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Biomedical subjects

Y Horikawa

Publications and source records attributed to Y Horikawa.

At least 55 records · Page 3Linked to original sources
PubMed2000

beta-cell transcription factors and diabetes: no evidence for diabetes-associated mutations in the gene encoding the basic helix-loop-helix transcription factor neurogenic differentiation 4 (NEUROD4) in Japanese patients with MODY.

The basic helix-loop-helix (bHLH) family of transcription factors plays an important role in the normal development and function of the endocrine pancreas. Heterozygous mutations in the gene encoding one member of this family, NeuroD1/BETA2, are associated with a monogenic form of diabetes that resembles maturity-onset diabetes of the young (MODY) in many respects. This result prompted us to screen the genes encoding related bHLH transcription factors that are also expressed in pancreatic islets for diabetes-associated mutations. We have screened 57 unrelated Japanese subjects with a clinical diagnosis of MODY for mutations in the NeuroD4/Math-3/ATH-3 gene (NEUROD4). This analysis revealed seven frequent polymorphisms that were not associated with MODY, including five in the 5'-untranslated region (UTR) (-477G/A, -436delA, -324delT, -107insTTTT, and -104T/C [cDNA sequences]) and two in the 3'-UTR (1027C/T and 1076C/A). A missense mutation, K68T (203A/C), was found in a heterozygous state in one MODY subject and two nondiabetic subjects. The results of our study suggest that genetic variation in NEUROD4 is not a common cause of MODY in Japanese.

Basic Helix-Loop-Helix Proteins↗
PubMed2000

Beta-cell transcription factors and diabetes: no evidence for diabetes-associated mutations in the hepatocyte nuclear factor-3beta gene (HNF3B) in Japanese patients with maturity-onset diabetes of the young.

Mutations in the transcription factors hepatocyte nuclear factor (HNF)-4alpha and -1alpha, insulin promoter factor-1, and HNF-1beta are the causes of four forms of maturity-onset diabetes of the young (MODY1 and 3-5, respectively). The winged-helix transcription factor HNF-3beta has been implicated in the regulation of expression of each of these MODY genes, suggesting that mutations in the HNF-3beta gene (HNF3B) may also cause MODY. We have tested this hypothesis by screening a panel of 57 unrelated Japanese subjects with a clinical diagnosis of MODY for mutations in HNF3B. This analysis revealed four frequent polymorphisms that were not associated with MODY, including one in the promoter region (-213A/G), two silent mutations in the codons for Ala 97 (291C/T) and Gly 279 (837A/G), and one in the 3'-untranslated region (1424C/T). Two rare substitutions in the 5'-untranslated region, -156C/T and -67A/C, were found in a heterozygous state in two subjects, and two subjects were heterozygous for putative missense mutations, S109N (326G > A) and A328V (983C>T). The two missense mutations were not found in 106 normal chromosomes from nondiabetic subjects. It was not possible to test for co-segregation of these mutations with diabetes and thus, it is unclear whether or not these mutations can cause MODY. The results of our study suggest that mutations in HNF3B are not a common cause of MODY in Japanese subjects.

Adult↗
PubMed2000

Genetic variation in the hepatocyte nuclear factor-3beta gene (HNF3B) does not contribute to maturity-onset diabetes of the young in French Caucasians.

Mutations in genes encoding hepatocyte nuclear factor (HNF) are responsible for three of the five subtypes of maturity-onset diabetes of the young (MODY). This observation and molecular studies indicate that the HNF network is required for normal function of pancreatic beta-cells. This suggests that transcription factors involved in this complex network are candidates for genetic defects in MODY. Because the HNF-3beta gene is implicated in this network, we screened it for mutations in 21 probands of French ancestry with clinical diagnosis of MODY and early-onset type 2 diabetes. All of the five known MODY genes, HNF-4alpha, glucokinase, HNF-1alpha, HNF-1beta, and IPF1, were previously excluded as being the cause of diabetes in these families. By direct sequencing, we identified two transitions, an A-to-G at position -213 and a C-to-T at position -63 in the promoter and exon 1, respectively, of the HNF-3beta gene. A G-to-C transversion at position +32 in the intron 1 and three transitions, C-to-T at position 291, A-to-G at position 837, and G-to-A at position 1188 in the exon 3, resulting in noncoding mutations Ala97Ala, Gly279Gly, and Gln396Gln, respectively, were also identified. The allele frequencies were not significantly different between a control group and MODY probands. Familial segregation studies and linkage analysis showed that genetic variation in the HNF-3beta gene is unlikely to be the cause of early-onset type 2 diabetes in these Caucasian families.

