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Biomedical subjects

S Kawano

Publications and source records attributed to S Kawano.

At least 343 records · Page 19Linked to original sources
PubMed1991

Photothermal, cryogenic, and diathermic effects of retinal adhesive force in vivo.

Argon laser photocoagulation, cryoretinopexy, and diathermy of moderate intensity is applied to 140 rabbit eyes. Retinal adhesive force is measured from 1 day to 6 months following the treatment, using the authors' new in vivo method. A small retinal detachment is induced within the area surrounded by the burns. At the moment when the detachment starts to expand beyond the burns, subretinal pressure is measured using a resistance servo-nulling method. Retinal adhesive force is then calculated according to Laplace's law and compared with that of untreated eyes. Both photocoagulation and diathermy enhanced adhesiveness within 24 hours to 128% and 122%, respectively, of normal levels. Cryoretinopexy reduced the retinal adhesiveness during the first week, but afterwards generated as much adhesiveness as the other two methods. Beyond 6 months, under the conditions described here by the authors, the adhesive force was stronger after diathermy (279%) than after cryoretinopexy (214%) or laser photocoagulation (220%).

Animals↗
PubMed1991

Collagen metabolism in cutis laxa fibroblasts: increased collagenase gene expression associated with unaltered expression of type I and type III collagen.

Collagen metabolism was studied in cutis laxa by analyzing collagen and collagenase gene expression in three dermal fibroblast strains from patients with congenital cutis laxa and comparing them with fibroblasts obtained from age-matched healthy subjects. Normal collagen synthetic activity was observed in the cutis laxa fibroblasts. An increased level of collagenase mRNA and unaltered levels of alpha 1(I) and alpha 1(III) collagen mRNA were found in all cutis laxa cell strains by dot blot hybridization. Reduced levels of elastin mRNA were also detected in these strains. However, no qualitative differences in these mRNA transcripts were detected between the control and cutis laxa fibroblasts by Northern blot analysis. Collagenase activity in fibroblast culture supernatants was then measured using fluorescein isothiocyanate (FITC)-labeled type I collagen. Increased collagenolytic activity in cutis laxa fibroblast culture supernatants was also found. These data suggest that increased collagenase expression of fibroblasts is related to the structural abnormality of dermal connective tissue in cutis laxa.

Collagen↗
PubMed1991

[Protective effect of rebamipide (OPC-12759) on the gastric mucosa in rats and humans].

The protective effect of rebamipide against 0.15 N HCl solution containing 40% ethanol (HCl-ethanol)-induced mucosal lesion in the stomach was evaluated in rats and humans. In rat experiments: (1) rebamipide prevented development of mucosal damage induced by HCl-ethanol in a dose-dependent manner when tested at 10, 30, 100 and 300 mg/kg, i.p., and the prevention at 30-300 mg/kg was significant (P less than 0.05); (2) rebamipide significantly (P less than 0.05) increased mucosal blood flow by continuous i.v. dosing at 10 mg/kg/hr by the hydrogen gas clearance method; (3) rebamipide at 10 mg/kg, i.v., also significantly (P less than 0.05) inhibited reduction in gastric mucosal blood volume and tended to suppress oxygen saturation of hemoglobin following hemorrhagic shock by organ reflectance spectrophotometry. A double-blind crossover study was conducted to compare the gastric protective effect of rebamipide with an inactive placebo using 6 healthy male volunteers. Rebamipide was administered to them at a clinical dose of 300 mg/day orally for 7 days, and then HCl-ethanol was given once to induce mucosal damage. Rebamipide significantly (P less than 0.05) inhibited formation of mucosal lesion, decrease in the number of mucous granules and dilatation of intercellular space. These clinical findings indicate that rebamipide was protective against HCl-ethanol-induced gastric lesion at a clinical dose, and the mechanism of this gastric effect was considered to involve, in part, the improvement of mucosal microcirculation.

Adult↗
PubMed1991

Age-related change in human gastric mucosal energy metabolism.

