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Biomedical subjects

Y Katayama

Publications and source records attributed to Y Katayama.

At least 487 records · Page 27Linked to original sources
PubMed1993

Elongation of growth cone filopodia observed with video-enhanced differential interference contrast microscopy.

Dynamics of filopodia configuration from growth cones of neurons isolated from the rat central nervous system were analyzed by using video-enhanced differential interference contrast microscopy. Rapid elongation of filopodia from growth cones and dendrites was observed when high K+ Krebs solution was applied to the growth cones. The maximum speed of the elongation was about 1 micron/s. The filopodia suspended in control Krebs solution moved at random. Retraction of the filopodia was observed within a few minutes after high K+ stimulation.

Animals↗
PubMed1993

[Examination of the risk factors for infectious urolithiasis formation in patients receiving urinary diversion or urinary reconstruction using intestine--comparison of reservoir and ileal conduit].

Urinary risk factors and preventive factors for infectious calcium (Ca) urolithiasis formation, such as citrate, oxalate, Ca, phosphate, magnesium, and uric acid were examined more than 2 months after performing a urinary reservoir in 12 patients (R group) and ileal conduit in 10 patients (C group). There was no difference in the positive rate of risk factors between the two groups and also no difference in the positive rate of more than two risk factors between the two groups. Although four patients with more than two risk factors in the R group suffered from reservoir stones all of which included Ca-urolithiasis, none in the C group did. In the R group, the incidence of stone formation in patients with 2 or more risk factors was significantly higher than those in patients with 1 or no risk factor. In conclusion, the urinary reservoir operation should not be carried out in patients with more than two risk factors for urolithiasis formation, and urinary risk factors should be examined before reservoir operation.

Adult↗
PubMed1993

[Effect of surface antigens on granulocytes in phagocytosis].

To analyze phagocytosis mechanism of granulocyte using fluorescent microspheres, changes of phagocytic index, complement receptors, Fc receptors and adhesion molecules on cell membrane, after exogenous stimulation were determined by flow cytometry. The changes of phagocytic index by blocking test was also determined using monoclonal antibodies for receptors. The phagocytic index was decreased by supernatant of S. aureus, and was increased by supernatant of E. coli and phorbol myristate acetate (PMA). By PMA stimulation, surface marker positive cells increased in CR1, IgGFcR2 and decreased in IgGFcR3, LFA-3, Homing receptor, whereas they increased in CR1, IgMFcR, LFA-1 beta and decreased in LFA-3 by the supernatants of S. aureus and E. coli. Blocking test using monoclonal antibodies to individual receptors showed decrease of phagocytic index in CR1, CR3, LFA-1 beta. In this phagocytosis using fluorescent microspheres, the complement receptors were most dedicating in phagocytosis of granulocyte.

Adult↗
PubMed1992

Functioning ovarian carcinoids induce severe constipation.

Five patients with ovarian carcinoid who had severe constipation for a long period preoperatively showed marked reduction of this symptom postoperatively. Because this phenomenon was believed to be caused by some biologically active substance rather than a mechanical effect of the tumor, reactivity to 17 amine and peptide hormones was studied immunohistochemically in these patients. Numerous peptide YY (PYY)-positive cells were detected, with PYY-positive cells representing more than 50% of all carcinoid tumor cells in each patient. PYY, which has a pharmacologic inhibitory action on intestinal motility, was presumably the cause of the constipation in these patients.

Adult↗
PubMed1992

Enduring suppression of hippocampal long-term potentiation following traumatic brain injury in rat.

This study investigated changes in synaptic responses (population spike and population EPSP) of CA1 pyramidal cells of the rat hippocampus to stimulation of the Schaffer collateral/commissural pathways 2-3 h after traumatic brain injury (TBI). TBI was induced by a fluid percussion pulse delivered to the parietal epidural space resulting in loss of righting responses for 4.90-8.98 min. Prior to tetanic stimulation, changes observed after the injury included: (1) decreases in population spikes threshold but not EPSP thresholds; (2) decreases in maximal amplitude of population spikes as well as EPSPs. TBI also suppressed long-term potentiation (LTP), as evidenced by reductions in post-tetanic increases in population spikes as well as EPSPs. Since LTP may reflect processes involved in memory formation, the observed suppression of LTP may be an electrophysiological correlate of enduring memory deficits previously demonstrated in the same injury model.

