Vicious circles: looking back on resistance plasmids.
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Drug Resistance, Microbial↗
Biomedical subjects
J Davies
Publications and source records attributed to J Davies.
Thrombomodulin release in baboon sepsis: its dependence on the dose of Escherichia coli and the presence of tumor necrosis factor.
This study was designed to test whether thrombomodulin is shed in septic baboons and whether shedding is blocked by antibody to tumor necrosis factor (anti-TNF). Live Escherichia coli were injected intravenously into 24 baboons according to one of the following regimens: 5 x 10(8) or 2 x 10(9) cfu/kg (n = 6/8), 2 x 10(9) cfu/kg with placebo (n = 5), or pretreatment with 1 mg/kg anti-TNF 2 h before E. coli injection (n = 5). E. coli administration resulted in a significant release of thrombomodulin in a dose-dependent manner; however, thrombomodulin release was significantly attenuated (180 to 40 ng/mL) by anti-TNF pretreatment. This is parallel to the reduction of neutrophil activation (elastase). These results provide evidence for an E. coli dose-related and TNF-dependent thrombomodulin release into the plasma of septic baboons and suggest a possible role of anti-TNF in protection of the endothelium.
Alanine Transaminase↗
Tumor necrosis factor antibody treatment of septic baboons reduces the production of sustained T-cell suppressive factors.
Post-traumatic septic complications result from impaired cell-mediated immune function, which is caused in part by circulating T-cell suppressive factors (TSFs). We examined whether tumor necrosis factor alpha (TNF-alpha) antibody treatment in a baboon sepsis model influences the production of TSFs, including interleukin-10 (IL-10) and transforming growth factor-beta (TGF-beta). Sepsis was induced in anesthetized baboons by Escherichia coli infusion, and caused an increase in plasma levels of TNF, TSF activity, IL-10, and active TGF-beta, as well as a decrease in latent TGF-beta. TNF antibody pretreatment reduced TNF levels by 98%. Transient TSF activity (0-4 h) was only marginally influenced, while sustained TSF activity (8-24 h) was markedly reduced. TSF activity at 24 h correlated with peak TNF levels. IL-10 levels, coinciding with early TSF activity, remained unchanged by anti-TNF treatment. Levels of active TGF-beta and the drop in latent TGF-beta were decreased. We conclude that anti-TNF treatment reduces sustained TSF activity and may partially restore impaired cell-mediated immune function.
Animals↗
Making total quality a clinical priority.
Outlines the introduction of total quality systems into all clinical services within a community-based NHS Trust in the West Midlands. Provides practical details of each aspect of the quality-planning process. Shows the commitment of clinicians to "managing quality improvement".
Community Health Services↗
Tumor necrosis factor (TNF)-dependent shedding of the p55 TNF receptor in a baboon model of bacteremia.
We have tested the hypothesis that the tumor necrosis factor (TNF) plays a significant role in vivo in TNF receptor shedding and studied the release of TNF-binding protein 1 (TNF-BP1), the soluble fragment of the 55- to 60-kDa TNF alpha (TNF) receptor, in a baboon model of Escherichia coli bacteremia, using three different doses of bacteria in acute infection (8 h) experiments (n [animals] = 11) and a single dose in a subchronic infection (72 h) experiment. In the subchronic infection study, one group of animals (n = 6) was pretreated with a neutralizing murine monoclonal antibody to TNF (CB0006). Concentrations of TNF and TNF-BP1 in plasma were determined in specific, monoclonal antibody-based immunoassays. Untreated animals (n = 6) showed undetectable TNF concentrations (< 10 pg/ml at baseline), whereas TNF-BP1 levels in plasma were in the range of 2 ng/ml, similar to concentrations observed in humans. Infusion of bacteria resulted in a rapid, dose-dependent increase in plasma TNF concentrations that reached a maximal level after 2 h and returned to baseline within 6 h. TNF-BP1 concentrations also showed a dose-dependent increase to peak concentrations three- to fivefold above baseline within 2 h but, in contrast to TNF levels, remained significantly elevated for up to 48 h. In animals pretreated with antibody CB0006, circulating TNF was completely neutralized, and TNF-BP1 was significantly reduced. We conclude that TNF-BP1 is released in bacteremia and that release in vivo is partially dependent on the presence of TNF.
