Biomedical subjects

H Nakamoto

Publications and source records attributed to H Nakamoto.

At least 37 records · Page 2Linked to original sources

PubMed2001

Crystal nephropathy: a variant form of myeloma kidney--a case report and review of the literature.

Cast nephropathy is the most common form of myeloma kidney, and also one of the major determinants of a patient's prognosis. We experienced a case of multiple myeloma with acute renal failure that was associated with massive crystal deposition in kidney and bone marrow. Large crystal formation in myeloma kidney is a rare pathological finding in renal biopsies. In the literature, most of the cases with multiple myeloma with extracellular crystal deposition often have a rapidly progressive course with a poor prognosis. Ball et al. [1993] suggested that this type of extracellular crystal deposition be designated as "crystalglobulinemia syndrome". The characteristics of the clinical and histopathological features, rapid progression and poor outcome, and crystal formation in the tubules found in the present case and in those previously reported, support the proposal of a new concept of "crystal nephropathy".

Aged↗

PubMed2001

New animal models for encapsulating peritoneal sclerosis--role of acidic solution.

OBJECTIVE: Encapsulating peritoneal sclerosis (EPS), in which all or part of the intestine is enveloped in a fibrous ball resembling a cocoon, is a serious complication of peritoneal dialysis (PD). The aim of the present study was to investigate whether pH-neutral or acidic dialysis solutions induce peritoneal fibrosis. DESIGN: We divided 18 male Wistar-Kyoto (WKY) rats into three groups and dialyzed them with various solutions as follows: group I, 10 mL acidic dialysis solution (pH 3.8, containing 1.35% glucose), n = 6; group II, 10 mL pH 5.0 dialysis solution, n = 6; and group III, 10 mL neutral dialysis solution (pH 7.0), n = 6. Peritoneal catheters were inserted, and dialysis solution was injected every day for 40 days. At the end of the experiment, a peritoneal equilibration test (PET) was performed. Expression of mRNA of aquaporins 1 and 4 (AQP-1 and AQP-4) in the peritoneum were studied by semiquantitative reverse-transcriptase polymerase chain reaction (RT-PCR). RESULTS: In rats treated with pH 3.8 dialysis solution, necropsy findings revealed features identical to those of EPS. The typical appearance was of granulation tissue or fibrotic tissue (or both) covering multiple surfaces. Multiple adhesions were present. In microscopic examinations, peritoneal fibrosis and loss of mesothelium were found. In rats treated with pH 7.0 dialysis solution, no signs of EPS were seen. In rats treated with pH 5.0 dialysis solution, milder changes (subserosal thickening and partial adhesion of the peritonea) were observed. The mRNA of AQP-1 and AQP-4 were expressed in the peritonea of the rats. The expression of the AQPs was significantly suppressed in rats treated with pH 3.8 dialysis solution. CONCLUSIONS: In rats, long-term intraperitoneal injection of acidic dialysis solution produced features typical of EPS in humans. Newly developed neutral dialysis solutions protected the against the development of EPS during peritoneal dialysis in rats.

Animals↗

PubMed2000

Regular training modulates the accumulation of reactive carbonyl derivatives in mitochondrial and cytosolic fractions of rat skeletal muscle.

The oxygen flux into the mitochondria of skeletal muscle increases with exercise. However, the extent of oxidative damage to mitochondrial proteins of skeletal muscle has only been estimated. We studied the alteration of reactive carbonyl derivatives (RCD) in mitochondrial and cytosolic fractions of skeletal muscle following 9 weeks of swimming training in rats. The RCD content of mitochondria was significantly elevated compared with the cytosolic fraction of both control and exercised animals. Accumulation of RCD in muscle mitochondria of the exercised group was also significantly elevated (P < 0.05). On the other hand, alteration of the accumulation of RCD was not apparent in the cytosolic fraction of skeletal muscle. The activity of proteasome complex, however, was increased in the cytosolic fraction of exercised muscle (P < 0.05). The data suggest that mitochondria of skeletal muscle accumulate significantly larger amounts of RCD than the cytosolic fraction and the tendency of the accumulation varies in cell fractions. Exercise training increases the accumulation of protein damage in mitochondria of skeletal muscle but cytosolic proteins are protected by increased activity of proteasome complex and possibly by other antioxidant enzymes.

