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Importance: Previous studies have demonstrated racial and ethnic inequities in medical student assessments, awards, and faculty promotions at academic medical centers. Few data exist about similar racial and ethnic disparities at the level of graduate medical education., Objective: To examine the association between race and ethnicity and performance assessments among a national cohort of internal medicine residents., Design, Setting, and Participants: This retrospective cohort study evaluated assessments of performance for 9026 internal medicine residents from the graduating classes of 2016 and 2017 at Accreditation Council of Graduate Medical Education (ACGME)-accredited internal medicine residency programs in the US. Analyses were conducted between July 1, 2020, and June 31, 2022., Main Outcomes and Measures: The primary outcome was midyear and year-end total ACGME Milestone scores for underrepresented in medicine (URiM [Hispanic only; non-Hispanic American Indian, Alaska Native, or Native Hawaiian/Pacific Islander only; or non-Hispanic Black/African American]) and Asian residents compared with White residents as determined by their Clinical Competency Committees and residency program directors. Differences in scores between Asian and URiM residents compared with White residents were also compared for each of the 6 competency domains as supportive outcomes., Results: The study cohort included 9026 residents from 305 internal medicine residency programs. Of these residents, 3994 (44.2%) were female, 3258 (36.1%) were Asian, 1216 (13.5%) were URiM, and 4552 (50.4%) were White. In the fully adjusted model, no difference was found in the initial midyear total Milestone scores between URiM and White residents, but there was a difference between Asian and White residents, which favored White residents (mean [SD] difference in scores for Asian residents: -1.27 [0.38]; P < .001). In the second year of training, White residents received increasingly higher scores relative to URiM and Asian residents. These racial disparities peaked in postgraduate year (PGY) 2 (mean [SD] difference in scores for URiM residents, -2.54 [0.38]; P < .001; mean [SD] difference in scores for Asian residents, -1.9 [0.27]; P < .001). By the final year 3 assessment, the gap between White and Asian and URiM residents' scores narrowed, and no racial or ethnic differences were found. Trends in racial and ethnic differences among the 6 competency domains mirrored total Milestone scores, with differences peaking in PGY2 and then decreasing in PGY3 such that parity in assessment was reached in all competency domains by the end of training., Conclusions and Relevance: In this cohort study, URiM and Asian internal medicine residents received lower ratings on performance assessments than their White peers during the first and second years of training, which may reflect racial bias in assessment. This disparity in assessment may limit opportunities for physicians from minoritized racial and ethnic groups and hinder physician workforce diversity.

Importance: Diversity in the medical workforce is critical to improve health care access and achieve equity for resource-limited communities. Despite increased efforts to recruit diverse medical trainees, there remains a large chasm between the racial and ethnic and socioeconomic composition of the patient population and that of the physician workforce., Objective: To analyze student attrition from medical school by sociodemographic identities., Design, Setting, and Participants: This retrospective cohort study included allopathic doctor of medicine (MD)-only US medical school matriculants in academic years 2014-2015 and 2015-2016. The analysis was performed from July to September 2021., Main Outcomes and Measures: The main outcome was attrition, defined as withdrawal or dismissal from medical school for any reason. Attrition rate was explored across 3 self-reported marginalized identities: underrepresented in medicine (URiM) race and ethnicity, low income, and underresourced neighborhood status. Logistic regression was assessed for each marginalized identity and intersections across the 3 identities., Results: Among 33 389 allopathic MD-only medical school matriculants (51.8% male), 938 (2.8%) experienced attrition from medical school within 5 years. Compared with non-Hispanic White students (423 of 18 213 [2.3%]), those without low income (593 of 25 205 [2.3%]), and those who did not grow up in an underresourced neighborhood (661 of 27 487 [2.4%]), students who were URiM (Hispanic [110 of 2096 (5.2%); adjusted odds ratio (aOR), 1.41; 95% CI, 1.13-1.77], non-Hispanic American Indian/Alaska Native/Native Hawaiian/Pacific Islander [13 of 118 (11.0%); aOR, 3.20; 95% CI, 1.76-5.80], and non-Hispanic Black/African American [120 of 2104 (5.7%); aOR, 1.41; 95% CI, 1.13-1.77]), those who had low income (345 of 8184 [4.2%]; aOR, 1.33; 95% CI, 1.15-1.54), and those from an underresourced neighborhood (277 of 5902 [4.6%]; aOR, 1.35; 95% CI, 1.16-1.58) were more likely to experience attrition from medical school. The rate of attrition from medical school was greatest among students with all 3 marginalized identities (ie, URiM, low income, and from an underresourced neighborhood), with an attrition rate 3.7 times higher than that among students who were not URiM, did not have low income, and were not from an underresourced neighborhood (7.3% [79 of 1086] vs 1.9% [397 of 20 353]; P < .001)., Conclusions and Relevance: This retrospective cohort study demonstrated a significant association of medical student attrition with individual (race and ethnicity and family income) and structural (growing up in an underresourced neighborhood) measures of marginalization. The findings highlight a need to retain students from marginalized groups in medical school.

