Improved Radiation Exposure Monitoring of Orthopaedic Residents After Institution of a Personalized Lead Protocol

Background:

Radiation exposure of orthopaedic residents should be accurately monitored to monitor and mitigate risk. The purpose of this study was to determine whether a personalized lead protocol (PLP) with a radiation monitoring officer would improve radiation exposure monitoring of orthopaedic surgery residents.

Materials and Methods:

This was a retrospective case-control study of 15 orthopaedic surgery residents monitored for radiation exposure during a 2-year period (March 2017 until February 2019). During the first 12-month period (phase 1), residents were given monthly radiation dosimeter badges and instructed to attach them daily to the communal lead aprons hanging outside the operating rooms. During the second 12-month period (phase 2), a PLP (PLP group) was instituted in which residents were given lead aprons embroidered with their individual names. A radiation safety officer was appointed who placed the badges monthly on all lead aprons and collected them at the end of the month, whereas faculty ensured residents wore their personalized lead apron. Data collected included fluoroscopy use time and radiation dosimeter readings during all orthopaedic surgeries in the study period.

Results:

There were 1,252 orthopaedic surgeries using fluoroscopy during phase 1 in the control group and 1,269 during phase 2 in the PLP group. The total monthly fluoroscopy exposure time for all cases averaged 190 minutes during phase 1 and 169 minutes during phase 2, with no significant difference between the groups (p < 0.45). During phase 1, 73.1% of the dosimeters reported radiation exposure, whereas during phase 2, 88.7% of the dosimeters reported radiation exposure (p < 0.001). During phase 1, the average monthly resident dosimeter exposure reading was 7.26 millirems (mrem) ± 37.07, vs. 19.00 mrem ± 51.16 during phase 2, which was significantly higher (p < 0.036).

Conclusions:

Institution of a PLP increased the compliance and exposure readings of radiation dosimeter badges for orthopaedic surgery residents, whereas the actual monthly fluoroscopy time did not change. Teaching hospitals should consider implementing a PLP to more accurately monitor exposure.

Level of Evidence:

3.

Implant Selection for Proximal Humerus Fractures

Proximal humerus fractures (PHF) are a common orthopedic injury; however, their treatment remains largely controversial with evidence supporting a wide array of treatments. Although many injuries can be treated nonoperatively, there has been much debate about surgical management of PHF. A detailed review of the literature was performed relative to operative management options specifically related to implant choices. Although no definitive answers are available regarding best practice, there is literature to guide operative decision-making and implant selection based on both patient- and surgeon-specific factors.

Characterization of the solubility of a poorly soluble hydroxylated metabolite in human urine and its implications for potential renal toxicity

The solubility, in human urine, of the major hydroxylated metabolite (M1) of an experimental cognition enhancer was characterized through a series of in vitro experiments in an effort to estimate the probability of crystalluria occurring following oral administration of the parent compound. The aim of these experiments was to determine if a safety margin existed between clinically observed urine concentrations and the solubility of M1. The mean urine concentrations of M1 in young and elderly subjects following oral administration of the parent compound at the highest doses tested, were 4865 +/- 2368 ng/mL and 2764 +/- 791 ng/mL, respectively. In vitro solubility experiments with M1 were conducted in drug-free human urine (37 degrees C) from four male and four female healthy subjects under conditions of high and low urine osmolality. Mean concentrations (n = 16) of M1 in human urine to which solid M1 was added, were 3656 +/- 621 ng/mL, 4678 +/- 1169 ng/mL and 5378 +/- 2474 ng/mL after stirring for 24, 48 and 72 h, respectively, indicating that the ex vivo mean solubility of M1 in human urine is no greater then approximately 5 microg/mL. Addition of solid M1 to urine from human subjects dosed with the parent compound resulted in mean urine M1 concentrations 23.5% greater than those observed in vivo. The results from both experiments indicated a significant overlap between urine concentrations of M1 in vivo following the highest oral administration of the parent drug and M1 solubility measured in vitro, suggesting a high potential for in vivo saturation of urine with M1 with subsequent precipitation, crystalluria, and nephrotoxicity. Consequently, the results of these studies have placed restrictions on the dose that could be administered during clinical development of this compound.

