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Biomedical subjects

M Nakazato

Publications and source records attributed to M Nakazato.

At least 145 records · Page 8Linked to original sources
PubMed1993

Alpha (1,3/1,4)fucosyltransferase (FucT-III) gene is inactivated by a single amino acid substitution in Lewis histo-blood type negative individuals.

Human alpha (1,3/1,4)fucosyltransferase (FucT-III) genes were cloned from genomic DNAs of seven Lewis negative (Le(a- b-)) individuals. Restriction mapping analyses revealed that an additional Pvu II site was created in the FucT-III genes from Lewis negative individuals. Four of these individuals were shown to be heterozygous for the Pvu II site and three were homozygous for it. The Pvu II site was produced by a single base substitution at the 508 nucleotide of coding sequence, G to A, resulting in the amino acid substitution, Gly to Ser at position 170. Another single base substitution, resulting in the change of Asp to Ala at position 336, was observed in the Lewis negative FucT-III gene which did not have the Pvu II site. The FucT-III enzyme was inactivated by these two mutations resulting in a single amino acid substitution in the catalytic region. All FucT-III genes, regardless of the Pvu II site, from Lewis negative individuals had a single base substitution, the T at position 59 to G, resulting in the change of Leu to Arg at position 20. This mutation, however, was not responsible for FucT-III gene inactivation.

Amino Acid Sequence↗
PubMed1993

Establishment of radioimmunoassay for human neutrophil peptides and their increases in plasma and neutrophil in infection.

Neutrophil peptide, also called defensin, is an antimicrobial peptide localized in azurophil granules in neutrophils. Using a synthetic human neutrophil peptide-1 (HNP-1), we prepared an antiserum against the peptide and established a highly sensitive radioimmunoassay (RIA). This RIA equally recognized HNP-1, -2, and -3 on a molar basis. Analyses of leukocyte and blood extracts obtained from normal individuals and patients with bacterial infection by reverse-phase high-performance liquid chromatography coupled with the RIA showed that the antiserum specifically detected HNP molecules. Concentrations of HNP 1-3 in total in normal human blood and plasma are 13.2 +/- 1.4 (mean +/- SEM) ng/mu 1 and 403.8 +/- 38.9 pg/mu 1, respectively. The values increased in infection and returned to within the normal levels after the recovery of the disorder. Granulocyte colony-stimulating factor (G-CSF) increased the plasma and blood concentrations of HNP 1-3. The RIA established here provides a useful tool to elucidate the pathophysiological significance of HNP and to evaluate the neutrophil functions in infection and inflammation.

Acute Disease↗
PubMed1993

A basic transthyretin variant (Glu61-->Lys) causes familial amyloidotic polyneuropathy: protein and DNA sequencing and PCR-induced mutation restriction analysis.

A new mutation of transthyretin (TTR) has been identified in a patient with late-onset familial amyloidotic polyneuropathy (FAP) of Japanese origin. Peptide mapping by reverse-phase high performance liquid chromatography to compare the patient's TTR with normal TTR showed the presence of an abnormal peptide. Amino acid sequence analysis of the peptide (residues 49-61) showed a lysine-for-glutamic acid substitution at position 61. This substitution, verified by direct DNA sequencing, was the result of a guanine to adenine change on exon 3 of the TTR gene. A polymerase chain reaction-induced mutation restriction analysis (PCR-IMRA) system was established to rapidly detect the missense mutation. TTR-Lys61 is the first variant TTR with a replacement of the acidic with basic amino acid to be found in the amyloid precursor proteins of FAP.

Aged↗
PubMed1993

Human alpha-1,3 fucosyltransferase (FucT-VI) gene is located at only 13 kb 3' to the Lewis type fucosyltransferase (FucT-III) gene on chromosome 19.

Human alpha-(1.3/1,4) fucosyltransferase (FucT-III) gene and alpha 1,3 fucosyltransferase (FucT-VI) gene were found in the 38-kb fragment isolated from a human cosmid library. These genes were present 13 kb apart in tandem orientation. The FucT-III gene has already been mapped on the Lewis locus of chromosome 19. This demonstrated that FucT-VI gene was localized close to the Lewis locus on chromosome 19.

Base Sequence↗
PubMed1993

Diagnostic radioimmunoassay and DNA-analysis in Swedish and Japanese patients with familial amyloidotic polyneuropathy. Homozygosity for the TTR met30 gene.

