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Biomedical subjects

T Higuchi

Publications and source records attributed to T Higuchi.

At least 505 records · Page 28Linked to original sources
PubMed1989

Studies on serum selenium and tocopherol in white muscle disease of foal.

In order to clarify the cause of white muscle disease (W.M.D.) in foals, tocopherol and selenium concentrations in serum and glutathione peroxidase activities in blood were measured. Examination was made on the samples from horses affected with W.M.D., the foal kept with them in the same stable, the foals kept in the stables without affected foals, and respective mares. The heavy-breed horses in Fukuoka prefecture and Tokachi district were also examined for comparison. Serum tocopherol levels of these foals were normal because after intake of colostrum. Mares of affected foals showed lower tocopherol levels than other examined mares (p less than 0.01). Serum selenium levels of all foals were below 65 ppb, showing deficient levels. The mares of affected foals had lower selenium levels than other mares (p less than 0.01). There was a good correlation between serum selenium concentration and blood glutathione peroxidase activity (r = 0.81). Selenium levels in the liver of affected foals were lower than the foals which succumbed with other diseases. Diet supplied in the stables with affected foals showed low alpha-tocopherol and selenium contents. These findings suggest that W.M.D. in foals is attributed to nutritional muscular dystrophy caused by tocopherol and selenium deficiency of their mares in late gestation period.

Animals↗
PubMed1989

Reduced responses of prolactin and catecholamine to stress in the lactating rat.

Prolactin, GH, TSH, adrenaline and noradrenaline responses to the stress of immobilization were compared between lactating and non-lactating dioestrous rats. The concentrations of GH in plasma were reduced to a similar degree by the immobilization of lactating and non-lactating rats, and TSH levels were unchanged in both groups. The increases in plasma concentrations of adrenaline and noradrenaline induced by stress were significantly smaller in lactating than in non-lactating rats. Immobilization caused a marked increase in prolactin levels in the plasma of non-lactating rats but no increase in lactating rats. These changes may help to save energy and maintain milk production during the period of lactation.

Animals↗
PubMed1989

Signet cell carcinoma of the stomach in a patient with acquired immunodeficiency syndrome: a case report.

A case of signet cell carcinoma associated with AIDS is presented. A 50-year old Japanese man with hemophilia A was suffering from human immunodeficiency virus (HIV) infection, the result of multiple injections of clotting factor concentrates. A diagnosis of signet cell carcinoma of the stomach was reached upon endoscopic and histological examinations. Opportunistic infections of esophageal candidiasis and candida septicemia occurred. The patient died of repeated gastrointestinal bleeding and cachexia. Although there is a possibility of the patient having a coincidential carcinoma along with AIDS, the HIV infection, perhaps, had a role in causing signet cell cercinoma.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Specificity of esterases and structure of prodrug esters: reactivity of various acylated acetaminophen compounds and acetylaminobenzoated compounds.

The relative rates of enzymatically catalyzed hydrolysis of various esters of p-acetylaminobenzoic acid (APAB) and variously acylated acetaminophen (APAP) derivatives were measured. Neutral, anionic, and cationic esters were examined. The enzyme sources adopted were rat intestinal homogenate, rat liver homogenate, rat plasma, and a partly purified commercial enzyme. In both APAB and APAP esters, neutral esters were the most sensitive of the enzyme sources examined, and the sensitivity was due to the carbon chain length. The APAB esters were enzymatically more stable than the APAP esters. The relative rates of hydrolysis of these esters varied depending on the enzyme source. The ability of structure recognition was good in rat intestinal homogenate, but weak in rat plasma. These results suggest that ester prodrugs can be designed to cleave preferentially at selected sites along the pathway between absorption and disposition in the body.

Acetaminophen↗
PubMed1988

Unsaturated cyclic ureas as new nontoxic biodegradable transdermal penetration enhancers I: Synthesis.

A new concept was implemented to reduce the toxicity of some new biodegradable transdermal penetration enhancers. These enhancers consist of 1-alkyl-4-imidazolin-2-one and a long-chain alkyl ester group at the N-3 position. The synthesis involves N-alkylation of the parent compound with soft alkylating agents which were prepared in high yields by an improved method. A phase transfer catalysis technique using KOH as the base, tetrabutylammonium bromide as the catalyst, and toluene as the solvent was found to be most effective in the N-alkylation step.

Adjuvants, Pharmaceutic↗
PubMed1988

The investigation of experimental brain tumours using 31P-MRS and 1H-MRI.

