Search PubMed⌕ Search

Biomedical subjects

S Kawamura

Publications and source records attributed to S Kawamura.

At least 217 records · Page 12Linked to original sources
PubMed1994

Therapeutic effects of nilvadipine on rat focal cerebral ischemia.

The present study was conducted to investigate the therapeutic effects of nilvadipine, a Ca2+ entry blocker, on rat focal cerebral ischemia. Under halothane anesthesia, a 3-0 nylon thread was introduced into the neck internal carotid artery to occlude the left middle cerebral artery. Either nilvadipine (3.2 mg/kg) or vehicle was administered subcutaneously 1, 2, 3, 4, 5 and 6 h following the occlusion (groups 1-6, respectively). Twenty-four hours after the occlusion, the percentage infarct volumes in nilvadipine-treated animals in groups 1-3 (21 +/- 11%, 24 +/- 11%, and 26 +/- 7%, respectively) were smaller than those in the respective control groups (36 +/- 5%, 35 +/- 3%, and 35 +/- 3%; P < 0.05). Compared with controls, the infarct size of the periphery of the fronto-parietal cortex decreased in nilvadipine-treated animals. The results indicate that nilvadipine decreases the size of infarction when administered up to 3 h after an ischemic insult. Thus, nilvadipine can be considered a potential therapeutic agent for acute focal cerebral ischemia, and may be clinically useful in stroke patients.

Animals↗
PubMed1994

Effects of increased intracranial pressure in brain surface microcirculation in rats.

The effects of increased intracranial pressure (ICP) on pial vessel diameters were investigated in rats using a cranial window and fluorescence microscopy. The brain surface was superfused with mock cerebro-spinal fluid (CSF) at a constant rate (5 ml/h), and the ICP was raised up to 20 mmHg by elevating a CSF-reservoir connected to the CSF-outlet of the window. Arterioles dilated as the ICP increased (+ 12% dilation at 20 mmHg ICP). Following a rapid reduction of the raised ICP to normal, arteriolar diameters did not return to control values (+ 7% dilatation), while venules dilated (+ 3%), indicating reactive hyperaemia. At this time, CO2 inhalation induced a low response in the arterioles (+ 0.4%/mmHg PaCO2 increase) and an over-response in the venules (+ 0.3%/mmHg). The CO2 response decreased in smaller arterioles (< or = 30-40 microns phi). In addition, a few animals showed extravasation of Na(+)-fluorescein administered intravenously. Our results indicate that reactive hyperaemia can take place following a rapid return from an increased ICP to an normal level, even in cases of mild intracranial hypertension; a disruption of the blood-brain barrier may follow.

Animals↗
PubMed1994

Haemodynamic and metabolic changes following extra-intracranial bypass surgery.

In order to study the haemodynamic and metabolic changes following bypass surgery, the regional cerebral blood flow (rCBF), the oxygen extraction fraction (rOEF), the cerebral metabolic rate of oxygen (rCMRO2), and the cerebral blood volume (rCBV) were measured using a positron emission tomograph (PET) on 13 patients who had unilateral internal carotid artery and/or middle cerebral artery occlusion. The patients were divided into two subgroups according to pre-operative rOEF values from the arterial occlusion side: the misery perfusion group, which had high rOEF values (> or = 0.56), and the coupling perfusion group, which had normal rOEF values (0.38-0.48). A post-operative PET study was performed 1-2 months and/or 1-5 years following the surgery. Six of the misery perfusion cases showed a post-operative CBF increase, where an accompanying OEF decreased to its normal level, indicating an attenuated misery perfusion state. The CMRO2 values, however, remained low. The other 7 coupling perfusion cases had an ipsilateral CBF increase in the earlier PET study. We conclude that misery perfusion is attenuated following bypass surgery, although the procedure does not consistently improve oxygen metabolism.

Aged↗
PubMed1994

Reversible middle cerebral artery occlusion in rats using an intraluminal thread technique.

