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Biomedical subjects

C Dillon

Publications and source records attributed to C Dillon.

29 records · Page 2Linked to original sources
PubMed1978

Influence of R-plasmid RP1 of Pseudomonas aeruginosa on cell wall composition, drug resistance, and sensitivity to cold shock.

R-plasmid RP1 was transferred to Pseudomonas aeruginosa cells, as indicated by their resistance to carbenicillin, ampicillin, cephaloridine, kanamycin, and tetracycline, and by the presence of a periplasmic beta-lactamase. The wild-type cells (RP1-) were lysed by ethylenediaminetetraacetic acid but not by ethylene-glycol-bis(2-aminoethyl ether)-N,N-tetraacetic acid, whereas cells carrying the plasmid (RP1+) were resistant to both these chelating agents. RP1+ and RP1- strains were both sensitive to the lytic action of polymyxin B and the lethal action of cold shock, but the effect was less marked in the RP1+ cultures. A proportion of the RP1+ cells surviving cold shock lost resistance to carbenicillin, tetracycline, and kanamycin. The chemical composition of whole cells and cell walls of RP1+ differed from that RP1- in the content of cation, phospholipid, and markers for lipopolysaccharide and peptidoglycan. Differences in cell wall composition, response to ethylenediaminetetraacetic acid and polymyxin B, and the effects of cold shock are all compatible with the hypothesis that RP1 confers changes in the cell envelope, probably in the outer membrane, of P. aeruginosa.

Ampicillin↗
PubMedDate not supplied

Pericanalicular location of hepatocyte lysosomes and effects of fasting: a morphometric analysis.

Lysosomes constitute a small proportion of hepatocyte volume, but they play a key degradative role, particularly during catabolic states such as nutritional deprivation. Our preliminary observations in hepatocytes suggested that fasting may alter the distribution of lysosomes, which are thought to congregate about the biliary canaliculus. The current study aimed to provide, in both fed and fasted rats, a quantitative morphometric analysis of lysosomes in the immediate pericanalicular and successively more distant regions. We selected three regions of radius 0 to 2 (region 1), 2 to 4 (region 2) and 4 to 6 micron (region 3) about the bile canaliculus and compared lysosomal numerical and volume densities. In fed rats, numerical and volume densities of both primary and secondary lysosomes were 5 to 10 times greater in region 1 than in region 3. After a 72-hr fast, this gradient was lost due largely to a reduced number of primary and secondary lysosomes in region 1. Our calculations suggest that during fasting, lysosomes are redistributed away from the bile canaliculus towards the more distant cytoplasm rather than being lost from the cell, for example, into bile. The number of overt macroautophagic vacuoles was not altered by fasting. We estimate that, in fed rats, there are approximately 270 lysosomes per hepatocyte, and that 43% of lysosomes are contained in the immediate pericanalicular region 1, which comprises only 7 to 8% of the cytoplasmic volume. The reason for this pericanalicular concentration of lysosomes and the mechanism of the redistribution with fasting remain to be determined.

Animals↗
PubMedDate not supplied

Selective attentional biases for physical threat in physical anxiety sensitivity.

Anxiety sensitivity is a trait susceptibility associated with the fear of anxiety-related sensations. One reason why such fears exist may be because those high in anxiety sensitivity selectively attend towards such sensations. However, few studies have actually investigated these cognitive biases in high anxiety sensitive individuals. The current study, therefore, sought to investigate selective attentional biases using the visual dot-probe paradigm. Since recent research suggests that at least one component of anxiety sensitivity is linked to the fear of physical sensations, individual were selected on the basis as to whether they were high or low in their anxious concern for physical sensations. In order to determine whether a general or specific attentional bias exists, the emotionality of material presented to participants was varied in terms of whether it was physically threat-related, socially threat-related, or positive. Consistent with predictions, those high in physical anxiety sensitivity were found to exhibit a selective attentional bias in favour of the location of physically threatening material. Furthermore, those low in anxiety sensitivity were found to avoid such material. Interestingly, a similar attentional bias was not found for either socially threatening or positive material. If anything, those high in physical anxiety sensitivity avoided positive material. These findings are discussed in light of current theories of anxiety sensitivity and future research.

