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Biomedical subjects

K Aoki

Publications and source records attributed to K Aoki.

At least 541 records · Page 30Linked to original sources
PubMed1991

Effect of TC-81, a new dihydropyridine derivative, on K(+)-induced contraction in rat aorta.

TC-81 (3-(N-benzyl-N-methylamino)-2,2-dimethylpropyl methyl-2,6-dimethyl-4-(2-fluoro-5-nitrophenyl)-1,4-dihydro-pyridine- 3,5-dicarboxylate hydrochloride) is a new dihydropyridine derivative. The effects of TC-81 (10(-10)-10(-8) M) on high K(+)-induced contractions were investigated in isolated rat aorta, and the results were compared with those obtained with nicardipine, nifedipine, diltiazem and papaverine. All drugs produced concentration-dependent relaxation of K(+)-induced contractions. The rate of relaxation induced by TC-81 was slower than that induced by the other drugs at concentrations producing the same final inhibition. However, the relaxing activity of TC-81 was 2.2, 16.7, 550 or 44,000 times more potent than that of nicardipine, nifedipine, diltiazem or papaverine, respectively. The inhibitory effect of TC-81 was dependent on the duration of exposure to the agent and was antagonized when the external Ca2+ concentration was raised. TC-81 concentration dependently inhibited La(3+)-resistant 45Ca2+ uptake in high K+ solution. The data thus show that TC-81 produces a concentration-dependent and time-dependent Ca2+ antagonistic action and that it is more potent than the other drugs tested.

Animals↗
PubMed1991

The formation of gastric ulcers with a tendency to hemorrhage in association with aortic aneurysms.

It is widely accepted that patients with aortic aneurysm (AA) show a higher incidence of peptic ulcers than those without. However, the pathogenesis of peptic ulcers associated with AA remains obscure. We measured the gastric mucosal blood flow (GMBF) endoscopically and also determined the gastric mucosal prostaglandin (PG) levels of these AA patients to investigated the mechanism behind gastric ulcer formation. Moreover, we investigated the consumption coagulopathy (CC) of AA responsible for inducing the hemorrhage from ulcers. The GMBF values of 7 AA cases, taken at the antrum, angle and corpus, were significantly decreased compared with those of control cases, while the PGE2 levels of the gastric mucosa were also significantly reduced. With regard to CC, the serum levels of fibrinogen or platelets were significantly lower than those of the control group. These results indicate that the decrease in GMBF, followed by the reduction in endogenous PG, might contribute to the gastric ulcer formation in AA patients, and that CC associated with AA could be an important factor causing the hemorrhage from these ulcers. AA patients should therefore be treated with focusing attention on the possibility of an associated ulcer and ulcer bleeding.

Aged↗
PubMed1991

Advanced gastric cancer associated with acute myelocytic leukemia--report of a case.

A case of advanced gastric cancer associated with acute myelocytic leukemia (AML) is reported. Synchronous double malignancies of gastric cancer and AML are very rare. Combination chemotherapy (BHAC-DMP) was used as the method for induction and consolidation therapy for AML and a complete remission was obtained. However, it failed to show any therapeutic effect on the gastric cancer. A radical subtotal gastrectomy was performed with lymphadenectomy. During the postoperative course, both respiratory failure and severe thrombocytopenia progressed. Fortunately, the patient responded well to mechanical ventilation and the administration of heparin. She was discharged on day 52 after surgery, and no sign of recurrence of either gastric cancer or AML has been observed over the one-year period following the gastrectomy. In principle, in order to achieve a good prognosis, a radical resection should be carried out for gastric cancer associated with AML. However, chemotherapy for AML might make the patient vulnerable to surgical stress, although we could not demonstrate any concrete evidence which could prove the impairment of host immunity in this case. It is, therefore, possible that not only the relapse of AML but also the impairment of host immunity may cause some other difficulties during the post-gastrectomy course.

Aged↗
PubMed1991

Recessive hereditary deafness, assortative mating, and persistence of a sign language.

