Biomedical subjects
Publications and source records attributed to S L Lewis.
The haematological complications of acquired copper deficiency have been well documented, but the neurological complications have only recently been reported. An illustrative case of copper deficiency myeloneuropathy with pancytopenia is presented and the potential aetiologies and neurological manifestations of this deficiency state discussed.
Several widespread changes in the ecology of old-growth tropical forests have recently been documented for the late twentieth century, in particular an increase in stem turnover (pan-tropical), and an increase in above-ground biomass (neotropical). Whether these changes are synchronous and whether changes in growth are also occurring is not known. We analysed stand-level changes within 50 long-term monitoring plots from across South America spanning 1971-2002. We show that: (i) basal area (BA: sum of the cross-sectional areas of all trees in a plot) increased significantly over time (by 0.10 +/- 0.04 m2 ha(-1) yr(-1), mean +/- 95% CI); as did both (ii) stand-level BA growth rates (sum of the increments of BA of surviving trees and BA of new trees that recruited into a plot); and (iii) stand-level BA mortality rates (sum of the cross-sectional areas of all trees that died in a plot). Similar patterns were observed on a per-stem basis: (i) stem density (number of stems per hectare; 1 hectare is 10(4) m2) increased significantly over time (0.94 +/- 0.63 stems ha(-1) yr(-1)); as did both (ii) stem recruitment rates; and (iii) stem mortality rates. In relative terms, the pools of BA and stem density increased by 0.38 +/- 0.15% and 0.18 +/- 0.12% yr(-1), respectively. The fluxes into and out of these pools-stand-level BA growth, stand-level BA mortality, stem recruitment and stem mortality rates-increased, in relative terms, by an order of magnitude more. The gain terms (BA growth, stem recruitment) consistently exceeded the loss terms (BA loss, stem mortality) throughout the period, suggesting that whatever process is driving these changes was already acting before the plot network was established. Large long-term increases in stand-level BA growth and simultaneous increases in stand BA and stem density imply a continent-wide increase in resource availability which is increasing net primary productivity and altering forest dynamics. Continent-wide changes in incoming solar radiation, and increases in atmospheric concentrations of CO2 and air temperatures may have increased resource supply over recent decades, thus causing accelerated growth and increased dynamism across the world's largest tract of tropical forest.
Previous work has shown that tree turnover, tree biomass and large liana densities have increased in mature tropical forest plots in the late twentieth century. These results point to a concerted shift in forest ecological processes that may already be having significant impacts on terrestrial carbon stocks, fluxes and biodiversity. However, the findings have proved controversial, partly because a rather limited number of permanent plots have been monitored for rather short periods. The aim of this paper is to characterize regional-scale patterns of 'tree turnover' (the rate with which trees die and recruit into a population) by using improved datasets now available for Amazonia that span the past 25 years. Specifically, we assess whether concerted changes in turnover are occurring, and if so whether they are general throughout the Amazon or restricted to one region or environmental zone. In addition, we ask whether they are driven by changes in recruitment, mortality or both. We find that: (i) trees 10 cm or more in diameter recruit and die twice as fast on the richer soils of southern and western Amazonia than on the poorer soils of eastern and central Amazonia; (ii) turnover rates have increased throughout Amazonia over the past two decades; (iii) mortality and recruitment rates have both increased significantly in every region and environmental zone, with the exception of mortality in eastern Amazonia; (iv) recruitment rates have consistently exceeded mortality rates; (v) absolute increases in recruitment and mortality rates are greatest in western Amazonian sites; and (vi) mortality appears to be lagging recruitment at regional scales. These spatial patterns and temporal trends are not caused by obvious artefacts in the data or the analyses. The trends cannot be directly driven by a mortality driver (such as increased drought or fragmentation-related death) because the biomass in these forests has simultaneously increased. Our findings therefore indicate that long-acting and widespread environmental changes are stimulating the growth and productivity of Amazon forests.
The purpose of this study was to identify and prioritize research topics of importance for nephrology nursing and the American Nephrology Nurses' Association (ANNA). This was an explorative survey design using the Delphi technique. Nephrology nurses who are members of ANNA participated in the study. In Round 1 participants included 90 members of the Advanced Practice Special Interest Group. Round 2 participants were 537 nephrology nurses who attended the 28th ANNA National Symposium. Participants in Round 3 were 491 ANNA members who had at least a master's degree in nursing or another field. A three-round Delphi technique was used to solicit, identify, and prioritize problems for nephrology nursing research. In Round 1, 90 nurses identified problems in response to an open-ended question. These responses were analyzed and categorized into a 21-item research survey that was used for subsequent rounds. Round 2 participants rated each research question/topic on the survey on a 1 to 5 scale for level of importance. In addition, they were asked to identify the top-ranked research priorities from the 21 questions. In Round 3, the participants were asked to do the same as in Round 2. In addition, they indicated whether the research priority was primarily a nursing responsibility or a collaborative effort with other health care personnel. Based on 3 rounds of the Delphi study and analysis of both level of importance and rated-research priority, the five areas that were identified as research priorities are (a) nursing interventions to prevent vascular access infections, (b) nursing interventions to maintain vascular access patency, (c) educational needs of patients and families, (d) levels of nursing competence and the effect on patient outcomes, and (e) validation of nursing interventions to achieve patient outcomes. These research priorities provide direction for nephrology nursing research and the ANNA. This Delphi study represents a significant step for ANNA in its commitment to research.
