The aim of this study was to perform screening of a novel drug for treating liver injury. Bis(maltolato)zinc(II) complex [Zn(Mal)₂], which was previously reported to possess insulinomimetic activity, was found to have potency against experimentally induced liver injury both in vitro and in vivo. Cultured rat hepatocytes were treated with bromobenzene for 24 h to induce cellular injury. Zn(Mal)₂ of various concentrations was added along with bromobenzene in order to evaluate the hepatoprotective activity of Zn(Mal)₂ in vitro. The number of viable hepatocytes decreased by 42% in the culture with bromobenzene. However, hepatocyte viability was maintained when Zn(Mal)₂ was added to the bromobenzene culture. The hepatoprotective activity of Zn(Mal)₂ in vivo was investigated using a concanavalin A-induced liver injury model in BALB/c mice. Changes in serum aminotransferase activities and the secretion of several cytokines were measured. The hepatoprotective effect of Zn(Mal)₂ was also demonstrated in vivo by the suppression of serum aspartate aminotransferase and alanine aminotransferase elevation. No significant changes in serum cytokines associated with the induction of hepatic damage were observed in the concanavalin A-induced injury model. However, examination of concanavalin A-treated mouse splenocytes revealed a dose-dependent suppression of cytokine secretions by Zn(Mal)₂. Zn(Mal)₂ possessed hepatoprotective activity and might exert its effect by a number of mechanisms.

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A-type (atrial) natriuretic peptide (ANP) levels in heart and plasma were examined by immunohistochemistry, electron microscopy, and radioimmunoassay (RIA) in hypertensive transgenic mice (Tsukuba hypertensive mice; THM). Additionally, the ANP mRNA level in the heart was measured using real-time polymerase chain reaction (PCR) assay. The blood pressure and the ratio of heart weight to body weight in THM was significantly higher than those in the control mice (C57BL/6J). The number of ANP-granules and ANP immunoreactivity in the auricular cardiocytes were significantly lower in THM than in the control. Ultrastructurally, the ventricular cardiocytes in the THM occasionally had ANP-like granules, which were not present in the controls. Using RIA, the plasma, auricular, and ventricular ANP concentrations were significantly higher in THM than in the control, but there was no significant difference in plasma cyclic guanosine monophosphate (GMP) concentration between THM and the control. The ANP mRNA levels of the auricular and ventricular cardiocytes in the THM were siginificantly higher than those in the controls. The present study suggested that the ANP release system of the auricular cardiocytes in these transgenic mice is different from normal (control mice).

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In this paper, we executed genome mapping and comparative mapping analyses for cvd and hob, autosomal recessive mutations with cerebellar vermis defect and cerebellar dysplasia in the rat. For the linkage analysis, we produced three sets of backcross progeny, (ACI × CVD)F₁ and (F344 × CVD)F₁ females crossed to a cvd homozygous male rat, and (HOB × WKY)F₁ males crossed to hob homozygous female rats. Analysis of the segregation patterns of simple sequence length polymorphism (SSLP) markers scanning the whole rat genome allowed the mapping of these autosomal recessive mutations to rat Chromosome (Chr) 2. The most likely gene order is D2Mgh12 - D2Rat86 - D2Mit15 - D2Rat185 - cvd - D2Rat66 - D2Mgh13, and D2Mit18 - Fga -D2Mit14 - D2Rat16 - hob - D2Mgh13. Crossing test between a proven cvd heterozygous and a hob heterozygous rats demonstrated their allelism. Furthermore, comparative mapping indicated the cvd locus corresponds to mouse chromosome 3 and a strong candidate gene Unc5h3, a causative gene for the rostral cerebellar malformation mouse, was implicated.

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The chronic hepatotoxic effects of carbon tetrachloride (CCl₄) in heat-shock protein (HSP) 70 knock out (HSP70-/-) mice were examined. After repeated intraperitoneal injections of CCl₄ for six weeks, the level of ALT and weight ratio of the liver to body were lower in HSP70-/- mice than in the control (WT) mice. The levels of HSP25 and HSP47 were lowered in HSP70-/- mice as compared with WT mice. The grades of hepatic necrosis and neutrophil infiltration were not significantly different between HSP70-/- and WT mice. The collagen content was not affected significantly by CCl₄ treatment.

