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Barrett C. Demonstrations of Physical Signs in Clinical Surgery. West J Med 2009. [DOI: 10.1136/bmj.a2992] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Barrett C, Rodrigues D, Bradey N, Strachan R. Intracranial metastasis masquerading as acute subdural haematoma. Br J Neurosurg 2008; 22:444-6. [PMID: 18568738 DOI: 10.1080/02688690802040637] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
We discuss a case of subdural metastasis in which the clinical features and associated images mimic acute subdural haematoma.
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Allen C, Bowdin S, Harrison RF, Sutcliffe AG, Brueton L, Kirby G, Kirkman-Brown J, Barrett C, Reardon W, Maher E. Pregnancy and perinatal outcomes after assisted reproduction: a comparative study. Ir J Med Sci 2008; 177:233-41. [PMID: 18521653 DOI: 10.1007/s11845-008-0172-9] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2007] [Accepted: 04/25/2008] [Indexed: 11/26/2022]
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Azuma M, Shi MM, Jacques CJ, Barrett C, Danenberg KD, Iqbal S, El-Khoueiry A, Yang D, Zhang W, Lenz H. Tumor VEGFA gene expression is associated with serum lactate dehydrogenase (LDH) levels and intratumoral mRNA expression of genes involved in glycolysis in patients with metastatic colorectal cancer (mCRC). J Clin Oncol 2006. [DOI: 10.1200/jco.2006.24.18_suppl.3530] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
3530 Background: It is well known that angiogenesis and glycolysis are regulated by hypoxic conditions. Recent clinical trials (CONFIRM1 and CONFIRM2) have shown that patients with mCRC with high serum LDH benefited from PTK787/ZK 222584, a VEGF receptor tyrosine kinase inhibitor. We tested the hypothesis that patients with high serum LDH have increased intratumoral expression of genes involved with hypoxia (hypoxia inducible factor (HIF1a and 2a) and lactate dehydrogenase A (LDHA) and glycolysis (glucose transporter 1 (Glut-1) and genes involved in angiogenesis such as vascular endothelial growth factor A (VEGFA) and neuropilin 1 (NRP1) in patients with mCRC. Methods: 78 formalin fixed paraffin embedded (FFPE) tumor samples from 36 patients (20 males, 16 females: Median age 59 years (range 29–84) with mCRC who underwent first line therapy (not from CONFIRM trials) were analyzed. In addition, tumor gene expression was correlated with serum LDH levels from the same group of patients. FFPE tissues were dissected using laser-captured microdissection and analyzed LDHA, VEGFA, HIF1a, HIF2a, Glut-1 and NRP1 mRNA expression using a quantitative real-time RT-PCR method. Gene expression values (relative mRNA levels) are expressed as ratios between the target gene and internal reference gene (beta-actin). Results: Spearman Rank Correlation Analysis of Associations Between serum LDH levels and Gene Expression values. Conclusions: Our results demonstrate that intratumoral gene expression of LDHA, HIF1a and HIF2a, Glut-1 and VEGFA are significantly correlated. Patients with high serum LDH have increased intratumoral gene expression of VEGFA. These results support the hypothesis that serum LDH levels may serve as a surrogate marker for activation of the HIF related genes in the tumor. These observations may explain the efficacy of PTK787 in metastatic colorectal cancer patients with high serum LDH levels. [Table: see text] [Table: see text]
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Kelly P, Barrett C. Coronary disease in the puerperium. Eur J Intern Med 2005; 16:469-72. [PMID: 16275537 DOI: 10.1016/j.ejim.2005.03.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/08/2004] [Revised: 02/21/2005] [Accepted: 03/11/2005] [Indexed: 11/24/2022]
Abstract
The manifestation of an acute coronary syndrome in women in the postpartum period is a rare but important clinical scenario, which, because of its multiple possible aetiologies, requires a different approach to management on the part of the clinician. Spontaneous coronary artery dissection (SCAD) is the most likely cause of an acute coronary syndrome in women in the puerperium. Unfortunately there is no medical consensus on the correct management pathway of such patients, but there is evidence that these patients have an improved prognosis when referred for bypass surgery or percutaneous intervention.
