bluuebunny/crossref_metadata_2025_split huggingface dataset:
New enzymes involved in aerobic benzoate metabolism in Azoarcus evansii
Authors: Zaar Annette , Gescher Johannes , Eisenreich Wolfgang , Bacher Adelbert , Fuchs Georg 
Published: September 2004

SummaryA new principle of aerobic aromatic metabolism has been postulated, which is in contrast to the known pathways. In various bacteria the aromatic substrate benzoate is first converted to its coenzyme A (CoA) thioester, benzoyl‐CoA, which is subsequently attacked by an oxygenase, followed by a non‐oxygenolytic fission of the ring. We provide evidence for this hypothesis and show that benzoyl‐CoA conversion in the bacterium Azoarcus evansii requires NADPH, O2 and two protein components, BoxA and BoxB. BoxA is a homodimeric 46 kDa iron‐sulphur‐flavoprotein, which acts as reductase. In the absence of BoxB, BoxA catalyses the benzoyl‐CoA stimulated artificial transfer of electrons from NADPH to O2 via free FADH2 to produce H2O2. Physiologically, BoxA uses NADPH to reduce BoxB, a monomeric 55 kDa iron‐protein that acts as benzoyl‐CoA oxygenase. The product of benzoyl‐CoA oxidation was identified by NMR spectroscopy as its dihydrodiol derivative, 2,3‐dihydro‐2,3‐dihydroxybenzoyl‐CoA. This suggests that BoxBA act as a benzoyl‐CoA dioxygenase/reductase. Unexpectedly, benzoyl‐CoA transformation by BoxBA was greatly stimulated when another enoyl‐CoA hydratase/isomerase‐like protein, BoxC, was added that catalysed the further transformation of the dihydrodiol product formed from benzoyl‐CoA. The benzoyl‐CoA oxygenase system has very low similarity to known (di)oxygenase systems and is the first member of a new enzyme family.
Positioning of the MinE binding site on the MinD surface suggests a plausible mechanism for activation of the Escherichia coli MinD ATPase during division site selection
Authors: Ma Luyan , King Glenn F. , Rothfield Lawrence 
Published: September 2004

SummaryDivision site selection in Escherichia coli requires that the MinD protein interact with itself and with MinC and MinE. MinD is a member of the NifH‐ArsA‐Par‐MinD subgroup of ATPases. The MinE–MinD interaction results in activation of MinD ATPase activity in the presence of membrane vesicles. The sites within MinD responsible for its interaction with MinC and MinE were studied by site‐directed mutagenesis and yeast two‐hybrid analysis, guided by the known three‐dimensional structure of MinD proteins. This provided evidence that MinC and MinE bind to overlapping sites on the MinD surface. The results also suggested that MinE and the invariant Lys11 residue in the ATPase P‐loop of MinD compete for binding to a common site within the MinD structure, thereby providing a plausible structural basis for the ability of MinE to activate the ATPase activity of MinD.
Molecular pathogenesis of neonatal group B streptococcal infection: no longer in its infancy
Authors: Doran Kelly S. , Nizet Victor 
Published: September 2004

SummaryThe process of human infection by group B Streptococcus (GBS) is complex and multifactorial. While this bacterium has adapted well to asymptomatic colonization of adult humans, it remains a potentially devastating pathogen to susceptible infants. Advances in molecular techniques and refinement of in vitro and in vivo model systems have elucidated key elements of the pathogenic process, from initial attachment to the maternal vaginal epithelium to penetration of the newborn blood–brain barrier. Sequencing of two complete GBS genomes has provided additional context for interpretation of experimental data and comparison to other well‐studied pathogens. Here we review recent discoveries regarding GBS virulence mechanisms, many of which are revealed or magnified by the unique circumstances of the birthing process and the deficiencies of neonatal immune defence. Appreciation of the formidable array of GBS virulence factors underscores why this bacterium remains at the forefront of neonatal pathogens.
Role of the GGDEF protein family in Salmonella cellulose biosynthesis and biofilm formation
Authors: García Begoña , Latasa Cristina , Solano Cristina , Portillo Francisco García‐del , Gamazo Carlos , Lasa Iñigo 
Published: September 2004

