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Biomedical subjects

E G Smith

Publications and source records attributed to E G Smith.

14 recordsLinked to original sources
PubMed1992

Primary humoral antibody response to Coxiella burnetii, the causative agent of Q fever.

Of 147 patients with acute Q fever diagnosed during a major outbreak in Birmingham, England, in early summer 1989, 41 provided sets of sera which allowed us to make a detailed analysis of the primary humoral immune response. Antibody titers specific for Coxiella burnetii were measured by the complement fixation test and by an immunoglobulin M (IgM)- and IgG-specific indirect immunofluorescence test. The relative avidity of specific IgGs was determined by the indirect immunofluorescence test with and without treatment of antigen-antibody complexes with 8 M urea. The IgG subclass responses after primary infection and their avidities were also determined for a limited number of paired serum specimens. Specific IgM titers persisted for more than 6 months in the majority of cases and were therefore not a sufficient criterion for the diagnosis of recent infection. However, for serial samples the antibody titer ratios (IgG/IgM) and the ratios (IgG titer with treatment/IgG titer without treatment) that indicated relative avidity changed significantly, depending on the time postinfection. Within the IgG class, the C. burnetii-specific antibody response over time was almost exclusively represented by subclass 1 molecules, which thus showed affinity maturation.

Antibodies, Bacterial↗
PubMed1991

Transcriptional regulation of cytochrome d in nitrogen-fixing Azotobacter vinelandii. Evidence that up-regulation during N2 fixation is independent of nifA but dependent on ntrA.

Cytochrome d has been postulated to be the "respiratory protection" oxidase of Azotobacter vinelandii, allowing this organism to fix nitrogen under aerobic growth conditions. We have previously cloned and characterized the structural genes for the A. vinelandii cytochrome d (cydA and cydB). The cyd genes are co-transcribed, yielding an mRNA of approximately 3.6 kilobase pairs. The level of the cyd message was 2-3-fold higher in cells that were fixing nitrogen, as compared with non-nitrogen-fixing cells. RNase protection analysis was used to determine the transcriptional start site at 275 bases upstream of the initiator ATG of cydA, and this start site was the same for nitrogen-fixing and non-nitrogen-fixing cells. The cyd promoter has sequence similarities to the canonical Escherichia coli promoters, which are transcribed by the major sigma 70 form of RNA polymerase. Plasmid-borne lacZ transcriptional fusions were constructed, using approximately 650 base pairs of 5'-upstream sequences of the cyd structural genes. This region had a strong promoter activity which was further up-regulated 1.5-2.5-fold upon the induction of nitrogen fixation. The cyd-lacZ fusions were characterized in a nifA- as well as an ntrA- background. Mutations in neither of these nif regulatory genes affected the constitutive expression of cyd under non-nitrogen-fixing conditions. However, the up-regulation of this promoter during the induction of nitrogen fixation was abolished only in the ntrA- background. Based on these results, the cytochrome d promoter of A. vinelandii belongs to a new class of nitrogen-regulated promoters which, unlike the authentic nif genes, does not require the ntrA gene product for its expression. The up-regulation of this promoter during nitrogen fixation, however, requires the ntrA gene product.

Amino Acid Sequence↗
PubMed1991

Derived guinea pig compound VIIIth nerve action potentials to continuous pure tones.

A technique is described which verifies neural activity to a very faint continuous sine wave through subtraction of two different far-field whole nerve action potentials from one another. A brief transient is presented to an animal in order to elicit a supra-threshold action potential. The technique is then repeated, but on the second trial a near-threshold sine wave is mixed with the transient and another action potential is collected. The resultant evoked is then subtracted from the evoked potential generated by the transient alone and a small but persistent difference potential is acquired that presumably represents the unit activity occupied by the continuous sine wave. Four experiments are presented to show the validity of this technique, along with a surprising stability of the derived-response latency despite a 30 dB range of the probes. The technique may have promise in predicting behavioral responses to sinusoids acquired from individual animals.

Acoustic Stimulation↗
PubMed1991

Objective auditory threshold estimation using sine-wave derived responses.

A derived response method of acquiring frequency specific auditory evoked potentials that utilizes a pure tone in combination with a toneburst is applied to the measurement of hearing sensitivity in guinea pigs, chinchillas and pocket gophers. Two experiments which demonstrate that thresholds acquired via tone-derived responses are 10 to 15 dB more sensitive than thresholds to solitary tonebursts are described. The derived potentials approximate behaviorally acquired thresholds at frequencies of 0.5 kHz and above. This technique may provide a more rapid means of assessing hearing sensitivity in laboratory animals than by behavioral means.

Acoustic Stimulation↗
PubMed1990

Serological response in Enterococcus faecalis endocarditis determined by enzyme-linked immunosorbent assay.

