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Biomedical subjects

B Marshall

Publications and source records attributed to B Marshall.

At least 109 records · Page 6Linked to original sources
PubMed1982

A reassessment of the mechanism of action of 4'-[(9-acridinyl)-amino]methanesulphon-m-anisidide.

The conclusion that treating cells with 4'-[(9-acridinyl)- amino]methanesulphon-m-anisidide (mAMSA) causes an alkali-dependent decrease in the size of their DNA was reinvestigated. Evidence is presented that alkali is not needed to detect an effect of mAMSA on the sedimentation rate of DNA released from mAMSA-treated PY815 cells and that mAMSA causes double-strand breaks in cellular DNA.

Aminoacridines↗
PubMed1981

Epidemic measles in Shetland during 1977 and 1978.

During 1977 and 1978 an unusual epidemic of measles occurred in Shetland, affecting 1032 (5%) of the population. All age groups were represented, and 309 cases occurred in people over 15. Geographical distribution of notified cases ranged from 1% to over one-third of the population aged under 65. All the recognised complications occurred, with a significant excess of respiratory troubles (p less than 0 . 05). Complications were much less common in female patients (p less than 0 . 05). Only about 30% of children under 5 had been vaccinated against the disease, and, based on a sample population, vaccination was found to have had a protective effect of 92%. On cost effectiveness alone, uptake of vaccination by a community as susceptible as that of Shetland should clearly be encouraged and probably given high priority.

Adolescent↗
PubMed1981

Competition between congenic Escherichia coli K-12 strains in vivo.

The ability of Escherichia coli to colonize the large bowels of animals is related to many factors inherent to the intestinal environment and the bacterium. The use of germfree mice eliminates the competition between E. coli and the other microflora and allows most E. coli strains to colonize. We found that E. coli K-12 strains differing in chromosomal antibiotic resistance could monoassociate in germfree mice in large numbers. However, when two or more strains were in competition with each other, we detected quantitative differences in the abilities of the strains to colonize. The order of colonizing ability was as follows: nalidixic acid resistance greater than streptomycin resistance greater than rifampin resistance. We also found that a nalidixic acid-resistant strain bearing plasmid pBR322 colonized less efficiently and at lower levels when in competition with the nalidixic acid-resistant strain. Studies of the membrane proteins of the various strains indicated that changes in membrane proteins occurred concomitantly with altered resistance to antimicrobial agents. These results suggest that chromosomally linked alterations in antimicrobial sensitivity may also reflect changes in membrane proteins and a decreased ability to colonize mammalian intestines in otherwise isogenic bacterial strains.

Animals↗
PubMed1981

Risk assessment studies of E. coli host-vector systems.

These studies have demonstrated the poor survival of E. coli K-12 in the human and mouse gut and the absence of detectable transfer of pBR322 to endogenous intestinal flora. Even in the presence of mobilizing plasmids, no mobilization of pBR322 was detected, and transfer of the transferable plasmids was greatly reduced in the gut. Colonization of the mouse intestine by E. coli was shown to be affected by spontaneous chromosomal mutations to Sm or Rif resistance; these derivatives were weak competitors for colonization in the presence of the original E. coli K-12 organism. Moreover, E. coli K-12 appeared to be at a selective disadvantage in the human and mouse gut since even antibiotic selection failed to increase its survival. A background of data has been accumulated on the frequency of lambda, and M13 phages, and amber-suppressible bacteria in natural human and animal populations. These data should be useful to present and future risk-assessment evaluations. The frequency of antibiotic resistant coliforms in fecal samples from different human and animal populations was found to high. In the present study, antibiotic resistance was very common in both hospitalized and non-hospitalized populations. The percentage of resistant coliforms within individual specimens, however, was higher in patient population.

Animals↗
PubMed1980

Survival of Escherichia coli host-vector systems in the mammalian intestine.

Survival in the mouse and human intestine of Escherichia coli host-vector systems used and proposed for recombinant DNA technology was assessed. There was no detectable survival of severely disabled E. coli K12 strain X1776 in mice or in human subjects 24 hours after ingestion. The same strain bearing the plasmid pBR322, however, was recovered from human subjects for 4 days in amounts of six organisms for every million ingested. Nondisabled E. coli K12 strain X1666, with or without pBR322, survived in 10(4)-fold greater numbers and for 2 days longer, with better recovery of the plasmid-containing derivative. Although the plasmid-bearing strains were recovered for longer periods, no intestinal colonization was noted. Despite the presence of pBR322 for a maximum of 6 days in the human intestine, there was no evidence that it was transferred from either bacterial host to endogenous aerobic fecal bacteria.

Animals↗
PubMed1980

Recovery frequency of phages lambda and M13 from human and animal faeces.

Derivatives of bacteriophages lambda and M13 are in common use as vectors in recombinant DNA RESEARCH. These laboratory-derived phages have been designed to allow cloning of DNA fragments, but to be unable to survive outside a defined laboratory and/or host-cell environment. To assess the availability of wild-type lambda or M13 phages in the environment which might potentially rescue debilitated derivative phages, we have now examined the frequency of these and other bacteriophages in human and animal faeces. We detected coliphage in over two-thirds of the faecal samples. Of these, 1.2% of the samples contained lambda-like phage and 3.5% had phage indistinguishable from M13.

Animals↗
PubMed1978

Social interactions and communication patterns in mentally retarded children.

An observational approach and videorecordings were used to investigate a group of four mentally retarded kindergarten children with minimal language development. Results showed that when a facilitator (teacher) was present, there were more social interactions and vocalizations, but there was no significant increase in meaningful verbal content. Nonverbal communication rose sharply in the presence of the facilitator. The findings indicate that an observational analysis of patterns of interaction is useful in planning intervention programs in the area of social and communication development.

Aggression↗
PubMedDate not supplied

Blood loss estimation by out-of-hospital emergency care providers.

OBJECTIVES: To evaluate emergency medical technicians' (EMTs') ability to estimate spilled blood volume and to determine whether limited training improves estimate accuracy and whether there is a difference in improvement comparing two different training methods. METHODS: The study design was a single-blinded, clinical model, utilizing EMTs (basic, intermediate, and advanced) from a local commercial ambulance service. Participants estimated the volume of randomly selected volumes of packed red blood cells reconstituted to a normal hematocrit and poured onto three absorbent (carpet) and three nonabsorbent (vinyl) surfaces. Participants were then randomly assigned to one of two teaching groups. The SITEGRP (n = 17) returned to the six testing sites and were told the actual blood volumes. The SLIDE-GRP (n = 16) were taught with slides of six similar blood spill sites. Both groups were provided with suggestions for making volume estimates. The same participants were then retested one month later using the same type of sites and six new blood volumes. RESULTS: Thirty-three participants with an average of 7.5 years of prehospital care experience completed testing on both dates. Mean percent error {[(estimated volume - actual volume)/actual volume] x 100} for all participants decreased from 65%+/-33% initially to 52%+/-20% after retesting (p < 0.05). Mean percent error was 74%+/-41% and 59%+/-20% for the SITEGRP (p < 0.15) initially and after retesting, respectively. Mean percent error was 56%+/-17% and 45%+/-17% for the SLIDEGRP (p < 0.05) initially and after retesting, respectively. CONCLUSION: Prehospital care providers are not accurate at estimating spilled blood volumes. This ability can be improved with limited education. Slides appear to be as effective as viewing actual spill sites.

Clinical Competence↗