Multiple amylin receptors arise from receptor activity-modifying protein interaction with the calcitonin receptor gene product

Receptor activity-modifying proteins (RAMPs) are single-transmembrane proteins that transport the calcitonin receptor-like receptor (CRLR) to the cell surface. RAMP 1-transported CRLR is a calcitonin gene-related peptide (CGRP) receptor. RAMP 2- or RAMP 3-transported CRLR is an adrenomedullin receptor. The role of RAMPs beyond their interaction with CRLR, a class II G protein-coupled receptor, is unclear. In this study, we have examined the role of RAMPs in generating amylin receptor phenotypes from the calcitonin (CT) receptor gene product. Cotransfection of RAMP 1 or RAMP 3 with the human CT receptor lacking the 16-amino acid insert in intracellular domain 1 (hCTRI1-) into COS-7 cells induced specific 125I-labeled rat amylin binding. RAMP 2 or vector cotransfection did not cause significant increases in specific amylin binding. Competition-binding characterization of the RAMP-induced amylin receptors revealed two distinct phenotypes. The RAMP 1-derived amylin receptor demonstrated the highest affinity for salmon CT (IC50, 3.01 +/- 1.44 x 10(-10) M), a high to moderate affinity for rat amylin (IC50, 7.86 +/- 4.49 x 10(-9) M) and human CGRPalpha (IC50, 2.09 +/- 1.63 x 10(-8) M), and a low affinity for human CT (IC50, 4.47 +/- 0.78 x 10(-7) M). In contrast, whereas affinities for amylin and the CTs were similar for the RAMP 3-derived receptor, the efficacy of human CGRPalpha was markedly reduced (IC50, 1.12 +/- 0.45 x 10(-7) M; P <.05 versus RAMP 1). Functional cyclic AMP responses in COS-7 cells cotransfected with individual RAMPs and hCTRI1- were reflective of the phenotypes seen in competition for amylin binding. Confocal microscopic localization of c-myc-tagged RAMP 1 indicated that, when transfected alone, RAMP 1 almost exclusively was located intracellularly. Cotransfection with calcitonin receptor (CTR)I1- induced cell surface expression of RAMP 1. The results of experiments cross-linking 125I-labeled amylin to RAMP 1/hCTR-transfected cells with bis succidimidyl suberate were suggestive of a cell-surface association of RAMP 1 and the receptors. Our data suggest that in the CT family of receptors, and potentially in other class II G protein-coupled receptors, the cellular phenotype is likely to be dynamic in regard to the level and combination of both the receptor and the RAMP proteins.

Behavioral assessment of social performance: a rating system for social phobia

The Social Performance Rating Scale (SPRS) is a modification of the rating system for behavioral assessment of social skills, originally developed by Trower, P., Bryant, B., & Argyle, M. (1978). Social skills and mental health. Pittsburgh: University of Pittsburgh Press) and subsequently adapted by Turner and colleagues (e.g., Turner, S.M., Beidel, D.C., Dancu, C.V., & Keys, D.J. (1986). Psychopathology of social phobia and comparison to avoidant personality disorder. Journal of Abnormal Psychology, 95, 389-394). Designed to yield ratings of social performance appropriate for use in a socially phobic population and based on videotaped role plays, the five SPRS ratings are gaze, vocal quality, speech length, discomfort, and conversation flow. The sum of these ratings provides an internally consistent total score. In an initial study of the psychometric properties of the SPRS, three groups were assessed: individuals with social phobia, another anxiety disorder, or no psychological disorder. Inter-rater reliability for individual items and the total score proved excellent, and positive evidence for convergent, divergent, and criterion-related validity was obtained.

Characterization of amylin and calcitonin receptor binding in the mouse alpha-thyroid-stimulating hormone thyrotroph cell line

Recently, a high affinity amylin binding site was identified in the mouse alpha-TSH thyrotroph cell line. In this study, we have characterized binding sites for 125I-salmon calcitonin (125I-sCT), 125I-rat alpha-calcitonin gene-related peptide (125I-CGRP), and 125I-rat amylin in alpha-TSH cells. Using 125I-CGRP or 125I-rat amylin, equilibrium was rapidly reached, and binding was fully reversible. Competition binding revealed the relative potency of peptides was sCT>amylin, CGRP>>rCT, which is similar to the specificity profile of amylin receptors characterized in rat brain. Furthermore, specific binding of 125I-rat amylin and 125I-CGRP to membrane preparations was reduced by 52% and 39%, respectively, in the presence of 20 microM GTP-gamma-s, indicating a requirement of G protein coupling for high affinity binding. In contrast, 125I-sCT binding reached equilibrium more slowly, was essentially irreversible, and was unaltered by GTP-gamma-s. Competition binding studies using 125I-sCT as radioligand demonstrated only weak interaction by CGRP or amylin, consistent with other described CT receptors. Assessment of ligand-induced cAMP accumulation and intracellular calcium signaling revealed a relative specificity profile of sCT>rCT with little or no second messenger signaling stimulated by amylin or CGRP, consistent with a C1-CT receptor phenotype. RT-PCR amplification of messenger RNA indicated that the predominant isoform was the C1a CT receptor. In cross-linking studies, 125I-rat amylin and 125I-CGRP specifically labeled a major band of relative molecular mass (Mr) approximately 80K, being approximately 10 kDa higher than the major 125I-sCT binding protein. Full deglycosylation of N-linked carbohydrates with endoglycosidase F reduced the Mr of each of the labeled proteins to approximately 50K. Cross-linked amylin or CT receptors were immunoprecipitated with C-terminally directed antimouse or antirat CT receptor antibodies but were not immunoprecipitated with nonimmune sera or antihuman CT receptor antibodies. The current data demonstrate expression of two biochemically distinct receptor phenotypes in mouse alpha-TSH cells, a CT receptor phenotype and an amylin receptor phenotype that have highly similar protein backbones.

