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Biomedical subjects

H Nishitani

Publications and source records attributed to H Nishitani.

At least 73 records · Page 4Linked to original sources
PubMed1996

[Clinical studies on vancomycin in the treatment of MRSA infection].

We evaluated the effectiveness and safety of vancomycin (VCM) alone and in combination with beta-lactam antibiotics in the treatment of MRSA infections, and obtained the following results: 1. Effectiveness. (1) In cases of MRSA infections alone, the improvement rate was 71.4% (5/7 patients) with VCM alone and 77.8% (35/45) with VCM in combination with beta-lactam antibiotics. (2) In cases of polymicrobial infections, few cases were treated with VCM alone, but the improvement rate in combination use with beta-lactam antibiotics was 71.8% (28/39). 2. Bacteriological effect. (1) In cases of single infection with MRSA, the rate of bacterial eradication was 71.4% (5/7) with VCM alone and 68.2% (30/44) with VCM in combination with beta-lactam antibiotics. (2) In cases of polymicrobial infections, few cases were treated with VCM alone, but the rate of bacterial eradication in combination use with be ta-lactam antibiotics was 63.2% (24/38) against MRSA and 31.6% (12/38) against polymicrobial agents including MRSA. 3. Safety. Occurrences of adverse reactions and abnormal laboratory test values when VCM was used alone or when it is used in combination with another drug were about the same in these uses. As a whole, advance reactions were observed in 16 patients (9.5%). Main adverse reactions were whole body redness, drug eruption, and rash etc. Abnormal laboratory test values were observed mainly in hepatic functions, and renal functions. 4. VCM concentrations in blood was determined in 38 patients. Doses of 0.5 g and 1.0 g of VCM was administered by intravenous drip infusion over a period of 1 to 2 hours, and mean blood concentrations 1 to 2 hours after the completion of drip infusion were 25.4 micrograms/ml and 14.4 micrograms/ml, respectively. 5. Synergic effects between VCM and other antibiotics tested were observed in FIC index against all of the six MRSA strains isolated from six patients, and the clinical effects of improvement or better were obtained against five of them.

Adolescent↗
PubMed1995

p65cdc18 plays a major role controlling the initiation of DNA replication in fission yeast.

A key problem in the cell cycle is understanding what brings about the initiation of DNA replication and how this is linked with global cell cycle controls. The fission yeast gene cdc18 is required for DNA replication and is transcriptionally activated by the cdc10/res1/res2 control acting at START in late G1. We show here that overexpressing cdc18 is able to bring about repeated rounds of DNA synthesis in the absence of mitosis and of continuing protein synthesis. The level of the cdc18-encoded protein p65cdc18 is periodic in the cell cycle, peaking at the G1 to S phase transition, and p65cdc18 is located in the nucleus when cdc18 is overexpressed. We propose that p65cdc18 acts at the initiation of DNA replication and plays a major role in controlling the onset of S phase.

Cell Cycle Proteins↗
PubMed1995

Finding of a homarine-synthesizing enzyme in turban shell and some properties of the enzyme.

A homarine-synthesizing enzyme was found for the first time in cell-free extract from turban shell (Batillus cornutus) and the enzyme was purified 36.2-fold and characterized. Properties of the enzyme were as follows: substrates were picolinic acid (pyridine-2-carboxylic acid) and S-adenosyl-L-methionine; optimum temperature for the enzymic reaction was 25 degrees C; optimum pH for the enzymic reaction was 6.3; and the Km values for picolinic acid and S-adenosyl-L-methionine were calculated at 317 and 14.5 microM, respectively. Among pyridine carboxylic acids, only picolinic acid was methylated with S-adenosyl-L-methionine by this enzyme. The molecular weight of the enzyme was estimated to be 70,800. The enzyme activity was inhibited by heavy metal ions, S-adenosyl-L-homocysteine, adenosine, homocysteine, and sinefungin. Homarine, which is an osmotic pressure regulator, morphogen, etc.; is enzymatically synthesized by the methylation of picolinic acid with S-adenosyl-L-methionine and the enzyme activity may be controlled by S-adenosyl-L-homocysteine (reaction product) and its related compounds.

