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Biomedical subjects

Y Mimura

Publications and source records attributed to Y Mimura.

At least 73 records · Page 4Linked to original sources
PubMed1997

Alterations of renal V1 and V2 receptors in spontaneously hypertensive rats and DOCA-salt hypertensive rats using computerized quantification for macro-autoradiogram.

We previously examined the precise localization of vasopressin (VP) V1 and V2 receptors in the rat kidney using in vitro macro- and micro-autoradiography (ARG), and established the methodology of quantification for macro-ARG. In this study, to elucidate the role of VP in hypertension, we investigated the change within V1 and V2 receptors in the kidney of spontaneously hypertensive rats (SHR) and deoxycorticosterone acetate (DOCA)-salt hypertensive rats at different hypertensive stages. In SHR, although medullary V1 and V2 receptors decreased compared with age-matched Wistar-Kyoto (WKY) rats at the developmental hypertensive stage, these receptors increased once hypertension was established. Conversely, in DOCA-salt hypertensive rats, both renal V1 and V2 receptors decreased with elevated blood pressure. Therefore, expression of renal V1 and V2 receptors proved to be different between two models of hypertension, SHR and DOCA-salt hypertensive rats, when their blood pressure increases. In DOCA-salt hypertensive rats, renal V1 and V2 receptors may be down-regulated secondary to the high blood VP level. In SHR, the increase in renal V1 and V2 receptors may have a role in the development of high blood pressure in this strain of rats.

Animals↗
PubMed1996

Mechanism of the development of autoimmune dacryodenitis in the mouse model for primary Sjögren's syndrome.

To elucidate the mechanism of development in autoimmune lacrimal gland disease, we analyzed different aspects of autoimmune dacryoadenitis in a newly established mouse model for primary Sjögren's syndrome, focusing on the local expressions of cytokine genes, and the repertoire of T cell receptor (TCR) V beta genes transcribed within the inflammatory infiltration in the lacrimal glands. We found that the vast majority of inflammatory infiltration into the lacrimal glands were CD4+ V beta 8+ T cells. We detected the up-regulation of local cytokine genes (IL-1 beta, TNF-alpha, IL-2, IFN-gamma, IL-10, IL-12p40) in the lacrimal glands with very early inflammatory lesions by reverse transcriptase (RT)-PCR analysis. The predominant expression of the V beta 8 gene segment was detected from a very early stage, while extensive age-related diversity of TCR V beta gene usage was observed. Single-strand conformation polymorphism (SSCP) analysis demonstrated a distinct and a common binding pattern in the PCR product of the V beta 8 gene on the infiltrating cells during the course of the disease. These data suggest that in autoimmune dacryoadenitis of the mouse model for primary Sjögren's syndrome there may be a restricted usage of TCR V beta elements on a very early stage of the autoimmune lesion to recognize unknown self-antigen, and the autoreactive CD4+ T cells constitute a unique cytokine profile in the autoimmune lacrimal gland disease.

Animals↗
PubMed1996

Immune response to different doses of a hapten of fluorescein isothiocyanate analyzed by two-dimensional affinity electrophoresis.

The immune response to different doses of a hapten of fluorescein isothiocyanate (FITC) in BALB/c mice was analyzed by two-dimensional affinity electrophoresis (2-D AEP). The mice were immunized with different doses (0.5 microgram, 5 micrograms, 50 micrograms, 500 micrograms and 2.5 mg) of FITC-conjugated bovine serum albumin (BSA). The antibodies to FITC bovine serum albumin (BSA) were separated into a large number of IgG spots due to differences in their isoelectric points (pI) and binding affinity to FITC ligand immobilized in the gel. The IgG spots, showing identical affinity to the ligand but different pI, have been considered as an IgG family. The affinity and quantity of IgG families changed with the increase in FITC-BSA dosage. With a low dose (5 micrograms) most of the families showed high affinity (Kd < 1 microM < Kd < 50 microM) and low affinity (Kd > 50 microM) antibodies were produced. The increase of FITC-BSA up to 500 micrograms markedly increased the quantity of IgG spots showing a variety of affinity to FITC. However, 2.5 mg FITC-BSA did not increase the quantity and heterogeneity of IgG spots significantly. The changes in the heterogeneity and quantity of anti-FITC antibodies and the subclass switch were observed over the course of immunization. The heterogeneity and the quantity of IgG1, IgG2b and IgG3 antibodies increased markedly during the first and the second immunization, whereas an increase in the heterogeneity and the quantity of IgG2a antibody was observed in the third immunization. This suggests that the subclass switch to IgG1, IgG2b and IgG3 and the somatic mutation of IgG1, IgG2b and IgG3 occur during the first and the second immunization, but the subclass switch to IgG2a and the somatic mutation of IgG2a seem to occur later than that of the other IgG subclasses.

