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Biomedical subjects

K Honda

Publications and source records attributed to K Honda.

At least 451 records · Page 25Linked to original sources
PubMed1992

The area postrema is not involved in osmotic activation of neurosecretory cells in the supraoptic nucleus.

Experiments were performed to examine whether or not the area postrema (AP) is involved in the osmotic control of neurohypophysial hormone release. In control rats and in rats bearing extensive lesions of AP, extracellular action potentials were recorded from neurosecretory cells in the supraoptic nucleus (SON) and firing rates determined before and after the intraperitoneal (i.p.) injection of 1.5 M-NaCl solution. Lesion of the AP significantly (p less than or equal to 0.05, Mann-Whitney's U-test) lowered firing rate of putative vasopressin (phasic) cells but not that of oxytocin (non-phasic) cells. In lesioned animals, i.p. injection of hypertonic saline, however, caused similar changes in plasma osmotic pressure, plasma oxytocin concentration and mean firing rates of both putative oxytocin and vasopressin cells to those in control rats. The results suggest that the osmotic control of SON neurosecretory cell activity in the rat can take place in the absence of the AP.

Animals↗
PubMed1992

Lesion and electrophysiological studies on the hypothalamic afferent pathway of the milk ejection reflex in the rat.

The afferent pathway of the milk ejection reflex in the hypothalamus was investigated with lesion and electrophysiological methods in anesthetized lactating rats. Destruction of the central region of the mid-hypothalamus (n = 12) blocked milk ejections induced by suckling, while that of the lateral region (n = 7) had no effect. In an electrophysiological study, extracellular recordings of neurons antidromically activated by electrical stimulation of the supraoptic nucleus were obtained from the ipsilateral hypothalamus caudal to the paraventricular nucleus (n = 84). Thirty-nine neurons were examined to see whether their firing activities changed during the milk ejection reflex. A group of 13 neurons were found to show changes in their activities prior to the reflex milk ejection; the neurons displayed a brief high-frequency burst of spikes before each milk ejection in the same manner as oxytocin neurons, and none of them antidromically responded to electrical stimulation of the neurohypophysis. The bursting neurons were recorded from the dorsomedial hypothalamic nucleus (n = 6), the region just lateral to that nucleus (n = 3) and the posterior hypothalamus (n = 4). The locations were included in a region whose destruction blocked the milk ejection reflex. These results indicate that the afferent pathway of the milk ejection reflex in the rat runs through the medial portion of the hypothalamus posterior to the paraventricular nucleus and that this region contains neurons which relay the input to the oxytocin neurons projecting in the neurohypophysis.

Afferent Pathways↗
PubMed1992

Cervical discs are most susceptible to beta 2-microglobulin amyloid deposition in the vertebral column.

Intervertebral discs of 41 chronic renal failure autopsy cases were examined histologically and immunohistochemically to assess the distribution of beta 2-microglobulin-associated (beta 2m) amyloid in the vertebral column. The results demonstrated beta 2m amyloid to appear first in the cervical discs, then in the lumbar and upper thoracic discs, and finally in the middle and lower thoracic discs as the dialysis period is prolonged. The shortest dialysis period for which beta 2m amyloid was detected was one year and seven months. Deposition of beta 2m amyloid was most remarkable in the C4-5, 5-6, and 6-7 levels, which are known to sustain severe mechanical stress in daily life. Thus it is suggested that local mechanical stress accelerates beta 2m amyloidosis. A marked macrophage reaction was observed around the amyloid in cases of severe amyloidosis, the macrophages themselves being immunohistochemically positive for IL-1 beta and TNF-alpha. Amyloid deposition and reactive inflammation mediated by cytokines appear to be closely related to the pathogenesis of destructive spondyloarthropathy.

Adult↗
PubMed1992

Production of monoclonal antibodies specific to major allergens of Cryptomeria japonica pollen.

