Search PubMed⌕ Search

Biomedical subjects

A E Wilkinson

Publications and source records attributed to A E Wilkinson.

At least 37 records · Page 2Linked to original sources
PubMed1980

Malate dehydrogenase from thermophilic and mesophilic bacteria. Molecular size, subunit structure, amino acid composition, immunochemical homology, and catalytic activity.

Malate dehydrogenases isolated from a number of mesophilic, moderately thermophilic, and extremely thermophilic bacteria yield upon denaturation subunits of molecular weight 32 000--36 000. Determination of their native molecular weights shows that some of the enzymes are dimeric and others are tetrameric; the two types are distributed in each of the three classes of bacteria. The amino acid compositions of the enzymes show no consistent trend that can be related to the progression of thermostability from the mesophile through the moderate thermophile to the extreme thermophile species. The tetrameric enzyme species all exhibit a high level of structural homology as judged by the criterion of immunological cross-reaction. Little cross-reaction occurs, however, between the tetramers and the dimers. The dimeric enzyme from the extreme thermophile, Thermus aquaticus, cross-reacts only weakly, if at all, even with dimeric malate dehydrogenases. The catalytic activities of the malate dehydrogenases vary over a wide range. Potassium chloride, organic solvents such as acetone, and the protein denaturants urea and guanidine hydrochloride activate a number of the malate dehydrogenases under the assay conditions employed. The diversity among the bacterial malate dehydrogenases, manifested not only in molecular size and subunit structure but also in properties such as catalytic activity and the dependence of this activity on electrolytes, organic solvents, and denaturants, indicates significant structural differences between several of these cognate enzyme species.

Amino Acids↗
PubMed1980

Sensitivity to penicillin of gonococci in different racial groups.

The distribution of the sensitivity to penicillin of gonococci isolated from 631 men and 290 women was analysed in relation to the racial origin of the patients and the type of source contact alleged by the men. No difference in the sensitivity patterns was found between strains from white patients from the United Kingdom and those from immigrants from the Caribbean area. Asian men harboured significantly more insensitive strains than men of other racial groups. Men of Caribbean stock who had been born in this country had significantly more infections due to fully sensitive strains. The reasons for these variations are not known, but one contributory factor may be differences within the racial groups in the proportions of infections contracted from prostitutes.

Ethnicity↗
PubMed1979

Sensitivity of Neisseria gonorrhoeae to antibiotics in London (1976-78).

Three surveys of the sensitivity of pretreatment isolates of gonococci to penicillin, ampicillin, tetracycline, spectinomycin, streptomycin, and co-trimoxazole were carried out during the period 1976-78. Compared with the results of previous surveys in the London area the decline in the proportion of strains of gonococci which are insensitive to penicillin appears to have halted. No changes were found in the levels of resistance to ampicillin, tetracycline, or spectinomycin during the period surveyed, although there was a slight increase in the proportion of strains requiring concentrations of 20 microgram spectinomycin per ml for inhibition. Streptomycin resistance has decreased considerably and 91% of strains are now sensitive to 10 microgram streptomycin per ml.

Ampicillin↗
PubMed1978

Isolation and characterization of isocitrate lyase from a thermophilic Bacillus sp.

Isocitrate lyase was isolated in homogeneous state from a thermophilic Bacillus. The enzyme has a mol.wt. of 180000 and a pI of 4.5 and contains threonine as the N-terminal residue. It resembles in size the cognate enzyme from the mesophilic bacterium Pseudomonas indigofera, but is smaller than the enzyme from the eukaryotic fungus Neurospora crassa. All three lyases are tetramers and similar in amino acid composition, but the thermophile enzyme is distinctive from its mesophilic coutnerparts in possessing a lower catalytic-centre activity, greater resistance to chemical and thermal denaturation and fewer thiol groups and in being strongly activated by salts. Salt activation, by 0.4M-KCl, is about 3-fold at 30 degrees C and pH 6.8 and weakens progressively as the temperature or pH is raised. The activation is probably due to a change in the enzyme conformation caused by the electrolyte modifying the interaction between charged groups or between hydrophobic groups in protein. The possible significance of the salt activation, of the relative paucity of thiol groups and of the greater resistance to chemical denaturants is discussed. Besides its effect on the Vmax., KCl produces large increases in the magnitude of several kinetic parameters. A rise in reaction temperature from 30 to 55 degrees C produces a somewhat similar result. In view of these peculiar features, the patterns of inhibition of enzyme activity by compounds such as succinate and phosphoenolpyruvate were examined at 30 and 55 degrees C in the presence and absence of KCl.

