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Biomedical subjects

A Tomoda

Publications and source records attributed to A Tomoda.

At least 109 records · Page 6Linked to original sources
PubMed1977

Opposite effect of organic phosphates on hemoglobin oxidation by hydroxylamine under aerobic and anaerobic conditions.

The effect of organic phosphates such as inositol hexaphosphate (IHP), ATP, and 2,3-diphosphoglycerate (2,3-DPG) on hemoglobin oxidation by hydroxylamine was studied under aerobic and anaerobic conditions. Under aerobic conditions, the oxidation rate of hemoglobin by hydroxylamine was accelerated as much as about 1.6 times, 1.4 times, and 1.4 times in the presence of IHP, ATP, and 2,3-DPG, respectively; however, under anaerobic conditions it was inhibited as much as 2.2 times, 2 times, and 2 times in the presence of these organic phosphates compared with the case for the absence of these organic phosphates. The effects of these organic phosphates on hemoglobin oxidation by hydroxylamine under aerobic conditions were elucidated by the two state models of hemoglobin including the R and the T state, however, the opposite effects under anaerobic conditions cannot be explained without the assumption of the existence of a third conformation of hemoglobin. The dissociation constant of IHP to deoxyhemoglobin was estimated from the rate of the hemoglobin oxidation by hydroxylamine in different concentrations of IHP under anaerobic conditions.

Adenosine Triphosphate↗
PubMed1977

Glycolysis of red cells suspended in solutions of impermeable solutes. Intracellular pH and glycolysis.

The glycolytic rate human red cells suspended in a sucrose medium of low or physiological pH was higher than that of the cells suspended in Ringer's medium of the same. pH. The medium pHP-glycolytic rate curve of red cells suspended in soucrose media shifted to the acidic side by about one unit compared with that of cells suspended in Ringer's medium. Similarly, the pattern of glycolytic intermediates in red cells suspended in a sucrose medium resembled that in cells suspended in Ringer's solution of about one unit higher pH. These phenomena could be ascribed to the change of intracellular pH, which was measured by the 5,5'-dimethyl-oxazolidine-2,4-dione method. A similar stimulation of glycolysis was observed when sodium citrate was added to red cells suspended in Ringer's solution at constant pH. These observations indicate that membrane-impermeable non-electrolytes or anions stimulate glycolysis of red cells by elevation ofthe intracellular pH. Red cell glycolysis is influenced mainly by the intracellular pH rather than by the pH of the suspending medium.

Adenosine Triphosphate↗
PubMed1977

Accumulation of phosphoenolpyruvate in red cells incubated with the phosphate ester in an acidified isotonic sucrose medium.

Accumulation of exogenous phosphoenolpyruvate against the concentration gradient was observed when human red cells were incubated in an acidified isotonic sucrose medium. Fluoride increased the apparent accumulation by inhibition of the intracellular metabolic interconversion of the phosphate compound. The accumulation appeared to be specific for phosphoenolpyruvate and the accumulation rate for 3-phosphoglycerate, which has a molecular size and pKa similar to those of phosphoenolpyruvate, was less than one-tenth of the rate of phosphoenolpyruvate. Red cells incubated in the acidified sucrose medium tended to adhere to each other when examined with a scanning electron microscope.

Biological Transport, Active↗
PubMed1976

Effect of organic phosphates on methemoglobin reduction by ascorbic acid.

The rate of methemoglobin reduction by ascorbic acid was accelerated in the presence of ATP,2,3-diphosphoglycerate (2,3-DPG), and inositol hexaphosphate (IHP). The acceleration was as much as three times, four times, and ten times in the presence of ATP, 2.3-DPG, and IHP at pH 7.0, respectively. The changes of the concentrations of methemoglobin and ascorbic acid during the methemoglobin reduction were determined, and the reaction was found to proceed stoichiometrically in the presence of IHP. The reduction rate of methemoglobin by ascorbic acid was compared at different concentrations of organic phosphates (ATP,2,3-DPG, and IHP) at various pH values (6.3, 7.0, 7.7). From the changes in the reduction rate under different concentrations of organic phosphates, the dissociation constants of ATP, 2,3-DPG, and IHP to methemoglobin could be determined and were estimated to be 3.3 X 10(-4) M, 2 X 10(-3) M, and 8 X 10(-6) M at pH 7.0, respectively. On the basis of these results, the acceleration mechanism of methemoglobin reduction by ascorbic acid due to the presence of organic phosphates was described. The physiological role of 2,3-DPG in human red cells was discussed in relation to the reduction of methemoglobin by ascorbic acid.