Animals↗
PubMed1996

Bafilomycin A1, a specific inhibitor of vacuolar-type H(+)-ATPases, inhibits the receptor-mediated endocytosis of asialoglycoproteins in isolated rat hepatocytes.

BACKGROUND/METHODS: The role of vacuolar type H(+)-ATPases (v-ATPases) and pH gradient between the endocytic compartments and cytoplasm in the endocytosis of asialoglycoproteins was morphologically investigated in isolated rat hepatocytes using bafilomycin A1, a specific inhibitor of v-ATPases. RESULTS: Fluorescent staining by acridine orange showed that bafilomycin A2 inhibited the acidification of the endocytic compartments. Uptake of gold-conjugated asialofetuin was significantly inhibited by bafilomycin A1. However, bafilomycin A1 did not significantly inhibit uptake of a fluid phase marker, horseradish peroxidase. The number of autophagic vacuoles increased after the bafilomycin A1 treatment. However, materials in the autophagic vacuoles were rapidly degraded after the removal of bafilomycin A1. CONCLUSIONS: Results suggest that: (a) v-ATPases are necessary for acidification of the endocytic compartments; (b) the pH gradient between the endocytic compartments and the cytoplasm which is generated by v-ATPases is necessary for the receptor-mediated endocytosis of asialoglycoproteins, and (c) v-ATPases may contribute to the degradation of the materials in autophagic vacuoles.

Animals↗
PubMed1996

Phosphate and cyclic AMP excretion decreases during less than 12 hours of hypoxia in conscious rats.

Hypocapnia is known to have an antiphosphaturic effect that overcomes the phosphaturic effect of hypoxia. The objective of this study was to examine whether conscious rats exposed to acute hypoxia show a decrease in phosphate excretion due to the concomitant hypocapnia. Wistar rats weighing 200 g were exposed to hypoxia (inspired oxygen fraction = 0.10) or normoxia (inspired oxygen fraction = 0.21) for 6 h; and rats were alternately exposed to hypoxia or normoxia every 12 h for a total 36 h. Renal clearance and hormone studies were performed. Rats exposed to 6 h of hypoxia (n = 11) showed significant hypophosphaturia and decreases in absolute and fractional excretion of phosphate (0.38 +/- 0.10 microgram min-1, mean +/- SE, P < 0.0001 and 0.59 +/- 0.15%, P < 0.0001) as compared with normoxic rats (n = 11, 3.91 +/- 0.68 micrograms min-1 and 5.62 +/- 0.85%). In addition, nephrogenous adenosine 3',5'-cyclic monophosphate level per glomerular filtrate was significantly decreased (-0.87 +/- 0.64 nmol dL GF-1, P < 0.05) and plasma parathyroid hormone level was unchanged (45.2 +/- 9.5 pg mL-1) after 6 h of hypoxia as compared with normoxic rats (4.03 +/- 1.83 nmol dL GF-1 and 54.3 +/- 10.4 pg mL-1). A parallel increase in urinary noradrenaline and a decrease in dopamine excretion was observed in rats after 6 h of hypoxia. The decreased phosphate and adenosine 3',5'-cyclic monophosphate excretion during acute hypoxia were restored to normoxic levels by reoxygenation with 21% oxygen in the study of 12-h intermittent hypoxia. In summary, (1) hypoxia produced by inhalation of 10% oxygen for 12 h or less causes reduced phosphate and adenosine 3',5'-cyclic monophosphate (cAMP) excretion by spontaneously breathing rats; (2) these effects are reversed by reoxygenation and (3) hypoxia elicits a parallel increase in noradrenaline excretion and a decrease in dopamine excretion. These data suggest that renal adrenergic and dopaminergic systems play important roles in hypophosphaturia during acute hypoxia in conscious rats.