Animals↗

PubMed2000

Constitutive expression of a small heat-shock protein confers cellular thermotolerance and thermal protection to the photosynthetic apparatus in cyanobacteria.

The role of a small heat-shock protein (Hsp) in the acquisition of thermotolerance in cyanobacteria was investigated. Synechococcus sp. PCC 7942 was transformed with an expression vector carrying the coding sequence of the hspA gene encoding a small heat-shock protein from Synechococcus vulcanus under the control of the tac promoter. The transformant which was shown to constitutively express HspA displayed improved viability compared with the reference strain upon transfer from 30 to 50 degrees C in the light. When the heat shock was given in darkness, the survival rate in the reference strain increased greatly, approaching a level similar to that for the HspA expressing strain after heat shock in the light. Expression of HspA increased thermal resistance of photosystem II (PS II) and protected phycocyanin from heat-induced photobleaching. Our results are indicative of a central role for HspA in amelioration of the harmful effect of light during heat stress and identified the possible sites of action of the small Hsp in vivo to be the PS II complex and the light-harvesting phycobilisomes.

Adaptation, Physiological↗

PubMed2000

Chromatographic separation of a small subunit (PsbW/PsaY) and its assignment to Photosystem I reaction center.

By using a hydroxyapatite column, the five major Photosystem I (PSI) subunits (PsaA,-B,-C,-D,-E) solubilized by sodium dodecyl sulfate (SDS) were fractionated from a spinach PSI reaction center preparation. Another small (5-6 kDa) polypeptide was also separated, and purified to homogeneity. Mass spectroscopy yielded its molecular weight to be 5942 +/- 10. This polypeptide had an N-terminal sequence homologous to those of previously reported 5-kDa subunits from spinach and wheat and a 6.1-kDa subunit of Chlamydomonas, which had all been assigned to Photosystem II (PSII) and designated as PsbW. However, we found similar 5-kDa polypeptides with highly conserved N-terminal sequences ubiquitously in PSI particles from other plants including Daikon (Raphanus sativus, Japanese radish), Chingensai (Brassica parachinensis, Chinese cabbage), parsley and Shungiku (Chrysanthemum coronarium, Garland chrysanthemum) as well. Preparations of spinach PSI particles prepared by using a mild detergent (digitonin) had this 5-kDa subunit, while PSII particles did not. Moreover, a bare-bone PSI reaction center preparation consisting of PsaA/B alone had a more than stoichiometric amount of this 5-kDa polypeptide. A mechanically (without detergent) fractionated stroma thylakoid preparation from Phytolacca americana, which lacked other PSII subunits, also contained this 5-kDa subunit. Thus, we propose that this 5-kDa polypeptide, previously designated as a PSII subunit (PsbW), is an integral subunit of PSI as well.

Amino Acid Sequence↗

PubMed2000

Exercise preconditioning against hydrogen peroxide-induced oxidative damage in proteins of rat myocardium.

Both regular physical exercise and low levels of H(2)O(2) administration result in increased resistance to oxidative stress. We measured the accumulation of reactive carbonyl derivatives and the activities of proteasome complex and DT-diaphorase in cardiac muscle of trained and untrained rats after chronic i.p. administration of 1 ml t-butyl H(2)O(2) (1 mmol/kg for 3 weeks every second day). Twenty-four rats were randomly assigned to a control group administered with saline, control administered with H(2)O(2), and exercised administered either saline or H(2)O(2). The activity of DT-diaphorase significantly increased in H(2)O(2) administered and exercised groups, indicating that an increase in H(2)O(2) levels stimulate the activity of this enzyme. The cardiac muscle of H(2)O(2) administered nonexercised animals accumulated significantly more carbonyl than control group (P < 0.05). The exercise and H(2)O(2) administration resulted in less oxidatively modified protein than found in nonexercised groups (P < 0.05). The peptide-like activity of proteasome complex was induced by the treatment of H(2)O(2) and exercise and exercise potentiate the effect of H(2)O(2). On the other hand, the chymotrypsin-like and trypsin-like activities were stimulated only by physical training and H(2)O(2) administration. The data suggest that chronic administration of H(2)O(2) after exercise training decreases the accumulation of carbonyl groups below the steady-state level and induces the activity of proteasome and DT-diaphorase. Hence, the stimulating effect of physical exercise on free radical generation is an important phenomenon of the exercise-induced adaptation process since it increases resistance to oxidative stress. Regular exercise training is a valuable physiological means of preconditioning the myocardium to prolonged oxidative stress.

