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Biomedical subjects

K Yamagata

Publications and source records attributed to K Yamagata.

At least 109 records · Page 6Linked to original sources
PubMed1998

A quantitative immunohistochemical evaluation of inflammatory cells at the affected and unaffected sites of inflammatory bowel disease.

Levels of T lymphocytes, histiocytes and mast cells have been reported to be increased in the affected mucosa of Crohn's disease (CD) and ulcerative colitis (UC), but the colorectal distribution of these cells is not fully understood. We hypothesized that differences in cell densities between CD and UC would be characteristic, not only in the affected, but also in the unaffected mucosa. The aims of the present study were to clarify whether there were any differences in cell densities in CD, UC and infectious colitis (IC) in the affected mucosa and between CD and UC in the unaffected mucosa. Using mouse monoclonal antibodies recognizing memory T cells (OPD4), cytotoxic/suppressor T cells (C8/144B), histiocytes (PG-M1) and mast cells (AA1), we evaluated mucosal cell densities in biopsy specimens from both endoscopically affected and unaffected sites of CD (n = 12) and UC (n = 15) and from affected sites of IC (n = 10). Ten normal controls were also examined. At affected sites, all cells were significantly more abundant in UC than in the other conditions, except that the density of PG-M1+ in CD was similar to that seen in UC. Although the densities of OPD4+ and C8/144B+ cells at unaffected sites were slightly higher in both CD and UC and in UC, respectively, there was no significant difference in cell densities between CD and UC. The ratio of OPD4+ cell density at affected sites to that at unaffected sites was appreciably higher in UC than in CD. The results suggest that a common feature of UC and CD is an increase in PG-M1+ cells at the affected mucosa but that the other inflammatory cells studied are more abundant, particularly in UC, and that the difference between UC and CD is conspicuous when comparing the OPD4+ cell density of the affected mucosa with that of the unaffected mucosa.

Adult↗
PubMed1998

[Evaluation of immunochromatography-based rapid detection kit for fecal Escherichia coli O157].

"Quix" is an immunochromatography-based direct detection kit for the E. coli O157 LPS antigen in the patient's stool. The present study was conducted to evaluate the efficacy of the kit for rapid diagnosis of enterohemorrhagic Escherichia coli (EHEC) O157 infection. Sensitivity of the kit was determined using a pure culture of a clinical isolate of E. coli O157. Analytical sensitivity was found to be 5 x 10(5) CFU/ml. When compared with the culture method using fecal samples of 64 patients and with bloody diarrhea, sensitivity and specificity were 95.0% (19/20) and 86.4% (38/44), respectively, and overall agreement to culture method was 89.1% (57/64). One patient was found positive by culture method while negative in the present method, where the sample contained a low number of the cells less than the detection limit. Four of the six patients with a negative result by culture method and positive in the present method, were confirmed E. coli O157 infection by positive IgM antibody response against the E. coli O157 LPS. The discrepancy between the two methods seemed to be attributable to antibiotic administration. In one patient, Salmonella urbana (O30(1)30(2)) was detected. The O30(1) antigen of this bacterium is well known to be identical to the E. coli O157 antigen. When the present method was compared with an ELISA-based E. coli O157 LPS antigen detection kit, sensitivity and specificity were 100% (11/11) and 82.1% (23/28), and overall agreement to ELISA method was 87.2% (34/39). From these findings, Quix is useful as a rapid diagnostic kit in the primary clinics, outpatient or bedside use. E. coli O157 LPS antigen in patient's fecal samples can be detected in about five minutes with this simple procedure. Early diagnosis using such a simple kit will largely contribute for the early treatment and prevention of severe complications of the E. coli O157 infection.

Antigens, Bacterial↗
PubMed1998

[In vitro specific binding of Shiga toxin 1 and 2 by TAK-751S (Gb3 analog)].

