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Results for “Microbial cooperation”

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PubMed2001

Cooperation of Toll-like receptor 2 and 6 for cellular activation by soluble tuberculosis factor and Borrelia burgdorferi outer surface protein A lipoprotein: role of Toll-interacting protein and IL-1 receptor signaling molecules in Toll-like receptor 2 signaling.

Toll-like receptor 2 (TLR2) and TLR4 play important roles in innate immune responses to various microbial agents. We have previously shown that human dermal endothelial cells (HMEC) express TLR4, but very little TLR2, and respond to LPS, but not to Mycobacterium tuberculosis 19-kDa lipoprotein, unless transfected with TLR2. Here we report that HMEC are unresponsive to several additional biologically relevant TLR2 ligands, including, phenol-soluble modulin (PSM), a complex of three small secreted polypeptides from the skin commensal Staphylococcus epidermidis, soluble tuberculosis factor (STF), and Borrelia burgdorferi outer surface protein A lipoprotein (OspA-L). Expression of TLR2 renders HMEC responsive to all these ligands. We further characterized the signaling pathway in response to STF, OspA-L, and PSM in TLR2-transfected HMEC. The TLR2 signaling pathway for NF-kappaB trans-activation shares the IL-1R signaling molecules. Dominant negative constructs of TLR2 or TLR6 inhibit the responses of STF and OspA-L as well as PSM in TLR2-transfected HMEC, supporting the concept of functional cooperation between TLR2 and TLR6 for all these TLR2 ligands. Moreover, we show that Toll-interacting protein (Tollip) coimmunoprecipitates with TLR2 and TLR4 using HEK 293 cells, and overexpression of Tollip inhibits NF-kappaB activation in response to TLR2 and TLR4 signaling. Collectively, these findings suggest that there is functional interaction between TLR2 and TLR6 in the cellular response to STF and OspA-L in addition to S. epidermidis (PSM) Ags, and that engagement of TLR2 triggers a signaling cascade, which shares the IL-1R signaling molecules, similar to the TLR4-LPS signaling cascade. Our data also suggest that Tollip may be an important constituent of both the TLR2 and TLR4 signaling pathways.

Adaptor Proteins, Signal Transducing↗
PubMed2002

Treatment of children with cystic fibrosis: central, local or both?

UNLABELLED: Owing to a lack of longitudinal studies, the effect of centralization of care on pulmonary function and survival remains unclear. Three different levels of involvement of centralized care in the treatment of paediatric cystic fibrosis patients were compared with regard to longitudinal pulmonary function and nutritional and microbiological status in a 3-y period, and the literature was reviewed on the possible advantages and disadvantages of centralized care. The study included 105 paediatric patients attending the Cystic Fibrosis Centre between January 1997 and January 2001. Twenty-three patients were treated by local paediatricians according to the protocol of the Centre and were seen only once a year at the Centre, for an annual check-up (local care). Forty-one patients were treated at the Centre only (centralized care). The remaining 41 patients were treated in close cooperation between the Centre and local hospitals, with patients visiting the doctors alternately (shared care). The mean annual changes in pulmonary function and body mass index from all patients, as well as a microbiological survey, were reviewed. No significant differences were found between the three groups for annual changes in FEV1, FVC and body mass index, nor did the review of microbial colonization show any significant differences between the groups. Because the groups in this study were relatively small, the results might have been influenced by lack of power. CONCLUSION: In this relatively small group, no differences in pulmonary function, nutritional status or microbiological colonization between the three levels of involvement of centralized care could be found. This could signify that local paediatricians have a special role in the care for patients with cystic fibrosis, in close cooperation with the specialists at the Centre.

Analysis of Variance↗
PubMed2002

Experimental social evolution with Myxococcus xanthus.

Genetically-based social behaviors are subject to evolutionary change in response to natural selection. Numerous microbial systems provide not only the opportunity to understand the genetic mechanisms underlying specific social interactions, but also to observe evolutionary changes in sociality over short time periods. Here we summarize experiments in which behaviors of the social bacterium Myxococcus xanthus changed extensively during evolutionary adaptation to two relatively asocial laboratory environments. M. xanthus moves cooperatively, exhibits cooperative multicellular development upon starvation and also appears to prey cooperatively on other bacteria. Replicate populations of M. xanthus were evolved in both structured (agar plate) and unstructured (liquid) environments that contained abundant resources. The importance of social cooperation for evolutionary fitness in these habitats was limited by the absence of positive selection for starvation-induced spore production or predatory efficiency. Evolved populations showed major losses in all measured categories of social proficiency- motility, predation, fruiting ability, and sporulation. Moreover, several evolved genotypes were observed to exploit the social behavior of their ancestral parent when mixed together during the developmental process. These experiments that resulted in both socially defective and socially exploitative genotypes demonstrate the power of laboratory selection experiments for studying social evolution at the microbial level. Results from additional selection experiments that place positive selection pressure on social phenotypes can be integrated with direct study of natural populations to increase our understanding of principles that underlie the evolution of microbial social behavior.

