Generation of normal human red cell volume, hemoglobin content, and membrane area distributions by "birth" or regulation?

Using flow cytometry and osmotic lysis measurements, we document here the means and coefficients of variation of the following red cell (RBC) properties: hemoglobin (Hb) content, volume, Hb concentration, and relative lytic tonicity distributions in populations of normal human RBCs, before and after density fractionation. The distributions showed a pattern characterized by much larger coefficients of variation of the Hb content and volume distributions than of the Hb concentration and relative lytic tonicity distributions. From analysis of the factors that determine those RBC properties, the patterns were interpreted as reflecting previously unrecognized statistical proportionalities between cell osmolyte content, Hb content, and membrane area. The possible origin of these statistical links was analyzed by considering alternative models with and without the participation of regulatory processes during cell maturation. A model was shown to be feasible in which mature RBC variability with proportional volume, area, and Hb content arises solely from cell size variability at the last erythroid cell division.     

Ectopic expression of rhombotin-2 causes selective expansion of CD4-CD8- lymphocytes in the thymus and T-cell tumors in transgenic mice

Although the proto-oncogene rhombotin-2 (RBTN-2) is widely expressed in most tissues, it is not expressed in T cells. We investigated the potential for overexpression of RBTN-2 to cause tumors in T cells and other tissues by constructing transgenic mice that expressed RBTN-2 under control of the metallothionein-1 promoter. Despite overexpression of RBTN-2 in all tissues, transgenic mice developed T-cell tumors only, thus indicating that tumorigenesis caused by RBTN-2 is T-cell-specific. Thymic tumors were found between 37 and 71 weeks and were invariably associated with metastasis to nonlymphoid organs. Thymuses from apparently healthy transgenic mice were also examined. In some mice there was an 10-fold increase in the CD4-CD8- thymocyte subset, yet the total number of thymocytes was the same as that in wild-type mice. Thymic homeostasis was maintained by a compensatory reduction in the CD4+CD8+ subset. The expansion of CD4-CD8- thymocytes was associated with increased expression of RBTN-2 and with increased cell proliferation. No differences were found in the proportion of thymocytes undergoing apoptosis in transgenic mice. Furthermore, RBTN-2- induced expansion of CD4-CD8- cells did not block differentiation of these cells. Thymuses with 30% CD4-CD8- cells were essentially monoclonal, indicating that all thymic immunophenotypes were derived from a single clone. Overall, our data are consistent with the following scenario: (1) RBTN-2 expression in T cells causes selective and polyclonal proliferation of CD4-CD8- thymocytes accompanied by a compensatory decrease in other thymocyte subsets; (2) a clone with growth advantage and differentiation potential is selected and populates the thymus; and (3) this clone eventually breaches homeostasis of the thymus, accompanied or followed by metastasis to other organs.     

Inactivation of CDK2 is synthetically lethal to MYCN over-expressing cancer cells

Two genes have a synthetically lethal relationship when the silencing or inhibiting of 1 gene is only lethal in the context of a mutation or activation of the second gene. This situation offers an attractive therapeutic strategy, as inhibition of such a gene will only trigger cell death in tumor cells with an activated second oncogene but spare normal cells without activation of the second oncogene. Here we present evidence that CDK2 is synthetically lethal to neuroblastoma cells with MYCN amplification and over-expression. Neuroblastomas are childhood tumors with an often lethal outcome. Twenty percent of the tumors have MYCN amplification, and these tumors are ultimately refractory to any therapy. Targeted silencing of CDK2 by 3 RNA interference techniques induced apoptosis in MYCN-amplified neuroblastoma cell lines, but not in MYCN single copy cells. Silencing of MYCN abrogated this apoptotic response in MYCN-amplified cells. Inversely, silencing of CDK2 in MYCN single copy cells did not trigger apoptosis, unless a MYCN transgene was activated. The MYCN induced apoptosis after CDK2 silencing was accompanied by nuclear stabilization of P53, and mRNA profiling showed up-regulation of P53 target genes. Silencing of P53 rescued the cells from MYCN-driven apoptosis. The synthetic lethality of CDK2 silencing in MYCN activated neuroblastoma cells can also be triggered by inhibition of CDK2 with a small molecule drug. Treatment of neuroblastoma cells with roscovitine, a CDK inhibitor, at clinically achievable concentrations induced MYCN-dependent apoptosis. The synthetically lethal relationship between CDK2 and MYCN indicates CDK2 inhibitors as potential MYCN-selective cancer therapeutics.     

Respiratory insufficiency in neuronopathic and neuropathic disorders

Twenty-nine patients with a neuronopathic or neuropathic disorder were referred for assessment of respiratory insufficiency between 1978 and 1994. Diagnoses included spinal muscular atrophy (6), chronic idiopathic demyelinating neuropathy (4), Vialetto-van Laere syndrome (3), hereditary motor and sensory neuropathy (3) and a miscellaneous group (5). We also describe seven patients with Guillain-Barre syndrome (GBS) who required long-term ventilatory support for over 6 months to 7 years after the initial illness. Respiratory insufficiency occurred as a consequence of respiratory muscle weakness, impaired bulbar function and restrictive lung defects. In some groups presentation was with progressive nocturnal hypoventilation culminating in acute respiratory failure. Five patients with GBS or chronic idiopathic demyelinating neuropathy were weaned from ventilatory support up to 18 months after the initial illness. The remaining 24 patients required continuous or nocturnal ventilatory support using intermittent positive-pressure ventilation (13), negative pressure ventilation (4), nasal-mask-delivered intermittent positive-pressure ventilation (4), nasal-mask-delivered continuous positive-pressure ventilation (3), mouthpiece-assisted ventilation by day (2) and rocking bed (1). None have been weaned from support after a period of ventilation ranging from one month to 10 years. Eight patients have subsequently died.      

