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H Koga

Publications and source records attributed to H Koga.

At least 127 records · Page 7Linked to original sources
PubMed1998

[Persistent lateral gaze palsy and abducens nerve palsy due to pontine infarction].

A 76-year-old hypertensive man noticed sudden dizziness and diplopia. On examination, right-sided gaze deviation was present, but the remainder of the neurological examination was normal. Five days later, MRI revealed a small lesion in the left paramedian pontine tegmentum, which was consistent with pontine infarction. The conjugate deviation disappeared about two weeks after the onset, but a left lateral gaze and abducens nerve palsy have persisted at ten months after the infarct. MRI findings are unchanged. The site of infarction is presumed to be located in the caudal portion of paramedian reticular formation and the abducens nerve fascicle. Persistent lateral gaze palsy is rare in pontine infarction, and this case is important in illustrating the anatomical location of paramedian pontine reticular formation.

Abducens Nerve↗
PubMed1998

[Multidrug-resistant tuberculosis. 2. Mechanisms of drug-resistance in Mycobacterium tuberculosis--genetic mechanisms of drug-resistance].

Multidrug-resistant Mycobacterium tuberculosis infection is now world wide health problem. However, according to the recent advances of molecular biological technics, some of the genetic mechanisms of drug-resistance of M. tuberculosis has been uncovered. Generally, drug-resistance of M. tuberculosis was caused by point mutations in chromosomal gene. In isoniazid (INH) resistant M. tuberculosis, mutations and genetic deletions in catalase-peroxidase gene (katG), inhA gene, or alkyl hydroperoxide reductase gene were reported. We also found that about 15% of INH-resistant M. tuberculosis isolates lacked katG gene, and these isolates showed highly resistance to INH with MIC > or = 64 micrograms/ml. On the other hand, mutations and other genetic alterations in RNA polymerase beta subunit gene (rpoB) were the major mechanisms of resistance to rifampicin (RFP) with high frequencies of 90% or more. Our evaluation of the relationship between RFP susceptibility and genetic alteration in rpoB gene also showed that 95% of RFP-resistant M. tuberculosis isolates involved genetic alterations in 69 bp core region of rpoB gene. Moreover, these genetic alterations in rpoB gene were suspected as the resistant mechanism to other rifamycin antituberculosis drugs, such as rifabutin and KRM-1648. In addition, it was reported that point mutations in 16S rRNA gene (rrs) and ribosomal protein S12 gene (rpsL) induced M. tuberculosis as streptomycin (SM) resistant phenotype. We analyzed genetic alternations in rpsL gene of clinically isolates of M. tuberculosis, about 60% of SM resistant isolates were shown point mutation in this gene ant they were all high SM-resistant with MIC > or = 256 micrograms/ml. Furthermore, nicotinamidase (pncA) gene, DNA gyrase A subunit (gyrA) gene, and embB gene were reported as the responsible gene to pyrazinamide-, quinolone- and ethambutol-resistance, respectively. Although all mechanisms of drug-resistance were still unclear, these informations are very useful and helpful for development of rapid diagnosis system of drug-resistant M. tuberculosis.

Drug Resistance, Microbial↗
PubMed1998

[Advances in genetic diagnostics for mycobacterial infection].

The past decade has seen the rapid advancement of molecular biology and its application in the field of mycobacteriosis. AccuProbe and DNA-DNA hybridization method for identification of mycobacteria are already commercially available and have expedited identification. Furthermore, three commercially available rapid mycobacteria detection kits based on amplification of nucleic acid from specimens, Amplicor, Ligase chain reaction, and Gen-Probe Amplified Mycobacterium tuberculosis Direct Test, have been developed since 1994. Although these new methods are clinically useful, and the utility frequency have been increasing, the problems of false positive and negative results due to various reasons should be carefully resolved in future.

DNA Probes↗
PubMed1997

Nuclear DNA fragmentation and expression of Bcl-2 in primary biliary cirrhosis.

