Biomedical subjects

Y Kashima

Publications and source records attributed to Y Kashima.

At least 37 records · Page 2Linked to original sources

PubMed1999

Roles of three histidine kinase genes in hyphal development and virulence of the pathogenic fungus Candida albicans.

The pathogenic fungus Candida albicans harbors three histidine kinase genes called CaSLN1, CaNIK1, and CaHK1. The disruption of any one of these three genes impaired the hyphal formation and attenuated the virulence of C. albicans in a mouse systemic candidiasis model. The effects of the disruption on hyphal formation and virulence were most severe in the cahk1Delta null mutants. Although the double disruption of CaSLN1 and CaNIK1 was impossible, further deletion of CaSLN1 or CaNIK1 in the cahk1Delta null mutants partially restored the serum-induced hypha-forming ability and virulence. When incubated with radiolabelled ATP, the recombinant CaSln1 and CaNik1 proteins, which contained their own kinase and response regulator domains, were autophosphorylated, whereas CaHk1p was not. These results imply that in C. albicans, CaSLN1 and CaNIK1 function upstream of CaHK1 but are in distinct signal transmission pathways.

Animals↗

PubMed1998

Isolation and characterization of the Candida albicans gene for mRNA 5'-triphosphatase: association of mRNA 5'-triphosphatase and mRNA 5'-guanylyltransferase activities is essential for the function of mRNA 5'-capping enzyme in vivo.

The amino acid sequence of the Saccharomyces cerevisiae mRNA 5'-triphosphatase (TPase) diverges from those of higher eukaryotes. In order to confirm the sequence divergence of TPases in lower and higher eukaryotes, the Candida albicans gene for TPase was identified and characterized. This gene designated CaCET1 (C. albicans mRNA 5'-capping enzyme triphosphatase 1) has an open reading frame of 1.5 kb, which can encode a 59-kDa protein. Although the N-terminal one-fifth of S. cerevisiae TPase (ScCet1p) is missing in CaCet1p, CaCet1p shares significant sequence similarity with ScCet1p over the entire region of the protein; the recombinant CaCet1p, which was expressed as a fusion protein with glutathione S-transferase (GST), displayed TPase activity in vitro. CaCET1 rescued CET1-deficient S. cerevisiae cells when expressed under the control of the ADH1 promoter, whereas the human capping enzyme derivatives that are active for TPase activity but defective in mRNA 5'-guanylyltransferase (GTase) activity did not. Yeast two-hybrid analysis revealed that C. albicans Cet1p can bind to the S. cerevisiae GTase in addition to its own partner, the C. albicans GTase. In contrast, neither the full-length human capping enzyme nor its TPase domain interacted with the yeast GTase. These results indicate that the failure of the human TPase activity to complement an S. cerevisiae cet1delta null mutation is attributable, at least in part, to the inability of the human capping enzyme to associate with the yeast GTase, and that the physical association of GTase and TPase is essential for the function of the capping enzyme in vivo.

Acid Anhydride Hydrolases↗

PubMed1998

Nurses' responses to people with schizophrenia.

General nurses, psychiatric nurses and lay people were investigated to identify differences between their personal standards concerning how they should respond, and beliefs about how they actually would respond, towards the target group, 'people with schizophrenia', in each of three response domains (thinking, feeling and behaving). Significant differences were identified between the response types and between the different response domains. Significant interaction effects were also identified based on participants professional status in nursing. It is argued that the results support Devine's (1989) theory concerning the automatic activation of stereotypes and their controlled inhibition in favour of different personal beliefs. It is also argued that professional specialization in psychiatric nursing facilitates this process in relation to the target group.

Adult↗

PubMed1998

[Ishikawa's classification of cavernous sinus lesions by clinico-anatomical findings].

