Tailoring Phosphonium Ionic Liquids for a Liquid-Liquid Phase Transition.

The existence of more than one liquid state in a single-component system remains the most intriguing physical phenomenon. Herein, we explore the effect of cation self-assembly on ion dynamics in the vicinity of liquid-liquid and liquid-glass transition of tetraalkyl phosphonium ([Pmmm,n]+, m = 4, 6; n = 2-14) ionic liquids. We found that nonpolar local domains formed by 14-carbon alkyl chains are crucial in obtaining two supercooled states of different dynamics within a single ionic liquid. Although the nano-ordering, confirmed by Raman spectroscopy, still occurs for shorter alkyl chains (m = 6, n < 14), it does not bring calorimetric evidence of LLT. Instead, it results in peculiar behavior of ion dynamics near the liquid-glass transition and 20-times smaller size of the dynamic heterogeneity compared to imidazolium ionic liquids. These results represent a crucial step toward understanding the nature of the LLT phenomenon and offer insight into the design of efficient electrolytes based on ionic liquids revealing self-assembly behavior.

Systematic calculation of finite-time mixed singular vectors and characterization of error growth for persistent coherent atmospheric disturbances over Eurasia.

Singular vectors (SVs) have long been employed in the initialization of ensemble numerical weather prediction (NWP) in order to capture the structural organization and growth rates of those perturbations or "errors" associated with initial condition errors and instability processes of the large scale flow. Due to their (super) exponential growth rates and spatial scales, initial SVs are typically combined empirically with evolved SVs in order to generate forecast perturbations whose structures and growth rates are tuned for specified lead-times. Here, we present a systematic approach to generating finite time or "mixed" SVs (MSVs) based on a method for the calculation of covariant Lyapunov vectors and appropriate choices of the matrix cocycle. We first derive a data-driven reduced-order model to characterize persistent geopotential height anomalies over Europe and Western Asia (Eurasia) over the period 1979-present from the National Centers for Environmental Prediction v1 reanalysis. We then characterize and compare the MSVs and SVs of each persistent state over Eurasia for particular lead-times from a day to over a week. Finally, we compare the spatiotemporal properties of SVs and MSVs in an examination of the dynamics of the 2010 Russian heatwave. We show that MSVs provide a systematic approach to generate initial forecast perturbations projected onto relevant expanding directions in phase space for typical NWP forecast lead-times.

Determining the Ratio of Wedge Height to Degree of Correction for Anterior Tibial Closing Wedge Osteotomies for Excessive Posterior Tibial Slope.

BACKGROUND: Anterior closing wedge osteotomy of the proximal tibia may be considered in revision anterior cruciate ligament (ACL) reconstruction surgery for patients with excessive posterior tibial slope (PTS). PURPOSE: (1) To determine the ratio of wedge thickness to degrees of correction for supratubercle (ST) versus transtubercle (TT) osteotomies for anterior closing wedge osteotomies and (2) to evaluate the accuracy of ST and TT osteotomies in achieving slope correction. STUDY DESIGN: Controlled laboratory study. METHODS: The computed tomography (CT) scans of 38 knees in 37 patients undergoing revision ACL reconstruction were used to simulate both ST and TT osteotomies. A 10° wedge was simulated in all CT models. The height of the wedge along the anterior tibia was recorded for each of the 2 techniques. The ratio of wedge height to achieved degree of correction was calculated. ST and TT osteotomies were performed on 3-dimensional (3D)-printed tibias of the 12 patients from the study group with the greatest PTS, after the desired degree of correction was determined. Pre- and postosteotomy slopes were measured for each tibia, and the actual change in slope was compared with the intended slope correction. RESULTS: According to CT measurements, the ratio of wedge height to degree of correction was 0.99 ± 0.07 mm/deg for the ST osteotomy and 0.83 ± 0.06 mm/deg for the TT osteotomy (P < .001). When these ratios were used to perform simulated osteotomies on the twelve 3D-printed tibias, the mean slope correction was within 1° to 2° of the intended slope correction, regardless of osteotomy location (ST or TT) or whether slope was measured on the medial or lateral plateau. The ST technique tended to undercorrect and the TT technique tended to overcorrect. CONCLUSION: When anterior tibial closing wedge osteotomies were removed to correct excessive PTS, removing a wedge with a ratio of 1 mm of wedge height for every 1° of intended correction for an ST technique and a ratio of 0.8 mm to 1° for a TT technique resulted in overall average slope correction within 1° to 2° of the target. CLINICAL RELEVANCE: The calculated ratios will allow clinicians to more accurately correct PTS when performing anterior closing wedge tibial osteotomy.

