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Biomedical subjects

M Kishimoto

Publications and source records attributed to M Kishimoto.

At least 55 records · Page 3Linked to original sources
PubMed1997

Sensitive, selective gas chromatographic-mass spectrometric analysis with trifluoroacetyl derivatives and a stable isotope for studying tissue sorbitol-producing activity.

One of the major mechanisms involved in diabetic microangiopathy is considered to be an altered polyol pathway. However, clarifying the pathophysiology is difficult due to the lack of a sensitive method for measuring the reduction of glucose to sorbitol in tissue. Here we report a sensitive and selective method for polyol measurement using trifluoroacetyl (TFA) derivatives of polyols and stable isotope-labeled D-sorbitol (U-[13C]sorbitol, 13C6H14O6, 98.7%) as an internal standard. Gas chromatography-mass spectrometry (GC-MS) using an SE-30 capillary column gave elution of TFA derivatives of sugars, polyols and U-[13C]sorbitol within 8 min, with clear separation of sorbitol. In the calibration study, the coefficients of correlation between the amount of sorbitol added and that determined in standard solutions containing 0.1-8.0 nmol sorbitol, erythrocyte mixture and liver cytosol mixture were r = 0.999, r = 0.997 and r = 0.997, respectively. The precision of the GC-MS measurement of standard solution was C.V. = 4.3%. Because glucose is used as a substrate, the method can clarify the polyol pathway under physiological conditions. With this method, Km and Vmax values of the reductase in erythrocytes were 115 +/- 19 mmol/l and 4.42 +/- nmol/min/g of hemoglobin. In human liver, on the other hand, they were 755 +/- 132 mmol/l and 0.773 +/- 0.090 nmol/min/mg of protein, respectively. This difference of Km values suggested that aldehyde reductase rather than aldose reductase is mainly responsible for reducing glucose to sorbitol in the liver. In conclusion, this newly developed method offers a highly sensitive and selective procedure for measuring low concentrations of sorbitol in various tissues and cells and should enable clarification of the kinetics of glucose reduction to sorbitol, which in turn can be used to evaluate the role of an altered polyol pathway in the pathophysiology of diabetic microangiopathy.

Adolescent↗
PubMed1997

Glycation-dependent, reactive oxygen species-mediated suppression of the insulin gene promoter activity in HIT cells.

Prolonged poor glycemic control in non-insulin-dependent diabetes mellitus patients often leads to a decline in insulin secretion from pancreatic beta cells, accompanied by a decrease in the insulin content of the cells. As a step toward elucidating the pathophysiological background of the so-called glucose toxicity to pancreatic beta cells, we induced glycation in HIT-T15 cells using a sugar with strong deoxidizing activity, D-ribose, and examined the effects on insulin gene transcription. The results of reporter gene analyses revealed that the insulin gene promoter is more sensitive to glycation than the control beta-actin gene promoter; approximately 50 and 80% of the insulin gene promoter activity was lost when the cells were kept for 3 d in the presence of 40 and 60 mM D-ribose, respectively. In agreement with this, decrease in the insulin mRNA and insulin content was observed in the glycation-induced cells. Also, gel mobility shift analyses using specific antiserum revealed decrease in the DNA-binding activity of an insulin gene transcription factor, PDX-1/IPF1/STF-1. These effects of D-ribose seemed almost irreversible but could be prevented by addition of 1 mM aminoguanidine or 10 mM N-acetylcysteine, thus suggesting that glycation and reactive oxygen species, generated through the glycation reaction, serve as mediators of the phenomena. These observations suggest that protein glycation in pancreatic beta cells, which occurs in vivo under chronic hyperglycemia, suppresses insulin gene transcription and thus can explain part of the beta cell glucose toxicity.

Acetylcysteine↗
PubMed1997

Identification of a point mutation (G727T) in the glucose-6-phosphatase gene in Japanese patients with glycogen storage disease type 1a, and carrier screening in healthy volunteers.

