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Biomedical subjects

J Kambayashi

Publications and source records attributed to J Kambayashi.

At least 91 records · Page 5Linked to original sources
PubMed1994

Involvement of calpain in myonephropathic metabolic syndrome (MNMS).

Myonephropathic metabolic syndrome (MNMS) is a serious muscle reperfusion injury associated with acute renal failure. The exact pathogenesis of MNMS has not been fully elucidated, nor effective treatment, through the renal failure is thought to be a consequence of rhabdomyolysis. In the present study, the possible involvement of calpain in the lysis was investigated in a MNMS animal model employing a cell permeable calpain antagonist calpeptin. Male rabbits were subjected to bilateral hind leg ischaemia for 5 hours by clamping the distal aorta, followed by reperfusion for 3 hours. Blood pressure, plasma N-acethyl-beta-D-glucosaminidase (NAG) and the presence of myoglobinuria were serially determined. Blood pressure remained constant during the ischemic period but dropped by about 25% immediately after reperfusion. This was significantly attenuated by intraaortic administration of calpeptin. NAG gradually increased during ischemia and during reperfusion and this was also significantly reduced by calpeptin. Myoglobinuria appeared immediately after reperfusion, and was also attenuated by calpeptin. Calpeptin prevented lytic and degenerative changes of the hind leg muscles, determined by light and electron microscopy. Thus it is concluded that activation of calpain in skeletal muscle is an important etiologic factor of MNMS and that the occurrence of MNMS may be prevented by administration of a calpain antagonist.

Acetylglucosaminidase↗
PubMed1994

Appraisal of the use of an externally supported polytetrafluoroethylene graft in left gastric vein to inferior vena cava shunting.

OBJECTIVE: To assess the results of left gastric vein to inferior vena cava (IVC) shunts with externally supported (ringed) polytetrafluoroethylene (PTFE) grafts in six patients with considerably dilated left gastric veins who required portal decompression. DESIGN: Open study. SETTING: University hospital, Japan. SUBJECTS: Six patients with advanced portal hypertension and massive oesophageal bleeding. INTERVENTIONS: The PTFE graft was first anastomosed end to side to the IVC, and then end to end (n = 4) or end to side (n = 2) to the left gastric vein. MAIN OUTCOME MEASURES: Short term and long term morbidity and mortality. RESULTS: There were no operative mortality or morbidity. Endoscopic examination postoperatively showed gradual, steady improvement in the oesophageal varices, and the hyperaemic appearance of the mucosa had disappeared within 10 months in all cases. Median follow up was 19 months (range 10-70); one patients rebled after occlusion of the graft at 12 months, one died of hepatocellular carcinoma at 16 months, and the remaining four patients are well with patent grafts at 10, 22, 40, and 70 months, respectively. CONCLUSIONS: These results confirm the effectiveness of externally supported PTFE grafts in left gastric vein to IVC shunts, and remove the technical restraints that have prevented surgeons from recommending the operation in the past.

Blood Vessel Prosthesis↗
PubMed1994

[A multi-institutional study for prevalence, diagnosis and treatment of deep fungal infection in gastrointestinal surgery].

A multi-institutional study was conducted for prevalence, diagnosis and treatment of deep fungal infection in gastrointestinal surgery. Forty five cases including thirty six complete cases were entered basing on the diagnostic criteria and the mortality of complete cases was 17%. By the administration of miconazole (MCZ), clinical response rate was obtained in 87%, mycological radiation rate in 82% and valuable rate in 71%, with occurrence of side effects in 20%. Fungal endophthalmitis was found in 41% (12/29 cases). beta-glucan [the toxinometer method (T), the Seikagaku-Kogyo method (S)] and candida antigen [the C and-Tec method (C)] were monitored as sero-diagnostic methods, the positive rates for all cases, fungemia, and mycosis of which were 63, 83, 62% (T), 88, 100, 92% (S) and 52, 83, 50% (C), respectively. After mycological re-classification, the positive rates of the T method and endophthalmitis, and the mortality rates were 86, 60, 38% in fungemia, 63, 43, 23% in urinary tract infection, 64, 80, 7% in TPN infection, and 33, 17, 33% in drain infection, respectively. High association of endophthalmitis was found in TPN infection. The beta-glucan assay and a prospective ophthalmoscopic examination are useful for the early diagnosis of deep fungal infection and it is reasonable to treat patients in gastrointestinal surgery by MCZ when mycosis is confirmed or suspected.

