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Biomedical subjects

M E Ward

Publications and source records attributed to M E Ward.

At least 145 records · Page 8Linked to original sources
PubMed1982

Control mechanisms governing the infectivity of Chlamydia trachomatis for hela cells: modulation by cyclic nucleotides, prostaglandins and calcium.

Chlamydia trachomatis causes common infections of the eyes and genital tract in man. The mechanism by which this obligate intracellular bacterium is taken into epithelial cells is unclear. The results described here support the concept that chlamydial infections of HeLa cells is under bidirectional cyclic nucleotide control, with guanosine 3':5'-cyclic monophosphate (cGMP) acting as a stimulator, and adenosine 3':5'-cyclic monophosphate (cAMP) as an inhibitor. Treatment of the HeLa cells with the divalent cation ionophore A23187, with carbamoylcholine, or with prostaglandins known to increase the concentration of endogenous cGMP, also increased host cell susceptibility to chlamydial infection. Cyclic GMP was only effective if added at or before chlamydial inoculation, suggesting that its main effect was on chlamydial uptake. The stimulatory effect of cGMP, but nt antagonism, by cAMP, was abolished if the cells were first treated with any of four different inhibitors of prostaglandin synthesis, suggesting a critical role for endogenous prostaglandin synthesis. Centrifugation of chlamydiae on to host cells was followed by a rapid increase in the mobility of Ca2+ across the cell membrane. The interrelationships of these observations and the possibility that chlamydiae and other intracellular pathogens might evoke alterations in host cell prostaglandin and cyclic nucleotide concentrations to aid their own uptake are discussed.

Bucladesine↗
PubMed1982

Outpatient sedation for oral surgery. A new technique using etomidate.

In an attempt to exploit the benefits and to reduce the incidence of side-effects of etomidate during intravenous sedation for nervous patients undergoing oral surgery under local analgesia, a series of four clinical trials were undertaken: a pilot study in which etomidate was preceded by a combination of pentazocine and diazepam; a double-blind study in which saline was randomly substituted for the etomidate, and two further studies in which the administration of etomidate was preceded by that of either pentazocine or diazepam alone. The combination of a small dose of diazepam (0.1 mg/kg) with an initial dose of etomidate (0.1 mg/kg) followed by increments of the latter as necessary proved to be most successful in reducing the severity of unwanted reactions while retaining the unique advantages of etomidate.

Adult↗
PubMed1982

Ophthalmia neonatorum in the 1980s: incidence, aetiology and treatment.

In a survey of 450 consecutive births in Southampton a 12% incidence has been found of ophthalmia neonatorum. Bacterial pathogens were isolated from only one-third of the cases, while nonpathogens were isolated from as many cases as controls. There was an incidence of chlamydial infection of 3.7 per 1000 live births, while Neisseria gonorrhoeae could not be found. Chloramphenicol is recommended for topical antibacterial treatment, but chlamydial infection will not respond; it must be considered in 'resistant' cases, when both the neonate and the parents will need treatment with erythromycin or tetracycline.

Anti-Bacterial Agents↗
PubMed1981

Polypeptide composition of Chlamydia trachomatis.

Strains of Chlamydia trachomatis representative of 14 serotypes were grown in HeLa 229 cells. HeLa cell susceptibility to chlamydial infection was increased by treating the host cells with DEAE-dextran. Optimal conditions of DEAE-dextran treatment were determined for each serotype of C. trachomatis to maximize chlamydial yields. Chlamydial polypeptides were selectively radiolabelled with 3H-labelled amino acids in the presence of emetine, an inhibitor of HeLa cell protein synthesis. The radiolabelled chlamydiae were purified from host cell components by density gradient centrifugation and their polypeptide composition was determined by sodium dodecyl sulphate-polyacrylamide gel electrophoresis. The distribution of the major chlamydial polypeptide of 38 000 to 42 000 daltons amongst the different serotypes correlated closely with the predominant human infections caused by each serotype. Lymphogranuloma venereum agents possessed a unique polypeptide of 118 000 daltons not found amongst trachoma inclusion conjunctivitis strains of chlamydiae. Chlamydial surface polypeptides were selectively radiolabelled with 125I by lactoperoxidase-catalysed oxidation. The major chlamydial polypeptide and polypeptides of 155 000 and 29 000 daltons were thus identified as surface polypeptides of the chlamydial elementary body. It is suggested that the 155 000 dalton polypeptide is a species-specific antigen, the major polypeptide is the principal outer membrane protein, and the 29 000 dalton polypeptide is the type-specific antigen.

Chlamydia trachomatis↗
PubMed1979

Sedation for outpatient conservative dentistry. A trial of pentazocine supplementation to diazepam and local analgesia techniques.

Pentazocine 30 mg. or 15 mg or a placebo, was administered randomly to forty-nine patients undergoing conservative dental treatment in combination with a local analgesic block and intravenous diazepam. Simple cardiorespiratory measurements were made throughout the treatment period. Patients in the 30 mg pentazocine group required some 6 mg diazepam less than the placebo (control) group (P less than 0.05). Patients receiving 15 mg pentazocine also required less diazepam compared to the control group, but this difference was not statistically significant. There were no significant differences between the three groups either in recovery times or the cardiorespiratory measurements.