Anterior Cruciate Ligament Revision Reconstruction.

Revision anterior cruciate ligament (ACL) reconstruction is used in patients with recurrent instability after primary ACL reconstruction. Identifying the etiology of graft failure is critical to the success of revision reconstruction. The most common etiologies include technical errors, trauma, failure to recognize concomitant injuries, young age, incomplete rehabilitation, and hardware failure. Patients should undergo a complete history and physical examination with a specific focus on previous injury mechanism and surgical procedures. A revision ACL reconstruction is a technically demanding procedure, and the surgeon should be prepared to address bone tunnel osteolysis, concurrent meniscal, ligamentous, or cartilage lesions, and limb malalignment. Surgical techniques described in this article include both single-stage and two-stage reconstruction procedures. Rates of return to sport after a revision reconstruction are lower than after primary reconstruction. Future research should be focused on improving both single-stage and two-stage revision techniques, as well as concomitant procedures to address limb malalignment and associated injuries.

Derivation of delay equation climate models using the Mori-Zwanzig formalism.

Models incorporating delay have been frequently used to understand climate variability phenomena, but often the delay is introduced through an ad hoc physical reasoning, such as the propagation time of waves. In this paper, the Mori-Zwanzig formalism is introduced as a way to systematically derive delay models from systems of partial differential equations and hence provides a better justification for using these delay-type models. The Mori-Zwanzig technique gives a formal rewriting of the system using a projection onto a set of resolved variables, where the rewritten system contains a memory term. The computation of this memory term requires solving the orthogonal dynamics equation, which represents the unresolved dynamics. For nonlinear systems, it is often not possible to obtain an analytical solution to the orthogonal dynamics and an approximate solution needs to be found. Here, we demonstrate the Mori-Zwanzig technique for a two-strip model of the El Niño Southern Oscillation (ENSO) and explore methods to solve the orthogonal dynamics. The resulting nonlinear delay model contains an additional term compared to previously proposed ad hoc conceptual models. This new term leads to a larger ENSO period, which is closer to that seen in observations.

Basin bifurcations, oscillatory instability and rate-induced thresholds for Atlantic meridional overturning circulation in a global oceanic box model.

The Atlantic meridional overturning circulation (AMOC) transports substantial amounts of heat into the North Atlantic sector, and hence is of very high importance in regional climate projections. The AMOC has been observed to show multi-stability across a range of models of different complexity. The simplest models find a bifurcation associated with the AMOC 'on' state losing stability that is a saddle node. Here, we study a physically derived global oceanic model of Wood et al. with five boxes, that is calibrated to runs of the FAMOUS coupled atmosphere-ocean general circulation model. We find the loss of stability of the 'on' state is due to a subcritical Hopf for parameters from both pre-industrial and doubled CO2 atmospheres. This loss of stability via subcritical Hopf bifurcation has important consequences for the behaviour of the basin of attraction close to bifurcation. We consider various time-dependent profiles of freshwater forcing to the system, and find that rate-induced thresholds for tipping can appear, even for perturbations that do not cross the bifurcation. Understanding how such state transitions occur is important in determining allowable safe climate change mitigation pathways to avoid collapse of the AMOC.

Orthopaedic Surgery Resident Financial Literacy: An Assessment of Knowledge in Debt, Investment, and Retirement Savings.

