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Biomedical subjects

T Tabata

Publications and source records attributed to T Tabata.

At least 19 recordsLinked to original sources
PubMed1992

Determination of manidipine enantiomers in human serum using chiral chromatography and column-switching liquid chromatography.

A stereoselective and highly sensitive method using chiral chromatography and successive column-switching liquid chromatography is described for the determination of manidipine enantiomers in human serum. A human serum sample obtained after ingestion of manidipine was extracted twice with a mixture of n-hexane-diethyl ether under alkaline conditions. The enantiomers in the extract were separated on a chiral stationary phase column (Chiralcel OJ), and the effluents containing the respective enantiomers were collected. Each fraction was then analysed by column-switching liquid chromatography. The proposed stereoselective method offered high sensitivity: detection limits for both isomers were 0.2 ng/ml in human serum, both at a signal-to-noise ratio of 3. The method is suitable for the pharmacokinetic studies of manidipine enantiomers.

Administration, Oral↗
PubMed1992

Bulbar reticular neurons relaying somatosensory information to the mesencephalic parabrachial area of the cat.

Somatosensory neurons projecting to the mesencephalic parabrachial area (MPBA), which is located ventral to the inferior colliculus and dorsal to the brachium conjunctivum, were recorded from the bulbar reticular formation of adult cats anesthetized with alpha-chloralose. The majority (41 of 50 neurons) were nociceptive-specific neurons responding only to noxious mechanical and/or thermal stimuli to the skin, cornea and/or oral mucosa. The size of their receptive fields was smaller than that of the intrinsic MPBA-neurons, but larger than that of the trigeminal sensory nucleus neurons. Twenty-three neurons received input from the tooth pulp nerve and 10 of 32 neurons tested responded to electrical stimulation of the vagal nerve. These results indicate that these bulbar reticular neurons receive noxious inputs and transmit them to the MPBA, which also receives input from spinal or trigeminal sensory nucleus neurons projecting directly to the MPBA.

Animals↗
PubMed1992

Different origin of leiomyoblastoma by immunohistochemical study.

Leiomyoblastoma has been regarded as a neoplasm of smooth muscle origin. With recent progress in immunohistostaining techniques, many clinicopathological discrepancies have been pointed out about the origin of leiomyoblastoma. It has been claimed that gastrointestinal non-epithelial tumors should be regarded as stromal tumors in order to study their origin. In the present study, we performed various forms of immunohistostaining in seven cases of leiomyoblastoma to determine their origin. One case expressed desmine and muscle specific actin and was considered to be derived from smooth muscle. Four neoplasms expressed X-100 protein (two cases were also NSE positive) and were thought to be derived from the nerve. Two cases were of unknown derivation. These results suggest that the cells of leiomyoblastoma may arise from a primitive to totipotential cell of neural lineages that may anomalously express smooth muscle filaments.

Actins↗
PubMed1992

Effect of tooth temperature on activities of slowly adapting periodontal mechanoreceptors in the cat.

The mass response of a nerve bundle and the unitary discharges from a functional single nerve fibre evoked by mechanical stimulation of the upper canine tooth were recorded from the superior alveolar nerves of 10 anaesthetized cats. When the pulpal cavity of the mechanically stimulated tooth was perfused with a 0.9% NaCl solution at temperatures from 10 to 45 degrees C, the mass response of the nerve bundle to that stimulation increased linearly with the rise in perfusate temperature (hereafter, tooth temperature). In the unitary discharge recordings, the activities of 30 (88%) of 34 slowly adapting periodontal mechanosensitive units were modulated by tooth temperature. The optimal temperature, at which the periodontal mechanoreceptor shows extreme excitation by mechanical tooth stimulation, was distributed widely from 10 to < or = 45 degrees C with a peak at < or = 45 degrees C. A shift in tooth temperature away from the optimal value caused a decrease in, or sometimes the disappearance of, the response. This decrease was the result of the decrease in the excitability of the periodontal mechanoreceptor; i.e. an increase in threshold stimulus intensity and a shortening of the adaptation time to sustained pressure applied to the tooth.

Adaptation, Physiological↗
PubMed1992

Dendritic regrowth of retinal ganglion cells in adult rats.

IN adult rat retinal ganglion cells, we investigated how their dendrites are maintained during axonal regeneration induced by a peripheral nerve (PN) graft. Intracellular Lucifer Yellow injection revealed that rapid dendritic retraction occurred immediately after axotomy and grafting. However, dendrites that probably sprouted after axotomy were often found in the regenerating ganglion cells, and their dendritic field tended to recover in area by 3 months after grafting. Although such dendrites were also found in an axotomized cell receiving no PN graft, they are much more frequently observed in the regenerating cells. Therefore, a PN graft can facilitate the rat ganglion cells to regrow their dendrites.

