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Biomedical subjects

M Andrews

Publications and source records attributed to M Andrews.

At least 37 records · Page 2Linked to original sources
PubMed1999

The GABA(B) agonist CGP 44532 decreases cocaine self-administration in rats: demonstration using a progressive ratio and a discrete trials procedure.

Previous self-administration experiments have shown that baclofen, the prototypical GABA(B) agonist, produces an apparent attenuation in the reinforcing effects of cocaine in rats. The present experiments examined the effects of CPG 44532, a novel and highly specific GABA(B) agonist, on cocaine self-administration using two distinctly different procedures. CGP 44532 (0.063-0.5 mg/kg) produced a dose dependent decrease in break point on a progressive-ratio (PR) schedule. A low dose of CGP 44532 (0.125 mg/kg) produced an apparent shift of the cocaine dose-response curve to the right. In contrast there was comparatively little effect on food-reinforced responding on the same PR schedule. Using a discrete-trials procedure that engendered a circadian pattern of self-administration, CPG 44532 (0.063-0.5 mg/kg) produced a dose-dependent suppression of cocaine intake in the 4 h period following treatment. When a concurrently available food reinforced lever was added to the discrete trials paradigm CGP 44532 failed to disrupt responding for food at any of the doses tested. Data from the PR and discrete-trials procedures taken together indicate that CGP 44532 produced a specific decrease in the motivation to self-administer cocaine.

Animals↗
PubMed1999

Revision hip surgery in the elderly: is it worthwhile?

We prospectively analyzed the outcome in 103 consecutive patients undergoing revision hip replacement, dividing the patients into 2 groups according to their age at the time of surgery. There were 45 patients aged 75 years or older and 58 patients aged younger than 75 years. The results of revision hip replacement in terms of pain relief, functional improvement, and patient satisfaction did not differ between the 2 groups. There was a significantly higher death rate among the elderly patients (13.3% versus 1.7%; P = .0202) and a significantly higher rate of dislocation (20% versus 1.7%; P = .0019). We conclude that revision hip replacement is an effective operation in the elderly, but that patient and surgeon must be aware of the risks that such surgery entails.

Adult↗
PubMed1999

Mentorship in nursing: a literature review.

The recent increase in published work relating to the supervision of nurses and in particular mentorship suggests that nurses value the opportunities that such schemes present for developing practice. Much of the literature surrounding mentorship concerns the supervision of students in practice settings but more recently, especially following the changes to post-registration education, attention has shifted to the supervision of qualified nurses. Although the principles of supervision for students and qualified nurses are the same, differences do occur in supervisory practices. This review examines the literature associated with the supervision of student nurses and focuses on the nature and practice of mentorship in practice settings. The literature reveals that confusion exists regarding both the concept of mentorship and the role of the mentor. Many authors propose models or frameworks for mentoring activities. These tend to outline the stages of the mentoring process and the relationship between mentor and mentee. No one model is seen as more appropriate than another and choice usually depends upon the mentor's familiarity with a particular framework. It is also evident that there is inconsistency in the length and level of preparatory courses for mentors. As yet there is in the United Kingdom no national minimum requirement or common preparation route and in practice mentors are prepared by way of the appropriate National Board Teaching and Assessing module and/or short local 2-day course.

Education, Nursing↗
PubMed1999

The stratified Petersen estimator with a known number of unread tags.

The Petersen estimator estimator of abundance can be biased when the assumption of homogeneous capture probability or homogeneous recapture probability is violated. Often this heterogeneity is related to the time or place of capture or recapture, and if these can be stratified, the stratified Petersen estimator reduces the bias caused by this heterogeneity. In some experiments, not all the recovered tagged animals can be examined, and only a subsample has its stratum of release and recovery determined. We develop methods for this modified experiment and apply them to estimate the number of salmon returning to spawn in a river in British Columbia, Canada.

Animals↗
PubMed1999

Effects of position of chest drainage tube on volume drained and pressure.

