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Biomedical subjects

K Oka

Publications and source records attributed to K Oka.

At least 271 records · Page 15Linked to original sources
PubMed1994

Internal Ca2+ mobilization is altered in fibroblasts from patients with Alzheimer disease.

The recent demonstration of K+ channel dysfunction in fibroblasts from Alzheimer disease (AD) patients and past observations of Ca(2+)-mediated K+ channel modulation during memory storage suggested that AD, which is characterized by memory loss and other cognitive deficits, might also involve dysfunction of intracellular Ca2+ mobilization. Bombesin-induced Ca2+ release, which is inositol trisphosphate-mediated, is shown here to be greatly enhanced in AD fibroblasts compared with fibroblasts from control groups. Bradykinin, another activator of phospholipase C, elicits similar enhancement of Ca2+ signaling in AD fibroblasts. By contrast, thapsigargin, an agent that releases Ca2+ by direct action on the endoplasmic reticulum, produced no differences in Ca2+ increase between AD and control fibroblasts. Depolarization-induced Ca2+ influx data previously demonstrated the absence of between-group differences of Ca2+ pumping and/or buffering. There was no correlation between the number of passages in tissue culture and the observed Ca2+ responses. Furthermore, cells of all groups were seeded and analyzed at the same densities. Radioligand binding experiments indicated that the number and affinity of bombesin receptors cannot explain the observed differences. These and previous observations suggest that the differences in bombesin and bradykinin responses in fibroblasts and perhaps other cell types are likely to be due to alteration of inositol trisphosphate-mediated release of intracellular Ca2+.

Adult↗
PubMed1994

Endoneurosurgical treatment for hydrocephalus caused by intraventricular tumors.

A flexible therapeutic ventriculoscope allowing for the use of a variety of different instruments has been developed. Endoneurosurgical instruments are composed of an endoscopic contact YAG laser endoprobe, grasping forceps and a punctured needle. Endoneurosurgical procedures include biopsies, III ventriculostomy, fenestration of the septum pellucidum, aspirations of cysts and excisions of tumors in the cerebrospinal fluid pathways. Our ventriculoscope allows the initial treatment for progressive hydrocephalus caused by intraventricular tumors to take the form of reducing ventricular size and decreasing intracranial pressure, and it can also be used to perform biopsy examinations, so that acceptable neurological outcomes and an accurate histological diagnosis can be obtained with fewer side effects. The subsequent therapies for hydrocephalus caused by intraventricular tumors include radical surgery for benign tumors, irradiation for radiosensitive tumors, and irradiation and/or chemotherapy for either malignant or disseminated tumors. We have tried to avoid the sequelae of shunt surgery and have achieved maximum effects with the minimum of procedures by using our ventriculoscope.

Adolescent↗
PubMed1994

Hepatotrophic activity in mouse serum infected with plerocercoids of Spirometra erinacei.

To investigate the mechanism by which liver weight increases during plerocercoid infections as well as the possible existence of a hepatocyte-growth-factor (HGF)-like substance in the serum of mice infected with Spirometra erinacei plerocercoids, liver DNA synthesis was measured in vivo and in vitro. Infection with S. erinacei plerocercoids significantly stimulated DNA synthesis in mouse parenchymal hepatocytes prior to the increase in liver weight, at least partly by stimulating the induction of the salvage pathways of pyrimidine biosynthesis. Furthermore, infected mouse serum directly stimulated DNA synthesis in cultured mouse parenchymal hepatocytes. These results suggest that an HGF-like substance is present in the serum of mice infected with S. erinacei plerocercoids.

Animals↗
PubMed1994

Ventriculoscope-guided ventriculoperitoneal shunt and shunt revision. Technical note.

