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Biomedical subjects

K Aoki

Publications and source records attributed to K Aoki.

At least 307 records · Page 17Linked to original sources
PubMed1997

Day-night variation of pituitary adenylate cyclase-activating polypeptide (PACAP) level in the rat suprachiasmatic nucleus.

Adenylate cyclase-activating polypeptide (PACAP) is synthesized in the retinal ganglion cells which terminate on vasoactive intestinal polypeptide neurons in the suprachiasmatic nucleus (SCN), the location of circadian clock. To examine whether PACAP exhibits daily variations in the rat SCN, we measured endogenous PACAP contents throughout the day under 12:12 h light-dark or constant dark conditions. PACAP level was low during the light periods, high during the dark periods, and was stable under constant dark conditions. In the periventricular nucleus of the hypothalamus and cerebral cortex, PACAP content did not show any significant variation throughout the day. Our findings suggest that PACAP content in the SCN may be changed by lighting conditions. Thus, PACAP-containing neurons may play certain roles in the entrainment of circadian rhythms.

Animals↗
PubMed1997

Gene therapy for peritoneal dissemination of pancreatic cancer by liposome-mediated transfer of herpes simplex virus thymidine kinase gene.

Peritoneal dissemination is one of the most common complications of the malignancies of the digestive system, such as gastric or pancreatic cancers. Yet, no effective therapy has been established so far to alleviate this devastating and often fatal end-stage condition. Here we describe a novel approach of intraperitoneal (i.p.) lipofection of a suicidal gene to the pancreatic cancer cells in a mouse peritoneal dissemination model. A human pancreatic cancer cell line, PSN-1, was inoculated into the peritoneal cavity of nude mice. Eight days later, a herpes simplex virus thymidine kinase (HSV-TK) gene expression plasmid under a potent hybrid promoter CAG was injected as a DNA-lipopolyamine complex. Ganciclovir (GCV) was then administered for 8 days, and the mice were examined for tumor development at the 24th day after the tumor inoculation. Although all 24 control mice showed macroscopic peritoneal dissemination and solid tumors on the pancreas, 8 of the 14 mice treated with HSV-TK and GCV were free of tumors, and only a few small tumors were observed in the remaining 6 mice. Treatment-related toxicity was not observed. The semiquantitative reverse transcription polymerase chain reaction (RT-PCR) analysis suggested that the HSV-TK transgene was expressed in about 10% of tumor cells but not in the normal pancreas or in the small intestine. When the lacZ gene was transduced in place of the HSV-TK gene, the blue-stained cells were identified only in tumor nodules and not in normal organs. This preclinical study suggests the therapeutic feasibility of the i.p. lipofection-based suicidal gene/prodrug strategy for peritoneal dissemination of pancreatic cancer.

Animals↗
PubMed1997

Novel genes encoding 2-aminophenol 1,6-dioxygenase from Pseudomonas species AP-3 growing on 2-aminophenol and catalytic properties of the purified enzyme.

2-Aminophenol 1,6-dioxygenase was purified from the cell extracts of Pseudomonas sp. AP-3 grown on 2-aminophenol. The product from 2-aminophenol by catalysis of the purified enzyme was identified as 2-aminomuconic 6-semialdehyde by gas chromatographic and mass spectrometric analyses. The molecular mass of the native enzyme was 140 kDa based on gel filtration. It was dissociated into molecular mass subunits of 32 (alpha-subunit) and 40 kDa (beta-subunit) by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, indicating that the dioxygenase was a heterotetramer of alpha2beta2. The genes coding for the alpha- and beta-subunits of the enzyme were cloned and sequenced. Open reading frames of the genes (amnA and amnB) were 816 and 918 base pairs in length, respectively. The amino acid sequences predicted from the open reading frames of amnA and amnB corresponded to the NH2-terminal amino acid sequences of the alpha-subunit (AmnA) and beta-subunit (AmnB), respectively. The deduced amino acid sequences of AmnB showed identities to some extent with HpaD (25.4%) and HpcB (24.4%) that are homoprotocatechuate 2,3-dioxygenases from Escherichia coli W and C, respectively, belonging to class III in the extradiol dioxygenases. On the other hand, AmnA had identity (23.3%) with only AmnB among the enzymes examined.

Amino Acid Sequence↗
PubMed1997

The translin ring specifically recognizes DNA ends at recombination hot spots in the human genome.

