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Biomedical subjects

H Higuchi

Publications and source records attributed to H Higuchi.

At least 289 records · Page 16Linked to original sources
PubMed1983

[Traumatic cerebral aneurysm: 94 cases from the literature and 5 cases observed by the authors].

Traumatic intracranial aneurysm is rare lesion which is complicated severe head injury. In spite of this rarity, this aneurysm is well known by the fact of high probability of rupture, and high mortality rate. Ninety-four cases of traumatic aneurysms, including 5 cases of our own are discussed. In 94 cases, 83 cases (88.3%) are located at the middle cerebral arteries and/or the anterior cerebral arteries. There are only 2 cases (2.1%) located at the posterior fossa. All of these 94 aneurysms are situated at the peripheral arteries and/or cortical branches, in the distance of Willis' arterial ring. There are 8 cases which lead to be cured spontaneously without any surgical treatment. It was reported by some authors that the traumatic intracranial aneurysms expecting spontaneous healing had some characteristics by the cerebral angiography, such as irregular shapes, and unclear connections from parent arteries. However, these characteristics are sometimes common in the traumatic intracranial aneurysms. Therefore, it is actually difficult to differentiate spontaneous healing aneurysms from deteriorating ones. As for the prognosis of these 79 cases which are able to be examined, the mortality rate of non-surgical group is 4 times higher compared with that of the surgical group, that is the former 40%, and the latter 11%, respectively. According to these facts, authors concluded that the principle therapy of traumatic intracranial aneurysm is surgical treatment.

Adolescent↗
PubMed1982

Molecular mechanism of the effects of guanine nucleotide and sulfhydryl reagent on muscarinic receptors in smooth muscles studied by radiation inactivation.

The molecular sizes of the units concerned in 3-quinuclidinyl benzilate (QNB) binding and in the effects of guanine nucleotide and sulfhydryl reagent on the inhibition of QNB binding by carbachol in smooth muscle of guinea pig ileum were determined to be 76,000, 179,000 and 107,000, respectively by the radiation inactivation method. One or more subunits (GTP subunit) other than the receptor subunit in a muscarinic receptor appeared to be involved in the effect of guanine nucleotide. When guanine nucleotide was present, the receptor subunit seemed to be dissociated from the GTP subunit.

Animals↗
PubMed1982

Effects of trypsin-treatment on agonist binding affinity to the muscarinic acetylcholine receptor.

Trypsin-treatment of the microsome fraction of the ileum and the synaptic membrane fraction of the cerebral cortex of guinea-pig caused selective reduction in the apparent affinity of an agonist (carbachol), but not an antagonist (atropine), to muscarinic acetylcholine receptors (mAChR), measured as inhibition of binding of 3H-quinuclidinyl benzilate (3H-QNB). This effect was similar to that of Gpp(NH)p. The effects of trypsin and Gpp(NH)p were not additive. On the other hand, treatment of these fractions with 5,5'-dithiobis (2-nitrobenzoic acid) (DTNB) increased the apparent affinity of agonist, but not antagonist. The effect of DTNB predominated over those of trypsin and Gpp(NH)p, when the fractions were treated with two reagents simultaneously.

Animals↗
PubMed1982

Desensitization of the alpha adrenergic receptor system in guinea pig vas deferens.

Desensitization induced by alpha adrenergic (alpha-Ad) stimulation was investigated in organ cultured vas deferens of guinea pig. Brief exposure (1-2 min) of the muscle to noradrenaline (NA) caused short-term desensitization to both NA and acetylcholine (ACh), but not to high K+. After removing the agonist this desensitization completely disappeared within 15 min. Prolonged exposure to NA (i.e., cultured with NA for 3-24 hr) elicited long-term desensitization to NA, ACh and K+ (50 mM), but it did not change the maximal contraction by high K+ (154 mM). After removing NA from the culture medium the response to the agonist was restored to normal within 24 hr, but not within 15 min. The number and affinity of alpha-Ad and muscarinic ACh receptors, which were measured by the binding of 3H-WB4101 and 3H-QNB, respectively, were not changed in the muscle during these treatments. Moreover, long-term desensitization, but not short-term desensitization, was depressed by the concomitant presence of cycloheximide. The possible mechanisms of desensitization were discussed in comparison with those of various receptor systems.

Acetylcholine↗
PubMed1982

Mechanism of agonist-induced degradation of muscarinic cholinergic receptor in cultured vas deferens of guinea-pig.

