Growth of epizootic hemorrhagic disease, akabane, and ephemeral fever viruses in Aedes albopictus cells maintained at various temperatures

The growth curves of one epizootic hemorrhagic disease (EHD) virus serotype (Reoviridae), two Akabane virus strains (Bunyaviridae) and three bovine ephemeral fever (BEF) group viruses (Rhabdoviridae) were determined in Aedes albopictus cells maintained at 15, 20, 28 and 33 degrees C. Ae albopictus cells supported the growth of all the viruses although not necessarily at all temperatures. Because none of the viruses exhibited cytopathic effect in Ae albopictus cells, growth was assayed in baby hamster kidney 21 (BHK21) cells maintained at 37 degrees C. The temperature at which the Ae albopictus cells were maintained had a marked effect on the growth and yield for each virus studied. EHD virus was heat-stable and grew after 4 days at 28 and 33 degrees C, and after 8 days at 20 degrees C. No growth was recorded up to 12 days at 15 degrees C. The two Akabane viruses were heat-sensitive and exhibited different growth patterns. One strain (B8935) showed no growth at 15 degrees C and only minimal growth at 20, 28 and 33 degrees C. The other strain (CSIRO 16) showed growth after 1-2 days at all temperatures with higher titres reached at 15 and 20 degrees C than at 28 and 33 degrees C. The BEF group viruses grew to approximately the same titres at all temperatures. At the higher temperatures (28 and 33 degrees C) most of BEF group viruses had disappeared within 9 days. In contrast at the lower temperatures (15 and 20 degrees C), there was still virus present 18 days after inoculation.(ABSTRACT TRUNCATED AT 250 WORDS)     

Multiple causes of pregnancy failure in hamsters precociously ovulated by human chorionic gonadotropin

Cycling adult female hamsters can be induced to mate and ovulate 24 h early by the injection of 20 IU human chorionic gonadotropin (hCG) at 1500 h on Day 3 (day before proestrus), but pregnancy is not established. Although there is evidence of decreased sperm transport in precociously ovulated females, this does not appear to be the primary cause of infertility. Reduced size and vascularity of corpora lutea (CL) in treated females suggests incomplete or failed CL activation. Control and hCG-treated females were killed by exsanguination under ether anesthesia at intervals for the first 5 days after mating. Serum luteinizing hormone (LH), follicle-stimulating hormone (FSH), prolactin, estradiol, and progesterone were measured by radioimmunoassay. Luteinizing hormone in treated animals was very high at 2200 h on Day 1 after mating (31 h after the hCG injection), due to endogenous release, and dropped below control levels thereafter. Follicle-stimulating hormone, by contrast, was significantly lower than controls at 2200 h on Day 1 and remained low until 2200 h on Day 3 after mating. Prolactin in treated animals was not different from that in controls, except for 1000 h on Day 4, when it showed a significant dip. Estradiol in treated animals was significantly higher than in controls at 2200 h on Day 1 (when LH was also high and FSH was low), and remained high at 1000 h and 2200 h on Day 2, dropping thereafter to control levels. Progesterone was initially at control levels but had dropped significantly by 1000 h on Day 2 and remained low for the next 24 h. These results suggest that pregnancy failure is due to inadequate activation of corpora lutea. This may be due to: 1) immaturity of follicles at the time of ovulation; 2) inappropriate timing of preovulatory events; 3) the luteolytic effects of high levels of LH or estradiol or both; 4) the low level of FSH in the early stages of corpus luteum development; or 5) a combination of the above. Abnormalities of prolactin secretion were not investigated in detail but cannot be ruled out at this time.     

Blockade of a motor response by cholinergic stimulation of the toad midbrain tegmentum

Application of an acid solution to the dorsal skin of conscious toads having intact nervous system induces a scratching reflex and escape movements, as well as autonomic alterations (hypertension and tachycardia) that are part of the defense response. The motor components of this response are abolished or reduced by microinjection of 60, 30, 15 or 7.5 ng carbachol into the midbrain tegmentum. The cardiovascular components, however, continue to be present, although their amplitude is reduced. The depression of the motor response is statistically significant up to 15 minutes for the 60 ng dose, up to 10 minutes for the 15 and 30 ng doses, and only up to 5 minutes for the 7.5 ng dose. The data suggest that the midbrain tegmentum may modulate the reflex motor response triggered by a noxious stimulus and also participate in the organization of the escape movements. The importance of cholinergic agents in this modulation is discussed. The persistence of the cardiovascular component of the response shows the importance of this parameter as an indicator of alert situations.     

