Search PubMed⌕ Search

Biomedical subjects

J Kobayashi

Publications and source records attributed to J Kobayashi.

At least 451 records · Page 25Linked to original sources
PubMed1987

Wechsler Intelligence Scale profiles, the cholinergic system, and Alzheimer's disease.

Forty-one patients with putative Alzheimer's Disease (AD) were evaluated to determine the diagnostic utility of a profile of Wechsler Adult Intelligence Scale (WAIS) subtests which has been proposed by Fuld (1984) to identify cholinergic dysfunction. Only nine (21.9%) of these patients had positive Wechsler profiles. Half (n = 21) of the AD patients had been given the WAIS, and the other half (n = 20) the Wechsler Adult Intelligence Scale-Revised (WAIS-R). Positive profiles occurred more often in the AD subgroup given the WAIS-R, but this difference was not statistically significant. Specificity of the formula was evaluated using Wechsler results of 42 older normals and 30 patients who were being evaluated for dementia but who did not have AD. One of the 42 normals (2.4%) and five of the patient controls (16.7%) showed a positive Wechsler profile. Because of the Fuld formula's low sensitivity, a negative Wechsler profile cannot be used to help rule out AD. Although specificity of the formula is high, the diagnostic value of a positive Wechsler profile is modest even under the most favorable AD baserate conditions.

Aged↗
PubMed1987

Surgical management of children with temporal lobe epilepsy and mass lesions.

In a review of 48 children who underwent temporal lobectomy for temporal lobe epilepsy, 16 patients had mass lesions in the temporal lobe. These mass lesions consisted of 12 tumors, 3 vascular malformations, and 1 arachnoid cyst. In 9 of 10 patients where the hippocampus was present in the pathological specimen and was not involved by tumor, there was concomitant mesial temporal sclerosis. All 16 patients have been followed for more than 1 year. Nine are free of seizures, with 4 of these 9 still on medication. Seven patients have had a greater than 50% reduction in seizures.

Adolescent↗
PubMed1987

The Conus toxin geographutoxin IL distinguishes two functional sodium channel subtypes in rat muscle cells developing in vitro.

Sodium currents in cultured rat muscle cells converted to myoballs by treatment with colchicine were recorded using a giga-ohm seal voltage-clamp procedure in the whole-cell configuration. Geographutoxin II (GTX II), a novel polypeptide toxin from the piscivorous marine snail Conus geographus, reduces sodium currents in rat myoballs without marked alteration of the time course or voltage dependence of activation of the remaining current. Titration of the inhibition of sodium currents by GTX II showed that, in individual myoballs, a fraction of the sodium current averaging 49 +/- 9% (SEM) was inhibited by saturating (25 microM) concentrations of GTX II. The concentration-effect curve fit a noncooperative, 1:1 binding isotherm with a single KD for GTX II of 19 nM characteristic of inhibition of the TTX-sensitive sodium channels of adult rat muscle. Titration of the sodium current remaining in the presence of 2.5 microM GTX II with TTX gave complete inhibition. The dose-response curve fit a noncooperative, 1:1 binding isotherm with a single KD for TTX of 1.3 microM characteristic of TTX-insensitive sodium channels of embryonic muscle. The action of GTX II was not frequency dependent. The all-or-none inhibition of these 2 sodium channel subtypes by GTX II suggests substantial structural differences in the region of neurotoxin receptor site 1 on TTX-sensitive and -insensitive sodium channels and provides definitive evidence that these 2 sodium channel subtypes function in parallel in muscle cells developing in the absence of innervation.

Animals↗
PubMed1987

Actions of a polypeptide toxin from the marine snail Conus striatus on voltage-sensitive sodium channels.

The effects of a polypeptide toxin of 25,000 Da from the marine snail Conus striatus (CsTx) on sodium channels in mouse neuroblastoma cells and rat brain synaptosomes were studied. CsTx slowed sodium channel inactivation without altering the time course of activation of the channels. The voltage dependence of sodium channel inactivation was shifted to more negative membrane potentials and made less steep. Peak sodium currents were increased, and the voltage dependence of activation was shifted to more negative membrane potentials. The action of the toxin was voltage-dependent. Maximum toxin effects were observed at membrane potentials in the range of -100 to -60 mV. Apparent KD values were calculated assuming a one-to-one binding interaction. At more positive membrane potentials, the apparent KD for toxin action increased e-fold for each 19-mV depolarization. Apparent KD also increased at membrane potentials more negative than -100 mV. CsTx did not have significant effects on the binding of saxitoxin or Leiurus alpha-scorpion toxin to their receptor sites on sodium channels. CsTx enhanced the binding of batrachotoxinin A 20-alpha-benzoate to sodium channels in the same concentration range as its physiological effects. It is concluded that CsTx interacts with a new receptor site on the extracellular surface of the sodium channel at which specific effects on channel inactivation can occur.

