Tadao Hoshino

Application of photodiode array ultraviolet detector to unresolved peak analysis

Abstract Poorly resolved chromatographic peaks have been mathematically resolved to give all component peaks of a multicomponent sample, using a newly developed 32-channel multiwavelength spectrophotometric UV detector and its data processor. In order to isolate poorly resolved peaks quantitatively, three-dimensional chromatographic data were stored on a floppy disk and computed by a data processor. A mathematical method of simultaneous multicomponent analysis for UV spectra was applied to all the points along the time axis. The results obtained have been compared with those by conventional perpendicular-dropping and tangential-skimming methods for known amounts of components. Recoveries obtained by the new method were 100.7 and 101.1%, while those by the conventional methods wer 89.9 and 110.1%, and 126.8 and 26.4%, respectively, by perpendicular dropping and tangential skimming. The detection of a hidden component in a chromatogram and determination of its UV spectrum was also investigated.

POSSIBLE NORADRENERGIC DYSFUNCTION IN SCHIZOPHRENIA

In spite of extensive studies over the last 2 decades to find direct evidence in support of the dopamine hypothesis of schizophrenia, no undisputed experimental data has been obtained. In contrast, estimation of noradrenalin (another major catecholamine) and its metabolites in postmortem brain and in the cerebrospinal fluid appears to be producing consistent results. To understand the meaning of this change for the pathogenesis of the illness, we have carried out animal experiments in which reproducibility of schizophrenic signs and symptoms by noradrenergic dysfunction, and treatability of the disorder by modulation of noradrenergic activity were studied. First, psychophysiological signs in skin conductance responsiveness (nonhabituating or nonresponding change) and smooth pursuit eye movement (spiky or stepwise pursuit) could be reproduced by enhancing or suppressing central noradrenergic activity. Behavioral abnormalities resembling schizophrenic symptoms are known to be reproducible by over- or underactivity of the system (overarousal or underarousal syndrome). Secondly, the action of various drugs capable of modulating schizophrenic symptoms was analyzed in relation to noradrenergic activity. Haloperidol, in particular, had a potent suppressing effect on skin conductance activity (spontaneous fluctuation rate and habituation rate) when administered chronically, suggesting its inhibitory action on noradrenergic activity.

Functional influence of the central noradrenergic system on the skin conductance activity in rats

Pharmacological studies on neuroleptics and amphetamine strongly suggest that some dysfunction of the central catecholamine system may play a key role in the pathogenesis of schizophrenia. Our previous studies have demonstrated that intraventricular administration of 6-hydroxydopamine, a selective neurotoxin of the catecholamine neuron, can reproduce schizophrenia-like abnormalities in the skin conductance activity. In the present experiments, effects of pharmacological modulation of the central noradrenergic activity were studied in rats. Stimulation of the central noradrenergic activity by yohimbine (0.6 mg/kg, i.m.) slowed down the habituation of the skin conductance response (SCR) and increase the spontaneous fluctuation of the skin conductance (SF), while inhibition of the activity by clonidine (0.06 mg/kg, i.m.) accelerated or obliterated the SCR and decreased the SF frequency. If the functional significance of the central noradrenergic system lies in vigilance control, the present results are consistent with classical theory in psychophysiology: the habituation rate of SCR and the frequency of SF are correlated well with each other and both indices reflect arousal level. The disorder of the system should produce not only these psychophysiological abnormalities but also psychological disturbances; i.e., overarousal and underarousal syndromes. Therefore, the dysfunction of the noradrenergic system might constitute an essential aspect of schizophrenic disorder.

Effects of acute methamphetamine administration on spacing in paired rats: Investigation with an automated video-analysis method

1. Effects of acute methamphetamine administration on spacing and locomotor activity were investigated in paired rats using a computer-assisted automated video-analysis method. 2. Both 0.1 and 1 mg/kg of methamphetamine significantly increased the spacing in comparison with saline. This alteration in behavioral interaction by methamphetamine may serve as one of the animal models of social withdrawal. 3. A significant increase in locomotor activity was found after 1 mg/kg of methamphetamine. 0.1 mg/kg dosage was accompanied by a locomotor change of a lesser degree and shorter duration. 4. The difference with respect to the dose dependency and the time course indicates that the changes in these two behavioral indices by methamphetamine may have different underlying mechanisms.

Effects of detergent on the elution profiles of latex beads in sedimentation field-flow fractionation

Abstract An unexpected prolongation of retention was observed in an experiment on the retention behaviour of latex beads in constant field sedimentation field-flow fractionation (SFFF). The prolongation depended on the type and concentration of detergent used in the solvent stream, and also on the size of the solute particulates. These facts suggested that retention in SFFF strongly depends on the state of the interface between the column surface and the solvent stream. On application of Sterns electrical double-layer diffusion model to the state of the surface border of the column wall, the prolongation of retention behaviour was well explained. As a result, an additional modification to the SFFF retention equation can be made, and the empirical equation, 1/ R = Cd + Dd + E, is proposed, where R is the retention ratio, C , D and E are functional parameters determined by the type and concentration of detergents used in the solvent stream and d p is the particle diameter.