Acute Disease↗
Binding of Haemophilus influenzae to purified mucins from the human respiratory tract.
Mucins are high-molecular-weight glycoproteins and major constituents of the mucus layer which covers the airway surface. We have studied the interactions between bacteria, mucins, and epithelial cells from the human respiratory tract. Nontypeable strains of Haemophilus influenzae were found to bind to purified airway mucins in suspension and on solid phase. Mucins in suspension inhibited the attachment of these strains to nasopharyngeal epithelial cells, while mucin coating of the cells enhanced their binding. In contrast, strains of Streptococcus pneumoniae and encapsulated and other nontypeable H. influenzae strains failed to interact with mucins. These H. influenzae strains used other strategies for adherence to epithelial cells. The type b strain 770235 attached via fimbriae but also expressed a subcapsular adhesin that was detected in a capsule- and fimbria-defective mutant. Mucin pretreatment of these bacteria did not inhibit adherence, but mucin pretreatment of epithelial cells inhibited adherence, probably by shielding of the receptors for these adhesins. Non-mucin-binding nontypeable and encapsulated H. influenzae strains would, therefore, adhere only after disruption of the mucus layer and exposure of cellular receptors. Differences in tissue toxicity and invasiveness among H. influenzae strains may also be influenced by the mucin interactions of the strains.
Bacterial Adhesion↗
Sulphated proteoglycan is required for collecting duct growth and branching but not nephron formation during kidney development.
Kidney epithelia have separate origins; collecting ducts develop by ureteric bud growth and arborisation, nephrons by induced mesenchyme-epithelium transition. Both express sulphated glycosaminoglycans (GAGs) which are strikingly upregulated during nephron differentiation. However, sodium chlorate, an inhibitor of GAG sulphation, and the GAG-degrading enzymes heparitinase plus chondroitinase, did not prevent nephron development. In contrast, ureteric bud growth and branching were reversibly inhibited by the above reagents, the inhibition correlating quantitatively with sulphated GAG deprivation caused by a range of chlorate concentrations. Growth and branching could be independently restored during GAG deprivation by hepatocyte growth factor and phorbol-12-myristate acetate (PMA) respectively. Together these signalling effectors stimulated both branch initiation and growth. Thus growth and morphogenesis of ureteric bud involve distinct signalling pathways both regulated by GAGs.
Animals↗
Immunocytochemical localization of proteins.
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Immunohistochemistry↗
Helicobacter pylori infection in dentists--a case-control study.
To test the null hypothesis that frequent and multiple salivary exposure is not a risk factor for developing H. pylori infection, serum anti-H. pylori IgG from 179 dentists and dental students and 179 age-, sex- and socioeconomic-matched controls were assayed using an ELISA. Seroprevalence in dentists was 16% (11/70); clinical dental students 6% (3/47); and pre-clinical dental students 10% (6/62). There were no differences in H. pylori seropositivity between cases and controls. There was an increase in H. pylori seropositivity with age (chi (trend)2 9.04, p = 0.003). These data provide evidence that adults are not at high risk of developing H. pylori infection as a result of exposures to saliva from multiple sources.
Adolescent↗
Direct transfer of plasmid DNA between Streptomyces spp. and E. coli by electroduction.
We describe a simple and reliable method which allows the direct transfer of shuttle plasmids between Streptomyces spp. and E. coli. The method is based on the fact that plasmid DNA molecules can be released or taken up from cells under conditions of electroporation. When a suspension of a plasmid-containing Streptomyces spp. is mixed with electroporation-competent E. coli and submitted to an electric pulse, plasmid DNA transfer to the E. coli recipient takes place. Two different Streptomyces spp. (S. lividans TK23, or TK24 and S. rimosus 554w) were effective donors, and the method was successfully employed to transfer four different bifunctional vectors (pPM801, pFD666, pRL270X and pZG5) varying in size from 5.2-14.4 kb, to E. coli. This provides a convenient method for the analysis of Streptomycete transformants.
