Mutation of PTB binding sites causes misregulation of alternative 3' splice site selection in vivo

Alternative splicing of pre-mRNA is a commonly used mechanism to regulate gene expression in higher eukaryotes. However, with the exception of regulated cascades in Drosophila, the cis-acting elements and the trans-acting factors that control tissue- and/or developmentally regulated splicing remain largely unidentified. Cis-acting elements that control smooth muscle-specific repression of exon 3 of alpha-tropomyosin (alpha-TM) have been identified recently and consist of two regions that flank this exon. Deletion of either element causes misregulated splicing of alpha-TM in transfected smooth muscle cells. In experiments designed to characterize essential sequences within each element and the factors that interact with these sequences, we have identified two overlapping sequences within the downstream regulatory element (DRE) that are identical to binding sites for polypyrimidine tract binding protein (PTB) that were identified using iterative selection techniques. Mutation of these sites caused aberrant splicing regulation in transfected smooth muscle cells. In addition, sequences identical to high-affinity PTB binding sites were also detected upstream of exon 3 and mutation of these sites also resulted in misregulation of splicing in vivo, suggesting that PTB binding to specific sequences flanking exon 3 is responsible, in part, for the repression of exon 3. Consistent with this hypothesis, UV crosslinking and equilibrium binding assays confirm that the same mutations that cause misregulated splicing also disrupt PTB binding to RNA.     

New insights into p53 function from structural studies

Recent structural analysis of p53 has greatly enhanced our understanding of the biochemical activities of this protein by presenting us with a detailed picture of the chemical groups in the protein that are involved in protein stability, conformation and functional interactions. The current structures form the basis for the design of potential therapeutics which could, for example, revert a DNA-binding mutant back to a DNA-binding competent conformation. The structure of the tet domain forms the basis for designing an active therapeutic p53 with an oligomerization domain which would not cross react with a DNA-binding mutant p53. However, as useful as these structures have been in providing insight into the structure/function relationship for p53, a complete understanding of this protein awaits more detailed information on the full-length protein. In this respect, one of the most useful roles for future structural studies will be to help identify the nature of the conformational transition between latent and active p53, and how it can be modulated.     

Accumulation of 5-aminolevulinic acid-induced protoporphyrin IX in normal and neoplastic human endometrial epithelial cells

The aim of this study was to evaluate 5-Aminolevulinic acid (ALA)-induced fluorescence of normal and neoplastic endometrial epithelial cells for diagnosis and photodynamic treatment. Fluorescence of ALA-induced PpIX in vitro was measured by flow cytometry in two different human endometrial adenocarcinoma cell lines and in normal cells cultivated from fresh endometrial tissue of three premenopausal patients. The cells were analysed after incubation with different concentrations of ALA during 3, 6, or 24 hours. Both tumor cell lines showed a statistically significant higher fluorescence of PpIX than normal epithelial cells after incubation with 1 mg ALA per ml medium during 24 hours. The well-differentiated cancer cells produced significantly more PpIX than the poorly differentiated cancer cells. Relative PpIX intensity of the two cancer cell lines correlated with cell proliferation rate as measured by the doubling times of the cells. Higher accumulation of Pp IX in neoplastic endometrium compared to normal endometrial epithelial cells may provide targeted biopsies and selective photodynamic destruction of neoplastic micro-lesions.     

A prospective study of reproductive factors and risk of epithelial ovarian cancer

BACKGROUND: Parity and long term use of oral contraceptives have been associated consistently with a decreased risk of ovarian cancer. However, previous reports of the relationship of other reproductive factors (time since first use or last use of oral contraceptives, age at menarche or menopause, age at first birth) with ovarian cancer have been inconsistent. METHODS: The authors studied these relationships in the Nurses' Health Study, a prospective cohort study of 121,700 female registered nurses aged 30-55 years in 1976 when the study began. From 1976 to 1988, 260 cases of confirmed epithelial ovarian cancer occurred among 1.2 million person-years of follow-up. RESULTS: A statistically significant inverse association was observed between parity and ovarian cancer risk (relative risk [RR] = 0.84; 95% confidence interval [CI] = 0.77-0.91 per pregnancy); age at first birth was not associated independently with risk. In age-adjusted analyses, a significant inverse association was noted between long term use of oral contraceptives and ovarian cancer, which was no longer significant after controlling for other ovarian cancer risk factors (RR with > or = 5 years' use: 0.65; 95% CI = 0.40-1.05). After control for duration of use, a weak nonsignificant inverse association was observed with time since first oral contraceptive use and no independent effect of time since last use. Neither age at menarche nor age at menopause was associated significantly with ovarian cancer risk. CONCLUSIONS: In this large prospective study, parity was the only reproductive factor that had a substantial independent association with ovarian cancer. Long term oral contraceptive use also appeared to have an inverse relationship with ovarian cancer, although this association was of borderline significance (P = 0.11) after adjustment for other risk factors.     

