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Biomedical subjects

Y Kamada

Publications and source records attributed to Y Kamada.

At least 73 records · Page 4Linked to original sources
PubMed1998

A visual method for analysing bucco-lingual position of artificial posterior teeth. Part 1: use of the ridge crest.

We have developed a visual analysis method to examine the spatial relationship between the edentulous ridges and the bucco-lingual position of the artificial posterior teeth in complete denture fabrication. In this system, a non-contact type shape measurement system is used. We applied this system to the plaster models and the wax dentures of an edentulous patient. Using the measurement data on the upper and lower plaster models, we reconstructed their shape three-dimensionally and determined the points regarded as the ridge crests and the inter-alveolar crest lines in the frontal sections. To generate the upper and lower ridge crest lines which consisted of the points of the ridge crests, interpolation by B-spline curves was applied. Furthermore, the loft surfaces that we regarded as the consecutive inter-alveolar crest lines, were generated between the upper and lower ridge crest lines. The surface models of the plaster models and artificial teeth were displayed on the cathode-ray tube display unit, and the ridge crest lines and the consecutive inter-alveolar crest lines were superimposed on the surface models. This method could be utilized to visualize and examine the bucco-lingual position of the artificial posterior teeth in reference to the inter-alveolar crest lines.

Computer Graphics↗
PubMed1998

RANTES augments eosinophil lucigenin-dependent chemiluminescence.

BACKGROUND: RANTES (regulated on activation, normal T expressed and secreted) has been shown to possess chemotactic activity for eosinophils. Eosinophils have been considered to play a key role in the allergic inflammation through the release of inflammatory molecules such as radical oxygen products. Thus, in this study, we examined the effect of RANTES on radical oxygen products from eosinophils. METHODS: Eosinophils were isolated from heparinized venous blood of patients with bronchial asthma by the modified CD16-negative depletion method. Radical oxygen products were examined in terms of lucigenin-dependent chemiluminescence. To a mixture of 50 microl of eosinophils (2x10(6)/ml) and 50 microl of lucigenin (5x10(-4)M), 50 microl of calcium ionophore A23187 (final concentration 10(-5)M) was added, and radical oxygen products were determined for 600 s. RESULTS: RANTES treatment resulted in the enhancement of peak value (0.64+/-0.23 RLU) and integrated value (119.08+/-20.52 RLU) as compared to untreated cells (0.15+/-0.03 RLU, 29.48+/-8.92 RLU, respectively). CONCLUSIONS We could conclude that RANTES might play an important role in the pathogenesis of allergic inflammation through involvement in selective eosinophil infiltration and eosinophil activation by augmentation of eosinophil oxidative metabolism.

Acridines↗
PubMed1998

Involvement of beta1 and beta2 integrin stimulation in RNA synthesis in an eosinophilic cell line (EoL-1).

In allergic inflammatory disease, especially in bronchial asthma, eosinophils play important roles as essential inflammatory cells. In the accumulation of eosinophils in airway inflammation, eosinophils receive very diverse stimuli. In this study, we investigated the influences of the signal between beta2 integrin/intercellular adhesion molecule-1 (ICAM-1) or beta1 integrin/fibronectin (FN) and RNA synthesis on proteins in eosinophilic cell line-1 (EoL-1), using recombinant soluble ICAM-1 (r-sICAM-1) as a global response of eosinophils. 3H-thymidine incorporation and 3H-uridine incorporation were used as indices for DNA synthesis and RNA synthesis, respectively. In a comparison of the RNA/DNA ratio with various durations of stimulation of 1 microg/ml of r-sICAM-1 and 100 microg/ml of FN, a time-dependent increase was observed, but the increase induced by FN rose slower than that induced by r-sICAM-1. From this result, a beta2 integrin/ICAM-1 signal induced an increase in the RNA/DNA ratio in EoL-1, implying that the signal promotes RNA synthesis, which suggests that various types of protein synthesis, such as the synthesis of various cytokines, are induced by the beta2 integrin/ICAM-1 signal. Similar results were obtained with a beta1 integrin signal using FN, but there was a difference in the time course between beta2 integrin/ICAM-1 and beta1 integrin/FN signals. This experimental method may be useful for understanding these manifestations as a global response of eosinophils.

