PubMed Health⌕ Search

Biomedical subjects

C Kobayashi

Publications and source records attributed to C Kobayashi.

At least 55 records · Page 3Linked to original sources
PubMed1999

Pregnancy in women receiving renal dialysis or transplantation in Japan: a nationwide survey.

BACKGROUND: Since a report on the first successful pregnancy of a woman on long-term haemodialysis in Japan in 1977, there has been a growing number of case reports on successful pregnancy in patients on dialysis. We undertook a nationwide survey on pregnancy in women on renal replacement therapy in 1996. METHODS: A preliminary questionaire was sent to 2504 dialysis units and 143 renal transplant units in Japan. For each reported pregnancy, a more detailed questionaire was sent to collect nephrological, obstetric and neonatal information. RESULTS: There were 172 pregnancies (0.44%) reported in 38889 women on dialysis, with 90 successful pregnancies (0.23%), and 194 pregnancies reported in 852 female renal transplant recipients. Detailed pregnancy information was collected from 74 women on dialysis and 194 renal transplant recipients. Of the 74 pregnancies in the women on dialysis, 36 (48.6%) resulted in surviving infants, nine (12.2%) in neonatal death, nine (12.2%) spontaneous abortions and 14 (18.9% elective abortions were reported. The outcome of six pregnancies (8.1%) was unknown. Of 194 pregnancies in renal transplant recipients, 159 (82.0%) resulted in surviving infants, two (1.4%) in neonatal death and 28 (14.4%) in spontaneous or elective abortion. In five cases the pregnancy outcome was not reported. No congenital anomalies were reported, except two infants with mental retardation and one with epilepsy. CONCLUSION: The current survey revealed that the rate of successful pregnancy in women on dialysis has improved. More than half of the pregnancies resulted in infant survival. But, premature birth is a major problem for the children of women on dialysis and there is a higher rate of neonatal death. There are significant differences in gestational age, birth weight, frequency and severity of prematurity and rates of neonatal death between pregnancies of women undergoing dialysis and those who are renal transplant recipients.

Adolescent↗
PubMed1999

Live virulent Rhodococcus equi, rather than killed or avirulent, elicits protective immunity to R. equi infection in mice.

Mice inoculated intravenously with a sublethal dose of live virulent Rhodococcus equi ATCC 33701 that contained an 85-kb virulence plasmid were immune to a lethal intravenous challenge of ATCC 33701. This immunity depended upon the dose of immunization and developed rapidly: mice primed with 10(5) live ATCC 33701 eliminated the challenged bacteria more rapidly than mice primed with doses ranging from 10(2) to 10(4) bacteria, and mice given 10(5) live ATCC 33701 intravenously withstood the lethal challenge as early as 5 days after the initial inoculation. However, this protective immunity did not develop in mice immunized with doses of heat-killed ATCC 33701 ranging from 10(6) to 10(8), or in mice immunized with doses of live ATCC 33701P-, a plasmid-cured derivative (avirulent), in doses ranging from 10(5) to 10(7). These mice had positive antibody titers against R. equi at the challenge (14 days after priming). Adoptive transfer of resistance to virulent R equi was obtained with spleen cells from mice immunized with live ATCC 33701, but not monoclonal antibody to 15- to 17-kDa virulence-associated antigens. These results revealed that live ATCC 33701P-, a plasmid-cured derivative of virulent R equi, could not elicit protective immunity, and are consistent with previous observations that protective immunity was induced by live virulent, but not killed organisms.

Animals↗
PubMed1998

Affinity purification of Helicobacter pylori urease. Relevance to gastric mucin adherence by urease protein.

A simple, reproducible and high yield method of Helicobacter pylori urease enzyme purification was developed using a heparinoid (Cellufine sulfate) affinity gel. The purification method involved two sequential steps using the same gel that takes advantage of the differential affinity of urease to the heparinoid at two levels of hydrogen ion concentration. SDS-polyacrylamide gel electrophoresis analysis of affinity-purified urease revealed two major protein bands with about 62- and 30-kDa molecular mass. When whole cell lysates of clinical and laboratory strains of H. pylori were probed by Western blot, anti-urease hyperimmune serum produced by affinity-purified urease in rabbit recognized only the two bands corresponding to the urease A and B subunits. To probe the molecular relevance of affinity gel adherence to mucin adherence, the purified urease was derivatized with N-hydroxysuccinimidobiotin and used in adherence assays. Competitive inhibition tests revealed commonality of urease receptors among gastric mucin, heparin, and heparinoid. Composite data on adherence kinetics modulated by pH, salt, incubation time, and concentration of urease or mucin were indicative of conformation-dependent ligand-receptor interaction.

Animals↗
PubMed1998

Lysinuric protein intolerance and systemic lupus erythematosus.

