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Biomedical subjects

J Davis

Publications and source records attributed to J Davis.

At least 55 records · Page 3Linked to original sources
PubMed2001

Shared learning in practice placements for health and social work students in east London: a feasibility study.

A voluntary organisation providing family support and mental health services carried out an enquiry into the feasibility of setting up placements in primary care for students from professional qualifying courses in community nursing, social work and occupational therapy to experience shared practice learning in their placement. Consultation with a range of courses from two universities in London and with GP practices and other primary care agencies in East London established that there was wide support for the idea from practitioners, managers and academic teachers. It was recommended that a small number of pilot placements be set up. It was acknowledged that the diversity of placement requirements across the spectrum of professional education is a limiting factor in bringing students together for practice learning. The authors suggest that in the longer term, the development of an interprofessional approach to practice learning will require structural changes to professional courses so as to bring their placement requirements more into line with each other.

Clinical Clerkship↗
PubMed2001

Cardiovascular health interventions in women: What works?

Women's Cardiovascular Health Network members representing 10 Prevention Research Centers completed a literature review of approximately 65 population-based studies focused on improving women's cardiovascular health through behavior change for tobacco use, physical inactivity, or diet. A framework was developed for conducting the search. Databases (Medline, Psychlit, Smoking and Health, Cumulative Index to Nursing and Allied Health Literature) of studies published from 1980 to 1998 were searched. The review was presented at a meeting of experts held in Atlanta, Georgia. Output from the meeting included identification of what has worked to improve cardiovascular health in women and recommendations for future behavioral research. Additional information is available at www.hsc.wvu.edu/womens-cvh. Cardiovascular health interventions geared toward women are scant. Based on the available studies, program components that emerged as effective included personalized advice on diet and physical activity behaviors and tobacco cessation, multiple staff contacts with skill building, daily self-monitoring, and combinations of strategies. Recommendations for community-based tobacco, physical activity, and diet interventions are discussed. A few overarching recommendations were to (1) conduct qualitative research to determine the kinds of interventions women want, (2) examine relapse prevention, motivation, and maintenance of behavior change, (3) tailor programs to the stage of the life cycle, a woman's readiness to change, and subgroups, that is, minority, low socioeconomic, and obese women, and (4) evaluate policy and environmental interventions. The effects of cardiovascular interventions in women have been inappropriately understudied in women. Our review found that few studies on cardiovascular risk factor modification have actually targeted women. Hence, adoption and maintenance of behavior change in women are elusive. Intervention research to improve women's cardiovascular health is sorely needed.

Attitude to Health↗
PubMed2001

Effects of adenosine receptor subtype A1 on ventricular and renal function.

The adenosine subtype 1 (A1) receptor, which may influence cardiac function and modulate renal function, may have particular relevance in congestive heart failure (CHF). However, the effects of A1 receptor inhibition in the setting of CHF are poorly defined. Systemic hemodynamics and indices of renal function were measured in pigs with pacing-induced CHF at 240 bpm for 3 weeks (n = 10) before and after A1 receptor blockade with 100 microg of BG9719 (1,3-dipropyl-8-[2-(5,6-epoxynorbornyl)]xanthene) or in CHF pigs after infusion of vehicle only (n = 10). Heart rate, mean aortic pressure, and left ventricular peak pressure increased following A1 blockade in the CHF group, consistent with an adenosine inhibitory effect. However, cardiac output and global measures of vascular resistance did not significantly change following A1 blockade. Urine output increased twofold and sodium clearance increased threefold following A1 blockade (p < 0.05). Creatinine clearance increased following A1 blockade (127 +/- 17 vs. 62 +/- 7 ml/min, p < 0.05). Selective A1 receptor blockade improved glomerular filtration rate and induced a natriuresis and diuresis in a model of CHF without adverse effects on cardiac function. These unique results suggest that renal A1 receptor activation may contribute to the reduced renal function associated with CHF.

Animals↗
PubMed2001

Managed care and the evolution of patient rights.

