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Biomedical subjects

T Kikuchi

Publications and source records attributed to T Kikuchi.

At least 361 records · Page 20Linked to original sources
PubMed1994

Methylcobalamin (methyl-B12) promotes regeneration of motor nerve terminals degenerating in anterior gracile muscle of gracile axonal dystrophy (GAD) mutant mouse.

We examined the effects of methylcobalamin (methyl-B12, mecobalamin) on degeneration of motor nerve terminals in the anterior gracile muscle of gracile axonal dystrophy (GAD) mutant mice. GAD mice received orally methyl-B12 (1 mg/kg body wt/day) from the 40th day after birth for 25 days. In the distal endplate zone of the muscle, although most terminals were degenerated in both the untreated and methyl-B12-treated GAD mice, sprouts were more frequently observed in the latter. In the proximal endplate zone, where few degenerated terminals were seen in both groups of the mice, the perimeter of the terminals was increased and the area of the terminals was decreased significantly in the methyl-B12-treated GAD mice. These findings indicate that methyl-B12 promotes regeneration of degenerating nerve terminals in GAD mice.

Animals↗
PubMed1994

Analysis of the p53 gene and its expression in human glioblastoma cells.

Chromosome 17p has been shown to be an early and frequent target for loss of heterozygosity through mitotic recombination in astrocytomas. These losses are frequently accompanied by point mutations in the p53 gene of the remaining allele, resulting in loss of wild type p53 function. However, a fraction of astrocytomas retain constitutional heterozygosity and do not have p53 mutations; some of these lose wild type p53 activity through binding to the protein product of amplified mdm2 genes. To test whether loss of wild type p53 biological function is a necessary step in astrocytoma progression we analyzed p53 expression and biological function in 13 glioma cell lines. All the cell lines expressed a 2.8-kilobase p53 transcript and showed various amounts of p53 protein by immunoprecipitation, except for cell line LN-Z308 which had only a small truncated p53 mRNA and no protein expression. To test whether the p53 expressed in these cell lines was functionally wild type or mutant we transfected them with a plasmid construct harboring a chloramphenicol acetyltransferase (CAT) reporter gene under the control of transcriptional elements that are induced by wild type but not mutant p53. Four lines were shown to retain wild type p53 function. Sequencing of the p53 gene in two of these cell lines confirmed the wild type genotype. These results show that inactivation of the p53 gene is not an obligatory step in glioblastoma genesis. This suggests either that two pathways (p53 inactivation dependent or independent) may lead to a tumor group classified histologically as glioblastoma or that in some cases p53 mutations are bypassed due to the presence of mutations in downstream effector genes.

Animals↗
PubMed1994

The sequence of the human phosducin gene (PDC) and its 5'-flanking region.

Phosducin, a principal protein of the retinal photoreceptor cells, modulates the phototransduction cascade by interacting with transducin. Recently, it has been reported that phosducin is a protein virtually identical to the G-protein inhibitor protein (GIP) in brain. Here, we have sequenced the complete human gene (PDC) and 2215 bp of its 5'-flanking region. The gene is 18 kb in length and has four exons and three introns. The splicing sites for donor and acceptor are in good agreement with the GT/AG rule. Comparative studies of human and mouse phosducin revealed highly homologous sequences. Both the human phosducin gene and a mutant gene locus for Usher syndrome type II have been assigned to chromosome 1q25-q32. The association of this gene with a human disease locus suggests that phosducin may be a potential candidate gene for this disorder.

Animals↗
PubMed1994

Corticosteroids enhance S-antigen expression in nonretinal ocular tissues of rats with experimental autoimmune uveitis.

