Biomedical subjects

M C Lin

Publications and source records attributed to M C Lin.

At least 109 records · Page 6Linked to original sources

PubMed1999

Increased absolute number but not proportion of gamma/delta T-lymphocytes in the bronchoalveolar lavage fluid of patients with active pulmonary tuberculosis.

SETTING: The proportions and absolute cell count of gamma/delta T-lymphocytes in the peripheral blood of patients with pulmonary tuberculosis (PTB) remains controversial. Since PTB is an infections airway disease, bronchoalveolar T-lymphocytes should be a better indicator of local immune T-cell reaction after TB infection than peripheral blood T-lymphocytes. OBJECTIVE: To quantitate the absolute cell count and proportions of gamma/delta T-lymphocytes in the bronchoalveolar lavage fluid (BALF) of patients with active PTB. DESIGN: Bronchoalveolar lavage (BAL) and analysis of lymphocytes in the BALF was performed in 25 patients with active PTB and 16 normal controls. All of the patients were negative for HIV infection and none was immunocompromised. BALF and blood were prepared for cell differential count and flow cytometry analysis using monoclonal antibodies CD3, CD4, CD8, CD25, HLA-DR and gamma/delta as well as alpha/beta T-lymphocyte receptors. RESULTS: The number of cells per volume of recovered BALF was significantly higher in the patients with active PTB than in normal controls. BALF from active PTB patients also showed increased percentage of lymphocytes and neutrophils. The absolute number of total lymphocytes, CD3+ lymphocytes and CD3+ gamma/delta T-lymphocytes were significantly higher in the BALF, but not in the blood, of patients with TB, however, the proportions of CD3+ gamma/delta T-lymphocytes in BALF of patients with TB was comparable to that of normal controls. gamma/delta T-lymphocytes in the BALF rarely expressed CD4, CD25, and HLA-DR in both groups. CONCLUSION: These results suggest that gamma/delta T-lymphocytes are not the major subpopulation of CD3+ lymphocytes in the BALF that react to mycobacterial infection in the patients with clinically established active TB.

Adult↗

PubMed1999

Pulmonary mechanics in patients with prolonged mechanical ventilation requiring tracheostomy.

This study was performed to assess the changes in pulmonary mechanics before and after tracheostomy in patients with prolonged mechanical ventilation and to detect pre-tracheostomy physiologic factors that predict the outcome of weaning from mechanical ventilation. Pulmonary mechanics were recorded before and after tracheostomy in 20 patients. Work of breathing, mean airway resistance and pressure/time product showed no significant differences after tracheostomy. Peak inspiratory pressure was significantly reduced (pre 33.4 +/- 11.8 vs post 28.6 +/- 9.2 mmHg). There was no difference in age or duration of mechanical ventilation between two different groups according to the outcome (weaned and not-weaned). Pre-tracheostomy intrinsic positive end expiratory pressure (PEEPi) was significantly lower in the weaned group (1.1 +/- 1.6 vs 2.7 +/- 1.4 mmHg). A significant difference was also found in pre-tracheostomy compliance (Cstatic) (47.3 +/- 36.9 vs 28.8 +/- 16.5 ml/cmH2O). We concluded that tracheostomy changed pulmonary mechanics very little except for a fall in peak inspiratory pressure. Patients who had better underlying lung mechanics (higher Cstatic and lower PEEPi) had better chances of weaning from mechanical ventilation after tracheostomy.

Adult↗

PubMed1999

Comparison of indoor allergens, allergic scores, and demographic data in Taiwanese adults with asthma or allergic rhinitis, or both.

