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Biomedical subjects

Y Katayama

Publications and source records attributed to Y Katayama.

At least 595 records · Page 33Linked to original sources
PubMed1990

Dietary intake and habits of Japanese renal stone patients.

The daily consumption of various nutrients as well as the daily habits of 241 male stone patients were investigated. Hypercalciuric (300 mg. or more per day) calcium stone patients ingested much more total protein, fats, oils and calcium than normocalciuric calcium stone patients, and uric acid stone patients ingested much more total and animal protein, and carbohydrates than calcium stone patients. However, the amount of ingested calcium by the patients (470 mg.) was similar to that of age-matched healthy male subjects (476 mg.) and did not reach the level of the daily nutritive requirements (600 mg.). The patients ingested large amounts of nutrients, especially animal protein, during the evening meal. From these results it was believed that synthetic dietary management, including not only ingesting various amounts of nutrients but also changing dietary habits, is necessary for the prophylaxis of renal stones.

Adult↗
PubMed1990

Spinal cord responses to feline transcranial brain stimulation: evidence for involvement of cerebellar pathways.

The physiological characteristics of spinal cord responses recorded from the spinal epidural space of the cat to transcranial brain stimulation were studied, in comparison with the spinal cord responses to direct stimulation of the motor cortex or cerebellum. The conduction velocity of the initial wave of the responses to transcranial brain stimulation (122.3 +/- 16.3 m/sec mean +/- SD, n = 5) was much faster than the conduction velocity of the initial wave of the responses to motor cortex stimulation (68.3 +/- 14.7, n = 5) and similar to the conduction velocity of the initial wave of the responses to cerebellar stimulation (120.2 +/- 16.2, n = 5). Furthermore, the conduction velocity of any component in the subsequent polyphasic waves at any intensity was not similar to the conduction velocity of the initial wave of the responses to motor cortex stimulation. All components of the responses to motor cortex stimulation disappeared after intercollicular transection. In contrast, the initial wave of the responses to cerebellar stimulation and transcranial brain stimulation remained unaffected by intercollicular transection. The initial wave caused by anodal transcranial brain stimulation was eliminated by ablation of the cerebellum. However, cathodal transcranial brain stimulation sometimes can produce an initial wave that can be eliminated only by transection at the medullospinal junction. The initial wave of the responses to cerebellar stimulation was largest in amplitude when the vicinity of the dentate nucleus was stimulated. These results suggest that responses to activation of the cerebellum, rather than corticospinal neurons arising from the motor cortex, represent a major component of the spinal cord responses to transcranial brain stimulation in cats. The data obtained indicate that it is difficult to activate the motor cortex selectively by transcranial brain stimulation in cats.

Animals↗
PubMed1990

Quantitative evaluation of hemiparesis with corticomyographic motor evoked potential recorded by transcranial magnetic stimulation.

Corticomyographic motor evoked potentials (MEP) activated by transcranial magnetic stimulation of the motor cortex provide clinicians with an opportunity to evaluate corticospinal motor systems quantitatively and noninvasively. Threshold, amplitude, and latency of the corticomyographic MEP, however, are variable between subjects mainly because current directions and intensities induced by magnetic stimulation cannot be determined precisely due to anatomical variations of subjects. The variability of corticomyographic MEPs has limited the use of corticomyographic MEP for evaluating mild changes in corticospinal motor function. In the present study, we used an internal standard to assess hemiplegia, expressing relative amplitude, latency, and threshold of responses on the paretic side as a function of responses elicited from the intact side (%MEP). Neurological function of paretic muscles, as determined by a muscle maneuver test (MMT), clearly correlated to %MEP threshold, amplitude, and latency. Since corticomyographic MEP are similar when recorded from symmetrical sites on two extremities of normal subjects, %MEP provided a sensitive measure of mild hemiparesis. The %MEP approach revealed abnormal MMT scores of 3 or 4 more frequently than did standard MEP approaches. %MEP amplitude was more sensitive to mild hemiparesis than %MEP latency or %MEP threshold. Since magnetic stimulation with a safe intensity range cannot reliably produce corticomyographic MEP in severely paretic muscles with MMT scores of 2 or less, the MEP appears to be most useful for evaluating mild hemiparesis. This technique should expand significantly the clinical usefulness of corticomyographic MEP in neurosurgical practice.