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DBA/2 CrSlc mice infected with the D variant of encephalomyocarditis virus (EMC-D) (10 PFU/head) developed biphasic hind limb paralysis due to spinal cord lesion. The early phase lesion was characterized by demyelination with infiltration of macrophages in the funiculus lateraris and the late phase lesion by degeneration of motor neurons with infiltration of CD4⁺ T cells in the cornu ventrale (Takeda et al., Int. J. Exp. Pathol., 1993, 1995). In the present study, treatment with anti-Mac1 monoclonal antibody (MAb) or anti-CD4 MAb prior to virus infection (-3 to -1 days) reduced the early phase lesion and the incidence of the first paralysis. Signals of viral RNAs were observed only in a few oligodendrocytes in the funiculus lateraris. Treatment with anti-CD4 MAb from 31 to 33 days post infection when mice showed recovery from the first paralysis reduced the late phase lesion and prevented the second paralysis. Signals of viral RNAs were still detected in a few degenerated neurons in the cornu ventrale. These results indicate that while macrophages and CD4⁺ T cells participate in the early phase lesion and paralysis and only CD4⁺ T cells in the late phase lesion and paralysis.

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We applied RT-nested PCR for the detection of MHV genomic RNA in a modified manner to obtain RNA from the intestines of mice and from filter dust in the ventilation ducts of the room in which a contaminated mouse colony was kept. Since the sequences of MHV-RNA that were extracted from the intestine of a serologically MHV-positive mouse in room No. 2 (MS2) and from the filter dust in a ventilation duct in the same room (FD2) were identical, amplified product from filter dust was demonstrated to come from the MHV contaminated room. Furthermore, sequences of FD2 and of filter dust from another contaminated mouse room, No. 7 (FD7) showed 38 nucleotide exchanges among 368-bp (10.3%), suggesting that two different MHV strains were contaminating our facilities. SSCP analysis of Dra I-digested PCR product of 393 bp also showed different patterns in FD2 and FD7 samples.

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Circadian rhythms of body temperature, heart rate, and locomotor activity were observed in the unanesthetized and unrestrained Syrian hamsters, Djungarian hamsters and Chinese hamsters, and the differences in these biological characters among the three species of hamster were investigated. In each species, body temperature, heart rate, and locomotor activity in the dark period were higher than those in the light period. Heart rate of Chinese hamsters was higher than that of the others in both the light and dark periods. In addition, it was found that the body temperature of Djungarian hamsters decreased rapidly one time a day. These results show species differences in body temperature, heart rate and locomotor activity of Syrian, Djungarian and Chinese hamsters.

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Alendronate, one of the bisphosphonates, is known to have an inhibitory effect on bone resorption. The purpose of this study was to investigate the effects of alendronate on ectopic bone graft resorption and to determine the optimal dose in the mouse. The grafted bone in the control group disappeared due to resorption by osteoclasts within 5 weeks. In the experimental groups, the area of bone tissue decreased by only 20-40% at 5 weeks post-operatively. At 8 and 9 weeks after surgery, the decreased area of bone structure was significantly less in all the 10^-4 M injected alendronate-immersed groups than in the 10^-4 M non-injected alendronate-immersed. At 9 weeks after surgery, the number of osteoclasts were significantly less in the 10^-4 M injected alendronate-treated groups than in the 10^-4 M non-injected alendronate-treated groups. These results suggest that alendronate inhibits resorption of ectopic bone graft at concentrations of 10^-4 and 10^-6 M.

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In order to improve the productivity of house musk shrews, we investigated whether a male could impregnate more than one female within 24 h. Eighteen males and 40 females aged one year were used in this experiment. The mating systems were as follows: one male was paired with one female, one male was paired with two females, and one male was paired with four females. In the fertility rate, six out of 6, 4 of 12 and 4 of 20 females became pregnant and gave birth under three systems, respectively. In the copulatory behavior, numbers of intromissions and ejaculations were more in the 1:1 mating group as compared with the 1:2 and 1:4 groups. We conclude that it is possible for a male to impregnate about one female within 24 h.

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We have reported the effect of di(2-ethylhexyl)phthalate (DEHP) on the tryptophan (Trp)-niacin pathway in rats. To clarify the universal effect of DEHP on rodents, we studied whether DEHP also has an effect on Trp metabolism in mice. Mice were fed a niacin-free, 20% casein diet supplemented with DEHP for 21 days. Feeding with DEHP decreased the body weight gain and increased the liver weight in correlation with the dose level of DEHP. The administration of DEHP significantly increased the formation of quinolinic acid and the lower metabolites of the Trp-niacin pathway. The flux of niacin in the lower part of the Trp-niacin pathway in mice was enhanced by feeding with DEHP.

