Biomedical subjects

R Tanaka

Publications and source records attributed to R Tanaka.

At least 307 records · Page 17Linked to original sources

PubMed1996

Role of glycoprotein 130 and c-Kit signaling in proliferation and differentiation of human hematopoietic progenitor cells.

Glycoprotein (gp) 130, a receptor component for interleukin 6 (IL-6), can associate with a soluble IL-6 receptor (sIL-6R)-IL-6 complex. To examine the role of gp130 signaling in human hematopoietic progenitor-cell proliferation and differentiation, we studied the effects of the sIL-6R-IL-6 complex in combination with other cytokines on human CD34+ cells in clonal and suspension cultures. The sIL-6R-IL-6 complex, but not sIL-6R or IL-6 alone, in the presence of stem-cell factor (SCF) produced dramatic increases in the populations of various cell lineages, including erythroid cells and various hematopoietic progenitors, in suspension culture. Significant numbers of colonies of (particularly) multilineage and blast cells were generated in methylcellulose culture supplemented with a combination of sIL-6R-IL-6 complex and SCF. Addition of anti-gp130 monoclonal antibodies (MAbs) and anti-IL-6R MAbs to the above-mentioned cultures dose-dependently inhibited the generation of cells of various lineages and of progenitor cells in suspension culture and completely blocked multilineage colony production in methylcellulose culture; an anti-erythropoietin antibody did not cause inhibition. These findings demonstrate that both proliferation and differentiation of hematopoietic progenitor cells can be induced through gp130 and c-Kit signaling, indicating that progenitor cells are responsive to the sIL-6R-IL-6 complex, even though they do not express IL-6R. Together with previous studies showing that detectable levels of sIL-6R, IL-6, and SCF are present in human serum, these results suggest that gp130 signaling may play an important role in human hematopoiesis in vivo.

Antigens, CD34↗

PubMed1996

Promotion of microfilament polymerization by depolymerized glia filament preparation through interaction of vimentin with actin.

We investigated the in vitro interaction between microfilaments and glia filaments in the presence of alpha-sialosylcholesterol (SC). The depolymerized glia filament preparation (GF) that had been extracted from a crude cytoskeletal fraction of cultured rat astrocytes promoted markedly the polymerization of the depolymerized microfilament preparation (MF) in the presence of SC. The ability of GF to promote the MF polymerization was highest in the concentration range 7.5-15 microM SC. The polymerization of MF at the concentration of 10 micrograms protein/200 microliters was enhanced to the highest level by 4 micrograms protein/200 microliters of GF in the presence of 15 microM SC. The MF polymerization was promoted more efficiently by GF than by MF: for example, the polymerization of actin in MF (7.5 micrograms/200 microliters) was enhanced by the addition of 5 micrograms GF protein/200 microliters to a twice greater extent than by the addition of 5 micrograms MF protein/200 microliters in the presence of 15 microM SC. GF enhanced the MF polymerization by over three-fold at 4-37 degrees C, and the GF activity became greater with an increase in incubation temperature. Vimentin promoted the G-actin polymerization in the presence of 11.3 microM alpha-SC. The finding suggested that the interaction between vimentin and actin was one of the factors to cause GF to promote the MF polymerization.

Actin Cytoskeleton↗

PubMed1996

Analysis of neuronal death in the central nervous system using a new apoptosis model.

