PubMed Health⌕ Search

Biomedical subjects

N Kamata

Publications and source records attributed to N Kamata.

At least 37 records · Page 2Linked to original sources
PubMed1998

[A clinical and portal hemodynamic analysis for obliteration of gastric-renal shunt communicated with gastric fundic varices].

To clear the efficacy of treatment for large porto-systemic shunts, changes of liver function and portal hemodynamics after obliteration of gastric-renal shunt (GRS) or gastric-inferior phrenic vein shunt (GIS) communicated with gastric fundic varies in 24 patients treated with balloon-occluded retrograde transvenous obliteration (B-RTO) were studied. 1) The wedged hepatic venous pressure and the hepatic venous pressure gradient were statistically not significant changed after obliteration of GRS or GIS. 2) Serum albumin value was significantly increased (p < 0.005) and ICGR15 was significantly improved (p < 0.005) at one year after treatment in patients that, not only whose GRS or GIS were larger than 10mm in diameter, but also whose superior mesenteric arterial venography before treatment showed hepatofugal flow. 3) At a mean follow-up abdominal angiography of 23.3 months in 20 cases, GRS or GIS was yet obliterated respectively. And more, superior mesenteric arterial venography revealed hepatopetal flow alone in 43% of patients that, whose superior mesenteric arterial venography before treatment showed hepatofugal flow. 4) During a mean follow-up of 32.5 months, gastric fundic varies were not recurrent in all patients, but the other hand, cumulative red color sign positive esophageal varies apparent rates were high (16.7% at before treatment, 38.4% at 2-years, 54.4% at 4-years). According to their hemodynamic characteristics, cumulative red color sign positive esophageal varies apparent rates in patients with another collaterals besides GRS or GIS before treatment (26.7% at before treatment, 61.1% at 2-years, 74.1% at 4-years) were significantly higher (p < 0.05) than those in patients without another collateral except GRS or GIS (0% at 2-years, 16.7% at 4-years). We conclude that, 1) Increment of portal flom and improvement of liver function can be expected by obliteration of GRS or GIS in patients that, whose superior mesenteric venous blood flow into large GRS or GIS. 2) After obliteration of GRS or GIS, the incidence of aggravation of esophageal varies in patients with another collaterals besides GRS or GIS before treatment is high, while that in cases without another collateral is low.

Adult↗
PubMed1997

DNA damage-associated dysregulation of the cell cycle and apoptosis control in cells with germ-line p53 mutation.

Lymphoblastoid cell lines (LCLs) with heterozygous p53 mutations at residues 286A, 133R, 282W, 132E, and 213ter were established from five independent Li-Fraumeni syndrome families. When cell cycle regulation in response to gamma-irradiation was studied, these LCLs showed an abnormal G1 checkpoint associated with defective inhibition of cyclin E/cyclin-dependent kinase 2 activity in all cases except for 282W LCL, which showed a normal G1 checkpoint. On the other hand, the control of S-phase-G2 as determined by cyclin A/cyclin-dependent kinase 2 activity was defective in all these LCLs. The mitotic checkpoint was also defective in the two LCLs analyzed as either competent or incompetent for G1 arrest. When radiation-induced apoptosis, which requires wild-type p53 function under optimal conditions, was studied, all of these LCLs showed significant failure compared to normal LCLs. These findings indicate that although p53-dependent transactivation and G1-S-phase cell cycle control are variably dysregulated, the induction of apoptosis and control of the cell cycle at S-phase-G2 and the mitotic checkpoint in response to DNA-damaging agents are consistently dysregulated in heterozygous mutant LCLs. This suggests that these dysfunctions underlie, at least in part, the susceptibility of Li-Fraumeni syndrome families to cancer. Furthermore, the approach presented is a potentially useful method for studying individual carriers of different germ-line p53 mutations and different biological features.

Adolescent↗
PubMed1997

Immunoadsorption for the treatment of bullous pemphigoid.

We treated 2 intractable patients with pemphigoid by absorbent plasmapheresis using dextran sulfate conjugated cellulose columns with an automated regenerating unit. During a 2 week period, this plasmapheresis was performed 4 to 6 times for Cases 1 and 2, respectively. Clinical findings including skin eruptions were remarkably improved, and the titers of antibasement membrane zone antibodies were decreased after the treatment of 1.8 to 4.2 L of plasma. These results suggest that the absorbent column is effective for intractable pemphigoid.