TAK-751S is a synthetic trisaccharide coupled to Chromosorb P using a spacer sequence of 8-methoxycarboyloctyl (MCO). Its chemical structure is similar to a human receptor (Gb3) of Stx produced by enterohemorrhagic Escherichia coli (EHEC). In vitro efficacy of TAK-715S was studied by using ACHN cultured cell assay, which is sensitive and specific for measuring low level of Stx. Under various conditions, TAK-715S was mixed with purified Stx1 and Stx2, and residual free toxins in the solution were measured by using ACHN cells. TAK-715S was demonstrated to bind specifically to Stx1 and Stx2 under the condition similar to a human intestine while Chromsorb P did not bind to any Stx. The binding activity was stable in the presence of various processed foods, fresh vegetables and fruits. Antibiotics such as fosfomycin, kanamycin and norfloxacin did not disturb its binding capability. Minimum inhibitory concentrations of these antibiotics against Staphylococcus aureus FDA209P or E. coli NIHJ JC-2 neither changed after incubating with TAK-751S for 60 min at 37 degrees C. These results suggest that TAK-751S can be given orally with various foods and antibiotics for the elimination of Stx1 and Stx2 in the gut of patients with EHEC infections.

Adsorption↗
PubMed1998

Anticancer effects of preoperative chemotherapy on colorectal carcinoma.

This study was designed to evaluate the efficacy of preoperative chemotherapy and to investigate the relationship between the histopathologic response and prognosis in patients with colorectal carcinoma. Thirty-six previously untreated patients with advanced colorectal carcinoma were consecutively enrolled in this study and received preoperative N-(2-tetrahydrofuryl-5-fluorouracil (FT-207) by suppository. The histopathologic response was investigated. Histopathologically, 14 patients had no response, 19 responded slightly, 2 moderately and 1 had a complete response to the chemotherapy. The extent of the histopathologic response to chemotherapy was greater in the deeper layers of the invaded tissue. There was no relation between the location of the tumor and the extent of the histopathologic response. Based on clinical cancer staging, the overall 5-year survival rate was 100% in patients with Duke's A and Duke's B cancer and 45% in patients with Duke's C cancer; the 3-year survival rate was 25% in patients with Duke's D cancer. The 5-year survival rate for those with a positive histopathologic response to chemotherapy was 71%, whereas that for the nonresponders was 79%. Mild chemotherapy in the form of FT-207 suppositories was found to be effective histopathologically. However, no relationship was seen between the histopathologic response and survival rate.

Adult↗
PubMed1998

Mutation P291fsinsC in the transcription factor hepatocyte nuclear factor-1alpha is dominant negative.

The type 3 form of maturity-onset diabetes of the young (MODY3) results from mutations in the gene encoding the transcription factor, hepatocyte nuclear factor-1alpha (HNF-1alpha). The mechanism by which mutations in only one allele of the HNF-1alpha gene impair pancreatic beta-cell function is unclear. The functional form of HNF-1alpha is a dimer--either a homodimer or a heterodimer with the structurally related protein HNF-1beta--that binds to and activates transcription of the genes whose expression it regulates. HNF-1alpha is composed of three functional domains: an amino-terminal dimerization domain (amino acids 1-32), a DNA-binding domain with POU-like and homeodomain-like motifs (amino acids 150-280), and a COOH-terminal transactivation domain (amino acids 281-631). Because the dimerization domain is intact in many of the mutant forms of HNF-1alpha found in MODY subjects, these mutant proteins may impair pancreatic beta-cell function by forming nonproductive dimers with wild-type protein, thereby inhibiting its activity; that is, they are dominant-negative mutations. This hypothesis was tested by comparing the functional properties of the frameshift mutation P291fsinsC, the most common mutation identified to date in MODY3 patients, and wild-type HNF-1alpha. P291fsinsC-HNF-1alpha showed no transcriptional transactivation activity in HeLa cells, which lack endogenous HNF-1alpha. Overexpression of P291fsinsC-HNF-1alpha in MIN6 cells, a mouse beta-cell line, resulted in an approximately 40% inhibition of the endogenous HNF-1alpha activity in a dosage-dependent manner. Furthermore, heterodimer formation between wild-type and P291fsinsC mutant proteins were observed by electrophoretic mobility shift assay. These data suggest that the P291fsinsC mutation in HNF-1alpha functions as a dominant-negative mutation. However, other mutations, such as those in the promoter region and dimerization domain, may represent loss of function mutations. Thus mutations in the HNF-1alpha gene may lead to beta-cell dysfunction by two different mechanisms.