Skin conductance activity after intraventricular administration of 6-hydroxydopa in rats

Absence of skin conductance response (SCR) and failure of its habituation are psychophysiological signs observed in most schizophrenics. In the present experiments, skin conductance activity was studied in rats before and after intraventricular administration of 6-hydroxydopa (6-OHdopa), a neurotoxin that selectively destroys noradrenaline nerve terminals and induces denervation supersensitivity at the synapse. All intact rats studied (n = 32) showed SCR and its habituation to repeated auditory stimuli (500 Hz, 90 dB, 1 sec, 20 times). They also showed some spontaneous fluctuation (SF) of the skin conductance. In the early stage following the 6-OHdopa (100 micrograms) administration (n = 16), it was noted that the SCR disappeared and the SF were markedly reduced in frequency (p less than 0.001). From the third day to the fourth week after this treatment, there was some recovery of the SF rate, and the SCR tended to reappear with a marked slowing down of its habituation. Eight weeks after the treatment, the majority (11/16) of the 6-OHdopa rats showed habituation failure of the SCR (p less than 0.005); vehicle-treated rats (n = 16) did not show these alterations. Estimation of catecholamine concentration after the experiment confirmed the selective depletion of brain noradrenaline. These results suggest that destruction of the noradrenergic fibers after the 6-OHdopa treatment and denervation supersensitivity which developed later are the cause of the nonresponding and nonhabituating changes of SCR, respectively.

A rapid-cross-sectioning and freeze-clamping device for the beating canine heart

A new sampling method of cross-sectioning the canine heart in situ was developed. A mechanical device, driven by spring power, enabled cross-sectioning of a short-axis plane of the beating canine heart (4 mm thick) with high speed rotating blades, at a pre-determined phase of the cardiac cycle, and instantaneous freeze-clamping (2.4 mm thick) with pre-cooled aluminum blocks, all within 120 ms. By this method, the anatomical structures of the sample were well preserved. Transmural metabolism and flow distribution were instantaneously fixed and high resolution of the two-dimensional redox state was obtained by application of NADH fluorescence photography. Micro-samplings from the desired portion of the cross-sectional slice were possible at -190 degrees C. NADH fluorescence of the samples did not increase from the surface to 1.2 mm in depth, confirming that there was no ischemic artifact. With the present technique, a heart sample in which transmural metabolism, and the redox state, are fixed and visualized is attainable, thus providing a new tool for the study of myocardial ischemia.

Quantitative deconvolution of heavily fused chromatographic peaks of biological components using a multiwavelength uv detector

Quantitative deconvolution of a chromatographic peak with extremely low UV absorption (less than 0.005 A.U.) is demonstrated for the analysis of an anaesthetic (ketamine) in rabbit serum. One ketamine metabolite, nor-ketamine, was deconvoluted from a completely fused peak in the three-dimensional chromatogram by using a highly sensitive multi-wavelength UV detector. After injection of ketamine, the nor-ketamine level in the serum increased to 3 micrograms/ml, calculated as ketamine, in 120 min.

Application of high-performance liquid chromatography in establishing an accurate index of blood glucose control.

A chromatographic method utilizing a carboxymethylated poly(vinyl alcohol) resin for a more accurate determination of stable haemoglobin A1c (St-A1c) has been developed. The complete separation between St-A1c, labile HbA1c (L-A1c) and HbF was achieved by gradient elution with sodium chloride in phosphate buffer. This high resolution permits accurate quantitation of St-A1c, even in the presence of high levels of HbF or L-A1c. In 142 subjects with normal fasting plasma glucose and normal response to a 75-g oral glucose tolerance test, the reference interval of St-A1c was 2.80-3.98%.

New High-Speed Fully Automated Guanidino Compound Analyzer

The introduction of dialysis has made rapid progress in the field of research and clinical treatment of renal failure, and has contributed very much to physiological elucidation of uremia. In uremia, concentrations of serum creatinine, BUN (Blood urea nitrogen), uric acid and guanidino compounds increase, and abnormalities of water, electrolytes, and acid-base equilibrium are seen. In addition, there are still many unknown substances and unknown factors, which play an important role in this disease. These substances are generally called uremic toxins. It is essential to investigate uremic toxins for the elucidation of uremia and the establishment of proper dialysis. Many compounds from low molecular weight to middle molecular weight have been investigated as suspicious candidates for the uremic toxin. Among these compounds, guanidines such as methylguanidine (MG), guanidinosuccinic acid (GSA) and guanidine (G) have been suggested. These guanidino compounds are also considered as causes for abnormalities in brain metabolism.