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Biomedical subjects

M Tetsuo

Publications and source records attributed to M Tetsuo.

At least 19 recordsLinked to original sources
PubMed1999

Gas chromatographic-mass spectrometric analysis of urinary sugar and sugar alcohols during pregnancy.

A refined and simplified method has been developed for the simultaneous analysis of urinary sugar and sugar alcohols after urease treatment by using capillary gas chromatography-mass spectrometry (GC-MS). Since carbohydrate metabolism during pregnancy is considered to be diabetogenic, our interest has been concentrated on understanding the mechanism of the metabolic deviation by assessing the glucose excursion and glucose fluxes. The present study suggests that changes of the levels of glucose, sorbitol, fructose, myo-inositol, and 1,5-anhydro-D-glucitol (1,5-AG) may reflect a mild alteration in carbohydrate metabolism that goes undetected by conventional diabetic indicators.

Carbohydrates↗
PubMed1992

The effects of glucose concentration on early embryogenesis using the whole embryo culture system on rats.

In order to investigate the effect of hyperglycemia on fetal teratogenesis, rat embryo culture was performed according to the method of New et al. The effect of hyperglycemia was then studied at glucose concentrations of 300, 600, 900 and 1,200 mg/dl in the medium. The embryos from the high glucose medium (600 mg/dl) had significantly shorter CRLs and fewer somites. Major anomalies characterized by neural lesions and minor anomalies characterized by extraneural lesions increased as the glucose concentration increased. However, fetal growth was promoted with statistical significance in the medium with 300 mg/dl of glucose, where the incidence of malformations remained unchanged as compared to the control group. The findings indicate that the glucose is one of the substantial compounds which influences embryo growth, development and abnormalities, but glucose alone appears to have no major effect on early embryogenesis in diabetic pregnancy.

Animals↗
PubMed1990

Serum levels of 1,5-anhydro-D-glucitol during the normal and diabetic pregnancy and puerperium.

In 25 normally non-pregnant women, 543 normally pregnant women and 75 pregnant women with diabetes mellitus or gestational diabetes mellitus, the relationship between the serum concentration of 1,5-anhydro-D-glucitol (1-deoxy-glucose) and carbohydrate metabolism was studied. The concentration of 1,5-anhydro-D-glucitol was estimated by means of gas-liquid chromatography. In normally non-pregnant women the concentration was found to be 18.6 +/- 5.2 mg/l (mean +/- SD). During the normal pregnancy, from 9 weeks of gestation, a steadily decreasing concentration was observed as the pregnancy progressed and the lowest value (10.2 +/- 4.6 mg/l) was found in the third trimester. After 5 days of puerperium the concentrations were found to be 10.8 +/- 3.7 mg/l. On the 30th day postpartum, the level was within the range for non-pregnant subjects. The values in pregnant women with diabetes mellitus and gestational diabetes mellitus were mostly below 10 mg/l throughout the entire pregnant period. The 1,5-anhydro-D-glucitol concentration was not affected by meals or oral glucose loading. A concentration below 10 mg/l was found in 36% of the normally pregnant women, where oral glucose tolerance tests and measurement of glycohemoglobin were shown to be within the normal range. The present study suggests that a change of 1,5-anhydro-D-glucitol level during pregnancy may reflect a mild alteration of carbohydrate metabolism that goes undetected by all the other diabetic indicators.

Blood Glucose↗
PubMed1989

Concentration and turnover of estradiol in the rat uterus in vivo.

The concentrations and turnover of estradiol isolated from cytosolic and nuclear fractions of uteri from ovariectomized rats given estradiol, either in single injections or in continuous infusion, were analyzed by gas chromatography-mass spectrometry. The analytical method was validated for different organs and lower limits of analysis were established. After infusion of 20 ng x h-1 for 18-22 h, mean estradiol levels were 2.0-2.4 fmol x mg-1 uterine wet weight in the nuclear fraction, and 1.2-1.5 fmol x mg-1 in the cytosolic fraction. The concentrations were about five times higher after a single injection of one microgram estradiol but the distribution between nuclear and cytosolic fractions was almost the same. The concentrations of estradiol in nuclei from liver and spleen were 50-200 times lower than those in uterus. Taken together with previous knowledge, the results indicate that the distributions of estradiol and its receptor are not the same and that hormone response cannot be predicted from the concentration of receptors alone. The exchange of estradiol molecules in the uterus was followed after a change of the infusion from unlabelled to [11,12,12-2H3]-labelled estradiol, or vice versa. The uterine uptake of estradiol was calculated to be about 0.7 fmol x h-1 x mg-1 uterine wet weight. The half-life time was calculated to be at least 4 h for estradiol molecules isolated from the nuclear fraction and 3 h (significantly shorter) for those isolated from the cytosolic fraction. The results indicate an uptake of 40-90% of all estradiol passing through the uterus in proestrus with only about 10% of available receptors becoming occupied. When the infusion was changed from estradiol to ethynylestradiol, estradiol disappeared from the uterus at the same rate as in the experiments above. Ethynylestradiol was taken up at a rate of about 0.3-0.4 fmol x h-1 x mg-1 tissue. The percentage of total steroid found in the nuclear fraction was higher for ethynylestradiol, about 70%, than for estradiol, about 60%, indicative of a more stable association of receptor to nuclear binding sites when ethynylestradiol is the ligand.