Aged↗
PubMed1997

Increased coronary vasomotor tone in acute myocardial infarction patients with spontaneous coronary recanalization.

To clarify the role of coronary spasm or dynamic coronary obstruction in the development of acute myocardial infarction (AMI) with spontaneous recanalization (SR), symptoms in 296 patients with AMI admitted within 24 h after the onset of chest pain were analyzed just before and after onset, and coronary angiograms were analyzed soon after onset. Patients were divided into 3 groups according to the initial angiographic findings in the infarct-related coronary artery (IRCA): group 1 comprised 172 patients with total occlusion (TIMI O); group 2 comprised 57 patients with subtotal occlusion (TIMI 1,2); and group 3 comprised 67 patients with SR (TIMI 3). The incidence of SR was 20.3% at 0-4 h after onset, 22.2% at 4-6 h, 19.7% at 6-12 h, 24.0% at 12-24 h, and 36.0% at 24 h or later. The incidence of SR did not increase significantly as time elapsed. The incidence of angina at rest and variable-threshold angina before the onset of infarction was only 16.2% in group 1, but was significantly higher in groups 2 (64.3%) and 3 (61.9%). The incidence of intermittent chest pain at onset in group 1 (8.4%) was significantly lower than in groups 2 (54.5%) and 3 (38.8%). Vasodilation of the proximal normal segment adjacent to the stenotic site of the IRCA induced by intracoronary nitroglycerin was significantly higher in groups 2 (11.7 +/- 1.2%) and 3 (20.7 +/- 2.6%) than in group 1 (4.0 +/- 0.6%). These results suggest that coronary spasm or dynamic obstruction may be involved in the pathogenesis of thrombus formation or coronary obstruction causing AMI in many Japanese patients.

Adult↗
PubMed1996

Intraoral free flap monitoring with a laser Doppler flowmeter.

The blood flow in 37 free flaps used for intraoral reconstruction was measured by laser Doppler flowmetry before and after elevation of the flap during surgery, immediately after the completion of reconstruction and on the 1st, 2nd and 3rd postoperative days (1 POD, 2 POD, 3 POD). Although the blood flow decreased temporarily after the flap elevation, it began to increase immediately after reconstruction and continued a gradual increase thereafter, reaching a peak on 2 POD. The flap survived in all cases where the blood flow on 3 POD was equal to or greater than that before flap elevation. Total necrosis of the flap occurred in one patient, and partial necrosis in another. In both patients, abnormal laser flow-metric measurements preceded the manifestation of the clinical signs. Using laser Doppler flowmetry to monitor free flaps both during surgery and for three days thereafter is thus a useful way of determining their viability.

Feasibility Studies↗
PubMed1996

Long-term nitrate treatment increases cardiac events in patients with healed myocardial infarction. Secondary Prevention Group.

BACKGROUND: Nitrates dilate coronary arteries, ameliorate myocardial ischemia, minimize left ventricular remodeling, and reduce mortality in patients with acute myocardial infarction. However, the effects of long-term treatment with nitrates on cardiac events in patients with healed myocardial infarction are not known. METHODS AND RESULTS: A total of 1,002 patients with healed myocardial infarction (789 male and 213 female) were randomly divided into 2 groups: treatment with nitrates or nontreatment. The mean observation period was 18.0 +/- 19.9 months. Primary end points were nonfatal and fatal recurrent myocardial infarction, death from congestive heart failure, and sudden death. Baseline characteristics of the 2 groups were also compared to determine any effects on outcome. Among the 621 cases treated with nitrates, 41 cases (6.6%) experienced cardiac events during the observation period, whereas only 12 of the 381 cases that were not treated with nitrates (3.1%) had cardiac events. This difference was statistically significant (p < 0.05; odds ratio 2.17; 95% confidence interval 1.13-4.19). There were no differences in the incidence of noncardiac death or being lost to follow-up between the 2 groups. Although the precise mechanism of this increase in the occurrence of cardiac events by long-term treatment with nitrates is not clear, nitrate tolerance with possible rebound and neurohormonal effects may be involved. CONCLUSION: Long-term treatment with nitrates increased cardiac events in patients with healed myocardial infarction.