Asthma↗
PubMed1998

Osteopathy in broiler chicks fed toxic mimosine in Leucaena leucocephala.

Further studies of mimosine toxicity in broiler chicks were done to clarify a possibility of osteopathy. The mineral content and density of femur and the strength, ductility, and toughness for the index of mechanical properties significantly decreased in the 1% mimosine group, compared with those in the control and restricted groups. The stiffness had a decreasing tendency in the 1% mimosine group. Consequently, it was concluded that chicks fed ad libitum a 1% mimosine diet for 12 days developed osteopathy. The bone mineral density and the strength of the restricted group were lower than those of the control group, and those of the 1% mimosine group were still lower than those of the restricted group. Contents of pyridinoline and deoxypyridinoline in the excrement were significantly higher in the restricted group than those in the control group, but the contents in the 1% mimosine group were significantly lowest among the groups. Osteopathy in chicks fed mimosine, therefore, seemed to be done by loss of appetite and changing to a low turnover of bone caused by mimosine.

Amino Acids↗
PubMed1998

A ruptured syphilitic descending thoracic aortic aneurysm. The characteristic findings on computed tomography for the etiological diagnosis of aneurysm.

We report the case of a 72-year-old man with a ruptured syphilitic descending thoracic aneurysm who underwent an emergency operation and successful graft replacement. Preoperative physical examination showed a pulsative mass on the left back. Preoperative computed tomography showed bone destruction in the TH6 to TH10 thoracic vertebrae and ribs and penetration (or rupture) of the aneurysm into the subcutaneous tissue. During the period of preoperative evaluations, free wall rupture of the aneurysm occurred and emergency operation for graft replacement was performed. The microscopical examination of the aneurysmal wall revealed the syphilitic changes. In literature, the vertebral destruction by atherosclerotic aneurysm is usually located at the TH12 to L3 of vertebral bodies. From the findings of this patient and a study of existing literature, we concluded that the finding of vertebral bone beyond TH12 to L3 region on CT examination of the aneurysm could be a etiological characteristic finding for syphilitic aortic aneurysm.

Aged↗
PubMed1998

[Pain-free injection of propofol].

Pain on injection is one of the well-known side effects of propofol. Previous studies have shown several methods to alleviate this discomfort. We employed all these methods together to clarity whether pain-free injection of propofol was possible. Sixty adult patients premedicated with midazolam were studied. Control group patients (n = 20) received an induction dose of propofol via a vein on the dorsum of the hand at a slow injection speed with carrier i.v. fluid. Study group patients (n = 40) received i.v. fentanyl 0.1 mg, followed by bolus injection of cold propofol premixed with lidocaine (final concentration of lidocaine was 0.2%) in a forearm vein without carrier i.v. fluid. Eighteen patients (90%) in the control group experienced injection pain. In the study group, however, no patients complained of pain or discomfort. In conclusion, pain-free injection of propofol was possible when prior-administration of fentanyl, premixing of lidocaine, cooling to 4 degrees C, and rapid injection via a forearm vein without carrier i.v. fluid was the adopted precedure.

Adult↗
PubMed1997

A role for the Pkc1 MAP kinase pathway of Saccharomyces cerevisiae in bud emergence and identification of a putative upstream regulator.

The protein kinase C of Saccharomyces cerevisiae, Pkc1, regulates a MAP kinase, Mpk1, whose activity is stimulated at the G1-S transition of the cell cycle and by perturbations to the cell surface, e.g. induced by heat shock. The activity of the Pkc1 pathway is partially dependent on Cdc28 activity. Swi4 activates transcription of many genes at the G1-S transition, including CLN1 and CLN2. We find that swi4 mutants are defective specifically in bud emergence. The growth and budding defects of swi4 mutants are suppressed by overexpression of PKC1. This suppression requires CLN1 and CLN2. Inhibition of the Pkc1 pathway exacerbates the growth and bud emergence defects of swi4 mutants. We find that another dose-dependent suppressor of swi4 mutants, the novel gene HCS77, encodes a putative integral membrane protein. Hcs77 may regulate the Pkc1 pathway; hcs77 mutants exhibit phenotypes like those of mpk1 mutants, are partially suppressed by overexpression of PKC1 and are defective in heat shock induction of Mpk1 activity. We propose that the Pkc1 pathway promotes bud emergence and organized surface growth and is activated by Cdc28-Cln1/Cln2 at the G1-S transition and by Hcs77 upon heat shock. Hcs77 may monitor the state of the cell surface.