Adaptation, Physiological↗

PubMed2000

Localization of calcitonin receptor mRNA in the mouse brain: coexistence with serotonin transporter mRNA.

To elucidate the sites of and mechanisms of analgesic effect of centrally injected calcitonin, we examined expression of calcitonin receptor mRNA in the mouse brain by in situ hybridization techniques. Calcitonin receptor mRNA was expressed in various brain regions, including the preoptic area, dorsomedial hypothalamic nucleus, lateral hypothalamic area, periaqueductal gray, dorsal raphe nucleus, locus coeruleus, lateral parabrachial nucleus, gigantocellular reticular nucleus alpha part, lateral paragigantocellular nucleus, raphe magnus nucleus and solitary tract nucleus, which are known to play important roles in pain modulation. In addition, a double in situ hybridization technique demonstrated the intense expression of calcitonin receptor mRNA on serotonergic neurons in some raphe nuclei and the lateral paragigantocellular nucleus, suggesting the involvement of central serotonergic pathways in analgesic effect of calcitonin.

Animals↗

PubMed2000

Tubular osteopontin expression in human glomerulonephritis and renal vasculitis.

Tubulointerstitial change is a common histopathologic feature of acute and chronic glomerular diseases and is more closely correlated than glomerular damage with renal function and subsequent outcome. Monocyte infiltration is presumed to be initiated by chemoattractants and has a pivotal role in tubulointerstitial changes. Osteopontin (OPN) is a candidate as such a chemoattractant and has been shown to recruit monocytes into the interstitium of animal models of renal diseases. In this study, we investigated OPN expression by immunostaining and its correlation with clinical and histopathologic parameters in patients with immunoglobulin A (IgA) nephropathy, diffuse proliferative lupus nephritis (DPLN), and myeloperoxidase-antineutrophil cytoplasmic autoantibody-associated microscopic polyangiitis (MMP). Twenty patients with IgA nephropathy, 12 patients with DPLN, and 14 patients with MMP were studied. OPN expression, which was constitutively observed on the apical membrane of distal tubules, was upregulated in the cytoplasm of proximal and distal tubular epithelium parallel to the degree of interstitial mononuclear cell infiltration in patients with IgA nephropathy, as well as those with DPLN. CD68(+) monocyte infiltration significantly correlated with the degree of OPN expression in the tubular epithelium. Conversely, there was no apparent induction of OPN in the proximal and distal tubular epithelium of patients with MMP despite remarkable monocyte infiltration. In conclusion, these data suggest that inducible expression of OPN in the tubular epithelium seems to be associated with interstitial monocyte infiltration and subsequent tubulointerstitial changes in some forms of human renal diseases.

Biopsy↗

PubMed2000

Vitamin B6 supplementation can improve peripheral polyneuropathy in patients with chronic renal failure on high-flux haemodialysis and human recombinant erythropoietin.

BACKGROUND: High-flux haemodialysis (HD) has recently been vigorously promoted as a novel standard, and it can indeed efficiently reduce the occurrence of most uraemic symptoms due to middle molecular toxins and/or underdialysis. However, some symptoms remain problematical, particularly peripheral polyneuropathy (PPN). One of the possible reasons for this is that the patients may have low concentrations of some nutrients, e.g. vitamin B(6), necessary for normal peripheral neuron function. METHODS: Predialysis serum pyridoxal-5'-phosphate (P5P) level was determined in 36 chronic HD patients who were undergoing high-flux HD and receiving human recombinant erythropoietin. Among them, 26 patients suffered from PPN. Prior to supplementation, these 26 patients were examined and their neurological symptoms were ranked according to our PPN symptom score. Vitamin B(6) (60 mg/day) was randomly prescribed to 14 of them, and vitamin B(12) (500 microg/day) was prescribed to the others. After 4 weeks, all the patients were re-examined. RESULTS: We found that predialysis serum P5P levels of HD patients with PPN were not significantly lower than those of matched HD patients without PPN. Nonetheless, it was demonstrated that supplementation with vitamin B(6) for 4 weeks significantly increased the predialysis level of P5P and dramatically attenuated PPN symptoms compared with initial symptoms. No improvement was observed in response to vitamin B(12) supplementation. CONCLUSION: This result suggests that although vitamin B(6) deficiency could not be demonstrated in patients with chronic renal failure on high-flux HD, vitamin B(6) supplementation was effective in improving PPN symptoms of various aetiologies, possibly because of vitamin B(6) resistance to PPN in these patients.

