The Effects of Prime Supporters within a College Student's Support Network.

College students face academic and emotional challenges within and outside of the classroom. There is not a unique way to deal with all of these challenges, however obtaining support from other individuals in their network can be an important factor in their success in dealing with these challenges. Exploratory social support network data from 38 undergraduate students were collected and analyzed to find common network structures and examine the relationship between these structures and student characteristics, GPA, perceived social support, and use of other help resources. We found half of the students had what we defined to be a novel network characteristic, prime supporters, which are individuals who provided academic and emotional support to students for both routine and intense academic and emotional problems. We found students with a prime supporter in their social network tended to have higher GPAs and perceived social support than those without a prime supporter. Students with prime supporters also had differences in academic help-seeking behavior. These findings suggest the need for further research on the social networks of college students, particularly the presence of individuals who are providers of multiple sources of support.

Model Comparison for Abiotic versus Biotic Pollen Dispersal.

An agent-based model with a correlated random walk is used to explore pollination within a forest. For abiotic dispersal, say via the wind, we use a purely random walk where there is no correlation between consecutive steps and for biotic dispersal, say via insect, we use a moderate or highly correlated random walk. In particular, we examine the differences in a number of biological measurement between a purely random walk and a correlated random walk in terms of gene dispersal in low and high plant densities.

Improving outcomes by combining septoplasty with primary external dacryocystorhinostomy.

PURPOSE: External dacryocystorhinostomy (EXT-DCR) is the gold standard in the treatment of acquired nasolacrimal duct obstruction. Intranasal pathology can compromise the success of primary and revision external dacryocystorhinostomy EXT-DCR procedures. Nasal septal deviations resulting in unfavorable anatomy are an identified cause of DCR failures. In this study, we examine the causes of failure in our patient population and propose that concomitant treatment of septal deviations at the time of primary EXT-DCR can decrease the rate of revision surgery. MATERIALS AND METHODS: Retrospective review of patients who had undergone an EXT-DCR. RESULTS: Over a five year period, 12 EXT-DCR failures were identified and 8 were directly attributable to nasal septal deviations. Revision surgery was successful in all 8 cases after correction of the nasal septal deviation. A second cohort of patients was identified who had undergone primary EXT-DCR and septoplasty concomitantly. Eight consecutive patients underwent the combined procedure for a total of 10 EXT-DCR and 8 septoplasties. The only failure was due to a common canalicular obstruction (90% success rate for the combined approach). CONCLUSIONS: As a result of our findings, we believe that treating nasal septal deviation at the time of the initial surgery can help minimize the need for revision surgery.

Modeling the interaction of vegetation and sea level rise on barrier island evolution.

Barrier islands provide a first line of defense against ocean flooding and storm surge. Biogeomorphic interactions are recognized as important in coastal system processes, but current barrier island models are primarily dominated by physical processes. Recent research has demonstrated different biogeomorphic states that influence response to sea level rise and other disturbance. Building on this understanding, we present a cellular model utilizing biotic and abiotic processes and their interactions for barrier island evolution. Using the literature and field derived parameters, we model barrier island evolution and compare to three decades of change for Smith Island, a Virginia Coast Reserve barrier island. We conduct simulations that show the impact of biogeomorphic states on island migration under different sea level rise scenarios. We find that migration is highest in areas with low topography and light vegetation cover (i.e. disturbance reinforcing) compared to areas with greater topographic complexity and high cover of woody vegetation i.e. disturbance resisting). This study demonstrates the importance of biogeomorphic interactions for barrier island evolution with sea level rise and will aid future predictions for these important ecosystems with climate change.

Effects of drought, disturbance, and biotic neighborhood on experimental tree seedling performance.

Forest biodiversity is likely maintained by a complex suite of interacting drivers that vary in importance across both space and time. Contributing factors include disturbance, interannual variation in abiotic variables, and biotic neighborhood effects. To probe ongoing uncertainties and potential interactions, we investigated tree seedling performance in a temperate mid-Atlantic forest ecosystem. We planted seedlings of five native tree species in mapped study plots, half of which were subjected to disturbance, and then monitored seedling survival, height growth, and foliar condition. The final year of data collection encompassed a drought, enabling comparison between intervals varying in water availability. Seedling performance was analyzed as a function of canopy cover and biotic neighborhood (conspecific and heterospecific abundance), including interactions, with separate generalized linear mixed models fit for each interval. All species exhibited: (a) pronounced declines in height growth during the drought year, (b) detrimental effects of adult conspecifics, and (c) beneficial effects of canopy openness. However, despite these consistencies, there was considerable variation across species in terms of the relevant predictors for each response variable in each interval. Our results suggest that drought may strengthen or reveal conspecific inhibition in some instances while weakening it or obscuring it in others, and that some forms of conspecific inhibition may manifest only under particular canopy conditions (although given the inconsistency of our findings, we are not convinced that conspecific inhibition is critical for diversity maintenance in our study system). Overall, our work reveals a complex forest ecosystem that appears simultaneously and interactively governed by biotic neighborhood structure (e.g., conspecific and/or heterospecific abundance), local habitat conditions (e.g., canopy cover), and interannual variability (e.g., drought).

