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Biomedical subjects

K Nowak

Publications and source records attributed to K Nowak.

At least 127 records · Page 7Linked to original sources
PubMedDate not supplied

Vectors for RNAi technology in poplar.

The potential of double-stranded RNA interference (RNAi) technology was studied for down-regulation of gene expression in poplar. A set of vectors was constructed generating RNAs capable of duplex formation of sequences specific for the beta-glucuronidase (GUS) reporter gene system. These gene cassettes are driven by the CaMV-35S promoter. To address the question of gene silencing, we tested the functionality of these vectors, both in transient assays by transforming protoplasts with the RNAi constructs, and in stably transformed GUSexpressing poplar plants. Agrobacterium-mediated transformation of those GUS-expressing plants with a GUS-specific RNAi construct showed a strong down-regulation of the reporter gene. From these results we conclude that RNAi is also functional in poplar.

Base Sequence↗
PubMedDate not supplied

Fluorescent proteins in poplar: a useful tool to study promoter function and protein localization.

The jellyfish (Aequorea victoria) green fluorescent protein (GFP) and its variants (CFP [cyan] and YFP [yellow]) were successfully used as a vital marker system for the transformation of hybrid poplar (Populus tremula x P. alba). Our results show that, in this woody plant, fluorescent proteins can be expressed: (i) transiently in protoplasts after PEG-mediated transformation, as well as in leaf cells after particle bombardment, and (ii) stably in callus cells and plants after Agrobacterium-mediated transformation. For these studies, we constructed vectors permitting easy recloning of any promoter fragments of interest. Confocal laser scanning microscopy was used both for visualization and differentiation between the different colours of the GFP variants and autofluorescence of chlorophyll and lignified xylem vessels. Peroxisomes were chosen as target organelles for GFP translocation via the peroxisomal targeting sequence PTS1 because this allowed us to concentrate the fluorochrome in the small volume of a few peroxisomes, giving a bright fluorescence over background noise.

Base Sequence↗
PubMedDate not supplied

A clinico-epidemiological study on gastritis in gastric carcinoma and in non-cancerous gastric pathology in Poland.

To investigate the risk of gastric cancer development in subjects with atrophic and nonatrophic gastritis, we studied 221 consecutive gastric cancer patients and 7647 non-cancer subjects for whom endoscopic biopsy of the gastric mucosa was available. In gastritis patients, the relative risk (RR) estimates of gastric cancer were as follows: corpus atrophic gastritis RR = 8.7 (95% CI = 5.4-14.1), antral atrophic gastritis RR = 4.5 (2.4-8.1), chronic atrophic pangastritis RR = 7.6 (3.8-15.3), corpus nonatrophic gastritis RR = 1.6 (0.9-2.7), antral non-atrophic gastritis RR = 1.2 (0.7-2.3), and pangastritis RR = 1.3 (0.6-2.8). The latter was of borderline significance (p = 0.07). In peptic ulcer, a significant excess risk was calculated for subjects with either corpus atrophic gastritis (RR = 3.1 [2.5-3.9] or antral atrophic gastritis (RR = 3.5 [2.6-4.8]). For stomach polyps, the risk was significantly increased only in subjects with corpus atrophic gastritis (RR = 2.1 [1.3-3.5]). The risks for both peptic ulcer and polyps, however, were significantly increased in chronic atrophic pangastritis. A substantial excess risk of gastric cancer was found for atrophy in the corpus (RR = 20.9 [9.0-48.9]) and in the antrum (RR = 14.9 [5.3-41.9]). An increased risk of peptic ulcer was also confirmed in subjects with atrophy in the corpus (RR = 3.0 [1.3-6.9]) and in the antrum (RR = 4.9 [2.0-12.1]).

Adolescent↗
PubMedDate not supplied

Adherence of bile-isolated bacteria to the bile ducts mucosa as a pathogenic factor in the development of inflammatory lesions.

Bacterial infection of the bile system appears to be an important factor in the formation of stones. In view of the hypothesis that strains of E. c. form an essential factor in infections of the bile ducts, an attempt has been made to determine the connection between infections of the bile ducts and the adherence of E. c. to the epithelium of the gallbladder. The research covered 148 patients operated electively for cholecystolithiasis (121), cholecystocholedocholithiasis (26) and recurrent lithiasis (1). In bile collected from the gallbladder in the course of the operation, E. coli strains were isolated. Cholangioscopy performed in 26 patients enabled the macroscopic evaluation and grading of inflammatory lesions of bile duct mucosa. The mucosa of the gallbladder was evaluated histologically. The adherence test was performed using homologous and heterologous strains of E. c. isolated from the bile of gallstone patients. The adherence occurred most frequently in the neck of the gallbladder (71-100%) in those patients in whom an infectious process of the bile ducts mucosa was endoscopically diagnosed. The adherence of bacteria to the epithelium of the gallbladder did not depend on the type of inflammation (acute, chronic).

Bacterial Adhesion↗