UNLABELLED: We report lysinuric protein intolerance (LPI) and systemic lupus erythematosus (SLE) in a 14-year-old girl. The co-existence of LPI and SLE in the same patient has been reported before and suggests that SLE is directly connected with LPI. CONCLUSION: Possibly in LPI the metabolic derangement can cause immunological abnormalities. Therefore, when multisystem involvement is observed in LPI patients, SLE should be considered as a rare complication.

Adolescent↗
PubMed1998

Overproduction of L-cysteine and L-cystine by Escherichia coli strains with a genetically altered serine acetyltransferase.

Organisms that overproduced L-cysteine and L-cystine from glucose were constructed by using Escherichia coli K-12 strains. cysE genes coding for altered serine acetyltransferase, which was genetically desensitized to feedback inhibition by L-cysteine, were constructed by replacing the methionine residue at position 256 of the serine acetyltransferase protein with 19 other amino acid residues or the termination codon to truncate the carboxy terminus from amino acid residues 256 to 273 through site-directed mutagenesis by using PCR. A cysteine auxotroph, strain JM39, was transformed with plasmids having these altered cysE genes. The serine acetyltransferase activities of most of the transformants, which were selected based on restored cysteine requirements and ampicillin resistance, were less sensitive than the serine acetyltransferase activity of the wild type to feedback inhibition by L-cysteine. At the same time, these transformants produced approximately 200 mg of L-cysteine plus L-cystine per liter, whereas these amino acids were not detected in the recombinant strain carrying the wild-type serine acetytransferase gene. However, the production of L-cysteine and L-cystine by the transformants was very unstable, presumably due to a cysteine-degrading enzyme of the host, such as cysteine desulfhydrase. Therefore, mutants that did not utilize cysteine were derived from host strain JM39 by mutagenesis with N-methyl-N'-nitro-N-nitrosoguanidine. When a newly derived host was transformed with plasmids having the altered cysE genes, we found that the production of L-cysteine plus L-cystine was markedly increased compared to production in JM39.

Acetyltransferases↗
PubMed1997

Thermal conversion from low- to high-activity forms of catalase I from Bacillus stearothermophilus.

Catalase I from Bacillus stearothermophilus has the interesting property of increasing its enzyme activity on heating. It was confirmed that after heating at 70 degrees C for 10 min or 65 degrees C for 20 min, almost all the enzyme molecules were converted irreversibly to the activated form. The increase in kcat from 1400 to 3930 s-1 and the decrease in Km for H2O2 from 4.4 to 2.7 mM by heat activation indicate changes in the kinetic property of the enzyme molecule. Therefore, it follows that catalase I has two active forms, a high-activity form and a low-activity form. The heat activation process followed the first-order kinetics with an activation enthalpy (DeltaH*) of 191 kJ/mol while the heat denaturation process had a DeltaH* of 545 kJ/mol. The CD spectra of the two enzyme forms had small but marked differences. The conversion of the low-activity form to the high-activity form was an endothermic process with a Tm of 56 degrees C, which is much lower than that of the heat denaturation (Tm = 76 degrees C), and the enthalpy change for the transition was only 5% of that for the denaturation. It has to be noted that the high-activity form of the enzyme was converted back to a low-activity form through the process of denaturation, refolding, and reconstitution with heme. In addition, the newly obtained low-activity form was brought to a high-activity form by heating. These results suggest that the native state of catalase I has two active conformations that are roughly the same but not identical and are separated by a high energy barrier.

Calorimetry, Differential Scanning↗
PubMed1997

Field evaluation of chicken egg yolk immunoglobulins specific for bovine rotavirus in neonatal calves.

The oral efficacy of chicken egg yolk immunoglobulins (yIg) specific for bovine rotavirus (BRV) serotypes G6 and G10 in protecting neonatal calves was examined in a herd of cattle under field conditions. In one of the three trials, yIg-treated calves tested under high relative humidity (RH) showed a significantly increased mean body weight (P < 0.05) and a decrease in number of calves shedding high titer of BRV (G6) in stool compared to control calves (P < 0.01), suggesting that our yIg product was effective in a field condition with an epidemic outbreak of BRV diarrhea.

Animals↗
PubMed1997

Penetration of constricted canals with modified K files.

A technique using K files with modified tips has been developed for the penetration of constricted canals. The tip of a #10 K file was sliced diagonally to make it thinner. Because this modified K file has an especially fine tip and an appropriate stiffness, it followed constricted or sharply curved canals well and had a high penetration potential. The author attempted to penetrate to the apical foramen in all 1844 canals of 977 teeth treated from 1987 to 1994. In 263 canals (14.3%) that could not be penetrated with conventional #10 K files, further attempts were made with the modified K files. As a result, the number of the nonpenetrated canals was reduced to 75 (4.1%). There were 7 file breakages and 14 accidental perforations.

