Mitochondrial permeability transition is altered in early stages of carcinogenesis of 2-acetylaminofluorene

The tumour promoting properties of carcinogenic 2-acetylaminofluorene (AAF) in rat liver are essentially unknown. We proposed that mitochondria are a target for the cytotoxic effects of 2- nitrosofluorene (NOF), a metabolite of AAF, since NOF induces a redox- cycle at complex I and complex III of the respiratory chain, and impairs respiration and oxidative phosphorylation. We now demonstrate that NOF is a potent inducer of the mitochondrial permeability transition pore (PTP) in isolated mitochondria. In the presence of Ca2+, NOF induced rapid swelling of mitochondria in a dose-dependent manner and depolarized the mitochondrial membrane. Permeability transition as well as depolarization were abolished completely by pre- incubation with the PTP inhibitor cyclosporin A. To study whether the PTP is involved in in vivo toxicity, rats were fed a diet containing AAF (0.04%) for 2 weeks. After isolation of mitochondria, permeability transition was induced by high Ca2+ concentrations (150-400 microM) or phosphate plus Ca2+. Swelling was determined as maximal rate of absorption decrease at 540 nm (delta A/delta t). Surprisingly, delta A/delta t-values of mitochondria from AAF-fed rats were significantly lower (16.3 +/- 4.8 x 10(3)/min) than of mitochondria from control animals (32.7 +/- 4.1 x 10(3)/min; P < 0.02). In the presence of phosphate (15 mM), delta A/delta t-values of mitochondria from AAF-fed rats were even lower (10% of control). Moreover, the membrane potential which was dissipated rapidly by the PTP-inducer NOF (30 microM) at a Ca2+ concentration of 80 microM in mitochondria from control animals, remained constant in mitochondria of AAF-treated rats. We therefore propose that the regulation of the PTP is altered on chronic AAF- feeding. The increased resistance of mitochondria against permeability transition may alter the threshold for apoptosis and thus suppress apoptosis. We also discuss the role of epigenetic modifications in early stages of carcinogenesis.      

Invasive mechanical ventilation as a risk factor for acute kidney injury in the critically ill: a systematic review and meta-analysis

Introduction

Mechanical ventilation (MV) is commonly regarded as a risk factor for acute kidney injury (AKI) in the critically ill. We investigated the strength of this association and whether settings of tidal volume (Vt) and positive end-expiratory pressure (PEEP) affect the risk for AKI.

Methods

We performed a systematic review and meta-analysis using studies found by searching MEDLINE, EMBASE, and references in relevant reviews and articles. We included studies reporting on a relation between the use of invasive MV and subsequent onset of AKI, or comparing higher with lower Vt or PEEP and subsequent onset of AKI. All studies clearly stating that MV was initiated after onset of AKI were excluded. We extracted the proportion with and without MV and AKI. We included 31 studies on invasive MV.

Results

The pooled odds ratio (OR) for the overall effect of MV on AKI was 3.16 (95% CI 2.32 to 4.28, P <0.001). Nearly all subgroups showed that MV increases the risk for AKI. The pooled OR for studies with a multivariate analysis including MV as a risk factor for AKI was 3.58 (95% CI 1.85 to 6.92; P <0.001). Different settings of Vt and PEEP showed no effect.

Conclusions

Invasive MV is associated with a threefold increase in the odds of developing AKI and various Vt or PEEP settings do not modify this risk. The latter argues in favour of a haemodynamic origin of AKI during MV.     

Intracranial metastasis from prostatic adenocarcinoma simulating a meningioma

We report an unusual case of extra‐axial metastatic adenocarcinoma of the prostate that closely simulated a frontal, parasagittal, dural‐based meningioma. Such tumours, which satisfy several criteria for a diagnosis of meningioma, but which have proved instead to be metastatic adenocarcinoma of the prostate, form the focus of our report.     

Procaine in Cardioplegia: Does It Affect the Endothelial Function?

