PubMed Health⌕ Search

Biomedical subjects

C Lan

Publications and source records attributed to C Lan.

At least 19 recordsLinked to original sources
PubMed2001

Simultaneous study of metabolism and function following cardioplegic arrest: a novel method of evaluation of the transplanted heart in the rat.

BACKGROUND: Limitations of the isolated perfused rat heart model for heart preservation studies include short study time due to the lack of stability of the preparation. We aimed to develop a new experimental model based on heterotopic heart transplantation in the rat to achieve simultaneous (31)P magnetic resonance spectroscopy (MRS) and functional study of the transplanted heart during early and late blood reperfusion. METHODS: Twenty-five Lewis rats underwent heterotopic abdominal isograft heart transplantation and were randomized in two groups. Hearts were harvested after cardioplegic arrest induced with Centre de Résonance Magnétique Biologique et Médicale (CRMBM) solution and then stored at 4 degrees C for a total ischemic time of 3 hours. Graft contractility measurement and simultaneous (31)P MRS were performed after 1 hour and 24 hours of blood reperfusion, respectively, in groups I (n = 12) and II (n =13). RESULTS: Contractility improved during reperfusion. The mean rate pressure product plus or minus standard error of mean increased from 11,373 +/- 1,377 mm Hg/min in group I to 24,363 +/- 3,860 mm Hg/min in group II (P = 0.003), while mean dP/dtmax increased from 1,642 +/- 173 mm Hg/sec to 2,571 +/- 333 mm Hg/sec, respectively (p = 0.03). Simultaneously, both the phosphocreatine/adenosine triphosphate (ATP) and inorganic phosphate/ATP ratios decreased from group I to group II (p = 0.025 and p = 0.015, respectively), suggesting regeneration of the intracellular pool of ATP in group II. CONCLUSIONS: Simultaneous functional and metabolic studies of the transplanted heart are feasible in rats. Improvement in contractility during late reperfusion is contemporary with significant changes in energetic metabolism. Our model should be useful for the further improvement of heart preservation, which may result in significant clinical progress.

Adenosine Triphosphate↗
PubMed2001

Energy expenditure of wheeling and walking during prosthetic rehabilitation in a woman with bilateral transfemoral amputations.

OBJECTIVE: To compare the energy expenditure of locomotion by wheelchair with that required for prosthetic ambulation in a person with bilateral transfemoral (TF) amputations. DESIGN: Observational, single patient, descriptive. SETTING: An 80-meter long rectangular hallway in a rehabilitation unit. PATIENT: A 41-year-old woman with bilateral TF amputations that were performed 79 days before her admission to the rehabilitation unit. MAIN OUTCOME MEASURES: The oxygen uptake, oxygen cost, heart rate, speed, cadence, and stride length of walking measured during a 4-month course of prosthetic rehabilitation. Five locomotion conditions were evaluated: (1) wheelchair propulsion, (2) walking with short-leg prostheses (stubbies) and a walker, (3) long-leg prostheses and a walker, (4) long-leg prostheses without knee mechanism and axillary crutches, and (5) long-leg prostheses with right polycentric knee and left locked knee and axillary crutches. A portable and telemetric system was used to measure the metabolic parameters. An arm ergometry graded exercise test was performed at the end of rehabilitation. RESULTS: Oxygen cost (range, 466%--707% of that of wheeling) and heart rate (range, 106%--116% of that of wheeling) were higher during walking with various combinations of prostheses and walking aids. The speed of prosthetic walking was only 24% to 33% of that of wheeling. Our patient preferred using a wheelchair to prosthetic walking after discharge. CONCLUSIONS: People with bilateral TF amputations require very high cardiorespiratory endurance to fulfill the energy demand during prosthetic rehabilitation. The high energy cost of prosthetic walking will limit its application in daily activities.

Accidents, Traffic↗
PubMed2001

[Acid producing potential of a lead/zinc mine tailings at Lechang, Guangdong Province].