We examined the relationships between exposure to different indoor allergens and demographic factors in 515 adult Taiwanese patients with allergic diseases such as asthma and rhinitis. Patients who had positive screening results on an immunoglobulin E (IgE) test were recruited from the outpatient clinics of Chang Gung Memorial Hospital. Patients were divided into the following three groups: asthma (n = 332), combined asthma and allergic rhinitis (n = 165), and allergic rhinitis (n = 18). Serum samples were analyzed for IgE by enzyme-linked immunosorbent assay. Significantly elevated titer of dust mite-specific IgE were found in all three groups, with markedly higher levels in the combined asthma and allergic rhinitis group (p < 0.05). Allergen scores were significantly related to the demographic variables of older age (> or = 65 years), female gender, and spring season, with significantly lower scores (p < 0.05). No significant difference in allergen scores was found among cigarette smoking subjects and subjects from residential areas. Multiple linear regression analysis revealed significant allergic contributors to be, in order of importance, age, gender, and atopic disease category. We conclude that mite allergen exposure is the most significant factor associated with asthma and/or allergic rhinitis in Taiwan. Younger subjects and males had a higher rate of asthma and/or allergic rhinitis.

Adolescent↗

PubMed1999

Measurement of post-lens tear thickness.

PURPOSE: A method to measure the tear film beneath a soft contact lens, referred to as post-lens tear thickness (PLTT), would have many applications to contact lens research. In this study a noninvasive technique for measuring the PLTT is presented. METHODS: The feasibility of measuring the tear layer by optical pachometry was first assessed using a model eye. The baseline corneal thickness (B) of both eyes of 21 subjects was measured, etafilcon-A ionic disposable soft contact lenses (58% water) were inserted, and the total thickness (T) of the cornea, contact lens, and PLTT were measured. After the pachometry readings the lenses were removed and their center thickness (C) determined. The PLTT was calculated using the equation: PLTT = T-(B+C). Two sets of measurements of T were performed at 15 and 25 minutes after lens insertion. The entire procedure was repeated at a second visit. RESULTS: The pachometry measurements of the small aqueous reservoir between the model eye and the lens closely matched those obtained by direct microscopic measurement. For human PLTT, the mean values (and 95% confidence intervals) for right eyes on visits 1 and 2 were 11 (8, 13) and 12 (10, 15) microm, respectively, and for left eyes were 12 (10, 15) and 11 microm (8, 14) microm, respectively. CONCLUSIONS: It is possible to measure the post-lens tear thickness using optical pachometry. The variability between repeated measurements suggests that with careful sample size planning, the technique is sufficiently precise to be useful in group assessments of PLTT.

Adolescent↗

PubMed1999

Tracheal neurilemmoma mimicking bronchial asthma--a dilemma of difficult diagnosis: case report.

Tracheal tumors are often overlooked as a cause of pulmonary symptoms until they reach an advanced state. They are often presented with a prolonged cough and shortness of breath. Most tracheal tumors in adults are cancerous (80% to 90%). Benign tracheal tumors are rare in adult patients. A case history is presented of a 19-year-old patient with a rare tracheal neurilemmoma. He was treated as having bronchial asthma initially, but his signs and symptoms did not improve with traditional therapy. The possibility of the presence of an upper airway obstruction was not raised until the typical "inspiratory tubular sound" was heard. Flow-volume loop testing, bronchoscopy, and three-dimensional computed tomography (3-D CT) confirmed the diagnosis of upper airway obstruction caused by a tracheal tumor. Therefore, surgical intervention rather than bronchoscopic removal was performed without difficulty. The patient was leading a stable life 8 months after a surgical resection. The presence of an upper airway obstruction can be proven by flow-volume loop testing and 3-D CT. Further pathologic confirmation can be accomplished by bronchoscopy. High suspicion of an upper airway obstruction such as a tracheal lesion should be raised when bronchial asthma patients fail to respond to conventional treatment.

Adult↗

PubMed1998

Transcriptional regulation of BMP-4 in the Xenopus embryo: analysis of genomic BMP-4 and its promoter.

