Biomedical subjects

C Kato

Publications and source records attributed to C Kato.

At least 109 records · Page 6Linked to original sources

PubMed1995

Thermococcus peptonophilus sp. nov., a fast-growing, extremely thermophilic archaebacterium isolated from deep-sea hydrothermal vents.

Two extremely thermophilic archaebacteria, strains OG-1 and SM-2, were isolated from newly discovered deep-sea hydrothermal vent areas in the western Pacific ocean. These strains were cocci, obligately anaerobic Archaea about 0.7-2 microm in diameter. Optimum growth conditions for OG-1 and SM-2 were at 85-90 degrees C (range 60-100 degrees C), pH 6 (range pH 4-8), a NaCl concentration of 3% (range 1-5%), and a nutrient concentration (tryptone plus yeast extract) of 0.2% (range 0.005-5%). Elemental sulfur stimulated the growth rate fourfold. Ammonium slightly stimulated growth. Both tryptone and yeast extract allowed growth as sole carbon sources; these isolates were not able to utilize or grow exclusively on sucrose, glucose, maltose, succinate, pyruvate, propionate, acetate, or free amino acids. OG-1 showed the fastest growth rate within the genus Thermococcus. Growth was inhibited by rifampicin. The DNA G+C content was 52 mol%. Sequencing of their 16S rDNA gene fragment indicated that these isolates belonged to the genus Thermococcus. OG-1 and SM-2 were different than the described Thermococcus species. We propose that OG-1 belongs to a new species: Thermococcus peptonophilus.

Archaea↗

PubMed1995

[An electrophysiological study on the effect of antioxidant drugs against retinal ischemia-reperfusion damage].

The effects of antioxidant drugs on retinal ischemia-reperfusion damage were studied by electroretinograms (ERGs) from reperfused Dutch rabbit eyes. After inducing retinal ischemia by increasing the intraocular pressure (IOP) up to 140 mmHg for 60 minutes, the reperfusion was started by lowering the IOP to the normal level. Mannitol, polyethylene glycol superoxide dismutase (PEG-SOD), or ascorbic acid was administered by drip-infusion to the rabbits immediately after (early group) or 1 hr after (delayed group) the start of reperfusion. Saline, as a control, was administered by the same method as the early group. The a- and b-waves were recorded before the ischemia and during the reperfusion. In the early group treated by each drug, the recovery rates of the b-wave amplitudes at 4 hrs after the start of reperfusion were significantly greater than those in the controls. In the delayed group, the ERG recovery rate in rabbits treated with PEG-SOD was significantly better than in the controls. These results indicated that all these drugs were effective in protecting from the retina from the ischemia-reperfusion damage, and that some antioxidant drugs might be effective even when they were administered after the start of reperfusion.

Animals↗

PubMed1995

[Imaging of infectious and inflammatory foci using 111In-DTPA-IgG].

We performed radionuclide scanning after intravenous administration of 80 MBq of 111In-labeled non-specific polyclonal human immunoglobulin G (111In-DTPA-IgG). Serial scintigrams were acquired at 6, 24, 48, and 72 hr after injection in 10 patients suspected of having inflammation and/or infection. In 5 patients, the results of scintigraphy were verified with intraoperative cultures or biopsy. The values were as follow: sensitivity: 100% (4/4); specificity 50% (3/6); accuracy: 70% (7/10); positive predictive value: 57.1% (4/7); and negative predictive value: 100% (3/3). The results indicate that 111In-DTPA-IgG scintigraphy is certainly a promising method for the detection of inflammation and/or infection.

Adult↗

PubMed1994

High pressure conditions stimulate expression of chloramphenicol acetyltransferase regulated by the lac promoter in Escherichia coli.

Recombinant plasmids with the chloramphenicol acetyltransferase (CAT) structural gene behind several kinds of promoters were tested for expression in Escherichia coli during growth at atmospheric pressure (0.1 MPa) and at high pressure (30 MPa). Expression of the CAT gene from the lac promoter was remarkably activated (approx. 78-fold) by high pressure in the absence of the inducer isopropyl-beta-D-thiogalactopyranoside (IPTG). The stimulation of the CAT activity by the lac promoter at high pressure did not simply result from an increased plasmid copy number, because the CAT activities from the other promoters and beta-lactamase activities were unaffected at high pressure.

Atmospheric Pressure↗

PubMed1994

On the molecular origin of charge heterogeneity of rat liver fatty acid-binding protein (Z-protein).