BACKGROUND: The nursing practice of avoiding dependent loops in the tubing of chest drainage systems because such loops may impede drainage and alter the intrapleural pressure is not research based. OBJECTIVES: To determine if the volume of fluid drained and pressure vary when the chest drainage tubing is straight, coiled, has a dependent loop, or has a dependent loop that is periodically lifted and drained. METHODS: A repeated-measures design was used. For each tubing position, 500 mL of fluid was infused into the pleural space of 8 adult pigs during 45 minutes. The volume of fluid drained and the pressure at 2 locations within the drainage tubing were measured for 1 hour. RESULTS: After 60 minutes, significantly less fluid (least significant difference test, P = .03) was drained with the dependent-loop tubing position (65 mL) than with the other 3 positions. However, the amount of fluid drained was not significantly different among the lift and drain (250 mL), coiled (301 mL), or straight (337 mL) tubing positions. Throughout the entire study, pressure at the connection between the chest tube and the drainage tube was significantly higher (least significant difference test, P = .003) for the dependent loop with and without periodic lifting and draining. CONCLUSIONS: Straight and coiled tube positions are optimal for draining fluid from the pleural space. If a dependent loop cannot be avoided, lifting and draining it every 15 minutes will maintain adequate drainage.

Animals↗
PubMed1999

The role of zinc in wound healing.

Zinc deficiency has been associated with delayed wound healing. Because zinc deficiency may be common in the United States, foods rich in zinc, as well as all other essential nutrients, should be promoted in the diet of patients who are malnourished or at risk for malnutrition.

Animals↗
PubMed1998

Age- and sex-related differences in clinical manifestations in patients with congenital long-QT syndrome: findings from the International LQTS Registry.

BACKGROUND: Unexplained female predominance is observed in long-QT syndrome (LQTS), a congenital autosomal disorder with prolonged repolarization and syncope or sudden death due to ventricular tachyarrhythmias. Our objectives were to evaluate age- and sex-related differences in events among LQTS patients referred to the LQTS International Registry. METHODS AND RESULTS: Age- and sex-related occurrence of events was analyzed in 479 probands (70% females) and 1041 affected family members (QTc >440 ms, 58% females). LQTS-gene mutations were identified in 162 patients: 69 LQT1 carriers (KVLQT1 on 11p15.5), 62 LQT2 carriers (HERG on 7q35-36), and 31 LQT3 carriers (SCN5A on 3p21-24). Females predominated among 366 probands (71% females) and 230 symptomatic family members (62% females). Male probands were younger than females at first event (8+/-7 versus 14+/-10 years, P<0.0001) and had higher event rates by age 15 years than females (74% versus 51%, P<0.0001). Affected family members had similar findings. By Cox analysis adjusting for QTc duration, the hazard ratio for female probands of experiencing events by age 15 years was 0.48 (P<0.001), and it was 1.87 (P=0.09) by age 15 to 40 years. In female family members, the hazard ratio was 0.58 (P<0.001) by age 15 years, and it was 3.25 (P<0.001) by age 15 to 40 years. The event rate was higher in male than female LQT1 carriers (69% versus 32%, P=0.001). No age-sex difference in event rate was detected in LQT2 and LQT3 carriers. CONCLUSIONS: Among LQTS patients, the risk of cardiac events was higher in males until puberty and higher in females during adulthood. The same pattern was evident among LQT1 gene carriers. Unknown sex factors modulate QT duration and arrhythmic events, with preliminary evidence of gene-specific differences in age-sex modulation.

Adult↗
PubMed1998

The cost-effectiveness of automatic implantable cardiac defibrillators: results from MADIT. Multicenter Automatic Defibrillator Implantation Trial.

BACKGROUND: The recently reported Multicenter Automatic Defibrillator Implantation Trial (MADIT) showed improved survival in selected asymptomatic patients with coronary disease and nonsustained ventricular tachycardia. The economic consequences of defibrillator management in this patient population are unknown. METHODS AND RESULTS: Patients were followed up to quantify their use of healthcare services, including hospitalizations, physician visits, medications, laboratory tests, and procedures, during the trial. The costs of these services, including the costs of the defibrillator, were determined in patients randomized to defibrillator and nondefibrillator therapy. Incremental cost-effectiveness ratios were calculated by relating these costs to the increased survival associated with the use of the defibrillator. The average survival for the defibrillator group over a 4-year period was 3.66 years compared with 2.80 years for conventionally treated patients. Accumulated net costs were $97,560 for the defibrillator group compared with $75,980 for individuals treated with medications alone. The resulting incremental cost-effectiveness ratio of $27,000 per life-year saved compares favorably with other cardiac interventions. Sensitivity analyses showed that the incremental cost-effectiveness ratio would be reduced to approximately $23,000 per life-year saved if transvenous defibrillators were used instead of the older devices, which required thoracic surgery for implantation. CONCLUSIONS: An implanted cardiac defibrillator is cost-effective in selected individuals at high risk for ventricular arrhythmias.

