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H Yokota

Publications and source records attributed to H Yokota.

At least 19 recordsLinked to original sources
PubMed1992

[Phosphorus 31-magnetic resonance spectroscopic studies of animal liver after extracorporeal shock wave lithotripsy].

The technique of magnetic resonance spectroscopy has been developed, and the study of high-energy phosphate metabolites in the liver using phosphorus 31 magnetic resonance spectroscopy (31P-MRS) has been reported in humans and animals, but few studies have used 31P-MRS for the evaluation of extracorporeal shock wave lithotripsy (ESWL) of the liver. In this study, 31P-MRS was used to evaluate the metabolic changes in hamster liver after ESWL and histological correlation was performed. Syrian golden hamsters were anesthetized and shock waves were irradiated to the left side of the liver. Hamsters were irradiated by LITHOSTAR-PLUS (SIEMENS) at a voltage of 19 KV. 31P-MRS was studied by JNM-GSX model 270 (6.34 Tesla). Typical peaks of 31P-spectra of hamster liver showed a tendency for PDE/beta-ATP, alpha-ATP/beta-ATP and gamma-ATP/beta-ATP to decrease among the irradiated group compared with the control group. However, there were no significant differences in PME/Pi, beta-ATP/Pi or (alpha-ATP-beta-ATP)/beta-ATP between the control group and irradiated group. With regard to intracellular pH and PDE/beta-ATP, a decreasing tendency was noted in the irradiated groups (p less than 0.05). There was no difference in the signal intensity of T1WI and T2WI on 1H-MRI, between these two groups. Pathologically, the irradiated group showed minor hemorrhage and edema in the liver, and subcapsular hematoma. The results obtained from 31P-MRS clearly showed the metabolic changes and were correlated well with the histological findings, but MRI was not capable of providing close visualization of post-ESWL liver damage.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

A restriction fragment length polymorphism (RFLP) locus of rat (Rattus norvegicus) linked to the Cs-1 locus of rat linkage group XIII.

A novel restriction fragment length polymorphism (RFLP) in inbred rats was revealed by Southern blot analysis with a clone arbitrarily chosen from a rat genomic library as a probe. A clone named alpha 403 showed interstrain variations in the length of the EcoRI and HindIII fragments. The EcoRI fragments were either 0.7 or 3 kb, those of HindIII were either 4.5 or 5 kb, and three types were identified as combinations of those fragments in 20 inbred rat strains. These types segregated in backcross progeny as codominant alleles. The locus for the RFLP was thus named A403. Analysis of linkage between the RFLP locus and 13 other loci reveal that the A403 locus was closely linked to the Cs-1 locus (15 +/- 5.2%), which belongs to rat linkage group XIII.

Animals↗
PubMed1992

Topological disposition of UDP-glucuronyltransferase in rat liver microsomes.

The topological disposition of a form of UDP-glucuronyltransferase (called GT-1) in rat liver microsomes was examined. Concanavalin A-Sepharose failed to bind microsomal vesicles even though GT-1 has sugar chains of "high mannose" type, indicating that mannose-containing sugar chains of microsomal glycoproteins including GT-1 are not exposed to the outer surface of microsomal vesicles. Polyclonal antibodies raised against purified GT-1 could bind to microsomal vesicles, indicating that at least part of the GT-1 polypeptide chain is extruded to the outside of the microsomal membrane. Intact microsomal vesicles were digested with carboxypeptidase Y and then subjected to immunoblot analysis using the anti-GT-1 antibodies. It was thus found that the digestion resulted in cleavage of a C-terminal, 2-kDa fragment, leaving a 52-kDa fragment of GT-1 still tightly bound to the membrane. From these results, it is concluded that GT-1 is a transmembrane protein, which extrudes its C-terminal end (at least 2 kDa) to the outside of the membrane, whereas most of its polypeptide chain together with the sugar chains are located on the luminal side of the membrane.

Animals↗
PubMed1992

Activation and stabilization of UDP-glucuronyltransferase by lysophosphatidylcholine.

