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Biomedical subjects

M F Chen

Publications and source records attributed to M F Chen.

At least 181 records · Page 10Linked to original sources
PubMed1996

Left atrial spontaneous echo contrast in asymptomatic patients with a mechanical valve prosthesis.

BACKGROUND: Valve thromboembolism may be a fatal complication of mechanical valve prosthesis if detected late. Spontaneous echo contrast (SEC) is a well-documented prothrombotic phenomenon; here we report it in asymptomatic patients with a mechanical valve prosthesis. METHODS: Ninety-two asymptomatic patients with a mechanical valve prosthesis for underlying rheumatic heart disease underwent transesophageal echocardiography. Appendage area, peak filling and emptying velocities of the left atrial appendage, and the presence or absence of SEC and thrombi were determined. The results of 56 patients without SEC or thrombi (group I) were compared with those of 24 patients with SEC and no thrombi (group II) and 12 patients with thrombi (group III). RESULTS: Spontaneous echo contrast was present in 39% of the asymptomatic patients with a mechanical valve prosthesis. Although 12 patients had cardiac thrombi, including valve thrombi in 4, no patients presented symptoms. Anticoagulant therapy had no significant association with SEC and atrial thrombi. There was a significantly greater prevalence of atrial fibrillation and mitral prosthesis in groups II and III than in group I. Two patterns of left atrial appendage flow were identified: one was organized biphasic flow with peak filling velocities of 41.2 +/- 17.2 cm/s and emptying velocities of 40.5 +/- 17.5 cm/s. The other showed irregular, very low peak filling velocities (104 +/- 11.5 cm/s) and emptying velocities (12.3 +/- 13.1 cm/s). The former flow pattern was associated with sinus rhythm and the latter form was associated with atrial fibrillation. CONCLUSIONS: There was a relatively high prevalence of SEC and thrombi in patients with a mechanical valve prosthesis. Patients with a valve prosthesis may not have clinical symptoms. Anticoagulation intensity was not associated with the occurrence of SEC and thrombi. Patients with the mitral valve prosthesis and atrial fibrillation were identified as a high-risk of subgroup for the development of SEC and thrombi.

Adult↗
PubMed1996

Surgical treatment of hepatolithiasis: long-term results.

BACKGROUND: Hepatolithiasis is a common disease in East Asia and is prevalent in Taiwan. Surgical and nonsurgical procedures for management of hepatolithiasis have been discussed, but long-term follow-up results of surgical treatment of hepatolithiasis are rarely reported. METHODS: We conducted a retrospective study of case records of patients with hepatolithiasis who underwent surgical or nonsurgical percutaneous transhepatic cholangioscopy treatment. Of 614 patients with hepatolithiasis seen between January 1984 and December 1988, 427 underwent follow-up after surgical (380) or percutaneous transhepatic cholangioscopy (47) treatment for 4 to 10 years and constituted the basis of this study. RESULTS: Long-term results of 427 patients with hepatolithiasis after surgical and nonsurgical treatment within 4 to 10 years of follow-up were recurrent stone rate 29.6% (105 of 355), repeated operation 18.7% (80 of 427), secondary biliary cirrhosis 6.8% (29 of 427), late development of cholangiocarcinoma 2.8% (12 of 427), and mortality rate 10.3% (44 of 427). The patients with hepatectomy had a better quality of life (symptom-free) with a lower recurrent stone rate (9.5%), lower mortality rate (2.1%), and lower incidence of secondary biliary cirrhosis (2.1%) and cholangiocarcinoma (0%) than did the nonhepatectomy group (p < 0.01). The patients without residual stones after choledochoscopy had a better quality of life than did the residual stone group (p < 0.01). CONCLUSIONS: Long-term follow-up study of hepatolithiasis after surgical treatment revealed a high recurrent stone rate (29.6%) that required repeated surgery and a high mortality rate (10.3%) resulting from repeated cholangitis, secondary biliary cirrhosis, and late development of cholangiocarcinoma. Patients who received hepatectomy or without residual stones after choledochoscopy had a good prognosis and quality of life.

Adolescent↗
PubMed1996

Plasma and erythrocyte thiamin concentrations in geriatric outpatients.