Digestive System Surgical Procedures↗
PubMed1993

The effects of calpeptin (a calpain specific inhibitor) on agonist induced microparticle formation from the platelet plasma membrane.

Platelets activated by various agonists produce formation of vesicles shed from the plasma membrane (microparticles). However, the mechanism of microparticle (MP) formation has not been clarified yet. The aim of the present study was to determine the possibility of involvement of calpain (a Ca(2+)-dependent thiol protease) in MP formation. Washed platelets preincubated with calpeptin, a cell permeable calpain specific inhibitor, or with a vehicle were activated by thrombin plus collagen or by calcium ionophore A23187. Flow cytometry was used to detect the amount of microparticle formation by using murine monoclonal antibodies against GP IIb-IIIa or GP IIb and fluorescein 5-isothiocyanate labeled goat anti-mouse IgG. MP formation stimulated either by thrombin plus collagen or by A23187 was inhibited by calpeptin in a dose dependent manner. The microparticle formation from platelets activated by A23187 reached a plateau in approximately 5 min after activation, whereas that from platelets activated by thrombin plus collagen reached a plateau at 30 min following the stimulation. These time sequences corresponded well with those of degradation of actin-binding protein (ABP), a well known substrate of calpain, of platelets activated by these two stimulations. However, the inhibition of MP formation by calpeptin was more marked in the early stage (within 10 min) than in the late stage (after 30 min) of platelet activation. At 30 min after platelet activation by either two stimulations, a significant amount of microparticle formation was observed in the presence of 30 microM calpeptin, which inhibited hydrolysis of ABP almost completely. Our data suggest the involvement of calpain in the early stage (especially within 10 min) of microparticle formation.

Antigens, Human Platelet↗
PubMed1993

Calyculin A inhibits the exposure of fibrinogen receptor in thrombin-stimulated platelets.

Calyculin A (CLA) and okadaic acid (OA), specific and potent inhibitors of protein phosphatase 1/2A, inhibit platelet aggregation. However, their inhibitory mechanisms remain unknown. We investigated the effects of CLA on the exposure of fibrinogen receptor in thrombin-stimulated platelets, using flow cytometry with a monoclonal antibody against the fibrinogen receptor of activated glycoprotein(Gp)IIb/IIIa complex (PAC-1). CLA inhibited the exposure of fibrinogen receptor in a dose related manner when added either before or 3 min after thrombin stimulation. In contrast, CLA had no significant effect when the expression of GpIIb/IIIa complex was examined in resting platelets, using a monoclonal antibody recognizing non-activated GpIIb/IIIa complex (NNKY1-32). These results suggest that protein phosphatase 1/2A may be directly involved in the exposure of platelet fibrinogen receptor.

Adult↗
PubMed1993

Cell-penetrating inhibitors of calpain block both membrane fusion and filamin cleavage in chick embryonic myoblasts.

Benzyloxycarbonyl(Z)-Leu-nLeu-H (calpeptin) and Z-Leu-Met-H, cell-penetrating inhibitors of calpain, were found to block myoblast fusion without any effect on cell proliferation and alignment along their bipolar axis. They also inhibited the accumulation of creatine kinase during myogenesis. These effects were dose-dependent, and could be reversed upon removal of the drug from the culture medium. Furthermore, treatment of the inhibitors prevented the hydrolysis of filamin, which is sensitive to cleavage by calpain in vitro and interferes with actin-myosin filament formation by cross-linking F-actin molecules. On the other hand, leupeptin, which can also inhibit calpain in vitro but can not penetrate into cells, showed little or no effect on both myoblast fusion and filamin clevage. These results suggest that calpain may play an important role in cytoskeletal reorganization that is requisite for myoblast fusion. The role of calpain on the expression of muscle-specific proteins remains unknown.

Animals↗
PubMed1993

The possible involvement of protein phosphatase 1 in thrombin-induced Ca2+ influx of human platelets.