Jefferson's classification (1938) has been used to localize lesions of the cavernous sinus. However, we think this classification is sometimes incorrect in identifying localization based on clinico-anatomical evidence. We investigated the efficacy of the newly proposed Ishikawa's classification. Based on the analysis on serial sections of human cavernous sinus, it classifies the locus of the lesion into three groups: anterior, middle, and posterior, corresponding to the location of the intracranial orifice of the optic canal and of the penetration of the maxillary nerve into the cavernous sinus. The subjects were 162 cases with cavernous sinus lesions. They were classified by the two methods. There was a total of 111 cases (69%) of unclassified cases in Jefferson's classification and 45 (28%) in Ishikawa's classification. The anterior type was frequently encountered in cases caused by inflammations and both posterior and whole types were caused by tumors in Ishikawa's classification. It was concluded that Ishikawa's classification is clinically useful to identify and classify the localization of cavernous sinus lesions.

Aneurysm↗

PubMed1997

An immunohistochemical study of TNF-alpha in optic nerves from AIDS patients.

PURPOSE: Both in vitro and in vivo studies have implicated a role for tumor necrosis factor (TNF-alpha) in the pathology of demyelinating diseases. The purpose of this study was to address the hypothesis that TNF-alpha is a mediator of AIDS-related optic nerve injury and to determine the cell types involved in the proliferation of TNF-alpha in the AIDS optic nerve. METHODS: Ten optic nerves from seven patients with AIDS, and three from persons who were HIV negative were stained, using the indirect immunoperoxidase method. Six of the ten AIDS optic nerves were positive for cytomegalovirus (CMV), but the remainder did not have abnormal fundus findings. RESULTS: In all the optic nerves from AIDS patients with or without CMV retinitis, the vast majority of astrocytes stained strongly for TNF-alpha. Microglial cells (MPS-derived macrophages) varied from not staining to staining strongly positive for TNF-alpha. However, oligodendrocytes were not labeled positively for TNF-alpha. Some endothelial cells also stained for TNF-alpha. Examination of normal optic nerves and controls did not reveal any cell type that stained positively for TNF-alpha. CONCLUSIONS: The present study supports the contention that TNF-alpha is a major mediator of AIDS-associated optic neuropathy. HIV infection induces the production of TNF-alpha in macrophages and astrocytes, which probably causes demyelination and other neuronal damage.

Acquired Immunodeficiency Syndrome↗

PubMed1996

Scanning electron microscopy of the basal surface of the epidermis of human digits.

The epidermal-dermal junction of the volar skin of human digits was examined by scanning electron microscopy (SEM). Fixed specimens obtained from cadavers were treated with 6 N NaOH to exfoliate the epithelium. The three-dimensional features of the basal surfaces were clearly visualized by SEM. Epithelial prolongations (intermediate and limiting ridges) protruded towards the dermis, and transverse ridges were visible between them. Nerve fibers and Schwann cells were aggregated around the sweat ducts on the intermediate ridges. Discoid structures were visible among the nerve fibers and Schwann cells. Examination by transmission electron microscopy of ultrathin sections of re-embedded specimens confirmed that the discoid structures were nerve endings that covered the Merkel cells. Minute projections were studded on the basal surfaces of basal keratinocytes. The projections in the intermediate ridges appeared to be villous, whereas the profiles of those in the limiting ridges resembled cobblestones. This morphological difference might be a reflection of function.

Aged↗

PubMed1995

Effects of oncogenes on the resistance to cis-diamminedichloroplatinum(II) and metallothionein gene expression.

