Comparison of estrus induction and subsequent fertility with two different intravaginal devices in ewes during the non-breeding season

Two experiments were conducted to compare the effect of estrus induction by controlled internal drug release (CIDR) and intravaginal cream containing 500 mg progesterone (P cream) in ewes during the non-breeding season. In the first experiment, twenty-four ewes were randomly grouped for two treatments with the different intravaginal devices for 12 days: Group A was the CIDR group and Group B was the P cream group. Blood was collected from all treated ewes, and progesterone (P(4)), estradiol 17-beta (E(2)) and luteinizing hormone (LH) concentrations were measured by enzyme immunoassay. In the second experiment, the conception rates from natural mating, estrus-detected AI (inseminated 12 h after estrus detection), or fixed-time AI (inseminated 42 h after removal of an intravaginal device) in 127 ewes treated with CIDR or P cream were compared. In Experiment 1, the rate of estrus induction and the time of estrus onset after device removal were 91.7% and 36.3 +/- 15.7 h in Group A, and 100% and 35.0 +/- 12.6 h in Group B, respectively. There were no significant differences between the devices. The mean plasma P(4) concentration in Group B was significantly (P < 0.01) lower than Group A between day -9 and day -1 (Day 0: the day of device removal). However, no significant differences were found in the mean E(2) concentrations of the two groups after treatment. The mean time of estrus onset in ewes with an observed LH surge and the time of LH surge after treatment were 23.3 +/- 8.7 h and 30.3 +/- 5.0 h for Group A and 27.6 +/- 6.5 and 26.3 +/- 8.0 h for Group B, respectively, and there were no significant differences. However, a significant difference (P < 0.05) was found in the mean time from the time of estrus onset to LH surge between Group A (6.4 +/- 6.7 h) and Group B (-1.3 +/- 4.1 h). In Experiment 2, the conception rates for natural mating, estrus-detected AI, and fixed-time AI were 55.0, 29.4, and 25.0% for Group A and 40.7, 25.0, and 42.1% for Group B, respectively, and there were no significant differences. These results suggest that the effect of induction of estrus and ovulation and the rate of conception after treatment were comparable to CIDR even though the plasma P(4) concentration of the P cream method tended to be low during the insertion period.     

Physico-chemical properties of calf-diarrhea coronavirus

Replication of calf diarrhea coronavirus was not inhibited by 5-iodo-2′-deoxyuridine, indicating that the virus is an RNA virus. Sensitivity to ether and chloroform indicated that the virus is enveloped, and this was confirmed by electron microscopic observation of the virion. The virus was readily inactivated by trypsin and sodium deoxycholate. The virus was labile at 50°C in diluted medium, but readily stabilized in the presence of MgCl₂. It was stable at pH 5 and 7, while a slight loss of infectivity was observed at pH 3. The virus was readily filtered through membrane filters of 200 and 100-nm pore sizes, but not through 50-nm filters. The buoyant density of the virion in CsCl was estimated to be 1.25 g/ml.     

Fipronil modulation of GABAA receptor single-channel currents

Fipronil is the first phenylpyrazole insecticide introduced for pest control. Although fipronil is known to inhibit GABA receptors, the detailed mechanism of action remains to be seen. In order to elucidate the mechanism of fipronil interaction with the mammalian GABAA system, single-channel patch clamp experiments were performed using rat dorsal root ganglion neurons. The amplitude of main conductance state (27pS) current was not significantly altered by co-application of 10 microM fipronil and 10 microM GABA. The histograms of open time distribution were fitted to a sum of three exponential functions. After application of 10 microM fipronil, the proportion of the fastest component increased slightly and that of the slowest component decreased slightly. Thus, the mean open time was decreased from 11.4 ms to 7.8 ms by fipronil. The histograms of closed time distribution were fitted to a sum of four exponential functions. Fipronil 10 microM prolonged the slowest time constant resulting in a prolongation of the mean closed time from 29.7 ms to 52.8 ms. Thus, the frequency of channel openings was reduced. Thus, the fipronil suppression of GABA-induced whole-cell currents is caused in part by decreases in the channel open time and the frequency of channel openings.     

Serological evidence of akabane virus infection in northern Israel in 2001

In February 2002 the first cases of a "blind newborn calves" syndrome with hydranencephaly appeared in Israel. Eighty-one serum samples, from 54 animals on farms where the syndrome was recorded and 27 others from unaffected farms were examined by neutralization of Akabane virus (AKAV, strain OBE-1) by the micro-titer method. Forty-seven of the 54 samples from the affected farms contained high serum neutralization titers against AKAV (mean SN titer 79.5 and +/- 44.7, standard deviation), whereas only one of the 27 samples from the unaffected farms was positive (titer of 8). These results suggest that the vector(s) of AKAV was circulating in Israel in August through December, 2001.     

