PubMed Health⌕ Search

Biomedical subjects

K Tajima

Publications and source records attributed to K Tajima.

At least 19 recordsLinked to original sources
PubMed1997

Breast cancer risk factors according to combined estrogen and progesterone receptor status: a case-control analysis.

Breast cancers demonstrate a gradient of responsiveness to endocrine therapy according to hormone receptor status, with tumors positive for both estrogen and progesterone receptors responding most favorably. The authors hypothesized that reproductive risk factors, which are probably mediated by endogenous hormones, would also differ according to receptor status, and that tumors positive for both receptors would exhibit the highest risk. Information on risk factors was obtained from 1,154 breast cancer cases and 21,714 cancer-free controls at the Aichi Cancer Center Hospital, Nagoya, Japan between 1988 and 1992. Receptor status was known for 40% of cases. For a given risk factor, odds ratios with respect to the common control group for breast cancers of differing receptor status were compared using multiple polytomous logistic regression. Risk factors did not differ significantly according to estrogen receptor status. However, age at diagnosis/interview, occupation, age at menarche, menstrual regularity at ages 20-29 years, and cigarette smoking differed significantly or borderline significantly in effect according to progesterone receptor status. Stratification of cases according to joint estrogen and progesterone receptor status indicated that estrogen receptor status did not modify this difference in effect. This study did not support the hypothesis of a gradient of risk for reproductive factors according to hormone receptor status. The authors recommend that the finding that some risk factors differ according to progesterone receptor status should be pursued in further studies.

Adult↗
PubMed1997

Deglycosylation susceptibility and base-pairing stability of 2'-deoxyoxanosine in oligodeoxynucleotide.

We have demonstrated recently that nitrous acid or nitric oxide converts 2'-deoxyguanosine (dGuo) into 2'-deoxyoxanosine (dOxo) [Suzuki, T., Yamaoka, R., Nishi, M., Ide, H., & Makino, K. (1996) J. Am. Chem. Soc. 118, 2515-2516]. In the present study, we have measured susceptibility of the N-glycosidic bond of dOxo to spontaneous hydrolysis and its base-pairing stability to evaluate the biological significance of dOxo as a new lesion in DNA. When oligodeoxynucleotide d(T5OT6) (O = dOxo), isolated from nitrous acid-treated d(T5GT6), was incubated at pH 4.0 and 70 degrees C, hydrolysis of the N-glycosidic bond of dOxo occurred with a first-order rate constant. Comparison of the rate constants with those of dGuo and dXao indicates that the N-glycosidic bond of dOxo was as stable as that of dGuo in d(T5GT6) and hydrolyzed 44-fold more slowly than that of 2'-deoxyxanthosine (dXao), a simultaneously generated damage by nitrous acid and nitric oxide. For the estimation of the base-pairing stability, UV melting curves were measured for the duplexes of d(T5OT6).d(A6NA5) (N = A, G, C, and T) at neutral pH. The Tm values obtained were 15.3, 14.1, 19.3, and 16. 3 degrees C for N = A, G, C, and T, respectively, which are much lower than that of the intact duplex containing a G.C pair at the same position [d(T5GT6).d(A6CA5), Tm = 32.8 degrees C] but comparable with those of d(T5XT6).d(A6NA5) (X = dXao, Tm = 14.8-22.3 degrees C). CD spectra of the four duplexes containing dOxo showed preservation of the structure of the intact duplex at low temperature. UV and NMR pH-titration studies indicated the pKa for the ring-opening and -closing equilibrium to be 9.4, implying that dOxo is in the ring-closed form at physiological pH. This structure appears to be not suitable geometrically for the hydrogen bond formation with a specific counter base, thus causing equally low Tm values for all the counter bases. Consequently, these results imply that dOxo, a novel DNA lesion, may have an important and unique role in mutagenic events in cells.

Acid-Base Equilibrium↗
PubMed1997

Pterin-6-aldehyde, an inhibitor of xanthine oxidase, has superoxide anion radical scavenging activity.