Adenosine↗
PubMed1995

A new type of E. coli recombinational hotspot which requires for activity both DNA replication termination events and the Chi sequence.

In E. coli rnh- mutants we identified chromosome-derived, specific DNA fragments termed Hot DNA. When the DNA in the ccc form is integrated into the E. coli genome by homologous recombination to form a directly repeated structure, a striking enhancement of excisional recombination between the repeats occurs. We obtained 8 groups of such Hot DNA, 7 of which were clustered in a narrow region called the replication terminus region (about 280 kb) on the circular E. coli genome. A Ter site can impede the replication fork in a polar fashion. The six Ter sites are approximately symmetrical in the terminus and surrounding region. To block the fork at the Ter site, a protein factor, Ter binding protein encoded in the tau (or tus) gene, is required. In tau- cells, Hot activity of HotA, B, and C DNAs disappears, thereby indicating that the Hot activity is fork arrest-dependent. Other Hot activities were tau-independent. In addition, for at least HotA activity, the presence of Chi, and E. coli recombinational hotspot sequence, is required; the Chi dependent HotA activity was detected in a wild type strain but to a lesser extent than that in the rnh- mutant. To explain the HotA phenomenon at the molecular level, we propose a model in which a ds-break occurs at the replication fork arrested at the Ter site. Our recent data that HOT1, a yeast recombinational hotspot, may also depend on the fork blocking event for activity, suggests that a similar ds-break occurs in both eucaryotes and procaryotes.

Base Sequence↗
PubMed1995

Heat-insoluble cryoglobulin in a patient with essential type I cryoglobulinemia and massive cryoglobulin-occlusive glomerulonephritis.

We report a case of type I essential cryoglobulinemia with massive cryoglobulin-occlusive glomerulonephritis, in which the clinical course and the physical characteristics of the cryoglobulin were unusual. Nine years before appearance of cryoglobulin, this 54-year-old man noted edema and purpura of the lower extremities. Renal biopsy performed 2 years later showed large amounts of amorphous, weakly eosinophilic, weakly periodic acid-Schiff (PAS)-positive materials occluding the glomerular capillaries. Immunostaining showed the material to be weakly immunoglobulin (Ig) G positive, and electron microscopy showed homogeneous, electron-dense deposits. Nephrotic syndrome and azotemia did not respond to steroid treatment, and dialysis was begun 5 years after the biopsy. A small amount of cryoglobulin was first detected 2 years later, 9 years after the onset of disease. The cryoglobulin had a white gelatinous appearance, was resistant to resuspension, and did not redissolve when rewarmed to 37 degrees C. Immunoelectrophoresis of the cryoglobulin, which partially dissolved at 54 degrees C, showed it to be composed of monoclonal IgG-kappa and a small amount of albumin. We consider that the unusual physical characteristics of the cryoglobulin in this case precipitated a massive cryoglobulin-occlusive glomerulonephritis, which progressed to end-stage renal failure in the absence of significant cryoglobulinemia during the initial onset of disease.

Cryoglobulinemia↗
PubMed1995

Detachment of cultured cells from the substratum induced by the neutrophil-derived oxidant NH2Cl: synergistic role of phosphotyrosine and intracellular Ca2+ concentration.