Adenosine Triphosphate↗
PubMed1975

Intracellular pH (pHi) of red cells stored in acid citrate dextrose medium. Effects of temperature and citrate anions.

The intracellular pH (pHi) of red cells stored in acid citrate dextrose (ACD) medium was estimated by the 5,5'-dimethyloxazoldine,-2,4-dione (DMO) method. The initial pHi at 4degrees was about 7.6 and was higher than the extracellular pH (pHe) at 4degrees. During storage, both pHi and pHe decreased, but the former was always higher than the latter and the former decreased more slowly than the latter. The high pHi of ACD blood was a results of the temperature at which the pHe and the pHi were measured (4degrees) and the presence of citrate anions in the medium, and could be explained by application of the Donnan-Gibbs equilibrium. ATP and 2,3-diphosphoglycerate (DPG) were well-maintained in heparinized blood when it was acidified and pHe and pHi at 4degrees were both about 7.4, which suggests that improvement of blood preservation may be attained by suitable adjustment of the pHi and pHe of the blood.

Adenosine Triphosphate↗
PubMedDate not supplied

Central nervous system disorders and possible brain type carnitine palmitoyltransferase II deficiency.

We describe two male infants with central nervous system disorders, i.e. infantile spasms in one and athetotic quadriplegia in the other, and with recurrent attacks of high plasma creatine kinase levels induced by viral infections. Although carnitine palmitoyltransferase I (CPT I) activity in biopsied muscle was normal in both cases, that of carnitine palmitoyltransferase II (CPT II) was decreased to 37% and 25% of the control value, respectively. Meanwhile, to determine whether or not and how CPT exists in the central nervous system (CNS), we studied animal brain tissues. CPT activity was demonstrated in almost all regions, especially in the brainstem, cerebellum and spinal cord. Although CPT deficiency can be classified into hepatic (CPT I) and muscular (CPT II) presentations, these data suggest that another symptomatology of CPT II deficiency with CNS involvement (brain type?) might exist.

Animals↗
PubMedDate not supplied

Two patients with distal muscular dystrophy and autonomic nerve dysfunction.

Two female patients with distal muscular dystrophy (Miyoshi) are reported. Neurological examination revealed marked weakness and a low skin temperature of both lower legs, especially over the gastrocnemius muscle. Biopsy specimens of the anterior tibial muscle exhibited myopathological features compatible with a dystrophic change and showed positive dystrophin reactions with all six antibodies used. Autonomic nerve studies in both patients, including laser Doppler flowmetry (LDF), component analysis of the cardiographic R-R interval and a sympathetic skin response (SSR) test, demonstrated marked abnormalities, such as sensitive vasoconstrictive responses, a suppressed peak of low frequency components and an absence of SSR, respectively, compared with findings in healthy controls. Sympathetic nerve blocking by means of epidural anesthesia produced clinical improvement and a marked decrease in the serum CK level in one patient. Although the etiology of autonomic nerve disturbances in these cases remains to be elucidated, a positive immunoreactivity of nerve growth factor receptor (NGFR) implies the possibility of some unknown sympathetic neurovascular disorder involving muscle degeneration.

Adolescent↗
PubMedDate not supplied

A school refusal case with biological rhythm disturbance and melatonin therapy.

An 18-year-old male high school student with school refusal and circadian rhythm disturbance is reported. At 17 years of age, he was unable to attend school because of a reversal of the daily rhythm and a moderate depressive feeling. Other circadian rhythms, including deep body temperature (DBT), and plasma melatonin, cortisol and beta-endorphin, also showed quite different or abnormal curves compared with those in normal controls. He was treated with methyl B12 and melatonin, which normalized the circadian rhythm, i.e. it became entrained to a 24-h period, and the DBT and hormonal rhythms became closer to normal patterns. These results suggest that desynchronization of the biorhythms, particularly the circadian rhythm, may be one of the important causes of school refusal in Japan, and melatonin and methyl B12 might be useful for treatment of the condition.

Adolescent↗