Eighteen Swedish patients with familial amyloidotic polyneuropathy were tested for the met30 mutation of the transthyretin (TTR) (prealbumin) gene by RFLP analysis of genomic DNA using the restriction enzyme NsiI. The results confirmed previous findings that the Swedish variant of familial polyneuropathy has the same valine by methionine substitution at position 30, as seen in patients with FAP from Japan, Portugal or patients of Swedish descent from USA. However, two of the patients were homozygous, totally lacking the wild type allele. Measurable serum values for the variant transthyretin (TTR) was detected with a RIA-method in all the 18 Swedish FAP patients studied with a mean concentration of 12.1 +/- 5.1 (SD) mg/100 ml, (11.0 +/- 4.1 when the two homozygotes were excluded). In 45 Japanese patients the mean was 9.2 +/- 2.7 mg/100 ml. The variant TTR was not detected in the healthy controls. The value for the variant TTR was nearly twice that high in the two homozygous patients, 21.14 and 21.16 mg/100 ml, respectively. There was no correlation between the serum levels of variant TTR and the duration of disease or levels of serum albumin in the FAP-patients.

Adolescent↗
PubMed1992

Excessive production of transforming growth-factor beta 1 can play an important role in the development of tumorigenesis by its action for angiogenesis: validity of neutralizing antibodies to block tumor growth.

Angiogenesis is an important part of tumor growth in vivo. We used the transfected Chinese hamster ovary (CHO) cells that overproduced recombinant transforming growth-factor beta 1 (TGF-beta 1) to examine the possible role of this factor in tumor growth and angiogenesis in a nude mouse model. The in-vitro proliferation of TGF-beta 1-transfected CHO cells was unaffected by the treatment of either recombinant TGF-beta 1 or an anti-TGF-beta 1 antibody. The TGF-beta 1-transfected cells grew more rapidly than the parental CHO cells when injected subcutaneously into nude mice. The tumors derived from the TGF-beta 1-transfected cells showed prominent tumor-associated angiogenesis, whereas the parental cells produced tumors without such angiogenesis. In addition, an anti-TGF-beta 1 neutralizing antibody was able to inhibit both growth and angiogenesis in the tumors derived from TGF-beta 1-transfected cells. These findings suggest that the overproduction of TGF-beta 1 by tumor cells can contribute to neovascularization and may help promote tumor development in vivo.

Animals↗
PubMed1992

Establishment of hypersensitive radioimmunoassay for islet amyloid polypeptide using antiserum specific for its N-terminal region.

Using a synthetic N-terminal hexadecapeptide of islet amyloid polypeptide (IAPP), we prepared an antiserum specific for IAPP[1-16] and established an extremely sensitive radioimmunoassay (RIA) for the peptide with a minimum detection level of 0.26 fmol/tube. Since the N-terminal sequence of IAPP is 100% conserved in many mammalian species, the RIA is widely applicable in quantifying their IAPP. Analyses of pancreatic extracts of human and hamster using reverse-phase high performance liquid chromatography coupled with the RIA revealed that almost all pancreatic IAPP consisted of IAPP[1-37]. On the other hand, rat and mouse pancreata contained substantial amounts of IAPP[1-16] and IAPP[1-17] in addition to IAPP[1-37] as a major molecular form. In human plasma, IAPP[1-37] is the major molecular form secreted into the circulation in response to glucose administration. The RIA established in this study is promising in elucidating the physiological functions and the pathophysiological significance of IAPP in diabetes mellitus.

Adult↗
PubMed1992

Identification of a novel transthyretin variant (Val30----Leu) associated with familial amyloidotic polyneuropathy.

A novel variant transthyretin which contains a leucine-for-valine substitution at position 30 was isolated and identified in the serum of a patient with familial amyloidotic polyneuropathy (FAP). The amino acid substitution was proven to result from a guanine-to-cytosine change at the first base of codon 30 located in exon 2 in the mutated transthyretin gene by restriction fragment length analysis on the amplified transthyretin gene using Cfr13 I. The study indicates that the point mutation of the transthyretin gene is a cause of the disorder.

Amino Acid Sequence↗
PubMed1992

Islet amyloid polypeptide plasma concentrations in individuals at increased risk of developing type 2 (non-insulin-dependent) diabetes mellitus.

