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Biomedical subjects

Y Tsuboi

Publications and source records attributed to Y Tsuboi.

At least 109 records · Page 6Linked to original sources
PubMed1991

Comparisons of the sensation perceived and intradental nerve activity following temperature changes in human teeth.

The relationship between the intradental nerve responses and subjective sensory ratings evoked by thermal stimulation of the teeth was studied in man. Recordings were taken from a total of 12 thermally sensitive units from the inferior dental nerve following thermal tooth stimulation, of which seven responded to both heating and cooling, two were exclusively cold-sensitive and three exclusively heat-sensitive. The early and late sensory responses following both cold and heat stimulation of the tooth were observed. The late sensory responses were more unstable than the early sensory responses. The mean threshold of the early sensory responses to tooth cooling was 13.6 +/- 1.9 degrees C (n = 9) and that to heat stimulation was 48.4 +/- 4.8 degrees C (n = 10). The firing frequency of the heat-sensitive, but not the cold-sensitive, units increased linearly in proportion to the increase in magnitude of the early sensory ratings.

Adult↗
PubMed1991

Fifth somatosensory cortex (SV) representation of the whole body surface in the medial bank of the anterior suprasylvian sulcus of the cat.

The physiological properties of neurons in the medial bank of the anterior suprasylvian sulcus (ASSS-m) of the cat's cortex were studied using unit recording techniques. Receptive fields (RFs) on the face are represented in the most rostral aspects of the ASSS-m. Of these neurons, 84% responded to light touch of the skin on the contralateral region of the face and 12% responded to mechanical stimulation of facial hair. In addition, 4% of the neurons responded to light touch to the skin or mechanical stimulation of the hair on the contralateral face and also to visual stimuli. The RFs of neurons responsive to the hindlimb and tail are located in the most caudal aspects of the ASSS-m. 22% of these neurons responded to the light touch to the skin and 78% responded to movement of hair. The RFs of neurons responsive to the trunk area in the ASSS-m are located between the facial and hindlimb regions. Of these neurons, 2% responded to light touch of the skin and 98% responded to movements of hair. Some neurons which responded to stimulation of hair or skin on the trunk included forelimb and/or hindlimb areas. In addition, some neurons had RFs on both sides of the trunk including the shoulder area. These regions were in area 5a. Various features of representation in ASSS-m distinguish this region from other somatosensory areas. We designate the ASSS-m as the fifth somatosensory cortex (SV).

Animals↗
PubMed1991

Role of antidiuretic hormone in hyponatremia in patients with isolated adrenocorticotropic hormone deficiency.

We found symptomatic hyponatremia in four elderly patients in which serum sodium (Na) levels ranged from 101 to 122 mEq/l. All 4 patients had low levels of plasma adrenocorticotropic hormone (ACTH), serum cortisol, and urinary excretion of 17-OHCS, and poor responses of ACTH to exogenous insulin and antidiuretic hormone (ADH). Other pituitary hormones were all normal. They were therefore diagnosed as having isolated ACTH deficiency. Plasma ADH was relatively high despite hypoosmolality which was associated with the hyponatremia. Water loading test revealed impaired water excretion and poor suppression of plasma ADH. Replacement with 20-30 mg hydrocortisone completely restored the serum Na level and restored the plasma ADH level to the normal range in all 4 patients. Other factors such as decreased glomerular filtration, enhanced urinary Na loss and decreased Na intake were also included. These results indicate that there is marked hyponatremia and that in the presence of hypoosmolality the sustained secretion of ADH is the key factor in causing the impaired water excretion and hyponatremia in isolated ACTH deficiency.

Adrenocorticotropic Hormone↗
PubMed1990

Input-output relationships in the jaw and orofacial motor zones of the cat cerebral cortex.

Input-output relationships of the jaw and orofacial motor zones in the cerebral cortex of lightly anesthetized cats were studied. These relationships were examined by studying the motor effects produced by intracortical microstimulation (ICMS) and recording from single neuron. Jaw and orofacial motor effects were evoked by ICMS of the anterior part of the coronal and lateral sigmoid gyri (C-S motor zone) and the lateral wall of the presylvian sulcus (P motor zone). ICMS of the P motor zone produced more complex movements than that of the C-S motor zone. Repetitive stimulation of the P motor zone also evoked rhythmic jaw movements. Almost all cortical cells located in the C-S motor zone responded to tactile stimulation of cutaneous skin of the orofacial regions or the tooth, whereas those of the P motor zone received no cutaneous input from the orofacial regions. Cytoarchitectonically, the C-S motor zone was restricted to areas 3a, 6a beta and occasionally to area 4 gamma, whereas the P motor zone was represented to area 6a beta. Therefore, it is concluded that the C-S motor zone might be involved in sensorimotor integration of the jaw and orofacial motor functions, whereas the P motor zone might function only as a command area for jaw and orofacial movements.

Animals↗
PubMed1990

Distribution and response properties of cat SI neurons responsive to changes in tooth temperature.

