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Biomedical subjects

C S Li

Publications and source records attributed to C S Li.

At least 73 records · Page 4Linked to original sources
PubMed1995

Pharmacology of a selective cyclooxygenase-2 inhibitor, L-745,337: a novel nonsteroidal anti-inflammatory agent with an ulcerogenic sparing effect in rat and nonhuman primate stomach.

Recent studies have shown that there are two isoforms of cyclooxygenases. The constitutive form, cyclooxygenase 1 (COX-1), is believed to be involved in the maintenance of physiological functions. A second isoform, cyclooxygenase 2 (COX-2), has been shown to be induced in inflammation. In the present study, the pharmacology of a selective inhibitor of COX-2, L-745,337 (5-methanesulfonamido-6-(2,4-difluorothiophenyl)-1-indano ne), is described. L-745,337 has IC50 values of 23 +/- 8 nM and > 10 microM for the inhibition of prostaglandin E2 production in whole-cell assays for COX-2 and COX-1, respectively. This compound inhibited carrageenan-induced rat paw edema and rat paw hyperalgesia with ID50 values of 2.00 and 0.37 mg/kg, respectively. In an endotoxin-induced pyresis assay in the rat, L-745,337 significantly reversed the pyretic responses (ID50 = 3.75 mg/kg). L-745,337 did not cause visible gastric lesions in rats at up to 30 mg/kg (4 hr after dosing). In a fecal 51chromium (51Cr) excretion assay to detect gastrointestinal integrity in rats and primates, L-745,337 had no effect at doses up to 100 mg/kg (rat) or after chronic dosing at 20 mg/kg per day for 5 days (primates). In contrast, oral administration of indomethacin, diclofenac or flurbiprofen resulted in substantial increase in fecal 51Cr excretion and/or frank gastric ulceration (rats). L-745,337 significantly inhibited the prostaglandin E2 levels in the inflammatory exudates from the rat pleural cavity after injection with carrageenan but did not inhibit prostaglandin E2 levels in the stomach.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Characteristics of airborne microfungi in subtropical homes.

Because of high relative humidity (60-90%) and mild temperature (15-37 degrees C) all year round, fungi grow more quickly and easily in Taiwan, a subtropical country. Field evaluations of airborne fungi indoors and outdoors in two major types of cities (Taipei and Tai-Chi) in Taiwan were conducted during the fungus concentration peak season. Two-stage Andersen culture plate impactors were used to determine the number concentrations, genus and respirable fraction of indoor and outdoor fungi. The geometric mean concentrations of indoor and outdoor fungi in these two areas were found to be > 1000 colony forming units (CFU) m-3. In addition, Aspergillus, Penicillium, Cladosporium and yeast were observed to be dominant and their number concentrations in some homes exceeded 1000 CFU m-3. Moreover, the indoor and outdoor concentrations of the abundant fungi were found to be moderately correlated.

Air Microbiology↗
PubMed1994

Relationships of indoor/outdoor inhalable and respirable particles in domestic environments.

Simultaneous air monitoring inside and outside of three domestic environments in residential and industrial communities were conducted to evaluate infiltrations of outdoor aerosols into indoor environments, and indoor aerosol characteristics. The relationships of total (TSP), inhalable (< 10 microns, PM10) and respirable (< 2.5 microns, PM2.5) suspended particles were compared. It was found that the fractions of the indoor (20%) and outdoor (40%) PM10 levels exceeding 150 micrograms/m3 were substantial. In addition, it was indicated that indoor TSP and PM10 concentrations (R2 = 0.99) were well correlated with their corresponding outdoor levels. Moreover, there was a close relationship between the paired PM10 and PM2.5 levels indoors (R2 = 0.75) and outdoors (R2 = 0.83). The average indoor/outdoor (I/O) and median I/O ratios observed were 0.60. Therefore, steps to mitigate the situations with particulate levels above ambient particulate standards requires further study.

Air Pollutants↗
PubMed1994

Effective induction of pregnancy block by electrical stimulation of the mouse accessory olfactory bulb coincident with prolactin surges.

Electrical stimulation (0.33 Hz, 0.2 mA) applied bilaterally to the accessory olfactory bulb (AOB) of newly mated female mice revealed that stimulation for 4 h was sufficient to produce pregnancy block providing stimulation is given for two separate 2-h periods coincident with prolactin surges. Stimulation for two 1-h periods coincident with prolactin surges or two 2-h periods between prolactin surges was without effect. These results indicate that electrical stimulation of the AOB can faithfully reproduce pheromone-induced pregnancy block and support the view that prolactin is the hormone mainly responsible for the olfactory block to pregnancy.

