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Biomedical subjects

M Oka

Publications and source records attributed to M Oka.

At least 289 records · Page 16Linked to original sources
PubMed1996

A comparison of glandular involvement between chronic graft-versus-host disease and Sjögren's syndrome.

Patients with chronic graft-versus-host disease (cGVHD) occasionally suffer from symptoms of xerostomia and xerophthalmia, which are also features of Sjógren's syndrome (SS). To identify differences in the glandular involvement between cGVHD and SS, we measured the proportions of infiltrating lymphocyte subsets and the expression of HLA-DR antigen and cell adhesion molecules in labial salivary glands (LSG). In cGVHD, more than 90% of the infiltrating lymphocytes were T cells with a slight predominance of CD8+ over CD4+ cells. In SS, CD4+ cells were predominant, and B cells accounted for 10-30% of the infiltrating lymphocytes. Ductal epithelial cell associated with lymphocytic infiltration expressed HLA-DR antigen in both cGVHD and SS. In SS alone, HLA-DR antigen expression also occurred without associated lymphocytic infiltration. The expression of adhesion molecules on ductal epithelial cells, especially vascular cell adhesion molecule 1, was more intense in SS than in cGVHD, while that on endothelial cell was similar in cGVHD and SS. These data suggest that the pathogenesis of glandular involvement of cGVHD is different from that of SS.

Adolescent↗
PubMed1996

Expression of extracellular matrix in human mandibular condyle.

OBJECTIVE: The age-related expression of the extracellular matrices in human mandibular condyle was examined. STUDY DESIGN: The distribution patterns of types I to V collagens, laminin, fibronectin, fibronectin receptor, and transforming growth factor beta in 34 human mandibular condyles dissected from autopsy specimens were studied by immunohistochemical procedure with special attention on the age-related changes. RESULTS: Type I collagen was detected in the full layer of the condylar cartilage, and a stronger immunoreaction was delineated in the articular and cartilage zone. Types II and III collagen were mainly localized in the fibrocartilage zone. Type IV collagen and laminin were detected not only in the basement membrane of the blood vessels but also in the degenerated lesion where the expression of transforming growth factor beta was also detected. Immunostaining of type V collagen and fibronectin was noted in the perichondrocytic area, whereas that of fibronectin receptor was seen in the chondrocytes. In materials from younger cadavers types I, II, IV and V collagens, fibronectin, its receptor, and laminin showed stronger expression in the degenerative lesions than in the normal portions. In the sections from cadavers over the seventh decade, the immunoreaction of extracellular matrices was weak compared with the younger materials, and no increased reaction of extracellular matrices in the degenerative lesions was detected. In addition, severe osteoarthrosis was frequently seen in the older materials in macroscopic findings. CONCLUSION: These results suggest that the expression of extracellular matrices thus seems to be closely related to aging and degenerative changes in the condyle.

Adolescent↗
PubMed1996

Protein kinases are involved in prolonged acetylcholine release from rat hippocampus induced by thyrotropin-releasing hormone analogue NS-3.

The effects of various protein kinase inhibitors on acetylcholine release from the rat hippocampus induced by the local application of NS-3 (montirelin hydrate, CG-3703), a thyrotropin-releasing hormone analogue, into the medial septum-diagonal band were examined using in vivo microdialysis. Perfusion of NS-3 (1 microM) into the medial septum-diagonal band for 20 min produced a pronounced and prolonged increase in the hippocampal acetylcholine efflux. Pretreatment of the medial septum-diagonal band with either K-252a, a nonselective protein kinase inhibitor, or selective protein kinase A inhibitor H-89 almost completely blocked the acetylcholine efflux evoked by NS-3, and selective protein kinase C inhibitor calphostin C inhibited the action of NS-3. On the other hand, NS-3 (0.1-10 microM) or TRH (1-100 microM) increased the cyclic AMP efflux from the medial septum-diagonal band in a concentration-dependent manner, as measured by microdialysis. These findings suggest that protein kinases A and C in the neurons of the medial septum-diagonal band are involved in the mechanism of the prolonged stimulation of acetylcholine release from the hippocampus induced by thyrotropin-releasing hormone and its analogue, NS-3.

