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Biomedical subjects

J Z Feng

Publications and source records attributed to J Z Feng.

At least 19 recordsLinked to original sources
PubMed2001

The Mediterranean score of dietary habits in Chinese populations in four different geographical areas.

OBJECTIVE: To compare the dietary intake of Chinese people living in Pan Yu, Hong Kong, San Francisco and Sydney with respect to cardiovascular health, using the Mediterranean diet score, examining the effects of age, gender, urbanization and acculturation on the diet score. SUBJECTS: A total of 500 men and 510 women in Hong Kong were recruited as a territory-wide stratified random sample. Subjects were recruited in response to local advertisements for the other three sites: Pan Yu, 58 men, 95 women; San Francisco, 166 men, 192 women; Sydney, 95 men, 73 women. METHOD: Food-frequency questionnaire over a 7 week period. A high/healthy score was taken as > or =4 for men and >3 for women, representing a dietary pattern beneficial for cardiovascular health. RESULTS: In Hong Kong, more women in the middle age group (35-54) had a high score than other age groups, and overall more women had high scores than men. In comparing the four geographical regions, Pan Yu had the highest number of subjects with high score, and Hong Kong had the lowest. With the exception of the younger population and men in Hong Kong, the percentage of the population with a high score in all sites is greater than among elderly Greeks consuming a more traditional heart-healthy Mediterranean diet. CONCLUSION: Considerable variations in Chinese dietary patterns exist with respect to age, gender and geographic location. Overall, the Chinese diet is comparable to the Mediterranean diet and may be expected to have similar health benefits that have been documented for the traditional Mediterranean diet.

Adult↗
PubMed2000

Changes in lipid peroxidation, the redox system and ATPase activities in plasma membranes of rice seedling roots caused by lanthanum chloride.

Highly purified plasma membranes were isolated by aqueous two-phase partitioning from rice (Oryza sativa) seedling roots. The effects of lanthanum chloride (LaCl3) on the activities of lipid peroxidation, the redox system and H+-ATPase, Ca2+-ATPase of plasma membranes were studied. The lipid peroxidation of plasma membranes could be depressed by certain low concentrations of LaCl3 and enhanced by high concentrations of LaCl3, while the lipid peroxidation was also dependent on the plasma membrane protein and incubation time. The relative activity of O2 uptake of plasma membranes was inhibited by all tested LaCl3 concentrations. In contrast, the reduction rate of Fe(CN)6(3-) by plasma membranes was stimulated below 40 microM of LaCl3, but was reduced above 60 microM of LaCl3. The relative activities of both H+-ATPase and Ca2+-ATPase increased constantly from control to LaCl3 of concentration 60 microM where the activities of both enzymes were the maximum. but decreased remarkably at 80 microM LaCl3 concentrations various LaCl3 were added to culture solutions. In the other measurement case in which various LaCl3 concentrations were added directly to reaction medium and the plasma membrane vesicles only came from the control cultured rice seedling roots, the response of H+-ATPase activity to La3+ was similar to the response in culture solution. However, the La3+ concentration was only 20 microM when the activity of H+-ATPase was the maximum. In contrast to the case of LaCl3 addition to culture solution, Ca2+-ATPase activity was inhibited by all concentrations of La3+ which were added directly to the reaction medium. The above results revealed that REEs inhibited electron transfer from NADH to oxygen in plant plasma membranes, depressed the production of active oxygen radicals, and reduced the formation of lipid peroxides through plasma membrane lipid peroxidation. REEs ions also enhanced the H+ extrusion by both standard redox system and H+-ATPase in plasma membranes at certain concentrations. A possible role for the plant cell wall in REEs effects on plasma membranes was also suggested.

Calcium-Transporting ATPases↗
PubMed1999

Westernization of Chinese adults and increased subclinical atherosclerosis.