Genetic and phylogenetic analysis of glycoprotein of rabies virus isolated from several species in Brazil

Genetic and phylogenetic analyses of the region containing the glycoprotein (G) gene, which is related to pathogenicity and antigenicity, and the G-L intergenic region were carried out in 14 Brazilian rabies virus isolates. The isolates were classified as dog-related rabies virus (DRRV) or vampire bat-related rabies virus (VRRV), by nucleoprotein (N) analysis. The nucleotide and amino acid (AA) homologies of the area containing the G protein gene and G-L intergenic region were generally lower than those of the ectodomain. In both regions, nucleotide and deduced AA homologies were lower among VRRVs than among DRRVs. There were AA differences between DRRV and VRRV at 3 antigenic sites and epitopes (IIa, WB+ and III), suggesting that DRRV and VRRV can be distinguished by differences of antigenicity. In a comparison of phylogenetic trees between the ectodomain and the area containing the G protein gene and G-L intergenic region, the branching patterns of the chiropteran and carnivoran rabies virus groups differed, whereas there were clear similarities in patterns within the DRRV and VRRV groups. Additionally, the VRRV isolates were more closely related to chiropteran strains isolated from Latin America than to Brazilian DRRV. These results indicate that Brazilian rabies virus isolates can be classified as DRRV or VRRV by analysis of the G gene and the G-L intergenic region, as well as by N gene analysis.     

Localization of endothelin receptor subtype-A in the testis of rats, dogs, and monkeys

In order to evaluate the physiological roles of the testicular endothelin (Edn) signaling via Edn receptor subtype-A (Ednra) in mammals, the localization of Ednra was investigated by in situ hybridization and immunohistochemistry in the testis of rats, dogs, and monkeys. For in situ hybridization, a rat Ednra RNA probe which is highly homologous to the subcloned canine and monkey Ednra (88.7% and 87.9% identical, respectively) was used. Both Ednra mRNA and protein were detected in interstitial cells and cells in the basal compartment of the seminiferous tubules, mainly Sertoli cells, as well as spermatogonia and some early spermatocytes, but not spermatids. The localization pattern of Ednra was exhibited in a same manner among species, indicating that the physiological role of Edn signaling throughout Ednra was maintained in the mammalian testis.     

Magnetic resonance imaging of alveolar echinococcosis experimentally induced in the rat lung

Pulmonary alveolar echinococcosis (AE) caused by the metacestode of Echinococcus multilocularis is a lethal zoonosis and is a lesion secondarily induced by hematogenous dissemination from hepatic AE lesions. In the present study, a hematogenous pulmonary AE model was experimentally induced in rats by the injection of echinococcal larval tissue homogenate to the tail vein, and then the pathological and diagnostic aspects of pulmonary AE were examined by magnetic resonance imaging (MRI). Histological primary, mature and degenerated AE lesions were observed 5, 18 and 50 weeks after injection, respectively. These lesions were discriminated as signal-void, hypointense and hyperintense regions in T1-weighted MRI (T1WI), respectively. The change in signal intensity in T1WI might reflect the content of proteinaceous fluid as a result of AE cyst degeneration. Western blot analysis of sera with antibodies of two epitopes (Em18 and Em16) of E. multilocularis provided evidence for AE infection in the early stage. T1WI in combination with Western blot analysis could possibility become definitive and early signs of hematogenous pulmonary AE infection.     

The effect of intermittent administration of sustained release isosorbide dinitrate (sr-ISDN) in rats with volume overload heart

Recently, it has been reported that intermittent administration of nitrate, with a nitrate-free interval of 10 to 12 hr eliminated expression of tolerance, and maintained its hypotensive effect. In the present study, we evaluated whether nitrate tolerance developed or not with an intermittent administration of sr-ISDN (5 mg/kg/ once a day) in Wistar rats. The effect of this administration protocol for sr-ISDN on the volume overload heart model, aortovenous fistula, was also examined. Furthermore, blood pressure was monitored by radio telemetry during sr-ISDN (5 mg/kg/once a day) administration. Nitrate tolerance did not develop, and eccentric hypertrophy due to volume overload was moderated by sr-ISDN administration. Sr-ISDN administration maintained blood pressure lower level than the placebo group. In conclusion, prolonged intermittent administration of sr-ISDN maintained its hypotensive effect during the entire experiment period, without developing tolerance, and moderated efferent hypertrophy with attenuated volume overload.