To study whether abnormal secretion of islet amyloid polypeptide is involved in the development of insulin resistance and impaired insulin secretion in Type 2 (non-insulin-dependent) diabetes mellitus, we measured islet amyloid polypeptide concentrations in 56 first-degree relatives of Type 2 diabetic subjects and in 10 healthy control subjects. Fasting islet amyloid polypeptide concentrations were similar in control subjects, glucose-tolerant and glucose-intolerant relatives (8 +/- 1, 9 +/- 1 and 11 +/- 2 fmol/ml; p = NS). The area under the islet amyloid polypeptide curve measured during an oral glucose load was larger in glucose-intolerant relatives (115 +/- 13 fmol/ml) compared to glucose tolerant relatives and control subjects (88 +/- 3 and 79 +/- 12 fmol/ml; p less than 0.05). The insulin response during the oral glucose load was inversely correlated with the rate of glucose disposal measured during a euglycaemic hyperinsulinaemic clamp (r = -0.725; p less than 0.01), while no significant correlation was observed between the corresponding values for islet amyloid polypeptide and glucose disposal (r = -0.380; p = NS). Hypersecretion of islet amyloid polypeptide is observed in glucose-intolerant first-degree relatives of patients with Type 2 diabetes. Since these patients are characterized by insulin resistance and abnormal first-phase insulin secretion, the putative role of islet amyloid polypeptide in the development of these abnormalities remains to be established. It is however, unlikely that islet amyloid polypeptide is involved in the development of insulin resistance as insulin-resistant relatives with normal glucose-tolerance showed normal islet amyloid polypeptide concentrations.

Adult↗
PubMed1992

Effects of aging on plasma islet amyloid polypeptide basal level and response to oral glucose load.

To delineate the effects of aging on basal and glucose-stimulated secretion of islet amyloid polypeptide (IAPP), we compared the basal level of plasma IAPP and its response to an oral glucose load in elderly subjects with those of young subjects. Plasma IAPP level was determined by radioimmunoassay. Basal level of plasma IAPP in 20 elderly subjects (mean age 63 yr) was 5.3 +/- 0.4 pmol/l, which was not significantly different from 5.0 +/- 0.3 pmol/l in 22 young subjects (mean age 26 yr). Plasma glucose levels after an oral glucose load in elderly subjects (n = 8, mean age 67 yr) and young subjects (n = 8, mean age 29 yr) were within normal limits. However, the plasma glucose response in the aged group was significantly higher than that in the young group. The plasma insulin response to a glucose load in elderly subjects was not different from that in young subjects. The plasma IAPP level in the aged group significantly increased from 5.3 +/- 0.5 to 16.4 +/- 2.3 pmol/l 120 min after the oral glucose load. This result was quite similar to that in the young group whose plasma IAPP level increased from 4.9 +/- 0.5 to 14.1 +/- 1.5 pmol/l 120 min after the glucose load. We concluded that the basal level of plasma IAPP and its response to glucose were not affected by aging.

Adult↗
PubMed1992

Islet amyloid polypeptide (IAPP) and pancreatic islet amyloid deposition in diabetic and non-diabetic patients.

Twenty pancreata of non-diabetic patients and 17 pancreata of diabetic patients, including two patients with insulin-dependent diabetes mellitus, were immunohistochemically studied using antiserum against human islet amyloid polypeptide (IAPP). The islet beta cells in non-diabetic patients were immunoreactive for both IAPP and insulin. Amyloid deposition immunoreactive for IAPP was detected in six of 20 pancreata of non-diabetic patients. The plasma glucose level of three of these six patients was elevated to more than 200 mg/dl, and that of the other three ranged from 143 to 162 mg/dl; all six were receiving intravenous hyper-alimentation and had no history of diabetes prior to treatment. Amyloid deposition was present in all patients with non-insulin-dependent diabetes mellitus (NIDDM). The deposition was absent in the pancreata of two secondary diabetic patients, one of whom had received steroid hormone for bronchial asthma and the other of whom had liver cirrhosis with hepatocellular carcinoma; deposition was also absent in the pancreas of a patient with impaired glucose tolerance diagnosed on a 75-g oral glucose load. Heterogeneous expression of immunoreactivities of beta cells for insulin and for IAPP was present, suggesting independently regulated production and secretion of the peptides. Immunoreactivity of beta cells was more sensitively decreased for IAPP than for insulin in the islets of NIDDM patients. The decreased immunoreactivity for IAPP suggested an initial stage of disturbed beta-cell function, even if the immunoreactivity for insulin was apparently intact or the amyloid deposition in the islets was insignificant. The degree of amyloid deposition immunoreactivity for IAPP did not necessarily reflect the severity of diabetes mellitus. Amyloid deposits were seen at the narrow spaces beneath the insular capsule of connective tissues and the perivascular region or, in some cases, occupying the whole of the islet. The diabetogenic role of IAPP is unclear, but the deposition might be an accelerating factor which disturbs beta-cell function.