Managed care has grown into the driving force for coordinating and managing healthcare delivery and its financing. At the same time, major initiatives have gained momentum in societal and legislative efforts regarding patient rights. This article provides a historical, legal, and philosophical review of the major events that have shaped the evolution of healthcare services and development of the patient rights issue. As the healthcare industry finds itself in a state of needed reform, the future evolution of managed care in light of the patient rights issue will have important implications for legislators, clinicians, and healthcare organizations as they struggle to provide quality care and improve cost controls.

Humans↗
PubMed2001

Impact of a school-based health center on emergency department use by elementary school students.

While school-based health centers (SBHC) improve student access to health services, it remains unclear if use of the centers can reduce hospital emergency department visits. This study evaluated the impact of an elementary school SBHC on emergency department visits by children enrolled in the center. Major reasons for visits included trauma (32%), otitis media (15%), upper respiratory infections (9%), and gastroenteritis (6%). Implementation of an elementary SBHC resulted in a significant decrease (p < 0.03) in non-urgent emergency department visits. No difference existed in urgent emergency department visits. Medicaid-insured children were more likely to use the emergency department than privately insured or uninsured children. Reducing emergency department visits can decrease medical costs and support the cost effectiveness of SBHCs.

Adolescent↗
PubMed2001

Evolution of an autotransporter: domain shuffling and lateral transfer from pathogenic Haemophilus to Neisseria.

The genomes of pathogenic Haemophilus influenzae strains are larger than that of Rd KW20 (Rd), the nonpathogenic laboratory strain whose genome has been sequenced. To identify potential virulence genes, we examined genes possessed by Int1, an invasive nonencapsulated isolate from a meningitis patient, but absent from Rd. Int1 was found to have a novel gene termed lav, predicted to encode a member of the AIDA-I/VirG/PerT family of virulence-associated autotransporters (ATs). Associated with lav are multiple repeats of the tetranucleotide GCAA, implicated in translational phase variation of surface molecules. Laterally acquired by H. influenzae, lav is restricted in distribution to a few pathogenic strains, including H. influenzae biotype aegyptius and Brazilian purpuric fever isolates. The DNA sequence of lav is surprisingly similar to that of a gene previously described for Neisseria meningitidis. Sequence comparisons suggest that lav was transferred relatively recently from Haemophilus to Neisseria, shortly before the divergence of N. meningitidis and Neisseria gonorrhoeae. Segments of lav predicted to encode passenger and beta-domains differ sharply in G+C base content, supporting the idea that AT genes have evolved by fusing domains which originated in different genomes. Homology and base sequence comparisons suggest that a novel biotype aegyptius AT arose by swapping an unrelated sequence for the passenger domain of lav. The unusually mobile lav locus joins a growing list of genes transferred from H. influenzae to Neisseria. Frequent gene exchange suggests a common pool of hypervariable contingency genes and may help to explain the origin of invasiveness in certain respiratory pathogens.

Amino Acid Sequence↗
PubMed2001

Effects of extracellular calcium and potassium on the sodium pump of rat adrenal glomerulosa cells.

