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Biomedical subjects

M Sugitani

Publications and source records attributed to M Sugitani.

At least 19 recordsLinked to original sources
PubMed1992

Sensitivity of serological assays to identify blood donors with hepatitis C viraemia.

Blood donors at high risk of hepatitis C virus (HCV) infection were tested for viraemia by the polymerase chain reaction (PCR). PCR results were accepted as positive only if reactive in 3 of 4 tests and if confirmed in an independent laboratory. The sera were also tested by 6 different assays to determine the ability of current serological assays to detect viraemic blood donors. Of 19 PCR-positive sera, only 13 (68%) were detected by the most sensitive of the serological assays. If these results are confirmed, automated PCR assays may be required for blood-donor screening to prevent transmission of HCV.

Blood Donors↗
PubMed1992

Actions of cholinergic agonists and antagonists on the efferent synapse in the frog sacculus.

Intracellular recordings were made from hair cells in the frog saccular epithelium isolated with its innervating nerves. Inhibitory post-synaptic potentials (IPSPs) were recorded from hair cells when the efferent fibers were activated by electrical stimulation. The effects of acetylcholine (ACh), cholinomimetics, and cholinergic antagonists on the efferent synapse were studied in a preparation where the IPSPs can be observed directly. ACh or carbachol (CCh) produced a transient membrane hyperpolarization with a decrease in input resistance followed by an abolition or reduction of the IPSP. In a low Ca2+ medium where efferent synaptic activity was abolished, ACh or CCh still induced hyperpolarization, though the response appeared to be smaller than that in normal medium. Neither nicotinic (dimethyl-4-phenyl-piperazinium (DMPP), phenyltrimethylammonium (PTMA) and nicotine) nor muscarinic (muscarine, methacholine, bethanechol and oxotremorine) agonists induced the membrane hyperpolarization, but the former drugs inhibited the IPSPs while the latter drugs did not. Both d-tubocurarine and atropine inhibited the IPSP, but the d-tubocurarine was more potent, causing inhibition even at a dose of 0.5 microM while 2 microM or more atropine was needed. The ACh- or CCh-induced hyperpolarization was inhibited completely by d-tubocurarine (5 microM), but only slightly by atropine (5 microM). These results may indicate that the IPSP and the effects of ACh or CCh are based on a direct interaction between ACh or CCh and ACh receptors on the hair cells.

Acetylcholine↗
PubMed1991

Genomic structure of the human prototype strain H of hepatitis C virus: comparison with American and Japanese isolates.

Genomic RNA from the human prototype strain H of the hepatitis C virus (HCV-H) has been molecularly cloned and sequenced. The HCV-H sequence reported consists of 9416 nucleotides including the 5' and 3' untranslated regions. HCV-H shows 96% amino acid identity with the American isolate HCV-1 but only 84.9% with the Japanese isolates HCV-J and HCV-BK. In addition to the hypervariable region (region V) previously identified in the putative E2 domain, three other variable domains were identified: region V1 (putative E1), region V2 (putative E2), and region V3 (putative NS5). These regions appear rather conserved (86-100%) among the American isolates (HCV-1 and HC-J1) or among various Japanese isolates (HCV-J, HCV-BK, HCV-JH, and HC-J4) but show striking heterogeneity when the two subgroups are compared (42-87.5% amino acid difference). A structural similarity between the 5'-terminal hairpin structure of HCV and of poliovirus was observed. This study further suggests the existence of at least two genomic subtypes of HCV and confirms a distant relationship between HCV and pestiviruses.

Amino Acid Sequence↗
PubMed1991

ONO-5046, a novel inhibitor of human neutrophil elastase.

ONO-5046, N-[2-[4-(2,2-Dimethylpropionyloxy)phenylsulfonylamino] aminoacetic acid, competitively inhibited human neutrophil elastase (IC50 = 0.044 microM, Ki = 0.2 microM). It also inhibited leukocyte elastase obtained from rabbit, rat, hamster and mouse. However, ONO-5046 did not inhibit trypsin, thrombin, plasmin, plasma kallikrein, pancreas kallikrein, chymotrypsin and cathepsin G even at 100 microM. In in vivo studies, ONO-5046 suppressed lung hemorrhage in hamster (ID50 = 82 micrograms/kg) by intratracheal administration and increase of skin capillary permeability in guinea pig (ID50 = 9.6 mg/kg) by intravenous administration, both of which were induced by human neutrophil elastase.

Animals↗
PubMed1991

Effects of activation of the divergent efferent fibers on the spontaneous activity of vestibular afferent fibers in the toad.