Cardiovascular event rates are much lower in China compared with developed countries. "Westernization" of diet and lifestyle in the Chinese, however, may lead to an increased prevalence of atherosclerosis-related diseases. Because carotid intima-media thickness (IMT) is a marker of subclinical atherosclerosis, we examined IMT and vascular risk profile in community-based groups of rural Chinese, Westernized urban Chinese, and urban whites. Mean IMT of the common carotid artery was measured in 348 healthy adults, aged 42+/-13 years (range 21 to 71 years); 116 subjects from rural China, 116 urban Chinese subjects living in Hong Kong or in Australia, and 116 urban Caucasians living in Australia. These 3 groups were matched for age, sex, and cigarette smoke exposure. Urban Chinese subjects had slightly better risk factor profile (higher HDL-cholesterol and lower blood pressure) compared with rural Chinese subjects. Despite this, however, the mean IMT was lowest in rural Chinese (0.50+/-0.10 mm), intermediate in urban Chinese (0.56+/-0.12 mm), and highest in urban whites (0.64+/-0.13 mm) (P<0.001 for comparisons between all groups). These differences in IMT were not altered after adjustment for the major traditional cardiovascular risk factors (serum lipids, smoking, and blood pressure or for body mass index). The influence of vascular risk factors on atherosclerosis between urban versus rural Chinese subjects was studied by multivariate regression models and by comparing the steepness of regression slopes between risk factors and IMT in the subject groups. The effects of smoking, HDL-cholesterol, and triglycerides on IMT were significantly greater in the urban compared with the rural Chinese (P<0.01). These data suggest that Westernization of Chinese subjects is associated with greater susceptibility to the pro-atherogenic effects of traditional vascular risk factors, such as lipids and smoking, and with evidence of increased IMT as a marker of subclinical atherosclerosis.

Adult↗
PubMed1997

Chinese adults are less susceptible than whites to age-related endothelial dysfunction.

OBJECTIVES: We sought to assess the effects of aging on the endothelial physiology of a group of Chinese adults. BACKGROUND: Several studies have documented an association between aging and progressive arterial endothelial dysfunction in white subjects. We hypothesized that age-related endothelial dysfunction, an important event in atherosclerosis, might be less marked in southern Chinese subjects, in whom the prevalence of coronary heart disease is only approximately 20% of that in industrialized countries. METHODS: We studied endothelial function in 76 healthy adults aged 16 to 70 years: 38 Chinese from a village of 3,000 people in southern China and 38 white subjects from Sydney, Australia. In each ethnic group, there were 19 younger persons (16 to 40 years) and 19 older adults (55 to 70 years). None had evidence of diabetes, hypertension or clinical vascular disease or had ever been regular cigarette smokers. With the use of high resolution external vascular ultrasound, brachial artery diameter was measured at rest, after flow increase (causing endothelium-dependent dilation) and after sublingual nitroglycerin (an endothelium-independent dilator). RESULTS: Endothelium-dependent dilation was similar in young Chinese (mean +/- SD 8.3 +/- 2.5%), young whites (7.9 +/- 2.0%) and older Chinese (6.8 +/- 2.9%), but it was significantly impaired in older whites (1.8 +/- 2.5%, p < 0.001 by analysis of variance). On multivariate analysis, older age was associated with impaired endothelium-dependent dilation (p < 0.001) (independent of the effects of serum cholesterol, gender and vessel size) in the white but not in the Chinese subjects (p = 0.83). Nitroglycerin-induced dilation was not significantly different with aging in either ethnic group. CONCLUSIONS: Endothelium-dependent dilation is similar in the arteries of healthy young Chinese and white adults. With older age, however, Chinese subjects are less susceptible to impaired endothelial function.

Adolescent↗
PubMed1994

Left ventricular wall motion abnormalities in chronic mitral and aortic valvular disease.

Left ventricular wall motion was analyzed from the contrast ventriculograms of 42 patients with mitral and aortic valvular diseases by the computer-aided 100-chords centerline method. The results showed that ventricular wall motion was decreased in the anterobasal and mitral valve regions in patients with mitral aortic valvular diseases. In 15 patients, there were also other local ventricular wall motion abnormalities, which were located in the anteroapical and posterobasal regions. Almost all of the patients with ejection fraction(EF) less than 0.5 had diffuse or localized hypokinesis. Ventricular wall motion in patients who died from cardiac causes early after receiving valvular replacement was lower than that of survivors. Using Fisher's judgement method, a formula could be established to predict the early prognosis of patients with chronic valvular diseases after valve replacement.

Adolescent↗
PubMed1993

[Application of central-line-chord method to study left ventricular wall motion in left ventriculogram].

The left ventricular wall motion in left ventriculogram of 71 patients with coronary artery disease was analysed in our laboratory with central-line-chord method. 55 of 71 patients had ventricular wall motion abnormalities (77.46%). The regional wall motion abnormality (RWMA) often occurred in the areas of ventricles with poor blood supply from the stenosed coronary artery (CCA). When both LCA and RCA had stenosis, abnormal area would show in chords 10 to 28 or chords 40 to 80, when LAD stenosed, chords 10 to 30 or chords 52 to 720, and when CFX stenosed, then chords 64 to 80 were involved. The results also suggest that RWMA would appear when EF was still within normal limits. Thus, RWMA provides earlier prediction of abnormal left ventricular function than LVEF.

