Autogenous arteriovenous elbow fistula for haemodialysis and upper extremity ischemia

BACKGROUND: The autogenous brachiocephalic or brachiobasilic arteriovenous elbow fistula is not considered to be only the secondary haemodialysis access. In patients with an unsuitable forearm vessel bundle, it is indicated as primary access and it is the method preferred to the fistula creation using a vascular prosthesis. Its rather rare complication is the development of upper extremity ischemia. AIM: To summarise current knowledge of this fistula type and its associated complications METHODS: Review of the literature. RESULTS: The creation and maturation of the fistula and occurrence of the steal syndrome is influenced by a number of factors. The analysis and awareness of such factors will provide for creation of a suitable fistula as well as for timely complication diagnostics and treatment. CONCLUSIONS: The autogenous elbow fistula utilising the brachial artery and the cephalic or basilic vein in the upper extremity represents a high-quality haemodialysis access. Its potential complication is the occurrence of the steal syndrome. Its occurrence and manifestations do not constitute indications for ligation of the access. The gathered information shows that a suitable surgical procedure can help meet the basic rule for haemodialysis access--resolving the ischemia and maintaining the access.     

Peripheral T-cell lymphoma, unspecified--the analysis of the data from the Czech Lymphoma Study Group (CLSG) registry

BACKGROUND: Peripheral T-cell lymphoma, unspecified (PTCL-US) is one of the entities from the infrequent family of nodal mature T-cell lymphomas. The clinical course is aggressive, and despite multiagent chemotherapy, the median survival is about 2 years. Published data are limited to retrospective, mostly single-center studies or reviews and usually include more lymphoma subtypes. AIM: To evaluate the current treatment modalities, clinical outcome and prognostic factors in unselected, new diagnosed patients with PTCL-US in the population of the central european region (Czech Republic). METHOD: Czech Lymphoma Study Group is a national scientific organization which provides an on-line database registry which collects a data about almost all new diagnosed lymphoma patients since year 2000. All diagnostic biopsies were reviewed by a reference pathologist. RESULTS: We analyzed 63 patients with new diagnosis of PTCL-US. The median age was 59 years (25-81), chemotherapy (CHT) was administered in 56 of the 63 patients: anthracyclin-based CHT in 51%, intensive CHT in 21% and non-anthracyclin regimen was applied in 13% of the patients. The overall response rate was 74.4%, (CR in 57.4%). After a median follow-up of 19.6 months, 41% of the patients were in CR, 3.4% in PR or stable disease and 55% of the patients died. The estimated survival probability in 3 years was 36%. Clinical stage (IV) and CR achievement were found to be independent survival predictors in a multivariate analysis. CONCLUSIONS: Although the current treatment modalities are mostly ineffective in PTCL-US, appropriate intensive treatment may lead to prolonged remission but not survival.     

Cytotoxicity of colchicine derivatives in primary cultures of human hepatocytes

BACKGROUND: Colchicine has been used to treat gout for centuries. However, owing to its toxicity it displays a variety of side effects. The replacement of colchicine by less toxic but still active derivatives would solve this drawback. AIM: The aim of this study was to examine the cytotoxicity of 17 colchicine derivatives. METHODS: Primary cultures of human hepatocytes were the model of choice. Prior to testing, we measured the biochemical parameters of liver donors and the toxicological response of the hepatocytes cultures. For toxicity testing, cells were treated for 24 h with tested compounds in concentrations 1-100 microM. We monitored lactate dehydrogenase (LDH) leakage into the medium, mitochondrial activity (MTT test) and secretion of albumin. RESULTS: Our data show that LDH and MTT were less sensitive parameters compared to albumin secretion for monitoring the toxicity of colchicine derivatives. Compounds with lower antimitotic activity displayed lowered toxicity. CONCLUSION: Since human hepatocytes in culture are quiescent cells, they are not as susceptible to tropolone alkaloids as proliferating cells. Screening for colchicine derivatives with lowered cytotoxicity revealed that 10-O-demethylated compounds might be the substances of choice.     

Interleukin 6 signaling regulates promyelocytic leukemia protein gene expression in human normal and cancer cells

Tumor suppressor PML is induced under viral and genotoxic stresses by interferons and JAK-STAT signaling. However, the mechanism responsible for its cell type-specific regulation under non-stimulated conditions is poorly understood. To analyze the variation of PML expression, we utilized three human cell types, BJ fibroblasts and HeLa and U2OS cell lines, each with a distinct PML expression pattern. Analysis of JAK-STAT signaling in the three cell lines revealed differences in levels of activated STAT3 but not STAT1 correlating with PML mRNA and protein levels. RNAi-mediated knockdown of STAT3 decreased PML expression; both STAT3 level/activity and PML expression relied on IL6 secreted into culture media. We mapped the IL6-responsive sequence to an ISRE(-595/-628) element of the PML promoter. The PI3K/Akt/NFκB branch of IL6 signaling showed also cell-type dependence, being highest in BJ, intermediate in HeLa, and lowest in U2OS cells and correlated with IL6 secretion. RNAi-mediated knockdown of NEMO (NF-κ-B essential modulator), a key component of NFκB activation, suppressed NFκB targets LMP2 and IRF1 together with STAT3 and PML. Combined knockdown of STAT3 and NEMO did not further promote PML suppression, and it can be bypassed by exogenous IL6, indicating the NF-κB pathway acts upstream of JAK-STAT3 through induction of IL6. Our results indicate that the cell type-specific activity of IL6 signaling pathways governs PML expression under unperturbed growth conditions. As IL6 is induced in response to various viral and genotoxic stresses, this cytokine may regulate autocrine/paracrine induction of PML under these pathophysiological states as part of tissue adaptation to local stress.     

