Biomedical subjects

K Yamauchi

Publications and source records attributed to K Yamauchi.

At least 163 records · Page 9Linked to original sources

PubMed1999

cDNA cloning of a stage-specific gene expressed during HCG-induced spermatogenesis in the Japanese eel.

A single injection of human chorionic gonadotropin (HCG) can induce complete spermatogenesis in immature Japanese eel (Anguilla japonica) testes consisting of only premitotic spermatogonia. Proliferation of spermatogonia, meiosis and spermiogenesis begin on 3, 12 and 18 days after HCG injection, respectively. To isolate the genes responsible for regulating the initiation of meiosis, differential mRNA display using poly (A)+ RNA extracted from testes of eels at different times after HCG treatment was carried out. Five cDNA clones in which expression was initiated before the onset of meiosis were obtained. Northern blot analysis showed that one clone, which encoded activin betaB subunit, was expressed in the initial phase of spermatogenesis (1-6 days after HCG treatment), in agreement with the previous suggestion that activin B induces the initiation of spermatogenesis in the Japanese eel. The remaining four were expressed in the testes during the following time frames: 3-18 days (two clones), 6-18 days (one clone) and 9-18 days (one clone) after HCG treatment. One of the two clones expressed on day 3 exhibited strong expression on days 12 and 15, just at the initiation period of meiosis. This clone was selected as a candidate gene responsible for initiating meiosis, and its full-length cDNA isolated. The cDNA contained an open reading frame of 1571 nucleotides encoding a protein of 260 amino acid residues, which showed high homology with the proliferating cell nuclear antigen (PCNA) of human, mouse and Xenopus. Northern blot analysis using eel PCNA cDNA showed that a 1.6 kb transcript first appeared on day 3 and became abundant, reaching maximum levels on days 12-15. In situ hybridization analysis revealed that PCNA mRNA was expressed strongly in late type B spermatogonia before the sixth mitotic division. It has already been shown that spermatogonia have a regulatory point to enter meiosis between the fifth and sixth mitotic division. The coincidence of PCNA expression and this regulatory point suggests an involvement of PCNA in the progression of mitotic germ cells into meiosis during HCG-induced spermatogenesis in the eel.

Anguilla↗

PubMed1999

A high molecular weight glycoprotein in seminal plasma is a sperm immobilizing factor in the teleost Nile tilapia, Oreochromis niloticus.

Sperm that have acquired potential for motility are kept immotile in seminal plasma in the teleost, Nile tilapia. In order to investigate the mechanism of immobilization, several experiments were performed using a previously characterized monoclonal antibody (TAT-30) against a molecular weight (Mr) = 120,000 protein that is secreted by Sertoli cells and epithelial cells of the sperm duct, and is also bound to the head of the spermatozoon. First, we assessed sperm motility in the seminal plasma protein fraction (SPP), and demonstrated that the sperm motility is inhibited by SPP in a concentration-dependent manner. Furthermore, sperm motility was recovered if SPP was pretreated with TAT-30, suggesting that the TAT-30 antigen is one of the components of the sperm immobilizing factor. Calibration by gel filtration followed by sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and western blotting with TAT-30 demonstrated that the sperm immobilizing factor was more than Mr = 1,000,000 in seminal plasma, suggesting that it is a homopolymer of the Mr = 120,000-TAT-30 positive protein. Additionally, lectin blot analysis showed that the TAT-30 antigen was reactive with Lens culinarin agglutinin (LCA) and Conavalia ensiformis agglutinin (ConA), indicating that it is a glycoprotein. Immunohistochemical studies showed that the TAT-30 antigen was localized specifically on the heads of spermatozoa and on the apical surface, lysosomes and rough endoplasmic reticulum of Sertoli cells.

Animals↗

PubMed1999

Discrimination of two different clinical entities, acute-type and subacute-type, human fulminant hepatitis by peripheral blood lymphocyte subsets.