A new small, flexible fiberoptic ventriculoscope for the accurate positioning of a ventricular catheter tip has been developed. The technique for ventriculoscope-guided ventriculoperitoneal shunt and shunt revision is described. The ventricular catheter can easily be positioned away from the choroid plexus. Choroid plexus adhering to the shunt tube can be coagulated during shunt revision. This procedure can thus prevent an obstruction of the ventricular catheter by an adherent choroid plexus.

Aged↗
PubMed1994

Natural flavonoids and lignans are potent cytostatic agents against human leukemic HL-60 cells.

Anti leukemic-cell efficacy of 28 naturally occurring and synthetic flavonoids and 11 naturally occurring lignans on human promyelocytic leukemic cell line HL-60 were examined using MTT assay methods. Differences between anti cell-proliferative activity and cytotoxicity of these compounds were compared with those of 4 clinical anti-cancer agents. Eight of the 28 flavonoids and 4 of the 11 lignans showed considerable suppressive effects on HL-60 cell growth with IC50s ranging from 10-940 ng/ml. Among these compounds, genistein, honokiol, machilin A, matairesinol, and arctigenin had the strongest effects with IC50s less than 100 ng/ml, which were almost equivalent to the effects of current anti-cancer agents. The flavonoid genistein and the lignans, however, showed little or no cytotoxicity against HL-60 cells as assessed by dye exclusion tests (LC50s > 2,900 ng/ml), whereas the regular anti-cancer agents had potent cytotoxicity. All of the flavonoids and lignans, except for machilin A and arctigenin, were less effective against growth of human T lymphocytic leukemia cell line MOLT-4. In addition, the flavonoid and the lignans showed little or no inhibiting activity on mitogen-induced blastogenesis of human peripheral-blood lymphocytes. The lignans and genistein were strongly suppressive against incorporations of [3H]thymidine, [3H]uridine, and [3H]leucine into HL-60 cells. These results showed that some of the naturally occurring flavonoids and lignans inhibited HL-60 cell growth with a non-toxic mechanism, possibly via cessation of DNA, RNA, and/or protein synthesis of the leukemic cells.

Antineoplastic Agents↗
PubMed1994

Percutaneous flexible neuroendoscopic ventriculostomy in patients with shunt malfunction as an alternative procedure to shunt revision.

Three patients with shunt malfunction, who had previously undergone a shunting procedure for noncommunicating hydrocephalus of adolescent and adult onset, successfully underwent a percutaneous flexible neuroendoscopic ventriculostomy. This procedure was performed as an alternative treatment for shunt revision by the use of our newly developed flexible fiberoptic ventriculoscope. All patients were able to remain independent of the shunt system after the ventriculostomy. These results thus suggest that a percutaneous flexible neuroendoscopic ventriculostomy can be effective for the treatment of shunt-dependent patients with shunt malfunction in adolescents and adults.

Adolescent↗
PubMed1994

Effects of stinging nettle root extracts and their steroidal components on the Na+,K(+)-ATPase of the benign prostatic hyperplasia.

The effects of organic-solvent extracts of Urtica dioica (Urticaceae) on the Na+,K(+)-ATPase of the tissue of benign prostatic hyperplasia (BPH) were investigated. The membrane Na+,K(+)-ATPase fraction was prepared from a patient with BPH by a differential centrifugation of the tissue homogenate. The enzyme activity was inhibited by 10(-4)-10(-5) M of ouabain. The hexane extract, the ether extract, the ethyl acetate extract, and the butanol extract of the roots caused 27.6-81.5% inhibition of the enzyme activity at 0.1 mg/ml. In addition, a column extraction of stinging nettle roots using benzene as an eluent afforded efficient enzyme inhibiting activity. Steroidal components in stinging nettle roots, such as stigmast-4-en-3-one, stigmasterol, and campesterol inhibited the enzyme activity by 23.0-67.0% at concentrations ranging from 10(-3)-10(-6) M. These results suggest that some hydrophobic constituents such as steroids in the stinging nettle roots inhibited the membrane Na+,K(+)-ATPase activity of the prostate, which may subsequently suppress prostate-cell metabolism and growth.