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Slip-down behavior from a raised platform of Slc:ddY mice was examined. Mice intraperioneally injected with 1 or 1.5 mg/kg of methamphetamine (MAP) slipped down from a raised platform of 10 cm diameter and 20 cm height within 5 min, 20 min after the injection. After pretreatment five times with 1 mg/kg MAP at intervals of 3 days, the slip-down was induced after injection of 0.5, 1 or 1.5 mg/kg MAP, but after pretreatment ten times with 1 mg/kg MAP at intervals of 3 days the behavior was not recognized at the same doses. These phenomena were like reverse-tolerance and tolerance. The situational change of the MAP treatments, placement on the platform after each pretreatment, did not affect the phenomena. The present findings strongly suggest that the slip-down is a behavior affected by the dose and number of administration of MAP, but not by the treatment situation.

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In this report we describe a means of general anesthesia for medium-duration (i.e., 20 to 60 min) surgery of infant mice. We tested isoflurane inhalation (2.0% isoflurane in air or oxygen during induction, and 1.5% after surgical anesthesia) anesthesia of 6-to 10-day-old C57BL/6JJcl mice and obtained safe, effective, and reproducible results.

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Age-related changes in hematological values, serum biochemical constituents, and weights of various organs in both sexes of the Spontaneously Hypertensive (SHR/Izm), Stroke-prone SHR (SHRSP/Izm), and Wistar Kyoto (WKY/Izm) rat strains, bred under SPF conditions, were examined to obtain fundamental data. The body weights from 3-30 weeks and systolic blood pressure from 6-30 weeks in each strain were measured every week. At the ages of 8, 16, and 30 weeks, the hematological values (erythrocyte, hemoglobin, hematocrit, leucocyte, thrombocyte), serum biochemical constituents (total protein, GOT, GPT, ALP, BUN, creatinine, glucose, total Ca and phosphorus, and ionized Ca, Na, K, and Cl were measured. Also, the organs, brain, heart, lung, thymus, liver, spleen, pancreas, bilateral kidneys, adrenal glands, testes/ovaries, digestive tract, and muscle (soleus) were weighed. The age-related changes as well as the strain and sex differences in each measured item were examined. The body weights of each strain increased, but rate of the increase was less in SHR and SHRSP, and was lowest in SHRSP. The blood pressure of SHR and SHRSP elevated with age, and showed higher in SHRSP than SHR, while that of WKY did not change. There were many strain differences in most measured items at each time point, particularly at 30 weeks. In SHRSP, high values of BUN, creatinine, total and ionized Ca, weights of brain, heart, liver, kidney and digestive duct were observed at most time points indicating that this strain's abnormality of calcium metabolism may be related to functions of the kidney and digestive duct as well as hypertension.

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Rat myelin vacuolation mutation at the Attractin locus (Atrn^mv) is a genomic deletion including the whole exon 1 of the Atrn gene. The precise size and location of the deleted region has not yet been identified because of poor information on genomic organization of the rat Atrn gene. Here, we identified the breakpoints of the Atrn^mv mutation, using a draft sequence of the rat genome. In the Atrn^mv/mv rat, a 6,914-bp genomic region was deleted. Primers flanked 5'- and 3'- breakpoints amplified the Atrn^mv allele but not the wild-type allele. This primer set enables us to distinguish Atrn^mv/+ heterozygous rats from Atrn^+/+ rats, and will contribute to the efficient production of Atrn^mv/mv rats.

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Two spontaneous mutant beige rats, with phenotypes resembling human Chediak- Higashi syndrome (CHS), were found independently in two inbred strains. Both beige mutations were identified to be recessive alleles in the Lyst locus on rat chromosome 17 and the alleles were denoted Lyst^bg and Lyst^bg-Kyo. As it is almost impossible to discriminate these mutations phenotypically, we developed an allele-specific genotyping method for the Lyst gene. The nested PCR amplification was followed by restriction fragment length polymorphism (RFLP) analysis. By this method, we could discriminate the mutant Lyst^bg, Lyst^bg-Kyo alleles, and the normal Lyst allele, easily and accurately.

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（正）Fig. 2 should be deleted.

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