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Biomedical subjects

W Lai

Publications and source records attributed to W Lai.

At least 19 recordsLinked to original sources
PubMed2006

Skin phototyping in a Chinese female population: analysis of four hundred and four cases from four major cities of China.

BACKGROUND/PURPOSE: The sun-reactive skin types in 404 Chinese females living in different cities were investigated in this study. METHODS: A questionnaire was designed according to the original concept of skin types proposed by Fitzpatrick and the investigation was conducted in two ways: self-administered reporting and then a personal interview. Minimal erythema dose (MED) and minimal persistent pigmentation dose (MPPD) were also measured in part of the volunteers with a standard solar simulator. RESULTS: The results show that in the way of personal interview, the predominant skin type of the investigated group is type III (71.4%), and then type II (14.7%) and type IV (14.2%), while in the self-reporting manner, the result is as follows: type III, 74.3%, type II, 25.6% and type IV, 1%. There are no skin type I, V or VI in the studied group. MED and MPPD from the same population show some relevance to the skin types, e.g. with the change of skin type from Type II to IV, the mean value of MED increases gradually and the MPPD decreases slightly. CONCLUSIONS: From the study we concluded that the skin types of the investigated Chinese females are principally type III (more than 70%), and then type II and type IV. The different ways of answering the questionnaire did not affect the results remarkably. The measurements of photobiology parameters confirmed that there is a certain correlation between skin types and MED or MPPD determined in this group of volunteers.

Age Distribution↗
PubMed2005

Peripheral injection of lipopolysaccharide prevents brain recruitment of leukocytes induced by central injection of interleukin-1.

I.c.v. injection of interleukin-1beta induces infiltration of leukocytes into the brain. I.p. injection of bacterial endotoxin lipopolysaccharide induces the expression of interleukin-1 in the CNS without causing the entry of leukocytes into the brain. This suggests that during systemic inflammation trafficking of potentially damaging leukocytes into the CNS is inhibited. In this study, we investigated the effects of peripheral injection of lipopolysaccharide on brain leukocyte recruitment induced by i.c.v.-interleukin-1 in mice. I.c.v.-interleukin-1 induced widespread infiltration of leukocytes into the brain 16 h after the injection. Pretreatment with i.p.-lipopolysaccharide 2 h before the i.c.v. interleukin-1 injection completely blocked interleukin-1-induced leukocyte infiltration, whereas i.p.-LPS only attenuated the effect of interleukin-1 if it was given 12 h before i.c.v. interleukin-1 injection. I.p.-lipopolysaccharide given 24 h before i.c.v. interleukin-1 injection did not alter interleukin-1 induced leukocyte infiltration. I.c.v.-interleukin-1 induced expression of p- and e-selectins in brain vasculatures prior to the appearance of leukocytes in the brain parenchyma. Induction of p- and e-selectin was inhibited by the pretreatment of i.p.-lipopolysaccharide 2 h, but not 24 h, before i.c.v.-interleukin-1 injection. I.c.v.-interleukin-1-induced leukocyte infiltration was diminished in both e- and p- selectin knockout animals. These results suggest that systemic inflammation actively inhibits recruitment of leukocytes by CNS. Inhibition of the expression of p- and e-selectins is a mechanism by which peripheral inflammation regulate CNS leukocyte recruitment.

Animals↗
PubMed2003

Increasing relative prevalence of HSV-2 infection among men with genital ulcers from a mining community in South Africa.

OBJECTIVES: To determine the aetiology of genital ulcer disease (GUD) and its association with HIV infection in the mining community of Carletonville, South Africa, from two cross sectional surveys of consecutive men presenting with genital lesions during October 1993 to January 1994 and July to November 1998. METHODS: A multiplex polymerase chain reaction (M-PCR) assay combined with amplicon detection was used to identify DNA specific sequences of Treponema pallidum, herpes simplex virus (HSV), and Haemophilus ducreyi. A real time PCR assay was used to differentiate between HSV-1 and HSV-2. RESULTS: M-PCR detected T pallidum, HSV, and H ducreyi in 10.3%, 17.2%, and 69.4% of 232 GUD patients during 1993-4 and in 12.4%, 36.0%, and 50.5% of 186 GUD patients in 1998. The proportion of patients with more than one agent increased significantly from 7.3% (17/232) in 1993-4 to 16.7% (31/186) in 1998 (p <0.01). HSV-2 was detected in a higher proportion of ulcer specimens from HIV infected patients than in specimens from HIV uninfected patients during both time periods (1993-4: 26.2% v 6.7%, p <0.001; 1998: 42.1% v 29.6%, p >0.09). CONCLUSIONS: Based on two cross sectional surveys, 4 years apart, chancroid remained the leading cause of GUD in men who presented at the STD clinic with genital ulcers in the mining community of Carletonville, South Africa. The relative prevalence of primary syphilis has remained low. However, HSV-2 has emerged as a more significant cause of GUD and the proportion of GUD patients infected with more than one agent also increased significantly. HSV-2 DNA was detected in a significantly higher proportion of ulcer specimens from HIV positive patients than from HIV negative patients. No association was found between HIV infection status and the relative prevalence of chancroid or syphilis.