Chronic Disease↗

PubMed2000

[A case report of Campylobacter fetus subspecies fetus oophoritis].

A 45-year-old female with oophoritis (pelvic inflammatory disease) caused by Campylobacter fetus (C. fetus) is reported. She was admitted to the hospital because of high fever and an acute abdomen. On admission, severe inflammation was observed by the laboratory findings, and abdominal X-ray and CT scan revealed ileus with marked swelling of the right ovary. Laparotomy was performed with adonexooophrectomy due to the tubo-ovarian abscesses. C. fetus was isolated from the right ovary, salpinx and ascites. Erythromycin was administered after a sensitive test of C. fetus as the bacteria was isolated at operation. She was discharged on the 17th day after her admission. Indirect immunofluorescent test with hyperimmune rabbit sera to isolated C. fetus revealed a fine to coarse granular immunoreaction in the cytoplasm of the macrophages infiltrated in the tissue. This result was interpreted as the existence and growth of bacteria in the right ovarian tissue. Oophoritis due to C. fetus subspecies fetus is very rare. To our knowledge, this case is the second case reported in Japan.

Campylobacter Infections↗

PubMed2000

Control of blood pressure and prevention of end-organ damage in patients with accelerated hypertension by combination with arotinolol and extended release nifedipine.

In patients with accelerated (malignant) hypertension, end-organ damage is the determinant factor for prognosis. Although recent advances in antihypertensive therapy have improved the outcome of patients with accelerated hypertension, the effectiveness of antihypertensive therapy still remains less convinced. In this study, we followed 13 patients clinically diagnosed with accelerated hypertension (defined as diastolic blood pressure > 130 mmHg, retinopathy with K-W IV and accelerated renal impairment) for 3 yr. One patient died due to acute myocardial infarction arising from poor compliance with antihypertensive therapy. One patient was maintained on hemodialysis for 3 yr. One patient was introduced for continuous ambulatory peritoneal dialysis (CAPD) for a year and then lived without dialysis therapy. The remaining 10 patients were followed for 3 yr. All patients were initially treated with intravenous administration of calcium antagonist for reduction of blood pressure, followed by hemodialysis therapy if needed. After stabilization of blood pressure, combination therapy with extended release nifedipine (40 to 80 mg daily) and arotinolol (20 mg daily) was started. The targets for blood pressure control were a systolic pressure of 135 mmHg and a diastolic pressure of 80 mmHg. If blood pressure control was unsatisfactory, guanabenz (2 to 4 mg before bedtime), a central acting drug, was added. At presentation, the mean diastolic blood pressure (mDBP) among the 10 remaining patients was 134 +/- 2 mmHg, the mean serum creatinine (mScr) was 4.5 +/- 0.7 mg/dl and the left ventricular mass index (LVMi) as measured by echocardiography was 150 +/- 9 g/m2. At 1 yr, the mDBP was reduced to 90 +/- 3 mmHg, the mScr to 2.9 +/- 0.9 mg/dl and the LVMi to 140 +/- 9 g/m2. At 3 yr, the mDBP was stabilized at 79 +/- 3 mmHg, the mScr maintained at 2.2 +/- 0.4 mg/dl, and the LVMi reduced to 128 +/- 9 g/m2. These results indicate that appropriate blood pressure control is important for improvement of renal impairment and cardiac damage in patients with accelerated hypertension. Moreover, combination therapy with arotinolol and extended release nifedipine may be beneficial for this purpose.

Adrenergic beta-Antagonists↗

PubMed2000

Quantitative blood velocity mapping in glomerular capillaries by in vivo observation with an intravital videomicroscope.