Biological Evolution↗
PubMed1986

A comparative trial between cefotetan and cephazolin for wound sepsis prophylaxis during elective upper gastrointestinal surgery with an investigation of cefotetan penetration into the obstructed biliary tree.

Cefotetan is a cephamycin antibiotic theoretically suited to prophylaxis of wound infection during upper elective gastrointestinal surgery. In a prophylaxis trial 100 patients undergoing this type of surgery were randomly allocated to receive 1g cefotetan or cephazolin iv at induction of anaesthesia. Cefotetan-treated patients had significantly fewer postoperative infections overall (P less than 0.05) and there were no wound infections recorded in this group. In a separate pharmacokinetic study the penetration of cefotetan into common bile duct bile and gallbladder wall was measured in a further six patients, all of whom had been jaundiced preoperatively. At the time of maximum risk concentrations of cefotetan in bile and biliary tissue as well as blood and wound fat were in excess of the minimum inhibitory concentration for the majority of relevant pathogens. Cefotetan appears to be equally or more effective than cephazolin and is a suitable alternative prophylactic agent in elective upper gastrointestinal surgery.

Bile↗
PubMed1995

Superiority of conventional culture technique over rapid detection of group A Streptococcus by optical immunoassay.

An optical immunoassay (OIA) has been reported to be more sensitive than conventional culture for the detection of Group A Streptococcus, eliminating the need for culture. We attempted to confirm the sensitivity and specificity through a laboratory quantitation study and a clinical trial. OIA did not detect Group A Streptococcus below 10(5) colony forming units (CFU). Culture detected Streptococcus to 10(2) CFU from the inoculated swab. In the clinical study, throat swabs were obtained from 77 patients in an outpatient clinic. Compared with culture, the sensitivity of OIA was 78% and the specificity was 90%. These results demonstrate that OIA was less sensitive than culture in seeded experiments and missed 22% of positives in clinical practice. Our study, contrary to previous reports, suggests that OIA is not sensitive enough to be used as the sole assay for Group A Streptococcus pharyngitis.

Adult↗
PubMed1991

Contaminated patellar tendon grafts: incidence of positive cultures and efficacy of an antibiotic solution soak--an in vitro study.

The incidence of positive cultures after contamination of sterile patellar tendon grafts in an operating room environment was studied in 10 specimens. The grafts were dropped on the floor for 3 min and then cultured. Six of the 10 grafts (60%) had a positive culture at 10 days. To test the efficacy of an antibiotic solution on cleansing contaminated grafts, 10 additional grafts were dropped on the floor for 3 min. Before the grafts were cultured they were soaked in a sterile saline solution containing bacitracin (33.33 U/ml) and polymyxin B (333.33 U/ml) for 15 min. Thirty percent of these grafts (3 of 10) cultured positive at 10 days. In each case the bacterial contaminant was found to be sensitive to one of the antibiotic agents used in the cleansing solution. The results of this study suggest that although soaking contaminated grafts in this antibiotic solution for 15 min may reduce the incidence of positive cultures, it still results in a 30% incidence of nonsterile grafts.

Anterior Cruciate Ligament↗
PubMed1985

Stimulation of in vitro human skin collagenase expression by platelet-derived growth factor.

Platelet-derived growth factor (PDGF) is both chemoattractant and mitogenic for stromal cells. Here, we examined the effects of PDGF on collagenase expression by normal human skin fibroblasts. Culturing cells for 24 hr in the presence of PDGF at 0-180 ng/ml resulted in a dose-dependent, saturable increase in collagenase activity in the culture medium that was paralleled by equal increases in immunoreactive collagenase protein, suggesting enhanced synthesis of a catalytically unaltered enzyme. The specificity of this effect was demonstrated by comparing the collagenase-stimulatory effect with that on total protein synthesis and DNA synthesis. Under in vitro conditions that produced a 2.5-fold increase in collagenase synthesis, there was an approximately equal to 20% increase in total protein synthesis and no change in DNA synthesis. In addition, platelet factor 4, another platelet-derived protein, caused a less than 20% increase in collagenase expression. In time-course studies, stimulation of collagenase synthesis was first observed 8-10 hr after exposure to the growth factor. Conversely, when cells were primed with PDGF for approximately equal to 24 hr and the stimulator was then removed, an increased rate of synthesis was seen for an additional approximately equal to 6 hr, after which the rate reverted to control levels. Since the kinetic data suggested a possible pretranslational effect, fibroblasts cultured with PDGF were used to prepare mRNA. In cell-free translation, total protein synthesis was essentially unaltered; however, the growth factor caused a greater than 2-fold increase in translatable collagenase mRNA. The data suggest that PDGF specifically modulates collagenase synthesis, possibly through a series of events that lead to increased transcription or preferential translation of collagenase mRNA.