Animals↗
PubMed1996

Resistance to natriuresis in patients with peritonitis carcinomatosa.

The natriuretic effect of atrial natriuretic peptide (ANP) is blunted in certain clinical disorders such as congestive heart failure and liver cirrhosis, despite the elevated plasma ANP levels. These sodium-retaining states are characterized by increased activity of the renal sympathetic nerves. Recent studies have shown higher levels of circulating and urinary catecholamines in cancer patients. We hypothesized that the increased adrenergic activity may be responsible for ascites formation in patients with peritonitis carcinomatosa (PC). The objective of this study was to determine the renal responses to endogenous ANP in patients with PC. Patients, hospitalized at our institute for PC, were examined using renal clearance studies for 2 h. Non-cancer patients were also examined as control subjects. Statistical analysis was performed using Wilcoxon's rank sum test. The results showed that absolute and fractional sodium excretions were markedly lower in patients with PC (54 +/- 16 microEq/min, means +/- SE, p < 0.0005; 0.55 +/- 0.15%, p < 0.005) than in control patients (166 +/- 14 microEql/min; 1.14 +/- 0.09%, respectively). Plasma ANP concentration was increased in patients with PC (34.7 +/- 8.4 pg/ml, p < 0.001) in comparison with control patients (13.3 +/- 2.0 pg/ml). Plasma and urinary levels of norepinephrine were significantly higher in cancer patients (0.36 +/- 0.10 ng/ml, p < 0.05; 125 +/- 20 ng/dl GF, p < 0.05) than in the controls (0.17 +/- 0.02 ng/ml; 73 +/- 13 ng/dl GF). These results suggest that increased renal sympathetic nerve activity may contribute to the attenuation of the natriuretic effect of ANP in patients with PC.

Adult↗
PubMed1996

Clinical evaluation of carbocyclic oxetanocin G eyedrops in the treatment of herpes simplex corneal ulcers.

BACKGROUND: Acyclovir (ACV) ophthalmic ointment is effective in the treatment of herpetic keratitis. However, when applied, the ointment has an unpleasant feeling and some cases are resistant to ACV. A new antiviral compound, carbocyclic oxetanocin G (C.OXT-G) has potent anti-herpes simplex virus activity and high water solubility, so the clinical effect of C.OXT-G eyedrops on ulcerative herpetic keratitis was evaluated. METHODS: Studies were conducted on the corneal ulcers in 37 eyes of 27 patients. Patients with typical dendritic or geographic corneal ulcers were treated with 0.1% C.OXT-G eyedrops, applied five times a day, together with eyedrops of an antibiotic applied four times a day. The eyes were examined at least twice a week until the ulcers healed, and thereafter at intervals for up to 3 months. RESULTS: All of the ulcers healed, their average healing time being 4.9 (SD 2.2) (range 2 to 9) days. The ulcers in 20 of the 37 eyes were induced by the use of corticosteroid or immunosuppressive drugs, and their average healing time was 4.8 (2.3) days. No adverse drug reactions were seen during the observation period in this trial. CONCLUSION: Eyedrops containing 0.1% C.OXT-G are excellent and safe for treatment of herpes simplex corneal ulcers in humans.

Administration, Topical↗
PubMed1996

Role of the ICAM-1/LFA-1 pathway during the development of autoimmune dacryoadenitis in an animal model for Sjögren's syndrome.

