VerstÄrkung der radiotherapeutischen wirkung auf HeLa-Zellen durch gemcitabine

BACKGROUND: Gemcitabine (2'.2'-difluorodeoxycytidine; dFdC) is a new nucleoside analog with promising activity in different solid tumors in vivo and in vitro. As published up to now, combined with irradiation dFdC demonstrates a radiosensitizing effect on pancreas and colon carcinoma cell lines. We investigated the influence of dFdC on the radiosensitization of human squamous carcinoma cells of the cervix (HeLa-cells, ATCC CCL-2). MATERIAL AND METHODS: Under standardized conditions monolayer cultures of HeLa-cells were incubated in medium with dFdC for different times (4 to 24 hours) and exposed to different concentrations (0.003, 0.01 and 0.03 mumol/l). Irradiation (2 to 6 Gy, electron beam) followed immediately or 12 hours after dFdC-exposure. Cell survival was determined by colony forming assay. Using the linear-quadratic model cell survival curves were fit after correction for drug-induced cytotoxicity and the mean inactivation dose (MID) was calculated. Radiation enhancement was defined as the ratio MIDRT(= Control)/MIDRT + dFdC > 1. RESULTS: Exposed to gemcitabine for 4 and 8 hours and followed by immediate irradiation the radiation enhancement ratio (Table 1) is 1.07 to 1.14 and 1.04 to 1.22, respectively, if dFdC concentration is > or = 0.01 to 0.03 mumol/l. Further increase of the irradiation effect is demonstrated in cells exposed to > or = 0.003 to 0.03 mumol/l dFdC for 16 and 24 hours (radiation enhancement ratio 1.08 to 2.0 and 1.08 to 2.48, respectively) (Figure 3). If irradiation is applied 12 hours after 24-hour-exposure (0.01 and 0.03 mumol/l) the enhancement ratio was 1.18 and 1.7, respectively (Figure 4). CONCLUSIONS: In cell cultures the assays combining irradiation with dFdC demonstrate that dFdC is a potent radiation sensitizer of HeLa-cells. The effect of irradiation on cells pre-treated with non- and hardly cytotoxic concentrations of dFdC is increased in dependence of dose and time of exposure.     

Intima-media thickness predicts stroke risk in the Heinz Nixdorf Recall study in association with vascular risk factors, age and gender

Background and purposeIndividual risk stratification requires reliable information on preexisting vascular disease. The intima-media thickness of the common carotid artery (CIMT) is a non-invasively accessible marker of atherosclerosis, which can be used for risk evaluation.MethodsIn a sample of 3669 initially stroke-free subjects aged 45–75 years belonging to the population-based Heinz Nixdorf Recall cohort, the predictive value of CIMT for incident stroke was evaluated over 85.3 ± 17.4 months in addition to established risk factors.ResultsIn a multivariable Cox regression analysis with traditional cardiovascular risk factors including age, gender, systolic blood pressure, LDL and HDL, diabetes, body mass index, smoking and CIMT, CIMT was a moderate stroke predictor (hazard ratio = 1.20 per 0.1 mm, 95% confidence interval = 1.01–1.44; p = 0.043), additional to e.g. age (1.46 per 5 years, 1.21–1.75; p < 0.001), systolic blood pressure (1.16 per 10 mm Hg, 1.04–1.30; p = 0.008) and current smoking (1.93, 1.12–3.31; p = 0.014). CIMT was associated with stroke risk in subjects above but not below 65 years. CIMT predicted stroke events in men, but not women. CIMT discriminated stroke incidence specifically in subjects belonging to the highest Framingham risk score tercile.ConclusionsCIMT is a moderate independent stroke predictor, which discriminates stroke incidence in subjects at high vascular risk.     

Perinatal exposure to the fungicide prochloraz feminizes the male rat offspring.