We investigated the temporal profile for neuropathologic outcomes after cerebral ischemia using a rat model of reversible middle cerebral artery occlusion, where reperfusion can be introduced in nonanesthetized rats. Reperfusion was performed 1 hour to 5 hours after the occlusion. Control animals underwent permanent occlusion. The results indicate that the time window to reduce infarct volume is 2 hours, and that a > or = 3-hour duration of ischemia is sufficient to attain the maximal infarction observed after permanent ischemia. This suggests that any therapies that follow the therapeutic window will provide little benefit for transient cerebral ischemia and reperfusion injury.

Animals↗
PubMed1994

Photoreceptor light-adaptation mediated by S-modulin, a member of a possible regulatory protein family of protein phosphorylation in signal transduction.

In vertebrate retinal photoreceptors, cytoplasmic [Ca2+] decreases upon exposure to light. A Ca(2+)-binding protein, S-modulin, detects this [Ca2+] decrease and reduces the light-sensitivity of the cell to induce light-adaptation. The reduction of the sensitivity is attained by disinhibition or facilitation of rhodopsin phosphorylation, a quenching mechanism of light-activated rhodopsin. S-modulin-like proteins are found in the brain as well. Several of these proteins show similar S-modulin effects, suggesting that these proteins also participate in the regulation of protein phosphorylation in the signal transduction in their host cells.

Adaptation, Physiological↗
PubMed1994

Effects of chronic treatment with clofibric acid on response of rat hepatocytes to mitogenic stimuli.

Mitoinhibitory effects of clofibric acid (CA) were investigated in rat hepatocytes in vitro and in vivo. Female Sprague-Dawley rats, 11 weeks of age, were dietetically treated with CA at 9000 ppm for up to 13 weeks. In the in vitro study, hepatocytes were isolated from rats on day 4 and in weeks 1, 2, 5, 9 and 13, and cultured for 48 h in a medium containing epidermal growth factor. Over the last 24 h, bromodeoxyuridine (BrdU) was added to the medium to determine number of hepatocytes in S-phase. The labeling index (LI) of CA-treated hepatocytes in culture was below control values as early as day 4, and progressively declined with increasing treatment period. In the in vivo study, rats were 2/3 partially hepatectomized at week 13 and maintained for 24 h. BrdU was injected intraperitoneally 1 h prior to necropsy. The LI in the CA-treated liver was also decreased. These data indicated that continuous treatment of CA resulted in decreases in hepatocyte response to growth stimuli, and suggested a possible relation between the chronic growth inhibitory effect on cell multiplication and tumor promotion in rat hepatocarcinogenesis.

Animals↗
PubMed1994

Application to cows and horses of Spotchem, a dry-chemistry blood analyzer for use in veterinary clinics.

The usefulness of a dry-chemistry blood analyzer, Spotchem SP-4410 (SP-4410) in a veterinary clinic for analysis of bovine and equine blood chemistry was studied. We quantitated total protein (TP), albumin (Alb), total bilirubin (T-Bil), blood urea nitrogen (BUN), total cholesterol (T-Cho), glucose (Glu), calcium (Ca), aspartate aminotransferase (AST), gamma-glutamyltransferase (GGT), creatinine phosphokinase (CPK), and alkaline phosphatase (ALP) in bovine sera. Each sample was assayed with both the SP-4410 and an automated blood analyzer which served as a wet-chemistry reference system, and the data were analyzed with regression analysis. The correlation coefficient for AST was 0.997 being the highest for all the parameters, and all the correlation coefficients were 0.93 or higher. The coefficients of variation were lower than 5.0 except in the case of bovine T-Bil where it was 5,756. The ranges of normal reference values measured by SP-4410 were the same as those reported by other investigators in most cases, but those for GGT and CPK were slightly higher. The strongest interference was observed with hemoglobin. It seems that dry-chemical-analysis of blood serum using the SP-4410 is useful for analysis of bovine and equine blood.

