Deregulated Chromatin Remodeling in the Pathobiology of Brain Tumors

Brain tumors encompass a heterogeneous group of malignant tumors with variable histopathology, aggressiveness, clinical outcome and prognosis. Current gene expression profiling studies indicate interplay of genetic and epigenetic alterations in their pathobiology. A central molecular event underlying epigenetics is the alteration of chromatin structure by post-translational modifications of DNA and histones as well as nucleosome repositioning. Dynamic remodeling of the fundamental nucleosomal structure of chromatin or covalent histone marks located in core histones regulate main cellular processes including DNA methylation, replication, DNA-damage repair as well as gene expression. Deregulation of these processes has been linked to tumor suppressor gene silencing, cancer initiation and progression. The reversible nature of deregulated chromatin structure by DNA methylation and histone deacetylation inhibitors, leading to re-expression of tumor suppressor genes, makes chromatin-remodeling pathways as promising therapeutic targets. In fact, a considerable number of these inhibitors are being tested today either alone or in combination with other agents or conventional treatments in the management of brain tumors with considerable success. In this review, we focus on the mechanisms underpinning deregulated chromatin remodeling in brain tumors, discuss their potential clinical implications and highlight the advances toward new therapeutic strategies.     

Description of response to aspirin and clopidogrel in outpatients with coronary artery disease using multiple electrode impedance aggregometry

Identification of outpatients with high platelet reactivity (HPR) on antiplatelet treatment is an unmet need. The present study was conducted in healthy individuals (n = 50) and in outpatients with coronary artery disease (CAD) at a distance from the acute ischemic episode (aspirin group, n = 71; aspirin/clopidogrel group, n = 106). We studied the feasibility and the precision of whole blood multiple electrode aggregometry (MEA) after triggering platelet aggregation by arachidonic acid or adenosine diphospate (ADP). The MEA can be performed on whole blood within 2 hours after sample venipuncture. The threshold for the diagnosis of HPR is situated at 55 and 50 U for the arachidonic acid and ADP test, respectively. Frequency of HPR was 7% and 20% in aspirin and aspirin/clopidogrel groups, respectively. In 3.8% of patients in aspirin/clopidogrel group, combined HPR on aspirin and clopidogrel was found. In outpatients with CAD, use of MEA is feasible for the diagnosis of HPR.     

A Novel Model of Urinary Tract Differentiation,Tissue Regeneration,and Disease: Reprogramming Human Prostate and Bladder Cells into Induced Pluripotent Stem Cells

Background

Primary culture and animal and cell-line models of prostate and bladder development have limitations in describing human biology, and novel strategies that describe the full spectrum of differentiation from foetal through to ageing tissue are required. Recent advances in biology demonstrate that direct reprogramming of somatic cells into pluripotent embryonic stem cell (ESC)-like cells is possible. These cells, termed induced pluripotent stem cells (iPSCs), could theoretically generate adult prostate and bladder tissue, providing an alternative strategy to study differentiation.

Objective

To generate human iPSCs derived from normal, ageing, human prostate (Pro-iPSC), and urinary tract (UT-iPSC) tissue and to assess their capacity for lineage-directed differentiation.

Design, setting, and participants

Prostate and urinary tract stroma were transduced with POU class 5 homeobox 1 (POU5F1; formerly OCT4), SRY (sex determining region Y)-box 2 (SOX2), Kruppel-like factor 4 (gut) (KLF4), and v-myc myelocytomatosis viral oncogene homolog (avian) (MYC, formerly C-MYC) genes to generate iPSCs.

Outcome measurements and statistical analysis

The potential for differentiation into prostate and bladder lineages was compared with classical skin-derived iPSCs. The student t test was used.

Results and limitations

Successful reprogramming of prostate tissue into Pro-iPSCs and bladder and ureter into UT-iPSCs was demonstrated by characteristic ESC morphology, marker expression, and functional pluripotency in generating all three germ-layer lineages. In contrast to conventional skin-derived iPSCs, Pro-iPSCs showed a vastly increased ability to generate prostate epithelial-specific differentiation, as characterised by androgen receptor and prostate-specific antigen induction. Similarly, UT-iPSCs were shown to be more efficient than skin-derived iPSCs in undergoing bladder differentiation as demonstrated by expression of urothelial-specific markers: uroplakins, claudins, and cytokeratin; and stromal smooth muscle markers: α-smooth-muscle actin, calponin, and desmin. These disparities are likely to represent epigenetic differences between individual iPSC lines and highlight the importance of organ-specific iPSCs for tissue-specific studies.