Human fulminant hepatitis tends to be classified into two groups: acute type (A-FH) and subacute type (S-FH). In order to define these two clinical entities more precisely, we examined and compared peripheral blood lymphocyte subsets in A-FH and S-FH patients. We found that S-FH patients had a higher prevalence of CD19+ B cells (31.1 +/- 7.6% in S-FH vs 12.7 +/- 3.7% in A-FH) and also a lower prevalence of CD3+T cells (50.2 +/- 8.7% in S-FH vs 65.6 +/- 10.5% in A-FH). Furthermore, by examining the absolute cell numbers of these subsets, we determined that their imbalance in S-FH was mainly due to a decrease in CD3+ T cells. Among several T cell subsets, the CD8+CD11b-T cell subset was elevated in A-FH and decreased in S-FH (6.1 +/- 2.1% in S-FH, 24.4 +/- 5.8% in A-FH, and 14.8 +/- 7.8% in control). Serial studies of two S-FH patients revealed that the imbalance of these lymphocyte subsets returned to their proper ratio together with the improvement of their liver injury. These results indicate that there might be a different immunological background between A-FH and S-FH.

B-Lymphocyte Subsets↗

PubMed1999

Analysis of adhesion molecules in patients with idiopathic portal hypertension.

BACKGROUND: The aetiology of idiopathic portal hypertension (IPH) is unknown. However, some evidence of immunological abnormalities in IPH patients has been reported. METHODS: As adhesion molecules are important in the interaction between lymphocytes and accessory and target cells, the expression and release of the soluble form of vascular cell adhesion molecule-1 (VCAM-1) and intercellular adhesion molecule (ICAM-1) were examined in this study. RESULTS: In IPH patients, the serum level of soluble VCAM-1 was found to be increased, compared with that of healthy subjects, fatty liver patients and chronic hepatitis patients. The level of soluble ICAM-1 of IPH patients was found to be slightly increased, compared with that of healthy subjects; however, it was not different from the level in patients with other diseases. The expression of VCAM-1 was observed in the sinusoidal lining cells and endothelial cells around the liver vessels of several IPH patients. In contrast, ICAM-1 was weakly expressed in sinusoidal lining cells and hepatocytes in the liver tissue of only one of four IPH patients. CONCLUSIONS: This differential pattern of VCAM-1 and ICAM-1 was found in IPH patients and it was suggested that VCAM-1 might be an important molecule in the occurrence of IPH.

Case-Control Studies↗

PubMed1999

Effect of B7.1-transfected human colon cancer cells on the induction of autologous tumour-specific cytotoxic T cells.

BACKGROUND: The induction of tumour-specific immunity is important for advanced cancer therapy. There are many molecules, including costimulatory molecules, that have been identified as the activator for tumour-specific T cells. METHODS: To induce autologous tumour-specific cytotoxic T lymphocytes (CTL) more effectively, we studied whether the expression of the B7 gene may render human colon cancer cells able to stimulate autologous peripheral blood mononuclear cells (PBMC) to become tumour-specific cytotoxic T cells. After the establishment of a B7.1 gene transfected tumour cell line, Cw2/B7.1, we first examined its stimulatory effect on autologous PBMC and subsequently, its effect on the induction of parental cell (Cw2)-specific CTL. RESULTS: The results showed that Cw2/B7.1 had a more potent stimulatory effect on PBMC for the induction of both proliferation and cytotoxicity than Cw2. By adding a low dose of interleukin-2, Cw2/B7.1-activated killer cell activity was significantly increased. The specificity of Cw2/B7.1-activated killer cells was demonstrated by the absence of their cytotoxicity to either human lymphocyte antigen (HLA)-A33 identical (ORF) or HLA-non-identical (MT) allogenic colon cancer cell lines. Furthermore, such Cw2-specific cytotoxic activity was significantly reduced by the deletion of CD8+ cells but not CD4+ cells, indicating that these killer cells were mainly CD8+ T cells. CONCLUSIONS: Thus, our results demonstrate that, by using B7.1 gene-transfected tumour cell lines, we effectively induced autologous tumour-specific CTL. These results will provide us with new tools for adoptive immunotherapy for colon cancer patients.

B7-1 Antigen↗

PubMed1999

Schizophrenia: is it time to replace the term?

The attitudes of Japanese psychiatrists toward their patients who suffer from schizophrenia were investigated. We were concerned specifically with whether the psychiatrists inform their patients of the suspected diagnosis. We discuss how the term 'schizophrenia' may influence a psychiatrist's decision to inform his patients of the diagnosis. A self-reported questionnaire was distributed to 150 executive board members of the Japanese Society of Psychiatry and Neurology and analysis of the data obtained from 110 respondents was carried out. The results showed that the concepts that psychiatrists use when they give a diagnosis of schizophrenia vary considerably. Fifty-nine per cent of the respondents informed their patients of a diagnosis of schizophrenia on a case-by-case basis, while 37% informed only the patients' families. A tree analysis showed that the most important predictors for informing the patients of the diagnosis were assumptions about the public image of schizophrenia and a negative impression of the term schizophrenia, translated as 'Seishin Bunretsu Byou' in Japanese. The results revealed that the Japanese term for schizophrenia influences a psychiatrist's decision to inform patients of the diagnosis and that, by changing the term to a less stigmatized one, the disclosure of information about schizophrenia to patients would be promoted.