Because the activity of the sodium pump (Na-K-ATPase) influences the secretion of aldosterone, we determined how extracellular potassium (K(o)) and calcium affect sodium pump activity in rat adrenal glomerulosa cells. Sodium pump activity was measured as ouabain-sensitive (86)Rb uptake in freshly dispersed cells containing 20 mM sodium as measured with sodium-binding benzofluran isophthalate. Increasing K(o) from 4 to 10 mM in the presence of 1.8 mM extracellular calcium (Ca(o)) stimulated sodium pump activity up to 165% and increased intracellular free calcium as measured with fura 2. Increasing K(o) from 4 to 10 mM in the absence of Ca(o) stimulated the sodium pump approximately 30% and did not increase intracellular free calcium concentration ([Ca(2+)](i)). In some experiments, addition of 1.8 mM Ca(o) in the presence of 4 mM K(o) increased [Ca(2+)](i) above the levels observed in the absence of Ca(o) and stimulated the sodium pump up to 100%. Ca-dependent stimulation of the sodium pump by K(o) and Ca(o) was inhibited by isradipine (10 microM), a blocker of L- and T-type calcium channels, by compound 48/80 (40 microg/ml) and calmidizolium (10 microM), which inhibits calmodulin (CaM), and by KN-62 (10 microM), which blocks some forms of Ca/CaM kinase II (CaMKII). Staurosporine (1 microM), which effectively blocks most forms of protein kinase C, had no effect. In the presence of A-23187, a calcium ionophore, the addition of 0.1 mM Ca(o) increased [Ca(2+)](i) to the level observed in the presence of 10 mM K(o) and 1.8 mM Ca(o) and stimulated the sodium pump 100%. Ca-dependent stimulation by A-23187 and 0.1 mM Ca(o) was not reduced by isradipine but was blocked by KN-62. Thus, under the conditions that K(o) stimulates aldosterone secretion, it stimulates the sodium pump by two mechanisms: direct binding to the pump and by increasing calcium influx, which is dependent on Ca(o). The resulting increase in [Ca(2+)](i) may stimulate the sodium pump by activating CaM and/or CaMKII.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed2001

Myocardial and interstitial matrix metalloproteinase activity after acute myocardial infarction in pigs.

A structural event during the evolution of a myocardial infarction (MI) is left ventricular (LV) remodeling. The mechanisms that contribute to early changes in LV myocardial remodeling in the post-MI period remain poorly understood. Matrix metalloproteinases (MMPs) contribute to tissue remodeling in several disease states. Whether and to what degree MMP activation occurs within the myocardial interstitium after acute MI remains to be determined. Adult pigs (n = 15) were instrumented to measure regional myocardial function and interstitial MMP levels within regions served by the circumflex and left anterior descending arteries. Regional function was measured by sonomicrometry, and interstitial MMP levels were determined by selective microdialysis and zymography as well as by MMP interstitial fluorogenic activity. Measurements were performed at baseline and sequentially for up to 3 h after ligation of the obtuse marginals of the circumflex artery. Regional fractional shortening fell by over 50% in the MI region but remained unchanged in the remote region after coronary occlusion. Release of soluble MMPs, as revealed by zymographic activity of myocardial interstitial samples, increased by 2 h post-MI. The increased zymographic activity after MI was consistent with MMP-9. Myocardial interstitial MMP fluorogenic activity became detectable within the ischemic region as early as 10 min after coronary occlusion and significantly increased after 1 h post-MI. MMP fluorogenic activity remained unchanged from baseline values in the remote region. The present study demonstrated that myocardial MMP activation can occur within the MI region in the absence of reperfusion. These unique results suggest that MMP release and activation occurs within the ischemic myocardial interstitium in the early post-MI period.

Animals↗
PubMed2001

Wavelet transform of the EEG reveals differences in low and high gamma responses to elementary visual stimuli.

Multiunit electrophysiological studies indicate that oscillatory activity is common in the awake mammalian central nervous system. Synchronous 20-80 Hz oscillations, so called gamma rhythms, have been proposed as a possible fundamental physiological mechanism of binding neuronal activity underlying object recognition. The purpose of this study was to determine whether or not gamma band oscillatory activity in the human brain is modulated by attributes of elementary visual stimulation. The experiment was performed on 7 normal subjects. Sinusoidal gratings were presented over a range of spatial frequencies. Evoked potentials were recorded over 5 surface electrodes placed in a horizontal occipital chain across the back of the head. Discrete wavelet transform was performed on the first 200 msec following stimulus onset on the average data of 256 sweeps. Power was analyzed with ANOVA across conditions. In our previous studies we have separated a "low" (14-28 Hz) and "high" (28-55 Hz) gamma band. The current results indicate that both gamma bands to full-field stimulation have the highest power at the midline (inion) electrode to a spatial frequency of 5.5 cpd, which is the peak spatial frequency from foveal psychophysical data. However, the spatial frequency bandwidth is considerably narrower in the HG than in the LG band. Occipital spatial frequency tuning of the massed high gamma response is narrower than the tuning of individual cortical neurons. The bandwidth difference between low and high gamma band suggests that different frequency gamma range oscillations may represent not only different functional properties of visual processing, but may also reflect underlying differences in excitatory and postsynaptic inhibitory circuits shaping the contrast sensitivity of the human observer. Our study emphasizes the importance of elementary visual filter properties for gamma responses and the need to subdivide gamma frequency ranges according to functional properties.