The neutrophil-derived, membrane-permeating oxidant, NH2Cl, (but not the non-membrane-permeating chloramine, taurine-NHCl) induced detachment of fetal mouse cardiac myocytes and other cell types (fibroblasts, epithelial cells, and endothelial cells) from the culture dish, concomitant with cell shrinkage ("peeling off"). Stimulated human neutrophils also induced peeling off of cultured mouse cardiac myocytes when the latter were pretreated with inhibitors of .OH and elastase. Immunofluorescence microscopy revealed that the NH2Cl-induced peeling off of WI-38 fibroblasts is accompanied by disorganization of integrin alpha 5 beta 1, vinculin, stress fibers, and phosphotyrosine (p-Tyr)-containing proteins. Decrease in the content of the p-Tyr-containing proteins of the NH2Cl-treated cells was analyzed by immunoblotting techniques. Coating of fibronectin on the culture dish prevented both NH2Cl-induced peeling off and a decrease in p-Tyr content. Preincubation with a protein-tyrosine phosphatase inhibitor, sodium orthovanadate (Na3VO4), also prevented NH2Cl-induced peeling off, suggesting that dephosphorylation of p-Tyr is necessary for peeling off. NH2Cl-induced peeling off was accompanied by an increase in intracellular Ca2+ concentration ([Ca2+]i) in mouse cardiac myocytes and WI-38 fibroblasts. The absence of extracellular Ca2+ prevented both NH2Cl-induced peeling off and increased [Ca2+]i, both of which did occur on subsequent incubation of the cells in Ca2+-containing medium. These observations suggest that an increase in [Ca2+]i is also necessary for peeling off. Depletion of microsomal and cytosolic Ca2+ by incubation with the microsomal Ca2+-ATPase inhibitor 2',5'-di(tert-butyl)-1,4-benzohydroquinone (BHQ) plus EGTA prevented both NH2Cl-induced increases in [Ca2+]i and peeling off. Direct inhibition of microsomal Ca2+ pump activity by NH2Cl may participate in the NH2Cl-induced [Ca2+]i increment. A combination of p-Tyr dephosphorylation by genistein (an inhibitor of tyrosine kinase) and an increase in [Ca2+]i by BHQ could also induce peeling off. All these observations suggest a synergism between p-Tyr dephosphorylation and increased [Ca2+]i in NH2Cl-induced peeling off.

Animals↗
PubMed1995

Non-invasive characterization of brain tumor by in-vivo proton magnetic resonance spectroscopy.

We studied the feasibility of characterizing brain tumor tissue by localized proton magnetic resonance spectroscopy (1H-MRS). Twenty-six newly diagnosed tumors were examined by in-vivo 1H-MRS. The NAA (N-acetylaspartate)/Cho (choline) ratio of Grade 2 astrocytoma was higher than that of Grade 4. The Cho/Cr (creatine and phosphocreatine) ratio of meningioma was considerably higher than that of glioma of all grades. We have experienced only two cases of ependymoma and the Cho/Cr ratios of both were lower than that of glioma. It seems likely that 1H-MRS can be used to differentiate Grade 2 from Grade 4 in most cases of astrocytoma based on the NAA/Cho ratio, though a few cases will overlap. Meningioma can be distinguished easily from glioma, and the results of our study suggest that ependymoma shows a characteristic pattern on 1H-MRS, different from those of other brain tumors.

Aspartic Acid↗
PubMed1995

Ectopic gastric mucosa in the upper esophagus: prevalence and radiologic findings.

OBJECTIVE: Ectopic gastric mucosa of the upper esophagus is an asymptomatic benign lesion that may simulate a more serious lesion on radiographs. We studied the radiographic findings and prevalence of this abnormality. SUBJECTS AND METHODS: During a 1-year period, 1142 consecutive patients (817 men, 325 women) who had an upper gastrointestinal series as part of an annual health checkup were prospectively studied. Routine examination of the esophagus consisted only of fluoroscopy. Radiographs were obtained if any localized irregularities were found in the upper esophageal wall at fluoroscopy. The findings were subsequently confirmed by endoscopy and biopsy. RESULTS: Ectopic gastric mucosa in the upper esophagus was seen in 27 (25 men, two women) of the 1142 patients. Forty-three localized ectopic gastric mucosal patches varying in size from 5 mm to 32 mm were detected at the level of the thoracic inlet in the 27 patients. The most common radiographic finding was a pair of small indentations on the wall of the esophagus (18 patches). Other findings included a rimlike shadow (three patches), a pair of somewhat large indentations with a shallowly depressed area between them (two patches), one indentation (five patches), a small flat elevation (one patch), a serrated irregular outline (five radiologic lesions consisted of 11 patches), other various irregular outlines (two patches), and a polypoid area (one patch). CONCLUSION: Prevalence of radiographic evidence of ectopic gastric mucosa in the upper esophagus is 2.4%. The lesion was found more commonly in men (3.1%) than in women (0.6%). Radiographic findings include a pair of indentations along the lateral margin of the esophagus and a rimlike shadow on the anterior or posterior wall. Recognition of the characteristic radiographic features of this abnormality makes endoscopy and follow-up unnecessary.

