Search PubMed⌕ Search

Biomedical subjects

M Davis

Publications and source records attributed to M Davis.

At least 73 records · Page 4Linked to original sources
PubMed2000

Bypass surgery for chronic lower limb ischaemia.

BACKGROUND: Surgical bypass of an occluded arterial segment is the mainstay of treatment for patients with critical limb ischaemia. As with many surgical interventions, however, it was introduced without formal evaluation. OBJECTIVES: The objective of this review was to determine the effects of bypass surgery in patients with chronic lower limb ischaemia. SEARCH STRATEGY: The reviewers searched the Cochrane Peripheral Vascular Diseases Group trials register, MEDLINE, EMBASE, reference lists of relevant articles, and contacted principal trial investigators. SELECTION CRITERIA: All randomised controlled trials of bypass surgery versus control, or versus any other form of treatment. DATA COLLECTION AND ANALYSIS: At least two reviewers extracted data and assessed trial quality independently. The reviewers contacted investigators to obtain information or data needed for the review that could not be found in published reports. Dichotomous data were analysed using the Peto odds ratio (OR), and continuous data with the weighted mean difference (fixed effect and random effects models). MAIN RESULTS: Eight trials were identified which appeared to meet the inclusion criteria, but two were subsequently excluded. The remaining six trials involved a total of just over 700 patients, two trials comparing bypass surgery with angioplasty (PTA), and one with each of thromboendarterectomy, thrombolysis, exercise, and spinal cord stimulation. Four trials included patients with a range of disease severity (intermittent claudication and critical limb ischaemia), one was restricted to claudicants only and another to only critical limb ischaemia. The type of bypass procedure performed in each trial was similar: vein grafts for distal reconstructions; synthetic prostheses for aorto-iliac or ilio-femoral bypasses. The outcome measures varied, but four of the six trials included mortality and operative failure. In general the quality of the trials was good, but none was blinded because of the nature of the intervention. There were no clear differences between bypass surgery and PTA. Mortality and amputation rates did not differ significantly, although primary patency was significantly higher in the bypass group after 12 months (Peto OR 1. 6, 95% CI 1.0, 2.6) but not after four years (p=0.14). Compared with thrombolysis, amputation rates were significantly lower in the bypass group (Peto OR 0.2, 95% CI 0.1, 0.6), but mortality rates did not differ. Compared with thromboendarterectomy, restoration of blood flow was significantly greater in the bypass patients (Peto OR 9.2, 95% CI 1.7, 50.6), but mortality and amputation rates did not differ. Bypass did not differ significantly from exercise or spinal cord stimulation. REVIEWER'S CONCLUSIONS: There is limited evidence for the effectiveness of bypass surgery and further large trials are required.

Angioplasty, Balloon↗
PubMed2000

The role of proteolytic enzymes in focal ischaemic brain damage.

Although various neuroprotective and fibrinolytic drugs are currently under evaluation in the acute stages of ischaemic stroke, their therapeutic potential is likely to be limited by unwanted side effects and a narrow time window of opportunity for intervention. Proteolytic enzymes are involved in the catabolism of peptide neurotransmitters and structural cellular proteins in normal brain and have been implicated in the pathogenesis of neurodegenerative disorders. We hypothesised that activation of these enzymes might also play a crucial role in effecting ischaemic neuronal injury, thereby providing a potential site for therapeutic intervention in human stroke. Focal cerebral ischaemia was induced by thermocoagulation of the left middle cerebral artery in aged (30 month) male Wistar rats who were pre-treated with saline or the competitive N-methyl-D-Aspartate antagonist D-CPP-ene, which has been shown to be neuroprotective in young animal models of stroke. Major protease activities were analysed in the left (ischaemic) and right (non-ischaemic) hemispheres, following tissue homogenisation. Data have been analysed using Mann-Whitney tests and are presented as means +/- standard errors. Enzyme activity decreased in ischaemic brain; for example, the mean activity of dipeptidyl aminopeptidase I was 23 +/- 3 and 43 +/- 6 nmol substrate/hour/ml brain extract in the left and right hemispheres respectively (n = 10, p < 0.05). Ischaemic neuronal injury is not effected by the early activation of proteolytic enzymes and protease inhibitors are therefore unlikely to be of benefit in human stroke.

Animals↗
PubMed2000

Synergistic enhancement of the acoustic startle reflex by dopamine D1 and 5-HT1A agonists and corresponding changes in c-Fos expression in the dorsal raphe of rats.