Adolescent↗
PubMed1979

Early detection of Chlamydia trachomatis using fluorescent, DNA binding dyes.

HeLa 229 cells were infected with genital tract strains of Chlamydia trachomatis. After incubation for varying times the infected cells were fixed and stained with the fluorescent DNA binding dyes Hoechst 33258 or DAPI for comparison with conventional Giemsa stain. Fluorochrome-treated preparations were examined by incident ultraviolet fluorescence microscopy and the Giemsa-stained preparations by dark-ground light microscopy. Chlamydial inclusion bodies could be identified unambiguously as early as 18 hours after infection of HeLa 229 cells using either Hoechst 33258 or DAPI but not until some 48 hours in Giemsa-stained preparations. The DNA rich chlamydial elementary bodies in infected egg yolk suspension were readily detected using Hoechst 33258. The fluorescent dye technique was simpler and more rapid than Giemsa staining. Using Hoechst 33258 it is possible to speed up the identification of chlamydial isolates growing in tissue culture.

Benzimidazoles↗
PubMed1978

The surface properties of Neisseria gonorrhoeae: determinants of susceptibility to antibody complement killing.

Monovalent rabbit antisera were prepared to highly purified gonococcal lipopolysaccharide (LPS), to pili and to two major purified outer envelope proteins. All these antisera were free from significant specific IgM antibody and were standardized to 4 microgram specific IgG antibody per test, permitting accurate comparisons between the different gonococcal surface antigens as triggers of the complement-dependent bactericidal reaction. LPS was the most effective antigen at inducing a bactericidal response to homologous and heterologous gonococci, followed by the two individual outer envelope proteins. Pili were relatively ineffective. Strain P9 gonococci grown in vivo or which possessed a 'capsule' in vitro were more resistant to serum killing than the non-capsulated parent strain. One highly susceptible strain, F62, which was killed by complement in the absence of any LPS antibody, was able to directly activate complement by the alternative pathway.

Antibodies↗
PubMed1978

A reappraisal of the role of Pityrosporum orbiculare in pityriasis versicolor and the significance of extracellular lipase.

Pityrosporum orbiculare is an obligate lipophilic yeast in vitro, which suggests it possesses an extracellular lipase crucial for nutrition. If present in vivo, the enzyme would enable the yeast to utilize skin surface lipids, which may therfore play an important role in the pathogenesis of pityriasis versicolor. Cultured P. orbiculare and biopsy material from patients with pityriasis versicolor were investigated for the presence of lipase by electron microscope histochemistry. At sites of lipase activity, fatty acid hydrolyzed from Tween 80 substrate reacts with Ca++ ions to form an insoluble Ca++ soap. Exchange of Ca++ with Pb++ enables the sites of lipase activity to be visualized as electron dense deposits of insoluble lead soap. Surface lipase activity was apparent when the technique was applied to P. orbiculare grown on lipid containing medium and its specificity confirmed by removal of substrate and inhibition by di-isopropyl fluorophosphate and quinine hydrochloride, but not by sodium fluoride. When the same technique was applied to stratum corneum infected with Pityrosporum furfur (Malassez), no reaction product could be detected. It is postulated that lipase, although critical for fungal nutrition in vitro, is unlikely to be of importance in vivo. Skin surface lipids are therefore probably not relevant to the pathogenesis of pityriasis versicolor.

Histocytochemistry↗
PubMed1977

Metabolism of 14C-labelled alphaxalone in man.

The metabolism of 14C-labelled alphaxalone, dispensed as Althesin, was studied in normal patients, patients with obstructive jaundice and patients with chronic renal disease and anuria. The radioactive label was removed rapidly from the plasma following i.v. administration. The major portion of the label was excreted in the urine. In patients with normal renal function 14C-labelled alphaxalone is probably taken up by the liver, metabolized to a more polar compound and excreted in the urine; a small amount is excreted in the bile. In the patient with anuria, hepatic uptake appears to be relatively normal and the length of action of Althesin is not prolonged. It is assumed that in such patients the eventual route of excretion is via the bile and faeces.

Alfaxalone Alfadolone Mixture↗
PubMed1977

Conditions for tracheal intubation following fazadinium and pancuronium.

Intubating conditions were studied in two groups of patients who received either fazadinium 1 mg/kg or pancuronium 0.1 mg/kg (group 1), or either fazadinium 0.5 mg/kg or pancuronium 0.08 mg/kg (group 2). In group 1 intubating conditions were studied at 30, 45, 60 and 75 s after injection of the relaxant drug, and in group 2 at 60 s after injection. Fazadinium provided better intubating conditions than pancuronium during the first 60 s after administration in group 1 (P less than 0.01). In group 2 there was no significant difference between the conditions provided by the two drugs.

Humans↗