Summary Salmonella enterica serovar Typhimurium is capable of producing cellulose as the main exopolysaccharide compound of the biofilm matrix. It has been shown for Gluconacetobacter xylinum that cellulose biosynthesis is allosterically regulated by bis‐(3′,5′) cyclic diguanylic acid, whose synthesis/degradation depends on diguanylate cyclase/phosphodiesterase enzymatic activities. A protein domain, named GGDEF, is present in all diguanylate cyclase/phosphodiesterase enzymes that have been studied to date. In this study, we analysed the molecular mechanisms responsible for the failure of Salmonella typhimurium strain SL1344 to form biofilms under different environmental conditions. Using a complementation assay, we were able to identify two genes, which can restore the biofilm defect of SL1344 when expressed from the plasmid pBR328. Based on the observation that one of the genes, STM1987, contains a GGDEF domain, and the other, mlrA, indirectly controls the expression of another GGDEF protein, AdrA, we proceeded on a mutational analysis of the additional GG[DE]EF motif containing proteins of S. typhimurium. Our results demonstrated that MlrA, and thus AdrA, is required for cellulose production and biofilm formation in LB complex medium whereas STM1987 (GGDEF domain containing protein A, gcpA) is critical for biofilm formation in the nutrient‐deficient medium, ATM. Insertional inactivation of the other six members of the GGDEF family (gcpB‐G) showed that only deletion of yciR (gcpE) affected cellulose production and biofilm formation. However, when provided on plasmid pBR328, most of the members of the GGDEF family showed a strong dominant phenotype able to bypass the need for AdrA and GcpA respectively. Altogether, these results indicate that most GGDEF proteins of S. typhimurium are functionally related, probably by controlling the levels of the same final product (cyclic di‐GMP), which include among its regulatory targets the cellulose production and biofilm formation of S. typhimurium.
Food vacuole‐associated lipid bodies and heterogeneous lipid environments in the malaria parasite, Plasmodium falciparum
Authors: Jackson Katherine E. , Klonis Nectarios , Ferguson David J. P. , Adisa Akinola , Dogovski Con , Tilley Leann 
Published: September 2004

SummaryThe malaria parasite Plasmodium falciparum induces a sixfold increase in the phospholipid content of infected erythrocytes during its intraerythrocytic growth. We have characterized the lipid environments in parasitized erythrocyte using the hydrophobic probe, Nile Red. Spectral imaging with a confocal microscope revealed heterogeneous lipid environments in parasite‐infected erythrocytes. An insight into the nature of these environments was gained by comparing these spectra with those of triacylglycerol/phospholipid emulsions and phospholipid membranes. Using this approach, we identified a population of intensely stained particles of a few hundred nanometers in size that are closely associated with the digestive vacuole of the parasite and appear to be composed of neutral lipids. Electron microscopy and isolation of food vacuoles confirmed the size of these particles and their intimate association respectively. Lipid analysis suggests that these neutral lipid bodies are composed of di‐ and triacylgycerols and may represent storage organelles for lipid intermediates that are generated during digestion of phospholipids in the food vacuole. Mono‐, di‐ and triacylglycerol suspensions promote β‐haematin formation, suggesting that these neutral lipid bodies, or their precursors, may also be involved in haem detoxification. We also characterized other compartments of the infected erythrocyte that were stained less intensely with the Nile Red probe. Both the erythrocyte membrane and the parasite membrane network exhibit red shifts compared with the neutral lipid bodies that are consistent with cholesterol‐rich and cholesterol‐poor membranes respectively. Ratiometric imaging revealed more subtle variations in the lipid environments within the parasite membrane network.
Human Cryptosporidiosis: An Update With Special Emphasis on the Situation in Europe
Authors: Joachim A. 
Published: September 2004

