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Biomedical subjects

K Kondo

Publications and source records attributed to K Kondo.

At least 451 records · Page 25Linked to original sources
PubMed1994

Morphology of the viable but nonculturable Vibrio cholerae as determined by the freeze fixation technique.

The morphology of the nonculturable Vibrio cholerae strain TSI-4 was examined by the freeze fixation technique of electron microscopy and subsequently four unique structures were found in the fine structure s of this bacterium. The size of the cell was about 2/3 of the growing cell. Although the cell was observed to have an outer membrane as well as the cell membrane and cytoplasm, the outer membrane was undulated and had a surface layer of fine fibers. The peptidoglycan layer was thick and more electron dense than that of normal cells.

Cell Wall↗
PubMed1994

Somatic mutations of the von Hippel-Lindau tumor suppressor gene in sporadic central nervous system hemangioblastomas.

Hemangioblastoma is one of the benign tumors in the central nervous system. It is often associated with the von Hippel-Lindau (VHL) disease, a well known hereditary tumor syndrome. It is believed that inactivation of both alleles of VHL tumor suppressor gene is essential in the tumorigenic processes in hemangioblastomas associated with VHL disease. The molecular basis for the development of sporadic hemangioblastomas is not known. Here, we analyzed 13 cases of primary sporadic hemangioblastomas for somatic mutations of VHL gene with single strand conformational polymorphism analyses of the tumor DNAs. We detected abnormal single strand conformational polymorphism pattern in 7 tumors (54%). Of these 7 possibly mutated tumors, we successfully characterized 3 tumors by direct sequencing. We were unable to sequence 4 tumors because of the poor quality of DNA obtained from paraffin blocks. Somatic mutations in the 3 tumors were 2 missense mutations and 1 microdeletion. These mutations were observed in 1 tumor in exon 1 and 2 tumors in exon 2. Our results suggest that mutations of VHL tumor suppressor gene are involved in the development of at least 20% of sporadic central nervous system hemangioblastomas.

Base Sequence↗
PubMed1994

Frequent somatic mutations and loss of heterozygosity of the von Hippel-Lindau tumor suppressor gene in primary human renal cell carcinomas.

We analyzed 47 primary sporadic human renal cell carcinomas (39 clear cell and 8 non-clear cell) for mutations of the von Hippel-Lindau (VHL) tumor suppressor gene using the polymerase chain reaction and single strand conformational polymorphism analysis of DNA. All of the positive cases in single strand conformational polymorphism analyses were further characterized by direct sequencing. Somatic mutations were detected in 22 (56%) of 39 clear cell renal carcinomas including 15 deletions, 3 insertions, 3 missense mutations, and 1 nonsense mutation. Nineteen of these mutations predicted to produce truncation of the VHL protein. These mutations mainly occurred in the last one-third region of exons 1, 2, and 3. In addition, loss of heterozygosity of the VHL gene was observed in 16 (84%) of 19 informative clear cell renal carcinomas. No somatic mutations were detected in 8 non-clear cell carcinomas. These results show that the VHL tumor suppressor gene is one of the major tumor suppressor genes in human renal cell carcinomas, especially in the clear cell subtype renal cell carcinoma. Clear cell carcinoma might be distinguished from other pathological types of renal cell carcinomas by molecular genetic techniques.

Base Sequence↗
PubMed1994

The transition of alpha-helix to beta-structure of poly(L-lysine) induced by phosphatidic acid vesicles and its kinetics at alkaline pH.