The acid producing potential of a Pb/Zn mine tailings at Lechang City, Guangdong Province were studied using both net acid generation (NAG) and net acid production potential (NAPP) methods. The pyritic and total sulfur contents of the tailings were 12.57% and 18.68% respectively. The NAG and NAPP values were H2SO4 220 kg.t-1 and 326 kg.t-1, and both the NAG and NAPP results indicated that the tailings had high acid forming potential. NAG was more accurate than NAPP in predicting acid forming potential of the tailings due to the uncompleted oxidization of pyritic sulfur. Analysis of samples from two profiles test indicated that the acidification major occurred on the surface (0-20 cm) of the tailings because of limited oxygen diffusion and had little effects on the tailings at lower horizons. pH values were negatively related to EC, indicated that the acid released accelerate dissolution of the solid matrix and increase in both cations and actions in solution, the extractable Pb, Zn, Cu and Cd at the acidifying tailings surface.

Cadmium↗
PubMed2000

Characterization of halotolerant rhizobia isolated from root nodules of Canavalia rosea from seaside areas.

Twelve nodule isolates from Canavalia rosea, an indigenous leguminous halophyte growing in the seaside areas of southern Taiwan, were effective symbionts for the original host and able to grow at NaCl concentrations up to 3-3.5% (w/v). The taxonomy of these isolates was investigated using a polyphasic approach, including phenotypic characteristics, banding patterns of total proteins from sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), genomic fingerprint patterns from random amplified polymorphic DNA (RAPD) analysis, pulsed-field gel electrophoresis (PFGE) analysis, amplified 16S rDNA restriction analysis (ARDRA), 16S rRNA gene sequencing, and nifH gene sequencing. Based on the SDS-PAGE, RAPD, PFGE and ARDRA results, the 12 isolates are highly diverse. The 16S rRNA and nifH gene sequences were determined for isolates with distinct ARDRA patterns and compared with other members of the rhizobial species. We propose these isolates should be classified into the genus Sinorhizobium and distinguished from the current species of this genus.

Journal Article↗
PubMed2000

Tai Chi Chuan to improve muscular strength and endurance in elderly individuals: a pilot study.

OBJECTIVE: To evaluate the training effect of a Tai Chi Chuan (TCC) program on knee extensor muscular strength and endurance in elderly individuals. DESIGN: Before-after trial. SETTING: Community setting. PARTICIPANTS: Forty-one community dwelling subjects aged 61.1 +/- 9.8 years undertook a TCC program. Nine dropped out during the study. Pretraining and posttraining measurements were obtained from 15 men and 17 women. INTERVENTION: Subjects participated in a 6-month TCC program. Each session consisted of 20 minutes of warm-up, 24 minutes of structured TCC training, and 10 minutes of cool-down exercises. MAIN OUTCOME MEASURES: Peak torque of dominant and nondominant knee extensors was tested at speeds of 60 degrees , 180 degrees , and 240 degrees/sec concentrically and eccentrically. Muscular endurance of the knee extensor was tested at the speed of 180 degrees /sec. RESULTS: In the group of men, concentric knee extensor peak torque increased by 15.1% to 20.0% and eccentric peak torque increased by 15.1% to 23.7%. The group of women also showed increases, ranging from 13.5% to 21.8% in concentric peak torque, and 18.3% to 23.8% in eccentric peak torque. In addition, the knee extensor endurance ratio increased by 9.6% to 18.8% in the men and 10.1% to 14.6% in the women. CONCLUSION: TCC training may enhance muscular strength and endurance of knee extensors in elderly individuals.

Aged↗
PubMed2000

L-arginine during long-term ischemia: effects on cardiac function, energetic metabolism and endothelial damage.