SummaryThe genus Cryptosporidium consists of different species and genotypes which infect a wide range of hosts, including humans. The parasite is ubiquitous and lack of differentiation between the species and strains has made it difficult to track down sources of human and animal infections. Genetic analysis of strains and isolates has led to the redescription of Cryptosporidium with special consideration of the host specificity and possible ways of transmission to humans. Infection with the small oocysts usually occurs directly by faecal–oral transmission, water‐ or food–borne. In Europe water from different sources is frequently contaminated with oocysts. Generally, humans are most frequently infected with C. hominis in an anthroponotic cycle (especially in cases of infections imported from highly endemic (sub‐) tropical regions) and the animal genotype (type II) of C. parvum in a zoonotic cycle which seems to play a major role in autochthonous infections in Switzerland, the UK and probably other European countries. Other species (such as C. felis or the avian species C. meleagridis and C. baileyi) and genotypes are rare in humans and mostly restricted to immunocompromised individuals who are highly susceptible to serious opportunistic cryptosporidial infections.
Classical Swine Fever Virus Strain ‘C’. How Long is it Detectable After Oral Vaccination?
Authors: Kaden V. , Lange E. , Riebe R. , Lange B. 
Published: September 2004

SummaryTo determine the persistence period of C‐strain vaccine virus in immunized animals, domestic pigs and wild boars were vaccinated orally and killed on different days post vaccinationem (dpv). Tissue samples were taken at necropsy from both species for detection of C‐strain virus. From domestic pigs nasal swabs and faeces were also collected. During the investigation period (2–12 dpv) vaccine virus could never be detected in nasal secretions and in faeces of vaccinated domestic pigs. In contrast, C‐strain virus was found in organs until day 8 pv in domestic pigs and until day 9 pv in wild boars. Whereas in domestic pigs virus was detected in tonsils, Ln. mandibularis or in spleen, in wild boar it only was found in tonsils. We conclude that C‐strain vaccine virus is not detectable in wild boars longer than 10–12 days after intake of the vaccine baits.
Effects of Subinhibitory Concentrations of Florfenicol on Morphology, Growth, and Viability of Staphylococcus aureus
Authors: Blickwede M. , Valentin‐Weigand P. , Rohde M. , Schwarz S. 
Published: September 2004

Summary Staphylococcus aureus strain Newman was investigated for changes in its growth pattern, its morphology and its viability when grown in the presence of 3 μg/ml florfenicol (Ff). This concentration corresponds to the 0.75‐fold strain‐specific minimum inhibitory concentration (MIC). Under these conditions, S. aureus Newman showed a distinct retardation in its growth pattern and 20% dead cells were detected in a fluorescence microscopic viability assay. However, bactericidal activity – defined as a 3‐log drop in the staphylococcal population – was not recorded at this Ff concentration. Further analysis of the cell wall revealed a significant increase in cell wall thickness of S. aureus Newman when grown in the presence of 3 μg/ml Ff. This might result in a compression of the protoplast with subsequent disruption of single staphylococcal cells. Accordingly, 20% of the staphylococcal cells analysed by electron microscopy proved to be disrupted. These observations suggest that Ff can cause a thickening of the cell wall accompanied by impaired viability of the staphylococcal cells.
Virulence Genes of Escherichia coli Strains Isolated from Mastitic Milk
Authors: Bean A. , Williamson J. , Cursons R. T. 
Published: September 2004

Summary Escherichia coli, a Gram‐negative environmental pathogen associated with bovine mastitis was isolated from the milk of 34 symptomatic cows that had been diagnosed with clinical mastitis. Eighty isolates were obtained over a 17‐month period and these isolates were screened by DNA amplification for the following E. coli virulence genes: cnf1, cnf2, eaeA, eagg, einv, ltx1, stx1, stx2 and vt2e. Thirty of the bacterial isolates, obtained from 23 different cows, had toxin genes identified in their DNA. The most common virulence gene detected was stx1, with a prevalence of 31%, followed by cnf2 (7.5%), vt2e (6.25%) and eaeA (4%). The possession of different virulence genes by the bacterial isolates had no discernable impact on the health status of the cows as there was no correlation between the potential for toxin production by the E. coli isolates and the systemic clinical condition of the respective infected cows.
Characterization of Pathogenic Escherichia coli Isolated from Humans in Austria: Phenotypes, Toxin Gene Types and Epidemiology
Authors: Wagner M. , Allerberger F. , Manafi M. , Lindner G. , Friedrich A. W. , Sonntag A.‐K. , Foissy H. 
Published: September 2004