Attitude of Health Personnel↗

PubMed1999

Salmonid olfactory system-specific protein (N24) exhibits glutathione S-transferase class pi-like structure.

A salmonid olfactory system-specific protein (N24) that has been identified in lacustrine sockeye salmon (Oncorhynchus nerka) was characterized by biochemical and molecular biological techniques. N24 is a homodimer, and the intact molecular mass is estimated as approximately 43.3 kDa by gel filtration. Furthermore, N24 was located only in the cytosolic fraction of the olfactory tissues as determined by subcellular fractionation. cDNA encoding the lacustrine sockeye salmon N24 was isolated and sequenced. This cDNA contained a coding region encoding 216 amino acid residues and the molecular mass of this protein is calculated to be 242,224.77. The protein and nucleotide sequencing demonstrates the existence of a remarkable homology between N24 and glutathione S-transferase (GST; EC 2.5.1.18) class pi enzymes. Northern analysis showed that N24 mRNA with a length of 950 bases is expressed in lacustrine sockeye salmon olfactory epithelium. Olfactory receptor cells showed strong hybridization signals for N24 mRNA in the olfactory epithelium. N24 demonstrated glutathione binding activity in affinity-purified GST column experiments. The present study describes for the first time cDNA cloning of GST in fish olfactory epithelium.

Animals↗

PubMed1999

Effects of missense mutations on rat aquaporin-2 in LLC-PK1 porcine kidney cells.

BACKGROUND: Mutations in the aquaporin-2 (AQP2) gene have been found in families with nephrogenic diabetes insipidus (NDI), but the pathophysiological mechanisms of how mutant AQP2 causes the disease are still not clear. METHODS: Wild-type (WT) AQP2 and four mutants-T126M, A147T, R187C, and S216P-were transiently expressed in LLC-PK1 cells. The osmotic water permeability of LLC-PK1 cells expressing AQP2 mutants was determined by stopped-flow light-scattering microphotometry. Cell surface expression, subcellular localization, and effects of vasopressin stimulation were examined by surface biotin labeling and confocal immunohistochemistry. RESULTS: The osmotic water permeability (Pf) of cells expressing WT increased significantly after vasopressin treatment, whereas the Pf of cells expressing T126M A147T, R187C, and S216P was not significantly different from that of the control even after vasopressin stimulation. Confocal immunohistochemistry demonstrated distribution of WT and A147T in early/recycling endosomal compartments and vasopressin-responsive translocation and surface expression. In contrast, stainings of T126M, R187C, and S216P were similar to that of Grp78, indicating that these mutants were misassembled and retarded in the endoplasmic reticulum. CONCLUSION: Our results indicated that the intracellular distribution and vasopressin-regulated trafficking of A147T is intact, in contrast to the other three mutants, of which both were impaired. Thus, it is conceivable that the disruption of the AQP2 channel function accounts for the pathogenesis of A147T NDI, whereas trafficking defects account for that of the other types, suggesting that the pathophysiology of AQP2-related NDI is heterogeneous.

Animals↗

PubMed1999

Cloning and sequencing of a protein involved in phagosomal membrane fusion in Paramecium.