The occurrence of many charge isoforms is known for rat liver fatty acid-binding protein, and this is the major cause of conflicting data on the characterization of the protein. Recently, M. Li and T. Ishibashi (1992, Arch. Biochem. Biophys. 298, 254-258) clearly demonstrated that some charge isoforms are due to bound fatty acids. We found that acidic fraction (DE-III) of rat liver fatty acid-binding protein contained isoaspartyl-105 protein resulted from deamidation and peptide rearrangement at Asn-105. Since DE-III fraction carries mainly arachidonate, this post-translational modification might modulate binding specificity of fatty acid-binding protein.

Amino Acid Sequence↗

PubMed1994

Arachidonic acid blocks gap junctions between retinal horizontal cells.

Horizontal cells in turtle retinae are electrically coupled via gap junctions, and the input resistances of the cells are too low to be measured. However, intracellular injection of arachidonic acid into horizontal cells caused great increases in the input resistances of the cells, and the cells could be easily polarized by intracellular current injection. The injection of arachidonic acid also caused decrease in light responses of horizontal cells to surround illumination, and blocked dye-couplings with Lucifer Yellow CH. On the other hand, injection of a lipoxygenase inhibitor or a guanylate cyclase inhibitor into horizontal cells suppressed the decoupling effect of arachidonic acid. These findings suggest that lipoxygenase metabolites of arachidonic acid block gap junctions by activating guanylate cyclase.

Animals↗

PubMed1994

[Detection and localization of parathyroid adenomas and hyperplasias in patients with hyperparathyroidism using thallium-201/technetium-99m parathyroid subtraction scintigraphy].

201Tl/99mTc subtraction scintigraphy (TTS) has been recognized as a useful procedure in the preoperative localization of hyperfunctioning parathyroid glands. Ninety-one patients suspected of hyperparathyroidism (HPT) were studied with TTS for the localization of lesions and 59 patients out of those had a neck exploration and parathyroidectomy which allowed for clinical correlation of pathologic findings with the imaging results. The weight of 30 glands of adenoma ranged 0.100 to 11.700 g (1.840 +/- 0.446 g (mean +/- SE)). The weight of 88 glands of hyperplasia ranged 0.025 to 7.000 g (0.623 +/- 0.100 g). Overall sensitivity and specificity were 47% and 54%, respectively. The sensitivity for the adenoma and the hyperplasia was 87% and 33%, respectively. The specificity for them was 57% and 52%. There was significant difference for the detection between adenomas and hyperplasias. TTS is more useful for the localizing diagnosis of parathyroid adenomas than parathyroid hyperplasia in a patient with hyperfunctioning parathyroid state.

Adenoma↗

PubMed1994

[Experimental and clinical studies of frequency domain Butterworth filter and wiener filter on process of radionuclide imaging].

A frequency domain filtering method provides accurate frequency response. In order to provide optimal radionuclide image quality, Butterworth or Wiener filters were applied in the frequency domain. A method is developed to determine automatically their optimal parameters from the power spectra of the object images. Phantom studies showed that proper parameters were derived by this method. Thirty-one cases of multigated cardiac blood-pool images and phantom images modeled on the cardiac images were filtered by 3 x 3 points temporal smoothing, frequency domain Butterworth and Wiener filters. From these images, ejection fractions were calculated and evaluated the correlation between the actual ejection fractions in the phantom study or the values derived from the contrast left ventriculography. The better correlation coefficients were derived with the frequency domain Butterworth filter than with the temporal smoothing. And more desirable correlation coefficients were derived with the frequency domain Wiener filter than with the frequency domain Butterworth filter, especially in the low count studies. Butterworth or Wiener filtering in the frequency domain reduces noise and improves the capacity for quantitative analysis in the radionuclide images.

Female↗

PubMed1994

Intraperitoneal leakage of technetium-99m-DTPA following renal transplantation: a sign of chylous ascites.

UNLABELLED: A 7-yr-old girl developed persistent ascites following renal transplantation. METHODS: Renal scintigraphy periodically performed to monitor renal function of the transplanted kidney showed increased 99mTc-DTPA in the abdominal cavity on delayed imaging. RESULTS: Paracentesis demonstrated a cloudy yellow, odorless fluid which was identified as chylous ascites, an extremely rare complication of abdominal vascular surgery. CONCLUSION: Technetium-99m-DTPA in the peritoneal cavity following renal transplantation should be recognized as a sign suggestive of chylous ascites.

Child↗

PubMed1993

Time-resolved infrared spectral analysis of the KL-to-L conversion in the photocycle of bacteriorhodopsin.

