Biomedical subjects

Chunxia Xu

Publications and source records attributed to Chunxia Xu.

3 recordsLinked to original sources

PubMed2006

Expression of p53 tumor suppressor protein in sun-exposed skin and associations with sunscreen use and time spent outdoors: a community-based study.

The p53 gene is a tumor suppressor gene that is commonly mutated in skin cancer and sun-exposed skin, and this can be detected through immunohistochemical expression of the p53 protein. The authors hypothesized that time spent outdoors is associated with p53 protein expression in human skin and that sunscreen use counteracts the association. In 1996, they investigated this in a community-based cross-sectional study in Australia. Detailed information about skin type, time spent outdoors, and sunscreen use was collected from 139 residents of a subtropical township who also provided a skin biopsy from the back of the hand for measurement of p53 expression. Increasing time spent outdoors was positively associated with immunoreactivity in the whole epidermis and in the basal layer of the epidermis. After adjustment for confounders, p53 immunoreactivity was twice as high for people who used sunscreen 1 or 2 days per week as for those who used sunscreen daily (whole epidermis: ratio estimate=2.0, 95% confidence interval: 1.1, 3.6; basal layer: ratio estimate=1.7, 95% confidence interval: 0.9, 3.1). The authors conclude that p53 immunoreactivity in the skin is a marker of exposure to ultraviolet light in the past 6 months, but this may be mitigated by regular application of sunscreen.

Adult↗

PubMed2006

Outcome after portoenterostomy in biliary atresia: pivotal role of degree of liver fibrosis and intensity of stellate cell activation.

OBJECTIVES: Biliary atresia (BA), a congenital idiopathic obliterative cholangiopathy, rapidly leads to liver cirrhosis and liver failure if untreated. A timely Kasai portoenterostomy (KP) variably alters this natural history. We evaluated liver fibrogenesis by the intensity of alpha-smooth-muscle actin (SMA) expression, which is a marker for hepatic stellate cell activation. We hypothesized that liver fibrogenesis as determined by intensity of alpha-SMA is already progressing at the time of KP, is related to age and degree of fibrosis at KP, and predicts outcome after KP. METHODS: BA patients at KP (n = 22, age 22-84 days, median 59) had wedge liver biopsies assessed by quantitative morphometry of immunohistochemistry for alpha-SMA expression. Fibrosis was scored by blinded pathologists. Outcome, reflected by conjugated bilirubin concentration 3 months after KP (CBili3m), survival of the native liver, need for liver transplant, or death, were assessed for 2 to 10 years after KP. RESULTS: At KP, age, fibrosis score, and alpha-SMA expression were significantly correlated. Moderate-severe fibrosis and intense alpha-SMA expression was observed in 15 of 22 (68%) patients. Severe fibrosis and high alpha-SMA expression were significantly associated with CBili3m greater than 2 g/dL and unfavorable liver survival (>90% of these ultimately underwent liver transplantation or died). Conversely, those with mild fibrosis and low alpha-SMA expression had normal CBili3m and favorable liver survival. CONCLUSION: Intense liver fibrogenesis is already established in many cases of BA at the time of KP. Fibrosis scores and intensity of alpha-SMA expression may be predictors of outcome after KP and may indicate those patients who might benefit from trials of potential antifibrotic agents early in the course of BA.

Actins↗

PubMed2003

A rapid method for determining recent sunscreen use in field studies.

The role of sunscreens in preventing skin cancer and melanoma is the focus of ongoing research. Currently, there is no objective measure which can be used in field studies to determine whether a person has applied sunscreen to their skin, and researchers must use indirect assessments such as questionnaires. We sought to develop a rapid, non-invasive method for identifying sunscreen on the skin for use in epidemiological studies. Our basic method is to swab the skin, elute any residues which have been adsorbed onto the swab by rinsing in ethanol, and submit the eluted washings for spectrophotometric analysis. In a controlled study, we applied 0.1 ml of sunscreen to a 50 cm(2) grid on both forearms of 21 volunteers. Each forearm was allocated one of 10 different sunscreen brands. The skin was swabbed after intervals of 20 min, 1 h, 2 h and 4 h. In a field study conducted among 12 children aged 2-4 years attending a child care centre, sunscreen was applied to the faces of half the children. Swabs were then taken from the face and back of all children without knowledge of sunscreen status. In the controlled study, sunscreen was clearly detectable up to 2 h after application for all brands containing organic sunscreen, and marginally detectable at 4 h. In the field study, this method correctly identified all children with and without sunscreen. We conclude that spectrophotometric analysis of skin swabs can reliably detect the presence of sunscreen on the skin for up to 2 h after application.

Adult↗