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Biomedical subjects

K Masaki

Publications and source records attributed to K Masaki.

At least 55 records · Page 3Linked to original sources
PubMed1998

[Clinical application of three-dimensional ultrasound imaging as intraoperative navigation for liver surgery].

Intraoperative hepatic ultrasonography provides a great deal of information about tumor location and vascular anatomy in the liver, and is an indispensable procedure for hepatic resection. However, an accurate three-dimensional understanding of ultrasound (US) images depends on the operator's skill and experience, as the original display is two dimensional. We developed a new three-dimensional US (3D-US) image processing method by application of the intensity projection method to US. The minimum and maximum intensity projection can display the arrangement of blood vessels (hepatic veins and portal veins) and hyperechoic regions, respectively. The intensity projection from several points of view can reconstruct 3D imaging by cine-display. Moving a probe manually, images are taken and processed on a real-time basis (in about 10 seconds). 3D-US was used in 24 patients undergoing hepatic resection, and allowed easy visualization of the tumors and vascular anatomy. It is considered to be an efficient and safe navigation system in liver surgery.

Aged↗
PubMed1997

Diagnosis of chronic liver disease from liver scintiscans by artificial neural networks.

Artificial neural networks were used in the diagnosis of chronic liver disease based on liver scintiscanning. One hundred and thirty-seven patients with chronic liver disease (12 with chronic persistent hepatitis, 39 with chronic aggressive hepatitis, and 86 with cirrhosis) and 25 healthy controls were studied. Sixty-five subjects (10 healthy controls, 20 patients with chronic hepatitis, and 35 patients with cirrhosis of the liver) were used in the establishment of a neural network. Liver scintiscans were taken starting 20 min after the intravenous injection of 111 MBq of Tc-99m-phytate. The neural network was used to evaluate five items judged from information on liver scintiscans: the ratio of the sizes of the left and right lobes, splenomegaly, radioactivity in the bone marrow, deformity of the liver and distribution of radioactivity in the liver. The neural network was designed to distinguish between three liver conditions (healthy liver, chronic hepatitis and cirrhosis) on the basis of these five items. The diagnostic accuracy with the neural network was 86% for patients with chronic hepatitis and 93% for patients with cirrhosis. With conventional scoring, the accuracy was 77% for patients with chronic hepatitis and 87% for patients with cirrhosis. Our findings suggest that artificial neural networks may be useful for the diagnosis of chronic liver diseases from liver scintiscans.

Case-Control Studies↗
PubMed1997

Immunohistochemical study of endothelin-1 in preeclamptic nephropathy.

Whether the serum levels of endothelin, a vasoconstrictive peptide produced in the endothelial cell, increase in preeclamptic patients is still controversial. We performed immunohistochemical studies to observe the changes in endothelin-1 (ET-1) in preeclamptic kidney tissues. The monoclonal anti-human ET-1 antibody (Yamasa, Japan) and anti-von Willebrand factor (vWF, Dako, Denmark), a marker of endothelial cells, were used for the studies by the strepto-avidin-biotin peroxidase method (ABC-POD Kit, Wako, Japan). Twenty-nine patients and 12 normal controls were divided into four groups. The preeclamptic group included 14 patients diagnosed with preeclampsia by clinical symptoms of hypertension, proteinuria, and edema occurring in late pregnancy and as having preeclamptic nephropathy. They underwent renal biopsy 16.7 +/- 1.0 (mean +/- SEM) days after delivery. The nephrotic group comprised 10 normotensive nonpregnant patients with nephrotic-range proteinuria examined through biopsy before treatment (six cases of minimal change, two of focal segmental glomerulosclerosis, one of membranous nephropathy, and one of IgA nephropathy). The pregnant women with preexisting glomerular disease group included five pregnant women with normal renal function who were normotensive and had no increase in the amount of proteinuria throughout pregnancy. They underwent renal biopsy 10.8 +/- 2.9 days after delivery (two cases of membranous nephropathy, one of focal segmental glomerulosclerosis, one of thin basement membrane disease, and one of non-IgA mesangioproliferative glomerulonephritis). The normal kidney group comprised 12 healthy tissue samples taken from nephrectomized kidneys (five cases of renal cell carcinoma, one case of lipofibrosarcoma, and six cases of kidney transplant donors). In these four groups, ET-1 and vWF showed equally positive staining in small arteries. VWF also showed positive staining in arterioles and peritubular capillaries in all groups. Although the glomeruli showed positive staining with ET-1 along the capillary walls in the normal group and the nonpregnant nephrotic group, they showed very weak or negative results in the preeclamptic group. Moreover, gravida with underlying glomerular disease without superimposed preeclampsia also showed negative findings of ET-1 in the glomeruli. The glomeruli in the four groups showed positive findings, with vWF readings the same as in the controls. These results indicate that the production of ET-1 in the glomerular endothelial cells decreases in cases of both preeclampsia and normal pregnancy, and the condition may be caused by pregnancy itself.