Prochloraz is a commonly used fungicide that has shown multiple mechanisms of action in vitro. It antagonizes the androgen and the estrogen receptors, agonizes the Ah receptor, and inhibits aromatase activity. In vivo prochloraz acts antiandrogenically in the Hershberger assay by reducing weights of reproductive organs, affecting androgen-regulated gene expressions, and increasing luteinizing hormone (LH) levels. The purpose of this study was to investigate reproductive toxic effects after exposure during gestation and lactation to prochloraz alone and a mixture of five pesticides (deltamethrin, methiocarb, prochloraz, simazine, and tribenuron-methyl). Prochloraz (30 mg/kg/day) or the mixture (20 mg/kg/day) was dosed to pregnant Wistar dams from gestational day (GD) 7 until postnatal day (PND) 16. Some dams were taken for cesarean section at GD 21, and others were allowed to give birth. Results showed that prochloraz and the mixture significantly reduced plasma and testicular testosterone levels in GD 21 male fetuses, whereas testicular progesterone was increased. Gestational length was increased by prochloraz. Chemical analysis of the rat breast milk showed that prochloraz was transferred to the milk. In males a significant increase of nipple retention was found, and the bulbourethral gland weight was decreased, whereas other reproductive organs were unaffected. In addition cytochrome P450 (CYP)1A activities in livers were induced by prochloraz, possibly as a result of Ah receptor activation. Behavioral studies showed that the activity level and sweet preference of adult males were significantly increased. Overall these results strongly indicate that prochloraz feminizes the male offspring after perinatal exposure, and that these effects are due, at least in part, to diminished fetal steroidogenesis.     

Four-year clinical evaluation of Class II nano-hybrid resin composite restorations bonded with a one-step self-etch and a two-step etch-and-rinse adhesive

Objective

The objective of this prospective clinical trial was to evaluate the 4-year clinical performance of an ormocer-based nano-hybrid resin composite (Ceram X; Dentsply/DeTrey) in Class II restorations placed with a one-step self-etch (Xeno III; Dentsply/DeTrey) and two-step etch-and-rinse adhesive (Ivoclar Vivadent).

Methods

Seventy-eight participants received at random at least two, as similar as possible, Class II restorations of the nano-hybrid resin composite bonded with either a single step self-etch adhesive or a control 2-step etch-and-rinse adhesive. The 165 restorations were evaluated using slightly modified USPHS criteria at baseline and then yearly during 4 years.

Results

162 restorations were evaluated at 4 years. Postoperative sensitivity was observed in 6 patients (3 Xeno III, 3 Exite) between 1 and 3 weeks. Eleven failed restorations (6.8%) were observed during the follow up. Seven in the one-step self-etch adhesive group (7.7%) and four in the 2-step etch-and-rinse group (5.6%). This resulted in non-significant different annual failure rates of 1.9% and 1.4%, respectively. Fracture of restoration was the main reason for failure.

Conclusion

The ormocer-based nano-hybrid resin composite showed a good clinical performance in Class II cavities during the 4 year evaluation. No significant difference was seen in overall clinical effectiveness between the two adhesives.     

Bone marrow aspirations in oncological patients: experience from an in-house standard in paediatrics

Wiener Medizinische Wochenschrift - Nearly all paediatric patients require deep sedation when undergoing bone marrow aspiration (BMA). We analyzed the data from our protocols documented in...     

Extreme sarcoplasmic reticulum volume loss and compensatory T-tubule remodeling after Serca2 knockout

Cardiomyocyte contraction and relaxation are controlled by Ca(2+) handling, which can be regulated to meet demand. Indeed, major reduction in sarcoplasmic reticulum (SR) function in mice with Serca2 knockout (KO) is compensated by enhanced plasmalemmal Ca(2+) fluxes. Here we investigate whether altered Ca(2+) fluxes are facilitated by reorganization of cardiomyocyte ultrastructure. Hearts were fixed for electron microscopy and enzymatically dissociated for confocal microscopy and electrophysiology. SR relative surface area and volume densities were reduced by 63% and 76%, indicating marked loss and collapse of the free SR in KO. Although overall cardiomyocyte dimensions were unaltered, total surface area was increased. This resulted from increased T-tubule density, as revealed by confocal images. Fourier analysis indicated a maintained organization of transverse T-tubules but an increased presence of longitudinal T-tubules. This demonstrates a remarkable plasticity of the tubular system in the adult myocardium. Immunocytochemical data showed that the newly grown longitudinal T-tubules contained Na(+)/Ca(2+)-exchanger proximal to ryanodine receptors in the SR but did not contain Ca(2+)-channels. Ca(2+) measurements demonstrated a switch from SR-driven to Ca(2+) influx-driven Ca(2+) transients in KO. Still, SR Ca(2+) release constituted 20% of the Ca(2+) transient in KO. Mathematical modeling suggested that Ca(2+) influx via Na(+)/Ca(2+)-exchange in longitudinal T-tubules triggers release from apposing ryanodine receptors in KO, partially compensating for reduced SERCA by allowing for local Ca(2+) release near the myofilaments. T-tubule proliferation occurs without loss of the original ordered transverse orientation and thus constitutes the basis for compensation of the declining SR function without structural disarrangement.     