Most orthopedic residents carry significant debt and may enter their practice with little knowledge of business management, minimal retirement savings, and overall poor financial literacy. This study aimed to gauge financial literacy, debt, and retirement planning in United States orthopedic surgery residents. Willingness to participate in formalized financial education was also assessed. Eighty-five allopathic orthopedic surgery residents in the United States completed a 14-question anonymous online survey in 2016. The survey assessed demographic data, self-assessed financial knowledge, amount of credit card debt and loans, preparation for retirement, and willingness to participate in formal didactic education on these topics. Most respondents derive their financial knowledge from personal research (51%), whereas only 4 per cent have a formal curriculum. Despite most respondents reporting more than $200,000 in outstanding loans, only 31 per cent create and stick to a budget. Few programs offer retirement advice, and 48 per cent of respondents save $0 toward retirement. Eighty-five per cent of residents expressed interest in learning about personal investment, savings, and retirement planning. Orthopedic surgery residents carry significant debt and do not achieve their high-income potential until disproportionately later in life. Only 4 per cent of residents have formal training in investing, personal finance, or retirement despite a majority who desire such a curriculum. In fact, almost 75 per cent of those surveyed felt less prepared for retirement than their peers outside of medical training. This study suggests a role for formal financial education in the orthopedic curriculum to prepare residents for retirement, improve financial literacy, and enhance debt management.

Administration of intravenous antibiotics in patients with open fractures is dependent on emergency room triaging.

BACKGROUND: Recent literature has demonstrated that emergent administration of antibiotics is perhaps more critical than even emergent debridement. Most recent studies recommend patients receive antibiotics no later than 1 hour after injury to prevent infection. The objective of this study is to evaluate the time to antibiotic administration after patients with open fractures arrive to a trauma center depending on triaging team. METHODS: A retrospective study at a level 1 Trauma center from January 2013 to March 2015 where 117 patients with open fractures were evaluated. Patients who presented with open fractures of the extremities or pelvis were considered. Subjects were identified using Current Procedural Terminology (CPT) codes. Patients aged 18 and older were analyzed for Gustilo type, antibiotics administered in the emergency room (ER), presence of an antibiotic allergy, post-operative antibiotic regimen and number of debridements, among others. Additionally, whether a patient was triaged by ER doctors or trauma surgeons (and made a trauma activation) was evaluated. Outcome measurements included time to intravenous (IV) antibiotic administration and time to surgical debridement. RESULTS: Patients received IV cefazolin a median of 17 minutes after arrival. Eighty-five patients who were made trauma activations received cefazolin 14 minutes after arrival while 24 non-trauma patients received cefazolin 53 minutes after arrival (p = <0.0001). The median time to gentamicin administration for all patients was 180 minutes. Patients not upgraded to a trauma received gentamicin 263 minutes after arrival, while patients upgraded received gentamicin 176 minutes after arrival. There was no statistically significant difference between the timing to cefazolin or gentamicin based on Gustilo type. CONCLUSIONS: Overall, patients that arrive at our institution with open fractures receive IV cefazolin significantly faster when trauma surgeons evaluate the patient. Additionally, delays in gentamicin administration are demonstrated in both triaging groups. This is due to the fact that cefazolin is stocked in the hospital ER, while gentamicin is commonly not due to weight-based dosing requirements precluding a standard dose. Improvements can be made to antibiotic administration of non-trauma patients and those requiring gentamicin via improved education and awareness of open fractures.

Identification of distinct cytomorphologic features in the diagnosis of NIFTP at the time of preoperative FNA: Implications for patient management.

