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Biomedical subjects

S Itagaki

Publications and source records attributed to S Itagaki.

At least 37 records · Page 2Linked to original sources
PubMed1997

Detection of viral RNA by electron microscopic in situ hybridization (ISH-EM) in the germinal epithelium of mice infected with encephalomyocarditis (EMC) virus.

Electron microscopic in situ hybridization (ISH-EM) was first applied to the detection of viral RNA in the germinal epithelium of mice inoculated i.p. with 10(5) plaque-forming units/mouse of the D variant of encephalomyocarditis virus (EMC-D). Signals of viral RNA were first detected in a small number of Sertoli cells showing mild degeneration at 2 days post inoculation, and 2 days later, they were also detected in germinal cells and spermatogonia when Sertoli cells showed prominent degeneration. The results clearly demonstrated that the first site of viral attack in the germinal epithelium was Sertoli cell in the case of EMC-D-induced mouse orchitis.

Animals↗
PubMed1997

The skin injury induced by high energy dose of ultraviolet in hairless descendants of Mexican hairless dogs.

Histopathological changes in the dorsal skin of hairless descendants of Mexican hairless dogs (MHDs) exposed to artificial irradiation with high energy dose (180 kJ/m2) of ultraviolet (UV) rays (UVA + B) were investigated. Macroscopically, erythema and edema were observed in the irradiated skin at 1 day after irradiation (DAI), and blister formation occurred except one dog at 2 DAI. Erythema almost disappeared at 5 DAI, and at 6 DAI, the skin recovered to almost normal state. Light microscopically, sunburn cells were observed at 1 DAI. Then intercellular edema and blister formation in the epidermis and dermal edema were evident at 2 and 3 DAI. At 6 DAI, the skin showed almost normal features except for slight epidermal thickening, but melanin granules, which were distributed in almost the whole length of the epidermis before UV irradiation, were detected only in cells which seemed to be melanocytes except one dog. Dihydroxyphenylalanine (DOPA)-positive melanocytes almost disappeared at 1 and 2 DAI, and at 6 DAI, the number of DOPA-positive melanocytes increased over the level before UV irradiation. The ultrastructural features of melanocytes were characterized by vacuolated cytoplasm, decreased melanosomes, irregular-shaped nuclei and shortened dendrites at 1 DAI, and returned to normal at 6 DAI. These findings of melanocytes reflect the severity of the skin injury and support weak suntan reaction in this case. In conclusion, severe form of UV-induced skin injury seen in humans could be reproduced in hairless descendants of MHDs exposed to high energy dose of artificial UVA + B.

Animals↗
PubMed1997

Ultrastructure of atheromatous lesions experimentally induced in Syrian hamsters of the APA strain.

In order to examine whether diabetes enhances, primary aortic lesions up to atherosclerotic ones, mild primary lesions were induced in aorta of APA hamsters by an administration of vitamin D2 (VD) and/or stop-and-reflow (SR)-operation, a modification of renal artery clamping. At 2 months after the treatment with the combination of VD-administration and SR-operation, atheromatous lesions, characterized by an appearance of many foam cells in the intima, were observed in the abdominal aorta, the site of SR-operation, in streptozotocin (SZ)-induced diabetic APA hamsters. Foam cells in the atheromatous lesions were originated from smooth muscle cells and monocyte/ macrophages. On the other hand, neither VD-administration alone nor SR-operation alone developed atheromatous lesions in SZ-induced diabetic APA hamsters. In conclusion, we succeeded in a rapid induction of atherosclerotic lesions in abdominal aorta of SZ-induced diabetic APA hamsters by the combination of VD-administration and SR-operation.

Animals↗
PubMed1997

[The EMG findings of spasmodic torticollis--the character of the EMG findings of neurogenic torticollis].