Cost-Benefit Analysis↗
PubMed1998

Influence of pregnancy on the risk for cardiac events in patients with hereditary long QT syndrome. LQTS Investigators.

BACKGROUND: The effects of pregnancy on women with the hereditary long QT syndrome are currently unknown. The appropriate medical management of pregnant patients with the long QT syndrome has not been established. METHODS AND RESULTS: The study was a retrospective analysis of the 422 women (111 probands affected with the long QT syndrome and 311 first-degree relatives) enrolled in the long QT syndrome registry who had one or more pregnancies. The first-degree relatives were classified as affected (QTc >0.47), borderline (QTc=0.45 to 0.47), and unaffected (QTc <0.45). Cardiac events were defined as the combined incidence of long QT syndrome-related death, aborted cardiac arrest, and syncope. The incidence of cardiac events was compared during equal prepregnancy, pregnancy, and postpartum intervals (40 weeks each). Multivariate logistic regression analysis was performed by use of a mixed-effects model to identify independent predictors of cardiac events among probands. The pregnancy and postpartum intervals were not associated with cardiac events among first-degree relatives. The postpartum interval was independently associated with cardiac events among probands (odds ratio [OR], 40.8; 95% confidence interval [CI], 3.1 to 540; P=.01); the pregnancy interval was not associated with cardiac events. Treatment with beta-adrenergic blockers was independently associated with a decrease in the risk for cardiac events among probands (OR, 0.023; 95% CI, 0.001 to 0.44; P=.01). CONCLUSIONS: The postpartum interval is associated with a significant increase in risk for cardiac events among probands with the long QT syndrome but not among first-degree relatives. Prophylactic treatment with beta-adrenergic blockers should be continued during the pregnancy and postpartum intervals in probands with the long QT syndrome.

Abortion, Induced↗
PubMed1998

Effects of r-metHuG-CSF on polymorphonuclear leucocyte kinetics and function in patients on continuous ambulatory peritoneal dialysis.

End-stage renal failure (ESRF) patients undergoing continuous ambulatory peritoneal dialysis (CAPD) are immunocompromised and exhibit abnormal circulating polymorphonuclear leucocyte (PMN) function, including reduced phagocytosis and intracellular killing. Six uraemic patients on CAPD were each given 300 microg granulocyte colony stimulating factor (G-CSF) every day for 5 d and PMN function tests were performed daily. By day 5 of the study CD11b expression was significantly decreased in response to N-formylmethionylleucylphenylalanine (fMLP) and opsonized Staphylococcus epidermidis stimulation, and expression of L-selectin (CD62L) was significantly decreased in response to opsonized Staphylococcus epidermidis stimulation. Further, superoxide anion production and Fc gammaRI (CD64) expression were found to be significantly increased and Fc gammaRII (CD16) expression was lowered. Circulating white cell and PMN counts were significantly elevated in response to treatment. Administration of G-CSF did not appear to have corrected the abnormalities in phagocytosis and intracellular killing. This study suggests that G-CSF does no harm to ESRF patients and influences uraemic PMN function in a manner that is comparable to its effects on PMN in non-uraemic subjects.

Adult↗
PubMed1997

Electrocardiographic findings in patients with diphenhydramine overdose.