BACKGROUND: We have evaluated the addition of L-arginine, a precursor of nitric oxide, to a cardioplegic solution (named CRMBM) designed for long-term heart preservation. METHODS: Isolated isovolumic-perfused rat hearts (n = 22) were arrested with the CRMBM solution either with (Arg) or without L-arginine (2 mmol/L) (Arg group, n = 12, vs control group n = 10), submitted to 8 hours of cold storage (4 degrees C) in the solution, and then reperfused for 60 minutes at 37 degrees C. In 11 hearts, we evaluated the quality of cardiac preservation with P-31 magnetic resonance spectroscopy and the measure of function and cellular integrity. Endothelium-dependent and independent vasodilatations were measured in 11 other hearts, using 5-hydroxytryptamine and papaverine to assess endothelial and smooth muscle function. RESULTS: Adding L-arginine to the cardioplegic solution improved functional recovery during reflow, as shown by the rate pressure product (31% +/- 3% for control vs 47% +/- 3% for Arg, p = 0.003) together with higher coronary flow and diminished contracture. Purine release in coronary effluents during reperfusion was lower in the Arg group. During ischemia and reflow kinetics of intracellular pH and high-energy phosphates were similar in both groups. Coronary endothelium-dependent vasodilatation was similarly impaired in both groups, but smooth muscle was less altered with L-arginine. CONCLUSIONS: As an additive to the CRMBM cardioplegic solution, L-arginine provides a protective effect for long-term heart preservation. Our data do not show coronary endothelial protection as the prominent mechanism.

Animals↗
PubMed1999

Metabolic and functional effects of low-potassium cardioplegic solutions for long-term heart preservation.

Cardioplegic solutions used to arrest the heart during open heart surgery and cardiac transplantation are based on potassium as a cardioplegic agent in a concentration range of 15-35 mM. However, high to moderate K+ concentrations increase Ca2+ influx and impair endothelial function. We have therefore evaluated the possible advantage of a lower potassium concentration in a new cardioplegic solution (named CRMBM solution) designed for long-term heart preservation. Nine isolated perfused rat hearts were submitted to 8 h of hypothermic ischemia after cardioplegic arrest, followed by 60 min of reflow at 37 degrees C. Two cardioplegic solutions were compared: (1) the CRMBM solution with 10 mM potassium (K-10 group), and (2) the CRMBM solution with 4 mM potassium (K-4 group). The quality of heart preservation was assessed by a metabolic study using P-31 magnetic resonance spectroscopy (energy metabolism and intracellular pH) combined to a functional evaluation and a measure of cellular integrity (biochemical assays in effluents and tissues). Decreasing the potassium concentration to 4 mM improved heart preservation, as shown by a higher functional post-ischemic recovery represented by the rate pressure product and a better preservation of cellular integrity. The evolutions of intracellular pH and high energy phosphate levels during ischemia and reflow were similar in both groups.

Animals↗
PubMed1999

Optimized cardiac graft preservation: a comparative experimental study using P-31 magnetic resonance spectroscopy and biochemical analyses.

BACKGROUND: The University of Wisconsin (UW), St. Thomas (ST) and Broussais (B) solutions were compared to the CRMBM solution, that we developed for long term heart preservation. METHODS: Isolated isovolumic rat hearts were arrested with each cardioplegic solution (n = 5) to 8 hearts in each group), submitted to 12 hours of cold storage (4 degrees C) in the same solution and then reperfused for 60 minutes at 37 degrees C. Function was measured during control and reflow. High energy phosphates and intracellular pH were monitored by P-31 magnetic resonance spectroscopy. Analyses were performed by biochemical assays and HPLC in coronary effluents (CK, Pi, lactate, purines) and in freeze-clamped hearts (amino acids, nucleotides, CK, LDH) at the end of reperfusion. RESULTS: Functional recovery was significantly improved with the new cardioplegic solution (50+/-12% recovery for the rate pressure product at the end of reflow vs 8+/-3% with UW, 0% with B and with ST). This result was correlated with the best metabolic and cellular protection as assessed in particular by higher PCr levels during reflow (30+/-3% vs 10+/-3% with UW, 8+/-4% with B, and 7+/-1% with ST) as well as reduced creatine kinase leakage during reflow (110+/-15 IU/60 minute vs 270 +/- 57 IU/60 minute with UW, 323+/-36 IU/60 minute with Broussais solution and 237+/-18 IU/60 minute with ST). CONCLUSION: This new solution is more effective in prolonged myocardial protection than the three most widely used solutions.