In vivo 31P-magnetic resonance spectra (MRS) were obtained by the surface coil method from rat glioma, human glioblastoma, and human neuroblastoma inoculated subcutaneously in CD Fisher rats and hamsters, and the effects of chemotherapy, photoradiation therapy, and radiofrequency hyperthermia as well as 60Co-irradiation were evaluated by sequentially observing spectral changes. In the 31P-spectra of tumour tissue, the nucleoside triphosphate (NTP), phosphomonoesters (PME) peaks were high and the phosphocreatine peak was low compared to those of normal brain. When the antitumour agents were given and were effective, NTP peaks decreased, and inorganic phosphate increased remarkably within several hours after the treatment. 1H-magnetic resonance imaging (MRI) were also obtained in some cases. Necrotic regions was detected by the 1H-MRI as image changes which appeared later than those detected by MRS. It proved practical to monitor the effect of therapy by employing either 31P-MRS or 1H-MRI. However, the image changes which demonstrated the effect of the therapy used closely resembled those changes which occurred with the onset of necrosis in tumour tissue during tumour growth. Several problems for future application of these techniques to human brain tumours are also mentioned.

Animals↗
PubMed1988

Pathophysiological investigation of experimental cerebral ischaemia using in vivo 31P-NMR spectroscopy and 1H-MRI.

The cerebral energy metabolism and brain oedema were investigated in three experimental cerebral ischaemia models using 31P-NMR spectroscopy (MRS) and 1H-NMR imaging (MRI) in the same subject animal. These measurements were performed also in experimental brain oedema models and the findings were compared with each other. 31P-MRS showed an ischaemic pattern in all of the cerebral ischaemia models, that is, ATP and PCr peaks decreased, and the Pi peak increased and shifted to a higher resonant frequency. However, 31P-MRS did not show any remarkable change in the brain oedema models. On the other hand, 1H-MRI clearly demonstrated brain oedema in the brain oedema model. In the cerebral ischaemia models, 1H-MRI findings differed depending upon the type of model, namely the most marked brain oedema was detected in the unilateral middle cerebral arterial occlusion model and no marked change was detected in the temporary four vessel occlusion model. It was thought that this difference depended on the severity of the ischaemic insult. Accordingly, the fundamental pathophysiological problem of cerebral ischaemia was the energy metabolism disturbance with the brain oedema being associated with this disturbance but occurring secondarily. However, in the brain oedema model the main pathological change was the increase in tissue water.

Animals↗
PubMed1988

Degradation mechanisms of phenolic beta-1 lignin substructure model compounds by laccase of Coriolus versicolor.

Phenolic beta-1 lignin substructure model compounds, 1-(3,5-dimethoxy-4-hydroxy-phenyl)-2-(3,5-dimethoxy-4-ethoxyphenyl)propa ne-1, 3-diol (I) and 1-(3,5-dimethoxy-4-ethoxyphenyl)-2-(3, 5-dimethoxy-4-hydroxyphenyl)propane-1,3-diol (II) were degraded by laccase of Coriolus versicolor. Substrate I was converted to 1-(3,5-dimethoxy-4-hydroxyphenyl)-2-(3,5-dimethoxy-4-ethoxyphenyl)-3- hydroxypropanone (III), 1-(3,5-dimethoxy-4-ethoxyphenyl)-2-hydroxyethanone (IV), syringaldehyde (V), 1-(3,5-dimethoxy-4-ethoxyphenyl)-3-hydroxypropanal (VI), 2,6-dimethoxy-p-hydroquinone (VII), and 2,6-dimethoxy-p-benzoquinone (VIII). Furthermore, incorporations of 18O of 18O2 into ethanone (IV) and 18O of H218O into hydroquinone (VII) and benzoquinone (VIII) were confirmed. Substrate II gave 1-(3,5-dimethoxy-4-hydroxyphenyl)ethane-1, 2-diol (IX), 1-(3,5-dimethoxy-4-hydroxyphenyl)-2-hydroxyethanone (X), and 3,5-dimethoxy-4-ethoxybenzaldehyde (XI). Also 18O of H218O was incorporated into glycol (IX) and ethanone (X). Based on the structures of the degradation products and the isotopic experiments, it was established that three types of reactions occurred via phenoxy radicals of substrates caused by laccase: (i) C alpha-C beta cleavage (between C1 and C2 carbons); (ii) alkyl-aryl cleavage (between C1 carbon and aryl group); and (iii) C alpha (C1) oxidation.

Basidiomycota↗
PubMed1988

An outbreak of foodborne hepatitis A in a factory: a possible shift in age of patients in Japan.

