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Biomedical subjects

H Nakamoto

Publications and source records attributed to H Nakamoto.

At least 55 records · Page 3Linked to original sources
PubMed1999

Endothelium-derived nitric oxide enhances the effect of intraaortic balloon pumping on diastolic coronary flow.

BACKGROUND: High shear rate with pulsation is one of the major stimuli for the release of endothelium-derived nitric oxide leading to coronary arteriolar dilation. Intraaortic balloon pumping mechanically enhances shear rate and diastolic-to-systolic flow oscillation. We aimed to evaluate whether or not coronary blood flow augmentation during intraaortic balloon pumping is mediated by coronary arteriolar dilation through endothelium-derived nitric oxide release. METHODS: Using a charge-coupled device intravital videomicroscope, we observed epicardial coronary arterioles (40 to 220 microm in diameter) in anesthetized open-chest dogs (n = 10) during 2:1 mode of intraaortic balloon pumping. Endothelium-derived nitric oxide-mediated vasodilatory effects of intraaortic balloon pumping were evaluated by comparing end-diastolic arteriolar diameters between the coupled beats of on and off intraaortic balloon pumping before and after intracoronary endothelium-derived nitric oxide synthesis inhibition with Nomega-nitro-L-arginine (L-NNA, 2 micromol/min) administration. RESULTS: Intraaortic balloon pumping increased coronary arteriolar diameters and coronary blood flow by 11.4%+/-1.8% (p < 0.0001) and 33.4%+/-4.1% (p < 0.001), respectively. Vasodilation was greater in small arterioles (<110 microm; 15.4%+/-2.2%) than in large arterioles (> or =110 microm; 4.2%+/-1.2%, p < 0.0001). L-NNA attenuated the intraaortic balloon pumping-induced vasodilation and augmentation of coronary blood flow to 4.6%+/-1.0% (p < 0.001) and to 20.8%+/-2.1%, (p < 0.05), respectively. Attenuation of vasodilatory effect by L-NNA was observed mainly in small arterioles (from 15.4%+/-2.2% to 5.9%+/-1.2%). CONCLUSIONS: Intraaortic balloon pumping augmented coronary blood flow by dilating coronary arterioles in diastole, more significantly in small arterioles than in large arterioles. Endothelium-derived nitric oxide inhibition markedly attenuated these effects. We conclude that, in a canine model, endothelium-derived nitric oxide contributes to mechanical enhancement of the coronary blood flow with diastolic arteriolar vasodilation during intraaortic balloon pumping.

Acetylcholine↗
PubMed1999

Thoracoscopic surgery and pleurodesis for pleuroperitoneal communication in patients on continuous ambulatory peritoneal dialysis.

Two patients on continuous ambulatory peritoneal dialysis (CAPD) developed right massive hydrothorax and were diagnosed as having pleuroperitoneal communication. Thoracoscopic surgery and pleurodesis were performed. It showed that one was caused by multiple flaws in the diaphragm and that the other was attributable to multiple blebs in the diaphragmatic dome. After the procedure, both of them had no recurrence of hydrothorax and underwent CAPD safely. We recommend thoracoscopic surgery and pleurodesis as the first choice of therapeutic methods for pleuroperitoneal communication.

Endoscopy↗
PubMed1999

The effect of exercise training on oxidative damage of lipids, proteins, and DNA in rat skeletal muscle: evidence for beneficial outcomes.

Moderate daily exercise is known to be beneficial to health, reducing risks of a number of age-related disorders. Molecular mechanisms that bring about these effects are not clear. In contrast, it has been claimed that some types of prolonged physical exertion are detrimental to health because active oxygen species are generated excessively by enhanced oxygen consumption. Using two age groups of rats, young (4 week) and middle aged (14 months), we investigated the effects of long-term swimming training on the oxidative status of phospholipids, proteins, and DNA. The concentration of thiobarbituric acid reactive substances and 4-hydroxynonenal protein adducts did not differ in the gastrocnemius muscle between exercised and nonexercised animals in the two age groups. The extent of carbonylation in a protein of molecular weight around 29 KDa and the amount of 8-hydroxydeoxyguanosine in nuclear DNA were smaller (p<.05) in the exercised rats than in the sedentary animals. Activities of DT-diaphorase (C1: 29.3+/-1.9; C2: 36.1+/-2.6; E1: 27.2+/-1.3; C2: 33.4+/-2.9 nmol/mg protein) and proteasome, a major proteolytic enzyme for oxidatively modified proteins were significantly higher in the exercised animals of both age groups (p<.05). The adaptive response against oxidative stress induced by moderate endurance exercise constitutes a beneficial effect of exercise.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed1999