Adolescent↗
PubMed1990

Regulation of activity of an ATP-dependent protease, Clp, by the amount of a subunit, ClpA, in the growth of Escherichia coli cells.

The activity of an ATP-dependent protease, Clp, was examined in Escherichia coli SG1110 (lon-) in various growth phases. The ATP-dependent proteolytic activity (Clp activity) in a crude extract of the cells changed with the growth phase. Cells in the early exponential growth phase showed the lowest activity, but then the activity increased dramatically with cell growth. The highest Clp activity was found in the cells in the late exponential and early stationary phases, however, the activity returned to the original level on prolonged culturing. These changes in Clp activity were closely correlated to the amount of one of the components of Clp, Clp A, which was quantitated immunochemically with antibodies against the Clp A protein. However, the amount of the other component of Clp, Clp P, did not change with the growth phase. These results suggest that the activity of Clp in the cells is regulated by the amount of Clp A in various growth phases. We next examined the effect of the cellular ATP level on Clp activity, because ATP is a cofactor for Clp protease in vitro. The addition of dinitrophenol (DNP) and sodium azide reduced the intracellular concentration of ATP, but had no effect on the Clp activity or the level of the Clp A protein when these drugs were added to the culture at the stationary phase. On the other hand, these drugs elevated both the Clp activity and the Clp A amount in exponentially growing cells, whose cellular ATP level was also reduced.(ABSTRACT TRUNCATED AT 250 WORDS)

ATP-Dependent Proteases↗
PubMed1990

Paracoccus kocurii sp. nov., a tetramethylammonium-assimilating bacterium.

A new species of tetramethylammonium-assimilating bacteria was isolated from an activated sludge which was used for the treatment of tetramethylammonium hydroxide contained in the wastewater from semiconductor manufacturing processes. Cells of the bacteria were gram-negative, nonmotile, short rods (0.5 to 0.8 micron by 0.7 to 1.1 microns). The major respiratory quinone component of the bacteria was Q-10. The G + C content was 71 mol%. Isolates are mesophilic and assimilate methylated amines such as tetramethylammonium, trimethylamine, dimethylamine, and methylamine under neutral conditions. The isolates resemble Paracoccus species with respect to morphology but were distinguishable from the known species of the genus. We propose Paracoccus kocurii sp. nov. The type strain is strain B (= JCM 7684).

Benzoquinones↗
PubMed1990

Synergistic activation by serotonin and GTP analogue and inhibition by phorbol ester of cyclic Ca2+ rises in hamster eggs.

1. Synergistic activation of a GTP-binding protein (G protein) by external serotonin (5-hydroxytryptamine, 5-HT) and internally applied guanosine-5'-O-(3-thiotriphosphate (GTP gamma S) in hamster eggs was demonstrated by the facilitation of repetitive increases in cytoplasmic Ca2+ as measured by their associated hyperpolarizing responses (HRs) and by aequorin luminescence. 2. Rapid application of 70 nM-5-HT caused a single HR of 10-12 s duration and with a delay of 80 s. The critical concentration of 5-HT to cause an HR was 50 nM. 3. With 10 microM-5-HT four to six HRs were often elicited with a delay to the first HR of 8-30 s. HRs disappeared after prolonged or repeated application of 5-HT, indicating an apparent desensitization. 4. 5-HT-induced HRs were completely inhibited by the protein kinase C (PKC) activator phorbol 12-myristate 13-acetate (TPA) (100 nM). Conversely, the PKC inhibitor sphingosine (2 microM) enhanced the series of HRs by shortening the delay to the first HR (3-9 s) and by causing more HRs. 5. Ionophoretic injection of GTP gamma S into the egg usually produced a large HR with a delay of 120-240 s followed by a series of much smaller HRs. When 5-HT was applied within 1 min of injection of GTP gamma S. 70 nM-5-HT induced a number of large HRs and even 1 nM-5-HT could induce HR(s). In contrast, when 5-HT was applied after the size of GTP gamma S-induced HRs had declined, as much as 10 microM-5-HT could only elicit a single large HR. Thus, GTP gamma S apparently caused a sensitization and then a desensitization of the action of 5-HT. 6. GTP gamma S-induced Ca2+ transients were facilitated when injected in the presence of 5-HT concentrations as low as 0.1 nM. The time delay to the first HR was 65 s in 0.1 nM-5-HT or 4 s in 100 nM-5-HT whereas it was 170 s without 5-HT (mean values). The magnitude as well as frequency of HRs succeeding the first HR was enhanced by 5-HT at concentrations above 0.01 nM. 7. TPA (100 nM) blocked the GTP gamma S-plus-5-HT-potentiated HRs after the first four to five HRs. Sphingosine (2 microM) augmented the series of HRs.(ABSTRACT TRUNCATED AT 400 WORDS)