To examine in detail neural apoptosis in the central nervous system (CNS) for the establishment of new therapies, we have developed an experimental in vitro model of neuronal death and analyzed the mechanism of apoptosis. Septal nuclei were dissected from embryonic brains (E16) of Wistar rats and cultured in chemically defined medium. Highly enriched neurons were obtained from the cultures at 4 days. Exposure to heat shock (43.0 degrees C, 60 min) between 24 and 36 h later, resulted in the death of approximately 70% of cells. Morphologically, dying neurons showed disruption of neurites, nuclear condensation, multiple nuclear fragments, condensation of cytoplasm and multiple cellular fragmentation. Agarose electrophoresis of chromosomal DNA revealed a typical ladder-pattern of fragmentation. Following heat treatment, incubation at 37 degrees C was necessary to detect DNA fragmentation. Quantitative analysis by in situ terminal deoxynucleotidyl transferase assay, revealed that the percentage of apoptotic cells markedly increased 8 h after heat treatment, and continued to gradually increase up until 30 h. Neuronal death and DNA fragmentation were prevented by inhibiting RNA and protein synthesis. Cell death and the DNA cleavage were also inhibited by cultivation in calcium-free medium. The addition of homogenous basic fibroblast growth factor to the medium markedly enhanced cell survival under these pathogenic conditions. These results suggest that neural cell death after mild heat treatment has apoptotic characteristics and may be useful for analyzing the mechanism of apoptosis. The clinical application of drugs acting against molecular components and as well as neurotrophic factors, may in the future prevent apoptosis in neural disease.

Animals↗

PubMed1996

Problems and priorities for controlling opportunistic pathogens with new antimicrobial strategies; an overview of current literature.

An International Study Group on New Antimicrobial Strategies (ISGNAS) has been formed in response to the recognition that development of microbial resistance to antibiotics is becoming a serious, world-wide problem. The group met in 1993 for the first time to discuss the feasibility of developing rational alternatives to the use of antibiotics and prepared, as a result, a comprehensive overview of normal (physiological) mechanisms involved in the control of potentially pathogenic (oppotunistic) microorganisms. One objective of ISGNAS is to understand the conditions which allow opportunistic microbes present among the symbionts to cause an infection. There is a need for more coherent information concerning the habitat, growth requirements and host and pathogen properties which allow opportunistic pathogens to cause life-threatening infections. In particular, information is urgently being sought to understand the complexity of the interactions between the vast number of microbial species, and the interactions between the microbes and their host. Another goal is to inspire and enable basic and clinical research that will lead to the development of new therapies for regulating colonization, translocation and infection by opportunistic micro-organisms in patients during periods of decreased resistance. With a sufficient amount of knowledge of how healthy individuals keep opportunistic micro-organisms under control, it may become feasible for physicians to maintain host resistance and inter-microbial factors involved in the containment of opportunistic microbes. Therapies aimed at boostering natural resistance mechanisms will be of critical importance to individuals whose resistance has been compromised as a result of another clinical condition.

Adjuvants, Immunologic↗

PubMed1996

Characterization of peripheral blood progenitor cells (PBPC) mobilized by filgrastim (rHuG-CSF) in normal volunteers: dose-effect relationship for filgrastim with the character of mobilized PBPC.

Filgrastim (rHuG-CSF)-mobilized peripheral blood progenitor cells (PBPC) in healthy Japanese volunteers were characterized in detail using two clonal cell culture systems and double-colour flow cytometry to detect multilineage colony-forming cells and subsets of CD34+ cells. The kinetics of PBPC during the administration of filgrastim was studied, and possible differences in the character of progenitor cells relative to given doses of filgrastim were investigated. Filgrastim was administered subcutaneously to normal volunteers for 7 d at doses of 100, 200 or 400 microgram/m2 (10 per cohort). Treatment with 100 or 200 microgram/m2 filgrastim was well tolerated; however, the 400 microgram/m2 dose level was not completed because of bone pain and myalgia. The treatment strikingly mobilized various types of progenitor cells, including highly proliferative megakaryocytic colony-forming cells. The number of progenitor cells peaked on days 5 and 6. The fold increase of circulating progenitor cells from the baseline value in the volunteers treated with 200 microgram/m2 filgrastim was more pronounced than in those treated with 100 microgram/m2. Treatment with 200 microgram/m2 also released the less mature progenitor cells (i.e. mixed colony-forming cells CD34+/33- cells, and CD34+/HLA-DR-cells) into circulation better than the 100 microgram/m2 dose. These results suggest that daily subcutaneous injection with 200 microgram/m/2 filgrastim for 5 d will effectively mobilize, both qualitatively and quantitatively, PBPC in healthy donors.

Adult↗

PubMed1996

A possible change in doubling time of haemopoietic progenitor cells with stem cell development.