In anesthetized toads, spontaneous activities were recorded from single afferent fibers of three semicircular canals and three otolith organs. Since some efferent fibers ramify within the eighth nerve and innervate two or more vestibular organs, a single branchlet of the eighth nerve was disconnected from its end organ, and was electrically stimulated to activate divergent efferent collaterals leading to other vestibular organs. The stimulation elicited an inhibitory effect on spontaneous activities of about one third of the afferent population, and a facilitatory effect on those of another one third. The remaining one third was unaffected. Whether or not the inhibitory or facilitatory effect was observed in an individual unit seemed to be related to its pattern and its rate of spontaneous activity. Most of the units showing relatively high and regular spontaneous firing were insensitive to the electrical stimulation, and units with a low firing rate and an irregular pattern of activity tended to be affected by the electrical stimulation. The activation of divergent efferent fibers elicited both inhibition and facilitation on the spontaneous afferent activities in all vestibular nerve branchlets, except in the saccular branchlet, where only inhibition was elicited. Electrical stimulation of the central stump of the saccular nerve branchlet, however, could produce both inhibitory and facilitatory effects in other vestibular nerve branchlets.

Afferent Pathways↗
PubMed1991

Organ specificity of the antigens reacting with the 48-1 and S-1 antibodies in chimpanzees infected with hepatitis C virus.

48-1 and S-1 antibodies produced by lymphoblastoid cells transformed with Epstein-Barr virus were reported to be associated with infection by not only the hepatitis non-A, non-B (NANB) virus but also hepatitis delta virus. Appearance of the antigens reacting with these antibodies in the liver of chimpanzees was recently found to be a host response to alpha-interferon induced by infections of both viruses. To investigate organ specificity of these antigens, various organs obtained from chimpanzees with hepatitis C (NANB) were examined. In addition to the liver, the adrenals and spleen were found to be positive by immunofluorescence. The positive reactions of these three organs were also confirmed by radioimmunoassay. By electron microscopy, microtubular aggregates similar to those observed in the liver were detected in the adrenals, but not in the spleen. The results suggested that these antigens existed in the liver, adrenal, and probably spleen of chimpanzees infected with hepatitis C.

Adrenal Glands↗
PubMed1991

[A case of malignant hemangioendothelioma effectively treated with intra-arterial continuous infusion of interleukin-2].

An 82-year-old female presented with a tumor in the right-frontal region and was diagnosed as MHE, based on the clinical and pathological findings. Increased LAK (lymphokine-activated killer cell) activity was observed during treatment with intraarterial continuous infusion of rIL-2. In addition, the decrease in tumor size was started when LAK activity became high. Treatments for MHE and mechanism of these therapies were discussed using data from this case and other authors' reports.

Aged↗
PubMed1990

Further studies of 48-1 antigen in serial liver biopsies from chimpanzees infected with hepatitis delta virus.

The 48-1 antibody, initially reported to react specifically with non-A, non-B infected liver tissue, has been found to react also with liver specimens from chimpanzees infected with hepatitis delta virus (HDV). To clarify further the relation between HDV and appearance of the antigen reacting with the 48-1 antibody (48-1 Ag), immunoperoxidase studies were carried out on serial liver specimens from chimpanzees infected with HDV. Immunohistochemical and serological findings suggested that the appearance of 48-1 Ag paralleled that of HDV. Double immunoperoxidase staining revealed HDAg in the nucleus and 48-1 Ag in the cytoplasm of the same hepatocytes as well as in different hepatocytes separately. The course of appearance of microtubular aggregates paralleled that of 48-1 Ag. The present results suggested that expression of 48-1 Ag was related to infection with HDV, probably because expression of this antigen is induced from the host genome.

Animals↗
PubMed1990

Somatotopic organization and columnar structure of vibrissae representation in the rat ventrobasal complex.

The region of vibrissae representation in the ventrobasal complex (VB) of the rat was systematically mapped, based on receptive fields of many single neurons. Results showed that the ventralmost row of vibrissae projected to the rostral part of VB, that the dorsal-most row projected to the caudal part, and that the caudalmost vibrissae of each row projected to the most dorsolateral part of VB and more rostral vibrissae to the more ventromedial part. Further, it was revealed that the clusters of neurons receiving projections from any individual vibrissae formed corresponding columns extending from the anterodorsomedial to the posteroventrolateral direction, and that these columns piled up dorsoventrally and anteroposteriorly, with ventral ones shifted progressively medially. When cross sections of these columns were viewed on an oblique horizontal section of VB, a group of columns corresponding to each row lined up from the dorsolateral to the ventromedial direction with a rostral convexity, which means that the third or fourth vibrissa in each row projected most rostrally in that row. These results confirmed previous physiological mapping studies of vibrissal representation and are in good agreement with anatomical studies on barreloid structure in VB.

Animals↗
PubMed1990

Observations of the sensing and the tectorial membrane in bullfrog amphibian papilla: their possible functional roles.