An mAb was raised to the C5 phagosomal antigen in Paramecium multimicronucleatum. To determine its function, the cDNA and genomic DNA encoding C5 were cloned. This antigen consisted of 315 amino acid residues with a predicted molecular weight of 36,594, a value similar to that determined by SDS-PAGE. Sequence comparisons uncovered a low but significant homology with a Schizosaccharomyces pombe protein and the C-terminal half of the beta-fructofuranosidase protein of Zymomonas mobilis. Lacking an obvious transmembrane domain or a possible signal sequence at the N terminus, C5 was predicted to be a soluble protein, whereas immunofluorescence data showed that it was present on the membranes of vesicles and digestive vacuoles (DVs). In cells that were minimally permeabilized but with intact DVs, C5 was found to be located on the cytosolic surface of the DV membranes. Immunoblotting of proteins from the purified and KCl-washed DVs showed that C5 was tightly bound to the DV membranes. Cryoelectron microscopy also confirmed that C5 was on the cytosolic surface of the discoidal vesicles, acidosomes, and lysosomes, organelles known to fuse with the membranes of the cytopharynx, the DVs of stages I (DV-I) and II (DV-II), respectively. Although C5 was concentrated more on the mature than on the young DV membranes, the striking observation was that the cytopharyngeal membrane that is derived from the discoidal vesicles was almost devoid of C5. Approximately 80% of the C5 was lost from the discoidal vesicle-derived membrane after this membrane fused with the cytopharyngeal membrane. Microinjection of the mAb to C5 greatly inhibited the fusion of the discoidal vesicles with the cytopharyngeal membrane and thus the incorporation of the discoidal vesicle membranes into the DV membranes. Taken together, these results suggest that C5 is a membrane protein that is involved in binding and/or fusion of the discoidal vesicles with the cytopharyngeal membrane that leads to DV formation.

Amino Acid Sequence↗

PubMed1999

1,2-dotriacontanedioyl-sn-glycero-3-phosphocholine: A cyclic lipid used for phospholipase A2-catalyzed modulation of the liposome surface charge.

An aqueous suspension of liposomes, which were made of cyclic 1, 2-dotriacontanedioyl-sn-glycero-3-phosphocholine (dTPC) and 1, 2-diphytanyl-sn-glycero-3-phosphocholine, was incubatedwith phospholipase A2 (Naja mossambica mossambica) in 0.05 M Tris-HCl, pH 7.7-7.8. At 25 degrees C, approximately 30% of the cyclic lipids was digested into 1-(omega-carboxyhentriacontanoyl)-sn-glycero-3-phosphocholine (lyso-dTPC), the original morphology being preserved but with a decrease in the zeta-potential of the membrane from ca. +2 to -1 mv. At 38 degrees C in 30 min, as much as 45% of the cyclic lipids was attacked by the lipase, which resulted in lowering of the potential to -2.5 to -3 mV. The enzymatic surface-charge modulation was discussed in conjunction with a side-selective attack of the phospholipase on the lipid bilayer.

Catalysis↗

PubMed1999

A mini-protein designed by removing a module from barnase: molecular modeling and NMR measurements of the conformation.

A globular domain can be decomposed into compact modules consisting of contiguous 10-30 amino acid residues. The correlation between modules and exons observed in different proteins suggests that each module was encoded by an ancestral exon and that modules were combined into globular domains by exon fusion. Barnase is a single domain RNase consisting of 110 amino acid residues and was decomposed into six modules. We designed a mini-protein by removing the second module, M2, from barnase in order to gain an insight into the structural and functional roles of the module. In the molecular modeling of the mini-protein, we evaluated thermodynamic stability and aqueous solubility together with mechanical stability of the model. We chemically synthesized a mini-barnase with (15)N-labeling at 10 residues, whose corresponding residues in barnase are all found in the region around the hydrophobic core. Circular dichroism and NMR measurements revealed that mini-barnase takes a non-random specific conformation that has a similar hydrophobic core structure to that of barnase. This result, that a module could be deleted without altering the structure of core region of barnase, supports the view that modules act as the building blocks of protein design.

Bacterial Proteins↗

PubMed1999

Recombinant human insulin-like growth factor I stimulates all stages of 11-ketotestosterone-induced spermatogenesis in the Japanese eel, Anguilla japonica, in vitro.

In this study, we examined the in vitro effects of insulin-like growth factor I (IGF-I) in the presence or absence of 11-ketotestosterone (11-KT: the spermatogenesis-inducing hormone) on the proliferation of Japanese eel (Anguilla japonica) testicular germ cells. Initially, a short-term culture (15 days) of testicular tissue with only type A and early type B spermatogonia (preproliferated spermatogonia) was carried out in Leibovitz-15 growth medium supplemented with different concentrations of recombinant human IGF (rhIGF)-I or -II in the presence or absence of 10 ng/ml of 11-KT. Late type B spermatogonia (proliferated spermatogonia) were observed in treatments of 100 ng/ml of both rhIGF-I and -II in combination with 11-KT, indicating the onset and progression of spermatogenesis. In all tested rhIGF-I concentrations (except 0.1 ng/ml) supplemented with 11-KT, late type B spermatogonia were detected in at least one individual. Then, we proceeded with an in vitro 45-day culture of testicular tissue with 100 ng/ml of rhIGF-I in the presence or absence of 10 ng/ml of 11-KT to test the long-term effects of rhIGF-I on the spermatogenetic cycle. The presence of all types of germ cells, including spermatozoa, in the testis cultured with the admixture of the two hormones indicated that the germ cells underwent complete spermatogenesis whereas no germ cell proliferation was observed when the rhIGF-I was applied alone. These results suggest that IGF-I in the presence of 11-KT plays an essential role in the onset, progress, and regulation of spermatogenesis in the testis of the Japanese eel.

