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Biomedical subjects

M Komatsu

Publications and source records attributed to M Komatsu.

At least 199 records · Page 11Linked to original sources
PubMed1994

Nontoxic intravitreal dose of ofloxacin for rabbit retina.

We studied the nontoxic intravitreal concentration of ofloxacin, a new quinolone antibacterial agent, by evaluating its effects on in vitro and in vivo electroretinograms (ERGs) in albino and pigmented rabbits. After perfusion with a 36 micrograms/ml solution of ofloxacin, the in vitro ERG remained unchanged. The in vivo ERG and the visually evoked potential remained unchanged 4 weeks after vitrectomy with 50 micrograms/ml ofloxacin, and the retina was within normal limits both ophthalmoscopically and histologically. Therefore, the retinal toxicity of ofloxacin is low and within safe limits at clinical dosage.

Animals↗
PubMed1994

Acid profiles and pH of carious dentin in active and arrested lesions.

Organic acids in caries lesions play important roles in initiation and progress of dental caries. We investigated relationships between clinical types of dentin caries and acid profile or pH in the lesions. Caries lesions in dentin from 76 permanent teeth were classified into active, arrested, situated beneath a restoration, and unclassified types. The pH of carious dentin was distinctly lower than that of sound dentin (p < 0.001). Carious dentin with a high percentage of lactate had a lower pH than that with a high percentage of acetate and propionate (p < 0.001). Dentin from active lesions showed a mean pH of 4.9, and the dominant acid was lactate (mean percentage, 88.2). In contrast, carious dentin from arrested lesions showed a higher pH, 5.7, with acetate and propionate as the dominant acids (mean percentages of acetate and propionate, 64.0 and 18.2, respectively). The acid profile (mean percentages of acetate and propionate, 54.0 and 27.7, respectively) and pH (mean 5.8) of carious dentin sampled from lesions beneath a restoration were similar to those of dentin from arrested lesions. This study showed a clear relationship between clinical classification of dentin caries and acid profile and pH, suggesting that both factors are important in dentin caries etiology.

Acetates↗
PubMed1994

Cytotoxicity of 1,3-dichloropropene and cellular phospholipid peroxidation in isolated rat hepatocytes, and its prevention by alpha-tocopherol.

1,3-Dichloropropene induced time- and dose-dependent toxicity and lipid peroxidation were examined in isolated rat hepatocytes. HPLC method with chemiluminescence detection (CL-HPLC) was employed to determine phosphatidylcholine hydroperoxide (PCOOH) and phosphatidylethanolamine hydroperoxide (PEOOH) contents. The release of lactate dehydrogenase (LDH) as a toxicological parameter was significantly increased after 90 min incubation at 1 mM of 1,3-dichloropropene and after 60 min incubation at 5 mM, respectively. The cellular PCOOH and PEOOH contents were increased after 90 min incubation at 1 mM of 1,3-dichloropropene, and after 15 min for PCOOH and 30 min for PEOOH at 5 mM, respectively. The increase of cellular phospholipid hydroperoxide preceded the cytotoxicity. Hepatotoxicity was effectively prevented by preincubation with d,1-alpha-tocopherol (alpha-toc.) accompanied by prevention of the membrane phospholipid peroxidation. In conclusion, the peroxidation of phospholipid preceded cytotoxicity, and cytotoxicity was effectively prevented by alpha-toc. These results indicated that the peroxidative degradation of membrane phospholipid is one of the main causes of cytotoxicity by 1,3-dichloropropene.

Allyl Compounds↗
PubMed1994

[Studies on antiulcer agents. I. The effects of various methanol and aqueous extracts of crude drugs on antiulcer activity].

The antiulcer activities of 59 methanol and aqueous extracts obtained from 59 crude drugs on the ethanol-HCl-induced ulceration in rats were investigated. Among them 15 extracts were selected and they were further examined for their effects on indomethacin-, aspirin- and the water-immersion stress-induced ulcer. From these results, the methanol extract of root of Iris germanica was found to, show potent antiulcer activities. The above methanol extract was separated into 3 portions by solvent extraction, and the ether soluble portion was fractionated into 5 fractions (1 to 5) by chromatography. Fractions 4 and 5 showed significant antiulcer activities. Fraction 4 was further purified and the obtained gamma-irigermanal exhibited a potent antiulcer activity. However, further investigations are required to understand the mechanism.

