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Biomedical subjects

M Jenkins

Publications and source records attributed to M Jenkins.

At least 55 records · Page 3Linked to original sources
PubMed1998

Prospective comparison of temperature guided microwave and radiofrequency catheter ablation in the swine heart.

Microwave energy has been proposed as an alternative to radiofrequency energy for use during catheter ablation procedures. The purpose of this study was to prospectively compare, in an animal model, the lesion size associated with temperature guided catheter ablation using either microwave or radiofrequency energy. Eleven swine underwent catheter ablation with either radiofrequency (N = 4) or microwave energy (N = 7). In each animal catheter ablation was performed at 7-15 sites. At each site energy was delivered for 60 seconds using closed loop feedback temperature control to achieve a target temperature of 70 degrees C. Cardiac catheterization was performed before and after ablation. Animals were sacrificed approximately one month following the ablation procedure. Analysis of lesion size demonstrated that overall lesions created using radiofrequency energy were larger than those created using microwave energy. In the ventricle, lesions created using microwave energy were longer, but had a similar width and depth as those created using radiofrequency energy. An important relation was observed between the depth of lesions created using microwave energy and catheter stability, as evidenced by the temperature profile. Overall, lesions created using microwave energy are smaller than those created using radiofrequency energy. Catheter stability has an important impact on lesion size.

Animals↗
PubMed1998

Memory processes in depressed geriatric patients with and without subcortical hyperintensities on MRI.

In this study, 12 patients over age 60 with depression with moderate to severe subcortical hyperintensities (SH) localized to the periventricular white matter were identified by quantitative MRI. Using the California Verbal Learning Test, they were compared with 12 age-, education-, and severity-matched patients with depression with minimal white matter changes on specific aspects of memory performance. Patients with cortical lesions, neurologic or systemic illness affecting cognition, and history of substance abuse were excluded. Patients in the group with high SH showed reduced use of semantic encoding strategies (p < 0.05), reduced learning efficiency (p < 0.05), and a greater discrepancy between free recall and recognition discriminability (p < 0.05) than their low SH counterparts. This pattern of performance on memory tasks is similar to that found in previous studies to be associated with subcortical degenerative disorders such as Huntington's and Parkinson's diseases. Geriatric patients with depression with SH may represent a subgroup with greater subcortical involvement, with associated cognitive and functional decline.

Aged↗
PubMed1998

Albumin-binding surfaces: synthesis and characterization.

The nature of the proteinaceous film deposited on a biomaterial surface following implantation is a key determinant of the subsequent biological response. To achieve selectivity in the formation of this film, monoclonal antibodies have been coupled to a range of solid substrates using avidin-biotin technology. Antibody clones varied in their antigen-binding activity following insertion of biotin groups into lysine residues. Biotinylated antibodies coupled to solid substrates via an immobilized avidin bridge retained their biological activity. During immobilization of avidin a significant proportion of the protein molecules were passively adsorbed rather than covalently attached to the surface. This loosely bound material could be removed by stringent elution procedures which resulted in a surface density of 5.4 pmol avidin cm(-2). Although these conditions would be harsh enough to denature monoclonal antibodies, they did not destroy the biotin-binding activity of the residual surface-coupled avidin, enabling the subsequent immobilization of biotinylated antibodies. The two-step immobilization technique allowed the use of gentle protein modification procedures, reduced the risk of surface-induced denaturation and removed loosely bound material from the surface. The versatility of the technique encourages its application to a wide range of immobilization systems where retention of biological activity is a key requirement.

Adsorption↗
PubMed1998

Albumin-binding surfaces: in vitro activity.

Immobilized monoclonal antibodies (Mabs) have been used to attract specific molecules to a solid surface from complex mixtures such as blood, plasma or serum, thereby directing the response to the modified substrate, a key goal in rational biomaterial design. The nature of the Mab dictated the nature of the response: anti-albumin antibodies were used to prevent cell and platelet adhesion in vitro, whilst anti-fibronectin Mabs promoted attachment. Patterned surfaces could be formed, bearing Mabs that generated adhesive and non-adhesive regions. Fibrinogen adsorption from plasma showed a Vroman peak on unmodified control polymer, which was reduced by 64% in the presence of surface-bound anti-albumin Mab. Immobilization of a control Mab reduced fibrinogen adsorption only slightly, implying an albumin-mediated effect. In static tests, platelet adhesion from human platelet rich plasma was significantly reduced by the immobilization of anti-HSA Mab when compared to the untreated FEP surface (p < 0.0001). This effect was also seen with citrated blood flowing through Mab-treated polyurethane tubing at a shear rate of 132 s(-1) (p=0.034). Since platelets and proteins (as blood, plasma or serum) were introduced to the surface simultaneously, the generation of a defined protein film must have been sufficiently rapid as to shape the platelet or cell response.