Anguilla↗

PubMed1999

Decrease in the prevalence of IL-4-producing CD4+ T cells in patients with advanced stage of primary biliary cirrhosis.

OBJECTIVE: To elucidate the precise immunological features in primary biliary cirrhosis (PBC), we examined the relative prevalence of CD4+ T cells in either symptomatic PBC (sPBC) or asymptomatic PBC patients (aPBC), and furthermore, these results were compared with their histological features. METHODS: Cytokine synthesis of peripheral blood mononuclear cells obtained from 24 PBC patients (9 sPBC and 15 aPBC) were examined by intracellular staining method. The relative prevalence of three distinct CD4+ T cells, gamma-interferon (IFN-gamma)-producing cells (Th1), interleukin-4 (IL-4)-producing cells (Th2), and the cells producing both IL-4 and IFN-gamma (Th0), was analyzed by FACScan and compared with those of closely age-matched healthy and disease controls. RESULTS: The results demonstrated that although a significant difference was not observed in the prevalence of Th1 or Th0, a remarkable difference was observed in the prevalence of Th2 (1.2+/-0.7 in sPBC, 4.1+/-1.3 in healthy subjects, 4.1+/-2.1 in aPBC, 3.4+/-1.3 in chronic hepatitis C, and 3.6+/-2.3 in cirrhosis secondary to CH-C; p < 0.05 for sPBC vs all others). Histological examination of these patients showed that all aPBC patients belonged to relatively early stage (stage I-II) and 7 of 8 sPBC patients belonged to late stage (stage III-IV). Thus, our results suggest that, mainly as a result of the decline of Th2, a predominance of Th1 may exist in advanced stage PBC. CONCLUSIONS: The present results demonstrated that a slight elevation of Th1 prevalence, as well as a significant decline of Th2 prevalence, was observed in peripheral blood of advanced stage PBC.

Adult↗

PubMed1999

Identification of an acid-activated Cl(-) channel from human skeletal muscles.

ClC-4 gene was isolated as a putative Cl(-) channel. Due to a lack of functional expression of ClC-4, its physiological role remains unknown. We isolated a human ClC-4 clone (hClC-4sk) from human skeletal muscles and stably transfected it to Chinese hamster ovary cells. Whole cell patch-clamp studies showed that the hClC-4sk channel was activated by external acidic pH and inhibited by DIDS. It passed a strong outward Cl(-) current with a permeability sequence of I(-) > Cl(-) > F(-). The hClC-4sk has consensus sites for phosphorylation by protein kinase A (PKA); however, stimulation of PKA had no effect on the currents. hClC-4sk mRNA was expressed in excitable tissues, such as heart, brain, and skeletal muscle. These functional characteristics of hClC-4sk provide a clue to its physiological role in excitable cells.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗

PubMed1999

D-Glucose and insulin stimulate migration and tubular formation of human endothelial cells in vitro.

Effects of high D-glucose and insulin on the endothelial cell migration and tubular formation were investigated with the use of ECV304 cells, a clonal human umbilical cord endothelial cell line. Exposure of the cells to high D-glucose resulted in a marked increase in the migration, which was blocked by inhibitors of protein kinase C such as H7 (10 microM) and GF109203X (200 nM). Furthermore, a protein kinase C agonist, phorbol 12-myristate 13-acetate, had an effect similar to that of glucose on ECV304 cells. Glucose stimulation of the migration was additively enhanced by 100 nM insulin, and the insulin effect was found to be unaffected by either PD-98059 or wortmannin, a mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase inhibitor and a phosphatidylinositol 3-kinase inhibitor, respectively. Neither did H7 inhibit insulin stimulation of the migration. In contrast, a combination of high D-glucose and insulin, rather than either one alone, promoted tubular formation, which was inhibited by addition of 10 microM PD-98059. Stimulation of ECV304 cells by the combination of high D-glucose and insulin also caused an activation of MAPK, which was again obliterated by the same concentration of PD-98059. In conclusion, human endothelial cell migration and tubular formation are stimulated by high D-glucose and insulin in different ways. In the former reaction, either is effective, a combination of the two results in an additive effect, and activation of protein kinase C is involved. In contrast, tubular formation will only occur in the presence of a combination of high D-glucose and insulin, and MAPK plays an essential role.