Adult↗
PubMed1992

Molecular forms of islet amyloid polypeptide (IAPP/amylin) in four mammals.

Using reverse-phase high performance liquid chromatography combined with radioimmunoassays for human and rat/mouse islet amyloid polypeptide (IAPP), we identified molecular forms of IAPPs in pancreata of four mammals including species in which islet amyloid deposition occurs (human and cat) and those in which amyloid deposition does not occur (rat and mouse). In human pancreas, IAPP (1-37) was the major molecular form, and IAPP (17-37), IAPP (24-37) and four IAPP-immunoreactive peptides were detected as minor components. In rat, mouse and cat pancreata, IAPP (1-37) and IAPP (19-37) were identified with the latter being the major molecular form. Major processing takes place at a single arginine residue at position 18 of rat/mouse and cat IAPPs, but not at the histidine at position 18 of human IAPP, indicating that arginine could yield different processing of IAPP between the 3 species and human. Different processing of IAPP by species suggests that processing of IAPP in pancreas is not responsible for islet amyloid formation. Identification of molecular forms of IAPP is helpful in elucidating the physiological function of the IAPP molecule and in determining the type of system regulating biosynthesis and catabolism of the peptide.

Amino Acid Sequence↗
PubMed1992

Plasma islet amyloid polypeptide levels in obesity, impaired glucose tolerance and non-insulin-dependent diabetes mellitus.

We examined the response of plasma islet amyloid polypeptide (IAPP) to an oral glucose load in non-obese and obese subjects with normal glucose tolerance or impaired glucose tolerance (IGT), and in non-obese patients with non-insulin-dependent diabetes mellitus (NIDDM). Plasma IAPP response to intravenous glucagon injection in NIDDM patients was also studied. Plasma IAPP concentration was determined by a sensitive and specific radioimmunoassay. Basal levels of plasma IAPP in non-obese subjects with normal glucose tolerance, IGT and NIDDM were not significantly different from each other. Non-obese subjects with IGT showed delayed and higher plasma IAPP response to oral glucose load compared to normal non-obese subjects. In NIDDM patients, IAPP response to glucose was delayed and lower when compared to normal non-obese subjects. Basal levels of plasma IAPP in normal obese subjects and obese subjects with IGT were significantly higher than those in normal non-obese subjects. Plasma IAPP response to glucose load in these obese subjects was higher than that in normal non-obese subjects. Plasma IAPP response was decreased in diabetic patients treated with diet, oral hypoglycemic agents and insulin in that order. We conclude that the secretion of IAPP is reduced with progression of NIDDM, although it appears to be rather augmented in IGT compared to normal non-obese subjects.

Adult↗
PubMed1992

Asymptomatic homozygous gene carrier in a family with type I familial amyloid polyneuropathy.

Type I familial amyloid polyneuropathy (FAP) is a molecular disorder with a mutation of the transthyretin (TTR) gene, and most patients previously examined were reported to be heterozygous for this mutant gene. In the present study a rapid and easy DNA diagnostic method employing the polymerase chain reaction revealed an asymptomatic homozygous TTR gene carrier in a Japanese family with type I FAP. The level of the variant TTR (methionine instead of valine at position 30) in his serum was much higher than that usually found in type I FAP patients. However, the histological findings of the biopsied rectum and abdominal fat tissues failed to demonstrate amyloid deposits, and the autonomic nerves from his rectal mucosa were normally preserved. Moreover, his 72-year-old mother (a TTR gene heterozygote) was supposed to start amyloid deposition in her late sixties. It is suggested that in addition to the mutant TTR gene some other factors control the development of the disease.

Aged↗
PubMed1992

Homozygosity for the transthyretin-Met30 gene in three Japanese siblings with type I familial amyloidotic polyneuropathy.

We report the cases of three siblings homozygous for a mutated transthyretin (TTR) gene that causes type I familial amyloidotic polyneuropathy (FAP), in whom we made the diagnosis by identifying both the mutated TTR gene and a variant TTR in their sera. Their serum levels for the variant TTR are twice those of patients heterozygous for the gene, but two have late-onset FAP and the third is an elderly asymptomatic carrier. TTR abnormality is a necessary condition for the development of FAP, but there may be other factors that retard or prevent its clinical development.

Aged↗