Emergency department management of patients with rectal bleeding.

Rectal bleeding accounts for approximately 1 out of every 1000 United States emergency department visits annually. The causes of rectal bleeding are broad, and can range from the benign to the life-threating. This review provides foundational knowledge on rectal bleeding as well as evidence-based recommendations for its evaluation and initial management in the emergency department. Anatomic considerations are discussed, and the differential diagnosis based on risk factors such as age and comorbid conditions is presented. Treatment recommendations based on the presumed diagnosis as well as the evidence associated with their use are also described. Decision-making, including disposition based on laboratory results, imaging studies, and application of risk scoring calculations is also discussed.

Competitive measurement of ß/α naphthyl phosphate catalytic efficiency by phosphatases utilizing quantitative NMR.

The two constitutional isomers of naphthyl phosphate have different steric properties, analogous to those of phosphotyrosine versus phosphoserine/threonine within a peptide or protein. The ratios of their respective rates of hydrolysis, assayed by measuring rates of inorganic phosphate release, have been used to probe the steric requirements around the active sites of many phosphatases in the literature. We report an NMR-based competitive method that is simpler to execute and has other advantages. It directly yields the ratio of catalytic efficiencies (V/K) of the two substrates, a more biologically relevant comparison than the ratio of initial rates (vo) or maximal rates (Vmax). The competitive method ensures that temperature, pH, enzyme and substrate concentrations, and the presence of any potential inhibitors are identical and will not skew the results. The method can be easily applied at any chosen temperature or pH, and to mutants, or under any other condition that might influence protein conformation and, thus, substrate specificity. It provides a facile screening method to select conditions for a detailed phosphopeptide screen to provide deeper insight into substrate preference.

Necrotizing Mediastinitis Following Dental Extraction: A Case Report.

INTRODUCTION: Necrotizing mediastinitis is a rare complication following a dental procedure. It is frequently lethal and requires prompt diagnosis with advanced imaging, administration of broad-spectrum antimicrobials, and early surgical consultation. CASE REPORT: A 19-year-old, otherwise healthy male presented to the emergency department with chest pain, muffled voice, and facial and neck swelling six days following dental extraction. He was found to have a retropharyngeal abscess causing necrotizing mediastinitis and septic shock. The patient was started on broad-spectrum antimicrobials, required 10 surgical procedures, and experienced a prolonged hospitalization. CONCLUSION: Consider necrotizing mediastinitis in patients presenting with chest pain and signs of retropharyngeal infection after dental procedures. Prompt imaging, antimicrobial therapy, and surgical consultation is critical in treating this frequently fatal disease.

Significant Loop Motions in the SsoPTP Protein Tyrosine Phosphatase Allow for Dual General Acid Functionality.

Conformational dynamics are important factors in the function of enzymes, including protein tyrosine phosphatases (PTPs). Crystal structures of PTPs first revealed the motion of a protein loop bearing a conserved catalytic aspartic acid, and subsequent nuclear magnetic resonance and computational analyses have shown the presence of motions, involved in catalysis and allostery, within and beyond the active site. The tyrosine phosphatase from the thermophilic and acidophilic Sulfolobus solfataricus (SsoPTP) displays motions of its acid loop together with dynamics of its phosphoryl-binding P-loop and the Q-loop, the first instance of such motions in a PTP. All three loops share the same exchange rate, implying their motions are coupled. Further evidence of conformational flexibility comes from mutagenesis, kinetics, and isotope effect data showing that E40 can function as an alternate general acid to protonate the leaving group when the conserved acid, D69, is mutated to asparagine. SsoPTP is not the first PTP to exhibit an alternate general acid (after VHZ and TkPTP), but E40 does not correspond to the sequence or structural location of the alternate general acids in those precedents. A high-resolution X-ray structure with the transition state analogue vanadate clarifies the role of the active site arginine R102, which varied in structures of substrates bound to a catalytically inactive mutant. The coordinated motions of all three functional loops in SsoPTP, together with the function of an alternate general acid, suggest that catalytically competent conformations are present in solution that have not yet been observed in crystal structures.

Gamma-radiation upregulates MHC class I/II and ICAM-I molecules in multiple myeloma cell lines and primary tumors.

The gamma-irradiation of normal cells causes an increased synthesis of specific proteins. However, few studies have described the effects of high doses of irradiation on the expression of cell surface antigens in tumor cells. This study analyzed the effects of high doses of gamma-irradiation on the surface antigen expression of Major Histocompatability Complex (MHC) class I/II and intercellular adhesion molecule-1 (ICAM-I) in human multiple myeloma (MM) cell lines ARP-1, ARK-RS, and 10 MM primary tumors. The expression of surface antigens was evaluated by fluorescence-activated cell sorter analysis at different time points, following the exposure to high doses of gamma-irradiation. Doses of 10,000 and 15,000 cGy were not sufficient to totally block cell replication in both cell lines and primary tumors; cell replication was able to be inhibited completely only at 18,000 cGy. Lower doses (10,000 cGy) and lethal doses of irradiation (i.e., 15,000 and 18,000 cGy) increased the expression of all surface antigens present on the cells before irradiation. Essentially, such upregulation was shown to be dose dependent, with higher radiation doses resulting in higher antigen expression. Furthermore, when the kinetics of this upregulation were studied 3 and 6 d after irradiation, there was a constant increase in antigen expression in MM cells. These findings suggest that upregulation of costimulatory molecules, such as of MHC class I/II antigens and ICAM-I molecules in MM patients treated by gamma-radiation, can increase the immunogenicity of the tumor cells. In light of these findings, radiotherapy combined with immunotherapy might be considered in relapsing patients after receiving the standard treatment.

