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Biomedical subjects

Y Katayama

Publications and source records attributed to Y Katayama.

At least 739 records · Page 41Linked to original sources
PubMed1985

Occurrence of calcitonin gene-related peptide in the chicken amacrine cells.

The distribution of calcitonin gene-related peptide (CGRP)-like immunoreactivity (CGRPI) in the chicken retina was investigated by means of immunohistochemistry. CGRPI was localized in the stratified amacrine cells. The terminal branching pattern of these cells was different between the central and peripheral retinal regions. Flat-mount preparations revealed these CGRPI cells to be evenly distributed in the entire retina with surprisingly rich arborization.

Animals↗
PubMed1985

Slow postsynaptic potentials in neurones of submucous plexus of guinea-pig caecum and their mimicry by noradrenaline and various peptides.

Intracellular recordings of membrane potential and membrane currents were made from neurones in the submucous plexus of the guinea-pig caecum in vitro. Fast and slow excitatory postsynaptic potentials and slow inhibitory postsynaptic potentials were recorded from the majority of neurones following focal stimulation of presynaptic fibres in the plexus. The slow inhibitory postsynaptic potential was associated with an increase in membrane conductance and reversed its polarity at -90 mV; it was reversibly blocked by yohimbine. The slow excitatory postsynaptic potential and its underlying current was associated with a decrease in membrane conductance. Two kinds of voltage-dependence both of the slow excitatory postsynaptic potential and current were observed; in 80% of cells, the excitatory postsynaptic potential and current became smaller with membrane hyperpolarization and reversed polarity at -90 mV (reversing type) but in 20% of cells both the excitatory postsynaptic potential and current simply disappeared when the membrane potential reached -70 mV (non-reversing type). The effects of acetylcholine, adenosine 5'-triphosphate, bombesin, 5-hydroxytryptamine, neurotensin, noradrenaline, substance P and vasoactive intestinal polypeptide were examined. The only substance which mimicked the slow inhibitory postsynaptic potential was noradrenaline; brief applications of noradrenaline caused hyperpolarizations which had the same time-course, reversal potential and sensitivity to yohimbine as the slow inhibitory postsynaptic potential. The non-reversing type of slow excitatory postsynaptic potential was mimicked only by adenosine 5'-triphosphate. The reversing type of slow excitatory postsynaptic potential was mimicked by bombesin, neurotensin, substance P and vasoactive intestinal polypeptide. 5-Hydroxytryptamine and vasoactive intestinal polypeptide (in some neurones) caused a depolarization with an increase in membrane conductance. All three synaptic potentials were reversibly depressed by superfusion of noradrenaline but noradrenaline did not affect the potential changes evoked by brief application of exogenous acetylcholine or substance P. It is concluded that, in guinea-pig submucous plexus neurones, the slow inhibitory postsynaptic potential is mediated by noradrenaline and results from a potassium conductance increase.(ABSTRACT TRUNCATED AT 400 WORDS)

Adenosine Triphosphate↗
PubMed1985

Dissociation of subjective pain report and pain-related late positive components of cerebral evoked potentials in subjects with brain lesions.

Several studies have described a correlation between subjective pain report and late positive components (LPCs) of cerebral evoked potentials occurring with latencies ranging from 150 to 400 msec after the onset of painful stimuli. We report here human subjects with brain lesions who revealed very small LPCs in response to painful electrical skin stimuli applied to the finger pads even though they described strong subjective pain for the same stimuli. A decrease in pain-related LPCs was observed regardless of whether the stimuli were applied to the finger pads ipsilateral or contralateral to the brain lesions. Based on this observation, it is suggested that the pain-related LPCs may reflect neural processes which are presumably associated with information processing of painful input rather than neural processes of pain perception per se.

Adult↗
PubMed1985

Thalamic negativity associated with the endogenous late positive component of cerebral evoked potentials (P300): recordings using discriminative aversive conditioning in humans and cats.