Adult↗
PubMed2002

Effects of long-term enalapril and losartan therapy of heart failure on cardiovascular aldosterone.

Plasma aldosterone escape is found during long-term ACE inhibitor therapy of chronic heart failure. Evidence for aldosterone production in cardiovascular tissues raised the question of whether aldosterone escape occurs or not in these tissues. Rats with infarction-induced chronic heart failure were treated with enalapril (20 mg/kg/d) and losartan (15 mg/kg/d) for 20 weeks. Untreated chronic heart failure and sham-operated rats were used as positive and normal controls, respectively. Ex vivo mesenteric artery and heart perfusion, high performance liquid chromatography, and RIA for aldosterone were performed. Chronic heart failure due to myocardial infarction was associated with tissue-specific activation of cardiovascular aldosterone synthesis. In the mesenteric artery, enalapril significantly inhibited aldosterone production compared to untreated, chronic heart failure rats, and losartan lowered aldosterone production to that of sham rats. In myocardium, enalapril failed to significantly inhibit aldosterone production, and losartan significantly inhibited aldosterone production compared to untreated, chronic heart failure rats. These results provide the first evidence that long-term ACE inhibition therapy induces aldosterone escape in myocardium but not in mesenteric artery of chronic heart failure. The angiotensin II subtype 1 receptor blocker losartan tranquilized aldosterone levels in the cardiovascular tissues of chronic heart failure rats.

Aldosterone↗
PubMed2002

Molecular typing of Treponema pallidum in South Africa: cross-sectional studies.

We evaluated a molecular subtyping system for Treponema pallidum for its ability to differentiate between strains obtained from male patients with primary syphilis in South Africa. Of 201 T. pallidum-positive specimens, 161 were typeable, revealing 35 subtypes. The unique subtypes identified in Durban, Cape Town, and Carletonville and the total number of subtypes suggested that the strain population was very diverse and varied geographically.

Bacterial Typing Techniques↗
PubMed2001

Regulation of steroidogenesis in transgenic mice and zebrafish.

Steroid hormones are important physiological regulators in the body. Steroid hormones are mainly synthesized in the adrenal and gonads. Their synthesis is stimulated by pituitary hormones through cAMP as an intracellular mediator. The first and rate-limiting step for steroid biosynthesis is catalyzed by CYP11A1. Important regulatory elements for the control of the CYP11A1 gene expression have been characterized both in vitro and in vivo. The SF-1-binding sites are cis-acting elements controlling the basal and cAMP-stimulated gene expression. Our transgenic mouse studies showed that the 2.3kb promoter contains information controlling developmentally regulated gene expression. Finally, we present our results on the cloning of steroidogenic genes in zebrafish, a new model organism for genetic studies.

Adrenal Glands↗
PubMed2001

Optimization of selected chromatographic responses using a designed experiment at the fine-tuning stage in reversed-phase high-performance liquid chromatographic method development.

This study evaluated the applicability of a designed experiment at the fine-tuning stage in reversed-phase high-performance liquid chromatographic (HPLC) method development. Using acetaminophen, theophylline, and caffeine as model drugs, a 3(2) factorial design was used to optimize selected chromatographic responses. The effects of the ratio of water to acetonitrile (%v/v) in the mobile phase and mobile phase flow rate on the theoretical plate number of acetaminophen peak, capacity factor of acetaminophen, resolution of acetaminophen and theophylline peaks, and the time for the elution of last peak (run time) were determined. Polynomial equations were derived to evaluate the quantitative relationships between the experimental factors and responses. A solution space was found by overlaying contour plots. Results indicated that, once the mobile phase that provides reasonably good retention and resolution has been identified, the strategy of using a designed experiment is advantageous over the conventional one-factor-at-a time approach since it would enable the analyst to optimize important responses, including run time with a minimum number of experiments.