Animals↗
PubMed1992

Excitatory amino acid antagonist administered via microdialysis attenuates lactate accumulation during cerebral ischemia and subsequent hippocampal damage.

Our previous studies have shown that kynurenic acid (KYN), a broad-spectrum antagonist of excitatory amino acids (EAAs), administered in situ through a dialysis probe can delay the massive ionic fluxes in the rat hippocampus during cerebral ischemia. The present experiments demonstrated that the same procedure attenuates the increase in extracellular concentration of lactate ([lactate]e) during ischemia as measured by microdialysis. This finding suggests that the lactate accumulation is partially caused by a sudden increase in energy demand due to the rapid ionic fluxes through EAA-coupled ion channels. This inference is consistent with the hypothesis that the earlier ionic event during ischemia is a cause of energy depletion, rather than the result merely of energy failure. The present experiments also revealed that KYN administered by the same procedure attenuates death of hippocampal CA1 pyramidal cells after 5-min transient ischemia in gerbils. Since lactate accumulation is likely to be an important factor affecting cell viability, the protective effect of KYN may be attributable, in part, to inhibition of lactate accumulation.

Amino Acids↗
PubMed1992

A thiocyanate hydrolase of Thiobacillus thioparus. A novel enzyme catalyzing the formation of carbonyl sulfide from thiocyanate.

A thiocyanate hydrolase that catalyzes the first step in thiocyanate degradation was purified to homogeneity from Thiobacillus thioparus, an obligate chemolithotrophic eubacterium metabolizing thiocyanate to sulfate as an energy source. The thiocyanate hydrolase was purified 52-fold by steps involving ammonium sulfate precipitation, DEAE-Sephacel column chromatography, and hydroxylapatite column chromatography. The enzyme hydrolyzed 1 mol of thiocyanate to form 1 mol of carbonyl sulfide and 1 mol of ammonia as follows: SCN- + 2H2O----COS + NH3 + OH-. This is the first report describing the hydrolysis of thiocyanate to carbonyl sulfide by an enzyme. The enzyme had a molecular mass of 126 kDa and was composed of three different subunits: alpha (19 kDa), beta (23 kDa), and gamma (32 kDa). The enzyme exhibited optimal activities at pH 7.5-8.0 and at temperatures ranging from 30 to 40 degrees C. The Km value for thiocyanate was approximately 11 mM. Immunoblot analysis with polyclonal antibodies against the purified enzyme suggested that it was induced in T. thioparus cells when the cells were grown with thiocyanate.

Blotting, Western↗
PubMed1992

Early cellular swelling during cerebral ischemia in vivo is mediated by excitatory amino acids released from nerve terminals.

This study demonstrates ischemic cellular swelling in vivo detected as changes in the concentration of 14C-sucrose pre-perfused into the extracellular space (ECS) as an ECS marker. Microdialysis was utilized as a means of perfusion and measurement of the extracellular concentration of 14C-sucrose ([14C-sucrose]e). Concomitant with an abrupt increase in [K+]e at 1-3 min following the ischemia induction, [14C-sucrose]e was also rapidly elevated. Since sucrose is not taken up by either cells or capillaries, the absolute amount of 14C-sucrose in the ECS must be unchanged. The increase therefore appears to represent a relative decrease in water volume in the ECS resulting from a movement of water into the cells, i.e. cellular swelling. Ca(2+)-free perfusate containing Co2+, which has been shown to block excitatory amino acid release during cerebral ischemia, significantly delayed the increase in [14C-sucrose]e and [K+]e. Kynurenic acid, a broad-spectrum antagonist of excitatory amino acids, administered in situ through the dialysis probe also significantly delayed the increase in [14C-sucrose]e and [K+]e. These findings indicate that the early cellular swelling occurring during cerebral ischemia is a result of massive ionic fluxes mediated by excitatory amino acids which are released by a Ca(2+)-dependent exocytotic process from the nerve terminals.

Amino Acids↗
PubMed1992

A homogeneous assay system of aspartate aminotransferase iso-enzymes using proteases and application for clinical evaluation of myocardial infarction.

