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Biomedical subjects

Y C Wu

Publications and source records attributed to Y C Wu.

At least 145 records · Page 8Linked to original sources
PubMed1994

Vasorelaxing effect in rat thoracic aorta caused by laurotetanine isolated from Litsea cubeba Persoon.

The pharmacological effects of laurotetanine on rat isolated thoracic aorta were examined. The contraction of aortic rings caused by high potassium (60 mM) and cumulative concentrations of calcium (0.03-3 mM) was inhibited by 3-50 microM laurotetanine in a dose-dependent manner with an IC50 value of 19.8 +/- 3.6 microM (n = 6) in a 1 mM Ca2+ medium. The phenylephrine (3 microM)-induced contraction was also inhibited by laurotetranine. Its effect was more marked on the tonic contraction than on the phasic contraction and was not easily washed-out. On addition of laurotetanine during the tonic contraction, relaxation could also be observed. This relaxing effect was not antagonized by indomethacin (20 microM) and was still seen in denuded aorta or in the presence of nifedipine (1 microM). The caffeine (20 mM)-induced contraction was not affected by laurotetanine. cAMP and cGMP levels of aorta were not changed by laurotetanine. It is concluded that laurotetanine relaxed the rat thoracic aorta mainly by suppressing the Ca2+ influx through both voltage- and receptor-operated calcium channels.

Animals↗
PubMed1994

Predicting adolescent problem use of marijuana: development and testing of a Bayesian model.

This paper reports on the development and testing of a risk assessment index for problem marijuana use designed to guide teenagers through an extensive computer-based support system intended to help them improve marijuana-related behaviors. Bayesian decision theory, used as the basis of the index development process, offers the advantage of building the index on subjective judgments of experts and does not require a large empirical data base. The index was found to predict an independent panel's ratings of teenager risk, and predict the marijuana use of 10th graders using self-reports of their profiles in the 7th grade. Implications for future risk assessment developments are discussed.

Adolescent↗
PubMed1994

Human dermal papilla cells and outer root sheath cells: no follicular differentiation in nude mice and chicken embryos.

Human scalp specimens were incubated in 5 U/ml dispase solution at 4 degrees C overnight before the isolation of dermal papillae and follicle epithelium. This pretreatment not only facilitated the attachment and cell outgrowth of dermal papillae but also made it easier to pluck out hairs with intact follicle epithelium. The outer root sheath cells were released from the follicle epithelium and grown on a feeder layer of mitomycin C-treated human dermal fibroblasts. The subcultured outer root sheath cells were grown in a serum-free medium. When the mixtures of early-passage dermal papilla cells and outer root sheath cells were injected into the subcutis of nude mice, an epidermal cyst surrounded by layers of fibrous tissue was found in three weeks. No hair follicles were found when the mixtures were implanted onto the chorioallantoic membrane of nine-day-old chicken embryos. A keratinized mass lying on the chorionic epithelium with or without smaller similar masses in the chorioallantoic membrane was found in eight days. No hair follicle-like structure could be found. Possible factors contributing to the failure to undergo follicular differentiation in this study are discussed.

Animals↗
PubMed1994

Q fever in Taiwan.

BACKGROUND: Although Q fever, a rickettsial disease caused by Coxiella burnetii, is supposed to occur sporadically worldwide, there is only one case report of this disease in Taiwan. We examined the antibody of Q fever to evaluate the status of Q fever in Taiwan. METHODS: In total, 579 paired serum specimens of suspected febrile patients sent by several hospitals and sanitary stations to this Institute in 1991 and 1992 were tested according to the technique of indirect fluorescent antibody (IFA). RESULTS: In total 48 serologically acute Q fever cases were found, mostly from Tainan, Pingtung and Kaohsiung. There was only one female, and the age of most patients was 40-50 years. The high season is in June and July. CONCLUSIONS: The antibody titer of all 48 positive cases reached 1:320 or higher on the 13th day after onset of the disease. IFA as a diagnostic tool to detect acute and convalescent serum antibody titer is discussed.

Adult↗
PubMed1994

Disparate cytochemical characteristics and production of cytokines and prostaglandin E2 by human mononuclear phagocytes from the blood, lung, and peritoneal cavity.