Animals↗
PubMed1998

Molecular mechanisms of pancreatic beta-cell destruction in autoimmune diabetes: potential targets for preventive therapy.

Mononuclear cell infiltration into the islets of the pancreas (insulitis) is characteristic of autoimmune diabetes. T lymphocytes are the predominant subpopulation seen in insulitis, and are involved in the autoimmune process. Insulin-producing beta cells are thought to be destroyed by cytotoxic T cells, cytokines or nitric oxide, and beta-cell death occurs, at least partly, via apoptosis. Beta-cell death induced by cytokines is inhibited by Bcl-2, suggesting its potential as a tool for gene therapy. The Fas/Fas-ligand system plays a critical role in inducing insulitis and overt diabetes in nonobese diabetic (NOD) mice, a model of autoimmune diabetes. T-cell receptor gene usage in infiltrating T cells is not restricted in NOD mice, but there are some observations indicating relative restriction in human IDDM patients. Preventive strategies might be developed by focusing on these molecules involved in beta-cell destruction. The establishment of screening techniques for detecting prediabetic patients is also necessary to allow successful intervention.

Animals↗
PubMed1998

Vitamin E prevents apoptosis in cortical neurons during hypoxia and oxygen reperfusion.

Cerebral ischemia followed by oxygen reperfusion induces apoptosis in hippocampal neurons in stroke-prone spontaneously hypertensive rats (SHRSP) but not in Wistar Kyoto rats (WKY). The overproduction of oxygen-free radicals that occurs in the tissues of SHRSP is implicated in reoxygenation injury after hypoxia. Antioxidants inhibit reoxygenation injury in hippocampal slices, and temporal cortices in Alzheimer's disease increase sensitivity to oxygen-free radicals. Because this sensitivity may contribute to the development of the disease, we have studied hypoxia and oxygen reperfusion using cortical neurons isolated from WKY and SHRSP (at 15 days of gestation). We have tried to determine whether cortical neurons are damaged under these conditions, and whether neurons from SHRSP are more vulnerable than those from WKY. We have tried also to verify whether neuronal damage is minimized by vitamin E using the following techniques: (a) Trypan blue staining, (b) in situ staining of apoptosis, (c) ultrastructural examination, and (d) measurement of lactic dehydrogenase (LDH) activity in the bathing medium. Furthermore, we have examined the mechanisms involved in the development of neuronal damage and have studied ways of minimizing it. We demonstrated that 36 hours of hypoxia significantly increased the rate of cell death in SHRSP (p < 0.01), although 12 to 24 hours of hypoxia did not increase cell death in either WKY or SHRSP. In addition, 6 to 36 hours of hypoxia and 1.5 to 5 hours of oxygen reperfusion heavily damaged cells of both WKY and SHRSP, and most became apoptotic or necrotic. In contrast, cells incubated with 50 to 300 microg/ml of vitamin E remained intact, although 10 to 20 microg/ml of vitamin E did not totally preserve the cells. Moreover, vitamin E protected the neurons from high concentrations of sodium nitroprusside (nitric oxide donor) in a dose-dependent manner. Vitamin E, when added to the cells, increased in concentration in a time-dependent manner over a 24-hour period and in a dose-dependent manner below 200 microg/ml, and it was detected mostly in the mitochondria. We also demonstrated that serial treatments with allopurinol (a xanthine oxidase inhibitor) or superoxide dismutase preserved neurons during hypoxia and oxygen reperfusion. These data indicate that SHRSP neurons are weaker than WKY neurons in long-term hypoxia; oxygen radical generation occurs in the early minutes after reperfusion, and then the oxygen-free radicals cause heavy damage to the cells; and antioxidants including vitamin E react with the radicals, thereby preventing apoptosis and necrosis. Therefore, antioxidants appear to be the most important agents in lowering oxygen-free radical damage in cortical neurons.