Glycogen storage disease type 1a (GSD 1a) is an autosomal recessive metabolic disorder caused by a deficiency in glucose-6-phosphatase (G6Pase). We analyzed the G6Pase gene of two unrelated Japanese families with GSD 1a. DNA sequencing of all five exons and exon-intron junctions revealed a G-to-T transversion at nucleotide 727 (G727T) in exon 5, which has been previously reported to cause abnormal splicing. Family studies using mismatch PCR showed that three patients were homozygous for the G727T mutation, while the parents were heterozygous. To investigate allele frequencies, we screened 216 Japanese healthy volunteers and found one asymptomatic carrier. Our findings suggest that the G727T mutation may be prevalent in Japan.

Adult↗
PubMed1997

Comparisons of modalities of mechanical stimulation with a toothbrush on improvement of oxygen sufficiency in dog gingiva.

Mechanical stimulation with a toothbrush was applied to each quadrant of 10 dogs at a force of 200 g for 10 s using following modalities: vibration at attached gingiva, pressurization at attached gingiva, vibration at marginal gingiva and no treatment as a control. Hemoglobin oxygen saturation (SO2) in the gingiva was measured by non-invasive tissue reflectance spectrophotometry. Simultaneously, oxygen tension (pO2) in gingival tissue was monitored with an oxygen microelectrode. Both SO2 and pO2 increased within 10-20 min after stimulation and then slowly returned to the initial level at all treatment sites. The response was most prominent after vibration at attached gingiva. SO2 and pO2 increased by 12% and 42%, respectively, and significant increase continued for 75-85 min. Response after vibration at marginal gingiva was moderate in pO2 and transient in SO2. Pressurization at attached gingiva caused moderate response in SO2, but the increase in pO2 was slight. Control showed little change in both indices. These results suggest that vibration with a toothbrush at attached gingiva may cause a maximal response in improving oxygen sufficiency to gingival tissue.

Analysis of Variance↗
PubMed1996

Prevention of experimental autoimmune myasthenia gravis by a monoclonal antibody to a complementary peptide for the main immunogenic region of the acetylcholine receptors.

We have previously reported that a complementary peptide (denoted RhCA 67-16), encoded by RNA complementary to that of the Torpedo acetylcholine receptor (AChR) main immunogenic region (MIR), AChR residues alpha 61-76, induces polyclonal and monoclonal Ab reactive with Ig against the AChR MIR. RhCA 67-16 vaccination also protected against the development of experimental autoimmune myasthenia gravis (EAMG) in Lewis rats. In the present report, we found that a mAb (denoted TCM 240, IgG1 kappa) against RhCA 67-16 recognized three different idiotypic Ab (mAb 6, mAb 35, and mAb 198), which were previously reported by others to recognize the AChR MIR and to cause EAMG. Based on these results, TCM 240 was tested for prophylactic effects in EAMG. EAMG induced passively by mAb 35 was inhibited by simultaneous injection with TCM 240. The disease severity was inversely paralleled by the ratio of mAb 35 to TCM 240. EAMG induced by immunization with purified native Torpedo AChR was also inhibited by TCM 240, but not a control mAb. The inhibitory effect of TCM 240 on actively induced EAMG occurred without significantly lowering the overall AChR Ab levels, which indicates a limited repertoire of disease-causing Ab in EAMG and perhaps MG. Such findings suggest the existence of an EAMG-associated Id and also support the concept of an MIR. In a more general sense, these results demonstrate that prophylactic and perhaps diagnostic mAb for autoimmune diseases can be produced by immunization with complementary peptides for disease-associated epitopes.

Amino Acid Sequence↗
PubMed1996

Phospholipases involved in lysophosphatidylinositol metabolism in rat brain.

A phospholipase C activity highly specific for lysophosphoinositide (lysoPI-PLC) has been demonstrated to be present in synaptic plasma membranes of the rat brain. Several lines of evidence suggested that the lysoPI-PLC is an enzyme distinct from known isoforms of phosphoinositide-specific phospholipase C (PI-PLC). On the other hand, the occurrence of a Ca(2+)-independent phospholipase A1 hydrolyzing PI in rat brain was also demonstrated. The lysoPI-PLC hydrolyzed the 2-acyl isomer as well as the 1-acyl isomer of lysoPI. These findings suggest possible pathways for PI metabolism through lysoPI to yield monoacylglycerol (mainly 2-arachidonoyl glycerol) and inositolphosphates in the brain, which are different from the well-characterized PI-PLC pathway.