Purification and characterization of the 16-kDa heat-shock-responsive protein from the thermophilic cyanobacterium Synechococcus vulcanus, which is an alpha-crystallin-related, small heat shock protein.

A 16-kDa protein, one of the major proteins that accumulates upon heat-shock treatment in the thermophilic cyanobacterium Synechococcus vulcanus, was purified to apparent homogeneity. The N-terminal and internal amino acid sequences of the protein exhibited a homology to the alpha-crystallin-related, small heat shock proteins from other organisms. The protein was designated HspA. Size-exclusion chromatography and nondenaturing gel electrophoresis demonstrated that HspA formed a large homo-oligomer consisting of 24 subunits. It prevented the aggregation of porcine malic dehydrogenase at 45 degrees C and 50 degrees C and citrate synthase at 50 degrees C. The activity of the malic dehydrogenase, however, was not protected under these heat-shock conditions or reactivated after a shift in temperature from 45 or 50 degrees C to 21 degrees C. HspA was able to enhance the refolding of chemically denatured rabbit muscle lactate dehydrogenase in an ATP-independent manner. A homologue to the 16-kDa protein was also found to be induced upon heat-shock treatment in the mesophilic cyanobacterium Synechocystis sp. PCC 6803.

Amino Acid Sequence↗
PubMed1999

Effects of cicletanine on the progression of renal failure in 5/6 nephrectomized hypertensive rats.

1. The effect of cicletanine, a novel antihypertensive agent with natriuretic activity, on blood pressure and progression of renal failure of 5/6 nephrectomized spontaneously hypertensive rats with salt loading was examined. 2. All nephrectomized rats were randomly assigned to one of four groups and their diet was changed from a normal- to a high-salt (5.5% NaCl) diet for the next 10 weeks. Either 10 or 50 mg/kg per day cicletanine (low- and high-dose cicletanine, respectively) or 10 mg/kg per day trichlormethiazide were administered to rats during this period once a day. During the experimental period, urine volume, urinary excretion of sodium, protein, prostaglandin (PG) E2 and 6-keto-PGF1 alpha and systolic blood pressure (SBP) were measured every 2 weeks. 3. Systolic blood pressure was significantly reduced by the administration of trichlormethiazide and the higher dose of cicletanine, but not by the lower dose of cicletanine. 4. In contrast with changes to SBP, levels of serum creatinine in rats treated with both doses of cicletanine were significantly lower than in controls (0.57 +/- 0.12, 0.78 +/- 0.12 and 1.68 +/- 0.26 mg/dL for high- and low-dose cicletanine and control, respectively). 5. Urinary excretion of both PGE2 and 6-keto-PGF1 alpha were significantly increased in groups treated with high and low doses of cicletanine compared with control. In rats treated with trichlormethiazide, PGE2 and 6-keto-PGF1 alpha levels were significantly decreased compared with control. 6. In contrast with changes in SBP, marked glomerular sclerosis with hyalinosis found in the control group was not ameliorated by trichlormethiazide treatment. These changes were not observed in rats treated with low- and high-dose cicletanine, particularly those treated with the higher dose of cicletanine. 7. These data suggest that administration of cicletanine has a beneficial protective effect regarding the progression of renal failure, regardless of the level of blood pressure, through a direct and/or indirect action on the glomerulus.

6-Ketoprostaglandin F1 alpha↗
PubMed1999

Does intensive perioperative dialysis improve the results of coronary artery bypass grafting in haemodialysed patients?