Aequorin↗
PubMed1990

[The antitumor activity of Lactobacillus casei--the direct effects of L. casei to human tumor cell lines].

The effects of somatic components of Lactobacillus casei (L. casei) were studied on cell growth in vitro. L. casei was able to suppress the growth of MT-2, MT-4 cells from adult T-cell leukemia, Molt-4 cells from acute lymphoblastic leukemia and U-937 cells from promonocytic leukemia. This effect was obviously different from the cytotoxicity of Vinbrastin, an anti-cancer drug. Flow cytometric experiments employing BrdU-anti BrdU antibody demonstrated an increase of cells in G1 + G0 phases (pre-DNA synthesis phases) by the treatment of L. casei, therefore L. casei maybe acts as a low grade inhibitor of the protein synthesis. PC-treated L. casei had no more inhibition on cell growth than the non-treated one.

Cell Cycle↗
PubMed1990

Role of penicillinase plasmids in the stability of the mecA gene in methicillin-resistant Staphylococcus aureus.

The stability of methicillin resistance (Mcr) in three independent clinical isolates, MR108, MR6, and MR61, of methicillin-resistant Staphylococcus aureus (MRSA) was studied. The Mcr phenotype was stably maintained in the progeny of all three MRSA clones carrying penicillinase plasmids. However, when the clones were tested after elimination of the plasmids, methicillin-susceptible (Mcs) subclones appeared at various frequencies. Seven Mcs subclones were classified into two groups based on their stabilities. Five Mcs subclones, which were derived from homogeneous strains MR108 and MR61, were stably susceptible. They lost penicillin-binding protein 2' production, and moreover, the mecA gene was deleted in four of five subclones. Two subclones were derived from heterogeneous strain MR6. They were very unstable, and more than half of their progeny were Mcr revertants. However, the remainder were stably Mcs and had lost penicillin-binding protein 2' and the mecA gene. We propose that penicillinase plasmids, which are present in most MRSA strains, play an important role in the stability and phenotypic expression of the mecA gene.

Blotting, Southern↗
PubMed1990

Molecular cloning of the protocatechuate 4,5-dioxygenase genes of Pseudomonas paucimobilis.

We determined the nucleotide sequence of a 1.9-kilobase fragment of Pseudomonas paucimobilis SYK6 chromosomal DNA that included genes encoding protocatechuate 4,5-dioxygenase, the enzyme responsible for the aromatic ring fission of protocatechuate. Two open reading frames of 417 and 906 base pairs were found that had no homology with previously reported sequences, including those encoding protocatechuate 3,4-dioxygenase. Since both open reading frames were indispensable for the enzyme activity, they should encode the subunits of protocatechuate 4,5-dioxygenase. We named these genes ligA and ligB. Protocatechuate 4,5-dioxygenase was efficiently expressed in Escherichia coli with the aid of the lac promoter, and the polypeptides of the ligA and ligB gene products were identified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and amino acid sequencing.

Amino Acid Sequence↗
PubMed1990

Effects of interstitial edema on brain cell transplantation.