Adult↗
PubMed1995

[A trial for quantification of proton MR spectroscopy: relaxation times of each metabolite and concentration using water signal as an internal standard].

We conducted quantification of proton MR spectroscopy (1H-MRS) using water signal as an internal standard. The 1H-MR spectrum was measured with and without water suppression pulses. For calculation of relaxation times, measurement conditions of the PRESS sequence were as follows: TR = 1500, 3000, 5000 ms, TE = 135,270 ms. The T1 relaxation and T2 relaxation of each metabolite were calculated by fitting to the curve of the equation of the spin echo sequence. The signal intensities of each metabolite were corrected using relaxation times and such corrected intensities were used for the quantitative calculation. The concentration of each metabolite was obtained from ratios of the corrected intensities of water and metabolites. The value of each concentration was coincident with that reported in the previous literature. We considered that this quantification using water signal as an internal standard would be very useful when the proton-weighted image does not show remarkable change.

Adult↗
PubMed1995

Classification criteria for polymyositis and dermatomyositis.

OBJECTIVE: The establishment of classification criteria for polymyositis (PM) and dermatomyositis (DM). METHODS: Questionnaires inquiring about patients with DM, PM, systemic lupus erythematosus, progressive systemic sclerosis and noninflammatory neuromuscular diseases were distributed to the main medical institutes in Japan. Data were collected and analyzed by computer. RESULTS: Among skin lesions of DM, heliotrope rash, Gottron's sign and erythema or purpura on the extensor surfaces of the extremity joints were shown to be distinguishing criteria. In both DM and PM, proximal muscle weakness, muscle grasping and spontaneous pain, nondestructive arthritis or arthralgia, elevated CK or aldolase level, presence of systemic inflammatory signs, myogenic changes on EMG, positive and anti Jo-1 antibody and pathologic findings compatible with inflammatory myositis were distinguishing criteria items. CONCLUSION: When a patient satisfies one of 3 skin lesion items and at least 4 other items, he or she shall be classified as having DM, sensitivity 94.1%. When a patient satisfies at least 4 items other than skin lesion items, he or she shall be classified as having PM, sensitivity 98.9%. Specificity of DM and PM is 95.2%.

Dermatomyositis↗
PubMed1995

[Three-dimensional longitudinal dissection view of hollow viscus].

To visualize the pathologies of hollow viscus and their extension three-dimensionally, volume data of the larynx, trachea, stomach, rectum, and urinary bladder were obtained using helical CT with moderately thin slices. Longitudinal cut sections were made as in a simulated surgical cut, and the interior morphology was displayed along with the pathology. A cylindrical projection profile was made by making a longitudinal incision on one wall and pulling apart the flaps to reveal the interior, providing better visual perception. The detailed outline from the 3D profile and the cylindrical projection views constituted an added advantage over the existing procedures.

Humans↗
PubMed1995

[Digitized medical images].

Digitalization of medical images implies that we are able to process images by computers, are able to make as many as exact copies of original images, and are able to transfer images without any loss of information. Clinical usefulness of image processing with special attention to three dimentional images were discussed. There are many problem to be solved in the development of PACS. It is important at least now that discussion of images for primary diagnosis and images for reference should be done separately. Utilization of digitized images for education is promising. A trial of education using a world wide web server-client system was reported. Possible trends of digitized medical images were described.

Diagnosis, Computer-Assisted↗
PubMed1994

Noninvasive localization of accessory pathways by magnetocardiographic imaging.