We designed a rapid, homogeneous assay for human aspartate aminotransferase (AST) isoenzymes, by a selective proteolysis of soluble AST (s-AST), using chymotrypsin and protease 401. The linearity of mitochondrial (m-AST) was elongated up to 4000 U/l. m-AST values from the human liver, and determined by a homogeneous assay using protease 401 or chymotrypsin, were relative to those obtained using an immunoprecipitation method. In perioperative patients or those with an acute myocardial infarction, the peaks of s-AST and m-AST values were noted 13 h and at 57 h after ictus, respectively, whereas the peak of ratio between was seen 6 h after ictus. In the case of Budd-Chiari syndrome, the maximum levels of the two AST activities were evident 14 days after hospitalization and the peak of ratio between them was seen after 7 days. We propose that this homogeneous assay can serve as a diagnostic tool for early phase detection of myocardial infarction and of Budd-Chiari syndrome.

Adult↗
PubMed1992

A new method for determination of urinary citrate.

We have developed a new assay technique using high-performance liquid chromatography. The assay was performed at a flow rate of 0.7 ml/min, a temperature of 60 degrees C and an ultraviolet absorption of 214 nm. Comparison of the results of the new assay with the results obtained for identical samples using the conventional fluorometric method demonstrated a very high correlation coefficient of 0.931.

Adult↗
PubMed1992

Intraparenchymal blood-fluid levels in traumatic intracerebral haematomas.

Blood-fluid levels within the cerebral parenchyma are observed more frequently on CT and MRI in traumatic intracerebral haematomas than in those of other aetiologies. The intraparenchymal blood-fluid interface can be formed without a fluid cavity. It is suggested that the blood-fluid levels represent layering of red blood cells within areas of contusion necrosis as well as extensive contusion oedema. The more extensive the damage to brain tissue, the more often blood-fluid levels formed. A poorer outcome can be therefore predicted when an intraparenchymal blood-fluid interface is seen.

Arteriovenous Malformations↗
PubMed1992

Differential diagnosis of adrenal tumour and upper pole renal tumour by I-131 cholesterol adrenocortical scintigraphy.

A 27-year-old housewife with right hypochondralgia was admitted for treatment of a huge right adrenal or upper pole renal tumour. The tumour measured 10 x 8 x 8 cm and was hypovascular. The main blood supply derived from the right adrenal artery which originated from the abdominal aorta just proximal to the right renal artery. Although several diagnostic imaging studies suggested that the tumour arose from the right adrenal gland, the bilateral adrenal glands were equally visualized on I-131 cholesterol adrenocortical scintigraphy. After surgery and pathological examination, the tumour proved to be a renal cell cancer, while the right adrenal gland was intact. This case demonstrates that adrenocortical scintigraphy is useful in the differentiation of adrenal and renal tumours when a large tumour occupies the upper pole of the kidney or adrenal gland.

Adrenal Gland Neoplasms↗
PubMed1992

Growth of a giant aneurysm following complete thrombosis by detachable balloon occlusion.

A giant basilar artery aneurysm demonstrating growth and causing neurological deterioration even after complete detachable balloon occlusion is reported. Autopsy revealed total thrombosis of the aneurysm and a hemiconcentric, onion skin-like, laminated structure. Numerous vascular channels and multiple fresh intramural hemorrhages were noted within the outer margin of the aneurysmal wall. Repeated intramural hemorrhages appeared to have been responsible for the aneurysmal laminated structure and contributed to progressive aneurysmal growth. This case demonstrates that the growth of some giant aneurysms is not dependent upon the continuity with the parent artery, and progressive enlargement cannot always be prevented by balloon occlusion.

Basilar Artery↗
PubMed1992

Primary Ewing's sarcoma of the temporal bone.

Primary cranial Ewing's sarcoma is exceptionally rare. Only ten cases of such a tumor had been reported heretofore in the literature. We describe a case of primary Ewing's sarcoma occurring in the temporal bone. The tumor was surgically excised, and the patient underwent radiation and chemotherapy. Neither recurrence nor distant metastasis was noted at 12 months after surgery. Although the prognosis of Ewing's sarcoma in general is often poor because of early metastasis to the lungs and/or to other bones, a review of the literature suggested that the same tumor occurring in the cranium can often be successfully managed by intensive therapy with radical excision and radiochemotherapy. This inference was supported by the case reported here.

Adult↗