Animals↗
PubMed1998

[Structure and function of neural plasticity-related gene products].

We have isolated novel immediate early genes (IEGs) from the hippocampus by differential cloning techniques. These mRNAs are induced by synaptic activity and translated into proteins that may affect neural function. We have analyzed a variety of "effector" immediate early genes. These mRNAs encode: 1) cytoplasmic proteins, such as cyclooxygenase-2, a small G protein, Rheb, and a cytoskeleton-associated protein, Arc; 2) membrane-bound proteins, such as the cell adhesion protein Arcadlin, and a neurite-outgrowth protein, Neuritin; and 3) a secreted protein, Narp. We hypothesize that physiological stimulation induces "effector" proteins that might strengthen synaptic connections of activated synapses. In contrast, pathological conditions such as epilepsy or drug addiction may accelerate overproduction of these gene products, which cause abnormal synapse formation. Gene targeting and in vivo gene transfer techniques are required to prove this hypothesis.

Animals↗
PubMed1997

Aspirin effects on colonic mucosal bleeding: implications for colonic biopsy and polypectomy.

BACKGROUND: Many patients who require endoscopic treatments such as biopsy and polypectomy are given antiplatelet agents reluctantly. We have studied the effects of aspirin on colonic mucosal hemostasis. METHODS AND PATIENTS: We developed a new endoscopic device to make a standard incision (7-mm length) on the colonic mucosa to study colon bleeding time. We measured the colon bleeding time of normal colonic mucosa in 47 cases. The colon bleeding time and skin bleeding time (Simplate method) were measured before and one hour after aspirin ingestion (990 mg) in ten healthy subjects. RESULTS: The bleeding time of normal colonic mucosa was 156 +/- 71 (mean +/- standard deviation) seconds. Significant prolongation was noted in both skin bleeding time (357 +/- 192 vs. 477 +/- 183 seconds; P < 0.05) and colon bleeding time (155 +/- 47 vs. 244 +/- 169 seconds; P < 0.05) after aspirin ingestion. CONCLUSIONS: Bleeding time was measured safely under direct colonoscopic visualization. Aspirin prolonged the colon bleeding time. Therefore, endoscopists should be aware of a risk of abnormal bleeding after endoscopic biopsy and polypectomy in patients with aspirin use. Two days were necessary for colon bleeding time to become normalized in patients with aspirin use.

Aspirin↗
PubMed1997

Genetic variation in the hepatocyte nuclear factor-1 alpha gene in Danish Caucasians with late-onset NIDDM.

Non-insulin-dependent diabetes mellitus (NIDDM) is a phenotypically and genetically heterogeneous disorder. A recent random genome mapping study has localized a locus termed NIDDM2 that maps to the region of chromosome 12 that includes MODY3, one of the three genes responsible for maturity-onset diabetes of the young, a monogenic form of NIDDM characterized by early age of onset and autosomal dominant inheritance. These findings suggest that NIDDM2 and MODY3 may represent different alleles of the same gene. MODY3 has recently been shown to be the gene encoding the transcription factor hepatocyte nuclear factor-1 alpha (HNF-1 alpha) thereby allowing us to determine whether mutations in the HNF-1 alpha gene are present in subjects with late-onset NIDDM. We screened 84 white NIDDM patients of Danish ancestry and found four nucleotide substitutions that changed the sequence of HNF-1 alpha, Ile27-->Leu, Ala98-->Val, Ser487-->Asn and Arg583-->Gln, five nucleotide substitutions that were silent and did not change the amino acid, Leu17, Gly288, Leu459 and Thr515, and five substitutions in the intron regions. The frequencies of the codon 27, 98 and 487 amino acid variants were similar in 245 unrelated NIDDM patients and 242 age-matched control subjects. The Arg583-->Gln mutation was found in 2 of 245 NIDDM patients and in none of the control subjects. Thus, genetic variation in the HNF-1 alpha gene is not a common factor contributing to NIDDM susceptibility in white subjects of Danish ancestry.