Static and dynamic circular dichroism (CD) measurements were carried out for poly(L-lysine) in suspensions of dilauroylphosphatidic acid (DLPA) vesicles at alkaline pH (8-11.5). The static experiments demonstrated that the alpha-helix of poly(L-lysine) induced by deprotonation in alkaline solutions is transformed to beta-structure by the addition of DLPA vesicles. Stopped-flow CD measurements for such order-to-order transition revealed that the rate determining step is the unfolding process of alpha-helix to random coil. Previously, we have reported the conformational change of poly(L-lysine) induced by DLPA vesicles at neutral pH, where the beta-structure transition from random coil was observed. Thus two types of transition of poly(L-lysine) are observed depending on bulk pH, i.e., from random coil to beta-structure and from alpha-helix to beta-structure. So far the phospholipid-induced conformations of poly(L-lysine) were interpreted in terms of counterbalance between the positively charged terminals of the lysyl chains and the negative headgroups of the phospholipid in vesicle. However, present work indicates the direct interaction other than electrostatic interaction between the lysyl chain and phosphate groups of the lipid.

Circular Dichroism↗
PubMed1994

Identification of cis- and trans-acting elements involved in the expression of cold shock-inducible TIP1 gene of yeast Saccharomyces cerevisiae.

Northern blot hybridization analysis of a series of 5' end, 3' end and internal deletions has revealed that at least four different regions are involved in the regulation of the expression of TIP1, a cold shock-inducible gene of Saccharomyces cerevisiae. One of these four regions has negative effect on the expression of the TIP1 gene, while the others are responsible for the activation and cold shock-induction of the gene. A fragment involved in the cold-shock induction of TIP1 was used as a probe in gel retardation assays to identify the cold shock-factor. The cold shock-factor could be detected in cells grown at 30 degrees C as well as 10 degrees C, but both the amount of the factor and its affinity to DNA were found to increase 2-3-fold after cold shock. In addition, another factor was found to bind just upstream of the cold shock element, in a region where a transcriptional activator was predicted to function by Northern blot hybridization analysis. The amount of this activating factor and its affinity for DNA was not affected by temperature. Implications of our data on possible mechanisms of transcriptional regulation of the TIP1 gene by cold shock are discussed.

Base Sequence↗
PubMed1994

Construction of a brewer's yeast having alpha-acetolactate decarboxylase gene from Acetobacter aceti ssp. xylinum integrated in the genome.

alpha-Acetolactate decarboxylase (ALDC) gene from Acetobacter aceti ssp. xylinum has several possible initiation codons in the N-terminus. To determine the initiation codon of the ALDC giving the highest expression levels, glyceraldehyde-3-phosphate dehydrogenase (GPD) promoter was linked just upstream of each possible initiation codon. The ALDC whose translation starts 130 bp downstream from the first ATG codon had the highest activity in yeast cells. When expression levels of the ALDC gene were compared using three strong yeast promoters of glycolytic genes, alcohol dehydrogenase I (ADC1), phosphoglycerate kinase (PGK) and GPD, the GPD promoter was the strongest. The ALDC gene was integrated in a ribosomal RNA gene of a brewer's yeast by co-transformation with an expression plasmid of G418-resistance gene. The laboratory-scale growth test confirmed that the total diacetyl concentration was reduced in wort.

Base Sequence↗
PubMed1994

Interaction between genetic and environmental risk factors for Alzheimer's disease: a reanalysis of case-control studies.

To study the interaction among genetic and environmental risk factors, a reanalysis of case-control studies of Alzheimer's disease (AD) was conducted based on the original data of all studies carried out to January 1, 1990. Seven studies were included in the present analysis, comprising a total of 814 AD patients and 894 control subjects. When comparing those with a positive and negative family history of dementia, similar odds ratio were found for late maternal age [1.7; 95% confidence interval (0.6-4.8) vs. 2.0 (1.1-3.5)], head trauma [1.7 (0.7-4.2) vs. 1.9 (1.1-3.2)], and history of depression [2.0 (0.2-19.8) vs. 2.1 (0.8-1.7)]. This suggests a model in which these risk factors increase the risk for AD independent of family history of dementia. Among those with a positive family history of dementia, the odds ratios for family history of Down's syndrome [4.2 (0.9-20.0)] and of Parkinson's disease [3.3 (0.4-28.2)] tended to be higher than among those with a negative family history of dementia [2.6 (0.8-8.5) and 2.4 (0.8-7.0), respectively]. However, for both disorders the difference in odds ratio was not statistically significant. For history of cigarette smoking, there was no association to AD for those with no first degree relatives with dementia and an inverse relation with AD for those with a positive family history. Although in all analyses, family history of dementia remained significantly associated with AD in the absence of other factors, the odds ratio associated with family history of dementia tended to be lower for those with a positive smoking history, particularly for those with two or more affected relatives. These findings suggest that smoking may interact specifically with a genetically determined process.

