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Biomedical subjects

M C Lin

Publications and source records attributed to M C Lin.

At least 145 records · Page 8Linked to original sources
PubMed1996

Effect of beta 2-adrenoceptor agonists on plasma potassium and cardiopulmonary responses on exercise in patients with chronic obstructive pulmonary disease.

OBJECTIVE: The effect of beta 2-adrenoceptor agonist-induced hypokalaemia on cardiac arrhythmias might be exacerbated during exercise, especially in patients with more compromised airway function. METHODS: To evaluate the effect of beta 2-adrenoceptor agonists on plasma potassium and cardiopulmonary function during exercise, two identical submaximal treadmill exercise tests were performed, at least 48 h apart, by 13 patients with moderate to severe COPD (11 men and 2 women, mean age 66 y, mean FEV1/FVC ratio 48.9 (2.8)% 30 min after they had received nebulised fenoterol or salbutamol (2 mg). The experiment was done as a randomised, double-blind, crossover trial after an initial baseline study with vehicle (0.45% saline). Plasma potassium concentration, spirometry and the degree of breathlessness (Borg scale) were measured before treatment and immediately after exercise; oxygen saturation, QTc interval and cardiac rhythm were monitored continuously before, during and for 30 min after exercise. RESULTS: After the saline control, exercise caused an increase in Borg rating (of 4.9), a premature ventricular contractions (VPC) (2.8 beats/min), and a fall in oxygen saturation (-6.7%), but no significant change in plasma potassium (+0.04 mEq.dl-1), FEV1 or QTc interval. Inhalation of fenoterol and salbutamol did not affect QTc interval, Borg scale or VPC frequency at rest, but significantly increased the duration of exercise undertaken to reach the submaximal levels (786 s, versus 783 s) compared to the vehicle control. Following exercise, plasma potassium fell after fenoterol by 0.2 mEq.dl-1 and it increased after salbutamol by 0.1 mEq.dl-1 compared to baseline levels. Plasma potassium after exercise was significantly lower after fenoterol (3.2 mEq.dl-1) compared to the saline control (3.7 mEq.dl-1) and salbutamol (3.6 mEq.dl-1). Neither fenoterol nor salbutamol had any significant effect on the change in FEV1, oxygen saturation, Borg scale, frequency of VPCs or QTc interval during or after exercise compared to the saline control. CONCLUSION: When compared to salbutamol 2 mg, fenoterol 2 mg caused more marked hypokalaemia but no significant difference in cardiopulmonary response in patients with COPD during exercise.

Adrenergic beta-Agonists↗
PubMed1996

Androgens are not major down-regulators of androgen receptor levels during growth of the immature rat penis .

This study was undertaken to investigate the prevalent hypothesis that androgens are responsible for the organ-specific down-regulation of penile androgen receptors (ARs) and decline of penile growth in the rat during sexual maturation. Sexually immature male rats (21 days old) were castrated and treated for 3 days ("short-term"), with high doses of: (a) testosterone and the alpha-reductase inhibitor finasteride (T/F); (b) dihydrotestosterone (DHT); or (c) finasteride alone (F). Intact and castrate controls received vehicle only. PolyA + RNA was analysed by Northern blot hybridization and ARs were estimated in the penis and ventral prostates by (3-H)R-1881 binding in the cytosol. Short-term castration, with or without F, increased penile AR mRNA, whereas high doses of T/F and DHT reduced it considerably. Although penile cytosol AR concentration in the control castrates, with or without F, paralleled the AR mRNA rise, treatment with androgens left cytosol AR content per organ and AR concentration above those of the intact rat penis despite the drop in AR mRNA. A "long-term" treatment (10 days) on 19-day-old rats with either medium or high doses of T/F and DHT also failed to down-regulate penile cytosol ARs below the intact controls. Western blot analysis of penile cytosol AR levels confirmed these results. Block of pituitary FSH and LH release by a GnRH antagonist in castrates receiving T/F or DHT at high doses did not modify the response. In the case of intact rats, high doses of T/F or DHT actually increased penile cytosol AR content. No difference was observed between T/F and DHT effects. In contrast to what occurs during sexual maturation, the prostate ARs and growth rate responded to all treatments in a similar way to what was observed in the penis. Our results suggest that increases in serum T or DHT are not major factors in the physiological down-regulation of ARs and androgen-dependent growth in the rat corpora cavernosa.