Electrical potentials within the thalamus associated with the endogenous late positive component (LPC or P300) of cerebral evoked potentials were investigated in humans and cats. Essentially identical discrimination tasks using classical aversive conditioning were employed for recording LPC in both species. In humans, a negative wave within the same latency range as that of LPC was noted, with dependency on stimulus-relevance, at all thalamic and mesencephalic recording sites which included the nucl. centrum medianum, nucl. parafascicularis, and periaqueductal gray. Similar negative waves were also observed over wide areas of the thalamus of cats including specific as well as non-specific thalamic nuclei. The negative waves seen in the thalamus were generally higher in amplitude than those seen in the white matter and became unclear when the electrodes penetrated the ventral border of the thalamus.

Animals↗
PubMed1985

Cronkhite-Canada syndrome associated with a rectal cancer and adenomatous changes in colonic polyps.

A 52-year-old man with the clinical features of Cronkhite-Canada syndrome developed rectal cancer. Radiologic and endoscopic examinations revealed gastrointestinal polyposis. Histologic examination of the biopsied polyps showed cystic dilatation of glands with an inflammatory stroma. A later biopsy from a rectal polyp proved to be an adenocarcinoma. The totally resected colon and upper rectum had an ulcerated rectal cancer and numerous polyps; most of the polyps showed histological changes typical of the syndrome. Only three polyps had adenomatous changes at their surfaces. Adenomatous and carcinomatous changes of epithelia can occur in non-neoplastic polyposis of Cronkhite-Canada syndrome from which presumably a carcinoma can develop, as in the present case.

Adenocarcinoma↗
PubMed1985

Effect of the endogenous analgesic dipeptide, kyotorphin, on transmitter release in sympathetic ganglia.

The effects of kyotorphin and the synthetic analogue, D-kyotorphin, on cholinergic fast excitatory postsynaptic potentials (fast-e.p.s.ps) were studied using intracellular recordings from bullfrog sympathetic ganglion cells. Kyotorphin and D-kyotorphin (1-100 microM) increased the amplitude and the mean quantal content of the fast-e.p.s.p. without changing the mean quantal size in a low Ca2+/high Mg2+ medium. Kyotorphin and D-kyotorphin (1-100 microM) did not change the resting membrane potential, input membrane resistance, the amplitude and duration of action potentials and the sensitivity to the transmitter, acetylcholine (ACh), of the ganglion cells. The facilitatory effect of D-kyotorphin on the fast-e.p.s.p. was reversibly inhibited by naloxone (10 microM). These results indicate that kyotorphin may increase transmitter release from preganglionic nerve terminals. The possible mechanisms underlying this action of kyotorphin are discussed.

Acetylcholine↗
PubMed1985

Deafferentation pain and stimulation of the thalamic sensory relay nucleus: clinical and experimental study.

This report summarizes our clinical experience in which the effects of both thalamic sensory relay nucleus (TSRN) and periaqueductal gray (PAG) stimulation were tested in the same series of patients with various forms of pain. The clinical data indicated that neurogenic pain due to deafferentation at the level of the peripheral nerves or the spinal cord was often controlled by TSRN stimulation but not by PAG stimulation. We also review the results of our experimental investigations in cats which were undertaken in an attempt to clarify the neurophysiologic basis of such differential clinical effects of TSRN and PAG stimulation. It appeared that abnormal hyperactivity within the trigeminal medullary dorsal horn following retrogasserian rhizotomy was far more frequently inhibited by TSRN stimulation than by PAG stimulation.

Afferent Pathways↗
PubMed1985

Pain relief following stimulation of the pontomesencephalic parabrachial region in humans: brain sites for nonopiate-mediated pain control.

It has been demonstrated that stimulation of the pontomesencephalic parabrachial region (PBR) by microinjection of cholinergic drugs or electricity in the cat produces potent pain suppression which is not antagonized by the opiate antagonist, naloxone. We report the application of electrical PBR stimulation in 2 patients whose pain was resistant to conventional methods of treatment including morphine administration. Intermittent use of low-frequency PBR stimulation was found to relieve pain in these patients. The present results appear to suggest that PBR stimulation, unlike periaqueductal gray stimulation, may be useful for the control of morphine-resistant pain in humans.