Adult↗
PubMed1997

Transient liver accumulation of Tc-99m phytate in hepatocellular carcinoma after percutaneous ethanol injection.

PURPOSE: We report that colloid liver scanning gave early evidence of the return to normal of Kupffer cell functions after ethanol injections into the liver. PATIENT AND METHODS: A 71-year-old man with hepatocellular carcinoma received percutaneous ethanol injections twice of 15 mL of ethanol, 1 week apart. RESULTS: Abdominal CT after the second injection showed an irregularly shaped low-density area in the left side of the tumor, extending outside the tumor. Liver imaging with To-99m phytate 10 days later showed increased activity at the corresponding site. Thirty days after the second injection, liver imaging did not show high activity. CONCLUSIONS: Ethanol that leaked into the normal part of the liver probably temporarily activated Kupffer cell function.

Aged↗
PubMed1997

Nonconvulsive status epilepticus during antidepressant treatment.

We report 3 patients who experienced nonconvulsive status epilepticus following generalized convulsions during antidepressant treatment. All showed prolonged confusion with some psychiatric symptoms, and their electroencephalograms (EEGs) showed either bilateral synchronous multiple spike wave discharges or continuous diffuse sharp and slow waves. When diazepam was administered intravenously to 1 patient, the clinical symptoms and EEG improved markedly.

Adult↗
PubMed1996

Fish intake may limit the increase in risk of coronary heart disease morbidity and mortality among heavy smokers. The Honolulu Heart Program.

BACKGROUND: Research has shown that fish consumption limits damage to the lungs caused by cigarette smoking, possibly by the effects of fish on arachidonic acid metabolism. We explored this fish-smoking interaction using coronary heart disease (CHD) incidence and mortality as the outcome. METHODS AND RESULTS: The Honolulu Heart Program began in 1965 to follow a cohort of 8006 Japanese-American men aged 45 to 65 years who lived on Oahu, Hawaii, in 1965. Fish intake was measured at baseline by use of a questionnaire. For current smokers at baseline (n = 3310) who reported low fish intake (< 2 times/wk), age-adjusted 23-year CHD mortality rates increased with the number of cigarettes smoked per day (2.3, 3.1, and 6.9 per 1000 person-years for men who smoked < 20, 20 to 30, and > 30 cigarettes/d, respectively; trend test P < .0001). Among current smokers whose fish intake was high (> or = 2 times/wk), CHD mortality rates showed no relation with cigarettes/d (3.7, 3.2, and 3.7 per 1000 person-years for the corresponding levels of smoking). A Cox proportional hazards model based on current smokers, adjusted for age, years in Japan, calories/d, alcohol intake, physical activity index, years smoked, hypertension, and serum cholesterol, blood glucose, and uric acid levels, was examined. In the high-smoking group, the risk factor-adjusted relative risk (RR) for CHD mortality among those with high fish intake was half that of those with low fish consumption (RR = 0.5, 95% confidence interval = 0.28 to 0.91). A Cox model that adjusted for similar risk factors confirmed a significant interaction of cigarettes/d and fish intake (P < .01) on CHD mortality. Analyses for CHD incidence showed similar results. CONCLUSIONS: Despite the findings of this investigation, the public health message for smokers continues to be to stop smoking. However, an interaction between fish intake and cigarette smoking is biologically plausible and deserves further investigation. The study of this phenomenon may shed light on the biological mechanisms by which cigarette smoking leads to CHD.