Many investigators have reported a decrease in mucosal blood flow resulting in impairment of gastric mucosal energy metabolism in animal experiments. Recently, endoscopic studies using reflectance spectrophotometry and laser Doppler flowmetry have indicated that gastric mucosal blood flow in humans decreases with age. However, changes in energy metabolism in human gastric mucosa with age remains obscure. In this study, we measured adenine nucleotides in biopsy samples from human gastric mucosa, using high-performance liquid chromatography, and investigated changes in energy metabolism with age in subjects proven normal endoscopically. Energy charge (EC = (ATP + 1/2 ADP)/ATP + ADP + AMP) in the gastric antral and body mucosa showed decrease with age. When the subjects were divided into two groups, less than and more than 65 years old, the EC level was significantly lower in the latter than the former in both antral and body mucosa (0.65 +/- 0.06 versus 0.74 +/- 0.03 in the antrum, 0.73 +/- 0.04 versus 0.79 +/- 0.04 in the body) and significantly less in the antral mucosa than in body mucosa in both groups. The adenosine triphosphate (ATP) level in the older group showed a significant decrease (6.48 +/- 1.14 versus 9.63 +/- 1.92 in the antrum, 8.59 +/- 1.64 versus 10.60 +/- 2.13 in the body) compared with those less than 65 years old. In the antral mucosa of the older group the adenosine diphosphate (ADP) level was also significantly lower than that in the group less than 65. In conclusion, in the elderly, the energy metabolism in human gastric mucosa is impaired, and this may weaken their defensive mechanism.

Adenine Nucleotides↗
PubMed1991

[Evaluation of usefulness of Tc-99m-GSA liver scintigraphy in chronic liver diseases].

Liver scintigraphy was performed using a newly developed radiopharmaceutical, Tc-99m-DTPA-Galactosyl-Human-Serum-Albumin (Tc-99m-GSA), which binds specifically to the receptors on the hepatic cell surface, in 15 patients with chronic liver diseases. The scintigraphy was evaluated qualitatively and quantitatively, and the results were compared with those obtained from the Tc-99m-PMT or Tc-99m-sn-phytate scintigraphy, and the liver function tests. The Tc-99m-GSA scintigraphy showed clear liver images in chronic hepatitis. However, in liver cirrhosis, the liver images was not clear and the cardiac images still existed 40 minutes after administration of Tc-99m-GSA, suggesting that the image quality of the Tc-99m-GSA scintigrams may be inferior to that of Tc-99m-sn-phytate or Tc-99m-PMT in some cases of severe liver dysfunction. The time-activity curves of the heart and liver were analyzed by non-linear regression analysis. The clearance rate from plasma (Kd) were obtained from the time-activity curve of the heart, and the hepatic uptake rate (Ku), hepatic excretion rate (Ke) and peak time of hepatic uptake-excretion curve (PT) were obtained from the time-activity curve of the liver. Kd, Ku and PT values were more significantly decreased or prolonged in the patients with liver cirrhosis than those in the patients with chronic hepatitis. Kd, Ku and PT values had positive correlations with the result of the serum liver function tests, ICG-R15 and ICG-K. Ku and PT values had also correlations with the histological degrees of hepatic fibrosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Lamellar scleral resection enhances subretinal fluid absorption in eyes with choroidal congestion.

The effects of choroidal congestion and lamellar scleral resection on the absorption of subretinal fluid were studied in rabbit eyes. Small retinal detachments were induced and choroidal congestion was produced by ligating two vortex veins. Absorption time was prolonged in these eyes to roughly 138% of that in the control eyes. The choroidal congestion could be alleviated by partial thickness scleral resection, after which the absorption time was only 115% of that in untreated eyes. Our data suggest that lamellar scleral resection relieves elevated choroidal tissue pressure and helps to absorb the subretinal fluid.

Absorption↗
PubMed1991

Role of blood ethanol on gastric mucosal injury and gastric hemodynamics.

The present series of studies were performed to test the hypothesis that ethanol in the blood may play a role in the pathogenesis of gastric mucosal injury. Another hypothesis to be examined was that endothelin may be involved in ethanol-induced gastric mucosal injury. Elevated levels of blood ethanol induced by intraperitoneal infusion of ethanol increased vulnerability of the stomach to hydrochloric acid in a dose-dependent manner in rats. This may be due to impaired gastric mucosal hemodynamics and oxygenation as demonstrated by the results obtained by organ reflectance spectrophotometry (decreases in indices of mucosal hemoglobin contents and hemoglobin oxygen saturation). Ethanol infusion caused a dose-dependent increase in gastric vascular resistance in perfused rabbit stomach, which was accompanied by an increased production of endothelin-1. The results suggest that endothelin may be involved in the pathogenesis of ethanol-induced gastric mucosal injury.