Interactions between purified UDP-glucuronyltransferase from 3-methylcholanthrene-treated rat liver microsomes (named GT-1) and lysophosphatidylcholine, which is essential for expression of GT-1 activity, were examined. Phospholipid-free GT-1, which could not express its full activity [Yokota et al. (1988) J. Biochem. 104, 531-536], was activated fully by addition of lysophosphatidylcholine (0.04 mM final concentration) into the assay medium. Lysophosphatidylcholine also protected GT-1 effectively against heat inactivation. Palmitoyllysophosphatidylcholine and stearoyllysophosphatidylcholine were most successful for the activation and stabilization of GT-1. On treatment of GT-1 with carboxypeptidase Y, the transferase was inactivated immediately, but the treatment in the presence of lysophosphatidylcholine affected the activity only a little. Lysophosphatidylcholine was also found to protect GT-1 against cleavage by carboxypeptidase Y. On treatment of GT-1 with trypsin or aminopeptidase T, the activity was lost and GT-1 protein could be digested even when lysophosphatidylcholine was present. It is suggested that UDP-glucuronyltransferase forms an active and stable conformation, in which the carboxy-terminal region is protected against protease, with lysophosphatidylcholine.

Animals↗
PubMed1992

Purification and properties of 4-hydroxybiphenyl UDP-glucuronyltransferase from bovine liver microsomes.

A UDP-glucuronyltransferase isoform glucuronizes phenolic xenobiotics such as 4-nitrophenol, and an isoform glucuronizing 4-hydroxybiphenyl has also been found in rat liver. We purified a UDP-glucuronyltransferase isoform glucuronizing 4-hydroxybiphenyl from bovine liver microsomes by solubilization with 0.7% sodium cholate followed by three column chromatographic separations using DEAE-Toyopearl 650S, UDP-hexanolamine Sepharose 4B, and hydroxyapatite. The purified bovine liver 4-hydroxybiphenyl UDP-glucuronyltransferase (named Bovine 4HBGT) had glucuronidation activities toward 4-hydroxybiphenyl and 4-methylumbelliferone but had little activity toward 4-nitrophenol and 1-naphthol. The apparent molecular mass of Bovine 4HBGT was 54,000 Da on SDS-PAGE, and this was decreased to 50,000 Da by digestion with endo-beta-N-acetylglucosaminidase H. These data suggest that Bovine 4HBGT consists of a 50,000 Da polypeptide and a high mannose type oligosaccharide chain(s) of about 4,000 Da. The NH2-terminal sequence of GT-3 was GKVLVWPVDFSXWINI. These properties of Bovine 4HBGT were very similar to those of rat UDP-glucuronyltransferase glucuronizing xenobiotics. However, the NH2-terminal sequence of Bovine 4HBGT had higher homology with that of rat liver 4-hydroxybiphenyl UDP-glucuronyltransferase than with that of rat liver 4-nitrophenol UDP-glucuronyltransferase.

Amino Acid Sequence↗
PubMed1992

Altering the position of the first horizontal cleavage furrow of the amphibian (Xenopus) egg reduces embryonic survival.

The animal/vegetal cleavage ratio (AVCR), defined as the ratio of the height of the animal blastomere to the height of the Xenopus embryo at the 8 cell stage, can be shifted by placing embryos in novel gravitational fields: clinostating (microgravity simulation) increases AVCR, and centrifugation (hypergravity simulation) reduces AVCR. This report contributes to an understanding of the subcellular mechanism responsible for the furrow relocation and assesses its significance. Embryo inversion and D2O immersion were found to increase AVCR, and cold shock was found to reduce AVCR. Based on the additive or antagonistic effects of combined treatments, it is postulated that the primary cause of AVCR changes is an alteration in the distribution of yolk platelets and the rearrangement of microtubule arrays. Embryos with a decreased AVCR exhibited reduced survival in early developmental stages, indicating serious difficulties in cleavage, blastulation and/or gastrulation. Cold-shocked embryos with a reduced AVCR could be rescued by D2O pretreatment or clinostating, an observation which supports the notion that changes accompanying AVCR modifications represent the primary cause of the reduction in percent survival.

Animals↗
PubMed1992

Changes in body composition of germ-free and conventional chickens during starvation.