OBJECTIVE: The objective of this study was a) to determine the plasma and red cell thiamin levels in geriatric outpatients and b) to evaluate, using the rat model, the sensitivity of plasma thiamin concentration as an indicator of nutritional status for this vitamin. SUBJECTS: Thirty geriatric outpatients were evaluated for their plasma and erythrocyte thiamin levels. METHODS: Plasma and red cell thiamin levels were determined by a microbiologic assay using kloeckera apiculata. Sprague-Dawley rats were fed a thiamin deficient diet. Blood samples were obtained on specified days and the plasma and erythrocyte thiamin levels determined. RESULTS: Forty-three percent of the subjects studied had plasma thiamin levels below 2 SD of the mean of the younger-age group (20-60 yr) while 57% had a plasma thiamin below 10 ng/ml (the lower reference range of the younger age group). Twenty-seven percent were found to have red cell thiamin levels below 2 SD of the mean of the younger-age group, while 33% had red cell thiamin levels below 138 ng/ml (the lower reference range of the younger-age group). The rat study indicated that plasma thiamin concentration is a sensitive indicator of the nutritional status for this vitamin. CONCLUSION: About 50% of geriatric outpatients in this study had low plasma thiamin levels. The long-term effect of a low plasma thiamin level on cognitive functions remains to be investigated.

Adult↗
PubMed1996

Effects of increasing flow rate on aortic stenotic indices: evidence from percutaneous transvenous balloon dilatation of the mitral valve in patients with combined aortic and mitral stenosis.

OBJECTIVES: To investigate the effects of transvalvar flow rate on aortic valve resistance and valve area after percutaneous transvenous balloon dilatation of the mitral valve in a homogeneous group of patients with rheumatic heart disease. DESIGN: Retrospective analysis of 12 patients with combined aortic and mitral stenosis who had undergone balloon dilatation of the mitral valve over a period of 9 years. SETTING: Tertiary referral centre. PATIENTS: Twelve (8 women, 4 men; mean (SD) age 37 (9) of 227 consecutive patients with critical mitral stenosis undergoing transvenous balloon dilation of the mitral valve in the centre also had aortic stenosis, defined as a transaortic pressure gradient of more than 25 mm Hg measured at a catheterisation study before valvuloplasty. INTERVENTIONS: Echocardiographic variables (mitral valve area measured by the pressure half-time method and planimetry, and the aortic valve area derived from the continuity equation) and haemodynamic measurements (cardiac output, left ventricular mean systolic pressure, aortic mean pressure, transaortic valve pressure gradient, mitral valve and aortic valve areas derived from the Gorlin formula, and aortic valve resistance) were assessed before and after transvenous balloon dilatation of the mitral valve. Follow up catheterisation to measure haemodynamic variables was performed one week after mitral valvuloplasty. RESULTS: Mean transaortic flow rate increased 33% after mitral valvuloplasty (from 198 (68) to 254 (41) ml/s, P = 0.002). Aortic valve areas derived from the Gorlin formula were significantly increased from 0.57 (0.12) to 0.73 (0.14) cm2 (P = 0.006) after mitral valvuloplasty. However, aortic valve area and valve resistance derived from the continuity equation were independent of the increase in flow rate after mitral valvuloplasty (from 1.29 (0.35) to 1.30 (0.29) cm2 and from 317 (65) to 259 (75) dyn.s.cm-5, both P = NS). CONCLUSION: The Gorlin-derived aortic valve area tends to be flow-dependent, and continuity equation-derived aortic valve area and catheterisation-derived valve resistance seem to be less flow-dependent. In patients with combined mitral and aortic stenosis, these flow-independent indices are important for decision-making.

Adult↗
PubMed1996

Effect of serum from partially hepatectomized cirrhotic and noncirrhotic rats on liver regeneration with primary hepatocyte cultures.

The effects of serum from cirrhotic and noncirrhotic rats after 33% and 70% partial hepatectomy on the hepatocyte culture were studied. Liver cirrhosis was produced by weekly intragastric feeding with carbon tetrachloride (CCl4) for 12-16 weeks. The serum was prepared with blood withdrawn from the rats 2 and 48 h after partial hepatectomy or sham operation. The incorporation of [3H]thymidine in the hepatocyte culture after addition of rat serum (1.0 +/- 10(5) cells/ml) was assessed. We found that the mitogenic effect of the serum at 2 and 48 h after partial hepatectomy was not significant. In the 70% hepatectomy group, the serum from cirrhotic rats had a stronger stimulatory effect to induce hepatocytes in primary culture entering DNA synthesis than that from noncirrhotic rats; but the difference was not statistically significant. The mitogenic effect of the serum from noncirrhotic rats after 33% hepatectomy was significantly lower than that from cirrhotic rats after 33% hepatectomy (p < 0.05). In this series, the serum from the cirrhotic rats after 33% hepatectomy had the strongest mitogenic effect; the serum from the partially hepatectomized rats with cirrhotic and non-cirrhotic livers increased [3H]thymidine uptake into hepatocyte DNA significantly more than control serum or plasma.

Animals↗
PubMed1996

Transcatheter embolization of a coronary arteriovenous fistula with a complex, helical-fibered platinum coil.