Mutagens in human urine: effects of cigarette smoking and diet

Human urine from smokers and nonsmokers on strictly controlled diets was assayed for mutagenic activity. Two distinct diets were employed in this study. Diet study A consisted of a high-meat, high-fat diet, observed for 5 days, followed by a vegan diet, adhered to for the next 5 days. The vegan diet contained no meat, fish, eggs, or dairy products. It was comprised of soy products, prepackaged vegan dinners, seeds, nuts, fruits, vegetables, beans and herbal teas. Diet study B consisted of 3 days on a typical western diet followed by a macrobiotic diet of grains and fresh vegetables for 5 days. Portions of 24-h urine samples were assayed in Salmonella typhimurium TA1538. The levels of urinary creatinine and cotinine were measured. Mutagenic activity was observed in the urine of most smokers. However, the levels of mutagens in the urine of light smokers were similar to those of nonsmokers. For both nonsmokers and smokers there was a significant increase in urine mutagenicity when volunteers were on the vegan diet. Several nonsmokers on the vegan diet in diet study A had pronounced mutagenic activity in their urine samples, in some instances at higher levels than that in the urine of smokers on a meat diet. In diet study B no clear differences were observed between the meat diet and the macrobiotic diet. In diet studies A and B the mutagenic potency of smokers' urine could not be correlated with cotinine levels alone or with urinary pH. These data suggest that dietary factors can play a dominant role in the mutagenicity of urine concentrates.     

An automated device for the preparation of complex reagent mixtures. The immunofluorescence tomograph

A microcomputer-controlled device was built that automatically prepares small volumes of mixtures of up to eight reagents. The operation of the system is fast, flexible, and reliable, thus making possible the routine use of experimental protocols that require large numbers of small volume reagent samples, each having a different composition. In particular, the software we developed for this device handles the preparation of three-antibody staining solutions to be used in triple labeling immunofluorescent flow cytometry experiments that involve only two fluorochromes. In this role, the device is known as an "Immunofluorescence Tomograph."     

Hematologic and immunologic responses in common marmosets (Callithrix jacchus) infected with Plasmodium knowlesi and Epstein-Barr virus

The hematologic and immunologic responses to infection with either the Epstein-Barr virus alone or infection with Epstein-Barr virus and Plasmodium knowlesi were studied using common marmosets (Callithrix jacchus). The assays performed included complete blood cell counts, determinations of natural killer cell activity, and determinations of antibody titers to Epstein-Barr virus early antigen, virus capsid antigen and the nuclear antigen. While no animal showed signs of lymphoproliferative disease, it was found that animals infected with Epstein-Barr virus became positive for early antigen, virus capsid antigen and nuclear antigen at low levels. No difference in antibody titers between Epstein-Barr virus infected animals and co-infected animals was observed. An increase also was found in the number of leukocytes in all groups, and an increase in natural killer cells following infection with Epstein-Barr virus. Some depression in natural killer cells was observed in the co-infected animals when compared to Epstein-Barr virus infected animals.     

Indomethacin inhibits thrombin-, but not thyroxin-stimulated resorption of fetal rat limb bones

The bone-resorbing effects of thrombin and thyroxin, two agents that stimulate resorption in neonatal mouse calvaria by prostaglandin-dependent mechanisms, were examined in cultures of fetal rat limb bones. Thrombin produced maximal resorption in the limb bone cultures at a concentration of 100 U/ml when bones were cultured in BGJ supplemented with 1 mg/ml bovine serum albumin. The effects of thrombin were partially inhibited by 0.5 and 10 uM indomethacin. Thrombin failed to elicit resorption when the limb bones were cultured in DMEM with 15% horse serum. Thyroxin stimulated the resorption of limb bones in both BGJ-albumin and DMEM-serum media. Resorption was elicited by thyroxin concentrations of 10 nM-10 uM. 30 uM thyroxin failed to stimulate resorption. The dose-response curve to thyroxin was shallow, and the agent did not produce maximal resorption. The bone-resorbing effects of thyroxin were not affected by 0.5 or 10 uM indomethacin.