Antibodies, Monoclonal↗
PubMed1998

On nurses.

Explore the source record for details and available documents.

Health Promotion↗
PubMed1998

Implementation of a clinical information system in nurse-managed care.

The Penn Nursing Network Information System Project is a collaborative effort of practitioners, academic researchers, and a health-care software developer. The Penn Nursing Network, a group of nurse-managed practices owned and operated by the University of Pennsylvania School of Nursing, has taken a leadership role in the project. PNN is developing an information system specific to the needs of nurse-managed care and creating a data warehouse for nursing centres in the Philadelphia region. Important components of this project include the identification of key data elements to represent the problems treated, interventions performed, and outcomes sensitive to the nursing care provided. The Omaha System provided a useful framework for capturing the necessary data elements. However, additional data were needed. In addition, attention was paid to the development of a software program that would complement the workflow of the practitioner while capturing data efficiently. The main goal of the project is development of a longitudinal database reflective of clinical practice, to be used for both research and evaluation.

Clinical Nursing Research↗
PubMed1997

Lack of effect of sleep on energy expenditure and physiologic measures in critically ill burn patients.

OBJECTIVE: Energy expenditure measurements, performed while patients are in standardized resting conditions, are often used as an indicator of care by which to evaluate the adequacy of nutrition support regimens. Little attention has been directed toward examining potential errors incurred by deriving daily energy needs based on a single 15- to 20-minute measurement. This study was designed to differentiate energy expenditure during periods of sleep (defined as time spent in any of the standard sleep stages) and wakefulness in pediatric burn patients. DESIGN: Twenty-four-hour indirect calorimetry, polysomnography, and physiologic assessments (mean arterial pressure, heart rate, body temperature, oxygen saturation, and respiratory rate) were conducted simultaneously in 14 patients, who were thermally injured and tracheally intubated, for a total of 45 24-hour intervals. SUBJECTS: Mean age of the patients was 10.8+/-1.2 years. Mean total body surface area of the injury was 55.7+/-4.7%, and mean full-thickness burn was 48.8+/-6.0%. STATISTICAL ANALYSES PERFORMED: A nested general linear analysis of variance model was used to evaluate the association between sleep, wakefulness, and energy needs; adjustments were made for postburn day and multiple test runs per patient. RESULTS: On average, subjects slept 699+/-46 minutes/day. They experienced a large number of awakenings from sleep (mean=53+/-6.3 awakenings per 24 hours). Patients had mean energy expenditure of 2,529+/-396 kcal/day while awake and 2,360+/-291 kcal/day while asleep, and these mean values did not differ significantly. No differences in physiologic measurements during the awake and sleep states were found. APPLICATIONS: There appears to be little difference in the metabolism of seriously injured burn patients while asleep and while awake. The study deemphasizes the importance of performing indirect calorimetry at rest in critically ill pediatric burn patients, and it supports the extrapolation of daily energy expenditure from a 15- to 20-minute steady-state measurement obtained during either sleep or wakefulness.

Adolescent↗
PubMed1997

Ovarian hyperthecosis, diabetes and hirsuties in post-menopausal women.

OBJECTIVE: We describe four patients with ovarian hyperthecosis and the effects of gonadotrophin releasing hormone on clinical and metabolic variables. DESIGN: Open out-patient study. PATIENTS: Four women presented with post-menopausal hirsuties. They had significant hair growth across the chest, upper back and shoulders. Three had histologically proven ovarian hyperthecosis and a fourth had large ovaries visualized on ultrasound. All four women had pronounced risk factors for vascular disease; hypertension, hyperlipidaemia and glucose intolerance, and three had already developed symptomatic vascular disease. RESULTS: Gonadotrophin releasing hormone agonist therapy resulted in significant reduction in plasma androgens and cosmetic reduction in hair growth but had no effect on hyperlipidaemia. CONCLUSION: The post-menopausal women described in this report were clinically considered to have hyperandrogenism due to the pathological pattern of marked body hair over the upper trunk. Treatment with GnRH was very effective at reducing the severity of the hirsuties. The post-menopausal women with hyperthecosis in this report had a high prevalence of cardiovascular disease. Since hyperandrogenism and insulin are considered risk factors for cardiovascular disease in premenopausal women with polycystic ovaries, we discuss the possible relationship between insulin and the post-menopausal ovary.

Aged↗
PubMed1997

Disruption of short-duration timing associated with damage to the suprachiasmatic region of the hypothalamus.