Acid-Base Equilibrium↗
PubMed1999

The effect of Tai Chi on cardiorespiratory function in patients with coronary artery bypass surgery.

PURPOSE: This study prospectively evaluated the training effect of a 1-yr Tai Chi Chuan (TCC) program for low-risk patients with coronary artery bypass surgery (CABS) after a postoperative outpatient (phase II) cardiac rehabilitation program. METHODS: Twenty patients with mean age of 56.5+/-7.4 yr completed this study. The TCC group included nine men who practiced classical Yang TCC with an exercise intensity of 48-57% heart rate range (HRR). The control group included 11 men whom were recommended to do a home-based self-adjusted exercise program with similar intensity of phase II cardiac rehabilitation. Graded exercise tests were performed before and after 1 yr of training for all subjects. RESULTS: Mean attendance of the TCC group was 3.8+/-1.5 times weekly in contrast to 1.7+/-1.1 times for the control group. During the follow-up examination, the TCC group increased 10.3% in VO2peak (from 26.2+/-4.4 to 28.9+/-5.0 mL x kg(-1) min(-1), P<0.01) and increased 11.9% in peak work rate (from 135+/-26 W to 151+/-28 W, P<0.01). However, the control group showed slight decrease in VO2peak from 26.0+/-3.9 to 25.6+/-4.6 mL x kg(-1) x min(-1) and in peak work rate from 131+/-23 W to 128+/-32 W. At the ventilatory threshold, the TCC group also showed significant increase in VO2 and work rate (P<0.05). The control group did not significantly change in these variables. CONCLUSIONS: The study demonstrated that a 1-yr TCC program for low-risk patients with CABS could favorably enhance cardiorespiratory function.

Analysis of Variance↗
PubMed1999

Dietary fish oil promotes positive inotropy of ouabain in the rat heart.

We tested the hypothesis that a fish oil (FO) diet promotes positive inotropy of ouabain without increased toxicity. For 2 mo, two groups of adult male rats were fed 1) a regular food diet supplemented with dietary long-chain polyunsaturated fatty acid from FO or 2) a regular food diet (control). The responsiveness to ouabain was evaluated for the two groups in Langendorff-perfused hearts, by (31)P nuclear magnetic resonance spectroscopy, and on purified membrane-bound Na-K-ATPase. The maximum positive inotropy achieved with ouabain was nearly two times higher in the FO than in the control group and was not associated with significant changes in energetics. Alteration of function and energetic metabolism and inhibition of Na-K-ATPase in response to 3 x 10(-4) M ouabain were delayed in the FO group. This study demonstrates that dietary FO, by a cardiac membrane incorporation of n-3 polyunsaturated fatty acid, promotes positive inotropy of ouabain without toxicity and changes in cardiac metabolism.

Animals↗
PubMed1999

Cardiorespiratory response of heart transplantation recipients to exercise in the early postoperative period.