We investigated extensively an outbreak of hepatitis A at a factory in suburban Nagoya. Epidemiological study indicated a foodborne outbreak by a supplier of lunches. Serologically, all the employees younger than 30 years of age had been susceptible to hepatitis A virus, but the highest morbidity was observed in the 40-44 age group. The age difference in morbidity from foodborne hepatitis and susceptible populations suggests a shift in mean patient age linked to a shift in antibody prevalence to hepatitis A virus. In communities where the prevalence started shifting after development of sanitary systems, effective prophylaxis for foodborne hepatitis A will be necessary to prevent the disease in an increasing number of older patients in a few decades.

Adult↗
PubMed1988

Reduced oxytocin response to osmotic stimulus and immobilization stress in lactating rats.

The release of oxytocin in response to an osmotic stimulus and immobilization stress was compared in lactating rats 8-12 days after delivery and in non-lactating rats. Intravenous injection of hypertonic saline or immobilization stress induced an increase in blood oxytocin levels in both lactating and non-lactating rats, but the increment in the former was significantly lower than that in the latter. The lower responsiveness of oxytocin release to stress in lactating rats was not altered by ovariectomy 2 days after parturition. Oxytocin release induced by electrical stimulation of the anteroventral third ventricle (an osmoreceptive area), paraventricular nucleus and neurohypophysis was significantly lower, to a similar extent, in lactating rats compared with non-lactating rats. These findings indicate that the structural reorganization reported in the hypothalamo-neurohypophysial system may not function to facilitate release of oxytocin in response to stress and osmotic stimulus in lactating rats. The reduced responsiveness of the release of oxytocin is independent of the influence of ovarian hormones, and may be due to the low ability of the oxytocin neurone itself to release oxytocin, and/or due to the activated inhibitory influence on the oxytocin neurone in the lactating rat.

Animals↗
PubMed1988

Osmoreceptor mechanism for oxytocin release in the rat.

In order to determine whether oxytocin release is controlled by an osmoreceptor mechanism identical with that for vasopressin release, the plasma oxytocin concentration and plasma osmolality were measured during intraatrial infusion and after intraventricular injection of various osmotic solutions in unanesthetized rats. Intraatrial infusion of 0.6 M NaCl Locke solution (L.S.) or 1.2 M mannitol L.S. elevated plasma oxytocin significantly, while 1.2 M urea L.S. caused only a small increase and isotonic L.S. did not change in plasma oxytocin. All hypertonic solutions produced significant and similar increases in the plasma osmolality. Plasma oxytocin was positively correlated with plasma osmolality in the animals infused with hypertonic NaCl or mannitol but not in the animals infused with hypertonic urea. The injection of 2 microliters of 0.6 M NaCl artificial cerebrospinal fluid (CSF) or 1.2 M mannitol CSF into the third ventricle caused a significant increase in plasma oxytocin immediately (5 min after injection) without changing plasma osmolality, while the intraventricular injection of 1.2 M urea CSF or isotonic CSF produced no significant change in plasma oxytocin. These results indicate that oxytocin release is controlled by osmoreceptors rather than Na receptors, that the adequate stimulus for the osmoreceptors is one which produces cellular dehydration and that the osmoreceptors are located in the brain region which is accessible to osmotic agents from both the outside and inside of the blood-brain barrier. Since the organum vasculosum of the lamina terminalis (OVLT) lacks a blood-brain barrier and is known to be involved in osmotic control of vasopressin release, a lesion was made in the anteroventral region of the third ventricle which encompasses the OVLT and the effect of hypertonic NaCl infusion on oxytocin release was examined. No significant increase in plasma oxytocin was observed after intraatrial infusion of 0.6 M NaCl L.S. in the lesioned rats. All of these findings lead to the conclusion that oxytocin release is under the control of osmoreceptors identical to those for vasopressin release.

Animals↗
PubMed1988

In vivo 31P MRS in new antineoplastic agents evaluation on experimental tumor models.

Two new antineoplastic agents, a nitrosourea and a DNA-bis-intercalator have been studied in vivo by 31P magnetic resonance spectroscopy on a rat glioma and Walker carcinoma. On rat glioma, spectra are modified when the tumor is treated by the nitrosourea, showing the depletion of high-energy phosphates. On Walker carcinoma both drugs delay the tumor evolution to necrosis, showing important levels of high-energy phosphates on NMR spectra. There appears to be a great dependence upon energy metabolism during chemotherapy, depending on the nature and physiology of the observed tumor.

Animals↗