We have evaluated rat glomerular microcirculation under in-vivo condition with an intravital videomicroscope. To measure erythrocyte velocities, a line segment was set along the glomerular capillaries in time-sequential videotaped images and then a spatiotemporal image was constructed along that segment. The angle of striped pattern in the spatiotemporal image which reflects the erythrocyte velocity, was estimated to compute erythrocyte velocity vector mapping. We found that erythrocyte velocities in rat glomeruli were significantly faster in diabetic rats than in control rats (p < 0.05). In conclusion, we have succeeded in quantitatively evaluating the in-vivo renal microcirculation with our videomicroscope system and by spatiotemporal image analyzing method.

Animals↗

PubMed2000

Impact of introduction of continuous ambulatory peritoneal dialysis on blood pressure: analysis of 24-hour ambulatory blood pressure.

Introduction of continuous ambulatory peritoneal dialysis (CAPD) induces a variety of hemodynamic changes in patients with end-stage renal failure. Among them, blood pressure (BP) control is likely to be the most important in determining long-term survival. The aim of our study was to use 24-hour ambulatory blood pressure monitoring (24 ABPM) to evaluate the previous and present BP status of patients on CAPD. We studied 18 non diabetic hypertensive patients who were introduced onto CAPD. At least 3-6 months before the introduction of CAPD, recordings of 24 ABPM were obtained. These recordings were then compared to others obtained 2-3 months after the introduction of CAPD. The average BP was higher before CAPD than after (160/91 +/- 10/5 mmHg vs 154/88 +/- 6/3 mmHg, p < 0.01). In addition, the doses and number of antihypertensive drugs used by the patients were reduced. Analysis of 24 ABPM revealed BP reduction predominantly in the daytime and less in the nighttime after introduction of CAPD. These results indicate that introduction of CAPD cannot reduce susceptibility of cardiovascular events, because nocturnal elevation of BP remains unchanged. We are therefore reminded that, after introduction of CAPD, casual BP measurements confined to the daytime may underestimate cardiovascular risk.

Adult↗

PubMed2000

Telemedicine system for home automated peritoneal dialysis.

We have developed a new telemedicine system to monitor elderly and handicapped patients that use an automated peritoneal dialysis (APD) system to perform continuous ambulatory peritoneal dialysis (CAPD) at home. The system has two parts: (1) a data collection and transport system, and (2) an interview system ("View Send" system). The former is assembled from the APD cycler, an automated blood-pressure recorder, and a scale. The latter is a combination of a digital camera, television, and set-top box (a kind of computer). The APD system contains recording and data transport junctions, a monitoring device, and a data tabulation function. All data collected by the APD system are sent directly in real time to the physician's office. Patients can easily use this telemedicine system to contact the medical staff at the Saitama Medical School CAPD center and to consult concerning their condition. Furthermore, the staff can directly change the CAPD schedule (dose and duration). Seven patients, including some who are older than 90 years or who are handicapped, have been using this telemedicine system for between 1 and 6 months (average: 3 months). From our recent experience, our tentative conclusions are that (1) elderly and handicapped patients benefit from this system by being able to maintain CAPD without major problems and accidents; (2) other problems are mainly due to simple mistakes such as accidentally pushing the on and off switches; (3) quality of life is improved for the patients.

Aged↗

PubMed2000

Glucocorticoid restores the deterioration of water transport in the peritoneum through increment in aquaporin.

This study was carried out to investigate the role of aquaporin (AQP) in the peritoneum undergoing continuous ambulatory peritoneal dialysis (CAPD). Furthermore, we examined the effects of treatment with prednisolone (PSL) in a rat model of peritoneal sclerosis. We modelled peritoneal sclerosis by using dialysis solution with the addition of 0.1% chlorhexidine gluconate (CHG) for 10 days. Twenty male Wistar Kyoto (WKY) rats were divided into four groups and dialyzed with various solutions: (1) saline (NS group, n = 5); (2) 10% glucose (TZ group, n = 5); (3) 0.1% CHG (CHG group, n = 5); and (4) 0.1% CHG plus PSL (CHG + PSL group, n = 5). Expression of mRNA of AQPs (AQP-1-AQP-4) was studied by semi-quantitative reverse-transcription polymerase chain reaction (RT-PCR). Expression of AQP-4 was also measured by Western blot analysis. Ultrafiltration volume and peritoneal function were measured by the peritoneal equilibration test. In the TZ group, expression of AQP-1 and AQP-4 were significantly enhanced, in parallel with an increment in ultrafiltration volume. On the other hand, in the CHG group, expression of AQP-1 and AQP-4 were significantly suppressed, and ultrafiltration volume was lost. The use of PSL with CHG completely restored the expression of AQP-1 and AQP-4, and peritoneal function improved. No expression of AQP-2 and AQP-3 was seen in the peritoneum. Our results suggest that AQP-1 and AQP-4 may be important factors in water transport in patients undergoing CAPD. PSL might be an effective treatment to prevent the progress of peritoneal sclerosis in patients undergoing CAPD.