Animals↗
PubMed1996

Portal insulin delivery is superior to peripheral delivery in handling of portally delivered glucose.

It is still controversial as to whether physiological portal insulin delivery has metabolic advantages over peripheral insulin delivery. To clarify this issue, glycemic regulation during intravenous (IVGTT) and oral (OGTT) glucose tolerance tests and hyperglycemic clamp studies with either peripheral or portal glucose infusion was investigated in left-segmentally pancreatectomized dogs with portal ([PPx] n = 7) or systemic ([Tx] n = 7) venous drainage of the remaining pancreas. In Tx dogs, systemic diversion of pancreatic venous effluent was accomplished by gastroduodenal-caval shunt. Data obtained were compared with those in normal control dogs ([NC] n = 7). The loss of pancreatic beta-cell mass in PPx dogs decreased insulin responses to peripheral and portal glucose loads. In contrast, Tx dogs showed insulin responses comparable to those of NC dogs to glucose loads via both routes. Against peripheral glucose loads (IVGTT and hyperglycemic clamp with peripheral glucose infusion), PPx and Tx dogs showed deteriorated glucose handling. Against portal glucose loads (OGTT and hyperglycemic clamp with portal glucose infusion), deteriorated glucose handling was observed in Tx dogs, but not in PPx dogs. Deterioration in glycemic regulation against portal glucose loads in left-segmentally pancreatectomized dogs with peripheral insulin delivery but not in pancreatectomized dogs with portal delivery indicates that intraportal hyperglycemia and hyperinsulinemia are essential for promoting hepatic glucose handling.

Animals↗
PubMed1996

Diurnal heart rate variability in healthy subjects: effects of aging and sex difference.

To study the effects of aging and gender, circadian profiles of heart rate variability were evaluated for 105 healthy volunteers by frequency domain analysis of a Holter electrocardiogram record. The low-frequency (LF) component representing cardiac beta-adrenergic function showed high values for the 0800-1200 period in male subjects and the 1200-2400 period in female subjects. The high-frequency (HF) component representing parasympathetic function showed a peak for the 0000-0600 period in both male and female subjects independent of age. Male subjects showed significantly higher %LF [LF/(LF + HF) x 100] than female subjects. LF showed consistently highly significant correlation with age. These basic findings can help elucidate the diurnal profile of cardiac nerve function and how it is affected by aging and sex difference.

Adult↗
PubMed1996

[Survey of allergic diseases in 3-year old children in Okinawa City].

A questionnaire survey was conducted between September 1993 and March 1994 to ascertain the presence of allergic diseases among 3-year old children in Okinawa City of Okinawa Prefecture. Nine hundred and twenty-two questionnaires were sent to caretakers of 3-year old children, with 697 responses of which five invalid cases were deleted for a total of 692 responses which were analyzed. About 30% of these children had allergic diseases as diagnosed by the medical doctor. Among the respondents 15.1% had experience of atopic dermatitis, while 13.9% had experience of asthma. The incidence of atopic dermatitis in this survey was lower than those reported in other prefectures of Japan. Symptoms for atopic dermatitis were more severe during summer. About 15% of the children had been on a diet regimen for prevention or treatment of allergic diseases since the time of conception. Eighteen percent of the respondents used a vacuum cleaner on their bedding. A high proportion of respondents (65.9%) obtained information from newspapers or magazines about allergic diseases.

Asthma↗
PubMed1995

Diabetes mellitus carrying a mutation in the mitochondrial tRNA(Leu(UUR)) gene.