We previously showed that consensus sequences exist at the chromosomal breakpoints in lymphoid malignancies and that these sequences are specifically recognized by a novel DNA binding protein, Translin. In the present study, the native form of Translin was established to be a ring-shaped structure by electron microscopy and crystallographic studies. It was also determined that this multimeric Translin formed by the subunits is responsible for its binding to target sequences situated only at single-stranded DNA ends. Furthermore, DNA-damaging reagents were found to initiate a signaling pathway for the active nuclear transport of Translin. The results support the hypothesis that staggered breaks occur at recombination hot spots and Translin has a pivotal function in recognition of the generated single-stranded DNA ends.

Binding Sites↗
PubMed1997

Presence of UDP-D-xylose: beta-D-glucoside alpha-1,3-D-xylosyltransferase involved in the biosynthesis of the Xyl alpha 1-3Glc beta-Ser structure of glycoproteins in the human hepatoma cell line HepG2.

HepG2 cells were examined for the presence of UDP-D-xylose: beta-D-glucoside alpha-1,3-xylosyltransferase activity by using 2-[(2-pyridyl)amino]ethyl beta-D-glucopyranoside (Glc beta-R) as a fluorogenic acceptor. UDP-D-xylose and the acceptor were incubated with the HepG2 microsomal fraction, and the enzymatic reaction mixture was analyzed by HPLC. Structural analysis of the fluorogenic product by alpha-D-xylosidase digestion, FAB-MS, and Smith degradation revealed that it was Xyl alpha 1-3Glc beta-R, thus demonstrating the existence of beta-D-glucoside alpha-1,3-xylosyltransferase. A solubilization study of the enzyme from the microsomal fraction indicated that it differed from UDP-D-xylose: alpha-D-xylodie alpha-1,3-xylosyltransferase of the HepG2 microsomal fraction producing Xyl alpha 1-3Xyl alpha 1-3Glc-R' [R', (2-pyridyl)amino-] from UDP-D-xylose and Xyl alpha 1-3Glc-R' [Minamida, S., Aoki, K., Natsuka, S., Omichi, K., Fukase, K., Kusumoto, S. & Hase, S. (1996) J. Biochem. (Tokyo) 120, 1002-1006]. The newly detected enzyme appears to be involved in the biosynthesis of the Xyl alpha 1-3Glc beta-Ser structure of glycoproteins such as human blood coagulation factors VII and IX.

Carcinoma, Hepatocellular↗
PubMed1997

Cloning of human bone morphogenetic protein type IB receptor (BMPR-IB) and its expression in prostate cancer in comparison with other BMPRs.

Bone metastasis is a common event in prostate cancer, and it is known that some of the bone morphogenetic proteins (BMPs) are expressed in prostate cancer cells, while no study on the expression of their receptors, BMPRs, has been reported. Here we report cloning and sequence analysis of the human BMPR-IB cDNA. We also analysed the expression of transcripts of three types of the BMPR genes in human tissues and prostate cancer cell lines. The BMPR-IB mRNA was present in various organs, but the highest level was found in the prostate. Moreover, the amount of BMPR-IB mRNA was significantly low in prostate cancer tissues after androgen withdrawal and was also low in prostate cancer cell lines. RT-PCR analysis showed that the BMPR-IB message was upregulated by androgen stimulation in the LNCaP cell line which expresses the androgen receptor. By contrast, the mRNA levels of BMPR-IA and BMPR-II were not significantly different among non-cancerous and cancerous prostate tissues. It was also suggested that human BMPR-IA and BMPR-IB might have different biological functions in the prostate, although their sequences were 85.3% identical in the serine-threonine kinase domain.

Amino Acid Sequence↗
PubMed1997

Classification of catechol 1,2-dioxygenase family: sequence analysis of a gene for the catechol 1,2-dioxygenase showing high specificity for methylcatechols from Gram+ aniline-assimilating Rhodococcus erythropolis AN-13.

