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Biomedical subjects

Y Katayama

Publications and source records attributed to Y Katayama.

At least 577 records · Page 32Linked to original sources
PubMed1991

[Clinical evaluation of platelet antagonists on the ex vivo inhibitory effects of platelet aggregation].

It is necessary in clinical to establish the effects of new substances for the primary and secondary prevention of thrombotic illnesses. We measured maximum aggregation after addition of collagen (F.C. 1.7 micrograms/ml) or ADP (F.C. 1.7 mumol/l) in 41 patients without drug treatment, 91 with ticlopidine, 22 with aspirin (ASA); 82-750 mg, 13 with ASA 81 mg, 20 with ticlopidine 100 mg and ASA 81 mg, 13 with cilostazol, 25 with flurbiprofen, 19 with nifedipine and evaluated the ex vivo effect of platelet antagonists. ASA inhibited remarkably collagen-induced platelet aggregation compared with other drugs, but there was significant (p less than 0.01 for 0.5 mumol/l ADP; p less than 0.02 for 1.0 mumol/l ADP) increase of primary aggregation induced by low dose of ADP in 14 healthy volunteers. While ticlopidine only significantly reduced ADP-induced platelet aggregation and we couldn't find dose dependency of ticlopidine (100-300 mg/day) on inhibitory effects of ADP or collagen-induced platelet aggregation. Our results indicate that the administration of one tablet of aspirin for pediatrics (aspirin 81 mg/tab) together with ticlopidine 100 mg is suitable for reduction of platelet aggregation.

Adenosine Diphosphate↗
PubMed1991

[Clinical significance of creatine kinase isoform assay by a new reagent based on immunoinhibition method].

Clinical significance of creatine kinase (CK) isoform assay by a new diagnostic reagent based on immunoinhibition method was evaluated. In the method, a monoclonal antibody (CKM-G 01), which inhibits MM3 but not MM1 isoform, was used. Serial serum samples from 143 acute myocardial infarction (AMI) patients were examined in hospitals. Isoform ratio (I.R.: defined as follows; inhibited CK activity/uninhibited CK activity) increased most rapidly (whose peak appeared 8.5 h after onset of AMI), compared with total CK (18.3 h) and CK-MB (16.1 h). In 61 patient samples collected within 4 h from onset, I.R. in 25 samples (41%) exceeded reference interval, whereas total CK in only 17 samples (28%) did it. Reference interval of the I.R. was 0.42 +/- 0.33 (mean +/- SD) in 1,246 normal subjects. These results show that the assay of CK isoforms by the reagents based on immunoinhibition method is useful for earlier detection of AMI.

Antibodies, Monoclonal↗
PubMed1991

[Analyses of creatine kinase isoforms to detect early diagnosis of reinfarction and reperfusion after acute myocardial infarction].

The detection of reinfarction and reperfusion of the acute myocardial infarction (AMI) in the early phase was studied by monitoring the 34 AMI patients of their changes in creatine kinase (CK, EC 2.7.3.2) isoforms level. CK isoform was assayed by immunoinhibition method using monoclonal antibody. The increased ratio of serum CK-MM3/CK-MM1 after the onset was observed earlier than conventional serum parameters such as CK-MB, CK-MM3, PK and LD and it was almost the same as myoglobin in both reperfused and non-reperfused patients. The increased ratio of CK-MM3/CK-MM1 in reperfusion group was gradually reduced after 5 hours of onset earlier and lowered to reference level two to three times more rapidly than in non-reperfusion group. The ratio of serum CK-MM3/CK-MM1 with AMI increased much more sharply compared to that of after hard exercise. Therefore, monitoring the ratio of patients serum CK-MM3/CK-MM1 with AMI (at serial times, or periodically, or every 3 hours, etc.) is significant for clinical diagnosis.

Aged↗
PubMed1990

Sequence and structure of Clp P, the proteolytic component of the ATP-dependent Clp protease of Escherichia coli.