It is uncertain whether or not apoptosis is involved in the pathogenesis of primary biliary cirrhosis (PBC). The aims of this study were to assess the nuclear DNA fragmentation and expression of Bcl-2 in the biliary epithelial cells (BECs) and in the hepatocytes of PBC. Additionally, the effects of ursodeoxycholic acid (UDCA) on DNA fragmentation and Bcl-2 expression in PBC were evaluated. Liver tissue specimens from 35 PBC patients were examined by in situ nick-end labeling to detect any nuclear DNA fragments, and by immunohistochemistry for Bcl-2. Ten of these patients underwent a second liver biopsy after the treatment with UDCA. Sixteen histologically normal liver tissues and 17 chronic viral hepatitis C (CVHC) samples were chosen as controls. DNA fragmentation in BECs was more frequently found in PBC than in CVHC and more frequently than in the normal controls (both P < .05), and fragmentation in the hepatocytes of PBC more frequently than in normal controls (P < .01). Bcl-2 expression was more frequently found in both the BECs and hepatocytes of PBC than in the controls. UDCA significantly decreased the DNA fragmentation in BECs (P < .05) and the positivity for Bcl-2 in BECs (P < .01), although no significant decrease was found in hepatocytes. In conclusion, de novo Bcl-2 expression in hepatocytes of PBC was shown, and the increased nuclear DNA fragmentation and the Bcl-2 expression both in BECs and in hepatocytes may reflect apoptotic stress, although nuclear DNA fragmentation in BECs did not necessarily represent apoptosis. UDCA showed a potential effect of reducing nuclear DNA fragmentation in BECs.

Apoptosis↗
PubMed1997

Apparent diffusion coefficient (ADC) and magnetization transfer contrast (MTC) mapping of experimental brain tumor.

Brain tumor tissue contains different pathological areas, such as tumor cell rich parts, necrotic tissues, and cyst. Furthermore, both neovascularization and edema formation progress along with the tumor progression. In this study we employed diffusion weighted (DW) and magnetization transfer contrast (MTC) imaging to chronologically investigate the biological characteristics of a rat glioma. RG-2 glioma cells were implanted stereotactically into the right hemisphere of male Wistar rats. MR images were taken 1, 2 and 3 weeks after inoculation. Apparent diffusion coefficient (ADC) and MTC values were calculated as follows; ADC = -ln (SI-DW/SI-T2)/1096, MTC = 1-SI-MTon/SI-MToff. Each mapping image was made based on the calculated average values of four pixels. The spatial signal changes and the real values were compared to the histological findings. The apparent increase of ADC was noted in the parenchyma adjacent to tumor suggesting the progression of edema. The tumor itself had similar or slightly increased ADC. Cystic and necrotic components appeared 2 weeks after implantation and they showed significantly higher ADC than those calculated in the contralateral putamen. On the other hand, MTC was slightly decreased in the parenchyma adjacent to the tumor, markedly within the tumor, and maximally in the cystic and necrotic area suggesting accumulation of macromolecules such as growth factors, cytokines, and serum albumin.

Animals↗
PubMed1997

Differential diagnosis of tuberculous pleurisy by measurement of cytokine concentrations in pleural effusion.

STUDY OBJECTIVE: Measurement of cytokine concentration in serum and pleural effusion may be useful in the differential diagnosis of tuberculous pleurisy. PATIENTS AND METHODS: We compared the biochemical properties and concentrations of cytokines in serum and pleural effusion samples of 18 patients with tuberculous pleurisy, 7 patients with parapneumonic pleurisy, and 25 patients with malignant pleurisy. RESULTS: A high value of adenosine deaminase (ADA) was observed in pleural effusion of patients with tuberculosis. The serum concentrations of interleukin (IL)-1-beta, IL-2, interferon (IFN)-gamma and tumor necrosis factor (TNF)-alpha were similar among the three groups. However, the concentration of IFN-gamma in pleural effusion was high in tuberculous patients, and that of TNF-alpha was high in tuberculous and parapneumonic pleural fluid, but both cytokines were low in malignant pleural fluid. The sensitivity, specificity and accuracy of IFN-gamma in the diagnosis of tuberculous pleurisy were 94%, 100% and 98%, respectively. Similarly, those of TNF-alpha for the diagnosis of infectious pleurisy including tuberculous and parapneumonic pleurisy were 88%, 80% and 84%, respectively. CONCLUSIONS: Our results indicate that simultaneous measurement of IFN-gamma and TNF-alpha in pleural effusion is a useful diagnostic tool for differentiating tuberculous pleurisy from parapneumonic and malignant pleurisy.

