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Biomedical subjects

D M Bell

Publications and source records attributed to D M Bell.

At least 19 recordsLinked to original sources
PubMed2001

Promoting appropriate antimicrobial drug use: perspective from the Centers for Disease Control and Prevention.

Extending the useful life of antimicrobial drugs through appropriate use-that is, use that maximizes therapeutic impact while minimizing toxicity and the development of resistance-is an important component of efforts to prevent and control the emerging threat of antimicrobial resistance. The major paradigms of antimicrobial drug use involve acute infections in outpatients, acute infections in inpatients, chronic infections, and agriculture/veterinary medicine. The factors that influence drug use and the challenges that need to be addressed in promoting more appropriate use are different in each of these paradigms. For acute respiratory infections in outpatients, data from intervention trials suggest that concurrent multifaceted interventions may be effective in promoting appropriate drug prescribing. The next challenge is to extend these interventions to larger populations by incorporating them into routine medical practice.

Anti-Infective Agents↗
PubMed2001

Markers for progression of coronary disease.

Endothelial cells play numerous physiologic roles including regulation of vascular tone, regulation of hemostasis and fibrinolysis, regulation of inflammatory processes, and maintenance of a permeability barrier to provide for exchange and active transport of substances into the artery wall. Pathophysiologic stimuli can result in localized alterations in endothelial activity. These changes include increased permeability to plasma lipoproteins, imbalances in local thrombogenic substances causing a prothrombotic state, and release of vasoactive compounds resulting in vasoconstriction. Loss of endothelium-dependent vasodilatation is thought to be an early physiologic event in the development of arteriosclerosis, occurring before morphologic changes in the endothelium can be detected. Much of the effects of healthy endothelium appear to be produced by nitric oxide. Decreased bioavailability of nitric oxide results in endothelial dysfunction, which is the first step in the atherosclerotic process. Risk factor modification and pharmacologic interventions that can reverse endothelial dysfunction have the potential to decrease cardiovascular events in patients at risk.

Biomarkers↗
PubMed2000

Myocardial infarction in women: a critical appraisal of gender differences in outcomes.

In every year since 1984, cardiovascular disease has claimed the lives of more women than men. Data from randomized trials indicate that gender contributes to increased mortality after myocardial infarction independent of other risk factors, but additional confounding variables cannot be discounted. Data from registry databases indicate that women are less likely to receive medically proven therapies for myocardial infarction. Women experience more vague symptoms, which may account for underuse of effective therapies. In addition, they may benefit less from thrombolytic therapy than men. Increased use of thrombolytic therapy has resulted in a continued decrease in cardiovascular deaths for men, but not for women. It is unclear if this disparity is a result of inequitable access to therapy or decreased efficacy of these agents in women.

Adrenergic beta-Antagonists↗
PubMed2000

Micro-capillary tube in situ hybridisation: a novel method for processing small individual samples.

We have developed a strategy to individually analyse large numbers of small tissue samples by RNA in situ hybridisation. Samples of approximately 0.4 mm x 0.5 mm are processed in rectangular capillary tubes fitted with nylon mesh and glass beads using standard protocols. Eighteen samples can be assayed simultaneously without loss, and background is low. Specifically, mouse Sox2 RNA expression is examined in the chorion of extraembryonic tissue of 7.5 days post-coitum embryos. This technique works equally well for double RNA labelling and could potentially be used for antibody staining of proteins.

Animals↗
PubMed1999

Analysis of number needed to treat and cost of platelet glycoprotein IIb/IIIa inhibitors in percutaneous coronary interventions and acute coronary syndromes.

This retrospective review and analysis of pivotal clinical trials compared acquisition costs and outcomes of platelet glycoprotein IIb/IIIa inhibitors. Absolute reduction in the number of deaths and nonfatal myocardial infarctions at 30 days, number of patients that need to be treated to prevent one event, and drug costs expended to prevent one event were assessed. In patients undergoing percutaneous coronary intervention (PCI), abciximab is the better value, especially in high-risk patients. In those with unstable angina and non-Q wave myocardial infarction, costs of eptifibatide and tirofiban were not significantly different, but the cost of tirofiban was more variable. These agents have the potential to be cost-effective if administered to populations at high risk for adverse outcomes of acute coronary syndromes or PCI. Prospective methods to identify these high-risk patients are being developed.

