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Biomedical subjects

H Nakata

Publications and source records attributed to H Nakata.

At least 109 records · Page 6Linked to original sources
PubMed1997

Evaluation of an automatic-mode image processing method in chest computed radiography.

RATIONALE AND OBJECTIVES: The automatic image processing mode of the storage phosphor computed radiography system was evaluated. MATERIALS AND METHODS: A dedicated chest unit designed for erect view was used to examine a chest phantom. Lucite plates 1, 2, and 3 cm thick that conformed to the shape of the lung were attached to the phantom, and images were obtained in automatic and manual image processing modes. The changes in the optical density of the lung, rib, and heart and the changes in contrast were measured. The degree of diffuse opacity due to the plates and the visibility of superimposed simulated nodular and honeycomb opacities were evaluated. RESULTS: The decrease in optical density and contrast caused by increasing thickness of the Lucite plates was less pronounced in the automatic mode compared with the manual mode. When plates were placed only on the right lung, the optical density and the contrast on the contralateral side either increased or remained unchanged with the automatic mode. The degree of diffuse opacity was rated higher in the manual mode, and the visibility of superimposed simulated opacities was considered relatively constant in the automatic mode. CONCLUSION: The automatic image reading mode used in the computed radiography chest system may mask the detection of abnormalities such as diffuse homogeneous lung opacity.

Evaluation Studies as Topic↗
PubMed1997

[Serological differences in Helicobacter pylori].

To study antigenic differences in Helicobacter pylori (H. pylori), we performed immunoblot (IB) analysis with monoclonal antibody, MAb102, and measured the serum antibody titer with captured ELISA method with MAb102 antibody. In IB analysis, specific 54 K antigen was detected in 39 strains derived from patients with gastritis, gastric ulcer, duodenal ulcer, and gastric carcinoma. But only one strain (GC32 strain) isolated from a patient with gastric cancer did not react with MAb102 antibody. In the result of antibody titer with captured ELISA method using other six strains of H. pylori as antigen, H. pylori strains were divided into 3 groups, group R (RD26, T7, and T13 strains), group E (England and MR31 strains), group T (T37 strain). However, four cases belonged to false negative in ELISA method. These cases could have been infected with H. pylori strains such as GC32 strain. These strains did not have 54 K antigen nor 54 K related antigen which is different in its antigenicity from the 54 K antigen of the six strains. Thus the GC35 strain and the strain(s), which infected these four cases, consisted of other group, group N. These results suggested that 54 K antigen is usually stable in many strains, but occasionally different in antigenicity in some strains.

Adult↗
PubMed1997

Helicobacter pylori independent chronological change in gastric acid secretion in the Japanese.

BACKGROUND: Gastric acid secretion in Japanese subjects decreases with aging. One of the possible causative mechanisms of this attenuated acid secretion is speculated to be a Helicobacter pylori induced chronic gastritis. The infection rate of this microorganism has decreased recently in Japan. AIMS: To investigate whether gastric acid secretion has altered over the past 20 years, and if so, what the influence of H pylori infection might be in the Japanese population. SUBJECTS AND METHODS: Gastric acid secretion, serum gastrin and pepsinogen I and II concentrations, and H pylori infection were determined in 110 Japanese subjects in both the 1970s and 1990s. RESULTS: Basal acid output as well as maximal acid output have greatly increased over the past 20 years, not only in individuals with H pylori infection but also in those without infection. Furthermore, subjects with H pylori infection tended to show decreased gastric acid secretion in comparison with those without infection, particularly in geriatric subjects. There was a positive correlation between gastric acid secretion and serum pepsinogen I concentrations. CONCLUSIONS: In Japan, both basal and stimulated gastric acid secretion have increased over the past 20 years; some unknown factors other than the decrease in H pylori infection may play an important role in this phenomenon.

Adult↗
PubMed1997

Relationship between changes of bone mineral content and twelve-minute walking distance in men with chronic obstructive pulmonary disease: a longitudinal study.

Cross-sectional studies have revealed that bone mass is reduced in patients with chronic obstructive pulmonary disease (COPD). To elucidate the factors influencing bone mass in COPD, we measured whole body bone mineral content (BMC) by dual energy X-ray absorptiometry (DXA), pulmonary function, and twelve-minute walking distance (TMD) in men with COPD, who had been monitored for at least one year. We studied the body composition in 22 male patients with COPD and 19 age-matched male controls (age 72.6 +/- 7.2 vs 67.5 +/- 10.1 years, mean +/- SD). COPD patients showed a significantly lower body weight (49.3 +/- 5.7 vs 57.9 +/- 3.5 kg, respectively), body mass index (18.9 +/- 2.1 vs 22.1 +/- 1.3 kg/m2) and BMC (1.9 +/- 0.4 vs 2.2 +/- 0.4 kg) than controls. The changes in BMC were significantly correlated with TMD (r=0.53, p<0.02). These results demonstrate that decreased exercise capacity, at least in part, accounts for acceleration of bone mass loss in COPD patients.

