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Biomedical subjects

M Miyazato

Publications and source records attributed to M Miyazato.

32 records · Page 2Linked to original sources
PubMed1995

Two novel rat guanylin molecules, guanylin-94 and guanylin-16, do not increase cyclic GMP production in T84 cells.

Guanylin, a 15-amino acid peptide homologue of bacterial heat-stable enterotoxins, is an endogenous activator of guanylate cyclase C (GC-C). We isolated two novel guanylin molecules from rat intestinal mucosa. They contained guanylin-15 at their C-termini and were identified as guanylin-94 and guanylin-16 by amino acid sequencing and mass spectrometry. Guanylin-94 and guanylin-16 in total account for 85% of guanylin molecules in both the small and large intestine, guanylin-15 being a minor component. Rat guanylin-94 and guanylin-16 did not increase cyclic GMP production in T84 cells. Identification of the post-translational processing products of guanylin should provide a better understanding of the biosynthesis of the peptide.

1-Methyl-3-isobutylxanthine↗
PubMed1994

Isolation and sequence determination of two N-terminal fragments of islet amyloid polypeptide in rat pancreas.

Using a highly sensitive and specific radioimmunoassay (RIA) for the N-terminal hexadecapeptide of islet amyloid polypeptide (IAPP), we isolated two N-terminal fragments of IAPP from rat pancreas. They were identified as IAPP(1-16) and IAPP(1-17) by amino acid sequencing. The two fragments were also found in rat plasma. IAPP(1-37) was the major molecular form of rat IAPP, IAPP(1-16) and IAPP(1-17) accounting for 6.0% and 32.3% of the immunoreactivity for the N-terminal region of the peptide in pancreata of normally fed rats. In human pancreas, the N-terminal fragments of IAPP were not present, indicating that the processing of IAPP in the pancreas differs between human and rat. Food deprivation increased the molar ratios of IAPP(1-16) and IAPP(1-17) to IAPP(1-37) in comparison to values for fed rats. Identification of novel fragments of IAPP, in addition to IAPP(1-37), offers a promise for the elucidation of the physiological function of IAPP and the identification of factors that regulate the biosynthesis and catabolism of the peptide.

Amino Acid Sequence↗
PubMed1992

Kaposi sarcoma in Okinawa.

BACKGROUND: The authors encountered six patients with Kaposi sarcoma in Okinawa; one was classic type, two were associated with adult T-cell leukemia (ATL), one was with multiple myeloma, and two were with acquired immune deficiency syndrome (AIDS). In the classic type, many nodular lesions were seen on the skin of the extremities and a few on the trunk, some of which were ulcerated. Most lesions regressed in 1.5 years. In four other patients (three without AIDS and one with AIDS), many plaques and a few nodular lesions were seen on the trunk, face, and extremities. The other patient with AIDS showed Kaposi sarcoma only in the lymph nodes and perineural tissues in the abdomen. METHODS: Immunohistochemical and lectin histochemical studies were done on deparaffinized sections and on cells cultured from small pieces of tumor mass from the classic type Kaposi sarcoma. Isolation of viruses from tumor tissue was also attempted. RESULTS: Large numbers of endothelial cells lining irregular vascular spaces, and some spindle cells showed positive reactions for Factor VIII-related antigen, Ulex europaeus 1 (UEA-1) (E.Y. Labs, Inc., San Mateo, CA), Griffonia simplicifolia (GS-1) (E.Y. Labs, Inc.) lectins, and epidermal growth factor (EGF) receptor antigen. Cytomegalovirus (CMV), hepatitis B, herpes simplex virus (HSV) 1 and 2, papillomavirus antigens, and human immunodeficiency virus (HIV) p24 core antigen were not seen in any patients, except in the patient with AIDS in whom CMV was demonstrated in tissues adjacent to the tumor (Patient 6). In cell culture, elongated spindle cells proliferated in plate and also in three-dimensional cultures. The cells were positive immunohistochemically for Factor VIII-related antigen and EGF receptor. They also stained lectin histochemically with UEA-1 and GS-1. Tube formations were demonstrated by electron microscopic study. CONCLUSIONS: Six cases of Kaposi sarcoma have been diagnosed within a short time span where this condition has previously been said to be rare. The studies suggest a vascular endothelial cell origin and growth factor regulated growth for this tumor.

Adult↗
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

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

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

Type I familial amyloidotic polyneuropathy in Japan.

We studied 107 cases and 64 carriers of type I familial amyloidotic polyneuropathy (FAP) residing in 16 districts in Japan. The age of onset of illness ranged from 20 to 71 years old, with a mean of 40.1 +/- 12.8 years (SD). One quarter of the cases were late-onset patients who developed the disorder after age 50. Asymptomatic carriers older than age 50 accounted for 20% of total carriers, with the oldest carrier being a 94-year-old woman. All the patients had a variant transthyretin with a methionine-for-valine substitution at position 30 with a mean serum level of 9.78 +/- 3.27 (SD) mg/dl. The serum level did not significantly differ by gender in either patients or carriers, nor between patients and carriers. Incomplete penetrance of clinical expression was shown in eight cases. This study indicates that there is a considerable variety in age of onset, progression and geographic distribution of type I FAP in Japan.

Adult↗
PubMed1991

Identification and characterization of islet amyloid polypeptide in mammalian gastrointestinal tract.