We model the cultural transmission of sign language when there is one-locus genetic variation for deafness and hearing. Our premises are that the deaf are more motivated to learn sign language than the hearing, and that a vertically transmitted sign language, unlike recessive hereditary deafness, cannot "jump a generation." Conditions are obtained for persistence (i.e. protection from loss) of signers. These conditions are more easily satisfied the greater the fraction of the hearing who also learn sign language and as the frequency of the recessive gene for deafness increases. Persistence is also facilitated by assortative mating for deafness, but not by assortment for signing. With vertical transmission only, it is necessary that one signer parent be able to transmit sign language with greater than one-half the efficiency of two. Under the assumption that the hearing do not learn sign language, the following additional results are obtained. Persistence is more likely with dominant as opposed to recessive inheritance. When recessive hereditary and acquired deafness co-occur, increasing the frequency of the latter has opposite effects depending on the degree of assortment. Opportunities for the deaf to learn sign language outside the family seem not to affect the conditions for persistence.

Deafness↗
PubMed1991

Time required for gene frequency change in a deterministic model of gene-culture coevolution, with special reference to the lactose absorption problem.

The time required for gene frequency change under natural selection in a deterministic model of gene-culture coevolution is investigated. A discrete generations model is formulated, and its continuous time approximation is derived. In passing to the continuous time limit, it is assumed that the frequency of the culturally transmitted trait does not change under oblique (between generations) transmission. The system of ordinary differential equations thus obtained are solved, and the dependence on the parameters of horizontal (within generations) transmission and natural selection is examined. The time required is found to be substantially longer when the determination of a phenotypic difference subject to natural selection is partly cultural rather than completely genetic. The predictions are relevant to the possibility of the coevolution of lactose absorbers and milk drinkers in some human populations. Alternative hypotheses are briefly discussed in the light of the theoretical results.

Biological Evolution↗
PubMed1991

Differential scanning calorimetric studies on bovine serum albumin: II. Effects of neutral salts and urea.

Using defatted and SH-blocked bovine serum albumin (BSA), measurements of differential scanning calorimetry (d.s.c.) have been made mainly in NaSCN solution. BSA undergoes a heat-induced conformational transition in a particular range of pH and ionic strength and is separated into two thermally independent units, each of which has different thermostability in acidic and alkaline pH regions. Comparisons were made of the pH dependencies of the enthalpy of thermal denaturation (delta H) and the temperature of thermal denaturation (Td) in 0.01 M NaSCN with those in 0.01 M NaCl. It has been found that the stabilizing effect of NaSCN on BSA is larger than that of NaCl at pH 3.5-8, and that the heat-induced transition occurs by the electrostatic repulsive forces among the positively charged amino acid residues in a segment Arg 184-Arg 216 containing Trp 212 and the primary binding sites of anions. At ionic strength 0.01, the relative effectiveness of anions in suppressing the heat-induced transition and increasing the thermostability of BSA follows the order ClO4- - greater than or equal to SCN- greater than I- greater than SO4(2-) greater than Br- greater than Cl-. At ionic strength 0.1, the heat-induced transition is suppressing in all the salt solutions, and a Td increase follows the order ClO4- greater than or equal to SCN- greater than I- greater than Br- greater than Cl- greater than or equal to SO4(2-). Thus, the highly chaotropic ions thermostabilize BSA more markedly than kosmotropic ions in the low and moderate salt concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Development of monoclonal antibodies reactive with methamphetamine raised against a new antigen.

Monoclonal antibodies (McAbs) specific to methamphetamine (MA) were produced using p-amino MA coupled to bovine serum albumin (BSA) with glutaraldehyde (GA) as an immunogen and with conventional hybridoma techniques. Hybridoma clones secreting the McAbs were selected by an enzyme-linked immunosorbent assay (ELISA) system using both the above conjugate and BSA modified with GA as screening antigens. In the ELISA system were used avidin and biotinyl-alkaline phosphatase which converts nicotinamide adenine dinucleotide phosphate (NADP) into NAD. The final enzyme activity was determined using diformazan of nitroblue tetrazolium formed together with the NAD produced, alcohol dehydrogenase and phenazine methosulfate. The McAbs from 9 clones were characterized by a crossreactivity test using the ELISA. The McAbs recognized MA (100%), methoxyphenamine (8.0%), ephedrine (2.3%), but did not react with metylephedrine, amphetamine, OH-amphetamine, dimethylamphetamine, beta-phenylethylamine, norephedrine, phentermine and ranitidine. An inhibition curve for MA was obtained in the range of 0.75 to 50 ng.