RATIONALE AND OBJECTIVES: Several studies have reported an increase in dopamine (DA)-stimulated behavioral responses after manipulations that reduce brain serotonin (5-hydroxytryptamine, 5-HT) levels. Because others have shown that systemic administration of the 5-HT1A agonist 8-hydroxy-2-(di-n-propylamino)-tetralin (8-OH-DPAT) reduces 5-HT levels throughout the brain, we tested the effects of 8-OH-DPAT on the enhancement of the acoustic startle reflex by the dopamine D1 receptor agonist SKF 82958. In addition, we used the expression of the c-Fos protein as a marker of neuronal activity to assess any corresponding drug-induced changes within the dorsal raphe (DR). METHODS AND RESULTS: Male Sprague-Dawley rats pretreated (10 min) with 8-OH-DPAT (0.5 mg/kg) showed a marked potentiation of the enhancement of startle by SKF 82958 (0.1 mg/kg). Furthermore, SKF 82958 produced a dramatic induction of c-Fos in the DR, an effect that was blocked by 8-OH-DPAT. Double-labeling immunohistochemistry for c-Fos and 5-HT showed that SKF 82958-induced expression of c-Fos, and its blockade by 8-OH-DPAT, occurred in a percentage of 5-HT-containing cells of the DR. CONCLUSIONS: These data suggest the possibility that inhibition of the DR by 8-OH-DPAT mediates the potentiation of startle by SKF 82958, perhaps through a reduction in 5-HT release in the striatum. Such an interpretation is consistent with the hypothesis of an inhibitory role of the 5-HT system on DA-mediated behaviors.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed2000

Development of a modified picture-sort food frequency questionnaire administered to low-income, overweight, African-American adolescent girls.

There is essentially no ideal method of dietary assessment. Physiologic methods (i.e., doubly labeled water) probably come closest, but high cost, participant burden, and limited information limit their use. Furthermore, most dietary assessment methods have been designed for and tested in white adults. Very few have been designed for and tested in African-American adolescents. This study examined validity and reliability of a modified picture-sort food frequency questionnaire (FFQ) administered to 22 low-income, overweight, African-American adolescent girls, aged 11 to 17 years. The FFQ was administered to subjects twice during a 2-week period, and evaluated using the mean values of three 24-hour recalls. The natural log-transformed energy-adjusted, deattenuated correlation coefficients between the second FFQ and the mean from 3 recalls exceeded 0.50 for most nutrients, ranging from 0.32 (protein) to 0.87 (saturated fat). The energy and nutrient values from the first FFQ were greater than those from the second FFQ. Most correlation coefficients for the test-retest reliability of the FFQ were not significant. We conclude that although larger samples are needed to generalize results, the picture-sort dietary assessment method appears to be promising and merits further research.

Adolescent↗
PubMed2000

Hemispheric specialization in spontaneous gesticulation in a patient with callosal disconnection.

This is an investigation of spontaneous gesticulation in a left-handed patient with a callosal disconnection syndrome due to infarction of the total length of the corpus callosum. After callosal infarction, the patient gesticulated predominantly unilaterally with the left hand despite left apraxia. Bilateral gesticulation occurred later on and was presumably achieved by an increase in ipsilateral proximal control. Movement analysis further indicated that the two hemispheres are specialized for certain gesture types. Gestures with emotional connotation and batons (emphasizing prosody) were generated predominantly in the right hemisphere whereas physiographics which picture the linguistic content concretely and deictics (pointing) were of left-hemispheric origin.

Apraxias↗
PubMed2000

Fear and anxiety: animal models and human cognitive psychophysiology.

The aim of this paper is to explicate what is special about emotional information processing, emphasizing the neural foundations that underlie the experience and expression of fear. A functional, anatomical model of defense behavior in animals is presented and applications are described in cognitive and physiological studies of human affect. It is proposed that unpleasant emotions depend on the activation of an evolutionarily primitive subcortical circuit, including the amygdala and the neural structures to which it projects. This motivational system mediates specific autonomic (e.g., heart rate change) and somatic reflexes (e.g., startle change) that originally promoted survival in dangerous conditions. These same response patterns are illustrated in humans, as they process objective, memorial, and media stimuli. Furthermore, it is shown how variations in the neural circuit and its outputs may separately characterize cue-specific fear (as in specific phobia) and more generalized anxiety. Finally, again emphasizing links between the animal and human data, we focus on special, attentional features of emotional processing: The automaticity of fear reactions, hyper-reactivity to minimal threat-cues, and evidence that the physiological responses in fear may be independent of slower, language-based appraisal processes.