Three dimensional reconstructions of the amphibian papilla were performed with light microscopic observations, mainly for the sensing membrane (SM). In horizontal sections of the papilla, the anteromedial end of the SM, which makes contact with the massive anterior portion of the tectorial membrane (TM), is several times thicker than the posterolateral end close to the column of the innervating nerves. This gradient of thickness is observed in all the sections from the dorsal portion attached to the TM to the ventral floor of the papilla. The SM connects to the TM in a topological manner; the anteromedial portion of the TM relates to the anterior end of the SM and the anterolateral and the middle portions of the TM correspond to the sites shifting posteriorly on the SM. The morphology of the SM and its manner of connection to the TM suggest that the SM plays important roles in the occurrence of frequency selectivity and of tonotopic organization of the amphibian papilla.

Animals↗
PubMed1987

Purification and properties of a pepstatin-insensitive carboxyl proteinase from a gram-negative bacterium.

A carboxyl proteinase was found in the culture filtrate of a Gram-negative bacterium. The optimum for the action of the purified enzyme was approx. pH 3 and its caseinolytic activity was not inhibited by carboxyl proteinase inhibitors, such as pepstatin, Streptomyces pepsin inhibitor and diazoacetyl-DL-norleucine methyl ester. 1,2-epoxy-3-(p-nitrophenoxy)propane modified the enzyme with concomitant loss of its enzyme activity. The enzymatic and physicochemical properties of the enzyme were compared with those of known pepstatin- and diazoacetyl-DL-norleucine methyl ester-insensitive carboxyl proteinases previously reported. To our knowledge, this is the first carboxyl proteinase isolated from bacteria.

Amino Acids↗
PubMed1987

Retinal inputs to the geniculate relay cells in the eastern chipmunk (Tamias sibiricus asiaticus): a comparison between color and non-color sensitive cells.

Single unit recordings were made from the relay cells of the lateral geniculate nucleus in the eastern chipmunk. Of 362 relay cells, 47 cells (13%) were classified as color sensitive and the rest as non-color sensitive cells. Non-color sensitive cells were further classified into 5 subclasses: off-phasic, on-phasic, on-off-phasic, on-tonic and uncommon types. Within the color sensitive cells there were 3 subclasses; blue excited and green inhibited (+B-G), blue inhibited and green excited (-B+G), and blue excited (+B) cells. Retinal afferents to color sensitive relay cells had the following characteristics: ganglion cells of their origin were distributed in the central high density areas of the retina and axonal conduction velocities were in the intermediate range, though they were somewhat slow in +B cells.

Animals↗
PubMed1986

Inhibition of hyperactive trigeminal subnucleus caudalis neurons after experimental trigeminal rhizotomy in response to thalamic sensory relay nucleus stimulation.

The effects of thalamic sensory relay nucleus stimulation on the single neuron activity and field potentials within the trigeminal subnucleus caudalis, which is trigeminal equivalent of the dorsal horn were investigated in intact cats as well as in cats subjected to retro-Gasserian rhizotomy 1-6 months before the experiments. Inhibition of nociceptive neural activity and a positive field potential were evoked by thalamic stimulation in the dorsal horn of the intact animals. A positive field potential followed double pulse stimulation with frequencies ranging up to approximately 50 Hz. The inhibitory periods ranged from 60 to 100 ms. Train pulse stimulation with frequencies ranging from 30 to 50 Hz produced long-lasting inhibition of nociceptive neural activity and a positive shift of the field potentials. Essentially identical inhibition of abnormal neural hyperactivity occurring in the rhizotomized dorsal horn was observed. The positive field potential corresponding to this inhibition also displayed characteristics similar to the field potential seen in the intact dorsal horn. These data indicate that the pathways involved in the inhibitory responses induced by thalamic sensory relay nucleus stimulation, unlike some other pain inhibitory systems, can exert their influence even to the dorsal horn which has undergone reorganization of neural circuits after rhizotomy.

Animals↗
PubMed1983

Transcutaneous recording of single neuron activity in the cerebral cortex of the monkey.

A new method is described for recording responses of single neurons in the monkey's cerebral cortex by passing a microelectrode directly through the overlying skin and dura. Previous to this recording a window had been cut in the calvarium, and the bone deficit repaired using a full-thickness skin graft. Stable unitary recordings have been made over a period of one year following craniotomy, the only skull attachment being a small stainless steel peg, on which the microdrive was mounted when required.

Animals↗
PubMed1982

Touching textured surfaces: cells in somatosensory cortex respond both to finger movement and to surface features.

Single neurons in Brodmann's areas 3b and 1 of the macaque postcentral gyrus discharge when the monkey rubs the contralateral finger pads across a textured surface. Both the finger movement and the spatial pattern of the surface determine this discharge in each cell. The spatial features of the surface are represented unambiguously only in the responses of populations of these neurons, and not in the responses of the constitutent cells.

Animals↗