Aged↗
PubMed1997

[Evaluation of left ventricular systolic function using cine MRI--application to hypertrophic cardiomyopathy].

Cine MRI is a useful means to analyse the anatomical and functional changes of hypertrophic cardiomyopathy. The visual evaluation of hypertrophic regions and the motion patterns of their walls is in most cases possible on cine MR images. To complement a subjective method a certain quantitative analysis is necessary. Left ventricular regional systolic function can be quantitatively evaluated using cine MRI images printed on films. There is a good correlation between % thickness of LV wall and its thickness at end diastolic phase. The comparison of % thickness of normal subjects with that of hypertrophic cardiomyopathies shows a tendency of its value being less at the region of more severe hypertrophic change.

Cardiomyopathy, Hypertrophic↗
PubMed1997

[Bronchial hyperresponsiveness in patients with vasospastic angina pectoris (VSAP)].

To determine the relationship between airway and coronary artery spasmogenesity in patients with vasospastic angina pectoris (VSAP), we measured the bronchial responsiveness to inhaled methacholine in 21 VSAP patients (V-group) and compared it to that of 17 chest pain syndrome patients with normal coronary (N-group). In the V-group, logarithmic values of the minimum cumulative dose required to decrease respiratory conductance from the baseline (Log Dmin) was significantly lower than that in N-group (0.47 +/- 0.60 log units vs. 0.98 +/- 0.60 log units respectively, p < 0.05). Log Dmin was significantly correlated with the dose of acetylcholine which induced a greater than 90% stenosis of the coronary artery (r = 0.383, p < 0.05). We concluded that both the coronary artery and the airway show hyperresponsiveness to cholinergic agonists in patients with VSAP.

Aged↗
PubMed1996

Identification of planarian serotonin receptor by ligand binding and PCR studies.

Binding sites for [3H]lysergic acid diethylamide (LSD), a serotonin receptor agonist, were identified in planarian membranes by ligand binding studies. The Kd and Bmax values were approximately 4 microM and 0.2 pmol mg-1 protein, respectively. The serotonin (5-HT) receptor antagonists methiothepin and dihydroergocriptine were also efficient displacers of [3H]LSD binding. When planarians were decapitated in the presence of these antagonists, head regeneration was significantly retarded. These results suggest that planarians possess LSD binding sites which are involved in the process of regeneration. Furthermore, we found a putative (5-HT) receptor expressed in planarians by the degenerate primer polymerase chain reaction.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed1996

Expression of neurofilament proteins in proliferating C2C12 mouse skeletal muscle cells.

Expression of neurofilament proteins, NF140K, NF68K, and NF200K, in C2C12 mouse skeletal muscle cells was studied. Immunofluorescence and immunoblot analyses revealed that NF140K was expressed in proliferating C2C12 cells and its localization was similar to desmin, a muscle-specific intermediate filament protein. NF140K became undetectable in C2C12 cells as muscle cell differentiation proceeded. Reverse transcription-polymerase chain reaction (RT-PCR) and Northern blot analyses confirmed the expression of NF140K, NF68K, and NF200K in proliferating C2C12 cells. Sequences of the RT-PCR products of NF140K and NF68K were identical to that of authentic mouse NF140K and NF68K, respectively. The NF140K and NF68K mRNA were down-regulated during myogenesis in contrast to the up-regulation of mRNA encoding troponin-T. Furthermore, subcloned C2C12 cells, which express NF140K at a higher level, exhibited retarded myogenesis, i.e., delayed onset of myosin heavy chain synthesis and myoblast fusion. These results suggest that neurofilament proteins may play an inhibitory role in commitment of muscle cell differentiation. The presence of neurofilament proteins in skeletal muscle cells indicates that desmin, vimentin, and neurofilament proteins can be expressed in a single muscle cell.

Animals↗
PubMed1996

3-Hydroxy-3-methylglutaryl coenzyme A reductase inhibitor impairs cell p4fferentiation in cultured adipogenic cells (3T3-L1).

Lovastatin, a 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor, inhibits the synthesis of mevalonic acid. We examined the effect of lovastatin on the differentiation of the fibroblast/adipocyte cell line (3T3-L1). Lovastatin inhibits the differentiation of 3T3-L1 cells in a dose-dependent fashion. The inhibitory effect of lovastatin was partially reversed by adding exogenous mevalonic acid to the 3T3-L1 cells. Exogenous cholesterol (15 micrograms/ml) did not prevent lovastatin inhibition of adipocyte conversion. The isoprenoids, farnesol and geraniol, partially prevented lovastatin inhibition of adipocyte conversion but squalene did not prevent lovastatin inhibition of adipocyte conversion. We conclude that the inhibitory effect of lovastatin was partially due to the blockade of the pathway leading to synthesis of isoprenoids, which are downstream products of mevalonic acid.