Animals↗
PubMed1994

Development of Babesia ovata in the salivary glands of the nymphal tick, Haemaphysalis longicornis.

The development of Babesia ovata in the salivary glands of nymphal Haemaphysalis longicornis ticks was morphologically studied for 4 days of feeding of tick on rabbits. Babesia ovata showed two forms (sporont and sporozoite) in the budding process. Sporozoites were formed in the acinar cells of salivary glands and released from the hollow cytoplasmic area of these cells by day 4 of feeding.

Animals↗
PubMed1994

Management of acute leukemia during pregnancy: from the results of a nationwide questionnaire survey and literature survey.

In March, 1993, a questionnaire was sent to 362 gynecological and obstetric offices of national, prefectural and municipal hospitals and private university hospitals with 250 beds or more. Answers were collected from 260 institutions. Thus, this study analyzed 39 patients with acute leukemia during pregnancy collected by the questionnaires survey and 64 cases reported in the Japanese literatures during 1975-1993 (total 103 patients). The weeks of pregnancy were defined as the 1st (< 15th week), 2nd (16th-27th week), and 3rd (> 28th week) trimesters. The time of diagnosis of leukemia during pregnancy changed from 25% in the 2nd trimester and 62% in the 3rd trimester during 1975-1984 to 39% and 48% after 1985, respectively. After 1985, the remission rate was 72% in the questionnaire group and 75% in the group from literatures. There was no statistical difference. The 50% survival period was 12 months in the group during 1975-1984, but 25 months in the group after 1985. The survival was significantly longer in the patients whose induction therapy was started before delivery than in those treated after delivery. The results suggest that the treatment for acute leukemia during pregnancy should be initiated as soon as possible after the diagnosis of leukemia, with carefully selected regimens. It is important that the time of delivery should be selected considering the maternal and fetal conditions after consultation with an obstetrician.

Adult↗
PubMed1994

In vivo effects of the Ca2+ entry blocker nilvadipine on brain surface microvessels in rats.

The effects of the Ca2+ entry blocker nilvadipine on the diameter of the brain surface microvessels of rats were studied in vivo using intravital fluorescence microscopy and a closed cranial window technique under an intracranial pressure of 5-7 mmHg. Intravenous Na(+)-fluorescein was used as a blood-brain barrier (BBB) and vessel marker. The BBB function, as determined by the barrier marker, remained intact during the entire observation period. Nilvadipine (10(-10)-10(-6)M) and/or vehicle were dissolved in artificial cerebrospinal fluid (CSF). Superfusion of the brain surface with artificial CSF with and without vehicle had no effect on vessel diameters. Nilvadipine dilated pial arterioles in a dose-dependent manner. The arterioles were dilated significantly at concentrations of > or = 10(-9)M when compared with resting diameters. The diameters of venules were not affected by nilvadipine. The results suggest a possible mechanism for the nilvadipine-induced increase in the cerebral blood flow under physiological conditions.

Animals↗
PubMed1994

Molecular mechanism of light-adaptation in retinal photoreceptors.

Vertebrate retinal photoreceptors respond to light by membrane hyperpolarization. The generation mechanism of the photoresponse, namely the phototransduction mechanism is now well characterized. Photoreceptors not only detected light, but also actively adapt to environmental light. Recent biochemical and electrophysiological studies uncovered the mechanism of light-adaptation. In this mechanism, light-induced decrease in the cytoplasmic [Ca2+] plays a major role: The [Ca2+] decrease induces the desensitization of the cell and the acceleration of the time course of the photoresponse. These effects are mediated by Ca(2+)-binding proteins named S-modulin and GCAP.

Adaptation, Ocular↗
PubMed1994

Dual staining methods for carbohydrates using lectin-gold silver techniques.