Age of Onset↗
PubMed1997

Identification of nine novel mutations in the hepatocyte nuclear factor 1 alpha gene associated with maturity-onset diabetes of the young (MODY3).

Maturity-onset diabetes of the young (MODY) is a genetically heterogeneous subtype of non-insulin-dependent diabetes mellitus (NIDDM) characterised by early onset, autosomal dominant inheritance and a primary defect in insulin secretion. Recent studies have shown that mutations in the two functionally related transcription factors, hepatocyte nuclear factor 4 alpha (HNF-4alpha) and hepatocyte nuclear factor 1 alpha (HNF-1alpha) are associated with the MODY1 and MODY3 forms of diabetes respectively, whereas mutations in the enzyme glucokinase are the cause of the MODY2 form. We have examined 10 unrelated Caucasian families in which MODY/NIDDM co-segregated with markers for MODY3 for mutations in the HNF-1alpha gene (TCF1). Ten different mutations were observed in these families, all of which co-segregated with diabetes. There were no obvious relationships between the nature of the mutations observed (i.e. frameshift, nonsense, or missense) or their location in the gene with clinical features of diabetes (age at onset, severity) in these families. The mechanisms by which mutations in the HNF-1alpha gene cause diabetes mellitus are unclear but might include abnormal pancreatic islet development during foetal life thereby limiting their later function, as well as impaired transcriptional regulation of genes that play a key role in normal pancreatic beta cell function.

DNA-Binding Proteins↗
PubMed1997

Involvement of cyclooxygenase-2 in LPS-induced fever and regulation of its mRNA by LPS in the rat brain.

We previously showed that a febrile dose of lipopolysaccharide (LPS) in rats resulted in induction of cyclooxygenase-2 (COX-2) mRNA in brain blood vessels/leptomeninges and telencephalic neurons. To elucidate the causal link between fever and LPS-induced COX-2 mRNA, we experimentally modified one or the other of these parameters and examined their relation. 1) LPS-induced fever was suppressed by pretreatment with a COX-2-specific inhibitor. 2) Levels of COX-2 mRNA in the neurons and blood vessels 2.5 h after LPS administration were even higher in the inhibitor-pretreated rats (afebrile) than in vehicle-pretreated ones (febrile). 3) After repeated administration of LPS, rats became tolerant to LPS, in which state LPS induced neither fever nor COX-2 mRNA in blood vessels/leptomeninges. When rats had not completely established LPS tolerance, they showed various degrees of fever that were closely correlated with the level of COX-2 mRNA in blood vessels but not with that in neurons. 4) Urethan anesthesia reduced basal as well as LPS-induced COX-2 mRNA in telencephalic neurons, but the rats still responded to LPS with fever and induction of COX-2 mRNA in the blood vessels/leptomeninges. These results suggest that COX-2 induced in brain blood vessels/leptomeninges is involved in the molecular mechanism of LPS-induced fever.

Abdomen↗
PubMed1997

Mutations in the hepatocyte nuclear factor-1alpha gene in MODY and early-onset NIDDM: evidence for a mutational hotspot in exon 4.