The cytochemical characteristics and the production of tumor necrosis factor-alpha (TNF-alpha), interleukin-1 beta (IL-1 beta), and prostaglandin E2 (PGE2) by peritoneal macrophages were compared with those of blood monocytes and alveolar macrophages. The comparative percentages of mononuclear phagocytes positive for peroxidase were as follows: blood monocytes > peritoneal macrophages > alveolar macrophages. The comparative percentages of cells positive for nonspecific esterase were as follows: alveolar macrophages > peritoneal macrophages = blood monocytes. The intensity of staining for nonspecific esterase was highest in alveolar macrophages and lowest in blood monocytes. Constitutive release of TNF, IL-1 beta, and PGE2 was minimal by each cell type. Lipopolysaccharide-stimulated TNF production by alveolar macrophages was approximately five times greater than that of monocytes and 10 times greater than that of peritoneal macrophages. By contrast, lipopolysaccharide-stimulated blood monocytes produced significantly more IL-1 beta than did peritoneal or alveolar macrophages. Lipopolysaccharide-stimulated production of PGE2 by peritoneal macrophages was significantly less than that of alveolar macrophages or blood monocytes. Thus peritoneal macrophages release relatively low levels of IL-1 beta, TNF, and PGE2 in response to lipopolysaccharide. Peritoneal and alveolar macrophages differ with respect to both cytochemical characteristics and lipopolysaccharide-stimulated production of TNF and PGE2 but are similar in their limited capacity to produce IL-1 beta.

Adult↗
PubMed1993

The relaxant actions on guinea-pig trachealis of atherosperminine isolated from Fissistigma glaucescens.

The pharmacological activity of atherosperminine, isolated from Fissistigma glaucescens, was determined in isolated guinea-pig trachealis. Atherosperminine (25-100 microM) and theophylline (10-1000 microM) both inhibited the contractile response caused by carbachol, prostaglandin F2 alpha (PGF2 alpha), U46619 (thromboxane A2 analogue), leukotriene C4 (LTC4) and Ca2+ (in the presence of 120 mM KCl) in a concentration-dependent manner. The inhibition was characterized by a rightwards shift of the concentration-response curves with suppression of the maximal contraction. Propranolol (1 microM), glibenclamide (10 microM) and removal of tracheal epithelium did not modify the relaxant action of atherosperminine. Atherosperminine (25 and 50 microM) caused a 2.4- and 5.0-fold, respectively, potentiation of the action of forskolin to cause tracheal relaxation but did not potentiate the action of sodium nitroprusside or cromakalim. Atherosperminine (50 microM) potentiated the action of forskolin to increase tissue cAMP content and, in higher concentrations (100 and 250 microM), itself increased tissue cAMP but not cGMP content. Atherosperminine markedly inhibited cAMP phosphodiesterase but not cGMP phosphodiesterase in homogenates of guinea-pig trachealis. It is concluded that atherosperminine exerts a non-specific relaxant effect on the trachealis. Its major mechanism of action appears to be inhibition of cAMP phosphodiesterase, perhaps with a minor effect on cGMP phosphodiesterase at higher concentrations.

Alkaloids↗
PubMed1993

Role of dialysis modality in responses of blood monocytes and peritoneal macrophages to endotoxin stimulation.