In this study, we evaluated the cardiorespiratory function of orthotopic heart transplantation (OHT) recipients during exercise. Seventeen male OHT recipients, ranging in age from 22 to 60 years, participated in this study 47 +/- 21 days after surgery. The control group consisted of 17 sedentary healthy men. Breath-by-breath measurement of cardiorespiratory function was obtained during the incremental exercise of leg cycling. At peak exercise, the oxygen (O2) uptake (16.5 +/- 3.3 vs 33.9 +/- 8.2 mL.kg-1.min-1), work rate (82 +/- 19 vs 169 +/- 42 watts), heart rate (HR), O2 pulse, and blood lactate level of the OHT recipients were significantly lower than the respective values of the control group. At the ventilatory threshold, the OHT group also showed a significantly lower O2 uptake (10.7 +/- 1.6 vs 18.3 +/- 5.1 mL.kg-1.min-1), work rate (39 +/- 12 vs 89 +/- 33 watts), HR, O2 pulse, ventilatory equivalent for O2, and ventilatory equivalent for carbon dioxide. The OHT recipients showed a high resting HR (97 +/- 7 beats/min) and a low peak HR (123 +/- 14 beats/min) during exercise, and their HR continued to increase for 1 to 3 minutes after cessation of exercise. Our data revealed a low level of cardiorespiratory endurance in OHT recipients during the early postoperative stage. A multidisciplinary cardiac rehabilitation program should be considered to enhance physical functional capacity and quality of life, and promote return to work.

Adult↗
PubMed1998

12-month Tai Chi training in the elderly: its effect on health fitness.

PURPOSE: The objective of this study was to evaluate the effect of Tai Chi Chuan (TCC) on health fitness in older individuals. METHODS: Thirty-eight community-dwelling persons aged 58 to 70 yr completed this study. The TCC group included 9 men and 11 women; the control group included 9 men and 9 women. The TCC group practiced TCC for 11.2+/-1.4 months, with the attendance of 4.6+/-1.3 times x wk(-1). Each session included 20 min of warm-up, 24 min of TCC practice, and 10 min of cooldown. The exercise intensity was 52-63% of the heart rate range. Cardiorespiratory function, strength, flexibility, and percent of body fat were evaluated before and at the end of this study. RESULTS: The male TCC group showed 16.1% increase in VO2max (P < 0.01), 11 degrees increase in thoracic/lumbar flexibility (P < 0.05), 18.1% increase in muscle strength of knee extensor (P < 0.01), and 15.4% increase of knee flexor (P < 0.05). The female TCC group showed 21.3% increase in VO2max (P < 0.01), 8.8 degrees increase in flexibility (P < 0.05), 20.3% increase in muscle strength of knee extensor (P < 0.05), and 15.9% increase of knee flexor (P < 0.05). The control group showed no significant change in these variables. CONCLUSIONS: The results indicate that a 12-month Tai Chi Chuan program is effective for improving health fitness of the elderly.

Aged↗
PubMed1998

Normal standards for cardiopulmonary responses to exercise using a cycle ergometer test.

The purpose of the study was to establish standards for cardiopulmonary responses to exercise in healthy Chinese subjects in Taiwan. One hundred and five sedentary healthy subjects, 55 men and 50 women aged between 20 and 75 years, were tested. They pedalled a cycle ergometer with the work rate increased by 10 W every minute until they were exhausted. Expiratory gas volume, oxygen concentration, carbon dioxide concentration, and heart rate were measured during the exercise test. Work rate (WRmax), oxygen consumption (VO2max), oxygen consumption divided by body weight (VO2max/BW), heart rate (HRmax), and ventilation (VEmax) at maximal exercise, and oxygen consumption at anaerobic threshold (VO2AT) were determined. These parameters were regressed by age (A, in year), height (H, in cm), body weight (G, in kg), and gender (S, 0 = women, and 1 = men), and the following predictive equations were obtained: 1) WRmax (W) = -1.2 A + 1.1 H + 0.7 G + 28 S - 56, R = 0.90; 2) VO2max (ml/min) = -20 A + 9.5 H + 16 G + 461 S - 237, R = 0.90; (3) VO2max/BW (ml/kg/min) = -0.31 A + 0.14 H - 0.14 G - 7.2 S + 22, R = 0.87; 4) HRmax (beat/min) = -0.81 A + 209, R = 0.61; 5) VEmax (L/min) = -0.74 A - 0.04 H + 0.93 G + 22.2 S + 42, R = 0.83; 6) VO2AT (ml/min) = -9.5 A + 3.5 H + 9.4 G + 140 S - 122, R = 0.79. Our results provide normal standards for cardiopulmonary responses to exercise during cycle ergometer testing in Taiwan.