Cells, Cultured↗
PubMed1978

Meningitis caused by Streptococcus dysgalactiae in a preterm infant.

This report describes a case of meningitis caused by a Lancefield group C streptococcus (Streptococcus dysgalactiae) in a 9-week-old infant. Bacteria of this group rarely cause serious infections in man. The organism was identified as a member of Lancefield group C by the acid extraction method and as S. dysgalactiae by biochemical tests. The patient's condition responded well to penicillin and tobramycin therapy, with no obvious neurologic sequelae.

Anti-Bacterial Agents↗
PubMed1991

Bactericidal activity of sparfloxacin and ciprofloxacin under anaerobic conditions.

The kill kinetics of sparfloxacin and ciprofloxacin have been investigated under anaerobic conditions against Bacteroides fragilis and Escherichia coli. The results for E. coli were compared with those obtained under aerobic conditions. It was found that the quinolones were bactericidal under anaerobic conditions. This bactericidal activity is inhibited by the presence of chloramphenicol, a known protein synthesis inhibitor. Filamentation was seen with B. fragilis after 2 h exposure to either agent.

Anaerobiosis↗
PubMed1991

In-vitro susceptibility of Chlamydia pneumoniae (TWAR) to seven antibiotics.

A modification of an immunofluorescence method previously used to study the in-vitro antimicrobial susceptibilities of Chlamydia trachomatis was used to investigate the activity of seven antimicrobials against a strain of C. pneumoniae. Our results differed from those obtained by other workers, so we modified our original method and repeated the study. Adding antimicrobial to pre-infected cells gave higher MICs and MLCs than when cells were infected in the presence of the antimicrobials, and this difference in methodology could account for the discrepancy between our results and those of others. Of the antimicrobials studied, clarithromycin and its 14-hydroxy metabolite were the most active agents; sparfloxacin was more active than ciprofloxacin, but no more active than more conventional antichlamydial agents.

Anti-Bacterial Agents↗
PubMed1995

Detection of amphotericin B-resistant Candida isolates in a broth-based system.

Because of the limited ability of the National Committee for Clinical Laboratory Standards proposed M27P methodology to detect resistance to amphotericin B by Candida isolates, we sought to identify alternative media and pH conditions that could reliably identify resistant isolates. Antibiotic Medium 3 broth (also known as Penassay broth) buffered to pH 5 or pH 7 produced superior results and readily identified a series of resistant isolates.

Amphotericin B↗
PubMed1980

The aminoglycoside antibiotics.IV. Synthesis of aminodeoxy analogs of neamine.

An efficient synthesis of the key 3',4'-galacto epoxide intermediate 4 obtained from the known 5,6-O,O'-cyclohexylidene-N,N'-bis-(methoxycarbonyl)-4-O-[2,6-bis(methoxycarbony lamino)-alpha-D-glucopyranosyl]-2-deoxystreptamine (5) is described. Treatment of this epoxide with sodium azide, followed by reduction and acetylation, yielded the protected4'-amino-4'-deoxyneamine 18 (3',4'-diequatorial), whereas treatment with ammonia followed by acetylation yielded the protected 3'-amino-3'-deoxyneamine analog 19 with a diaxial configuration of its 3' and 4' positions. Reaction of the previously described protected 3',4'-allo epoxide 3 with sodium azide yielded separable mixtures of the protected 3'-amino-3'-deoxyneamine 14 and the protected diaxial 4'-amino-4'-deoxyneamine isomer 13, the ratios of products depending on the solvent temperature. Structural assignments for 13, 14, 18 and 19 were based on their PMR spectra. An additional 4'-amino-4'-deoxyneamine analog (24) with an axial configuration as its 4' position was also prepared by azide displacement of an approximately protected 4'-methanesulfonyl neamine intermediate 10. The five protected isomers were deblocked to yield a series of aminodeoxyneamine analogs (15, 16, 20, 21 and 25), all of which were less active in vitro than neamine against a group of Gram-positive and Gram-negative bacteria.

Bacteria↗
PubMed1979

Group B streptococci in blacks.

Vaginal swabs were taken from 60 Black women attending a family planning clinic and from 60 attending a special clinic for sexually transmitted diseases. Using selective media, the isolation rate for group B streptococci was 26,7% in the former group and 40,0% in the latter. The isolation rates of other streptococcal serogroups are also given. All group B streptococci isolated were uniformly sensitive to penicillin but resistant to gentamicin. Clinical details of 7 patients with group B streptococcal septicaemia are also given.

Adult↗