We separated haemopoietic progenitors derived from marrow cells of 5-fluorouracil (5-FU)-treated mice into three groups, based on the stages of stem cell development and studied doubling time, using a serum-free clonal culture system. Stage I progenitors were those present in primary marrow cells from 5-FU-treated mice. Stages II and III progenitors were early and late progenies in culture of stage I progenitors respectively. The morphological analysis of colonies derived from stage I, II and III progenitors demonstrated an association of progression of stages with loss of multipotentiality. The doubling time of haemopoietic progenitors was estimated by sequential analysis of colony formation and studies of growth fraction. The time required for haemopoietic progenitors to double shortened as their stage of development progressed. Alteration in one doubling time of haemopoietic progenitors at progressive stages of stem cell development was seen in cultures supported by various combinations of growth factors, including interleukin-3 (IL-3), IL-11. and steel factor (SF), Cell-cycle analysis suggested that reduction of the doubling time of haemopoietic progenitors is probably due to a decrease in the time spent in the G1 phase of the cell cycle. Our results suggest that in early haemopoiesis the doubling time of haemopoietic progenitors may change with stem cell development.

Animals↗

PubMed1996

Effects of nilvadipine (a dihydropyridine-type calcium entry blocker) on cerebral blood flow in acute experimental brain ischemia in rats.

The purpose of the present study was to examine the effect of nilvadipine (a dihydropyridine-type calcium entry blocker) on the cerebral circulation, experimental models of cerebral ischemia were used to measure abrupt changes in the cortical cerebral blood flow (CBF) at the 'penumbra' (the boundary region between the anterior cerebral artery (ACA) and the middle cerebral artery (MCA)). Left middle cerebral artery occlusion (MCAO) was performed in Sprague--Dawley rats, and then 8 or 16 micrograms kg-1 of nilvadipine was administered to two groups of the rats. The former group was referred to as the 8-MCAO(+) group (n = 8), and the latter group, the 16-MCAO(+) group (n = 8). To a control group (n = 8), only the solvent of nilvadipine was administered. After the administration in each group, CBF and the mean arterial blood pressure (MAP) were continuously measured for 60 min. The MAP in both the 8-MCAO(+) and 16-MCAO(+) groups was significantly lower than in the control group for 25 min after nilvadipine administration (Wilcoxon 2 sample test, p < 0.05). Also, the CBF in the 16-MCAO(+) group was significantly lower (about 20%) for 55 minutes than that in the control group. On the other hand, the CBF in the 8-MCAO(+) group three minutes after nilvadipine administration was not significantly lower than in the control group (Wilcoxon 2 sample test). Our findings confirmed that nilvadipine (8 micrograms kg-1) maintained CBF while lowering the blood pressure in the experimental model of acute cerebral ischemia.

Animals↗

PubMed1996

Circulating parathyroid hormone-related protein (109-141) in malignancy-associated hypercalcemia.

For differential diagnosis between hypercalcemia-induced bone metastasis and humoral hypercalcemia of malignancy (HHM), serum parathyroid hormone-related protein (PTHrP) concentrations were measured in normal subjects and patients with malignancy-associated hypercalcemia according to the presence or absence of bone metastasis, using a new sensitive PTHrP(109-141) radioimmunoassay system. The serum PTHrP(109-141) levels in all of 14 patients without bone metastasis were significantly higher than those in normal subjects. However, in four patients with hypercalcemia associated with bone metastasis the levels were nearly the same as those in normal subjects. The time course in two hypercalcemic patients with esophageal carcinoma revealed that serum PTHrP(109-141) levels were elevated before hypercalcemia developed and that changes in PTHrP(109-141) and corrected serum calcium levels were significantly correlated. These findings suggest that determination of serum PTHrP(109-141) may be clinically important not only for differential diagnosis of HHM but also as a useful predictive marker of hypercalcemia.

Adolescent↗

PubMed1996

Triple paraneoplastic syndrome of hypercalcemia, leukocytosis and cachexia in two human tumor xenografts in nude mice.

