Lack of ceramide generation and altered sphingolipid composition are associated with drug resistance in human ovarian carcinoma cells

PTX (Paclitaxel) is an antimitotic agent used in the treatment of a number of major solid tumours, particularly in breast and ovarian cancer. This study was undertaken to gain insight into the molecular alterations producing PTX resistance in ovarian cancer. PTX treatment is able to induce apoptosis in the human ovarian carcinoma cell line, CABA I. PTX-induced apoptosis in CABA I cells was accompanied by an increase in the cellular Cer (ceramide) levels and a decrease in the sphingomyelin levels, due to the activation of sphingomyelinases. The inhibition of acid sphingomyelinase decreased PTX-induced apoptosis. Under the same experimental conditions, PTX had no effect on Cer and sphingomyelin levels in the stable PTX-resistant ovarian carcinoma cell line, CABA-PTX.The acquisition of the PTX-resistant phenotype is accompanied by unique alterations in the complex sphingolipid pattern found on lipid extraction. In the drug-resistant cell line, the levels of sphingomyelin and neutral glycosphingolipids were unchanged compared with the drug-sensitive cell line. The ganglioside pattern in CABA I cells is more complex compared with that of CABA-PTX cells. Specifically, we found that the total ganglioside content in CABA-PTX cells was approximately half of that in CABA I cells, and GM3 ganglioside content was remarkably higher in the drug-resistant cell line. Taken together our findings indicate that: i) Cer generated by acid sphingomyelinase is involved in PTX-induced apoptosis in ovarian carcinoma cells, and PTX-resistant cells are characterized by their lack of increased Cer upon drug treatment, ii) PTX resistance might be correlated with an alteration in metabolic Cer patterns specifically affecting cellular ganglioside composition.     

The regeneration and screening of watercress somaclones for resistance to Spongospora subterranea f. sp. nasturtii and measurement of somaclonal variation

A range of watercress (Rorippa nasturtium-aquaticum) explants (stems, hypocotyls, true-leaves, cotyledons and petioles) were tested for their capacity to regenerate adventitious shoots from callus formed using Murashige and Skoog medium containing different concentrations of thidiazuron and 2,4-dichlorophenoxyacetic acid. The highest shoot regeneration rate was a mean of 18 shoots per responding explant from stem callus formed on medium containing 5 μM thidiazuron and 0.05 μM 2,4-dichlorophenoxyacetic acid. A histological study confirmed that shoots originated directly from callus tissue. Twenty five percent of somaclones exhibited somaclonal variation in leaf shape, plant height, axillary branching or ploidy. The variation in 6% of somaclones was heritable to the first selfed generation. A screening protocol was developed to permit the identification of somaclones with increased resistance to the economically damaging watercress root pathogen, Spongospora subterranea f. sp. nasturtii. Although 883 somaclones were screened using this protocol, no significant increase in disease resistance was detected. This revised version was published online in June 2006 with corrections to the Cover Date.     

Serum creatine kinase activity following repeated bouts of isometric exercise with different muscle groups

The purpose of this study was to examine the relationship between the muscle mass involved in exercise and post-exercise serum creatine kinase (CK) elevation. Twelve untrained college-aged men completed three isometric exercises: one arm flexion (OAF), two arm flexion (TAF) and one leg knee extension (OLE). These exercises were balanced over subjects and days and separated by two week intervals. Each exercise consisted of 40 maximal isometric concentrations lasting for 10 s with a 20 s rest between contractions. Relative increases in serum CK for OAF, TAF, and OLE were 181 +/- 70% (SD), 222 +/- 69% and 297 +/- 67%, respectively. An ANOVA using a latin square design for analysis of carry over effects showed that these CK increases were not significantly different (p greater than 0.05). However, the increase in serum CK following the first exercise (379 +/- 90%), regardless of what it was (OAF, TAF, or OLE), was significantly greater (p less than 0.05) than those following bouts 2 and 3 (155 +/- 29%; 167 +/- 54%). Regression analysis indicated that post-exercise serum CK elevation was not related to the amount of muscle mass involved in the exercise (r = 0.30, p greater than 0.05) nor to muscle tension developed (r = 0.28, p greater than 0.05). We conclude that post-exercise serum CK elevation is not necessarily related to the muscle mass involved in the exercise. Because each exercise involved the use of different muscle groups, factors outside the exercising muscle may contribute to post-exercise serum enzyme activity.     

A preliminary investigation into tooth care, dental attendance and oral health related quality of life in adult stroke survivors in Tayside, Scotland

Objective: The aim of this study was to investigate patterns of oral care, dental attendance and oral health‐related quality of life among adults who had suffered a stroke. Background: Stroke is the most common cause of adult disability in the UK. Seventy per cent of strokes occur in adults over 65 years of age. A mild stroke may leave little residual disability but in cases of moderate or severe stroke the disability may be significant and may impact on oral health and function. Materials and methods: A cross‐sectional survey was conducted among adults surviving 1 year after stroke, between January and July 2001. A medical screening was carried out which included an assessment of disability and handicap using the modified Rankin scale. A structured interview was conducted to identify normal patterns of oral care and dental attendance and to elicit if since suffering a stroke any changes had occurred or were likely to occur. The Short Form Oral Health Impact Profile (OHIP‐14) was administered prior to an oral examination. Analysis used SPSS 11.0 for Windows. Parametric and nonparametric tests were undertaken (t‐tests and chi‐squared tests with Yates correction where appropriate). Results: Forty‐one adults were recruited into the study comprising 21 female and 20 male. They ranged in age from 50 to 87 years and the mean age was 69 years (SD = 9.8). Forty per cent of participants experienced moderate disability or greater following their stroke. Thirty‐seven per cent had difficulty with tooth cleaning. The most frequently reported problem was being unable to use one hand properly as a result of the stroke. There was a significant association between the degree of disability following stroke and difficulty with tooth cleaning (P = 0.015). Disability as a result of the stroke was cited as the main reason for reported or projected attendance pattern change. The most frequently experienced OHIP‐14 dimension was functional limitation (39%). Conclusion: Individuals who have been left disabled after a stroke may require help with or advice on oral care and information on how to access dental services in a setting appropriate to their disability. Further research is needed to identify the dental needs of adults with stroke and to identify appropriate interventions to meet these needs.     

Diatom motility and low frequency electromagnetic fields--a new technique in the search for independent replication of results

The hypothesis that exposure to a certain combination of static and alternating electromagnetic fields (EMFs) results in an increase in motility of the marine diatom Amphora coffeaeformis was tested. Diatom motility in three strains of A. coffeaeformis was positively correlated with extracellular calcium ion (Ca2+) concentration. The test apparatus consisted of two pairs of Helmholtz coils supported around the stage of a microscope linked to a video recorder and monitor. This system allowed real-time in vivo recordings of diatom speed under EMF and control exposures. The EMFs were calculated at calcium resonance values, previously found to cause enhanced motility. Computerised image analysis was used to calculate the distance moved by individual diatoms in 2-min periods before, during and after EMF or sham-EMF (control) exposure. The addition of EMF caused no significant increase in diatom motility. The results are discussed in relation to the use of diatom motility to measure EMF exposure effects.