Brain Mapping↗
PubMed1985

Pain suppression induced by electrical stimulation of the pontine parabrachial region. Experimental study in cats.

Cholinergic stimulation by microinjection of drugs into a region surrounding the lateral half of the brachium conjunctivum selectively produces a non-opiate form of pain suppression in the cat. Since this suppression does not appear to involve neural systems that mediate morphine analgesia, stimulation of this pontine parabrachial region (PBR) may potentially be useful for control of human pain resistant or tolerant to opiate treatment. Because of technical problems associated with the clinical use of microinjection techniques in the human brain, we investigated whether electrical stimulation of the PBR can produce pain suppression similar to pain suppression produced by cholinergic stimulation. The results indicate that electrical stimulation of an area generally corresponding to the PBR can also produce significant pain suppression. Although the PBR is a region previously implicated in a variety of behavioral and physiological functions, the stimulation parameters that produce maximal pain suppressive effects (namely, low frequency and relatively low intensity) were not associated with noticeable changes in such functions. The prolonged onset period and persistent analgesic effects outlasting the period of stimulation--features that have been reported in other studies of brain stimulation-produced pain suppression--were observed in the present study. The time course of pain suppression did not parallel other changes in behavioral and physiological functions. These data indicate that electrical stimulation of the PBR, under certain stimulation parameters, can activate previously demonstrated neural populations related to pain suppression without affecting neural elements contributing to other behavioral or physiological functions. The authors suggest that electrical stimulation of the PBR may be clinically applicable for treatment of human pain.

Acetylcholine↗
PubMed1985

Concussive head injury producing suppression of sensory transmission within the lumbar spinal cord in cats.

This study examines the effects of concussive levels of a fluid-percussion head injury on sensory transmission within the lumbar spinal cord of the cat. Primary afferent depolarization (PAD) was suppressed for 2 to 5 minutes following injury, as assessed by dorsal root potentials and augmentation of antidromic dorsal root potentials, both evoked by stimulation of adjacent dorsal roots. Polysynaptic reflex discharges in ventral root potentials evoked by dorsal root stimulation were also profoundly suppressed during this same period, even when spontaneous and monosynaptic reflex discharges were facilitated. Changes in PAD produced by injury were abolished by spinal cord transection, but were not affected by midpontine transection. These findings suggest that concussive head injury can produce suppression of segmental sensory transmission by neurally mediated processes involving the bulbar brain stem. Recordings of dorsal root resting potentials, antidromic dorsal root potentials, and reductions of antidromic dorsal root potentials induced by tetanic root stimulation indicated that depressed segmental sensory function produced by injury was due to suppression of postsynaptic interneuronal transmission rather than to excitability changes in primary afferent fibers. Somatosensory cortical potentials evoked by dorsal root stimulation were profoundly depressed at the same time as segmental sensory transmission was suppressed, suggesting that suppressed segmental sensory transmission may also contribute to suppression of ascending sensory transmission. It is hypothesized that transmission failure of interneuronal systems in the initial period following insult may be a general response occurring in wide areas of the central nervous system, and not restricted to areas to which mechanical stress is directly applied. This response pattern may result from indiscriminate activation of interconnected excitatory and inhibitory elements of interneuronal systems.

Animals↗
PubMed1985

Serum cholesterol levels and the ratio of polyunsaturated to saturated fatty acid as an indicator of lipid metabolism in rat liver.