Abciximab↗
PubMed1999

Rash in patients receiving ticlopidine after intracoronary stent placement.

As many as half of the approximately 400,000 patients who undergo nonsurgical coronary artery procedures every year receive an intracoronary stent. To prevent thrombus formation within the stent, antiplatelet treatment with ticlopidine and aspirin is administered. Ticlopidine is known to cause cutaneous adverse reactions in up to 5.1% of patients, with a 3.4% discontinuation rate. However, published studies of patients receiving the drug to prevent subacute thrombosis after intracoronary stent placement report a frequency of rash ranging from 0.8-1.6%. We hypothesized that the frequency of rash in this patient population is underreported, and conducted a retrospective chart review, collecting data on frequency and severity of rash, treatment required, patient demographics, and concomitant drugs that may predispose patients to rash. The frequency of rash was approximately 7% in this group of patients.

Aged↗
PubMed1999

Controlled drug misuse by Certified Registered Nurse Anesthetists.

The primary purpose of this study was to determine the prevalence of controlled drug misuse among actively practicing Certified Registered Nurse Anesthetists (CRNAs). A second purpose was to determine variance in controlled drug misuse by the variables of age, sex, population and geographic area of residence, type of anesthesia position currently held, and number of years in anesthesia practice. The research data were obtained through self-administered surveys mailed to 2,500 actively practicing CRNAs throughout the United States. With a response rate of 68.4% (1,709 of 2,500), the survey instrument allowed for stratification according to admitted misuse of controlled drugs commonly used in the clinical practice of anesthesia. The established prevalence of controlled drug misuse in the target population was found to be 9.8% of the sample (167 of 1,709 respondents), with the majority indicating a distinct proclivity for polydrug misuse. The survey results were comparable with those of studies involving anesthesiologists and registered nurses with the notable exception of the preferred drugs for misuse. A strong relationship existed between sex, number of years in clinical anesthesia practice, and the likelihood for controlled drug misuse, thus indicating a potential predictor of which CRNAs may misuse controlled drugs. In addition, a significant relationship existed between recency of controlled drug misuse and drug(s) of choice (P = .05). Recommendations include specific tactics for strengthening drug misuse education and prevention. Also, modifications in research design and additional studies in the research area are suggested.

Adult↗
PubMed1998

Characteristics of West Virginians having myocardial infarction.

BACKGROUND: Prevalence of risk factors in patients having myocardial infarction (MI) have been reported in large US and international studies, but little is known about the prevalence of risk factors in West Virginians having MI. METHODS: Risk factors for MI were identified by ICD-9 codes. Logistic regression analysis was used to compute odds ratios and 95% confidence intervals. RESULTS: In this cohort (n = 727), 72% of men less than 65 years old were current smokers. Women were older and had a lower frequency of smoking and a higher frequency of diabetes mellitus and obesity than men. Women less than 65 years old had significantly more hypertension than men. CONCLUSIONS: In West Virginia, women who have MI are more likely to be nonsmoking diabetics with hypertension.

Adult↗
PubMed1998

Effects of alignment changes on stance phase pressures and shear stresses on transtibial amputees: measurements from 13 transducer sites.

Interface pressures and shear stresses were measured at 13 sites on two unilateral below-knee amputee subjects ambulating with lower-limb patellar-tendon-bearing prostheses. Interface stresses at the time of the first peak in the shank axial force-time curve were investigated at different socket-shank alignment settings. Stress magnitudes ranged from 1.2 to 214.7 kPa for pressure and 0.4 to 79.6 kPa for resultant shear stress, and changes in stress due to misalignment ranged from 1.3 to 80.7 kPa for pressure and from 0.2 to 38.0 kPa for resultant shear stress. For both subjects interface stress changes were much greater in the anterior socket region than in the lateral or posterior regions. Thus, alignment changes had a localized effect on interface stresses. Plots of alignment versus pressure or resultant shear stress were nonlinear for both subjects, in a number of cases maximizing or minimizing at the nominal alignment, indicating complex interface stress-alignment relationships. Variation (standard deviation/mean) was not significantly different for nominal versus misaligned steps, indicating that the subjects adapted well to the alignment changes. Session to session differences in interface stresses were typically larger than interface stress differences induced by alignment modifications. Thus, while these subjects compensated well for alignment changes to maintain consistent interface stresses within a session, they did not do so for different sessions conducted weeks apart.