S-antigen (S-Ag), a major protein on the retinal photoreceptor cell, can induce experimental autoimmune uveitis (EAU). We have previously detected S-Ag and its mRNA in irises of chronic uveitis patients receiving long-term steroid therapy. To further investigate the effect of steroid therapy on ocular tissue, we compared levels of S-Ag and its mRNA in EAU rats with and without steroid treatment. EAU was induced in 72 Lewis rats by two footpad injections of S-Ag. The rats were then treated with Depo-Medrol or phosphate-buffered saline by intramuscular injection. Eyes were collected at different time points. S-Ag mRNA was detected in the lens epithelium, trabecular meshwork, iris, and ciliary body of 47.2% of the steroid-treated group vs 22.2% of the controls. S-antigen was also detected in 30.6% of the eyes of the treated group vs 16.7% of the controls. S-Ag and its mRNA was found only in the retina of normal rats. These results support the hypothesis that prolonged corticosteroid therapy in uveitic patients might enhance the expression of S-Ag in nonretinal ocular tissues and might contribute to the ocular side effects of corticosteroid.

Animals↗
PubMed1994

Effect of platelet-activating factor antagonist on brain injury in rats.

The ability of a platelet-activating factor (PAF) antagonist to reduce infarct size has been reported in a animal model of focal brain ischemia. The authors studied the effect of PAF antagonist (TCV-309) on cold brain injury in rats. Twenty-four hours after injury, water content was determined by both drying-weighing and specific gravimetric techniques, and ischemic brain damage was assessed with 2,3,5-triphenyltetrazolium chloride in multiple coronal sections. Pretreatment with TCV-309 (lmg/kg) significantly reduced the water content (p < 0.01) and volume of ischemic damage (p < 0.001) produced by the cold brain injury. These results indicate that PAF antagonist can ameliorate secondary brain tissue damage following brain injury.

Animals↗
PubMed1994

Curative effects of combination therapy with lentinan and interleukin-2 against established murine tumors, and the role of CD8-positive T cells.

The antitumor activity of a combination of an antitumor polysaccharide, lentinan (a beta 1-3 glucan with beta 1-6 branches), and interleukin-2 (IL-2) was evaluated against established MBL-2 lymphoma and S908.D2 sarcoma at i.d. sites. Treatment of the MBL-2-tumor-bearing BDF1 mice with lentinan and IL-2 induced complete regression of tumor in 87.5% of mice treated. In contrast, treatments using either lentinan or IL-2 alone failed to induce complete regression of tumor, although temporal growth inhibition of tumor was observed about in half of the mice treated. Improvements of antitumor effects by the combination of lentinan and IL-2 were also observed in the MBL-2/B6 and S908.D2/B10.D2 systems. Expression of the antitumor effects of lentinan/IL-2 treatments required the intact T cell compartment, because the effects were not observed when nude mice were used. In the MBL-2/B6 system, the antitumor action of lentinan/IL-2 treatment was abolished in mice treated with antibody to CD8 antigen, whereas antibodies to CD4 or NK1.1 were ineffective. Furthermore, augmented tumor-specific cytotoxic T lymphocyte (CTL) activity was observed in regional lymph node cells of the mice after lentinan and IL-2 administration. These data indicate that the antitumor effects of lentinan/IL-2 are mediated by CD8+ CTL but not by CD4+ T cells or NK1.1+ NK/LAK cells, and suggest that this combined therapy may be effective against even established tumors that are resistant to IL-2 therapy.

Animals↗
PubMed1994

The successful surgical repair of a left ventricular-right atrial communication and aneurysm of the mitral valve caused by infective endocarditis: report of a case.

We report herein the case of a 42-year-old man who developed a left ventricular-right atrial communication and aneurysm of the mitral valve caused by infective endocarditis, which was associated with aortic regurgitation. Based on the findings of congestive heart failure, prolongation of the PR interval, and the added threat of rupture of the mitral aneurysm, surgical treatment was decided upon as the best course of action. The aortic and mitral valves were replaced with prosthetic mechanical valves, and the septal communication was simultaneously closed with a patch. The patient's postoperative course was uneventful and he has been in good health since. Thus, we believe that aggressive surgical intervention for complicated lesions such as those seen in our patient may be life-saving, even in the presence of inflammatory signs.

Adult↗
PubMed1994

Valvuloplasty for common atrioventricular valve regurgitation in cyanotic heart diseases.

Valvuloplasty for common atrioventricular valvular regurgitation and bidirectional cavopulmonary shunt were successfully performed in 3 children with univentricular heart and double-outlet right ventricle. The free margins of opposite leaflets of the common atrioventricular valve were sutured together to restore coaptation of the leaflets, and Kay-Reed's or DeVega's annuloplasty was carried out. Postoperative examinations revealed significant reduction of atrioventricular valve regurgitation and improvement of general condition in all patients.