Humans↗
PubMed1994

A quantitative study of specific immunoglobulins to mosquito salivary gland antigen in hypersensitive and common types of mosquito bite reaction.

This study was designed with two purposes: first, to elucidate immunologic mechanisms in different cutaneous reactions, particularly in hypersensitivity to mosquito bites, and, second, to develop a more reliable and safer method of identifying the causative species of mosquito in severe cases. The amounts of IgG, IgG4 and IgE specific to the mosquito salivary gland extract of Aedes albopictus were determined in the sera of 116 volunteers with normal reactions, either immediate or delayed, and 4 patients with severe systemic symptoms caused by mosquito bites. Titers of IgG and IgE in the severe cases were considerably higher than in volunteers with normal reactions, but there were no differences in IgG4 titers between the two groups. These results indicate that high titers of IgG and IgE may be involved in development of systemic symptoms in severe cases and verify the possibility of in vitro tests to identify causative species of the mosquito.

Adolescent↗
PubMed1994

S100-positive histiocytes in T-cell-dependent area in human lymph nodes express P-glycoprotein.

In the present study, we examined P-glycoprotein (P-gp)-expressing cells in human lymph nodes (LN) from patients with reactive lymph adenitis and various malignant lymphomas (ML). MDR1 mRNA was detected in all reactive LN and in 8 of 10 ML samples examined by reverse transcription polymerase chain reaction (RT-PCR). The signal intensity of the bands was stronger in samples from T-cell ML LN than in those from LN of reactive lymph adenitis and B-cell ML. Immunohistochemistry also showed positive reactivity with cellular components in the LN. The P-gp-positive cells, detected by UIC2, in reactive lymph adenitis and ML samples were large in size in the T-cell-dependent paracortical area in LN. Further, morphological characteristics were similar in UIC2-positive cells between reactive and ML LN. Double staining with UIC2 and a hematopoietic cell lineage-specific monoclonal antibody showed that UIC2-positive cell co-expressed S-100, but not other lymphocyte- and ML cell-specific antigens, indicating that these cells correspond to histiocytes in the T-cell-dependent paracortical area. Our results show that P-gp was expressed in histiocytes but not ML cells in LN, and suggest that this molecule may play an important role in the biological function of histiocytes and/or for maintenance of homeostatic levels in T-cell ML LN.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1994

PRAD1 gene over-expression in mantle-cell lymphoma but not in other low-grade B-cell lymphomas, including extranodal lymphoma.

Employing Northern blot analysis and the polymerase chain reaction, we investigated PRAD1 gene overexpression in the tumour tissues of 58 patients with B-cell lymphoma. These findings were then examined in relation to the patients' clinical and immunohistological characteristics. The over-expression of this gene was detected in 6/8 patients with mantle cell lymphoma (MCL) and in only 1/50 other lymphomas, indicating its close association with MCL. The patients with MCL had common clinical findings of advanced disease with generalized lymphadenopathy on admission, and they had a CD5+CD10-IgD+ phenotype. The patients with chronic lymphocytic leukaemia (CLL) also showed findings indicating a distinctive disease entity: a CD5+CD10-IgD+ phenotype and lack of PRAD1 over-expression. In contrast, most patients with diffuse low-grade lymphoma other than MCL and CLL had localized extranodal disease, expressed a CD5-CD10-IgD- phenotype, and lacked PRAD1 over-expression. These findings suggest that extranodal low-grade lymphomas differ from nodal MCL and are not part of the spectrum of CLL.

Base Sequence↗
PubMed1994

Primary gastric Ki-1 positive anaplastic large cell lymphoma: a report of two cases.