Three dual staining methods were established for the histochemical detection of saccharide residues and acidic groupings of carbohydrates in light microscopy. The first method consisted of combined lectin-gold silver (LT-G-S) and alcian blue (AB) pH 1.0 techniques, whereas the second staining technique was composed of LT-G-S and AB pH 2.5 procedures. These two techniques were found to color saccharide residues and acidic groupings of carbohydrates in black and blue shades respectively, which exhibited a high contrast between the both. The third methods, LT1-G-S-LT2-PO-DAB techniques, yielded reaction products of blackish and yellowish brown shades, which represented the localizations of two different saccharide residues in one and the same section. According to the results of the experimental and control procedures, the present three dual staining methods are believed to be reliable, reproducible and unusually useful for light microscopic histochemical studies on acidic and non-acidic carbohydrates.

Animals↗
PubMed1994

[Combination therapy of high energy under water shock waves and anticancer drugs for subcutaneous murine bladder cancer (MBT-2)].

The effect in combination therapy of high energy under water shock waves (HESW) and anticancer drugs for subcutaneous murine bladder cancer (MBT-2) in C3H/He mice was examined. HESW were generated by piezoceramics and directed to the subcutaneous tumor under ultrasonographic guidance. The subcutaneous tumor was exposed to HESW alone (100 MPa, 1000 shots, 3 shots/sec) or in combination with pirarubicin (THP, 5 mg/kg, i.p.) or carboplatin (CBDCA, 40 mg/kg, i.p.). Remarkable bleeding in the tumor was seen immediately after the exposure of HESW, destroyed cancer cells appeared after one day and wider and clearly bordered tumor necrosis was observed after three days. In the HESW alone therapy, tumor growth of smaller tumors (< 10 mm3, n = 8) were suppressed more than that of larger tumors (10-35 mm3, n = 11). Tumor growth ratio on the 14th day (TGR 14) (tumor volume on the 14th day/tumor volume on the 1st day) was examined in larger tumors. TGR 14 were 152.2 +/- 146.6 (mean +/- S.D.) in the control (n = 20), 116.3 +/- 98.9 in HESW alone (n = 11), 75.5 +/- 110.7 in THP alone (n = 8), 90.7 +/- 61.6 in CBDCA alone (n = 6), 75.8 +/- 72.2 in THP + HESW (n = 9), 3.2 +/- 4.5 in CBDCA + HESW (n = 8) and 0.8 +/- 1.3 in CBDCA + HESW 2 cycles (n = 9). Evident suppression on tumor growth was more often seen in CBDCA + HESW and CBDCA + HESW 2 cycles therapies than in the other therapies (p < 0.01). The cumulative survival rates were higher in CBDCA + HESW and CBDCA + HESW 2 cycles therapies than in the other therapies (p < 0.05). Tumor metastasis was seen only in the lungs of the dead mice after 19 days. Lung metastases were seen in 1/6 in the control, 0/5 in HESW alone, 1/5 in CBDCA alone, 0/6 in CBDCA + HESW and 1/5 in CBDCA + HESW 2 cycles therapy, respectively.

Animals↗
PubMed1994

[A case of adrenal lipoma].

Lipoma of the adrenal gland is extremely rare. This condition was first described in 1988 and only seven cases have been reported to date. We have experienced a case of adrenal lipoma which was thought to be adrenal myelolipoma on computed tomography (CT). A 56-year-old man was admitted to our department with a complaint of left abdominal pain. Sonography revealed a hyperechoic mass above the left kidney, and a CT scan revealed the mass to be comprised sharply marginated and an inhomogeneous structure. The tumor was comprised of areas of different density including a fatty tissue portion. These findings were strongly suggestive of adrenal myelolipoma or liposarcoma, and a left adrenalectomy was performed. Macroscopically, the tumor was consisted of yellow fatty mass and necrotic areas, which were surrounded by thin fibrous capsule. The adrenal gland was compressed at the bottom of the tumor. The weight of tumor was 290 g. Microscopically, the tumor consisted of large fat cells in direct contact with adrenal cortical cells, and it was then diagnosed adrenal lipoma. Postoperatively, the patient no longer experienced left abdominal pain and there has been no recurrence in the 31 months since the operation.