Aged↗
PubMed1994

Investigation of varicella-zoster virus DNA by the polymerase chain reaction in healthy children with varicella vaccination.

Investigation of varicella-zoster virus (VZV) DNA in 20 healthy children with varicella vaccination was carried out by using the polymerase chain reaction (PCR) and nested double PCR. Samples of peripheral blood mononuclear cells (PBMC) and throat swabs were simultaneously collected 3 times (before, 1 week, and 4 weeks after vaccination) for PCR analysis. One sample of PBMC was also obtained from each of the 12 healthy children with varicella during the acute phase as a positive control. VZV DNA was not found by the first PCR in any samples except one PBMC of a control subject. The nested double PCR, which is a more sensitive method for VZV DNA detection, was applied to the same samples. The viral DNA was detected in every PBMC of the controls, and in 2 (16.7%) PBMC at 1 week and in 6 (50%) PBMC at 4 weeks after vaccination in the 12 vaccinees with seroconversion. In 3 of 4 vaccinees who were seropositive before vaccination, VZV DNA was detected in PBMC at 1 or 4 weeks after vaccination. The three vaccinees showed a booster immunization with a significant increase in antibody titers. In contrast, no VZV DNA could be detected in any throat swabs of all the vaccinees nor in PBMC of the vaccinees who did not seroconvert.

Ambulatory Care Facilities↗
PubMed1994

Molecular epidemiological studies of human herpesvirus 6 in families.

The mode of transmission of human herpesvirus 6 (HHV-6) was investigated by molecular epidemiological techniques in four families. HHV-6 was isolated from the peripheral blood of seven infants with exanthem subitum, including siblings, and from the saliva of two mothers. These isolates were examined for genetic relatedness by means of restriction enzymes analysis of purified DNA. While the profiles of the digestion patterns differed among families, they were very similar in a particular family. These results may suggest that HHV-6 is transmitted primarily from mother to child.

Adult↗
PubMed1994

Measurement of temafloxacin in human scalp hair as an index of drug exposure.

Scalp hair samples were obtained at 1-month intervals up to 3 months from healthy male volunteers participating in a phase I study of a new antimicrobial quinolone, temafloxacin. Hair was sectioned into 1-cm lengths from the scalp end. After corresponding portions from 10 pieces of hair were dissolved in 1 N NaOH, temafloxacin was extracted by chloroform and measured by HPLC equipped with fluorescence detection (excitation and detection wavelengths, 280 and 460 nm, respectively). In all subjects taking a single oral dose (600 mg; n = 6) or repeated oral doses (900 mg/day, b.i.d., for 6.5 days; total, 5850 mg; n = 6), the drug was detected in hair. The 1-cm length of hair, in which temafloxacin was peaked, was shown to move at the rate of 1 to 1.3 cm/month when the hair of growing stage was analyzed. The largest sum of the concentrations of temafloxacin found in any set of measurements in hair in each subject was 31.7 +/- 15.0 (mean +/- SD, n = 6) and 226.3 +/- 99.4 ng/mg hair (n = 6) for the single and repeated doses, respectively. The drug concentration in hair increased by a factor of 7.1, whereas the ratios between the single and repeated doses were 9.8, 1.3, and 10.7 for the total given dose, observed maximal plasma concentration (Cmax), and area under the plasma concentration curve, respectively. It was obvious that the Cmax was the least likely factor determining temafloxacin concentration in hair.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

p53 alteration correlates with negative ER, negative PgR, and high histologic grade in breast cancer.

