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Biomedical subjects

K Aoki

Publications and source records attributed to K Aoki.

At least 847 records · Page 47Linked to original sources
PubMed1983

Incidence of chromatoblastomas in aging goldfish (Carassius auratus).

The incidence of chromatoblastomas in aging goldfish, Carassius auratus, was observed for 2 successive years. Tumors first appeared in fish at 5 years of age, and the tumor frequency increased with increasing age of the fish. The cumulative incidence rate of chromatoblastomas and the mean number of tumors per fish were estimated for each age. The mean number of tumors per fish fitted a straight line with a slope of approximately 3 on a double logarithmic graph against age. Thus tumor incidence seemed proportional to about the third power of age, and tumor appearance seemed dependent on some mutational events.

Aging↗
PubMed1983

Effectiveness of "two-route chemotherapy" using cisplatin and its antidote, sodium thiosulfate, on lifespan of rats bearing metastatic liver tumors.

The therapeutic efficacy of "two-route chemotherapy" (TRC) using cisplatin (DDP) and its potent antidote, sodium thiosulfate (STS), was studied on rat metastatic liver tumors. Twenty mg/kg of DDP was given to rats via the hepatic artery in combination with systemic STS at a dose of 1054 mg/kg (100-fold molar ratio to 20 mg/kg of DDP) or at two doses of 1054 mg/kg. As controls, 5 or 4 mg/kg of DDP alone was given intra-arterially or iv. Antitumor effects were evaluated by prolongation in lifespan after the tumor cell inoculation. Side effects were assessed by weight loss, BUN, and serum transaminases after the chemotherapy. TRC resulted in the longest lifespan, with a minimum weight loss and without elevation of BUN or serum transaminases. The therapeutic efficacy of TRC was enhanced by temporary ligation of the portal vein for 5 minutes, performed simultaneously with DDP infusion. Our findings clearly indicate the effectiveness of TRC using intra-arterial DDP in a high dose and in combination with iv STS.

Animals↗
PubMed1982

Histologic features of bladder cancer in Boston, USA, Manchester, UK, and Nagoya, Japan.

Histologic characteristics of bladder cancer in Boston, USA, Manchester, UK, and Nagoya, Japan, were evaluated. In each of these areas broadly-based series of cases were assembled during a collaborative case-control study. The present analysis was based on 589 cases in Boston, 484 cases in Manchester, and 241 cases in Nagoya. A single pathologist reviewed a slide of the primary tumor without reference to identifying information or other data. The primary histologic type of nearly all tumors was transitional-cell, and there was little variation in the proportion of transitional-cell tumors among the study areas. Nor was there much variation in the distribution of histologic grade, the proportion of tumors showing submucosal invasion, or the proportion of tumors with a papillary surface. Age at diagnosis was strongly correlated with histologic grade. The proportion of grade III (most malignant) tumors was about twice as high among patients 80 years of age and over as among those aged less than 50. An apparent association between age and submucosal invasion was explained in large part by the relationships of histologic grade to submucosal invasion and to age. Other histologic features had only weak and inconsistent relations with age. None of the features evaluated showed consistent associations with history of cigarette-smoking or with sex.

Adenocarcinoma↗
PubMed1982

Age at menarche, probability of ovulation and breast cancer risk.

An analysis is undertaken of the frequency of ovulation in 17 groups of women aged 15 to 19 who had been the subjects of other studies. A urine specimen of at least 8 h accumulation had been provided on the 20th or 21st day of a menstrual cycle by 681 women. Analysis is restricted to 431 specimens which had been collected between 11 and 3 days prior to the onset of the subsequent menstrual period. A pregnanediol concentration of less than 1 mg per litre in such a specimen was taken as evidence that the cycle was anovular. The probability of a cycle being anovular was inversely and significantly related to the number of years since menarche, and, with years since menarche held constant, was positively but not significantly associated with age at menarche. This observation indicates that women with early menarche do not have a longer duration of exposure to anovular cycles than do those whose menarche is delayed, and that variation in the duration of exposure to post-menarcheal anovular cycles does not explain the association of breast cancer risk with early age at menarche. The 17 groups of women were classified into four categories according to ethnic origin and breast cancer incidence in the populations from which they derived. Anovular cycles were not more common in the high-risk groups; indeed, the two centers in the lowest risk category had the highest proportion of anovular cycles.

Adolescent↗
PubMed1982

Acute and long-term hypotensive effects and plasma concentrations of nifedipine in patients with essential hypertension.

The acute and long-term hypotensive effects of low doses of nifedipine, and the correlation between the fall in the blood pressure (BP) and the plasma nifedipine concentration, were investigated in patients with essential hypertension. The oral administration of nifedipine 5 mg rapidly decreased BP from 163 +/- 22/101 +/- 10 to 127 +/- 12/82 +/- 9 mmHg (mean +/- SD; p less than 0.001), and increased heart rate from 72 +/- 8 to 76 +/- 6 beats/min (p less than 0.05), plasma renin activity rose from 1.2 +/- 0.6 to 1.4 +/- 0.8 ng/ml/h (p less than 0.05), and plasma nifedipine concentration was 75.6 +/- 22.0 ng/ml 30 min after administration (n = 7). The nifedipine concentration was significantly correlated both with the fall in BP (r = 0.410, p less than 0.02, n = 31) and the rise in the heart rate (r = 0.412, p less than 0.02, n = 31). Treatment with nifedipine 5 mg t.d.s. alone or in combination either with propranolol 10 mg t.d.s., or thiazide 1 tablet daily, or propranolol and thiazide, controlled BP in 36 patients during the 22 week study period. During the long-term nifedipine therapy, the plasma nifedipine level was significantly correlated with the fall in systolic (r = 0.577, p less than 0.01, n = 20) and diastolic (r = 0.595, p less than 0.01, n = 20) BP. It was concluded that the plasma nifedipine concentration could be correlated with the fall in BP, and that low doses of nifedipine, either as monotherapy or in combination, were effective in the acute and long-term treatment of patients with essential hypertension.