Animals↗
PubMed1994

[Studies on antiulcer agents. II. Synthesis and antiulcer activity of phenylpropanol derivatives].

It was found that gamma-irigermanal, obtained from the methanol extract of root of Iris germanica, exhibited a potent antiulcer activity. Therefore, this compound was selected as a lead-compound, and related compounds were synthesized and tested for antiulcer activities. It was found that (+/-) ethyl 2-[2-(3-hydroxypropyl)-4-oxocyclohexylidene]- propionate (1) had excellent antiulcer activities. Then phenylpropanol derivatives, obtained by changing from cyclohexane ring of 1 to benzene ring, were synthesized and tested for antiulcer activities in order to study structure activity relationships. As a result, (+/-) ethyl 2-[2-(3-hydroxypropyl)-4,5-dimethoxy-phenyl]propionate (2b) and (+/-) 3-[2-(3-hydroxypropyl)-4,5-dimethoxyphenyl]-2-butanone (5) were shown to have antiulcer activities.

1-Propanol↗
PubMed1994

A family with hereditary high serum thyroxine-binding globulin.

A family with hereditary high serum thyroxine-binding globulin was studied. All the subjects studied were clinically euthyroid without goiter. The propositus (female), her mother and sister had high TBG, total T4 and total T3 with normal free T4, free T3 and TSH. Her father's thyroid function was within the normal range. Possible etiologic factors causing secondary hyper-TBG-nemia were ruled out in all the affected subjects. Isoelectric focusing demonstrated qualitatively normal microheterogeneity, ruling out possible TBG variations caused by liver diseases, estrogen therapy or pregnancy. Although the mechanism involved in the TBG increase awaits further investigation, it could be an abnormality in the gene controlling the synthesis of TBG.

Adult↗
PubMed1994

Responses to hemodynamic stress in the aged heart.

In aged individuals the incidence of heart failure is higher than in younger subjects. Ischemic events are also common in the aged heart because of changes in the coronary vasculature and myocytes caused by aging. Adaptational responses to increased hemodynamic overload and to ischemia in the aged heart are discussed at the molecular, cellular and organ levels. One characteristic of the aged heart is a limited capacity for adaptation with hypertrophy to increased mechanical load. This age-related attenuation of the hypertrophic response may be attributed to the diminished induction of proto-oncogenes such as c-fos, c-myc and c-jun by hemodynamic stress. This diminution results from the aging of the heart per se and may be modulated by extracardiac factors. An age-related diminution was also observed in the mRNA induction of heat shock proteins by transient ischemia. However, this diminished induction of immediate early genes in the aged heart was not observed after more severe stress. With regard to the coronary vasculature, the age at which pressure-overload begins seems to be one of the important factors which determine the vascularity of hypertrophied hearts. Late-onset pressure-overload decreased dilator reserve in spite of the absence of myocardial hypertrophy. Thus, the responses to stress in the aged heart are quite different from those in the young heart. The limited capacity for adaptation to hemodynamic overload and poor protective mechanisms against stress may be causes of the higher incidence of heart failure in the aged.

Aged↗
PubMed1994

Syndrome of inappropriate secretion of ADH (SIADH) due to small cell lung cancer with extremely high plasma vasopressin level.

A 76-year-old man with small cell lung cancer associated with the syndrome of inappropriate secretion of ADH (SIADH) visited our hospital. The serum Na level was normal on the first visit, but 2 weeks later it decreased to 114 mEq/L with an extremely high plasma vasopressin (VP) level of 1520 pg/ml. Serum Na was normalized after the reduction of the tumor size by chemotherapy, but the plasma VP level remained between 150 to 600 pg/ml. On gel filtration of plasma VP two peaks of immunoreactive VP were eluted at the positions of a larger molecule than authentic VP and authentic VP, and VP in urine gave only one peak compared to that of authentic VP. The dilution curve of plasma VP was almost parallel and that of urine was completely parallel to the standard curve. These findings suggest that a larger VP with low physiological activity was predominantly secreted in the present patient and manifested relatively mild symptoms despite the extremely high plasma VP level.

Aged↗
PubMed1994

[A longitudinal study of brain atrophy and its relation with background factors and common carotid hemodynamics].

