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Biomedical subjects

T Yabe

Publications and source records attributed to T Yabe.

At least 145 records · Page 8Linked to original sources
PubMed1991

Effects of serotonin, GABA and glycine on the activity of pause neurons during vestibular nystagmus in the cat.

Pause neurons (PNs), found in the pontine raphe nuclei, are important in the regulation of fast eye movements. The present study focuses on transmitters regulating the activity of the PNs. Extracellular spikes of single PNs and ocular motor nerve discharges were simultaneously recorded during horizontal vestibular nystagmus in the alert cat. Several transmitter candidates were iontophoretically applied, while methysergide, a serotonin antagonist, was administered both systemically and topically. The following data supported the conclusion that PNs are probably under the control of two different types of neurons, and the firing of PNs may be caused partly by GABAergic, but not by glycinergic neurons: 1) serotonin markedly decreased the spontaneous firing of the PNs; 2) methysergide abolished the inhibitory effect of serotonin on the PN firing; however, a pause pattern was maintained under this condition; 3) GABA moderately suppressed the firing but only in 25% of PNs; and 4) glycine hardly changed the PN firing in any case examined.

Animals↗
PubMed1991

Neurotransmitters regulating vestibular commissural inhibition in the cat.

The present study focuses on the transmitters which control the vestibular neural activity and, in particular, those which regulate commissural inhibition. Extracellular spike recordings were taken from single vestibular neurons of decerebrate cats. Seven-barreled electrodes were used. The barrels, except for the central one, were filled with several transmitter candidates and their specific inhibitors. After isolation of a type I neuron, the chemicals were iontophoretically applied to examine their effects on the activity of the neuron. The results were as follows: i) GABA and glycine markedly decreased spontaneous firing of the neurons, while serotonin did not change the activity. ii) Bicuculline abolished the inhibitory effects of GABA on the neurons. iii) Strychnine also abolished the effects of glycine, iv) Commissural inhibition caused by electrical stimulation of the contralateral labyrinth was not abolished by the application of strychnine but was abolished by bicuculline. We concluded that 1) vestibular type 1 neurons are controlled by GABAergic and glycinergic neurons, and that 2) the commissural inhibition is activated by the GABAA receptor, but not by the GABAB receptor.

Animals↗
PubMed1991

[The effect of blood pressure control on the progression of chronic glomerulonephritis associated with hypertension].

It is well known that hypertension (HT) frequently develops in patients with chronic glomerulonephritis (CGN) and that HT contributes to progression of CGN. So, proper antihypertensive therapy is required in hypertensive patients with CGN. However, there is so far no consensus of optimal blood pressure (BP) level to maintain the renal function in these patients. In order to evaluate the BP control level in the patients with renal insufficiency, we investigated the transition of BP and renal function in 22 CGN patients with HT (average age 36.5 +/- 9.9 years at the first medical examination, 15 male, 7 female, total 179.5 patient-years), who receive antihypertensive therapy for more than 5 years as outpatients at the second department of internal medicine of Tohoku University Hospital between 1975 and 1990. Renal biopsy had been performed in all these patients for CGN diagnosis. During this period 7 patients came to receive hemodialysis therapy from 5 to 10 (average 7.6 +/- 2.1) years after the first medical examination. In one of these 7 patients, the rate of decline in renal function accelerated after child-birth, and one after two years interruption of treatment. The other 13 patients are currently receiving drug treatments at our hospital. As a result, in CGN patients there was an optimal mean BP (MBP) control range, that is, when MBP was controlled in this range, the rate of decline in renal function became slow, but when MBP deviated from this range it became fast (p less than 0.01). Moreover, this range changed according to the serum creatinine (SCr) concentration level.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

A cDNA clone expressed in natural killer and T cells that likely encodes a secreted protein.

We have isolated a series of cross-hybridizing cDNA clones, as a group designated as NKG5, from a human natural killer (NK) cell clone cDNA library. These clones show a high degree of homology with a previously described gene, 519, which was thought to be T cell specific. A comparison of the full-length cDNA sequence of NKG5 and the published sequence of 519 shows that NKG5 lacks a 242-base segment that is found in 519 and that this deletion leads to the use of a different putative translational start codon. Unlike 519, the predicted NKG5 polypeptide has an NH2-terminal sequence that is strongly hydrophobic, characteristic of a signal peptide, and lacks any additional hydrophobic regions in the remainder of the peptide, suggesting that NKG5 encodes a secreted protein. Both NKG5 and 519 are expressed in NK and T cells but not in a variety of other hematopoietic cell lines. NKG5 is an abundant transcript and its level of expression is about 40 times that of 519 in NK and T cells. Southern blot and DNA sequence analyses suggest that NKG5 and 519 mRNAs are transcripts from a single gene that has allelic polymorphism.