1. The activity of 214 tooth pulp-driven neurons (TPNs) in the primary somatosensory cortex (SI) activated by electrical stimulation of the canine tooth pulp was studied in anesthetized cats. These neurons were tested for their responses to thermal stimulation of the tooth pulp. 2. One hundred fifty-five TPNs were not responsive to changes in tooth temperature (thermally insensitive, TINS-TPNs) and 59 TPNs were responsive (thermally sensitive, TS-TPNs: 38 TS-TPNs were heat sensitive and 21 were cold sensitive). TS-TPNs were also tested for responsiveness to mechanical and thermal stimulation of the skin, mucosa, or periodontal membrane. Each TS-TPN was classified on the basis of cutaneous, mucosal, or periodontal mechanical receptive-field properties as either low-threshold mechanoreceptive (LTM: 57%), wide dynamic range (WDR: 25%), nociceptive specific (NS: 10%) or pulp specific (PS: 8%). 3. TS-TPNs were distributed in an upper bank of the orbital sulcus of SI. The majority were located in laminae III (32%) and IV (60%) of area 3b. 4. Heat-sensitive LTM, WDR, PS TS-TPNs, and cold-sensitive LTM TS-TPNs were characterized by a rapid rise in firing rate during thermal stimulation of the tooth pulp. In contrast, heat-sensitive NS and cold-sensitive NS and PS TS-TPNs responded with a slow rise in firing frequency during thermal stimuli delivered to the tooth pulp. 5. A linear regression analysis was applied to the stimulus-response functions of neuronal discharges of TS-TPNs. Fifty-six percent of heat-sensitive LTM, WDR, and cold-sensitive LTM TS-TPNs showed statistically significant relation (P less than 0.5) between peak firing frequency and stimulus temperature and increasing firing frequency after increases in stimulus temperature, whereas heat-sensitive and cold-sensitive NS and PS TS-TPNs did not show a clear increase in firing frequency during the thermal stimulus. 6. These findings suggest that heat-sensitive LTM and WDR TS-TPNs and cold-sensitive LTM TS-TPNs that showed high regression coefficients in stimulus-response function may be involved in encoding the intensity of noxious thermal stimulation of the tooth pulp.

Animals↗
PubMed1989

Effects of intrastriatal injections of selective dopamine D-1 and D-2 agonists and antagonists on jaw movements of rats.

The effects of bilateral intrastriatal injections of the selective D-1 and D-2 antagonists, SCH23390 and sulpiride on apomorphine-induced jaw movements were studied in ketamine-anaesthetized rats after C1 spinal transection. A photo-transducer attached to the lower mandible automatically detected jaw movements. Apomorphine (0.2, 0.5 and 1.0 mg/kg i.v.) dose dependently increased jaw movements, an effect prevented by prior administration into the ventral striatum of either SCH23390 (0.1, 0.5 and 1 microgram) or sulpiride (125 ng). To be effective, SCH23390 had to be given less than 30 min before apomorphine whereas sulpiride had to be given earlier. Sulpiride injected into the dorsal striatum potentiated the effects of apomorphine, an action prevented by administering the sulpiride with SCH23390. Local application of the selective D-1 and D-2 agonists, SKF38393 (5 micrograms) and quinpirole (10 micrograms) into sites within the ventral striatum from which repeated jaw movements could be obtained by electrical stimulation, also evoked jaw movements; the effects of combining the two drugs were much greater than the effects of either drug alone.

Animals↗
PubMed1989

Kinetics and dynamics of enalapril in patients with liver cirrhosis.

The pharmacokinetics and pharmacodynamics (blood pressure, heart rate, serum angiotensin-converting enzyme, and plasma renin activity) of enalapril and enalaprilat were studied after oral administration of enalapril maleate (10 mg) to seven biopsy-proven cirrhotic patients and to seven healthy subjects. The mean Cmax, AUC, and urinary excretion of enalapril and enalaprilat were greater and less (p less than 0.01), respectively, and mean oral clearance of enalapril was less (p less than 0.01) in the cirrhotic group than in the healthy group. However, there was no significant difference in the mean total drug (enalapril plus enalaprilat) excretion between the two groups. Blood pressure fell (p less than 0.05) only at 3 or 4 hours postdose, with no change in heart rate in the two groups. Serum angiotensin-convering enzyme (ACE) decreased (p less than 0.001) and plasma renin activity (PRA) increased (p less than 0.05) in the two groups. The magnitude of the percentage of inhibition of ACE activity was comparable between the two groups. Serum enalaprilat concentration correlated (p less than 0.001) with the percentage of inhibition of ACE activity. The results suggest that the bioactivation of enalapril to enalaprilat is considerably impaired in patients with cirrhosis but that the pharmacodynamic effects do not appear to be blunted in those patients. The mechanism and clinical implications remained unclear.

Administration, Oral↗
PubMed1989

Spotted fever group rickettsia in dogs in Japan.

Prevalence of antibody against spotted fever group-rickettsia in dogs (14/134) from the northern part of Shikoku Island, where spotted fever group rickettsia infection in human is endemic, is significantly higher than that in dogs (4/189) from nonendemic areas.

Animals↗
PubMed1985

Spotted fever group rickettsiosis in Japan.

The acute febrile disease with characteristic rash encountered in Tokushima Prefecture was proved to be a spotted fever group rickettsiosis, which showed a significant rise in agglutinins to both Proteus OX2 and OX19 and significantly high levels of CF antibodies to Rickettsia akari and Rickettsia rickettsii.

Aged↗