Protein phosphatase 1 is considered to be involved in thrombin-induced platelet activation (Murata et al., Biochem Int 26:327-334, 1992). To clarify the mechanism, we examined the effects of protein phosphatase 1 and 2A inhibitors (calyculin A, tautomycin, okadaic acid) on Ca2+ influx. In the presence of 1 mM Ca2+, thrombin- (0.1 U/ml) induced platelet aggregation and ATP release were inhibited by calyculin A, while this inhibitory effect was abolished in the absence of Ca2+ (EGTA 1 mM). Furthermore, thrombin-induced Mn2+ influx but not intracellular Ca2+ mobilization was inhibited by calyculin A in a dose-related manner. Calyculin A also blocked the ongoing Ca2+ influx when added 3 min after thrombin stimulation. Similar inhibitory effects were observed with okadaic acid and tautomycin in the same potency sequence as the reported one for protein phosphatase 1 (calyculin A > tautomycin > okadaic acid). These results suggest that the anti-platelet effects of phosphatase inhibitors are due to the inhibition of Ca2+ influx and that protein phosphatase 1 plays a key role in the regulation of receptor operated Ca2+ channel of human platelets.

Antifungal Agents↗
PubMed1993

Portal vein calcification: a clinical review of the last 50 years and report of a case associated with dysplasminogenemia.

We report herein a case of a 68-year-old Japanese woman in whom calcification of the portal vein was recognized by plain abdominal X-ray radiograph and computed tomography (CT) scan when she presented with repeated thrombosis of the portal system. Following emergency small bowel resection for intestinal necrosis caused by superior mesenteric vein thrombosis, hematological studies revealed the association of dysplasminogenemia. A review of 21 cases of portal vein calcification reported between 1940 and 1990 revealed the average age to be 53.7 +/- 10.2 years and the male/female ratio 17:4. Although the majority of cases suffered from portal hypertension (81%), only 38% had any evidence of liver cirrhosis, while 52% had normal liver function, being comparable to idiopathic portal hypertension. The calcified lesions were located in the portal vein in 100% of cases, the splenic vein in 62%, the superior mesenteric vein in 33%, and the inferior mesenteric vein in 0%. The precise etiology of the calcification was not elucidated in any of the reviewed cases. The patient reported herein is the first reported case of portal vein calcification due to repeated thrombosis of the portal system caused by dysplasminogenemia, which could be accounted as a cause of idiopathic portal hypertension.

Aged↗
PubMed1993

Stimulation of human platelet Ca(2+)-ATPase and Ca2+ restoration by calpain.

To clarify the possible role of calpain (calcium activated neutral protease; EC 3.4.22.17) in Ca2+ homeostasis of human platelets, we investigated the effects of cell permeable calpain inhibitors, calpeptin and E-64d (EST), on the restoration of cytoplasmic Ca2+ ([Ca2+]i) in both Fura-2 and aspirin (ASA) loaded platelets. Although neither calpeptin (30 microM) nor EST (250 microM) altered the increase of [Ca2+]i in thrombin (1 U/ml) stimulated platelets, both calpain inhibitors delayed the decrease of [Ca2+]i back towards the basal level. These observations suggested that calpain might be involved in Ca2+ restoration. Then, the activity of Ca(2+)-ATPase was examined in thrombin (2 U/ml) stimulated platelets. Thrombin produced a rapid rise in Ca(2+)-ATPase activity by 2-fold at 8 s of incubation, which then returned to below the basal activity within 2 min. Calpeptin inhibited transient Ca(2+)-ATPase activation induced by thrombin in a dose related manner. Ca(2+)-ATPase of isolated platelet membranes was digested by purified human platelet calpain-I and Ca(2+)-ATPase activity was investigated. With a short incubation (8-15 s), Ca(2+)-ATPase activity was increased about 2-fold and then it decreased below the basal level at longer incubations or at a higher calpain/membrane ratio. The initial rate of Ca2+ uptake was also increased by about 2-fold with a short incubation (8-15 s). For molecular characterization of the Ca(2+)-ATPase, the formation of the enzyme-phosphate complex (EP) was investigated. The membrane bound intact 105 kD Ca(2+)-ATPase was converted by calpain to a fragment of approximately 50 kD.(ABSTRACT TRUNCATED AT 250 WORDS)

Aspirin↗
PubMed1993

Purification and characterization of endogenous protein activator of human platelet proteasome.