Adult↗
PubMed2000

Mutations in the genes for hepatocyte nuclear factor (HNF)-1alpha, -4alpha, -1beta, and -3beta; the dimerization cofactor of HNF-1; and insulin promoter factor 1 are not common causes of early-onset type 2 diabetes in Pima Indians.

OBJECTIVE: Maturity-onset diabetes of the young (MODY) is a genetically heterogeneous subtype of type 2 diabetes characterized by an early age at onset and autosomal dominant inheritance. MODY can result from heterozygous mutations in at least five genes. The purpose of this study was to determine whether alterations in known MODY genes and two MODY candidate genes contribute to the development of early-onset type 2 diabetes in Pima Indians. RESEARCH DESIGN AND METHODS: The coding regions of the known MODY genes hepatocyte nuclear factor (HNF)-1alpha, HNF-4alpha, HNF-1beta, and insulin promoter factor 1 and the coding regions of two MODY candidate genes, HNF-3beta and the dimerization cofactor of HNF-1, were sequenced in genomic DNA from Pima Indians. The primary "affected" study population consisted of 46 Pima Indians whose age at onset of type 2 diabetes was < or =20 years. DNA sequence variants identified in the affected group were then analyzed in a group of 80 "unaffected" Pima Indians who were at least 40 years old and had normal glucose tolerance. RESULTS: A total of 11 polymorphisms were detected in these genes. However, none of the polymorphisms differed in frequency among Pima Indians with an early age at onset of diabetes compared with older Pima Indians with normal glucose tolerance. CONCLUSIONS: Mutations in these known MODY or MODY candidate genes are not a common cause of early-onset diabetes in Pima Indians.

Adolescent↗
PubMed1999

Distinctions between microglial cells and peripheral macrophages with regard to adhesive activities and morphology.

Activated microglial cells and peripheral macrophages are hardly distinguishable from the viewpoints of morphology and function. There are various immunological markers common to both microglial cells and peripheral macrophages. In the present study, however, we found that microglial cells have distinct characters in terms of adhesion and morphology. By using a "rheoscope," that is an apparatus to rheologically measure the strength of cell adhesion to substrates, rat microglial cells were found to attach to polystyrene dishes much more weakly than alveolar and peritoneal macrophages. Interferon-gamma (IFNgamma) strengthened the adhesion of alveolar and peritoneal macrophages, whereas it weakened that of microglial cells. Morphological changes of microglial cells induced by IFNgamma were also different from those of peripheral macrophages. Furthermore, alveolar and peritoneal macrophages produced NO in response to IFNgamma, while microglial cells did not. When cultured on astrocyte-derived extracellular matrix (AsECM) in serum-free medium, only microglial cells extended multiple ramified processes. Conversely, alveolar and peritoneal macrophages on AsECM shrunk their ruffling membrane and rounded up. These distinctions between microglial cells and macrophages may reflect differences in cell lineages as well as environments in which individual cells reside.

Animals↗
PubMed1999

Three new mutations in the hepatocyte nuclear factor-1alpha gene in Japanese subjects with diabetes mellitus: clinical features and functional characterization.