The ATP-dependent Clp protease of Escherichia coli contains two dissimilar components: the Clp A regulatory polypeptide, with two ATP binding sites and intrinsic ATPase activity, and the Clp P subunit, which contains the proteolytic active site. The DNA sequence of the clpP gene predicts a protein of 207 amino acids (Mr 21,679), which is in close agreement with the size determined by sodium dodecyl sulfate-gel electrophoresis of purified Clp P. Clp P has a native Mr of approximately 240,000, and electron micrographs of the protein show superimposed disk-like structures with a central cavity, similar in appearance to purified proteasomes from eukaryotic cells. Clp P is synthesized with a 14-amino acid leader which is rapidly cleaved in vivo to yield the 193-amino acid protein which has activity in vitro. The clpP gene is at 10 min on the E. coli map, close to that for the ATP-dependent Lon protease of E. coli and far from the gene for clpA. Primer extension experiments indicate that transcription initiates immediately upstream of the coding region for Clp P, with a major transcription start at 120 bases in front of the start of translation. Insertion mutations in clpP have been isolated and transferred to the chromosome; strains devoid of Clp P are viable in the presence or absence of Lon protease. Mutations in clpP stabilize the same Clp A-beta-galactosidase fusion protein specifically stabilized by clpA mutations, providing the first genetic evidence that Clp A and Clp P act together in vivo.

ATP-Dependent Proteases↗
PubMed1990

Oedema fluid formation within contused brain tissue as a cause of medically uncontrollable elevation of intracranial pressure: the role of surgical therapy.

In patients with focal cerebral contusions, medical therapies have generally been advocated unless haemorrhages significantly contributing to the elevated intracranial pressure (ICP) exist. We report here several lines of clinical evidence which indicate that (1) enormous amount of extracellular oedema fluid is formed within contused brain tissue, (2) the formation of extracellular oedema fluid within contused brain tissue alone can be a cause of medically uncontrollable elevation of ICP and (3) surgical excision of the contused brain tissue provides excellent control of the elevated ICP in such patients. The excision of contused brain tissue appears to be the only therapy currently available to alleviate the formation of extracellular oedema fluid in cerebral contusions. We believe that, if ICP is elevated primarily by extracellular oedema due to cerebral contusions and the elevated ICP is medically uncontrollable, surgical excision of contused brain tissue should be carried out without delay regardless of the size of associated haemorrhages.

Body Fluids↗
PubMed1990

The increase in local cerebral glucose utilization following fluid percussion brain injury is prevented with kynurenic acid and is associated with an increase in calcium.

Immediately following a lateral fluid percussion brain injury, the cerebral cortex and hippocampus ipsilateral to the percussion show a marked accumulation of calcium and a pronounced increase in glucose metabolism. To determine if this increase in glucose metabolism was related to the indiscriminate release of the excitatory amino acid (EAA) glutamate, kynurenic acid (an EAA antagonist) was perfused into the cerebral cortex through a microdialysis probe for 30 min prior to injury. The results show that adding kynurenic acid to the extracellular space prior to trauma prevents the injury-induced increase in glucose utilization. These results indicate that calcium contributes to the ionic fluxes that are typically seen following brain injury and supports the concept of an increased energy demand upon cells to drive pumping mechanisms in order to restore membrane ionic balance.

Animals↗
PubMed1990

Cellular swelling during cerebral ischaemia demonstrated by microdialysis in vivo: preliminary data indicating the role of excitatory amino acids.

When rapid cellular swelling occurs, water moves from the extracellular space (ECS) into the cells and the concentration of ECS markers which do not move into the cells increases. Cellular swelling during cerebral ischaemia has therefore been demonstrated in vivo as an increase in ECS markers which is measurable with intracerebral electrodes. We attempted to detect the cellular swelling by brain microdialysis employing a similar principle. Dialysis probes were placed in the hippocampus, and perfused for 20 min with 14C-sucrose as an ECS marker. The probes were subsequently perfused without 14C-sucrose and the dialysate concentration of 14C-sucrose was determined at 1-min intervals. The dialysate concentrations of 14C-sucrose suddenly became elevated 1-3 min after the onset of cerebral ischaemia, indicating the occurrence of cellular swelling. The present technique is useful because it enables the mechanism of cellular swelling to be analyzed by observing the effects of pharmacological agents administered through a dialysis probe. Preliminary data indicating the role of excitatory amino acids in producing cellular swelling during cerebral ischaemia are presented as an example.

Amino Acids↗
PubMed1990

Survival and fibre outgrowth of neuronal cells transplanted into brain areas associated with interstitial oedema.