Child↗
PubMed1994

Loss of biological activity of human chorionic gonadotropin (hCG) by the amino acid substitution on the "CMGCC" region of the alpha-subunit.

In order to study the bioactive sites of the glycoprotein hormones, we have prepared five point mutants on the CMGCC (Cys28-Met29-Gly30-Cys31-Cys32) region of the human alpha-subunit by using site-directed mutagenesis. Each mutant human chorionic gonadotropin (hCG) agr; cDNA and a wild-type hCG beta cDNA were transcribed by T3 RNA polymerase, and the mixture of the hCG alpha mRNA and hCG beta mRNA was microinjected into Xenopus laevis oocytes. All five mutant hCGs produced in oocyte culture supernatants were detected as immunoreactive forms by enzyme immunoassay. In contrast, four mutants (Cys28-->Tyr28, Gly30-->Arg30, Ala30, Asp30) were devoid of biological activity in vitro bioassay using the production of testosterone with mouse Leydig cells. These results indicate that the CMGCC region in the alpha-subunit, particularly the cysteine residue at position 28 and the glycine residue at position 30, plays an important role in the biosynthesis of glycoprotein hormones.

Amino Acid Sequence↗
PubMed1994

Selective interferon-alpha/beta effects on platelet-derived growth factor-stimulated processes in quiescent BALB/c-3T3 fibroblasts.

Interferon-alpha/beta (IFN-alpha/beta) suppresses cell cycle activation by platelet-derived growth factor (PDGF) as well as the induction of the 31-kD (pI) and the 35-kD (pII) proteins in density-arrested BALB/c-3T3 cells. We report that elevation of [Ca2+]i by ionomycin induces the synthesis of the 31-kD protein, but not that of the 35-kD protein. Since IFN blocks the PDGF-induced elevation of [Ca2+]i, these results suggest that IFN treatment may suppress pI induction by impairing this PDGF-activated signal transduction pathway. In contrast, because ionomycin did not induce the 35-kD protein, the suppression by IFN of PDGF-induced pII appears to be mediated via a pathway distinct from that operating in the suppression of pI. In BALB/c-3T3 cells, IFN-alpha/beta did not itself affect the turnover or de novo synthesis of inositol phospholipids and the cellular content of diacylglycerol, nor did IFN block the enhancement of these parameters by PDGF.

3T3 Cells↗
PubMed1994

Synergistic antimetastatic effects of lentinan and interleukin 2 with pre- and post-operative treatments.

The antimetastatic activity of a combination of lentinan and interleukin 2 (IL-2) was evaluated against spontaneously metastatic 3-methylcholanthrene-induced DBA/2.MC.CS.T fibrosarcoma. Although pre-operative treatment with either IL-2 or lentinan alone exerted little effect on the reduction of lung metastasis colony numbers (7.1% or 28.4% reduction, respectively), the combination exhibited a synergistic effect (85% reduction). Furthermore, 3 of 13 mice given the pre-operative combination treatment achieved complete cure, while no mice given saline did. Although the post-operative combination treatment also reduced the colony number (71% reduction), it caused little prolongation of survival and no mouse achieved complete cure. Synergistic effects were observed between pre- and post-operative treatments with lentinan and IL-2: 8 of 12 mice were completely cured. The anti-metastatic activity was abolished in mice treated simultaneously with antibodies to CD4 and CD8 antigens, whereas either CD4, CD8, or NK1.1 antibody alone was ineffective. Analysis of the cellular mechanism involved in the antimetastatic activity revealed the involvement of a tumor-associated antigen-specific delayed-type hypersensitivity response. These data suggest that the life-prolonging effect of the combination of lentinan and IL-2 is mediated by antigen-specific T cells and that the combination of pre- and post-operative therapy with lentinan and IL-2 may be effective to prevent cancer recurrence and metastasis after surgical resection.

Animals↗
PubMed1994

Expression and localization of human oxytocin receptor mRNA and its protein in chorion and decidua during parturition.