Animals↗
PubMed2000

Trigeminal neuralgia: opportunities for research and treatment.

Trigeminal neuralgia was the focus of a recent workshop convened by the National Institute of Neurological Disorders and Stroke (NINDS) and the National Institute of Dental and Craniofacial Research (NIDCR). The workshop brought together basic scientists, clinicians, epidemiologists, and patient advocates. New research directions for epidemiology, diagnosis and assessment, pain mechanisms, and treatment were identified. (The workshop was held in Rockville MD on September 14, 1999, with financial support from NINDS, NIDCR, the NIH Office of Rare Diseases, and the NIH Pain Research Consortium.)

Animals↗
PubMed2000

Disruption of contextual freezing, but not contextual blocking of fear-potentiated startle, after lesions of the dorsal hippocampus.

The role of the dorsal hippocampus in contextual fear conditioning was investigated with a contextual blocking paradigm. In Experiment 1, rats were given pairings of a light conditioned stimulus (CS) and footshock after preexposure either to footshock or to the context alone. The group preexposed to footshock showed poorer fear conditioning to the light CS, as measured by the fear-potentiated startle reflex. In Experiment 2, a group preexposed to footshock in the same context showed poorer fear conditioning to the light CS than did a group preexposed to footshock in a different context, indicating contextual blocking of fear-potentiated startle. In Experiment 3, lesions of the dorsal hippocampus had no effect on contextual blocking, even though contextual freezing was disrupted. The sparing of contextual blocking indicated that contextual memory was intact following hippocampal lesions, despite the disruption of contextual freezing.

Animals↗
PubMed2000

Dietary change through African American churches: baseline results and program description of the eat for life trial.

BACKGROUND: Eat for Life, a multicomponent intervention to increase fruit and vegetable (F & V) consumption among African Americans, is delivered through African American churches. METHODS: Fourteen churches were randomly assigned to one of three treatment conditions: 1) comparison; 2) culturally-sensitive multicomponent intervention with one phone call; and 3) culturally-sensitive multicomponent intervention with four phone calls. The intervention included an 18-minute video, a project cookbook, printed health education materials, and several "cues" imprinted with the project logo and a 5 A Day message. A key element of the telephone intervention was the use of motivational interviewing, a counseling technique originally developed for addictive behaviors. Major outcomes for the trial included total F & V intake, assessed by food-frequency questionnaires (FFQs) and 24-hour recalls, and serum carotenoids. Psychosocial variables assessed included outcome expectations, barriers to F & V intake, preference for meat meals, neophobia, social support to eat more F & V, self-efficacy to eat more F & V, and nutrition knowledge. RESULTS: Baseline mean F & V intakes across the three FFQs ranged from 3.45 to 4.28 servings per day. Intake based on a single 24-hour recall was 3.0 servings. Variables positively correlated with F & V intake included self-efficacy, outcome expectations, and a belief that F & V contain vitamins. Factors negatively correlated with intake include perceived barriers, meat preference, neophobia, and high-fat cooking practices. The completion rate for the first telephone counseling call was 90%. Completion rates for the remaining three calls ranged from 79% to 86%. CONCLUSION: The recruitment and intervention methods of the Eat for Life study appear promising. The telephone intervention based on motivational interviewing is potentially useful for delivering dietary counseling.

Adult↗
PubMed2000

Efficient export of the vesicular stomatitis virus G protein from the endoplasmic reticulum requires a signal in the cytoplasmic tail that includes both tyrosine-based and di-acidic motifs.

The vesicular stomatitis virus (VSV) G protein is a model transmembrane glycoprotein that has been extensively used to study the exocytotic pathway. A signal in the cytoplasmic tail of VSV G (DxE or Asp-x-Glu, where x is any amino acid) was recently proposed to mediate efficient export of the protein from the endoplasmic reticulum (ER). In this study, we show that the DxE motif only partially accounts for efficient ER exit of VSV G. We have identified a six-amino-acid signal, which includes the previously identified Asp and Glu residues, that is required for efficient exit of VSV G from the ER. This six-residue signal also includes the targeting sequence YxxO (where x is any amino acid and O is a bulky, hydrophobic residue) implicated in several different sorting pathways. The only defect in VSV G proteins with mutations in the six-residue signal is slow exit from the ER; folding and oligomerization in the ER are normal, and the mutants eventually reach the plasma membrane. Addition of this six-residue motif to an inefficiently transported reporter protein is sufficient to confer an enhanced ER export rate. The signal we have identified is highly conserved among divergent VSV G proteins, and we suggest this reflects the importance of this motif in the evolution of VSV G as a proficient exocytic protein.