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Barrett C, Kinzer D, Alper M, Powers R. Analysis of Failed Fertilization in IVF and ICSI Patients Using the DNA Specific Stain Hoechst 33342. Fertil Steril 2005. [DOI: 10.1016/j.fertnstert.2005.07.736] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Barrett C. Dermatology nursing: spreading good practice in primary care. THE JOURNAL OF FAMILY HEALTH CARE 2005; 15:35. [PMID: 15945491] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
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Hardy M, Barrett C. Interpretation of trauma radiographs by radiographers and nurses in the UK: a comparative study. Br J Radiol 2004; 77:657-61. [PMID: 15326043 DOI: 10.1259/bjr/53007610] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
The purpose of this study was to identify the number of hospitals employing nurses and radiographers formally to undertake radiographic interpretation of trauma images and to compare the education undertaken by these professionals and any limitations imposed. A cross-sectional questionnaire survey of nurse and radiographer managers responsible for Accident and Emergency services within National Health Service hospitals in the UK was undertaken in January 2002. A total of 526 questionnaires were distributed. Response rates of 75.3% (n=198/263) and 69.2% (n=182/263) were received from radiographer and nurse managers, respectively. 96 nurse managers (52.7%, n=96/182) indicated that nurses within their departments were formally interpreting radiographs as part of their extended role whereas only 68 radiography managers (34.3%, n=68/198) indicated that radiographers were undertaking this role. Education to support radiographic interpretation varied markedly with 92.6% (n=63/68) of radiographers having undertaken a postgraduate qualification in image interpretation. In contrast, nurse education at all levels was more generic to the nursing role. The range of examinations which nurses and radiographers were permitted to interpret also varied markedly. Radiographic interpretation is undertaken by both nurses and radiographers. However, there is interprofessional and intraprofessional inconsistency in the range of examinations they are permitted to interpret and the level of education provided to support this role. Consequently, it can be surmised that national variation in service delivery and quality exists and a review of current service delivery strategies is recommended.
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Peacock NW, Hainsworth JD, Switzer AB, Burris HA, Barrett C, Nicolau MF, Greco FA. Weekly bolus topotecan as secondary therapy in extensive stage small cell lung cancer: A Minnie Pearl Cancer Research Network phase II trial. J Clin Oncol 2004. [DOI: 10.1200/jco.2004.22.90140.7278] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Harris NM, Thorpe R, Dickinson H, Rorison F, Barrett C, Williams C. Hospital and after: experience of patients and carers in rural and remote north Queensland, Australia. Rural Remote Health 2004; 4:246. [PMID: 15884987] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/02/2023] Open
Abstract
INTRODUCTION This article reports a study of patients and carers discharged from the Townsville General Hospital into rural and remote communities in north Queensland, Australia. The findings indicate the importance of focusing on the experiences of patients and carers in attempting to understand the impact of discharge procedures. The four stories and their implications exist within a particular healthcare context that impacts disproportionately on rural patients and their carers. Economic rationalism has shaped contemporary healthcare policy in Australia, creating a system that is encouraged to conform to market principles. The costs borne by individuals, groups and communities have been increasingly privatised. Later admission and earlier discharge from hospital is now the norm. Concern about the impact of this policy context on the lives of rural and remote patients and carers prompted the study, which aimed to: (1) examine, from the patient and carer perspective, the social, economic, cultural and emotional cost of hospitalisation away from home communities; (2) identify the needs of rural and remote patients and their carers before, during and after hospitalisation a long way from home; and (3) make recommendations for improved policies and practices concerning the continuum of care: from admission planning, through hospitalisation, discharge-planning, and post-discharge support, in the context of rural and remote location. METHODS The experiences presented highlight the depth of the challenges faced by patients and their carers who live in rural and remote communities. Both quantitative and qualitative methodologies were used to obtain insight into the complexity of patients and carers' lives. The four vignettes presented in this paper are taken from in-depth, qualitative interviews with 12 patients and 12 carers. RESULTS The four stories described reveal the high financial and emotional costs, for patients and carers, of negotiating a healthcare system a long way from home. Challenges faced included inadequate admission planning, excessive accommodation and transport costs, and lack of post-discharge support services in home communities, as well as business failure, marital and family strain. There was an over-reliance on carers who lacked medical caring expertise, had other major commitments (family and work) and who may have had a tenuous and uncertain relationship with the patient. CONCLUSIONS Recognition of these complex circumstances, exacerbated by rural location, during the discharge planning process should mean that attention to ensuring patients and their carers are linked to adequate support services in their communities is of the highest priority. The communication and dissemination of information to patients and carers is also vital. Information on hospital admission, travel benefits, accommodation options, care requirements post-discharge are particular recommendations. To summarise, the experiences highlighted in this study suggest that patients and carers in rural and remote communities have not benefited from adequate discharge planning, and are struggling to cope in a policy context that encourages later admission, earlier discharge and over reliance on family and friends as carers.