Transformation of NIH3T3 cells with the ras, the sis, or the neu oncogene rendered cells less susceptible to cis-diamminedichloroplatinum(II). Since resistance to cis-diamminedichloroplatinum(II) is reported to be associated with increased levels of metallothionein, we examined effects of these oncogenes on metallothionein gene expression. NIH3T3 cells were first transfected with the lacZ gene whose transcription is under the control of mouse metallothionein I promoter and then with the ras, the sis, or the neu oncogene. The ras and the sis oncogenes increased beta-galactosidase activities which were induced either by metal (cadmium and zinc) or by glucocorticoid (dexamethasone), whereas the neu oncogene repressed its activity. When SV40 early promoter was used instead of metallothionein I promoter for the lacZ gene transcription, the beta-galactosidase activities were not affected by metal, dexamethasone, or any of these oncogenes. This result was coincident with that of reverse transcription polymerase chain reaction that metal-induced MT I mRNA was only detected in the sis- or the ras-transformed cells, whereas any of these oncogenes did not affect the metal-induced transcription of the MT II gene. These results demonstrate that the ras and the sis oncogenes upregulate the metal- or glucocorticoid-induced transcription from metallothionein I promoter, but the neu oncogene negatively regulates it. Thus, resistance to the chemotherapeutic agent by oncogenic transformation is partly associated with the metallothionein gene expression, and MT I and MT II gene expressions are differently controlled by different oncogenes.

3T3 Cells↗

PubMed1995

Culture, gender, and self: a perspective from individualism-collectivism research.

Individualism and collectivism are often equated with independent vs. interdependent, agentic vs. communal, and separate vs. relational self-construals. Although these same concepts have been used to characterize both cultural and gender differences, a perspective of cultural evolution suggests it is unlikely. A division of labor within society may produce gender differences, but this cannot explain cultural differences. A study of self-construal involving 5 cultures (Australia, the United States, Hawaii, Japan, and Korea) shows that differences between these cultures are captured mostly by the extent to which people see themselves as acting as independent agents, whereas gender differences are best summarized by the extent to which people regard themselves as emotionally related to others.

Adolescent↗

PubMed1995

[Horizontal gaze palsy due to lesion of the abducens nucleus detected with magnetic resonance imaging].

A case of unilateral horizontal gaze palsy is reported. The lesion of the abducens nucleus was clearly detected with magnetic resonance imaging. In the early stage, the adduction of the right eye and abduction of the left eye were completely limited and the vestibulo-ocular reflex was also impaired. However, during the recovery stage, the improvement of limitation of abduction was delayed compared with that of adduction. We suggest that this phenomenon is useful as a differential diagnosis between lesions of the abducens nucleus and of the paramedian pontine reticular formation.

Abducens Nerve↗

PubMed1993

[3H]2-(4-phenylpiperidino)cyclohexanol (AH5183) binding to synaptosomes and subcellular fractions obtained from rat brain.

We investigated the binding of [3H]AH5183 (2-(4-phenylpiperidino)cyclohexanol) to rat brain synaptosomes and subcellular fractions. A high content of specific binding was observed in crude synaptosomes obtained from the striatum, cerebral cortex and hippocampus. The highest density of subcellular binding sites was observed in the synaptic vesicle-rich fraction. The affinities of AH5183 binding to crude synaptosomes and the synaptic vesicle-rich fraction were almost equivalent, but the density of binding sites was higher in the synaptic vesicle fraction. The present findings indicate that [3H]AH5183 binding to both synaptosomes and the synaptic vesicle-rich fraction is useful as a cholinergic marker, and that for quantitative studies, binding to the latter fraction is more preferable.

Animals↗

PubMed1993

The theory of reasoned action and cooperative behaviour: it takes two to use a condom.

The applicability of the Theories of Reasoned Action and Planned Behaviour to the cooperative behaviour of condom use were examined. Seventy-one male and 78 female students, all sexually active unmarried heterosexuals aged 17 to 21 years, gave information about their intentions for the next sexual encounter, as well as their attitude, subjective norm, expectancy-value attitude and subjective norm (including normative beliefs for their sexual partner), and their past behaviour with respect to condom use. After their next sexual encounter, they completed a questionnaire on their actual condom use. Results indicated that when behavioural conditions including the availability of a condom and an agreement with the partner to use it were satisfied, intention interacted with past behaviour to predict actual behaviour. These results imply that intentions which are consistent with past behaviour are stable enough to be carried out in the face of the interpersonal dynamics of a sexual encounter. Further, normative belief for the sexual partner had a direct influence on attitudes, subjective norm and intention. Neither the Theory of Reasoned Action nor the Theory of Planned Behaviour can fully explain these results, which point to the need for further theoretical inquiry into the dynamics of cooperative behaviour.

