Physician bias refers to the unconscious negative perceptions that physicians have of patients or their conditions. Medical schools and residency programs often incorporate training to reduce biases ...among their trainees. In order to assess trends and organize available literature, we conducted a scoping review with a goal to categorize different biases that are studied within medical student (MS), resident (Res) and mixed populations (MS and Res). We also characterized these studies based on their research goal as either documenting evidence of bias (EOB), bias intervention (BI) or both. These findings will provide data which can be used to identify gaps and inform future work across these criteria.
Online databases (PubMed, PsycINFO, WebofScience) were searched for articles published between 1980 and 2021. All references were imported into Covidence for independent screening against inclusion criteria. Conflicts were resolved by deliberation. Studies were sorted by goal: 'evidence of bias' and/or 'bias intervention', and by population (MS or Res or mixed) andinto descriptive categories of bias.
Of the initial 806 unique papers identified, a total of 139 articles fit the inclusion criteria for data extraction. The included studies were sorted into 11 categories of bias and showed that bias against race/ethnicity, specific diseases/conditions, and weight were the most researched topics. Of the studies included, there was a higher ratio of EOB:BI studies at the MS level. While at the Res level, a lower ratio of EOB:BI was found.
This study will be of interest to institutions, program directors and medical educators who wish to specifically address a category of bias and identify where there is a dearth of research. This study also underscores the need to introduce bias interventions at the MS level.
Hydrogen Sulfide Oxidation by Myoglobin Bostelaar, Trever; Vitvitsky, Victor; Kumutima, Jacques ...
Journal of the American Chemical Society,
07/2016, Letnik:
138, Številka:
27
Journal Article
Recenzirano
Odprti dostop
Enzymes in the sulfur network generate the signaling molecule, hydrogen sulfide (H2S), from the amino acids cysteine and homocysteine. Since it is toxic at elevated concentrations, cells are equipped ...to clear H2S. A canonical sulfide oxidation pathway operates in mitochondria, converting H2S to thiosulfate and sulfate. We have recently discovered the ability of ferric hemoglobin to oxidize sulfide to thiosulfate and iron-bound hydropolysulfides. In this study, we report that myoglobin exhibits a similar capacity for sulfide oxidation. We have trapped and characterized iron-bound sulfur intermediates using cryo-mass spectrometry and X-ray absorption spectroscopy. Further support for the postulated intermediates in the chemically challenging conversion of H2S to thiosulfate and iron-bound catenated sulfur products is provided by EPR and resonance Raman spectroscopy in addition to density functional theory computational results. We speculate that the unusual sensitivity of skeletal muscle cytochrome c oxidase to sulfide poisoning in ethylmalonic encephalopathy, resulting from the deficiency in a mitochondrial sulfide oxidation enzyme, might be due to the concentration of H2S by myoglobin in this tissue.
Hydrogen sulfide is a critical signaling molecule, but high concentrations cause cellular toxicity. A four-enzyme pathway in the mitochondrion detoxifies H2S by converting it to thiosulfate and ...sulfate. Recent studies have shown that globins like hemoglobin and myoglobin can also oxidize H2S to thiosulfate and hydropolysulfides. Neuroglobin, a globin enriched in the brain, was reported to bind H2S tightly and was postulated to play a role in modulating neuronal sensitivity to H2S in conditions such as stroke. However, the H2S reactivity of the coordinately saturated heme in neuroglobin is expected a priori to be substantially lower than that of the 5-coordinate hemes present in myoglobin and hemoglobin. To resolve this discrepancy, we explored the role of the distal histidine residue in muting the reactivity of human neuroglobin toward H2S. Ferric neuroglobin is slowly reduced by H2S and catalyzes its inefficient oxidative conversion to thiosulfate. Mutation of the distal His64 residue to alanine promotes rapid binding of H2S and its efficient conversion to oxidized products. X-ray absorption, EPR, and resonance Raman spectroscopy highlight the chemically different reaction options influenced by the distal histidine ligand. This study provides mechanistic insights into how the distal heme ligand in neuroglobin caps its reactivity toward H2S and identifies by cryo-mass spectrometry a range of sulfide oxidation products with 2–6 catenated sulfur atoms with or without oxygen insertion, which accumulate in the absence of the His64 ligand.