BACKGROUND: Between January 1996 and April 1998, 17 chronic haemodialysed patients underwent coronary artery bypass grafting (CABG). Two of them simultaneously had valve replacement. METHODS: Except for two cases in which CABG was performed in an emergency, 15 patients (CRF group) received 3 consecutive days of haemodialysis in the preoperative period, intraoperative haemodialysis connected to cardiac pulmonary bypass (CPB) and continuous hemodiafiltration in the early postoperative period. The perioperative clinical parameters of the CRF group were compared with those of 17 age-matched patients with normal renal function undergoing CABG as the control (NRF group). RESULTS: When the perioperative variables were compared, no significant differences were seen in total operation time and CPB time, but we noted significant increases in the mean volume of transfused blood in the 6 perioperative days, postoperative intubation time, postoperative fasting time, and time spent in the intensive care unit. Levels of central venous pressure, systolic blood pressure, respiratory index (PaO2/FiO2) and daily fluid balance of the CRF group were the same as the control group in the early postoperative period. In addition, the levels of serum creatinine, urea nitrogen, potassium and hematocrit of CRF group remained almost constant in the early postoperative period. After all, the hospital morbidity of the CRF group was not more serious than that of the NRF group, and hospital mortality of the CRF and NRF groups was 0%. CONCLUSIONS: Our intensive perioperative dialysis programme could successfully manage the perioperative clinical course of haemodialysed patients undergoing CABG.

Coronary Artery Bypass↗
PubMed1999

Targeted inactivation of the gene psaK encoding a subunit of photosystem I from the cyanobacterium Synechocystis sp. PCC 6803.

Mutant strains of the unicellular cyanobacterium Synechocystis sp. PCC 6803, in which the psaK gene was insertionally inactivated by targeted mutagenesis, were constructed. The gene is one of the two potential PsaK-coding genes which have been found as a result of the genome project with this cyanobacterium. One of the mutants was characterized in detail. A monocistronic, 480-nucleotide mRNA of psaK was absent in total RNA from the mutant cells. Inactivation of psaK had little effect on the accumulation of polypeptides in the isolated PSI complexes except for a polypeptide with an apparent molecular mass of 4.6 kDa which was absent in the mutant. The amino-terminal amino acid sequence of the 4.6-kDa polypeptide confirmed that it was the translation product of psaK and further revealed a presequence of PsaK. Characteristics of photoautotrophic growth at different temperatures, the amount of chlorophyll per cell, photosynthetic electron transport rates with rates with various electron acceptors, the kinetics of charge recombination between P700+ and reduced FA/FB, and the molar ratio of chlorophyll to P700, of the mutant were not significantly different from those of the wild type. Furthermore, the trimer to monomer ratio of the PSI complexes isolated from the mutant was similar to that isolated from the wild type.

Amino Acid Sequence↗
PubMed1999

Possible involvement of descending serotonergic systems in antinociception by centrally administered elcatonin in mice.

To elucidate the mechanisms of analgesic action of elcatonin, a synthetic analog of eel calcitonin, the effect of centrally injected elcatonin on acetic acid-induced writhing behavior was examined in mice. Intracisternal or intracerebroventricular injection of elcatonin significantly inhibited acetic acid-induced writhing behavior, while the intrathecal injection of elcatonin did not inhibit it. The inhibitory effect of intracisternal elcatonin was significantly attenuated by subcutaneous pretreatment with methysergide and (+/-)-propranolol or by intrathecal pretreatment with methysergide, (+/-)-propranolol, 1-(2-methoxyphenyl)-4-[4-(2-phthalimido) butyl]-piperazine hydrobromide (NAN-190) and granisetron, but not with (+/-)-atenolol or butoxamine. Further, the depletion of spinal 5-hydroxytryptamine (5-HT, serotonin) by pretreatment with 5,7-dihydroxytryptamine (5,7-DHT) significantly attenuated the inhibitory effect of intracisternally injected elcatonin on acetic acid-induced writhing behavior. These results suggest that the inhibitory descending serotonergic systems may be involved, through 5-HT1A and 5-HT3 receptors, in the production of an antinociceptive effect by centrally injected elcatonin.

5,7-Dihydroxytryptamine↗
PubMed1999

Nifedipine and arotinolol in combination for accelerated-malignant hypertension: results of one year follow-up.

