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Biomedical subjects

L B Tan

Publications and source records attributed to L B Tan.

At least 73 records · Page 4Linked to original sources
PubMed1992

Intracellular free magnesium in lymphocytes from patients with congestive cardiac failure treated with loop diuretics with and without amiloride.

Cellular Mg2+ depletion has been reported in patients on long term diuretic therapy. We therefore measured lymphocyte free Mg2+ concentrations in patients with congestive cardiac failure treated with loop diuretics or a frusemide/amiloride mixture (Frumil) and compared them with control subjects. There was no correlation between lymphocyte free Mg2+ levels and plasma Mg2+ concentrations. Patients treated with loop diuretics did not show lymphocyte intracellular free Mg2+ depletion compared with normal controls, and those on Frumil showed higher intracellular free Mg2+ levels than normal.

Amiloride↗
PubMed1992

The use of dobutamine stress thallium scintigraphy in the diagnosis of syndrome X.

Dobutamine stress thallium scintigraphy is a non-exercise stress technique used in the assessment of myocardial ischaemia. Non-exercise techniques are independent of the patient's exercise capacity or the subjective development of limiting symptoms. Preliminary data are presented regarding the effects of graded infusions of dobutamine (maximum 20 micrograms/kg/min) in seven consecutive patients with syndrome X. The dobutamine stress test caused significant increases in mean heart rate (rest 65.4 beats/min, peak dobutamine infusion 112.4 beats/min, P < 0.001) and systolic blood pressure (rest 138.6 mmHg, peak dobutamine infusion 166.7 mmHg, P = 0.002) and provoked typical symptoms in all the patients. Single photon emission computerized tomography was performed and the mean number of reversible defects was 1.86 per patient (range 1-3). One patient developed transient atrial fibrillation during the dobutamine infusion but there were no complications in the remainder of the study group. It is concluded that dobutamine-thallium scintigraphy in patients with syndrome X is safe, reproduces patients symptoms' reliably and presents a controllable degree of stress to the cardiovascular system. The consistent demonstration of a reversible perfusion defect in patients with syndrome X is evidence of abnormal myocardial physiology. This criterion could be added to those currently used to define syndrome X in order to improve objectively the identification of this patient group.

Aged↗
PubMed1992

[Renal pelvic tumor associated with contralateral renal cyst--a case report].

A 74-year-old female presented with a two years history of malaise, weakness and intermittent gross hematuria. Two years earlier, left renal cyst had been diagnosed by excretory urography, abdominal sonography and computed-tomography. Initially she was treated conservatively with oral antibiotics, however medical management had not been successful in improving her condition. Finally she was transfer to our ward for further evaluation and treatment. Cystoscopic examination demonstrated no abnormality, except for bloody urine efflux from the right ureteric orifice. Right retrograde pyelograms confirmed a solitary filling defect in the upper calyx of right kidney. Because of immediate concern for right renal pelvic tumor and contralateral renal cyst, a midline transperitoneal exploration was made. The right nephroureterectomy with cuff of bladder was removed and left unroofing of cyst was carried out. Convalescence was uneventful. The pathologic examination revealed moderately differentiated transitional cell carcinoma of right kidney with a simple renal cyst of left kidney. We suggest that cases with a clinical diagnosis of renal cyst based on the presence of gross hematuria, a normals excretory urogram and computed tomogram, generally require further evaluation especially by cystoscope and retrograde pyelogram to determine the source of bleeding.

Aged↗
PubMed1991

Comparison of the haemodynamic effects of dopexamine and dobutamine in patients with severe congestive heart failure.

Dopexamine hydrochloride is a novel compound with properties of DA1-dopaminergic and beta 2-adrenergic receptor agonism and neuronal noradrenaline uptake inhibition. It has been shown to produce beneficial renal and haemodynamic effects in patients with severe heart failure. We compared the haemodynamic effects of dopexamine (0.5 to 6 micrograms/kg/min) with those of dobutamine (5 to 25 micrograms/kg/min) in 9 patients with severe congestive heart failure. The two drugs were similar in their effects at peak infusion rates: heart rate increased (dopexamine 87 +/- 17 to 100 +/- 14; dobutamine 91 +/- 18 to 103 +/- 17 min-1), cardiac index increased (dopexamine 1.7 +/- 0.5 to 2.8 +/- 1.1; dobutamine 1.8 +/- 0.5 to 3.0 +/- 1.1 l.min-1.m-2) and systemic vascular resistance decreased (dopexamine 1553 +/- 221 to 1117 +/- 432; dobutamine 1721 +/- 347 to 1280 +/- 433 dyne.s.cm-5). Neither drug affected pulmonary artery wedge pressure (dopexamine 24 +/- 6 to 22 +/- 6; dobutamine 25 +/- 9 to 24 +/- 10 mm Hg). Dopexamine had significantly lower peak effects on left ventricular stroke work index (dopexamine 20 +/- 9, dobutamine 27 +/- 15 g.m.m-2, P less than 0.05) and cardiac power output (dopexamine 0.71 +/- 0.36, dobutamine 0.93 +/- 0.46 W, P less than 0.05). These haemodynamic effects, due largely to vasodilatation but with some contributory positive inotropy, indicate that dopexamine will be useful in the acute treatment of congestive heart failure.