Animals↗

PubMed2000

Vitamin B6 deficiency in elderly patients on chronic peritoneal dialysis.

Polyneuropathy is one of the most frequent manifestations in chronic uremia. Among the factors related to polyneuropathy, vitamin B6 deficiency is well known. The exact prevalence of vitamin B6 deficiency related to neurological manifestations has not been previously reported. We studied vitamin B6 status, collected self-reported symptoms, and carried out full neurological examinations in 66 patients on chronic peritoneal dialysis. Vitamin B6 status was estimated by direct measurement of pyridoxal phosphate. In general, symptoms related to vitamin B6 deficiency are peripheral neuropathies, such as paresthesia, burning and painful dysesthesias, and thermal sensations. These symptoms were reported and assigned one of five grade scores. Of our 66 patients, 12 patients complained at least one sensory abnormality. The levels of vitamin B6 in the patients varied between 1.0 ng/mL and 30 ng/mL. Patients who complained of neurological symptoms owing to vitamin B6 deficiency were significantly older than the other patients. In analyzing the symptomatic cases before and after vitamin B6 supplementation, a significant correlation was seen between the level of vitamin B6 and symptoms. Within one month after initiation of oral vitamin B6 supplementations (30 mg daily), levels of pyridoxal phosphate rose, and sensory abnormalities improved in 8 of 12 patients. When peripheral neuropathy is suspected in elderly patients on chronic peritoneal dialysis, vitamin B6 deficiency should be taken into consideration as the cause. If vitamin B6 deficiency is appropriately treated by oral supplementation, sensory abnormalities can be eliminated.

Adolescent↗

PubMed1999

HtpG is essential for the thermal stress management in cyanobacteria.

The heat shock protein (Hsp) HtpG is a member of the Hsp90 protein family. We cloned a single-copy gene encoding a homologue of HtpG from the unicellular cyanobacterium Synechococcus sp. PCC 7942. Sequence alignment with HtpGs from other prokaryotes revealed unique features in the cyanobacterial HtpG primary sequence. A monocistronic mRNA of the htpG gene increased transiently in response to heat shock. In order to elucidate the role of HtpG in vivo, we inactivated the htpG gene by targeted mutagenesis. Although the mutation did not affect the photoautotrophic growth at 30 and 42 degrees C, the mutant cells were unable to grow at 45 degrees C. They lost both basal and acquired thermotolerances. These results indicate that HtpG plays an essential role for the thermal stress management in cyanobacteria, the first such an example for either a photosynthetic or a prokaryotic organism.

Amino Acid Sequence↗

PubMed1999

Carbonylated proteins in aging and exercise: immunoblot approaches.

Protein carbonyls were studied in aging and exercise by immunoblot followed by one- or two-dimensional polyacrylamide gel electrophoresis using antibodies against 2,4-dinitrophenylhydrazones. Proteins of rat kidneys exhibited significant age-related increase in the amount of carbonyl while those of the brain and liver did not. Major carbonylated proteins in the kidney included serum albumin. In nematodes in which protein carbonyls increased with age, one of the carbonylated proteins was identified as vitellogenin, an egg-yolk protein. A possible biological significance of this protein present in abundance even after egg-laying stages is discussed in terms of protection against oxidative stress. Exhaustive exercise induced significant increase in the carbonylation of selected but unidentified proteins in the lung. This oxidative stress might be caused by xanthine oxidase in this tissue and hypoxanthine derived from ATP-depleted muscles. Exercise at high altitude caused higher carbonylation of the skeletal muscle proteins, most notably a protein likely to be actin, than that at sea level but no significant difference was observed in lipid peroxidation. These studies emphasize the value of immunoblot analysis of tissue protein carbonyls in a variety of situations where oxidative stress is likely involved.

Aging↗