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Biomedical subjects

A Baba

Publications and source records attributed to A Baba.

At least 307 records · Page 17Linked to original sources
PubMed1978

Characterization of thiamine diphosphatase in rat small intestine.

The properties of thiamine diphosphatase (TDPase) and p-nitrophenylphosphatase (p-NPPase) in rat small intestine were investigated. TDPase activity, like p-NPPase activity, was high in the mucosa and in the proximal region. Both activities were high in the membrane-associated fractions of the duodenal mucosa. Furthermore, TDPase had the same properties as intestinal alkaline phosphatase (al-Pase). These results suggest that thiamine diphosphate (TDP) and p-nitrophenylphosphate (p-NPP) are hydrolyzed by a single enzyme, al-Pase, in the intestine.

4-Nitrophenylphosphatase↗
PubMed1978

Centrally mediated hyperglycemia by 6-aminonicotinamide.

Some metabolic changes induced by the intraventricular administration of 6-aminonicotinamide (6-AN) were studied in mice. Five or ten microgram/animal of 6-AN produced a marked hyperglycemia, lowered glycogen content in the brain and liver, and reduced the adrenal epinephrine content. Adrenalectomy or hexamethonium prevented 6-AN-induced hyperglycemia and decrease of glycogen content in the liver but not in the brain. Decrease of adrenal epinephrine content induced by 6-AN was overcome by hexamethonium. Pretreatment with 6-AN (10 microgram/animal) markedly lowered the toxic action, but not the hypoglycemic action, of a large dose of insulin.

6-Aminonicotinamide↗
PubMed1977

The mechanism of actions of collagenase on the inhibition of release of acetylcholine from synaptosomal preparations.

The release of acetylcholine from synaptosomal preparations from bovine superior cervical ganglia and rat cortex was inhibited when the preparations were pretreated with collagenase. The inhibition of release could be overcome with the calcium ionophore A23187. Collagenase treatment was shown to inhibit the uptake of calcium into the preparations. In addition, gel electrophoresis of synaptosomal membranes revealed two missing high molecular weight proteins when either synaptosomes or synaptosomal membranes were incubated with collagenase.

Acetylcholine↗
PubMed1977

Possible regulation of thiamine diphosphatase activity in rat brain microsomes by lipids.

The effects of various treatments, which affect membrane structure, on microsomal thiamine diphosphatase and thiamine triphosphatase activities of rat brain, were examined. The treatment of micorosomes at alkaline pH caused a 2-fold activation of the thiamine diphosphatase, this being related to a change in membrane structure which was evidenced by a decrease of the turbidity of the microsomal suspension. Repeated freezing and thawing after hypo-osmotic treatment also increased the activity of microsomal thiamine diphosphatase. In addition, the thiamine diphosphatase activity was enhanced by treatment of the microsomes with phospholipase C or acetone. This lipid depletion resulted in a marked reduction in the apparent Km value of the thiamine diphosphatase with a corresponding loss in heat stability of the enzyme. We found further that brain thiamine diphosphatase was solubilized by Triton X-100. This decreased the phospholipid content in the preparation, but did not affect the apparent Km value and heat stability of the enzyme. In contrast with thiamine diphosphatase, thiamine triphosphatase was inactivated by treatment at alkaline pH or with acetone. However, treatment with phospholipase C did not affect the activity of thiamine triphosphatase.

Animals↗
PubMed1977

The properties of Corbicula sandai apoferritin.

Corbicula sandai apoferritin possesses physical properties different from apoferritins of other species. The native molecular weight was estimated from its s020,w of 18.7 S to be about 503 000. Empirical molecular weight estimation methods in denaturing solvents yielded a molecular weight estimate for the constituent polypeptide chain of 23 000. The circular dichroic spectrum of C. sandai apoferritin was significantly different from other apoferritins and it was immunologically unreactive with rabbit anti-human ferritin antisera.

Amino Acids↗
PubMed1976

Thiamine diphosphatase in rat small intestine.

TDPase is located mostly in the proximal portion of the small intestine and its activity, like that of ALPase, decreased markedly in thiamine deficiency. The decreased enzyme activities were restored after thiamine or vitamin D3. Kinetic and other studies of the purified enzyme indicated the identity of the two enzymes.

Alkaline Phosphatase↗
PubMed1975

Effect of various nucleotides and drugs on microsomal thiamine diphosphatase activity in rat brain.

The basic properties of microsomal thiamine diphosphatase (TDPase) in rat brain were examined. It was mainly localized in the microsomal fraction. Microsomal TDPase showed an absolute requirement for divalent cation which was best satisfied by Ca++. Theophylline (1 mM), NADP (0.1 mM) and NADPH (0.1 mM) significantly inhibited its activity. However, caffeine, theobromine, NAD and various putative neurotransmitters did not affect the enzyme activity. UDP was inhibitory and IDP was a competitive inhibitor, but ATP had no effect on the enzyme activity.

Animals↗
PubMed1974

Role of thiamine metabolism in the central nervous system. I. Basic properties of thiamine triphosphatase in rat brain.

The properties of soluble and microsomal thiamine triphosphatase (TTPase) in rat brain were examined. The subcellular distributions and the pH optima of these enzyme activities differ markedly. TTPase seems to be distinct from a general nucleoside triphosphatase. The TTPase activities have an absolute divalent cation requirement which is fulfilled by Mg-++ or Ca-++ in microsomes and by Mg-++, but not Ca-++, in the soluble fraction. Addition of a physiological concentration of Ca-++ markedly inhibited the soluble TTPase activity.

Animals↗
PubMed1974

Role of thiamine metabolism in the central nervous system. II. Effects of various agents on thiamine triphosphatase activity in rat brain.

The effects of various agents on the activity of brain thiamine triphosphatase (TTPase) in vivo and in vitro were studied. Thiamine deficiency caused a significant increase in soluble TTPase activity and a decrease in membrane-associated TTPase activity. Insulin and a fasting state did not affect these enzyme activities. DL-Methamphetamine (10mg/kg i.p.) increased the activity of the soluble TTPase, whereas reserpine (2.5 mg/kg i.p.) caused no change in the enzyme activities. A single injection of chlopromazine (25 mg/kg s.c.) had no effect on the microsomal or soluble TTPase activities, but repeated injections reduced the activity of the microsomal enzyme. The effects of various neuroactive agents on microsomal TTPase activity were examined in vitro. Among the drugs tested, only chlorpromazine caused marked inhibition of the enzyme activity.

Acetylcholine↗