QT interval prolongation and torsades de pointes ventricular tachycardia have been reported after therapeutic doses and overdosage of second generation antihistamines, such terfenadine and astemizol. Diphenhydramine (DPHM), a first generation H1 antagonist, is the most frequently used antihistaminic drug. Despite its widespread use, there are no data about cardiac action and electrocardiographic consequences of DPHM overdose. The 12-lead electrocardiograms of 126 patients (mean age 26 +/- 11 years) who had DPHM overdose were evaluated. The ingestion of large doses of DPHM (in majority of cases the dose was >500 mg) was primarily suicidal. Repolarization duration, dispersion, and morphology were evaluated in DPHM overdose patients and compared with those of healthy subjects. Mean heart rate of DPHM overdose patients was 103 +/- 25 beats/min. The QTc duration was significantly longer (453 +/- 43 vs 416 +/- 35 ms, respectively, p <0.001) and mean T-wave amplitude significantly lower (0.20 +/- 0.10 vs 0.33 +/- 0.15 mV, respectively, p <0.001) in DPHM-overdose patients than in control subjects. Dispersion of repolarization was significantly lower in DPHM-overdose patients than in control subjects (42 +/- 25 vs 52 +/- 21 ms, respectively; p = 0.003). None of the DPHM-overdose patients experienced torsades de pointes. In conclusion, DPHM overdose is associated with a significant increase in heart rate and a significant but moderate QTc prolongation. None of the studied patients, including those who had apparent QTc prolongation, experienced torsades de pointes ventricular tachycardia.

Adult↗
PubMed1997

Differential effects of immunologic challenge on self-stimulation from the nucleus accumbens and the substantia nigra.

Paralleling the effects of uncontrollable stressors, systemic administration of sheep red blood cells (SRBC) provokes brain neurotransmitter alterations, including DA variations within mesocorticolimbic regions, coinciding with or slightly preceding the peak immune response. Inasmuch as stressors disrupt responding for brain stimulation from the nucleus accumbens, possibly reflecting the anhedonic consequences of stressors, the present investigation assessed whether antigenic challenge would also influence responding for brain stimulation. Sheep red blood cell administration was found to reduce responding for brain stimulation from the nucleus accumbens, without affecting performance from the substantia nigra. The alterations of self-stimulation from the nucleus accumbens occurred at times that approximated the peak immune response. These data suggest that antigenic challenge may induce anhedonic-like effects that may be secondary to central neurochemical alterations engendered by the treatment. The possibility is also entertained that antigenic challenge may be interpreted as a stressor and contribute to alterations of affect.

Animals↗
PubMed1997

New uses for gentamicin-impregnated polymethyl methacrylate spacers in two-stage revision hip arthroplasty.

The use of antibiotic-impregnated cement as a bone spacer in two-stage revision hip surgery has been well described. Two additional placements for spacers are described: within the trochanteric osteotomy and overlying the greater trochanter. These spacers have been found to dramatically facilitate exposure at the second-stage procedure and are now being incorporated into all two-stage revision hip arthroplasties at The General Infirmary at Leeds.

Anti-Bacterial Agents↗
PubMed1997

Pharmacology of the 5-lipoxygenase inhibitors BAY Y 1015 and BAY X 1005 in the horse.

Calcium ionophore A23187 induced time and concentration dependent production of immunoreactive leukotriene (LT) B4 by equine heparinized whole blood in vitro. Time dependent production of immunoreactive LTB4 by equine neutrophils and immunoreactive LTC4 by equine eosinophils in vitro was also demonstrated. The 5-lipoxygenase activating protein (FLAP) inhibitors, BAY X 1005 and BAY Y 1015, produced concentration dependent inhibition of ionophore-induced LTB4 synthesis by equine whole blood (mean +/- SEM IC50s n = 5; 6.14 +/- 0.28 microM vs. 12.30 +/- 0.75 microM for BAY Y 1015 and BAY X 1005, respectively) and neutrophils (mean +/- SEM IC50s n = 5; 0.003 +/- 0.001 microM vs. 0.045 +/- 0.021 microM for BAY Y 1015 and BAY X 1005, respectively) and LTC4 synthesis by equine eosinophils (mean +/- SEM IC50s n = 5; 0.0036 +/- 0.0002 microM and 0.108 +/- 0.023 microM for BAY Y 1015 and BAY X 1005, respectively) in vitro. In all three assays, BAY Y 1015 was more potent than BAY X 1005, and for both compounds much higher concentrations were required to inhibit LT synthesis by whole blood compared to isolated neutrophils and eosinophils. Plasma concentration-time relationships and pharmacokinetic parameters for BAY Y 1015 administered intravenously and orally to six horses at a dosage of 10 mg/kg in a two period cross-over study were established. The study also evaluated the anti-inflammatory properties of BAY Y 1015 and its ability to inhibit ex vivo whole blood LTB4 synthesis and in vivo LTB4 synthesis in a tissue cage model of acute inflammation. At this dosage, BAY Y 1015 failed to significantly inhibit immunoreactive LTB4 synthesis or the oedema produced by intradermal injection of the mild irritant, carrageenan.