Recent experiments in the Xenopus embryo suggest that proper regulation of BMP-4 signaling is critical to the dorsal ventral specification of both mesoderm and ectoderm. Regulation of BMP-4 signaling is known to occur extracellularly by direct binding with chordin, noggin, and follistatin, and intracellularly through the antagonistic signal interaction with dorsalizing TGF-beta family member activin. However, tight repressional regulation of BMP transcription may also be required to sustain the dorsal and neural status of the induced cells. Here we demonstrate that the dominant negative mutant of the BMP receptor (DN-BR) or the BMP-4 antagonizers, chordin and noggin, negatively regulate BMP-4 transcription in animal cap explants. We suggest that repression of BMP-4 transcription is important in the maintenance of dorsal fate and that continuous input of BMP-4 signaling is required to sustain the expression of BMP-4 transcription in the maintenance of epidermal/ventral fate. Consistent with this postulation, we found that the promoter region of the isolated BMP-4 genomic DNA includes several consensus binding sites for transcriptional regulators functioning under BMP-4 signaling such as GATA binding and ventralizing homeobox genes. In a functional assay we found that the GATA binding and ventral homeobox proteins can positively modulate BMP-4 promoter activity. We also observed that DN-BR decreases BMP-4 promoter activity. This was likely due to a repression of the above-mentioned transcription factors. The significance of these observations to embryonic patterning is discussed.

Animals↗

PubMed1998

Effects of magnets with non-unit magnetic permeability on an elliptically polarizing undulator.

This study employs the three-dimensional magnetostatic code TOSCA to assess numerically the effects of NdFeB magnets with non-unit magnetic permeability on an elliptically polarizing undulator. A reduction of a few percent of the on-axis magnetic field strength is predicted. In addition, a deviation of +/-100 G cm uncompensated dipole steering is predicted in a phase shift of 180 degrees for the elliptically polarizing undulator EPU5.6 (having a period length of 56 mm) at the minimum gap of 18 mm, which is related primarily to the configuration of the device end scheme. Results presented herein demonstrate that implementing an active compensation mechanism is a prerequisite for minimizing the orbit distortion during phase-shift adjustment, particularly for operating such a polarizing undulator in a third-generation machine having a median energy similar to that of the 1.5 GeV storage ring at SRRC.

Journal Article↗

PubMed1998

An SRRC elliptically polarizing undulator prototype to examine mechanical design feasibility and magnetic field performance.

In this work, a 1 m long Sasaki-type elliptically polarizing undulator (EPU) prototype with 5.6 cm period length is used to examine the mechanical design feasibility as well as magnetic field performance. The magnetic field characteristics of the EPU5.6 prototype at various phase shifts and gap motion are described. The field errors from mechanical tolerances, magnet block errors, end field effects and phase/gap motion effects are analysed. The procedures related to correcting the field with the block position tuning, iron shimming and the trim blocks at both ends are outlined.

Journal Article↗

PubMed1998

Spectral properties of the polarizing devices at SRRC.

User requirements at SRRC for high-brilliance synchrotron light in various polarization states will be fulfilled in the near future by the implementation of two types of polarizing devices in the storage ring: the elliptically polarizing undulator (EPU) and the elliptically polarized bending magnet (EPBM). The EPBM provides a broadband polarized spectrum up to the soft X-ray range with rapid alternation of the left and right helicities. The EPU, which has a magnetic period length of 56 mm, generates a high-brilliance harmonic spectral intensity in the range 80-1400 eV with abundant polarization states, including circular ones. The optimal merit flux is evaluated for the operation of these two polarizing devices in the SRRC 1.5 GeV storage ring. The available polarization states are also surveyed.

Journal Article↗

PubMed1998

Indoor environmental risk factors and childhood asthma: a case-control study in a subtropical area.

This study examined the relation between indoor environmental factors and childhood asthma in a subtropical area. A hospital-based case-control study was performed in Kaohsiung, Taiwan, between July of 1995 and June of 1996. Eighty-six children seen in the out-patient clinic of our university hospital and who had a first-time diagnosis of asthma made by a pediatrician were the test group; 86 control subjects were selected from children attending the Childhood Orthopaedic Clinic in the same hospital and who had no previous diagnosis of asthma or asthma symptoms and no history of physician confirmed atopic diseases. The control subjects were matched with test case children on the basis of gender and age. Information was obtained from parents using a structured questionnaire. Of the many indoor environmental factors included in this study, only home dampness showed an association with asthma (adjusted odds ratio=1.77; 95% confidence intervals, 1.24-2.53). We conclude that dampness in the home is a new public health risk factor related to asthma in subtropical areas.