Conclusions

IPSCs provide an exciting new model to characterise mechanisms regulating prostate and bladder differentiation and to develop novel approaches to disease modelling. Regeneration of bladder cells also provides an exceptional opportunity for translational tissue engineering.     

Laparoscopic adrenalectomy in patients with subclinical Cushing syndrome

Background

Subclinical Cushing syndrome in patients with adrenal incidentalomas has been associated with an increased prevalence of the metabolic syndrome and cardiovascular risk. The management of these patients, be it conservative or surgical, is still debated, but there is accumulating evidence that surgery is best and that laparoscopic adrenalectomy, when possible, is the most preferred procedure. Here we present the short- and long-term results of laparoscopic adrenalectomy for subclinical Cushing syndrome and determine the effect of this procedure on components of the metabolic syndrome.

Methods

Twenty-nine patients, 8 men and 21 women with adrenal incidentalomas and subclinical Cushing syndrome who underwent laparoscopic adrenalectomy, were studied retrospectively. They had undergone postoperative follow-up for improvement or worsening of their arterial blood pressure, body weight, and fasting glucose level for a mean period of 77 months.

Results

Preoperatively, 17 patients (58.6 %) had arterial hypertension, 14 (48.3 %) had a body mass index exceeding 27 kg/m², and 12 (41.4 %) had diabetes mellitus. Postoperatively, a decrease in mean arterial pressure was found in 12 patients (70.6 %), a decrease in body mass index in 6 patients (42.9 %), and an improvement in glycemic control in 5 patients (41.7 %).

Conclusions

Laparoscopic adrenalectomy is beneficial in many patients with subclinical Cushing syndrome because it reduces arterial blood pressure, body weight, and fasting glucose levels. Prospective randomized studies are needed to compare laparoscopic adrenalectomy with a conservative approach and to confirm these results.     

Intravenous morphine attenuates pain induced changes in skin blood flow in newborn infants

Abstract

In a previous study we found that pain and discomfort caused a marked increase in skin blood flow, in newborn infants, and that skin blood flow decreased after morphine. In this study we tested morphine effect on the skin blood flow response to pain more systematically. Skin blood flow was measured using a laser Doppler technique during 19 percutaneous central venous catheter placements in 18 infants, 10 of whom received intravenous morphine premedication. The mean ± SD baseline skin blood flow was similar between the two groups: 22.5±9.5 ml 100 g-7 m/n-7 in the morphine group, and 23.7± 8.0 ml TOO g~1 min~1 in the no-morphine group, respectively (p = n.s.). During PCVC placement in the morphine treated group, skin blood flow remained low with minimal variability. The mean value was 22.6 ±7.7 ml 100 g~1 min(p = n.s. compared to baseline). In 7/9 infants not treated with morphine skin blood flow increased dramatically during PCVC placement; while in two it did not. But the mean skin blood flow in this group of 9 infants during PCVC placement was 45.3 ±34 ml 100 g~1 min~ \ an overall change of 97% increase from the baseline. This was statistically significant compared with the baseline and the morphine group value during PCVC insertion (p< 0.04). During the 45 min time period after PCVC placement, skin blood flow values between groups again were similar. We conclude that morphine pretreatment for PCVC placement minimizes pain-associated increases in skin blood flow. The issue of whether skin blood flow changes could serve as measures of adequate analgesia needs to be evaluated with further studies. [Neurol Res 1996; 18: 440-444]     

Recurrent episodes of rhabdomyolysis in pontocerebellar hypoplasia type 2

Pontocerebellar hypoplasia type 2 is an autosomal recessive disorder characterized by hypoplasia and atrophy of the cerebellum and pons, leading to microcephaly, dystonia/dyskinesia, seizures, and severe cognitive impairment. Until lately it was considered a CNS-refined disease, but recent reports have associated it with muscular defects, as well. A 5-year-old boy with genetically confirmed pontocerebellar hypoplasia type 2 is described. The patient had all the clinical and radiological features of the disease, but he, additionally, exhibited two episodes of rhabdomyolysis precipitated by respiratory infections. The possible mechanisms associating encephalopathy and myopathy in pontocerebellar hypoplasia type 2 are discussed.