Algorithms↗
PubMed2001

Effects of long-term enalapril and losartan therapy of hypertension on cardiovascular aldosterone.

BACKGROUND: Plasma aldosterone escape is found during long-term angiotensin-converting enzyme inhibitor therapy. Evidence for aldosterone production in cardiovascular tissues raised the question of whether or not aldosterone escape occurs in these tissues. METHOD: Spontaneously hypertensive rats were treated with enalapril (20 mg/kg/day) and losartan (50 mg/kg/day) for 20 weeks; untreated spontaneously hypertensive and Wistar rats were used as positive and normal controls, respectively. Ex vivo mesenteric artery and heart perfusion, high-performance liquid chromatography, and radioimmunoassay for aldosterone were performed. RESULTS: The results showed that enalapril failed to significantly inhibit aldosterone production in mesenteric artery, myocardium and plasma. Losartan significantly inhibited aldosterone production to that of Wistar rats in the mesenteric artery, myocardium and plasma. CONCLUSION: This study provides the first evidence that long-term angiotensin-converting enzyme inhibition therapy induces aldosterone escape in hypertensive cardiovascular tissues, and angiotensin II subtype 1 receptor antagonist does not induce aldosterone escape in mesenteric artery, myocardium and plasma of spontaneously hypertensive rats.

Aldosterone↗
PubMed2001

Dietary zinc supplementation inhibits NFkappaB activation and protects against chemically induced diabetes in CD1 mice.

Zinc status in patients with Type I diabetes is significantly lower than healthy controls. Whether zinc supplementation can prevent the onset of Type I diabetes is unknown. Recent studies have suggested that the generation of reactive oxygen species (ROS) is a cause of beta cell death leading to Type I diabetes. In addition, we found that activation of NFkappaB (a ROS-sensitive transcription factor that regulates immune responses) may be the key cellular process that bridges oxidative stress and the death of beta cells. Zinc is a known antioxidant in the immune system. Therefore, this study is designed to test whether an increase in dietary zinc can prevent the onset of Type I diabetes by blocking NFkappaB activation in the pancreas. The results show that high zinc intake significantly reduced the severity of Type I diabetes (based on hyperglycemia, insulin level, and islet morphology) in alloxan and streptozotocin-induced diabetic models. Zinc supplementation also inhibited NFkappaB activation and decreased the expression of inducible NO synthase, a downstream target gene of NFkappaB. It is concluded that zinc supplementation can significantly inhibit the development of Type I diabetes. The ability of zinc to modulate NFkappaB activation in the diabetogenic pathway may be the key mechanism for zinc's protective effect. Inhibition of the NFkappaB pathway may prove to be an important criterion for choosing nutritional strategies for Type I diabetes prevention.

Alloxan↗
PubMed2001

[CYP11B2 expression in rat liver and the efficacy of antisterone on liver fibrosis].

OBJECTIVE: To identify aldosterone synthase gene-CYP11B2 mRNA expression in rat livers and evaluate the efficacy of antisterone. METHODS: One hundred and twenty male Wistar rats were divided into 3 groups: model group (subcutaneous injection of CCl(4), 0.25 ml/100 mg, 3 times/week), antisterone group (besides same dosage of CCl(4) given, gastropufusion of antisterone of 20mg x kg(-1) x d(-1)), and control group (subcutaneous injection of olive oil). The area of collagen was examined by image analyzing system. The expression of aldosterone synthase gene-CYP11B2 mRNA was detected by RT-PCR and in situ hybridization. RESULTS: The expression of CYP11B2 mRNA, which located in the endoplasm of HSC, was upregulated when fibrogenesis occurred. The grade of fibrosis and the area of collagen in antisterone group were less than those in model group before 6th week (P<0.05). After the 6th week however, there was no significant difference between the two groups (P>0.05). CONCLUSIONS: The expression of CYP11B2 mRNA is upregulated in fibrotic liver. Antisterone can partly have a fibrogenesis-inhibiting effect on the early stage of CCl(4)-induced hepatic fibrosis.

Animals↗
PubMed2001

Gene-CYP11B2 expression in rat liver in hepatic fibrogenesis induced by CCl4.

