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Biomedical subjects

T Bruce

Publications and source records attributed to T Bruce.

At least 19 recordsLinked to original sources
PubMed2001

Recent advances in the chemistry of spinosyns.

The spinosyns are a new class of fermentation-derived insect control agents that are effective against a variety of chewing insect pests. The successful introduction of spinosad into the agricultural marketplace represents an important milestone in the use of natural products for commercial pest control. The development of a natural product presents additional limitations relative to a synthetic material. While the latter affords some degree of control in building appropriate physical attributes such as photostability, a natural product, designed to function in a different environment, is often less suited for traditional spray applications. Despite its intrinsic photolability, spinosad is stable enough to perform under field conditions. In an effort to generate analogs with improved physical characteristics, we have developed a variety of conditions for selectively modifying different portions of the molecule, and we have discovered analogs with greater activity against a broader spectrum of pests. The inability to translate improved greenhouse activity to actual field conditions resulted in a detailed study of the effects of formulations and crystallinity on biological activity. Through this effort, measurably improved field performance of synthetic spinosyn analogs relative to the natural product have now been observed.

Animals↗
PubMed1999

Further analysis of the separate and interactive effects of methylphenidate and common classroom contingencies.

We evaluated separate and interactive effects between common classroom contingencies and methylphenidate (MPH) on disruptive and off-task behaviors for 4 children with a diagnosis of attention deficit hyperactivity disorder. Analogue conditions consisting of contingent teacher reprimands, brief time-out, no interaction, and alone were conducted in a multielement design. Medication status (MPH or placebo) was alternated across days in a superordinate multielement design. Results indicate that (a) the behavioral effects of MPH were influenced by one or more of the analogue conditions for each participant, and (b) time-out was associated with zero or near-zero levels of both disruptive and off-task behavior for 3 of the 4 participants during MPH and placebo conditions. Implications for the clinical effectiveness of MPH and possible behavioral mechanisms of action of MPH in applied settings are discussed.

Achievement↗
PubMed1998

Labour-saving strategies to maintain survey response rates: a randomised trial.

To evaluate response-aiding strategies feasible in large surveys, we randomly allocated general practitioners (GPs) to one of four intervention groups: Group 1 received 'exhaustive' telephone prompts by a medical peer in advance of a questionnaire; Group 2, inclusion of an embossed pen with the questionnaire; Group 3, an advance letter prompt; and Group 4, a 'single attempt' advance telephone prompt by a non-medical research assistant. Follow-up procedures were identical. Response rates by group were not significantly different overall (chi 2 = 4.59, df = 3, p = 0.20) although advance prompts by a medical peer were significantly more effective than other strategies for male GPs. The difference in overall response rates between males (63%) and females (74%) was significant (chi 2 = 15.40, df = 1, p < 0.01). No other response bias was evident. Our demonstration of a significant interaction between respondent sex and response-aiding strategy invites further research.

Adult↗
PubMed1989

Silent ischemia: evaluation by exercise and redistribution tomographic thallium-201 myocardial imaging.

UNLABELLED: To compare the amount of myocardium jeopardized during silent ischemia and painful ischemia, 112 consecutive patients undergoing coronary arteriography with ischemia demonstrated by exercise and redistribution tomographic thallium-201 myocardial imaging (SPECT) were divided into two groups: 84 patients without anginal pain (silent ischemia) and 28 with pain (painful ischemia). The SPECT apical, mid and basal ventricular levels of the short-axis view and the apical portion of the long-axis view were divided into 20 segments. The results were 1) 7.4 +/- 4.7 ischemic segments in silent ischemia and 7.6 +/- 3.7 in painful ischemia (p = NS) with 4.7 +/- 3.6 segments in silent ischemia undergoing total redistribution compared with 5.4 +/- 3.4 in painful ischemia (p = NS); 2) no difference in the incidence of single, double or triple vessel disease between silent and painful ischemic groups; 3) similar anatomic distribution of ischemic segments between the two groups; 4) more positive exercise electrocardiographic (ECG) changes in painful ischemia (70%) than in silent ischemia (32%) (p less than 0.001) with equal amounts of ischemia associated with positive and negative exercise ECG findings. CONCLUSIONS: 1) Patients with silent and painful ischemia during exercise have similar amounts of ischemic myocardium demonstrated by tomographic thallium-201 imaging and similar extent of angiographically documented coronary artery disease despite the absence of pain and the lower incidence of positive exercise ECG findings in silent ischemia. 2) Positive and negative exercise ECG findings were associated with similar amounts of ischemic myocardium.

