[The role of STAT proteins in the regulation of the response to the interferone alpha therapy in chronic hepatitis C]. / Role proteinu rodiny STAT v regulaci odpovedi na lécbu chronické hepatitidy C interferonem alpha.

The currently used standard treatment for chronic hepatitis C using a dual combination of IFNalpha/RBV is only successful in 50% cases. With the exception of some clinical and biochemical factors, degree of inflammation (grading) and degree of fibrosis (staging), there are no other known markers which may serve as valid predictors of response to therapy. Interference of hepatitis C virus (HCV) with signaling pathways modulated by JAK-STAT, ERK 1/2, NFkappaB and MAP proteins is one mechanism which may influence the interaction between HCV and IFNalpha. These proteins regulate different cell processes such as activation of cytokines, activation of apoptosis, regulation of cell proliferation etc. Therefore, it is possible that impaired signaling or inhibition/dysregulation of some of these proteins by HCV infection may cause resistance to IFNalpha treatment. This review is completed by results of preliminary study the aim of which was immunohistochemical assessment and analysis of expression of STAT 2, 3 proteins, their inhibitors SOCS 2, 3 and PIAS 3 and proteins JAK 1 and ERK 1/2 in liver biopsies of 26 patients with chronic hepatitis C treated by dual combination IFNalpha/RBV and subsequent correlation of the results of immunohistochemical analysis (histoscore) with histological picture and clinical response to treatment. The results shows increased expression of STAT 3, STAT 2 and ERK 1 proteins and decreased expression of SOCS 3 and SOCS 2 in hepatocytes of patients with more marked inflammation and fibrosis. In patients with sustained virological response there was increased expression of SOCS 3 and JAK 1 and decreased expression of SOCS 2. Relapse was associated with increased expression of SOCS 3 and PIAS 3. However, owing to the small sample size, the results only approximated statistical significance, but we suggest that proteins of STAT family and their inhibitors SOCS and PIAS probably play an important regulatory role during response to treatment for chronic hepatitis C.

Immunohistochemical detection of the hMLH1 and hMSH2 proteins in hereditary non-polyposis colon cancer and sporadic colon cancer.

Defects in DNA mismatch repair system are involved in carcinogenesis of sporadic and inherited human cancers. We assessed the feasibility of using immunohistochemistry to detect tumors with DNA mismatch repair deficiency. We analyzed 81 samples (74 colon cancers (CC), 1 colon dysplasia and 6 extracolonic cancers) for hMLH1 and hMSH2 protein expression, microsatellite instability (MSI) and/or mutational analysis. A meta-analysis of the published data on immunohistochemistry of hMLH1/hMSH2 proteins was performed. Sensitivity and specificity of the method was calculated. Twenty four of 29 tumors from hMLH1/hMSH2 mutation carriers and 10 of 13 sporadic high frequency MSI tumors lost one of the proteins. None of the 42 tumors with stable microsatellites or low frequency MSI lost the proteins. Based on literature review of 49 publications on colorectal cancer, hMLH1 immunohistochemistry was able to detect 136 of 154 tumors from hMLH1 germline mutation carriers (the sensitivity of 88.3% [95%CI, 85.8-90.8%]), hMSH2 immunohistochemistry detected 99 of 109 tumors from hMSH2 mutation carriers (the sensitivity of 90.8% [95%CI, 88.5-93.1%]), and hMLH1/hMSH2 immunohistochemistry identified 1262 of 1382 tumors with high-frequency microsatellite instability not correlated with mutational analysis (the sensitivity of 91.3% [95%CI, 90.4-92.2%]). The specificity of the method was 99.4% (95%CI, 99.2-99.6%). In conclusion, immunohistochemistry of hMLH1 and hMSH2 proteins is a useful method to predict the presence of mismatch repair deficiency, although its sensitivity is lower than that of MSI analysis.

The isolation of FOS-1, a gene encoding a putative two-component histidine kinase from Aspergillus fumigatus.