Amino Acid Sequence↗
PubMed1990

Prevalence of spotted fever group rickettsia antibody in Apodemus speciosus captured in an endemic focus in Miyazaki Prefecture, Japan.

Fourteen of Apodemus speciosus (large Japanese field mouse) were captured near the place where one of the patients with spotted fever group rickettsiosis had been infected, in Takaoka town, Miyazaki Prefecture. In the town, four human cases were reported. All of the mice had antibodies against Rickettsia japonica and R. montana. The incidence of the antibody was significantly higher in Apodemus mice in the area than in those from nonendemic area.

Animals↗
PubMed1990

Isolation and characterization of NK cell or NK/T cell-specific cDNA clones.

Natural killer (NK) cells are cytotoxic lymphocytes that share numerous cell surface antigens and functional components with T cells. However, in comparison with our knowledge of T cells, little is known about the molecular mechanisms of NK cell activation and function. The following study was initiated as an effort to obtain further information about similarities and differences between NK and T cells at the level of gene expression and also to identify NK-specific cDNA clones for future functional studies of the corresponding gene products. The study used cDNA libraries prepared from an NK clone and from an Epstein-Barr virus transformed B cell lymphoblastoid cell line (LCL). We employed a combination of differential and subtractive hybridization methodologies, which can successfully identify cell-specific cDNA clones representing medium to high abundance transcripts, to identify genes that are expressed in NK cells but not in the LCL. We were particularly interested to ascertain to what extent genes isolated in this manner would be expressed only in NK cells as opposed to being expressed in NK and T cells. Twelve different cross-hybridizing groups were identified that were not expressed in the LCL, and these groups were further characterized: (1) they were used to probe Northern blots prepared from a panel of cells including NK cells, T cells, and B cells: (2) changes in the steady-state level of message following T cell growth factor (TCGF)-induced activation of an NK cell clone were examined for selected isolates; and (3) a partial DNA sequence was determined for each cross-hybridizing group. The DNA sequences of seven groups were identical to previously reported sequences. One group was highly homologous with but not identical to what has been reported as a T cell specific gene, named 519. The DNA sequences of four groups showed no significant homology with the sequences in the GenBank and EMBL databases. The mRNA expression of the newly-identified groups demonstrated several different regulation patterns with respect to cell distribution and level of expression in response to TCGF-activation. Expression of the twelve different genes was examined in three populations of NK cells all of which were CD3- and possessed NK activity. Although these cells differentially expressed the prototype NK markers CD16 and CD56 (the cells were CD16+, CD56-, CD16-, CD56+ and CD16+, CD56+), the expression of all groups of cDNA clones was comparable in the three different types of NK cells despite the phenotypic differences.(ABSTRACT TRUNCATED AT 400 WORDS)

Blotting, Northern↗
PubMed1989

Effect of lipoteichoic acid on proliferation and differentiation of keratinocytes.

Bacterial infection is always found to be associated with cholesteatoma. Accumulation of keratin debris is one of the crucial factors for the growth of cholesteatoma. The effects of lipoteichoic acid, a cell wall component of gram-positive bacteria, on the proliferation and differentiation of keratinocytes were studied. Various concentrations of lipoteichoic acid (0 to 100 micrograms/ml) were added to keratinocytes. DNA synthesis and protein synthesis were inhibited by decreasing the incorporation of 3H-thymidine and 3H-leucine into keratinocytes. The effects of lipoteichoic acid on terminal differentiation were then studied by measuring the number of sodium dodecyl sulfate-insoluble cornified cell envelopes and the transglutaminase activity (a marker of terminal differentiation) determined by incorporation of 3H-putrescine into cornified envelopes. These studies showed that lipoteichoic acid stimulated the formation of cornified cell envelopes and transglutaminase activity. These findings suggest that lipoteichoic acid stimulated the terminal differentiation and accumulation of keratin debris and that lipoteichoic acid might have stimulatory effects on the development of cholesteatoma.

Animals↗
PubMed1989

Neurotransmitter effects on inhibitory burst neurons in the cat.