Transcatheter embolization was successfully performed on a 51-year-old man with a coronary arteriovenous fistula arising from the left circumflex coronary artery and draining into the superior vena cava. The patient presented with typical manifestations of angina pectoris that were first noticed during childhood but had worsened over the past 5 years. A 2 x 20 mm complex, helical-fibered platinum coil was placed in the mid-portion of the fistula and successfully occluded the fistula within 30 minutes. The patient has been free from angina pectoris since the procedure.

Arteriovenous Fistula↗
PubMed1996

Propofol anesthesia in a patient with myasthenia gravis--a case report.

Experience with the use of propofol for induction and maintenance of anesthesia in patients with myasthenia gravis is limited in the literature. We report, in this case, the well prepared and successful use of continuous propofol infusion without conventional neuromuscular blocking agents in a patient with Ossermann stage IIb of myasthenia gravis undergoing laparoscopic cholecystectomy.

Anesthesia, Intravenous↗
PubMed1995

Dobutamine stress echocardiography predicts early wall motion improvement after elective percutaneous transluminal coronary angioplasty.

In 24 patients with chronic coronary artery disease, dobutamine stress echocardiography (DSE) was performed within 2 days before and after successful elective percutaneous transluminal coronary angioplasty (PTCA) in a blinded fashion. Patients with ischemic response on DSE before PTCA had significant improvement in the global peak-dose DSE score index after PTCA (1.62 +/- 0.35 to 1.40 +/- 0.29, p < 0.001), whereas patients without ischemic response had no improvement. The positive and negative predictive values of pre-PTCA DSE on early myocardial ischemia relief after angioplasty were 93% and 80%, respectively. In patients showing contractility recruitment during low-dose dobutamine infusion in the DSE before PTCA, there was significant improvement in the global resting wall motion score index in the DSE after PTCA (1.48 +/- 0.43 to 1.34 +/- 0.33, p = 0.004), while patients without contractility recruitment showed no improvement. Again, the positive and negative predictive values of pre-PTCA DSE on early hibernation recovery following angioplasty were 80% and 89%, respectively. In conclusion, DSE in patients with chronic, stable coronary artery disease accurately predicts wall motion improvement after successful angioplasty, and the expected improvement is safely demonstrated early after the procedure.

Adult↗
PubMed1995

Radical scavenger and antihepatotoxic activity of Ganoderma formosanum, Ganoderma lucidum and Ganoderma neo-japonicum.

The free radical scavenging and antihepatotoxic activity from Ganoderma lucidum, Ganoderma formosanum and Ganoderma neo-japonicum were studied. Treatment with the water extract of Ganoderma lucidum, Ganoderma formosanum and Ganoderma neo-japonicum caused a marked decrease in the CCl4-induced toxicity in rat liver, made evident by their effect on the levels of glutamic oxaloacetic transaminase (GOT) and lactic dehydrogenase (LDH) in the serum. The scavenging potency of the water extracts of the crude drugs was evaluated in terms of their ability to reduce the peaks of spin adducts using electron spin resonance (ESR) spin-trapping techniques. The results indicated that Ganoderma formosanum showed the greatest antihepatotoxic activity and the greatest free radical scavenging activity.

Alanine Transaminase↗
PubMed1995

Effect of 5-fluorouracil on methotrexate transport and cytotoxicity in HT29 colon adenocarcinoma cells.

Exposure of the human colon adenocarcinoma HT29 cells to different concentrations of 5-fluorouracil (5FU) for 24 h resulted in a dose-dependent increase in the cellular glutathione (GSH) level which remained elevated up to 72 h following 5FU treatment. Pretreatment of HT29 cells with 5FU was found to enhance the uptake of methotrexate (MTX) as compared to control cells. Administration of MTX 24 h after 5FU was found to be synergistic, whereas administration of MTX 24 h before 5FU or together with 5FU was not found to be synergistic. The results of this study suggest that the increase in cellular GSH level as a result of 5FU pretreatment may play a role in the enhancement of MTX uptake and the cytotoxicity of both drugs in HT29 cells.

Adenocarcinoma↗
PubMed1995

Developmental anomalies suggestive of the human homologue of the mouse mutant disorganization.

We describe a 21-week-old fetus with a pattern of multiple congenital anomalies suggestive of the human homologue of the mouse mutant disorganization (Ds). Manifestations included facial asymmetry, thick eye brows, micrognathia, apparently lowset ears, an enormous abdominal wall defect, severe kyphoscoliosis, camptodactyly of the fingers, complete absence of the left lower limb, and absence of the lower part of the sacrum and coccyx, as well as left side of the pelvis. There was a disorganized appearance of the right foot with supernumerary digits and appendages and talipes equinovarus. No obvious amniotic bands or oligohydramnios were noted. Similar cases in the literature are reviewed and the clinical significance to genetic counselling is emphasized.