The effects of a combined therapy with a calcium channel antagonist and alphabeta-blocker in patients with accelerated-malignant hypertension on blood pressure and renal function were examined. Thirteen patients presented with the clinical features of malignant hypertension (diastolic blood pressure >130 mmHg, retinal damage and progressive renal failure) at our hospital, over the 3 yr period from 1995 to 1997. These patients were treated with both a calcium antagonist, 60-80 mg/d dose of long acting nifedipine, and an alphabeta-blocker, 20 mg/d dose of arotinolol, for over 12 mo. At admission, the average blood pressure of the patients was 233+/-8/144+/-3 mmHg. The level of serum creatinine in these patients was 6.2+/-1.0 mg/dl. Intermittent hemodialysis therapy was introduced in 7 patients. Three days after treatment, blood pressure decreased to 162+/-4/102+/-4 mmHg. A month later, blood pressure decreased to 148+/-3/89+/-2 mmHg and serum creatinine levels were 3.6+/-0.4 mg/dl. Renal function in these patients improved, and they completely recovered from renal dysfunction, allowing withdrawal of haemodialysis therapy. One year later, the blood pressure in all of these patients was well controlled and no further renal deterioration was observed, except in one patient. Despite the reduction in blood pressure, one patient was on hemodialysis three times a week after 8 mo of treatment. From these finding, it is concluded that combination therapy with a calcium antagonist and alphabeta-blocker is effective in both the reduction of highly elevated blood pressure and protection of the kidneys, resulting in amelioration of accelerated-malignant hypertension.

Adrenergic beta-Antagonists↗
PubMed1999

Incidence of gingival hyperplasia caused by calcium antagonists in continuous ambulatory peritoneal dialysis patients.

Calcium antagonists are widely used for the treatment of cardiovascular diseases in patients receiving dialysis therapy. The incidence of gingival hyperplasia has been reported as 10%-20% in patients treated with calcium antagonists in the general population. However, precise reports examining the incidence or pathogenesis of gingival hyperplasia in continuous ambulatory peritoneal dialysis (CAPD) patients are lacking. We recruited 54 CAPD patients. Three patients treated with long-acting nifedipine and one patient treated with felodipine were reported by a periodontist to have gingival hyperplasia. No patients were taking amlodipine and other calcium antagonists. After discontinuation of calcium antagonists, gingival hyperplasia disappeared within 1 month. Based on these results, we suggest that it is important to examine whether the gingiva is overgrown in CAPD patients taking calcium antagonists.

Adult↗
PubMed1999

Evidence that gender difference affects peritoneal dialysis capacity in continuous ambulatory peritoneal dialysis patients.

The progression of renal disease is reported to be more rapid in male patients than in premenopausal females. However, few studies compare the difference in dialysis therapy between males and females. We compared the efficacy of peritoneal dialysis capacity, using measurements of retention volume and pelvic cavity by helical section of computed tomography (CT) in 6 male and 6 female patients. The patients did not differ significantly in age (males: 54 +/- 3 years; female: 56 +/- 4 years). Males were heavier than females (p < 0.05). Retention volume in the visceral cavity was significantly larger in males (1787 +/- 43 mL) than in females (1580 +/- 59 mL) (p < 0.05). Peritoneal dialysis capacity was evaluated by peritoneal equilibration test (PET). Although no significant differences were observed in the PET data, when the PET results at 4 hours were divided by body weight in kilograms, a significant difference between males and females was seen (p < 0.05). There was a mild, but not significant, correlation between the volume of the pelvis as measured by helical CT and the PET data per kilogram body weight (p = 0.07). These results suggest that gender differences in peritoneal dialysis capacity relate partially to the difference in pelvic cavity volume.

Female↗
PubMed1998

A period of anaerobic exercise increases the accumulation of reactive carbonyl derivatives in the lungs of rats.

