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Biomedical subjects

T Higuchi

Publications and source records attributed to T Higuchi.

At least 523 records · Page 29Linked to original sources
PubMed1987

Regiospecific oxygenations during ring cleavage of a secondary metabolite, 3,4-dimethoxybenzyl alcohol catalyzed by lignin peroxidase.

Enzymatic oxidation of veratryl alcohol yielded a new ring cleavage product (delta-lactone) in addition to the two known gamma-lactone products. The experiment with 18O-enriched water and dioxygen clearly showed that one oxygen atom each from water and dioxygen is specifically incorporated into the cleavage product at the original C3 or C4 position of 3,4-dimethoxybenzyl alcohol. A new type of reaction mechanism proposed for the ring cleavage of this compound is rationally explained in good accord with the one-electron transfer mechanism.

Benzyl Alcohols↗
PubMed1987

Vaginal distension induces milk ejection-related burst of oxytocin neurones interacting with suckling stimuli in lactating rats.

Milk ejection-related bursts of action potentials recurred at fairly regular intervals during suckling in oxytocin cells of anesthetized lactating rats. Additional milk ejection-related bursts were frequently induced in response to vaginal distension. The latency for the induced response was 2.9 +/- 0.2 s and the size of the induced bursts was similar to that of spontaneous ones. When animals were not suckled, the burst was in no case induced by the stimulus. The findings indicate that the two afferent stimuli arising from the mammary gland and vagina can interact with each other in generating milk ejection-related bursts of oxytocin cells.

Action Potentials↗
PubMed1987

Facilitation of milk ejection-related activation of oxytocin-secreting neurones by osmotic stimulation in the rat.

Extracellular recordings were made from antidromically identified neurosecretory cells in the paraventricular nucleus of the hypothalamus in urethane-anesthetized lactating rats. Sixty-six percent of the rats tested (n = 80) showed reflex milk ejections during suckling. Oxytocin neurones could be distinguished from other neurosecretory neurones by a characteristic high-frequency burst of spikes displayed before a reflex milk ejection. Twenty-three of the oxytocin neurones recorded from twenty-three individual animals were tested for the effect of intraperitoneal injection of 1.5 M NaCl (1 ml), which raised the plasma osmotic pressure from 299.3 +/- 2.4 (SE) mosmole/kg to 313.0 +/- 2.4 mosmole/kg. The injection significantly increased not only the firing rate of the oxytocin neurones (from 1.7 +/- 0.3 spikes/s to 4.9 +/- 0.6 spikes/s) but also the number of spikes per burst (from 53.6 +/- 7.4 to 75.5 +/- 7.5) and burst duration (from 3.38 +/- 0.22 s to 3.80 +/- 0.18 s). The amplitude of reflex milk ejection was also increased to 1.9 times. However, the injection did not change the interval between bursts. On the other hand, intraperitoneal injection of 0.15 M NaCl affected neither these parameters of oxytocin neurones nor the amplitude of milk ejection. Some of the antidromically identified neurones recorded in the rats which showed no detectable reflex milk ejection during suckling displayed intermittent bursts of action potentials. Ten of these neurones in ten individual rats were tested for the effect of 1.5 M NaCl. The number of spikes per burst was significantly increased and reflex milk ejection was induced by the injection in eight of these rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗
PubMed1987

Serum C3 and C4 levels and complement-dependent antibody-mediated cytotoxic activity of islet cell surface antibody in type 1 (insulin-dependent) diabetic children.