Adolescent↗

PubMed1998

Enhanced expression of hepatic acyl-coenzyme A synthetase and microsomal triglyceride transfer protein messenger RNAs in the obese and hypertriglyceridemic rat with visceral fat accumulation.

The liver plays a central role in lipoprotein metabolism. In particular, very-low density lipoprotein (VLDL) is assembled in the hepatocytes and secreted into the blood circulation. The VLDL is then catabolized to low-density lipoprotein by lipoprotein lipase and hepatic triglyceride lipase. Obese subjects, especially those with visceral fat accumulation, are frequently associated with hyperlipidemia, non-insulin-dependent diabetes mellitus (NIDDM), and hypertension. The mechanism of hyperlipidemia in visceral fat obesity has not yet been elucidated. Otsuka Long-Evans Tokushima Fatty (OLETF) rat is an animal model of NIDDM, characterized by obesity with visceral fat accumulation, hyperlipidemia, and late-onset insulin resistance. To elucidate the mechanism of hyperlipidemia observed in OLETF rats, we focused on the production of VLDL by the liver and investigated hepatic messenger RNA (mRNA) levels of microsomal triglyceride transfer protein (MTP), acyl-coenzyme A synthetase (ACS), and apolipoprotein B (apo B), which play important roles in VLDL synthesis and secretion. In 6-week-old OLETF rats, in which insulin resistance had not been manifested, visceral fat weight was already higher and portal free fatty acid (FFA) and VLDL-triglyceride levels were elevated compared with the control rats. Hepatic ACS activity and mRNA levels, and MTP mRNA levels were also increased in OLETF rats, whereas apo B mRNA levels were similar; these results suggest that the enhanced expression of both ACS and MTP genes associated with visceral fat accumulation before developing insulin resistance may be involved in the pathogenesis of hyperlipidemia in obese animal models with NIDDM.

Adipose Tissue↗

PubMed1998

The incidence of school-related injuries among adolescents in Kaohsiung, Taiwan.

OBJECTIVES: To determine the incidence of nonfatal school-related injuries in adolescent schoolchildren. DESIGN: Nurses completed a Student Accident Report Form (SARF) on all injuries in schools meeting standardized criteria from September 1995 to June 1996. SETTING: Six junior high schools in Kaohsiung city, Taiwan. SUBJECTS: 13,335 adolescents aged 13-15 in six schools. RESULTS: A total of 3,640 injuries were reported among the city's 13,335 students, for an overall injury rate of 27.3 injuries/100 student years. Injury rates were higher for boys than for girls at all grade levels. The seventh-grade students had the highest incidence rate. Injuries not involving other students accounted for nearly 64% of all injuries. Injuries occurring on the playground/gymnasium and classroom were the two most common types and were more than twice as frequent as injuries occurring in the hall or stairs. Contusions, abrasions, and swelling were the most frequently reported types of injuries. The body sites most frequently injured were the extremities. When exposure time is taken into account, injury rates were higher in the unsupervised areas of the schools. CONCLUSIONS: School-related injury incidence among adolescents attending junior high school is higher than has been previously reported and should be recognized as a significant public health problem in Taiwan.

Accidents↗

PubMed1998

Oxygen, arterial blood gases and ventilation are unchanged during dialysis in patients receiving pressure support ventilation.