Acetylcholine↗
PubMed1996

Influence of continuous interleukin-2 administration via the portal vein on liver regeneration following partial hepatectomy in rats.

We have reported the efficacy of intraarterial-combined immunochemotherapy including interleukin-2 (IL-2) for unresectable hepatocellular carcinoma (HCC). To further test this therapy for prevention of intrahepatic recurrence after hepatectomy, the influence of IL-2 on liver regeneration was examined using mitotic index (MI) and the bromodeoxyuridine (BrdU) labeling index (LI) in 70% hepatectomized Donryu rats. In addition, gap junction appearance, which may change during liver regeneration, was analyzed using a monoclonal antibody (HAM8). Serum albumin, alanine transaminase, and total bilirubin (TB) levels were also evaluated. IL-2 (45,000 Japanese reference units [JRU]/d) or saline was administered continuously via the portal vein immediately after hepatectomy using an infusion pump. We also examined the influence of IL-2 on liver regeneration after hepatectomy with splenectomy. No difference in the weight of the liver, serum albumin, alanine transaminase, or TB was observed in any groups at 1, 2, or 4 days after hepatectomy. Neither IL-2 nor splenectomy influenced MI and BrdU LI at all three points. Gap junctions began to disappear after hepatectomy and reached a minimum on day 2 in all groups. Four days after hepatectomy, the density of the reappearing gap junctions was markedly lower in groups treated with IL-2 than in those receiving saline with or without splenectomy. However, the density returned to close to preoperative levels 6 days after hepatectomy in all groups. Continuous portal infusion of IL-2 transiently disturbed gap junction reappearance during liver regeneration. However, no other parameters of liver regeneration or liver functions differed. These results suggest that the liver regeneration after partial hepatectomy may be suppressed by the administration of IL-2, even though the suppression may not be harmful for overall recovery of the resected liver. However, it seems that hepatic IL-2 administration can be performed without serious complications after hepatectomy.

Alanine Transaminase↗
PubMed1996

The influence of interleukin-6 on the growth of human esophageal cancer cell lines.

We reported that human esophageal cancer cell lines (ECC) (YES-1, -2, -3, -4, -5, and -6) produced interleukin-6 (IL-6). We, therefore, investigated the growth effects ([3H]thymidine uptake assay and direct cell count) of IL-6 on these ECC. IL-6 receptor (R) and GP-130 mRNA were detected in all the ECC, using reverse transcriptase-polymerase chain reaction (RT-PCR) assay, and IL-6R was detected in one (YES-3) by immunohistochemical staining. IL-6, anti-IL-6 monoclonal antibody (mAb), or anti-IL-6R mAb caused no reproducible enhancement or suppression of [3H]thymidine uptake by all six ECC. Direct cell count also revealed that the growth enhancement or suppression by IL-6, anti-IL-6 mAb, or anti-IL-6R mAb was relatively small. Particularly, there was no significant sensitivity of YES-3 cells, which definitely produce IL-6 and express IL-6R for IL-6, anti-IL-6 mAb, or anti-IL6R mAb. These results suggest that some esophageal cancers may produce IL-6 and express IL-6R. However, no major interactions between IL-6 and the growth of human esophageal cancer cell lines were detected in this study.

Antibodies, Monoclonal↗
PubMed1996

Liposomal amikacin: improved treatment of Mycobacterium avium complex infection in the beige mouse model.

Disseminated Mycobacterium avium complex (MAC) infection has reached epidemic proportions and is a major cause of morbidity and mortality in AIDS patients. We have developed a liposomal preparation of amikacin, VS107, which incorporates the drug in 54-65 nm diameter unilameller phospholipid vesicles and is stable at 4 degrees C for more than 4 months. VS107 exhibits superior microbiological and pharmacological activity over the free amikacin and improves the survival of mice in the established model for MAC infection. The serum half-life of VS107 in mice was 9.1 h and a peak serum level of 730 mg/L was obtained after administering three doses of 160 mg/kg. For the therapeutic study, beige mice infected with 10(7) cfu M. avium complex strain 101 were randomised to be treated with placebo liposomes, buffer, free amikacin or VS107 The drugs were administered via the caudal vein thrice weekly for 1, 3, 5 or 7 weeks beginning 5 days after infection. After 51 days of treatment with VS107, the number of viable M. avium in the liver and spleen was a 100 fold lower than was achieved with conventional amikacin (P < 0.01), and more than six decimal logarithms lower than was found untreated controls (P < 0.001). VS107 was well tolerated and might be a suitable candidate for treating human MAC infections.