Adult↗
PubMed1997

Genetic relationship of penicillin resistant Streptococcus pneumoniae serotype 19B strains in Japan.

Pulsed field gel electrophoresis (PFGE) of the genomic DNA of penicillin resistant serotype 19B Streptococcus pneumoniae was carried out. Thirteen strains form the Nagasaki area and 12 strains from other areas in Japan were examined. Twenty-three strains were resistant to erythromycin, tetracycline and trimethoprim/sulfamethoxazole but susceptible to chloramphenicol. Eight strains were resistant to ceftriaxone. All strains were multiply resistant. Five strains isolated from Nagasaki were indistinguishable from each other by using restriction enzymes Apa I and Sma I. Two strains isolated from other areas were indistinguishable from the above five strains. We could classify 13 Nagasaki strains into 3 groups and the total of 25 Japanese strains into 6 groups. These results suggest that the increasing prevalence of multiply drug resistant S. pneumoniae serotyped 19B in Japan is not due to a single clone, but at least one clone has spread widely in Japan.

DNA, Bacterial↗
PubMed1997

In vitro susceptibility studies and detection of vancomycin resistance genes in clinical isolates of enterococci in Nagasaki, Japan.

Glycopeptide resistance in enterococci is now a cause of clinical concern in the United States and Europe. However, details of vancomycin resistance in enterococci in Japan have been unknown. We measured minimum inhibitory concentrations (MICs) of various antimicrobial agents for a total of 218 clinical strains of enterococci isolated in our hospital in 1995-6 in addition to 15 strains with known genotypic markers of resistance. We also screened vancomycin resistance genes using a single step multiplex-PCR. In clinical isolates, only two strains of Enterococcus gallinarum were of intermediate resistance to vancomycin (MIC, 8 micrograms/ml), while the others were all susceptible. Glycopeptides (vancomycin and teicoplanin) and streptogramins (RP 58500 and RPR 106972) showed potent antimicrobial effects for the isolates. In addition, ampicillin was also potent for Enterococcus faecalis, while ampicillin, minocycline and gentamicin were potent for Enterococcus avium. No vanA or vanB genes were detected, while vanC1 and vanC23 genes were detected from two and four strains, respectively. Our results suggest that incidence of VRE in Japan may be estimated as still very low at this time.

Anti-Bacterial Agents↗
PubMed1997

Effects of all-trans-retinoic acid on superoxide generation in intact neutrophils and a cell-free system.

To determine the pathophysiology of the retinoic acid syndrome which occurs during all-trans-retinoic acid (ATRA) treatment of acute promyelocytic leukaemia patients, we investigated the direct effects of ATRA on the function of human neutrophils. We found that ATRA (10-200 microM) dose-dependently stimulated superoxide (O2-) generation in intact neutrophils. The maximal activity of ATRA-stimulated O2- generation was 3.0 nmol/min/10(6) cells. Adding EGTA to the assay mixture did not affect the activity nor was the intracellular free calcium concentration changed upon stimulation. The treatment of neutrophils with 0.1 microM staurosporine, an antagonist of protein kinase C, for 10 min, enhanced the activity of ATRA-stimulated O2- generation up to 186% of that for control samples. Wortmannin (1 microM), an inhibitor of phosphatidylinositol 3-kinase (PI 3-kinase), reduced this stimulatory activity by 67%. These results suggest that ATRA activates the signalling pathway related to PI 3-kinase rather than that utilizing calcium and protein kinase C. ATRA enhanced the O2- generated in a sodium-dodecyl-sulphate (SDS) cell-free system, resulting in rates up to 288% higher than that seen with SDS alone. This enhancement was not affected by pretreatment with staurosporine or wortmannin. ATRA may thus directly activate and/or enhance the function of neutrophils.

Androstadienes↗
PubMed1997

Defective response to thrombopoietin and impaired expression of c-mpl mRNA of bone marrow cells in congenital amegakaryocytic thrombocytopenia.