Electrophoretic mobility and glycosylation characteristics of heterogeneously expressed calcitonin receptors

The translated calcitonin receptor (CTR) complementary DNA sequences contain potential N-linked glycosylation sites within the extracellular N-terminus. We investigated the relative molecular mass (M(r)) and degree of N-linked glycosylation of five cloned CTRs (pig, rat C1a, rat C1b, human I1-ve, and human I1+ve), together with the pig hypothalamic CTR, to analyze the potential contribution of carbohydrate moieties to the molecular identity of these receptors. Receptors were cross-linked to 125I-salmon CT with the homobifunctional reagent bis(sulfosuccinimidyl) suberate. Autoradiographic analysis of the cross-linked receptors, following SDS-PAGE, revealed apparent M(r)S, ranging between 70,000 and 80,000 for the rat, human, and pig hypothalamic receptors. However, the cloned, expressed pig CTR was much smaller (approximately 58,000). The lower M(r) of the cloned pig CTR appeared to be due to absence of N-terminal residues, but this did not impact on ligand-receptor specificity when compared with the hypothalamic pig CTR. Cleavage under nondenaturing conditions of N-linked sugars from the CTRs using endoglycosidase F (Endo F), increased the electrophoretic mobility of all receptors, except the pig CTRs, by approximately 10 kDa. Under denaturing conditions, electrophoretic mobilities increased by approximately 30 kDa for the rat C1a, rat C1b, and humanI1-ve (expressed in human embryonic kidney-293 cells) CTRs and by approximately 20 kDa for the cloned pig, pig hypothalamic, and human CTR isoforms (expressed in baby hamster kidney cells). Competition binding studies using glycosylated and partially deglycosylated (nondenaturing conditions) receptor preparations demonstrated no significant differences in binding affinity or specificity. Thus the CTRs are N-linked glycoproteins whose degree of glycosylation is both cell-type and species dependent.

Cognitive biases in generalized social phobia

Judgmental biases for threat-relevant stimuli are thought to be important mechanisms underlying the etiology and maintenance of anxiety disorders. The authors hypothesized (a) that people with generalized social phobia (GSP) would rate negative social events but not nonsocial events as more probable and costly than would nonanxious controls (NACs) and (b) that cognitive behavioral treatment would decrease probability and cost estimates for social but not nonsocial events. Participants with GSP and NACs were assessed twice, 14 weeks apart, during which the former received cognitive behavioral therapy. Those with GSP evidenced socially relevant judgmental biases prior to treatment, and these were attenuated following treatment. Reduction in cost estimates for social events, but not in probability estimates, mediated improvement in social phobia. Results are discussed in light of emotional processing theory.

Evaluation of a brief cognitive-behavioral program for the prevention of chronic PTSD in recent assault victims

The efficacy of a brief prevention program (BP) aimed at arresting the development of chronic PTSD was examined with 10 recent female victims of sexual and nonsexual assault who received 4 sessions of a cognitive-behavioral program shortly after the assault. Their PTSD and depression severity was compared with that of 10 matched recent female assault victims who received repeated assessments of their trauma-related psychopathology (assessment control; AC). The BP program consisted of education about common reactions to assault and cognitive-behavioral procedures. Two months postassault, victims who received the BP program had significantly less severe PTSD symptoms than victims in the control condition; 10% of the former group met criteria for PTSD versus 70% of the latter group. Five and a half months postassault, victims in the BP group were significantly less depressed than victims in the AC group and had significantly less severe reexperiencing symptoms.