Monoclonal antibodies (MAbs) directed against Cryptomeria japonica pollen antigen (CPAg) were prepared. CPAg was precipitated with these MAbs and both MAbs CPA7 (IgG2a) and CPA9 (IgG1) recognized two major glycoproteins (m = 41 kDa and 46 kDa) of CPAg. MAb CPA7 or CPA9 was coupled to CNBr activated sepharose and affinity purification of the major allergen of CPAg from the crude extract was performed. The affinity purified CPAg bound IgE antibody present in patients with Cedar pollinosis.

Allergens↗
PubMed1992

An appraisal of pediatric liver transplantation from living relatives. Initial clinical experiences in 20 pediatric liver transplantations from living relatives as donors.

The authors performed 20 liver transplantations from living related donors between June 1990 and July 1991. The 20 pediatric patients (14 biliary atresia, two Budd-Chiari syndrome, one liver cirrhosis after hepatitis C viral infection (HCV hepatitis), 1 progressive intrahepatic cholestasis, 1 liver cirrhosis, 1 protoporphyria) were transplanted with 11 left lobes, eight left lateral segments, and one right lobe. The choice of donors was restricted to the parents of the recipients. The immunosuppressive treatment consisted of FK 506 and steroids. Seventeen recipients are alive, 15 of whom are well and at home. Two recipients, who underwent emergency transplantation, died of postoperative complications. Another recipient died of accidental asphyxia at 6 months after the transplantation. All 20 donors had uneventful postoperative courses and were able to resume their normal social lives. The arterial ketone body ratio (AKBR) increased to above 1.0 within 2 days after the transplantation in all cases. Relatively mild rejection episodes were encountered in only two cases transplanted with ABO-compatible grafts, and these were treated successfully with steroids and FK 506.

Adolescent↗
PubMed1992

Effect of the optical isomers of YM-12617 on increased intra-urethral pressure induced by phenylephrine in anaesthetized dogs.

1. Effects of the individual optical isomers of YM-12617 (R, S 5-[2-[[2-(o-ethoxyphenoxy)ethyl]-amino]propyl]-2- methoxybenzenesulphonamide HCl, (+/-)-YM), a potent selective alpha 1-adrenoceptor antagonist, on the increase in intraurethral pressure (IUP) and diastolic blood pressure (DBP) induced by phenylephrine were evaluated in pentobarbital-anaesthetized female dogs. 2. Phenylephrine (0.1-30 micrograms kg-1 i.v.), an alpha 1-adrenoceptor agonist, dose-dependently increased IUP and DBP. 3. alpha-adrenoceptor antagonists (i.v.) dose-dependently antagonized the increase in IUP and DBP induced by phenylephrine, with a potency ranking of R(-)-YM greater than (+/-)-YM greater than prazosin greater than phentolamine greater than S(+)-YM greater than yohimbine. 4. These results suggest that the alpha 1-adrenoceptor mediates the increase in IUP as well as DBP in anaesthetized dogs, and that alpha 1-adrenoceptors in the urethra and arteries show a stereochemical preference for R(-)-YM.

Adrenergic alpha-Agonists↗
PubMed1992

Platelet alpha-2 adrenergic receptor binding and plasma free 3-methoxy-4-hydroxyphenylethylene glycol in depressed patients before and after treatment with mianserin.

To examine the noradrenergic function in endogenous depression, binding of a selective agonist radioligand, 3H-UK14304, to platelet alpha 2-adrenergic receptors and plasma free 3-methoxy-4-hydroxyphenylethylene glycol (MHPG) were measured in untreated depressed patients. The effects of an antidepressant, mianserin, on these parameters were also assessed. The Bmax and Kd values for 3H-UK14304 binding in 26 untreated depressed patients were significantly higher (p less than 0.05, p less than 0.01) than those in 26 normal controls. On the other hand, there were no significant differences in plasma free MHPG levels between 12 untreated depressed patients and 12 normal controls. Chronic administration of mianserin to 8 depressed patients slightly increased the Bmax and Kd values. However, plasma free MHPG levels did not change after treatment. These findings suggest that depression is related to the subsensitivity of alpha 2-receptors as indicated by a decreased affinity of platelet alpha 2-receptors. In addition, chronic administration of mianserin further decreased the affinity of alpha 2-receptors. This suggests that mianserin acts not only on alpha 2-receptors but also on the other neurotransmitter systems.