Aged↗
PubMed1996

Effect of YM934, a novel potassium-channel opener, in various experimental asthma models in guinea-pigs.

YM934 is a novel synthetic potassium-channel opener. We have investigated its anti-asthma effect after intravenous (i.v.) and oral (p.o.) administration in various experimental asthma models in the guinea-pig, and compared the results with those for lemakalim, theophylline and salbutamol. In an ovalbumin-active sensitization anaphylaxis asthma model, YM934, lemakalim, theophylline and salbutamol dose-dependently prolonged the time before the occurrence of asthma attacks and reduced the mortality rate. The respective ED50 values (dose required to prolong by 50% the time before the occurrence of attacks) of the anti-asthma effects of YM934, lemakalim, theophylline and salbutamol were 6, 340, 30000, and 45 micrograms kg-1 (i.v.); the efficacy ratios were YM934 (1) > salbutamol (1/9) > lemakalim (1/57) > > theophylline (1/5000). YM934 also prolonged the period before the occurrence of attacks in the anti-BSA (bovine serum albumin) serum-passive sensitization anaphylaxis, histamine-induced and methacho-line-induced asthma models, with respective ED50 values for these models of 15, 22 and 20 micrograms kg-1 (i.v.). Among these models a reduction in mortality rate was seen in the histamine- and methacholine-induced asthma models. After oral administration, YM934 showed an anti-asthma effect in the ovalbumin-active sensitization anaphylaxis, histamine-induced and methacholine-induced asthma models, with respective ED50 values of 38, 44 and 193 micrograms kg-1. YM934 was 5-6 times more potent than salbutamol. These results indicate that YM934 has potent anti-asthma activity, and that this activity is mainly attributable to bronchodilation, most likely mediated through its potassium-channel opening activity.

Administration, Oral↗
PubMed1996

Peripheral artery disease and cardiovascular risk factors in the elderly. The Honolulu Heart Program.

Peripheral vascular disease as measured by the ankle/brachial blood pressure index (ABI) is associated with increased risk of mortality and morbidity. Few sources of data on the relationship of risk factors to ABI are available for the elderly, especially those > 80 years of age, and minority populations. ABI measurements from the Honolulu Heart Program's fourth reexamination of 3450 ambulatory, elderly Japanese American men indicate that the prevalence of an abnormal ABI, defined as a ratio of < 0.9, was 13.6%, increasing from 8.0% in those 71 to 74 years of age to 27.4% in those 85 to 93 years. Associations that were U or J shaped were present for a number or risk factors (higher rates of abnormality [ABI < 0.9] in those in the lowest and highest risk factor quintiles) in a cross-sectional analysis. Risk factors measured at baseline were also predictive of an abnormal ABI 25 years later, even after adjustment for multiple risk factors. The odds ratio (OR) for an ABI < 0.9 at the 80th percentile of cholesterol compared with that at the 20th percentile was 1.4; the OR for 1-hour postload glucose was 1.3, and for alcohol intake 1.2. The OR associated with hypertension was 1.8 and that for smoking, 2.9 (P < .05 for all ORs). These findings are consistent with ABI being a marker for generalized atherosclerotic disease in old and very old Japanese American men.

Aged↗
PubMed1996

Fulminant hepatic failure monitored by technetium-99m-DTPA-galactosyl-human serum albumin scintigraphy.

