Biomedical subjects

Jerzy Ostrowski

Publications and source records attributed to Jerzy Ostrowski.

24 records · Page 2Linked to original sources

PubMed2003

Quantitative detection for low levels of Helicobacter pylori infection in experimentally infected mice by real-time PCR.

Accurate diagnosis of Helicobacter pylori infection is important in both clinical practice and clinical research. Molecular methods are highly specific and sensitive, and various PCR-based tests have been developed to detect H. pylori in gastric biopsy specimens. We optimized a sensitive and specific quantitative SYBR Green I real-time PCR assay for detection of H. pylori based on amplification of the fragment of a 26-kDa Helicobacter species-specific antigen gene that allows for detection of 5 bacterial cells per PCR sample. Under the assay conditions, SYBR Green I real-time PCR is highly reproducible with a precise log-linear relation in the range of six orders of magnitude of bacterial DNA concentrations. For accurate comparison of H. pylori infection in different tissue samples, the amount of total host DNA in each sample is normalized by TaqMan real-time PCR of glyceraldehyde 3-phosphate dehydrogenase (GAPDH) pseudogenes. The developed method was validated in prophilactically immunized and experimentally infected mice and revealed a level of H. pylori gastric colonisation that was below the limit of detection for a rapid urease test. This new method established for a quantitative analysis of H. pylori in the host's stomach may be useful in experimental studies evaluating new anti-H. pylori drugs and vaccines.

Animals↗

PubMed2003

Homoplasmic MELAS A3243G mtDNA mutation in a colon cancer sample.

We have analyzed mtDNA variation in various cancer samples, comparing them with normal tissue controls, and identified mutations and polymorphisms, both known and novel, in mitochondrial tRNA, rRNA and protein genes. Most remarkably, in a colon cancer sample we have found the A3243G mutation in the homoplasmic state. This mutation is known to cause severe mitochondrial dysfunction and, until now, has not been found in cancer cells, nor in the homoplasmic state in living subjects. The mutation was absent from normal tissue, suggesting that mtDNA mutation and resulting respiratory deficiency played a role in carcinogenesis.

Journal Article↗

PubMed2003

Multivariate analysis of risk factors for development of duodenal ulcer in Helicobacter pylori-infected patients.

BACKGROUND: Although Helicobacter pylori is a significant etiologic factor of peptic ulcer disease, it remains unknown why ulcers develop only in the minority of infected individuals. AIM: The aim of this cross-sectional study was to evaluate the association between the presence of duodenal ulcer in H. pylori-infected patients and different risk factors. METHODS: A total of 122 H. pylori-infected patients were enrolled; 79 had duodenal ulcer and 43 gastritis. Univariate analysis was conducted using either Fisher's exact test or exact Cochrane-Armitage trend test. In multivariate analysis the logistic model was used. RESULTS: Univariate analysis indicated six factors (male sex, smoking, antral H. pylori density, CAGA presence in antrum, and VACA s1a presence in antrum and corpus). Four factors (sex, smoking-alcohol index, H. pylori density index, and CAGA index) were found to be significant in multivariate analysis. The best model predicting duodenal ulcer included male sex, smoking, presence of H. PYLORI on histopathology in antrum and CAGA presence in corpus. CONCLUSION: Although several risk factors were significantly associated with duodenal ulcer, we failed in the identification of either a single risk factor or a set of factors that can unequivocally differentiate patients with ulcer from those with gastritis.

Adolescent↗

PubMed2002

The hppA gene of Helicobacter pylori encodes the class C acid phosphatase precursor.

Screening of the Helicobacter pylori genomic library with sera from infected humans and from immunized rabbits resulted in identification of the 25 kDa protein cell envelope (HppA) which exhibits acid phosphatase activity. Enzyme activity was demonstrated by specific enzymatic assays with whole-cell protein preparations of H. pylori strain N6 and from Escherichia coli carrying the hppA gene (pUWM192). HppA showed optimum activity at pH 5.6 and was resistant to inhibition by EDTA. Bioinformatics analysis and site-directed mutagenesis of two putative active site residues (D73 and D192) provide further insight into the sequence-structure-function relationships of HppA as a member of the DDDD phosphohydrolase superfamily.

Acid Phosphatase↗

PubMed2002

Increased expression of ribosomal protein S2 in liver tumors, posthepactomized livers, and proliferating hepatocytes in vitro.

The ribosomal protein S2 (RPS2) is encoded by a gene from the highly conserved mammalian repetitive gene family LLRep3. It participates in aminoacyl-transfer RNA binding to ribosome, potentially affecting the fidelity of mRNA translation. These studies were designed to measure the expression of RPS2 during increased cell proliferation. Using Western and Northern blot analyses, we found that the levels of RPS2 protein and its corresponding mRNA were higher in mouse hepatocellular carcinoma, in mouse livers after one-third partial hepatectomy, and in serum-starved cultured hepatocytes following serum treatment. Our study shows that the increased expression of RPS2 correlates with increased cell proliferation. However, whether the altered expression of this protein reflects its involvement in cellular proliferation or represents an associated phenomena is still a key question that needs to be explored.

Amino Acid Sequence↗

PubMed2001

Heterogeneous nuclear ribonucleoprotein K protein associates with multiple mitochondrial transcripts within the organelle.

Heterogeneous nuclear ribonucleoprotein K (hnRNP K) protein interacts with a subset of cellular RNAs. We used K protein as a bait in the yeast three-hybrid screen to identify RNAs that bind K protein in vivo. A large number of K protein-binding RNA clones were identified from a human hybrid RNA library. These sequences consisted of C-rich patches and were G-poor. Unexpectedly, several of the RNA clones were encoded by the mitochondrial genome. In a subsequent three-hybrid screen of a hybrid RNA library generated from a mouse liver mitochondrial genome, K protein bound RNA sequences encoded by different loci spanning nearly the entire mitochondrial genome. Western blot analysis of extracts from mitochondria and mitochondrial fractions showed that K protein is localized within mitoplasts. Reverse transcriptase PCR of RNA co-immunoprecipitated with K protein from lysates of isolated mitochondria showed that K protein is associated with several processed mitochondrial transcripts. In contrast, in the same assay, the polycistronic nascent mtRNA bound K protein weakly or not at all. Results of this study suggest that K protein acts within functional modules that are responsible for expression of genes in mitochondria.

Animals↗