A DR4:tBID axis drives the p53 apoptotic response by promoting oligomerization of poised BAX

The cellular response to p53 activation varies greatly in a stimulus- and cell type-specific manner. Dissecting the molecular mechanisms defining these cell fate choices will assist the development of effective p53-based cancer therapies and also illuminate fundamental processes by which gene networks control cellular behaviour. Using an experimental system wherein stimulus-specific p53 responses are elicited by non-genotoxic versus genotoxic agents, we discovered a novel mechanism that determines whether cells undergo proliferation arrest or cell death. Strikingly, we observe that key mediators of cell-cycle arrest (p21, 14-3-3σ) and apoptosis (PUMA, BAX) are equally activated regardless of outcome. In fact, arresting cells display strong translocation of PUMA and BAX to the mitochondria, yet fail to release cytochrome C or activate caspases. Surprisingly, the key differential events in apoptotic cells are p53-dependent activation of the DR4 death receptor pathway, caspase 8-mediated cleavage of BID, and BID-dependent activation of poised BAX at the mitochondria. These results reveal a previously unappreciated role for DR4 and the extrinsic apoptotic pathway in cell fate choice following p53 activation.     

The BRCA1 alternative splicing variant Δ14-15 with an in-frame deletion of part of the regulatory serine-containing domain (SCD) impairs the DNA repair capacity in MCF-7 cells

The BRCA1 gene codes for a protein involved in the DNA double strand break (DDSB) repair. Alongside the dominant full-length splicing form of BRCA1, numerous endogenously expressed alternative splicing variants of unknown significance have been described in various tissues. Some of them retain the original BRCA1 reading frame but lack several critical BRCA1 structural domains, suggesting an altered function of the resulting protein in the BRCA1-regulated processes. To characterize the effect of the BRCA1Δ14-15 splicing variant (with an in-frame deletion affecting the regulatory serine-containing domain) on the DDSB repair, we constructed the MCF-7 clones stably expressing the analyzed variant with/without a shRNA-mediated downregulation of the endogenous full-length wild-type BRCA1 expression. Our results show that the expression of the BRCA1Δ14-15 variant delays the γ-radiation-induced DDSB repair, alters the kinetics of irradiation-induced foci formation/decomposition and reduces the non-homologous end-joining capacity in MCF-7 cells. Therefore, the BRCA1Δ14-15 is not able to functionally replace the full-length wt BRCA1 in the DDSB repair. Our findings indicate that the endogenously expressed BRCA1 alternative splicing variants may negatively influence genome stability and support the growing evidence of the pathological potential of the sequence variants generated by an altered or misregulated alternative splicing in the process of mammary malignant transformation.     

Improved vaccine protection from simian AIDS by the addition of nonstructural simian immunodeficiency virus genes

An HIV-1 vaccine able to induce broad CD4+ and CD8+ T cell responses may provide long-term control of viral replication. In this study we directly assess the relative benefit of immunization with vaccines expressing three structural Ags (Gag, Pol, and Env), three early regulatory proteins (Rev, Tat, and Nef), or a complex vaccine expressing all six Ags. The simultaneous administration of all six Ags during vaccination resulted in Ag competition manifested by a relative reduction of CD8+ T cell and lymphoproliferative responses to individual Ags. Despite the Ag competition, vaccination with all six Ags resulted in a delay in the onset and a decrease in the extent of acute viremia after mucosal challenge exposure to highly pathogenic SIV(mac251). Reduced levels of acute viremia correlated with lower post-set point viremia and long-term control of infection. In immunized animals, virus-specific CD4+ T cell and lymphoproliferative responses were preserved during acute viremia, and the maintenance of these responses predicted the long-term virological outcome. Taken together, these results suggest that the breadth of the immune response is probably more important than high frequency responses to a limited number of epitopes. These data provide the first clear evidence of the importance of nonstructural HIV Ags as components of an HIV-1 vaccine.     

A novel insertion of a rearranged L1 element in exon 44 of the dystrophin gene: further evidence for possible bias in retroposon integration

L1 elements are mammalian retrotransposons contributing to genome evolution and causing rare mutations in human. We describe a de novo insertion of an L1 element into the dystrophin gene resulting in skipping of exon 44 and causing Duchenne muscular dystrophy in a boy. The L1 element was rearranged due to the twin-priming mechanism, but contrary to all described L1 rearrangements the 5' region of the inverted L1 sequence ended within the poly(A) tail of the element. Furthermore, the target site for the insertion was located only 87 bp from the insertion site in another patient described previously. These findings can contribute to the understanding of the mechanisms of L1 element rearrangement, and may support the notion that some subregions of the human genome could be preferred targets for retroelements using the L1 enzymatic machinery.