Animals↗
PubMed1991

A clinical study of acute gastrointestinal hemorrhage associated with various shock states.

Gastrointestinal hemorrhage from stress ulceration is a life-threatening complication in a critically ill patient. We retrospectively studied 471 patients admitted to the Department of Traumatology of our hospital who developed shock in their clinical course. Forty-two patients (8.9%) developed gastrointestinal hemorrhage, most within 1 wk (76.2%). The hemorrhage lesion usually was located in the corpus of the stomach. The mortality rate of the shock patients with gastrointestinal hemorrhage was 33.3% (14 of 42). Comparison of different types of shock showed that the incidence, severity, and mortality rates of gastrointestinal hemorrhage were significantly higher in septic shock patients than in hemorrhagic shock patients. These findings show the importance of preventive therapy against progression of early mucosal damage and development of gastrointestinal hemorrhage in shock patients, especially those with sepsis.

Acute Disease↗
PubMed1991

[Intracellular calcium level, lipid peroxidation, and development of gastric mucosal injury in rat hemorrhagic shock].

Although acute gastric mucosal lesions (AGMLs) develop after the mucosal ischemia and reperfusion, precise intracellular mechanism for the development of AGMLs remains unclear. In the present paper, we investigated intracellular calcium level, lipid peroxidation, and gastric mucosal lesion in rat hemorrhagic shock model. We estimated intracellular calcium by measuring phosphorylase a activity in the gastric mucosa. The mucosal phosphorylase a increased during hemorrhagic shock, while it returned to be normal after the reinfusion of shed blood. Although mucosal lipid peroxide and area of AGMLs did not increase significantly during hemorrhagic shock, they increased significantly after the reinfusion. Diltiazem, a calcium antagonist, prohibited both of the increase in mucosal phosphorylase a activity during hemorrhagic shock and the increase in lipid peroxide content and area of AGMLs after the reinfusion of the shed blood. Organ reflectance spectrophotometry revealed that the gastric corpus suffered mucosal ischemia and hypoxia during the hemorrhagic shock. The are of AGMLs had a good correlation with a level of lipid peroxidation in the gastric mucosa. These results suggest 1) that intracellular free calcium in gastric mucosa increases during the mucosal ischemia; 2) that a calcium antagonist prohibits the increased intracellular free calcium during mucosal ischemia; and 3) that a calcium antagonist prohibits the increased mucosal lipid peroxide and the development of AGMLs after the mucosal reperfusion. Thus it is concluded that the increased intracellular free calcium during ischemia plays a key role in the mucosal tissue injury in the ischemia-reperfusion state.

Animals↗
PubMed1990

Effect of ethanol on hepatic oxygenation: evidence of hepatic hypoxia.

The effects of low (1 g/kg body wt) and high doses (4 g/kg body wt) of ethanol on hepatic oxygenation in rats was investigated employing an in vivo microscopic and spectrophotometric system and also a micro oxygen electrode. The low dose of ethanol increased sinusoidal blood hemoglobin oxygenation (ISO2) at periportal regions in the liver lobule. The high dose of ethanol increased ISO2 at periportal regions, but decreased ISO2 at pericentral regions. The low dose of ethanol increased hepatic surface tissue PO2, but the high dose decreased this PO2. From these data it is concluded that the increase of hepatic blood flow, after administration of a low dose of ethanol, compensated for the increase of oxygen demand in hepatocytes but that administration of a high dose of ethanol reduced hepatic tissue oxygenation via an imbalance between delivery and demand of oxygen in pericentral regions of the liver lobule, resulting in local hypoxia in surface hepatic tissue.

Animals↗
PubMed1990

Analysis of the T-type calcium channel in embryonic chick ventricular myocytes.