Animals↗
PubMed1994

Factors associated with viremia and elevated transaminase levels in asymptomatic hepatitis D virus-infected risk groups.

To detect hepatitis D virus (HDV) RNA in asymptomatic HDV-infected risk groups, Northern blot hybridization was carried out using a strand-specific riboprobe. Univariate and multivariate analyses were carried out to evaluate factors associated with HDV viremia and elevated transaminase levels in these subjects. Two (15%) of 13 antibody to HDV (anti-HDV) -positive intravenous drug addicts, 15 (33%) of 45 anti-HDV positive prostitutes, and 6 (40%) of 15 anti-HDV positive brothel goers had detectable serum HDV RNA. Older age (> 31 years old) was negatively associated with HDV RNA (P < .04), while hepatitis B e antigen (HBeAg) was positively associated with it (P < .002) in univariate analysis. Only HBeAg was still significant in multivariate analysis (P < .05). Of the 76 asymptomatic anti-HDV positive case, 28 (37%) had mildly elevated serum ALT levels and only 5 (7%) had ALT levels more than twice normal (> 80 U/L). HBeAg (P < .05) and HDV RNA (P < .02) were two factors associated with ALT elevation in univariate analysis, and HDV RNA was the only significant factor in multivariate analysis (P < .005). In summary, active replication of HBV seemed to be of help for the assembly of HDV and viremia. However, active replication of HDV was associated mostly with mildly elevated ALT levels in these subjects. These cases may represent a particular group in the disease spectrum of HDV infection.

Adolescent↗
PubMed1994

Contrasting effects of identical nutrients given parenterally or enterally after 70% hepatectomy.

Based on clinical observations, we hypothesized that prolonged parenteral nutrition (in contrast to enteral nutrition) is detrimental after major hepatic resection. Male Sprague-Dawley rats (300 to 380 g) anesthetized with intraperitoneal sodium pentobarbital had 70% hepatic resection and jugular vein and gastrostomy catheterizations using aseptic techniques and were divided randomly into three groups: (1) total parenteral nutrition (TPN) (nutrients via central vein), (2) total enteral nutrition (TEN) (identical nutrients via gastrostomy), and (3) standard oral feeding (SOF) (chow and water ad libitum). Unused catheters were plugged. In the first set of experiments (n = 42), nutrient intake was formulated to approximate the nutritional intake of normal rats, 216 kcal/kg/d. Infusate was 15% glucose, 4.5% amino acids, electrolytes, trace minerals, vitamins, and 20% fat emulsion given half-strength the first day, three-fourths strength the second day, and full strength thereafter. On postoperative day 7, surviving rats were killed. Mortality prior to day 7 was very high (68%) in the TPN group and low in the TEN (9%) and SOF (9%) groups (p < 0.005). Among survivors, the serum albumin level was lowest (p < 0.002) and serum bilirubin level (p < 0.025) and wet weight of regenerated liver (p < 0.002) highest in the TPN group. However, the livers in TPN rats appeared pale and were found to be abnormal histologically with markedly diminished glycogen and amphophylic hepatocyte cytoplasm, and their spleens were enlarged (by a factor of two). The high mortality of TPN rats was seen whether the fat emulsion was given as a bolus daily, continuously as part of the infusate, or not included as part of the TPN regimen. In the next series (n = 70), nutrient concentrations, volumes, and rates of infusion were varied. There was a high correlation between caloric (r2 = 0.831, p < 0.0006), glucose (r2 = 0.598, p < 0.02), and amino acid (r2 = 0.619, p < 0.03) intakes and mortality in the TPN group: at 140 kcal/kg/d, none died; at 178 kcal/kg/d, 50% to 62% died; and at 230 kcal/kg/d, 80% died. No TEN rat died. In conclusion, 70% hepatectomized rats fed enterally with nutrients approximating the intake of normal rats do well and survive. In sharp contrast, mortality is very high when identical nutrients are infused parenterally. By reducing the levels of nutrients given parenterally, survival improves significantly.

Animals↗
PubMed1994

L-745,337: a selective inhibitor of cyclooxygenase-2 elicits antinociception but not gastric ulceration in rats.

L-745,337 [5-methanesulphonamido-6-(2,4-difluorothiophenyl)-1-indan one] a selective cyclooxygenase-2 inhibitor reversed hyperalgesia induced by carrageenan in rats without causing gastric ulceration at doses 100 times those causing antinociception. In contrast, piroxicam and indomethacin produced ulcerations at antinociceptive doses. These findings demonstrate that L-745,337 possesses antinociceptive activity but has a reduced liability for gastric ulceration.