Amino Acids↗
PubMed1978

Prevertebral soft-tissue swelling as a sign of undisplaced fracture of the odontoid process.

Marked evanescent swelling of the prevertebral soft tissues has been found in 2 patients with undisplaced fractures of the odontoid process. In one patient the significance of the swelling was appreciated only in retrospect and after shift had occurred at the fracture site. The experience gained from this patient alerted the radiologist and the clinician so that any further damage could be averted in the second patient. All patients with head injuries require radiography of the cervical spine. Soft-tissue swelling anterior to the atlas should be viewed in a serious light.

Cervical Vertebrae↗
PubMed1977

Reappraisal of the left lateral decubitus X-ray in splenic rupture.

The lateral decubitus view of the barium-filled stomach has been reassessed in a series of 42 patients with possible splenic rupture and compared with a group of 17 patients with splenomegaly. Displacement of the gastric fundus of more than 4 cm from the inner rib margin is highly suggestive of splenic rupture. Where doubt exists, the test should be repeated within a short while. Peritoneal lavage and a full blood count investigation both add to the diagnostic accuracy.

Adult↗
PubMed1976

A comparison of brain heart infusion blood agar sterilized by filtration and heat on the growth of Neisseria gonorrhoeae.

The growth of Neisseria gonorrhoeae on brain heart infusion blood agar in which the base was sterilized by filtration has been compared with growth on the same medium sterilized by heat. Colonies were larger on the unheated medium, and autoclaving at 115 degrees C of 121 degrees C for 15 minutes was accompanied by a progressive decrease in colony size. Viable counts on the three media showed no difference in end points. Colonies on the unheated medium were usually large enough to be easily recognizable after overnight incubation.

Agar↗
PubMed1976

IgM-FTA test in syphilis in adults. Its relation to clinical findings.

IgM-FTA tests have been carried out on 209 sera from 169 patients with treated or untreated syphilis at various stages and on 128 sera from 109 patients, born in areas where yaws is or was prevalent, with treated or untreated latent treponemal disease. IgM anti-treponemal antibody was found in virtually all cases of untreated early or early latent syphilis but in only 23 per cent. of sera from patients with untreated late latent syphilis. After treatment the antibody usually disappeared within one year, but it persisted in a minority of patients, including some treated for late symptomatic or congenital syphilis. Except in isolated cases there was no clinical evidence to suggest continued disease activity, although a third of the patient in whom the antibody persisted for more than 2 years after treatment were noted to be homosexuals. The test may assist in differentiating untreated early latent from late latent syphilis.

Adult↗
PubMed1975

A comparison between sorbent and Reiter sonicate in the absorbed fluorescent treponemal antibody test.

Some syphilitic sera still fluoresce with Reiter treponemes as the antigen after treatment with the sorbent used in the FTA-ABS test; this finding indicates incomplete removal of group antitreponemal antibody. Levels of this antibody in normal sera have been studied in relation to the titration of sorbent for use in the test. A comparison has been made of the results of FTA-ABS tests with sorbent and Reiter sonicate and the TPI test on 1141 selected problem sera. Results with the sonicate displayed closer agreement (60.9%) with those of the TPI test than did tests with sorbent 40.8%). The use of sonicate as the sorbing agent is thought to improve the performance of the FTA-ABS test without diminishing its sensitivity.

Absorption↗