Animals↗
PubMed1991

Relationship between serum xanthophyll levels and the consumption of cigarettes, alcohol or foods in healthy inhabitants of Japan.

The relationship between serum concentrations of beta-cryptoxanthin and zeaxanthin and the consumption of cigarettes and alcohol or the intake frequencies of foods was investigated in 775 Japanese inhabitants. Serum concentrations of beta-cryptoxanthin and beta-carotene in healthy Japanese aged 40-70 years were higher in females than in males. Serum beta-cryptoxanthin levels were inversely associated with the consumption of cigarettes and alcohol, as were the serum beta-carotene levels. Serum zeaxanthin (including lutein) levels were associated with cigarette consumption. The levels of serum beta-cryptoxanthin were positively correlated with the intake frequency of some fruits, and those of zeaxanthin, with the intake frequency of green vegetables, milk and eggs. These xanthophylls may play a role with beta-carotene in smoking-related cancer prevention.

Adult↗
PubMed1991

Malfunction of arterial sarcoplasmic reticulum leading to faster and greater contraction induced by high-potassium depolarization in young spontaneously hypertensive rats.

The contribution of sarcoplasmic reticulum was studied with regard to the increase in arterial contraction induced by a high-potassium depolarization in spontaneously hypertensive rats (SHR). The 20 mmol/l potassium-induced contraction of femoral arteries was faster and greater in 6-week-old SHR than in age-matched normotensive Wistar-Kyoto (WKY) rats. Relaxation after washing the arteries with a Krebs solution was slower in SHR than in WKY rats. When the sarcoplasmic reticulum of SHR arteries had been depleted of calcium by caffeine in a calcium-free solution, the rate of high-potassium-induced contraction of the calcium-depleted SHR arteries was slowed, the same result as that with non-calcium-depleted WKY arteries. In ryanodine-treated arteries, the rate and magnitude of high-potassium-induced contraction were enhanced slightly in SHR and greatly in WKY rats, resulting in no final difference between SHR and WKY rats. Ryanodine slowed the relaxation rate in WKY rats but not in SHR. These results suggest that the diminution in ability of sarcoplasmic reticulum to sequester calcium may be responsible for the faster rate and greater magnitude of high-potassium-induced contraction with the slower relaxation in SHR arteries. We postulated that genetic malfunction of sarcoplasmic reticulum causes the increased contraction of arterial smooth muscle leading to the enhanced vasoconstriction and elevated blood pressure in SHR.

Animals↗
PubMed1991

A case of congenital onychoheterotopia on both fifth fingers.

The present report illustrates the extremely rare clinical features of congenital onychoheterotopia (ectopic nail). The amino-acid composition of congenital ectopic nail was estimated, and the surface of nail clippings was compared to the patient's normal nail using scanning electron microscopy.

Adult↗
PubMed1991

Early and late contraction induced by ouabain in human umbilical arteries.