Adult↗
PubMed1982

"Two route infusion chemotherapy" using cis-Diamminedichloroplatinum (II) and its antidote, sodium thiosulfate, for metastatic liver tumors in rats.

We studied the effects of combination chemotherapy of an antitumor drug cis-diamminedichloroplatinum (II) (DDP) and its potent antidote, sodium thiosulfate (STS) in rat liver tumor systems. This therapy was given to female WKA rats with metastatic liver tumors 13 days after inoculation of syngeneic hepatoma cells through the mesenteric vein. DDP and STS were administered via two different routes, hepatic artery and femoral vein, respectively (we call this treatment "two route infusion chemotherapy"). The antitumor effects were evaluated 21 days after the treatment by calculating the tumor weight from the total weight of the liver. Tumor weights of rats treated with 20 mg/kg of intra-arterial DDP plus 1,054 mg/kg of systemic STS (group A), 5 mg/kg of intra-arterial DDP alone (group B), and 5 mg/kg of systemic DDP alone (group C) were, about one fifth, two fifths and three fifths of the tumor weights in the untreated controls, respectively. In group A, no rats died despite administration of a 4-fold higher DDP dose than in the latter two groups B and C in which 14-18 per cent of the rats died, due to DDP-induced toxicity. The patterns of body weight gain in the three groups after the chemotherapy were much the same. Our results clearly indicate that the antitumor effect of DDP on metastatic liver tumors in rats can remarkably be enhanced by the "two route infusion chemotherapy" of DDP and STS.

Animals↗
PubMed1982

Artificial sweeteners and bladder cancer in Manchester, U.K., and Nagoya, Japan.

We have evaluated the relation between cancer of the lower urinary tract ("bladder cancer") and the use of artificial sweeteners, by means of case-control studies in Manchester, U.K., and Nagoya, Japan, areas where extensive use occurred 30-40 years ago. In each area, a broadly based series of cases (555 in Manchester, 293 in Nagoya) was interviewed and a series of controls (735 in Manchester, 589 in Nagoya) chosen from the general population. A history of use of sugar substitutes primarily saccharin, was not associated with an elevated risk of bladder cancer in either study area. Risk of bladder cancer did not increase regularly with frequency or duration of use of sugar substitutes. Data on dietetic beverages were not obtained in Nagoya. This exposure was not associated with a greater risk of bladder cancer in Manchester. The results of this study suggest that use of artificial sweeteners confers little or no risk of bladder cancer.

Adult↗
PubMed1982

Illegitimate recombination mediated in vitro by DNA gyrase of Escherichia coli: structure of recombinant DNA molecules.

We have developed a cell-free system from Escherichia coli for studying illegitimate recombination between nonhomologous DNA molecules. The recombination is stimulated by oxolinic acid, an inhibitor of DNA gyrase. The stimulation is abolished by coumermycin A1 and is not found in extracts of nalidixic acid-resistant (gyrA) mutants. We therefore inferred that DNA gyrase directly participates in illegitimate recombination, at least in the presence of oxolinic acid [Ikeda, H., Moriya, K. & Matsumoto, T. (1981) Cold Spring Harbor Symp. Quant. Biol. 45, 399--408]. The structure of recombinant DNA molecules formed in the presence of oxolinic acid from a cross between phage lambda and plasmid pBR322 DNAs was analyzed by heteroduplex mapping. Among nine isolates tested, two recombinants were formed by the insertion of the plasmid into the lambda genome. The seven other recombinants had more complicated genome structures. Insertion of pBR322 was accompanied by a deletion on one of the genomes. In all cases, the end points of deletions coincided with one end of the pBR322 insertion. Recombination sites seemed to be distributed randomly on the lambda and pBR322 genomes. Analysis of nucleotide sequences of the recombination junctions proved that the crossover took place between nonhomologous DNA sequences. A model for DNA gyrase-mediated illegitimate recombination is discussed.

Bacteriophage lambda↗
PubMed1982

Group selection for a polygenic behavioral trait: a differential proliferation model.

Conditions for natural selection to increase a polygenic behavioral trait are derived for a model in which the population is divided into a very large number of partially isolated groups of variable and varying size. Specifically, we consider an altruistic trait that is deleterious to the individual but raises the mean fitness of the group. We assume, for each generation, that all groups have the same proportion of males, k, at the time of migration and that each group contributes Mf females and Mm males to a pool of migrants, from which Mf females and Mm males are randomly parceled out to each group. This assumption ensures that at equilibrium between random drift and a low level of migration and neglecting the small per locus effect of selection, each group has the same expected value of Wright's fixation index, FST = F. AT equilibrium, this is approximately 1/(1 + 4Me), where Me = 2kMf + 2(1 - k)Mm. The trait will increase when (b - c)/c greater than (1-F)/2F=2Me, where b is the expected benefit to the group and c is the expected cost of a unit change in the mean value of the altruistic trait. In particular, the group selection analogue of Hamilton's inequality, c/b less than r, where r is the coefficient of relationship, is obtained. The effect of isolation is enhanced if migration is mainly between adjacent groups and if group splitting is along family lines, as data on population structure of primates seem to indicate.

Altruism↗