Androgens↗
PubMed1996

Home mechanical ventilation: investigation of 34 cases in Taiwan.

To evaluate the characteristics of and acceptance by persons in Taiwan who currently use positive-pressure mechanical ventilation at home (HMV), a survey was conducted in August 1992 through home care and equipment providers to investigate these patients. The 34 cases enrolled, including 18 males and 16 females, were classified into four groups: (1) lung disease group (LD) (n = 7) including chronic obstructive pulmonary disease and bronchiectasis; (2) neuromuscular group (NM) (n = 14) including diverse neuromuscular diseases; (3) spinal disease group (SP) (n = 7) including spinal cord injuries or tumors and (4) unresponsive stroke group (US) (n = 6). The average age of the SP group was much younger than those of the other three groups. The duration of home ventilation was from 1 to 36 months, with a mean duration of 10.6 +/- 8.7 months. Fifteen cases had received HMV for more than one year. Twenty six (76.5%) of the patients were completely dependent. All of the US patients had to be ventilated all day long in contrast to 71.4% of LD completely dependent. The cost of the US group was higher than that of the other three groups. Two of the LD, five of NM and one US patient had been re-admitted because of pneumonia, tracheostomy wound infection, granulation formation or weaning problems before the study. A follow-up survey was done four months, then one year later. The survival rate was 16.7% for LD group, 50% for NM and US group. Of the SP group, all patients were surviving at the end of this study. Most of the present HMV users were satisfied with their setting. It was concluded that HMV is an acceptable alternative way of therapy for long-term ventilation patients in Taiwan. SP and NM patients are better candidates for HMV. The overall one year survival rate is promising, while SP patients had the best prognosis. Patients who had already used HMV for more than 11 months, regardless of the disease, have a better chance to live another year.

Adolescent↗
PubMed1996

Mature cystic teratoma of the ovary: a clinicopathologic study of 283 cases.

BACKGROUND: Although in the English literature, much has been published about ovarian teratoma, no large series has been reported in Taiwan. Therefore a retrospective study of 283 consecutive cases of mature cystic teratomas of the ovary, operated at National Taiwan University Hospital between 1988 and 1993, was undertaken. METHODS: This series was based on a retrospective chart study at the Department of Obstetrics and Gynecology of the National Taiwan University Hospital from 1988 to 1993. All cases included in this study were proven by pathology review. The clinical data, pathology and complications are summarized. RESULTS: The incidence of mature cystic teratoma was 32.6% of primary ovarian neoplasm. As for the age distribution, the youngest patient was 12 years old and the oldest, 76. The largest number of cases was found in patients between the ages of 20 and 30 years; the mean age was 35.4 years. Pain, the most common complaint, was noted in 48.1% of the cases in whom it varied from a dull ache to the sharp, stabbing pain of torsion. Of greater interest was an unexpectedly high incidence (16.6%) of asymptomatic cysts found on routine physical examination. The right ovary was involved in 51.2%, the left ovary in 40.6% and bilateral ovaries were involved in 8.2%. The incidence of torsion was 9.2%, and was the highest in all complications. Ten concurrent pregnancies were noted, an incidence of 3.5%. The incidence of malignant transformation was 0.7%, with a pathology of squamous cell carcinoma. CONCLUSIONS: Mature cystic teratom is the most common germ cell tumor and accounts for about 33% of all ovarian neoplasm They occur primarily during the reproductive years, but may occur in the postmenopausal period or in childhood. A cystic teratoma can undergo malignant transformation; it occurs most frequently in postmenopausal women, and the prognosis is poor. However, it is a rare complicaiton, with an incidence less than 1%.

Adolescent↗
PubMed1996

Cholera associated with acute renal failure and rhabdomyolysis: a case report.