Fetal raphe cells were transplanted into the anterior part of the corpus callosum of serotonin denervated hydrocephalic rats using a cell suspension method. Hydrocephalus was induced by intracisternal injection of kaolin. The survival of the transplanted cells and fiber outgrowth were evaluated according to the level of serotonin and its metabolite, hydroxyindoleacetic acid, using high-performance liquid chromatography with electrochemical detection in the anterior and posterior parts of the corpus callosum 1-2, 5-6, and 7-8 weeks after transplantation. The results suggest favorable effects of interstitial edema associated with hydrocephalus on the survival of transplanted raphe cells and fiber outgrowth.

Animals↗
PubMed1990

Inhibitory effect of glutamic acid and aspartic acid on calcium oxalate crystal formation.

The effects of Glu and Asp on calcium stone formation was evaluated in three experiments. Studies using mixed suspension, mixed product removal crystallization and scanning electron microscopy showed that Glu and Asp inhibited the nucleation rate, growth rate and suspension density (crystal mass produced) in proportion to the concentration. The main amino acids in calcium oxalate stones and calcium phosphate stones were Glu and Asp. However, the main amino acids in uric acid stones were glycine and urea, and there were no specific amino acids in struvite stones. The activity of urinary GOT and GPT, which convert Asp and alanine, respectively, to Glu in normal subjects was significantly greater than in calcium stone formation.

Aspartic Acid↗
PubMed1990

Role of platelets as a factor aggravating cerebral ischemia.

In order to clarify the role of platelets as a factor aggravating cerebral ischemia, an experimental model of ischemia was investigated using thrombocytopenic rats. In addition, the prostacyclin derivative (OP-41483) and the thromboxane A2 synthetase inhibitor (OKY-046), both of which inhibit platelet aggregation, were tested for possible beneficial effects on cerebral ischemia. Cerebral ischemia was produced in spontaneously hypertensive male rats using bilateral common carotid artery ligation (BLCL). Thrombocytopenia was produced with an antiplatelet antiserum which reduced the platelet count to less than 6 x 10(4)/microliters by 24 h. OP-41483 was administered four times hourly (500 ng/kg x 4, i.p.), beginning 1 h prior to BLCL. Similarly, OKY-046 was injected four times hourly (10 mg/kg x 4, i.p.). Brain metabolites such as ATP, lactate and pyruvate and water content were determined after 3 h of cerebral ischemia. Brain levels of ATP in the ischemic rats with thrombocytopenia were higher than those of the ischemic rats without thrombocytopenia. In addition, thrombocytopenia reduced the increase of lactate and water content in the ischemic brain. Animals treated with OP-41483 also maintained higher levels of ATP and lower levels of lactate and water compared to animals given a vehicle. OKY-046 significantly reduced brain water content, but had no effect on the ischemic alteration of brain metabolite levels. These results indicate that platelets play an important role in the progression of metabolic change during ischemia.

Adenosine Triphosphate↗
PubMed1990

Massive increases in extracellular potassium and the indiscriminate release of glutamate following concussive brain injury.

An increase in extracellular K+ concentration ([K+]c) of the rat hippocampus following fluid-percussion concussive brain injury was demonstrated with microdialysis. The role of neuronal discharge was examined with in situ administration of 0.1 mM tetrodotoxin, a potent depressant of neuronal discharges, and of 0.5 to 20 mM cobalt, a blocker of Ca++ channels. While a small short-lasting [K+]c increase (1.40- to 2.15-fold) was observed after a mild insult, a more pronounced longer-lasting increase (4.28- to 5.90-fold) was induced without overt morphological damage as the severity of injury rose above a certain threshold (unconscious for 200 to 250 seconds). The small short-lasting increase was reduced with prior administration of tetrodotoxin but not with cobalt, indicating that neuronal discharges are the source of this increase. In contrast, the larger longer-lasting increase was resistant to tetrodotoxin and partially dependent on Ca++, suggesting that neurotransmitter release is involved. In order to test the hypothesis that the release of the excitatory amino acid neurotransmitter glutamate mediates this increase in [K+]c, the extracellular concentration of glutamate ([Glu]c) was measured along with [K+]c. The results indicate that a relatively specific increase in [Glu]c (as compared with other amino acids) was induced concomitantly with the increase in [K+]c. Furthermore, the in situ administration of 1 to 25 mM kynurenic acid, an excitatory amino acid antagonist, effectively attenuated the increase in [K+]c. A dose-response curve suggested that a maximum effect of kynurenic acid is obtained at a concentration that substantially blocks all receptor subtypes of excitatory amino acids. These data suggest that concussive brain injury causes a massive K+ flux which is likely to be related to an indiscriminate release of excitatory amino acids occurring immediately after brain injury.