Nude mice bearing the human oral cavity carcinoma cell line OCC-1, and the lung cancer cell line LC-1, developed a triple paraneoplastic syndrome consisting of hypercalcemia, cachexia and leukocytosis. All of these abnormalities disappeared rapidly after surgical resection of the tumors, suggesting their ectopic humoral nature. Search for the factors responsible for the respective abnormalities revealed that the production of parathyroid hormone-related protein and colony-stimulating factors (CSFs), mainly granulocyte-CSF, by the tumors could explain the hypercalcemia and leukocytosis, respectively. With regard to the severe cachexia, the production of two cachexia-associated cytokines, interleukin-6 and leukemia inhibitory factor, was able to explain the syndrome in OCC-1 bearing nude mice; however, the factor responsible in LC-1 bearing nude mice could not be identified. The triple paraneoplastic syndrome that developed in these two animal models could be explained partly by concomitant production of the peptide hormone and cytokines by cancer cells. These animal models may be very useful for the evaluation of diagnostic and therapeutic modalities for humoral abnormalities.

Animals↗

PubMed1996

Differential expression of two hemA mRNAs encoding glutamyl-tRNA reductase proteins in greening cucumber seedlings.

The first committed step of porphyrin synthesis in higher plants is the reduction of glutamyl-tRNA to glutamate 1-semialdehyde. This reaction is catalyzed by glutamyl-tRNA reductase, which is encoded by hemA genes. Two hemA cDNA clones (hemA1 and hemA2) were obtained from cucumber (Cucumis sativus) cotyledons by the PCR and cDNA library screening. They showed significant homology with published hemA sequences. Southern blot analysis of cucumber genomic DNA revealed that these genes are located at different loci and that there is another gene similar to the hemA genes. Accumulation of hemA1 mRNA was detected primarily in cotyledons and hypocotyls of greening cucumber seedlings, whereas that of hemA2 mRNA was detected in all tissues examined. Illumination of cucumber seedlings increased markedly the accumulation of hemA1 mRNA, but it did not induce remarkable changes in that of hemA2 mRNA. These findings suggest that hemA1 mRNA was accumulated in response to the demand of Chl synthesis in photosynthesizing tissues, whereas hemA2 mRNA was expressed in response to the demand of the synthesis of porphyrins other than chlorophylls.

Aldehyde Oxidoreductases↗

PubMed1996

Establishment and characterization of high- and low-lung-metastatic cell lines derived from murine colon adenocarcinoma 26 tumor line.

We established and characterized high- (LuM1) and low-lung-metastatic (NM11) cell lines derived from murine colon adenocarcinoma 26 tumor line. LuM1 cell line was established as a clonal cell line from a cultured cell mixture derived from a lung-metastatic nodule after 7 sequential subcutaneous transplantations of lung-metastatic tumors in the abdominal wall of BALB/c mice. NM11 cell line was established from a cultured cell mixture derived from a subcutaneous transplant of murine colon adenocarcinoma 26 tumor cells. LuM1 cells showed marked spontaneous lung metastases, but NM11 cells rarely did. High invasive potential of LuM1 cells was revealed by in vitro invasion assay using Matrigel reconstituted membranes. Rapid retraction was observed in monolayers of human umbilical vein endothelial cells and bovine aortic endothelial cells when LuM1 cells were added on the monolayers. Gelatin zymography and immunochemical examinations with monoclonal antibodies against gelatinase B (Mr 95,000 type IV collagenase) showed secretion of large amounts of the gelatinase by LuM1 cells.

Adenocarcinoma↗

PubMed1996

Effects of anisosmotic stress on cardiac muscle cell length, diameter, area, and sarcomere length.

