Preclinical evaluation of statins as a treatment for ovarian cancer.

OBJECTIVE: To evaluate the potential for statins to treat ovarian cancer. METHODS: The sensitivity of 7 ovarian cancer cell lines to either statins or statins combined with either carboplatin or paclitaxel was assessed using monolayer cultures. Sensitivity to simvastatin was also evaluated in ovarian cancer spheroids. The kinetics of cell death induced by simvastatin was evaluated by measuring Trypan Blue exclusion. Autophagy induced by simvastatin was assessed by measuring LC3-II, p62 or Rab7 by immunoblotting or immunocytochemistry. RESULTS: All statins except pravastatin demonstrated single agent activity against monolayers (IC50=1-35 µM) and spheroids (IC50=1-13 µM). This was mediated by HMG-CoAR inhibition, because either mevalonate or geranylgeraniol prevented the cytotoxic effects of simvastatin. Continuous exposure for 4 days was necessary to cause cell death. Simvastatin caused accumulation of p62 but loss of Rab7, suggesting inhibition of autophagosome trafficking. Accumulation of LC3-II was also observed, even in the presence of bafilomycin, suggesting additional stimulation of an earlier step in autophagy. Knockdown of the key autophagy regulator Atg5 caused a modest increase in the sensitivity of Ovcar-8 cells to simvastatin. Finally, additive or mild antagonist effects were observed when simvastatin was combined simultaneously with either carboplatin or paclitaxel, but when cells were exposed to simvastatin prior to carboplatin, profound antagonism was observed. CONCLUSIONS: These observations suggest that clinical trials of statins in ovarian cancer should evaluate high doses and schedules that ensure continual inhibition of HMG-CoAR. Simvastatin has conflicting effects on the autophagy pathway and this may contribute to its cytotoxic activity.

Thermal damage to red cells.

Erythrocytes from a burned patient show a temporal sequence of morphological changes. Immediate severe changes occur which are followed by a transient phase only of less abnormal morphology. Heating whole blood in vitro to 49 degrees C instead of 50 degrees C does not show the expected dose response curve. Heating whole blood in vitro to 50 degrees C induces progressive morphological changes. Fractionation of whole blood and subsequent heating to 48 degrees C show the older cells to be less deformable.

Optimization and phase transitions in a chaotic model of data traffic.

Ohira and Sawatari [Phys. Rev E 58, 193 (1998)] introduced a simple model for a packet-switching network which was extended by Solé and Valverde [Physica A 289, 595 (2001)]. Both models used Poisson-like traffic sources. Solé and Valverde demonstrated that long-range dependence (LRD) in autocorrelation behavior can be seen in the queue length dynamics at a given node. Actual network traffic sources are known to exhibit long-range autocorrelation. To simulate the real case more closely, we have studied the effect of introducing LRD behavior at an earlier stage. We replaced the Poisson-like sources with LRD sources, modeled using chaotic maps. As was seen in the previous models, a phase transition occurs as the traffic load on a network is increased and the network changes to a congested state where the time taken for delivery of packets increases dramatically and throughput collapses. The paper reports extensive numerical results from our simulations using both Poisson and LRD sources. It demonstrates the natural network-induced LRD when sources are purely Poisson and shows strong enhancement when LRD sources are added. The model is adapted to include congestion control mechanisms and their impact is considered.

Radiologic appearance of stress fractures.

The large numbers of Americans involved in sports and physical activities have made stress fractures a more common injury to the lower extremities than before. Presented are the typical radiographic and scintigraphic appearances of stress fractures and the appropriate medical imaging with which to diagnose this entity.

Characterisation of two tomato fruit-expressed cDNAs encoding xyloglucan endo-transglycosylase.

Xyloglucan endo-transglycosylase (XET) catalyses the cleavage and concomitant transfer of one xyloglucan molecule to another. It is thought to be an important component of cell wall metabolism, particularly in expanding tissue and ripening fruits. The recently reported cloning of a cDNA encoding a seed-expressed XET from nasturtium [9] has enabled two XET-encoding cDNAs to be isolated from a tomato fruit (breaker stage) cDNA library. Their deduced amino acid sequences exhibit ca. 40% identity to nasturtium XET. One of the tomato cDNA clones (tXET-B2) was over-expressed in Escherichia coli; following purification and refolding, the recombinant protein was shown to have XET activity, with no detectable hydrolytic activity. Southern hybridisation analysis suggests that these clones are members of a small multi-gene family encoding tomato XET. Ribonuclease protection assays show that transcripts protected by one of the clones (tXET-B1) are most abundant in pink fruit pericarp and were also detected in stems.

Clinical, haemodynamic, rheological, and biochemical findings in 126 patients with intermittent claudication.

Increased blood viscosity has been shown to be an important factor in reducing blood flow in a review and analysis of the history, clinical findings, and haemodynamic, rheological, radiological, and biochemical measurements in 126 patients with intermittent claudication. In some patients increased viscosity seemed to be the determining cause of claudication. A raised plasma fibrinogen was the most common single biochemical abnormality. The results of conventional serum lipid and lipoprotein estimations were abnormal in the series as a whole but did not correlate with clinical findings or flow measurements at individual patient level. There was, however, a significant correlation between some clinical findings and the susceptibility of the red cells to autoxidation.

Prognostic significance of rheological and biochemical findings in patients with intermittent claudication.

To assess the prognostic significance of clinical and laboratory findings in intermittent claudication a group of 62 untreated patients was followed up in detail for periods of from one to three years. There was a significant correlation between progressive deterioration of the peripheral circulatory disturbance and the initial blood viscosity, the plasma fibrinogen level, and the susceptibility of red cell lipids to autoxidation.

Molecular characterization of a xyloglucan-specific endo-(1-->4)-beta-D-glucanase (xyloglucan endo-transglycosylase) from nasturtium seeds.

A novel xyloglucan-specific endo-(1-->4)-beta-D-glucanase, involved in the post-germinative mobilization of xyloglucan storage reserves, has previously been isolated from nasturtium (Tropaeolum majus L.) seed. Its mode of action has been shown, in vitro, to be one of transglycosylation except at low substrate (glycosylacceptor) concentrations when hydrolysis predominates. Here it is shown that this nasturtium seed xyloglucan endo-transglycosylase is encoded by a single gene which is transcribed and processed to a 1.5 kb mRNA. The isolation and DNA sequence analysis of a cDNA copy of the nasturtium xyloglucan endo-transglycosylase transcript is described. The cDNA encodes a 33.5 kDa precursor polypeptide which is subsequently processed to a 31 kDa mature protein. The precursor incorporates an N-terminal signal sequence which probably contains information relevant to the targeting of the enzyme to the cell wall. The computer-predicted isoelectric point (5.14) and low (approximately 0%) alpha-helix content of the deduced mature protein are in excellent agreement with the experimental data obtained using the purified enzyme. The deduced protein sequence lacks homology with known plant endo-(1-->4)-beta-D-glucanases, consistent with the unique properties of the enzyme. Database searches have revealed that a Brassica protein (meri-5) of previously unknown function, but abundantly expressed in expanding tissue, shares structural identity with the nasturtium xyloglucan endo-transglycosylase. The expression of a xyloglucan endo-transglycosylase in expanding tissue would be consistent with the contention that enzymes of this type are involved in cell wall loosening.