Spasmodic torticollis is a clinical entity that is hard to treat though various symptomatic therapy have been tried. On the other hand, microvascular decompression operation have been established for cranial nerve vascular compression syndrome such as hemifacial spasm. Case reports on the decompression of the spinal accessory nerve for the treatment of spasmodic torticollis have been published on the basis of the concept of cranial nerve vascular compression syndrome. Thus, spasmodic torticollis related to unilateral accessory nerve has attracted much attention for selecting an optimal treatment, although there have not been any diagnostic criteria with electromyographic study. From the viewpoint of the clinical electrophysiological findings on hemifacial spasm those we have acquired by EMG study, we have examined the EMG findings of various types of spasmodic torticollis and here report the classification of spasmodic torticollis based on the EMG study. Thirty-five patients with spasmodic torticollis were analyzed. The symptoms were classified to the horizontal rotation type, the lateral bending type and the mixed type with the number of each group of 23, 2 and 10, respectively. As we have shown the criteria of the EMG findings on hemifacial spasm, the EMG of the patients with spasmodic torticollis were analyzed on four conditions as follows; (1) distribution of the involved muscles, (2) maximum firing rate of the abnormal spontaneous activity of the sternocleidomastoid muscle, (3) synkinetic discharge between the muscles innervated by unilateral accessory nerve and (4) alteration of the spontaneous muscle discharge by posture change. Abnormal spontaneous muscle discharges were recorded only from the sternocleidomastoid muscle and the trapezius muscle on the same side in twelve patients. Maximum firing rate of spontaneous muscle discharge was higher than that of maximum voluntary contraction in twenty-two patients. Abnormal synkinetic discharge was recorded between the sternocleidomastoid muscle and the trapezius muscle on the same side in twenty-one patients. Spontaneous EMG activities of the muscles innervated by the accessory nerve increased when the patients stood up from the resting supine position in thirty-one patients. Thus, ten patients out of thirty-five subjects had all four conditions mentioned above as typical patients with hemifacial spasm usually had. These ten patients with spasmodic torticollis were thought to have strong similarity to the EMG characteristics of hemifacial spasm that suggested hyperexcitability of unilateral accessory nervous system. This classification with EMG is considered to be useful in diagnosing the spasmodic torticollis related to unilateral accessory nerve and can be applied for selecting an optimal treatment.

Accessory Nerve↗
PubMed1996

Relation between distribution of viral RNA and development of histopathological changes in encephalomyocarditis virus-induced orchitis in mice.

The relation between the distribution of viral RNA and the development of histopathological changes was investigated in the early stage of encephalomyocarditis (EMC) virus-induced orchitis in mice. Signals of viral RNA were first detected by in situ hybridization in a few Sertoli cells in almost intact germinal epithelia at 2 days post-inoculation (d.p.i.). The number of Sertoli cells bearing signals of viral RNA increased at 3 d.p.i. when mild degenerative changes were exceptionally found in germinal epithelia. Signals of viral RNA came to be detected not only in Sertoli cells but also in a small number of germinal cells and spermatogonia at 4 d.p.i. when mild to moderate degenerative changes developed in germinal epithelia, resulting in desquamation of degenerated cells. At the same time, virus-like particles were observed by electron-microscopy in the degenerated and desquamated germinal cells. At and after 5 d.p.i., luminal obstruction with cellular debris and inflammatory cells was generally found. These results suggest that EMC virus carried to seminiferous tubules via the blood first attacks Sertoli cells and then damages germinal cells and spermatogonia.

Animals↗
PubMed1996

Depletion of Mac1-positive macrophages protects DBA/2 mice from encephalomyocarditis virus-induced myocarditis and diabetes.

DBA/2 mice treated with anti-Mac1 monoclonal antibody (MAb) failed to develop encephalomyocarditis virus (EMCV)-induced diabetes and myocarditis. Virus concentrations and the number of viral RNA-positive cells in the pancreas and heart were significantly reduced in mice treated with anti-Mac1 MAb. Mac1-positive macrophages seem to be involved in EMCV-induced disease and to affect the replication of EMCV in target organs.

Animals↗
PubMed1996

Molecular cloning and characterization of a new member of the rat placental prolactin (PRL) family, PRL-like protein D (PLP-D).