While cholera is not endemic in Taiwan, the number of imported cases is increasing. We report a 59-year-old Taiwanese male who developed severe diarrhea and vomiting, two days after returning from Bali. The patient admitted drinking a beverage with ice purchased from a street vendor. On admission he was weak and dehydrated. The patient suffered from hypovolemic shock and acute renal failure. Elevated creatine phosphokinase indicated rhabdomyolysis. Fluid replacement with Ringer's lactate solution was instituted. Dyspnea and pulmonary edema developed, and hemodialysis was begun to remove excess fluid due to decreased urinary output. Isolation of Vibrio cholerae O1 from stool confirmed the diagnosis of cholera, and doxycyline was begun. The patient's condition stabilized, with increased urinary output, and resolution of diarrhea, vomiting and dyspnea. Cholera, although rare in Taiwan, can be lethal if left untreated. Rapid intervention with fluid replacement is essential to prevent hypovolemic shock and circulatory collapse in severe cases.

Acute Kidney Injury↗
PubMed1995

The cis-acting phorbol ester "12-O-tetradecanoylphorbol 13-acetate"-responsive element is involved in shear stress-induced monocyte chemotactic protein 1 gene expression.

Vascular endothelial cells, serving as a barrier between vessel and blood, are exposed to shear stress in the body. Although endothelial responses to shear stress are important in physiological adaption to the hemodynamic environments, they can also contribute to pathological conditions--e.g., in atherosclerosis and reperfusion injury. We have previously shown that shear stress mediates a biphasic response of monocyte chemotactic protein 1 (MCP-1) gene expression in vascular endothelial cells and that the regulation is at the transcriptional level. These observations led us to functionally analyze the 550-bp promoter region of the MCP-1-encoding gene to define the cis element responding to shear stress. The shear stress/luciferase assay on the deletion constructs revealed that a 38-bp segment (-53 to -90 bp relative to the transcription initiation site) containing two divergent phorbol ester "12-O-tetradecanoylphorbol 13-acetate" (TPA)-responsive elements (TRE) is critical for shear inducibility. Site-specific mutations on these two sites further demonstrated that the proximal one (TGACTCC) but not the distal one (TCACTCA) was shear-responsive. Shear inducibility was lost after the mutation or deletion of the proximal site. This molecular mechanism of shear inducibility of the MCP-1 gene was functional in both the epithelial-like HeLa cells and bovine aortic endothelial cells (BAEC). In a construct with four copies of the TRE consensus sequences TGACTACA followed by the rat prolactin minimal promoter and luciferase gene, shear stress induced the reporter activities by 35-fold and 7-fold in HeLa cells and BAEC, respectively. The application of shear stress on BAEC also induced a rapid and transient phosphorylation of mitogen-activated protein kinases. Pretreatment of BAEC with TPA attenuated the shear-induced mitogen-activated protein kinase phosphorylation, suggesting that shear stress and TPA share a similar signal transduction pathway in activating cells. The present study provides a molecular basis for the transient induction of MCP-1 gene by shear stress.

Animals↗
PubMed1995

Multiple cis-elements mediate shear stress-induced gene expression.

Fluid shear stress activates the expression of immediate early (IE) genes in vascular endothelial cells. The transcriptional regulation can be mediated through the shear stress-sensitive cis-acting elements at the 5' promoter regions of various IE genes such as the monocyte chemotactic protein-1 (MCP-1) gene. We linked wild-type and mutated MCP-1 promoters to the reporter gene luciferase and used such constructs to investigate the role of the phorbol ester TPA responsive element (TRE) in the shear-induced MCP-1 gene expression in vascular endothelial cells. Functional analysis showed that TGACTCC (a divergent TRE) located at nt -54 to -60 is necessary for shear-inducibility in bovine aortic endothelial cells (BAEC). The induction of the wild-type MCP-1 promoter construct by shear stress was attenuated by pretreating the cells with 1 microM dexamethasone or 1 microM retinoic acid 12 h before the shear stress experiments. The induction by shear stress reduced from 13-fold in the untreated cells to 7- and 3-folds in the dexamethasone- and retinoic acid-treated cells, respectively. These results demonstrate that the glucocorticoid receptor and retinoic acid receptor may interfere with the shear stress-activated AP-1/TRE. The reporter activity of HIV(LTR), which is a plasmid construct of the long terminal repeats of the human immunodeficiency virus and contains a kappa B enhancer element, was also activated by shear stress. The results of our investigations indicate that the shear stress-induced IE gene expression can be mediated through multiple cis-elements.