Cell Line↗

PubMed1999

Functional analysis of aquaporin-2 mutants associated with nephrogenic diabetes insipidus by yeast expression.

Mutations of aquaporin-2 (AQP2) vasopressin water channel cause nephrogenic diabetes insipidus (NDI). It has been suggested that impaired routing of AQP2 mutants to the plasma membrane causes the disease; however, no determinations have been made of mutation-induced alterations of AQP2 channel water permeability. To address this issue, a series of AQP2 mutants were expressed in yeast, and the osmotic water permeability (P(f)) of the isolated vesicles was measured. Wild-type and mutant AQP2 were expressed equally well in vesicles. P(f) of the vesicles containing wild-type AQP2 was 22 times greater than that of the control, which was sensitive to mercury and weakly dependent on the temperature. P(f) measurements and mercury inhibition examinations suggested that mutants L22V and P262L are fully functional, whereas mutants N68S, R187C, and S216P are partially functional. In contrast, mutants N123D, T125M, T126M, A147T, and C181W had very low water permeability. Our results suggest that the structure between the third and fifth hydrophilic loops is critical for the functional integrity of the AQP2 water channel and that disruption of AQP2 water permeability by mutations may cause NDI.

Animals↗

PubMed1999

Clinical implication of vascular cell adhesion molecule-1 and very late activation antigen-4 interaction, and matrix metalloproteinase-2 production in patients with liver disease.

OBJECTIVES: To clarify the role of adhesion molecule in liver cell injury. PATIENTS AND METHODS: The serum levels of soluble vascular cell adhesion molecule-1 (sVCAM-1), and the expression of VCAM-1 and its ligand, very late activation antigen-4 (VLA-4), were examined in patients with various liver diseases. In addition, the presence of matrix metalloproteinase-2 (MMP-2) was investigated because the release of MMP-2 is thought to be mediated by VLA-4-positive cells. sVCAM-1 and MMP-2 were measured by ELISA assay, and VCAM-1 and VLA-4 were studied by immuno-histological methods. RESULTS: In acute hepatitis (AH) patients, the serum level of sVCAM-1 was significantly elevated compared with that in other cohorts. VCAM-1 was expressed on sinusoidal lining cells but not on hepatocytes. In patients with chronic liver disease, sVCAM-1 levels rose in concert with the progression of chronic hepatitis (CH), and VCAM-1 was also expressed. VLA-4 was detected in both mononuclear cells and Kupffer cells in AH livers, but mainly in Kupffer cells in patients with CH. In AH patients, MMP-2 levels were similar to those in control subjects, but in CH and liver cirrhosis patients, MMP-2 level was elevated in association with CH progression. CONCLUSIONS: The immune response through the VCAM-1 and VLA-4 pathways is important in hepatocyte injury, especially in AH patients, to attach VLA-4-positive mononuclear cells to VCAM-1-positive sinusoidal lining cells. The distribution of VLA-4-positive cells differs between AH and CH patients. VLA-4-positive Kupffer cells in chronic liver diseases might be involved in the progression of CH, perhaps through the mechanism of upregulation of MMP-2 production.

Acute Disease↗

PubMed1999

Evaluation of a PC-based teleconferencing system for reading chest radiographs.

Chest radiographs from 50 patients, including 25 with lung cancer, were digitized at a resolution of 100 dots/inch (40 dots/cm) and saved in JPEG format at a low compression ratio. The average size of the stored images was 55 kByte (range 6-86 kByte). Four respiratory specialists observed these images on the cathode ray tube (CRT) display of a PC-based teleconferencing system with a resolution of 800 x 600 pixels. One month later they observed the original chest radiographs. A receiver operating characteristic (ROC) analysis was performed on their diagnoses, based on a five-point confidence scale about the presence of lung cancer. The observer-specific Az values for the teleconferencing system ranged from 0.801 to 0.944, and the corresponding Az values for the conventional radiographs from 0.926 to 0.957. No significant differences were found between the teleconferencing images and the original images, which suggests that a PC-based teleconferencing system could be useful in the diagnosis of lung cancer on chest radiographs.

Evaluation Studies as Topic↗