SummaryOne hundred and ten clinical Escherichia coli isolates of serovar O157 (n = 102) and O26 (n = 8) were characterized for the presence of putative virulence genes by PCR. All but one of these isolates contained the eae gene. The EHEC‐hly gene could be detected in all E. coli O157 and in 50% of E. coli O26 isolates. Forty‐five (40.9%) of the 110 E. coli were positive for both stx1 and stx2 genes, 2 (1.8%) isolates were positive for stx1 and 57 isolates (51.8%) were positive for stx2 only. Among the 102 stx2 positive isolates, 14 (13.7%) E. coli O157 contained also the stx2c variant gene. No other stx2 variant was identified. Six clinical isolates (five E. coli O157:H7 and one E. coli O26) did not contain stx genes. Ten non‐pathogenic E. coli isolates which were amplified as controls didn't contain any stx and eae gene but two of the ten strains contained the EHEC‐hly gene. By their growth on chromogenic media, all but two of 50 E. coli O157 could be differentiated from eight E. coli O26 and 10 non‐pathogenic E. coli. Sixty‐one of the O157:H7 isolates were further subjected to pulsed‐field gel electrophoresis (PFGE) which identified 49 distinguishable patterns. In five cases where contact infection among family members was suspected, indistinguishable PFGE patterns confirmed the epidemiological relatedness of the isolates. Moreover, two PFGE clusters were identified which comprised five and three strains, respectively. These findings indicate the occurrence of both family and diffuse outbreaks of E. coli O157 infections in Austria during recent years and demonstrate the need for molecular subtyping of these pathogens.
Lameness in Piglets. Abrasions in Nursing Piglets and Transfer of Protection towards Infections withStreptococcifrom Sow to Offspring
Authors: Zoric M. , Sjölund M. , Persson M. , Nilsson E. , Lundeheim N. , Wallgren P. 
Published: September 2004

SummaryA group of 175 newborn piglets were monitored with respect to development of abrasions and lameness. Lameness was diagnosed in 10.9% of the piglets. About every second litter was affected and around 75% of these diagnoses took place during the first 3 weeks of life. Skin lesions were present already on day 3. They increased in magnitude until day 10 and thereafter declined. They were generally bilateral and most commonly observed as abrasions over the carpal joints. Hocks, face and tails were affected in a similar way, but at lower magnitudes. Sole bruising was observed in 87% of the piglets on the third day of life, and moderate to severe lesions dominated until day 10. Thereafter the incidence decreased, indicating healing with time. Still 39% of the piglets were affected at day 17. There was a significant positive correlation between skin lesions of carpus and hock within all examination days in selected piglets with known identity (n = 48). Between day 10 and 17 significant positive correlations were found within all examination sites with exception of abdomen and teats. The offspring of sows treated against mastitis expressed more abrasions then piglets delivered by healthy sows and the mortality during the first 17 days postpartum was significantly higher among piglets delivered by sows treated for mastitis. The level of serum antibodies toStreptococcus equisimilisin eight dams decreased during the last month of gestation and a declining maternal immunity toS. equisimiliswas demonstrated in all piglets (n = 47) during the first 5 weeks of life. During the first 2 weeks of life somewhat lower median levels of serum antibodies were recorded among the piglets that were treated against arthritis (n = 8).
C‐reactive protein may be a marker of bacterial translocation in experimental intestinal obstruction
Authors: Çevikel Mehmet Hakan , Özgün Hedef , Boylu Sükrü , Demirkiran Ahmet Ender , Aydin Neriman , Sari Cavide , Erkus Muhan 
Published: September 2004