An endogenous activator of 20S proteasome was purified from human platelets and its effect on three peptidase activities of proteasome was studied. This activator had a molecular weight of 170 kDa, and was composed of 32 kDa polypeptides as determined by SDS-PAGE. It was highly labile upon heat treatment (56 degrees C, 20 s) and proteinase (pronase CB) digestion. Suc-LLVY-MCA degrading activity of the platelet proteasome showed positive cooperativity between two or more catalytic sites because the coefficient was 1.54 when analyzed by use of the Hill plot. The endogenous activator increased Vmax and caused a loss of cooperativity. The plot of reaction velocity as a function of activator concentration yielded a saturation curve, implying the binding of the activator to proteasome. Boc-LTR-MCA degrading activity followed Michaelis-Menten kinetics. The activator enhanced the activity by increasing Vmax and decreasing Km. In contrast, CBz-LLE-2NA degrading activity could not be analyzed according to any kinetic scheme reported so far. The activator stimulated this activity at lower substrate concentrations (below 200 microM), while it inhibited the activity at higher substrate concentrations (400-800 microM). It is concluded from these findings that the endogenous protein activator may regulate the intracellular proteasome activity by functioning as a positive allosteric effector.

Blood Platelets↗
PubMed1993

Translocation of human platelet calpain-I.

Intracellular localization of calpain (calcium dependent cysteine proteinase) was studied in resting or activated human platelets. When stimulated with 2 U/ml thrombin, approximately 40% of total cellular calpain activity and 25% of antigen translocated mainly to the intracellular membrane fractions with autolytic activation. Translocation of calpain was completely abolished by the addition of EDTA to the sonication medium. However an endogenous calpain inhibitor (calpastatin) activity was not detected in the membrane fractions both in resting and in thrombin stimulated platelets. Translocation of calpain was also observed in the platelets stimulated with ionomycin, collagen or phorbor myristate acetate (PMA). These data suggest that cytosolic calpain reversibly translocates to the intracellular membranes during platelet activation without an interference by calpastatin.

Blood Platelets↗
PubMed1993

[Treatment of multiple organ failure].

Since numerous pathogenic factors are known to be involved in the development of disseminated intravascular coagulation (DIC) and multiple organ failure (MOF) in sepsis, the successful management of these clinical states is difficult. To investigate the mechanisms further, we developed experimental sepsis models associated with DIC and MOF, or endotoxin induced renal insufficiency model unaffected by prerenal factors. The hypercoagulable state leading to DIC is considered to be a prerequisite for MOF and inactivation of Xa or suppression of platelet activation is an important step to prevent the occurrence of DIC and MOF.

Alprostadil↗
PubMed1992

Bedside monitoring of warfarin therapy by a whole blood capillary coagulation monitor.

A recently developed portable capillary coagulation monitor device allows rapid determination of prothrombin time (PT) in sec. and in International Normalized Ratio (INR) from a drop of whole blood. Considering a possible application of this device for monitoring of warfarin therapy at bedside or at outpatient clinic, a comparative study was performed in patients receiving warfarin between the whole blood capillary PT(WBC-PT) and conventional laboratory tests such as plasma PT (LAB-PT) and Thrombotest (TTO). There was an excellent positive correlation (r = 0.95, n = 49) between LAB-PT(sec) and WBC-PT(sec). As the correlation coefficient between WBC-PT(sec) and the reciprocal of LAB-PT(%) was excellent (r = 0.95, n = 49), it is feasible to convert WBC-PT(sec) to LAB-PT(%) by the following formula; y = 313.48x +8.29 (x:reciprocal value of LAB-PT(%), y:WBC-PT). As the correlation between WBC-PT(sec) and TTO(sec) was also excellent (r = 0.85, n = 63), TTO(%) may be likewise estimated by the following formula; y = 66.49x + 11.36 (x:reciprocal value of TTO(%), y:WBC-PT). From these observations it is concluded that the determination of WBC-PT is simple and accurate and that the monitoring of warfarin therapy is easily performed by the present method.

Ambulatory Surgical Procedures↗
PubMed1992

Blood compatibility of venous prosthesis made of textile or non-textile material.