3T3 Cells↗
PubMed1996

[Characteristics and limitations of three-dimensional spiral CT--experimental evaluation].

We evaluated the image quality of three-dimensional (3D) spiral CT using a Somatom Plus CT scanner (Siemens, Germany). A T-shaped acrylate plastic model was made and scanning was performed with a table speed of 5 mm/sec for 24 seconds. The thickness of the X-ray beam was 5mm with one second per rotation. The various images of the model were created based on the shaded surface display (SSD) method and the effect of threshold and rotation (spin and tilt) on the quality of the 3D images was studied. The increase of threshold caused a rapid decrease in the diameter of the stick observed on the film, and this phenomenon was particularly remarkable on the transverse stick and the junctional portion of the longitudinal stick. The change of spin or tilt did not affect the diameter of the stick on the film. It was found that the depth perception of the stick could be achieved with the gray scale technique. We concluded that the interpretation of the 3D spiral CT image obtained with SSD needs caution and the diagnosis should not be made only on this image.

Humans↗
PubMed1996

alpha-1-Adrenergic receptor stimulation causes arachidonic acid release through pertussis toxin-sensitive GTP-binding protein and JNK activation in rabbit aortic smooth muscle cells.

In the present study, we investigated the mechanism of phenylephrine (alpha-1-adrenergic receptor agonist)-induced arachidonic acid release in Japanese white rabbit aortic smooth muscle cells (SMC). When introduced into permeabilized smooth muscle cells, guanosine S-[gamma-thio] triphosphate (GTPgamma S), which activates GTP-binding proteins (G proteins), stimulated arachidonic acid (AA) release. Neomycin, an inhibitor of phosphoinositide (PI) turnover, was almost without effect on GTP[gamma S] stimulated AA release. In addition, pertussis toxin (PT) partially inhibited phenylephrine-stimulated AA release, suggesting that IAP (Islet activating protein)-sensitive G proteins mediate this process. Phenylephrine-stimulated AA release was also inhibited by decreased extracellular calcium and aristolochic acid, suggesting a role for a phospholipase A2 (PLA2). Next PLA2 is reported to be a substrate for mitogen-activated protein (MAP) kinase. We examined the effect of phenylephrine on MAP kinase and c-jun N-terminal kinase (JNK) phosphorylation. Phenylephrine didn't induce phosphorylation of MAP kinase, but did induce phosphorylation of JNK. In addition, cells which were pretreated with PT inhibited the phosphorylation of JNK. These results suggest that IAP-sensitive G protein is involved in the coupling between alpha1-adrenergic receptor (AR) and PLA2 in cultured rabbit aortic SMCs, and that the alpha1-AR-induced AA release is mediated by JNK.

Amyloid↗
PubMed1996

Photoaffinity labeling of a P3 purinoceptor-like protein purified from rat brain membranes.

We have found a novel adenosine binding protein in rat brain membranes. Based on the ligand binding specificities, this protein is not classified into any known P1 or P2 purinoceptors but is likely to be classified into the putative P3 purinoceptor which was recently proposed. This P3 purinoceptor-like protein was partially purified from rat brain membranes and characterized further by photoaffinity labeling with 8-azidoadenosine-5'-[gamma-32P]triphosphate. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the labeled preparations revealed that the probe is incorporated specifically into a single band with an approximate molecular size of 54 kDa.

Adenine Nucleotides↗
PubMed1996

Proliferation and differentiation of PC12 cells were affected by p21ras GTPase activating proteins and its deletion mutant proteins.

In this study, a mammalian expression vector containing cDNA of human GAP (p120GAP) or its deletion mutant was transfected into PC12 cells. The deletion mutant peptide has SH2 and SH3 domains, but no GTPase activating domain. Cells stably overexpressing intact p120GAP showed enhanced proliferation, demonstrated by 5-bromo-2'-deoxyuridine labeling and cell cycle analysis. On the other hand, in cells expressing the deletion mutant GAP, differentiation induced by NGF was potentiated, as demonstrated by enhanced acetylcholinesterase activity and induction of neurofilament proteins.

Acetylcholinesterase↗
PubMed1996

Clinical evaluation of irreversible data compression for computed radiography in excretory urography.

Efficient data compression is required for practical daily use of digital images in computed radiography (CR). This study investigated the clinical utility of data compression in excretory urography using the FCR 9000 system (Fuji Photo Film, Tokyo, Japan). Type III data compression technique was used, which can achieve a 20:1 to 25:1 compression ratio. To evaluate the degradation of image quality, we compared paired original and compressed CR images. Although a slight deterioration of image quality was noted in the renal calyx including collecting tubules among various anatomical structures, the difference was not significant. Receiver operating characteristics analysis revealed no significant difference among the original and compressed images. We conclude that compressed CR images using Type III data compression technique in excretory urography appear to be clinically applicable and acceptable.

Adolescent↗