The magnetocardiogram (MCG) is a newly developed method that helps localize a cardiac current source. To test the clinical accuracy of a 7-channel biomagnetic system in the localization of early ventricular depolarization sites, the MCGs of 14 patients with Wolff-Parkinson-White (WPW) syndrome were recorded in a radiofrequency-shielded room. The locations of early ventricular depolarization sites were classified by standard 12-lead electrocardiograms (ECGs) and body surface isopotential mapping. The accessory pathways of 3 patients with WPW syndrome were located in the right free wall and in 11 patients in the left free wall. The three-dimensional (3-D) dipole location was computed every 2 ms from the onset of the QRS complex by the least-square method. These 3-D dipole locations were projected onto a gated magnetic resonance image in order to visualize the propagation of the calculated ventricular source. The results were compared with those obtained by body surface isopotential mapping, and electrocardiographic and electrophysiologic studies. The location of the deduced current dipole at 20 ms correlated well with the location of the accessory pathway by the body surface mappings in 12 of the 14 patients with WPW syndrome. The MCG is capable of precisely determining the 3-D location of a current source in a noninvasive manner and may be of potential benefit in the treatment of WPW syndrome by catheter ablation.

Adolescent↗
PubMed1994

Brain abscess observed by localized proton magnetic resonance spectroscopy.

We encountered a case of brain abscess that was difficult to differentiate from glioblastoma. Localized 1H-MRS was found to be useful for obtaining information on the biochemical status of brain abscess. The peak of lipid and high residual peak of NAA (N-acetyl-aspartate) were observed in the cystic lesion of the brain abscess by 1H-MRS. The NAA/Cho (Choline-containing compounds) ratio in brain parenchyma showing an edematous lesion before therapy gradually increased with the relief of inflammation.

Aspartic Acid↗
PubMed1994

The DNA replication fork blocked at the Ter site may be an entrance for the RecBCD enzyme into duplex DNA.

In Escherichia coli, eight kinds of chromosome-derived DNA fragments (named Hot DNA) were found to exhibit homologous recombinational hotspot activity, with the following properties. (i) The Hot activities of all Hot DNAs were enhanced extensively under RNase H-defective (rnh) conditions. (ii) Seven Hot DNAs were clustered at the DNA replication terminus region on the E. coli chromosome and had Chi activities (H. Nishitani, M. Hidaka, and T. Horiuchi, Mol. Gen. Genet. 240:307-314, 1993). Hot activities of HotA, -B, and -C, the locations of which were close to three DNA replication terminus sites, the TerB, -A, and -C sites, respectively, disappeared when terminus-binding (Tau or Tus) protein was defective, thereby suggesting that their Hot activities are termination event dependent. Other Hot groups showed termination-independent Hot activities. In addition, at least HotA activity proved to be dependent on a Chi sequence, because mutational destruction of the Chi sequence on the HotA DNA fragment resulted in disappearance of the HotA activity. The HotA activity which had disappeared was reactivated by insertion of a new, properly oriented Chi sequence at the position between the HotA DNA and the TerB site. On the basis of these observations and positional and orientational relationships between the Chi and the Ter sequences, we propose a model in which the DNA replication fork blocked at the Ter site provides an entrance for the RecBCD enzyme into duplex DNA.

Bacterial Proteins↗
PubMed1994

Ectopic gastric mucosa in the upper esophagus: detection and radiographic findings.

PURPOSE: To detect and characterize the appearance of islands of ectopic gastric mucosa in the upper esophagus at routine examination of the upper gastrointestinal (GI) tract. MATERIALS AND METHODS: Well-distended upper esophagus was documented with spot radiographs obtained with routine double-contrast examination performed after administration of high-density barium in nine patients. Detected lesions were confirmed by means of endoscopy and biopsy. RESULTS: Twelve lesions were detected. Radiographic findings were characterized by either a discrete, shallow depression surrounded by a subtle, rimlike elevation on double-contrast images or by a pair of small indentations on the same wall on full-column, single-contrast images at the level of the thoracic inlet. Endoscopic examination revealed well-circumscribed areas of reddish mucosa located 15-26 cm from the incisors. CONCLUSION: Ectopic gastric mucosa in the upper esophagus is easily demonstrated at routine examination of the upper GI tract. Diagnosis can be based on location and characteristic radiographic appearance.

Adult↗