Dobutamine↗
PubMed1991

Traumatic rupture of the corpus cavernosum.

Twelve patients with fracture of the penis have been treated in this department during the last 18 years. Their mean age was 41.5 years (range 25-55) and two-thirds of the injuries resulted from coitus. Eleven patients underwent immediate exploration and repair of the tunica albuginea and only 1 still has sexual dysfunction. One patient was treated conservatively and remains impotent. Immediate surgical treatment is recommended, since it avoids the formation of penile plaque, penile fibrosis and angulation and accelerates restoration of normal penile function.

Adult↗
PubMed1991

Comparison of the effects of papaverine versus prostaglandin E1 on penile blood flow by color duplex sonography.

To compare the effects of papaverine (60 mg) and prostaglandin E1 (20 microgram: PGE1) on penile blood flow, the vascular response detected with color duplex ultrasound scanning and the clinical response in 34 impotent men were observed and recorded after they had received an intracorporeal injection of the respective drugs on separate days. The results demonstrate that PGE1 has the advantage of a slower onset, longer maintenance, less chance of priapism and is at least as effective as papaverine in inducing an increment of penile blood flow. In conclusion, PGE1 may be a better alternative to papaverine in the diagnosis and treatment of impotence.

Alprostadil↗
PubMed1991

Cardiac myocyte necrosis induced by angiotensin II.

Although the role of angiotensin II (Ang II) in the pathogenesis and progression of the failing heart is uncertain, previous reports have suggested that myocyte injury may be a component in this process. In this study, we investigated this possibility in more detail. Cardiotoxic effects of nonacutely hypertensive doses of Ang II were examined in 90 rats, including those receiving an angiotensin infusion (200 ng/min i.p.) and those with renovascular hypertension, where endogenous stimulation of Ang II occurred. Myocyte injury and wound healing resulting from these treatments were evaluated by 1) immunofluorescence after in vivo monoclonal antibody labeling of myosin to detect abnormal sarcolemmal permeability, 2) [3H]thymidine incorporation into DNA, to detect fibroblast proliferation, and 3) light microscopic evidence of myocytolysis and subsequent scar formation. We found that exogenous Ang II produced multifocal antimyosin labeling of cardiac myocytes and myocytolysis, which were maximal on days 1-2 of the infusion. Subsequently, DNA synthesis rates were increased, with fibroblast proliferation reaching peak levels on day 2 (Ang II-treated rats, 90.0 +/- 18.6 cpm/micrograms DNA; control rats, 11.4 +/- 2.3 cpm/micrograms DNA; p less than 0.05); microscopic scarring was found on day 14 and represented 0.12 +/- 0.02% of the myocardium. Concurrent treatment with both propranolol (30 mg/kg/day s.c.) and phenoxybenzamine (5 mg/kg/day i.m.) did not attenuate Ang II-induced antimyosin labeling. Increased endogenous Ang II, resulting from renal ischemia after abdominal aortic constriction, produced both antimyosin labeling and increased rates of DNA synthesis like that observed with Ang II infusion. Both myocyte injury and fibroplasia were prevented with captopril (65 mg/day p.o.), but this protective effect was not seen with reserpine pretreatment. Infrarenal aortic banding without renal ischemia, on the other hand, produced hypertension without necrosis. We conclude that pathophysiological levels of endogenous as well as low-dose exogenous Ang II were associated with altered sarcolemmal permeability and myocytolysis with subsequent fibroblast proliferation and scar formation. Myocyte injury was unrelated to the hypertensive or enhanced adrenergic effects of Ang II or to hypertension per se. Captopril was effective in preventing myocyte injury in renovascular hypertension. The mechanism(s) responsible for Ang II-induced necrosis will require further study.

