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Biomedical subjects

P Davidson

Publications and source records attributed to P Davidson.

At least 37 records · Page 2Linked to original sources

Quality use of medicines (QUM) in critical care: an imperative for best practice.

Quality use of medicines (QUM) as a discrete concept is gaining increasing importance in Australia and is supported by a policy platform which has federal government and health professional support. The QUM movement is also supported by a strong consumer base and this lobby group has been responsible for endorsement as a major health initiative. However, the importance of QUM to achievement of optimal patient outcomes has not achieved sufficient recognition in the critical care literature. Implicit in the discussion of QUM is the rational, ethical, safe and effective use of drugs within a best practice framework. Successful implementation of QUM requires appropriate infrastructure and the commitment and cooperation of medical, nursing and pharmacy staff. Support, education and training provide the prerequisites of knowledge, skills and awareness for quality use of medicines for all groups. An emphasis upon evidence based practice and the prevalence of polypharmacy in contemporary health care systems requires examination of factors that are barriers to best practice. QUM in critical care areas requires appropriately skilled staff who are competent to manage patients with a wide range of selected drugs, often in highly stressful situations. In many situations in critical care, the role of the critical care nurse is one of patient advocate. It is important to note that the delivery of critical care is not limited to a discrete setting and is inclusive of management at the trauma scene, assessment and delivery of care in the emergency department, through to intensive, coronary care and high dependency units. This paper presents a discussion of the concept of QUM and its relevance in the critical care context. Key theoretical, policy and research considerations for establishment of QUM in critical care are reviewed and discussed. This paper seeks to describe key issues in QUM and endorse the need for a research agenda in critical care.

Australia↗

Effect of sucrose/raffinose mass ratios on the stability of co-lyophilized protein during storage above the Tg.

PURPOSE: To examine the potential of raffinose as an excipient in stabilizing protein and to study the effect of sucrose/raffinose mass ratios on the stability of co-lyophilized protein and amorphous solids during storage at an elevated temperature. METHODS: Glucose-6-phosphate dehydrogenase (G6PDH) was colyophilized with sucrose and raffinose mixed at different mass ratios. The activity of dried G6PDH was monitored during storage at 44 degrees C. Thermal properties of sucrose/raffinose matrices were determined by differential scanning calorimetry (DSC). RESULTS: Mass ratios of sucrose to raffinose did not affect the recovery of G6PDH activity after freeze-drying, but significantly affected the stability of freeze-dried G6PDH during storage. The sucrose-alone formulation offered the best enzyme stabilization during storage. With increasing fraction of raffinose, the G6PDH stability decreased, sugar crystallization inhibited, and crystal-melting temperature increased. CONCLUSIONS: Despite the higher Tg of the formulations with higher fraction of raffinose, they provided less protection for G6PDH than did sucrose alone during storage. Our data do not support the prediction from recent thermophysical studies that raffinose should be superior to sucrose and trehalose as a potential excipient or stabilizer.

Drug Stability↗

Addressing the burden of heart failure in Australia: the scope for home-based interventions.

The growing burden of heart failure (HF) challenges health practitioners to implement and evaluate models of care to facilitate optimal health related outcomes. Australia supports a publicly funded universal health insurance system with a strong emphasis on primary care provided by general practitioners. The burden of chronic HF, and a social and political framework favoring community-based, noninstitutionalized care, represents an ideal environment in which home-based HF programs can be implemented successfully. Cardiovascular nurses are well positioned to champion and mentor implementation of evidence-based, patient-centered programs in Australian communities. This paper describes the facilitators and barriers to implementation of best practice models in the Australian context. These include the challenge of providing care in a diverse, multicultural society and the need for clinical governance structures to ensure equal access to the most effective models of care.

Aged↗

Implications for tobacco control of the multistate tobacco settlement.

The 1998 master settlement agreement between major tobacco manufacturers and the US states will have a profound effect on many tobacco industry practices and will significantly influence future settlements with the tobacco industry. This article analyzes the settlement's key provisions pertaining to youth sales, advertising, marketing, and lobbying. It also examines the ways in which the settlement restricts industry practices as well as the many industry practices that remain unregulated.

Health Planning↗

Intussusception of the vermiform appendix: preoperative colonoscopic diagnosis of two cases and review of the literature.