Adult↗
PubMed1996

Cardiorespiratory function, flexibility, and body composition among geriatric Tai Chi Chuan practitioners.

OBJECTIVE: To evaluate the health-related fitness of geriatric Tai Chi Chuan (TCC) practitioners. DESIGN: Case-control study of a TCC group and a group of sedentary controls. SETTING: Research project at a hospital-based exercise physiology laboratory. PARTICIPANTS: Seventy-six community-dwelling senior persons (mean age 69.3 +/- 3.9 yr), a TCC group that included 22 men and 19 women and a control group of sedentary subjects that included 18 men and 17 women with matched age and body size. INTERVENTION: The TCC group had practiced TCC regularly for 11.8 +/- 5.6 years, with an exercise frequency of 4.3 +/- 1.3 times per week. Each session included 20 minutes of warm-up, 24 minutes of TCC training, and 10 minutes of cool-down. Exercise intensity was estimated to exceed 70% of maximal heart rate (HRmax). MAIN OUTCOME MEASURE: Breath-by-breath measurement of cardiorespiratory function was obtained during the incremental exercise of leg cycling. Flexibility of thoracic/lumbar spine was measured by an electronic inclinometer. Percentages of body fat was calculated from biceps and subcapsular skinfolds. RESULTS: In the peak exercise, men in the TCC group showed 19% higher peak oxygen uptake (VO2peak) in comparison with their sedentary counterparts (26.9 +/- 4.7 mL/kg/min vs 21.8 +/- 3.1 mL/kg/min). Women in the TCC group also showed 18% higher VO2peak than in the sedentary group (20.1 +/- 2.9 mL/kg/ min vs 16.5 +/- 2.0 mL/kg/min). The TCC group also showed higher oxygen uptake at the ventilatory threshold. In addition, the TCC practitioners were characterized by greater flexibility and lower percentage of body fat in comparison with their sedentary counterparts. CONCLUSION: It is concluded that TCC training has benefits for health-related fitness, and it may be prescribed as a suitable conditioning exercise for the elderly.

Aged↗
PubMed1996

[Quadrant pattern visual evoked potential in normal eyes].

OBJECTIVE: The study was designed to approach the difference in pattern visual evoked potential (PVEP) among quadrants of the normal eye. METHODS: Quadrant transient PVEP method was used to record quadrant PVEP for 70 eyes of 35 normal subjects. RESULTS: The latency of P100 in lower temporal and lower nasal fields was significantly shorter than that in upper temporal and upper nasal fields; the amplitude of P100 in lower temporal and lower nasal fields was significantly higher than that in upper temporal and upper nasal fields. Generally, in lower field, the P100's latency is shorter and its amplitude higher. CONCLUSION: The difference in P100 between upper and lower field of normal person is possibly related to the fact that the lower field is used more frequently than the upper in ordinary human or animal life, and to the differences in distribution of retinal ganglion cells and in retina-cortex pathway between the upper and lower retina.

Adult↗
PubMed1995

Social aspects of malaria in Heping, Hainan.

This paper presents findings from a study conducted in Heping Town, Qiongzhong County, Hainan Province, China. The study, conducted in 1992, used qualitative as well as quantitative methods to gather social, cultural and behavioural data associated with the acquisition, transmission and prevention of malaria, and the diagnosis and treatment of disease. These methods included focus groups, key informant and other in-depth interviews, and observations, a household survey and tests of school children of knowledge of malaria. The study is among the first to our knowledge that has utilized this broad mix of methods for tropical disease research in China.

Adolescent↗