1. Changes in body composition during starvation were compared between germ-free (GF) and conventionalized (CVL) chicks in experiment 1. At 8 days of age, the GF birds were divided into two groups, i.e. GF and CVL groups. The CVL birds were inoculated with faeces from conventionally reared birds. Until 14 days of age, both birds were fed a diet ad lib. and thereafter starved for 6 days. 2. Nitrogen loss during starvation was significantly lower in CVL birds, though the reverse was true for water loss. Fasting heat production was comparable between two environments. 3. Influence of the gut microflora on body weight and nitrogen losses during starvation was investigated in birds prefed diets high or low in dietary protein in experiment 2. 4. No significant effect of the gut microflora was observed in body weight and nitrogen losses. Body weight was severely reduced in birds prefed the high protein diet and nitrogen loss was lower in birds prefed the low protein diet.

Animals↗
PubMed1992

[Clinical study of intracranial pressure and auditory brain stem response in the cases of diffuse axonal injury].

The course of intracranial pressure (ICP) and the finding of auditory brain stem response (ABR) was discussed in the cases diagnosed as diffuse axonal injury (DAI) established by Gennarelli. ICP was measured in twenty-six cases which were divided into three groups according to the course of ICP: Group (1), in which ICP remained below 20 mmHg (group I, 9 cases). Group (2), in which ICP rose above 20 mmHg but was controlled by therapy (group II, 8 cases). Group (3), in which ICP rose above 20 mmHg and could not be controlled by any therapies (group III, 9 cases). Glasgow outcome scale 3 months after the injury in the cases of group I and II was severe disability (SD) and/or persistent vegetative state (PVS), but all of the cases in group III died. The findings of serial ABR were divided into 3 groups. These were group A (2 cases) which showed normal record, group B (5 cases) which showed elongation of latencies between the first and fifth waves, and group C (5 cases) in which there was no response in ABR. GOS in group A or B was SD and/or PVS, but all of the cases in group C were shown to be dead in GOS. Our studies suggest that the level of ICP in DAI is rather higher than that published in previous reports, and the continuous measurements of ICP and serial records of ABR are useful for evaluating the outcome of DAI.

Adolescent↗
PubMed1992

[Magnetic resonance imaging in diffuse brain injury].

Forty cases diagnosed as diffuse brain injury (DBI) were studied by magnetic resonance imaging (MRI) performed within 3 days after injury. These cases were divided into two groups, which were the concussion group and diffuse axonal injury (DAI) group established by Gennarelli. There were no findings on computerized tomography (CT) in the concussion group except for two cases which had a brain edema or subarachnoid hemorrhage. But on MRI, high intensity areas on T2 weighted imaging were demonstrated in the cerebral white matter in this group. Many lesions in this group were thought to be edemas of the cerebral white matter, because of the fact that, on serial MRI, they were isointense. In mild types of DAI, the lesions on MRI were located only in the cerebral white matter, whereas, in the severe types of DAI, lesions were located in the basal ganglia, the corpus callosum, the dorsal part of the brain stem as well as in the cerebral white matter. As for CT findings, parenchymal lesions were not visualized especially in mild DAI. Our results suggested that the lesions in cerebral concussion were edemas in cerebral white matter. In mild DAI they were non-hemorrhagic contusion; and in severe DAI they were hemorrhagic contusions in the cerebral white matter, the basal ganglia, the corpus callosum or the dorsal part of the brain stem.

Adolescent↗
PubMed1991

A one step sandwich enzyme immunoassay for gamma-carboxylated osteocalcin using monoclonal antibodies.

A highly sensitive, simple and reliable one-step sandwich enzyme immunoassay (EIA) for the gamma-carboxylated form of osteocalcin (Gla-OC) has been developed using a monoclonal antibody. The minimum amount of Gla-OC detected by this EIA was approximately 0.2 ng/ml when a 10 microliter aliquot of the sample was used. The serum Gla-OC level in 30 healthy subjects was 3.6 +/- 2.19 ng/ml (mean +/- SD). A significant increase was seen in patients with chronic renal failure (20.3 +/- 4.60 ng/ml), atherosclerosis (8.3 +/- 4.94 ng/ml) and osteoporosis (10.1 +/- 4.60 ng/ml). The correlation between the values obtained by the sandwich EIA and competitive RIA methods was given by the linear regression equation, y = 2.896 + 0.759 chi, for which the correlation coefficient (r) was 0.815 (n = 58). This newly developed Gla-OC specific EIA may be useful for the diagnosis of metabolic bone disease and ectopic calcification.