Selenium has a protective role in caspase-3-dependent apoptosis induced by H2O2 in primary cultured pig thyrocytes

OBJECTIVE: Hydrogen peroxide (H2O2), necessary for thyroid hormonogenesis, is produced at the apical surface of the thyroid follicular epithelium. Excess H2O2 is potentially cytotoxic and may contribute to the development of hypothyroidism, e.g. in severe selenium deficiency. Yet it is unclear how H2O2 contributes to thyroid cell death. DESIGN AND METHODS: H2O2-induced apoptosis and necrosis were studied in primary cultured pig thyroid cells. Glutathione peroxidase (GPx) activity was altered by culture in low serum with or without selenite substitution. Apoptosis was evaluated by spectrofluorometric measurement of caspase-3-specific substrate cleavage, and by analysis of DNA fragmentation by agarose gel electrophoresis. Necrosis was detected by 51Cr release from prelabeled cells. RESULTS: Exogenous H2O2 dose-dependently (100-400 micromol/l) activated caspase-3 within 3-12 h, and DNA degradation was observed after 24 h. The potency of H2O2 to induce apoptosis was low compared with that of staurosporine, a strong proapoptotic agent. H2O2-treated cells with reduced GPx activity showed increased caspase-3 activation. Incubation of serum-starved cells with selenite (10-100 nmol/l) normalized the GPx activity and reduced the activation of caspase-3 by H2O2. High H2O2 concentrations (400-800 micromol/l) were required to obtain necrosis. The H2O2-induced necrosis was exaggerated by both low GPx activity and catalase inhibition. CONCLUSIONS: Cytotoxic effects of H2O2 on thyroid cells include caspase-3-dependent apoptosis that occurs at H2O2 concentrations insufficient to induce necrosis. Selenium deficiency aggravates the apoptotic response, probably due to impaired capacity of GPx to degrade H2O2.     

Subclinical coronary atherosclerosis and resting ECG abnormalities in an unselected general population

ObjectivesExposure to cardiovascular (CV) risk factors may result in coronary atherosclerosis and myocardial disease, which is reflected in the extent of coronary artery calcification (CAC) and resting ECG abnormalities, respectively. We studied the association of CAC with ECG abnormalities in a general population without myocardial infarction or revascularization.MethodsThe total cohort of 4814 subjects (45–75 years) were randomly selected from the general population for the Heinz Nixdorf Recall Study, an ongoing study designed to assess the prognostic value of modern risk stratification methods. In addition to measuring standard risk factors, digitized resting ECGs and the EBT-based Agatston score were obtained. Subjects were separated into those without (n = 1929) and with CV disease (CVD) or treated risk factors (tRF) (n = 2558).ResultsIn both groups, a positive CAC-score was more frequent and CAC-scores were higher in men and women with ECG abnormalities as compared to those with normal ECGs (p < 0.05 each). In persons without CVD/tRF, a CAC ≥75th percentile was more frequent in those with LVH (42.4%) and QTc >440 ms (34.2%) as compared to normal ECGs (23.0%, p < 0.01 for both). In persons with CVD/tRF, a CAC-score ≥75th percentile was found in subjects with A-Fib (46.3%), borderline-LVH (39.1%), ECG signs of MI (40.5%) and major ECG abnormalities (40.3%) versus 31.2% in those with normal ECGs (p < 0.03 for all). In multivariate analysis, LVH (p = 0.025) and major ECG abnormalities (p = 0.04) remained independently associated with CAC in subjects without and with CVD/tRF, respectively.ConclusionsECG-based evidence of myocardial disease is often associated with an elevated CAC burden, suggesting a link between epicardial and myocardial manifestations of risk factor exposure. The association of CAC burden with different ECG abnormalities in different clinical groups may have implications for the interpretation of the resting ECG and CAC burden in risk stratification.