The role of complement in the pathogenesis of diabetes was studied in 31 Type 1 (insulin-dependent) diabetic children by assaying serum islet cell surface antibody, C3, C4 and serum complement-dependent antibody-mediated cytotoxicity. Nine of 21 islet cell surface antibody-positive children were within 5 months of disease onset and showed significantly lower serum C3 and C4 levels than either 1 year later or the remainder of the islet cell surface antibody-positive children at 6-12 months after disease onset. The overall trend of all islet cell surface antibody-positive diabetic children within 1 year of disease onset was toward increased serum C3 and C4 levels as the disease progressed. Serum C4 concentration and complement-dependent antibody-mediated cytotoxicity which showed an initial negative correlation were uncorrelated 1 year later. Four children who were initially strongly islet cell surface antibody-positive but negative 1 year later also exhibited significantly higher (p less than 0.05) mean serum C4 levels after 1 year. There was a significant decrease in complement-dependent antibody-mediated cytotoxicity when sera from the diabetic children were treated with either ethylene glycol tetra-acetic acid or ethylene diamine tetra-acetic acid. These data strongly suggest that complement-dependent antibody-mediated cytotoxicity induced by the classical complement pathway involving an islet cell surface antibody may play an important role in the pathogenesis of Type 1 diabetes.

Adolescent↗
PubMed1987

Pelvic neurectomy abolishes the fetus-expulsion reflex and induces dystocia in the rat.

To clarify the origin of dystocia in bilaterally pelvic neurectomized (BPN) rats, the uterine activity during the periparturient period, and reflex straining movements in response to vaginal stimulation and cervical extensibility were monitored. The BPN rat displayed "stretching" movements and the regular continuous uterine activity with a similar onset and intensity to that in control rats (intact, sham-operated or unilateral pelvic neurectomized rats) on days 22 or 23 of gestation, but lacked the "straining" movements which precede each delivery of pups in controls so that parturition was prolonged. Dissection of rats revealed that an unborn fetus was retained in the expanded upper portion of the vaginal cavity. Vaginal distension induced contraction of the abdominal muscles and diaphragm and an inhibition of respiratory movements, resulting in an increase in intraabdominal pressure in urethane-anesthetized control rats. This reflex muscular contraction which reflects the straining movements in normal delivery may be called the fetus-expulsion reflex and does not occur in BPN rats. It differs from the fetus-ejection reflex (Ferguson reflex) which initiates oxytocin release. There was no difference in weight and distensibility of the uterine cervix between sham-operated and operated rats on day 22 of pregnancy. The results suggest that the main abnormality of delivery in BPN rats, a prolongation of the process of delivery, may be due to a lack of the fetus-expulsion reflex which plays a physiologic role in removing a fetus from the upper vaginal cavity against the resistance of the pelvic outlet.

Animals↗
PubMed1987

Endoscopic mechanical lithotripsy for the treatment of common bile duct stone. Experience with the improved double sheath basket catheter.

Using a newly designed basket catheter, endoscopic mechanical lithotripsy was attempted in 14 patients with common bile duct stones following endoscopic sphincterotomy, and was successful in all cases. Endoscopic mechanical lithotripsy is a supplementary means of removing common bile duct stones after endoscopic sphincterotomy, and its usefulness is highly rated. In some cases, however, there is difficulty in inserting the basket catheter into the common bile duct and grasping the gallstone. The newly designed forceps was accordingly developed, to smash these bile duct stone more reliably and effectively.

Catheterization↗
PubMed1987

Overproduction and preliminary X-ray characterization of aspartate aminotransferase from Escherichia coli.

The aspartate aminotransferase of Escherichia coli was overproduced in cells after genetic manipulation, and was crystallized from a polyethylene glycol solution, pH 7.0. The crystals obtained were of good quality and had diffractions extending beyond 2.4 A. The space group and unit cell dimensions were determined with a precession camera and a four-circle diffractometer to be C222(1), and a = 157.1 A, b = 85.5 A, and c = 79.7 A, respectively. Only one protein subunit is contained in an asymmetric unit.

Aspartate Aminotransferases↗
PubMed1987

Effect of triglyceride on small intestinal absorption of cefoxitin in rats.

Coadministration of trilaurin or monolaurin with sodium cefoxitin increased its absorption from the small intestine of the rat. Its absorption from the rectum was effected to a lesser extent except when lipase was present. Lipase, a natural constituent of the small intestine fluid, may therefore be essential for the adjuvant action of trilaurin on cefoxitin absorption across the intestinal membrane. Among the triglycerides used, trilaurin and tricaprin were the most effective enhancers of cefoxitin absorption. Both the rate of degradation of triglyceride to its fatty acid component and subsequently the rate of fatty acid absorption were factors influencing the enhancing action. Maintenance of fatty acid concentration at the small intestinal absorption site was shown to be necessary to obtain a cefoxitin bioavailability of up to 70%.