Adolescent↗
PubMedDate not supplied

Clinical and psychological correlates of lumbar motion abnormalities in low back disorders.

BACKGROUND CONTEXT: Low back pain (LBP) and low back disorders (LBDs) identify a complex constellation of conditions that frustrate both diagnosis and therapy. Dynamic quantitative assessment and questionnaire instruments directed toward psychosocial and situational variables provide potentially powerful tools for determining functional pathology and potentially outcome. PURPOSE: Our goal was to independently assess clinical correlates of a trunk motion measurement device, the lumbar motion monitor (LMM). The reliability of the LMM as a clinical test was assessed by comparison with an independent medical examination and biobehavioral questionnaires. STUDY DESIGN/SETTING: There were three study components. A multispecialty physician panel that administered a structured physical examination contributed to a clinical correlation case series study. Standardized outcomes and risk identification questionnaires were administered to the case population. Finally, the LMM was administered in a customary fashion to the same population. PATIENT SAMPLE: Nineteen subjects were recruited on the basis of criteria that included symptoms of chronic recurrent low back pain. This was an employed and active, although impaired, population. Eighteen of the subjects were currently employed with limited lost work time, but chronic and recurrent pain was a common feature. OUTCOME MEASURES: Questionnaire outcome measures were both characterologic and situation based. In addition to providing diagnoses, the physician panel was also asked to offer certain qualitative assessments, such as rehabilitative potential and functional level pertinent to activities of daily living. The impact of LMM measures on physician decision making was also assessed. Trunk angular measurements were used to assess function of patients with chronic low back disorders. METHODS: Kinematic performance on the LMM was expressed as three probability scores. These were the likelihood of abnormality, the "sincerity of effort" (exacerbation or aggravation of impairment), and the likelihood of structural anatomic disease. These variables were examined against established self-report measures of pain and disability. RESULTS: The LMM and physician panels were in agreement on the presence or absence of abnormality. LMM findings tended to be more consistent with clinical history than the clinical examination. The LMM results were also generally consistent with the self-reported measures of pain and disability: a high likelihood of structural disease was associated with depression, somatization, poor health perception and diminished vitality. CONCLUSIONS: The LMM appears to be a useful assessment tool for gauging the presence of LBP and LBD. It was accurate in detecting abnormality when abnormality was determined by clinical history and physician diagnosis. The LMM's differentiation of mechanical low back disease (nonanatomically specific disorders) from structurally specific low back disease was not consistent with a parallel clinical differentiation. Larger trials in a prospective format and studies on a chronically disabled population seem warranted. In an impaired but less disabled population, elevated pain and somatization did not appear to weaken the effort during testing.

Adult↗
PubMedDate not supplied

The economic and social consequences of work-related musculoskeletal disorders: the Connecticut Upper-Extremity Surveillance Project (CUSP).

A population-based telephone survey was conducted in Connecticut to determine the social and economic impact of work-related musculoskeletal disorders (WRMSDs). Only 10.6% of cases had filed for workers' compensation. Respondents had spent an average of $489 annually out-of-pocket. Only 21% of individuals who had had medical visits or procedures reported having them paid for by workers' compensation. The WRMSD cases reported much higher levels of difficulty in daily tasks rated by the activities of daily living (ADL) scale, with odds ratios (ORs) ranging from 8.2 (child care) to 35.2 (bathing). The cases were significantly more likely to have moved for financial reasons (OR = 2.41), including having lost a home (OR = 3.44). The cases were also significantly more likely to have lost a car due to finances (OR = 2.45), more likely to have been divorced (OR = 1.91), and less likely to have been promoted (OR = 0.45). The study supports significant externalization of costs for WRMSD out of the workers' compensation system and a substantial social and economic impact on workers.

Activities of Daily Living↗