To study blood compatibility of venous prosthesis made of textile or non-textile material, the inferior vena cava of 37 rabbits was partly replaced by 3 mm internal diameter synthetic tube graft made of textile material (T: woven tetron) or non-textile material (P: polytetrafluoroethylene). At designated time intervals after the replacement (5 hours to 4 weeks), graft patency was examined and the dry weight of intraluminal deposits was measured. The harvested grafts were then subjected to light and scanning electron microscopy. All the T-grafts were occluded as early as 5 hours after grafting but when ticlopidine was administered prior to the grafting, all the grafts were patent. All the P-grafts were patent up to 4 weeks after grafting, though the amount of intraluminal deposits was increased in a time related manner, narrowing the lumen of the grafts. The luminal surface of the P-grafts harvested at 5 hours after grafting was covered by piles of fibrin networks entrapping erythrocytes without an association of platelet aggregates, which resembles the finding in the T-grafts harvested from the ticlopidine treated rabbits. In the P-grafts, both the proximal and distal luminal surfaces near the anastomosis were fully covered with endothelial cells by 2 weeks and the entire luminal surface was covered with these cells by 4 weeks. From these results, the following conclusions were obtained; (1) P-graft was superior to T-graft for venous prosthesis, which is mainly due to the inertness of P against platelet activation. (2) Though the luminal surface of the P-grafts was completely covered with endothelial cells by 4 weeks after grafting, the lumen was markedly narrowed by intimal hyperplasia.

Animals↗
PubMed1992

Purification and characterization of a calpain activator from human platelets.

A calpain (Ca(2+)-activated neutral protease) activator was purified from human platelets by ammonium sulfate fractionation, gel-filtration, ion-exchange chromatography, followed by heat-treatment. The purified calpain activator with a Mr of 47.5 kDa was a heat-stable protein as demonstrated in other cells. The calpain activator did not change the Ca2+ sensitivity of calpain but activated calpain activity about 2-fold. This calpain activator may play an important role in the activation of the protease system leading to the Ca(2+)-mediated physiological process of platelets.

Biological Factors↗
PubMed1992

Ultrastructural analysis of pseudo-intimal hyperplasia of polytetrafluoroethylene prostheses implanted into the venous and arterial systems.

To evaluate and compare the pathogenesis of pseudo-intimal hyperplasia (PH) of venous and arterial prostheses, a segment of the inferior vena cava (n = 16) or abdominal aorta (n = 16) was substituted by a 3 mm internal diameter polytetrafluoroethylene tube graft (PTFE, 3 cm long, 30 microns in nodal distance) in albino rabbits. At designated time intervals (3-28 days) after the replacement, graft patency was examined and the dry weights of the intraluminal deposits measured as an indicator of the degree of PH. The harvested grafts were then subjected to an ultrastructural analysis by means of light microscopy (LM), and scanning electron and transmission electron microscopy (SEM, TEM). All the grafts remained patent during the entire observation period. The PH judged by the dry weight was significantly more extensive in the venous than in the arterial prostheses. The PH on day 28, observed by light microscopes was apparently most extensive in the mid-portion of venous prostheses but in the arteria prostheses it was mostly seen at the anastomotic sites. The lining of the intraluminal surface of the prostheses with endothelial-like cells observed by SEM was faster and more extensive in venous than in arterial prostheses. The process of PH in venous prostheses observed by TEM may be divided into the following steps: early thrombosis, phagocytosis of the thrombus, appearance of fibroblasts, growth of endothelial-like cells, appearance of smooth muscle cells, and pseudointimal thickening and proliferation of fibroblasts producing collagen fibrils. The process in arterial prostheses was essentially identical to that in venous prostheses but was much slower and less extensive. From these observations, it was concluded that the formation of PH occurs much faster in venous than in arterial prostheses, although the mechanism of PH is mostly identical in venous and arterial prostheses.

Animals↗
PubMed1992

Species differences in platelet aggregation induced by platelet-activating factor (PAF).

Species differences in platelet aggregation induced by platelet-activating factor (PAF) were investigated by using the same procedure of platelet preparation and biological assay. Washed platelets of six different species (horses, dogs, rats, rabbits, sheep and guinea pigs) were prepared employing the same method and platelet aggregation was induced by C16-PAF. Horse platelets were most sensitive to PAF (8.0 x 10(-12) M) and rabbit platelets activated by 5.0 x 10(-11) M PAF were also sensitive enough to detect PAF in clinical samples.

Animals↗