AIMS/HYPOTHESIS: Mutations in the hepatocyte nuclear factor-1alpha gene are a common cause of the type 3 form of maturity-onset diabetes of the young. We examined the clinical features and molecular basis of hepatocyte nuclear factor-1alpha (HNF-1alpha) diabetes. METHODS: Thirty-seven Japanese subjects with early onset Type II (non-insulin-dependent) diabetes mellitus and 45 with Type I (insulin-dependent) diabetes mellitus were screened for mutations in this gene. Functional properties of mutant HNF-1alpha were also investigated. RESULTS: Three new mutations [G415R, R272C and A site of the promoter (+ 102G-to-C)] were found. Insulin secretion was impaired in the three subjects. Insulin and glucagon secretory responses to arginine in the subject with the R272C mutation were also diminished. Molecular biological studies indicated that the G415R mutation generated a protein with about 50% of the activity of wild-type HNF-1alpha. The R272C mutation had no transactivating or DNA binding activity and acted in a dominant negative manner. The + 102 G-to-C mutation in the A site of the promoter activity was associated with an increase in promoter activity and it had 42-75% more activity than the wild-type sequence. CONCLUSION/INTERPRETATION: Mutations in the HNF-1alpha gene may affect the normal islet function by different molecular mechanisms.

Adult↗
PubMed1999

Risk factors for the progression of microalbuminuria in Japanese type 2 diabetic patients--a 10 year follow-up study.

To clarify risk factors for the progression of microalbuminuria in Japanese type 2 diabetic patients, the longitudinal study for 10 years was conducted on 67 outpatients with type 2 diabetes, who had shown no overt proteinuria at baseline. The urinary albumin index (UAI) has been determined based on the mean of at least two random urine samples each year. Categories were defined as normoalbuminuria (UAI < 30.0 mg/g x Cr.), microalbuminuria (30.0 < or = UAI < 300.0), and macroalbuminuria (UAI > or = 300.0). Progression was defined as worsening of the category and/or more than doubling of the baseline UAI value. Multiple logistic regression analysis was performed using age, duration of diabetes, HbA1c, blood pressure, BMI, serum lipids, smoking habits, and alcohol consumption as independent variables and the progression of microalbuminuria as a dependent variable. Age and HbA1c were estimated as significant and independent variables. Furthermore, genetic polymorphisms of angiotensin I-converting enzyme (ACE) and angiotensinogen were analyzed to evaluate the genetic contribution. The D/D genotype of ACE was significantly more common in progressors than in non-progressors. These results suggest that glycemic control and age are important risk factors and the D/D genotype of ACE acts as a risk factor for the progression of microalbuminuria in Japanese type 2 diabetic patients.

Adult↗
PubMed1999

Widespread occurrence of alpha-synuclein/NACP-immunoreactive neuronal inclusions in juvenile and adult-onset Hallervorden-Spatz disease with Lewy bodies.

Alpha-Synuclein (originally called precursor of the non-Abeta component of Alzheimer's disease amyloid-NACP) is a presynaptic nerve terminal protein and is now known to be a major component of Lewy bodies (LBs) in Parkinson's disease. Previous studies have shown that LBs are occasionally found in patients with Hallervorden-Spatz disease (HSD), a hereditary or sporadic neuroaxonal dystrophy. Therefore, an immunocytochemical examination of the brain tissues from two patients with HSD for alpha-synuclein/NACP was performed. In both cases, LBs were observed in the substantia nigra, locus ceruleus and other subcortical nuclei. These LBs were strongly immunolabelled with anti-alpha-synuclein/NACP. Moreover, abnormal alpha-synuclein/NACP-immunoreactive structures in the neuronal somata and processes were found in the cerebral neocortex, hippocampus, basal ganglia, thalamus, pontine and inferior olivary nuclei, spinal grey matter, and peripheral sympathetic ganglia. Although numerous dystrophic axons (spheroids) were found throughout the brain, either none or only a few were positive for alpha-synuclein/NACP. These findings suggest that widespread accumulation of alpha-synuclein/NACP is a pathological feature in patients suffering from HSD with LBs, and that this phenomenon is unrelated to axonal spheroid formation.

Adult↗
PubMed1999

Gastrointestinal motility in patients with irritable bowel syndrome studied by using radiopaque markers.

