Shin-ichi Itagaki

Preliminary comparisons of the biological properties of two strains of feline immunodeficiency virus (FIV) isolated in Japan with FIV Petaluma strain isolated in the United States

SummaryTwo strains of feline immunodeficiency virus (FIV) were isolated directly from peripheral blood mononuclear cells (PBMCs) of Japanese domestic cats or indirectly from PBMCs of specific pathogen free (SPF) cats inoculated with whole blood from naturally infected cats with FIV by cocultivation with primary PBMCs from SPF cats. Two isolates, designated as FIV TM 1 and FIV TM 2, had a lentivirus-like morphology by elecron microscopy, a tropism for interleukin-2 dependent T-lymphocytes and Mg2+-dependent reverse transcriptase activity. By immunoblotting the isolates gave bands at 130, 48, 44, 40, 28, 17, and 13 kDa, and these bands except 130 kDa were detected in FIV Petaluma strain when reacted with the plasma of cats infected naturally with FIV TM 1 strain.

Characterization of an integrase mutant of feline immunodeficiency virus

SummaryThe role of the integrase region of feline immunodeficiency virus (FIV) in viral replication was examined using an integrase mutant clone of FIV which carries a frameshift mutation in the region. Upon transfection, although the integrase mutant was able to release virus-like particles into the supernatant from the transfected cells, the virions produced by the mutant contained unprocessed gag precursor protein and undetectable levels of reverse transcriptase activity. Furthermore, the mutant virions were unable to direct the synthesis of viral DNA after infection in target cells. To understand this phenotype of the integrase mutant in more detail, we constructed a gag-pol expression plasmid from an FIV molecular clone and assayed roles of the integrase region on virus particle formation following transfection. When an inframe deletion was introduced into the protease region of the expression plasmid, the mutant was able to efficiently release gag- and gag-pol precursor proteins into the supernatant from the transfected cells. An expression plasmid with mutations in both the protease and integrase regions, however, failed to release the gag-pol precursor protein from the cells. These results suggested an essential role for the integrase region for efficient incorporation of the gag-pol precursor into the virions.

Amelioration of the β‐cell dysfunction in diabetic APA hamsters by antioxidants and AGE inhibitor treatments

In our recent report, probucol treatment ameliorated glucose intolerance and increased the insulin‐positive area in the pancreas of streptozotocin (SZ)‐induced diabetic APA hamsters. The data suggested that the beneficial effects of probucol treatment on β‐cell function might result from its additive effect as an antioxidant. Here, we examined the antioxidant effects on the β‐cell function in SZ‐induced diabetic APA hamsters treated with three different agents, N‐acetyl‐L‐cysteine (NAC), aminoguanidine (AG) and pyridoxamine (PM).

Activation of feline immunodeficiency virus long terminal repeat by feline herpesvirus type 1.

By transfection of a recombinant plasmid containing the feline immunodeficiency virus (FIV) long terminal repeat (LTR) linked to the chloramphenicol acetyltransferase (CAT) gene followed by infection of feline herpesvirus type 1 (FHV-1) into Crandell feline kidney cells and Felis catus whole fetus 4 cells, enhancement of CAT activity was demonstrated. Furthermore, individual feline T-lymphocytes were productively co-infected with both FIV and FHV-1 in vitro as determined by two-color immunofluorescence and electron microscopy analyses. These results revealed the transactivation of the FIV LTR by FHV-1 and the dual infection of T-lymphocytes with both viruses. The possibility that FHV-1 might be a cofactor which plays a role in the pathogenesis of FIV infection is discussed.

Hepatic changes of mice in the subacute phase of streptozotocin (SZ)-induced diabetes

Hepatic changes of mice in the subacute phase of streptozotocin (SZ)-induced diabetes were investigated biochemically and pathologically. Biochemically, the contents of serum glucose and of serum and liver lipids increased while the content of liver glycogen decreased in SZ-induced diabetic mice. Histopathologically, hypertrophy of hepatocytes due to an increase in number of intracytoplasmic acidophilic granules was common to SZ-induced diabetic mice. Electron microscopically, these hepatocytes were characterized by a prominent increase in number of mitochondria showing normal structure, a marked decrease of glycogen granules and poorly developed rough endoplasmic reticulum, which were common to so-called oncocytic cells. In some SZ-induced diabetic mice, bile duct hyperplasia with an appearance of cytomegalic hepatocytes was also observed.