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Hardy ML, Barrett C. Requesting and interpreting trauma radiographs: a role extension for accident & emergency nurses. ACTA ACUST UNITED AC 2003; 11:202-13. [PMID: 14521966 DOI: 10.1016/s0965-2302(03)00037-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Government supported expansion of the nursing role within Accident & Emergency (A&E) departments in the United Kingdom (UK) has begun to break down the traditional barriers to professional practice. Today, many nurses working within A&E departments are both requesting and interpreting radiographic examinations as part of their normal working practice. However, role expansion does not occur without increased responsibility. Unsatisfactory requests for radiography and inaccurate radiographic interpretation may result in inappropriate patient treatment, misuse of resources, patient recall and litigation. Nurses undertaking these role extensions need to ensure that their levels of knowledge and skill to perform the role are appropriate and adequately supported. This article summarises the results of a national questionnaire survey of A&E nurse managers that aimed to identify current working practices, including education, training and limitations to practice, with respect to the requesting and interpretation of trauma radiographs by A&E nurses.
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Abstract
BACKGROUND Many accident and emergency clinicians regard the radiographic image as an extension of the clinical examination, as a provisional diagnosis, based on clinical signs and symptoms, can be confirmed or refuted by inspection of X-rays. However, the value of radiography in this context is not determined by the actual presence of trauma or pathology on the radiograph, but is dependent on the ability of a clinician to identify any trauma or pathology present. Traditionally, the responsibility for interpreting radiographic images within the accident and emergency environment in the United Kingdom (UK) has been with medical clinicians. However, expansion of the nursing role has begun to change the boundaries of professional practice and now many nurses are both requesting and interpreting trauma radiographs. AIM To ascertain the ability of accident and emergency doctors and nurses to interpret trauma radiographs, and identify whether there is a consistent standard of interpretive accuracy that could be used as a measure of competence. METHODS A literature review was conducted using the Cochrane Library, Medline and CINAHL databases and the keywords radiographic interpretation, radiographic reporting, accident and emergency and emergency/nurse practitioner. FINDINGS The ability of accident and nursing doctors and nurses to interpret trauma radiographs accurately varies markedly, and no identified published study has established an appropriate level of accuracy that should be achieved in order to demonstrate satisfactory competence in the interpretation of radiographic images. CONCLUSIONS Determining a measure of interpretive accuracy that can be used to assess ability to interpret radiographic trauma images is fraught with difficulties. Consequently, nurses may attempt to prove their skills by directly comparing their abilities to those of their medical colleagues. However, as a result of marked variation in the ability of senior house officers to interpret trauma radiographs, a similar ability does not automatically imply that a satisfactory level of ability has been achieved.
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Karplus K, Karchin R, Barrett C, Tu S, Cline M, Diekhans M, Grate L, Casper J, Hughey R. What is the value added by human intervention in protein structure prediction? Proteins 2002; Suppl 5:86-91. [PMID: 11835485 DOI: 10.1002/prot.10021] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
This article presents results of blind predictions submitted to the CASP4 protein structure prediction experiment. We made two sets of predictions: one using the fully automated SAM-T99 server and one using the improved SAM-T2K method with human intervention. Both methods use iterative hidden Markov model-based methods for constructing protein family profiles, using only sequence information. Although the SAM-T99 method is purely sequence based, the SAM-T2K method uses the predicted secondary structure of the target sequence and the known secondary structure of the templates to improve fold recognition and alignment. In this article, we try to determine what aspects of the SAM-T2K method were responsible for its significantly better performance in the CASP4 experiment in the hopes of producing a better automatic prediction server. The use of secondary structure prediction seems to be the most valuable single improvement, though the combined total of various human interventions is probably at least as important.
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Barrett C, Natansohn A, Rochon P. Thermal Cis-Trans Isomerization Rates of Azobenzenes Bound in the Side Chain of Some Copolymers and Blends. Macromolecules 2002. [DOI: 10.1021/ma00095a019] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Barrett C, Good C, Moore C. Comparison of point-of-collection screening of drugs of abuse in oral fluid with a laboratory-based urine screen. Forensic Sci Int 2001; 122:163-6. [PMID: 11672972 DOI: 10.1016/s0379-0738(01)00492-3] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Oral fluid is becoming increasingly useful for the detection of drugs, since it is a non-invasive specimen to collect and, because collection is directly observed, it is difficult to adulterate. A point-of-collection (POCT) oral fluid drug analysis kit has been developed for use in many drug testing situations. This paper summarizes the results of field evaluations of the ORALscreen System for screening of drugs in oral fluid. The ORALscreen System consists of an oral fluid collection device and a test device containing a lateral flow membrane immunoassay system. Paired samples (oral fluid and urine) were collected from drug users and the results from the ORALscreen POCT system were compared to urine screening results conducted in a licensed laboratory. The results demonstrate that the ORALscreen System has excellent percent agreement with the laboratory-based urine screening test results for the detection of cocaine and opiates through 2.5-3 days following drug use, respectively. Tetrahydrocannabinol (THC) was detected by ORALscreen on the day of use and 1 day after use. Good correlation between urine and oral fluid screening results was observed for the methamphetamine positive samples; however, the number of days following drug use was not determined.
