Activities of drug metabolizing enzymes in bovine colon epithelial cell cultures

The metabolic competence of cultured bovine colon epithelial cells was evaluated by determining activities of phase I and II enzymes in colonocytes cultured for different intervals (maximum of 10 days) compared with activities measured in freshly isolated cells. Cytochrome P450 1A1-associated 7-ethoxyresorufin O-deethylase (EROD) activity was detectable in freshly isolated colonocytes and in colon cells maintained in culture for up to 5 days. In contrast to liver samples, cytochrome P450 3A4-associated 7-benzyloxyresorufin O-debenzylase (BROD) activity was not detectable in bovine colon cells. Prostaglandin H synthase-mediated production of prostaglandin E₂ was found in freshly isolated and also in cultured colonocytes. Both isoenzymes (COX 1 and COX 2) were detected in cultured cells. To examine phase II metabolic potency, activities of N-acetyltransferases 1 and 2, of phenol and amino sulfotransferases, of glutathione S-transferases alpha, mu, pi and theta and of UDP-glucuronyltransferase were measured. N-Acetyltransferase (NAT) activity (substrate p-aminobenzoic acid, PABA, a diagnostic substrate for the human NAT-1 enzyme) was stable under culture conditions and during the observed culture period comparable to that of freshly isolated cells. In contrast, sulfamethazine, a specific substrate for NAT-2, was not acetylated, neither in bovine colon cells nor in bovine liver samples. Whereas activity of amino sulfotransferase (substrate 2-naphthylamine) decreased continuously during the entire culture period, the activity of phenol sulfotransferase (substrate 1-naphthol) decreased only slowly. Activity of total glutathione S-transferases (alpha, mu, and pi) (substrate 1-chloro-2,4-dinitrobenzene) decreased after 2 days in culture, but was stable during the following culture period. Activity of glutathione S-transferase theta (substrate epoxy-3-nitrophenoxypropane) changed during the culture period. At the beginning and the end (after 10 days) of the culture period maximum activity was measured. Activity of UDP-glucuronyltransferase increased during the culture period reaching a maximum after 7 days. The results show that cultured bovine epithelial colon cells express several enzyme activities required for the biotransformation of xenobiotics.     

DR-nm23 expression affects neuroblastoma cell differentiation, integrin expression, and adhesion characteristics

BACKGROUND AND PROCEDURE: Nm23 gene family has been associated with metastasis suppression and differentiation. We studied DR-nm23 during neuroblastoma cells differentiation. DR-nm23 expression increased after retinoic acid induction of differentiation in human cell lines SK-N-SH and LAN-5. RESULTS: In several cell lines, overexpression of DR-nm23 was associated with more differentiated phenotypes. SK-N-SH cells increased vimentin expression, increased deposition of collagen type IV, modulated integrin expression, and underwent growth arrest; the murine neuroblastoma cell line N1E-115 showed neurite outgrowth and a striking enhancement of beta1 integrin expression. Up-regulation of beta1 integrin was specifically responsible for the increase in the adhesion to collagen type I-coated plates. Finally, cells overexpressing DR-nm23 were unable to growth in soft agar. CONCLUSIONS: In conclusion, DR-nm23 expression is directly involved in differentiation of neuroblastoma cells, and its ability to affects the adhesion to extracellular substrates and to inhibit growth in soft agar suggests an involvement in the metastatic potential of neuroblastoma.     

Role of c-MET in upper aerodigestive malignancies--from biology to novel therapies.

Overactivation and defective downregulation of receptor tyrosine kinase (RTK) pathways have been implicated in human carcinogenesis. RTKs represent an important class of anticancer novel therapeutic target. Some RTKs are known to be protooncogenes that can mediate signal transduction, alteration of reactive oxygen species (ROS), cellular proliferation, cell motility and migration, apoptosis, and survival. c-MET is a unique RTK that regulates a wide variety of cellular functions. c-MET has been shown to be overexpressed or mutated in a variety of human malignancies. Stimulation of c-MET via its natural ligand hepatocyte growth factor/ scatter factor (HGF/SF) leads to a plethora of biological and biochemical effects in the cell. Activation of c-MET signaling can lead to cell motility and scattering, angiogenesis, proliferation, branching morphogenesis, invasion, and eventual metastasis. This review summarizes the structure and functions of c-MET, with particular emphasis on its role in upper aerodigestive malignancies. The unique biological functions altered by c-MET and its mutations are discussed as well. Finally, c-MET, when mutated or overexpressed in malignant cells, serves as an important therapeutic target, and the most recent data with respect to its inhibition are also summarized in this review.     

Restraint use among nursing home residents: cross‐sectional study and prospective cohort study

Aims and objectives. To investigate (1) the prevalence of physical restraints and psychoactive medication, (2) newly administered physical restraints, frequency of application of the devices and frequency of psychoactive medication on demand during 12‐month follow‐up and (3) characteristics associated with restraint use in nursing homes. Background. High quality data on restraint use in German nursing homes are lacking so far. Such information is the basis for interventions to achieve a restraint‐free care. Design. Cross‐sectional study and prospective cohort study. Setting and subjects. Thirty nursing homes with 2367 residents in Hamburg, Germany. Methods. External investigators obtained prevalence of physical restraints by direct observation on three occasions on one day, psychoactive drugs were extracted from residents’ records and prospective data were documented by nurses. Results. Residents’ mean age was 86 years, 81% were female. Prevalence of residents with at least one physical restraint was 26·2% [95% confidence interval (CI) 21·3–31·1]. Centre prevalence ranged from 4·4 to 58·9%. Bedrails were most often used (in 24·5% of residents), fixed tables, belts and other restraints were rare. Prevalence of residents with at least one psychoactive drug was 52·4% (95% CI 48·7–56·1). The proportion of residents with at least one physical restraint after the first observation week of 26·3% (21·3–31·3) cumulated to 39·5% (33·3–45·7) at the end of follow‐up (10·4 SD 3·3 months). The relative frequency of observation days with at least one device ranged from 4·9–64·8% between centres. No characteristic was found to explain centre differences. Conclusions. The frequency of physical restraints and psychoactive drugs in German nursing homes is substantial. Pronounced centre variation suggests that standard care is possible without restraints. Relevance to clinical practice. Effective restraint minimisation approaches are urgently warranted. An evidence‐based guideline may overcome centre differences towards a restraint‐free nursing home care.     

Cerebrovascular risk factors and MRI abnormalities in migraine

Case series have demonstrated an increased incidence of white matter lesions (WMLs) in patients with migraine. It is controversial whether the evidence of subclinical brain lesions relates to a higher risk of cerebrovascular disease. The objective of this study was to evaluate the association between magnetic resonance imaging (MRI) subclinical brain lesions and cerebrovascular risk factors (hyperhomocysteinaemia, MTHFR genotype, patent foramen ovale, hypertension, smoking and hypercholesterolaemia). From our database of 1201 patients followed at our Headache Clinic since September 2003 we analysed the MRI findings of 253 individuals. All MRI were blindly analysed by a second neuroradiologist (C.A.) and patients with WMLs (study group) were evaluated. In order to assess the association of WMLs with specific vascular risk factors, patients with WMLs were matched, according to age, sex and ICHD II diagnosis, with an equal number of individuals with normal MRI (control group). Headache was classified by the International Classification of Headache Disorders (ICHD 2004) criteria. We did not find any statistically significant difference between the two groups with regard to the presence of the cerebrovascular disease risk factors considered. Our results confirm that the WMLs are not related to the cerebrovascular disease risk factors.