Chi-Square Distribution↗
PubMed1997

A new engine-driven canal preparation system with electronic canal measuring capability.

A new cordless engine-driven root canal preparation system has been developed that electronically monitors the location of the file tip and the torque applied to the file during all instrumentation procedures. The Root ZX is mounted inside the handpiece to measure the canal length. The engine is driven with a rechargeable battery, and it works more than 40 minutes without a recharge. Nickel-titanium files are used for this preparation system. The file is rotated at 240 to 280 rpms. When the file tip reaches the apical constriction, the revolution of the file can be automatically reversed (Auto-apical-reverse mechanism). If there is too much torque, the rotation is automatically reversed (Auto-torque-reverse mechanism). These automatic functions promise a safer engine preparation of the canal with nickel-titanium files.

Dental Alloys↗
PubMed1997

Quantitative subtraction with direct digital dental radiography.

OBJECTIVES: To elucidate the accuracy in vitro of quantitative digital subtraction for direct digital dental radiography using a commercially available image analysis system. METHODS: Images were corrected first for dark current and sensitivity variation among pixels of the CCD sensor (first correction), and corrected further for interimage variations due to the variations in exposure conditions (second correction). A copper stepwedge with six steps was used in the second correction. Three corrected images derived from three original images at each different exposure time were examined to confirm the reliability of the second correction. Correlation between bone mineral content and pixel value was assessed in subtracted images of an artificial bone phantom. RESULTS: The first and second corrections significantly improved the intra- and inter-image variation respectively. The second corrected images obtained at three different exposure times showed almost the identical grey levels. An original image was transformed to a copper equivalent image with a high reliability by our original method. The pixel value in the subtracted image between two copper equivalent images of a bone phantom was linearly related to the bone mineral content. There was a slight overestimate at lower pixel values but it was accurate at higher pixel values. CONCLUSIONS: Quantification of digital subtraction using this method is sufficiently reliable for its application to clinical practice to be evaluated.

Adult↗
PubMed1997

CT findings during phase of accelerated deterioration in patients with idiopathic pulmonary fibrosis.

OBJECTIVE: Most patients with idiopathic pulmonary fibrosis (IPF) show slowly progressive deterioration. However, accelerated deterioration also occurs in patient with IPF who have previously shown slowly progressive deterioration. The purpose of this study was to evaluate the CT findings of accelerated deterioration in patients with IPF. MATERIALS AND METHODS: We evaluated the CT findings of 17 patients with IPF who fulfilled all the following criteria for accelerated deterioration of IPF: exacerbation of dyspnea within 1 month, new diffuse pulmonary opacities on chest radiography, a decrease in arterial oxygen tension (PaO2) of more than 10 mm Hg under similar conditions, and absence of apparent infectious agents and heart failure. Seven patients underwent sequential CT examination. Pathologic specimens were obtained from nine patients. RESULTS: CT findings were classified as peripheral parenchymal opacification (n = 6), multifocal parenchymal opacification (n = 6), and diffuse parenchymal opacification (n = 5). Multifocal lesions developed diffusely in two of the seven patients who underwent sequential CT. These two patients both died. Three of the six patients with a multifocal pattern responded to corticosteroid therapy. All patients with a peripheral pattern showed various degrees of improvement following corticosteroid therapy. Multifocal and diffuse parenchymal opacification corresponded pathologically to acute diffuse alveolar damage. Peripheral parenchymal opacification corresponded pathologically to active fibroblastic foci. CONCLUSION: CT patterns seen during periods of rapid deterioration in patients with IPF may allow predictions of prognosis and of response to treatment.

Aged↗
PubMed1997

[Utility of prostate specific antigen (PSA) density in detecting prostate cancer in men showing gray zone serum PSA levels].

The efficacy of prostate specific antigen density (PSAD) in diagnosing prostate cancer was assessed in 98 patients with serum prostate specific antigen (PSA) levels between 2 and 10 ng/ml who had a pathological diagnosis made by prostate biopsy or transurethral resection of the prostate. Of the 98 patients, 22 (22%) had prostate cancer. The PSA (based on a cut-off value of 4.5 ng/ml) had a sensitivity and positive predictive value (PPV) of 82% and 38%, respectively, for diagnosing prostate cancer, while the results for PSAD (based on a cut-off value of 0.13) were 91% and 61%. The PSAD was more efficient than the PSA levels and was also superior to digital rectal examination (DRE) combined with transrectal ultrasonography (TRUS), for which the sensitivity and PPV were 73% and 39%, respectively. Six (11%) out of 57 patients who were normal on DRE and TRUS had prostate cancer. In these 57 patients, the PSA (cut-off value: 4.5 ng/ml) had a sensitivity of 50% and PPV while the values for PSAD (cut-off value: 0.13) were 83% and 36% respectively. The PSAD could effectively detect even impalpable prostate cancer not visible on TRUS.

