Combined inhibition of DNA methyltransferase and histone deacetylase restores caspase-8 expression and sensitizes SCLC cells to TRAIL

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a promising drug for the treatment of tumors; however, a number of cancer cells are resistant to this cytokine. Among the mechanisms of resistance of small cell lung carcinomas (SCLCs) to TRAIL is the lack of caspase-8 expression. Although methylation of the caspase-8 promoter has been suggested as the main mechanism of caspase-8 silencing, we showed that reduction of the enzymes involved in DNA methylation, DNA methyltransferases (DNMT) 1, 3a and 3b, was not sufficient to significantly restore caspase-8 expression in SCLC cells, signifying that other mechanisms are involved in caspase-8 silencing. We found that combination of the DNMT inhibitor decitabine with an inhibitor of histone deacetylase (HDAC) significantly increased caspase-8 expression in SCLC cells at the RNA and protein levels. Among all studied HDAC inhibitors, valproic acid (VPA) and CI-994 showed prolonged effects on histone acetylation, while combination with decitabine produced the most prominent effects on caspase-8 re-expression. Moreover, a significant reduction of survivin and cIAP-1 proteins level was observed after treatment with VPA. The combination of two drugs sensitized SCLC cells to TRAIL-induced apoptosis, involving mitochondrial apoptotic pathway and was accompanied by Bid cleavage, activation of Bax, and release of cytochrome c. Both initiator caspase-8 and -9 were required for the sensitization of SCLC cells to TRAIL. Thus, efficient restoration of caspase-8 expression in SCLC cells is achieved when a combination of DNMT and HDAC inhibitors is used, suggesting a combination of decitabine and VPA or CI-994 as a potential treatment for sensitization of SCLC cells lacking caspase-8 to TRAIL.     

When Initial Postexcision PTH Level Does Not Fall Appropriately During Parathyroidectomy: What to Do Next?

Background  Inadequate fall in the intraoperative parathyroid hormone (PTH) level after removing enlarged parathyroid gland(s) typically signifies additional hyperfunctioning gland(s), prompting further neck dissection, but it may also be a false negative result. We analyzed intraoperative management of patients with an inadequate fall on PTH after excision of enlarged parathyroid gland(s). Methods  Analysis involved a prospective database of 189 patients undergoing 193 procedures for primary hyperparathyroidism. The PTH level was determined before neck incision and 10–15 min after excision of enlarged parathyroid gland(s). A PTH decrease > 50% and into normal range was used as the criterion of successful parathyroidectomy. Results  In 48 of 193 operations, initial postexcision PTH level did not fall appropriately. That inadequate fall in PTH level was a false negative result in 16 patients (33%) and cure was achieved without additional neck exploration in all but one patient, who had additional (negative) neck exploration after excision of a parathyroid adenoma. In all patients with false negative postexcision PTH assay, operative findings concurred with preoperative imaging tests. Conclusions  Inadequate fall in intraoperative PTH may be false negative, particularly after removal of an adenoma found in the location determined by preoperative imaging. Repeat PTH may confirm the initial assay as false negative, obviating the need for additional neck dissection. Importantly, if repeat PTH does not fall appropriately, additional neck exploration needs to be performed. Some of the results reported here were part of an oral presentation at the 88th Annual Meeting of the New England Surgical Society, Burlington, VT, September 29, 2007.     

Herpes simplex virus (HSV) pneumonia in a heart transplant: diagnosis and therapy

Organ transplants are frequently complicated by viral infections. The period of maximum immunosuppression, 1 to 6 months posttransplantation, predisposes one to intracellular pathogens. The most common intracellular viral pathogens in transplant recipients include cytomegalovirus (CMV), herpes simplex virus (HSV), and respiratory syncytial virus (RSV). Cytomegalovirus and HSV are common viral pathogens in the early transplant period (0-1 month posttransplant). Although respiratory syncytial virus commonly presents in the late posttransplant period (> or =6 months posttransplant), HSV pneumonia may be acquired in organ transplants by endogenous reactivation caused by immunosuppression or may be introduced from colonized oropharyngeal secretions into the lower respiratory tract during intubation in patients on ventilators. In ventilated patients without severe preexisting lung disease, HSV pneumonia presents with otherwise unexplained profound/prolonged hypoxemia or "failure to wean." As other viral pneumonias, HSV pneumonia is characterized by profound hypoxemia requiring a high FIo(2), and a highly increased A-a gradient (> or =30). These findings are indicative of an oxygen diffusion defect typical of noninfectious (eg, sarcoidosis) or infectious disorders (eg, HSV, cytomegalovirus, respiratory syncytial virus, Pneumocystis (carinii) jiroveci pneumonia) primarily affecting the interstitium of the lung. We present a case of HSV pneumonia in a heart transplant recipient and include a review of the clinical presentation, diagnostic findings, and therapy of HSV pneumonia.     