Oxytocin (OT) is widely used to induce labor in the clinical setting. However, its physiological role in normal human parturition remains unclear. We demonstrated the enhanced expression of OT receptor (OTR) mRNA in chorio-decidual tissue, using the polymerase chain reaction after the reverse transcriptase reaction (RT-PCR) and Northern blot analysis. OTR gene expression in chorio-decidual tissue increased fivefold during the course of parturition. In situ hybridization of fetal membrane revealed the expression of OTR mRNA in maternally derived decidual cells. The OTR mRNA was also detected in fetally derived chorionic trophoblast cells. Immunohistochemistry, using a newly developed anti-OTR monoclonal antibody, demonstrated the distribution of OTR protein in fetal membrane. The distribution pattern of OTR protein and OTR mRNA was identical, indicating that the regulation of OTR expression occurs mainly at the transcriptional level. These results support the idea that the expression of decidual OTR regulates the initiation and amplification of labor. The implications of these findings with regard to the pathogenesis of preterm labor are also discussed.

Base Sequence↗
PubMed1994

Molecular characterization of a cloned human oxytocin receptor.

We describe here the binding and functional properties of a cloned human oxytocin receptor (OTR). We established a transient OTR expression system on COS-1 cells, which do not express vasopressin receptors. With the transfected cells and [3H]oxytocin, the dissociation constant (Kd) of OTR to oxytocin was 6.0 +/- 1.1 nmol/l; the binding properties of several oxytocin-related peptides were also examined. The functional properties of OTR were determined by an electrophysiological method, using a Xenopus laevis oocyte injected with in vitro transcribed OTR mRNA. These two methods showed that [Phe2,Orn8]vasotocin, a vasopressin agonist, was an OTR antagonist. A combination of these methods using cloned OTR cDNA is a novel and effective method for the investigation of oxytocin-related ligands.

Animals↗
PubMed1994

Clinical characteristics in non-insulin-dependent diabetic patients with long duration in Japan--relation to risk factors for vascular complications.

In this study, we evaluated the control state of body weight, blood pressure, and blood glucose during the recent 10 years in 82 patients of non-insulin-dependent diabetes mellitus (NIDDM) who had long duration of diabetes for 20-25 years without ischemic heart disease (IHD) and diabetic nephropathy (Neph). The patients without either IHD or Neph showed significantly lower incidences of obese (11 vs. 40%, p < 0.05), hypertensive (0 vs. 20%, p < 0.05) and poor glycemic control state (7 vs. 27%, p < 0.05) for 10 years than the patients with IHD alone, and showed significantly lower incidences of hypertensive (0 vs. 20%, p < 0.05) and poor glycemic control state (7 vs. 33%, p < 0.01) than the patients with Neph alone. The control state of body weight was similar between the patients without either IHD or Neph and with Neph alone. In addition, the patients without either IHD or Neph showed significantly lower incidences of obese (11 vs. 56%, p < 0.01) and hypertensive control state (0 vs. 40%, p < 0.01) for 10 years than the patients with both IHD and Neph. The control state of blood glucose was similar between the two groups. These results suggest that for long survival of NIDDM patients without development or progression of IHD and Neph, non-obese and non-hypertensive state as well as good glycemic control should be maintained for long time.

Aged↗
PubMed1994

Lipoprotein(a) as an independent risk factor for diabetic retinopathy in male patients in non-insulin-dependent diabetes mellitus.

Relationship of the lipoprotein(a) [Lp(a)] concentration as a risk factor independent of other factors with the severity of diabetic retinopathy were evaluated by multiple regression analysis. The subjects were 158 patients with non-insulin-dependent diabetes mellitus (NIDDM). Multiple regression analysis was carried with the severity of diabetic retinopathy as the dependent variable and 13 independent variables, namely the Lp(a) concentration, sex, age, body mass index, duration of diabetes, ischemic heart disease, fasting plasma glucose, glycosylated hemoglobin A1c, total cholesterol, triglyceride, high-density lipoprotein cholesterol, anti-diabetic treatments, and diabetic nephropathy. The analysis was performed separately in all subjects, males only, and females only. The standard partial regression coefficient of Lp(a) was significant (0.293, p < 0.01), and the multiple correlation coefficient was 0.611 in the males. However, the standard partial correlation coefficient of Lp(a) was not significant in all patients and in females only. The rank of contribution of Lp(a) to retinopathy was the third in males, following triglyceride and nephropathy and followed by anti-diabetic treatments. These results suggest that Lp(a) might be an independent risk factor for diabetic retinopathy in male patients with NIDDM.