Time-resolved infrared spectra of the hydrated film of light-adapted bacteriorhodopsin were recorded from earlier than 200 ns to 450 microseconds after light excitation in the 1800-900-cm-1 region on a newly designed dispersive-type infrared spectrometer [Iwata & Hamaguchi (1989) Appl. Spectrosc. 44, 1431-1437]. Both the KL-to-L and L-to-M conversions were detected in this time range. The spectral shape of KL is similar to K measured at 77 K except for the intense hydrogen out-of-plane vibrational band at 984 cm-1. The kinetics of this band are different from those of the other KL-specific bands at 1510, 1296, and 956 cm-1. Since the hydrogen out-of-plane vibrational bands are intensified by twists of the polyene chain, a change in the twist of the chromophore is suggested within the lifetime of KL. During the decaying process of L, the KL-specific vibrational bands are observed in parallel with L, indicating that KL and L are in equilibrium.

Bacteriorhodopsins↗

PubMed1993

Molecular cloning, sequencing, and mapping of the gene encoding protease I and characterization of proteinase and proteinase-defective Escherichia coli mutants.

Clones carrying the gene encoding a proteinase were isolated from Clarke and Carbon's collection, using a chromogenic substrate, N-benzyloxycarbonyl-L-phenylalanine beta-naphthyl ester. The three clones isolated, pLC6-33, pLC13-1, and pLC36-46, shared the same chromosomal DNA region. A 0.9-kb Sau3AI fragment within this region was found to be responsible for the overproduction of the proteinase, and the nucleotide sequence of the region was then determined. The proteinase was purified to homogeneity from the soluble fraction of an overproducing strain possessing the cloned gene. N-terminal amino acid sequencing of the purified protein revealed that the cloned gene is the structural gene for the protein, with the protein being synthesized in precursor form with a signal peptide. On the basis of its molecular mass (20 kDa), periplasmic localization, and substrate specificity, we conclude this protein to be protease I. By using the gene cloned on a plasmid, a deletion mutant was constructed in which the gene was replaced by the kanamycin resistance gene (Kmr) on the chromosome. The Kmr gene was mapped at 11.8 min, the gene order being dnaZ-adk-ush-Kmr-purE, which is consistent with the map position of apeA, the gene encoding protease I in Salmonella typhimurium. Therefore, the gene was named apeA. Deletion of the apeA gene, either with or without deletion of other proteinases (protease IV and aminopeptidase N), did not have any effect on cell growth in the various media tested.

Amino Acid Sequence↗

PubMed1993

[Urease test].

In order to elucidate bacterial infection, as a rule, isolated and cultured bacteria of a specimen are identified by their morphologies or biochemical characteristics. However, the culture of Helicobacter pylori (H. pylori) is difficult and takes, much time. Therefore, favorable test results are currently obtained by combining the culture method, histopathologic method, urease test and sero-immunologic test. The merits of the urease test are that judgement is available immediately after endoscopy and that the test is inexpensive. The demerits are that the existence of H. pylori is diagnosed only by estimation that endoscopy is indispensable for the test. When compared with the culture method, the urease test has 91.8% sensitivity and 94.7% specificity and when compared with the histopathologic method, it has 94.4% sensitivity 88.4% specificity. In the future, the clinical requirement will increase for quick investigation on the evidence of H. pylori-induced infection. These results show that urease test is useful because it is simple and allows quick judgement.

Ammonia↗

PubMed1992

Molecular genetic analysis of the catalytic site of Streptococcus mutans glucosyltransferases.

In the present communication molecular genetic approaches have been utilized to confirm the nature of the catalytic site of Streptococcus mutans glucosyltransferases (GTF)s. Site-directed mutagenesis was used to convert the putative sucrose binding Asp-451 of the GTF-I enzyme from S. mutans GS5 to Glu, Asn, and Thr. All three of the resulting mutated enzymes displayed no detectable sucrase or GTF activities. By contrast, mutation of nearby Asp residues did not markedly reduce enzymatic activity. The inactive enzymes also appear to bind acceptor dextrans as well as the parental enzyme. These results confirm the essential role of Asp-451 of the GTF-I from strain GS5 and analogous Asp residues in other related GTFs in enzymatic activity.

Amino Acid Sequence↗

PubMed1992

[Clinical usefulness of exercise/rest 99mTc-teboroxime SPECT imaging: results of a Japanese multi-center phase II study].