BACKGROUND: A major reclassification occurred with the redesignation of noninvasive encapsulated follicular variant of papillary thyroid carcinoma as noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) due to its indolent nature. The aim of this study was to determine whether distinct cytomorphologic features could be identified on preoperative fine-needle aspiration (FNA) when NIFTP cases were compared with invasive follicular variant of papillary thyroid carcinoma (FVPTC) subtypes. METHODS: Thyroid resection cases with the diagnosis of FVPTC from 2012 to 2016 were reclassified as NIFTP, invasive encapsulated follicular variant of papillary thyroid carcinoma (IEFVPTC), and invasive FVPTC subtypes. Corresponding FNA specimens were retrieved and retrospectively reviewed. A univariate analysis using Fisher's exact test was performed to determine any differences in the frequencies of various cytomorphologic features among NIFTP, IEFVPTC, and FVPTC cases. A multivariate analysis was performed to identify any independent salient features that would be helpful in differentiating NIFTP from its invasive counterparts. RESULTS: The study population consisted of 93 cases, including 51 cases of NIFTP, 21 cases of IEFVPTC, and 21 cases of infiltrative FVPTC. Demographics such as age, sex, and tumor size were comparable across the 3 groups. A predominantly microfollicular pattern, an absence of nuclear pseudo-inclusions, and less frequent nuclear elongations and grooves were significantly more likely to be associated with NIFTP versus its invasive counterparts. The absence of nuclear pseudo-inclusions and the presence of a microfollicular pattern were the only independent predictors of a NIFTP diagnosis. CONCLUSIONS: This study demonstrates that NIFTP cases have distinguishing cytomorphologic characteristics in comparison with invasive FVPTC cases. Therefore, a preoperative cytologic evaluation provides clues that can aid in the distinction between NIFTP and its invasive counterparts. Cancer Cytopathol 2017;125:865-75. © 2017 American Cancer Society.

Parathyroidectomy prior to kidney transplant decreases graft failure.

BACKGROUND: Uncorrected uremic hyperparathyroidism is associated with delayed graft function after kidney transplantation. The current guidelines of the Kidney Disease Improving Global Outcomes recommend maintaining parathyroid hormone ≤9x normal in patients pre-kidney transplantation. This study explores the effect of increased levels of serum parathyroid hormone and preoperative parathyroidectomy on outcomes after kidney transplantation. METHODS: A retrospective review was performed of adult patients who underwent kidney transplantation between January 1, 2005, and December 31, 2014, at a single institution. Biochemistries and outcomes were analyzed pre-kidney transplantation and at 30 days, 6 months, and 1 year post-kidney transplantation. RESULTS: A total of 913 patients underwent kidney transplantation from 2005-2014. Graft survival 1 year post-kidney transplantation was 97.8%. Overall, 462 (50.6%) patients had a pre-kidney transplantation diagnosis of uncorrected uremic hyperparathyroidism, which was associated with complications in the first year post-kidney transplantation (odds ratio 1.44; 95% confidence interval, 1.11-1.87); no statistical association with delayed graft function or graft failure was detected. Pre-kidney transplantation parathyroid hormone ≥6x normal was associated with post-kidney transplantation graft failure (P < .05). A total of 57 (6.2%) patients underwent pre-kidney transplantation parathyroidectomy, which was associated with lesser risk of graft failure (odds ratio: 0.547; 95% confidence interval, 0.327-0.913), but no statistically significant association with delayed graft function or complications were detected. CONCLUSION: Pre-kidney transplantation parathyroidectomy decreases post-kidney transplantation graft failure and may benefit patients whose serum parathyroid hormone levels decrease into the target range of current Kidney Disease Improving Global Outcomes guidelines.

Primary hyperparathyroidism with normal baseline intraoperative parathyroid hormone: A challenging population.

BACKGROUND: Patients with primary hyperparathyroidism and baseline intraoperative parathyroid hormone levels in the normal range are challenging. This study compares the predictive value of a commonly used intraoperative parathyroid hormone algorithm, a software model for cure prediction, and surgeon judgment in this population. METHODS: This was a retrospective review of consecutive patients who underwent parathyroidectomy for primary hyperparathyroidism at a single institution from March 2013 to October 2014. RESULTS: Of 541 operative patients, 114 (21.1%) had a mean normal baseline intraoperative parathyroid hormone of ≤69 pg/mL (median 59.0 ± 10.3; range 26-69). Of the 114 patients, 93 (81.6%) were women, median age was 61 years (range 18-88). Overall, 107/108 (99.1%) patients were cured; 47 (41.2%) patients had single adenomas, 16 (14%) had double adenomas, and 51 (44.7%) had multigland hyperplasia. Using the 50% decline algorithm, a correct prediction was made in 86 (75.4%) patients. Using the computer software, a correct prediction was made in 88 (77.2%) patients. Surgeon judgment, however, was 99.1% accurate. CONCLUSION: Patients with normal baseline intraoperative parathyroid hormone have a high incidence of multigland disease (58.8%), greater than reported previously. Current software modeling and the 50% decline algorithm are insufficient to predict cure in this population; intraoperative parathyroid hormone interpretation combined with operative findings and surgical judgment yield optimal outcomes.