Animals↗
PubMed1987

[Postoperative complications of abdominal aortic aneurysm--with special reference to postoperative renal hypofunction].

Effects of various factors before and during operation on postoperative renal hypofunction were studied in 34 preoperatively evaluated surgical cases of non-ruptured abdominal aneurysm. The cases were divided into two groups, with and without postoperative renal hypofunction. The two groups showed no differences with respect to age, sex, preoperative serum Crn or Ccr level, presence or absence of treatment with antihypertensives or diabetes mellitus, duration of intraoperative aortic clamping, or the volume of blood loss or transfusion. However, the group with postoperative renal hypofunction included many cases of preoperative hypertension. The incidence of postoperative renal hypofunction was high among cases which exhibited preoperative hypertension, but was low among those with preoperative normal blood pressure. Further, renal hypofunction occurred in few of the patients whose blood pressure had been controlled by the use of antihypertensives. The possibility was suggested that in palliative operations, preoperative blood pressure control, was useful for the prevention of postoperative renal hypofunction.

Aged↗
PubMed1987

[Follow-up study of children born following immunization therapy for habitual abortions].

A follow up study was carried out on 24 children whose mothers were treated with HLA immunization as therapy for habitual abortion. Among 350 couples who had experienced recurrent spontaneous abortions registered at this clinic, 117 women were immunized with their husbands' leucocytes. Seventy became pregnant and so far 24 have delivered. The sex ratio of the babies was 16 males to 8 females. The average body weight and height at birth were 3,294 +/- 88.5 g (mean +/- S.E., male) and 3,079 +/- 114.4 g (female), 50.0 +/- 0.38 cm (male) and 49.0 +/- 0.60 cm (female), respectively. Average gestational duration was 39.0 +/- 0.23 weeks and mean labor hours were 7.0 +/- 0.73 without any complication except two cesarean sections. Four out of 24 children were more than 2 years old and 12 were less than one year old. All of them were interviewed or investigated by questionnaires on the developments of body weight, height, sensory organs as well as dental development after birth. Emotional and other physical developments and history of disease after the neonatal period were also examined. Though basic immunological studies will be required in future, all investigations indicate that no abnormal sign normal developments were found in these children, indicating further application of this therapy for habitual abortion.

Abortion, Habitual↗
PubMed1986

Purealin, a novel stabilizer of smooth muscle myosin filaments that modulates ATPase activity of dephosphorylated myosin.

Effects of purealin isolated from a sea sponge, Psammaplysilla purea, on the enzymatic and physiochemical properties of chicken gizzard myosin were studied. At 0.15 M KCl, 40 microM purealin increased the Ca2+- and Mg2+-ATPase activity of dephosphorylated gizzard myosin to 2.5- and 3-fold, respectively, but decreased the K+-EDTA-ATPase activity of the myosin to 0.25-fold. In contrast, purealin had little effect on the ATPase activities of phosphorylated gizzard myosin. The ATP-induced decrease in light scattering of dephosphorylated gizzard myosin at 0.15 M KCl was lessened by 40 microM purealin. Electron microscopic observations indicated that thick filaments of dephosphorylated myosin were disassembled immediately by addition of 1 mM ATP at 0.15 M KCl, although they were preserved by purealin for a long time even after addition of ATP. Upon ultracentrifugation, dephosphorylated myosin sedimented as two components, the 10 S species and myosin filaments, in the solution containing 0.18 M KCl and 1 mM Mg X ATP in the presence of 60 microM purealin. These results suggest that purealin modulates the ATPase activities of dephosphorylated gizzard myosin by enhancing the stability of myosin filaments against the disassembling action of ATP.

Actin Cytoskeleton↗
PubMed1986

Specific inhibition of [3H] saxitoxin binding to skeletal muscle sodium channels by geographutoxin II, a polypeptide channel blocker.

