A critical lineage-nonspecific role for pTalpha in mediating allelic and isotypic exclusion in TCRbeta-transgenic mice.

Although it is well established that early expression of TCRbeta transgenes in the thymus leads to efficient inhibition of both endogenous TCRbeta and TCRgamma rearrangement (also known as allelic and "isotypic" exclusion, respectively) the role of pTalpha in these processes remains controversial. Here, we have systematically re-evaluated this issue using three independent strains of TCRbeta-transgenic mice that differ widely in transgene expression levels, and a sensitive intracellular staining assay that detects endogenous TCRVbeta expression in individual immature thymocytes. In the absence of pTalpha, both allelic and isotypic exclusion were reversed in all three TCRbeta-transgenic strains, clearly demonstrating a general requirement for pre-TCR signaling in the inhibition of endogenous TCRbeta and TCRgamma rearrangement. Both allelic and isotypic exclusion were pTalpha dose dependent when transgenic TCRbeta levels were subphysiological. Moreover, pTalpha-dependent allelic and isotypic exclusion occurred in both alphabeta and gammadelta T cell lineages, indicating that pre-TCR signaling can potentially be functional in gammadelta precursors. Finally, levels of endogenous RAG1 and RAG2 were not down-regulated in TCRbeta-transgenic immature thymocytes undergoing allelic or isotypic exclusion. Collectively, our data reveal a critical but lineage-nonspecific role for pTalpha in mediating both allelic and isotypic exclusion in TCRbeta-transgenic mice.

Prophylaxis of experimental endocarditis with antiplatelet and antithrombin agents : a role for long-term prevention of infective endocarditis in humans?

BACKGROUND: Infective endocarditis (IE) mostly occurs after spontaneous low-grade bacteremia. Thus, IE cannot be prevented by circumstantial antibiotic prophylaxis. Platelet activation following bacterial-fibrinogen interaction or thrombin-mediated fibrinogen-fibrin polymerization is a critical step in vegetation formation. We tested the efficacy of antiplatelet and antithrombin to prevent experimental IE. METHODS: A rat model of experimental IE following prolonged low-grade bacteremia mimicking smoldering bacteremia in humans was used. Prophylaxis with antiplatelets (aspirin, ticlopidine [alone or in combination], eptifibatide, or abciximab) or anticoagulants (antithrombin dabigatran etexilate or anti-vitamin K acenocoumarol) was started 2 days before inoculation with Streptococcus gordonii or Staphylococcus aureus. Valve infection was assessed 24 hours later. RESULTS: Aspirin plus ticlopidine, as well as abciximab, protected 45%-88% of animals against S. gordonii and S. aureus IE (P < .05). Dabigatran etexilate protected 75% of rats against IE due to S. aureus (P < .005) but failed to protect against S. gordonii (<30% protection). Acenocoumarol was ineffective. CONCLUSIONS: Antiplatelet and direct antithrombin agents may be useful in the prophylaxis of IE in humans. In particular, the potential dual benefit of dabigatran etexilate might be reconsidered for patients with prosthetic valves, who require life-long anticoagulation and in whom S. aureus IE is associated with high mortality.

Critical thinking and accuracy of nurses' diagnoses. Part I: risk of low accuracy diagnoses and new views of critical thinking

Interpretations of patient data are complex and diverse, contributing to a risk of low accuracy nursing diagnoses. This risk is confirmed in research findings that accuracy of nurses' diagnoses varied widely from high to low. Highly accurate diagnoses are essential, however, to guide nursing interventions for the achievement of positive health outcomes. Development of critical thinking abilities is likely to improve accuracy of nurses' diagnoses. Newer views of critical thinking serve as a basis for critical thinking in nursing. Seven cognitive skills and ten habits of mind are identified as dimensions of critical thinking for use in the diagnostic process.

Critical thinking and accuracy of nurses' diagnoses. Part II: application of cognitive skills and guidelines for self-development

Part I of this article, the author explained the difficulties of achieving accuracy of nurses' diagnoses, the relevance of critical thinking to the achievement of accuracy, and newer views of critical thinking. In Part II, the critical thinking dimensions identified as important for nursing practice are applied in the diagnostic process using a case study of a 16 year old girl with type 1 diabetes. Application of seven cognitive skills and ten habits of mind illustrate the importance of using critical thinking for accuracy of nurses' diagnoses. Ten strategies are proposed for self-development of critical thinking abilities.

Epidermal growth factor (EGF) stimulation of cultured brain cells. I. Enhancement of the developmental increase in glial enzymatic activity.