Intussusception of the appendix is an uncommon condition, and the diagnosis is rarely made preoperatively. Making an accurate diagnosis before laparotomy is important in providing the optimal treatment for the patient. We present the clinical and endoscopic features of two cases of intussusception of the appendix and review the literature. Diagnosis was made preoperatively by colonoscopy in these cases and an elective appendectomy was performed. Appendiceal intussusception should be considered in the differential diagnosis of abdominal pain. Colonoscopy can be a valuable tool in establishing this diagnosis and in selecting the appropriate management.

Abdominal Pain↗

Women recovering from first-time myocardial infarction (MI): a feminist qualitative study.

Although myocardial infarction (MI) is a leading cause of death and disablement for women internationally, little is known about women's recovery. This paper describes an exploratory descriptive study that was informed by feminist principles, and which aimed to explore the recovery experiences of a group of women survivors of first-time MI in the initial period following discharge from hospital. A total of 10 female survivors were interviewed using an open-ended semi-structured interview schedule administered at 7, 14 and 21 days post-hospital discharge. Findings revealed that recovery was experienced as a complex process, initially characterized by fear and uncertainty. Over the duration of the study these feelings were replaced with a more positive outlook, a return of energy, and a sense of confidence in the future. Participants identified an unmet need for reliable information which persisted over the duration of the study. The findings of this study have implications for nursing practice and research. Chief among these is the issue of effective provision of information to women following an acute MI. The importance of providing relevant information to be understood and retained by people experiencing crisis cannot be overstated. Equally important are the provision of opportunities for patients to have regular contact with health professionals to question and seek clarifying information. These findings should now be tested on larger populations.

Adaptation, Psychological↗

A population-based survey of tuberculosis symptoms: how atypical are atypical presentations?

There is scant information on tuberculosis symptoms from a population-based perspective. We prospectively identified 526 tuberculosis cases reported in Los Angeles County over a 6-month period. Of 313 persons who completed our questionnaire, 72.7% had cough, 48.2% for >2 weeks, and 52.3% had fever, 29.4% for >2 weeks. Among those with pulmonary disease, only 52.4% had cough for >2 weeks. In a multivariate model, persons with significant symptoms typical of tuberculosis disease (defined as cough or fever for >2 weeks, weight loss, or hemoptysis) were associated with lack of medical insurance, negative tuberculin skin test, diagnosis during a process other than screening, and non-Asian race. In summary, classic symptoms of prolonged cough and fever are insensitive predictors of tuberculosis. Our data suggest that Asians may need to be added to the list of persons who present with tuberculosis atypically. We believe that the Infectious Diseases Society of America guidelines for community-acquired pneumonia should emphasize demographic features in addition to clinical symptoms when suggesting which patients require evaluation for Mycobacterium tuberculosis.

Adult↗

Demographics of dumping. II: A national environmental equity survey and the distribution of hazardous materials handlers.

Using a national survey of facilities governed by the Resource Conservation and Recovery Act (RCRA), we examine the sociospatial distribution of a much larger group of hazardous materials handlers than did previous environmental equity studies. Overall we find that RCRA-governed facilities are more likely to be sited in working-class neighborhoods with lower percentages of minority residents. We do not find evidence of stark environmental inequities. RCRA facilities, however, are close to neighborhoods with a higher percentage of minority residents. And in nonmetropolitan areas, they are slightly more likely to be located in neighborhoods with a higher percentage of black residents.

Black or African American↗

Health status, perceptions of coping, and social support immediately after discharge of survivors of acute myocardial infarction.

BACKGROUND: The period immediately after discharge from the hospital after an acute myocardial infarction is a stressful and vulnerable time about which little is known. OBJECTIVE: To explore health status, perceptions of coping, and social support among survivors of a recent myocardial infarction in the first 3 weeks after discharge from hospitals in southwestern Sydney, Australia. METHODS: A descriptive, exploratory approach with a triangulated methodology was used to assess the experiences of 38 survivors, detect patterns in these experiences, explore the health-support needs of survivors, and determine changes in health status in the first 3 weeks after discharge. Quantitative data were collected with the Medical Outcomes Study SF-36, New York Heart Association classification, Canadian Cardiovascular Society Angina Scale, and the Jalowiec Coping Scale. A semistructured interview schedule provided additional qualitative data about the experiences of the survivors. RESULTS: The health status of participants was relatively stable during the 3-week period; most had no activity limitation due to dyspnea or angina. However, the subjects' health status was considerably lower than that of their age-matched population. The most common and most effective coping strategies adopted during this period were confrontation, optimism, and self-reliance. In addition, the subjects experienced anxiety, depression, ambiguity and uncertainty, fear of recurrence of the infarction and of deterioration in health, of boredom and of inertia. CONCLUSION: These findings can help nurses in hospital and community settings assist survivors of acute myocardial infarction to prepare for and deal effectively with experiences during convalescence.