The neural bases of circadian rhythmicity have been demonstrated in a variety of animal species, including primates. Yet, the brain mechanisms underlying time experience and the timing of behaviors of shorter duration are still not well understood. In the present study, we demonstrate disruption of short-duration timing capacity in AH, a patient with damage to the suprachiasmatic (SCN) region of the hypothalamus. AH exhibited extreme inconsistency in her rate of tapping production on a motor continuation paradigm. Her inter-response intervals (IRIs) were extremely large compared with normal control subjects and were similar to those previously reported in patients with cerebellar dysfunction. Increased variability of both central timing and motor implementation processes was evident compared with both age-matched and elderly normal control subjects. Severe impairment of time perception was also evident on duration discrimination, whereas auditory loudness discrimination was intact. These findings suggest that a hierarchic relationship between long-duration (circadian) and short-duration timing exists, and that in addition to the cerebellum, intact hypothalamic functioning is necessary for short-duration timing.

Adult↗
PubMed1997

Community partnership primary care case study: Abbottsford Community Health Center.

Welfare reform and the movement of Medicaid to managed care have set the stage for great risk and potential reward for low-income communities and their health care providers. Nurse practitioners are responding to current opportunities by opening up nurse practitioner-directed practices to offer a range of care to targeted high-risk patients and communities. Nursing practices and the communities they serve will be greatly strengthened by democratic collaboration and partnership. The beginnings of Abbottsford Community Health Center are described as an example of community partnership primary care.

Community Health Centers↗
PubMed1996

Symptom reporting in cancer patients: the role of negative affect and experienced social stigma.

BACKGROUND: Recent research suggests that patients' appraisal of somatic symptoms is more closely related to emotional variables (particularly negative affect) than to their actual health as determined by external criteria. METHODS: Sixty surgical cancer patients who at the time of a routine follow-up examination filled out the European Organization for Research and Treatment of Cancer (EORTC) quality of life questionnaire-C30, which included a positive/negative affect scale and a scale tapping into experienced social stigma. Patients' health status was determined in two ways: the examining physician gave a global judgement on a standardized scale at the end of the examination, and an additional two external physicians later rated the patients based on the findings listed in the medical record. RESULTS: Patients' reports of somatic symptoms were strongly correlated with two measures of negative affect (r = 0.75 and r = 0.65, respectively) and with experienced social stigma (r = 0.51). In contrast, the correlations between reported symptoms and the examining or external physicians' ratings were considerably weaker (r = 0.31 and r = 0.19). According to a multiple linear regression with 6 predictors, negative affect was the best single predictor of symptom reporting (beta = 0.68; P < 0.001) and global quality of life (beta = 0.48; P < 0.001). Factor analysis yielded a dimension of somatopsychosocial distress that accounted for 44.1% of the variance and is comprised of reported symptoms (factor loading = 0.86), negative affect (0.90 and 0.82), experienced social stigma (0.74), and global quality of life (0.70). Physicians' ratings and positive affect constituted two additional separate factors. CONCLUSIONS: Cancer patients' reporting of somatic symptoms by means of a standardized quality of life questionnaire is closely related to emotional and social distress and is not equivalent to health status as determined from a clinical perspective. Researchers and practitioners have to be aware of this fact when interpreting quality of life data. Furthermore, negative affect deserves attention as an important signal for intervention in tumor follow-up programs.

Abdominal Neoplasms↗
PubMed1996

Effects of short-term supplementation with coenzyme Q10 on myocardial protection during cardiac operations.

BACKGROUND: Coenzyme Q10 (CoQ10) is a naturally occurring vitamin-like substance that may have a beneficial role in ischemia-reperfusion injury. Coenzyme Q10 administered either as an additive to cardioplegia or as long-term preoperative oral supplementation has been reported to ameliorate myocardial injury after cardiac operations. METHODS: To determine whether short-term supplementation with large doses of CoQ10 (600 mg in divided doses 12 hours before operation) was effective in myocardial protection, 20 patients with well-preserved left ventricular function (ejection fraction greater than 0.50) undergoing elective coronary revascularization were enrolled in a prospective, double-blind, placebo-controlled randomized trial. Serial concentrations of CoQ10, myoglobin, creatine kinase MD fraction, and cardiac troponin T were measured preoperatively and 1, 6, 24, 72, and 120 hours postoperatively. Efficacy of myocardial protection was also assessed by clinical outcome and serial changes in electrocardiographic indices. RESULTS: The patient groups were similar with respect to preoperative and intraoperative characteristics. There was no significant difference in the preoperative plasma levels of CoQ10. These levels fell significantly in both groups after operation, although the magnitude of the decrease was less in the CoQ10-supplemented group (43% versus 60%). In both groups, there were significant postoperative increases in myoglobin, creatine kinase MB fraction, and cardiac troponin T. The magnitude of increases in cardiac troponin T was greater in the CoQ10-supplemented group, reaching marginal overall statistical significance (p = 0.06). CONCLUSIONS: Short-term supplementation with large doses of CoQ10 does not lead to improved myocardial protection in patients undergoing coronary revascularization with well-preserved ventricular function and relatively short ischemic times.