Estimating the effect of active detection and isolation on Clostridioides difficile infections in a bone marrow transplant unit.

OBJECTIVE: To model the effects of active detection and isolation (ADI) regarding Clostridioides difficile infection (CDI) in the bone marrow transplant (BMT) unit of our hospital. SETTING: ADI was implemented in a 21-patient bone marrow unit. PATIENTS: Patients were bone marrow recipients on this unit. INTERVENTIONS: We compared active ADI, in which patients who tested positive for colonization of C. difficile before their hospital stay were placed under extra contact precautions, with cases not under ADI. RESULTS: Within the BMT unit, ADI reduced total cases of CDI by 24.5% per year and reduced hospital-acquired cases by ∼84%. The results from our simulations also suggest that ADI can save ∼$67,600 per year in healthcare costs. CONCLUSIONS: Institutions with active BMT units should consider implementing ADI.

An in silico approach to the analysis of acute wound healing.

The complex interactions that characterize acute wound healing have stymied the development of effective therapeutic modalities. The use of computational models holds the promise to improve our basic approach to understanding the process. By modifying an existing ordinary differential equation model of systemic inflammation to simulate local wound healing, we expect to improve the understanding of the underlying complexities of wound healing and thus allow for the development of novel, targeted therapeutic strategies. The modifications in this local acute wound healing model include: evolution from a systemic model to a local model, the incorporation of fibroblast activity, and the effects of tissue oxygenation. Using these modifications we are able to simulate impaired wound healing in hypoxic wounds with varying levels of contamination. Possible therapeutic targets, such as fibroblast death rate and rate of fibroblast recruitment, have been identified by computational analysis. This model is a step toward constructing an integrative systems biology model of human wound healing.

You get back what you give: Decreased hospital infections with improvement in CHG bathing, a mathematical modeling and cost analysis.

BACKGROUND: Multiple studies have shown that bathing with chlorhexidine gluconate (CHG) wipes reduces hospital-acquired infections (HAIs). We employed a mathematical model to assess the impact of CHG patient bathing on central line-associated bloodstream infections (CLABSIs), catheter-associated urinary tract infections (CAUTIs), and hospital-onset Clostridium difficile (C diff) infections and the associated costs. METHODS: Using a Markov chain, we examined the effect of CHG bathing compliance on HAI outcomes and the associated costs. Using estimates from 2 different studies on CHG bathing effectiveness for CLABSI, CAUTI, and C diff, the number of HAIs per year were estimated along with associated costs. The simulations were conducted, assuming CHG bathing at varying compliance rates. RESULTS: At 32% reduction in HAI incidence, increasing CHG bathing compliance from 60% to 90% results in 20 averted infections and $815,301.75 saved cost. CONCLUSIONS: As CHG bathing compliance increases, yearly HAIs decrease, and the overall cost associated with the HAIs also decreases.

Contemporary Trends in the Management of Posttraumatic Cerebrospinal Fluid Leaks.

The objective of this review is to provide an overview on the diagnosis and management of traumatic cerebrospinal fluid (CSF) leaks. This comprehensive review explores controversies associated with the management of CSF leaks as well as a review of the most contemporary literature. The scope of this article covers both traumatic CSF leaks of the middle and anterior cranial fossae.

Delayed functional expression of neuronal chemokine receptors following focal nerve demyelination in the rat: a mechanism for the development of chronic sensitization of peripheral nociceptors.

BACKGROUND: Animal and clinical studies have revealed that focal peripheral nerve axon demyelination is accompanied by nociceptive pain behavior. C-C and C-X-C chemokines and their receptors have been strongly implicated in demyelinating polyneuropathies and persistent pain syndromes. Herein, we studied the degree to which chronic nociceptive pain behavior is correlated with the neuronal expression of chemokines and their receptors following unilateral lysophosphatidylcholine (LPC)-induced focal demyelination of the sciatic nerve in rats. RESULTS: Focal nerve demyelination increased behavioral reflex responsiveness to mechanical stimuli between postoperative day (POD) 3 and POD28 in both the hindpaw ipsilateral and contralateral to the nerve injury. This behavior was accompanied by a bilateral increase in the numbers of primary sensory neurons expressing the chemokine receptors CCR2, CCR5, and CXCR4 by POD14, with no change in the pattern of CXCR3 expression. Significant increases in the numbers of neurons expressing the chemokines monocyte chemoattractant protein-1 (MCP-1/CCL2), Regulated on Activation, Normal T Expressed and Secreted (RANTES/CCL5) and interferon gamma-inducing protein-10 (IP-10/CXCL10) were also evident following nerve injury, although neuronal expression pattern of stromal cell derived factor-1alpha (SDF1/CXCL12) did not change. Functional studies demonstrated that acutely dissociated sensory neurons derived from LPC-injured animals responded with increased [Ca2+]i following exposure to MCP-1, IP-10, SDF1 and RANTES on POD 14 and 28, but these responses were largely absent by POD35. On days 14 and 28, rats received either saline or a CCR2 receptor antagonist isomer (CCR2 RA-[R]) or its inactive enantiomer (CCR2 RA-[S]) by intraperitoneal (i.p.) injection. CCR2 RA-[R] treatment of nerve-injured rats produced stereospecific bilateral reversal of tactile hyperalgesia. CONCLUSION: These results suggest that the presence of chemokine signaling by both injured and adjacent, uninjured sensory neurons is correlated with the maintenance phase of a persistent pain state, suggesting that chemokine receptor antagonists may be an important therapeutic intervention for chronic pain.