Angiotensin II↗
PubMed1991

[Transvesical prostatectomy for benign prostatic hyperplasia--a 364 cases analysis].

During a 16 year period from January 1972 to December 1988, transvesical prostatectomies were performed on 364 patients with benign prostatic hyperplasia in the Department of Urology, Kaohsiung Medical College Hospital. The average operational procedure time was 116.1 minutes and the average amount of tissue resected was 38.3 grams. The most common complications were wound infections (6.8%), stress incontinence (1.92%), urethral stricture (4.12%) and impotence (0.27%). In this series, epididymitis and/or orchitis was noted in 4.3% of those who underwent vasectomies and 1.8% of those who did not; thus, epididymitis cannot be prevented by a prophylactic vasectomy. There was one postoperative death (mortality rate-0.27%). The present study found that 6.86% of the transvesical prostatectomy patients will require longer hospitalization and greater amounts of antibiotics due to post-operative wound infection; therefore the use of transvesical prostatectomy will decline and only be recommended for fit patients with others genitourinary diseases such as bladder diverticulum or giant bladder calculus.

Aged↗
PubMed1991

Evaluation of cardiac dysfunction, cardiac reserve and inotropic response.

The assessment of cardiac function and dysfunction has often concentrated on particular but piecemeal aspects of ventricular performance. This leads to diverse and often opposite claims on how to define, evaluate and treat heart failure. This review adopts a more integrative approach of appraising the heart, putting it in the context of its role in the circulation. The emphasis is to find a variable which would evaluate the overall function of the heart. Several objective criteria on how to select such a variable were proposed. It was argued that of all currently available variables, cardiac power output fulfils these requirements best. It has long been recognised that cardiac performance assessed at basal resting states do not reflect how much reserve the cardiac pump possesses. Having a variable which represents overall cardiac function implies that cardiac pumping capability and reserve can now be quantified. Cardiac reserve has been found to be a major determinant of exercise capacity in heart failure, and pumping capability a major determinant of prognosis in patients with severe heart failure. Therapeutic attempts at improving the exercise capacity of heart failure patients should be gauged against their ability to improve cardiac reserve. Inotropic agents that augment myocardial performance but compromise cardiac reserve do not improve exercise capacity. An ideal inotrope is one that is synergistic with the sympathetic system and enhances cardiac performance only during exercise.

Cardiac Output↗
PubMed1990

The correlation of cardiac power output to exercise capacity in chronic heart failure.

Cardiac haemodynamics are deranged in chronic heart failure but fail to predict the exercise capacity of the patient. Cardiac power output is a descriptor of cardiac function derived from preload, blood pressure and cardiac output. Forty-one patients with moderately severe and severe chronic heart failure were exercised on a cycle ergometer to determine the relationship between traditional haemodynamics and cardiac power output and exercise capacity. Resting cardiac power output was no more predictive of exercise capacity than resting stroke-work index or resting cardiac index (r = 0.53, 0.61 and 0.51 respectively). Maximum cardiac power output and the ability to increase cardiac power output, however, were correlated with exercise capacity (r = 0.79 and 0.80). It is concluded that resting cardiac power output does not predict subsequent exercise capacity but that maximum cardiac power output and the ability to increase cardiac power output on stimulation are good descriptors of functional cardiac reserve.

Adult↗
PubMed1990

Experiences in the treatment of chyluria in Taiwan.

From 1967 through 1986, 55 patients with chyluria were treated by renal pelvic instillation of 10 ml. 0.5% silver nitrate solution and surgical disconnection of the renal pedicle lymphatics was done in 9 (16.3%) due to persistent chyluria after instillation therapy. Among these 46 renal pelvic instillation patients and 9 operated patients followed for 2 years chyluria recurred in 11 (22.7%) and 5 (55.5%), respectively. Renal pelvic instillation is a safe and effective method to treat chyluria.

Chyle↗
PubMed1990

Measurement of cardiac reserve in cardiogenic shock: implications for prognosis and management.