Amino Acid Sequence↗
PubMed2000

Anger and cancer: an analysis of the linkages.

The purposes of this article are to review literature on anger's link to cancer, to analyze the state of the science in this area, and to propose some directions for future research. Extremely low anger scores have been noted in numerous studies of patients with cancer. Such low scores suggest suppression, repression, or restraint of anger. There is evidence to show that suppressed anger can be a precursor to the development of cancer, and also a factor in its progression after diagnosis. Some studies indicate that it may be beneficial for patients to mobilize anger to battle their cancer. However, there is a paucity of research on the outcomes of various anger interventions. Longitudinal studies that repeatedly measure anger and other moods over the disease trajectory are needed.

Adaptation, Psychological↗
PubMed2000

Proposed curriculum for an "observational" international emergency medicine fellowship program.

This article presents information on considerations involved in setting up and conducting fellowship training programs in emergency medicine (EM) for physicians from other countries. General goals for these programs are to assist in providing physicians from other countries with the knowledge and skills needed to further develop EM in their home countries. The authors report their opinions, based on their cumulative extensive experiences, on the necessary and optional structural elements to consider for international EM fellowship programs. Because of U.S. medical licensing restrictions, much of the proposed programs' content would be "observational" rather than involving direct "hands-on" clinical EM training. Due to the very recent initiation of these programs in the United States, there has not yet been reported any scientific evaluation of their structure or efficacy. International EM fellowship programs involving mainly observational EM experience can serve as one method to assist in EM development in other countries. Future studies should assess the impact and efficacy of these programs.

Curriculum↗
PubMed2000

Ruminant gastrointestinal cell proliferation and clearance of Escherichia coli O157:H7.

Human infections with Escherichia coli O157:H7 cause hemorrhagic colitis that can progress to a life-threatening sequelae. The most common mode of disease transmission is ingestion of contaminated bovine food products, and it is well established that E. coli O157:H7 is a transient member of the bovine microbiota. However, the conditions that induce acquisition and subsequent clearance of this bacterium from the ruminant gastrointestinal tract (GIT) are not understood. Evidence that the rates of epithelial cell proliferation in the lower GIT of cattle are associated with the duration animals remained E. coli O157:H7 culture positive is presented. Cattle with slower rates of intestinal cell proliferation in the cecum and the distal colon were culture positive significantly longer than cohort cattle with faster cell proliferation rates. Cell death rates (apoptotic indices) between the short- and long-term culture-positive animals were not different. Typical grain-based finishing diets and forage-based growing diets did not effect GIT cell proliferation or the duration animals remained E. coli O157:H7 culture positive. To identify a dietary intervention that would effect GIT cell proliferation, we used sheep as a model ruminant. A fasting-refeeding regime that increased the rate of GIT cell proliferation was developed. The fasting-refeeding protocol was used in cattle to test the hypothesis that feeding interventions that increase the rate of GIT cell proliferation induce the clearance of E. coli O157:H7 from the bovine GIT.

Animal Feed↗
PubMed2000

Gimme 5 fruit, juice, and vegetables for fun and health: outcome evaluation.

A theory-based multicomponent intervention (Gimme 5) was designed and implemented to impact fourth- and fifth-grade children's fruit, juice, and vegetable (FJV) consumption and related psychosocial variables. Gimme 5 was a randomized controlled intervention trial with school (n = 16 elementary) as unit of random assignment and analysis. Participants included the cohort of students who were in the third grade in the winter of 1994 and students who joined them in the fourth and fifth grades. The intervention included a curriculum, newsletters, videotapes, and point-of-purchase education. Evaluation included 7-day food records and psychosocial measures from students, telephone interviews with parents, and observational assessments. Favorable results were observed for consumption of FJV combined, FJV consumed at weekday lunch, eating FJV self-efficacy, social norms, asking behaviors, and knowledge. A theory-based school nutrition education program can help change children's FJV consumption and impact factors at home that predispose to FJV consumption, but changes were small, and their persistence is unknown.

Child↗