Superoxide anion radical (O2.-) scavenging activity of neopterin (NP) and its photodegraded products was studied. NP did not affect O2.- release in hypoxanthine/xanthine oxidase (HPX/XOD) reaction system, but pterin-6-aldehyde (P6A), one of photodegraded products of NP, suppressed it. The identification of P6A was successful by confirming inhibiting property of xanthine oxidase. In neutrophil/phorbol myristate acetate reaction system, NP did not affect the O2.- release but P6A suppressed it. The suppression by P6A was not associated with oxygen uptake, which indicated that P6A did not inhibit the generation of O2.- but directly scavenged it. These findings suggest that P6A has ameliorating effects on ischemic-reperfusion injury in which O2.-, which is generated both in HPX/XOD reaction and in activated neutrophil, is one of the major substances to damage the tissues.

Biopterins↗
PubMed1997

Polymorphism of the HLA-DRB1 locus in Colombian, Ecuadorian, and Chilean Amerinds.

We have characterized the DRB1 genotypes in a sample of 64 South American Indians drawn from populations in Chile, Colombia, and Ecuador. No novel DRB1 alleles were found in the total of 17 different alleles characterized, indicating that rapid allelic generation does not occur at the DRB1 loci, in contrast to HLA-B. Comparison between Chilean and Colombian/Ecuadorian samples revealed no major differences in their allelic frequencies. In the combined Amerind sample the HLA-DRB1*0407 and HLA-DRB1*1402 alleles occurred in the highest frequencies (38% and 22%, respectively). Genetic distance measurement showed the HLA-DRB1 frequencies reported here to agree with findings in other Amerind groups. The high frequencies of both HLA-DRB1*0407 and HLA-DRB1*1602 alleles, in conjunction with their absence in Siberian samples, suggest that migratory groups other than Siberians may have been involved in the peopling of the Americas.

Alleles↗
PubMed1997

Spectroscopic evidence for the formation of four-stranded solution structure of oligodeoxycytidine phosphorothioate.

Oligodeoxycytidine phosphorothioate (PS-dCn, n = chain length), known to show virus inhibition ability by a mechanism other than the antisense one when n approximately 20, was explored for its solution structure by circular dichroism (CD) and ultraviolet (UV) absorption spectroscopy. For PS-dC4, when the strand concentration was higher than 10 microM, the respective 288-nm positive and 265-nm negative peaks appeared in the CD spectra at slightly acidic pHs and 0 degree C in the absence of salt, which is indicative of a four-stranded structure (namely, the i-motif). Strand concentration-dependent CD spectroscopy indicated that intermolecular association is responsible for this i-motif. The formation or i-motif was also characterized by UV absorption spectroscopy, in which the dissociation of this structure caused a sharp increase in the absorbance at 275 nm and a decrease at 305 nm. By plotting this change, the Tn values were estimated to be ca. 11 and 13 degrees C at 20 and 50 microM strand concentrations, respectively. Stability of the i-motif was compared between PS-dC, P-chiral diastereoisomers, and the Sp configuration produced a more stable structure than Rp. PS-dC20 was also investigated at physiological temperature, and the respective 288-nm positive and 265-nm negative peaks appeared at slightly acidic pH: it has been suggested that intermolecular folding was predominant above ca. 1 microM and that intramolecular folding dominated at low strand concentrations such as 0.05 microM. Gel-filtration chromatography and nondenaturing gel electrophoresis provided the supporting data for the four-stranded folding of PS-dC20.

Chromatography, Gel↗
PubMed1997

Molecular phylogeny of human T-cell leukemia virus type I and II of Amerindians in Colombia and Chile.

Six human T-cell leukemia virus type I (HTLV-I) and eight human T-cell leukemia virus type II (HTLV-II) cases newly isolated from the South American countries of Colombia and Chile were analyzed together with the two Amerindian HTLV-I isolates previously reported. All of the HTLV-I isolates belonged to the transcontinental subgroup of the "cosmopolitan" group, and Colombian isolates, including those from native Amerindians and Negroes, formed a single tight cluster within this subgroup. The transcontinental subgroup consisted of isolates from various regions such as the Caribbean basin, India, Iran, South Africa, Sakhalin, and Japan, and included isolates from the "Ainu" and "Okinawa" people, regarded as relatively pure Japanese descended from the prehistoric "Jomon" period which began more than 10,000 years ago. This implied a dissemination of the subgroup associated with the movement of human beings in ancient times. On the other hand, all of the HTLV-II isolates from native Amerindians in Colombia and Chile belonged to the HTLV-IIb subtype which has previously been reported to be mainly endemic in certain populations of native Amerindians. The southernmost isolate from Chile, showing wide distribution of the IIb subtype in native South Amerindians and largest heterogeneity of the subtype in Colombian isolates, supported the idea that the HTLV-IIb subtype has been endemic for a long time in native Indians of South America.