We describe a 43-yr-old woman with fulminant hepatic failure whose progress was monitored scintigraphically using 99m-Tc-galactosyl-human serum albumin (99mTc-GSA). On admission, the liver was atrophic and the heart was delineated distinctly by scintigraphy with 99m-Tc-GSA. The receptor index, calculated by dividing the radioactivity of the liver region of interest by the radioactivity of the liver plus heart regions of interest at 15 min post-tracer injection, was very low. As the patient's condition improved, the right lobe of the liver enlarged while the left lobe became atrophic; after 4 mo, the left lobe almost completely disappeared. Delineation of the heart gradually became less distinct, and the receptor index slowly increased. Hepatic receptor imaging with 99m-Tc-GSA can define both the hepatic functional reserve and morphological changes of the liver, so it is useful for the diagnosis and follow-up study of fulminant hepatic failure.

Adult↗
PubMed1995

The association between midlife blood pressure levels and late-life cognitive function. The Honolulu-Asia Aging Study.

OBJECTIVE: To assess the long-term relationship of midlife blood pressure levels to late-life cognitive function. DESIGN: The 4678 surviving cohort members of the prospective Honolulu Heart Program (baseline, 1965-1968) were examined a fourth time in 1991 through 1993 and given a cognitive test. PARTICIPANTS: The subjects were 3735 Japanese-American men living in Hawaii in the community or in institutions, with an average age of 78 years at the fourth examination. MAIN OUTCOME MEASURES: Cognitive function, measured by the 100-point Cognitive Abilities Screening Instrument (CASI), was categorized into good (reference: a CASI score of 92 to 100), intermediate (< 92 to 82), and poor (< 82). Midlife systolic blood pressure (SBP) and diastolic blood pressure (DBP) values were measured in 1965, 1968, and 1971. A respondent was classified into the following categories if two of three measurements fell into the following groups: for SBP, < 110, 110 to 139, 140 to 159, and > or = 160 mm Hg; and for DBP, < 80, 80 to 89, 90 to 94, and > or = 95 mm Hg. RESULTS: When we controlled for age and education, the risk for intermediate and poor cognitive function increased progressively with increasing level of midlife SBP category (P for trend < .03 and < .001, respectively). For every 10-mm Hg increase in SBP there was an increase in risk for intermediate cognitive function of 7% (95% confidence interval [CI], 3% to 11%) and for poor cognitive function of 9% (95% CI, 3% to 16%). Adjustment for prevalent stroke, coronary heart disease, and subclinical atherosclerosis reduced the strength of the relationship between midlife SBP and poor cognitive function to 5% (95% CI, 0% to 12%). The level of cognitive function was not associated with midlife DBP. CONCLUSIONS: Midlife SBP is a significant predictor of reduced cognitive function in later life. Early control of SBP levels may reduce the risk for cognitive impairment in old age.

Aged↗
PubMed1995

Effect of barnidipine on blood flow to major organs and renal function in anaesthetized dogs and spontaneously hypertensive rats.

1. The effects of barnidipine on blood flow to major organs and on renal function were investigated in anaesthetized dogs and conscious spontaneously hypertensive rats (SHR), and the results were compared with those for nicardipine, nitrendipine, nisoldipine, manidipine and amlodipine. 2. In anaesthetized dogs, barnidipine (0.3-3 mu g/kg i.v.) dose-dependently decreased blood pressure and increased or preserved blood flow in the vertebral, coronary, femoral and renal arteries. The effect of barnidipine on blood flow was the most potent of the compounds tested. In conscious SHR, barnidipine (0.3-3 mg/kg p.o.) produced a dose-dependent antihypertensive effect and decreased renal vascular resistance. Barnidipine also dose-dependently increased urinary volume. The antihypertensive and diuretic effects of barnidipine were the most potent of the drugs tested. 3. In summary, barnidipine was shown to preserve or increase blood flow to major organs and to produce diuretic activity with a decrease in blood pressure. These findings suggest that barnidipine maintains or promotes renal function at antihypertensive doses.

Anesthesia↗
PubMed1994

Pulmonary function decline and 17-year total mortality: the Honolulu Heart Program.