The mechanism of agonist-induced degradation of muscarinic cholinergic receptors (mAChRs) was examined by means of [3H]QNB binding by organ-cultured guinea-pig vas deferens. Long-term exposure to ACh decreased the surface mAChR. This so-called 'down regulation' of mAChR was significantly inhibited by anti-endocytotic drugs. Anti-microtubular agents also strongly inhibited the decrease of mAChR remaining on the cell surface. Ammonium chloride and protease inhibitors, which are known to inhibit lysosomal enzymes, had little effect on the decrease and no increase in intracellular mAChR could be detected under these conditions. Chloroquine blocked the decrease in mAChR remaining on the cell surface. Based on these findings, the involvement of clustering and endocytosis in mAChR degradation were considered as possibilities. Furthermore, contraction of the smooth muscle to ACh in long-term desensitization was also examined in relation to the number and nature of the receptors. When the muscles were cultured with ACh and chloroquine or vinblastine, there were indications that the surface mAChR and the contractile system were uncoupled.

Acetylcholine↗
PubMed1982

Developmental changes in alpha-adrenergic and muscarinic receptor-mediated contractions of rat vas deferens.

Studies were made on developmental changes in phasic contractions of isolated rat vas deferens in response to norepinephrine (NE) and acetylcholine (ACh), which are mediated by alpha-adrenergic and muscarinic cholinergic receptors (alpha-R and m-R). The ED50 values of both contractions were almost constant during development, but the maximum responses to NE and ACh per wet weight and the relative contractions by NE and ACh to that by 100 mM K+ decreased greatly between 3 and 8 weeks after birth. However, the alpha- and m-receptors, assayed by measuring binding of [3H]-WB4101 and [3H]-quinuclidinyl benzylate (QNB), increased quantitatively per g wet weight and per mg protein between 2 and 8 weeks after birth, but did not change qualitatively. Thus, a discrepancy between the increases of alpha- and m-receptors and decreases of the maximum responses to NE and ACh was found, and possible mechanisms for this are discussed.

Acetylcholine↗
PubMed1982

Regulation of the alpha-adrenergic system in rat vas deferens.

Regulation of the supersensitivity and subsensitivity of the alpha adrenergic (alpha-Ad) system of rat vas deferens cultured under various experimental conditions was investigated. Muscles cultured for 3 days in normal medium (Eagle's MEM) exhibited marked increase in maximal contraction to noradrenaline (NA) and high K+ (154 mM), while muscles cultured with NA (100 microM) were subsensitive to the stimulants. Studies on the binding of 3H-WB4101, an alpha-Ad antagonist, to the homogenates of normal, supersensitive and subsensitive muscles revealed that the changes in NA-sensitivity were not accompanied by changes in the number or affinity of alpha-Ad receptors in the muscles. The effect of NA in decreasing NA-sensitivity was depressed by an inhibitor of protein synthesis, puromycin or cycloheximide. These results suggest that NA may be important in regulation of the contraction, at least in part through protein synthesis, without affecting the number or affinity of alpha-Ad receptors.

Adrenergic alpha-Antagonists↗
PubMed1982

[Aneurysm of anterior communicating artery associated with aortitis syndrome--a treated case by aneurysmal neck clipping (author's transl)].

A rare case of the cerebral aneurysm associated with aortitis syndrome was reported. It seems to be the first case in which neck clipping was successfully performed for aneurysm of the anterior communicating artery. The patient was a 48-year-old female afflicted with pulseless disease. She was admitted to Iwate Central Hospital with severe headache, vomiting and unconsciousness on November 16, 1980. Her radial pulse was faint on the right side. The left carotid angiography revealed an aneurysm in the anterior communicating artery, and neck clipping of the aneurysm was performed 17 days after the onset. The right serial brachiocephalic arteriography revealed occlusion of the right brachiocephalic artery and the right common carotid artery. The serial aortography revealed stenosis of the left common carotid artery and the left vertebral artery. In the literature, 4 cases of those 7 cases associated with aortitis syndrome had aneurysms at the basilar bifurcation or basilar top. It seems to be the reason that the vertebral artery outlasts longer in aortitis syndrome. In our case, we can relate the aneurysmal formation of the anterior communicating artery to the hemodynamic overload of the left A1. General anesthesia in such cases was discussed.

Aortic Arch Syndromes↗
PubMed1982

[Thermal behavior of phosphate-bonded investment. Part 1. Thermal behavior of MgNH4PO4.6H2O (author's transl)].