99mTc-Teboroxime [Chloro[tris(cyclohexyldioxime)methaneboronic acid] (99mTc)technetium], a perfusion agent for myocardial imaging, has a distinct advantage over 201Tl because of its very high myocardial extraction and is a 99mTc compound ideal for gamma camera imaging. This agent also demonstrates rapid myocardial washout, which allows completion of exercise and rest imaging studies in a short interval (to 1 hour). However, the rapid washout necessitates the completion of image acquisition very quickly after injection and therefore may require nonconventional SPECT imaging. In this Phase II study we evaluate the safety and efficacy of 99mTc-Teboroxime to detect coronary artery disease by exercise and rest SPECT imaging in 38 patients with prior myocardial infarction, 31 patients with angina pectoris, and 4 patients with non-coronary cardiac diseases. The 99mTc-Teboroxime dose used was 370-740 MBq in each study. The findings were compared with coronary angiography or 201Tl exercise and redistribution SPECT. No significant adverse reactions or laboratory abnormalities attributable to 99mTc-Teboroxime were observed. The quality of SPECT images was optimal in 62.5% of all patients. The relatively large population of suboptimal cases (37.5%) was attributed to the delay of the start and prolongation of the image acquisition time. In 85.7% of patients whose imaging was started within 5 minutes and completed within 11 minutes after injection, optimal quality was observed. Thus, 99mTc-Teboroxime SPECT requires the rapid completion of image acquisition after injection to achieve optimal image quality. Abnormalities of 99mTc-Teboroxime distribution were detected in 97.1% and 62.1% of patients with prior myocardial infarction or angina pectoris, respectively. The concordance with coronary angiography was 84.4% and 68.0%, and with 201Tl was 78.1% and 74.1%, respectively. Although standardization of the image protocol suitable for this agent is needed for the next study, these high correlations suggest the potential usefulness of 99mTc-Teboroxime SPECT imaging.

Adult↗

PubMed1991

The carboxyl terminal domain of Streptococcus mutans glucosyltransferases prevents secretion in Escherichia coli.

The extracellular glucosyltransferases (GTFs) of Streptococcus mutans are not secreted into the periplasmic space of Escherichia coli when the corresponding gtf genes are isolated in the latter organism. The utilization of both deletion analysis and gtfB: phoA fusions indicate that the signal sequences of the GTFs are functional in E. coli. However, these results further suggest that amino acid sequences present in the carboxyl terminus of the GTFs inhibit secretion through the cytoplasmic membrane in E. coli.

Alkaline Phosphatase↗

PubMed1991

Molecular basis for the association of glucosyltransferases with the cell surface of oral streptococci.

The expression of Streptococcus mutans mutant glucosyltransferase-I enzymes in S. sanguis and S. milleri suggests that cell-associated glucosyltransferase activity is dependent upon both glucan synthesis and glucan binding by the carboxyl-terminal repeating units of the enzyme. Mutant enzymes lacking these repeating units were only present in the extracellular fluids of these transformed streptococcal strains.

Blotting, Western↗

PubMed1991

Single photon emission computed tomography with Tc-99m-dimercaptosuccinic acid in patients with upper urinary tract infection and/or vesicoureteral reflux.

By means of Tc-99m dimercaptosuccinic acid (DMSA) scintigraphy, an established method for assessing renal cortical damage, we evaluated the pick-up rate for renal defects (scars) by single photon computed tomography (SPECT) and planar images of 10 normal volunteers, and 58 patients (70 scintigrams) with upper urinary tract infections, most of whom had a history of vesicoureteral reflux (VUR). The positive study rate for renal defects depended on the severity of VUR. The overall positive rates for renal cortical defects obtained by DMSA SPECT imaging and DMSA planar imaging were 60% and 43%, respectively, and the difference between these was significant (p less than 0.005). The mean absolute individual renal uptake (/injected dose) at 2 hours post-injection was decreased in kidneys with defects detected by SPECT alone. The positive study rate for intravenous urography (IVU) depended on the grade of VUR and was 15% overall. DMSA SPECT imaging detects renal cortical defects at greater frequency than previously achieved.

Adolescent↗

PubMed1991

Characterization of Ac1-Proteinase from the venom of Agkistrodon acutus (Hundred-pace snake) from Taiwan.

1. Ac1-Proteinase from the venom of Agkistrodon acutus was isolated in a homogeneous form by a previously published method. 2. Ac1-Proteinase possessed lethal, hemorrhagic, caseinolytic, azocaseinolytic, azoalbumin hydrolytic and hide powder azure hydrolytic activities. 3. The toxin also hydrolyzed the oxidized B chain of insulin and fibrinogen. The cleavage sites in the oxidized B chain of insulin were identified as Ala(14)-Leu(15) and Tyr(16)-Leu(17). The A alpha chain of fibrinogen was digested. 4. Biological properties of Ac1-Proteinase were investigated further and are reported in this paper.

Amino Acid Sequence↗