Effect of Nitric Oxide on Mechanoelectric Feedback in Rat Right Atrium

In situ microelectrode examination of rat right atrium showed that in physiologically prestretched tissue, NO donor SNAP modifies the repolarization phase of cardiomyocyte AP in a “hump-like” way provoking the development of arrhythmia. Gadolinium both prevents and eliminates this effect attesting to involvement of stretch-activated channels in the development of NO-induced abnormalities. Elevation of SNAP concentration or further stretch of the tissue (presumably, it increases NO concentration) eliminated the hump depolarization induced by moderate SNAP stimulation. Thus, low NO opens the stretch-activated channels while high NO inactivates them.     

Oxidative changes of bronchoalveolar proteins in cystic fibrosis

Chronic bacterial infection and severe, polymorphonuclear neutrophil-dominated endobronchial inflammation are characteristic hallmarks of cystic fibrosis (CF) lung disease. The free radicals generated can be deleterious for structure and function of many proteins. The goal of this study was to investigate the degree of oxidation of pulmonary epithelial lining fluid proteins. BAL fluid (BALF) from 55 children with CF and from 11 patients in a control group were investigated by dot-blot assay for content and by two-dimensional electrophoresis and Western blotting for the pattern of distribution of oxidized proteins. The highest level of oxidative stress, as assessed by the level of protein carbonyls, was found in patients with FEV1 < 80% of predicted or with highly elevated neutrophil counts. Compared to control subjects without lung disease, CF patients with normal lung function and CF patients with a normal neutrophil count in their BALF had significantly higher protein carbonyl levels. The extent of protein oxidation was directly related to the neutrophil granulocyte count and inversely to lung function. Our data support the hypothesis that oxidative damage of pulmonary proteins during chronic and excessive neutrophilic endobronchial inflammation may contribute to the decline of lung function in CF patients.     

Exposure from the Chernobyl accident had adverse effects on erythrocytes,leukocytes, and,platelets in children in the Narodichesky region,Ukraine: A 6-year follow-up study

Background  

After the Chernobyl nuclear accident on April 26, 1986, all children in the contaminated territory of the Narodichesky region, Zhitomir Oblast, Ukraine, were obliged to participate in a yearly medical examination. We present the results from these examinations for the years 1993 to 1998. Since the hematopoietic system is an important target, we investigated the association between residential soil density of ¹³⁷Caesium (¹³⁷Cs) and hemoglobin concentration, and erythrocyte, platelet, and leukocyte counts in 1,251 children, using 4,989 repeated measurements taken from 1993 to 1998.     

Main Regularities of Mutual Location of Different Pacemaker Cells in the Rat Heart Sinoatrial Node

The distribution of pacemaker cells and atrial working cardiomyocytes in the anterior right atrial wall was studied using intracellular glass microelectrodes under conditions of shortterm culturing. It was shown that the dominant pacemaker region and the functional tail are located in the lateral area of the central part of the sinoatrial node, while the medial area is occupied by latent pacemaker cells.     

Helicobacter pylori upregulates prion protein expression in gastric mucosa： A possible link to prion disease

AIM: Pathological prion protein (PrPSC) is responsible for the development of transmissible spongiform encephalopathies (TSE). While PrPc enters the organism via the oral route, less data is available to know about its uptake and the role of gastrointestinal inflammation on the expression of prion precursor PrPc, which is constitutively expressed in the gastric mucosa. METHODS: We studied PrPc expression in the gastric mucosa of 10 Helicobacter pylori-positive patients before and after successful H pylori eradication compared to non-infected controls using RT-PCR and Western blotting. The effect of central mediators of gastric inflammation, i.e., gastrin, prostaglandin E2 (PGE2), tumor necrosis factor alpha (TNF-α) and interleukin 1 beta (IL-1β) on PrPc expression was analyzed in gastric cell lines. RESULTS: PrPc expression was increased in H pylori-infection compared with non-infected controls and decreased to normal after successful eradication. Gastrin, PGE2, and IL-1β dose-dependently upregulated PrPc in gastric cells, while TNF-α had no effect. CONCLUSION: H pylori infection leads to the upregula-tion of gastric PrPc expression. This can be linked to H pylori induced hypergastrinemia and increased mucosal PGE2 and IL-1β synthesis. H pylori creates a milieu for enhanced propagation of prions in the gastrointestinal tract.     

Structured versus narrative reporting of pelvic MRI in perianal fistulizing disease: impact on clarity,completeness, and surgical planning

Abdominal Radiology - To evaluate clarity, completeness, and impact on surgical planning of MRI reporting of perianal fistulizing disease using a structured disease-specific template versus...