This longitudinal study was performed to clarify the relation between brain atrophy and common carotid hemodynamics. A total of 147 patients, including 70 males and 77 females, who had neither neurologic deficits nor organic lesions on computed tomography of the brain, were enrolled in this study. The ages of the patients ranged from 47 to 76 years (mean: 62 years) at the first diagnosis of brain atrophy. The patients were divided into three groups: 66 controls without hypertension or diabetes mellitus (Group I), 60 with hypertension (Group II) and 21 with both hypertension and diabetes mellitus (Group III). Brain atrophy was diagnosed by caudate head index (CHI). Mean blood flow volume (BF) at the right common carotid artery was measured by an ultrasonic quantitative flow measurement system. Both CHI and BF were measured twice at a mean interval 6.5 years. Increment in CHI per year (delta CHI) and decrement in mean blood flow volume per year (delta BF) were calculated. delta CHI of Group I and Group II had a significant relation with aging. delta CHI of Group III showed a larger increase than that of both Group I and Group II in subjects in the sixties. delta CHI had a significant relation with delta BF in each group. These results indicate that complication of both HT and DM, or decrement in mean blood flow volume may cause brain atrophy to progress.

Aged↗
PubMed1994

[Ultrasonography in the diagnosis of malignant lymphoma of the thyroid].

Malignant lymphoma of the thyroid was rare condition and it was difficult to make a diagnosis of malignant lymphoma preoperatively. Both ultrasonographic appearance and diagnostic significance of ultrasonography in malignant lymphoma of the thyroid were investigated in this study. Ultrasonography of 10 patients with malignant lymphoma of the thyroid was analyzed. Only 3 cases of 10 were diagnosed as malignant lymphoma by ultrasonography. Five cases were misdiagnosed as thyroid carcinoma, 1 as adenomatous goiter accompanied by cystic degeneration and 1 as chronic thyroiditis. Nine cases were nodular type i.e. limited extremely hypoechoic mass as contrasted with surrounding thyroid tissue, occupying asymmetrically in the thyroid gland. One case was diffuse type i.e. diffused hypoechoic area without surrounding residual thyroid tissue. The tumor size of the 2 cases in which no accumulation was observed in the 67Ga scintigram was 2 cm or less. By ultrasonography of these 2 cases, one case was diagnosed as malignant lymphoma and the other as thyroid carcinoma. Ultrasonography can be regarded to be very significant method as a screening test to make a diagnosis of malignant tumor for nodular type, especially small sized malignant lymphoma of the thyroid.

Aged↗
PubMed1994

[Relationship between child epilepsy and MRI findings in von Recklinghausen neurofibromatosis (NF 1)].

Fourteen children meeting the NIH consensus diagnostic criteria for NF 1 were evaluated at the Department of Pediatrics, Himeji Red Cross Hospital. MRI and EEG were examined in all patients, respectively. Four of 14 patients had a history of epilepsy, two had suffered West syndrome, one had complex partial seizures and one had secondary generalized partial epilepsy. Seven (50%) of 14 patients showed abnormal MRI; three (75%) of 4 patients with epilepsy and four (40%) of 10 patients with epilepsy showed low intensity on T1 weighted images and hyperintensity on T2 weighted images in the globus pallidus and brainstem. These results suggest that children with NF 1 have a spectrum of MRI abnormalities, irrespective of existence of epilepsy.

Brain↗
PubMed1993

Mastoparan stimulates exocytosis at a Ca(2+)-independent late site in stimulus-secretion coupling. Studies with the RINm5F beta-cell line.

Mastoparan, a tetradecapeptide from wasp venom, stimulated exocytosis in a concentration-dependent manner, which was enhanced by pertussis toxin pre-treatment, in the insulin secreting beta-cell line RINm5F. Mastoparan (3-20 microM) also elevated cytosolic free calcium concentration ([Ca2+]i), a rise that was not attenuated by nitrendipine. Divalent cation-free Krebs-Ringer bicarbonate (KRB) medium with 0.1 mM EGTA nullified the mastoparan-induced increase in [Ca2+]i, suggesting that the peptide increased Ca2+ influx but not through the L-type voltage-dependent Ca2+ channel. Depletion of the intracellular Ca2+ pool did not affect the mastoparan-induced elevation of [Ca2+]i. Remarkably, in divalent cation-free KRB medium with 0.1 mM EGTA and 2 microM thapsigargin in which mastoparan reduced [Ca2+]i, the mastoparan-stimulated insulin release was similar to that in normal Ca(2+)-containing KRB medium. Inhibitors of protein kinase C, such as bisindolylmaleimide, staurosporine, and 1-O-hexadecyl-2-O-methyl-rac-glycerol did not suppress the mastoparan-stimulated insulin release. Mastoparan at 10-20 microM did not increase cellular cAMP levels, nor did mastoparan at 5-10 microM affect [3H]arachidonic acid release. In conclusion, although mastoparan increased [Ca2+]i, this increase was not involved in the stimulation of insulin release. Rather, the data suggest that mastoparan directly stimulates exocytosis in a Ca(2+)-independent manner. As GTP-binding proteins (G proteins) are thought to be involved in the process of exocytosis and as mastoparan is known to exert at least some of its effects by activation of G proteins, an action of mastoparan to activate the putative stimulatory Ge (exocytosis) protein is likely.

