian cultures. These data strongly suggest that AMH is the testicular factor responsible for triggering the morphological abnormalities of freemartin gonads.     

Neuronal gene expression in aluminum myelopathy

1. Aluminum administration to susceptible animal species results in neurofilament accumulation in neuronal perikarya and proximal axons. Pathogenetic studies in vivo have shown that aluminum rapidly associates with neuronal chromatin. Whether the effect of aluminum on DNA components plays a role in the production of the neurofibrillary lesion remains unclear. 2. In this study we used Northern analysis and in situ hybridization to evaluate mRNA levels of specific neuronal and glial components in the rabbit spinal cord at various times following aluminum administration. 3. Our results show that (a) all neuronal mRNAs evaluated (neurofilament triplet components, neuronal-specific enolase, and amyloid precursor protein) are markedly decreased, with no decrease in glial fibrillary acidic protein; (b) the effect on neuronal gene expression occurs early and concurrently with the development of the neurofibrillary lesion and reverses rapidly after a single dose of aluminum; and (c) there is a direct correlation between the severity of the neurofibrillary lesion and the decrease in neuronal mRNA levels. 4. We interpret our results to mean that the accumulation of neurofilaments in this model is not due to a selective effect on neurofilament gene expression but may be due to an inhibition of genes coding for components involved in processing of neurofilament proteins.     

Target Detection Assay (TDA): a versatile procedure to determine DNA binding sites as demonstrated on SP1 protein.

We developed a rapid method designated Target Detection Assay (TDA) to determine DNA binding sites for putative DNA binding proteins. A purified, functionally active DNA binding protein and a pool of random double-stranded oligonucleotides harbouring PCR primer sites at each end are included the TDA cycle which consists of four separate steps: a DNA protein incubation step, a protein DNA complex separation step, a DNA elution step and a polymerase chain reaction (PCR) DNA amplification step. The stringency of selection can be increased in consecutive TDA cycles. Since tiny amounts of retained DNA can be rescued by PCR, buffer systems, salt concentrations and competitor DNA contents can be varied in order to determine high affinity binding sites for the protein of choice. To test the efficiency of the TDA procedure potential DNA binding sites were selected by the DNA binding protein SP1 from a pool of oligonucleotides with random nucleotides at 12 positions. Target sites selected by recombinant SP1 closely matched the SP1 consensus site. If DNA recognition sites have to be determined for known, mutated or putative DNA binding proteins, the Target Detection Assay (TDA) is a versatile and rapid technique for consideration.     

Prolonged submaximal exercise and L-carnitine in humans

Changes in the main physiological parameters and circulating indicators of carbohydrate, protein, lipid (and ketone body) metabolism were measured in ten exercising subjects before L-carnitine (L-carn) loading, after 4 weeks of daily loading with 2 g L-carn, and 6-8 weeks after terminating L-carn administration. Measurements were made on venous blood samples collected during each experiment at fixed time intervals over an initial rest of 45 min, 60 min bicycle exercise performed near 50% VO2max and 120 min recovery. Free and total plasma carnitine levels reached a plateau corresponding to an average rise of 25% for both fractions, 9-10 days after the beginning of the L-carn diet. These levels returned to their initial values 6-8 weeks after cessation of the supply. Generally L-carn supplementation did not significantly modify the physiological parameters and circulating metabolites. No distinct increase of the relative participation of endogenous lipids in the fuel supply of prolonged submaximal exercise was observed. In normal human subjects the increased demand for fatty acid oxidation resulting from exercise seems to be adequately supported by endogenous levels of carnitine.     