It is known that acute physical exercise may have diverse pathophysiological consequences in various organs due to free radical formation. We have investigated whether a period of anaerobic running to exhaustion in rats results in oxidative modification of proteins in the lungs. Six rats of an exercised group (E) ran for two periods of 5 min at a speed of 30 m.min-1 followed by a recovery period of 5 min, and then by a third period of running to exhaustion. Reactive carbonyl derivatives (RCD) were measured by the Western blot technique on lungs of E and control (C) rats. In addition, the activity of glutamine synthetase (GS) was also monitored as marker of oxidative damage to proteins. This investigation revealed significant exercise-induced increases in accumulation of RCD in the lungs of the E group compared with the C group. The RCD signals were visibly stronger in proteins with molecular weight of 55 kDa and 32 kDa. The activity of GS was higher by about 30% in E rats than in C rats. The present data suggest that anaerobic exercise induces protein oxidation in the lungs.

Anaerobiosis↗
PubMed1998

The effect of high altitude and caloric restriction on reactive carbonyl derivatives and activity of glutamine synthetase in rat brain.

Both exposure to high altitude (HA) and caloric restriction (CR) may influence free radical generation. The aim of the present study was to evaluate the effects of 4 wk chronic exposure to 4,000m of HA and CR (60% of CR of control (C) rats) on protein oxidation in brain. Eighteen rats with similar body mass were assigned to CR, HA and C rats. Reactive carbonyl derivatives (RCD), marker of protein oxidation, were measured by Western blot. In addition, the activity and protein content of glutamine synthetase (GS) were determined. The body mass of C rats was significantly higher (P< 0.001) than that of HA and CR groups. The quantified signal intensity of RCD was significantly stronger in C rats than in HA and CR rats. The activity of GS was significantly increased in CR rats, while the protein content of GS was decreased in HA rats compared to C group. The data suggest that both HA and CR decreases the accumulation of RCD in the brain, however the mechanism of the decrease seems to be different during HA and CR.

Altitude↗
PubMed1998

Assessment of psychosocial stressors and maladjustment among foreign students of the University of the Ryukyus.

An extensive survey of problems encountered by foreign students of the University of the Ryukyus and the resulting levels of stress was carried out in order to determine the main stressors hindering academic progress and personal adjustment. Subjectively perceived stress levels after arrival in Japan were obtained from 134 subjects through a comprehensive questionnaire for reporting specific stressors. The 30-item General Health Questionnaire (GHQ) was included to assess mental health state. Differences in scores by area of origin were also determined for the total GHQ scores and its sub-scales. The GHQ results showed that regardless of length of time in Japan, more than 60% of the subjects scored within a range usually indicative of a mental health risk. Mean scores by area of origin showed a 50% reduction over time for non-Chinese Asians and North American/Europeans, but only a reduction of 1.1% or less for Chinese, Latin American, Middle/Near Eastern and African subjects. Limitations in achievement of academic goals were reported by the greatest number of students as causing moderate to excessive stress (57.5%); most frequently reported causes were language inadequacy (55.2%), reference materials unavailable (34.3%), unfamiliarity with Japanese study methods (32.1%), and inadequate guidance from teachers/advisors (26.9%). Various social, personal and daily life problems in the non-academic setting were also reported as causing high stress levels. Most of the stressors identified are not considered inevitable and point toward directions to pursue in preventive strategies in mitigating psychological distress and maladjustment of students.

Adolescent↗
PubMed1998

Heterogeneity of protein profiles of Helicobacter pylori isolated from individual patients.

BACKGROUND: In order to characterize the diversity of Helicobacter pylori (H. pylori) in infected individuals, 10 colonies of H. pylori were isolated from the gastric juice of 25 patients with gastroduodenal diseases (total 250 isolates). METHODS: Protein profiles of isolates were compared by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Results were confirmed by Western blotting (immunoblotting) test using rabbit antisera against three different strains of H. pylori. RESULTS: The protein profiles of 18 of 25 cases (72%) showed a single type of H. pylori with the same polypeptide pattern. In contrast, heterogeneity in the protein profiles was seen in isolates from seven cases (28%). Two differing H. pylori types with two very different polypeptide patterns were found in 10 isolates from one case. In six patients, the protein profiles of isolates were found to have variations in their polypeptides between molecular weights of 30,000 (30K) and 14K, which are thought to be associated with bacterial membrane protein. In some isolates, a polypeptide band of the 16K was missing. Each of three different antisera confirmed differences among the distinct isolates from individual patients. CONCLUSIONS: These findings suggest that more than one antigenically different strain of H. pylori may exist in same infected individuals.

Animals↗