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Barrett C, Wang S, Powers R. Maintaining temperature in IVF culture dishes: do aluminum warming blocks reduce the rate of cooling? Fertil Steril 2001. [DOI: 10.1016/s0015-0282(01)02681-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Abstract
In this article, the authors review the most recent advances in the pharmacotherapy, psychotherapy, and combined therapy for panic disorder. The authors focus on peer-reviewed data and on pragmatic clinical approaches that may help patients suffering from panic disorder.
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Barrett C, Guthrie S. Expression patterns of the netrin receptor UNC5H1 among developing motor neurons in the embryonic rat hindbrain. Mech Dev 2001; 106:163-6. [PMID: 11472849 DOI: 10.1016/s0925-4773(01)00415-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The axon guidance molecule netrin-1 has been implicated in the midline repulsion of developing cranial motor axons. We have examined expression patterns of the netrin receptors UNC5H1 and DCC in embryonic rat hindbrains, in combination with labelling of developing motor neurons. We found that UNC5H1 expression colocalised with a number of cranial motor neuron subpopulations from embryonic day 11 (E11) to E14, while DCC was expressed by motor neurons at E12.
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Sharma V, Barrett C. Tryptophan for treatment of rapid-cycling bipolar disorder comorbid with fibromyalgia. CANADIAN JOURNAL OF PSYCHIATRY. REVUE CANADIENNE DE PSYCHIATRIE 2001; 46:452-3. [PMID: 11441787 DOI: 10.1177/070674370104600521] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Barrett C, Cavallari W, Sciulli PW. Estimation of sex from the talus in prehistoric Native Americans. COLLEGIUM ANTROPOLOGICUM 2001; 25:13-9. [PMID: 11787537] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Abstract
We present both a multivariate discriminant analysis and a univariate procedure to estimate sex from measures of the talus (length, width and height). Both methods are comparable in accuracy (about 85%), but the univariate procedure ispreferred due to its simplicity.
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Barrett C, Whitton M. Interventions for vitiligo. Hippokratia 2001. [DOI: 10.1002/14651858.cd003263] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Barr JT, Otto CN, Freeman SF, Barrett C, Hirsch CA, Cerda SR. Linking variation in the structure and process of bedside glucose testing programs with patient outcomes. CLINICAL LABORATORY SCIENCE : JOURNAL OF THE AMERICAN SOCIETY FOR MEDICAL TECHNOLOGY 2001; 14:27-32. [PMID: 15633491] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 05/01/2023]
Abstract
OBJECTIVE The objective of this study was to determine if variation in compliance to standards listed in Ancillary (Bedside) Blood Glucose Testing in Acute and Chronic Care Facilities (ABBGT) was linked to variation in patient outcomes. DESIGN AND SETTING A retrospective analysis examined 450 hospitalized patients with a diagnosis of diabetes from three hospitals with high, medium, and low assessment scores for compliance with ABBGT guidelines. Patients with a diagnosis of diabetes without surgical interventions or intensive care unit stays were selected for the study. MAIN OUTCOMES MEASURED percent bedside glucose tests that were out of normal range and length of stay. RESULTS Compliance with ABBGT guidelines explained the variation for out of range bedside glucose tests---1.4% and length CONCLUSION Within a narrow range and high level of compliance with ABBGT guidelines, the compliance scores had a small effect upon the selected outcomes. The hypothesis that following ABBGT guidelines improves patient outcomes was neither proven nor disproven with this study.
