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S Kanba

Publications and source records attributed to S Kanba.

90 records · Page 5Linked to original sources
PubMed1989

Automated determination of drugs in serum by column-switching high-performance liquid chromatography. IV. Separation of tricyclic and tetracyclic antidepressants and their metabolites.

We describe automated column-switching high-performance liquid chromatography for determining nine tricyclic and tetracyclic antidepressants (TCAs) and their metabolites in human serum. TSKgel ODS-80TM and TSKprecolumn PW (Tosoh Co., Tokyo) are used in the analytical column and the precolumn, respectively. A 200-microL serum sample is directly injected onto the precolumn. After washing the serum proteins from the precolumn with potassium phosphate buffer, the precolumn connection is switched to introduce the retained substances onto the analytical column. The drugs are then eluted within 30 min with an acetonitrile/potassium phosphate buffer mixture containing sodium 1-heptanesulfonate. The analytical recoveries (95-104%), reproducibilities (within-run CV less than 3%), and detection limits (10 micrograms/L) indicate that this HPLC system is suited for therapeutic drug monitoring. Correlations were good between the TCA concentrations in serum and administered dose (r = 0.713, n = 41), and between 10-hydroxynortriptyline and nortriptyline in serum (r = 0.691, n = 24).

Amitriptyline↗
PubMed1988

[3H]neurotensin(8-13) binds in human brain to the same sites as does [3H]neurotensin but with higher affinity.

The binding of [3H]neurotensin(8-13) to membranes from human frontal cortex at 0 degree C was time dependent, specific, saturable, and reversible. Saturation isotherms provided an equilibrium dissociation constant (KD) of 0.52 nM, and the maximal number of binding sites (Bmax) was 3.5 pmol/g original wet weight of tissue. Scatchard analysis yielded a straight line, and the Hill coefficient was equal to 1, a result indicating that [3H]neurotensin(8-13) bound to single, noncoopertive sites. The KD values of several analogs of neurotensin determined in competition with [3H]neurotensin(8-13) were similar to those previously determined in competition with [3H]neurotensin. The regional distribution of binding sites for [3H]neurotensin(8-13) was also similar to that for [3H]neurotensin. These results suggest that [3H]neurotensin(8-13) binds to the same sites as [3H]neurotensin and that [3H]neurotensin(8-13) has a higher affinity than [3H]neurotensin for these sites in human brain.

Aged↗
PubMed1987

Selective enlargement of the third ventricle found in chronic schizophrenia.

Selective enlargement of the third ventricle was observed when the area and the VBR (ventricle-brain ratio) were measured in 37 chronic schizophrenics (DSM-III criteria) as compared with 37 controls. However, the width or the width to IS (maximum inner skull width) ratio was not significantly different between the two groups. There was no correlation between any measure of the third ventricle and any of the clinical variables. Five patients had VBRs of the third ventricle that were larger than the mean + 2 SD of the control, but there was no significant difference between these five schizophrenics and the others in any of the clinical variables.

Adult↗
PubMed1986

Lithium ions have a potent and selective inhibitory effect on cyclic GMP formation stimulated by neurotensin, angiotensin II and bradykinin.

The effect of lithium ion (Li+) on receptor-mediated synthesis of cyclic GMP, a putative second messenger, was examined using intact murine neuroblastoma cells (clone N1E-115). Lithium chloride potently inhibited cyclic GMP formation stimulated by the neuropeptides, neurotensin, angiotensin II and bradykinin in an identical concentration-dependent (IC50 s of around 12 mM), saturable and reversible manner. In the presence of veratridine, an alkaloid which by stimulating sodium channels can increase Li+ entry into the cells, Li+ inhibited neurotensin-stimulated cyclic GMP formation more potently (IC50 = 7 mM). No effect of Li+ was observed on phosphodiesterase (EC 3.1.4.17) activity. These results suggest that Li+ may interfere with the function of these receptors through its inhibitory effect at a common site in the pathway of receptor-mediated cyclic GMP formation.

Angiotensin II↗
PubMed1986

Binding of [3H]neurotensin in human brain: properties and distribution.