Gram+ aniline-assimilating Rhodococcus erythropolis AN-13 (AN-13) produces catechol 1,2-dioxygenase (C12O) showing high enzymatic activities for 3- and 4-methylcatechols [Aoki et al. (1984) Agric. Biol. Chem. 48, 2087-2095]. A 3.0 kb Sau3AI fragment carrying a gene encoding C12O(catA) was cloned by selection of transformants showing C12O activity from a gene library of AN-13. Furthermore, we specified a 1.6 kb SalI fragment containing catA from the Sau3AI fragment by subcloning. Sequence analysis revealed that the 1.6 kb SalI fragment carried a 855 bp open reading frame (ORF) encoding the entire AN-13 catA, preceded by a potential ribosome binding site (RBS). From comparison of the deduced amino acid (aa) sequence of C12O from AN-13 with other C12O reported previously, it was found that the AN-13 enzyme shares 56.0% aa sequence identity with C12o from Arthrobacter sp. mA3 (mA3) [Eck and Belter (1991) Gene 123, 87-92] compared with less than 36.4% aa sequence identities with others. In conclusion, we classified all C12O including the AN-13 enzyme into three subfamilies on the basis of similarity of aa sequences, numbers of aa residues, and substrate specificity.

Amino Acid Sequence↗
PubMed1997

Isolation and characterization of a cDNA encoding a Translin-like protein, TRAX.

Translin is a DNA binding protein which specifically binds to consensus sequences at breakpoint junctions of chromosomal translocations in many cases of lymphoid malignancies. To investigate its functional significance at such recombination hotspots, we examined whether Translin interacts with other proteins using a yeast two-hybrid system and identified an associated 33 kd protein partner, TRAX, with extensive amino acid homology. The TRAX protein was established to contain bipartite nuclear targeting sequences in its N-terminal region, suggesting a possible role in the selective nuclear transport of Translin protein lacking any nuclear targeting motifs.

Amino Acid Sequence↗
PubMed1997

Time course of tolerance to ischemia-reperfusion injury and induction of heat shock protein 72 by heat stress in the rat heart.

We compared the time course of tolerance to myocardial ischemia-reperfusion injury with the time course of heat shock protein 72 (hsp72; inducible form) induction after heat stress in a rat model. The size of the infarct resulting from ischemia-reperfusion was increased 12 h after whole-body hyperthermia (42 degrees C for 15 min), but was significantly decreased 48 and 72 h after hyperthermia, compared with the sham control. The infarct size was decreased as late as 96 h after hyperthermia, although the infarct-limiting effect was smaller at that time. The myocardial content of hsp72 was markedly increased for 3-72 h after hyperthermic treatment, and was decreased after 72 h in association with an increase in the infarct size. The hsp72 content remained elevated during the period of tolerance to ischemia-reperfusion injury, but the infarct size decreased after the hsp72 content peaked. Pretreatment with a protein kinase C (PKC) inhibitor, chelerythrine chloride, immediately before hyperthermia, significantly suppressed the delayed cardioprotective effect of hyperthermia and reduced hsp72 induction. These results suggest that newly synthesized hsp72 through PKC activation after heat stress may have to be post-translationally modified and compartmentalized prior to assuming to the development of the delayed tolerance to ischemia-reperfusion injury in rats.

Animals↗
PubMed1997

Are serum progesterone levels predictive of recurrent miscarriage in future pregnancies?

OBJECTIVE: To examine the predictive value of midluteal serum P as a marker of a luteal phase defect (LPD) in future pregnancies of recurrent aborters. DESIGN: Prospective analysis. SETTING: Nagoya City University Hospital. PATIENT(S): One hundred ninety-seven women with a history of two consecutive first trimester abortions, none of whom had any other medical problems or an identifiable cause of recurrent miscarriages, such as uterine anomalies or evidence of antiphospholipid antibodies. None of the study subjects received any medication for miscarriage or infertility. MAIN OUTCOME MEASURE(S): A midluteal phase single serum P level < 10 ng/mL was used as the criterion for a potential LPD: those whose subsequent pregnancy was successful and those in which failure was the end result. RESULT(S): Of the 197 patients, 46 (23.4%) demonstrated LPD without other endocrine abnormalities and 38 (19.3%) recurrent aborters suffered another abortion, with figures for LPD-negative and LPD-positive patients of 20.5% (31/151) and 15.2% (7/46), respectively. There was no statistically significant difference between the two groups. CONCLUSION(S): Progesterone, E2, and the P/E2 ratio may not predict future pregnancy loss in recurrent aborters.

Abortion, Habitual↗
PubMed1997

Vascular angiotensin-converting enzyme activity in cholesterol-fed rabbits: effects of enalapril.