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Mutimer D, Dusheiko G, Barrett C, Grellier L, Ahmed M, Anschuetz G, Burroughs A, Hubscher S, Dhillon AP, Rolles K, Elias E. Lamivudine without HBIg for prevention of graft reinfection by hepatitis B: long-term follow-up. Transplantation 2000; 70:809-15. [PMID: 11003363 DOI: 10.1097/00007890-200009150-00018] [Citation(s) in RCA: 131] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
BACKGROUND This open, multicenter study was conducted to evaluate the efficacy and safety of lamivudine prophylaxis given to chronic hepatitis B virus-(HBV) infected patients before and after orthotopic liver transplantation (OLT). We now present long-term data that follow our previous short-term report. METHODS Twenty-three patients were treated with lamivudine (100 mg orally, daily); 13 (57%), were serum HBV DNA positive (Abbott Genostics, Abbott Laboratories, Chicago, IL) at study entry. Patients received lamivudine for at least 4 weeks before OLT, and for up to 50 months (median 25 months) after OLT. RESULTS Of the 23 treated patients, 17 survived to undergo OLT. Eleven patients (65%) survived up to 4 years (median 36 months) after OLT. One of the survivors stopped lamivudine because of a possible adverse reaction 9 months post-OLT, and prophylaxis with HBV immune globulin was then established. Ten survivors continue lamivudine. Eight long-term survivors have normal liver function without evidence of HBV reinfection. Of the 17 transplanted patients, 6 died. Four patients died (3 days to 5 months post-OLT) without evidence of graft reinfection. Two further patients died at 19 and 23 months post-OLT from graft failure. Both patients had YMDD variant detected at 12 months post-OLT. Two other patients with YMDD-variant HBV remain alive on lamivudine, 9 and 15 months after development of the variant. CONCLUSIONS Lamivudine, given before and after OLT, prevents significant graft reinfection for the majority of treated patients. The study has also shown that lamivudine is extremely well tolerated by liver failure patients and for a prolonged period after transplantation.
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Holt J, Barrett C, Clarke D, Monks R. The globalization of nursing knowledge. NURSE EDUCATION TODAY 2000; 20:426-431. [PMID: 10959129 DOI: 10.1054/nedt.2000.0497] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
External influences placed upon nurses working in universities and in clinical practice require them to attract research funding, carry out research, generate new knowledge and publish in national and international journals. While there does not appear to be an agreed, unified body of nursing knowledge, critical and scholarly debate is essential to generate knowledge, but this is not an activity in which the majority of nurses can effectively participate. Nevertheless, nurses in the Western world are free to communicate their research, theories or ideas, essentially uncensored, to a vast invisible audience, and there is global dissemination through a vast array of literature and educational materials. This paper challenges nurses to examine the implications of globalization and suggests that the continuing debate on the nature of nursing knowledge should be updated to include consideration of both a change in philosophical stance and the far reaching effects of global dissemination of information.
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Jurevics H, Hostettler J, Barrett C, Morell P, Toews AD. Diurnal and dietary-induced changes in cholesterol synthesis correlate with levels of mRNA for HMG-CoA reductase. J Lipid Res 2000; 41:1048-54. [PMID: 10884284] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023] Open
Abstract
We determined the extent to which diurnal variation in cholesterol synthesis in liver is controlled by steady-state mRNA levels for the rate-limiting enzyme in the pathway, hydroxymethylglutaryl (HMG)-CoA reductase. Rats 30 days of age and maintained on a low-cholesterol diet since weaning were injected intraperitoneally with (3)H(2)O. The specific radioactivity of the whole-body water pool soon became constant, allowing for expression of values for incorporation of label into cholesterol as absolute rates of cholesterol synthesis. In liver, there was a peak of cholesterol synthesis from 8 pm to midnight, a 4-fold increase over synthesis rates from 8 am to noon. Increases in synthesis were quantitatively in lock step with increases in mRNA levels for HMG-CoA reductase occurring 4 h earlier. In a parallel experiment, rats received 1% cholesterol in the diet from weaning to 30 days of age. Basal levels of hepatic cholesterol synthesis were greatly diminished and there was little diurnal variation of cholesterol synthesis or of levels of mRNA for HMG-CoA reductase. Levels of mRNA for the low density lipoprotein receptor and scavenger receptor-B1 (putative high density lipoprotein receptor) showed little diurnal variation, regardless of diet. This suggests that diurnal variation of hepatic cholesterol synthesis is driven primarily by varying the steady-state mRNA levels for HMG-CoA reductase. Other tissues were also examined. Adrenal gland also showed a 4-fold diurnal increase in accumulation of recently synthesized cholesterol. In contrast to liver, however, there was little corresponding change in mRNA expression for HMG-CoA reductase. Much of this newly synthesized cholesterol may be of hepatic origin, imported into adrenal by SR-B1, whose mRNA was up-regulated 2-fold. In brain, there was no diurnal variation in either cholesterol synthesis or mRNA expression, and no influence of high- or low-cholesterol diets on synthesis rates or HMG-CoA reductase mRNA levels.
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