The hypothesis that the prognosis of cardiogenic shock patients is primarily dependent on cardiac pumping reserve was tested in a prospective study of 28 consecutive patients clinically diagnosed to be in cardiogenic shock and treated medically. Haemodynamic function was assessed by thermodilution Swan-Ganz catheters and arterial cannulas. The cardiac pumping reserve was evaluated by the response of the failing heart to graded incremental dobutamine infusion (2.5 to 40 micrograms/kg/min) after optimalising the left ventricular preload. Eleven of the patients survived for more than the one year of follow up and the rest died. Haemodynamic evaluation during the basal resting state was only able to identify unambiguously non-survivors whose cardiac function was most severely compromised. Survivors and non-survivors with higher values were indistinguishable by basal haemodynamic criteria. The response to dobutamine stimulation clearly separated the cardiac pump function of survivors and those who died. All patients with peak cardiac power output of less than 1.0 W or peak left ventricular stroke work index of less than 0.25 J/m2 died whereas all those with higher values lived for more than a year. Thus this study showed that haemodynamic evaluation of cardiac reserve can provide objective criteria for predicting outcome in individual patients with cardiogenic shock. The availability of such a prognostic indicator will be invaluable in formulating management plans for these patients.

Adult↗
PubMed1990

Remodeling of the rat right and left ventricles in experimental hypertension.

Pathological left ventricular hypertrophy in renovascular hypertension is associated with the accumulation of fibrillar collagen within the extracellular space and around intramyocardial coronary arteries. Even though the angiotensin converting enzyme inhibitor captopril was previously found to attenuate this interstitial and perivascular fibrosis, the relative importance of arterial and ventricular systolic pressures versus circulating angiotensin II (AII) and aldosterone (AL) in promoting hypertrophy and collagen accumulation in renovascular hypertension is uncertain. By drawing on the in-parallel arrangement of the right and left ventricles, with respect to their coronary circulation, and the in-series mechanical alignment of the ventricles, with a pressure-overloaded left and a normotensive right ventricle, this study sought to address this uncertainty. Three models of experimental hypertension, each having a different circulating AII and AL profile, were examined and compared with their controls: renovascular hypertension, where both AII and AL are increased; infrarenal aorta banding, where AII and AL are normal; and a chronic infusion of AL, where AII is suppressed or normal and AL is increased. In renovascular hypertension, as well as with AL, we found a significant rise in the interstitial collagen volume fraction and perivascular collagen area of the pressure-overloaded, hypertrophied left ventricle as well as the normotensive, nonhypertrophied right ventricle. This remodeling was not seen in either ventricle with infrarenal aorta banding despite comparable systemic hypertension and left ventricular hypertrophy. Thus, in experimental arterial hypertension in the rat, myocyte and nonmyocyte compartments of the myocardium are under separate controls: myocyte hypertrophy is most closely related to ventricular loading while circulating AII and AL, acting alone or in concert with other humoral factors, regulate the accumulation of collagen within the right and left ventricles.

Aldosterone↗
PubMed1990

[Clinical analysis of penile cancers among Chinese in Taiwan].

From 1972 to 1984, 34 patients with the histologic diagnosis of penile carcinoma were treated at Kaohsiung Medical College Hospital. Of the 34 patients 1 (3%) had transitional cell carcinoma, the others had epidermoid carcinoma. Their ages ranged from 19 to 73 years with a mean of 54 years; the majority of the patients were in the fifth and sixth decades of life. The most common clinical symptom of the tumor was a mass or ulcer over the penis. Phimosis, Bowen's disease and venereal diseases seemed to bear a close etiologic relationship to the penile carcinoma. The prognosis of penile cancer depends upon the stage of the disease. The 5-year survival rates were: 60% for Stage A, 38% for Stage C, and 0% for Stage D patients. Cumulative survival rate was 39%. Circumcision in the neonatal stage is the most effective method in preventing such a disease.

Adult↗
PubMed1990

[Prostatic cancer: an analysis of 42 cases].

Between January 1972 and December 1983, 42 cases of adenocarcinoma of the prostate were admitted to Kaohsiung Medical College Hospital. The ages ranged from 46 to 90 years, with a mean of 68.6 years. The peak age group was 60-79 years of age and 2.3 per cent were less than 50 years old. The prospect for prognosis was worse if the serum acid phosphatase level was elevated. The over-all 5-year survival rate of this series was 21%. The survival rate varied according to the clinical stage: Stage A, 40%; Stage B, 31.5%; Stage D, 6.25%. On the basis of our study, the most promising approach toward increasing the survival of patients with cancer of the prostate would be earlier detection and immediate definitive treatment, including radical prostatectomy and castration. The importance of an annual physical examination, especially in men over 50 years of age which includes digital palpitation of the prostate gl, is emphasized.

Acid Phosphatase↗