Two cases with primary gastric Ki-1 positive anaplastic large cell lymphoma are presented. Morphologic features of both cases involved pleomorphism of the neoplastic cells, fibrosis and lymphatic infiltration. The neoplastic cells in both cases were positive for BerH2 (CD30), LCA(CD45), lysozyme and alpha-1-antitrypsin (alpha 1-AT). In additional case, the neoplastic cells were additionally positive for MAC387 and alpha 1-antichymotrypsin (alpha 1-ACT). The neoplastic cells in these cases were negative for L26(CD20), UCHL-1(CD45RO), DAKO CD3 and epithelial membrane antigen (EMA). According to the results of the phenotypic studies, the authors consider that the neoplastic cells have some of the features of histiocytes. Both patients at 2 and 8 years after surgery without chemotherapy are disease free. This lymphoma is well known to be frequently misdiagnosed as undifferentiated carcinoma. Although rare in occurrence, recognition of this primary lymphoma in the stomach has a significant clinical implication, as the authors consider that its prognosis might be better than undifferentiated carcinoma of the stomach.

Adult↗
PubMed1994

A novel 11 beta-hydroxysteroid dehydrogenase inhibitor contained in saiboku-to, a herbal remedy for steroid-dependent bronchial asthma.

To identify the inhibitor of prednisolone metabolism contained in Saiboku-To, we conducted in-vitro experiments of 11 beta-hydroxysteroid dehydrogenase (11 beta-HSD), using rat liver homogenate and cortisol as a typical substrate. We studied the effects of ten herbal constituents on 11 beta-HSD. Five herbal extracts showed inhibitory activity with Glycyrrhiza glabra > Perillae frutescens > Zizyphus vulgaris > Magnolia officinalis > Scutellaria baicalensis. This suggests that unknown 11 beta-HSD inhibitors are contained in four herbs other than G. glabra which contains a known inhibitor, glycyrrhizin (and glycyrrhetinic acid). Seven chemical constituents which have been identified as the major urinary products of Saiboku-To in healthy and asthmatic subjects were studied; magnolol derived from M. officinalis showed the most potent inhibition of the enzyme (IC50, 1.8 x 10(-4) M). Although this activity was less than that of glycyrrhizin, the inhibition mechanism (non-competitive) was different from a known competitive mechanism. These results suggest that magnolol might contribute to the inhibitory effects of Saiboku-To on prednisolone metabolism through inhibition of 11 beta-HSD.

11-beta-Hydroxysteroid Dehydrogenases↗
PubMed1994

[A prospective study of septic episodes due to Staphylococcus aureus and the background of the patients].

From January 1983 to December 1991, 94 cases of Staphylococcus aureus septicemia were identified at Matsue Red Cross Hospital and were evaluated. Methicillin-resistant Staphylococci aureus counted 49%. Seventy two percent of the patients were 60 years or over in age. Intravascular catheters were the most common foci (33%), respiratory infections in 25% and so on. Administration of antibiotics before isolation of Staphylococcus aureus were thought to be the most significant factor in producing the methicillin-resistant septicemia, used in 41% of MSSA and 91.3% of MRSA cases. Especially, the trend of unproper usage of the 3rd generation cephems derivative antibiotics had a major role in producing multi-drug resistant bacteria. No significance was seen in the clinical background, underlying diseases, primary site of infection in between the two groups of methicillin resistant and sensitive cases. Mortality due to septicemia was 47.9% in the MSSA group of patients, while it was much higher in cases of MRSA (73.9%). In conclusion, as the administration of antibiotics even in non-infectious episodes is common in daily clinical activities in some out-patient clinics, the indications should be restricted, in order to prevent the further MRSA infections.

Adolescent↗
PubMed1994

Effects of oral AVP receptor antagonists OPC-21268 and OPC-31260 on congestive heart failure in conscious dogs.