The present experiment was designed to determine which neurotransmitter influences the burst pattern in the firing of the inhibitory burst neurons (IBN) during vestibular nystagmus. Cats were anesthetized with ether and mounted in a stereotaxic apparatus on a turntable, implanted stimulation electrodes, removed occipital bone and aspirated the vermal part of cerebellum. After the operation ether was discontinued. The recordings took place with the cats in an alert condition created by upper cervical cord transsection, artificial respiration and local anesthesia by infiltrating 0.5% lidocaine into the semilunar ganglions every two hours. We also employed iontophoretic application of the various drugs: GABA, muscimol, glycine, serotonin (5-HT) and bicuculline through seven-barrelled glass micropipettes. GABA or muscimol did not influence nystagmus rhythm, but both chemicals caused strong suppression of burst activities in IBN. Since this inhibitory effect of GABA was suppressed by the simultaneous application of bicuculline, IBNs appear to be controlled by GABAA receptor. Glycine and 5-HT did not change the firing pattern of IBN. Application of bicuculline itself caused an increase of tonic discharges of IBN. These findings suggest that IBN receive inhibitory impulses from the higher GABAergic neurons.

Animals↗
PubMed1989

Temporal bone pathology of a patient without hearing and caloric reaction, and with counter-rolling after chronic myelocytic leukemia.

The temporal bone pathology of a 36-year-old man who suffered from chronic myelocytic leukemia and sudden hearing loss of both ears, was studied from the viewpoint of neurotology. Neurotological examination showed bilaterally profound hearing loss and no caloric reaction but good counter-rolling reaction to the right and the left head tilt and no other abnormal neurological findings. He died of intracranial hemorrhage. A study of histopathology of the temporal bones revealed extensive destruction of the organ of Corti, dilatation of Reissner's membrane, leukemic infiltration in the cochlea but good preservation of sensory hair cells in the vestibular endorgans. Leukemic cell infiltration in perilymphatic and endolymphatic spaces, and leukemic hemorrhage in the perilymphatic spaces were observed. And also in the left internal auditory canal, obvious leukemic infiltration and marked hemorrhage were observed, but in the right internal auditory canal, no abnormal change was found. We discuss the correlation between neurotological findings and histopathological findings.

Adult↗
PubMed1988

The optimum pH of serum alkaline phosphatase after induced cholestasis in the male rat, mouse and rabbit.

The optimum pH of serum alkaline phosphatase (alk. P., EC 3.1.3.1) was investigated in adult male rats, mice and rabbits after fasting or after the induction of cholestasis by a single oral dose of 200 mg/kg alpha-naphthylisothiocyanate (ANIT). The nature of serum alk.P. was also studied with the inhibitory effects of three L-amino acids (L-phenylalanine, L-homoarginine and L-cystine) and by electrophoresis. In the rat, fasting as well as ANIT-treatment shifted the optimum pH of alk.P. from 9.4 to 10.0 due to a decrease in intestinal isoenzymes or due to newly appeared liver isoenzymes, while no shifting occurred in mouse and rabbit.

1-Naphthylisothiocyanate↗
PubMed1988

Circadian rhythm of liver parameters (cellular structures, mitotic activity, glycogen and lipids in liver and serum) during three consecutive cycles in phenobarbital-treated rats.

The circadian rhythm of gastric content, serum alkaline phosphatase (alk.P.), serum lipids, body weight (wt), relative (rel.) liver wt, cellular structures (by light- and electron-microscopy), mitotic activity of hepatocytes, glycogen content, protein and lipids in liver was studied in 180 male Sprague-Dawley rats orally treated at 0830-1030 with 50 mg/kg phenobarbital (PB) for 7 days. Thereafter, five PB-treated males and five controls each were studied at 4-hr intervals at 0600, 1000, 1400, 1800, 2200 and 0200 on 3 consecutive days. The lighting schedule in the colony was 12:12 = light/dark (light from 0600 to 1800). Following the rhythm of gastric emptying, the rel. liver wt showed a clear circadian rhythm with a peak at 0800. The rel. liver wt was raised in PB-treated rats at all times of the day. The circadian rhythm of cellular structures was closely related to the hepatic glycogen content which exhibited a clear rhythm with the peak also at 0800, but lowered values were found in PB-treated rats. The mitotic activity of hepatocytes was significantly increased in PB-treated rats but displayed the same circadian rhythm as controls with peaks at noon and troughs at midnight. The well-known hypertrophy of the smooth endoplasmic reticulum in PB-treated rats was not found at 0600, but was fully developed at 1400 and 2200. PB-treatment increased significantly the liver content of cholesterol, triglycerides and phospholipids. Liver cholesterol showed a clear circadian rhythm with peaks at 1800. No rhythm of liver protein, triglycerides and phospholipids was observed. In serum, levels of cholesterol were significantly elevated, those of triglycerides and alk.P. significantly lowered, while those of phospholipids were not affected by the treatment. The three serum lipids, alk.P. and beta-lipoprotein exhibited a clear circadian rhythm, while serum glucose and non-esterified fatty acids did not.

Animals↗