Aged↗
PubMed1996

Comparison of pH and ionic strength dependence of interactions between monoclonal antibodies and bovine beta-lactoglobulin.

A panel of 13 monoclonal antibodies (mAbs) against distinct determinants on bovine beta-lactoglobulin, a model protein antigen, were examined and compared for their ability to bind and desorb from the antigen at differing pHs and ionic strengths by an enzyme-linked immunosorbent assay and elution assay. Among them, mAb 61C1 was found to be highly sensitive to the pH, and 3 in 4 mAbs directed to the region 42-56 also strongly depended on the change in ionic strength. Because of the large proportion of charged amino acid residues in the region 42-56, the electrostatic forces are considered to be more predominant than the hydrophobic interactions in the latter antigen-antibody reactions, thereby resulting in their high sensitivity to the ionic strength.

Amino Acid Sequence↗
PubMed1996

Postparturient change in endotoxin levels of ruminal fluid and serum in dairy cows.

The changes in the endotoxin levels of ruminal fluid and serum in postparturient cows were evaluated. Five cows were fed hay and concentrates on an individual basis (farm A) and the other 5 cows were given complete feed ad libitum (farm B) after parturition. Ruminal pH levels decreased in both groups after parturition. Subsequently, the ruminal endotoxin levels increased with the declining pH on both of the farms. The ruminal endotoxin levels were slightly higher in cows of farm B than those of farm A. Serum endotoxin levels also showed episodic fluctuations, however, there were no parallel changes between the endotoxin levels of the ruminal fluid and sera.

Animals↗
PubMed1996

[Fundamental study of lung-cancer screening by helical CT: second report: evaluation of CT images using normal volunteers].

In order to examine the use of helical computed tomography (CT) in lung cancer screening, we evaluated the effects of tube current and table feed speed on image quality. CT images of normal volunteers, which were scanned under various tube currents (150mA, 100mA, 50mA) and various table feed speeds (15mm/sec, 20mm/sec, 25mm/sec, 30mm/sec), were visually evaluated by experienced diagnostic radiologists. The images were not affected by decreasing the milliamperage. However, as table feed speed increased, images were evaluated as significantly worse. Particularly, since the degradation of the images scanned at greater than 25mm/sec was remarkable, they were judged to be unacceptable for detection of the abnormality. In conclusion, a tube current of less than 50mA and table feed speed of less than 20mm/sec are suitable in the application of helical CT for lung cancer screening.

Adult↗
PubMed1995

New collateral flow increasing early after coronary occlusion prevented myocardial necrosis in dogs.

Increases in regional myocardial blood flow (Qm) developing soon after myocardial infarction may minimize myocardial necrosis. To test this hypothesis, Qm in the area surrounding an acutely occluded coronary artery was determined successively over 4 weeks in 11 dogs. Non-radioactive colored microspheres were injected into the left atrium 5 s (Qm at this time is referred to as Q1), 3 h (Q2), 12 h (Q3), and 4 weeks (Q4) after occlusion of the coronary artery. After termination of the experiment, the heart was removed, and Qm and three indices of myocardial necrosis i.e., myocardial creatine kinase activity (CK), infarct size determined by triphenyl tetrazolium chloride stain (TTC), and myocardial fibrosis visualized by Azan-Mallory stain, were determined. Each Qm was expressed as a percentage of normal: Qm (% of normal) = [Q/Qc] ischemic area/[Q'/Qc']non-ischemic area x 100, where Qc indicates Qm determined before coronary occlusion. In the ischemic area of the left ventricle, Q1, Q2, Q3, and Q4 were 25 +/- 3%, 30 +/- 3%, 31 +/- 3%, and 42 +/- 3% of normal, respectively, in the inner layer, and 31 +/- 3%, 52 +/- 4%, 52 +/- 4%, and 77 +/- 6% of normal, respectively, in the outer layers. During the 4-week period, the increase of Qm in the outer layer was greater than that in the inner layer. The inner layer showed a small increase of flow from Q3 to Q4 (9 +/- 2%), but in the outer layer there were greater flow increases from Q1 to Q2 (21 +/- 3%) and from Q3 to Q4 (24 +/- 6%).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

[Optimal concentration of contrast medium in helical CT of the thorax].

