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Biomedical subjects

K Kasamo

Publications and source records attributed to K Kasamo.

At least 37 records · Page 2Linked to original sources
PubMed1994

Effects of zopiclone, triazolam, and nitrazepam on standing steadiness.

We examined the effects of the nonbenzodiazepine hypnotic zopiclone and the benzodiazepine hypnotics triazolam and nitrazepam on standing steadiness. Eight healthy volunteers received placebo, zopiclone (7.5 mg), triazolam (0.25 mg), and nitrazepam (5 mg) in a random-order, double-blind crossover design. Postural sway was assessed before and 1 and 2 h after drug administration using a stabilometer connected to a microcomputer. Triazolam significantly impaired standing steadiness. Zopiclone also impaired standing steadiness but the degree of impairment seemed to be less marked. Nitrazepam 5 mg had no significant effects on postural sway. Triazolam 0.25 mg, zopiclone 7.5 mg, and nitrazepam 5 mg, which are reported to be equipotent to each other as hypnotics, are not equipotent with respect to their effects on postural sway.

Adult↗
PubMed1993

Epileptic seizure of El mouse initiates at the parietal cortex: depth EEG observation in freely moving condition using buffer amplifier.

The initiation site of seizure discharges and the relationship between behavioral manifestations and electroencephalography were investigated in the El mouse, a hereditary epilepsy model. The chronic depth electrodes were implanted stereotaxically into the frontal cortex, parietal cortex, temporal cortex, hippocampus, striatum, amygdaloid complex, non-specific nuclei of thalamus and substantia nigra. Electrical activities were recorded in freely moving condition with use of the buffer amplifier devised in the laboratory and behaviors were monitored simultaneously. Seizure spike discharges started in the parietal cortex and spread out into other brain areas. When the hippocampus was involved, the tonic convulsion occurred behaviorally. The paper describes the first direct evidence of the initiation and propagation of seizure discharges in the brain of El mouse.

Amplifiers, Electronic↗
PubMed1993

Chronological changes of MRI findings on striatal damage after acute cyanide intoxication: pathogenesis of the damage and its selectivity, and prevention for neurological sequelae: a case report.

A 31-year-old male technician in an electroplating factory, who had been suffering from the temporal lobe epilepsy for 24 years and from hypertension for 2 years, took an unknown amount of potassium cyanide apparently over the lethal dose, in an attempt to commit suicide. He was treated successfully and survived without any neurological sequelae. The electroencephalograms and the nature of the seizures were not different before and after the poisoning. The T2-weighted magnetic resonance images at 9 and 51 days after the poisoning showed bilateral elevation of signals in the caudate nuclei and the putamina. At the 143th and 286th days. T2-weighted high-resonance areas were restricted to the lateral portion of the putamina. The T1-weighted images at the 51st day showed abnormal signal elevations in both putamina, while those of 9th, 143th and 286th days were mainly normal. Selective vulnerability of the putamen and the caudate nucleus may be due to their specific structural properties of high oxygen and glucose utilization, and enzyme distribution. Both chronological changes of striatal damage and the absence of neurological sequelae in this patient suggest the possibility that anti-epileptics and a calcium antagonist played a neuroprotective role in the acute cyanide intoxication.

Adult↗
PubMed1992

Crystallization and preliminary X-ray diffraction studies of aspartic proteinase from Irpex lacteus.

Crystals of ILAP (Irpex lacteus aspartic proteinase) have been obtained by the hanging drop method using ammonium sulfate as a precipitant. The crystals are monoclinic, space group P2(1) with cell dimensions a = 54.5 A, b = 79.6 A, c = 37.5 A, beta = 96.8 degrees. The crystals are quite stable to X-rays and diffract beyond 1.9 A resolution. There is one molecule in the asymmetric unit.

Animals↗
PubMed1992

Binding of 7-Chloro-4-nitrobenzo-2-oxa-1,3-diazole to an Essential Cysteine Residue(s) in the Tonoplast H-ATPase from Mung Bean (Vigna radiata L.) Hypocotyls.

Vacuolar-type H(+)-ATPase was solubilized from tonoplasts of mung bean (Vigna radiata L.) and purified on a Mono Q anion-exchange column by fast protein liquid chromatography. The purified enzyme was inactivated by the reactive adenine analog, 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole (NBD-Cl). This inactivation was reversed by addition of dithiothreitol (DTT). Inactivation by NBD-Cl was prevented by Mg-ADP, a competitive inhibitor of ATPase. [(14)C]NBD-Cl predominantly modified the 68-kilodalton subunit and the degree of (14)C incorporation was decreased in the presence of Mg-ADP or upon subsequent addition of DTT. The loss of activity followed pseudo first-order kinetics with respect to NBD-Cl concentration, and double log plots of pseudo first-order rate constants versus reagent concentration yielded a straight line with a slope of 0.957. The NBD-modified/inactivated enzyme showed an absorbance maximum at 418 nanometers and a fluorescence emission peak at 515 nanometers. The absorption and fluorescence emission spectra of the NBD-modified enzyme were essentially the same as those of the model compound, N-acetyl-S-NBD cysteine. Absorbance by the modified enzyme at 418 nanometers disappeared upon addition of DTT, which coincided with the restoration of ATPase activity and the decrease in bound [(14)C]NBD-Cl. These findings show that NBD-Cl modifies an essential cysteine residue(s) at or near the catalytic site in the 68-kilodalton subunit of tonoplast H(+)-ATPase and that the modification closely correlates with the loss of ATPase activity.