Aged↗
PubMed1994

Three types of "mid-band" lipoproteins in non-insulin-dependent diabetes mellitus: relation to metabolic abnormalities and vascular complications.

A number of fine bands which occur in positions between the beta- and pre-beta-lipoproteins in polyacrylamide gell electrophresis are called mid-bands (MB). In this study, the relationship between the occurrence of these MB and metabolic abnormalities or vascular complications was evaluated in 181 patients with non-insulin-dependent diabetes mellitus (NIDDM). The incidence of MB in diabetic patients was significantly higher than that in 149 healthy control subjects (35 vs. 20%, p < 0.01). Analysis according to the type of MB revealed that the incidence of the central type in diabetic patients was significantly higher than that in healthy control subject (11 vs. 5%, p < 0.05). When the values of HbAlc were elevated, the incidence of MB and its central type slightly increased. The occurrence of the lower type of MB showed no relationship with the levels of HbAlc. The incidence of MB and its central type were significantly higher in patients with type IIb hyperlipidemia (86 and 41%, respectively) and with type IV hyperlipidemia (63 and 25%) than in those with normolipidemia (21 and 5%) (p < 0.01 of all). The incidence of the lower type of MB was significantly higher in patients with type IIa hyperlipidemia (25%) and with type IIb hyperlipidemia (36%) than in those with normolipidemia (11%) (p < 0.05, p < 0.01, respectively). There was no significant difference in the occurrences of MB and of the central and lower types of MB between the normolipidemic patients and healthy control subjects. The incidence of MB and its central type were significantly higher in patients with nephropathy (54 and 23%, respectively) than in those without nephropathy (32 and 9%) (p < 0.05 of all). There was no significant difference in the incidence of lower type of MB between patients with and without nephropathy. These results indicate that the incidence of central type of MB may be high in NIDDM, and that the occurrence of central type may be associated with abnormal metabolism of glucose or lipid and with diabetic nephropathy.

Aged↗
PubMed1994

Different change in lipoprotein(a) levels from lipid levels of other lipoproteins with improved glycemic control in patients with NIDDM.

OBJECTIVE: To evaluate change both in lipoprotein(a) [Lp(a)] and lipid levels in other lipoproteins in non-insulin-dependent diabetes mellitus (NIDDM) after short-term improvement of glycemic control. RESEARCH DESIGN AND METHODS: We compared Lp(a) levels in 210 NIDDM patients with those in 46 control subjects and evaluated the relationship between glycemic control and Lp(a) levels in diabetic patients. In addition, changes in Lp(a) levels and lipid levels were assessed after the improvement of glycemic control in 54 poorly controlled NIDDM patients. RESULTS: In NIDDM, Lp(a) levels in all patients, 62 patients with HbA1c < 6.0%, and 75 patients with HbA1c between 6.0 and 8.0%, were significantly higher than those in control subjects (19.1 [1.7-106.6], 19.2 [6.0-106.6], and 20.3 [2.7-75.3] vs. 15.4 [2.0-61.7] mg/dl, median [range], P < 0.05). Lp(a) levels in 73 patients with HbA1c of > or = 8.0% (18.7 [1.7-58.8] mg/dl) were not significantly different from those in control subjects. After glycemic control, lipid levels in plasma and in other lipoproteins fell significantly, but Lp(a) did not change (from 18.3 [1.7-58.8] to 18.4 [6.6-95.3] mg/dl). Changes in lipid levels, including Lp(a), did not correlate with those in fasting plasma glucose or HbA1c. CONCLUSIONS: These results suggest that elevated Lp(a) levels do not reflect poor glycemic control and that Lp(a) levels are independent of lipid levels in other lipoproteins after improved glycemic control in NIDDM.

Blood Glucose↗