Aged↗
PubMed1996

Measurement of airborne mite allergen exposure in individual subjects.

To evaluate the extent of personal exposure to airborne mite allergens, subjects were asked to carry a personal air sampler when in their houses. The level of Der 1 allergen trapped by the sampler was measured with a highly sensitive immunoassay. There were great variations in airborne Der 1 exposure in each subject. When used bedding was replaced with new allergen-free bedding, we detected a decrease in the allergen level. The use of new bedding seems to be an effective measure for reducing airborne mite allergen exposure.

Air Pollutants↗
PubMed1996

A new ultrasonic canal preparation system with electronic monitoring of file tip position.

A new ultrasonic root canal preparation system has been developed that electronically monitors the location of the file tip during all instrumentation procedures. The Root ZX has been adapted for this purpose, and its filter circuit effectively cuts out the large spike noise of the ultrasonic unit. During enlargement of the canal, the ultrasonic vibration of the file can be stopped at any desired position on the meter. Extracted human tooth models with electronically measurable canals were used to test the device. Pre- and postoperative shapes of the root canals were evaluated using contact microradiography. The autostop mechanism worked correctly. Using a weak power and fine files, straightening, ledge formation, and file breakage were minimal. It seems that this system minimized the danger of overinstrumentation and could be safely applied in clinical practice.

Dental Instruments↗
PubMed1996

Correction of background noise in direct digital dental radiography.

OBJECTIVES: To clarify the source of noise in direct digital intra-oral radiography with RVG-S (Trophy Radiologie, Vincennes, France) and to use these to develop a method for correction of background noise. METHODS: Sensor temperature, image acquisition time and X-ray dose were independently analysed with the IPLab Spectrum (Signal Analytics, Vienna, VA) software. RESULTS: The decrease in pixel value due to the dark current was linearly related to the image acquisition time. Although a variation in sensitivity was observed when the sensor was exposed to X-rays, the mean pixel value of the entire image was linearly related to the exposure time. The image showing only the signal due to X-ray dose was derived from the original RVG-S image by correcting for the dark current and the pixel-by-pixel sensitivity variation of the CCD sensor. CONCLUSION: The image formed only by X-ray dose distribution can be derived by correcting for the background noise.

Algorithms↗
PubMed1996

[The characteristics of clinical features of pulmonary tuberculosis in female].

We studied the clinical features of culture-positive, previously untreated patients with pulmonary tuberculosis (77 in females and 200 in males), with special reference on the gender differences in clinical features. The mean age was 50.8 y.o. for female and 54.4 y.o. for male, and the age distribution was almost similar to that of newly-registered patients of whole Japan in 1993, namely, small peak in 20s decade and large peaks in the age group over 50 in female, and gradual increase up to 50 years and get to plateau in male. Thirty-nine % in female and fifty-four % in male had various past histories and/or complications which might affect to the deterioration of tuberculosis, such as diabetes mellitus, liver function distress, respiratory failure, malignancy, stomach resection and so on. The rates with each complication were, in general, higher in male than in female. The positive rate to Mantoux reaction was higher in female than in male, and stronger reactions were observed in female than in male. According to the classification of pulmonary tuberculosis designed by the Japanese Society for Tuberculosis (GAKKAI classification), the site(s) of affected lung, the stage and the extent of lesions were more advanced in male than in female, and the positive rate and the amount of bacilli on smear were higher in male than in female. The most marked difference was the location of the main lesions, 80% in the apical and posterior segments of upper lobe (S1,2) and 8% in the superior segments of lower lobe (S6) in male, while 60% in S1,2 and 25% in S6 in female. The rate of complete resistance against to anti-tuberculosis agents was higher in male than in female, but the combination chemotherapy of isoniasid and refampicin with streptomycin or ethambutol was almost equally effective both in males and females, and almost all patients converted to bacilli negative within three months after the initiation of the chemotherapy, except in a few male patients.

Adult↗
PubMed1995

Electronic canal length measurement.

The most important advantage of the electronic method is that it can measure the length of the root canal to the end of the apical foramen, not to the radiographic apex. The most striking disadvantage of the electronic method is that if strong electrolytes are in the root canal, the meter shows a reading that is too high (obtaining a short working length), or sometimes the measurement itself becomes impossible. Recently new electronic devices have been developed. These devices can make an accurate measurement of the root canal length, even if a strong electrolyte is present in the root canal. These new devices allow the dentist to enlarge the apical portion of the canal more precisely than when the radiographic method is used.

Dental Pulp Cavity↗