Angina Pectoris↗
PubMed1986

Emotional sequelae of chronic inflammatory bowel disease in children and adolescents.

It is clear that further study needs to be made of the link between emotional disorder and chronic inflammatory bowel disease in children. It is commonly accepted that such a link exists in ulcerative colitis and although there is at present no proof in either direction it seems highly probable that such a relationship is also present in Crohn's disease. We have seen that the families of children with Crohn's disease appear to find it much more than ordinarily difficult to accept such a relationship, but an objective study is projected to explore the presence of psychiatric illness in our patients and their families. Such a study will be extremely time consuming, requiring the services of a part-time research worker, and the exigencies of clinical service have so far prevented its being set in motion. We feel that our experience in St Bartholomew's Hospital during the past seven years has very clearly demonstrated the value of close liaison between the Child Psychiatry Unit and the Paediatric Inflammatory Bowel Disease Clinic, and the much greater efficacy of such a liaison as against referrals made to a separate Psychiatric Unit. It should be emphasized, however, that a liaison of this sort is time consuming, and in our experience has involved child psychiatrists, social workers, child psychotherapists and behaviour therapists. Thus the provision of such a service is expensive both in time and money. Where a new Paediatric Inflammatory Bowel Disease Clinic is being projected there must be very careful forward planning, looking particularly at financial implications if a psychiatric liaison team is to be included.

Adolescent↗
PubMed1984

Epidemiological investigation of exfoliative toxin-producing Staphylococcus aureus strains in hospitalized patients.

The incidence of exfoliative toxin-producing strains of Staphylococcus aureus was studied. Samples from hospitalized patients of all ages and samples from infants less than 6 weeks old were screened; out of 2,632 coagulase-positive S. aureus strains tested, 6.2% synthesized exfoliative toxin. The clinical features could be assessed in 86 patients harboring exfoliative toxin-producing staphylococci. Skin lesions (pustules, blisters, and bullous impetigo) could be observed only when the exfoliative toxin-positive strains were isolated from the skin. Phage nongroup II strains seemed less skin pathogenic than phage group II strains. Outbreaks and sporadic cases were observed.

Animals↗
PubMed1980

The isolation and characterization of a sequence-specific endonuclease from Anabaena subcylindrica.

An endonuclease, AsuI, was isolated from extracts of Anabaena subcylindrica on the basis of gel-electrophoretic analysis of digests of bacteriophage-lambda DNA with the paritally purified extracts. The enzyme requires Mg2+, but no other cofactors. Endonuclease AsuI recognizes the interrupted tetranucleotide sequence: (Formula: see tex), and breaks the phosphodiester bonds indicated by the arrows to leave single-stranded trinucleotide projections at the 5'-termini of the DNA fragments.

Bacteriophage lambda↗
PubMed1976

Squamous epithelial cancer in metaplastic pleura following extrapleural pneumothorax for pulmonary tuberculosis.

During the period 1947-1955, 148 patients underwent extrapleural pneumolysis for pulmonary tuberculosis in Stockholm City Chest Hospital at Söderby. In 121 tuberculosis healed following operation. Ten of these later developed pain and a feeling of tension on the operated side and were operated upon with evacuation of the extrapleural sac. In four of them a highly differentiated keratinizing aquamous cell carcinoma had developed. In addition, two more cases of carinomas of the same type operated on at other hospitals are described. Five of the six patients died of cancer. Squamous cell carcinoma occurring in metaplastic mesothelial cells has hitherto not been reported on and the phenomenon is discussed and compared with the more common scar cancers within lung tissue caused by damage from tuberculosis.

Adult↗