The approximation of euglycemia is the most effective means of preventing diabetic complications, which is achieved through effective insulin delivery. Recent reports indicate that insulin phenolic ...preservatives, which are found in all commercial insulin formulations, are cytotoxic, pro-inflammatory and induce secondary fibrosis. Therefore, we hypothesize that these preservatives induce an inflammatory response at the site of insulin infusion leading to diminished glycemic control and adverse pharmacokinetic outcomes. Insulin degradation by inflammatory cell proteases was quantitated following protease treatment in vitro. A modified murine air pouch model was utilized to evaluate the relative inflammatory responses following infusions of saline, insulin preservatives, and insulin, utilizing the adjuvant irritant thioglycolate. Blood glucose levels were monitored in diabetic mice with and without air pouch irritation. A pharmacokinetic analysis evaluated insulin effectiveness for diabetic mice between these two conditions. Inflammatory cells are significantly present in insulin preservative-induced inflammation, which effects diminished blood glucose control by both insulin uptake and degradation. Insulin containing these preservatives resulted in similar degrees of inflammation as observed with the irritant thioglycolate. These studies imply that the preservative agents found in commercial insulin formulations induce an intense localized inflammatory reaction. This inflammatory reaction may be responsible for the premature failure of insulin infusion devices. Future studies directed at reducing this inflammatory reaction may prove to be an important step in extending the lifespan of insulin infusion devices.
Exposing cells to excess metal concentrations well beyond the cellular quota is a powerful tool for understanding the molecular mechanisms of metal homeostasis. Such improved understanding may enable ...bioengineering of organisms with improved nutrition and bioremediation capacity. We report here that Chlamydomonas reinhardtii can accumulate manganese (Mn) in proportion to extracellular supply, up to 30-fold greater than its typical quota and with remarkable tolerance. As visualized by X-ray fluorescence microscopy and nanoscale secondary ion MS (nanoSIMS), Mn largely co-localizes with phosphorus (P) and calcium (Ca), consistent with the Mn-accumulating site being an acidic vacuole, known as the acidocalcisome. Vacuolar Mn stores are accessible reserves that can be mobilized in Mn-deficient conditions to support algal growth. We noted that Mn accumulation depends on cellular polyphosphate (polyP) content, indicated by 1) a consistent failure of C. reinhardtii vtc1 mutant strains, which are deficient in polyphosphate synthesis, to accumulate Mn and 2) a drastic reduction of the Mn storage capacity in P-deficient cells. Rather surprisingly, X-ray absorption spectroscopy, EPR, and electron nuclear double resonance revealed that only little Mn2+ is stably complexed with polyP, indicating that polyP is not the final Mn ligand. We propose that polyPs are a critical component of Mn accumulation in Chlamydomonas by driving Mn relocation from the cytosol to acidocalcisomes. Within these structures, polyP may, in turn, escort vacuolar Mn to a number of storage ligands, including phosphate and phytate, and other, yet unidentified, compounds.
Background:
Effective exogenous insulin delivery is the cornerstone of insulin dependent diabetes mellitus management. Recent literature indicates that commercial insulin-induced tissue reaction and ...cellular cytotoxicity may contribute to variability in blood glucose as well as permanent loss of injection or infusion site architecture and function. It is well accepted that insulin formulations are susceptible to mechanical and chemical stresses that lead to insulin fibril formation. This study aims to characterize in vitro and in vivo toxicity, as well as pro-inflammatory activity of insulin fibrils.
Method:
In vitro cell culture evaluated cytotoxicity and fibril uptake by macrophages and our modified murine air-pouch model quantified inflammatory activity. The latter employed FLOW cytometry and histopathology to characterize fibril-induced inflammation in vivo, which included fibril uptake by inflammatory phagocytes.
Results:
These studies demonstrated that insulin derived fibrils are cytotoxic to cells in vitro. Furthermore, inflammation is induced in the murine air-pouch model in vivo and in response, macrophages uptake fibrils both in vitro and in vivo.
Conclusions:
Administration of insulin fibrils can lead to cytotoxicity in macrophages. In vivo data demonstrate insulin fibrils to be pro-inflammatory which over time can lead to cumulative cell/tissue toxicity, inflammation, and destructive wound healing. Long term, these tissue reactions could contribute to loss of insulin injection site architecture and function.