Rapid right ventricular pacing could induce congestive heart failure in conscious dogs with significant increase in plasma concentration of arginine vasopressin (AVP) (from 1.2 +/- 0.2 to 3.4 +/- 0.6 pg/ml). In this experimental model of heart failure, oral administration of the selective AVP V1 receptor antagonist OPC-21268 significantly increased cardiac output and improved renal function without significant changes in serum electrolytes and hormones. Oral administration of the selective AVP V2 receptor antagonist OPC-31260 induced marked water diuresis, which resulted in significant increases in serum sodium concentration, plasma renin activity, and plasma concentration of AVP, although it did not produce hemodynamic improvement. Combined administration of OPC-21268 and OPC-31260 showed supra-additive hemodynamic responses as well as additive renal and metabolic responses, i.e., it showed prolonged decrease in mean arterial pressure and profound increase in cardiac output. These results suggest that AVP plays a significant role in elevation of vascular tone through V1 receptors and plays a major role in retaining free water through V2 receptors in this model of heart failure. Furthermore, combined administration of V1 and V2 receptor antagonists could induce not only metabolic and hormonal responses but also more beneficial hemodynamic responses than those observed following treatment with V1 receptor antagonist alone.

Animals↗
PubMed1994

Ki-1-positive anaplastic large cell lymphoma with different phenotypes in skin nodules and lymph nodes.

A 54-year-old man had lymph node swelling and skin nodules. Neoplastic cells with pleomorphic nuclei, prominent eosinophilic nucleoli and abundant cytoplasm were present in the lymph node sinuses and around the dermal appendages. Neoplastic cells in the lymph nodes expressed Ber-H2 (CD30)+/KP1 (CD68)+/MAC387-/LN-5+. Those in the skin nodules expressed Ber-H2+/KP1-/MAC387+/LN-5-. These findings suggest that he had Ki-1-positive anaplastic large cell lymphoma (ALCL) with different phenotypes in lymph nodes and skin nodules. The discrepancy among KP1, MAC387 and LN-5 reactivities may represent the concurrent occurrence of ALCL and lymphomatoid papulosis. However, the possibility cannot be ruled out that ALCL developed first in the lymph nodes and then metastasized to the skin.

Antigens, CD↗
PubMed1994

Long-term infusion of kallikrein attenuates renal injury in Dahl salt-sensitive rats.

We investigated whether long-term infusion of kallikrein would attenuate renal injury in salt-induced hypertension in Dahl salt-sensitive rats. A subdepressor dose of purified rat urinary kallikrein (700 ng/d IV) was infused by osmotic minipump for 4 weeks in male Dahl salt-sensitive rats fed a high salt (2% NaCl) diet. This dose did not affect the time-dependent elevation of blood pressure; however, urinary protein excretion was significantly decreased, and glomerular filtration rate was increased. These beneficial effects were reflected morphologically by an attenuation of glomerulosclerotic lesions and tubular injury seen in the hypertensive Dahl salt-sensitive rats. Kallikrein infusion increased urinary excretion of bradykinin and stimulated excretion of cyclic GMP, suggesting that the kallikrein-kinin-prostaglandin and nitric oxide axes were enhanced by rat urinary kallikrein infusion. The alterations induced by kallikrein infusion were potentiated by the concomitant administration of the angiotensin-converting enzyme inhibitor alacepril. These studies indicated that long-term replacement with rat tissue kallikrein attenuates renal injury in hypertensive Dahl salt-sensitive rats.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1994

Structural and conformational studies of [Ile7] and [Leu7]surfactins from Bacillus subtilis natto.

A novel [Ile7]surfactin (1), which showed anti-human immunodeficiency virus activity, has been isolated from Bacillus subtilis natto. Structural and conformational analysis of the peptide backbone of [Ile7]surfactin was conducted by a combination of various two-dimensional (2D) nuclear magnetic resonance (NMR), circular dichroism (CD) spectroscopy and simulated annealing calculations, compared with a known [Leu7]surfactin (2). Both surfactins were shown to exist in different conformational states in both polar and apolar solvents.

Amino Acid Sequence↗