Congenital amegakaryocytic thrombocytopenia (CAMT) is an uncommon disorder in newborns and infants, characterized by isolated thrombocytopenia and megakaryocytopenia in the first year without physical anomalies. The defect of thrombopoiesis is not well understood. Recently, thrombopoietin (TPO), the ligand for the c-mpl receptor, was cloned. Accumulating evidence from in vitro and in vivo studies indicate that TPO plays a key role in the regulation of megakaryocytopoiesis. In this study we examined the effect of TPO on megakaryocyte colony formation from a patient with CAMT using a plasma-containing methylcellulose clonal culture. The in vitro results demonstrated a defective response to TPO in megakaryocyte colony formation from bone marrow mononuclear cells (MNC) of the patient. although interleukin-3 (IL-3) but not stem cell factor (SCF) induced only a small number of megakaryocyte colonies. These findings indicated that thrombocytopenia in CAMT could not be corrected by administration of TPO in vitro. Additionally, clonal cultures containing SCF, IL-3, IL-6 and erythropoietin showed decreased numbers of erythroid and myelocytic progenitors in the bone marrow of the patient. The serum TPO level measured by enzyme-linked immunosorbent assay was significantly higher than that in healthy controls. By PCR, marrow MNC from healthy children and from a patient with essential thrombocytosis expressed c-mpl mRNA, whereas no c-mpl mRNA was detected in marrow MNC from the patient with CAMT. There was no difference in the CD34 expression and c-kit mRNA between the CAMT patient and healthy children. The results of this study suggest that the pathophysiology in CAMT may be a defective response to TPO in haemopoietic cells through impaired expression of c-mpl mRNA.

Bone Marrow↗
PubMed1997

A rapid drug susceptibility test for Mycobacterium tuberculosis using the hybridization protection assay.

The conventional drug susceptibility tests for Mycobacterium tuberculosis are time-consuming and the results are available only after 2-4 weeks. We have recently reported a new, simple and fast M. tuberculosis drug susceptibility test, using the hybridization protection assay (HPA), that allows the detection of isoniazid- or rifampicin-resistant strains of M. tuberculosis within 24 h of incubation. In the present study, the scope of application of our new test was extended to another two first-line antimycobacterial agents, namely ethambutol and streptomycin, and a quinolone antimicrobial agent, ciprofloxacin. The ethambutol-, streptomycin- and ciprofloxacin-resistance characteristics of M. tuberculosis were also delineated within 72 h of incubation with or without the drug. The results of our novel and rapid drug susceptibility test for M. tuberculosis were not only comparable to those determined by the conventional method, but became available within a few days of incubation. Our results also suggest that the drug susceptibility test using HPA might also be useful for detecting organisms resistant to antimicrobial agents other than antimycobacterials.

Anti-Infective Agents↗
PubMed1997

An extensive cranial base meningioma extending bilaterally into Meckel's cave: case report.

OBJECTIVE AND IMPORTANCE: A patient with an extensive cranial base meningioma that included bilateral invasion of Meckel's cave underwent surgical resection and had an unexpected rare complication, malocclusion from bilateral trigeminal dysfunction. CLINICAL PRESENTATION: A 19-year-old male patient was admitted to our hospital with alternating painful ophthalmoplegia. He had been blind since the age of 10 years. At the time of admission, neurological findings included bilateral visual loss and optic atrophy. Magnetic resonance images showed an extensive tumor located at the planum sphenoidale, tuberculum sellae, and bilaterally at Meckel's cave and the medial tentorial incisura. INTERVENTION: The patient underwent a two-stage operation. During the first procedure, the masses in the planum sphenoidale, tuberculum sellae, and the left side of Meckel's cave were excised intradurally. At the second operation, the mass in the right side of Meckel's cave was excised extradurally and the tentorial mass was removed intradurally. The patient's postoperative course was complicated by bilateral trigeminal nerve dysfunction, which caused malocclusion. CONCLUSION: Bilateral dysfunction of the trigeminal nerve may cause a number of problems. Thus, extreme caution must be taken to preserve the function of this nerve.

Adult↗
PubMed1997

Significance of the BTA test in bladder cancer: a multicenter trial. BTA Study Group Japan.