Spider silks have unique mechanical properties but current efforts to duplicate those properties with recombinant proteins have been unsuccessful. This study was designed to develop a single process ...to spin fibers with excellent and consistent mechanical properties. As-spun fibers produced were brittle, but by stretching the fibers the mechanical properties were greatly improved. A water-dip or water-stretch further increased the strength and elongation of the synthetic spider silk fibers. Given the promising results of the water stretch, a mechanical double-stretch system was developed. Both a methanol/water mixture and an isopropanol/water mixture were independently used to stretch the fibers with this system. It was found that the methanol mixture produced fibers with high tensile strength while the isopropanol mixture produced fibers with high elongation.
Mitochondrial 2Fe-2S cluster biosynthesis is driven by the coordinated activities of the Iron–Sulfur Cluster (ISC) pathway protein machinery. Within the ISC machinery, the protein that provides a ...structural scaffold on which 2Fe-2S clusters are assembled is the ISCU protein in humans; this protein is referred to as the “Scaffold” protein. Truncation of the C-terminal portion of ISCU causes the fatal disease “ISCU Myopathy”, which exhibits phenotypes of reduced Fe-S cluster assembly in cells. In this report, the yeast ISCU ortholog “Isu1” has been characterized to gain a better understanding of the role of the scaffold protein in relation to 2Fe-2S assembly and ISCU Myopathy. Here we explored the biophysical characteristics of the C-terminal region of Isu1, the segment of the protein that is truncated on the human ortholog during the disease ISCU Myopathy. We characterized the role of this region in relation to iron binding, protein stability, assembly of the ISC multiprotein complex required to accomplish Fe-S cluster assembly, and finally on overall cell viability. We determined the Isu1 C-terminus is essential for the completion of the Fe-S cluster assembly but serves a function independent of protein iron binding.
Little is known about iron efflux transporters within bacterial systems. Recently, the participation of Bacillus subtilis PfeT, a P1B4-ATPase, in cytoplasmic Fe2+ efflux has been proposed. We report ...here the distinct roles of mycobacterial P1B4-ATPases in the homeostasis of Co2+ and Fe2+. Mutation of Mycobacterium smegmatis ctpJ affects the homeostasis of both ions. Alternatively, an M. tuberculosis ctpJ mutant is more sensitive to Co2+ than Fe2+, whereas mutation of the homologous M. tuberculosis ctpD leads to Fe2+ sensitivity but no alterations in Co2+ homeostasis. In vitro, the three enzymes are activated by both Fe2+ and Co2+ and bind 1 eq of either ion at their transport site. However, equilibrium binding affinities and activity kinetics show that M. tuberculosis CtpD has higher affinity for Fe2+ and twice the Fe2+-stimulated activity than the CtpJs. These parameters are paralleled by a lower activation and affinity for Co2+. Analysis of Fe2+ and Co2+ binding to CtpD by x-ray absorption spectroscopy shows that both ions are five- to six-coordinate, constrained within oxygen/nitrogen environments with similar geometries. Mutagenesis studies suggest the involvement of invariant Ser, His, and Glu residues in metal coordination. Interestingly, replacement of the conserved Cys at the metal binding pocket leads to a large reduction in Fe2+ but not Co2+ binding affinity. We propose that CtpJ ATPases participate in the control of steady state Fe2+ levels. CtpD, required for M. tuberculosis virulence, is a high affinity Fe2+ transporter involved in the rapid response to iron dyshomeostasis generated upon redox stress.
The purpose of this study was to determine a method to purify recombinant hagfish intermediate filament proteins, alpha and gamma, in a scalable manner. The study succeeded by having an increase in ...protein recovery of up to 35% when comparing centrifuge purification and the developed tangential flow purification. The proteins were approximately the same purity of 70% pure but further purification increased the purity of the proteins by 16%, based on ImageJ analysis. The developed tangential flow filtration purification and final purification methods could be easily scaled up to meet industry scale purification needs. The scaled-up processes described in this study did not interfere with fiber production or formation, indicating the methods can produce usable proteins for material development.
•Recombinant hagfish slime intermediate filaments expressed as inclusion body proteins in E. coli with high expression.•Process developed to scale up from laboratory to pilot or industrial levels by replacing centrifugation with TFF.•Additional purification to unfold proteins to release contaminants improved purity by up to 16% to a final purity of 86%.•Initial and additionally purified proteins were able to be solubilized and form fibers with decent mechanical properties.
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