Central venous parathyroid hormone monitoring using a novel, specific anatomic method accurately predicts cure during minimally invasive parathyroidectomy.

BACKGROUND: Measurement of intraoperative parathyroid hormone (PTH) levels is an important adjunct to confirm biochemical cure during parathyroidectomy. The purpose of this study was to evaluate a simplified anatomic technique for PTH sampling from the central veins through the minimally invasive neck incision, and to compare the predictive accuracy of central and peripheral PTH values. METHODS: A specific anatomic method for central PTH sampling was employed in 48 patients. Samples were drawn simultaneously from peripheral and central veins at baseline and 10 minutes postexcision of all hyperfunctioning parathyroid glands. RESULTS: The central venous PTH levels independently predicted biochemical cure according to the Miami criterion in all the patients. There was no significant difference in the postexcision central and peripheral values, which were 24.40 + 1.86 and 21.69 + 1.74, respectively (P = .877, ANOVA test). CONCLUSIONS: This study provides the original description of a simplified technique for measurement of intraoperative PTH levels in the central veins with direct comparison to peripheral venous levels, and confirmation of accuracy in predicting biochemical cure when relying on centrally obtained values alone.

Shifting patterns of genomic variation in the somatic evolution of papillary thyroid carcinoma.

BACKGROUND: Cancer is increasingly understood to arise in the context of dynamically evolving genomes with continuously generated variants subject to selective pressures. Diverse mutations have been identified in papillary thyroid carcinoma (PTC), but unifying theories underlying genomic change are lacking. Applying a framework of somatic evolution, we sought to broaden understanding of the PTC genome through identification of global trends that help explain risk of tumorigenesis. METHODS: Exome sequencing was performed on 53 PTC and matched adjacent non-tumor thyroid tissues (ANT). Single nucleotide substitution (SNS) signatures from each sample pair were divided into three subsets based on their presence in tumor, non-tumor thyroid, or both. Nine matched blood samples were sequenced and SNS signatures intersected with these three subsets. The intersected genomic signatures were used to define branch-points in the evolution of the tumor genome, distinguishing variants present in the tissues' common ancestor cells from those unique to each tissue type and therefore acquired after genomic divergence of the tumor, non-tumor, and blood samples. RESULTS: Single nucleotide substitutions shared by the tumor and the non-tumor thyroid were dominated by C-to-T transitions, whereas those unique to either tissue type were enriched for C-to-A transversions encoding non-synonymous, predicted-deleterious variants. On average, SNSs of matched blood samples were 81 % identical to those shared by tumor and non-tumor thyroid, but only 12.5 % identical to those unique to either tissue. Older age and BRAF mutation were associated with increased SNS burden. CONCLUSIONS: The current study demonstrates novel patterns of genomic change in PTC, supporting a theory of somatic evolution in which the zygote's germline genome undergoes continuous remodeling to produce progressively differentiated, tissue-specific signatures. Late somatic events in thyroid tissue demonstrate shifted mutational spectra compared to earlier polymorphisms. These late events are enriched for predicted-deleterious variants, suggesting a mechanism of genomic instability in PTC tumorigenesis.

Dissection of Levels II Through V Is Required for Optimal Outcomes in Patients with Lateral Neck Lymph Node Metastasis from Papillary Thyroid Carcinoma.