Enterococcus (Streptococcus) faecalis expresses three species-specific surface protein antigens of molecular weights 73,000, 40,000, and 37,000. On Western blotting (immunoblotting), they were detected strongly by immunoglobulin G (IgG) in sera from patients with E. faecalis endocarditis, but not in sera from patients with other E. faecalis infections or with endocarditis due to other streptococci. We developed an enzyme-linked immunosorbent assay system to measure IgG, IgM, and IgA levels to these antigens and evaluated its potential as a serodiagnostic test for E. faecalis endocarditis. The test correctly diagnosed E. faecalis endocarditis in 15 of 16 cases. Of 10 cases of endocarditis due to other streptococci and 10 E. faecalis infections other than endocarditis, 9 and 8, respectively, gave negative results. The test should prove particularly useful in culture-negative cases, for which choice of appropriate antibiotic therapy for E. faecalis endocarditis is vital.

Antibodies, Bacterial↗
PubMed1987

Cryptosporidium-associated diarrhoea in children.

Over a 3-month period during summer, 30 out of a group of 194 children admitted with a primary diagnosis of gastro-enteritis with dehydration were found to excrete cryptosporidium oocysts in their stools. On retrospective analysis, children with cryptosporidia in their stools had a significantly higher mortality than those without. They spent a longer time in hospital and were more likely to have intestinal salmonella infection. They also had a higher incidence of bronchopneumonia. They were not significantly different from the group of children without cryptosporidia in respect of age, mass for age, duration of symptoms prior to hospitalization, prior treatment, or severity of metabolic derangement on admission. Since cryptosporidiosis has a recognized association with immune deficiency, the presence of cryptosporidium oocysts in the stools of our children with diarrhoea may be a pointer to morbidity and mortality.

Cryptosporidiosis↗
PubMed1987

Serodiagnosis of Streptococcus faecalis endocarditis by immunoblotting of surface protein antigens.

We describe a method for the serodiagnosis of Streptococcus faecalis in infective endocarditis which could be of value in culture-negative cases. Serum-grown cells of S. faecalis produced three major characteristic protein antigens (73,000, 40,000, and 37,000 molecular weight) which were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of solubilized whole cells. After electrophoretic transfer to a nitrocellulose membrane, these antigens were visualized by probing with serum from patients with endocarditis caused by S. faecalis. Serum from patients with endocarditis caused by other organisms did not react with the S. faecalis-specific antigens. This procedure should facilitate positive early diagnosis of S. faecalis endocarditis or establish its absence in culture-negative cases.

Antibodies, Bacterial↗
PubMed1979

Antibiotic susceptibility of Haemophilus vaginalis (Corynebacterium vaginale) to 21 antibiotics.

A total of 56 strains of Haemophilus vaginalis were tested for their in vitro susceptibility to 21 antimicrobial agents by an agar dilution method. All strains were inhibited by 1 mug or less of penicillin, ampicillin, carbenicillin, and vancomycin per ml. The cephalosporins were less active; 4 mug of cefazolin per ml, 16 mug of cephalothin per ml, or 128 mug of cephalexin per ml was required to inhibit all strains. Kanamycin, gentamicin, tobramycin, and neomycin were relatively inactive against H. vaginalis. All strains were inhibited by 4 mug of streptomycin per ml and 2 mug of chloramphenicol per ml. Only 57% of the strains were inhibited by 4 mug of tetracycline per ml, whereas 43% were inhibited by 16 to 64 mug/ml. The combination sulfamethoxazole/trimethoprim was relatively inactive against H. vaginalis. All strains tested exhibited minimal inhibitory concentrations of >/=128 mug when tested against colistin, nalidixic acid, and sulfadiazine. Erythromycin and clindamycin were the most active of the antibiotics tested; for all strains the minimal inhibitory concentrations were </=0.06 mug/ml.

Anti-Bacterial Agents↗
PubMedDate not supplied

Imipenem/cilastatin in the treatment of serious bacterial infections.

Imipenem (N-formimidoyl thienamycin) is a new carbapenem beta-lactam antibiotic with a broad antibacterial spectrum. Forty-five patients were treated with either 500 or 1,000 mg of imipenem/cilastatin four times daily, the duration varying according to clinical response. The diagnoses were urinary tract infection, 10 patients; septicemia, six; intraabdominal sepsis, six; pneumonia, six (two cases of Legionnaires' disease); skin and soft tissue infection, four; and other diagnoses, 13. Of the 32 clinically assessable patients, 17 were cured, nine improved, three died, and three were withdrawn from the trial. Of 21 patients who were microbiologically assessable, 13 were cured. In six cases of complicated urinary tract infection, the organism--which had been eradicated from the urine during treatment--reappeared after completion of antibiotic therapy. Two patients developed adverse clinical reactions that were thought to be drug-related (drug-induced fever and nausea plus vomiting, respectively). Both patients had mildly abnormal results in liver function tests, and one developed a positive direct Coombs' test. Fifty-seven percent of the patients developed some degree of phlebitis, which was moderate to severe in 19%. In this study imipenem/cilastatin proved to be a highly effective agent for the treatment of a variety of serious bacterial infections.

Adolescent↗
PubMedDate not supplied

An epidemiological study of severe osteoarthritis.

A study was made of the relationship between weight, education, use of tobacco and alcohol, participation in athletics and family history of arthritis and severe osteoarthritis of the hip. Estimated relative risk of osteoarthritis was highest for those whose weight was at least 20% or more above ideal, having more than a high school education or with a familial history of arthritis. There was no association between severe osteoarthritis and participation in high school athletics or regular use of alcohol.

Aged↗