The pathophysiology of transient global amnesia (TGA) has been obscure since the definition of this syndrome more than 30 years ago. Current hypotheses include migraine, seizure, or transient cerebral arterial ischaemia. However, none of these potential mechanisms explain both the absence of other neurological signs or symptoms during TGA, and its frequent precipitating activities: many of which would be expected to result in marked increases in venous return from the arms to the superior vena cava. Patients with TGA also commonly have a Valsalva manoeuvre at the onset of attacks. I suggest that a Valsalva manoeuvre, blocking venous return through the superior vena cava, may allow brief retrograde transmission of high venous pressure from the arms to the cerebral venous system, resulting in venous ischaemia to the diencephalon or mesial temporal lobes and to TGA.
OBJECTIVE: The purpose of this study was to determine nephrology nurses' perceptions of barriers to research utilization and to identify effective ways to facilitate integration of research findings in nephrology nurses' practice. DESIGN: This was an explorative, descriptive study. SAMPLE/SETTING: Four hundred ninety-eight nephrology nurses participated in the study. The primary areas of clinical practice were hemodialysis (36%), peritoneal dialysis (29%), transplantation (15%), pediatric nephrology (3%), or various combinations (18%). METHODS: Participants completed a demographic data form and the previously validated instrument, Barriers and Facilitators to Using Research in Practice. Descriptive statistics were used to analyze the data. RESULTS: The majority of respondents (52%) were staff nurses. The other respondents included 30% in management, 12% in advanced practice roles, and 6% in education. The barriers to research utilization most frequently identified were insufficient time on the job to implement new ideas and not enough time to read research. The most effective facilitators identified were increased administrative support and encouragement, increased time available for reviewing and implementing research findings, and improved understandability of research reports. CONCLUSIONS: Additional nursing and nonnursing administrative support for research activities and designated time to read research and implement research-based clinical practices may facilitate the development of research-based nephrology nursing practice.
A review of factors contributing to early mortality after cardiac transplantation revealed that up to 25% of deaths were due to primary graft dysfunction unrelated to rejection or infection. In light of this finding, evaluation of a donor heart with regard to its suitability for transplantation takes on added importance. In an effort to screen the suitability of donor hearts in the region covered by the Northwest Organ Procurement Agency (USA), all donors are evaluated by two-dimensional transthoracic echocardiography as part of the initial evaluation. A total of 110 donor echocardiograms were reviewed and an attempt was made to correlate the 30-day outcome with the parameters measured. An unexpected finding was that the presence of left ventricular hypertrophy in the donor heart was associated with an increase in the incidence of donor heart dysfunction compared with donors with normal echocardiographic profiles (33% vs 3%, P = 0.007).
Previous studies of changes in immune function in platelet donors have investigated subjects who were undergoing plateletpheresis using older equipment that is no longer in general use. Therefore, the purpose of this study was to determine the effect of long-term platelet donation on lymphocyte numbers and subsets and plasma protein concentrations in platelet donors using newer cell separators. Three groups included in the study were nondonor controls (n = 27), long-term whole blood donors (n = 29), and long-term platelet donors (n = 20). Using a cross-sectional analysis, lymphocyte numbers and subsets were determined and compared among the three groups. Plasma concentrations of total protein, globulin, albumin, and IgG were also compared. Among the three groups there were no significant differences in total white blood cell counts, percentage or absolute number of lymphocytes, or percentage or absolute number of lymphocyte subsets. Serum total protein, globulin, albumin, and IgG concentrations of platelet donors were within normal ranges. These data support the current Food and Drug Administration (FDA) and American Association of Blood Banks' standards for the frequency of platelet donation allowed and monitoring required for plateletpheresis donors. Furthermore, these data indicate that the FDA could eliminate the requirement for the warning in informed consents about lymphocyte depletion in platelet donors.
Patients with acute renal failure are at high risk for developing malnutrition. Provision of adequate nutrition support begins with an understanding of the metabolic alterations that occur due to the disease state and renal replacement therapies. Assessment of nutritional requirements and implementation of appropriate feeding modalities can lead to optimal nutritional status and positive patient outcomes. Building collaborative relationships with other health care professionals is crucial to overcoming the barriers that hinder implementation of appropriate nutritional management.