Adolescent↗
PubMed2001

Progression curves for endometrial lesions.

OBJECTIVE: To derive a numeric measure for the progression of endometrial lesions as a baseline study for an eventual assessment of chemopreventive intervention efficacy. STUDY DESIGN: Tissue sections from normal endometrium at the proliferative and secretory phase, simple hyperplasia, atypical hyperplasia from cases free of concomitant adenocarcinoma and adenocarcinoma of the endometrium were recorded at high spatial resolution. Six cases from each diagnostic category were chosen as "typical," and 60 epithelial nuclei were randomly selected for measurement for each case. Discriminant analyses were carried out to derive a direction of progressive change in feature space and to correct the progression curve for the presence of cells not expressing progressive change among the random sample of nuclei. RESULTS: A well-conditioned progression curve was derived based on the mean discriminant function scores for each diagnostic category and the mean nuclear abnormality of the nuclei in each category, as expressed by their deviation in feature values from normal reference nuclei. The lesion signatures showed a clear trend toward extension into the range of higher nuclear abnormalities with increasing progression. There was an indication that abnormal endometrial lesions may comprise cases with distinctly different degrees of nuclear abnormality. CONCLUSION: A numeric assessment of lesion progression for endometrial lesions, based on karyometric measurements, is possible. The data suggest that additional analysis may provide further characterizing information for individual lesions.

Adenocarcinoma↗
PubMed2001

Phase I and pharmacokinetic study of ecteinascidin 743 administered as a 72-hour continuous intravenous infusion in patients with solid malignancies.

Ecteinascidin 743 (ET-743) is a cytotoxic tetrahydroisoquinoline alkaloid that covalently binds to DNA in the minor groove. The in vitro chemosensitivity of cancer cells to ET-743 is markedly enhanced by prolonging the duration of exposure to the drug. A Phase I study of ET-743 given as a 72-h continuous i.v. infusion every 21 days was performed. Characteristics of the 21 adult patients with refractory solid tumors enrolled in the study were as follows: (a) 12 men; (b) 9 women; (c) median age, 59 years; (d) Eastern Cooperative Oncology Group performance status < or = 1, 20 patients; and (e) two prior regimens of chemotherapy, 7 patients. Dose limiting toxicity (DLT) was defined by typical criteria, except that grade 3 transaminitis did not constitute a DLT. There were no DLTs in the six patients evaluated at the first two dose levels of 600 and 900 microg/m2. Reversible grade 4 transaminitis occurred in two of nine patients after treatment with the first cycle of therapy at the third dose level of 1200 microg/m2. Another patient experienced grade 4 rhabdomyolysis, renal failure requiring hemodialysis, grade 4 neutropenia, and grade 3 thrombocytopenia during the second cycle of therapy with this dose. The maximum tolerated dose was 1200 microg/m2, and an additional six patients were enrolled at an intermediate dose level of 1050 microg/m2. This well-tolerated dose was established as the recommended Phase II dose. The disposition of ET-743 was distinctly biexponential, and a departure from linear pharmacokinetic behavior was evident at the 1200-microg/m2 dose level. Pharmacokinetic parameters determined at 1050 microg/m2 were (mean +/- SD): maximum plasma concentration, 318 +/- 147 pg/ml; initial disposition phase half-life, 9.0 +/- 10.3 min; terminal phase half-life, 69.0 +/- 56.7 h; and total plasma clearance, 28.4 +/- 22.5 liters/h/m2. Prolonged systemic exposure to concentrations of the agent that are cytotoxic in vitro were achieved. Toxicity of the drug is clearly schedule-dependent, because increasing the duration of infusion from 3 or 24 h to 72 h results in decreased myelosuppression and comparable hepatotoxicity. Although there were no objective responses to therapy, clear evidence of antitumor activity was observed in a patient with epithelioid mesothelioma, as confirmed by positron emission tomography studies. A Phase II trial to assess the efficacy of ET-743 against this highly refractory neoplasm has been initiated on the basis of this observation. The therapeutically optimal administration schedule remains to be established, inasmuch as there have been indications of activity against a variety of tumors during Phase I studies when the drug was infused over times ranging from 1 to 72 h. Characterizing the pharmacokinetics of ET-743 during the course of Phase II trials and Phase I combination studies is recommended to assure that this promising new anticancer drug can be used with an acceptable margin of safety.