We have analyzed the role of cell adhesion molecules during the development of autoimmune dacryodenitis in an NFS/sld mouse model for primary Sjögren's syndrome. The expression of cell adhesion molecules was assessed by RT-PCR and immunohistochemistry. We detected an up-regulation of local cell adhesion molecule genes (ICAM-1, LFA-1, CD44 and Mel-14) in the course of autoimmune lacrimal gland diseases. Immunohistochemically, ICAM-1 was localized exclusively in the endothelial cells of variously sized blood vessels before the onset of disease, and LFA-1, CD44 and Mel-14, expressing infiltrating cells, were found within these lesions. When the therapeutic effects of blocking cell adhesion molecules in vivo were examined, antibodies to ICAM-1 in combination with anti-LFA-1 prevented the development of autoimmune lacrimal gland diseases in NFS/sld mice. These data suggest that in Sjögren's syndrome-like autoimmune dacryoadenitis in NFS/sld mutant mice, the ICAM-1/LFA-1 pathway may play a crucial role in the development and subsequent progression of T-cell-mediated autoimmunity in the lacrimal glands.

Animals↗
PubMed1996

Manifestation of subclinical diabetes insipidus due to pituitary tumor during pregnancy.

We describe a case of diabetes insipidus (DI) due to a pituitary tumor in a 33-year-old pregnant woman who developed a sudden onset of polyuria (over 8 l/day) and polydipsia at 30 weeks of gestation. Her plasma concentration of vasopressin (AVP) was low compared with high serum osmolality (298 mOsm/kg), and her urine output was well controlled by treatment with desmopressin acetate (DDAVP). Cranial magnetic resonance imaging (MRI) demonstrated a 1.8 x 1.2-cm pituitary tumor, but she did not have any disturbance in the release of anterior pituitary hormones. The serum concentration of cystine aminopeptidase (CAP) was within the normal range for a woman at 34 weeks of gestation. After an uncomplicated delivery of a healthy girl, her polyuria gradually resolved. The size of the pituitary tumor gradually decreased in parallel to a reduction in her urine output, but a silent hemorrhage was detected in her pituitary gland 4 weeks after the delivery. Although pregnancy is sometimes associated with central DI, the occurrence of DI due to pituitary tumor under pregnancy is rare. The basal AVP recovered to within the normal range, but the low response of AVP secretion to high osmolality persisted. In this case, pregnancy may affect the manifestation of subclinical DI. This case may therefore enhance our understanding of the mechanisms of DI during pregnancy.

Adenoma↗
PubMed1996

A patient with sarcoidosis associated with recurrent urolithiasis and tubular injury caused by calcium deposition.

A 38-year-old woman was hospitalized in January 1994 with renal dysfunction and hypercalcemia. Before admission, she was diagnosed as having urolithiasis, and had been treated twice with extracorporeal shock wave lithotripsy (ESWL). Ophthalmologically, she exhibited iritis and secondary glaucoma. Hypercalcemia, an extremely low titer of parathyroid hormone (PTH), and elevation of angiotensin-converting enzyme (ACE) and lysozyme activity were noted. These findings suggested sarcoidosis, although the chest X-ray showed only fibrotic changes. Hypercalcemia was suspected of having been caused secondarily by sarcoidosis. Since her laboratory data also showed renal dysfunction and abnormal urinalysis, a renal biopsy was performed. The histological findings indicated a tubular and interstitial disorder without glomerular abnormality; calcium deposition, which was detected by X-ray energy dispersive analysis, was observed in the tubular cytoplasm. Administration of prednisolone alleviated the renal dysfunction and decreased the elevation of ACE activity and lysozyme level of the blood. Sarcoidosis is sometimes associated with hypercalcemia, but rarely with renal dysfunction. These findings suggested that sarcoidosis may be associated with renal dysfunction due to tubular injury caused by calcium deposition in the tubules, and that glucocorticoid therapy was effective for these disorders.

Adult↗
PubMed1996

[A study of acute infection of herpes simplex virus in mouse trigeminal ganglia].

We investigated the shift to latency and protective reaction in mice trigeminal ganglia after inoculation of herpes simplex virus type 1 (HSV-1) onto the cornea. BALB/c mice were inoculated and the trigeminal ganglia were removed periodically. Lymphocytes in the ganglia were observed using immunocytochemical techniques. The results obtained were as follows: (1) HSV-1 positive neuronal cells were recognized at 3 days after inoculation but not at 14 days. (2) The relative proportion of T cells in lymphocytes was greater than that of B cells at 3 days, but B cells were more numerous at 5 days. Then T cells become more numerous again at 7 days. (3) Among the subsets in T cells, the ratio of CD4+ and CD8+ cells was almost equal at 3 days, but then CD4+ cells increased and CD8+ cells had disappeared at 14 days after inoculation. These results show that HSV-1 that reached the trigeminal ganglion from the cornea by axonal transport infected neuronal cells, multiplied there and then disappeared resulting in latency. Cellular immunity, especially the function of CD4+ cells, played a main role in this protective reaction by suppressing the viral growth.