Constitutive and endotoxin (lipopolysaccharide [LPS])-stimulated release of interleukin-1 beta (IL-1 beta), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha), and prostaglandin E2 (PGE2) by blood monocytes and peritoneal cell preparations from patients on various forms of dialysis was measured. Monocytes were obtained from healthy controls (n = 20), and from patients on peritoneal dialysis (n = 8), on hemodialysis with cellulose ester membranes (n = 9), and on hemodialysis with polysulfone membranes (n = 8). Peritoneal macrophages were recovered by lavage during laparoscopic surgery from 11 healthy controls, from dialysate in 37 patients on peritoneal dialysis, and at catheter placement for transfer to peritoneal dialysis from eight patients on hemodialysis with polysulfone membranes. Peak LPS-induced production of TNF-alpha, IL-1 beta, and IL-6 by monocytes from patients on peritoneal dialysis and cellulose ester hemodialysis was less than that by monocytes from healthy controls. In contrast, monocytes from patients treated with polysulfone hemodialysis produced amounts of cytokine not different from controls. Lipopolysaccharide-stimulated PGE2 production by monocytes was the same in both patient and control groups. Peritoneal cell preparations from patients on peritoneal dialysis showed decreased release of IL-1 beta and TNF-alpha as compared with control peritoneal cells and with their own blood monocytes. To determine whether the decreased response to LPS by peritoneal cells compared with their own blood monocytes could be attributed to lower numbers of macrophages in the peritoneal cell preparations, adherence of peritoneal cells to plastic was performed. Adherence increased the percentage of macrophages from 70% to more than 90%. In monocytes and adherence purified peritoneal macrophages from peritoneal dialysis patients, no significant difference between monocytes and adherent peritoneal macrophages could be found for TNF-alpha and PGE2. Interleukin-1 beta production by the adherent peritoneal macrophages, as by total peritoneal cells, was significantly lower than that by monocytes. Constitutive production of PGE2 and IL-6 by peritoneal cells from patients on peritoneal dialysis was significantly increased. In contrast, LPS-stimulated production of TNF-alpha, IL-1 beta, and IL-6 by blood monocytes and peritoneal cells from patients receiving hemodialysis with polysulfone membranes was comparable to that produced by monocytes and peritoneal cells obtained from healthy controls. Thus, blood monocytes and peritoneal cells from patients on peritoneal dialysis and from patients on hemodialysis with cellulose-ester membranes demonstrate a decreased cytokine response to LPS, suggesting a state similar to endotoxin tolerance.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Studies on the acetogenins of Formosan annonaceous plants. II. Cytotoxic acetogenins from Annona reticulata.

Using cytotoxicity as a guide to fractionation, one novel acetogenin, annoreticuin-9-one [3], and four known cytotoxic acetogenins, squamone [4], solamin [5], annomonicin [6] and rolliniastatin 2 [7], were isolated from active extracts of the leaves of the Formosan plant Annona reticulata. Their structures were elucidated on the basis of uv, ir, 1H- and 13C-nmr, and ms data of the natural compounds and their derivatives.

Animals↗
PubMed1993

Pharmacological activity of (-)-discretamine, a novel vascular alpha-adrenoceptor and 5-hydroxytryptamine receptor antagonist, isolated from Fissistigma glaucescens.

1. The pharmacological activity of (-)-discretamine, isolated from Fissistigma glaucescens, was determined in rat isolated thoracic aorta, cardiac tissues and ventricular myocytes and guinea-pig isolated trachea. 2. (-)-Discretamine was found to be an alpha 1-adrenoceptor blocking agent in rat thoracic aorta as revealed by its competitive antagonism of noradrenaline (pA2 = 7.20 +/- 0.10)- or phenylephrine (pA2 = 7.60 +/- 0.09)-induced vasoconstriction. It was as potent as phentolamine (pA2 = 7.51 +/- 0.10), but was more potent than yohimbine (pA2 = 6.18 +/- 0.06). Removal of endothelium significantly increased the antagonistic potency of (-)-discretamine on noradrenaline (pA2 = 7.52 +/- 0.09)- or phenylephrine (pA2 = 7.90 +/- 0.09)-induced vasoconstriction. 3. (-)-Discretamine was also an alpha 2-adrenoceptor blocking agent (pA2 = 6.30 +/- 0.15) and a 5-hydroxytryptamine antagonist (pA2 = 6.87 +/- 0.06), both in rat aorta denuded of endothelium. 4. (-)-Discretamine protected alpha-adrenoceptors from alkylation by the irreversible blocking agent, phenoxybenzamine. 5. [3H]-inositol monophosphate formation caused by noradrenaline (3 microM) in rat thoracic aorta was suppressed by (-)-discretamine (10 and 30 microM) and prazosin (3 microM). 6. A high concentration of (-)-discretamine (30 microM) did not affect the contraction induced by the thromboxane receptor agonist U-46619, prostaglandin F2 alpha (PGF2 alpha), angiotensin II, high K+ or endothelin in rat aorta denuded of endothelium. Neither cyclic AMP nor cyclic GMP content of rat thoracic aorta was changed by (-)-discretamine. 7. Contraction of guinea-pig trachea caused by histamine, leukotriene C4 or carbachol was not affected by (-)-discretamine (30 microM). (-)-Discretamine also did not block beta l- or beta2-adrenoceptor-mediated responses induced by isoprenaline in rat right atria and guinea-pig trachea.8. A voltage clamp study in rat ventricular single myocytes revealed that sodium inward current, slow inward Ca2+ current or transient (ItO) and steady state (I800) outward current was not affected by(-)-discretamine (30 microM).9. It is concluded that (-)-discretamine is a selective x-adrenoceptor and 5-HT receptor antagonist in vascular smooth muscle.