Adolescent↗

PubMed1993

[Effects of ascorbic acid on trace element metabolism in the choroid-retina of streptozotocin-induced diabetic guinea pigs].

In order to investigate the effect of ascorbic acid on trace element metabolism in the choroid-retina, experimental diabetes mellitus was induced in Hartley guinea pigs with intraperitoneal injection of streptozotocin. After 4 weeks, ascorbic acid-deficient feed was given for 3 weeks. Trace elements of the choroid-retina were measured with inductively-coupled plasma emission spectrometry. The activity of superoxide dismutase and lipid peroxide content also were measured. The results indicated that zinc and magnesium increased in diabetes mellitus. However, with ascorbic acid deficiency in diabetes mellitus, zinc and magnesium significantly decreased. On the other hand, the activity of superoxide dismutase showed no change between either condition and lipid peroxide content decreased under ascorbic acid deficiency in diabetes mellitus. These findings suggested that ascorbic acid played an important role in chorioretinal damage of diabetes mellitus. However, it was also suggested that lipid peroxide has little influence on the choroid-retina under these conditions.

Animals↗

PubMed1992

Acetylcholine synthesis is modulated by acetylcholine content of cytosolic fraction but not by that of releasable fraction.

Synthesis and release of acetylcholine (ACh) in the rat hippocampal slices were examined to clarify the mechanism of modulation of ACh synthesis. Treatment with 2-(4-phenylpiperidino)cyclohexanol (AH5183, 50 microM), an inhibitor of ACh transport from cytosol to synaptic vesicles, inhibited the increase in ACh content of the membrane-bound fraction which is readily releasable, but did not affect the cytosolic ACh content. Under these conditions, the total ACh content reached a plateau value. These results indicate that ACh synthesis is modulated by cytosolic ACh content but not by the vesicular fraction.

Acetylcholine↗

PubMed1991

Regional differences in extracellular choline dependency of acetylcholine synthesis in the rat brain.

Acetylcholine (ACh) synthesis under conditions of restricted extracellular choline uptake was investigated in order to clarify the procurement of choline for ACh synthesis using slices of several regions of the rat brain. Extracellular choline-independent ACh synthesis was observed in the hippocampus, frontal cortex and caudate putamen, which contain cholinergic nerve terminals, whereas little or no synthesis was observed in the medial septum or basal nucleus of Meynert, which contain cholinergic cell bodies. These results indicate that cholinergic nerve terminals, but not the cell bodies, may be able to synthesize choline for ACh biosynthesis. Extracellular choline-dependent ACh synthesis was observed in all regions examined. In the presence of 10 microM choline, the highest content of newly synthesized ACh and the proportionate increase in ACh compared with the unreleasable fraction (basal level) were observed in the caudate putamen. In the frontal cortex, although the level of synthesized ACh was low, the proportionate increase in ACh was high. In contrast, in the medial septum and basal nucleus of Meynert, high levels of ACh with a low proportionate increase compared with basal levels were observed. In the presence of hemicholinium-3, extracellular choline was also taken up for ACh synthesis in all regions examined, the level being especially high in the frontal cortex and medial septum. The present results indicate that the manner of choline procurement for ACh synthesis is heterogeneous among the various regions of the rat brain.

Acetylcholine↗

PubMed1991

A new rat colon cancer cell line metastasizes spontaneously: biologic characteristics and chemotherapeutic response.