Animals↗
PubMed1987

The synergistic effects of concurrent administration to rats of EDTA and sodium salicylate on the rectal absorption of sodium cefoxitin and the effects of inhibitors.

Plasma levels of cefoxitin, as enhanced by rectal coadministration of sodium salicylate, were reduced by concurrent administration of less than 0.5 mg mL-1 N-ethylmaleimide (NEM) or p-chloromercuriphenylsulphonic acid, sodium salt (p-CMP). Concentrations of these inhibitors above 1 mg mL-1 resulted in enhanced peak plasma values of cefoxitin. This did not occur after coadministration with either ethylenediaminetetraacetic acid (EDTA) or polyoxyethylene-23 lauryl ether (POE). Ouabain and 2,4-dinitrophenol (DNP) suppressed plasma cefoxitin levels in the presence of salicylate and the enhancing effects of EDTA and POE when EDTA and POE were administered at low doses. At higher concentrations of EDTA and POE, DNP had little effect, while ouabain had little effect on POE and only partially suppressed the effects of EDTA. Plasma concentrations of cefoxitin after coadministration with salicylate and POE together, or with EDTA and POE together, were about the same as expected from summing the plasma levels resulting from coadministration of each adjuvant individually at the same concentrations. However, combined administration of salicylate and EDTA with cefoxitin yielded plasma cefoxitin concentrations which were much higher than expected from the sum of their individual actions.

2,4-Dinitrophenol↗
PubMed1987

Activation of neurosecretory cells by osmotic stimulation of anteroventral third ventricle.

Extracellular action potentials of paraventricular neurosecretory cells were obtained from urethan-anesthetized rats during microinjection of a hyper- or hypotonic solution into the anteroventral third ventricle (AV3V), third ventricle, or the vicinity of the recording site. The injection of a 0.2-microliter NaCl solution with a concentration range from 0.16 to 0.8 M into the AV3V excited most of the neurons tested. However, the magnitude of the response was dose related. In most cases, arterial blood pressure recorded simultaneously with the excitatory response of the neuron did not change after the injection. Distilled water (0.2 microliter) was injected into the AV3V after the intraperitoneal injection of a 1.5 M NaCl solution (1 ml), which decreased the firing rate in 67% of the neurons tested. The small volume (0.2 microliter) of hypertonic saline, which was effective when injected into the AV3V, excited none of the neurons tested when injected into the third ventricle or the vicinity of the recording site. These results strongly suggest that the AV3V is sensitive to the osmotic stimulus within a physiological range and that the region plays an important role as an osmoreceptor site for the osmoregulation of paraventricular neurosecretory cells.

Animals↗
PubMed1987

Certain neuroleptics reduce bone mineralization in schizophrenic patients.

A significant increase of urinary Ca and hydroxyproline levels and a decrease of urinary alkaline phosphatase activity were found in 12 schizophrenic patients receiving certain neuroleptic drugs. In these patients, the levels of active metabolites of vitamin D3 were decreased, while the levels of midmolecule parathyroid hormone were within the normal range, except for 2 cases. These results suggest that certain neuroleptics induce the increased urinary Ca excretion through suppression of active vitamin D3 formation and that chronic treatment with certain neuroleptics may induce abnormal bone mineralization.

Adolescent↗
PubMed1987

[Traumatic posterior fossa hematoma].