Calcium-Calmodulin-Dependent Protein Kinases↗
PubMed1997

Carcinoma of the lung in Okinawa, Japan: with special reference to squamous cell carcinoma and squamous metaplasia.

In Okinawa, a subtropical island in southern Japan, squamous cell carcinoma (SCC), especially the well-differentiated form, is prevalent, while this form is relatively rare in both the mainland and other countries (e.g. United States of America). More patients with SCC from Okinawa, moreover, were positive for human papillomavirus (HPV) DNA by polymerase chain reaction (PCR) (79%), and harbored HPV types 6, 16 and 18, in combination. On the other hand, less than 30% of the mainland patients were positive for HPV DNA by PCR. Those patients who were positive all harbored only one HPV type. Furthermore, in Okinawa, there were a significant number of cases with adenosquamous carcinoma, and they too were positive for HPV DNA. The SCC and the adenocarcinoma cells adjacent to the SCC component in these cases were also positive for HPV DNA, and such adenocarcinoma cells were enlarged in size with relatively wide cytoplasm. The authors postulate that HPV infects adenocarcinoma cells and changes them to enlarged cells, followed by squamous metaplasia. In this report, HPV DNA was transfected to adenocarcinoma cells (cultured cell lines) and this showed that HPV causes squamous metaplasia. In addition, aberrant expression of p53 was demonstrated in a large number of the SCC cases in Okinawa. The enlarged adenocarcinoma cells adjacent to the SCC components in adenosquamous carcinomas also showed aberrant expression of p53. The recent advances in the studies of anti-oncogenes, p53, etc. and oncogenes are outlined. It is to be noted that the molecular mechanisms of carcinogenesis in the lung have been studied in general, classifying lung tumors into two groups, namely, small cell carcinoma (SCLC) and non-small cell carcinoma (NSCLC). However, because human lung cancer is represented by a wide variety of histologic types, molecular genetic studies according to a more detailed histological subclassification is needed.

Adult↗
PubMed1997

Expression of mRNA for RANTES in human eosinophils.

RANTES has been considered to play an important role in various immune and allergic disorders since RANTES is a potent chemoattractant for various important inflammatory cells such as eosinophils. Eosinophils, on the other hand, are considered to be the major inflammatory cells in bronchial asthma since eosinophil-specific granule proteins can damage bronchial mucosal cells. The recent demonstration that eosinophils themselves could synthesize some cytokines such as IL-5 indicates the role of these cytokines not only in paracrine but also in autocrine regulation of eosinophil production, differentiation and activation. Therefore, in this study, we examined mRNA for RANTES and release of RANTES by human eosinophils. The present findings revealed that eosinophils obtained from asthmatic patients could express and release RANTES. Taken together, these findings suggest that eosinophils play a crucial role in the pathogenesis, particularly in eosinophil and T lymphocyte recruitment into the inflamed sites in asthma through RANTES production.

Asthma↗
PubMed1996

Activation of yeast protein kinase C by Rho1 GTPase.

We have investigated the role of the essential Rho1 GTPase in cell integrity signaling in budding yeast. Conditional rho1 mutants display a cell lysis defect that is similar to that of mutants in the cell integrity signaling pathway mediated by protein kinase C (Pkc1), which is suppressed by overexpression of Pkc1.rho1 mutants are also impaired in pathway activation in response to growth at elevated temperature. Pkc1 co-immunoprecipitates with Rho1 in yeast extracts, and recombinant Rho1 associates with Pkc1 in vitro in a GTP-dependent manner. Recombinant Rho1 confers upon Pkc1 the ability to be stimulated by phosphatidylserine, indicating that Rho1 controls signal transmission through Pkc1.

Cell Cycle Proteins↗
PubMed1996

Human papillomavirus DNA in squamous cell carcinoma of the lung.

