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Biomedical subjects

J F Richardson

Publications and source records attributed to J F Richardson.

At least 37 records · Page 2Linked to original sources
PubMed1992

Oral motor control, posturing, and myofunctional variables in 8-year-olds.

One hundred thirty-three rural second graders were evaluated for diadochokinetic abilities and myofunctional variables. Single-syllable diadochokinetic rates were significantly correlated with open-mouth resting postures. Slow trisyllable diadochokinetic rates were significantly correlated with a dentalized resting tongue posture and dentalized swallow patterns. The implications of these relationships are discussed.

Articulation Disorders↗
PubMed1992

Evaluation of methods for typing coagulase-negative staphylococci.

One hundred and forty-two coagulase-negative staphylococci (CNS) isolated from dialysate effluent or skin of patients receiving continuous ambulatory peritoneal dialysis (CAPD) were typed by extended antibiogram (16 antibiotics) and biotype (26 reactions). These isolates were then typed by supplementary methods to determine the most suitable typing method for an epidemiological study of antibiotic resistance. These included phage typing, reverse phage typing, plasmid typing, whole-cell protein typing by SDS-PAGE with analysis by densitometry, and immunoblotting. The percentage of isolates typed successfully by the supplementary methods were: phage typing 20%, reverse phage typing 0%, plasmid typing 66%, SDS-PAGE 100%, immunoblotting 100%. The discrimination of each method was: phage typing 20%, plasmid typing 37%, SDS-PAGE 69%, immunoblotting 57%. Reproducibility was 88% for phage typing and 97% for plasmid typing. The reproducibility of the whole-cell protein typing was 83% if the same extracts were used but only 43% when separate protein extracts were analysed on separate occasions. However, strain relatedness was highly reproducible. The determination of an antibiogram-biotype profile was not a sufficiently accurate typing method for an epidemiological study of antibiotic resistance. Whole-cell protein typing by SDS-PAGE or immunoblotting was technically demanding but was the most effective of the supplementary methods for detecting erroneous discrimination and false matching produced by antibiogram-biotype combinations.

Bacterial Proteins↗
PubMed1990

Beta-lactamase-negative, methicillin-resistant Staphylococcus aureus in a newborn nursery: report of an outbreak and laboratory investigations.

An outbreak of skin infection caused by a beta-lactamase-negative strain of methicillin-resistant Staphylococcus aureus (MRSA) occurred during a five-week period in a newborn nursery. Twelve babies, two mothers and two members of staff were involved. One baby had a diagnosis of staphylococcal scalded skin syndrome and two others required treatment with antibiotics. The infecting strain produced exfoliative toxin A. It was thought that it had been introduced from a different maternity unit by a nasal carrier. Laboratory investigations tended to support this hypothesis.

Bacteriophage Typing↗
PubMed1988

Complex typing of methicillin-resistant Staphylococcus aureus (MRSA).

To discriminate between methicillin-resistant Staphylococcus aureus from 5 nosocomial outbreaks and from sporadic nosocomial infections, the efficacy of a complex typing scheme by phage typing, biochemical typing, resistance phenotype, plasmid profiles, plasmid patterns and attribution of resistance determinants to the chromosome was studied. In addition to the International Basic Set and experimental phages 88-93, 10 experimental phages from the Public Health Laboratory Service, Colindale, London, were used for phage-typing. The 10 experimental phages from PHLS in particular, in combination with plasmid profiles and plasmid patterns, were of special discriminative value.

Bacterial Typing Techniques↗
PubMed1988

Supplementary phages for the investigation of strains of methicillin-resistant Staphylococcus aureus.

Nineteen experimental phages were derived by mitomycin-C induction from methicillin-resistant strains of Staphylococcus aureus collected world-wide. They were assessed for their ability to distinguish isolates of a methicillin-resistant strain of S. aureus epidemic in the London area from other British strains, both sensitive and resistant to methicillin. The experimental phages were most active against strains of phage groups III and I + III. One phage was related to the phages of lytic group I. A typing pattern common to isolates of the epidemic strain was identified and used as an aid in the recognition of this strain. Ten of the phages were retained for further study.

Bacteriophage Typing↗
PubMed1988

Evaluation of electrophoretic methods for typing methicillin-resistant Staphylococcus aureus.

Three electrophoretic methods of typing methicillin-resistant Staphylococcus aureus (MRSA) strains--plasmid profiles (PP), whole-cell protein profiles (WCPP) and immunoblotting profiles (IP)--were evaluated and compared with phage typing. The results obtained with isolates from 12 outbreaks were compared both within the outbreaks, to determine the consistency of results, and between outbreaks. There was generally good agreement between the typing methods but in only six outbreaks did all four methods indicate the same relationship between isolates. WCPP comprised more than 50 bands; when differences occurred, they were seen in only a few bands. In contrast, IP comprised only one or two major bands and the differences were much easier to interpret. The PPs of many of the isolates were similar; many isolates contained a plasmid of mol. wt (18-25) x 10(6). In several outbreaks both WCPP and IP showed minor differences between isolates that were not apparent with phage typing. When comparisons were made between the 12 index strains and an isolate representing the London epidemic MRSA strain, phage typing and WCPP were the most discriminatory methods; both gave nine distinct patterns, whereas there were eight IPs and only six PPs amongst the 13 strains. It was concluded that both WCPP and IP could provide valuable epidemiological data on MRSA and that IP was the easiest of the three methods to interpret.

Bacterial Proteins↗
PubMed1986

Bacteriological characters of strains of Staphylococcus aureus submitted to a reference laboratory related to methicillin resistance.