The Honolulu Heart Program continues to follow a cohort of Japanese-American men initially aged 45-68 years, of whom 4,000 had three acceptable measurements of forced expiratory volume in 1 second (FEV1) between 1965 and 1974 and were free of cardiovascular disease and cancer. The 6-year rate of change (slope) in FEV1 was calculated using a within-person linear regression method. Men were divided into tertiles based on the rate of change in FEV1. During 17 subsequent years of follow-up, 796 deaths occurred. The tertile with the greatest rate of decline in FEV1 (mean, -61 ml/year) had the highest age-adjusted total mortality rate (17.3/1,000 person-years), followed by rates of 13.2 for the middle tertile (mean, -25 ml/year) and 11.0 for men with the smallest change in FEV1 (mean, +9 ml/year) (test for trend, p < 0.0001). Using the Cox model, comparing the tertile with the smallest change in FEV1 as a reference group with the tertile with the greatest decline in FEV1, and after adjusting for age, hypertension, smoking, body mass index, alcohol intake, diabetes mellitus, and cholesterol, the authors found the relative risk (RR) for total mortality to be 1.48 (95% confidence interval (CI) 1.24-1.77). After stratification by smoking status, this association remained significant for past smokers (RR = 1.79, 95% CI 1.31-2.14), as well as for the low, < or = 42 (RR = 1.46, 95% CI 1.05-2.03), and high, > 42 (RR = 1.56, 95% CI 1.20-2.02), pack-year groups. An increased risk was also present for current smokers (RR = 1.29), but it was of borderline significance (p = 0.08). No association was found among never smokers. These data suggest that the rate of decline in FEV1 is a predictor of total mortality among smokers.

Aged↗
PubMed1994

To what extent do cardiovascular risk factor values measured in elderly men represent their midlife values measured 25 years earlier? A preliminary report and commentary from the Honolulu Heart Program.

In a Honolulu Heart Program cohort of 1,604 elderly men aged 70-90 years who were sampled from the most recent follow-up examination (1991-1992), current risk factor values were compared with those obtained 25 years earlier when the same men were between ages 45-64 and free of clinically diagnosed cardiovascular disease. Cardiovascular disease risk factors studied included systolic blood pressure, diastolic blood pressure, serum cholesterol, cigarette smoking, body mass index, and alcohol intake. For systolic pressure, 65% of the men had moved into a different quartile by old age, with 25% changing by more than one quartile. For diastolic pressure, 68% had moved into another quartile, with 28% moving more than one quartile, and for body mass index, 53% had moved into another quartile, with 14% moving more than a quartile. Less than 1% started to smoke, while 27% were reclassified from smokers to nonsmokers. Only 4% started to drink alcohol, while 30% were reclassified from drinkers to nondrinkers. When the men were stratified into cardiovascular disease, noncardiovascular disease, and healthy follow-up groups, modest deviations from the overall pattern were observed, with morbidity groups showing a greater tendency to reduction in risk factor levels. The results show that there is a substantial redistribution of major cardiovascular disease risk factor values between midlife and old age. Since midlife values are more likely to represent lifelong exposure values that, in turn, make the main contribution to the development of atherosclerosis, investigators and clinicians may need to be cautious in using risk factor values measured late in life as the only means of assessing risk for subsequent disease.

Aged↗
PubMed1994

Osteopenia in primary biliary cirrhosis and cirrhosis of the liver in women, evaluated by dual-energy X-ray absorptiometry.

To study bone involvement in primary biliary cirrhosis (PBC), we used dual-energy X-ray absorptiometry to measure bone mineral density (BMD) in Japanese women with PBC and with cirrhosis of the liver. In both groups, in each decade up to 60 years of age, the mean BMD of the lumbar spine was not significantly different from that in healthy Japanese women; however, in patients aged 60 years or more, the level was significantly lower both in the patients with PBC (P < 0.001) and in those with cirrhosis of the liver (P < 0.01). Patients with PBC were also examined by single-photon absorptiometry. The BMD of the radius in the patients with PBC was less changed than that of the lumbar vertebrae; thus, the bone changes in PBC seem to be greater in spongy than in cortical bone.

Absorptiometry, Photon↗
PubMed1994

Angiographic follow-up after successful percutaneous coronary angioplasty for chronic total coronary occlusion: experience in 110 consecutive patients.