We screened 214 Japanese NIDDM (non-insulin-dependent) diabetic patients with a family history of diabetes for mutations in the mitochondrial tRNA(Leu(UUR)) gene using polymerase chain reaction-restriction fragment length polymorphism and direct sequencing. Six patients were identified as having an A to G transition at position 3243 (3243 mutation), but no patients were detected with a T to C transition at position 3271, in the mitochondrial tRNA(Leu(UUR)) gene. These two mutations were not present in 85 healthy control subjects. It was disclosed that the patients' mothers were also affected by diabetes mellitus in five of the six cases. In these six affected patients, the 3243 mutation shows variable phenotypes, such as the degree of multiple organ involvement, intrafamilial and interfamilial differences in disease characteristics, and the degree of the involvement of MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes) phenotype. Endocrinological examinations revealed that those diabetic patients with the 3243 mutation show not only beta-cell dysfunction, but also a defect in alpha-cell function, which is considered characteristic of diabetes with the 3243 mutation. When compared with 50 selected diabetic control subjects without the 3243 mutation, whose mothers, but not fathers, were found to have diabetes, it was established statistically that those with the 3243 mutation possess the following clinical characteristics; 1) the age of diabetes onset is lower, 2) they have lean body constitutions, and 3) they are more likely to be treated with insulin than control subjects. We suggest that diabetes with the 3243 mutation possesses phenotypes distinct from those in common forms of diabetes.

Adolescent↗
PubMed1995

Amino acid polymorphisms of the insulin receptor substrate-1 in Japanese noninsulin-dependent diabetes mellitus.

By using polymerase chain reaction-restriction length polymorphism and polymerase chain reaction-single-strand conformation polymorphism analysis, we screened 283 Japanese subjects [226 noninsulin-dependent diabetes mellitus (NIDDM), 12 impaired glucose tolerance, and 45 normal controls] for 2 amino acid polymorphisms, Ala513Pro and Gly972Arg, of the insulin receptor substrate-1. Only 8 NIDDM, 1 impaired glucose tolerance, and 1 normal subject were identified to be heterozygous for the Gly972Arg mutation, whereas no subject had an Ala513Pro polymorphism. The frequency of Gly972Arg was lower than recently reported in Danish and Finnish populations and was in good agreement with that previously reported in another Japanese cohort. Analysis of 1 pedigree of 1 NIDDM patient with a Gly972Arg showed no co-segregation between this polymorphism and the onset of NIDDM. Our results suggest that the Gly972Arg polymorphism does not play an important role in the pathogenesis of NIDDM in Japanese patients.

Adolescent↗
PubMed1995

Cloning and nucleotide sequence of the inulin fructotransferase (DFA I-producing) gene of Arthrobacter globiformis S14-3.

A gene encoding an inulin fructotransferase (DFA I-producing) [EC 2.4.1.200] from Arthrobacter globiformis S14-3 was cloned and the nucleotides sequenced, for the first time. The sequence indicated that the native enzyme protein is composed of 392 amino acid residues. The native enzyme is an extracellar enzyme produced in the culture supernatant of A. globiformis S14-3, but the nucleotide sequence of the gene lacks a sequence for signal peptide for secretion. The 1.5-kb DNA fragment encoding the gene was found to produce the active enzyme in the culture supernatant of an E. coli clone, under the control of the lac promoter of pUC119.

Amino Acid Sequence↗
PubMed1995

A case of non-insulin dependent diabetes mellitus with antiinsulin antibody: effect of subcutaneous injection of human recombinant insulin-like growth factor-I.

We saw a 57-yr-old female non-insulin dependent diabetes mellitus (NIDDM) patient with antiinsulin antibody, in whom insulin-like growth factor-I (IGF-I) was shown to be effective as a blood glucose-lowering agent. Due to the presence of the antibody, the patient suffered from postprandial hyperglycemia and frequent hypoglycemia, which were uncontrollable even by multiple insulin injection therapy. In contrast to insulin injection (0.24 IU/kg body wt) which showed a delayed glucose-lowering effect, subcutaneous injection of recombinant human IGF-I (0.05-0.1 mg/kg body wt) caused a quick fall in plasma glucose levels. Prolongation of the glucose-lowering effect of "rapid-acting" insulin frequently caused subsequent hypoglycemia in this patient, but the effect of IGF-I seemed to have disappeared within the first three hours.

Diabetes Mellitus, Type 2↗
PubMed1995

1,5-Anhydro-D-glucitol evaluates daily glycemic excursions in well-controlled NIDDM.