Animals↗
PubMed1982

Gas chromatographic-mass spectrometric analysis of endogenous levels of estradiol in plasma and in cytosol from rat uterus.

A method that permits the analysis of low levels of estradiol in plasma from women, men and rats and in cytosolic fractions of uterine tissue is described. The samples are extracted with Amberlite XAD-2 and a phenolic fraction is isolated on a lipophilic ion exchanger. Less polar contaminants in this fraction are separated from estradiol on Sephadex LH-20. Estradiol from human plasma can then be analysed by gas chromatography-mass spectrometry (GC-MS) as the trimethylsilyl ether using a capillary column and single ion monitoring of m/z 416. Samples from rat plasma and uterine cytosol require final purification by high-performance liquid chromatography prior to the GC-MS analysis. The approximate detection limits with the GC-MS instrument used were 1 x 10(-11)--2 x 10(-11) moles/l in plasma and 5 x 10(-11) moles/kg in the uterus. Problems in the purification procedures and the specificity and sensitivity of GC-MS analyses are discussed.

Animals↗
PubMed1982

Light exposure reduces and pinealectomy virtually stops urinary excretion of 6-hydroxymelatonin by rhesus monkeys.

The major metabolite of the pineal hormone melatonin, conjugated 6-hydroxymelatonin, was hydrolyzed, separated from the urine of rhesus monkeys, and assayed mass spectrometrically. The daily excretion pattern reflected pineal melatonin synthetic activity, being 5- to 16-fold higher at night than during the day. Progressive lengthening of the daily photoperiod beyond 12 h decreased the daily excretion of 6-hydroxymelatonin proportional to the increase duration of light exposure. Constant light reduced daily excretion by 90%, and pinealectomy reduced daily excretion by 96%. These results demonstrate the absence of significant extrapineal contributions to the urinary melatonin metabolite and confirm the use of 6-hydroxymelatonin excretion rates as a valid index of pineal gland melatonin synthesis.

Animals↗
PubMed1982

Melatonin metabolite excretion during childhood and puberty.

Daily urinary excretion of conjugated 6-hydroxymelatonin, the major metabolite of the pineal hormone melatonin, has been determined in 54 boys and 47 girls (aged 3-16 yr) and 20 normal adults to determine whether a change in melatonin production is seen during the maturation of reproductive function in humans. There was no correlation between daily excretion rates and age in children, and the excretion rates were similar to those in adults. In addition, children of all ages had normal circadian patterns of 6-hydroxymelatonin excretion from the earliest age tested. A significant increase in 6-hydroxymelatonin excretion was observed at the time of the onset of breast development (Tanner stage II) in girls. No similar difference was seen during puberty in males. The significance of this difference in Tanner II girls is not known.

Adolescent↗
PubMed1981

Urinary 6-hydroxymelatonin excretion in patients with orthostatic hypotension.

The rates of melatonin formation and its diurnal fluctuations have been examined in patients with three types of orthostatic hypotension by measuring the urinary excretion rates of 6-hydroxymelatonin, the major metabolite of the pineal gland hormone. Deficiencies in the peripheral autonomic nervous system resulted in markedly diminished daily excretion (2.5 +/- 1.3 micrograms) relative to control (12.2 +/- 1.2). Patients with impaired central nervous system function exhibited low and/or abnormal excretion patterns. Two patients with sympathotonic orthostatic hypotension excreted greater amounts of 6-hydroxymelatonin than any of the control subjects. Melatonin secretion by the pineal gland can be used as an index of sympathetic nerve function. The study of patients with altered function may reveal the role of the pineal gland in human physiology.

Adolescent↗
PubMed1980

Pinealectomy abolishes plasma melatonin in the rat.

Using gas chromatography-negative ionization mass spectrometry, plasma melatonin levels in pinealectomized and sham-operated rats were assessed. The pinealectomized rats consistently demonstrated an absence of plasma melatonin while the intact animals showed detectable amounts. This suggests that although melatonin may be formed in tissues other than a pineal gland, the contribution to plasma is of pineal origin. Thus, plasma melatonin levels can be used as a marker of circadian melatonin secretion by the pineal gland and of its beta-adrenergic regulation.

Animals↗