Journal Article↗
PubMed1992

Effects of prodigiosin 25-C on cultured cell lines: its similarity to monovalent polyether ionophores and vacuolar type H(+)-ATPase inhibitors.

Prodigiosin 25-C inhibited the proliferation of various cultured cell lines more strongly when concanavalin A (Con A) was added to the cultures. The increase in sensitivity was most evident in T lymphoma YAC-1 cells. The combination of prodigiosin 25-C and Con A induced characteristic morphological changes in these cells. In the presence of Con A, monovalent polyether ionophores and vacuolar type H(+)-ATPase inhibitors induced effects similar to those of prodigiosin 25-C on YAC-1 cells. Prodigiosin 25-C had neither K+ionophore activity nor inhibitory effect on vacuolar type H(+)-ATPase. A Golgi mannosidase II inhibitor, swainsonine, inhibited the proliferation of YAC-1 cells only when Con A was added. Prodigiosin 25-C and swainsonine increased Con A binding receptors on the surface of YAC-1 cells. These results suggest that prodigiosin 25-C affects the intracellular transport and/or processing of glycoproteins.

Biological Transport↗
PubMed1990

Mechanism for the Activation of Plasma Membrane H-ATPase from Rice (Oryza sativa L.) Culture Cells by Molecular Species of a Phospholipid.

The activation of H(+)-ATPase solubilized from plasma membrane of rice (Oryza sativa L. var Nipponbare) culture cells was examined by the exogenous addition of various phospholipids, free fatty acids, glycerides, polar head groups of phospholipids and molecular species of phosphatidylcholine (PC). H(+)-ATPase activity appeared to be stimulated by phospholipids in the following order: asolectin > phosphatidylserine > PC > lysophosphatidylcholine > phosphatidylglycerol, and maximal ATPase activation was noted at around 0.05 to 0.03% (w/v) of asolectin or molecular species of PC. Polar head groups such as glycerol, inositol, and serine only slightly activated ATPase activity or not at all, while ethanolamine and choline had no effect. Activation was dependent on the degree of saturation or unsaturation of the fatty acyl chain and its length. The activity decreased with increase in the length of fatty acyl chain from dimyristoryl(14:0)-PC to distearoyl(18:0)-PC and the degree of unsaturation from dioleoyl(18:1)-PC to dilinolenoyl(18:3)-PC. Maximum activation was observed when PC possessing 1-myristoyl(14:0)-2-oleoyl(18:1) or 1-oleoyl-2-myristoyl was added to the reaction mixture. These data show that the activation of plasma membrane H(+)-ATPase by PC depends on a combination of saturated (myristic acid 14:0, palmitic acid 16:0, and stearic acid 18:0) and unsaturated (oleic acid 18:1, linoleic acid 18:2, and arachidonic acid 20:4) fatty acids at the sn-1 and sn-2 positions of the triglycerides.

Journal Article↗
PubMed1988

Essential Arginyl Residues in the Plasma Membrane H-ATPase from Vigna radiata L. (Mung Bean) Roots.

Proton-translocating ATPase (H(+)-ATPase) was purified from mung bean (Vigna radiata L.) roots. Treatment of this enzyme with the arginine-specific reagent 2,3-butanedione in the presence of borate at 37 degrees C (pH 7.0), caused a marked decrease in its activity. Under this condition, half-maximal inhibition was brought about by 20 millimolar 2,3-butanedione at 12 minutes. MgATP and MgADP, the physiological substrate and competitive inhibitor of the ATPase, respectively, provided partial protection against inactivation. Loss of activity followed pseudo-first order kinetics with respect to 2,3-butanedione concentration, and double log plots of pseudo-first order rate constants versus reagent concentration gave a curve with a slope of 0.984. Thus, inactivation may possibly result from reaction of one arginine residue at each active site of the enzyme. The results obtained from the present study indicate that at least one arginyl residue performs an essential function in the plasma membrane H(+)-ATPase, probably at the catalytic site.

Journal Article↗
PubMed1987

The Role of Phospholipids in Plasma Membrane ATPase Activity in Vigna radiata L. (Mung Bean) Roots and Hypocotyls.

Root and hypocotyl plasma membrane H(+)-ATPases were partially purified from deoxycholate-solubilized fractions of microsomes in mung bean (Vigna radiata L.) plants in the presence of glycerol. Certain properties of the ATPases and the manner in which phospholipids affect their activity were compared. Root ATPase was similar to hypocotyl ATPase with respect to substrate specificity, salt stimulation, pH dependence, K(m) for ATP.Mg(2+) and inhibitor sensitivity, except for inhibition by vanadate. Both purified ATPases required phospholipids for their activation. Optimum concentrations of exogenously added phospholipid mixture (asolectin) to hypocotyl and root ATPase mixture were 0.03% and 1.0%, respectively. Root ATPase activation did not decrease if more than 1.0% asolectin was added. Qualitatively, phosphatidylserine and phosphatidylcholine brought about greater ATPase activation than other phospholipids. The hypocotyl ATPase was activated by phosphatidylinositol, phosphatidylserine and phosphatidylglycerol to a greater extent than the root ATPase. Root, but not hypocotyl ATPase, was slightly inhibited by the addition of phosphatidylinositol, phosphatidylethanolamine, and phosphatidic acid. The hypocotyl plasma membrane contained phosphatidylinositol + phosphatidylserine, phosphatidylglycerol and phosphatidic acid, and unsaturated fatty acids in greater abundance than the root plasma membrane. The differential activation of the plasma membrane ATPases may arise from these differences.

Journal Article↗