Aged↗
PubMed1992

Plasma free 3-methoxy-4-hydroxyphenylglycol in acute schizophrenics before and after treatment.

Plasma free 3-methoxy-4-hydroxyphenylglycol (pMHPG) was measured in 19 patients with acute schizophrenia before and after neuroleptic therapy. Plasma antinoradrenergic activity (pANA) of the neuroleptics used was measured after treatment. Before treatment, pMHPG was higher in the patients than in 20 normal controls. There was a positive correlation between pMHPG level and the global severity of positive symptoms. After neuroleptic therapy, pMHPG was reduced, and there was a significant correlation between the decline in pMHPG and the improvement in positive symptom score. The decline in pMHPG was also correlated with pANA. These results suggest that there is a dysfunction of the noradrenergic system in the brains of some acute schizophrenics with mainly positive symptoms, and that this dysfunction may be improved, along with positive symptom score, after neuroleptic therapy.

Adult↗
PubMed1992

Abolition of prolactin surge induced by ovarian steroid hormones in the lactating rat.

There are data indicating that stress-induced prolactin (PRL) release is blunted in the lactating rat like the release of other stress-associated hormones. In this experiment, the PRL release evoked by administration of estrogen, which is another principal stimulus for PRL release, was examined in ovariectomized lactating rats 8-15 days after delivery. Estradiol benzoate (EB, 20 micrograms) injections into ovariectomized nonlactating rats induced a PRL surge starting between 13:00 and 15:00 h with a peak at 17:00 h 2 days after the treatment, whereas the EB-induced PRL surge was absent in ovariectomized lactating rats separated from their pups at 09:00 h on the day or in mothers without separation from their pups. Injection of either thyrotropin-releasing hormone (TRH; 10 micrograms/kg) or pimozide (0.5 mg/kg) elevated serum PRL concentrations similarly in lactating and nonlactating rats when examined just before the beginning of the expected estrogen-induced PRL surge. Thus, the main cause for the reduced PRL response to estrogen in lactating rats seems not to be in the pituitary gland but in the brain. Progesterone, which is known to induce a PRL surge in ovariectomized estrogen-primed rats by acting on the mediobasal hypothalamus, also failed to evoke a PRL surge in lactating rats. Recovery from the inhibitory influence of suckling on PRL response to EB followed a time course similar to that observed in response to immobilization stress or to morphine injection; estrogen-induced PRL surge started to recover at 6 days and was almost fully recovered 8 days after weaning.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Factors contributing to phoneme recognition ability of users of the 22-channel cochlear implant system.

A study was carried out to determine which factors contributed to the vowel and consonant recognition ability of recipients of the 22-channel cochlear implant system. On the basis of the statistical analysis, no isolated factor showed a strong correlation with vowel recognition score. On the other hand, negative correlations were found between patients' consonant recognition scores and postoperative psychophysical percepts such as threshold levels and maximum comfortable loudness levels. However, multiple regression analysis also showed that the combination of lower threshold levels, a larger number of usable electrodes, and wider dynamic ranges contributed to higher consonant recognition scores.

Adult↗
PubMed1992

L-365,260, a potent CCK-B/gastrin receptor antagonist, suppresses gastric acid secretion induced by histamine and bethanechol as well as pentagastrin in rats.