The influence of interstitial oedema on the survival of fetal raphe cells transplanted into serotonin (5-HT)-denervated rats and the fibre outgrowth from these cells was investigated. Fetal raphe cells were transplanted into the corpus callosum in which long-lasting interstitial oedema had been induced by intracisternal kaolin injection. The 5-HT and 5HIAA levels in the corpus callosum were restored to their maximum within 5-6 weeks post-transplantation regardless of whether interstitial oedema was induced or not. Furthermore, it was appeared that the presence of interstitial oedema even facilitated fibre growth as demonstrated by the 5-HT immunohistochemistry and the restoration of the 5-HT and 5-HIAA levels in brain areas distant from the transplantation sites. These results imply favourable effects of interstitial oedema on the survival of transplanted raphe cells and their fibre outgrowth.

Animals↗
PubMed1990

Early cellular swelling in experimental traumatic brain injury: a phenomenon mediated by excitatory amino acids.

Early cellular swelling following fluid-percussion brain injury was demonstrated in vivo by means of microdialysis in the rat. When rapid cellular swelling occurs, water moves from the extracellular space (ECS) into the cells and the extracellular concentration of ECS marker which does not move into the cells increases. Cellular swelling was therefore demonstrated in vivo as an increase in the dialysate concentration of 14C-sucrose ([14C-sucrose]d) pre-perfused as an ECS marker. The increase in [14C-sucrose]d occurred concomitantly with an increase in the dialysate concentration of K+ ([K+]d) representing large ionic fluxes. The increases in [K+]d and [14C-sucrose]d were both inhibited by kynurenic acid, a broad spectrum antagonist of excitatory amino acids (EAAs), which was administered through the dialysis probe. These findings suggest that early cellular swelling following traumatic brain injury is a result of ionic fluxes mediated by EAAs.

Amino Acids↗
PubMed1990

Protective effect of insulin on suppressed electrical activity caused by ouabain in isolated frog retina.

The reduction in amplitude of the a-wave of the frog ERGs in response to light at seven different intensities recorded from isolated frog retinas (Rana catesbeiana) caused by ouabain (10(-5) M) was partially prevented dose-dependently by the insulin pre-treatment (between 6.6 x 10(-8) and 6.6 x 10(-5) M). Inversely, however, the already suppressed a-waves by ouabain could not be recovered by the application of insulin. The preventive effect of insulin pretreatment was also significantly dependent upon the stimulus intensity, but not upon the presence of glucose in the external media. The effect of insulin itself on the amplitude of the a-wave was below significance level over the range of its concentrations employed in the present experiments. It was suggested that this effect of insulin on the a-wave can be explained by assuming that insulin enhanced the Na-K pump activity under its suppressed conditions in visual cell.

Animals↗
PubMed1990

Relationship of plasma and urine composition to recurrence of calcium urinary stones in patients on drug therapy.

Factors relating alterations in plasma and urine composition to recurrence of urinary stones during drug therapy were investigated by using a multiple regression analysis technique. These factors were influenced not only by the efficacy of the drugs but also by other factors (plasma or urinary constituents and overall health of the patients, etc.). In order to study the effect of drug therapy or other treatment on the alteration of plasma and urine constituents, multiple regression analysis is more appropriate than Student's paired t-test which has been used by some workers. These two analytical methods yield different results even if used on the same data.

Adult↗
PubMed1990

Allopurinol and thiazide effects on new urinary stone formed after discontinued therapy in patients with urinary stones.

We treated 87 patients with calcium-containing urinary stones with either allopurinol alone (44 patients) or in combination with thiazide (43 patients) and studied new stone formation before, during, and after the discontinuation of the drug therapy. The number of stones formed were 1.18, 0.24, and 0.13 before, during, and after discontinuation of the drug therapy, respectively, in the patients treated with allopurinol alone and 1.32, 0.20, and 0.09 in those treated in combination with thiazide. No differences were observed in these values and the duration of each observation period between the two groups. Decreases in the incidence of stone formation even after interruption of drug therapy suggested that recurrence-preventive effects observed following administration of these drugs include the effects of medical guidance. However, allopurinol therapy was effective in preventing recurrence in patients with hyperuricosuria.

Allopurinol↗
PubMed1990

Calcium oxalate crystal formation in patients with hyperparathyroidism and hyperthyroidism and related metabolic disturbances.