Adult↗
PubMed2001

Infection in total knee replacement: a retrospective review of 6489 total knee replacements.

Six thousand four hundred eighty-nine knee replacements were done in 6120 patients at the authors' institution between 1993 and 1999. Operations were done in a theater with vertical laminar flow and with the surgical team using body exhaust suits. Of these knee replacements, 116 knees became infected and 113 were available for followup. One hundred of the infections occurred in patients undergoing primary knee replacement, whereas the remaining infections occurred in patients undergoing revision knee replacement. Ninety-seven of these knees (86%) had deep periprosthetic infections and the remaining 16 knees had superficial wound infections. One third of the deep infections occurred within the first 3 months after surgery and the remaining 2/3 occurred after 3 months. The overall early deep infection rate for patients undergoing a primary knee replacement was 0.39%, whereas the rate for patients undergoing a revision knee replacement was 0.97%. A cohort of noninfected knee replacements from patients matched for gender, age, and month of surgery was used as a control group. Those comorbidities that were statistically significant in increasing the risk of infection were prior open surgical procedures, immunosuppressive therapy, poor nutrition, hypokalemia, diabetes mellitus, obesity, and a history of smoking. Patients undergoing revision procedures had a statistically higher risk of infection than did patients undergoing primary surgeries. If the surgery took longer than 2.5 hours, the risk of infection was increased significantly. There was no change in the infection rate when the perioperative antibiotic prophylaxis was decreased from 48 to 24 hours after surgery. The predominant infectious organisms were gram-positive (Staphylococcus aureus, Staphylococcus epidermidis, and Streptococcus Group B). Twenty percent of the knees that were infected clinically had no organisms that could be identified. In each case, the patient had been treated empirically at another institution with antibiotics before a culture of the joint was obtained.

Comorbidity↗
PubMed2000

Consensus statement on the live organ donor.

OBJECTIVE: To recommend practice guidelines for transplant physicians, primary care providers, health care planners, and all those who are concerned about the well-being of the live organ donor. PARTICIPANTS: An executive group representing the National Kidney Foundation, and the American Societies of Transplantation, Transplant Surgeons, and Nephrology formed a steering committee of 12 members to evaluate current practices of living donor transplantation of the kidney, pancreas, liver, intestine, and lung. The steering committee subsequently assembled more than 100 representatives of the transplant community (physicians, nurses, ethicists, psychologists, lawyers, scientists, social workers, transplant recipients, and living donors) at a national conference held June 1-2, 2000, in Kansas City, Mo. CONSENSUS PROCESS: Attendees participated in 7 assigned work groups. Three were organ specific (lung, liver, and kidney) and 4 were focused on social and ethical concerns (informed consent, donor source, psychosocial issues, and live organ donor registry). Work groups' deliberations were structured by a series of questions developed by the steering committee. Each work group presented its deliberations to an open plenary session of all attendees. This information was stored and shaped into a statement circulated electronically to all attendees for their comments, and finally approved by the steering committee for publication. The term consensus is not meant to convey universal agreement of the participants. The statement identifies issues of controversy; however, the wording of the entire statement is a consensus by approval of all attendees. CONCLUSION: The person who gives consent to be a live organ donor should be competent, willing to donate, free from coercion, medically and psychosocially suitable, fully informed of the risks and benefits as a donor, and fully informed of the risks, benefits, and alternative treatment available to the recipient. The benefits to both donor and recipient must outweigh the risks associated with the donation and transplantation of the living donor organ.