AIM: To compare the incidence of squamous cell carcinoma (SCC) of the lung in Okinawa with that in Niigata on the mainland. METHODS: All patients presenting with SCC of the lung in Okinawa and Niigata in 1993 were included in the study. Diagnoses were confirmed by conventional histological examination of paraffin wax sections. Human papillomavirus (HPV) was detected by non-isotopic in situ hybridisation (NISH) and polymerase chain reaction (PCR) amplification with primers specific for the E6 and E7 regions of the HPV genome. PCR products were analysed by Southern and dot blotting. RESULTS: The incidence of well differentiated SCC of the lung was high in patients from Okinawa compared with moderately and poorly differentiated types, and compared with the incidence of SCC in patients from Niigata. This is despite similar patterns of age, sex (predominatly male), and smoking habit. More patients from Okinawa, however, were positive for HPV DNA by PCR (79%) and NISH (53%). Many patients haboured HPV types 6, 16, and 18. Only 30% of patients from Niigata were positive for HPV DNA by PCR and 20% by NISH. These patients all harboured one HPV type only. CONCLUSION: Surprisingly large numbers of patients from Okinawa were positive for HPV DNA. The detection of HPV DNA was strongly associated with well differentiated SCC. This was particularly true for HPV types 6 and 16. There was no correlation between either smoking and detection of HPV DNA, or smoking and histological differentiation.

Adult↗
PubMed1996

Immunoelectron microscopic observation of the behaviors of peroxisomal enzymes inducibly synthesized in an n-alkane-utilizable yeast cell, Candida tropicalis.

We reported that immunoelectron microscopy was an excellent tool for determining the subcellular localization of thiolase isozymes, acetoacetyl-CoA thiolase (T-I) and 3-ketoacyl-CoA thiolase (T-III) in n-alkane-grown Candida tropicalis cells (KAMASAWA, N. et al., (1992). Cell Struct. Funct., 17: 203-207). Current investigation on the visualization of other peroxisomal enzymes, acyl-CoA oxidase (ACO), catalase (KAT), carnitine acetyltransferase (CAT), isocitrate lyase (ICL) and malate synthase (MS), showed that ACO localized in peroxisomes, KAT in peroxisomes and cytoplasm, and CAT in peroxisomes, mitochondria and cytoplasm. Most of ICL and MS were found in peroxisomes. These results agreed with previous biochemical studies and supported the presumed roles of these enzymes. The same technique was applied to study the process of synthesis and localization of these enzymes early in the cultivation period in n-alkane medium when peroxisomes began to proliferate. ACO and T-III were rapidly induced after transfer of cells from glucose- to n-alkane-media. There was a drastic change of their location from cytoplasm to peroxisomes between 1 h and 2 h after the transfer, while T-I, KAT and CAT were moderately induced in cytoplasm and their location was gradually changed to each organelle. ICL and MS, the key enzymes in the glyoxylate cycle, were already localized in peroxisomes in the glucose-grown cells and respective inducible enzymes also were gradually localized there. This visual analysis is useful for the vivid elucidation of the process of peroxisome proliferation and enzyme transport within a cell.

Alkanes↗
PubMed1996

Purification and characterization of N-acetylglucosamine 6-phosphate deacetylase with activity against N-acetylglucosamine from Vibrio cholerae non-O1.

An enzyme that deacetylates N-acetylglucosamine to glucosamine from Vibrio cholerae non-O1 was purified to homogeneity by sequential procedures. The native enzyme had a molecular mass of 190,000 Da and was predicted to be composed of four identical subunits with molecular masses of 45,000 Da. The purified enzyme hydrolyzed N-acetylglucosamine, N-acetylglucosamine 6-phosphate, and N-acetylglucosamine 6-sulfate, but not chitin oligosaccharides, and N-acetylgalactosamine. The deacetylase activity was completely abolished by N-ethylmaleimide, p-chloromercuribenzoate, EDTA, and Cu2+. On the other hand, the activity was activated by Co2+. The amino-terminal amino acids of the purified enzyme were sequenced. Among the 22 N-terminal amino acid residues, 12 residues of Vibrio deacetylase were identical with that of Escherichia coli GlcNAc 6-phosphate deacetylase.

Acetylglucosamine↗
PubMed1995

A second osmosensing signal transduction pathway in yeast. Hypotonic shock activates the PKC1 protein kinase-regulated cell integrity pathway.