In 99 examinations of 89 patients, we took CT images of the chest after administering one of three concentrations of contrast medium (iohexol 140 mgI/ml, 240 mgI/ml, 300 mgI/ml) to determine the optimal iodo-concentration for intravenous contrast enhancement in spiral CT. Attenuation values of the superior vena cava, ascending aorta, descending aorta, and pulmonary artery were measured to evaluate the degree of contrast enhancement. Five radiologists judged the image quality by scoring factors such as vascular opacification, delineation of the lung and chest wall, detectability of calcification, lymphadenopathy and pulmonary nodules, and the presence of artifacts. The relationships between the iodo-concentration and the scores were analyzed statistically. The higher the iodo-concentration of the contrast medium administered, the stronger the vascular structures were opacified. There was also a concurrent improvement in the detection of lymphadenopathy. However, artifacts appeared on the administration route as a result of the high-concentration contrast medium, and the image quality was degraded. Among the three groups, iohexol 240 mgI/ml exhibited the best performance, namely, good image quality, so that a high degree of contrast enhancement of the vasculature was obtained with few artifacts due to the contrast medium. However, we believe that iohexol 140 mgI/ml presents no significant problems in routine studies.

Adult↗
PubMed1994

Antibodies elicited by the primary response are useful as ligands for immunoaffinity chromatography.

A suitable antibody for immunoaffinity chromatography is considered to efficiently bind the antigen in the adsorption step and to dissociate the bound antigen with mild changes in the environmental conditions. To develop an effective method for preparing such antibodies, murine antisera elicited by the primary and secondary responses against bovine beta-lactoglobulin, a model protein antigen, were examined and compared for their ability to bind the antigen under differing pH and ionic strength conditions. Antibodies from the primary response were usually found to be highly sensitive to changes in pH and ionic strength, suggesting that these antibodies may be useful as ligands for immunoaffinity chromatography.

Animals↗
PubMed1994

Myristylation-dependent transactivation by FBR v-fos is regulated by C/EBP.

Viral oncogenes are generally believed to cause transformation through disregulated mimicry of their cellular homologues. However, here we show that FBR v-fos, unlike c-fos, transcriptionally activates unique genes in retrovirally induced chondro-osseous sarcomas. We show that FBR v-fos transactivates the collagen III and stromelysin promoters and that the unique transcriptional properties of transforming FBR depend upon its N-terminal myristylation and the differentiation state of the cell. Deletion or mutation of the myristylation site results in a loss of FBR v-fos transactivation in HeLa and undifferentiated 3T3-L1 preadipocyte cell lines. FBR v-fos transactivation of collagen III maps to a negative regulatory site which binds a key regulator of adipocyte differentiation, C/EBP alpha. Cotransfection of C/EBP alpha abolishes FBR v-fos transactivation of the alpha 1(III) collagen promoter. Furthermore, FBR v-fos cannot transactivate collagen III subsequent to adipocyte differentiation. We also demonstrate that collagen III transcription is reduced during adipocyte differentiation as the transcriptional activity of C/EBP alpha is concomitantly induced. Our results indicate that FBR v-fos transactivation depends upon its cotranslational myristylation and maps to a negative regulatory region which binds C/EBP alpha.

Adipocytes↗
PubMed1994

Preservation of high regional blood flow at epicardial rim after coronary occlusion in dogs.

A thin myocardial layer adjacent to the epicardium (epicardial rim) often survives after transmural myocardial infarction. Regional myocardial blood flow (Qm) at this rim may be high enough to maintain myocardial viability during coronary occlusion. To test this hypothesis, we measured Qm in 12 anesthetized dogs during left anterior descending coronary artery occlusion using nonradioactive colored microspheres. Myocardium in the region supplied by the occluded artery was sliced into sections approximately 0.5 mm thick from the epicardial surface to the endocardium, and the Qm in each section was determined. During occlusion, the Qm of myocardium within 0.5 mm of the epicardial surface remained at 74.8 +/- 8.8% of the preocclusion level. Maintenance of this high Qm during occlusion was abolished when an epicardial incision approximately 1 mm deep was made around the occluded area. These findings suggest that Qm is maintained at a surprisingly high level at the epicardial rim after coronary occlusion through epicardial arterial communications, which may be sufficient to maintain myocardial viability.