Adrenergic alpha-Antagonists↗
PubMed1993

Ca(2+)-channel blockade in rat thoracic aorta by crychine isolated from Cryptocarya chinensis Hemsl.

The pharmacological effects of crychine, isolated from Cryptocarya chinensis Hemsl, on rat thoracic aorta were examined. In the high-K+ medium (60 mM), Ca2+ (0.03-3 mM)-induced vasoconstriction was inhibited by crychine in a concentration-dependent manner (10-100 micrograms mL-1). Increasing the incubation time from 5 to 30 min did not cause more pronounced inhibitory effect on KCl-induced contraction. The tonic contractions elicited by KCl (60 mM) and Bay K 8644 (0.1 microM) were also relaxed by the addition of crychine and were more marked in the 1.9 mM than in the 5 mM Ca2+ medium. The noradrenaline concentration-response curves were antagonized non-competitively by crychine (10-100 micrograms mL-1). At the plateau of noradrenaline-induced tonic contraction, the addition of crychine also caused relaxation. This relaxing effect of crychine was not antagonized by indomethacin (20 microM) or methylene blue (50 microM), and was still present in denuded aorta or in the presence of nifedipine (2 microM). Caffeine (10 mM)-induced contraction and cAMP or cGMP levels were not affected by crychine. It is concluded that crychine relaxes the rat thoracic aorta mainly by suppressing the Ca2+ influx through both voltage- and receptor-operated calcium channels.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1993

The effects of low calcium on the voltage-dependent conductances involved in tuning of turtle hair cells.

1. The voltage-dependent conductances of turtle cochlear hair cells of known resonant frequency were characterized by tight-seal, whole-cell recording during superfusion with solutions containing normal (2.8 mM) and reduced (0.1-10 microM) Ca2+. 2. In 1 microM Ca2+, the current flowing through the voltage-dependent Ca2+ channels was increased roughly fivefold and had a reversal potential near 0 mV. This observation may be explained by the Ca2+ channels becoming non-selectively permeable to monovalent cations in low-Ca2+ solutions. Lowering the Ca2+ further to 0.1 microM produced little increase in the current. 3. The size of the non-selective current increased systematically with the resonant frequency of the hair cell over the range from 10 to 320 Hz. This suggests that hair cells tuned to higher frequencies contain more voltage-dependent Ca2+ channels. 4. There was a good correlation between the amplitudes of the non-selective current and the K+ current which underlies electrical tuning of these hair cells. The amplitude of the K+ current also increased systematically with resonant frequency. 5. In cells with resonant frequencies between 120 and 320 Hz, the K+ current was completely abolished in 1 microM Ca2+, consistent with prior evidence that this current flows through Ca2+ activated K+ channels. In a majority of cells tuned between 50 and 120 Hz, the K+ current was incompletely blocked in 1 microM Ca2+, but was eliminated in 0.1 microM Ca2+. In all hair cells the K+ current was abolished by 25 mM tetraethylammonium chloride. 6. In cells tuned to 10-20 Hz, the K+ current was not substantially diminished even in 0.1 microM Ca2+, which argues that it may not be Ca2+ activated. 7. In cells tuned to frequencies above 100 Hz, the K+ current could still be evoked by depolarization during superfusion with 10 microM Ca2+. However, its half-activation voltage was shifted to more depolarized levels and its maximum amplitude was systematically reduced with increasing resonant frequency. 8. These observations are consistent with the notion that in cells tuned to more than 50 Hz, there is a fixed ratio of the number of voltage-dependent Ca2+ channels to Ca(2+)-activated K+ channels, the numbers of each increasing in proportion to resonant frequency. The results also provide indirect evidence that the Ca(2+)-activated K+ channels in cells tuned to higher frequencies may be less sensitive to intracellular Ca2+.