Animals↗
PubMed1993

Role of dehydroepiandrosterone and dehydroepiandrosterone sulfate for the maintenance of axillary hair in women.

To delineate the relationship between sex hormones and the axillary hair in women, serum concentrations of dehydroepiandrosterone, dehydroepiandrosterone sulfate and testosterone were measured in 177 normal women (aged 16 to 76 y). Both menstrual cycle and axillary hair were present in all normal women younger than 50 years. In the 6th decade, axillary hair was present in 21 of 42 normal women but menstruation was present only in 8 of the 42 women. In the 7th and 8th decades, axillary hair was present in 36% and 25% of them, respectively. None of the subjects over 60 years of age had a menstrual cycle. Serum dehydroepiandrosterone and dehydroepiandrosterone-sulfate concentrations were significantly higher in axillary hair-positive than in -negative women after 50 years of age. Serum testosterone concentration was low in normal women after 50 years of age compared to those of under 49 years, and it was marginally lower in axillary hair-negative than in -positive normal women. However the difference between the axillary hair-positive and -negative subjects was not statistically significant. It is suggested that weak adrenal androgens such as dehydroepiandrosterone and dehydroepiandrosterone-sulfate, rather than testosterone, play an important role for the maintenance of axillary hair in aged women.

Adolescent↗
PubMed1993

Possible link between a low prevalence of cardiovascular disease and mild dyslipidaemia: a study in Japanese patients with type 2 diabetes.

In 98 Japanese patients with Type 2 diabetes mellitus, serum total cholesterol, triglyceride, high density lipoprotein cholesterol (HDL-C), free fatty acid (FFA), and apolipoproteins (apo) A-I, A-II, B, C-II, C-III, and E were determined. The data were compared with those in 47 normolipidaemic normal controls. The total cholesterol value of the diabetic patients was also compared to that of a general population (n = 2227). The diabetic patients were separated into those with cardiovascular disease (n = 20) and without it (n = 78) and a comparison of clinical characteristics and dyslipidaemia was also performed. The diabetic patients had slightly but significantly higher FFA, LDL-C, apo B, C-II, C-III, E, and B/A-I, and lower apo A-I and A-II compared to the normal controls. The total cholesterol level of the diabetic patients (5.17 +/- 0.96 mmol-1) was not significantly higher than that of the general population (5.12 +/- 0.91 mmol-1). By multivariate stepwise discriminant analyses, only total cholesterol significantly discriminated the patients with and without cardiovascular disease. In Japanese patients with Type 2 diabetes, a diabetic population with a very low prevalence of cardiovascular disease, high total cholesterol is a risk factor for developing cardiovascular disease. Nevertheless, a markedly low prevalence of cardiovascular disease in Japanese with Type 2 diabetes compared to Caucasian counterparts may partly be due to the mildness of dyslipidaemia.

Aged↗
PubMed1993

Intravitreal flomoxef sodium in rabbits.

We studied the intraocular concentration of flomoxef sodium in nonvitrectomized and vitrectomized eyes of albino rabbits after intravenous administration of 100 mg/kg flomoxef sodium. The concentration of flomoxef sodium in the vitreous body was undetectable (< 0.1 micrograms/ml) in nonvitrectomized eyes. Retinal toxicity of flomoxef sodium was investigated with ophthalmoscopy, electroretinography (ERG) and light microscopy after intravitreal injection of 200, 500, 1,000 and 2,000 micrograms flomoxef sodium in albino and pigmented rabbits. No ERG changes were induced with 200 micrograms. Other higher doses caused transient ERG changes. After the 200-micrograms injection, the intravitreal concentration decreased exponentially, the half-life being 4.4 h. The antibacterial activity, broad coverage and low intravitreal toxicity of flomoxef sodium suggest that this compound may be used to treat bacterial endophthalmitis.

Animals↗