Evaluation of a brief cognitive-behavioral program for the prevention of chronic PTSD in recent assault victims

The efficacy of a brief prevention program (BP) aimed at arresting the development of chronic PTSD was examined with 10 recent female victims of sexual and nonsexual assault who received 4 sessions of a cognitive-behavioral program shortly after the assault. Their PTSD and depression severity was compared with that of 10 matched recent female assault victims who received repeated assessments of their trauma-related psychopathology (assessment control; AC). The BP program consisted of education about common reactions to assault and cognitive-behavioral procedures. Two months postassault, victims who received the BP program had significantly less severe PTSD symptoms than victims in the control condition; 10% of the former group met criteria for PTSD versus 70% of the latter group. Five and a half months postassault, victims in the BP group were significantly less depressed than victims in the AC group and had significantly less severe reexperiencing symptoms.

Enhanced reverse saturable absorption and optical limiting in heavy-atom-substituted phthalocyanines

The reverse saturable absorption and the optical-limiting response of metal phthalocyanines can be enhanced by use of the heavy-atom effect. Phthalocyanines containing heavy-metal atoms, such as In, Sn, and Pb, show a nearly factor-of-2 enhancement in the ratio of effective excited-state to ground-state absorption cross sections compared with those containing lighter atoms, such as Al and Si. In an f/8 optical geometry, homogeneous solutions of heavy-metal phthalocyanines, at 30% linear transmission, limit 8-ns 532-nm laser pulses to </=3 microJ (the energy for 50% probability of eye damage) for incident energies as high as 800 microJ.

Dissociation of immune capacity from nutritional status by triiodothyronine supplements in severe protein deficiency

Weanling mice were fed ad libitum from age 23 to 37 days either an 18 or an 0.6% protein diet. Half the animals in each dietary group received supplemental triiodothyronine (T3, 0.2 mg/kg diet). T3 increased the primary in vivo antibody response of protein-deficient mice to sheep red blood cells, as measured by both splenic plaque-forming cells (PFC) per 10(6) nucleated spleen cells and serum hemagglutinin titers. T3 also increased PFC/spleen in well-nourished mice. The effect on protein-deficient animals was achieved although nutritional status in these animals, as estimated by weight loss and carcass composition, was further impaired by T3 supplementation. These results support the hypothesis that immune functions can be improved independently of nutritional status in severe (wasting) malnutrition. Insofar as T3 was effective in a model of malnutrition that does not reduce serum total or free T3 levels, the phenomenon appears to represent a pharmacological action of the hormone.

Triiodothyronine improves the primary antibody response to sheep red blood cells in severely undernourished weanling mice

Three experiments were conducted in which weanling mice were fed a nutritionally complete diet either ad libitum or in restricted quantities such that they lost about 30% of their initial weight over a 14-day period. In Experiments 1 and 2, half the animals from each group received dietary triiodothyronine (T3) supplements. In Experiment 3, food-intake-restricted mice were fed graded levels of potassium iodide. Malnutrition reduced the number of nucleated cells per spleen, the number of splenic IgG plaque-forming cells (PFC) per 10(6) cells, and the serum antibody titers against sheep red blood cells. T3 supplements increased antibody titers, the number of nucleated cells per spleen, and both IgM and IgG PFC per 10(6) spleen cells in malnourished mice, but had no effect on well-nourished mice. The beneficial effect of T3 was not a result of improved protein, energy, or iodine status in the malnourished mice.

The effect of triiodothyronine on evanescent delayed hypersensitivity to sheep red blood cells and on the primary antibody response to trinitrophenylated Brucella abortus in severely undernourished weanling mice

Two experiments were conducted using weanling male CBA/J mice. Animals were fed for 14 days a nutritionally complete diet, either ad libitum, or in restricted amounts such that they lost about 30% of their weaning weight during the feeding period. Half the animals from each food intake group received 0.2 mg triiodothyronine (T3)/kg diet. Evanescent delayed hypersensitivity to sheep red blood cells (SRBC) was depressed by malnutrition but not influenced by T3 supplementation. T3 increased nucleated spleen cell number in mice immunized with trinitrophenylated Brucella abortus (TNP-BA). The number of splenic anti-TNP direct plaque-forming cells (PFCs) was decreased by malnutrition when expressed on a per spleen basis. T3 supplements increased splenic PFC number of malnourished mice when results were expressed either per spleen or per 10(6) cells, and increased PFCs per spleen in well-nourished mice. Serum anti-TNP agglutinin titres were unaffected by malnutrition and by T3. The results extend our previous observations as to the improvement by T3 of the primary anti-SRBC antibody response of malnourished weanling mice, and suggest that therapeutic hormonal treatment could be used to improve antibody responses of malnourished individuals. The mechanism of the effect of T3 is unknown, but the lack of effect on delayed hypersensitivity to SRBC implies that T3 (when administered at the dosage of the present protocol) acts on only some immune cells and does not exert a generalized adjuvant effect.