Animals↗
PubMed1995

Multiple brushings with immediate Riu's stain via flexible fibreoptic bronchoscopy without fluoroscopic guidance in the diagnosis of peripheral pulmonary tumours.

BACKGROUND: Accurate diagnosis of peripheral pulmonary lesions usually relies on fluoroscopic guided procedures. As fluoroscopy is not routinely available in many respiratory units, an approach not using fluoroscopy but with a high diagnostic yield is highly desirable. METHODS: Immediate cytological examination of multiple brushings using Riu's stain, a modified Wright's stain, was performed in 38 patients with peripheral pulmonary lesions not visible at bronchoscopy. The results were compared with the final diagnoses determined by histological examination or subsequent Papanicolaou staining of cytological specimens and clinical course. RESULTS: Of the 38 patients 29 were subsequently confirmed to have a malignant tumour. Our method provided a diagnosis of malignancy in 86% of these lesions. The accuracy (91%) and sensitivity (88%) were higher for lesions > 3 cm in diameter than for those of diameter < or = 3 cm (87% and 83%). There were no false positive results. The 29 lesions correctly diagnosed as malignant by Riu's stain required significantly fewer brushings (mean (SD) 3 (2)) than the nine benign lesions (5 (4)). CONCLUSIONS: This technique provides a high diagnostic yield, avoids the need for fluoroscopy, and is probably safer than percutaneous biopsy.

Adenocarcinoma, Bronchiolo-Alveolar↗
PubMed1995

Chromogranin A in human hypertension. Influence of heredity.

Multiple heritable traits are associated with essential (genetic) hypertension in humans. Because chromogranin A is increased in both human and rodent genetic hypertension, we examined the influence of heredity and blood pressure on chromogranin A in humans. In estimates derived from among- and within-pair variance in monozygotic versus dizygotic twins, plasma chromogranin A displayed significant (F15,18 = 2.93, P = .016) genetic variance (sigma 2 g), and its broad-sense heritability was high (h2B = 0.983). Plasma chromogranin A was increased in essential hypertension (99.9 +/- 6.7 versus 62.8 +/- 4.7 ng/mL, P < .001) but was influenced little by genetic risk for (family history of) hypertension (in normotensive or hypertensive subjects), by race, or by several antihypertensive therapies (angiotensin-converting enzyme inhibitor, diuretic, or beta-adrenergic antagonist). In normotensive subjects at genetic risk for essential hypertension, neither basal nor sympathoadrenal stress-evoked chromogranin A differed from values found in subjects not at risk. In established essential hypertension, plasma chromogranin A responses to adrenal medullary (insulin-evoked hypoglycemia) or sympathetic neuronal (dynamic exercise) activation were exaggerated, whereas responses to sympathoadrenal suppression (ganglionic blockade) were diminished, suggesting increased vesicular stores of chromogranin A and an adrenergic origin of the augmented chromogranin A expression in this disorder. We conclude that plasma chromogranin A displays substantial heritability and is increased in established essential hypertension. Its elevation in established hypertension is associated with evidence of increased vesicular stores of the protein and with adrenergic hyperactivity but is influenced little by customary antihypertensive therapies. However, the chromogranin A elevation is not evident early in the course of genetic hypertension.

Adrenal Medulla↗
PubMed1995

Immunoelectrophoretic differentiation of alpha-fetoprotein in disorders with elevated serum alpha-fetoprotein levels or during pregnancy.

Our study aims to make differential diagnosis by immunoelectrophoresis for some common conditions with elevated levels of serum alpha-fetoprotein (AFP). One hundred and nine cases with elevated AFP levels were included in this study: yolk sac tumor (n = 8), hepatocellular carcinoma (n = 26), gastric cancer (n = 12), chronic hepatitis (n = 27) and normal pregnancy (n = 36). Lectin agarose gel electrophoresis, antibody-affinity blotting, and immunoreaction were used to identify the specific patterns of AFP in the respective conditions. The results showed that there were three possible bands: L1, L2 and L3. Yolk sac tumor produced a prominent L2 band and a light L3 band. Hepatocellular carcinoma produced a prominent L1 band and a light L3 band. Gastric cancer produced only an L1 band. Chronic hepatitis had a light L1 band and a pronounced L3 band. In pregnancy, the AFP pattern is similar to that of hepatocellular carcinoma. Immunoelectrophoresis is a useful method facilitating the differentiation of AFP origins.