DNA, Bacterial↗
Plasma glutathione S-transferase as an early marker of posttraumatic hepatic injury in non-human primates.
We have hypothesized that the measurement of alpha-glutathione S-transferase (alpha-GST) in serum may provide a suitable sensitive marker of shock-induced liver damage. Six male adult baboons were studied. Hemorrhage was induced by blood withdrawal of 60-70% of the total blood volume down to an arterial pressure of 35-40 mmHg. Then the reinfusion was performed with the heparinized shed blood plus the same amount of Ringer's solution over the next 4 h. Before the start of hemorrhage, 2 mL/kg zymosan-activated plasma was infused to simulate trauma-related complement activation. alpha-GST antigen levels were determined using an anti-human alpha-GST immunoassay (Hepkit). Concentrations of alpha-GST at baseline in baboon were found to be 3.1 +/- 1.8 ng/mL; at the end of the shock period a significant increase in alpha-GST serum levels (74.8 +/- 13.8 ng/mL) was found. In contrast, transaminase levels did not significantly change. From the current evidence in posttraumatic non-human primates, which resemble the clinical situation in several aspects, alpha-GST measurements are a suitable marker of early hepatocellular injury.
Animals↗
Efficacy of subcutaneous heparin in prevention of venous thromboembolic events in trauma patients.
Trauma patients have an incidence of deep venous thrombosis (DVT) of 7% to 65%. Conflicting data exists regarding the impact of prophylactic anticoagulant therapy. The purpose of this study is to assess the efficacy of DVT prophylaxis based upon our data and a meta-analysis of the current literature. Literature review revealed five recent studies that met the following criteria: 1) Adult patients sustaining major trauma (injury severity score (ISS) > 10), 2) prospective surveillance for DVT using lower extremity duplex examinations, 3) clear documentation of method of DVT prophylaxis with particular attention to the use of anticoagulation and the corresponding incidence of DVT or pulmonary embolus (PE). Additionally, 66 trauma patients in our intensive care unit were prospectively identified and followed with duplex examinations. Patients received either anticoagulation DVT prophylaxis or pneumatic compression boots. An unpaired Student t test was used to compare the characteristics of patients with and without DVT. A Mantel-Haenszel chi-square meta-analysis was performed on the five recent studies and our own data to compare the incidence of DVT/PE in patients with and without anticoagulation. Meta-analysis of the literature included 1102 patients and demonstrated no benefit from anticoagulation for DVT prophylaxis in trauma patients (10% DVT/PE with anticoagulation versus 7 per cent DVT/PE without anticoagulation, P = 0.771). Our own population had a mean age of 38 +/- 17 years, ISS of 29 +/- 11 and a length of stay (LOS) of 34 +/- 22 days. Sixteen events occurred with 13 (20%) DVTs and three (4%) pulmonary emboli.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
Physiological and morphometric studies into the pathophysiology of detrusor hyperreflexia in neuropathic patients.
The in vitro responses of isolated detrusor strips obtained from neuropathic patients with neuropathic bladder dysfunction were found to be supersensitive to both carbachol [ED50 1.2 x 10(-6) M. versus 2.5 x 10(-6) M. in control strips; p < 0.005] and potassium chloride [ED50 41.8 mM. versus 49.3 mM. in control strips, p < 0.05]. There were no significant differences in the frequency-response curves obtained with intramural nerve stimulation. However, expressed as a percentage of the maximal response with carbachol, the maximal responses to intramural nerve stimulation in neuropathic strips were reduced [58.3 +/- 21% versus 74.4 +/- 18% for control strips; p < 0.005, Student t test]. Morphometric studies revealed a lower density of 'presumptive' cholinergic nerves in neuropathic detrusor (1.0 +/- 1.4 x 10(-4) microns -2 compared with 3.2 +/- 1.3 x 10(-4) microns -2 in controls, p < 0.05, Mann Whitney U test). The combined physiological and morphometric results were in keeping with a state of postjunctional supersensitivity of neuropathic detrusor secondary to a partial parasympathetic denervation of the smooth muscle. This may be an important factor in the etiology of detrusor hyperreflexia. The contractility of neuropathic tissue in response to field stimulation was found to be much lower than normal (2.4 +/- 1.5 g./10 mg. versus 5.9 +/- 3.0 g./10 mg., p < 0.001; Mann Whitney U test). This reduced contractility to neuronal stimulation might be responsible for some of the characteristics of bladder dysfunction that are seen in patients with similar neurological conditions.
