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Biomedical subjects

R T Evans

Publications and source records attributed to R T Evans.

At least 91 records · Page 5Linked to original sources
PubMed1983

Interlaboratory study of the proficiency of cholinesterase phenotyping.

We report the results of a proficiency survey into the accuracy of cholinesterase (EC 3.1.1.8) phenotyping undertaken by 12 laboratories over a three-year period, during which 21 samples of nine different genotypes were analyzed. Specimens from patients who were homozygous for the atypical variant AA or from UA and AF heterozygotes were identified without difficulty, but the less-well-recognized combinations AJ and AK were detected by only two and three laboratories, respectively. Some degree of difficulty was also experienced in differentiating among UU, UF, and FS specimens. Clinically significant ascription errors occurred on 11 occasions. We recommend that detailed studies of cholinesterase status be undertaken only by laboratories experienced in the assay, those likely to be able to produce accurate results and offer appropriate advice.

Cholinesterases↗
PubMed1982

Development and evaluation of an enzyme-linked immunosorbent assay (ELISA), using chlamydial group antigen, to detect antibodies, to Chlamydia trachomatis.

Chlamydial group antigen was extracted from Chlamydia trachomatis strain SA2(f) and used as the antigen for an ELISA. The assay was reproducible since chlamydial antibody titres differed by no more than twofold when sera were tested on up to eight occasions. In tests on sera from 75 patients attending venereal disease or rheumatology clinics, the results of the ELISA and of a microimmunofluorescence (MIF) technique were similar for 61 of the sera, that is an 81% agreement. However, the ELISA was a little more sensitive than the MIF technique and at least tenfold more sensitive than the complement fixation procedure. Chlamydial IgG antibody at a titre of 1/greater than or equal to 16 was detected by the ELISA in 6% of children's sera, in 20% of sera from adult patients attending hospital with non-venereal diseases and in 85% of sera from persons attending venereal disease or rheumatology clinics. IgM and IgG antibodies were detected also by the ELISA in the sera of chimpanzees and marmosets which had been infected genitally with C trachomatis and, in general, the titres were greater than those recorded by the MIF test. The value of the ELISA in comparison with the MIF test is discussed.

Adult↗
PubMed1981

Potential salicylamide antiplaque agents: in vitro antibacterial activity against Actinomyces viscosus.

A series of 55 salicylamides, including 3,5-dibromo-, 5-n-alkyl-, and 5-n-acylsalicyloyl derivatives of various anilines, heterocyclic amines, benzylamines, and alkylamines, was synthesized and evaluated for in vitro antibacterial activity against Actinomyces viscosus, an adherent oral microorganism implicated in periodontal disease. The in vitro minimum inhibitory concentrations of 15 4'-bromosalicylanilides were found to correlate (r = 0.92) with estimated log D values. Several nonhalogenated salicylanilides, such as 5-n-hexyl- (40) and 5-n-decanoyl-4'-nitrosalicylanilide (47), were found to exhibit higher levels of in vitro antibacterial activity against a number of Actinomycetes than did tribromsalan (1) or fluorophene (2).

Actinomyces↗
PubMed1981

Metabolic rate and blood hormone and metabolite levels of individuals susceptible to malignant hyperpyrexia at rest and in response to food and mild exercise.

Resting metabolic rate and the energy cost of performing a specific (light work load on a bicycle ergometer were measured in nine subjects susceptible to malignant hyperpyrexia (MHS) and nine control subjects, both fasting and following a 600-kcal meal. Blood glucose, lactate, pyruvate and serum triglycerides, thyroxine, cortisol, creatine kinase, growth hormone, and calcium and potassium levels at rest and immediately following exercise, after fasting and eating, were measured. There was no evidence of increased heat production in the MHS subjects compared with controls. The MHS subjects, however, showed a complete absence of dietary-induced thermogenesis with exercise. Compared with the controls, MHS subjects had higher insulin levels for essentially the same blood glucose values. Triglycerides in the MHS group rose steadily over the course of the experiment, whereas in the controls they did not vary from the initial value. Lactate did not rise as much with exercise in the MHS group but did nor fall with rest, and pyruvate did not change from resting fasting values, whereas in the controls it rose steadily. Differences were also found in thyroxine and cortisol levels between the MHS and control groups. The shunting of blood away from thermogenic tissue is suggested as a mechanism for the absence of diet-induced thermogenesis with exercise in the MHS group and the possibility of an underlying abnormality of cardiovascular (sympathetic) control mechanisms in these subjects is discussed. The biochemical abnormalities are discussed in relation to previous biochemical data from MHS humans and pigs and in relation to the abolition of dietary-induced thermogenesis.

Adult↗
PubMed1981

Follicular cervicitis--colposcopic appearances and association with Chlamydia trachomatis.

Follicular cervicitis was recognised in 15 (44 per cent) of 34 women who were examined colposcopically and who were sexual partners of men with non-gonococcal urethritis. Valid results of culture for Chlamydia trachomatis were obtained in 26 cases: the organism was isolated from the cervix of five of 11 women in whom follicular cervicitis had been diagnosed, but from only one of 15 whose cervices did not have this change. A similar correlation was not found for infection with Mycoplasma hominis or Ureaplasma urealyticum.