BACKGROUND: The BTA test is a latex agglutination assay for the qualitative detection in the urine of analytes that are associated with bladder tumor. We compared the results of the BTA test with those of voided urine cytology (VUC) in patients with bladder cancer. METHODS: A multicenter trial was performed at 6 institutions. A total of 132 patients with histologically diagnosed bladder cancer were enrolled. Urine samples were split for BTA and VUC testing. RESULTS: The sensitivities of the BTA test and VUC were 57.6% and 37.9%, respectively; this difference was significant (P < 0.001). The BTA test had much higher sensitivity for small, solitary, superficial tumors than did VUC. CONCLUSION: The BTA test is simple to perform, gives rapid results, and is far more sensitive than VUC for detection of bladder cancer. The BTA test has the potential to become an additional tool for detecting bladder cancer.

Adult↗
PubMed1997

Reversible limbic encephalitis caused by ovarian teratoma.

A 19-year-old woman developed memory loss followed by psychosis, coma, convulsion, and central hypoventilation requiring mechanical ventilation. MRI of the brain showed minimal changes, and SPECT imaging revealed a small region of increased uptake in the cortex. Intravenous acyclovir and high-dose corticosteroids were administered without any effect. An extensive work-up revealed an elevated serum alpha-fetoprotein (AFP) concentration and the presence of an ovarian tumor. Following resection of the tumor, an immature teratoma by pathology, the patient had significant recovery of her cognitive function with some psychotic sequela. Serum anti-neuronal antibody (anti-Hu) was negative both by immunohistochemistry and by Western blot analysis. A rare combination of paraneoplastic limbic encephalitis and brainstem encephalitis was the suspected diagnosis. Because the tumor contained a neuronal component, we propose an immunologic cross-reaction as the pathomechanism, but the lack of a specific antibody may suggest cell-mediated rather than globulin-mediated immunity.

Adult↗
PubMed1997

Bafilomycin A1, a specific inhibitor of V-type H+-ATPases, inhibits the acidification of endocytic structures and inhibits horseradish peroxidase uptake in isolated rat sinusoidal endothelial cells.

The role of vacuolar type H+-ATPases (v-ATPases) and pH gradient between the endocytic compartments and cytoplasm in the endocytosis of horseradish peroxidase, a mannose-terminated glycoprotein, was investigated morphologically in isolated rat sinusoidal endothelial cells. Toward this purpose, a specific inhibitor of v-ATPases, bafilomycin A1, was used to inhibit v-ATPases in the vacuolar system. Uptake of horseradish peroxidase was examined by electron microscopy. Fluorescent staining by acridine orange showed that bafilomycin A1 inhibited the acidification of the endocytic compartments. Horseradish peroxidase was taken up via mannose receptors and was distributed in the endocytic structures in the isolated sinusoidal endothelial cells. Uptake of horseradish peroxidase was significantly inhibited by bafilomycin A1, and this finding was confirmed by morphometrical analysis. These results suggest that: a) v-ATPases are necessary for acidification of the endocytic compartments in the sinusoidal endothelial cells and b) the pH gradient between the endocytic compartments and the cytoplasm that is generated by v-ATPases is necessary for the receptor-mediated endocytosis of a mannose-terminated glycoprotein, horseradish peroxidase.

Acridine Orange↗
PubMed1997

[Clinical evaluation of a reagent for detection of DNA of Mycobacterium tuberculosis complex using the ligase chain reaction (LCR) method].

We evaluated the clinical efficacy of LCR MTB, a reagent developed by Abbott in the USA, in the full automatic ligase chain reaction (LCR) for detection of DNA of M. tuberculosis complex using a thermostable ligase. Using 458 samples isolated from patients with tuberculosis, LCR was compared with a smear method and with a culture method, and was also compared with two other methods of gene amplification, MTD and Amplicor, using 340 and 200 of the 458 samples, respectively. The LCR method detected M. tuberculosis in 49.8% (228/458) of the samples, and was superior to the smear method (31.9%, 146/458) and the culture method (39.1%, 179/458) in sensitivity. The LCR method was also superior to the MTD and Amplicor methods; sensitivity were 37.9% (129/340) for MTD vs. 47.6% (162/340) for LCR, and 56.5% (113/200) for Amplicor vs. 59.5% (119/200) for LCR. These favorable results and the convenience of the LCR method, which enables rapid detection of target genes with a high degree of sensitivity, strongly suggest that LCR MTB is useful as a reagent for detection of M. tuberculosis using nucleic acid amplification.

Adolescent↗