Seventy tumors of invasive ductal carcinoma of the breast were examined for p53 alteration by the RT-PCR-SSCP method. Sixty-five samples (92.9%) were investigated in the regions of codons 101-200 and 201-300. In total, 16 samples (24.6%) showed p53 gene alteration. We found that p53 gene alteration showed a correlation with (1) a negative ER status, (2) a negative PgR status, and (3) a high histologic grade (especially numerous mitotic figures) of the tumor. However, we found no correlation between p53 gene alteration and the lymph node status or clinical stage. Thus, p53 gene alteration in breast cancer may occur in highly malignant breast cancer other than advanced clinical stage cancer or node-positive cancer.

Adult↗
PubMed1994

Magnesium distribution in human bone.

The present study was undertaken to reveal the magnesium distribution in human bone. Sixty human ribs, obtained from subjects aged 10-80 years of age, were used. Transverse sections were prepared from the middle region of the human ribs. Adjacent sections were ground to a thickness of about 1000 microns. One section was used for magnesium determination by atomic absorption spectrophotometry, and the other was used for analysis with X-ray microanalysis. Thirty micron thick samples were abraded continuously from the periosteal and the endosteal surfaces by abrasive microsampling, as previously described by Weatherell et al. Results showed that magnesium concentrations were higher in both the periosteal and endosteal surfaces and did not change with age in general, although it tended to be higher among teenagers and lower over 80 years old.

Adolescent↗
PubMed1994

Expression of glutathione-S-transferases alpha and pi in gastric cancer: a correlation with cisplatin resistance.

Glutathione-S-transferase (GST) in one of several factors that are proposed to affect tumor sensitivity to anticancer drugs, including cisplatin (CDDP). Attempts are made herein to evaluate the significance of the enzymes in resistance to CDDP in clinical samples of gastric cancer. A total of 22 gastric cancer specimens, 16 of which were obtained with matching normal mucosae, underwent immunoblotting with polyclonal antibodies against GST-alpha and GST-pi. At the same time, the chemosensitivity of 15 gastric cancer specimens to CDDP was evaluated by the succinic dehydrogenase inhibition (SDI) test. The expression of GST-pi was detected in all the specimens, and its content in the neoplasms exhibited a significant positive correlation with that in the matched normal mucosae. The expression of GST-alpha was detected in 18 of 22 cancer specimens (82%), but its content in the neoplasms did not correlate with that in the matched mucosae. A comparison of the drug-sensitivity findings with the results of immunoblotting revealed a weak but interesting correlation between the protein levels of GST-alpha and CDDP resistance. The cellular content of GST-alpha correlated weakly with CDDP resistance in gastric cancer, and its quantification could contribute to prediction of the clinical effects of CDDP in patients with gastric cancer.

Cisplatin↗
PubMed1994

Desensitization of prostaglandin F2 alpha receptor-mediated phosphoinositide hydrolysis in cultured rat astrocytes.

Desensitization of prostaglandin (PG) F2 alpha receptor-mediated phosphoinositide (PI) hydrolysis was investigated in cultured rat astrocytes. Prolonged exposure of astrocytes differentiated by dibutyryl cyclic AMP-treatment to PGF2 alpha caused the desensitization of subsequent PGF2 alpha-induced PI hydrolysis. The desensitization was time- and PGF2 alpha dose-dependent; maximal decrease in the PI hydrolysis was observed after exposure to 10 microM PGF2 alpha for 4 h and the degree of the desensitization was 31.7 +/- 2.7% of control. Pretreatment with either PGD2 or PGE2 also induced the desensitization of subsequent PGF2 alpha-stimulated PI hydrolysis and conversely pretreatment of PGF2 alpha decreased the PI responses to PGD2 and PGE2. The desensitization prevented by phloretin and was reversible upon removal of the agonist. Protein synthesis inhibitors blocked the recovery of the desensitization. Treatment of the cells with phorbol 12-myristate 13-acetate had no effect on the desensitization. These results suggest that prolonged exposure of the astrocytes to PGF2 alpha caused the desensitization of the receptors.

Animals↗