We evaluated the effects of a potent cholecystokinin (CCK)-B/gastrin receptor antagonist, L-365,260 (3R(+)-N-(2,3-dihydro-1-methyl-2-oxo-5-phenyl-1H-1,4-benzodiazepin - 3-yl)-N'-( 3-methylphenyl) urea); a selective CCK-A receptor antagonist, devazepide (L-364,718); and cimetidine on gastric acid secretion induced by pentagastrin, histamine and bethanechol in anesthetized rats. We also evaluated the effects of L-365,260 and cimetidine on acid secretion in pylorus-ligated rats. Intravenous administration of L-365,260, L-364,718 and cimetidine dose-dependently reduced acid secretion induced by pentagastrin (20 nmol/kg/hr), with ED50 values of 0.63, 19.1 and 2.5 mumol/kg, respectively. Of interest was the finding that L-365,260, like cimetidine, dose-dependently inhibited acid secretion induced by histamine (100 mumol/kg/hr) and bethanechol (5 mumol/kg/hr) with ED50 values of 5.9 and 4.3 mumol/kg, respectively. L-364,718, even at 30 mumol/kg, i.v., had only a slight effect on histamine- or bethanechol-induced acid secretion. Gastric acid secretion was suppressed by treatment with L-365,260 (3-100 mumol/kg, i.v.) and cimetidine (11.9-396.4 mumol/kg, i.v.) in pylorus-ligated rats, with ED50 values of 13.3 and 96.9 mumol/kg, respectively. These results indicate that L-365,260 suppresses acid secretion induced by histamine and bethanechol in rats and that the gastrin receptor plays an important role in acid secretion in pylorus-ligated rats.

Animals↗
PubMed1992

Expansion of plasma volume by intragastric isotonic saline inhibits supraoptic neurones in rats.

To determine whether an increase in plasma volume might directly influence supraoptic neurones, single cell extracellular recordings were made from magnocellular neurones of the supraoptic nucleus in urethane-anaesthetized rats as plasma volume was expanded by intragastric injection of isotonic saline. Continuous ratemeter records taken before, during and after intragastric injections of 10 ml isotonic saline showed that the firing rate of putative vasopressin cells was reduced by 2.21 spikes/s (P < 0.02; n = 9; paired t-test) after 50 min. Putative oxytocin cells, after an initial increase in firing rate which lasted approximately 30 min, showed a decrease of 0.98 spikes/s (P < 0.02; n = 6; paired t-test). A population of 93 control cells of both types had a median firing rate of 4.69 spikes/s, a comparable group of 65 cells recorded 1 h after intragastric injection had a median firing rate of 3.15 spikes/s and another group of 68 cells recorded 1 h after a second injection had a median firing rate of 2.5 spikes/s. These differences were significant (P < 0.04 and P < 0.01; Mann-Whitney U test). The haematocrit of plasma samples taken from five similarly anaesthetized control animals was 49.7%. One hour after one intragastric injection the value was significantly (P < 0.02; paired t-test) reduced to 46.7% and 1 h after a second injection it was further reduced to 42.1% (P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Influence of noise on heart rate and quantity of work in mental work.

In the present study, we investigated the correlation between the physiological function, heart rate (HR) and the quantity of work performed when A-weighted sound pressure level of factory noise or construction noise was varied during the mental operations of calculation and erosion. Furthermore, we looked for differences in the effects of sound noise and music on the quantity of work performed. The A-weighted sound pressure level was set at four levels of background noise, i.e. 60, 70 and 80 dB (A). The music sound level was set at 70 dB (A). The subjects were exposed to factory noise, construction noise and music during their mental work. A balanced factorial experiment was conducted with a total of 16 combinations of types of mental work (two levels of calculation and erosion), sound noise (two levels of factory and construction sound noise), and A-weighted sound pressure levels (four levels). The order of the experimental procedures was determined at random. The following conclusions were made from the findings of the study. 1) HR elevation occurred due to exposure to sound noise, and further increase in HR resulted from an increase in the A-weighted sound pressure level. This result can be attributed to the action of sound noise as a stressor, which excites sympathetic nerves, leading to an elevation of HR. 2) The quantity of work performed decreased with an increase in the A-weighted sound pressure level. 3) When the subjects were exposed to music with an A-weighted sound pressure level of 70 dB (A) instead of sound noise of the same level, almost no elevation of HR was observed. However, the quantity of work completed when exposed to music was less than that performed when exposed to sound noise of the same A-weighted sound pressure level.

Heart Rate↗
PubMed1992

Remarkable improvement of growth and developmental retardation in Crohn's disease by parenteral and enteral nutrition therapy.