The crystallization of calcium oxalate in the urine of patients with hyperparathyroidism and hyperthyroidism was studied using a mixed suspension mixed product removal (MSMPR) system. In addition, calcium metabolism in hyperthyroidism and its relationship to urolithiasis was investigated. The urines from all the three groups (normal subjects, hyperparathyroid and hyperthyroid patients) showed reduced nucleation rates and increased growth rates in comparison with the control synthetic urine. The nucleation rate was not significantly different between the three human urine groups, while the growth rate was significantly higher in the hyperparathyroid group compared to the normal and hyperthyroid groups. Crystal volume (suspension density) in the hyperparathyroid group was approximately twice that in the other two groups. Serum and ionized calcium levels in hyperparathyroid patients were higher than in normal subjects, while hyperthyroid patients had levels only slightly higher than those in normal subjects. The hyperparathyroid and hyperthyroid groups differed significantly from the normal group in urinary calcium excretion. These two groups also showed significantly higher levels of serum alkaline phosphatase and urinary hydroxyproline than did the normal group. Although hyperthyroid patients have a calcium metabolism similar to hyperparathyroid patients, the incidence of urolithiasis is no different between hyperthyroid and normal subjects. The results of both crystallization and calcium metabolism in hyperparathyroid patients were not significantly different between those with and without urolithiasis. The result of crystallization was also not significantly different between hyperparathyroid patients with and without hypercalciuria. This study suggests that hypercalciuria alone does not produce urinary stones and that urine from hyperparathyroid patients may contain promotors of calcium oxalate crystallization and calcium stone formation.

Calcium Oxalate↗
PubMed1990

Facilitated growth of transplanted raphe cells in hydrocephalic interstitial edema.

Fetal raphe cells were transplanted into the anterior corpus callosum (CC) of serotonin (5-HT)-denervated hydrocephalic rats. The levels of 5-HT and its metabolite, 5-hydroxyindoleacetic acid (5-HIAA), were measured in the anterior and posterior parts of the CC at 1-2, 5-6, and 7-8 weeks posttransplantation. The 5-HT and 5-HIAA levels in the anterior part were restored to their maximum within 5-6 weeks posttransplantation in both hydrocephalic and nonhydrocephalic rats. In contrast, the 5-HT and 5-HIAA levels in the posterior part continued to increase for the period beyond 5-6 weeks posttransplantation. The longer time course of the restoration in the posterior part may reflect the time for fiber growth from the site of transplantation to remote brain areas. Hydrocephalic rats showed slightly higher levels of 5-HT (154.4%) and 5-HIAA (159.5%) in the anterior part, and markedly higher levels of 5-HT (254.8%) and 5-HIAA (388.7%) in the posterior part at 5-6 weeks posttransplantation, compared with nonhydrocephalic rats. These results imply favorable effects of interstitial edema associated with hydrocephalus on the survival of transplanted raphe cells and fiber outgrowth.

Animals↗
PubMed1990

Clinical effects of prophylactic dietary treatment on renal stones.

From the investigation of the dietary intake and habits of male Japanese renal stone patients we established several general guidelines. Fluid intake should be increased, especially after dinner. Unbalanced diets should be corrected and avoided (the diet should include different types of food, with vegetables being eaten at every meal and an excessive intake of meat should also be avoided). Three meals a day should be eaten and an excessive intake at dinner should be avoided. The interval from dinner until retiring should be extended. By following these individual dietary guidelines the stone recurrence rate in 199 male calcium stone patients who had received individual dietary instruction decreased remarkably compared to that in male calcium stone patients who had not received individual dietary instruction, not only during the period of outpatient visits but also after outpatient visits were discontinued. From these results we conclude that individual dietary management should be the primary measure for the prophylaxis of renal stone disease in Japan.

Adult↗
PubMed1990

The loop-loosening procedure for urination difficulties after Stamey suspension of the vesical neck.

A main complication of an anti-stress urinary incontinence operation in women is postoperative urinary retention or difficulty in urination caused by the urethrovesical junction being suspended too tightly. A total of 7 women who complained of the complication after a modified Stamey operation underwent our procedure in which the suspension loops were loosened to an adequate tension with the patient under local anesthesia. All patients recovered normal voiding without incontinence immediately after the procedure. The Stamey operation uses a nylon loop for suspension of the urethrovesical junction. Therefore, the tightness of the suspension loop can easily be readjusted postoperatively by the procedure, even though initially the suspension of the urethrovesical junction was too tight or too loose. We believe the procedure will enhance the value of the Stamey operation.

Female↗