Adult↗
PubMed1998

Endothelial dysfunction: implications for therapy of cardiovascular diseases.

OBJECTIVE: To review current literature regarding endothelial dysfunction in cardiovascular diseases and examine implications of these findings for the treatment of various cardiovascular disorders. DATA SOURCE: A MEDLINE search of basic science articles pertinent to understanding the role of the endothelium in the atherosclerotic process and of clinical trials examining the presence and treatment of impaired endothelium-dependent vascular relaxation was conducted. STUDY SELECTION: Selected basic science articles and reviews were included to explain the foundation for subsequent clinical trials. All clinical trials examining the treatment of impaired endothelium-dependent vascular relaxation were reviewed. DATA SYNTHESIS: Endothelial dysfunction characterized by impaired endothelium-dependent vascular relaxation is an early physiologic event in atherogenesis. Endothelial dysfunction in peripheral vasculature serves as a marker for impairment in coronary arteries. Techniques for measuring endothelium-dependent vascular relaxation are specific and have a high positive predictive value for coronary artery disease, but low sensitivity. Various pharmacologic agents have been used in an attempt to improve endothelial function, but only lipid-lowering agents and estrogen supplementation have been shown to improve endothelium-dependent vascular relaxation consistently. Treatments used in patients with heart failure or hypertension fail to demonstrate consistent improvement. CONCLUSIONS: Endothelial dysfunction serves as a marker for cardiovascular disease, but pharmacologic treatment does not consistently restore normal endothelial function. Nevertheless, some of these agents are known to have positive clinical outcomes. Future research using these techniques will provide greater insight into the effects of many commonly used therapies for cardiovascular disease on the pathobiology of endothelial dysfunction.

Animals↗
PubMed1998

Anterior cruciate ligament injuries in the skeletally immature patient.

Anterior cruciate ligament injury in the skeletally immature is becoming increasingly recognized and reported. History taking and physical examination based on the principles of ACL injuries in adults, with adjuncts such as arthroscopy and MRI, are effective in diagnosing ACL injury in the young patient. Evaluation of the young patient's true level of skeletal immaturity by comparison with family growth history, examination for signs of sexual maturity, and radiographic evaluation is critical. The risk of physeal damage with surgical treatment is related to the immaturity of the distal femoral and proximal tibial physes. The functional results of nonsurgical treatment of ACL injury, either as an attempt at definitive treatment or as a temporizing plan until skeletal maturity occurs, are poor and the risks of reinjury and further meniscal and cartilage damage are significant. Surgical treatment for primary repair or extra-articular reconstruction alone has not proven to be efficacious. In the adolescent patient who is approaching skeletal maturity, risk of physeal injury is low and intra-articular reconstruction can be performed as in the adult patient. Results with respect to decreased laxity and return to athletic activities mirror those described in adults. In patients with significant growth remaining, however, surgical treatment carries much higher risks of physeal damage and subsequent deformity. Yet, as noted above, intra-articular reconstruction in truly skeletally immature patients using a soft-tissue graft through a transphyseal tibial tunnel of moderate or small diameter and the over-the-top position on the femur has not been shown to cause early physeal closure, limb-length discrepancy, or angular deformity. In humans, the maximum diameter of graft tunnel that will not cause physeal closure has not been determined Animal studies have shown that the tibial physis can be very sensitive to drilling. Therefore it is wise to use moderate tunnel diameters. Bone-patellar tendon-bone grafts have been used with success in patients closer to skeletal maturity. Their use has not been reported in the very skeletally immature knee and cannot be recommended because of the presumed high risk of physeal closure with a bone plug traversing the physis. It is hoped that improved understanding of the ACL injury in the skeletally immature patient will provide treatment options that will restore enduring knee function and prevent early arthrosis.