Acute ethanol exposure combined with burn injury enhances IL-6 levels in the murine ileum.

BACKGROUND: Recent studies suggest that ethanol use imposes a greater risk of trauma-associated intestinal injury than trauma alone. The initiating and regulatory factors for multiple organ dysfunction syndromes are not well defined, yet evidence points to the gut as a possible trigger of the systemic inflammatory cascade as well as a potential source of cytokines. In the current study, we hypothesized that ethanol administration would alter cytokine levels and intestinal infiltration by neutrophils within the ileum of mice exposed to burn injury (15% total body surface of dorsal skin). METHODS: Ileal samples were collected for histological assessment, myeloperoxidase quantitation and the protein presence of tumor necrosis factor alpha (TNFalpha), interleukin (IL-) 6, macrophage inflammatory protein-2 (MIP-2; CXCL2) and the anti-inflammatory cytokine, IL-10. Additional ileal tissue samples were examined for localization of the IL-6 immunoreactivity. RESULTS: We did not detect statistically significant cytokine/chemokine differences (MIP-2 and IL-10) between sham control and treatment conditions at either 2 or 24 hours. However, there was a significant decrease in TNFalpha at 24 hours in both burn injury alone and in combination with ethanol treatment conditions (p < 0.05). In addition, there was an increase in IL-6 levels at 24 hours in intestinal tissue obtained from mice subjected to a combination of acute ethanol and burn injury, compared to the mice receiving burn or sham injury (p < 0.001). Ileal homogenate increases in IL-6 at 24 hours were concurrent with decreased villus height in the ileum, but no discernable changes in neutrophil infiltration (myeloperoxidase activity levels) at either 2 or 24 hours. Additional immunocytochemical localization studies of ileal tissue revealed that there was a substantial increase of IL-6 in intestinal enterocytes subjected to both burn injury alone, or in combination with acute ethanol exposure. CONCLUSIONS: The present study suggests that acute ethanol exposure combined with burn injury enhances levels of IL-6 protein in the ileum. The enhanced levels of ileal IL-6 are likely due to enterocyte production of the cytokine.

CXCR4 chemokine receptor signaling mediates pain hypersensitivity in association with antiretroviral toxic neuropathy.

Nucleoside reverse transcriptase inhibitors (NRTIs) are known to produce painful neuropathies and to enhance states of pain hypersensitivity produced by HIV-1 infection. It has also been observed that in some neuropathic pain models, chemokines and their receptors are upregulated, perhaps contributing to the pain state. In order to understand if chemokines are involved in NRTI-mediated sensory neuropathies, we treated rats with the anti-retroviral drug, 2',3'-dideoxycytidine (ddC), which is known to produce an extended period of hyperalgesia and allodynia. Using in situ hybridization, we observed that under normal conditions, CXCR4 chemokine receptors were widely expressed by satellite glia in the dorsal root ganglia (DRG) and Schwann cells in the sciatic nerve. A limited number of DRG neurons also expressed CXCR4 receptors. The chemokine SDF-1/CXCL12 was similarly expressed in glial cells in the DRG and peripheral nerve. Following a single administration of ddC, expression levels of CXCR4 mRNA in glia and neurons and SDF-1 mRNA in glia increased considerably. The functional nature of increased CXCR4 mRNA expression was confirmed by measuring SDF-1 induced [Ca2+]i increases in acutely isolated DRG neurons and glia. In contrast, the expression of the chemokine receptors CCR2 and CCR5 did not change following ddC treatment. Pain hypersensitivity produced by ddC could be inhibited by treatment with the CXCR4 antagonist, AMD3100. Hence, we postulate that NRTIs produce pain hypersensitivity through the upregulation of CXCR4 signaling in the DRG. Increased numbers of CXCR4 receptors would also explain the synergism observed between NRTI treatment and the proalgesic effects of HIV-1 infection.