The purpose of this study was to examine the effects of anisosmotic stress on adult mammalian cardiac muscle cell (cardiocyte) size. Cardiocyte size and sarcomere length were measured in cardiocytes isolated from 10 normal rats and 10 normal cats. Superfusate osmolarity was decreased from 300 +/- 6 to 130 +/- 5 mosM and increased to 630 +/- 8 mosM. Cardiocyte size and sarcomere length increased progressively when osmolarity was decreased, and there were no significant differences between cat and rat cardiocytes with respect to percent change in cardiocyte area or diameter; however, there were significant differences in cardiocyte length (2.8 +/- 0.3% in cat vs. 6.1 +/- 0.3% in rat, P < 0.05) and sarcomere length (3.3 +/- 0.3% in cat vs. 6.1 +/- 0.3% in rat, P < 0.05). To determine whether these species-dependent differences in length were related to diastolic interaction of the contractile elements or differences in relative passive stiffness, cardiocytes were subjected to the osmolarity gradient 1) during treatment with 7 mM 2,3-butanedione monoxime (BDM), which inhibits cross-bridge interaction, or 2) after pretreatment with 1 mM ethylene glycol-bis(beta-aminoethyl ether)-N, N,N',N'-tetraacetic acid (EGTA), a bivalent Ca2+ chelator. Treatment with EGTA or BDM abolished the differences between cat and rat cardiocytes. Species-dependent differences therefore appeared to be related to the degree of diastolic cross-bridge association and not differences in relative passive stiffness. In conclusion, the osmolarity vs. cell size relation is useful in assessing the cardiocyte response to anisosmotic stress and may in future studies be useful in assessing changes in relative passive cardiocyte stiffness produced by pathological processes.

Animals↗

PubMed1996

In vitro increase of aromatase mRNA in diencephalic neurons.

This study was designed to (1) examine the ability of fetal diencephalic neurons cultured in vitro to express aromatase mRNA and (2) evaluate the involvement of several environmental factors which may regulate the development and differentiation of the neurons in the central nervous system. Brain cells from fetal mice at various developmental stages were cultured as tissue slices and as primary monolayer cells, and the expression levels of aromatase mRNA in the cultured cells were measured by a quantitative reverse transcription-polymerase chain reaction method using an internal standard. On cultured slices of the diencephalic region from fetal mice on embryonic day 12 (E12), E13, or E15 on collagen-coated membranes, the expression level of the mRNA continued to increase for the initial 2-3 days as that in vivo. Time-dependent increase of aromatase mRNA was also observed for 3 days in E13 neuronal cells dissociated with papain and cultured on poly L-Lys-coated dishes in serum-free medium. However, no significant time-dependent increase of the aromatase mRNA level was observed in E10 or E11 brain cells cultured by either method. These findings suggest that the developmental increase of aromatase mRNA in diencephalic neurons is an endogenous characteristic and probably genetically determined after E12.

Animals↗

PubMed1996

Inhaled tryptase causes bronchoconstriction in sheep via histamine release.

Allergen-induced bronchoconstriction involves mast cell activation. Tryptase is a mast cell serine protease that is released during this process, but little is known about the action of tryptase in the airway. The purpose of this study was to determine: (1) if aerosolized tryptase causes bronchoconstriction, and (2) the mechanism by which this occurs. We measured mean pulmonary flow resistance (RL) in five allergic sheep before and after consecutive inhalations of 100 and 500 ng tryptase (in 2 ml total volume). Inhaled tryptase at 100 and 500 ng increased RL (mean +/- SE) by 33 +/- 12 and 122 +/- 8% (p < 0.05) over baseline. The response was reproducible upon repeat challenges. These studies were repeated in the same animals after pretreatment with aerosolized APC 366 (9 mg/3 ml), a specific tryptase inhibitor. In APC-366-treated sheep, tryptase increased RL by 10 +/- 3 and 6 +/- 2% (p < 0.05 versus control values) at 100 and 500 ng, respectively. The response to tryptase was also blocked by pretreating the sheep intravenously with the histamine H1-antagonist chlorpheniramine (2 mg/kg), in which RL increased only 5 +/- 4 and 7 +/- 6% after 100 and 500 ng tryptase. APC 366, however, did not block histamine-induced bronchoconstriction. Consistent with these findings was the observation that segmental bronchial challenge with tryptase (1 microgram) resulted in a significant increase in histamine levels in bronchoalveolar lavage. Inhaled tryptase (500 ng) also caused airway hyperresponsiveness to aerosolized carbachol 2 h after tryptase challenge. This tryptase-induced airway hyperresponsiveness could be blocked either by pretreating the sheep with APC 366 (30 min before challenge) or by treating the sheep 30 min after challenge. These results indicate that inhaled tryptase causes bronchoconstriction and airway hyperresponsiveness in allergic sheep by an event that may involve mast cell activation.