Chile↗
PubMed1997

Construction of a Fibrobacter succinogenes genomic map and demonstration of diversity at the genomic level.

The genomic cleavage map of the type strain Fibrobacter succinogenes S85 was constructed. The restriction enzymes AscI, AvrII, FseI, NotI, and SfiI generated DNA fragments of suitable size distribution that could be resolved by pulsed-field gel electrophoresis (PFGE). An average genome size of 3.6 Mb was obtained by summing the total fragment sizes. The linkages between the 15 AscI fragments of the genome were determined by combining two approaches: isolation of linking clones and cross-hybridization of restriction fragments. The genome of F. succinogenes was found to be represented by the single circular DNA molecule. Southern hybridization with specific probes allowed the eight genetic markers to be located on the restriction map. The genome of this bacterium contains at least three rRNA operons. PFGE of the other three strains of F. succinogenes gave estimated genome sizes close to that of the type strain. However, RFLP patterns of these strains generated by AscI digestion are completely different. Pairwise comparison of the genomic fragment distribution between the type strain and the three isolates showed a similarity level in the region of 14.3% to 31.3%. No fragment common to all of these F. succinogenes strains could be detected by PFGE. A marked degree of genomic heterogeneity among members of this species makes genomic RFLP a highly discriminatory and useful molecular typing tool for population studies.

Animals↗
PubMed1997

Epidemiological features of first-visit outpatients in Japan: comparison with general population and variation by sex, age, and season.

To evaluate the methodological issues in using first-visit outpatients as controls in epidemiological studies, the features of general lifestyles of non-cancer outpatients at Aichi Cancer Center Hospital (ACCH) were compared with those of the general population, and their variation by sex, age, and season was determined by using a self-administered questionnaire. The study included 1231 subjects randomly selected from the Nagoya electoral roll (CRG), and three groups of non-cancer ACCH outpatients living in Nagoya; 800 from the period September to December 1992 (OPG1), 2326 from January to December 1992 (OPG2), and 12,243 from January 1991 to December 1992 (OPG3). In the younger age group, the proportion of current smokers was higher in the CRG than in the OPGs. In the older age groups, the proportion of those who consumed fresh vegetables and fruit everyday was higher in the OPGs than in the CRG. For other items, the features of the OPGs were not significantly different from those of the CRG. Among the OPG3, there were differences in the features of general lifestyles between sexes and consumption of several food items varied with age. Seasonal variation, however, was only observed in the specific food items where supply varied seasonally. It was concluded that, with due consideration of age, sex, and season in the analysis, it is feasible to use non-cancer outpatients as controls in epidemiological studies.

Adult↗
PubMed1997

Intra-abdominal bleeding after repair of total anomalous pulmonary venous connection.

A case is reported of sudden rupture of a subcapsular hematoma of the liver (SHL) due to birth injury occurring after complete repair of a total anomalous pulmonary venous connection in a 3-day-old male infant. Autopsy showed a wide bruised surface of liver parenchyma. Although making a diagnosis of SHL may be difficult before neonatal cardiac surgery, special care on this quite rare complication must be taken in neonates with difficult delivery.

Birth Injuries↗
PubMed1997

Estimation of adult T-cell leukemia incidence in Kyushu District from vital statistics Japan between 1983 and 1982: comparison with a nationwide survey.