Adolescent↗
PubMed1997

A case-control study of HIV seroconversion in health care workers after percutaneous exposure. Centers for Disease Control and Prevention Needlestick Surveillance Group.

BACKGROUND: The average risk of human immunodeficiency virus (HIV) infection after percutaneous exposure to HIV-infected blood is 0.3 percent, but the factors that influence this risk are not well understood. METHODS: We conducted a case-control study of health care workers with occupational, percutaneous exposure to HIV-infected blood. The case patients were those who became seropositive after exposure to HIV, as reported by national surveillance systems in France, Italy, the United Kingdom, and the United States. The controls were health care workers in a prospective surveillance project who were exposed to HIV but did not seroconvert. RESULTS: Logistic-regression analysis based on 33 case patients and 665 controls showed that significant risk factors for seroconversion were deep injury (odds ratio= 15; 95 percent confidence interval, 6.0 to 41), injury with a device that was visibly contaminated with the source patient's blood (odds ratio= 6.2; 95 percent confidence interval, 2.2 to 21), a procedure involving a needle placed in the source patient's artery or vein (odds ratio=4.3; 95 percent confidence interval, 1.7 to 12), and exposure to a source patient who died of the acquired immunodeficiency syndrome within two months afterward (odds ratio=5.6; 95 percent confidence interval, 2.0 to 16). The case patients were significantly less likely than the controls to have taken zidovudine after the exposure (odds ratio=0.19; 95 percent confidence interval, 0.06 to 0.52). CONCLUSIONS: The risk of HIV infection after percutaneous exposure increases with a larger volume of blood and, probably, a higher titer of HIV in the source patient's blood. Postexposure prophylaxis with zidovudine appears to be protective.

Analysis of Variance↗
PubMed1997

Occupational risk of human immunodeficiency virus infection in healthcare workers: an overview.

Healthcare workers (HCWs) are at risk for occupational acquisition of human immunodeficiency virus (HIV) infection, primarily due to percutaneous exposure to infected blood. As of June 1996, 51 documented cases and 108 possible cases of occupationally acquired HIV infection in HCWs in the United States had been reported to the Centers for Disease Control and Prevention. The frequency of blood exposure among HCWs varies according to occupation, procedures performed, and use of preventive measures. Based on limited data, it has been estimated that approximately 500,000 percutaneous blood exposures may occur annually among hospital-based HCWs in the United States. Of these, approximately 5,000 may involve exposures to blood that is known to be HIV infected. The average risk of HIV transmission after percutaneous exposure to HIV-infected blood is approximately 0.3%; however, the risk is believed to be higher for exposures involving an increased volume of blood and/or high viral load.

Centers for Disease Control and Prevention, U.S.↗
PubMed1997

SOX9 binds DNA, activates transcription, and coexpresses with type II collagen during chondrogenesis in the mouse.

Two lines of evidence suggest that the Sry-related gene Sox9 is important for chondrogenesis in mammalian embryos. Sox9 mRNA is expressed in chondrogenic condensations in mice, and mutations in human SOX9 are known to cause skeletal dysplasia. We show here that mouse SOX9 protein is able to bind to a SOX/SRY consensus motif in DNA and contains a modular transcriptional activation domain, consistent with a role for SOX9 as a transcription factor acting on genes involved in cartilage development. One such gene is Col2a1, which encodes type II collagen, the major structural component of cartilage. We have compared, in detail, the expression of Sox9 and Col2a1 during mouse development. In chondrogenic tissues the expression profiles of the two genes were remarkably similar. Coexpression was detected in some nonchondrogenic tissues such as the notochord, otic vesicle, and neural tube, but others such as heart and lung differed in their expression of the two genes. Immunohistochemistry using an antibody specific for SOX9 revealed that expression of SOX9 protein mirrored the distribution of Sox9 mRNA. Our results suggest that SOX9 protein is involved in the regulation of Col2a1 during chondrogenesis, but that this regulation is likely to depend on additional cofactors.

Animals↗