OBJECTIVE: To identify aldosterone synthase gene-CYP11B2 mRNA expression in normal and fibrotic liver in rats and evaluate the curative effect of antisterone. METHODS: 160 Wistar rats weighing about 250 g were divided into 4 groups. In the model group (n = 40), the rats were injected with 40% CCl4 (0.25 ml/100 g) subcutaneously three times a week. In the antisterone group (n = 40), the rats were injected with 40% CCl4 (0.25 ml/100 g) subcutaneously three times a week. Antisterone equivalent to 20 mg.kg-1.d-1 was given intragastrically (ig). In the malotilate group (n = 40), the rats were injected with 40% CCl4 (0.25 ml/100 g) subcutaneously three times a week. Malotilate equivalent to 50 mg/kg-1.d-1 was given ig. In the control group (n = 40), the rats were injected with olive oil only. After 2, 4, 6, 8 and 10 weeks, animals were sacrificed, and morphological examination was carried out. The area of collagen was examined with an Image Analyse System. Expression of the aldosterone synthase gene, CYP11B2 mRNA, in fibrotic and normal liver was detected by means of reverse transcriptase polymerase chain reaction (RT-PCR) and in situ hybridization. RESULTS: In situ hybridization and RT-PCR showed that the expression of CYP11B2 mRNA, which localized in the endoplasm of hepatic stellate cells (HSCs), was up regulated when fibrogenesis occurred. Histological observation indicated that the grade of fibrosis and the area of collagen in the antisterone group were less than those in model group before 6 weeks (P < 0.05). There was no significant difference between the antisterone and malotilate groups (P > 0.05). After that, however, the grade of fibrosis and the area of collagen in the antisterone group were higher than those in the malotilate group (P < 0.05). There was no significant difference between the antisterone and model groups (P > 0.05). CONCLUSIONS: The expression of CYP11B2 mRNA is up regulated in fibrotic liver. Antisterone can have a partial fibrogenesis-inhibiting effect in the early stages.

Animals↗
PubMed2001

[Role of salbutamol in inducing apoptosis of cultured human airway smooth muscle cells].

OBJECTIVE: To study the effect of salbutamol on inducing apoptosis of cultured human airway smooth muscle cells (ASMCs). METHODS: Human ASMCs were isolated and cultured in DMEM containing 10% fetal bovine serum. Cells of Passes 4 approximately 6 were used in experiments. The cells were cultured with salbutamol, cromakalim, 8-Br-cAMP for 24 or 48 hours. Morphological changes were observed by light microscopy and electron microscopy. DNA fragmentation was analyzed by agarose gels. SP immunohistological staining method was performed to detect the changes of expressions of p53, Bcl-2 and Bax gene. The percentage of apoptosis cell was detected by situ end labeling technique (TUNEL) of fragmental DNA. RESULTS: (1) Salbutamol or 8-Br-cAMP decreased the number of viable cells. At 48 hour, at 300 micromol/L, number of viable cells was the lowest. (2) Human ASMCs incubated with salbutamol (100 micromol/L or 300 micromol/L) for 48 h revealed morphological features of apoptosis (cellular shrinkage, condensation of chromatin). (3) Agarose gel electrophoresis showed a characteristic "ladder" of DNA bands representing integer multiples of the internucleosomal DNA length (about 180 approximately 200 bp). (4) The expression of p53 or Bax gene in salbutamol or 8-Br- cAMP group was significantly higher than that in control group, but the expression of BCl-2 gene was lower than that in control group. (5) The TUNEL indicated: apoptotic positive rate of human ASMCs was significantly different following 100 micromol, 300 micromol salbutamol or 100 micromol 8-Br-cAMP treatment (q = 24.04, 58.47, 27.78 respectively, P < 0.0001), but cromakalim, propranolol before salbutamol not affected basal level of apoptotic cell (q = 0.12, 0.52 respectively, P = 0.932, 0.717 respectively), as compared with the controls. CONCLUSIONS: (1) Salbutamol induced apoptosis in human ASMCs in vitro in time and concentration dependent manner. (2) A cAMP-protein kinase A pathway is necessary and sufficient for salbutamol induced apoptosis. (3) beta(2) adrenergic agonist or cAMP analogue may prevent airway remodeling in asthma.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed2001

[Preliminary study on the methods of systematizing the data of ancient epidemic situations].

Taking the data of ancient epidemic situations in the south of the Five Ridges, as an example, the systematization materials of ancient epidemic situation guided by epidemiological methods are explored by defining the material of epidemic situation, selected compilation of relevant factors, decision of the severity, location, and its occasion etc. It is attempted to solve some problems in modernization and datalization of the collation of ancient literatures of Traditional Chinese Medicine.