This study was undertaken to observe whether dialysis-induced alveolar hypoventilation and arterial hypoxaemia occur during bicarbonate haemodialysis in patients receiving partial mechanical support with pressure support ventilation. Nineteen patients admitted to the medical intensive care unit requiring mechanical ventilation and haemodialysis were enrolled. Arterial blood gas, white blood cell (WBC) count, minute ventilation, respiratory rate, breathing pattern and blood pressure were measured according to the following time schedule: pre-dialysis (time 0), and at 15, 30, 60, 120, 180, 240 min thereafter. Results showed that, with the use of cuprammonium dialyser, the WBC count dropped immediately and reached the nadir 15 min after haemodialysis. Thereafter, it recovered and overshot the pre-dialysis values until the end of dialysis. The bicarbonate dialysate indeed resulted in rapid and significant metabolic alkalosis. However, no decrease of PaO2 occurred throughout haemodialysis. The tidal volume, minute ventilation and breathing pattern remained stable during haemodialysis. We conclude that neither dialysis-induced alveolar hypoventilation nor arterial hypoxaemia developed during bicarbonate dialysis in patients mechanically ventilated with the pressure support ventilation.

Adult↗

PubMed1998

Prospective randomized trial of systemic antibiotics in patients undergoing liver resection.

BACKGROUND: Systemic antibiotics are administered frequently after hepatectomy to prevent infective complications, but their effectiveness is uncertain. METHODS: A total of 127 patients with liver tumours were prospectively randomized into two groups after hepatectomy: in group 1 (62 patients) no antibiotics were given until the appearance of infective complications; in group 2 (65 patients) intravenous cephazolin 1 g every 6 h and gentamicin 80 mg every 8 h were given for 7 days. On the day before surgery all patients received bowel preparation by clear liquid diet and oral antibiotics (neomycin 1 g and erythromycin 1 g, given together in three doses). RESULTS: The infective complication rate was 23 per cent in both groups (P = 0.95). The hospital costs were higher in group 2 (P < 0.001). Of the group 1 patients, 51 (82 per cent) did not require antibiotic treatment. No patient in either group died after hepatectomy. CONCLUSION: Postoperative systemic antibiotics cannot prevent infective complications, and their routine use after hepatectomy is unnecessary and costly. The use of antibiotics should be delayed until infective complications and persistent septic symptoms occur.

Antibiotic Prophylaxis↗

PubMed1998

Peroxynitrite induces apoptosis of HL-60 cells by activation of a caspase-3 family protease.

Apoptosis is an active process critical for the homeostasis of organisms. Enzymes of the caspase family are responsible for executing this process. We have previously shown that peroxynitrite (ONOO-), a biological product generated from the interaction of nitric oxide and superoxide, induces apoptosis of HL-60 cells. The aim of this study was to elucidate the mechanisms involved in the execution process of peroxynitrite-induced apoptosis. Proteolytic cleavage of poly(ADP-ribose) polymerase, an indication of caspase-3 family protease activation and an early biochemical event accompanying apoptosis, was observed in a time-dependent manner during peroxynitrite-induced apoptosis of HL-60 cells. Activation of caspase-3 during peroxynitrite-induced apoptosis was substantiated by monitoring proteolysis of the caspase-3 proenzyme and by measuring caspase-3 activity with a fluorogenic substrate. Furthermore, pretreatment of HL-60 cells with N-acetyl-Asp-Glu-Val-Asp-aldehyde, a specific inhibitor of caspase-3, but not N-acetyl-Tyr-Val-Ala-Asp-aldehyde, a specific inhibitor of caspase-1, decreased peroxynitrite-induced apoptosis. These results suggest that the activation of a caspase-3 family protease is essential for initiating the execution process of peroxynitrite-induced apoptosis of HL-60 cells.

Apoptosis↗

PubMed1998

Diaphragm sarcolemmal injury is induced by sepsis and alleviated by nitric oxide synthase inhibition.