Animals↗
PubMed1994

[Cell cycle arrest induced by epidermal growth factor on human squamous cell carcinoma cell lines].

Although human squamous cell carcinoma (SCC) cell lines frequently contain an elevated number of epidermal growth factor (EGF) receptor accompanied with amplification of EGF receptor/c-erbB gene, it is well known that EGF inhibits the growth of these cells in culture at doses that stimulate the growth of epidermal keratinocytes and dermal fibroblasts. To study this growth inhibitory effect of EGF on the SCC cell lines, 3H-thymidine incorporation into DNA and cell cycle distribution were analyzed. In HSC-1 and NA cells, which contain the highest number of EGF receptor among these SCC cell lines, the inhibition of 3H-thymidine incorporation was apparent 2 to 4 hours after treatment with 100 ng/ml of EGF and reached more than 95% inhibition after 24 hours. Two-color cell cycle analysis using fluorescein isothiocyanate (FITC)-conjugated anti-Bromodeoxyuridine (BrdU) antibody and propidium iodide revealed that this inhibitory effect was due to cell cycle arrest not only in G1 but also in G2 phase. This effect was well correlated to the sensitivity to the growth inhibitory effect of EGF among the 4 SCC cell lines. These observations suggest that the SCC cells contain altered machineries which regulate the normal cell growth in both G1 and G2 phases, and the EGF affects these machineries via overexpressed its receptor.

Carcinoma, Squamous Cell↗
PubMed1992

Inhibitory effect of myristylation on transrepression by FBR (Gag-Fos) protein.

The myristylated v-fos product, FBR murine sarcoma virus (Gag-Fos) protein, exhibits a lower level of transrepression of the serum response element (SRE) than does c-fos protein (Fos). Mutation of the N-terminal myristylation site in FBR protein restored SRE transrepression. Replacement of N-terminal viral Gag sequences with the Fos N terminus also restored this activity, providing additional evidence that myristylation inhibits transrepression by FBR protein. However, the myristylated Gag domain did not inhibit SRE transrepression when fused to Fos, indicating that myristylation of a fos protein is not by itself sufficient to prevent SRE transrepression and that C-terminal mutation is necessary to inhibit transrepression by N myristylation. Comparison of transfection results with Fos C-terminal deletion mutants and the Fos/FBR chimeric mutant revealed that the FBR C terminus retained the potential for transrepression despite deletion of the normal Fos C terminus, whereas similar Fos deletion mutants did not. These results indicate that both N- and C-terminal mutations are required to inhibit transrepression by FBR protein and that multiple structural mutations accompanied by posttranslational protein modification alter gene regulation by FBR protein.

3T3 Cells↗
PubMed1992

Residual critical coronary stenosis during myocardial reperfusion is deleterious to myocardial salvage in dogs.

Hyperemia, which occurs immediately after coronary reperfusion, injures the myocardium. Mild coronary stenosis may mitigate this hyperemia and thus may augment myocardial salvage. To test this hypothesis, left anterior descending coronary arteries of dogs were occluded for 3 h. Then, reperfusion was permitted without residual stenosis (group A, n = 17) or with 75% stenosis (group B, n = 10). Regional myocardial blood flow (RMBF) was determined using colored microspheres. Dogs were sacrificed 1 week later to measure myocardial creatine kinase activity (CK) and for staining with triphenyl tetrazolium chloride (TTC). The RMBF measured 5 min after reperfusion increased significantly (inner layer, 171 +/- 16; outer layer, 165 +/- 11% of control) in group A. This hyperemia disappeared in group B (inner, 106 +/- 8; outer, 117 +/- 10% of control). However, the myocardial CK was more preserved (group A: inner, 31 +/- 4; outer, 44 +/- 4%; and group B: inner, 21 +/- 6; outer, 29 +/- 5%), and the infarct size was smaller in group A than in group B (group A: inner, 44 +/- 6; outer, 33 +/- 5; and group B: inner, 53 +/- 10; outer, 58 +/- 7% of the area at risk). We concluded that a residual stenosis of 75% at reperfusion abolishes the hyperemia but does not improve myocardial salvage.

Animals↗