The traumatic posterior fossa hematoma was regarded as relatively rare thing, but recently, as the result of the prevalence of CT scanners, the number of reported cases is increasing. We report nine cases of traumatic posterior fossa hematoma. We divided into two categories: one was the acute epidural hematoma, the other was the acute subdural hematoma with cerebellar contusion. Five were cases of the acute epidural hematoma, three were cases of the acute subdural hematoma with cerebellar contusion and a case had both an epidural and a subdural hematoma. All the cases had struck the occipital region and had the occipital bone fracture. The prognosis of the five cases of the acute epidural hematoma was excellent, but that of the four cases of the acute subdural hematoma with cerebellar contusion was poor and they all died inspite of the removal of the hematoma executed in three cases. We estimated that the hitting forth was extremely strong in cases of the subdural hematoma with cerebellar contusion, and that the momentary deformity of the occipital bone might injure the cerebellum directly. Once a hematoma was produced in the posterior fossa, it oppresses the brainstem and causes the acute hydrocephalus, so the state of consciousness and respiration deteriorate suddenly. In cases of the acute epidural hematoma, appropriate surgical intervention could save the patients and resulted in good outcome. But in some cases of the fulminant type acute epidural hematoma of the posterior fossa caused by tearing the sinuses, though we have not experienced, patients die before the diagnosis and treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1986

Effects of carbamazepine and valproic acid on brain immunoreactive somatostatin and gamma-aminobutyric acid in amygdaloid-kindled rats.

Somatostatin and gamma-aminobutyric acid (GABA) concentrations were evaluated in the brain of kindled rats treated chronically with carbamazepine and valproic acid. Kindled seizures were almost completely blocked by treatment with carbamazepine, whereas the effect of valproic acid was partial, suppressing only generalized seizures. The duration of after-discharge in amygdala was suppressed by carbamazepine not by valproic acid. Carbamazepine induced a decrease in immunoreactive somatostatin concentration and an increase in GABA concentration in the temporal cortex of kindled rats. Valproic acid induced only an increase in GABA concentration. The results suggest that somatostatin may be associated with the suppression of focal seizure in amygdala and GABA may have a role in the suppression of generalized seizures.

Amygdala↗
PubMed1986

A novel disialoganglioside (IV3NeuAcIII6NeuAcLc4) of human adenocarcinoma and the monoclonal antibody (FH9) defining this disialosyl structure.

This ganglioside is highly immunogenic, and immunization of mice with this disialoganglioside fraction coated on Salmonella minnesota followed by fusion of immunized spleen cells with mouse myeloma and selection of the hybridoma by positive reactivity with the purified disialoganglioside resulted in the establishment of a hybridoma secreting immunoglobulin G2a antibody FH9 that reacts specifically with the ganglioside antigen above but not with monosialosyllactotetraosylceramide I (IV3NeuAcLc4), monosialosyllactotetraosylceramide II (III6NeuAcLc4), or any other gangliosides tested.

Adenocarcinoma↗
PubMed1986

Novel fucolipids of human adenocarcinoma: disialosyl Lea antigen (III4FucIII6NeuAcIV3NeuAcLc4) of human colonic adenocarcinoma and the monoclonal antibody (FH7) defining this structure.

A new fucoganglioside, disialosyl Lea, has been found in the disialoganglioside fraction of human colonic adenocarcinoma. The ganglioside has been isolated from four other disialogangliosides by high-performance liquid chromatography followed by preparative high-performance thin-layer chromatography. The structure of the antigen was characterized by its conversion to lactofucopentaosyl(II)ceramide (Lea-active ceramide pentasaccharide), methylation analysis, and high-mass range electron-impact as well as field-desorption mass spectrometry of the permethylated derivative, as shown below: (Formula; see text) Specific removal of alpha 2----3-linked sialosyl residue by influenza virus A2 sialidase, or preferential hydrolysis of the same residue by Clostridium perfringens sialidase in the absence of detergent, resulted in the formation of an intermediate product, monosialosyl LeaII (III4FucIII6NeuAcLc4), which reacted with anti-Lea antibody and with monoclonal antibody FH7 and may have a sialic acid linked at the 6 position of GlcNAc. The IgG3 monoclonal antibody FH7 was established, which reacts specifically with disialosyl Lea and monosialosyl LeaII as above, but does not react with disialosyllactotetraosylceramide (IV3NeuAcIII6Neu-AcLc4), monosialosyl LeaI (IV3NeuAcIII4FucLc4), and other mono- and disialogangliosides isolated from the same cancer tissue. The antibody FH7 may be useful in the detection of human cancer.

Adenocarcinoma↗