1. Ouabain (3 x 10(-7)-10(-4) M) evoked a biphasic contraction in human umbilical artery that consisted of an early and a late contraction. The Ca(2+)-antagonists, verapamil (10(-7)-10(-5)) M), diltiazem (10(-7)-(10(-5)) M) and nifedipine (10(-9)-10(-7)) M) inhibited the early but not the late contraction. Caffeine (5 mM) changed neither the magnitude of the peak of the biphasic contraction nor the time needed to reach it. 2. Sodium concentration reduction (140 to 0 mM, replaced by N-methyl-D-glucamine, NMG) produced dose-dependent contraction of the arterial strip in 2.5 mM Ca2+ solution after the first treatment with verapamil (10(-5) M) and caffeine (5 mM), but not in Ca(2+)-free solution. 3. After prior treatment with verapamil and caffeine, the amplitude of the ouabain (10(-4) M)-induced late contraction varied, depending on the concentration of Ca2+ (0-2.5 mM) in the medium. 4. Amiloride (5 x 10(-5) M-5 x 10(-4) M), an inhibitor of the Na(+)-Ca2+ exchange system, produced dose-dependent inhibition of the late contraction induced by ouabain (10(-5) M) after prior treatment with verapamil and caffeine. 5. The time needed to reach the peak tension induced by monensin (5 x 10(-7) M) together with ouabain (10(-6) M) was less than that with ouabain alone, but the magnitude of the peak tension was not changed. 6. These results suggest that the early and late contractions caused by ouabain respectively produce a Ca2+ influx through voltage-sensitive Ca2+ channels and Ca2+ entry through sodium-calcium (Na(+)-Ca2+) exchange.

Adult↗
PubMed1991

Changes in subgenome types of adenovirus type 4 isolated from patients with ocular disease between 1985 and 1989 in Sapporo, Japan.

A total of 122 adenovirus type 4 (Ad4) strains isolated from patients with epidemic keratoconjunctivitis at an eye clinic in Sapporo, Japan, from 1985 to 1989 were identified as Ad4a. By the use of HinfI and TaqI restriction endonucleases, these Ad4a strains were classified into 12 subgenome types. During this observation period, two epidemics of Ad4 infection relating to epidemic keratoconjunctivitis occurred. During the Ad4a epidemic in 1985, three subgenome types became predominant successively. However, except for one strain, the prevalent strains isolated during the epidemic of Ad4a in 1988 all belonged to a single subgenome type. In the years when an Ad4a epidemic was not observed, such Ad4a strains were new or previous subgenome types. The prevalent subgenome types tended to change within several years.

Adenoviruses, Human↗
PubMed1991

Effect of non-enzymatic glycosylation and heating on browning of human stratum corneum and nail.

The purpose of the present study was to examine the effect of non-enzymatic glycosylation and subsequent heating on the browning of the plantar stratum corneum and the finger-nail, and to elucidate the pathogenesis of the yellow skin and the yellow nail seen in diabetic subjects. We incubated stratum corneum and nail from non-diabetics in 0 (control), 10 (only nail), 20 (only nail), 100 and 250 mM glucose buffer at 37 degrees C for 5 days. These glycosylated samples were dialysed against distilled water for 96 h. Distilled water was changed every 24 h. Then samples were dried for 24 h. The extent of non-enzymatic glycosylation was measured by furosine content. Each 5 mg of sample was hydrolysed by 6 N HCl and processed for measurement of furosine by high-performance liquid chromatography. The rest of each sample was stored at 37, 42 (only nail), 47 and 52 degrees C for 14 days. Browning of the stratum corneum was assessed macroscopically, and that of the nail by spectrophotometry. Based on their spectrophotometric reflectances. Munsell's scores (H = hue score, V = lightness score, C = saturation score) and (H + C)/V were calculated for objective evaluation of browning. Incubation of the stratum corneum and nail with glucose buffer increased their non-enzymatic glycosylation (furosine) dose dependently. Macroscopically, the browning of the stratum corneum was enhanced in proportion to the glucose concentration and storage temperature. However, samples incubated in 10 and 20 mM glucose and stored at 42 degrees C did not show visible browning. Munsell's score of the nail samples treated by glycosylation and heating showed increased hue and saturation but reduced lightness. (H + C)/V values of these nail samples were significantly higher than those of the control. We could not detect any fluorescence with Wood light in the browned samples. The present in vitro study demonstrated that the browning of the stratum corneum and the nail depended on the extent of both non-enzymatic glycosylation and storage temperature. We suggested a hypothesis that the non-enzymatic glycosylation and the storage temperature of the stratum corneum and the nail might be a contributory factor in the development of yellow skin and yellow nail in diabetic patients.

Adult↗
PubMed1991

Abnormality in sarcoplasmic reticulum-dependent arterial contraction in responses to caffeine and noradrenaline in spontaneously hypertensive rats.