Hepatocellular Carcinoma in Hepatitis B Surface Antigen Carriers in Eight Institutions

We reviewed records of all persons dying between 1979 and 1986 in eight California institutions for the mentally retarded. Autopsies had been done in 71% of the 1,181 deaths. Nine deaths were due to hepatocellular carcinoma, which invariably developed in carriers of hepatitis B surface antigen (HBsAg) and was fatal within four months of diagnosis. The mean age at death was 32.7 years. The incidence of hepatocellular carcinoma in HBsAg carriers was 140 times greater than in the US population. Persistent hepatitis B infection was probably etiologically related to hepatocellular carcinoma in this population, which is relatively free of exposure to other hepatocarcinogens.     

Characterization of an X-ray-hypersensitive mutant of V79 Chinese hamster cells

A V79 Chinese hamster cell line XR-V15B exhibiting hypersensitivity to X-ray has been isolated and characterized. Additionally to increased X-ray-sensitivity (approximately 8-fold, as judged by D10 values), cross-sensitivity to bleomycin (3-fold increase), 4NQO (3-fold), H2O2, EMS, MMS (2-fold) were observed also. No increased sensitivity to UV and MMC was found. Genetic complementation analysis indicates that XR-V15B belongs to the same complementation group as the X-ray-sensitive (xrs) mutants of Chinese hamster ovary (CHO) cells described by Jeggo (1985). Biochemical analysis of XR-V15B confirms this finding: the mutant showed a decreased ability to rejoin double-strand breaks induced by X-ray as measured by neutral elution. After 4 h of repair more than 50% of the double-strand breaks remain in comparison to 3% in V79 cells. No difference was observed between wild-type and XR-V15B cells in the initial number of single-strand breaks induced, in the kinetics of their rejoining and in the final level of unrejoined single-strand breaks. Treatment with 5-azacytidine did not have an effect on the reversion frequency of XR-V15B, contrary to the results obtained with the xrs mutants. XR-V15B has been grown in continuous culture for more than 3 months without evidence of reversion. The mutation induction by X-ray irradiation at the HPRT locus is not significantly increased in the mutant, but at doses giving the same degree of cell killing, XR-V15B cells are hypomutable.     

A new experimental approach for the study of cardiopulmonary physiology during early development

In this report, an experimental approach and newly designed apparatus for liquid ventilation of preterm animals are described. Findings of age-related changes in cardiopulmonary function of this animal preparation are presented. Thirty-one lambs, 102-137 days gestation (term 147 +/- 3 days), were studied. The carotid artery, jugular vein, and trachea of the exteriorized fetus were cannulated under local anesthesia. Immediately after cesarean section delivery, ventilation commenced; warmed (39 degrees C) and oxygenated (PIO2 greater than 500 Torr) liquid fluorocarbon (RIMAR 101) was delivered to the lung by a mechanically assisted liquid ventilation system. Skeletal muscle paralysis, low-dose exogenous buffering, and thermal support were maintained during the 3-h experiment. Pulmonary gas exchange, acid-base status, and cardiopulmonary and metabolic function were assessed. By utilizing these techniques, effective arterial oxygenation, CO2 elimination, acid-base status, and cardiovascular stability were supported independent of gestational age. The results demonstrate a developmental increase in specific lung compliance and mean arterial pressure and decrease in heart rate and systemic O2 consumption per kilogram with advancing gestational age. These findings demonstrate that liquid ventilation negates the dependency of effective pulmonary gas exchange on surfactant development, thereby extending the limits of viability of the immature extrauterine lamb. As such this new experimental approach is useful for the study of physiological development over an age range previously limited to fetal animal preparations and, therefore, may provide insight regarding adaptation of the premature to the extrauterine environment.     

Dinocrocuta gigantea头骨的发现

本文记述了甘肃和政县晚中新世地层中发现的一个完整的巨鬣狗头骨;讨论了它的分类地位,修正了 Schlosser 1903年建种时的一些鉴定错误.巨鬣狗是鬣狗科中一个十分特化的成员,应代表一个独立的属.根据命名规则,我们采用 N. schmidt-Kittler 1976年所创的 Dinocrocuta. 因此,这个种应订正为 Dinocrocuta gigantea (schlosser, 1903).