Adolescent↗
PubMed1981

Use of combined immunization routes in induction of a salivary immunoglobulin A response to Streptococcus mutans in Macaca fascicularis monkeys.

Various combinations of immunization routes were examined for ability to elicit or prolong (or both) a salivary secretory immunoglobulin A response to Streptococcus mutans strain Ingbritt (serotype c) in Macaca fascicularis monkeys. Intraductal (i.d.), per os (p.o.), and subcutaneous (s.c.) routes were utilized. Four groups of three to five monkeys each were immunized by the following schedules: group I--p.o., s.c., i.d.; group II--i.d., p.o., i.d.; group III--s.c., p.o., i.d.; and group IV--control. Immune responses in the serum and parotid fluid were quantitated by using passive hemagglutination assays with purified serotype-specific polysaccharide and by indirect immunofluorescent staining assays. Both s.c. and i.d., but not p.o., routes resulted in detectable serum antibody responses. Only i.d. immunization resulted in a measurable salivary response. Indirect immunofluorescent staining revealed specific secretory immunoglobulin A antibodies in the parotid fluid which correlated with passive hemagglutination titers. The p.o. procedures used in this study did not result either in a prolonged immune response or in measurable tolerance related to the humoral or secretory immune system.

Administration, Oral↗
PubMed1981

Satisfactory screening for cystic fibrosis with the BM meconium procedure.

The Boehringer Mannheim test (BM test) for cystic fibrosis has been applied to 15 734 neonates. A positive result occurred in 130, seven of whom were subsequently shown to have the disease. To our knowledge no cases have been missed. Tests have been performed centrally by experienced laboratory staff and the false-positive rate of 0.83% is considered acceptable. It is important to follow up weak as well as strongly positive reactions to the BM test strip.

Cystic Fibrosis↗
PubMed1981

Microbiological, serological, and histopathological features of experimental Chlamydia trachomatis urethritis in chimpanzees.

A laboratory-passaged genital strain of Chlamydia trachomatis and two unpassaged genital strains from patients with nongonococcal urethritis were inoculated intraurethrally into three young male chimpanzees. Chlamydia were recovered from the urethra of two animals and specific antibody responses were detected in all of them. Furthermore, a urethral polymorphonuclear leucocyte response, but not an overt discharge, occurred in all the chimpanzees about 1-2 weeks after inoculation. None of these events occurred in a chimpanzee inoculated with medium only. At necropsy three months after inoculation the submucosa of the urethra of one chimpanzee was densely infiltrated with small round cells. This suggests that a similar chronic lymphocytic response may occur in human chlamydial infection of the urethra.

Animals↗
PubMed1981

Taking cell cultures to the patient in an attempt to improve chlamydial isolation.

McCoy cell cultures were inoculated with 121 urethral and cervical specimens taken from patients attending one of two sexually transmitted disease clinics. The mean number of Chlamydia trachomatis inclusions was greater when the cultures were inoculated with the specimens and centrifuged in the clinic than when the specimens were first stored in liquid nitrogen. Furthermore, 18 of the 29 chlamydia-positive specimens produced larger numbers of of inclusions when inoculated immediately. Despite this, the isolation rate from specimens inoculated directly (22%) was about the same as from specimens which had been frozen (21%). Of the 30 occasions on which the cell monolayers were disrupted, 29 followed immediate inoculation. This may possibly have been due to some toxic factor in some of the specimens.

Bacteriological Techniques↗
PubMed1981

In vitro evaluation of antibiotics in the treatment of periodontal disease.

To assess the antibiotic sensitivity of subgingival microflora, chloramphenicol sodium succinate, clindamycin hydrochloride hydrate, disodium carbenicillin, doxycycline hyclate, erythromycin, minocycline hydrochloride, penicillin -G, spiramycin adipate, tetracycline hydrochloride and metronidazole were examined. Eleven patients with periodontitis were selected for sampling. Subgingival plaque samples were taken from three sites on each patient. Anaerobic incubation of the plaque samples for ten days was made on the blood agar plates which contained 0.1 microgram/ml and 5 microgram/ml of each antibiotic substance, respectively. According to the results of viable counts on the plates, it was determined that penicillin, tetracycline, doxycycline, and minocycline were most effective antibiotics with which to control the periodontal plaque organisms. Resistant organisms against those four antibiotics were generally Streptococcus species. "anaerobic vibrios", and Veillonella parvula. Some of the oral anaerobic isolates were also tested against all antibiotics at the concentration of 1 microgram/ml of each. Minocycline and clindamycin were the two most effective antibiotics against anaerobic subgingival purified strains and chloramphenicol was the least effective.

Anti-Bacterial Agents↗
PubMed1980

Plasma cholinesterase changes during pregnancy. Their interpretation as a cause of suxamethonium-induced apnoea.