Adrenal Gland Neoplasms↗
PubMed1994

[Trans-urethral whole layer core biopsy of invasive bladder tumor].

We have developed a percutaneous whole layer core biopsy (WLCB) of bladder tumor and applied it successfully to stage invasive bladder tumor since April, 1985. We report here a modified method, trans-urethral WLCB (TU-WLCB) and present its clinical results. The patient was placed in the lithotomy position under caudal anesthesia, and a 20 F rigid nephroscope was introduced transurethrally. A newly developed 18-gauge (1.2 mm), 350 mm-long biopsy needle (Crown Core Cut Biopsy Needle) was advanced to the tumor through the nephroscope. A longitudinal transabdominal US was used to measure the distance between the needle tip and the outer layer of the bladder tumor. Because the needle advances 2.5 cm when fired by spring-loaded BIP Biopsy Gun (BIP, Germany), biopsy is performed by advancing the needle tip until the outer layer of tumor is slightly pierced under US guidance. Specimens of all 11 trans-urethral WLCB cases included the muscle layer and adipose tissue, and pathological staging were possible. TU-WLCB could be applied safely to tumors located at posterior wall and covered with the peritoneum. Serious complications were not observed so far. Thus, TU-WLCB may become a reliable technique to stage and evaluate neoadjuvant therapy for invasive bladder cancer.

Adult↗
PubMed1994

Phenotypic characteristics of bone marrow cells in patients with rheumatoid arthritis.

OBJECTIVE: Our previous study showed the presence of abnormal myeloid lineage cells in the epiphyseal bone marrow adjacent to joints affected with severe rheumatoid arthritis (RA). Now, we investigated whether there were any changes of other marrow cell populations related to RA, and whether there were any pathologically characteristic changes in the iliac bone marrow, which is one of the major systemic hematopoietic organs. METHODS: 2-Color flow cytometry was carried out to analyze the phenotypes of mononuclear cells (MNC) fractions in bone marrow aspirates and venous blood from 56 patients with RA and 7 non-RA controls. RESULTS: The absolute number of MNC in the iliac bone marrow was increased by 3-fold in the RA patients compared with the non-RA controls. In contrast, no significant increase of MNC was observed in the tibial epiphyseal bone marrow or peripheral blood. The ratio of each MNC fraction in the iliac bone marrow did not differ significantly between the RA patients and the non-RA controls. In lymphocyte subsets, the percentage of HLA-DR+CD8+ cells to all CD8 cells in the iliac bone marrow increased significantly in the RA patients compared with the non-RA controls. Abnormal myeloid cells (MX-GA+MY4+ cells), specific to severe RA, were found to be more concentrated in the iliac bone marrow than in the tibial epiphyseal bone marrow. CONCLUSION: Characteristic pathologic changes of the iliac bone marrow suggest an important role of systemic bone marrow in the progression of RA.

Adult↗
PubMed1994

Failure of normobaric oxygen therapy to reduce ischemic brain damage in rats.

We investigated the effects of 24-h oxygen therapy on focal cerebral ischemia in rats. Under halothane anesthesia, a 3-0 nylon thread was introduced into the neck internal carotid artery to occlude the left middle cerebral artery (MCA). Under atmospheric pressure, group 1 animals inhaled standard air; group 2, 40% O2; group 3, 60% O2; and group 4, 100% O2. Neuropathologic outcomes were quantified after a 24-h inhalation period. Infarct volumes tended to decrease in groups 2-4, but the decreases were not significant when compared with group 1. Hemispheric volume differences of groups 2-4 (27 +/- 18 mm3, 22 +/- 17 mm3, and 31 +/- 22 mm3, respectively) were less than that of group 1 (61 +/- 23 mm3, P < 0.05). Our results demonstrate that O2 therapy reduces brain swelling in rats 24 h after MCA occlusion. However, a dose-dependent decrease in brain swelling was not observed. In addition, we failed to see a significant decrease in the infarct size.

Animals↗