The patient, an 18-yr-old male (admission ht 153 cm, wt 30 kg), had been suffering from growth arrest and intermittent abdominal pain since he was 13 yr old, which was left untreated. Examinations on admission disclosed almost normal pituitary function, while levels of testosterone and somatomedin C were low. Roentgenological examination revealed extensive skip-stenotic lesions and longitudinal ulcers in the ileum, diagnostic of Crohn's disease. Therapy involving high-caloric parenteral and enteral alimentation resulted in a marked increase in both ht and wt, and improvement in roentgenological and colonoscopical findings. The interrelation between Crohn's disease and malnutrition with reference to some reports in the literature is discussed.

Adolescent↗
PubMed1992

Kinetics and thermodynamics of double-helix formation of self-complementary deoxyribooctanucleotides d(TCTATAGA) and d(TAGATCTA).

Double-helix formation of self-complementary deoxyribooctanucleotides, d(TCTATAGA) and d(TAGATCTA), with identical nearest neighbor base pairs has been studied by means of UV melting and temperature-jump techniques. The self-complementary duplexes of both octanucleotides with identical nearest neighbors had similar stabilities: The stabilization energies of the octanucleotides at 25 degrees C were 5.8 kcal mol-1 for d(TCTATAGA) and 6.7 kcal mol-1 for d(TAGATCTA). On the kinetic curve the melting reactions finished within 20 ms for d(TCTATAGA) and 40 ms for d(TAGATCTA) at 20 degrees C. For both octanucleotides the rate constants of dissociation increased and the rate constants of association decreased with increasing temperature.

Deoxyribonucleotides↗
PubMed1992

[Analysis of pedestrian injuries in traffic accidents: impact point, injury portion, and injury severity].

We conducted in-depth case studies of traffic accidents involving 118 pedestrians, who were struck by the fronts of bonnet-type cars. The data were reviewed in order to correlate injury severity with pedestrian age, and area of body contact, contact surface of vehicle or the local environment, and impact speed. It was found that head injuries caused by impacts against the top surface of car bonnets and leg injuries caused by front bumpers both showed high incidence rates. Both head and leg injuries caused by striking the vehicle were more severe than those caused by striking the road surface. In cases of impact between the head and the solid portion of the vehicle, such as the A-pillar, or in cases of secondary impact between the head and underhood solid structures such as shock tower, injuries tended to be more severe. The location of head impact varied according to the stature of the pedestrians.

Accidents, Traffic↗
PubMed1992

Prolonged exposure to catecholamines enhances sensitivity of smooth muscle relaxation induced by sodium nitroprusside and atriopeptin.

Desensitization of alpha-1 adrenergic receptor-mediated contraction occurs in aortic smooth muscle from rats after in vitro exposure to norepinephrine (NE). The purpose of this study was to examine effects of pretreatment of blood vessels with catecholamines on relaxant responses of the vessels to sodium nitroprusside (SNP) and atriopeptin III (ANF). Vessels preincubated with NE for 4 hr had a markedly increased sensitivity to relaxation induced by SNP as compared to controls. The concentration of SNP giving half-maximal relaxation (log EC50) was -8.78 +/- 0.09 in the vessels pretreated with NE and -7.40 +/- 0.18 in controls (P less than .001). NE-treated vessels also had an increased sensitivity to ANF (EC50 -8.23 +/- 0.11 vs. -7.03 +/- 0.31, respectively; P less than .01). However, both desensitized and control vessels had similar sensitivity to relaxation induced by 8-bromo-cyclic GMP. The capacity of SNP to stimulate intracellular cyclic GMP accumulation in vessels pretreated with NE was greater than controls at a high concentration of SNP (10(-5) M.). However, there was no correlation between vasodilation induced by lower concentrations of SNP and stimulation of cyclic GMP accumulation in these blood vessels. Activity of soluble and particulate guanylate cyclase in NE-treated vessels was increased compared to controls. Changes in sensitivity of smooth muscle relaxation to SNP and ANF after prolonged exposure to catecholamines may relate to changes in capacity of the cyclic GMP system.

Animals↗