Cholinesterase activities were measured on serum from 941 pregnant women distributed evenly throughout the 40 weeks of gestation. A rapid fall has been shown to occur during the first trimester to a level which did not alter significantly during the remainder of pregnancy. Even lower values were observed in 105 patients examined during the first 7 days following delivery. Enzyme activity was used to determine the probable incidence of a prolonged reaction to suxamethonium in obstetric patients. The risk was greatest in the immediate post partum period affecting 11% of the patients investigated.

Adolescent↗
PubMed1980

Suxamethonium apnoea associated with plasmaphoresis.

A patient is reported who developed suxamethonium apnoea as a result of reduction in serum cholinesterase activity secondary to both pregnancy and plasmaphoresis. Had the enzyme studies been carried out before operation, regional rather than general, anaesthesia would have been used. In order to avoid the problems associated with prolonged paralysis we recommend the measurement of cholinesterase activity in all patients who have undergone plasmaphoresis and in whom anaesthesia involving the use of suxamethonium is contemplated.

Adult↗
PubMed1980

In vitro antimicrobial susceptibility of Actinobacillus actinomycetemcomitans.

The agar dilution technique was used for determination of the antibiotic susceptibilities of 57 oral isolates and 2 nonoral isolates of Actinobacillus actinomycetemcomitans. Tetracycline, minocycline, and chloramphenicol inhibited more than 96% of the strains tested at a concentration of less than or equal to 2 micrograms/ml; 89% of the strains were inhibited by 2 micrograms of carbenicillin per ml. The other antimicrobial agents tested were less active. Approximately 10% of the A. actinomycetemcomitans strains were resistant to ampicillin, erythromycin, and penicillin G at concentrations of 32 to 64 micrograms/ml. These data suggest that tetracycline and minocycline may be valuable drugs in the treatment of A. actinomycetemcomitans infections.

Actinobacillosis↗
PubMed1980

Detection of Chlamydia trachomatis in rapidly produced McCoy cell monolayers.

The 24-hour delay between seeding coverslips with cells and inoculating samples for culture of chlamydiae was reduced to less than 1 hour by using coverslips which had been pre-treated with glutaraldehyde-activated gamma-aminopropyl-triethoxysilane. Treated coverslips were not toxic for McCoy cells and even one year after treatment monolayers formed rapidly on them. Furthermore, all of 13 Chlamydia trachomatis serotypes and one C. psittaci strain tested produced inclusions in such cell monolayers. In comparative tests, when there were large numbers of inclusions, more were always seen in conventionally produced monolayers than in monolayers on treated coverslips. However, when there were few inclusions, more were seen in the latter monolayers, a phenomenon observed with unpassaged chlamydiae in clinical specimens as well as in laboratory-passaged strains. The rapid method is, therefore, as sensitive for isolating chlamydiae as using conventionally produced monolayers.

Bacteriological Techniques↗
PubMed1980

A family segregating for E1j and E1k at cholinesterase locus 1.

A family segregating for the A, J, and K alleles at cholinesterase locus 1 is described. Several further examples of the AJ and AK phenotypes occur in this family, and one member of the family, by genetic analysis, is phenotype JK. In relation to possible succinylcholine apnoea, phenotypes AJ, AK, and JK should all be considered vulnerable.

Adolescent↗
PubMed1979

The effect of formaldehyde treatment before ensiling on the digestion of wilted grass silage by sheep.

1. Wilted perennial ryegrass (Lolium perenne L. cv. Endura) was ensiled without additive or after addition of a mixture of equal volumes of formic acid (850 g/kg) and formalin (380 g formaldehyde/kg) applied at a rate of 35 g formaldehyde/kg herbage crude protein (nitrogen x 6.25). The digestion of the two silages and the effect of supplemental N as urea or urea plus soya-bean meal on the digestion of the treated silage was studied using sheep fitted with a rumen cannula and re-entrant cannulas in the proximal duodenum and distal ileum. 2. The additive markedly reduced carbohydrate fermentation and protein degradation in the silo. 3. There were no significant differences between diets in rumen pH, dilution rate, volatile fatty acid production and the molar proportions of acetate, propionate and butyrate. However, rumen ammonia levels and the apparent digestibility of organic matter (OM), gross energy (GE) and cellulose in the stomach were significantly depressed (P less than 0.05) by the additive. It also reduced (P less than 0.05) the extent to which the N of the silage was degraded in the rumen and, with the treated silage, more microbial N was synthesized in the rumen than food N degraded, resulting in a net grain of N between mouth and duodenum, as compared to a net loss with the untreated silage. 4. Supplementation of the treated silage with urea or urea plus soya-bean meal significantly increased (P less than 0.05) the amount of food N degraded in the rumen and rumen ammonia levels but had no effect on the apparent digestibility of OM, GE and cellulose in the stomach or on the amount of microbial N reaching the duodenum. 5. The quantity of microbial amino acids entering the small intestine and the apparent digestibility of amino acids in the small intestine were similar for all four diets. However, the quantity of food amino acids reaching the small intestine was significantly higher with the three diets containing the treated silage and consequently the apparent absorption of amino acids from the small intestine was substantially higher with these diets than with the untreated silage.

Amino Acids↗