Background:  C‐reactive protein (CRP) is used as a marker of intestinal ischaemia. This study evaluated whether CRP levels can be used to detect ischaemia‐induced (strangulated) intestinal obstruction and subsequent bacterial translocation.Methods:  Forty‐eight rats, divided into four groups underwent the following procedures: anaesthesia alone (native controls), laparotomy (sham‐operated controls), or surgical induction of simple or strangulated intestinal obstruction (simple and strangulated obstruction groups, respectively). Blood samples were collected for culture and serum CRP analysis. In addition, liver and mesenteric lymph node (MLN) specimens were collected for culture, to determine the presence of bacterial translocation; and ileal segments, for histopathological investigation.Results:  CRP levels and rates of bacterial translocation, expressed as colony forming units (cfu) per gram wet tissue, were higher in both intestinal obstruction groups than in the native and sham‐operated control groups (P < 0.001 for both). The increases in CRP levels paralleled increases in the number of cfu in the MLN and liver cultures (P < 0.01). Compared to controls, animals in the obstruction groups also had a higher incidence of positive blood cultures (P < 0.005) and greater histopathologic evidence of inflammatory infiltration of the lamina propria (P < 0.01). However, no significant difference between the simple and strangulated obstruction groups was observed.Conclusion:  CRP levels increase with the severity of bacterial translocation in acute intestinal obstruction but do not permit discrimination between simple and strangulated intestinal obstruction.
Comparison of pulmonary hydatid cysts in children and adults
Authors: Kanat Fikret , Turk Emel , Aribas Olgun Kadir 
Published: September 2004

Background:  The purpose of the present study was to compare the clinical features and the surgical approaches of the pulmonary hydatid cysts in children and adults.Methods:  One hundred and thirty‐four patients, operated on for pulmonary hydatid cysts over the last 10 years were retrospectively evaluated in two groups: 39 children who were younger than 18 years old (29%) and 95 adults (71%). The patients in each group were analysed according to their clinical, radiological and surgical findings.Results:  The frequency of pulmonary hydatid cysts in children was significantly higher in boys (74%) than in girls (26%). However, there was no sex tendency in adults (52% in male vs 48% in women). The sex difference in hydatid cyst frequencies between adults and children was significant (P < 0.05). Among preoperative pleural complications, pneumothorax (15.5%) in children and empyema (11%) in adults were more frequent. The frequency of concomitant hepatic cysts was less in children than in adults (33%vs 79%). Huge pulmonary cysts (=10 cm) were more common in children (31%) than in adults (22%). Cystotomy with capitonnage was the most frequently preferred method in both groups. Postoperative complications developed in six children (16%) and 19 adults (19%), and were more frequent in patients with huge cysts (27%vs 16%). No recurrence was observed in both groups.Conclusions:  Isolated pulmonary cysts are more common in children than adults. The cysts also tend to be bigger in children than adults. The frequency of concomitant hepatic cysts is less in children. Because of higher lung expansion ability and improvement capacity in children, resection should be avoided and lung saving surgical procedures should be performed. In spite of differences observed in the clinical features it does not change the treatment of pulmonary hydatid cysts in children.
Role of Gastrografin in assigning patients to a non‐operative course in adhesive small bowel obstruction
Authors: Roadley Graeme , Cranshaw Isaac , Young Michael , Hill Andrew G. 
Published: September 2004

Background:  Adhesive small bowel obstruction (SBO) is a common surgical emergency. Water soluble contrast agents have been used to identify patients who might be treated non‐operatively rather than operatively. The present study was designed to audit the introduction of such use of Gastrografin contrast into clinical practice.Method:  Patients presenting acutely to hospital with clinically suspected and radiologically proven SBO were entered in the study. As soon as practicable, 100 mL of undiluted Gastrografin was given either orally or by the nasogastric tube (which was then spigotted). After 4 h, a plain supine abdominal X‐ray (AXR) was taken. If the contrast was seen in the large bowel, and there had been no deterioration in the patient's condition, then non‐operative treatment was continued. If the contrast remained in the small bowel, a clinical judgement was made as to whether to proceed with operative intervention.A group of historical controls were obtained by a retrospective review of the hospital medical records through data obtained from the Department of General Surgery Audit System.Results:  Twenty‐five patients were entered into the study. In 20 of these patients the contrast was seen to arrive in the large bowel at 4 h. All of these patients completed a non‐operative course to full recovery. In another two patients a successful decision was made to pursue a non‐operative management strategy. These 22 patients had a mean hospital stay of 3.9 days. Eighty historical controls had successfully completed a non‐operative course for SBO. They had a mean hospital stay of 5.6 days. This was significantly longer than that of the Gastrografin group (P < 0.016, t‐test).Conclusion:  This paper has demonstrated that undiluted Gastrografin may be safely used to assign patients to a non‐operative management plan and this results in a decreased hospital stay.