Effects of granulocyte-macrophage colony-stimulating factor on 3'-azido-3'-deoxythymidine uptake, phosphorylation and nucleotide retention in human U-937 cells

Previous studies have demonstrated that granulocyte-macrophage colony-stimulating factor (GM-CSF) both increases and decreases levels of 3'-azido-3'-deoxythymidine (AZT) nucleotides in certain human myeloid cells. The present studies have examined the effects of GM-CSF on AZT metabolism in U-937 cells. The results demonstrate that GM-CSF stimulated AZT nucleotide formation in these cells. This stimulation was detectable during concurrent exposure to GM-CSF and AZT or as a result of pretreatment with GM-CSF. The GM-CSF-induced enhancement in AZT nucleotide formation was associated with a 4-fold increase in AZT uptake. The finding that uptake of AZT into U-937 cells was only partially sensitive to 6-[(4-nitrobenzyl)thio]-9-beta-D-ribofuranosylpurine (NBMPR) suggested a process primarily involving nonfacilitated diffusion. The results also demonstrate that treatment of U-937 cells with GM-CSF was associated with nearly a 2-fold increase in thymidine kinase activity. Moreover, the findings indicate that retention of AZT-MP and AZP-TP was prolonged significantly (P less than 0.05 and P less than 0.01 respectively) in association with GM-CSF treatment. Taken together, these results suggest that GM-CSF enhances the formation of AZT nucleotides by increasing AZT uptake and phosphorylation, as well as increasing retention of phosphorylated derivatives.     

Distribution of glutathione S-transferase isoenzymes in human kidney: basis for possible markers of renal injury.

To determine whether the tissue distribution of glutathione S-transferase (GST) isoenzymes could define the precise nature of renal injury, 13 adult kidneys were studied, using specific antibodies raised against purified isoenzymes. Basic GST stained strongly proximal convoluted tubules and some medullary tubules; acidic GST stained strongly distal convoluted tubules and medullary tubules; neutral GST stained similarly to acidic GST, but weaker, and microsomal GST stained glomerular and interstitial endothelium and collecting ducts deep in the medulla, although there was considerable variation in staining intensity among cases. It is suggested that the measurement of these isoenzymes in serum and urine may help to elucidate the localisation of tissue damage, which may be particularly valuable in patients with cyclosporine toxicity following renal transplantation.     

Dynamic changes in injured myocardium,very early after acute myocardial infarction,quantified using T1 mapping cardiovascular magnetic resonance

Background

It has recently been suggested that myocardial oedema follows a bimodal pattern early post ST-segment elevation myocardial infarction (STEMI). Yet, water content, quantified using tissue desiccation, did not return to normal values unlike oedema quantified by cardiovascular magnetic resonance (CMR) imaging. We studied the temporal changes in the extent and intensity of injured myocardium using T1-mapping technique within the first week after STEMI.

Methods

A first group (n?=?31) underwent 3 acute 3?T CMR scans (time-point (TP) <?3?h, 24?h and 6?days), including cine, native shortened modified look-locker inversion recovery T1 mapping, T2* mapping and late gadolinium enhancement (LGE). A second group (n?=?17) had a single scan at 24?h with an additional T2-weighted sequence to assess the difference in the extent of area-at-risk (AAR) compared to T1-mapping.

Results

The mean T1 relaxation time value within the AAR of the first group was reduced after 24?h (P?<?0.001 for TP1 vs.TP2) and subsequently increased at 6?days (P?=?0.041 for TP2 vs.TP3). However, the extent of AAR quantified using T1-mapping did not follow the same course, and no change was detected between TP1&TP2 (P?=?1.0) but was between TP2 &TP3 (P?=?0.019). In the second group, the extent of AAR was significantly larger on T1-mapping compared to T2-weighted (42?±?15% vs. 39?±?15%, P?=?0.025). No change in LGE was detected while microvascular obstruction and intra-myocardial haemorrhage peaked at different time points within the first week of reperfusion.

Conclusion

The intensity of oedema post-STEMI followed a bimodal pattern; while the extent of AAR did not track the same course. This discrepancy has implications for use of CMR in this context and may explain the previously reported disagreement between oedema quantified by imaging and tissue desiccation.

     

Epigenetic histone modifications in a clinically relevant rat model of chronic ethanol-binge-mediated liver injury

Purpose

Ethanol binge augments liver injury after chronic ethanol consumption in humans, but the mechanism behind the enhanced liver injury by ethanol binge is not known. In this study we used a clinically relevant rat model in which liver injury is amplified by binge after chronic ethanol treatment and investigated the importance of histone modifications.

Methods

Eight-week-old Sprague-Dawley rats were fed ethanol in a liquid diet for 4 weeks. Control rats were fed an isocaloric liquid diet. This was followed by three binge administrations of ethanol (intragastric 5 g/kg body weight, 12 h apart). In the control, ethanol was replaced by water. Four hours after the last binge administration, liver samples were analyzed for histone modifications and parameters of liver injury.

Results

Chronic ethanol administration alone caused an increase in histone H3 ser10 and ser28 (H3S10 or S28) phosphorylation, and binge ethanol reduced their levels. Levels of dually modified phosphoacetylated histone H3 (H3AcK9/PS10) increased after acute binge ethanol and remained same after chronic ethanol binge. In contrast, histone H3 lysine-9 acetylation (H3AcK9) was not increased after chronic ethanol but increased significantly after acute binge and chronic ethanol binge. Increase in histone acetylation was accompanied by increased phospho-ERK1/2 in the nuclear extracts. Increased acetylation after chronic ethanol binge was also accompanied by increased protein levels of GCN5 histone acetyl transferase and a modest increase in HDAC3 in the nucleus. Histone lysine-9 dimethylation was significantly increased after chronic ethanol binge. Chronic ethanol binge also resulted in a decrease in the SAM:SAH ratio with a relative decrease of SAM levels and a corresponding increase in SAH levels.

Conclusions

Ethanol binge after chronic ethanol altered the profile of site-specific histone modifications and may underlie the mechanism of augmented liver injury by chronic-ethanol-binge-treated rats.

     

Atrial Myxoma-Related to Chronic Immunosuppression: A case report

Although rare, atrial myxoma is the most common primary tumour of the heart. Its relation to immunosuppression in solid organ transplant is presently debateable. We report the case of a 71-year-old male patient who underwent renal transplant 17 years prior. Since that time he continued high dose immunosuppression without physician consultation and presented to us with atrial myxoma and its complications raising the question of any association between immunosuppression and the development of atrial myxoma.     

A case of poly-parasitism involving a trematode and four different nematodes in a migrant from Bihar

Reported is a case of seven-year-old, migrant from Bihar state, infested with Fasciolopsis buski Strongyloides stercoralis Ascaris lumbricoides, Trichuris trichiura and Ankylostoma duodenale in feces. Patient responded to treatment with piperazine, thiabendazole and albendazole, the importance of considering multiple and non-endemicparasite infestations in migrant of poor socio-economic background is emphasized.