Acute Disease↗
PubMed1996

Changes in urinary enzyme activity and histochemical findings in experimental tubular injury induced by gold sodium thiomalate.

To elucidate the renal injury induced by gold treatment, we administered various doses of gold sodium thiomalate (GST) to Wistar rats and investigated alterations in the urinary enzyme activity, gamma-glutamyl transpeptidase (gamma GTP) and N-acetyl-beta-glucosaminidase (NAG) activity, and histochemical change of enzymes, gamma GTP, alkaline phosphatase (ALP) and acid phosphatase (ACP) activity in the renal tissue. The single administration of a large dose of gold salts induced acute tubular necrosis and enzyme leakage was detected histochemically without damage to the glomerulus. After chronic administration of small doses of gold salts, the urinary gamma GTP activities gradually increased, but urinary NAG activities did not. These findings suggested that the change in urinary enzyme activities, which leaked from inside of brushborder or lysosome, indicated the degree or localization of tubular damage, because renal tubules were selectively injured by gold salts.

Acetylglucosaminidase↗
PubMed1996

Role of ICAM-1 and LFA-1 in endotoxin-induced uveitis in mice.

The effect of monoclonal antibodies against adhesion molecules on the development of endotoxin-induced uveitis (EIU) and interleukin-1 (IL-1)-enhanced EIU were studied. When endotoxin or IL-1 was injected into C3H/HeN mice, the expression of intercellular adhesion molecule-1 (ICAM-1) on the ciliary body was up-regulated as determined by immunohistochemical assay. However, these agents did not alter lymphocyte function-associated antigen-1 (LFA-1) expression on leukocytes when whole blood cells were analyzed with flow cytometry. Monoclonal anti-ICAM-1 antibody or anti-LFA-1 antibody was intraperitoneally administered to C3H/HeN mice simultaneously with endotoxin, and the effect on the development of EIU was studied. The cell number in aqueous humor and frequency of posterior synechiae were markedly decreased in EIU when either antibody was administered. However, protein concentration in the aqueous humor was not statistically reduced by the injection of these antibodies. In the model of IL-1 enhanced EIU, not only the cell number and frequency of posterior synechiae but also protein concentration were decreased. Moreover, there were no differences between these two antibodies in the effect on EIU, whereas anti-LFA-1 antibody was more effective than anti-ICAM-1 antibody in IL-1-enhanced EIU.

Animals↗
PubMed1996

Detection of herpes simplex virus DNA in tear fluid of stromal herpetic keratitis patients by nested polymerase chain reaction.

The value of the polymerase chain reaction (PCR) in the diagnosis of stromal herpetic keratitis was examined using tear fluid specimens; the sensitivity of the nested PCR method in detecting the herpes simplex virus (HSV) genome was 1 plaque-forming unit/mL. PCR assay of 72 tear samples from the eyes of 15 patients with stromal herpetic keratitis detected the HSV genome in 5 (33.3%). No positive band was detected in 20 tear samples from both eyes of 10 healthy volunteers. Seven of 38 tear samples (18.4%) and 1 of 34 samples (2.9%) collected from the diseased eye and the contralateral normal eye, respectively, produced positive results; the difference in rates was statistically significant (P < 0.05). The positive rate of samples collected from the diseased eye during an active phase was 16.0% (4 of 25 samples); in the quiescent phase, 23.1% (3 of 13 samples); the difference was not significant (P = 0.45). In HSV genome-positive cases, the average number of tear collections needed to detect the HSV genome was 3.3. Results indicate that PCR assay of tear fluid provides valuable information for the diagnosis of stromal herpetic keratitis, and that repeated tear samples should be collected regardless of the phase of the phase of disease activity.