AGE-DEPENDENT REMODELING OF PERIPHERAL BLOOD CD4+ CD8+ T LYMPHOCYTES IN CYNOMOLGUS MONKEYS

Recently, we have found in adult cynomolgus monkeys that substantial peripheral blood CD4+ CD8+ double-positive (DP) T lymphocytes exhibit a resting memory phenotype and increase in proportion with age. In this study, we investigated whether phenotypic changes occur in the course of the increase in proportion of the DP T cells. The results obtained from 195 clinically healthy monkeys aged from 1 month to 31 years showed that the CD29hi and CD28 subpopulation in the DP T subset increased in proportion with age and that the increase reached a plateau at six years old for the CD29hi subpopulation and at eleven years old for the CD28 one, respectively. The phenotypic alteration preceded the abrupt increase in proportion of the DP T cells and was able to be classified into four phases on the basis of the qualitative and quantitative alteration.

Histopathology of subacute renal lesions in mice induced by streptozotocin

Streptozotocin (SZ) was inoculated intraperitoneally to male and female mice of ICR and BALB/c strains in a different way of administration (A: single injection and B consecutive 5 days-injection) and subacute renal changes were examined light and electron microscopically 8 weeks after SZ-administration. The following changes were detected: (1) reduction in the rate of male-type Bowmans capsules in male mice, (2) karyocytomegaly of proximal tubular epithelial cells, and (3) dilation of distal tubules Tubular changes were detected with high incidence in A (males and females) and B groups (males) of ICR strain.

Hair follicles of young Wistar strain hairless rats: a histological study

The histological changes in hair follicles in hairless rats derived from the Wistar strain (hW, hairless Wistar) were examined from birth to maturity and compared with those of age‐matched normal Wistar rats. In the 1st hair cycle, the hair follicles of hW rats were shorter and less well developed than those of Wistar rats. In early anagen, eosinophilic bodies were observed in some hair follicles which showed immature histological features. By using Tdt‐mediated dUTP nick end labelling (TUNEL) method and electron microscopic examination, these bodies were confirmed to be apoptotic bodies. These follicles seemed to disappear by abnormal regression. In late anagen phase, the follicles in which the apoptosis did not occur showed enlarged hair roots with hypertrophy of the inner root sheath. Subsequently, when the follicles in normal Wistar rats synchronously regressed in the catagen phase, most of the follicles in hW rats similarly entered the catagen phase, but a few follicles did not regress completely and showed aberrant hair root enlargement. Finally, both types of follicle in hW rats formed follicular cysts. These abnormalities in follicle development (abnormal follicular regression and follicular cyst formation) appear to be associated with the hairlessness in this rat strain.

Modification of spontaneous renal lesion of APA hamsters by streptozotocin-induced diabetes

Syrian hamsters of the APA strain (APA hamsters) develop spontaneous mesangial thickening in the renal glomeruli from an early age. They also develop focal and segmental glomerulosclerosis (FSG) at and after 6 months of age. In this study, histopathological, immunohistochemical and lectin histochemical examinations were conducted to clarify the modification of the spontaneous renal lesions of APA hamsters by streptozotocin(SZ)‐induced diabetes. Histopathological analysis revealed that the expansion of the mesangial region was more prominent and the thickening of the glomerular basement membrane (GBM) was weaker in SZ‐treated animals than in non‐treated ones. Immunohistochemical analysis suggested that type IV collagen and laminin were involved in the expansion of the mesangial region and thickening of the GBM. In lectin histochemical analysis, podocytes, capillary endothelial cells, GBM and a part of mesangial region of SZ‐treated animals were positive for RCA120 and GSL‐I with neuraminidase‐pretreatment although they were negative for these lectins in non‐treated animals. These results suggest that the spontaneous glomerular lesion of APA hamsters is modified qualitatively and quantitatively by SZ‐induced diabetes.

Histopathological sequence of hepatic and renal lesions in rats after cessation of the repeated administration of CCl4.

The histopathological sequence of hepatorenal lesions in rats after cessation of the repeated administration of CCl4 (0.5 ml/kg, p.o., twice a week for 12 weeks) was examined. In the liver, cirrhotic lesions reduced rapidly after cessation of the CCl4-administration and collagen bundles surrounding the pseudolobules almost disappeared 12 weeks later. In contrast, in the kidney, vacuolation of epithelial cells in the proximal tubules disappeared rapidly but glomerular lesions progressed even after cessation of the CCl4-administration, and marked glomerulosclerosis developed 12 weeks later. Electron microscopically, marked expansion of the mesangial region due to increases of mesangial cells and matrix material, irregular thickening of the capillary basement membrane with mesangial interposition, and various degenerative changes in podocytes including deposition of small-sized droplets were observed.