Many reports have shown inhibitory effects of angiotensin-converting enzyme (ACE) inhibitors on the progression of atherosclerotic plaque lesions in vascular tissue of experimental models. However, no report has shown alterations of ACE activity in vascular tissue during the process of atherosclerosis. We measured ACE activity in plasma and aortic tissue in rabbits fed a cholesterol-rich (1%) or normal diet for 10 weeks. We also evaluated the blood pressure response to angiotensin (Ang) I and II. These data were compared in untreated rabbits and in rabbits receiving chronic treatment with an ACE inhibitor, enalapril (3 mg/kg/day for 10 weeks). ACE activity in aortic tissue, but not in plasma, in cholesterol-fed rabbits was gradually but significantly increased compared with that in noncholesterol-fed rabbits even after the 4-week feeding period, when no atherosclerotic lesion was observed in the aortic tissue. Treatment with enalapril for 10 weeks, but not 4 weeks, significantly reduced the ACE activity in aortic tissue in association with the reductions in the elevated Ang II level and the atherosclerotic plaque area of the aortic tissue. These results indicated that ACE activity in aortic tissue was increased during the early phase of atherosclerotic process.

Angiotensin I↗
PubMed1997

Rapid diagnosis of adenoviral conjunctivitis on conjunctival swabs by 10-minute immunochromatography.

PURPOSE: Several methods are available for the diagnosis of acute conjunctivitis, all of which are time-consuming or require the use of a well-equipped laboratory. A new method, immunochromatography (IC), for detecting the presence of adenovirus (Ad) has been developed. Two direct rapid tests to detect Ad antigen, IC and enzyme immunoassay (EIA), were compared with regard to sensitivity, specificity, and technical complexity. METHODS: The study materials consisted of 130 swabs from patients with conjunctivitis (95 samples of adenoviral conjunctivitis proven by positive virus DNA on polymerase chain reaction [PCR], 35 samples of nonadenoviral conjunctivitis proven by PCR). IC is a one-step procedure that detects the presence of adenoviral antigen by sandwich EIA on a paper disc. RESULTS: In 95 adenoviral DNA-positive samples by PCR, the sensitivity and specificity of IC were 54.7% and 97.1%, respectively, whereas those of EIA were 50.5% and 100%, respectively. By IC, PCR-positive Ad type 3 was recognized in 31%; Ad4 in 100%; Ad7 in 60%; Ad8 in 67%; and Ad37 in 59%, showing similar positivity rates for different serotypes (except Ad7) to those using EIA. Visual determination of the presence of Ad took an average of 10 minutes by IC compared with 70 minutes by EIA. CONCLUSIONS: These results indicate that IC is a more rapid and easier test compared with EIA, and it has high specificity. Detection of Ad antigen by this simple and rapid method will serve physicians as a useful tool for early diagnosis and prevention of adenoviral conjunctivitis.

Adenoviridae↗
PubMed1997

A high level of accumulation of 2-hydroxymuconic 6-semialdehyde from aniline by the transpositional mutant Y-2 of Pseudomonas species AW-2.

Four transpositional mutants of aniline-assimilating Pseudomonas sp. AW-2 produced 2-hydroxymuconic 6-semialdehyde (HMS) from aniline and accumulated it in a cultural medium. Among the four mutants, strain Y-2 produced the greatest amount of HMS (0.77 mg/ml) from 1 mg/ml of aniline hydrochloride in a 15-h growing culture. The conversion rate of aniline to HMS was 70% on a molar basis. Resting cells of strain Y-2 produced 0.65 mg/ml of HMS during 4h of incubation in a reaction mixture containing 1 mg/ml of aniline hydrochloride (conversion rate, 60%). Transposon Tn5-Mob was found to be inserted into the gene of HMS dehydrogenase in strain Y-2 by sequence analysis.

Alcohol Oxidoreductases↗
PubMed1997

Familial aggregation and covariation of diseases in a Japanese rural community: comparison of stomach cancer with other diseases.