BACKGROUND: Irritable bowel syndrome (IBS) has been identified as a physiologic abnormality, but no test has been established as a diagnostic standard for gastrointestinal dyskinesia in IBS patients. The aim of this study was to investigate gastrointestinal motility in patients with IBS by using radiopaque markers. METHODS: Gastrointestinal motility was studied in IBS patients (n = 72), constipation patients (n = 19), diarrhoea patients (n = 9), and healthy controls (n = 23). Using three types of radiopaque markers, analysis was performed to establish the transit time and a new indicator, the 'scattering index'. RESULTS: Transit times were not characteristic in IBS. The patients with IBS had significantly higher scattering indexes in the colon and total gut than the healthy controls and the patients with constipation and diarrhoea. The transit time and scattering index of the colon were linearly correlated in the healthy controls and the constipation and diarrhoea patients but were not correlated in the IBS patients. Using transit time and scattering index was a reliable means of evaluating gastrointestinal motility in IBS patients, with a sensitivity of 65% and a specificity of 96%. CONCLUSION: Three days' use of the radiopaque marker method was useful for providing an objective means of detecting gastrointestinal dysmotility in IBS patients.

Adolescent↗
PubMed1999

A novel syndrome of diabetes mellitus, renal dysfunction and genital malformation associated with a partial deletion of the pseudo-POU domain of hepatocyte nuclear factor-1beta.

Mutations in the homeodomain-containing transcription factor hepatocyte nuclear factor (HNF)-1beta are the cause of one form of maturity-onset diabetes of the young (MODY), type 5 (MODY5). We have studied a Norwegian family, N5, with a syndrome of mild diabetes, progressive non-diabetic renal disease and severe genital malformations. The sequence of the HNF-1beta gene ( TCF2 ) revealed a 75 bp deletion in exon 2 (409-483del) which would result in the synthesis of a protein lacking amino acids Arg137 to Lys161 (R137-K161del). This deletion is located in the pseudo-POU region of HNF-1beta, a region implicated in the specificity of DNA binding. Functional studies of R137-K161del HNF-1beta revealed that it could not bind an HNF-1 target sequence or stimulate transcription of a reporter gene indicating that this is a loss-of-function mutation. The R137-K161del allele co-segregated with diabetes and renal disease in pedigree N5. In addition, two of four female carriers with this mutation had vaginal aplasia and rudimentary uterus (Müllerian aplasia). These studies strongly suggest that heterozygous mutations in the HNF-1beta gene are associated with a syndrome characterized by MODY and severe, non-diabetic renal disease. Moreover, the presence of internal genital malformations in two females suggests that additional clinical features may be associated with HNF-1beta mutations.

Adolescent↗
PubMed1999

Antipsychotic-induced life-threatening 'esophageal dyskinesia'.

We report two patients with lingual dyskinesia and complaints of food regurgitation following long-term antipsychotic therapy. Esophageal contrast radiography revealed dyskinetic movements extending from the pharynx to the upper portion of the esophagus. The elevation of intraesophageal pressure was confirmed by esophageal manometry. The dyskinetic movements almost disappeared along with improvement of lingual dyskinesia following the administration of sulpiride in one patient. Another patient suddenly died due to asphyxiation of foods before the beginning of treatment. We termed this life-threatening movement, 'esophageal dyskinesia'. It should be emphasized that 'esophageal dyskinesia' associated with lingual dyskinesia is a potentially fatal adverse reaction to antipsychotic therapy.

Aged↗
PubMed1999

Functional roles of thrombopoietin-c-mpl system in essential thrombocythemia.

Thrombopoietin (TPO) is implicated as a primary regulator of megakaryopoiesis and thrombopoiesis through binding to the cytokine receptor c-Mpl (the product of the c-mpl-proto-oncogene). In addition to its physiologic role, the TPO-c-mpl system has been suggested to participate in the pathophysiology of essential thrombocythemia (ET) which is a clonal disorder characterized by a sustained elevation of the circulating platelet count and bone-marrow hyperplasia with excessive proliferation of megakaryocytes. Recent studies have demonstrated that serum TPO levels are slightly elevated or within normal range in ET patients, whereas serum TPO levels tend to be inversely correlated with platelet mass. Flow cytometric, Western blot, and Northern blot analyses have revealed that the expression of platelet c-Mpl is strikingly reduced in all of patients with ET, possibly due to the decreased expression of c-mpl mRNA. These results suggest that normal or slightly elevated levels of serum TPO in ET patients may be attributable to the impaired uptake and catabolism of TPO owing to the low c-Mpl expression. Furthermore, immunoblotting with anti-phosphotyrosine antibody showed that no aberrant protein-tyrosine phosphorylation was observed in platelets of ET patients before treatment with TPO, and the levels of TPO-induced protein-tyrosine phosphorylation, including c-Mpl-tyrosyl phosphorylation, roughly paralleled those of c-Mpl expression, suggesting that c-Mpl-mediated signaling pathway was not constitutively activated in platelets of ET patients. Although activating mutation in the TPO gene, which leads to overexpression of TPO mRNA, has been reported in familial thrombocythemia, these results suggest that TPO-c-Mpl system may not be directly linked to pathogenesis of sporadic ET.