Methicillin-resistant Staphylococcus aureus (MRSA) strains present an increasing clinical problem. Analysis of 2679 strains submitted to a reference laboratory in the first quarter of 1983 and 3050 strains submitted in summer 1984 showed 479 and 593 multi-resistant strains. The proportion of methicillin-resistant strains classified as epidemic rose from 5.9 to 10.2%. Other methicillin-resistant strains continued to occur but other methicillin-sensitive multi-resistant strains appeared to fall. A strain with defined characters could be recognized in the Thames regions.

Bacitracin↗
PubMed1986

The induction of reciprocal translocations in rhesus monkey stem-cell spermatogonia: effects of low doses and low dose rates.

The induction of reciprocal translocation in rhesus monkey spermatogonial stem cells was studied following exposure to low doses of acute X rays (0.25 Gy, 300 mGy/min) or to low-dose-rate X rays (1 Gy, 2 mGy/min) and gamma rays (1 Gy, 0.2 mGy/min). The results obtained at 0.25 Gy of X rays fitted exactly the linear extrapolation down from the 0.5 and 1.0 Gy points obtained earlier. Extension of X-ray exposure reduced the yield of translocations similar to that in the mouse by about 50%. The reduction to 40% of translocation rate after chronic gamma exposure was clearly less than the value of about 80% reported for the mouse over the same range of dose rates. Differential cell killing with ensuing differential elimination of aberration-carrying cells is the most likely explanation for the differences between mouse and monkey.

Animals↗
PubMed1985

Adhesive tapes in the special care baby unit.

Semi-quantitative sampling of 37 taped sites and 37 matching control sites in 30 babies in a special care baby unit showed a tendency for bacterial growth under the cardiac monitors or the occlusive plastic adhesive tape to be greater than at the control site. This tendency was demonstrable even when potential pathogens were considered. During the study, an outbreak due to Candida albicans occurred. Antibiotic resistance of coagulase-negative staphylococci was marked and this, and other evidence, suggested that part of the skin flora was acquired from the unit.

Adhesives↗
PubMed1984

Characters of coagulase-negative staphylococci and micrococci from cases of endocarditis.

Strains of coagulase-negative staphylococci and micrococci submitted to a reference laboratory from 137 cases of endocarditis over a 5 year period were reviewed. Staphylococcus epidermidis biotype 1 (SII) was the commonest biotype in all groups of patients but exceeded 80 per cent in the 61 patients who had undergone prosthetic valve surgery and the 16 patients who had undergone other forms of surgery. Biotype 4 (SVI) was recovered from 10 of the 34 patients without surgery. Strains from prosthetic valve endocarditis were frequently resistant to many antibiotics while strains from natural valve endocarditis were frequently sensitive to all, or resistant only to penicillin. The value of bacteriophage typing was confirmed.

Adult↗
PubMed1984

Cyheptamide and 3-hydroxy-3-phenacyloxindole: structural similarity to diphenylhydantoin as the basis for anticonvulsant activity.

The molecular structures of cyheptamide and 3-hydroxy-3- phenacyloxindole were determined by X-ray diffraction methods. The amide group in both compounds exhibits delocalization of the pi-electrons over the three atoms (N, C, and O), while the bond linking the amide to the tetrahedral carbon atom is a single bond. These structural features are also present in two drugs used for the treatment of generalized tonic-clonic ( GTC ) seizures, namely, carbamazepine and diphenylhydantoin. The shapes of cyheptamide , 3-hydroxy-3- phenacyloxindole , and carbamazepine have three features that are the same and can be simultaneously overlapped, the amide and two hydrophobic regions, whereas diphenylhydantoin fits two of the three regions at one time. These structural and electronic features are analyzed in light of current models for anticonvulsant activity.

Animals↗
PubMed1983

Frequency of resistance to trimethoprim among isolates of Staphylococcus epidermidis and Staphylococcus saprophyticus.

Four hundred and forty-nine strains of staphylococci, 386 Staphylococcus epidermidis and 63 Staph. saprophyticus were tested by MIC and disc for susceptibility to trimethoprim. About 30% of clinically significant strains of Staph. epidermidis were resistant to trimethoprim; this fell to 12.6% in strains from normal flora. The frequency of resistance among clinically significant strains did not alter from 1976 to 1980. Strains of Staph. saprophyticus were uniformly sensitive to trimethoprim.

Culture Media↗
PubMed1982

Changing resistance to antimicrobial drugs, and resistance typing in clinically significant strains of Staphylococcus epidermidis.

Resistance to 11 antimicrobial drugs was assessed in 532 clinically significant strains of Staphylococcus epidermidis received in the years 1978, 1979 and 1980 and compared with that of strains collected in 1976 and 1977 for an international study. Only 14% of strains were sensitive to all the drugs tested. Resistance to gentamicin increased significantly from 7% to 33% during the study period. The degree of association between pairs of drugs was assessed. There was strong association between resistance to methicillin, aminoglycosides and macrolide antibiotics and only weak association between resistance to novobiocin, tetracycline, chloramphenicol and penicillin. Patterns of resistance were complex and may be useful as an accessory typing system.

Aminoglycosides↗
PubMed1982

Evaluation of a micromethod gallery (API Staph) for the identification of staphylococci and micrococci.

A collection of 300 well-characterised strains of staphylococci and micrococci was examined by a commercially available gallery micromethod (API Staph). The results were compared with biotyping by conventional methods. The gallery micromethod broadly agreed with the biotyping scheme used but gave an identification from the index supplied in less than 30% of the trials. Reproducibility was better after 48 h incubation than after 24 h but was poor for the tests for phosphatase and acetoin. When compared with the results of conventional tests, the tests for acetoin, phosphatase and urea were unsatisfactory.

Bacteriological Techniques↗