Administration, Inhalation↗

PubMed1996

Zwitterionic digalactosylceramides from the earthworm, Pheretima asiatica.

Nine homogeneous glycosphingolipids were isolated from the earthworm, Pheretima asiatica (Annelida). All of them are digalactosylceramides carrying a choline phosphate group in the outer galactose moiety. Their full structures including the position of a phosphocholine unit were determined based on chemical and spectral evidence.

Acetylation↗

PubMed1996

Six trigalactosylceramides from the leech (Hirudo nipponica).

Six neutral glycosphingolipids were isolated in the pure state from the leech, Hirudo nipponica (Annelida). In contrast to the zwitterionic monogalactosylceramides carrying a choline phosphate group so far obtained, all compounds are non-zwitterionic glycosphingolipids, trigalactosylceramides. Five compounds possess a Ga1 alpha 1-6Ga1 alpha 1-6Ga1 beta 1-Cer core, and one is unique in having a Ga1 alpha 1-6Ga1 beta 1-Cer structure. Their full structures have been determined on the bases of chemical and spectral evidence.

Animals↗

PubMed1996

Peritumoral edema and seizure in patients with cerebral convexity and parasagittal meningiomas.

Epileptogenic factors associated with cerebral convexity or parasagittal meningiomas were investigated by retrospective analysis of clinical symptoms and computed tomographic findings in 83 consecutive patients. The patients were divided into Group A consisting of 27 patients presenting with epilepsy as the first symptom, and Group B consisting of 56 patients presenting with other symptoms. Tumor location, tumor size, histological subtype, and the amount of peritumoral edema were compared between the groups. Tumor size, location, and histological subtype did not differ significantly between the two groups, but the area of peritumoral edema was significantly greater in Group A than in Group B. Similar results were found in subgroups of patients with frontal meningioma, central meningioma, and fibroblastic meningioma. Generalized seizures tended to occur in patients with frontal or fibroblastic meningioma, and partial seizures in those with central or parietal meningioma. Peritumoral edema is a significant epileptogenic factor associated with both cerebral convexity and parasagittal meningiomas, and may be especially related to the occurrence of secondarily generalized seizures in frontal and fibroblastic meningiomas.

Adult↗

PubMed1996

Ultra-early rebleeding in spontaneous subarachnoid hemorrhage.

To determine the incidence of, and risk factors for, the occurrence of rebleeding between admission and early operation (ultra-early rebleeding) in patients with spontaneous subarachnoid hemorrhage (SAH), the authors reviewed the cases of 179 patients admitted within 24 hours after their last attack of SAH. Thirty-one (17.3%) of these patients had ultra-early rebleeding despite scheduling of early operation (within 24 hours after admission). The incidence of rebleeding significantly decreased as the time interval between the last attack and admission increased. Patients with rebleeding before admission, high systolic blood pressure, intracerebral or intraventricular hematoma, those in poor neurological condition on admission, and those who underwent angiography within 6 hours of the last SAH were significantly more likely to have ultra-early rebleeding than those without these factors. The incidence of rebleeding also significantly increased as levels of enhancement of platelet sensitivity and thrombin-antithrombin complex increased. Multivariate analysis revealed that the following three factors were independently associated with ultra-early rebleeding: the level of enhancement of platelet sensitivity; the time interval between the last attack and admission; and the level of thrombin-antithrombin complex. On the basis of these findings, the authors suggest that many of the risk factors for ultra-early rebleeding are interrelated. A particularly high risk of ultra-early rebleeding was observed in those patients 1) who had platelet hypoaggregability; 2) who were admitted shortly after their last SAH; and 3) whose thrombin-antithrombin complex levels were extremely high and were thus in severe clinical condition.

Cerebral Angiography↗