Coenzymes↗
PubMed1995

Serum and colostrum antibody responses induced by jet-injection of sheep with DNA encoding a Cryptosporidium parvum antigen.

In an effort to generate high titer colostrum for immunotherapy of cryptosporidiosis, a study was conducted to test the efficacy of immunizing sheep with recombinant plasmid DNA (pCMV-CP15/60) encoding epitopes of 15 and 60 kDa surface antigens of Cryptosporidium parvum sporozoites. The plasmid DNA was used to immunize preparturient ewes at three dose levels by jet-injection into either hind limb muscle (IM) or mammary tissue (IMAM). Regardless of route of injection, a dose-dependent anti-CP15/60 immunoglobulin response was observed in sera and colostrum from sheep immunized with pCMV-CP15/60 plasmid DNA. High titer antibody responses were observed in one of three animals per group receiving an IM injection of 100 or 1000 micrograms pCMV-CP15/60. IMAM immunization with 100 or 1000 micrograms pCMV-CP15/60 plasmid DNA elicited higher titer colostrum responses and more consistent serum responses compared to IM injections. A negligible serum and colostrum anti-CP15/60 response was observed in ewes injected IM with 10 micrograms pCMV-CP15/60 or 1000 micrograms control plasmid DNA. Immunoblotting of native C. parvum sporozoite/oocyst protein with hyperimmune serum and colostrum corroborated the increased titers against CP15/60 antigen. Serum and colostrum antibodies from pCMV-CP15/60-immunized sheep were eluted from native CP15 protein and bound a surface antigen of C. parvum sporozoites as indicated by indirect immunofluorescence staining.

Animals↗
PubMed1995

Unidentified retained left atrial myxoma: intra-operative detection by trans-oesophageal echocardiography.

A 73-year-old woman underwent surgery for removal of a large left atrial myxoma diagnosed by transthoracic echocardiogram. At operation a large tumour was removed, and the left atrium and atrial septum closed. Trans-oesophageal echocardiography prior to weaning from cardiopulmonary bypass revealed that a smaller tumour, which had not been detected by visual inspection or palpation, remained within the left atrium. This was removed through the atrial septum, and the operation completed uneventfully. The patient made a full recovery.

Aged↗
PubMed1995

Clinical evaluation of CFC-free metered dose inhalers.

Current metered dose inhalers (MDIs) contain chlorofluorocarbon (CFC) propellants. A new propellant HFA134a, with no effect on ozone, may be a suitable alternative. Four asthma medications, salbutamol, salmeterol, fluticasone propionate (FP) and beclomethasone dipropionate (BDP), currently containing standard CFC propellants, were formulated with HFA134a for investigation. Single doses of salbutamol (200 micrograms) and salmeterol (50 micrograms, 100 micrograms) provided equivalent protection against bronchial provocation, after histamine and methacholine respectively, compared with the current preparation. A double-blind 4 week study comparing the two formulations of salbutamol, used as required in mild to moderate asthma, showed similar effects on morning peak expiratory flow rates (PEFR) and inhaler use. Salmeterol (50 micrograms) twice daily was compared with the current formulation in a 4 week trial. Improvement in morning PEFR was similar for both formulations. A double-blind study compared the two formulations of FP (250 micrograms) twice daily in moderate asthmatics previously taking 400-1,000 micrograms of inhaled corticosteroid daily. Morning PEFR improved in both groups. Safety and tolerability of the HFA134a product were similar to current formulations. The HFA134a formulations of salbutamol, salmeterol and FP provide equivalent efficacy with a similar safety profile to the existing formulations at equivalent doses.

Adult↗
PubMed1995

Health maintenance behaviors in advanced Parkinson's disease.

Co-morbidity in the older adult Parkinson's disease patient decreases functional status and quality of life, and increases the risk of permanent disability. Although many chronic conditions in the adult population can be prevented, or at least influenced by early detection and treatment many progressive neurologic disorders such as Parkinson's disease cannot. This pilot study describes the health maintenance and disease prevention behaviors of a group of patients with Parkinson's disease. Findings demonstrate that parkinsonians attend in a way similar to their peers without Parkinson's disease to most parameters of general health maintenance as established by the United States Preventive Task Force. In fact, in 11 out of 12 selective parameters, parkinsonians exhibit increased frequency of participation in the recommended behaviors. However, achievement of our national goals for health promotion and disease prevention will require additional efforts in this population. Emphasis should include the participation in Pap smears, mammograms, exercise, seat belt usage and adult immunizations, especially the pneumococcal vaccination. Neuroscience nurses can play an important role in reaching health promotion and disease prevention goals in persons with Parkinson's disease through patient education, advocacy, case management, anticipatory guidance and referrals to primary care providers.

Aged↗