The binding of [3H]neurotensin to membranes from human brain at 0 degrees C was specific, saturable, and reversible. In the frontal cortex, the equilibrium dissociation constant (KD) for [3H]neurotensin determined from the ratio of rate constants (k-1/k1), saturation isotherms, and inhibition binding experiments was 0.80, 2.0, and 2.0 nM, respectively, and the maximum number of binding sites (Bmax) from the saturation isotherms and the competitive binding experiments was 2.4 and 2.2 pmol/g of tissue, respectively. Hill coefficients for binding were equal to 1, indicating the presence of single, noncooperative binding sites. Inhibition of specific binding of [3H]-neurotensin by several analogs of neurotensin showed that [Gln4]neurotensin and neurotensin(8-13) had the highest affinities for these binding sites in human frontal cortex, with each analog being approximately 13-fold more potent than neurotensin. In addition, these data showed that the carboxy-terminal portion of neurotensin played an important part in the binding of this neuropeptide in human brain, a result described for other species. Regional distribution of binding sites was different from that reported for animal brains. Of the 33 different regions investigated, the uncus and substantia nigra showed the highest specific binding of [3H]neurotensin, whereas such areas as the pineal body, medulla, and corpus callosum had few binding sites.

Aged↗
PubMed1985

Lithium ions inhibit function of low- but not high-affinity muscarinic receptors of murine neuroblastoma cells (clone N1E-115).

Murine neuroblastoma cells (clone N1E-115) possess both high- and low-affinity muscarinic receptors. The low-affinity muscarinic receptor, when stimulated, initiates the formation of cyclic GMP by activating the enzyme guanylate cyclase; whereas stimulation of the high-affinity receptor inhibits prostaglanding E1-mediated cyclic AMP formation by inhibiting the enzyme adenylate cyclase. We have reported that lithium ion (Li+) inhibits cyclic GMP formation mediated by the muscarinic receptor agonist, carbachol, in a concentration-dependent manner and that neither ammonium nor sodium ions have such an effect. We extended this study to show that Li+ was an apparently noncompetitive inhibitor of the low-affinity muscarinic receptor with an IC50(+/- SEM) = 13.6 +/- 0.8 mM. In addition, Li+ with a similar IC50 inhibited the cyclic GMP response in intact cells to sodium azide, which is thought to stimulate guanylate cyclase directly. Moreover, though Li+ was found to have a slight inhibitory effect on prostaglandin E1-stimulated cyclic AMP formation (15% inhibition at 10 mM), it had no effect on the function of the high-affinity muscarinic receptor in intact murine neuroblastoma cells.

Alprostadil↗
PubMed1985

Normal ventricles in chronic schizophrenics.

The computed tomography (CT) scans of 46 chronic schizophrenic patients and 46 controls were studied using ventricular-brain ratio. Ewans' index, and cella media index. None of the indices used revealed significant differences between the patient and the control groups.

Adult↗
PubMed1984

Histamine H1 receptors in human brain labelled with [3H]doxepin.

Doxepin, a tricyclic antidepressant, is one of the most potent histamine H1 antagonists. Therefore, the binding of [3H]doxepin to human brain membranes was examined. Scatchard analysis revealed two distinct binding sites. The high-affinity binding site with a dissociation constant (KD +/- S.E.M.) of 3.1 +/- 0.3 X 10(-10) M was pharmacologically identified as histamine H1 receptors. Dissociation curves at low concentrations of [3H]doxepin were biphasic, suggesting several possibilities about the interaction between [3H]doxepin and histamine H1 receptors. Tetracyclic antidepressants, mianserin and maprotiline, were very potent, with KDs of 3.6 +/- 0.7 X 10(-10) M and 7.9 +/- 0.5 X 10(-10) M, respectively. Mequitazine, a new antihistamine with a weak sedative effect, had a KD of 5.8 +/- 0.8 X 10(-9), making it ten times as potent as the classic antihistamine diphenhydramine. The highest binding of [3H]doxepin to histamine H1 receptors was found in cerebral neocortex and the limbic system. The distribution of histamine H1 receptors in human central nervous system did not correlate with the previously reported distributions in rat brain and guinea pig brain determined by [3H]doxepin binding.

Adult↗
PubMed1984

Depression and ventricular enlargement.

Compared with controls, 46 depressed patients showed increased ventricular-brain ratio (VBR). Patients with poor outcome, single episode, onset at 50 years or over, or without melancholia were found to have greater VBR than controls.

Adult↗
PubMed1983

Antidepressants are weak competitive antagonists of histamine H2 receptors in dissociated brain tissue.

Guinea pig hippocampus dissociated by mechanical means into uniform clumps of cells (approximately 100 micron in diameter) contains histamine receptors (H1 and H2) which mediate the formation of cyclic AMP. In this preparation, antidepressants are very potent antagonists of histamine H1 receptors but are weak antagonists of histamine H2 receptors. The latter result is contrary to data derived by others using homogenates of the guinea pig hippocampus and seems to dispel the idea that antidepressants derive their efficacy by blocking histamine H2 receptors in brain.

Animals↗