Health Status↗
PubMed2000

Effect of community-based interventions on high-risk drinking and alcohol-related injuries.

CONTEXT: High-risk alcohol consumption patterns, such as binge drinking and drinking before driving, and underage drinking may be linked to traffic crashes and violent assaults in community settings. OBJECTIVES: To determine the effect of community-based environmental interventions in reducing the rate of high-risk drinking and alcohol-related motor vehicle injuries and assaults. DESIGN AND SETTING: A longitudinal multiple time series of 3 matched intervention communities (northern California, southern California, and South Carolina) conducted from April 1992 to December 1996. Outcomes were assessed by 120 general population telephone surveys per month of randomly selected individuals in the intervention and comparison sites, traffic data on motor vehicle crashes, and emergency department surveys in 1 intervention-comparison pair and 1 additional intervention site. INTERVENTIONS: Mobilize the community; encourage responsible beverage service; reduce underage drinking by limiting access to alcohol; increase local enforcement of drinking and driving laws; and limit access to alcohol by using zoning. MAIN OUTCOME MEASURES: Self-reported alcohol consumption and driving after drinking; rates of alcohol-related crashes and assault injuries observed in emergency departments and admitted to hospitals. RESULTS: Population surveys revealed that the self-reported amount of alcohol consumed per drinking occasion declined 6% from 1.37 to 1. 29 drinks. Self-reported rate of "having had too much to drink" declined 49% from 0.43 to 0.22 times per 6-month period. Self-reported driving when "over the legal limit" was 51% lower (0. 77 vs 0.38 times) per 6-month period in the intervention communities relative to the comparison communities. Traffic data revealed that, in the intervention vs comparison communities, nighttime injury crashes declined by 10% and crashes in which the driver had been drinking declined by 6%. Assault injuries observed in emergency departments declined by 43% in the intervention communities vs the comparison communities, and all hospitalized assault injuries declined by 2%. CONCLUSION: A coordinated, comprehensive, community-based intervention can reduce high-risk alcohol consumption and alcohol-related injuries resulting from motor vehicle crashes and assaults. JAMA. 2000;284:2341-2347.

Accidents, Traffic↗
PubMed2000

Inhibitors of tyrosine phosphatases block angiotensin II inhibition of Na(+) pump.

To determine how angiotensin II inhibits the Na(+) pump (Na(+), K(+)-ATPase) in rat zona glomerulosa, we selectively blocked signaling proteins that could be activated by the angiotensin AT(1) receptor and known to affect Na(+) pump activity. Inhibitors of protein kinase C [calphostin C (1 microM); staurosporine (1 microM)], phospholipase A(2) [arachidonyl triflouromethyl ketone (25 microM); quinacrine (75 microM)], diacylgycerol lipase [RHC-80267 (5 microM)], and tyrosine phosphorylation [tyrphostin 47 (100 microM)] had no effect on angiotensin II inhibition of the Na(+) pump. On the other hand, inhibitors of tyrosine phosphatases [phenylarsine oxide (5 microM) and 4-bromotetramisole oxalate (100 microM)] blocked angiotensin II inhibition, where as inhibitors of serine/threonine phosphatases [okadaic acid (1 microM) and microcystin (1.5 microM)] did not. Thus, angiotensin II inhibition of the Na(+) pump may in part be mediated by a tyrosine phosphatase.

Angiotensin II↗