OBJECTIVE: To evaluate the usefulness of plasma 1,5-anhydro-D-glucitol (1,5-AG) as a possible marker for daily glycemic excursion, we measured plasma 1,5-AG, HbA1c, fasting plasma glucose (FPG) level, and daily excursion of glycemia, from which the M-value (after Schlichtkrull) was calculated as an index of daily glycemic excursion. RESEARCH DESIGN AND METHODS: The subjects were 76 patients with well-controlled non-insulin-dependent diabetes mellitus (NIDDM) treated with diet therapy only (diet, n = 17), oral hypoglycemic agents (OHA, n = 28), conventional insulin therapy (CIT, n = 16), or multiple insulin injection therapy (MIT, n = 15). RESULTS: HbA1c values were similar among all the groups (diet, 6.9 +/- 0.6; OHA, 7.2 +/- 0.5; CIT, 7.1 +/- 0.6; MIT, 7.2 +/- 0.5%). The MIT group showed a significantly higher 1,5-AG concentration (11.5 +/- 5.3 micrograms/ml), a significantly lower M-value (9.2 +/- 5.2), and little risk of hypoglycemia ( < 4 mmol/l) and hyperglycemia ( > 10 mmol/l) (1.3 +/- 1.1 times/24 h) compared with the CIT group (6.9 +/- 3.3 micrograms/ml, 15.7 +/- 8.9, 2.2 +/- 1.6 times/24 h, respectively). Insulin doses (22.4 +/- 4.5 vs. 22.0 +/- 8.9 U/day), FPG (6.6 +/- 2.2 vs. 7.4 +/- 2.4 mmol/l), and HbA1c concentrations were not significantly different between the CIT and MIT groups. M-values significantly correlated with 1,5-AG concentrations (r = 0.414, P < 0.05), but not with HbA1c concentrations. CONCLUSIONS: The findings suggest that the plasma 1,5-AG concentration can be a useful index of the daily excursion of blood glucose, especially in patients with well-controlled NIDDM.

Biomarkers↗
PubMed1995

The CD5+ B cells and myasthenia gravis.

A high frequency of CD5+ B lymphocytes in the peripheral blood of patients with myasthenia gravis (MG) has been reported recently. These results seem to indicate an attractive linkage between CD5+ B lymphocytes and autoantibodies against Acetylcholine receptor in MG. We examined the frequency of CD5+ B cells in 20 patients with MG and 21 normal healthy controls by two-color flow cytometry. However, there were no significant differences in the percentages of CD5+ B lymphocytes between the two groups. We also examined the frequency of CD5+ B lymphocytes in the resected thymus of patients. The frequency of CD5+ B lymphocytes in the thymus was low and similar pattern to that in the peripheral blood. We checked the antibody (Ab) production against the human acetylcholine receptor in either CD5+ B or CD5- B lymphocytes using B lymphoblastoid cell line generated from the lymphocytes of 11 patients with anti-AChR Abs in the sera. Abs against the AChR in the human were mostly produced by CD5- B, not CD5+ B lymphocytes. The anti-AChR Abs (IgG) production of CD5+ B cells and CD5- B cells (mean +/- SD) were 6.8 +/- 2.4 fmol/ml and 18.5 +/- 17.6 fmol/ml, respectively. These results suggest that in MG, the frequencies of the CD5+ B lymphocytes in PBL may be genetic background and that there may be no strong linages between AChR Ab production and CD5+ B lymphocytes.

Adult↗
PubMed1995

Bassiatin, a new platelet aggregation inhibitor produced by Beauveria bassiana K-717.

A new platelet aggregation inhibitor, bassiatin, was isolated from the cultured broth of Beauveria bassiana which had been isolated from a soil sample collected in Yunnan province, China. The structure of bassiatin was determined to be (3S, 6R)-4-methyl-6-(1-methylethyl)-3-phenylmethyl-1, 4-perhydrooxazine-2,5-dione by NMR analysis, X-ray crystallographic analysis and chemical synthesis. Bassiatin inhibited ADP-induced aggregation of rabbit platelets with the IC50 being 1.9 x 10(-4) M.

Animals↗