Characterization of the immune response to DNA vaccination strategies for schistosomiasis candidate antigen, Sm-p80 in the baboon.

Even though schistosomicidal agents and other control measures, including public hygiene and snail control exist, development of an efficacious vaccine still remains the most potentially powerful method for control of schistosomiasis. In our continuing efforts to develop a vaccine against schistosomiasis, we have selected a vaccine candidate (Sm-p80), which plays an important role in the immune evasion process of the parasite. Sm-p80 has been shown to confer up to 60% protection in mice following experimental infection. In this initial study, we have used Sm-p80 plus the Th1 response promoting cytokine, interleukin-2 (IL-2), in a DNA immunogen formulation. The vaccine was tested for its safety and immunogenicity in a baboon model of schistosomiasis. The vaccine generated a Th1 type Sm-p80-specific response in baboons with IgG(1)/IgG(2) ratios of less than 1.0. No detectable IgG(3) or IgG(4) anti-Sm-p80 responses were present in the immunized baboons. The antibodies to Sm-p80 were able to kill up to 35% schistosomula in vitro in the presence of complement. These results although preliminary suggest the potential of Sm-p80 as a viable vaccine candidate for schistosomiasis.

Induction of protective immunity against Schistosoma mansoni via DNA priming and boosting with the large subunit of calpain (Sm-p80): adjuvant effects of granulocyte-macrophage colony-stimulating factor and interleukin-4.

Considerable morbidity and mortality result from schistosomiasis, an affliction affecting an estimated 200 million people. Although schistosomicidal drugs and other control measures (including public hygiene and snail control) exist, the advent of an efficacious vaccine remains the most potentially powerful means for controlling this disease. We have targeted a vaccine candidate (large subunit of calpain, Sm-p80) because of its consistent immunogenicity, protective potential, and integral role in surface membrane biogenesis of schistosomes. Since surface membrane renewal appears to be one of the major phenomena employed by schistosomes to evade the host's immune system; an immune response directed against Sm-p80 should render the parasite susceptible to immune clearance from the host by both providing a focus of attack and by potentially impairing the membrane repair process. In the present study, we have employed DNA immunization protocols using Sm-p80 with plasmids encoding granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-4 (IL-4). Sm-p80 by itself provided 39% protection (P = < or =0.0001) against challenge infection in C57BL/6 mice. This protection was increased to 44% (P = < or =0.0001) when the plasmid encoding GM-CSF was coadministered with Sm-p80 DNA. Coinjection of plasmid DNA encoding IL-4 with Sm-p80 DNA yielded a protection level of 42% (P = < or =0.0001). Statistically, the protection conferred by including GM-CSF, but not IL-4, was significantly greater than that when only Sm-p80 was used. Sm-p80 DNA by itself elicited strong responses that include IgG2A and IgG2B antibody isotypes. The introduction of GM-CSF DNA with Sm-p80 DNA led to distinct increases in total IgG and IgG1 titers, whereas the coadministration of IL-4 DNA with Sm-p80 DNA resulted in a slight elevation of IgG1 and IgG3 titers and in some reduction of IgG2A and IgG2B titers. Our data again indicate that Sm-p80 can be an excellent candidate for a schistosomiasis vaccine.

Enhancement of Sm-p80 (large subunit of calpain) induced protective immunity against Schistosoma mansoni through co-delivery of interleukin-2 and interleukin-12 in a DNA vaccine formulation.

Schistosomiasis afflicts an estimated 200 million people in 76 countries and an additional 600 million people are at risk of acquiring this infection. Even though effective anthelmintic treatment and snail eradication control programs exist, the discovery of an effective vaccine still remains the most potentially powerful means of control for this disease. We have concentrated on a vaccine candidate (large subunit of calpain or Sm-p80) because of its potential in conferring protection against challenge infection and its pivotal role in surface membrane biogenesis of schistosomes. Since surface membrane renewal is a major phenomenon employed by hemohelminths to evade host immune system; an immune response directed against Sm-p80 should make the parasite prone to immune clearance from the host by both providing a well-targeted attack and by potentially inhibiting the surface membrane biogenesis process. In the present study, we have utilized DNA immunization protocols using Sm-p80 with plasmids encoding interleukin-2 (IL-2) and interleukin-12 (IL-12). Sm-p80 by itself provided a 39% protection (P