T-type calcium channels (IT channels) were studied in cell-attached patch electrode recordings from the ventricular cell membrane of 14-day embryonic chick heart. All experiments were performed in the absence of Ca2+ with Na+ (120 mM) as the charge carrier. IT channels were distinguished from L-type calcium channels (IL) by their more negative activation and inactivation potential ranges; their smaller unitary slope conductance (26 pS), and their insensitivity to isoproterenol or D600. Inactivation kinetics were voltage dependent. The time constant of inactivation was 37 msec when the membrane potential was depolarized 40 mV from rest (R + 40 mV), and 20 msec at R + 60 mV. The frequency histogram of channel open times (tau o) was fit by a single-exponential curve while that of closed times (tau c) was bi-exponential. tau o was the same at R + 40 mV and R + 60 mV whereas tau c was shortened at R + 60 mV. The open-state probability (P o) increased with depolarization: 0.35 at R + 40 mV, 0.8 at R + 60 mV and 0.88 at R + 80 mV. This increase in Po at depolarized potentials could be accounted for by the decrease in tau c.

Animals↗
PubMed1990

Early and delayed imaging with 123I-IMP SPECT in patients with ischemic cerebrovascular disease.

Cerebral blood flow imaging with N-isopropyl (I-123) p-iodoamphetamine (IMP) was performed in 44 patients with ischemic cerebrovascular disease (CVD) at an acute or subacute stage less than 30 days from the onset. IMP imaging was obtained at 20 minutes (early scan) and 4 hours (delayed scan) after intravenous injection of 222 MBq of IMP. The region of interest (ROI) was selected in a slice compatible with the findings on the CT images, and the lesion to tissue ratio (L/T ratio) was calculated in a comparison with the unaffected side. The redistribution index (RI) was also calculated by dividing the difference between the L/T ratio in early and delayed image by the L/T ratio in the early image. The patients were classified into three groups (Grade 1, 2, 3) on the basis of the CT findings. The L/T ratio in the delayed images and RI was high in grade 1 and 2 groups and low in grade 3 groups both in early and delayed scans. The RI had tendency to grow high as the days after the onset became later. In the duration period from 4 to 7 days, 'reversed' redistribution was observed in 4 cases. Follow up examinations were performed in 6 cases in grade 3 group. The RI became higher in 3 cases and lower in 3 cases in the second examination. In conclusion, good redistribution was observed in grade 1 and 2 groups, and the prognosis was good. On the other hand, poor redistribution was observed in grade 3 group.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Sequential protooncogene expression during regeneration in rat stomach.

Cellular protooncogenes such as c-myc and c-Ha-ras may play important roles in the control of regeneration of the stomach. In this study, in situ hybridization histochemistry and immunohistochemistry were used to determine how these protooncogenes and the corresponding oncoproteins are expressed at the cellular level during gastric regeneration after mucosal injuries caused by indomethacin. In addition, cells in the S-phase were immunohistochemically detected by means of 5-bromo-2'-deoxyuridine incorporation. Expression of the c-myc gene was localized to nuclei and reached a maximum at 3 h, and that of the c-Ha-ras gene was localized to cytoplasm with a peak at 6-12 h after treatment on the mucous neck, parietal, chief, and enterochromaffinlike cells around the lesions. The distribution of cells in the S-phase roughly coincided with that of cells in which expression of the protooncogenes was detected. In conclusion, various types of gastric mucosal cells participated in the sequential regulated expression of cellular protooncogenes during regeneration of the rat stomach.

Animals↗
PubMed1990

An ecological study on air pollution: changes in annual ring growth of the Japanese cedar and prevalence of respiratory symptoms in schoolchildren in Japanese rural districts.

The effect of air pollution caused by oil-fired electricity-generating stations on the annual ring growth of the Japanese cedar (Cryptomeria japonica, D. Don) and prevalence of respiratory symptoms in schoolchildren were investigated. By retrospective analysis the annual ring growth has been demonstrated to show good agreement with the general trend in air pollution. In addition it was found to be related to the prevalence of respiratory symptoms. The reduction in annual ring growth and increase in the prevalence of respiratory symptoms followed a deterioration in air pollution. Following upgrading of the power station and an improvement in air pollution, the annual ring growth and prevalence of respiratory symptoms showed opposite changes, respectively. Concerning the latter, the prevalence of wheezing and respiratory symptoms associated with school absence in schoolchildren with a positive skin test to house dust extract showed a closer correlation with the annual ring growth when compared with those who had never had a positive skin test.