The rat placental PRL family consists of molecules structurally similar to PRL and GH, and to date, seven members have been identified. During investigation of pregnancy stage-specific placental factors by the differential display method, we obtained a complementary DNA (cDNA) fragment (199 bp) encoding a peptide homologous to PRL-like protein (PLP)-C. By using the 3' and 5' rapid amplification of cDNA ends method, a full-length cDNA was cloned and tentatively named PLP-D. The cDNA encoded a mature protein of 240 amino acids, including a 29-amino acid signal sequence. PLP-D contains one putative N-glycosylation site and six cysteine residues that are highly conserved in the placental PRL family. Sequence comparison between PLP-D and other members of the placental PRL family showed that PLP-D is highly homologous to PLP-C (80%) and decidual PRL-related protein (73%). Northern blot analysis revealed that PLP-D messenger RNA (mRNA) first appeared at day 14 of pregnancy, and that its expression increased until term. In situ hybridization analysis indicated that PLP-D mRNA was specifically expressed in spongiotrophoblast cells and trophoblast giant cells of the placental junctional zone. Differentiated Rcho-1 cells also expressed PLP-D mRNA, whereas undifferentiated Rcho-1 cells did not.

Amino Acid Sequence↗
PubMed1996

Age-related histochemical and ultrastructural changes in renal glomerular mesangium of APA hamsters.

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, histochemical and electron microscopical examinations were conducted to clarify the age-related renal glomerular changes in spontaneous FSG of APA hamsters. Histopathological analysis revealed that expansion of the mesangial region and thickening of the glomerular basement membrane (GBM) in the glomeruli of APA hamsters progressed with age. These age-related changes appeared earlier in male animals. Immunohistochemical analysis suggested that type IV collagen was responsible for the expansion of the mesangial region and thickening of the GBM. In lectin histochemical analysis, positive sites for WGA with and without neuraminidase pretreatment and PNA with neuraminidase pretreatment were detected mainly in podocytes and were expanded with age. Ultrastructurally, the increase in basement membrane-like materials in the mesangial matrix, development of intracellular organella of mesangial cells and migration of a part of the mesangial cell cytoplasm into the GBM were observed at and after 6 months of age. These features suggested that mesangial cells played an important role in the age-related expansion of the mesangial region and thickening of the GBM.

Aging↗
PubMed1996

Involvement of macrophages in the development of encephalomyocarditis (EMC) virus-induced diabetes in mice.

The role of macrophages in the development of diabetes following infection with encephalomyocarditis (EMC) virus was examined in 3 strains of mice (DBA/2 and BALB/c: susceptible, C57BL/6: resistant). After infection with 100 plaque forming units (PFU)/head of EMC-D (highly diabetogenic variant), the incidence of diabetes at 3 days post infection (DPI) (DBA/2: 7/8, BALB/c: 3/8, C57BL/6: 0/8) was well correlated with the severity of macrophage infiltration with beta cell damage in the pancreatic islets (DBA/2: sever, BALB/c: moderate, C57BL/6: slight). Silica-pretreatment depleted macrophage infiltration in the pancreatic islets and decreased the incidence of diabetes at 7 DPI from 100% to 40% in DBA/2 and from 80% to 0% in BALB/c mice, respectively. These results suggest that macrophages play a critical role in the process of pancreatic beta cell damage in EMC virus infection in mice.

Animals↗
PubMed1995

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 Bowman's 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.

Animals↗
PubMed1995

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.

Animals↗
PubMed1995

Intracellular killing of Listeria monocytogenes in the J774.1 macrophage-like cell line and the lipopolysaccharide (LPS)-resistant mutant LPS1916 cell line defective in the generation of reactive oxygen intermediates after LPS treatment.

Listeria monocytogenes is a facultative intracellular pathogen and survives within phagocytic cells by escaping from phagosomes into the cytoplasm. It has been reported that, in vivo, L. monocytogenes is effectively eliminated through cell-mediated immunity, especially by macrophages which have been immunologically activated by cytokines such as gamma interferon (IFN-gamma). However, this killing mechanism for L. monocytogenes and the role of macrophage activation in this bacterial killing are unclear. We demonstrated the listericidal effect of oxidative radicals induced by lipopolysaccharide (LPS) and IFN-gamma, using a macrophage-like cell line, J774.1, and a mutant cell line, LPS1916. LPS1916 cells do not exhibit normal generation of O2- and H2O2 after treatment with 0.1 microgram of LPS per ml, although J774.1 cells generate 100 times the normal level of oxidative radicals with the same LPS treatment. The growth of L. monocytogenes was strongly inhibited in J774.1 cells pretreated with 0.1 microgram of LPS per ml or the combination of 0.1 microgram of LPS per ml and 10 U of IFN-gamma per ml. On the other hand, in LPS1916 cells, the growth of L. monocytogenes was not inhibited by treatment with LPS only, although LPS1916 cells pretreated with the combination of LPS and IFN-gamma showed moderate inhibition of listerial growth. This killing was not influenced by treatment with NG-monomethyl-L-arginine, which is a strong inhibitor of nitrite oxide generation. Interestingly, J774.1 cells treated with LPS did not show enhanced intraphagosomal killing of a nonhemolytic strain of avirulent L. monocytogenes that lacks the ability to escape from phagosomes, and this killing was not influenced by treatment with NG-monomethyl-L-arginine either. These results suggest that the reactive oxygen radicals are more important than nitric oxide in the mechanism underlying the intracellular killing of virulent L. monocytogenes and that there seem to be different killing mechanisms for virulent and avirulent strains of L. monocytogenes in activated-macrophage cell lines.