Amikacin↗
PubMed1996

Induction of Fas-mediated apoptosis on circulating lymphocytes by surgical stress.

OBJECTIVE: The authors determined whether the decrease in lymphocytes after surgery is related to apoptosis. SUMMARY BACKGROUND DATA: Surgery induces a profound but transient depletion of circulating lymphocytes, However, the mechanism underlying this phenomenon is unclear. METHODS: Peripheral blood mononuclear cells were obtained from 18 patients before and after elective surgery and studied for morphologic and biochemical markers of apoptosis, DNA fragmentation, and Fas expression. RESULTS: The DNA staining of peripheral blood mononuclear cells obtained after surgery, which had been cultured for 24 hours in vitro, showed chromatin condensation and fragmentation of cells into collapsed spheres. Moreover, DNA isolated from these peripheral blood mononuclear cells formed a ladder of oligonucleosomal fragments. However, peripheral blood mononuclear cells obtained before surgery showed neither of these changes. The observation that none of these apoptotic cells ingested latex suggested that they were of lymphocytic origin. Fas-positive lymphocytes increased significantly 2 hours after the start of surgery and returned to preoperative levels by postoperative day 7. Anti-Fas antibody augmented apoptosis, whereas ZB4, a Fas antagonist, inhibited apoptosis in lymphocytes after surgery. CONCLUSIONS: These results indicate that circulating lymphocytes in the early perioperative period are susceptible to Fas-mediated apoptosis, which may cause depletion of circulating lymphocytes after surgery.

Adult↗
PubMed1996

A topoisomerase II inhibitor, NK109, induces DNA single- and double-strand breaks and apoptosis.

2,3-(Methylenedioxy)-5-methyl-7-hydroxy-8-methoxybenzo[c]phenanthr idinium hydrogensulfate dihydrate, called NK109, is a benzo[c]phenanthridine derivative, which inhibits DNA topoisomerase II activity by stabilizing the DNA-enzyme-drug complex, and shows strong growth-inhibitory effects on several human cancer cells. In the present study, NK109 treatment induced DNA fragmentation and a rise in the level of cytoplasmic nucleosomes, which are markers of apoptosis, in human small-cell lung carcinoma SBC-3 cells. These effects were inhibited by zinc ions and enhanced by cycloheximide or actinomycin D. Dose-dependent single- and double-strand DNA breaks were observed, using alkaline and neutral elution assays, in SBC-3 cells treated with more than 0.2 microM NK109 for 4 h. Treatment with NK109 caused more DNA single- and double-strand breaks than treatment with an equimolar amount of VP-16. These results suggest that NK109 induces DNA strand breaks and apoptosis. In addition, it appears that this process does not require protein or RNA synthesis, but involves a specific endonuclease which is inhibited by zinc ions.

DNA↗
PubMed1996

The multidrug resistance-associated protein gene confers drug resistance in human gastric and colon cancers.

To determine the expression of multidrug resistance-associated protein (MRP) gene and its role in gastric and colon cancers, we analyzed 10 gastric and 10 colon non-drug-selected cell lines and a similar number of tissue samples of these cancers. We compared the expression of MRP and mdrl mRNA in cell lines and tissues using reverse-transcriptase polymerase chain reaction. In mdrl-negative cells, the relationship between the level of MRP gene expression and sensitivity to anticancer drugs was examined. The effect of verapamil, an MRP-modulating agent, was also examined in these cells. The expression of MRP gene in gastric cancer cell lines varied from a low to a high level, but mdrl was not detected in any of these cell lines. Colon cancer cell lines expressed low to intermediate levels of MRP gene, and half of the cells co-expressed low to high levels of mdrl. In tissue samples, the expression pattern of the two multidrug resistance (MDR) genes was broadly similar to that described for the cell lines, except that most of the gastric cancer tissue samples did express low levels of mdrl. No significant correlation was observed between the level of MRP gene expression and sensitivity to anticancer drugs in gastric and colon cell lines. However, verapamil significantly increased the sensitivity to etoposide, doxorubicin and vincristine in cells highly expressing MRP gene. Our results indicate that MRP gene may be important in conferring MDR in gastric and colon cancer cells.