Animals↗
PubMed1993

Monitoring of segmental intra- and extracellular volume changes using electrical impedance spectroscopy.

Osmotically induced cellular volume changes in the perfused rat hindlimb were used to validate the use of bioelectrical impedance spectroscopy as a method for observing fluid shifts between the intracellular and extracellular spaces. Electrical impedance spectra were measured as cell volumes were manipulated by perfusion with Krebs-Henseleit solutions having different concentrations of NaCl. A simple equivalent circuit model of current conduction through the monitored tissue was fit to each measured spectrum to obtain segmental values of the equivalent intracellular resistance, membrane capacitance, and extracellular resistance. These parameters are theoretically governed by variations in the average cell volume fraction and ionic concentrations in the intra- and extracellular fluid spaces. In accord with this theoretical dependence, the parameters changed systematically and reversibly in conformance with both the magnitudes and directions of the perfusate concentration changes and the resultant cell volume changes. Results indicate that bioelectrical impedance spectroscopy, coupled with computer-aided equivalent circuit analysis, can be used to monitor segmental intercompartmental fluid shifts at minute-by-minute resolution.

Algorithms↗
PubMed1993

Changing seroepidemiology of hepatitis A virus infection between two regions in Taiwan differing in socioeconomic status.

In Taiwan, hepatitis A virus (HAV) infection is hyperendemic, and prior to the late 1970s more than 85% of the population was infected by 15 years of age. In this study, the prevalence of HAV infection in two regions of Taiwan with differing standards of living is evaluated. Serum antibody to HAV (anti-HAV) was determined by enzyme immunoassay. A total of 4,218 subjects under the age of 16 years were enrolled. The first group of 1,581 subjects were residents of the prosperous western plain region where the socioeconomic status and living environment have improved greatly in the past 20 years; the second group of 2,637 subjects were aborigines inhabiting the eastern and central mountain regions where improvement in the standard of living lags far behind the western region. All serum samples were collected in 1991 except for 1,100 samples collected in 1989 from elementary and junior middle school students in Tainan city. The prevalence of HAV infection was 11.9% for the western region and 81.0% for the eastern and central regions. In the eastern and central regions, 80% of the subjects had been infected with HAV before the age of six years, in contrast to 0% in the western region. By the age of 13 years, only 6% of the subjects were infected in the western region; however 97% had been infected in the eastern and central regions. Among children under the age of 10 years, only 10.6% (10/94) of the IgM-anti-HAV positive cases had clinical symptoms. These findings indicate that HAV infection has a close relationship with socioeconomic status and environmental sanitation.

Adolescent↗
PubMed1993

Dispase pretreatment enhances cell outgrowth from explanted human hair papillae.

An improved method which accelerates the attachment of cultured human hair papillae and enhances cell outgrowth is described. Bulbs of human hair follicles were exposed and treated in situ with dispase solution (50 units/mL) at 37 degrees C for 45 minutes before isolation and culture of the dermal papillae. About 45% of dispase-treated dermal papillae showed cell outgrowth five days after explant culture, while none of the control papillae did so. At 10 days after culture, 95% of dispase-treated dermal papillae had cell outgrowth, while the comparative figure for the control papillae was only 63%. In addition, many more outgrowing cells were found around the dispase-treated dermal papillae at any time compared to the control papillae. Dispase pretreatment is recommended as a routine procedure in the culture of the dermal papilla cells of human hair follicles.

Cell Division↗
PubMed1993

Growth of human melanocytes from suction blister of localized vitiligo patient and from foreskins of newborns and adults by modified culture medium.