Yeast cells respond to hypertonic shock by activation of a (MAP) mitogen-activated protein kinase cascade called the (HOG) high osmolarity glycerol response pathway. How yeast respond to hypotonic shock is unknown. Results of this investigation show that a second MAP kinase cascade in yeast called the protein kinase C1 (PKC1) pathway is activated by hypotonic shock. Tyrosine phosphorylation of the PKC1 pathway MAP kinase increased rapidly in cells following a shift of the external medium to lower osmolarity. The intensity of the response was proportional to the magnitude of the decrease in extracellular osmolarity. This response to hypotonic shock required upstream protein kinases of the PKC1 pathway. Increasing external osmolarity inhibited tyrosine phosphorylation of the PKC1 pathway MAP kinase, a response that was blocked by BCK1-20, a constitutively active mutant in an upstream protein kinase. These results indicate that yeast contain two osmosensing signal transduction pathways, the HOG pathway and the PKC1 pathway, that respond to hypertonic and hypotonic shock, respectively.

Calcium-Calmodulin-Dependent Protein Kinases↗
PubMed1995

The protein kinase C-activated MAP kinase pathway of Saccharomyces cerevisiae mediates a novel aspect of the heat shock response.

The PKC1 gene of budding yeast encodes a homolog of the alpha, beta, and gamma isoforms of mammalian PKC that is proposed to regulate a MAPK-activation pathway. Mutants in this pathway undergo cell lysis resulting from a deficiency in cell wall construction when they attempt to grow at elevated temperatures. We show that the PKC1-regulated pathway is important for induced thermotolerance and that the MPK1 protein kinase (the MAPK of this pathway) is strongly activated by mild heat shock. This activation is sustained during growth at high temperature and is dependent on the function of pathway components proposed to function upstream of MPK1, including PKC1. Expression of genes under the control of known heat shock-inducible promoter elements (HSEs and STREs) was not compromised in PKC1 pathway mutants, indicating that this pathway mediates a novel aspect of the yeast heat shock response. We propose that the heat-induced signal for pathway activation is generated in response to weakness in the cell wall created during growth under thermal stress, perhaps as a result of increased membrane fluidity. Evidence is presented that the mechanism by which the cell detects this weakness is by measuring stretch of the plasma membrane.

Base Sequence↗
PubMed1995

Dynamics and organization of MAP kinase signal pathways.

In the budding yeast, Saccharomyces cerevisiae, four separate but structurally related mitogen-activated protein kinase (MAPK) activation pathways are known. The best understood of these regulates mating. Pheromone binding to receptor informs cells of the proximity of a mating partner and induces differentiation to a mating competent state. The MAPK activation cascade mediating this signal is made up of Ste11 (a MEK kinase [MEKK]), Ste7 (a MAPK/ERK kinase [MEK]), and the redundant MAPK-related Fus3 and Kss1 enzymes. Another MAPK activation pathway is important for cell integrity and regulates cell wall construction. This cascade consists of Bck1 (a MEKK), the redundant Mkk1 and Mkk2 enzymes (MEKs), and Mpk1 (a MAPK). We exploited these two pathways to learn about the coordination and signal transmission fidelity of MAPK activation cascades. Two lines of evidence suggest that the activities of the mating and cell integrity pathways are coordinated during mating differentiation. First, cells deficient in Mpk1 are susceptible to lysis when they make a mating projection in response to pheromone. Second, Mpk1 activation during pheromone induction coincides with projection formation. The mechanism underlying this coordination is still unknown to us. Our working model is that projection formation generates a mobile second messenger for activation of the cell integrity pathway. Analysis of a STE7 mutation gave us some unanticipated but important insights into parameters important for fidelity of signal transmission. The Ste7 variant has a serine to proline substitution at position 368. Ste7-P368 has higher basal activity than the wild-type enzyme but still requires Ste11 for its function. Additionally, the proline substitution enables the variant to transmit the signal from mammalian Raf expressed in yeast. This novel activity suggests that Ste7-P368 is inherently more permissive than Ste7 in its interactions with MEKKs. Yet, Ste7-P368 cross function in the cell integrity pathway occurs only when it is highly overproduced or when Ste5 is missing. This behavior suggests that Ste5, which has been proposed to be a tether for the kinases in the mating pathway, contributes to Ste7 specificity and fidelity of signal transmission.

Calcium-Calmodulin-Dependent Protein Kinases↗