We studied caffeine- and noradrenaline-induced contraction in tail arteries from 4-week-old male SHR and age- and sex-matched WKY. After the sarcoplasmic reticulum Ca2+ had been depleted by the Ca(2+)-free EGTA (0.1 mmol/l) solution, the caffeine (10 mmol/l)-induced contractions in a low-Ca2+ (0.5 mmol/l) solution were smaller in SHR than in WKY. After the sarcoplasmic reticulum had been loaded with Ca2+ in physiological Ca2+ (2.5 mmol/l) solution, caffeine- and noradrenaline (10(-5) mol/l)-induced contractions in a Ca(2+)-free EGTA solution were smaller in SHR than in WKY. The Ca2+ concentration-tension relationship in skinned arterial fibres was similar in WKY and SHR. These data suggest that the ability of the sarcoplasmic reticulum to take up Ca2+ and store Ca2+ is decreased in SHR. The decreased take up and store of Ca2+ may increase cytosolic Ca2+, which elevates arterial resistance and develops hypertension in gene hypertension.

Animals↗
PubMed1991

[Effects of high- and low-intensity training on cardiorespiratory system and serum lipids].

The differences between the effects of high- and low-intensity exercise training on cardiorespiratory system and serum lipid levels were examined under conditions in which the total work load was same. Twenty-two healthy, untrained female students, aged 18 to 24 years, participated in the 8-week training experiment. Two training groups exercised on bicycle ergometers 4-5d/wk for 8 wk with high-intensity (H: 70% VO2 max 13 min/session; N = 8) or in low-intensity (L: 36% VO2 max 33 min/session; N = 8). The control group (C: N = 6) continued its sedentary life style. Data of 6 students (H: N = 2, L: N = 2, C: N = 2) were excluded from the analysis, because they did not carry out their duties. The results of this study were as follows; 1) Aerobic capacity increased in both training groups. 2) After training, both heart rates and oxygen uptake during submaximal work loads significantly decreased in group H, but only heart rates significantly decreased in group L. 3) Heart rates with a same oxygen-uptake load during submaximal work seemed to increase in group H, but significantly decreased in group L. 4) The mechanical efficiency during the submaximal work load significantly increased in group H, but not in group L. 5) DBP and MBP during the submaximal work load in group L significantly decreased compared with those before the training. SBP with a same oxygen-uptake load during submaximal work increased in group H, but decreased in group L. 6) Rate pressure products both at rest and during submaximal exercise decreased significantly in group L. 7) Serum lipid levels remained in all groups. These results suggested that when the amount of exercise is the same, low-intensity exercise training with 35% VO2 max was more effective to increase endurance capacity and was safer than high-intensity exercise training.

Adolescent↗
PubMed1991

Effects of the consumption of cigarettes, alcohol and foods on serum concentrations of carotenoids, retinol and tocopherols in healthy inhabitants living in a rural area of Hokkaido.

The relationship between serum concentrations of carotenoids, tocopherols and retinol and the consumption of cigarettes, alcohol and foods was investigated in 835 healthy inhabitants (aged 35-79 years) of a rural area of Hokkaido. Serum concentrations of beta-carotene (BC), alpha-carotene (AC), lycopene (LY), beta-cryptoxanthin (BX), zeaxanthin (including lutein, ZX), canthaxanthin (CX) and beta-tocopherol (including gamma-tocopherol, BT) were higher in females than in males, while serum retinol (RE) concentrations were lower. Serum alpha-tocopherol (AT) concentrations were the same for both sexes. The serum values of BC, BX, AC, LY and ZX for males were inversely associated with the consumption of cigarettes in multiple-regression analysis. The serum values of BC, AC and BX for males were inversely associated with alcohol consumption, while serum RE values were positively related to alcohol consumption for both sexes. There were significant relations between serum values of BC, AC, and ZX and the intake frequencies of carrots, tomatoes, milk and/or green-leaf vegetables, especially for females, and between serum BX values and the intake of oranges, juices and fruits. Serum RE and AT concentrations were not associated with any food intake, and BT concentrations were associated with the intake of tomatoes and juices for males.

Adult↗