Serum-free aggregating cell cultures of fetal rat telencephalon grown in the presence of 3 ng/ml (5 X 10(-10) M) epidermal growth factor (EGF) until day 12 showed 2- to 3-fold increased activities in the two glial enzymes, glutamine synthetase (GLU-S) and 2',3'-cyclic nucleotide 3'-phosphohydrolase (CNPase). This effect was concentration-dependent, with maximal stimulation in cultures treated daily with 3 ng/ml EGF. Addition of EGF during the first 10 culture days was sufficient to produce a maximal stimulation of both GLU-S and CNPase on day 19, whereas treatments starting on day 12 were ineffective. The stimulation of GLU-S preceded that of CNPase. The EGF-induced increase in GLU-S activity was not directly dependent on the presence of insulin, triiodothyronine, or hydrocortisone in the medium, whereas insulin was required for the stimulation of CNPase. A single dose of 5 ng/ml EGF on day 2 caused a slight but significant decrease in DNA synthesis after day 6. The present results indicate that in serum-free aggregating cell cultures of fetal rat telencephalon EGF partially inhibits DNA synthesis, and stimulates an early step in glial differentiation.

The neuronal adhesion protein D2 in differentiating aggregates of brain cells.

The D2-protein is a high molecular weight protein involved in interneuronal adhesion. The concentration of D2-protein was measured both in aggregates of fetal rat telencephalic cells cultured in a chemically defined medium and in developing forebrain. Both the concentration of the D2-protein and the degree of sialylation were changed in the cultures in parallel with the corresponding values obtained from postnatal forebrain. In the cultures the highest specific concentration of D2-protein was observed after 12 days in culture. This value was 2.7 times higher than the average value of adult rat forebrain. Antibodies to D2-protein have previously been shown to inhibit fasciculation of neuritic fibers extending from cultured explants of sympathetic ganglia. We investigated the effect of such antibodies on the differentiation of aggregating telencephalic cells. By adding surplus antibodies to the cultures from day 11 to day 16 we were able to decrease the specific concentration of D2-protein on the neurons by 53% measured at day 19. The decrease was not compensated fully even after further 10 days in the culture. Although the concentration of D2-protein was decreased during the period of synaptogenesis no change was found in the specific concentration of a marker of mature synapses, the D3-protein. Thus, in this culture system synaptogenesis could proceed to an unimpaired extent in the presence of a decreased concentration of a putatively involved adhesion molecule. However, the specific concentration of two markers of myelination, 2',3'-cyclic nucleotide 3'-phosphodiesterase and myelin basic protein, were both increased, suggesting an antibody-induced stimulation of myelination in the cultured aggregates.

Pancreatic stone protein as an early biomarker predicting mortality in a prospective cohort of patients with sepsis requiring ICU management.

ABSTRACT: INTRODUCTION: Biomarkers, such as C-reactive protein [CRP] and procalcitonin [PCT], are insufficiently sensitive or specific to stratify patients with sepsis. We investigate the prognostic value of pancreatic stone protein/regenerating protein (PSP/reg) concentration in patients with severe infections. METHODS: PSP/reg, CRP, PCT, tumor necrosis factor-alpha (TNF-α), interleukin 1 beta (IL1-β), IL-6 and IL-8 were prospectively measured in cohort of patients ≥ 18 years of age with severe sepsis or septic shock within 24 hours of admission in a medico-surgical intensive care unit (ICU) of a community and referral university hospital, and the ability to predict in-hospital mortality was determined. RESULTS: We evaluated 107 patients, 33 with severe sepsis and 74 with septic shock, with in-hospital mortality rates of 6% (2/33) and 25% (17/74), respectively. Plasma concentrations of PSP/reg (343.5 vs. 73.5 ng/ml, P < 0.001), PCT (39.3 vs. 12.0 ng/ml, P < 0.001), IL-8 (682 vs. 184 ng/ml, P < 0.001) and IL-6 (1955 vs. 544 pg/ml, P < 0.01) were significantly higher in patients with septic shock than with severe sepsis. Of note, median PSP/reg was 13.0 ng/ml (IQR: 4.8) in 20 severely burned patients without infection. The area under the ROC curve for PSP/reg (0.65 [95% CI: 0.51 to 0.80]) was higher than for CRP (0.44 [0.29 to 0.60]), PCT 0.46 [0.29 to 0.61]), IL-8 (0.61 [0.43 to 0.77]) or IL-6 (0.59 [0.44 to 0.75]) in predicting in-hospital mortality. In patients with septic shock, PSP/reg was the only biomarker associated with in-hospital mortality (P = 0.049). Risk of mortality increased continuously for each ascending quartile of PSP/reg. CONCLUSIONS: Measurement of PSP/reg concentration within 24 hours of ICU admission may predict in-hospital mortality in patients with septic shock, identifying patients who may benefit most from tailored ICU management.