Thermal behavior of MgNH4PO4.6H2O was investigated by means of TG-DTA and X-ray diffraction. Two endothermic peaks (90 degrees C and 230 degrees C) and a exothermic peak (660 degrees C) were observed in a micro-DTA curve. Weight loss occurred at two stages corresponding to the two endothermic peaks. Values of weight loss were about 38% and 53%, respectively, at the end of each stage. These values were nearly equal to theoretical weight losses in the formation of Mg2P2O7 from MgNH4PO4.6H2O via MgNH4PO4.H2O. The intermediate, MgNH4PO4.H2O was identified by X-ray diffraction. The second weight loss continued till about 600 degrees C. The product during the second stage was amorphous and Mg2P2O7 began to crystallize above about 600 degrees C. The exothermic peak was thought to correspond to the crystallization. On the other hand, the first endothermic peak separated into two peaks in a macro-DTA curve. The first corresponded to removal of crystal water from MgNH4PO4.6H2O and the second to evaporation of the condensed water. Moreover the exothermic peak also separated into two peaks and the peak temperatures lowered. It was considered that the crystallization was affected by the atmosphere.

Dental Casting Investment↗
PubMed1982

[Thermal behavior of phosphate-bonded investment. Part 2. Reactions in the systems of MgO-MgNH4PO4.6H2O and MgO-NH4H2PO4 (author's transl)].

Reaction process in the equimolar mixtures of MgO-MgNH4PO4.6H2O and MgO-NH4H2PO4 were investigated by TG-DTA and X-ray diffraction. In the MgO-MgNH4PO4.6H2O system, MgNH4PO4.6H2O was changed by heating in the following way. The formation of MgNH4PO4.H2O by dehydration about 100 degrees C and of amorphous Mg2P2O7 by dehydration and removal of NH3 above 200 degrees C and the crystallization of Mg2P2O7 above 600 degrees C. A part of the amorphous Mg2P2O7 reacted with MgO to form Mg3(PO4)2 above 600 degrees C. The crystallized Mg2P2O7 also reacted with MgO to form Mg3(PO4)2 at higher temperature. In the MgO-NH4H2PO4 system, MgNH4PO4.H2O was formed by the reaction between them, which was corresponded to an exothermic peak about 140 degrees C in the DTA curve. MgNH4PO4.H2O, an unknown phase Y and an amorphous phase were formed at 200 degrees C. The crystalline phases almost disappeared and another unknown phase X appeared at 300 degrees C. The phase X also disappeared and Mg(PO3)2 appeared at 400 degrees C. In the TG-DTA curve for this system, an exothermic peak, which was corresponded to crystallization of Mg(PO3)2, was observed about 550 degrees C and the decomposition of NH4H2PO4 ceased after the crystallization. Mg(PO3)2 reacted with MgO to form Mg2P2O7 at higher temperature.

Dental Casting Investment↗
PubMed1982

[The concentrations of 60Co and stable cobalt in the migratory marine organism (author's transl)].

In order to investigate both the contamination level and distribution of radioactive nuclides in the marine environment, the concentrations of both 60Co and stable cobalt were determined. The samples collected from the sea around Japan were fishes, squids. The analytical method for 60Co was consisted of the radiochemical separation using ion exchange resins followed with the low background beta counting, and that for stable cobalt was the spectrophotometric determination. The results obtained were as follows: (1) The viscera of squids was found to enrich both 60Co and stable cobalt. (2) No 60Co was detected in fishes except the liver of bonito taken from the north west Pacific. (3) The correlation between 60Co and stable cobalt was rather good in the squids samples. (4) The enrichment factors for squids and fishes agreed well with the values reported by B. Patel or S.E. Tompson.

Animals↗
PubMed1982

[The concentrations of 60Co and stable cobalt in the coastal marine organisms (author's transl)].

The concentration of 60Co and stable cobalt in the shellfishes and seaweeds which were collected from the coast around Japan were obtained by low background beta counting for 60Co and spectrometric determination of stable cobalt. The results obtained were as follows: (1) The 60Co was found in the shellfishes which were enriched in the stable cobalt. (2) The correlation between 60Co and stable cobalt was rather good in the shellfishes. (3) The activities of 60Co was found in the seaweeds taken from seashore near the nuclear power plant. (4) There was great differences in the specific activities between samples collected from contaminated and not contaminated area.

Cobalt↗