PURPOSE: We investigated familial aggregation as well as familial covariation of diseases by means of a questionnaire survey dealing with family histories of stomach cancer, stroke, hypertension, diabetes and tuberculosis as well as life style among 2,769 inhabitants of a rural community (84% of census population). METHODS: The strength of familial aggregation was shown by an odds ratio (OR) that compared the number of families in which siblings suffered from one of the above diseases among families in which at least one parent suffered from it, and among families in which neither did. Probands were divided into two groups for analysis: an under-55 "young group," and a 55-and-older "old group." RESULTS: The OR for stomach cancer was lowest and insignificant in the young group, and significant (2.2, p < 0.05) only in the old group. The OR for stroke, hypertension, and tuberculosis was 4.5-5.1 (p < 0.05) in the young group but decreased to 2.3-3.2 in the old group. Diabetes increased from 3.9 to 5.7 (p < 0.05) with advancing age. Age-related OR trends were not affected by exposure to cigarette smoke in the past. Stomach cancer showed a borderline familial covariation with diabetes and a borderline inverse covariation with hypertension. Hypertension showed a familial covariation with stroke and diabetes. CONCLUSIONS: Among the investigated diseases, familial aggregation was weakest for stomach cancer. The results suggest that stomach cancer may share a common familial etiologic factor with diabetes and hypotension.

Adult↗
PubMed1997

Effects of surface roughness of titanium implants on bone remodeling activity of femur in rabbits.

We investigated the bone remodeling activity on titanium implants with different surface roughnesses using a confocal laser scanning microscope (CLSM). Two kinds of implants were used, the machined smooth-surfaced titanium and the plasma-sprayed rough-surfaced titanium. These implants were randomly inserted in a rabbit's femur from the lateral aspect of the diaphysis bicortically. Rabbits were killed at 6, 16, and 42 weeks after surgery. The implant-bone blocks were embedded in polyester resin, and were prepared to make undecalcified ground sections. Histomorphometric analyses were performed at the cortical bone-implant interface using the image obtained by CLSM. Percentages of direct bone-implant contact and bone volume (BV/TV) around the implant was greater in rough-surfaced titanium compared with the smooth-surfaced titanium at 42 weeks after implantation. On the contrary, the eroded surface (ES/BS) appeared to be less in the rough-surfaced titanium than in the smooth-surfaced titanium at 6 weeks after implantation, but thereafter, no difference was found between the two kinds of implants. Mineralizing surface (MS/BS) and mineral apposition rate (MAR) showed no significant differences throughout the experimental period. These results indicate that increased bone volume in the rabbits of rough-surfaced titanium implants is due to less remodeling activity during the early stage after implantation compared with the smooth-surfaced implants. The surface roughness of titanium is one factor which helps in determining the balance between bone formation and resorption of remodeling at the interface of the bone implants.

Animals↗
PubMed1997

Clinical trial of immunostimulation with a biological response modifier in unexplained recurrent spontaneous abortion patients.

We determined clinically whether a killed streptococcal preparation (KSP), a biological response modifier, is as effective as paternal lymphocyte immunotherapy for unexplained recurrent pregnancy abortion (RSA) therapy. The success rate of adverse pregnancy in the study group of 23 RSA cases, who were administered low doses of KSP before and during early pregnancy, was statistically compared with that in a control group of 205 women who received paternal lymphocyte immunotherapy. The association of natural killer (NK) cell activity in the peripheral blood with pregnancy outcome was also assessed. The success rate in the study group was 73.9% (17/23), compared to 75.1% (154/ 205) observed for the controls (not significant). Most of the successful cases exhibited low levels of NK cell activity in the peripheral blood. Immunotherapy with low doses of KSP is as effective as that with paternal lymphocytes, providing a simple and safe alternative therapy for unexplained RSA. Suppression of NK cell activity by some immunoregulatory mechanism was also found to have potential benefit in terms of a successful pregnancy outcome.

Abortion, Habitual↗
PubMed1997

Effects of reduced muscle temperature on the oxygen uptake kinetics at the start of exercise.

The purpose of this study was to examine the effects of reduced muscle temperature (Tm) on gas exchange kinetics and haemodynamics at the start of exercise. Six male subjects performed moderate cycle exercise under reduced (C) and normal (N) Tm conditions. Tm and rectal temperature were significantly reduced by immersion in cold water (by 6.6 degrees C and 1.8 degrees C, respectively). The increases in oxygen uptake (Vo2) and oxygen pulse (Vo2/HR) during phase 1 (abrupt increase after the start of exercise) were significantly lower under C than under N. The time constant for O2 under C (36.0 +/- 7.7 (SD)s) was significantly greater than under N (27.5 +/- 4.4 s); however, the time constants of cardiac output under C (38.3 +/- 16.6 s) and N (33.7 +/- 18.5 s) were similar. These results suggest that the slower Vo2 on-response under reduced Tm conditions is caused by decreased O2 extraction in working muscle and/or by impairment of oxidative reactions by reduced muscle temperature.

Adult↗