To investigate the change in adult T-cell leukemia incidence between 1983 and 1992 and to evaluate the sensitivity of the nationwide adult T-cell leukemia survey, we estimated adult T-cell leukemia incidence in the Kyushu district, southern Japan, where adult T-cell leukemia is endemic. The incidence of adult T-cell leukemia was calculated from the difference between Kyushu and the rest of Japan in mortality from malignant lymphoid neoplasms, i.e., Kyushu's excess rate was assumed to be due to adult T-cell leukemia. In Kyushu, average annual adult T-cell leukemia cases aged > or = 20 years were estimated for men as 252 during the period 1983-87 and 341 during 1988-92, and for women as 201 and 246 respectively. The age-adjusted mortality rate tended to be higher in the latter period [6.29 per 100000 (95% confidence interval 5.59-7.00) vs. 5.25 (4.60-5.90) in men, and 3.33 (2.85-3.80) vs. 3.18 (2.71-3.66) in women]. By contrast, the registered number of adult T-cell leukemia cases nationwide during 1988-93 was only 35% (203/587) of the estimated number, and the number of registered versus estimated cases decreased with age, especially when cases were > 60 years old. In conclusion, the estimated adult T-cell leukemia incidence for 1983-92 increased in the latter half of the period. The estimation suggests that 65% of adult T-cell leukemia cases might be missed by a nationwide survey, and older cases were more likely than younger ones to be missed.

Adult↗
PubMed1997

Epidemiologic survey of lower urinary tract symptoms in Asia and Australia using the international prostate symptom score.

BACKGROUND: The prevalence of lower urinary tract symptoms was determined by survey as an initial step in estimating the significance of benign prostatic hyperplasia (BPH) in Asia and Australia. METHODS: The symptom index (0 to 35) and quality-of-life (QOL) index (0 to 6) of the international prostate symptom score were measured in 7588 men in 9 Asian countries and 146 men in Australia. RESULTS: The percentages of Asian men considered to be symptomatic (symptom index > or = 8) were 18%, 29%, 40%, and 56% in the age groups of 40 to 49, 50 to 59, 60 to 69, and 70 to 79 years, respectively. For Australian men, these figures were 36%, 33%, and 37% in the 50 to 59, 60 to 69, and 70 to 79 year age groups, respectively. CONCLUSIONS: Our estimates indicate that the prevalences of symptomatic men in Asia and Australia are similar to or greater than those in Europe and America, and suggest BPH is similarly common in these areas.

Adult↗
PubMed1997

Malignant melanoma of the kidney presenting as a primary tumor.

We report a case of malignant melanoma of the kidney presenting as a primary tumor. This tumor was found incidentally in a 74-year-old woman. The patient underwent a right radical nephrectomy, and has been living tumor free for 2 years and 3 months. This is the first reported case of primary renal malignant melanoma. We discuss the probability that this tumor is renal in origin and directly linked to the origin of malignant melanoma.

Aged↗
PubMed1997

Electronic and structural requirements for metabolic activation of butylated hydroxytoluene analogs to their quinone methides, intermediates responsible for lung toxicity in mice.

Previous studies have shown that butylated hydroxytoluene (BHT) undergoes oxidation by cytochrome P450 to form BHT-quinone methide. BHT-quinone methide is probably responsible for BHT-induced lung damage in mice. In this study, we calculated the MO parameters for BHT analogs and the corresponding quinone methide intermediates. Except for the analogs with structures that form a highly sterically hindered quinone methide, correlations could be established between the lung toxicity in mice and electronic charges on the hydroxyl oxygen and 4-carbon atoms of BHT analogs. The same toxicity could also be correlated to the difference between the heat of formation of the quinone methide intermediates and the parent BHT analogs, and to the electronic charge on the carbonyl oxygen atom of the quinone methides. These results suggest that the metabolic activation of BHT analogs to their quinone methide intermediates is energetically dependent on the oxidation of the aromatic pi-electron system, and that the toxic potency of BHT analogs is controlled by protonation of the oxygen atom of the quinone methides. These electronic features provide further evidence of the importance of the quinone methide intermediates in the mechanism of lung toxicity induced by BHT analogs.

Animals↗
PubMed1997

Patients' views on reference to clinical data.

In order to survey patients' views on reference to clinical data for research purposes, an anonymous self-administered questionnaire was distributed to Aichi Cancer Center Hospital patients in 1995. All eligible first-visit outpatients (97 persons), randomly selected revisit outpatients (99 persons), and all eligible inpatients in a good condition at discharge except six cases (97 persons), responded to the questionnaire. Out of 293 patients (115 males, 174 females and 4 unspecified), 85.3% (standard error 2.1%) considered that hospitals should make active efforts to improve their health care and treatment skills. And 88.1% (standard error 1.9%) answered that reference to their own clinical data to improve health care and treatment skills was "preferable" or "don't mind".

Adult↗