Animals↗
PubMed1991

Direct measurement of calpastatin subtypes by sandwich enzyme immunoassay using monoclonal antibodies.

Six stable hybridoma cell lines secreting monoclonal antibodies to human calpastatin were established. All monoclonal antibodies belong to the IgG1 subclass and recognized different epitopes on calpastatin. At least two groups were distinguished; the first group was specific for muscle-type (M-) calpastatin and the second group recognized not only M-calpastatin but also erythrocyte-type (E-) calpastatin. The inhibitory effect of all monoclonal antibodies on calpastatin activity was relatively low even at high concentrations of antibodies. Enzyme immunoassay systems were developed for direct determination of calpastatin subtypes in human cells requiring no other sample treatment than the disruption of the cells. The assay methods were, in principle, based on the sandwich enzyme immunoassay using epitope-specific monoclonal antibodies. The enzyme immunoassay system for M-calpastatin was specific for M-calpastatin and could not detect E-calpastatin. The enzyme immunoassay system for total calpastatin detected not only M-calpastatin but also E-calpastatin. The sensitivity of these assay systems was 10 pmol l-1 of calpastatins. Antigenicity of calpastatins was found to be unchanged in the presence of EDTA and haemoglobin. Good reproducibilities of within-and between-assay series and excellent recovery of exogenous calpastatins from cell lysates were observed. From these results, it seems that our newly developed subtype-specific enzyme immunoassay systems for calpastatins are useful in biochemical studies and clinical testing for determination of calpastatin subtypes.

Antibodies, Monoclonal↗
PubMed1991

Differential effects of phospholipids on two similar forms of UDP-glucuronyltransferase purified from rat liver and kidney microsomes.

Two isoforms of UDP-glucuronyltransferase purified from rat liver (named GT-1) and kidney (named GT-2) have various properties in common but differ in their NH2-terminal sequences. In this study, the two forms were further found to have common immunochemical properties, i.e., they could not be distinguished by Ouchterlony double diffusion and immunoblotting analyses. These isoforms also had the same inducibility as shown by immunoblotting analysis: GT-2 protein in rat was increased by treatment with beta-naphthoflavone and 3-methylcholanthrene, whereas GT-1 was inducible by 3-methylcholanthrene. However, the effects of phospholipids on these enzymes were extremely different. 1-Naphthol glucuronizing activity of GT-1 was increased 7.5-8-fold by lysophosphatidylcholine, but the activity of GT-2 was increased only 3-3.6-fold. The transferase activity of GT-1 toward 4-methylumbelliferone was increased 2-2.5-fold by dilauroylphosphatidylcholine, but that of GT-2 was reduced, while its 4-nitrophenol glucuronidation activity was increased 1.5-fold by the phospholipid. These results indicate that the two similar UDP-glucuronyltransferases from rat liver and kidney interact differently with phospholipids and that the activation level of UDP-glucuronyltransferase activity with phospholipids depends on the aglycone substrates.

Animals↗
PubMed1991

Significance of magnetic resonance imaging in acute head injury.

One hundred seventy-seven patients who had incurred head trauma were studied with magnetic resonance imaging (MRI). Patients varied from those with mild injury without any focal neurological deficit to those with severe injury with post-traumatic coma. Altogether, 177 lesions were demonstrated by MRI in 123 of 177 patients within 3 days of injury using T2-weighted (SE2000/40,2000/111) and T1-weighted (IR1500/500/40) multislice sequences. In contrast, computerized tomography (CT) demonstrated 103 lesions in 90 patients. MRI was superior to CT in the diagnosis of nonhemorrhagic contusions demonstrated as a high-intensity area on T2-weighted imaging. MRI provided some information to evaluate the severity of diffuse axonal injury or to predict delayed traumatic intracerebral hematoma (DTICH).

Acute Disease↗
PubMed1991

Orbital fractures: surface coil MR imaging.