China↗
PubMed2001

[The clinical application and modification of the Quad Helix appliance].

OBJECTIVE: The aims of this study are to investigate the working mechanism, the characteristics, the clinical application and the suggested modification of the Quad Helix appliance. METHODS: A 7-year-old, female patient with Pierre-Rokin syndrome, who was preformed with palatorrhaphy at 21-month-old treated by using a Quad Helix appliance for one year. RESULTS: After one-year treatment, the wide between the maxillary first molars increased 9.65 mm, and the wide between maxillary canines increased 5.20 mm. The wide between the mandibular first molars also increased 3.60 mm, however the wide between mandibular canines decreased 5.20 mm. CONCLUSION: The Quad-helix appears to be a successful Orthodontic appliance to expand the narrow maxillary or mandibular arches.

Child↗
PubMed2000

Optical patternation: a technique for three-dimensional aerosol diagnostics

A novel technique based on optical patternation is described for three-dimensional diagnostic studies of aerosols used in analytical spectroscopies. The aerosol is illuminated with a thin laser light sheet to capture images of the fluorescence and Lorenz-Mie light-scattering signals from the aerosol field with a charge-coupled detector. These measurements allow for the rapid and nonintrusive elucidation of two-dimensional spray structures, planar mass distributions, and spatial droplet size distributions. The ratio of the fluorescence image to the Lorenz-Mie image is then utilized to construct a spatially resolved map of the volume-to-surface area mean of the aerosol (Sauter mean diameter). Three-dimensional maps of spray structure, mass distribution, and droplet size distribution are obtained for the entire aerosol field by image stacking. The technique is applied to the measurement of the droplet size over the aerosol field at distances of 5-30 mm from the nebulizer tip where droplet sizes ranged from 6 to 12 microm for a direct injection high efficiency nebulizer used in inductively coupled plasma spectrometries.

Journal Article↗
PubMed2000

Induction of IkappaBalpha mRNA expression in the brain by glucocorticoids: a negative feedback mechanism for immune-to-brain signaling.

Peripheral injection of bacterial endotoxin lipopolysaccharide (LPS) induces brain mRNA expression of the proinflammatory cytokines interleukin-1beta (IL-1beta) and tumor necrosis factor-alpha and the cytokine-responsive immediate-early gene IkappaBalpha. Peripheral LPS also increases levels of plasma glucocorticoids. Whether the induction of IkappaBalpha mRNA in the brain after peripheral LPS injection is caused by the feedback action of glucocorticoids has not been determined. In this study, we examined the mRNA expression of IkappaBalpha and IL-1beta in the rat brain by in situ hybridization histochemistry. Injection of the glucocorticoid agonist dexamethasone induced IkappaBalpha mRNA expression in the brain in a pattern identical to that of LPS injection. LPS but not dexamethasone also induced IL-1beta mRNA expression. Pretreatment with dexamethasone 30 min before LPS injection enhanced the expression of IkappaBalpha mRNA in the brain in a dose-dependent manner. Immobilization of rats for 2 hr (which raises glucocorticoid levels) also induced IkappaBalpha mRNA expression without inducing the expression of IL-1beta. Brain IkappaBalpha expression induced by peripheral LPS injection was attenuated by pretreatment of rats with the glucocorticoid antagonist RU-486. Finally, increased expression of IL-1beta mRNA in the brain was observed at 4 hr after peripheral LPS injection in adrenalectomized rats compared with sham-operated rats. These results reveal that in the brain glucocorticoids selectively induce IkappaBalpha mRNA expression, which serves as a negative feedback mechanism for peripheral LPS-induced synthesis of proinflammatory cytokines. Such an inhibitory control mechanism may be important for preventing prolonged expression of proinflammatory cytokines in the brain after peripheral immune challenge.

Animals↗
PubMed2000

[Toxicity of anti-herbicide gene (BAR) transgenic rice].

In order to evaluate the safety of anti-herbicide gene(BAR) transgenic rice, acute toxicity experiments, mutation experiments and a 30-day feeding test were conducted. The results were as follows: The oral LD50 for mice and rats was larger than 21.5 g/kg BW and no mutation was found. The rats consuming 16.32 and 64 g/kg BW were in good growth and development at the 30-day feeding test. The body weight, food utilization, routine blood tests, the ratio of organ weight to body weight, and patho-histological observations had no obvious change. The none effect dosage for the transgene rice was 64 g/kg.

Animals↗