Animals↗
PubMed1992

One-step typing of Epstein-Barr virus by polymerase chain reaction: predominance of type 1 virus in Japan.

The prevalence of two types of Epstein-Barr virus (EBV) in Japan was studied by using the polymerase chain reaction (PCR). The U2 region encoding EBV nuclear antigen 2 (EBNA-2) was chosen as the target of amplification. Consensus primers were synthesized from sequences common to the two types but encompassing a large stretch of deletion in the sequence of type 1 EBV. The primers were capable of amplifying both types at the same time but allowed differentiation of each type by the size of the amplification products. Thus we could carry out detection and typing of EBV in a one-step PCR. EBV was detected in mouth washings of 21 (23%) of 91 seropositive healthy adults. Twenty samples (22%) contained type 1 and only one (1%) type 2. Seventy-nine patients suffering from various types of tonsillitis were also studied. EBV was detected in mouth washings of 37 patients (47%). Thirty-four (43%) contained type 1 and three (4%) type 2. Double infection was not seen in either healthy donors or patients. These results indicate that type 1 EBV is highly dominant and the type 2 variant is quite rare in Japan.

Base Sequence↗
PubMed1992

The Drosophila hedgehog gene is expressed specifically in posterior compartment cells and is a target of engrailed regulation.

cDNAs were isolated that represent transcripts of the Drosophila segment polarity gene, hedgehog (hh). Sequence analysis reveals a motif characteristic of a transmembrane domain, suggesting that the hh protein is membrane-associated. hh expression in epidermal cells is confined to the posterior compartments and coincides precisely with that of engrailed (en). Despite the similar patterns of expression in the cellular blastoderm, hh expression is independent of en, but hh expression becomes sensitive to and dependent on en during the extended germ band stage. The ectopic expression of hh that is normally induced in patched (ptc) mutant embryos does not appear in ptc en double mutants. We discuss these findings in terms of the relationship between en and hh, and the role of the hh function.

Amino Acid Sequence↗
PubMed1992

Impaired long-term T cell immunity to Epstein-Barr virus in patients with nasopharyngeal carcinoma.

The long-term T cell immunity to Epstein-Barr virus (EBV) is considered to play an important role in suppressing proliferation of EBV-infected B cells and outgrowth of EBV-associated tumors. It can be manifested and quantified by the EBV-induced focus regression assay. In the present study, we examined the strength of T cell immunity to EBV in patients with nasopharyngeal carcinoma (NPC) and other cancers originating from the head and neck region. In contrast to patients with other types of cancers, including EBV-negative NPC, patients with EBV-positive NPC were found to have a profound impairment in the long-term T cell immunity to EBV.

Adolescent↗
PubMed1992

Plasma 1,5-anhydroglucitol concentration in patients with end-stage renal disease with and without diabetes mellitus.

The plasma concentration of 1,5-anhydroglucitol, a new clinical marker of glycemic control in diabetic patients, was evaluated as a marker of glycemia in 83 diabetic and nondiabetic patients with end-stage renal disease. Plasma 1,5-anhydroglucitol concentration decreased and correlated inversely with blood glucose, hemoglobin A1c, or fructosamine in 48 diabetic patients with normal renal function. In 13 nondiabetic patients with end-stage renal disease not on dialysis, plasma 1,5-anhydroglucitol concentrations were lower than in 23 healthy subjects (6.22 +/- 2.10 vs. 24.20 +/- 7.50 micrograms/ml, respectively). The plasma concentration of 1,5-anhydroglucitol concentration in nondiabetic patients with end-stage renal disease was inversely correlated to the urinary N-acetyl-beta-D-glucosaminidase activity (r = -0.634) but not to blood glucose, hemoglobin A1c, or fructosamine. Renal tubular damage may contribute to the low plasma concentration of 1,5-anhydroglucitol in this group. The plasma concentrations of this polyol decreased in both diabetic (4.63 +/- 1.08 micrograms/ml) and nondiabetic patients on hemodialysis (4.71 +/- 0.87 micrograms/ml). In these two groups, there was no correlation between plasma concentration of this polyol and blood glucose, hemoglobin A1c, or fructosamine. The plasma concentration of 1,5-anhydroglucitol decreased after a single hemodialysis session. The results showed that impaired renal function and removal of 1,5-anhydroglucitol by dialysis may contribute to its decreased concentration in patients with end-stage renal disease, but that glycemic control does not. Therefore, we should consider renal function when we use plasma 1,5-anhydroglucitol concentration as a marker of glycemic control in diabetic patients.

Adult↗
PubMed1992

Interleukin-1 of cholesteatomatous keratinocytes.