Adaptation, Psychological↗

Can pleural effusions cause cardiac tamponade?

Pleural effusion(s) can increase the pressure of an otherwise insignificant pericardial effusion to a degree that can result in cardiac tamponade. The case histories presented here illustrate the importance of recognizing this phenomenon and altering our treatment algorithm to drain the pleural effusions instead of the pericardial collections.

Aged↗

Complete sequence of the IncPbeta plasmid R751: implications for evolution and organisation of the IncP backbone.

The broad host range IncP plasmids are of particular interest because of their ability to promote gene spread between diverse bacterial species. To facilitate study of these plasmids we have compiled the complete sequence of the IncPbeta plasmid R751. Comparison with the sequence of the IncPalpha plasmids confirms the conservation of the IncP backbone of replication, conjugative transfer and stable inheritance functions between the two branches of this family. As in the IncPalpha genome the DNA of this backbone appears to have been enriched for the GCCG/CGGC motifs characteristic of the genome of organisms with a high G+C content, such as P. aeruginosa, suggesting that IncPbeta plasmids have been subjected during their evolution to similar mutational and selective forces as IncPalpha plasmids and may have evolved in pseudomonad hosts. The IncP genome is consistently interrupted by insertion of phenotypic markers and/or transposable elements between oriV and trfA and between the tra and trb operons. The R751 genome reveals a family of repeated sequences in these regions which may form the basis of a hot spot for insertion of foreign DNA. Sequence analysis of the cryptic transposon Tn4321 revealed that it is not a member of the Tn21 family as we had proposed previously from an inspection of its ends. Rather it is a composite transposon defined by inverted repeats of a 1347 bp IS element belonging to a recently discovered family which is distributed throughout the prokaryotes. The central unique region of Tn4321 encodes two predicted proteins, one of which is a regulatory protein while the other is presumably responsible for an as yet unidentified phenotype. The most striking feature of the IncPalpha plasmids, the global regulation of replication and transfer by the KorA and KorB proteins encoded in the central control operon, is conserved between the two plasmids although there appear to be significant differences in the specificity of repressor-operator interactions. The importance of these global regulatory circuits is emphasised by the observation that the operator sequences for KorB are highly conserved even in contexts where the surrounding region, either a protein coding or intergenic sequence, has diverged considerably. There appears to be no equivalent of the parABCDE region which in the IncPalpha plasmids provides multimer resolution, lethality to plasmid-free segregants and active partitioning functions. However, we found that the continuous sector from co-ordinate 0 to 9100 bp, encoding the co-regulated klc and kle operons as well as the central control region, could confer a high degree of segregational stability on a low copy number test vector. Thus R751 appears to exhibit very clearly what was first revealed by study of the IncPalpha plasmids, namely a fully functional co-ordinately regulated set of replication, transfer and stable inheritance functions.

Amino Acid Sequence↗

Protein inactivation in amorphous sucrose and trehalose matrices: effects of phase separation and crystallization.

Trehalose is the most effective carbohydrate in preserving the structure and function of biological systems during dehydration and subsequent storage. We have studied the kinetics of protein inactivation in amorphous glucose/sucrose (1:10, w/w) and glucose/trehalose (1:10, w/w) systems, and examined the relationship between protein preservation, phase separation and crystallization during dry storage. The glucose/trehalose system preserved glucose-6-phosphate dehydrogenase better than did the glucose/sucrose system with the same glass transition temperature (Tg). The Williams-Landel-Ferry kinetic analysis indicated that the superiority of the glucose/trehalose system over the glucose/sucrose system was possibly associated with a low free volume and a low free volume expansion at temperatures above the Tg. Phase separation and crystallization during storage were studied using differential scanning calorimetry, and three separate domains were identified in stored samples (i.e., sugar crystals, glucose-rich and disaccharide-rich amorphous domains). Phase separation and crystallization were significantly retarded in the glucose/trehalose system. Our data suggest that the superior stability of the trehalose system is associated with several properties of the trehalose glass, including low free volume, restricted molecular mobility and the ability to resist phase separation and crystallization during storage.