Critical role for the lactate transporter, monocarboxylate transporter 1 (mct1), in the regeneration of peripheral nerves

Axons, and particularly regenerating axons, have high metabolic needs in order to maintain critical functions such as axon transport and membrane depolarization. Though some of the required energy likely comes form extracellular glucose and ATP generated in the soma, we and others hypothesize that some of the energy may be supplied by lactate. Unlike glucose that requires glycolytic enzymes to produce pyruvate, lactate can be converted directly to pyruvate by lactate dehydrogenase and transported into mitochondria for oxidative metabolism. In order to be transported into or out of cells, lactate requires specific monocarboxylate transporters (MCTs), the most abundant of which is MCT1. If MCT1 and lactate are critical for nerve function and regeneration, we hypothesize that MCT1 heterozygote null mice, which appear phenotypically normal despite having approximately 40% MCT1 as compared to wildtype littermate mice, would have reduced capacity for repair following nerve injury. To investigate this, adult MCT1 heterozygote null mice or wild-type mice underwent unilateral sciatic nerve crush in the proximal thigh. We found that regeneration of the sciatic nerve, as measured by recovery of compound muscle action potentials (CMAP) in the lateral plantar muscles following proximal sciatic nerve stimulation, was delayed from a median of 21 days in wildtype mice to 38.5 days in MCT1 heterozygote mice. In fact, half of the MCT1 heterozygote null mice had no recovery of CMAP by the endpoint of the study at 42 days, while all of the wild-type mice had recovered. In addition, the maximal amplitude of CMAP recovery in MCT1 heterozygote mull mice was reduced from a mean of 3 mV to 0.5 mV. As would be expected, the denervated gastrocnemius muscle of MCT1 heterozygote null mice remained atrophic at 42 days compared to wild-type mice. Our experiments show that lactate supplied through MCT1 is necessary for nerve regeneration. Experiments are underway to determine whether loss of MCT1 prevents nerve regrowth directly due to reduced energy supply to axons or indirectly by dysfunctional Schwann cells normally dependent on lactate supply through MCT1.

Critical thoughts on computing atom condensed Fukui functions

Different procedures to obtain atom condensed Fukui functions are described. It is shown how the resulting values may differ depending on the exact approach to atom condensed Fukui functions. The condensed Fukui function can be computed using either the fragment of molecular response approach or the response of molecular fragment approach. The two approaches are nonequivalent; only the latter approach corresponds in general with a population difference expression. The Mulliken approach does not depend on the approach taken but has some computational drawbacks. The different resulting expressions are tested for a wide set of molecules. In practice one must make seemingly arbitrary choices about how to compute condensed Fukui functions, which suggests questioning the role of these indicators in conceptual density-functional theory

Critical analysis and extension of the Hirshfeld atoms in molecules

The computational approach to the Hirshfeld [Theor. Chim. Acta 44, 129 (1977)] atom in a molecule is critically investigated, and several difficulties are highlighted. It is shown that these difficulties are mitigated by an alternative, iterative version, of the Hirshfeld partitioning procedure. The iterative scheme ensures that the Hirshfeld definition represents a mathematically proper information entropy, allows the Hirshfeld approach to be used for charged molecules, eliminates arbitrariness in the choice of the promolecule, and increases the magnitudes of the charges. The resulting "Hirshfeld-I charges" correlate well with electrostatic potential derived atomic charges

Evidence from glut2-null mice that glucose is a critical physiological regulator of feeding.

A role for glucose in the control of feeding has been proposed, but its precise physiological importance is unknown. Here, we evaluated feeding behavior in glut2-null mice, which express a transgenic glucose transporter in their beta-cells to rescue insulin secretion (ripglut1;glut2-/- mice). We showed that in the absence of GLUT2, daily food intake was increased and feeding initiation and termination following a fasting period were abnormal. This was accompanied by suppressed regulation of hypothalamic orexigenic and anorexigenic neuropeptides expression during the fast-to-refed transition. In these conditions, however, there was normal regulation of the circulating levels of insulin, leptin, or glucose but a loss of regulation of plasma ghrelin concentrations. To evaluate whether the abnormal feeding behavior was due to suppressed glucose sensing, we evaluated feeding in response to intraperitoneal or intracerebroventricular glucose or 2-deoxy-D-glucose injections. We showed that in GLUT2-null mice, feeding was no longer inhibited by glucose or activated by 2-deoxy-D-glucose injections and the regulation of hypothalamic neuropeptide expression by intracerebroventricular glucose administration was lost. Together, these data demonstrate that absence of GLUT2 suppressed the function of central glucose sensors, which control feeding probably by regulating the hypothalamic melanocortin pathway. Furthermore, inactivation of these glucose sensors causes overeating.

Evaluation of a modified Broström-Gould procedure for treatment of chronic lateral ankle instability: A retrospective study with critical analysis of outcome scoring.

BACKGROUND: Chronic lateral ankle instability accounts for 20% of the ankle injuries. This study evaluates functional outcome of the modified Broström-Gould technique using suture anchors, with 4 different clinical scores. METHODS: A consecutive series of 41 patients were included with a minimum follow-up of one year. The function was assessed using 4 clinical scores including: the AOFAS for hind foot; the FAAM; the CAIT and the CAIS. RESULTS: Out of 41 patients; 27 patients were very satisfied, 11 satisfied and 3 were not satisfied. Ankle mobility returned to normal in 93% of patients. At follow-up the AOFAS was 89/100 (37-100), the FAAM 85/100% (35-100%), the CAIT 20/30 (5-30), and the CAIS 74/100% (27-100%). CONCLUSION: Outcome of modified Broström-Gould procedure is good with high satisfaction rate in terms of ankle mobility. The disparity in outcome of scores, signals towards the need of a standard evaluation system.