Endotoxemia is associated with impaired diaphragm contractility, and increased nitric oxide (NO) production has recently been implicated in this phenomenon. However, the precise nature of sepsis-related alterations in diaphragm myofiber function remains unclear. We tested the hypothesis that enhanced NO synthesis during sepsis produces diaphragm sarcolemmal injury with attendant abnormalities of myofiber membrane electrophysiology. Two different rat sepsis models were employed: acute (4 h) intraarterial endotoxin (LPS; 20 mg/kg) and subacute (24 h) peritonitis induced by cecal ligation and perforation (CLP). Diaphragm damage occurred after both LPS and CLP, as indicated by hyperpermeability of myofibers to a low molecular weight tracer dye, which is normally unable to penetrate the sarcolemma. Sarcolemmal injury was significantly correlated with reductions in the resting membrane potential (Em) of single diaphragm myofibers. Western analysis revealed increased diaphragmatic expression of the inducible isoform of NO synthase (iNOS) after LPS and CLP. An inhibitor of NOS activity, LNMMA, significantly decreased morphologic as well as electrophysiologic signs of myofiber membrane injury and dysfunction. Therefore, we conclude that both acute endotoxemia and subacute peritonitis models of sepsis lead to significant sarcolemmal damage and altered Em in diaphragm myofibers. These changes appear to be mediated, at least in part, through the pathway of increased nitric oxide production.

Animals↗

PubMed1998

Childhood asthma and the indoor environment in a subtropical area.

STUDY OBJECTIVES: The objective of this study is to examine the relationship between indoor environmental factors and childhood asthma in a subtropical area. DESIGN: A case-control study was performed using participants of a prevalence survey that included 165 schoolchildren with asthma and 165 age- and gender-matched control subjects. SETTING: The study was confined to 4,164 schoolchildren aged 6 to 12 years attending eight primary schools in Kaohsiung County rural municipalities who participated in a prevalence study concerning the health effects of the indoor environment. PARTICIPANTS: Cases (n=165) were defined as children with current asthma confirmed by a physician. Control subjects (n=165) were selected from the same school and class and matched for age and gender, and they did not have a previous diagnosis of asthma, history of physician-confirmed atopic diseases, persistent wheezing, cough, or phlegm, or reported chest illness, pneumonia, or bronchitis. MEASUREMENTS AND RESULTS: Information regarding the home environment was obtained using a structured written questionnaire, completed by the parents of the children. Of the many indoor environmental factors included in this study, only home dampness showed an association with asthma (odds ratio=2.65). CONCLUSIONS: We conclude that dampness in the home is a new public health issue in subtropical areas.

Air Pollution, Indoor↗

PubMed1998

Arterial oxygenation is unchanged during hemodialysis in patients mechanically ventilated in assist-control mode.

Dialysis-induced hypoxemia can occur in spontaneously breathing renal failure patients but whether it occurs during bicarbonate hemodialysis in critically ill patients receiving mechanical ventilation in assist-control mode is not clear. Twenty-one patients admitted to the medical intensive care unit who required mechanical ventilation and hemodialysis with the use of a cuprammonium dialyzer were enrolled and 25 sessions of hemodialysis were performed. Arterial blood gas, white blood cell count, minute ventilation, respiratory rate, and blood pressure were measured before dialysis (time 0) and at 15, 30, 60, 120, 180, and 240 minutes thereafter. The white blood cell count dropped immediately and reached the nadir 15 minutes after hemodialysis began. Thereafter, it recovered and overshot the predialysis value at the end of dialysis. The serum HCO3- concentration increased progressively after dialysis began and resulted in significant metabolic alkalosis. The P (A-a)O2 was not aggravated and minute ventilation was not depressed by rapid metabolic alkalosis under mechanical ventilatory support. The PaO2 remained stable throughout hemodialysis. No significant hypoxemia occurred in groups of varying predialysis cardiopulmonary dysfunction. These findings suggest that in renal failure patients ventilated in assist-control mode, l) hypoventilation and accompanying hypoxemia did not occur during bicarbonate (35 mEq/L) dialysis, despite significant metabolic alkalosis; and 2) patients with higher Acute Physiologic and Chronic Health Evaluation (APACHE) III scores and P(A-a)O2 levels were not more prone to dialysis-induced hypoxemia.

Adult↗