Chemical Phenomena↗

Protein stability in the amorphous carbohydrate matrix: relevance to anhydrobiosis.

The formation of intracellular glass is proposed to be relevant to protein stabilization and survival of anhydrobiotic organisms in the dry state. The stability of proteins in the amorphous carbohydrate matrix and its relevance to seed survival have been investigated in the present study. Glucose-6-phosphate dehydrogenase (G6PDH) was preserved in the amorphous glucose/sucrose (1:10, w/w) matrix by freeze-drying. The stability of freeze-dried G6PDH was examined at temperatures above and below the glass transition temperature (Tg). The rate of G6PDH inactivation in the amorphous carbohydrate matrix deviated significantly from the Arrhenius kinetics, and conformed to the Williams-Landel-Ferry (WLF) relationship. The temperature dependence of G6PDH inactivation in two sets of samples with different Tg values was compared. Identical temperature dependence of G6PDH inactivation was observed after temperature normalization by (T-Tg). Seed survival of Vigna radiata Wilczek (mung bean) showed a similar WLF kinetics at storage temperatures T > or = Tg. In situ protein stability in mung bean embryonic axes was studied using differential scanning calorimetry (DSC). Thermal stability of seed proteins exhibited a strong dependence on the Tg of intracellular glass. These results indicate an important role of the glassy state in protein stabilization. Our data suggest an association between protein stability in intracellular glass and seed survival during storage.

Calorimetry, Differential Scanning↗

The influence of polymer molecular weight in lamellar gels based on PEG-lipids.

We report x-ray scattering, rheological, and freeze-fracture and polarizing microscopy studies of a liquid crystalline hydrogel called Lalpha,g. The hydrogel, found in DMPC, pentanol, water, and PEG-DMPE mixtures, differs from traditional hydrogels, which require high MW polymer, are disordered, and gel only at polymer concentrations exceeding an "overlap" concentration. In contrast, the Lalpha,g uses very low-molecular-weight polymer-lipids (1212, 2689, and 5817 g/mole), shows lamellar order, and requires a lower PEG-DMPE concentration to gel as water concentration increases. Significantly, the Lalpha,g contains fluid membranes, unlike Lbeta' gels, which gel via chain ordering. A recent model of gelation in Lalpha phases predicts that polymer-lipids both promote and stabilize defects; these defects, resisting shear in all directions, then produce elasticity. We compare our observations to this model, with particular attention to the dependence of gelation on the PEG MW used. We also use x-ray lineshape analysis of scattering from samples spanning the fluid-gel transition to obtain the elasticity coefficients kappa and B; this analysis demonstrates that although B in particular depends strongly on PEG-DMPE concentration, gelation is uncorrelated to changes in membrane elasticity.

Biophysical Phenomena↗

Phenotypic characterisation of the dendritic cell infiltrate in prostate cancer.

PURPOSE: To investigate whether dendritic cells (DC), which as professional antigen presenting cells have the capacity to stimulate immune responses against tumour associated antigens, are recruited into and activated within prostate cancer. MATERIALS AND METHODS: Immunoenzyme and immunofluorescence labelling was used to identify leucocyte and DC subsets within 15 cases of prostate cancer. Cell numbers were compared with numbers in adjacent normal prostatic tissue. Total DC numbers were identified as CD45+ leucocytes not coexpressing any lineage specific markers. The Langerhans cell (LC) subset was detected using anti CD1a staining and activated DC were identified by their expression of either CD83, CD86 or CMRF44. RESULTS: DC were found to represent a small subset of leucocytes present in both benign and malignant prostatic tissue. Statistically there were significantly less DC and LC in prostate cancer compared with normal prostatic tissue. While only a small subset of DC expressed markers of activation in prostate cancer, this was significantly more than the virtual absence of activated DC in normal prostatic tissue. CONCLUSIONS: This is the first time that DC have been studied in prostate cancer using the relatively new DC specific monoclonal antibodies CD83 and CMRF-44. These findings suggest that there is no active recruitment of DC into prostate cancer and those DC present are only minimally activated.

Antigens, CD↗