Biomarkers, Tumor↗
PubMed1995

Pulmonary echinococcosis--a case report.

Pulmonary echinococcosis is a rare disease in Taiwan and has never been reported in Taiwan's literatures. Here we report an overseas Chinese from Calcutta, India, presenting with recurrent hemoptysis and chest pain and with two big lung masses on chest roentgenogram. Rupture and spike fever ensured after fine needle aspiration of the cysts. Successful surgical intervention was obtained and echinococcal infection was documented pathologically.

Adult↗
PubMed1995

Microsomal triglyceride transfer protein (MTP) regulation in HepG2 cells: insulin negatively regulates MTP gene expression.

The microsomal triglyceride transfer protein (MTP) is a heterodimeric lipid transfer protein that is required for the assembly and secretion of apoB-containing lipoproteins. In this study, four factors that modulate lipid and lipoprotein metabolism were tested for their ability to regulate MTP levels in HepG2 cells. Of the factors tested, only insulin (> or = 10(-9) M), and high concentrations of glucose (> 30 mM) were found to decrease MTP large subunit mRNA levels. Oleate and glucagon had no effect on MTP mRNA levels. The insulin effect was dose- and time-dependent and was mediated through the insulin receptor. In addition, insulin also decreased protein disulfide isomerase (the small subunit of MTP) mRNA levels, although to a lesser extent. Due to the slow turnover rate of MTP (t1/2 = 4.4 days), short-term insulin treatment (24 h) did not change MTP activity levels, indicating that the regulation of MTP mRNA levels by insulin is unrelated to insulin's acute inhibition of apoB secretion in HepG2 cells. In summary, MTP mRNA levels are acutely regulated by insulin in HepG2 cells; however, sustained changes in MTP mRNA levels would be required to affect MTP protein levels.

Carrier Proteins↗
PubMed1995

Female genital tuberculosis: report of seven cases.

Seven cases of histologically proven genital tuberculosis (TB) encountered at the National Taiwan University Hospital in the past 16 years were reviewed. From a total of 54,576 gynecologic specimens submitted for pathologic examination, the occurrence of genital TB was 0.01%. Of these seven patients, one suffered from primary infertility and one from secondary infertility. The patient with primary infertility had been married for 29 years. The patient with secondary infertility underwent a tuboplasty due to bilateral hydrosalpinx. Genital TB was not diagnosed preoperatively in any of the seven cases. The preoperative diagnoses included: postmenopausal spotting, ovarian malignancy, cervicitis, ectopic pregnancy and hydrosalpinx with secondary infertility. This review suggests that genital TB is becoming rare in Taiwan. It is difficult to diagnose from clinical symptoms and is usually discovered on pathologic examination.

Adult↗
PubMed1994

Cloning and regulation of hamster microsomal triglyceride transfer protein. The regulation is independent from that of other hepatic and intestinal proteins which participate in the transport of fatty acids and triglycerides.