Positive practice environments in critical care units in South Africa

PRETORIUS R. & KLOPPER H.C. (2011) Positive practice environments in critical care units in South Africa. International Nursing Review 59 , 66–72 Background: The demanding nature of the critical care unit (CCU) presents a challenge to many nursing professionals and carries the risk of a high turnover rate. The critical care nurse (CCN) is responsible for caring for the most ill patients in hospitals, and the acute shortage of nurses contributes to the intensity and pressure of the environment. While the reasons for the nursing shortage are varied and complex; a key factor seems to be an unhealthy work environment. Little evidence exists of research conducted to investigate the practice environment of CCNs in South Africa (SA). Purpose: This study aimed to construct a grounded theory for positive practice environments (PPEs) in private CCUs in SA. Methods: Intensive interviews and a constant comparative approach to data collection and data analysis were used to explore the participants' (n = 6) perceptions of the elements of a PPE. Findings: A theory depicting the core conceptual category of being in control and its relation to the other six categories was constructed from the data to explain a PPE for private CCUs in SA. Conclusions: The study provides a robust overview of the elements of a PPE and contributes to the constructivist application of grounded theory. Study limitations: The study was conducted in the private healthcare sector in SA, thus limiting the findings to this context.     

Intravenous glutamine decreases lung and distal organ injury in an experimental model of abdominal sepsis

Introduction

The protective effect of glutamine, as a pharmacological agent against lung injury, has been reported in experimental sepsis; however, its efficacy at improving oxygenation and lung mechanics, attenuating diaphragm and distal organ injury has to be better elucidated. In the present study, we tested the hypothesis that a single early intravenous dose of glutamine was associated not only with the improvement of lung morpho-function, but also the reduction of the inflammatory process and epithelial cell apoptosis in kidney, liver, and intestine villi.

Methods

Seventy-two Wistar rats were randomly assigned into four groups. Sepsis was induced by cecal ligation and puncture surgery (CLP), while a sham operated group was used as control (C). One hour after surgery, C and CLP groups were further randomized into subgroups receiving intravenous saline (1 ml, SAL) or glutamine (0.75 g/kg, Gln). At 48 hours, animals were anesthetized, and the following parameters were measured: arterial oxygenation, pulmonary mechanics, and diaphragm, lung, kidney, liver, and small intestine villi histology. At 18 and 48 hours, Cytokine-Induced Neutrophil Chemoattractant (CINC)-1, interleukin (IL)-6 and 10 were quantified in bronchoalveolar and peritoneal lavage fluids (BALF and PLF, respectively).

Results

CLP induced: a) deterioration of lung mechanics and gas exchange; b) ultrastructural changes of lung parenchyma and diaphragm; and c) lung and distal organ epithelial cell apoptosis. Glutamine improved survival rate, oxygenation and lung mechanics, minimized pulmonary and diaphragmatic changes, attenuating lung and distal organ epithelial cell apoptosis. Glutamine increased IL-10 in peritoneal lavage fluid at 18 hours and bronchoalveolar lavage fluid at 48 hours, but decreased CINC-1 and IL-6 in BALF and PLF only at 18 hours.

Conclusions

In an experimental model of abdominal sepsis, a single intravenous dose of glutamine administered after sepsis induction may modulate the inflammatory process reducing not only the risk of lung injury, but also distal organ impairment. These results suggest that intravenous glutamine may be a potentially beneficial therapy for abdominal sepsis.     

An evaluation of lecturer practitioners in Ireland

Nursing continues to struggle to integrate the theoretical and clinical aspects of nurse education for the development of competent practitioners. Collaborative approaches to nurse education as well as the development of joint clinical-academic roles have had questionable success to date on merging the theoretical and clinical components of nursing. Lecturer practitioners' posts are new in Ireland. These posts were created as nurse educators were cognizant of the need for students to integrate theory to practice. The aim of the lecturer practitioner role was to increase the support forstudent nurses in both academia and practice. An evaluation of the impact of the lecturer practitioner role from three key perspectives was conducted in three Irish teaching hospitals in 2007. The results of this study suggest that as lecturer practitioners have both a clinical and academic remit they can integrate theory to practice through collaborative practice.     

Impact of the palliative care clinical nurse specialist on patients and relatives: a stakeholder evaluation

Within the last decade, there has been a rapid expansion in the United Kingdom of clinical nurse specialists (CNSs), yet there has been limited evidence of their effectiveness. The clinical area of palliative care has one of the largest numbers of CNSs which has particularly started to escalate in the acute hospital setting. Following the Calman-Hine Report and the more recent NHS Cancer Plan, it is anticipated that the number of CNSs in palliative and cancer care is likely to grow. In light of the current policy emphasis of Clinical Governance and Clinical Effectiveness, there is an urgent need to demonstrate the contribution that CNSs make. This paper presents the qualitative findings of an evaluation study on the impact of the CNS within a palliative care team in a large acute hospital in the North-West of England. A stakeholder evaluation that encompassed tape-recorded semi-structured interviews to explore how the stakeholders saw the impact of the CNS within palliative care was performed. Twenty-seven interviews were conducted with stakeholders across the hospital setting including senior nurses, consultants, junior doctors and nurses representing the different grades. Data were analysed for emerging themes utilizing a case and cross-case analysis. The results indicated that the CNSs within palliative care in an acute hospital are seen to be potentially beneficial for both patients and relatives. This paper will focus on exploring these perceived benefits, which included symptom control, psychological care and being an advocate for patients and relatives.