Percutaneous transluminal coronary angioplasty (PTCA) was performed in 110 consecutive patients (111 vessels) with chronically occluded coronary arteries and was successful in 69 patients (69 vessels). Successful initial PTCA was related to the extent of coronary artery disease, the morphology of the proximal surface of the occlusion site, and the clinical duration of occlusion. Repeat angiography was performed for 62 patients, with successful initial PTCA and demonstrated restenosis in 34 (55%) patients, of whom 11 had total occlusion. Repeat PTCA was performed in 30 patients and was successful in 80%. Follow-up angiography after repeat PTCA was carried out in all patients who underwent successful second PTCA, and, it demonstrated re-restenosis in 7 (29%) patients. In this study, among 111 total occlusions, 28 vessels undergoing successful initial PTCA and 17 undergoing successful repeat PTCA were free from restenosis or re-restenosis at the time of follow-up angiography.

Adult↗
PubMed1994

Physical activity and 23-year incidence of coronary heart disease morbidity and mortality among middle-aged men. The Honolulu Heart Program.

BACKGROUND: The purpose of the study was to examine the association between physical activity and 23-year incidence of coronary heart disease morbidity and mortality. This cohort study continues to follow 8006 Japanese-American men who were 45 to 68 years of age and living on Oahu, Hawaii, in 1965, for the development of coronary heart disease morbidity and mortality. METHODS AND RESULTS: The Framingham physical activity index was calculated by summing the product of average hours spent at each activity level and a weighting factor based on oxygen consumption. Study subjects were divided into tertiles of physical activity index at baseline. Relative risks and 95% confidence intervals (CI) for incidence of coronary heart disease morbidity and mortality were obtained using the Cox model. After age adjustment and using the lowest physical activity index tertile as a reference group, the relative risk for coronary heart disease incidence for the highest tertile of physical activity was 0.83 (CI, 0.70 to 0.99). After adjusting for age, hypertension, smoking, alcohol intake, diabetes, cholesterol, and body mass index, the relative risk was 0.95 and CI included 1 (CI, 0.80 to 1.14). For coronary heart disease mortality, the age-adjusted relative risk was 0.74 (CI, 0.56 to 0.97) and 0.85 (CI, 0.65 to 1.13) after risk factor adjustment. CONCLUSIONS: The results suggest that the impact of physical activity index on coronary heart disease is mediated through its effects on hypertension, diabetes, cholesterol, and body mass index. These findings support the hypothesis that physical activity is inversely associated with coronary heart disease morbidity and mortality and suggest that physical activity interventions in middle-aged men, by improving cardiovascular risk factor levels, may have significant public health implications in the prevention of coronary heart disease.

Aged↗
PubMed1994

Sex-related differences in the expression of cytochrome P450 in hamsters: cDNA cloning and examination of the expression of three distinct CYP2C cDNAs.

Sex-related differences in the expression of cytochrome P450 isozymes in hamsters were investigated. Three distinct cDNA clones (assigned as CYP2C25, CYP2C26, and CYP2C27) were isolated from liver cDNA libraries from male and female hamsters, using rat CYP2C11 cDNA as a probe. Sequence analysis revealed that these three forms were very similar to each other (> 90% identity of nucleotide sequences) and belong to the CYP2C gene subfamily. The CYP2C25, CYP2C26, and CYP2C27 cDNA clones consisted of an open reading frame encoding 490 amino acids. CYP2C25, CYP2C26, and CYP2C27 proteins expressed in Saccharomyces cerevisiae catalyzed the hydroxylation of tolbutamide and the N-demethylation of aminopyrine and benzphetamine. Only CYP2C25 showed testosterone hydroxylase (16 beta) activity. Northern blot analyses with specific oligonucleotide probes demonstrated that expression of CYP2C27 was male specific and male predominant in kidneys and livers, respectively. No sex-related difference was observed in the expression of CYP2C25 and CYP2C26. These results support our previous findings that sex-related differences in the expression of liver microsomal cytochromes P450 occur in hamsters.

Aminopyrine↗