Humans↗
PubMed1999

[Postoperative respiratory failure resulting from perioperative withdrawal of antiparkinsonian medications].

A patient with Parkinson's disease developed postoperative respiratory arrest due to perioperative withdrawal of antiparkinsonian medications and later presented a rapid recovery after parenteral administration of levodopa. In perioperative management of parkinsonian patients, it is important to continue antiparkinsonian medications until the operation is started and to administer levodopa parenteraly after the operation until oral administration of antiparkinsonian drugs becomes possible. In addition, we must pay attention to the choice of drugs so that parkinsonism may not be induced or aggravated.

Aged↗
PubMed1999

[The clinical features of patients with probable dementia with Lewy bodies--report of 4 cases].

Recently, McKeith et al. proposed criteria for the clinical diagnosis of dementia with Lewy bodies (DLB). In our study the clinical features of four patients with progressive dementia, visual hallucinations, delusions, and parkinsonism were compatible with those of DLB. To evaluate the neurological and psychiatric features, responses to medications, magnetic resonance imaging (MRI), and single-photon emission computed tomography (SPECT) in patients with DLB, we compared the above DLB patients with age- and gender-matched Parkinson's disease patients showing no signs of dementia. Our DLB patients presented with mild tremor, moderate rigidity and akinesia, severe constitutional dysfunction and recurrent visual hallucinations and delusions. These psychiatric symptoms became worse by anticholinergic agents and dopamine agonists and were difficult to control using neuroleptic medications. MRI revealed atrophy of the cerebrum to be more accentuated in the parietal region. SPECT demonstrated hypoperfusion in the parietal and occipital lobes. These findings suggest that parietal lobe dysfunction is a feature of DLB. It may, therefore, be concluded from this study that brain MRI and SPECT are useful in the clinical diagnosis of DLB, and that great caution should be taken when prescribing longacting dopamine agonists and neuroleptics to such patients.

Aged↗
PubMed1999

Sutureless technique for subacute left ventricular free wall rupture: A case report of an 85-year-old.

This case was an 85-year-old female who developed left ventricular free wall rupture (LVFWR) of the anterior wall 13 days after an acute myocardial infarction. She was further complicated with an ascending aortic aneurysm and severe aortic regurgitation. The wall was repaired using a sutureless technique with an autologous pericardial patch and GRF glue without cardiopulmonary bypass. Although the complication of a left ventricular aneurysm was seen, the postoperative course was uneventful. Nevertheless, she is doing well 9 months after surgery.

Aged↗
PubMed1999

In vivo effects of calcium entry blockers on human parathyroid adenoma cells with special reference to calcium sensing ability and the hormone secretion.

We evaluated the effects of calcium-entry blockers on parathyroid hormone (PTH) secretion by human parathyroid adenoma cells in vitro. Nifedipine and bamidipine inhibited PTH secretion, while diltiazem had no significant effect. Cytosolic calcium concentrations were measured by use of the calcium-sensitive fluorescent dye fluo-3 with confocal laser scanning microscopy. Nifedipine increased the cytosolic concentration of calcium, whereas diltiazem decreased it. Results suggest that, in parathyroid adenoma cells, regulation of PTH secretion with respect to intracellular calcium concentration would be maintained despite differing response of intracellular calcium concentration following exposure to calcium-entry blockers.

Adenoma↗