Administration, Oral↗
PubMed1996

Lower limb alignment and foot angle are related to stance phase knee adduction in normal subjects: a critical analysis of the reliability of gait analysis data.

Anatomic and mechanical factors that affect loading in the knee joint can contribute to pathologic changes seen at the knee in degenerative joint disease and should be considered in treatment planning. The objectives of this study were to quantify the relationships between the alignment of the bones of the lower extremity, foot progression angle, and knee adduction moment, and to determine the reliability of our gait measurements. Gait analysis and complete radiographic evaluation of the lower extremity were performed on 11 healthy subjects. The gait measurements were recorded with an optoelectronic digitizer and a multi-component force plate. The subjects who had radiographic measurements indicative of varus alignment of the lower extremity had statistically higher peaks in knee adduction moment in early stance. Conversely, those with valgus alignment of the lower extremity had statistically lower peaks in knee adduction moment in early stance. The subjects who had a large toe-out angle and low ankle inversion moment peaks in late stance had significantly lower peaks in knee adduction moment in late stance. These significant (low to moderate) correlations suggest that the limbs with more valgus alignment and those with a toe-out gait exhibited a reduced peak adduction moment at the knee. To verify the reproducibility of the data, gait analysis testing was performed on each lower limb on 2 separate days for each subject. Analysis of variance showed that there was no significant difference between test limbs or test days for each subject. Our results suggest that the alignment of the lower limb and the foot progression angle, which can be readily measured in a clinical setting, can serve as predictors of knee joint loading in healthy individuals. These findings may have important implications for both surgical and nonsurgical treatment of abnormalities of the knee joint.

Adult↗
PubMed1996

Marked reduction in long-term cardiac deaths with aspirin after a coronary event. Multicenter Myocardial Ischemia Research Group.

OBJECTIVES: We sought to assess the role of aspirin in a precisely defined cohort with coronary disease receiving current therapy. BACKGROUND: Prior results suggest that aspirin modestly decreases cardiac mortality in patients with coronary disease. However, these findings reflect heterogeneous study conditions and earlier management strategies. METHODS: We utilized findings from the Multicenter Study of Myocardial Ischemia, which enrolled 936 subjects 1 to 6 months after an acute myocardial infarction (n = 651 [70%]) or unstable angina (n = 285 [30%]). The follow-up period averaged 23 months, with treatment determined by referring physicians. RESULTS: At enrollment, 751 patients (80%) took aspirin regularly, usually 250 to 325 mg/day. Before enrollment, 291 patients (31%) had thrombolysis, and 352 (38%) had coronary angioplasty. During follow-up, cardiac death occurred in 22 patients, all-cause mortality in 31 and cardiac death or nonfatal myocardial infarction in 70. Each of these outcomes was significantly less frequent among aspirin users. Cardiac death rate was markedly reduced: 1.6% for aspirin users and 5.4% for nonusers (p = 0.005). These differences were not explained by imbalances in predictors of postinfarction risk or therapy other than aspirin (Cox hazard ratio 0.37, p = 0.023). They persisted at least 2 years after enrollment. The difference in mortality rate was particularly prominent after thrombolysis: 0.9% for aspirin users and 8.8% for nonusers (p = 0.004). CONCLUSIONS: Reduction in cardiac deaths among aspirin users is substantially greater than that reported previously. Although derived secondarily, our findings suggest that current practice leads to situations in which aspirin exerts a long-term, life-protecting action, particularly after thrombolysis.

Aspirin↗