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Biomedical subjects

A Matsuda

Publications and source records attributed to A Matsuda.

At least 379 records · Page 21Linked to original sources
PubMed1988

HLA DR antigens in adult-onset and juvenile-onset Japanese insulin-dependent diabetic patients.

In order to discover the HLA DR antigens linked to Japanese insulin-dependent diabetes (IDDM), and to relate them to the clinical features, HLA DR antigens were examined in 75 IDDM patients including 56 adult-onset cases. Among the tested HLA DR antigens, 4, w9 and w13 were significantly more frequent in IDDM (55%, 47% and 27% respectively). The relative risk was 1.71 for DR4, 2.81 for DRw9 and 4.74 for DRw13. DR2 was significantly less frequent and the relative risk was 0.14. The distribution of DR antigens did not differ between juvenile-onset and adult-onset IDDM, males and females, or cases with and without thyroid autoantibodies. Homozygotes for DRw9 were, but those for DRw13 and DR4 were not more frequent than expected by a random combination. Heterozygotes for DR4 and w9 were less frequent while other heterozygotes for high-risk antigens were as frequent as expected. 97% of IDDM had either DR4, w9 or w13. In conclusion, HLA DR4, w9 and w13 were significantly increased in patients with both juvenile- and adult-onset IDDM. There was no surplus increase in the frequency of IDDM patients with two high-risk HLA DR antigens, more than expected from random combination of each of these DR antigens. Clinical features did not differ among IDDM patients with each of these three antigens.

Adult↗
PubMed1988

5-Fluorocytosine in DNA is a mechanism-based inhibitor of HhaI methylase.

5-Fluorodeoxycytidine (FdCyd) was incorporated into a synthetic DNA polymer containing the GCGC recognition sequence of HhaI methylase to give a polymer with about 80% FdCyd. In the absence of AdoMet, poly(FdC-dG) bound competitively with respect to poly(dG-dC) (Ki = 3 nM). In the presence of AdoMet, the analogue caused a time-dependent, first-order (k = 0.05 min-1) inactivation of the enzyme. There is an ordered mechanism of binding in which enzyme first binds to poly(FdC-dG), then binds to AdoMet, and subsequently forms stable, inactive complexes. The complexes did not dissociate over the course of 3 days and were stable to heat (95 degrees C) in the presence of 1% SDS. Gel filtration of a complex formed with HhaI methylase, poly(FdC-dG), and [methyl-3H] AdoMet gave a peak of radioactivity eluting near the void volume. Digestion of the DNA in the complex resulted in a reduction of the molecular weight to the size of the methylase, and the radioactivity in this peak was shown to be associated with protein. These data indicate that the complexes contain covalently bound HhaI methylase, poly(FdC-dG), and methyl groups and that 5-fluorodeoxycytidine is a mechanism-based inactivator of the methylase. By analogy with other pyrimidine-modifying enzymes and recent studies on the mechanism of HhaI methylase (Wu & Santi, 1987), these results suggest that an enzyme nucleophile attacks FdCyd residues at C-6, activating the 5-position for one-carbon transfer.(ABSTRACT TRUNCATED AT 250 WORDS)

Algorithms↗
PubMed1988

A novel lysine-substituted nucleoside in the first position of the anticodon of minor isoleucine tRNA from Escherichia coli.

A minor species of isoleucine tRNA (tRNA(minor Ile)) specific to the codon AUA has been isolated from Escherichia coli B and a modified nucleoside N+ has been found in the first position of the anticodon (Harada, F., and Nishimura, S. (1974) Biochemistry 13, 300-307). In the present study, tRNA(minor Ile)) was purified from E. coli A19, and nucleoside N+ was prepared, by high-performance liquid chromatography, in an amount (0.6) A260 units) sufficient for the determination of chemical structures. By 400 MHz 1H NMR analysis, nucleoside N+ was found to have a pyrimidine moiety and a lysine moiety, the epsilon amino group of which was involved in the linkage between these two moieties. From the NMR analysis together with mass spectrometry, the structure of nucleoside N+ was determined as 4-amino-2-(N6-lysino)-1-(beta-D-ribofuranosyl)pyrimidinium ("lysidine"), which was confirmed by chemical synthesis. Lysidine is a novel type of modified cytidine with a lysine moiety and has one positive charge. Probably because of such a unique structure, lysidine in the first position of anticodon recognizes adenosine but not guanosine in the third position of codon.