Twenty-six patients with orbital fractures diagnosed with plain radiography and computed tomography were examined with surface coil magnetic resonance (MR) imaging. Fifteen patients had blow-out fractures, and 11 had maxillofacial complex fractures. In all patients with blow-out fractures, the location of the fracture was precisely indicated by the presence of prolapsed orbital fat. Incarceration of the extraocular muscle or orbital fat was correctly diagnosed with MR imaging, which was less sensitive in depicting maxillofacial fractures but was useful in assessment of soft-tissue involvement. Postoperative follow-up MR studies provided valuable information about the cause of motility impairment. While T1-weighted images are useful for the detection of the fracture site, both T1- and T2-weighted images are usually necessary for evaluating soft-tissue lesions. The results of this study indicate that surface coil MR imaging is an important adjunct procedure in the diagnosis and treatment of orbital fractures.

Adolescent↗
PubMed1991

Decrease of cytochrome P-450 having arylhydrocarbon hydroxylase and increase of UDP-glucuronyltransferase glucuronizing phenolic xenobiotics in rat liver nodule.

Microsomal arylhydrocarbon (benzo[a]pyrene) hydroxylase activity in hyperplastic nodules in the livers of rats was decreased by feeding 2-acetylaminofluorene in their diet to 10% of that without 2-acetylaminofluorene feeding. By immunoblotting analysis with the antibodies raised against P-450/B[a]P, which is a form of cytochrome P-450 catalyzing benzo[a]pyrene hydroxylation in liver microsomes of untreated rats, it was shown that P-450/B[a]P content was decreased in the microsomes prepared from the nodular tissues. Microsomal UDP-glucuronyltransferase activity toward phenolic xenobiotics such as 1-naphthol and 4-nitrophenol was increased by 4.5-5.0-fold in the nodular tissues. This increase was inhibited by the addition of antibodies raised against GT-1, a form of UDP-glucuronyltransferase glucuronizing phenolic xenobiotics. Immunoblotting analysis with the antibodies against GT-1 showed that a protein band corresponding to GT-1 was increased in the microsomes from nodular tissues. The increased UDP-glucuronyltransferase also had about 4,000 daltons "high mannose" oligosaccharide(s) like GT-1. The decreases of P-450/B[a]P and increases of GT-1 were observed mainly in nodular foci of the liver tissues. These results indicate that in liver nodules, decreased cytochrome P-450-dependent benzo[a]pyrene hydroxylase activity and increased UDP-glucuronyltransferase activity toward phenolic xenobiotics result from the decrease of the P-450 corresponding to P-450/B[a]P and the increase of the GT corresponding to GT-1.

2-Acetylaminofluorene↗
PubMed1991

[Hypothalamic and pituitary function in brain death].

Hypothalamic and pituitary hormone levels were measured in 56 patients meeting the criteria of brain death proposed by the Japanese Ministry of Welfare. Pituitary hormone releasing tests were carried out in 39 patients. In addition, cerebral angiography and transcranial Doppler (TCD) were performed in 13 and six patients, respectively, just after hormone measurements. Serum hypothalamic and pituitary hormone levels were inconsistently high based on the half life time in the presumed absence of cerebral blood flow shown by angiography. The responses to releasing hormones were normal in 16 patients. TCD detected cerebral blood flow in the middle cerebral artery or ophthalmic artery in three patients who showed non-filling on angiography. Postmortem microscopic examination of the hypothalamus and anterior pituitary lobe revealed normal structure and cells intermingled with lytic changes and necrosis. This series suggests that some part of the hypothalamus and hypophysis may still be alive after brain death, although the function of these regions may be clinically insignificant.

Adolescent↗
PubMed1991

Nitrogen and energy utilization in germ-free and conventional chicks at early stages of growth.

Influence of aging on N and ME utilization in germ-free and conventional (CV) chicks was investigated at Stage 1 (2 to 6 days old) and Stage 2 (10 to 14 days old). Chicks were fed diets for ad libitum consumption with protein concentrations of 116, 220, or 445 g/kg diet. The N utilization was not affected by the gut microflora at either stages, but it significantly decreased for chicks on the high-protein diet compared with those on the low-protein and adequate-protein diets. The ME values of diets were not influenced by treatments, except for the high-protein diet at Stage 1, in which ME was significantly reduced.

Animals↗