We report on the culturing of melanocytes from suction blisters from the uninvolved skin of localized (focal and segmental) vitiligo patients and from the foreskins of newborns and adults, over a long period of time using a modified culture medium composed of F-12 medium supplemented with insulin (5 mg/mL), cholera toxin (40 ng/mL), transferrin (5 mg/mL), hydrocortisone (1 mM), epithelial growth factor (20 ng/mL), endothelial cell growth supplement (ECGS) (15 mg/mL), retinol (1 x 10(-7) M), 12-o-tetradecanoyl-phorbol-13 acetates (TPA) (85 nM), and 1% fetal calf serum (FCS). This method may be used in in vitro studies on normal human melanocytes and for study of the difference between melanocytes of normal individuals and of those with vitiligo. The ability to culture melanocytes from localized vitiligo, and the inability to grow those of generalized vitiligo with this system reconfirms the difference in the pathogenesis of various types of vitiligo. Thus, culturing may be used for differentiating localized vitiligo from generalized vitiligo and may be used to guide the mode of treatment when vitiligo has just started to develop and only a few depigmented patches have appeared. The results of studies on seeding density effect and serial Dopa reaction on the melanocytes of normal individuals reveal that the use of tyrosinase activity as the assessment parameter requires the use of melanocytes cultured for less than five months at a seeding density of less than 4 x 10(4) cells/cm2. Enlarged and heavily pigmented cells, senescent cells, were observed after very long-term culture (one year and four months).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

Absence of intravascular bubble nucleation in dead rats.

Bubble formation in the inferior vena cavae (IVC) of dead rats was investigated after 6-15-h exposures to air at 123 atm abs (12.5 MPa) and decompression to 1 atm abs at 13.6 atm/min (1.4 MPa/min). The maximum estimated air-supersaturation attained in the IVCs after decompression was 6.1-18.3 atm (0.6-1.8 MPa). Bubbles were detected by light microscopy, buoyancy, and underwater dissection. No bubbles formed in 42 blood-filled IVCs that were isolated from the circulation by ligatures, but bubbles were always observed in unisolated IVCs (P < 0.000005). Other isolated IVCs were filled with tap water, water and bubbles, or water and iron filings. Bubbles formed in 13% of the IVCs filled with tap water, in 16% of the IVCs containing water with preexisting bubbles, and in 80% of the IVCs containing water with iron filings. Results indicate that at the air supersaturations attained in the isolated IVCs a) blood is resistant to de novo bubble formation; b) preexisting bubbles are dissolved by compression; c) bubbles in water originate from preexisting gas nuclei; and d) iron filings harbor gas nuclei that are able to survive 122 atm (12.4 MPa) overpressures and form bubbles on subsequent decompression.

Air↗
PubMed1992

Presence of anti-basal cell antibodies in oral lichen planus.

BACKGROUND: An autoimmune hypothesis for oral lichen planus (OLP) has been proposed, but no anti-basal cell antibodies (anti-BCA) have been found in the sera of patients with OLP. OBJECTIVE: Our purpose was to test whether the negative results of anti-BCA assays in sera have been due to the insensitivity of the substrates. Rat esophagus, monkey esophagus, as well as human oral mucosa and skin were used to detect anti-BCA in sera of OLP patients. METHODS: By indirect immunofluorescence technique, the rat esophagus was found to be the most sensitive substrate. Therefore it was used as the only substrate to test the presence of anti-epithelial cell antibodies (anti-ECA) in a large group of patients with OLP and other oral mucosal diseases or normal control subjects. RESULTS: The results showed that anti-ECA were detected in 54% (34 of 63) of patients with OLP, 71% (15 of 21) of patients with aphthous ulcers, 29% (6 of 21) of patients with oral carcinoma, 20% (2 of 10) of patients with traumatic ulcer, and 7% (1 of 15) of patients with periodontitis but none of the healthy control subjects (n = 41). The presence of anti-BCA in OLP patients' sera was persistent and lasted for a few months or years. There was a decrease in the serum anti-BCA titers in six of eight anti-BCA-positive OLP patients after topical application of triamcinolone. CONCLUSION: These anti-BCA that persist longer in OLP patients' sera may be autoantibodies that are raised against altered basal cell-specific antigens.

Adult↗