Adult↗
PubMed1990

Efficacy of isosorbide-5-mononitrate on painful and silent myocardial ischemia after myocardial infarction.

The anti-ischemic efficacy of isosorbide-5-mononitrate, 20 mg 3 times daily, on silent myocardial ischemia after myocardial infarction was studied in 28 Chinese patients with use of 48 hours of ambulatory electrocardiographic monitoring in a randomized, crossover, single-blind, placebo-controlled study. Isosorbide mononitrate reduced both painful and painless episodes of ischemia compared with placebo. The number of total ischemic episodes was reduced 88%, duration of ischemia 94%, time-ischemia integral 95%, and total maximal ST-segment depression 86% (p less than 0.01). The drug did not alter the heart rate and blood pressure, and had no evident adverse effect. Thus, isosorbide mononitrate is effective and well tolerated in postinfarction patients with silent ischemia.

Adult↗
PubMed1989

[A preliminary report on silent myocardial ischemia detected using ambulatory electrocardiogram monitoring].

572 cases have been examined with ambulatory electrocardiogram monitoring (AEM). They are divided clinically into three groups, (1) cases after myocardial infarction (2) cases with angina (3) cases without coronary artery disease (CAD). The incidences of silent myocardial ischemia (SMI) in the three groups were 80%, 24% and 3% respectively. The ratios of silent myocardial ischemia to symptomatic myocardial ischemia in groups (1) and (2) were 88.8% and 70.4%. It is shown that silent myocardial ischemia is very frequent in CAD. The article also reviewed and discussed the criteria for diagnosis of SMI, the mechanism of its presence, and its relation to degree of ST segment depression and daily activities.

Adult↗
PubMed1989

[24-hour ambulatory blood pressure monitoring in normal and hypertensive subjects].

24-hour ambulatory blood pressures (BP) of 172 normal subjects and 167 hypertensive patients recorded by automatic ambulatory monitoring device (A method) and standard mercury sphygmomanometer (B method) were studied. The results show: (1) 66% of normal subjects and 78% hypertensive patients have an evident circadian rhythm BP during 24-hours, BP readings during sleep and noon time are lower. (2) There is no significant difference between times at work and at home readings (P greater than 0.05), but the mean BP during sleeping time is the lowest (P less than 0.01). (3) The correlative coefficient of 24-hour average BP and casual clinic BP is low (r = 0.38-0.74). (4) The validity and accuracy of ambulatory BP monitoring by A and B methods were compared.

Adult↗
PubMed1985

Postnatal development of the phase-locked response to low frequency tones of auditory nerve fibers in the cat.

The maturation of the auditory nerve's ability to encode temporal information in an acoustic signal was studied in young kittens, 7 to 23 days old, and in adult cats by measuring the degree to which auditory nerve fiber responses are synchronized (phase locked) to low frequency tones. The major findings include the following. In 7- to 10-day-old kittens thresholds are high (around 100 dB), and secure phase locking is observed only at frequencies below about 600 Hz. The upper frequency limit for phase locking in the adult, around 4 kHz, is reached gradually toward the end of the third postnatal week, a time when thresholds also reach their adult levels. The time course of development of the phase-locked response is similar for fibers with different characteristic frequencies (CFs). At all ages studied, the maximal phase synchrony at any given low frequency is generally obtained at stimulus intensities less than 20 dB above the rate threshold and some 10 to 30 dB below the saturation firing level of the fiber. Time delays, estimated from phase-versus-frequency plots, were similar across ages, although they tended to be longer and more variable at lower CFs during the first 2 postnatal weeks. Comparing the phase-locked response of auditory nerve fibers with that of the anteroventral cochlear nucleus neurons from a previous study suggested that the upper frequency limit for phase synchrony was reached later in the nucleus than in the nerve.

Acoustic Stimulation↗
PubMed1983

Geometry and orientation of neuronal processes in cat primary auditory cortex (AI) related to characteristic-frequency maps.

Microelectrode mapping and horseradish peroxidase oxidase histochemistry were combined to study the relationship between the characteristic-frequency representation and the intrinsic connectivity of the primary auditory cortex in the cat. Small extracellular iontophoretic injections of horseradish peroxidase within the characteristic-frequency map resulted in labeling of neuronal processes that, in the tangential plane, radiated out asymmetrically from the injection site over distances of several millimeters. The heaviest concentration of labeled fibers was along an axis parallel with the orientation of the isofrequency line within which the injection had been made. Thus, primary field neurons that have the same or a similar characteristic frequency have the potential of being preferentially interconnected.

Animals↗