Analgesics↗
PubMed1994

Studies on atrophic change of soleus muscle and its countermeasures in suspended rat.

In the environment of microgravity, the disused atrophy of skeletal muscle, especially leg's muscle, would occur. The three purposes of this study were: 1. To observe the dynamic changes of disused atrophy of skeletal muscle under simulated weightlessness; 2. To approach the mechanism of disused atrophy of muscle; 3. To approach the countermeasures for reducing the degree of atrophy of muscle.

Animals↗
PubMed1994

Peritoneal equilibration test in Chinese patients.

Since the introduction of the peritoneal equilibration test (PET) by Twardowski in 1987, it became a widely accepted test that provided useful prognostic information on continuous ambulatory peritoneal dialysis (CAPD). It had been shown to be a readily reproducible test if the standard procedure was followed. Although there was wide interpersonal difference in the test results, the mean and range (and standard deviation, SD) were remarkably similar as suggested by Davies et al. in 1993 (3). We had performed PET on our CAPD patients for a few years, and all along we used the reference range established by Twardowski to classify our patients into High, High average, Low average, and Low transporters because no reference range had ever been established in Chinese. The aim of this study was to define the normal mean and range of the PET results in Chinese CAPD patients. We analyzed 100 PET results from 100 Chinese CAPD patients. The mean +/- (SD) of the ratio of dialysate/plasma of creatinine and glucose at four-hour dwell times were 0.71 (0.15) and 0.37 (0.12), respectively. There was a significant difference in the dialysate/plasma ratio of creatinine (p < 0.01) while that of glucose was similar when compared with those found by Twardowski. There was no difference in the solute transfer in diabetic and nondiabetic patients. We concluded that the creatinine clearance of the peritoneal membrane in Chinese CAPD patients was higher than the previously reported result in North American patients.

Adult↗
PubMed1994

[Changes of cardiac function and hemodynamics in peripartum period].

Doppler's echocardiography was used to measure the changes of cardiac function and hemodynamics in peripartum period of 30 healthy women. The results showed that heart rate, body weight, body surface area, left ventricular mass (LVM), stroke volume (SV), cardiac output (CO), ejection fraction (EF), fractional shortening (delta D%), diastolic dimension (Dd), end-diastolic volume (EDV) and A/E ratio were significantly lowered within the first few postpartum days. However, the mean blood pressure (MBP) and systemic vascular resistance (SVR) were markedly increased (P < 0.01) in contrast to that of antepartum. Aorta diastolic dimension (AODd), aorta systolic dimension (AODs), maximum velocity (Vmax) and velocity time integral (VTI) were significantly different between before and after delivery. It may result from eliminated weight load, decreased blood volume load, and low circulating estrogen and progestogen levels and reduced physiological effects. It showed a great adaptability of cardiovascular system in healthy women to physiological load.

Adult↗
PubMed1993

Effects of various neuroactive substances on single-unit activities of hypothalamic arcuate neurons in brain slices.

Extracellular single-unit activities of 288 dorsomedial/ventrolateral hypothalamic arcuate (ARC) neurons were studied electrophysiologically in brain slices in vitro. We tested the effects of several neuroactive substances plus some of their analogs in this study. Among them, baclofen, a GABAb-receptor agonist, inhibited 95.6% of ARC neurons tested, although GABA itself was much less effective (23.8%). About half of baclofen's effect was blocked by phaclofen, a GABAB antagonist. Serotonin and dopamine also exhibited mostly inhibitory effects on responsive ARC neurons (80 and 78.4%, respectively), although more than half ARC neurons tested (53.3% of 169) were not responsive to dopamine. Neither ketanserin, a 5-HT2, nor domperidone, a D2 receptor antagonist, had much effect on blocking the actions of 5-HT or DA. Histamine and carbachol excited 67.4% and 52.2% of ARC neurons tested, respectively. Moreover, their effects were completely blocked by pyrilamine, a H1, and atropine, a muscarinic receptor antagonist, respectively. Ranitidine, a H2 receptor antagonist, however, was less effective. Norepinephrine had about equal number of excitation (33.3%) and inhibition (38.5%) on ARC neurons. Cholecystokinin-octapeptide sulphate (CCK-8S), a neuropeptide tested exerted potent excitatory effects on ARC neurons (62.8% of 137). In summary, ARC neurons in a more localized region aiming at the tuberoinfundibular dopaminergic neurons were selected in this study. Their responses to many agents and the implications on the regulation of prolactin secretion were discussed.