Anticodon↗
PubMed1988

Serum proinsulin levels at fasting and after oral glucose load in patients with type 2 (non-insulin-dependent) diabetes mellitus.

A simple and sensitive human proinsulin radioimmunoassay system was developed using guinea pig anti-proinsulin serum, which cross-reacted neither with human insulin nor C-peptide. The recognition site of the antiserum seems to be located near the junction between the B chain and C-peptide. With this assay system, we studied the serum proinsulin concentration at fasting and after an oral 100 g glucose load in 25 healthy subjects, 21 subjects with impaired glucose tolerance and 40 patients with Type 2 (non-insulin-dependent) diabetes mellitus. At fasting, serum proinsulin was 5.8 +/- 3.3 pmol/l in normal subjects as compared to 9.5 +/- 6.9 pmol/l (p less than 0.05) in subjects with impaired glucose tolerance and 12.6 +/- 7.5 pmol/l (p less than 0.001) in diabetic patients. The molar ratio of proinsulin to insulin was also increased in subjects with impaired glucose tolerance or diabetes compared to control subjects. After a 100 g oral glucose load, serum proinsulin increased more slowly than insulin. The proinsulin response after an oral glucose load was augmented in subjects with impaired glucose tolerance and diabetes, while the insulin response decreased with the elevation of fasting plasma glucose. Diabetic patients with high fasting plasma glucose had a very poor insulin response, but the proinsulin response was similar to control subjects. There was a linear correlation between summed proinsulin values and summed insulin values, but the slope of the regression line was steeper in diabetic patients than in control subjects. There was a relative increase in serum proinsulin both in subjects with impaired glucose tolerance and diabetic patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Reduction in urine C-peptide clearance rate after metabolic control in NIDDM patients.

One hour urine C-peptide and creatinine clearance rates were determined simultaneously in 25 hospitalized patients with non-insulin-dependent diabetes mellitus (NIDDM) undergoing sulfonylurea and/or diet treatment. The studies had been performed after an overnight fast on the second day of admission and on a day soon before discharge, with intervals of 18.9 +/- 7.0 days. Fasting plasma glucose (FPG) and hemoglobin A1c (HbA1c) values decreased significantly at the second examination as compared to the initial values (FPG: 101 +/- 20 mg/dl vs. 161 +/- 47 mg/dl, p less than 0.005; HbA1c: 7.3 +/- 1.5% vs. 8.4 +/- 1.7%, p less than 0.005). The urine C-peptide clearance rate also decreased significantly after metabolic control (0.75 +/- 0.36 l/hr vs. 1.06 +/- 0.54 l/hr, p less than 0.005). Meanwhile, the urine creatinine clearance rate tended to decrease, but the difference was not significant (3.69 +/- 2.04 l/hr vs. 4.87 +/- 2.98 l/hr) at the second examination. The data suggest that the urine C-peptide clearance rate is susceptible to the effects of the fluctuation of metabolic states in NIDDM patients. In order to use urinary C-peptide for a follow up study of pancreatic B-cell secretion, the changes in C-peptide clearance under various metabolic conditions must be taken into account.

Adult↗
PubMed1988

Identification of nucleotide substitution in gene encoding [LeuA3]insulin in third Japanese family.

We previously described a new case of abnormal insulinemia in Japan. In one allele, nucleotide-sequence analysis revealed a substitution in the codon for the third position of insulin A chain (GTG----TTG), causing [LeuA3]insulin. This point mutation is the same as that found in insulin Wakayama. In this family, the mutant insulin allele cosegregated with an 850-base pair PvuII allele of the hypervariable region 5'-flanking the insulin gene.

Base Sequence↗
PubMed1988

Metabolic effects of 3'-deoxyadenosine (cordycepin) and 2-halo-3'-deoxyadenosine on repair of X-ray-induced potentially lethal damage in Chinese hamster V79 cells.

Using cultured Chinese hamster V79 cells, an attempt has been made to examine the phosphorylation of cordycepin and its 2-halo derivatives (2-chloro-3'-deoxyadenosine, 2-bromo-3'-deoxyadenosine, and 2-iodo-3'-deoxyadenosine) by adenosine kinase, within the cells, and to correlate it with their cytotoxicities and abilities to inhibit the repair of X-ray-induced potentially lethal damage (PLDR). Of all compounds, only cordycepin was found to be phosphorylated and showed both potent cytotoxicity and ability to inhibit PLDR.

2-Chloroadenosine↗