Objective: Cardioplegic solutions are widely used in cardiac surgery and hyperkelemia in cardioplegia has been demonstrated to impair the endothelium‐derived hyperpolarizing factor (EDHF)‐mediated endothelial function. The present study examined the effect of procaine in St. Thomas Hospital Cardioplegia on the EDHF‐mediated response in porcine coronary arteries. Methods: Isometric force study: Porcine coronary micro‐arteries were studied in a myograph. Two rings taken from the same artery (diameter 200–450 μm, n = 8 ) were incubated with Kreb's solution as control or Kreb's solution plus procaine (1 mM) at 37 °C for 1 h, respectively. The EDHF‐mediated relaxation was induced by bradykinin (BK, ?10 ～?6.5 log M) in the presence of indomethacin (Indo, 7 μM), NG‐nitro‐L‐arginine (L‐NNA, 300 μM), and hemoglobin (HbO, 20 μM) after U46619‐precontraction (?8 log M). Electrophysiological study: The membrane potential of a single smooth muscle cell in coronary arteries was measured by a microelectrode after superfusion with Kreb's solution or Kreb's containing procaine (1 mM) for 1  h. Results: Procaine had little effect on the resting force of porcine coronary micro‐arteries (0.94 ± 0.74 mN vs. 0.67 ± 0.23 mN in control, P > 0.05 ) and did not alter the U46619‐induced precontraction (10.7 ± 1.7 mN vs. 12.0 ± 1.7 mN, P > 0.05 ). The BK‐induced, EDHF‐mediated relaxation was increased by the treatment with procaine with the EC50 shifted leftward (97.3 ± 0.6% vs. 83.0 ± 5.1% at ?7 log M and 99.4 ± 0.6% vs. 96.7 ± 1.6% at ?6.5 log M, P < 0.05 ; EC50: ?8.57 ± 0.24 vs. ?7.92 ± 0.23 log M, P < 0.05 ). Procaine slightly depolarized the smooth muscle cell (?56.3 ± 1.0 vs. ?59.3 ± 0.7 mV, P > 0.05 ) and decreased the BK‐induced hyperpolarization from ?70.3 ± 0.4 mV to ?68.0 ± 0.8 mV (?7 log M, P < 0.05) and from ?72.3 ± 0.7 mV to ?68.8 ± 0.8 mV (?6.5 log M, P < 0.01) . Conclusions: In the coronary arteries, procaine has depolarizing effect but it enhances the EDHF‐mediated relaxation. Therefore, addition of procaine in cardioplegia may preserve the EDHF‐mediated endothelial function.     

The 47-kD fragment of talin is a substrate for protein kinase P

This laboratory has been characterizing protein serine/threonine kinase reactions of hematopoietic tissues, whose most distinguishing characteristics in vitro are stimulation with vesicular phosphatidyl glycerol, and the ability to function using Mn2+ as the sole divalent cation. The major protein substrates are a 73-kD protein and a protein migrating near ovalbumin on sodium dodecyl sulfate polyacrylamide gel electrophoresis. The 47-kD protein was partially purified from cells harvested by leukapheresis from a patient with acute myelogenous leukemia, using ammonium sulfate precipitation and ion exchange chromatography. This partially purified ion-exchange fraction contained an endogenous kinase activity with characteristics similar to those we previously described of protein kinase P (protein kinase, phospholipid- stimulable: PK-P), but not typical of any form of protein kinase C (PK- C). With longer phosphorylation, the 47-kD band showed increasingly lower mobility demonstrable both by Coomassie blue staining and autoradiography, suggesting both that it was multiply phosphorylated, and that the excisable band was pure. The protein was thus eluted from preparative gel slices and digested with endoproteinase lys C. Sequence data from the fragments identified the protein as the 47-kD calpain fragment of talin, a protein found in focal adhesion plaques and some cell-cell contacts. PK-C phosphorylated the 47-kD protein, as has been reported previously, and phosphopeptide mapping disclosed a similar pattern of phosphorylation using either PK-C or the endogenous activity. The 47-kD protein labeled with the endogenous kinase contained predominantly phosphoserine, with some phosphothreonine and a trace of phosphotyrosine. Intact, purified talin was also phosphorylated by PK-P in a phospholipid-stimulable manner, but at 1/20 the rate of the 47-kD fragment.     