Adult↗
PubMed1995

Plasma and red blood cell thiamine deficiency in patients with dementia of the Alzheimer's type.

OBJECTIVES: To determine the prevalence of plasma thiamine deficiency in patients referred to a memory disorder clinic and to compare plasma thiamine levels with red blood cell (RBC) thiamine levels. To determine if patients with senile dementia of the Alzheimer's type (SDAT) differ from those without SDAT in either plasma or RBC thiamine levels. DESIGN: Case-control study. SETTING: Ambulatory care referral center. PATIENTS: Consecutive sample of 34 patients; 17 patients who met the National Institute of Neurological and Communicative Disorders and Stroke-Alzheimer's Disease and Related Disorders Association criteria for probable Alzheimer's disease and 17 patients with other forms of dementia. METHODS: Plasma and RBC thiamine levels were determined in all patients with the use of a microbiologic assay known for its specificity to biological forms of thiamine. Vitamin supplementation was determined by chart review. OUTCOME MEASURES: Plasma and RBC thiamine levels. RESULTS: Patients with SDAT were found to have significantly lower plasma thiamine levels than patients without SDAT. Low plasma thiamine levels were detected in a significantly larger proportion of patients with SDAT than in patients without SDAT. Red blood cell thiamine levels did not correlate with the clinical diagnosis of SDAT. Vitamin supplementation did not correlate with diagnosis and plasma or RBC thiamine levels. CONCLUSIONS: A significant proportion of patients with SDAT may have a thiamine deficiency, which may have an impact on cognitive function. Currently used assays may not be adequate to assess thiamine status.

Aged↗
PubMed1995

A double-blind comparison of once-daily metoprolol controlled-release and atenolol in the treatment of Chinese patients with mild to moderate hypertension.

The efficacy and tolerability of controlled-release metoprolol (metoprolol CR/ZOK), 100-200 mg, and atenolol, 50-100 mg, once daily was compared in Chinese patients with mild to moderate essential hypertension. The study was of a randomized, double-blind, two-way crossover design. The active treatment periods lasted 4 weeks each and were preceded by a 4-week placebo run-in period. The two double-blind phases were separated by a 2-week washout period on placebo. Blood pressures and heart rates were measured at rest in each 2-week visit and during exercise at the end of each treatment period. Twenty-four patients (M/F = 14/10) were valid for efficacy analysis. Their ages ranged from 39 to 68, with a mean of 53.5 years. The rest supine blood pressure and heart rate before active treatment was 160 +/- 15/106 +/- 6 mmHg and 75 +/- 14 beats/min (mean +/- SD), respectively. A responder was defined as exhibiting a supine diastolic blood pressure < or = 90 mmHg or a supine diastolic blood pressure reduction of at least 10% of the baseline level. Both agents had high response rate: 88% and 92% of all patients responded to metoprolol CR/ZOK and atenolol, respectively. Both active treatments considerably reduced resting systolic and diastolic blood pressures and heart rates as compared with baseline (p < 0.001), respectively. With controlled-release metoprolol, a more pronounced beta 1 blockade was obtained than with atenolol, which was expressed as a significant reduction in exercise-induced heart rate at the highest comparable workload compared with placebo (p < 0.05). These findings are compatible with those reported from western populations.

Administration, Oral↗
PubMed1995

Liver regeneration following partial hepatectomy and stimulation by hepatic stimulatory substance in cirrhotic and non-cirrhotic rats.

The effects of hepatic stimulatory substance (HSS) on cirrhotic and non-cirrhotic rats were studied after 70% partial hepatectomy. Liver cirrhosis was produced by weekly intragastric infusion of chloroform for 12-16 weeks. The HSS was prepared by extraction from the livers of weanling mice. Rats in the experimental group were injected with 5 ml HSS after 70% partial hepatectomy, and those in the control group received normal saline. The results showed that the 3H-thymidine incorporation was higher in the HSS group 24 h after partial hepatectomy in both cirrhotic and non-cirrhotic rats, and persistently higher in the non-cirrhotic rats at 48 h. Total DNA was significantly higher in the HSS group of non-cirrhotic rats 24 and 48 h after partial hepatectomy. The restituted liver volume and weight was significantly higher in non-cirrhotic rats 48 h after partial hepatectomy, while there was no significant difference between the HSS and the control groups in the cirrhotic rats. The HSS induced significant effects on 3H-thymidine incorporation in the non-cirrhotic liver, resulting in increasing liver weight, volume and total DNA 48 h after partial hepatectomy. In cirrhotic rats, the 3H-thymidine incorporation was higher in the HSS group at 24 h after partial hepatectomy, though not showing any increase at 48 h, but the regeneration of liver weight, volume and total DNA at 48 h showed no difference between the HSS group and the control group.

Animals↗