Adolescent↗
PubMed1990

Mucosal blood flow stasis and hypoxemia as the pathogenesis of acute gastric mucosal injury: role of endogenous leukotrienes and prostaglandins.

To clarify the roles of endogenous leukotrienes and prostaglandins in the ethanol-induced gastric mucosal injury, the effect of AA-861 (a selective 5-lipoxygenase inhibitor) and indomethacin (a cyclooxygenase inhibitor) on the ethanol-induced gastric mucosal lesions was investigated in fasted rats. Furthermore, the effect of these agents on the gastric mucosal microcirculatory disturbance induced by ethanol was also investigated using laser Doppler velocimetry and reflectance spectrophotometry. Forty percent ethanol caused mucosal microcirculatory stasis and mucosal hypoxemia, followed by mucosal injury. The pretreatment with AA-861 reduced the mucosal injury and significantly reduced the mucosal congestion and hypoxia induced by 40% ethanol. The pretreatment with indomethacin did not reduce the gastric mucosal damage or influence the mucosal blood flow stasis and the mucosal hypoxemia induced by ethanol. These results suggested that the increase of endogenous leukotrienes after intragastric administration of ethanol is responsible for the mucosal microcirculatory disturbance and mucosal tissue hypoxemia resulting in the mucosal injury, and that the decrease of prostaglandins alone may not play an important role in ethanol-induced mucosal injury.

Animals↗
PubMed1990

Protective effect of PGD2 against ethanol-induced gastric mucosal injury in rats.

The protective effect of prostaglandin D2 (PGD2) in ethanol-, HCl-, or NaCl-induced gastric mucosal injury was investigated. To clarify the mechanism, the gastric mucosal hemodynamics were also investigated using reflectance spectrophotometry and laser Doppler flowmetry in anesthetized rats. PGD2 administered orally significantly reduced the ethanol-induced mucosal injury. Although it did not reach any significance, PGD2 also reduced 0.6 N HCl-induced mucosal damage, and slightly reduced 25% NaCl-induced mucosal damage. Topical application of PGD2 did not affect gastric mucosal hemodynamics at steady state before the administration of necrotizing agent. However, PGD2 significantly improved the gastric mucosal microcirculatory congestion caused by ethanol, and partly improved 0.6 N HCl-induced ischemia. However, it did not improve the 25% NaCl-induced mucosal congestion. The results indicated that PGD2 had a protective effect in the ethanol-induced gastric mucosal injury through the improvement of gastric mucosal microcirculation. However, further investigations are needed to clarify the precise effect of PGD2 in 0.6 N HCl- or 25% NaCl-induced mucosal damage.

Animals↗
PubMed1990

Electrophysiologic and antiarrhythmic actions of pirmenol on rabbit and guinea pig cardiac preparations.

The electrophysiological and antiarrhythmic effects of pirmenol HCl were examined using the microelectrode technique applied to multicellular preparations and the suction-pipette whole-cell clamp method applied to ventricular myocytes from rabbit and guinea pig hearts. Pirmenol at 5 microM and higher doses suppressed the sinus node automaticity by depressing the slow diastolic depolarization without changing the maximum diastolic potential. Pirmenol at 1 microM and higher doses depressed the maximum upstroke velocity (Vmax) of action potentials and prolonged the action potential duration at 90% repolarization in atrial muscles and Purkinje fibers without affecting resting membrane potentials. Pirmenol at 5 microM depressed the early part of the plateau and lengthened the final repolarization of the action potentials in ventricular myocytes, of which effects were attributed to the depression of the calcium current and the delayed outward K+ current. Triggered tachyarrhythmias arising from delayed afterdepolarizations in papillary muscles and ventricular myocytes were markedly inhibited by 1-5 microM pirmenol. The drug changed the amplitude and appearance of the transient inward current in ventricular myocytes. These results suggest that pirmenol has electrophysiologic properties that could provide an antiarrhythmic action on various types of arrhythmias.

Action Potentials↗