Tne dietary effects of phytosterol and polyunsaturated fat (PUFA-fat) on the cholesterol and fatty acids levels in serum and liver of female rats were studied, with the following results. (1) Addition of 1% cholesterol with 0.25% cholic acid to a 10% butter diet increased cholesterol levels and decreased the ratio of polyunsaturated fatty acid (PUFA) to saturated fatty acid (SFA) in the serum and liver. These changes diminished upon additions of phytosterol and PUFA-fat (cod liver oil) to the 10% butter-cholesterol diet. (2) While the cholesterol-rich diet increased the fatty acid content of the liver, addition of phytosterol to the butter-cholesterol diet depressed this increase. On the other hand, addition of PUFA-fat to the butter-cholesterol diet caused an increase of total fatty acid in the liver. (3) A negative relationship was found between the cholesterol level and the ratio of PUFA to SFA in serum (r = -0.810) and also in liver (r = -0.548). There were significant positive correlations between the values for the serum and liver cholesterol levels (r = 0.720) and also between the respective values in the ratios of PUFA to SFA (r = 0.521). These results indicate that dietary phytosterol and PUFA-fat modulate the levels of cholesterol in proportion to the increase in the ratio of PUFA to SFA in both serum and liver with the cholesterol diet, and show that the changes in the values for the serum reflected in changes in the liver.

Animals↗
PubMed1985

[Effects of S-adenosyl-L-methionine on experimental cerebral ischemia].

Effects of S-adenosyl-L-methionine (SAMe) on experimental cerebral ischemia were investigated using two different ischemic models. Cerebral energy metabolites (ATP, lactate, c-AMP) and brain water content were measured. It is reported that SAMe accelerates synthesis of phosphatidyl choline and increases erythrocyte membrane fluidity. Complete ischemia was produced by heart excision using wistar kyoto rats. SAMe (100 mg/kg, I.P.) was administered twice at one hour and immediately before inducing ischemia. The brain of rats were irradiated by microwave to stop the enzyme activity exactly 60 seconds after inducing ischemia and brain energy metabolites were measured. Recirculation model was produced by one hour recirculation following two hours ischemia induced by clipping of bilateral common carotid arteries using stroke-prone spontaneously hypertensive rats. SAMe (100 mg/kg, I.V.) was administered twice one hour after clipping and ten minutes after recirculation. The brain metabolites and water content were measured one hour after recirculation. In the complete ischemia, ATP and c-AMP levels were statistically high in the SAMe treated group compared to the untreated group (vehicle). But there was no statistical difference in lactate between the treated group and the untreated group. In the recirculation model, lactate elevation was suppressed in the SAMe treated group compared to the vehicle group with statistical difference, but there was no difference in ATP and c-AMP. Also, there was no difference in water content between the treated and the untreated group. SAMe protected energy failure in ischemia and accelerated recovery from ischemia. It is indicated that this agent is beneficial for treatment of cerebral ischemia in the acute stage.

Acute Disease↗
PubMed1985

Membranous glomerulonephritis associated with hepatitis B antigen in children: a comparison with idiopathic membranous glomerulonephritis.

The laboratory and pathological findings are reported for 16 children with membranous glomerulonephritis (MGN) associated with hepatitis B virus (HBV) infection and compared with those of 12 children with idiopathic MGN. Serum hepatitis B surface antigen (HBsAg) was found in all children with HBV associated MGN and serum hepatitis B e antigen (HBeAg) in 11 of the 15 examined. Five patients with HBV associated MGN, but none with idiopathic MGN, showed reduced serum C3 values. Otherwise there was no difference in laboratory findings. HBeAg was detected in the glomeruli of all 7 patients with HBV-associated MGN examined but HBsAg was not detected. Of the 14 children with HBV-associated MGN examined by electron microscopy, all but one showed small mesangial deposits and 4 subendothelial deposits, whereas of 9 with idiopathic MGN only 2 showed mesangial deposits and none subendothelial deposits. Thus most of the children with HBV-associated MGN are characterized by some laboratory and pathological features of membrano proliferative glomerulonephritis in addition to those of idiopathic MGN. These observations are consistent with HBV inducing a spectrum of glomerulopathy from typical MGN to typical membranoproliferative glomerulonephritis.

Adolescent↗