Antineoplastic Agents↗
PubMed1996

Levels of recombinant human granulocyte colony-stimulating factor in serum are inversely correlated with circulating neutrophil counts.

Recombinant human granulocyte colony-stimulating factor (rhG-CSF) is effective in countering chemotherapy-induced neutropenia. However, serum rhG-CSF levels cannot be maintained throughout the course of rhG-CSF therapy. The drop in serum rhG-CSF levels may vary with the duration of rhG-CSF administration or with the circulating neutrophil counts. We investigated the relationship between serum G-CSF levels and circulating neutrophil counts and the pharmacokinetics of rhG-CSF for patients with lung cancer who had been treated with myelosuppressive chemotherapy and then with subcutaneous rhG-CSF (lenograstim, 2 micrograms per kg of body weight per day). Twelve patients were randomly assigned to four groups with different rhG-CSF therapy schedules. Serum G-CSF levels were measured by an enzyme immunoassay method. Serum G-CSF levels during the rhG-CSF therapy greatly exceeded endogenous G-CSF levels and were mainly due to the presence of exogenous rhG-CSF rather than increased levels of endogenous G-CSF. Despite the duration of rhG-CSF administration, serum G-CSF levels during rhG-CSF therapy were inversely correlated with circulating neutrophil counts (r2 = 0.73, P < 0.0001). The value for the area under the concentration-time curve of rhG-CSF on the day of neutrophilia was lower than that on the day of neutropenia (P < 0.05). Our results suggest that the fall in serum G-CSF levels during rhG-CSF therapy may result from increased clearance and/or decreased absorption of rhG-CSF, two processes related to circulating neutrophil counts.

Aged↗
PubMed1996

Altered vasoreactivity in lungs isolated from rats exposed to nitric oxide gas.

A rebound phenomenon (severe arterial desaturation and pulmonary vasoconstriction) has been observed in some patients with pulmonary hypertension after sudden discontinuation of nitric oxide (NO) inhalation therapy. The mechanism responsible for this phenomenon is unknown. It has recently been reported that NO synthase (NOS) can be inhibited by NO as a negative feedback mechanism. We therefore hypothesized that this rebound phenomenon might be attributable to reduced endogenous NO production due to inhibition of pulmonary endothelial NOS (eNOS) activity by inhaled NO. To test this hypothesis, vasoreactivities were compared in isolated perfused lungs from rats exposed to 40 ppm NO gas and room air for 2 days. The pressor responses to angiotensin II and hypoxia of lungs from rats exposed to NO were markedly potentiated and their depressor response to bradykinin was considerably impaired, whereas that to sodium nitroprusside was preserved, compared with the responses of those exposed to room air. This altered pulmonary vasoreactivity was also induced by lower concentrations of inhaled NO (as low as 1 ppm) and was completely reversed by discontinuation of NO inhalation for several (< 8) hours. The expression of eNOS mRNA by lungs isolated from rats exposed to 40 ppm NO and room air for 2 days did not differ. These results suggest that pulmonary endogenous NO production is reversibly reduced after relatively short-term NO inhalation, which probably inhibits eNOS activity directly. We speculate that reduced production of pulmonary endogenous NO by exogenous (inhaled) NO could be the mechanism responsible for this rebound phenomenon.

Administration, Inhalation↗
PubMed1996

Enzymatic hydrolysis of copoly(N-hydroxypropyl-L-glutamine/L-leucine) hydrogels in vitro.