Lung transplantation has recently offered hope for prolonged survival in patients with cystic fibrosis. Patients with cystic fibrosis have a 7% prevalence of associated liver disease and portal hypertension. These patients have been previously excluded from consideration for lung transplantation. The natural history of cystic fibrosis-associated liver disease suggests a benign and protracted course in most cases. At the University of Washington, 14 of 53 patients (26%) have undergone lung transplantation for cystic fibrosis-related respiratory failure. We report the outcome of double lung transplantation in four of these 14 patients who also had cystic fibrosis-associated liver disease and portal hypertension, all of whom were symptom free from their liver disease. All four patients are alive and well without complications 4 to 31 months after transplantation. We conclude that the presence of cystic fibrosis-associated liver disease with portal hypertension, in the setting of good synthetic function (albumin > 3.0 gm/L and normal prothrombin time), normal serum bilirubin, minimal varices, without ascites or encephalopathy, should not be an absolute contraindication to lung transplantation. We recommend that other transplantation centers also include this patient population in consideration for lung transplantation.
The immunomodulating effects of repeated exposure to blood from multiple donors coupled with an immature immune system may predispose the preterm neonate to an increased incidence of infection in his first few months of life. To test this hypothesis, we compared lymphocyte phenotypes, serum IgG concentrations, and histories of infection and rehospitalization in neonates at 4 months corrected age. Two of the study groups were preterm infants who had been transfused with either frozen, deglycerolized or CMV-negative, gamma-irradiated blood. Control groups consisted of nontransfused term and preterm infants. There were no differences found in lymphocyte phenotypes or serum IgG concentrations of controls or transfused infants. No differences were found in the infection or rehospitalization incidence in the transfused infants as compared with nontransfused preterm neonates. We failed to show differences in immune parameters or in infection and rehospitalization rates of the preterm infants analysed. Alongside previously published reports, our data suggest that red cell transfusions have a minimal impact on the immature immune system of the neonate.
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In this article, the authors examine the spectrum of HIV disease as it affects parents and their children from the initial diagnosis through the progression of the disease. The psychosocial factors affecting access to health care, family relationships, and issues of loss are focused on. Practitioner guidelines for assisting families to deal with the psychosocial challenges presented by HIV infection are provided.
OBJECTIVE: The purpose of the study was to obtain information from nephrology nurses on existing policies and protocols related to peritoneal catheter exit site care and treatment of exit site infections. DESIGN: This was an explorative, descriptive study. SAMPLE/SETTING: Fifty-four nurses who attended the 1995 Consensus Conference on Peritoneal Dialysis at the 26th Annual American Nephrology Nurses' Association National Symposium completed a survey questionnaire on exit site care and management of exit site infections. METHODS: A survey was mailed to nephrology nurses preregistered to attend the 1995 ANNA Consensus Conference related to peritoneal dialysis at the 26th National Symposium. Surveys were also collected at the meeting. RESULTS: Hydrogen peroxide and povidone iodine are frequently used in the nursing care of both healing and chronic exit sites. Almost all of the dialysis units require patients to stabilize or secure the catheter. The majority of respondents had a standardized method of assessing exit sites. Risk factors for exit site infections are presented for both the immediate post-catheter insertion period and the well-healed exit site. There were many different combinations of cleansing agents used to treat inflamed and infected exit sites. CONCLUSIONS: Procedures for exit site care vary widely. Prospective, randomized studies of exit site care protocols and cleansing agents are necessary to determine the most effective procedures to promote healthy exit sites.
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BACKGROUND: The possible effects of long-term plasma donation remain unknown, but it is important to investigate them so that donor safety is ensured. The purpose of this study was to determine if long-term plasma donation alters plasma proteins or lymphocyte phenotypes. STUDY DESIGN AND METHODS: Two groups of long-term plasma donors, source plasma donors (n = 20) and Rh immune globulin plasma donors (n = 26), were compared with whole blood donors (n = 29) and nondonor controls (n = 30). Blood samples were obtained prior to donation. Serum protein, albumin, globulin, and immunoglobulin levels were determined. In an assay using whole blood, lymphocyte phenotypes were characterized with a panel of single- and dual-labeled monoclonal antibodies and subsequent analysis by flow cytometry. RESULTS: As compared to the nondonor controls and/or whole blood donors, the mean values for serum protein, globulin, and IgG levels were lower in both plasma donor groups, with a significant negative correlation between donation frequency and serum protein values for the source plasma donors. Albumin levels were within normal ranges for both groups of plasma donors. No significant differences existed among the donor groups in total white cell counts, the percentage or absolute number of lymphocytes, T (CD3) cells, or helper T (CD4) cells. However, there were increased percentages of B (CD19) cells and decreased percentages of suppressor T (CD8+/CD11b+) cells and natural killer cells in both groups of plasma donors as compared to nondonor controls. CONCLUSION: Many plasma donors have low levels of serum protein, globulin, and IgG. In addition, they have increased percentages of B cells and decreased percentages of suppressor T and natural killer cells. The clinical significance of these findings warrants further investigation.
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