Animals↗
PubMed1995

Early development of encephalomyocarditis (EMC) virus-induced orchitis in Syrian hamsters.

Lesions associated with encephalomyocarditis (EMC) virus in the testes of Syrian hamsters were investigated. Histopathologic changes were first detectable by light microscopy at 3 days postinoculation (DPI). Immunohistochemically, virus antigens were detected in the cytoplasm of germ cells and Sertoli cells in some seminiferous tubules beginning at 2 DPI. The following ultrastructural changes were observed: 1) swelling of mitochondria and dilatation of endoplasmic reticulum in germ cells, 2) large number of residual bodies in seminiferous tubules, 3) aggregates of virus-like particles in the cytoplasm of degenerated cells and tubular lumen, 4) condensation of cytoplasm and dilatation of endoplasmic reticulum in Sertoli cells, and 5) degenerative changes in capillary endothelial cells.

Animals↗
PubMed1995

Establishment of carrier-state infection of a feline renal cell line with feline syncytial virus.

Although feline syncytial virus (FSV) is normally highly cytopathogenic in Crandell feline kidney cells, a non-cytopathic persistent infection was established in the cells after cocultivation of the initially infected cells with uninfected cells 4 times. More than 90% of the persistently infected cells were positive for FSV antigen, and electron microscopy showed that the culture produced morphologically normal FSV. Virus from the carrier culture was infectious, however, the titer of the virus from the culture was lower than that from the cytocidally infected CRFK cells.

Animals↗
PubMed1995

Dermal histology of hairless rat derived from Wistar strain.

The dermal histology of 9-week-old hairless rats derived from Wistar rats was investigated and compared with that of age-matched Wistar rats. Skin samples were taken from 4 portions: the head, dorsal and ventral skin, and foot pad. The epidermis of the 3 portions other than the foot pad was thicker in hairless rats than in Wistar rats. The hair canals of hairless rats contained lamellar cornified tissues instead of hair, and some of the hair follicles deep in the dermis exhibited cyst formation. S-100-immunoreactive cells were detected in the basal layer of epidermis and their number in hairless rats was greater than that in Wistar rats. Ultrastructurally, electron-lucent cells, i.e. Langerhans cells, which contained Birbeck granules and/or cored tubules, were observed more frequently in the epidermis of hairless rats than in that of Wistar rats. Some cells in one hairless rat, which had similar characteristics to Langerhans cells without Birbeck granules, contained confronting cisternae.

Animals↗
PubMed1995

Ultrastructure of the dorsal skins of hairless descendants derived from Mexican hairless dogs.

Ultrastructural characteristics of the dorsal skin of hairless descendants derived from Mexican hairless dogs (3-month-, 1-year- and 5-year-old) were investigated and compared with those of age-matched beagles. Except that beagles had no melanocytes in epidermis, there was no essential difference in ultrastructural characteristics of epidermis between hairless dogs and beagles. In the Stratum basale of epidermis of hairless dogs, a small number of melanocytes and a few Langerhans cell (LC)-like cells were observed among keratinocytes. Melanocytes contained many melanosomes and a few premelanosomes. LC-like cells were characterized by electron-lucent cytoplasm and lobulated nucleus and lacked melanin granules, tonofilaments and desmosomal attachments. Unlike LC in humans and rodents, these LC-like cells did not contain Birbeck granules. Although age-related ultrastructural changes of dorsal skin were generally not clear both in hairless dogs and in beagles, cells containing melanin granules were not infrequently observed among dermal collagen bundles in 5-year-old hairless dogs.

Animals↗