We identified and determined the content and molecular form of islet amyloid polypeptide (IAPP/amylin) in the gastrointestinal (GI) tract of human, rat, mouse and cat. IAPP was isolated by anti- IAPP- IgG immunoaffinity chromatography and reverse-phase high performance liquid chromatography coupled with radioimmunoassays for human and rat/mouse IAPPs. Human IAPP [1-37], [17-37] and [24-37] were identified in human stomach with IAPP [1-37] being the major molecular form. In the GI tract of rat, mouse and cat, IAPP [1-37] and IAPP [19-37] were identified with the latter being the major molecular form. IAPP is present from stomach to colon with the highest concentration being observed in pyloric antrum of stomach. IAPP content in rat antrum fell to 69% of control after 4 days of fasting, with the molar ratio of IAPP [19-37] to IAPP [1-37] increasing from 1.4 in controls to 2.9 in fasted rats. Identification of IAPP and characteristic morphology of IAPP- cells in the GI tract indicate a possible biological function of IAPP as a gastrointestinal peptide.

Aged↗
PubMed1991

Acute ascending necrotizing myelitis in Okinawa caused by herpes simplex virus type 2.

A case of rapidly progressing ascending myelitis was necropsied. Necrosis was present throughout the whole length of the spinal cord and involved both the grey and white matter randomly. The perivascular lymphocytic infiltration in the spinal cord in the present case was more pronounced than that in the previously reported two cases of necrotizing myelopathy associated with malignancy. Using immunoperoxidase staining the presence of herpes simplex virus type 2 (HSV 2) antigen was demonstrated. Electron microscopic examinations revealed large numbers of HSV particles in the spinal cord. HSV 2 may be a common aetiological agent of necrotizing myelopathy and myelitis in Okinawa, an HSV 2 endemic area. In the present case, the necrosis was mainly found in the spinal cord but was also observed, to a very limited extent, in the brain.

Acute Disease↗
PubMed1991

Growth characteristics of retinal capillary endothelial cells compared with pulmonary vein endothelial cells in culture. The effect of pericytes on differentiation of endothelial cells.

Bovine retinal capillary endothelial cells (RCECs) and pulmonary vein endothelial cells (PVECs) were isolated and investigated in plate culture, three-dimensional culture and in co-culture with pericytes. In plate culture, RCECs required growth factor in the medium for growth whereas PVECs did not. Phenotypic modulation (a tendency to become similar morphologically to smooth muscle cells, and to accumulate into thread-like structures) was observed in PVECs but not in RCECs. In three-dimensional culture, RCECs contracted, aggregated and were unable to proliferate. Proliferation was elicited when the gel matrix was adsorbed by fibronectin or upon co-culture with pericytes. In contrast, PVECs not only proliferated but also formed tubular structures. In co-culture with pericytes, PVECs in close contact with, or in near apposition to pericytes formed tubular structures earlier than those without contact in the same dish. These results provide new findings about differences in the growth characteristics of endothelial cells between microvessels and large vessels. In addition, it is considered that pericytes may promote tube formation by endothelial cells in three-dimensional culture.

Actins↗
PubMed1990

Isolation and identification of islet amyloid polypeptide in normal human pancreas.

To identify islet amyloid polypeptide (IAPP) present in normal human pancreas, we isolated the peptide from a soluble peptide fraction of amyloid deposit-free pancreata of two non-diabetic patients by using reverse-phase high performance liquid chromatography coupled with a radioimmunoassay specific for human IAPP. IAPP(1-37) and IAPP(17-37) were isolated and their complete amino acid sequences were determined up to the C-terminus. Identification of IAPP in normal human pancreas suggests the possible biological function of IAPP as a novel pancreatic hormone in humans.

Adult↗
PubMed1990

Islet amyloid polypeptide, a novel pancreatic peptide, is a circulating hormone secreted under glucose stimulation.

Islet amyloid polypeptide (IAPP) was identified in human plasma using immunoaffinity chromatography, gel filtration and reverse- phase high performance liquid chromatography coupled with radioimmunoassay specific for the peptide. IAPP[1-37], IAPP[17-37], and other two IAPP- related peptides which were putative pro-IAPPs or different processing products of IAPP, were isolated. All of these IAPPs were also found in human pancreatic extract, indicating that they were secreted from B cell secretory granules into the circulation. IAPP[1-37] is a major molecular form of IAPP in the pancreas, but it accounted for 31% of immunoreactive IAPP in the plasma. Plasma concentration of IAPP in normal individuals increased to 3.0 times the basal level in response to oral administration of 75 g glucose. This study indicated that IAPP is a circulating hormone secreted under glucose stimulation.

Adult↗
PubMed1990

Regional distribution and molecular forms of rat islet amyloid polypeptide.

Using a highly sensitive and specific radioimmunoassay (RIA) for rat islet amyloid polypeptide (IAPP), we clarified regional distribution and molecular forms of rat IAPP. IAPP[1-37] and IAPP[19-37] were identified in normal rat pancreas by sequence analyses IAPP[19-37], accounting for 57% of IAPP-immunoreactivity in rat pancreas, is a major molecular form of rat IAPP moiety. In human, however, IAPP[1-37] is the major component, with IAPP[17-37] composing as little as 2-6% of IAPP-immunoreactivity in pancreas. This indicates that processing of IAPP in pancreas differs in species. A large amount of IAPP (328.5 +/- 25.0 pmol/g wet weight) was found in rat pancreas and the peptide was also detected in pyloric antrum of the stomach, duodenum, jejunum, ileum, and colon at 0.1-0.8% of the level of pancreas. It was not detected in central nervous system. The content of rat IAPP in pancreas fell to 54% of control after 4 day fasting. The distribution of IAPP suggests its possible endocrine or paracrine function in pancreas and gastrointestinal tract.

Amyloid↗