A new cell line (RCN-9) was established in culture from a transplantable rat colon adenocarcinoma, which was induced in the colon of a male Fischer F344 rat by subcutaneous administration of 1,2-dimethylhydrazine. When RCN-9 cells were injected subcutaneously or into the cecal subserosa of syngeneic rats, carcinomas with progressive growth were obtained and the development of lung (63.6%) and liver (40.0%) metastases, respectively, ensued. Antitumor effects of 5-fluorouracil (5-FU), adriamycin (ADM) and mitomycin C (MMC) against RCN-9 were examined in vivo and in vitro. 5-FU and ADM had antitumor effects both in vivo and in vitro; MMC had antitumor effects in vitro. These results show that the RCN-9 cell line can be used both as a model to study mechanisms of metastasis from colon carcinoma and as a model in chemotherapeutic studies of metastatic disease from colon carcinoma.

Adenocarcinoma↗

PubMed1991

Direct visualization of colloidal gold-bound molecules and a cell-surface receptor by ultrahigh-resolution scanning electron microscopy.

The structure of protein A-coated colloidal gold particles, and of macrophage cell-surface receptors conjugated with immunogold particles, was studied using an ultrahigh-resolution scanning electron microscope. Protein A, when conjugated with 15-nm gold, formed a coat completely surrounding the particle. Particles conjugated with both protein A and immunoglobulin G (IgG) were similar, but with additional protrusions formed by the IgG. IgG molecules directly bound to gold were resolved sometimes as complexes of three units, sometimes as more filamentous, V-shaped structures. On the cell surface of macrophage reacted with a monoclonal antibody to Mac-1 antigen (the murine C3bi receptor) followed by protein A-gold, gold particles were seen to be linked via the IgG to the receptor, visualized as a round granule.

Animals↗

PubMed1991

Determination of acetylcholine release in the striatum of anesthetized rats using in vivo microdialysis and a radioimmunoassay.

A vertical-type in vivo microdialysis probe and a sensitive, specific radioimmunoassay (RIA) were used to study the mechanism of acetylcholine (ACh) release in the striatum of anesthetized rats. Without the use of physostigmine, a cholinesterase inhibitor, our RIA could still detect the amount of ACh present in the perfusate (5.6 +/- 0.6 fmol/min, n = 16). Tetrodotoxin (1 microM) produced a significant decrease in the amount of ACh collected in the perfusate, suggesting that basal ACh determined under the present experimental conditions was related to cholinergic neural activity. Atropine (0.1-1 microM) applied topically via the dialysis probe did not affect the amount of ACh recovered in the perfusate in the absence of physostigmine. Addition of physostigmine (10 microM) to the perfusion fluid produced about a 100-fold increase in the amount of ACh collected. In the presence of physostigmine, topical administration of atropine and pirenzepine (0.01-1 microM) through a dialysis probe produced a further three- to fourfold increase in ACh output, whereas a slight increase was produced by AF-DX 116 at the highest concentration (1 microM). These results indicate that presynaptic modulation of ACh release in the striatum does not occur under basal conditions, and that presynaptic M1 muscarinic receptors are involved in the modulation of ACh release when the ACh concentration is raised under certain conditions.

Acetylcholine↗

PubMed1989

Hemicholinium-3-resistant choline uptake system linked to acetylcholine synthesis in the rat hippocampus.

Extracellular choline-dependency of acetylcholine (ACh) synthesis was examined in rat hippocampal slices. In the presence of hemicholinium-3 (HC-3, 5 microM), extracellular choline-dependent ACh synthesis appeared to consist of two different components. The first component (saturated at up to 50 microM choline) was dependent on the HC-3-resistant choline uptake system having a low capacity for choline in comparison with the high-affinity choline uptake system (HACU). The second component, observed in the presence of more than 50 microM choline, was considered due to competitive inhibition of HACU by HC-3. HACU-dependent ACh synthesis seemed to be saturated in the presence of up to 2 microM choline. These results indicate that both the HACU and HC-3-resistant choline uptake systems are linked to ACh synthesis in the hippocampus.

Acetylcholine↗