Inhibition of growth of a murine squamous cell carcinoma by a cyclooxygenase inhibitor increases leukotriene B4 production

OBJECTIVE: To determine the role of metabolites of arachidonic acid in the growth of squamous cell carcinomas of the head and neck. DESIGN: Investigation of the effect of a cyclooxygenase inhibitor, piroxicam, on the growth of squamous cell carcinoma in a murine model. INTERVENTION: C3H/HeJ mice bearing squamous cell carcinoma (SCCVII) were treated with piroxicam (0.08 mg/d, orally) for 30 days beginning 1 day before tumor inoculation. MAIN OUTCOME MEASURES: Decrease in tumor volumes and tumor growth rates. RESULTS: Significant inhibition of tumor growth (P = .002) and final tumor weight (P = .0007) was noted in the group receiving piroxicam therapy. Prostaglandin E2 levels in the tumor tissue were unrelated to treatment or tumor size. Increased levels of leukotriene B4 were observed in the piroxicam-treated group (P = .03), and larger tumors were associated with decreased leukotriene B4 levels (P = .0001). CONCLUSIONS: Cyclooxygenase inhibitors may be effective in the treatment of some squamous cell carcinomas. The therapeutic effect of cyclooxygenase inhibitors may result from shunting into the lipoxygenase pathway of arachidonic acid metabolism.     

Pediatric percutaneous endoscopic jejunostomy by J-tube extension through a preexisting gastrostomy site: a preliminary report

A prematurely born 5-year-old boy with chronic lung disease, hypoxic-ischemic encephalopathy, cerebral palsy, repeated aspiration pneumonia, and stroke underwent percutaneous endoscopic jejunostomy (PEJ) to alleviate repeated aspiration pneumonia. Studies, including 24-hour esophageal pH monitoring, 99mTc gastric emptying time, upper gastroesophageal barium radiography, and endoscopic examinations showed severe gastroesophageal reflux and prolonged gastric emptying. Percutaneous endoscopic gastrostomy (PEG) was performed first, followed by placement of a polyurethane J-tube (9 French) through the preexisting gastrostomy site. We passed the style-guided J-tube through the pyloric ring endoscopically and advanced it to the jejunum. The position of the J-tube was confirmed by radiologic study. Feeding with an elemental formula, 20 mL/hour, commenced immediately after the procedure, and the rate was gradually increased to 50 mL/hour. No further episodes of aspiration pneumonia have occurred since J-tube placement. Our initial experience with jejunal feeding through a PEJ is encouraging.     

Assessment of the effects of combination therapy with ciprofloxacin and fenbufen on the central nervous systems of healthy volunteers by quantitative electroencephalography

The potential effects of concurrent administration of fenbufen and ciprofloxacin on central nervous system activity in healthy young subjects were investigated by electroencephalography (EEG). Visual analog scales (VAS) were used to assess subjective measures of concentration, vigilance, tension, and irritability. When ciprofloxacin was administered in combination with fenbufen, none of the EEG parameters or VAS ratings measured were significantly different from those measured when the drugs were administered alone.     

Stereovideographic evaluation of the postural geometry of healthy and scoliotic patients

Idiopathic scoliosis principally characterised by a deformation of the vertebral column can also be associated to postural abnormalities. The validity and reliability of current quantitative postural evaluations has not been thoroughly documented, frequently limited by a two dimensional view of the patient, and do not include the whole posture of the patient. The purpose of this study is to 1) quantify within and between-session reliability of a stereovideographic Postural Geometry (PG) evaluation and 2) to investigate the sensitivity of this technique for the postural evaluation of scoliosis patients. The PG of 14 control subjects and 9 untreated scoliosis patients were evaluated with 5 repeat trials, on two occasions. Postural geometry parameters that describe the position and orientation of the pelvis, trunk, scapular girdle and head were calculated based on the 3-dimensional co-ordinates of anatomical landmarks. The mean between and within-session variability across all parameters were 12.5 mm, 2.8 degrees and 5.4 mm and 1.4 degrees respectively. The patient group was heterogeneous with some noted pathological characteristics. This global stereovideographic postural geometry evaluation appears to demonstrate sufficient reliability and sensitivity to follow-up on the posture of scoliosis patients.