Unlabelled: Clinical diagnosis of cyanide poisoning is complicated by the lack of an easy, convenient assay for cyanide concentration in blood. Therapy may be delayed with unconfirmed diagnosis because the conventional antidote to cyanide poisoning exposes patients to substantial risks. We developed a new spectrophotometric assay to measure cyanide by extraction into a sodium hydroxide trap, followed by the addition of exogenous methemoglobin as a colormetric indicator. Samples of blood from 15 healthy subjects and 5 patients who had received prolonged nitroprusside infusions were assayed. To optimize assay characteristics, methemoglobin concentrations, pH, temperature, incubation time, and buffer strengths were varied. Duplicate samples were assayed by using the polarographic method for assay validation. Over a range from 300 ng/mL to 7 microg/mL, the correlation between methods was r = 0.983. Interassay and intraassay variability were 5% and 2%, respectively. Samples drawn from the five patients and tested by using both methods yielded a correlation of r = 0.978. This new assay for cyanide in blood may greatly facilitate the diagnosis and treatment of cyanide ingestion. The use of methemoglobin as the colorimetric indicator in the assay contributes to its low cost and ease of use., Implications: Cyanide, an important factor in death from burn-related inhalation injury, is difficult and time-consuming to measure. We developed a new, rapid blood test for cyanide using methemoglobin as a colormetric indicator. A rapid, accessible test for cyanide may speed the diagnosis and treatment of cyanide poisoning.

We have characterized new aspects of macrofiber structure and assembly which provide a mechanism for macrofiber formation from fibers. After the formation of fibers, HbS forms macrofibers by the association of small, organized bundles of partially fused fibers. These macrofibers consist of double strands, packed into antiparallel rows, and are identical to double strands found in crystalline HbS, except that the double strands in macrofibers are axially displaced from their crystalline position and are twisted about the particle axis, whereas in crystals they are linear. In lateral views, electron micrographs of macrofibers show prominent sets of "rows." We use the number of these rows to designate a particular type of macrofiber. In this study we present micrographs of macrofibers with 3 to 11 rows visible in lateral views. Such particles contain from 20 to 200 double strands. The pitch of a macrofiber is coupled to the number of rows in a manner so that the angle between the molecules in the outermost double strand is always 1.8 degrees. This observation has led us to propose that the factor limiting the extent of lateral growth of macrofibers is distortions in bonding between the hemoglobin molecules in the outermost double strands. Similar considerations have provided an explanation of the factors that limit the lateral growth of fibers. Finally, we propose a simple mechanism for the formation of macrofibers from fibers. This mechanism postulates that integral numbers of fibers form specific types of macrofibers and has the virtue of conserving the polarity of the fibers.

Deoxyhemoglobin S fibers associate into bundles, or fascicles, that subsequently crystallize by a process of alignment and fusion. We have used electron microscopy to study the formation of fascicles and the changes in fiber packing that occur during the conversion of fascicles to crystals. The first event in crystallization involves fibers forming fascicles that are initially small and poorly ordered but, with time, become progressively larger and more highly ordered. After six to eight hours, the fibers in a fascicle form a crystalline lattice. The three-dimensional unit cell parameters of this lattice are a = 1300 A, b = 365 A, and c = 210 A (the a axis is parallel to the fiber axis). Fibers have an elliptical cross-section whose major and minor axes are 250 A and 185 A, respectively. When projected on to the unit cell vectors, these dimensions are 210 A and 155 A, so the unit cell dimension of 365 A implies that there are two fibers per unit cell. Theoretically, fibers could pair so that each member of the unit cell is oriented in the same direction (parallel) or opposite directions (antiparallel). Fourier transforms of electron micrographs (or models) cannot distinguish between these alternatives, since the two arrangements produce very similar intensity distributions. The orientation of the fibers was determined from cross-sections of the fascicles in which the fibers are seen end-on. In this view the images of the fibers are rotationally blurred because the fibers twist 30 degrees to 40 degrees about their helical axis through the 300 A to 400 A thick section. We have been able to remove the rotational blur from each of the fibers in the unit cell using the procedures described by Carragher et al. The deblurred images of the two fibers in the unit cell are related by mirror symmetry. This relationship means that the fibers are antiparallel. These observations suggest that crystallization of fibers in fascicles is mediated by assembly of the fibers into antiparallel pairs that contain equal numbers of double strands running in each direction.

We have examined the structure of hemoglobin S fibers, which are associated into large bundles, or fascicles. Electron micrographs of embedded and cross-sectioned fascicles provide an end-on view of the component fibers. The cross-sectional images are rotationally blurred as a result of the twist of the fiber within the finite thickness of the section. We have applied restoration techniques to recover a deblurred image of the fiber. The first step in this procedure involved correlation averaging images of cross-sections of individual fibers in order to improve the signal-to-noise ratio. The rotationally blurred image was then geometrically transformed to polar co-ordinates. In this space, the rotational blur is transformed into a linear blur. The linearly blurred image is the convolution of the unblurred image and a point spread function that can be closely approximated by a square pulse. Deconvolution in Fourier space, followed by remapping to Cartesian co-ordinates, produced a deblurred image of the original micrograph. The deblurred images indicate that the fiber is comprised of 14 strands of hemoglobin S. This result provides confirmation of the fiber structure determined using helical reconstruction techniques and indicates that the association of fibers into ordered arrays does not alter their molecular structure.