Adult↗
Correlation of bone marrow minimal residual disease and apparent isolated extramedullary relapse in childhood acute lymphoblastic leukaemia.
We have used a polymerase chain reaction (PCR) technique capable of detecting one leukaemic cell in 10(5) normal cells to monitor minimal residual disease (MRD) in a retrospective study of childhood ALL. We were particularly interested in comparing MRD findings in patients in long-term remission, bone marrow relapse and apparent isolated extramedullary relapse (EMR). Archival slides were initially studied from 21 patients. However, on subsequent analysis, only 15 patients were informative at the molecular level. All seven patients with EMR had evidence of MRD in the bone marrow at the time of relapse. Five of the seven also had evidence of bone marrow MRD prior to EMR. In one of the seven patients, MRD was not detected in a bone marrow sample studied 5 months prior to EMR. The remaining EMR patient was not studied prior to EMR. Of five patients who remained in long-term remission (mean 144 months), three did not have detectable MRD at the end of induction therapy (2 months) and all five were MRD-negative at the end of treatment (36 months). This contrasts with the three patients who relapsed in the bone marrow at 8, 15 and 88 months post-treatment and who had evidence of MRD at the end of therapy.
Bone Marrow↗
Sensitivity and responsiveness of glucose removal to insulin decrease following systemic pancreatic venous drainage.
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Animals↗
Hemipancreatectomy, peripheral diversion of pancreatic venous drainage, and insulin sensitivity.
It has been previously noted that a mild insulin deficiency could increase insulin sensitivity in rats. The data shown here are consistent with such an observation in that the insulin resistance, which was induced by diversion of pancreatic venous drainage to the peripheral circulation, was corrected by the insulin deficiency which was secondary to the hemipancreatectomy performed. These results also help to explain some of the apparent inconsistencies that appear to be present in the comparison often made of insulin sensitivity following various transplantation procedures. Both the site of pancreatic venous drainage and any decrease in beta-cell mass which may accompany pancreas or islet transplantation appear to have independent and opposite effects on insulin sensitivity.
Animals↗
Pharmacological stress electrocardiography--when is it indicated?
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Cardiotonic Agents↗
Characterisation by molecular cloning of two genes from Streptomyces verticillus encoding resistance to bleomycin.
Extracts of a bleomycin (Bm)-producing Streptomyces verticillus ATCC15003 were found to possess an acetyltransferase activity which inactivates Bm in the presence of acetyl coenzyme A. DNA fragments of S. verticillus were introduced into S. lividans by cloning and transformants selected for resistance to Bm. Deletion mapping and subcloning of a 6-kb DNA fragment showed the presence of two resistance determinants, blmA and blmB. The acetyltransferase activity was encoded by blmB; nucleotide sequence analysis identified an ORF consisting of 301 amino acids (aa) proposed to be that of Bm acetyltransferase (Bat). S. lividans and Escherichia coli transformants harboring plasmids carrying blmB produced an acetyltransferase which modified and determined resistance to Bm and structurally related antibiotics; this resistance gene has potential as a selective marker in gene transfer studies. Nucleotide sequence analysis of blmA revealed an ORF encoding 122 aa that had significant sequence similarity to the gene encoding the Bm-binding protein (Shble) identified by Gatignol et al. [FEBS Lett. 230 (1988) 171-175] in Streptoalloteichus hindustanus, the tallysomycin-producer. The blmA gene was expressed in E. coli and the resulting protein, like the Shble protein, prevents in vitro Bm-induced DNA breakage.
Acetyltransferases↗