We have recently shown that mutations in the gene encoding the transcription factor hepatocyte nuclear factor (HNF)-1alpha are the cause of one form of maturity-onset diabetes of the young (MODY3). Here, we report the exon-intron organization and partial sequence of the human HNF-1alpha gene. In addition, we have screened the ten exons and flanking introns of this gene for mutations in a group of 25 unrelated white subjects from Germany who presented with NIDDM before 35 years of age and had a first-degree relative with NIDDM. Mutations were identified in nine of these individuals, suggesting that mutations in the HNF-1alpha gene are a common cause of diabetes in German subjects with early-onset NIDDM and a family history of diabetes. Thus, screening for mutations in this gene may be indicated in subjects with early-onset NIDDM. Interestingly, three of the nine mutations occurred at the same site in exon 4 with insertion of a C in a polyC tract, centered around codon 290 (designated Pro291fsinsC), thereby resulting in a frameshift during translation and premature termination. Analyses of linked DNA polymorphisms in the HNF-1alpha gene indicated that the Pro291fsinsC mutation was present on a different haplotype in each subject, implying that the polyC tract represents a mutational hot spot. We have also identified the mutation in the HNF-1alpha gene in the Jutland pedigree, one of the original MODY pedigrees reported in the literature, as being a T-->G substitution in codon 241, resulting in the replacement of a conserved Cys by Gly (C241G). The information on the sequence of the HNF-1alpha gene and its promoter region will facilitate the search for mutations in other subjects and studies of the role of the gene in determining normal beta-cell functions.

Adolescent↗
PubMed1997

Mutations in the hepatocyte nuclear factor-1alpha gene are a common cause of maturity-onset diabetes of the young in the U.K.

Mutations in the hepatocyte nuclear factor-1alpha (HNF1alpha) gene have recently been shown to cause maturity-onset diabetes of the young (MODY). We have examined 15 U.K. MODY families for mutations in the coding region of the HNF-1alpha gene. Eight different mutations, three frameshift (P291fsinsC, P379fsdelCT, and A443fsdelCA) and five missense mutations (P129T, R131W, R159W, P519L, and T620I), were identified in eleven families (73%). The previously reported mutation P291fsinsC was found in four pedigrees. A screen of a further 32 probands with early onset (<40 years of age) NIDDM showed the mutation in two additional families. This common mutation was present on at least three different haplotypes, suggesting that its high frequency is due to recurrent mutation rather than a founder effect. We have demonstrated that mutations in the HNF-1alpha gene are a common cause of MODY in U.K. families and result in early onset NIDDM with a progressive clinical course. Mutation-based genetic counseling can now be considered for the majority of patients with MODY.

Adolescent↗
PubMed1997

Mutations in the hepatocyte nuclear factor-1alpha/MODY3 gene in Japanese subjects with early- and late-onset NIDDM.

Recent studies have shown that mutations in the hepatocyte nuclear factor (HNF)-1alpha gene are the cause of maturity-onset diabetes of the young type 3 (MODY3). We have screened 193 unrelated Japanese subjects with NIDDM for mutations in this gene: 83 with early-onset NIDDM (diagnosis at <30 years of age) and 110 with late-onset NIDDM (diagnosis > or = 30 years of age). All of the members of the latter group also had at least one sibling with NIDDM. The 10 exons, flanking introns, and promoter region were amplified using polymerase chain reaction and were sequenced directly. Mutations were found in 7 of the 83 (8%) unrelated subjects with early-onset NIDDM. The mutations were each different and included four missense mutations (L12H, R131Q, K205Q, and R263C) and three frameshift mutations (P379fsdelCT, T392fsdelA, and L584S585fsinsTC). One of the 110 subjects with late-onset NIDDM was heterozygous for the missense mutation G191D. This subject, who was diagnosed with NIDDM at 64 years of age, also had a brother with NIDDM (age at diagnosis, 54 years) who carried the same mutation, suggesting that this mutation contributed to the development of NIDDM in these two siblings. None of these mutations were present in 50 unrelated subjects with normal glucose tolerance (100 normal chromosomes). Mutations in the HNF-1alpha gene occur in Japanese subjects with NIDDM and appear to be an important cause of early-onset NIDDM in this population. In addition, they are present in about 1% of subjects with late-onset NIDDM.

Age Factors↗