Animals↗
PubMed1993

Coordinate transformations in the representation of spatial information.

Coordinate transformations are an essential aspect of behavior. They are required because sensory information is coded in the coordinates of the sensory epithelia (e.g. retina, skin) and must be transformed to the coordinates of muscles for movement. In this review we will concentrate on recent studies of visual-motor transformations. The studies show that representations of space are distributed, being specified in the activity of many cells rather than in the activity of individual cells. Furthermore, these distributed representations appear to be derived by a specific operation, which systematically combines visual signals with eye and head position signals.

Animals↗
PubMed1993

Occupational exposure to 4,4'-bipyridyl vapor and aerosol during paraquat manufacturing.

The mass concentrations of both vapor and aerosol phases of 4,4'-bipyridyl were determined by a glass fiber filter and an XAD-2 tube in a paraquat factory. The size distributions of 4,4'-bipyridyl aerosols and particles < 10 microns were measured by a six-stage cascade impactor. The mass concentrations of 4,4'-bipyridyl aerosols were in the range of 81.9 to 159.9 mg/m3 with an average 4,4'-bipyridyl vapor mass concentration of 3.1 mg/m3 at the top of the open tank. On the average, the mass ratio of vapor phase to aerosol phase of 4,4'-bipyridyl was 0.025. Therefore, the aerosol phase is the major form of 4,4'-bipyridyl exposure to the workers in this environment. From the 4,4'-bipyridyl concentrations measured by the sampling systems of an XAD-2 tube alone and a filter followed by an XAD-2 tube, the 4,4'-bipyridyl aerosol collection efficiency of the XAD-2 tube was found to be approximately 50%. The average mass concentrations of less than 10 microns aerosols and 4,4'-bipyridyl aerosol in the occupational environment were 0.42 mg/m3 and 1.26 micrograms/m3, respectively. The mass median aerodynamic diameter (geometric standard deviation) of particles < 10 microns and 4,4'-bipyridyl aerosol are 3.50 microns (2.35) and 3.47 microns (2.58), respectively. The major mass fraction of 4,4'-bipyridyl aerosol occurred in the 3.3-5.8 microns size range. The enclosure efficiencies of a hood cover attached to a suction tube were found to be 88% and 82% for both aerosol and vapor phases of 4,4'-bipyridyl, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Air Pollutants, Occupational↗
PubMed1993

Physical and chemical composition of hospital waste.

For selecting the most efficient treatment method of hospital waste, the composition analysis is generally considered to be the fundamental information. Currently, there are few studies regarding the characteristics of hospital waste. This study evaluated the physical and elemental composition of the hospital waste at the National Taiwan University Hospital (NTUH). The results should help us design an incinerator for the treatment of infectious waste, plastic syringes, pathological waste, and kitchen waste. During the study period, the estimated daily waste generation rate at NTUH was 4,600 kg/day, which consisted of 4,100 kg/day noninfectious refuse, 340 kg/day infectious waste, 70 kg/day kitchen waste, 50 kg/day pathological waste, and 40 kg/day plastic syringes. The NTUH waste consisted of 99.02% combustible wastes and 0.97% noncombustible wastes by mass. The combustible wastes constituted paper (16.17%), textiles (9.77%), cardboard, wood, and leaves (1.12%), food waste (21.51%), and plastics (50.45%). The noncombustible waste included 0.40% metal and 0.57% glass. Furthermore, the analysis indicated that the wastes contained 38% moisture, 4% ashes, and 58% solid with an average heat value of 3,400 kcal/kg. From the elemental analysis, the dominant elements were found to be carbon (34%) and oxygen (15%).

Hospitals, University↗
PubMed1993

Clinical profile of Chinese patients with systemic lupus erythematosus.

In the 9-year period between 1982 and 1991, 137 patients attending a medical clinic of Queen Elizabeth Hospital, Hong Kong, were diagnosed as having systemic lupus erythematosus according to the American Rheumatism Association's criteria for classification. The female-to-male ratio was 16 to 1. Commonly the onset age was between 20 and 40. Malar rash (70%), arthritis (70.8%) and nephropathy (69.3%) were the most common manifestations. Anti-nuclear factor was invariably positive, whereas anti-extractable nuclear antigen antibodies were positive in varying degrees--Sm 12.7%, nRNP 28.8%, Ro 60.2%, La 8.4%. There were 22 deaths during the follow-up period, two-thirds from active diseases. Gastro-intestinal bleeding and opportunistic infection were common complications.

Adolescent↗