Animals↗
PubMed1990

[Effects of speaking tube in patients with dysacousis].

Comparative study was made between the conventional speaking tube and the modern electric hearing aid. The results revealed that the conventional speaking tube was inferior to the electric hearing aid in terms of specificity to various frequencies, advantages and understanding of singular syllables, but almost equal to the latter in terms of understandings of three syllables. Actual comparison by listening with both revealed a face that the speaking tube was more acceptable than the hearing aid in terms of naturalness of voice heard with it. It was assumed that the advantages of the speaking tube like this may be attributable to the less sense closure of eyes as it had an open end and consequently to the better hearing through the speaking tube, which may have made better understandable conversation.

Evaluation Studies as Topic↗
PubMed1990

[Clinical studies on thirty-two cases of childhood urolithiasis].

We evaluated 32 patients with urinary calculi under 16 years of age over the past 14 years since the founding of the Department of Urology, Kinki University School of Medicine. They comprised 0.8% of the total urolithiasis patients. They consisted of 18 boys and 14 girls with a male-to-female ratio of 1.29. The average age was 8.7 years for boys and 10.4 years for girls without any marked peak. The most frequently chief complaint was hematuria which was present in 15 cases (47%). Although pyuria was seen in seven cases (22%), urinary bacterial culture was positive only in 5. The underlying diseases could be diagnosed in 13 cases (41%), of which eight cases (62%) developed metabolic disorder. The sites of calculi were determined in 29 cases (91%), of which 28 had stones in the upper urinary tract. Surgical treatment was performed on 16 cases in 17 sessions. Ureterolithotomy was done in as many as five cases, followed by pyeloplasty in four cases. Nephrectomy was performed in only one case. There was only one case which had been treated with extracorporeal shock-wave lithotripsy (ESWL). The composition of calculi was found in 21 cases (66%), the majority or 13 cases (57%) of which had calcium-containing stones. Nevertheless, there was no case of hypercalciuria. When compared to the previous reports in Japan, it was worthy of note that calculi in the upper urinary tract and calcium-containing stones had higher incidences. It is expected that more patients will be treated with ESWL in the future.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1990

[Effects and side effects of ureteral stenting during extracorporeal shock wave lithotripsy].

We retrospectively studied the effects and side effects of placing indwelling ureteral stents in 196 cases who underwent extracorporeal shock wave lithotripsy with a ureteral stent. The average period of ureteral stenting was approximately 22 days. Placing ureteral stents was mainly for large renal stones (79.3%), single kidney etc. There were no significant differences between the stunted and non-stunted patients with approximately 2 cm sized single renal stone with respect to the stone free rate, stone free period, and symptoms during stenting, which suggested that ureteral stenting might be unnecessary in those patients. High fever was highest in incidence of the symptoms and complications during stenting (17.2%). It occurred frequently in patients with infected stones or cystine stones. The percentages of pyrexia and stone street in patients using Towers type's stents were higher than those using the others. It was also shown that the bladder portions of the stents in patients using Towers peripheral ureteral stents were densely encased in calculous material and were very brittle. Fortunately the ureteral portions were removed intact. This study suggests that use of an indwelling ureteral stent may not contribute to the higher rate of being free of stones after the treatment of small to medium sized renal calculi, and that stents should be removed or changed early.

Adolescent↗