Administration, Topical↗
PubMed1995

[Phosphaturic effect of PTH during hypoxia and hypocapnia in rats].

This study examined the effect of acute hypoxia or hypocapnia on renal phosphate excretion in thyroparathyroidectomized rats. Hypoxia is usually accompanied by a secondary hypocapnia due to hypoxic hyperventilation. Respiratory alkalosis has been described as blunting the phosphaturic effect of parathyroid hormone (PTH). In the present study, to know the effect of hypoxia on renal phosphate excretion in the absence of hypocapnia, the rats were ventilated mechanically, and arterial PCO2 levels were controlled. The rats were divided into three groups depending on the arterial PO2 and PCO2 levels: 1) hypoxic normocapnic group; 2) normoxic normocapnic group; 3) normoxic hypocapnic group. Hypoxia was achieved by ventilating with 10% oxygen, and hypocapnia by hyperventilating with 25-30% oxygen. PTH infusion significantly increased fractional excretion of phosphate (FEPi) from 4.1 +/- 0.9 (mean +/- SE) to 37.7 +/- 2.6% in the hypoxic group (n = 7), from 1.4 +/- 0.3 to 27.4 +/- 2.5% in the normoxic group (n = 8), and from 1.5 +/- 0.4 to 19.5 +/- 1.2% in the hypocapnic group (n = 10). The change of FEPi (delta FEPi) after PTH infusion during hypoxia was significantly greater (33.6 +/- 2.1%) than that during normoxia (26.1 +/- 2.4%, p < 0.05). In contrast to this, hypocapnia blunted the phosphaturic response to PTH (18.0 +/- 1.1% delta FEPi, p < 0.05). Urinary adenosine 3', 5'-cyclic monophosphate (cAMP) increased similarly after PTH infusion in all three groups. To test whether the enhanced phosphaturic effect of PTH during hypoxia and the blunted phosphaturic effect of PTH during hypocapnia are due to steps beyond the production of cAMP, cAMP was administered to the three groups. Cyclic AMP infusion displayed greater phosphaturia in the hypoxic group (n = 6, 30.0 +/- 1.4%) and less phosphaturia in the hypocapnic group (n = 7, 11.3 +/- 1.8%) as compared the the normoxic group (n = 6, 24.1 +/- 1.0%). In conclusion, acute hypoxia enhances the phosphaturic effect of PTH, whereas acute hypocapnia attenuates the phosphaturic effect of PTH.

Animals↗
PubMed1995

[Acute hypocapnia attenuates phosphaturic effect of atrial natriuretic peptide in rats].

This study evaluated phosphate excretion in response to atrial natriuretic peptide during acute hypocapnia in the presence or absence of the renal nerves in rats. To achieve a hypocapnic state, rats were mechanically hyperventilated with room air. As mechanical ventilation per se has been reported to affect renal excretory functions depending on the ventilatory conditions, this study was designed to examine renal functions during acute hypocapnia as compared with those during normocapnia produced by normal and/or hyperventilation. Rats were divided into three experimental groups: 1) a normally ventilated normocapnic (control) group (n = 8), 2) a hyperventilated normocapnic group (n = 8), and 3) a hyperventilated hypocapnic group (n = 8). The innervated right kidney served as a control for the contralateral denervated kidney. Acute renal denervation produced a greater phosphaturia compared to the innervated kidney during the control period in the two normocanic groups but not in the hypocapnic group. Infusion of ANP 12 micrograms/kg/h produced a remarkable increase in phosphate excretion in either kidney in the normocapnic groups. The degree of the phosphaturia (delta FEPi%) during infusion of ANP was similar between the normally ventilated and hyperventilated normocapnic groups both in innervated (10.6 +/- 2.4% and 7.4 +/- 1.2%) and denervated (14.0 +/- 3.0% and 13.5 +/- 2.2%) kidneys. In contrast to both normocapnic groups, the hypocapnic group had a greater hypophosphaturia during the control and ANP infusion periods in either kidney. The increase in fractional excretion of phosphate was smaller both in innervated (0.34 +/- 0.34% delta FEPi) and denervated (0.72 +/- 0.69% delta FEPi) kidneys than that in the other two normocapnic groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