Two component random copolypeptide hydrogels consisting of N-hydroxyalkyl L-glutamine and L-leucine were prepared by carrying out aminolysis reactions with 3-amino-1-propanol(P) together with cross-linking reactors with 1,8-octamethylenediamine (OMDA) on hydrogels of the starting copolymers consisting of gamma-methyl-L-glutamate(M) and L-leucine(L). The relation between their bulk structure and properties was investigated with regard to the swelling ration in water, aqueous vapor permeability, tensile properties, and enzymatic degradation behavior in a pseudoextracellular fluid (PECF). The tensile property of the hydrogels was highly dependent on the swelling ratio in PECF, and on the hydrophobicity of the side chains, whose behavior was typical of an elastomer. It was shown that a common relation was obtained between the rate of water vapor permeabilities and the swelling ratio of hydrogels in PECF regardless of the difference of the nature of side chains. Biodegradation of the hydrogels in vitro by bromelain indicated that the degradation took place in bulk rather than on surface, and that the rate of degradation was also highly dependent on the swelling ratio of samples as well as on the hydrophobicity of the side chains of samples.

Biocompatible Materials↗
PubMed1996

Chronic bronchial foreign body mimicking peripheral lung tumor.

We describe a case with chronic bronchial foreign body presenting with recurrent hemoptysis mimicking a peripheral lung tumor, and the outcome of surgical resection. A 61-year-old female with recurrent hemoptysis had a peripheral nodule in the right lower lobe. A right bronchial arteriogram showed dilatation and hypervascularity in the nodule. Surgical removal of the nodule contained a small branch of a white cedar. Chronic bronchial foreign body, while rare in adults, should be considered in the differential diagnosis of peripheral lung tumors associated with recurrent hemoptysis.

Angiography↗
PubMed1996

A prospective study of bronchoscopy for endotracheobronchial tuberculosis.

To clarify the role of bronchoscopy for endotracheobronchial tuberculosis (EBTB), we performed a prospective study in 45 patients with active pulmonary tuberculosis, in 15 (33%) of whom bronchoscopic findings related to EBTB were seen. The findings were classified into six types:edematous hyperemic, submucosal nodule, ulcerative (shallow and deep), polypoid, cicatrical, and compression type. Each of these types was related to the healing process and outcome after antituberculosis chemotherapy. Serial bronchoscopy revealed that lesions less advanced than the deep ulcerative type responded to chemotherapy; the deep ulcerative and polypoid types progressed to cicatrical bronchostenosis despite chemotherapy. In the follow-up of patients with lesions of the deep ulcerative and polypoid types, serial bronchoscopy after chemotherapy is recommended; these patients also require adjunctive therapy to prevent cicatrical bronchostenosis.

Biopsy↗
PubMed1996

Two types of K+ currents underlying inward rectification of rat osteoclast membrane: a single-channel analysis.

1) Electrical membrane properties of spread type-osteoclasts were examined using the whole-cell and cell-attached configurations of the patch clamp technique. The membrane potential of the osteoclasts was measured and grouped into two populations: hyperpolarized and depolarized (around -80 and 0 mV, respectively). The current-voltage relation was N-shaped, showing the property of inward rectification which was produced by K+ conductance. Either Na+ or Ca2+ inward currents were not observed. 2) The single-channel recordings were made with osteoclasts of the hyperpolarized population. Two types (slow and fast) of the current were analyzed, which appeared predominantly and had large unit conductances. The reversal potential for both types shifted according to the equilibrium potential for K+. 3) The slow type had high open probabilities (> or = 0.85) at all potentials examined. The mean open time was 349 ms at the resting potential (RP) and had a tendency to become shorter with hyperpolarization of the membrane. The closed time histogram was fitted with a double exponential function, yielding closed times of 8.3 and 55.2 ms at RP, which were not changed by hyperpolarization. The unit conductance was 32.0 pS. No outward currents were recorded at depolarized potentials to RP. 4) The open probability of the fast type was 0.25 at RP and increased with hyperpolarization of the membrane (0.55 at -80 mV to RP). The mean open time was short (2.6 ms at RP), which became longer with hyperpolarization. The channel had two closed times, 2.8 and 15.3 ms at RP, which were not voltage dependent. The unit conductance was 38.8 pS in the range of hyperpolarization from RP. The amplitude of outward currents evoked by voltage pulses beyond RP was small, probably due to rapid flickering of the current. 5) The two types of single-channel K+ currents showed the inwardly rectifying property and may play an important role in the inward rectification seen in the whole-cell configuration.

Animals↗