Geographutoxin II (GTX II), a peptide toxin isolated from Conus geographus, inhibited [3H]saxitoxin binding to receptor sites associated with voltage-sensitive Na channels in rat skeletal muscle homogenates and rabbit T-tubular membranes with K0.5 values of 60 nM for homogenates and 35 nM for T-tubular membranes in close agreement with concentrations that block muscle contraction. Scatchard analysis of [3H]saxitoxin binding to T-tubular membranes gave values of KD = 9.3 nM and Bmax = 300 fmol/mg of protein and revealed a primarily competitive mode of inhibition of saxitoxin binding by GTX II. The calculated KD values for GTX II were 24 nM for T-tubules and 35 nM for homogenates, respectively. In rat brain synaptosomes, GTX II caused a similar inhibitory effect on [3H]saxitoxin binding at substantially higher concentrations (K0.5 = 2 microM). In contrast, binding of [3H]batrachotoxin A 20-alpha-benzoate and 125I-labeled scorpion toxin to receptor sites associated with Na channels in synaptosomes was not affected by GTX II at concentrations up to 10 microM. Furthermore, [3H]saxitoxin binding to membranes of rat superior cervical ganglion was only blocked 10% by GTX II at 10 microM. These results indicate that GTX II interacts competitively with saxitoxin in binding at neurotoxin receptor site 1 on the sodium channel in a highly tissue-specific manner. GTX II is the first polypeptide ligand for this receptor site and the first to discriminate between this site on nerve and adult muscle sodium channels.

Amino Acid Sequence↗
PubMed1986

Bromo-eudistomin D, a novel inducer of calcium release from fragmented sarcoplasmic reticulum that causes contractions of skinned muscle fibers.

Bromo-eudistomin D induced a contraction of the chemically skinned fibers from skeletal muscle at concentrations of 10 microM or more. This contractile response to bromo-eudistomin D was completely blocked by 10 mM procaine. The extravascular Ca2+ concentrations of the heavy fractions of the fragmented sarcoplasmic reticulum (HSR) were measured directly by a Ca2+ electrode to examine the effect of bromo-eudistomin D on the sarcoplasmic reticulum. After the HSR was loaded with Ca2+ by the ATP-dependent Ca2+ pump, the addition of 10 microM bromo-eudistomin D caused Ca2+ release that was followed by spontaneous Ca2+ reuptake. In the presence of 2 microM ruthenium red or 4 mM MgCl2, no Ca2+ release was induced by 20 microM bromo-eudistomin D. The rate of 45Ca2+ efflux from HSR, which had been passively preloaded with 45Ca2+, was accelerated 7 times by 10 microM bromo-eudistomin D. The concentration of bromo-eudistomin D for half-maximum effect on the apparent efflux rate was 1.5 microM, while that of caffeine was 0.6 mM. The bromo-eudistomin D-evoked efflux of 45Ca2+ was abolished by 2 microM ruthenium red or 0.5 mM MgCl2. Bromo-eudistomin D was found to be 400 times more potent than caffeine in its Ca2+-releasing action but was similar in its action in other respects. These results indicate that bromo-eudistomin D may induce Ca2+ release from the sarcoplasmic reticulum through physiologically relevant Ca2+ channels.

Adenosine Triphosphate↗
PubMed1986

Presynaptic inhibitory effect of geographutoxin II, a new peptide toxin from Conus geographus venom, in the guinea-pig vas deferens.

Geographutoxin II (GTX II), a new peptide toxin, isolated from Conus geographus venom, caused a dose-dependent inhibition of the contractile response of the guinea-pig vas deferens to transmural stimulation at concentrations of 3 X 10(-8) to 10(-6) M. The dose-response curves for noradrenaline, acetylcholine and KCl was not affected by GTX II (2 X 10(-7) to 10(-6) M). The release of noradrenaline induced by veratridine was strongly inhibited by GTX II. These results suggest that the GTX II-induced inhibition of the vas deferens may be a presynaptic effect causing a decrease of transmitter release.

Animals↗
PubMed1986

Preferential block of skeletal muscle sodium channels by geographutoxin II, a new peptide toxin from Conus geographus.

The effects of geographutoxin II (GTX II), a novel polypeptide toxin isolated from the marine snail Conus geographus, on nerves and muscles were studied by current clamp and voltage clamp techniques. GTX II (5 X 10(-7) M) abolished the action potential of the guinea pig skeletal muscle without change in the resting potential. However, action potentials of the crayfish giant axon, mouse neuroblastoma N1E-115 cell and guinea pig cardiac muscle were not affected by GTX II even at concentrations higher than 1 X 10(-6) M. In the voltage clamped bullfrog skeletal muscle fiber, sodium currents were almost completely blocked by GTX II (1 X 10(-6) M), and slowly recovered after washout. The time course of sodium currents was not appreciably altered by GTX II. These results suggest that GTX II selectively blocks skeletal muscle sodium channels in much the same way as tetrodotoxin.

Action Potentials↗