Interleukin-1 (IL-1) has been thought to be one of the essential cytokines mainly produced by macrophages. It has recently been reported that epidermal keratinocytes produce IL-1, and attention is being paid to local immune reactions mediated with this cytokine. Interleukin-1 not only activates lymphocytes, but also acts as an osteoclast-activating factor. In this study, we used immunohistochemistry and immunoblotting on cholesteatomatous epithelium with anti-IL-1 alpha antibody and anti-IL-1 beta antibody. Next, the relationship of cholesteatomatous debris to the production of IL-1 by keratinocytes was evaluated. Highly concentrated IL-1 alpha was found in the cholesteatomatous epithelium, especially in the basal cell layer. The intensity of IL-1 beta staining was weaker than that of IL-1 alpha staining. In the immunoblotting study, the 31 kd band, an intracellular immature precursor molecule, was identified. The production of IL-1 alpha from keratinocytes was augmented to a greater degree by cholesteatomatous debris than by lipopolysaccharide or keratin. The keratinocytes did not produce IL-1 beta. These findings suggest that IL-1 alpha is derived from cholesteatomatous keratinocytes. Interleukin-1, mainly IL-1 alpha, from the stimulated cholesteatomatous keratinocytes may be an important factor in the markedly increased bone resorption observed in cholesteatoma.

Blotting, Western↗
PubMed1992

Evidence for the presence of differently glycosylated forms of prorenin in the plasma of anephric man.

Previously, we unexpectedly observed that plasma inactive renin (trypsin-activatable renin) in bilaterally nephrectomized rats is not prorenin. To determine whether plasma inactive renin in anephric man is prorenin, we examined the immunological and biochemical properties of plasma inactive renin from five anephric patients. There were significant concentrations of inactive renin (5.33 +/- 2.08 ng/L.s) in plasma of anephric patients, while active renin was negligible (0.06 +/- 0.01 ng/L.s). The inactive renin from anephric patients could be immunoprecipitated 97 +/- 1% by specific antiserum against the prosegment portion of prorenin. Specific antimature renin serum completely inhibited the angiotensin-I-generating activity of inactive renin induced by trypsin treatment. The molecular mass of inactive renin from anephric patients (49.0 +/- 0 kDa), estimated by gel permeation high performance liquid chromatography, was similar to that of normal human plasma prorenin (48.2 +/- 0.8 kDa). These results indicate that plasma inactive renin in anephric man is prorenin, findings different from our previous observations obtained in anephric rats. Concanavalin-A chromatography separated inactive renin from anephric patients into three forms, including the column-unbound form, the loosely bound form, and the tightly bound form. Thus, in anephric man, differently glycosylated multiple forms of prorenin are released into the circulation from an extrarenal organ(s).

Adult↗
PubMed1992

Properties of an albumin inhibiting lysosomal acid cholesteryl ester hydrolase in rat liver.

Lysosomal acid cholesteryl ester hydrolase (acid CEH, EC. 1.1.1.13) activity was inhibited by addition of an increasing amount of d = 1.21 bottom fraction from rat serum (Lipids in press). To clarify the mechanism of this inhibition, rat native and modified albumin were added to the assay mixture and their effects on acid CEH activity were examined. The inhibitory effect on acid CEH activity was dependent on the concentration of rat albumin. Albumin of various mammalian species, including human, bovine and rabbit, also inhibited acid CEH activity. This inhibitory activity was markedly increased by heat treatment, the effect increasing in parallel with the prolongation of the treatment. Moreover, this albumin-dependent inhibition of acid CEH activity was also markedly increased by methylation of albumin. In contrast, the inhibition of acid CEH activity by modified albumins, such as acetyl albumin, succinyl albumin and glycine methyl ester albumin, was much lower than that of albumin, and no stimulatory effect of heat treatment on the albumins was observed. The heat-treated albumin-dependent inhibition of acid CEH activity was not abolished in the presence of sodium deoxycholate. The values of Vmax obtained were similar with or without heat-treated albumin. These results suggest that the inhibitory effects of heat-treated albumin may be due to an intrinsic and characteristic property of the lipid/water interface, and that the stimulatory effects of heat treatment on albumin-dependent inhibition may be due to heat-induced changes in the affinity and conformation of albumin.

Albumins↗
PubMed1992

Response field of cat trigeminal sensory complex neurons responsive to mechanical stimulation of the canine tooth.

Response fields of periodontal mechanoreceptive (PM) neurons in the cat's trigeminal sensory complex were examined while mechanical stimulation was applied to the canine tooth in 12 directions on the horizontal plane. Almost all the slowly adapting PM neurons were directionally selective to stimulation, and their response fields had response angles greater than 180 degrees, i.e. broad type.

Afferent Pathways↗