基于PC Matlab平台的扩散张量参数的计算

本文介绍了在普通计算机上根据磁共振成像系统测量所得到的扩散张量数据计算扩散张量参数的方法,并且基于Matlab编程语言实现了目前应用较广的临床参数,如表观扩散系数、扩散张量的最大特征值、特征向量以及各向异型扩散系数FA等的计算.     

Haemodynamic parameters predicting variceal haemorrhage and survival in alcoholic cirrhosis

The relationship between the various haemodynamic abnormalities observed in cirrhosis and their prognostic value remains unclear. We report haemodynamic measurements on 96 patients with alcoholic cirrhosis (mean Childs-Pugh Score, CPS, 9.0 +/- 0.2, mean age 55.6 +/- 1.0 years) and assess their value in predicting variceal bleeding and death during a mean follow-up of 19.3 +/- 1.5 months. Baseline CPS correlated with hepatic venous pressure gradient (HVPG) (p = 0.001), azygos blood flow (p < 0.05), cardiac index (p < 0.05), and inversely with mean arterial pressure (p < 0.01) and systemic vascular resistance index (p < 0.05). Renal blood flow was not related to any haemodynamic parameter or CPS. Thirty-eight patients died during follow-up, and 16 had a variceal bleed. Death (p = 0.001) and variceal bleeding (p < 0.05) were more likely in patients with HVPG > 16 mmHg than in those with HVPG < 16 mmHg, and variceal bleeding was more likely in patients with HVPG > 12 mmHg (vs. HVPG < 12 mmHg, p < 0.05). HVPG also predicted death and variceal haemorrhage on univariate and multivariate analyses. No other haemodynamic parameter predicted death or bleeding. In alcoholic cirrhosis, severity of liver disease is related to HVPG, collateral blood flow and degree of systemic circulatory abnormalities. HVPG is a useful predictor of survival and variceal bleeding in these patients.      

NON-HODGKINS LYMPHOMA PRESENTING WITH EVIDENCE OF RIGHT VENTRICULAR OUTFLOW TRACT OBSTRUCTION

SUMMARY Anterior mediastinal tumours have been reported that initially presented with signs suggestive of cardiac disease. The widespread availability of two-dimensional echocardiography has demonstrated that, in the majority of cases, right ventricular compression is the major cardiac complication of such masses. We report two cases of mediastinal lymphoma that presented with chest pain and signs of right ventricular outflow obstruction.     

Large numbers of primitive stem cells are active simultaneously in aggregated embryo chimeric mice

The possibility has been repeatedly raised that erythropoiesis results from clonal succession--the differentiation of one or a very small number of the most primitive stem cells that are sequentially activated to proliferate forming clones of differentiated cells and then eventually decline, to be replaced by new stem cell clones. We studied this possibility in chimeric mice made by combining embryos from two different strains so that they would have two distinct stem cell populations, each of which produces a different hemoglobin type (d and s). These were compared with F1 hybrids in which every stem cell produces both types. We measured the percentage of type d in seven to ten serial samples of circulating reticulocytes taken at three- to seven-day intervals and found that the variability in percent of this hemoglobin was only slightly higher in the chimeric mice than in F1 controls; SD ranged from 2.7% to 5.5% in the chimeric mice and from 3.4% to 3.9% in the controls. Using the binomial formula, the numbers of new clones formed during the reticulocyte life span, approximately three days, ranged from 33 to 118 in the individual chimeric mice. However, these numbers are underestimates because estimated numbers of clones depend inversely on variabilities, and the calculations did not exclude the contribution of experimental error to the overall variability. Total percentages of type d hemoglobin were also measured in seven to nine successive serial samples at 60- to 136-day intervals. These gave mean values similar to measures of newly synthesized hemoglobin in the same mice, but SD were larger, ranging from 5.3% to 8.4%. This reflects experimental error, both because of excess day-to- day variability found in this type of measurement and because there could not be fewer primitive stem cells activated to form clones of erythrocytes during the 45-day erythrocyte life span than during the three-day life span of reticulocytes. Since most and maybe all of the variation between successive samples in the same chimeric mouse appear to result from experimental error, many or even all of the primitive stem cells may simultaneously contribute to erythropoiesis.