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Biomedical subjects

K Yamada

Publications and source records attributed to K Yamada.

At least 19 recordsLinked to original sources
PubMed1979

Specificity and selectivity of diacylglycerolphosphate synthesis in Escherichia coli.

The glycerolphosphate and 1-acylglycerolphosphate acyltransferase systems Escherichia coli membranes show relatively low specificities for acylcoenzymes A when maximal velocities for the respective acyl-coenzymes A are compared. However, the selectivities for palmitate and oleate in the acylations of the 1- and 2-positions of glycerolphosphate moiety, respectively, are higher at lower concentrations of acceptors in the presence of an equimolar mixture of palmitoyl-CoA and oleoyl-CoA. More 1-palmitoyl-2-oleoyl-glycerolphosphate species and less other species were synthesized at lower concentrations of glycerolphosphate. The fatty acyl moiety at the 1-position of 1-acylglycerolphosphate did not influence significantly the specificity for acyl-coenzymes A of the 1-acylglycerolphosphate acyltransferase system. Thus, the acceptor concentrations being kept low in vivo and in vitro are important for the highly selective incorporations of saturated and unsaturated fatty acids into the 1- and 2-positions of diacylglycerolphosphate, respectively, in the presence of mixtures of saturated and unsaturated acyl-coenzymes A while these acyltransferase systems exhibit relatively low specificies for acyl-coenzymes A when the respective maximal velocities are compared.

Acyltransferases↗
PubMed1979

Ultrastructural features of acidic complex carbohydrates in the intercellular matrix of the ovarian follicles in adult mice.

In the intercellular matrix of the granulosa layer of the mouse ovarian follicles, ultrastructural features of acidic complex carbohydrates have been studied by means of dialyzed iron (DI) staining in combination with procedures of digestion with Streptomyces and testicular hyaluronidases. In the intercellular matrix, DI reactive structures containing acidic complex carbohydrates consist of layers of a variable thickness coating the plasma membrane of the granulosa cells and reticular elements distributed in the spaces between the cells. The latter exists in two appearances; one is clumped masses of irregular shapes and different sizes, whereas the other being filamentous figures radiating from the masses. The effects of digestion with Streptomyces and testicular hyaluronidases upon the DI staining of the tissues indicate that the DI reactive structures in the intercellular matrix contain at least three types of acidic complex carbohydrates; hyaluronic acid, isomeric chondroitin sulfates and other acidic glycosaminoglycans. The histophysiological activities played by these particular complex carbohydrates have been briefly discussed.

Animals↗
PubMed1979

Serotonergic function in mouse head twitches induced by lithium and reserpine.

We examined the relationship between lithium-induced head twitches and serotonergic neurons. Head twitches were elicited by combined treatment with lithium chloride (2 or 5 mEq/kg x 5, s.c. administered hourly) and rauwolfia alkaloids, i.e., reserpine (5 mg/kg, s.c.), tetrabenazine (20 mg/kg, s.c.), and syrosingopine (10 mg/kg, s.c.). Neither lithium nor the alkaloid alone induced the twitches; nor did combined administration of lithium with methamphetamine or p-chloroamphetamine. The head twitches induced by lithium in combination with reserpine were strongly inhibited by antiserotonin drugs, methysergide and cyproheptadine, and also by a serotonin synthesis inhibitor, p-chlorophenylalanine (PCPA), when administered between lithium and reserpine. When PCPA was administered before lithium for 3 days, the head twitches were potentiated. In addition, the head twitches were potentiated by a serotonin receptor stimulant, 5-methoxy-N,N-dimethyltryptamine. The results imply that lithium can induce head twitches in the presence of rauwolfia alkaloids and may exert its effect in part by acting on the serotonergic neuron system.

Acetylcholine↗
PubMed1979

Intra-arterial BCNU therapy in the treatment of metastatic brain tumor from lung carcinoma: a preliminary report.

Nine patients with intracerebral metastasis from lung carcinoma were treated with intracarotid and intravertebral artery infusion of 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU). Four of these patients considered definite responders showed unequivocal clinical improvement and definite decreases in the size of tumors evaluated by neurologic examination, computerized tomographic (CT) scan and radionuclide brain scan (RBS). One patient's clinical condition stabilized with doubtful improvement of diagnostic tests (probable responder). The remaining four patients had further unfavorable progression of the clinical and scan findings and were clearly nonresponders. Complications were transient and included: local pain in the eye, orbit, and occipital-nuchal area during infusion in 7 patients, focal seizure in 3 patients, mild confusion with disorientation in 2 patients, and nausea in 2 patients. Our findings suggest that intra-arterial BCNU therapy may be effective and may be used as an adjuvant to surgery and/or radiotherapy for the treatment of metastatic brain tumor from lung carcinoma.

Adult↗
PubMed1979

Comparison of intramural 5-fluorouracil and more conventional routes of drug administration on concentrations in gastric regional lymph nodes: a potential for trans-endoscopic adjuvant chemotherapy.

Intramural injection of 20 muCi (2-14C) 5-fluorouacil (5-FU) into the gastric submucosa of dogs and baboons was employed to evaluate the kinetics of 5-FU distribution following this route of administration and to compare these results with those following intraluminal, intravenous, and local intraarterial injections. Measurements of radioactivity taken over a six-hour period after injections demonstrated that the greatest concentration of isotope in samples of gastric wall and perigastric lymph nodes was found after administration of the drug directly into the stomach wall. Clinical application of intramural injections of 5-FU into the stomach wall under direct gastroscopic visual control, may be worthy of trial in patients with gastric cancer.

Animals↗
PubMed1979

The use of peroxidase-labelled Limulus polyphemus agglutinin for the histochemistry of sialic acid-containing glycoproteins in light microscopy.

The usefulness of a lectin, Limulus polyphemus agglutinin (LPA) has been tested in a series of mammalian tissues with sialic acid-containing glycoproteins. In nearly all the tissues employed, the positive peroxidase-labelled LPA diaminobenzidine (LPA-PO-DAB) reaction of various histological structures was markedly diminished in intensity or abolished, following digestion with neuraminidase. In the same tissues, sialic acid added with LPA-PO abolished the LPA-PO-DAB reaction or notably suppressed its intensity. In the majority of the tissues tested, the LPA-PO-DAB-Alcian Blue (AB) (pH 1.0 or 2.5) procedures appear to be useful dual staining methods which enable one to colour selectively sialic acid-containing and other acidic carbohydrates. In view of the endogenous peroxidase activity in particular histological structures, however, appropriate control staining procedures should be performed when the LPA-PO-DAB procedure is employed, either alone or in combination with AB procedures, to determine the histochemical properties of sialic acid-containing glycoproteins.

Animals↗