In fungi, two-component histidine kinases are involved in response mechanisms to extracellular changes in osmolarity, resistance to dicarboximide fungicides, and cell-wall assembly. In the human opportunistic fungus, Candida albicans, each of the three histidine kinases plays a role in virulence. Here, we identify, for the first time, a gene, FOS-1, from the human pathogenic fungus Aspergillus fumigatus that predicts a protein with homology to two-component histidine kinases. The predicted FOS-1 protein is highly homologous to bacterial and other fungal histidine kinases in several functional domains, but is divergent at the amino- and carboxy-termini. A mutant lacking the FOS-1 locus, DeltaFOS-1, did not exhibit a detectable defect in either hyphal growth or morphology when grown on solid or liquid medium. However, in liquid medium, conidiophore development of the DeltaFOS-1 mutant was delayed. Compared to wild type, the DeltaFOS-1 strain was neither osmotically sensitive nor sensitive or resistant to a number of nondicarboximide antifungal drugs, but was highly resistant to dicarboximide fungicides and resistant to novozym 234, suggesting that FOS-1p may play a role in the regulation of cell-wall assembly.

Expression of a plant protein by Neurospora crassa.

Heterologous expression of plant genes may serve as an important alternative for producing plant proteins. We have investigated the ability of the fungus Neurospora crassa to secrete zeamatin, a protein produced by Zea mays. Zeamatin was induced after being fused to glucoamylase, an extracellular hydrolase produced by N. crassa. Glucoamylase induction and other culture parameters were monitored in untransformed N. crassa grown in shaken liquid culture. A DNA plasmid, pGEZ, was constructed by inserting zeamatin-encoding cDNA into an expression cassette containing the promoter, a truncated open reading frame, and the terminator sequence of the N. crassa glucoamylase gene. Zeamatin-encoding cDNA was modified at the N terminus to include a kex-2 protease site, allowing cleavage of the chimeric product in the secretory pathway. Strains containing the chimeric gene construct were grown in liquid culture and induced for glucoamylase and zeamatin production. Zeamatin antibody detected a protein in a Western blot of concentrated culture supernatants that comigrated with authentic zeamatin. Secreted zeamatin was active in inhibiting the growth of Candida albicans in an agar diffusion assay, indicating that zeamatin had been correctly synthesized, processed, and secreted by N. crassa.

Inhibition of Neurospora crassa growth by a glucan synthase-1 antisense construct.

We have used the filamentous fungus, Neurospora crassa, as a model system to test the concept that antisense targeting of the cell-wall assembly enzyme, (1,3)beta-glucan synthase [E.C. 2.4.1.34; UDPglucose: 1,3-beta-D-glucan 3-beta-D-glucosyltransferase], leads to a corresponding decrease in growth of the organism. Previously, our laboratory isolated a gene (glucan synthase-1, gs-1) that is required for (1,3)beta-glucan synthase activity. Wild-type cells were transformed with DNA vectors encoding various RNAs complementary to the gs-1 messenger RNA (antisense RNA) cloned downstream from an inducible promoter (quinic acid-2[qa-2p]). Stable transformants, expressing a partially inverted antisense message of gs-1 (pMYX107), exhibited dramatic reduction ingrowth compared with empty vector controls. Hyphal measurements of these transformants grown on race tubes indicated that all of the transformants showed various degrees of inhibition. Microscopic observations of transformants revealed shorter hyphal lengths when grown under conditions expressing antisense. Further characterization revealed that the specific activities of (1,3)beta-glucan synthase were decreased by as much as 63% relative to empty vector controls. Together, these observations suggest that antisense against (1,3)beta-glucan synthase led to a reduction in enzyme levels that resulted in altered cell-wall morphology and inhibition of growth. It is possible that antisense oligonucleotides against gs-1 may be useful antifungal agents.

[Pathomorphologic findings after catheterization]. / Patomorfologické nálezy po kanylacích.

Thrombosis and its complications were studied in a group of 110 autopsies of patients who had had a subclavian vein cannulation. A unique complete obliteration of vena cava superior was found in connection with cannulation thrombosis related to the cause of death. A mycotic septicaemia occurred in two cases. "Floated-off cannules" were presented in five cases.

[Congenital aneurysm of the aortic sinus of Valsalva]. / Kongenitálni aneurysma Valsalvova sinu aorty.

In a 25-years-old man following a virus of short duration, cardiac dyspnea developed and within ten days following the onset of the disease, the patient died with manifestations of heart failure. A congenital aneurysm of the sinus of Valsalva was found at the post-mortem accompanied by a double perforation into the right atrium. In accordance with the literature, this finding is considered to be rather rare. The malformation was associated with a fenestration of the aortic and the pulmonary valves.