Microsomal triglyceride transfer protein (MTP) is a heterodimer consisting of protein disulfide isomerase and a unique large subunit. Recent studies showing that an absence of MTP is a cause of abetalipoproteinemia indicate that MTP is required for the assembly of very low density lipoproteins in the liver and chylomicrons in the intestine. In this study, complementary DNA encoding the large subunit of hamster MTP was cloned. The cDNA sequence was used to design a 50-base pair oligonucleotide probe for a solution hybridization assay to quantitate MTP large subunit mRNA levels in a study of MTP regulation in male Syrian Golden hamsters. In animals fed a low fat diet, MTP exhibited a proximal to distal gradient of expression in the intestine. MTP activity and large subunit mRNA levels in the liver were about 25 and 10% that found in the proximal intestine, respectively. To investigate the effect of diet on MTP, hamsters were maintained for 31 days on one of four diets: 1) control low fat, 2) high fat, 3) low fat, high sucrose, or 4) diet 1 followed by a 48-h fast. The high fat diet increased MTP large subunit mRNA levels in the liver and throughout the small and large intestine. A 55 and 126% increase was observed in the liver and intestine (duodenum and jejunum), respectively. A 40% increase of intestinal MTP protein mass was also observed. The high sucrose diet caused a significant 55% increase in hepatic MTP mRNA levels but did not significantly affect the intestinal mRNA levels. MTP mRNA levels were unchanged in response to fasting. A short term dietary study showed that intestinal MTP mRNA was up-regulated within 24 h after initiating a high fat diet. An acute hepatic response was not observed. The regulation of MTP mRNA levels by high fat diets was compared to that of the liver fatty acid binding protein (L-FABP) and apolipoprotein B (apoB). ApoB mRNA levels were not significantly affected by a high fat diet. Although L-FABP mRNA levels were increased in the liver and intestine, the onset of the changes did not parallel that of MTP. These results suggest that L-FABP, apoB, and MTP, three proteins which play important roles in the transport of fatty acids and triglyceride in the liver and intestine, are not coordinately regulated by diet in hamsters.

Amino Acid Sequence↗
PubMed1994

Human microsomal triglyceride transfer protein large subunit gene structure.

Microsomal triglyceride transfer protein (MTP) is a heterodimer consisting of the multifunctional enzyme protein disulfide isomerase and a unique, large 97-kDa subunit. MTP is required for the assembly and secretion of very low density lipoproteins and chylomicrons by the liver and intestine, respectively. In vitro, MTP catalyzes the transport of triglyceride, cholesteryl ester, and phosphatidylcholine between phospholipid surfaces. We have characterized the gene encoding the large subunit of human MTP. It contains 18 exons and spans approximately 55-60 kb. Fluorescent in situ hybridization localized this gene to band 4q24 of chromosome 4. A (CA)n repeat polymorphic marker, which may be useful for investigating a link between the MTP gene and genetic defects in lipid metabolism, was identified in intron 10. Sequence analysis of the 5' flanking region of the gene revealed potential sites which may bind transcriptional factors and control MTP expression.

Alleles↗
PubMed1994

Channel formation in planar lipid bilayers by a neurotoxic fragment of the beta-amyloid peptide.

Alzheimer's disease (AD) pathology is characterized by plaques, tangles, and neuronal cell loss. The main constituent of plaques is beta-amyloid peptide (A beta), a 39-42 residue peptide which has been linked to disruption of calcium homeostasis and neurotoxicity in vitro. We demonstrate that a neurotoxic fragment of A beta, A beta (25-35) spontaneously inserted into planar lipid membranes to form weakly selective, voltage dependent, ion-permeable channels. We suggest that channel formation may be involved in the pathogenesis of AD and that A beta (25-35) may be the active channel forming segment.

Amino Acid Sequence↗
PubMed1994

Ileal neobladder reconstruction after radical cystoprostatectomy.

To improve the outcome and patient acceptance of bladder substitution, five male patients underwent O-shaped ileal neobladder reconstruction, after radical cystoprostatectomy for invasive bladder cancer, with a mean follow-up of 11 months. With only 40 cm of ileal segment, an O-shaped neobladder was constructed after complete detubularization. Bilateral ureters were implanted using the Le Duc-Camey method. Six months after operation, all patients were totally continent during the day time, and one patient suffered from mild incontinence at night, which could be overcome by waking to void once or twice. The satisfactory continence levels are in agreement with a urodynamic study of the neobladder which showed a low pressure, high-capacity (mean, 456 mL) reservoir in the cystometric tracings. The mean maximal flow rate was 22.2 mL/sec, the mean residual urine was minimal (10 to 20 mL), the mean maximal urethral closing pressure was 74.4 cm H2O and the mean functional profile length was 2.9 cm. All renal units do not have neovesico-ureteral reflux. Two patients showed unilateral hydronephrosis which subsided later, one patient sustained bilateral hydronephrosis and died of jejunal perforation five months postoperatively. There were few perioperative complications and no patient expressed regret at having undergone the procedure. We consider bladder substitution to be the treatment of choice in male patients requiring radical cystoprostatectomy.

Aged↗