BACKGROUND: Completeness of surgical resection is an important determinant of outcomes in patients with papillary thyroid carcinoma and regional lymph node metastasis. The extent of therapeutic lateral neck dissection remains controversial. This study aims to assess the impact of modified radical neck dissection of levels II to V in a large patient series. STUDY DESIGN: Retrospective analysis of consecutive patients with papillary thyroid carcinoma who underwent lateral neck dissection at a single institution from June 1, 2006 to December 31, 2014 was performed. RESULTS: A total of 241 lateral neck dissections were performed in 191 patients (118 [62%] women; median age 46 years [range 6 to 87 years]; median follow-up 14.3 months [range 0.1 to 107 months]). Overall, 202 initial neck dissections (195 modified radical neck dissections and 7 less extensive dissections) were performed. Among these initial dissections, 137 (68.8%), 132 (65.7%), 105 (52.0%), and 33 (16.9%) had positive lymph nodes in levels II, III, IV, and V, respectively. Ipsilateral lymph node persistence or recurrence occurred after 22 (10.9%) initial dissections, at level II in 10 (45.5%), level III in 8 (36.4%), level IV in 7 (31.8%), and level V in 3 (13.6%). Thirty-nine reoperative lateral neck dissection were performed, including 18 cases of persistence and recurrence after our initial dissections. In reoperative dissections, positive lymph nodes were confirmed in levels II, III, IV, and V in 18 (46.2%), 10 (25.6%), 13 (33.3%), and 5 (12.8%) dissections, respectively. Temporary nerve injury occurred in 6 (3.0%) initial and 4 (10.3%) reoperative dissections, respectively. There were no permanent nerve injuries. CONCLUSIONS: Omitting levels II and V during lateral neck dissection for papillary thyroid carcinoma potentially misses level II disease in two-thirds of patients and level V disease in one-fifth of patients. Formal modified radical neck dissection is necessary to avoid the morbidity of reoperative surgery.

Digging Deeper: A Case Study of Farmer Conceptualization of Ecosystem Services in the American South.

The interest in improved environmental sustainability of agriculture via biodiversity provides an opportunity for placed-based research on the conceptualization and articulation of ecosystem services. Yet, few studies have explored how farmers conceptualize the relationship between their farm and nature and by extension ecosystem services. Examining how farmers in the Southern Piedmont of South Carolina discuss and explain the role of nature on their farm, we create a detail-rich picture of how they perceive ecosystem services and their contributions to the agroeconomy. Using 34 semi-structured interviews, we developed a detail-rich qualitative portrait of these farmers' conceptualizations of ecosystem services. Farmers' conceptualization of four ecosystem services: provisioning, supporting, regulating, and cultural are discussed, as well as articulation of disservices. Results of interviews show that most interviewees expressed a basic understanding of the relationship between nature and agriculture and many articulated benefits provided by nature to their farm. Farmers referred indirectly to most services, though they did not attribute services to biodiversity or ecological function. While farmers have a general understanding and appreciation of nature, they lack knowledge on specific ways biodiversity benefits their farm. This lack of knowledge may ultimately limit farmer decision-making and land management to utilize ecosystem services for environmental and economic benefits. These results suggest that additional communication with farmers about ecosystem services is needed as our understanding of these benefits increases. This change may require collaboration between conservation biology professionals and extension and agriculture professionals to extended successful biomass provisioning services to other ecosystem services.

Real-Time Super Selective Venous Sampling in Remedial Parathyroid Surgery.

BACKGROUND: Remedial cervical exploration for persistent or recurrent primary hyperparathyroidism can be technically difficult, but is expedited by accurate preoperative localization. We investigated the use of real-time super selective venous sampling (sSVS) in the setting of negative noninvasive imaging modalities. STUDY DESIGN: We performed a retrospective analysis of a prospective database incorporating real-time sSVS in a tertiary academic medical center. Between September 2001 and April 2014, 3,643 patients were referred for surgical treatment of primary hyperparathyroidism. Of these, 31 represented remedial patients who had undergone one (n=28) or more (n=3) earlier cervical explorations and had noninformative, noninvasive preoperative localization studies. RESULTS: We extended the use of the rapid parathyroid hormone assay in the interventional radiology suite, generating near real-time data facilitating onsite venous localization by a dedicated interventional radiologist. The predictive value of real-time sSVS localization was investigated. Overall, sSVS correctly predicted the localization of the affected gland in 89% of cases. Of 31 patients who underwent sSVS, a significant rapid parathyroid hormone gradient was identified in 28 (90%), localizing specific venous drainage of a culprit gland. All patients underwent subsequent surgery and were biochemically cured, with the exception of one who had metastatic parathyroid carcinoma. Three patients with negative sSVS were also explored and cured. CONCLUSIONS: Preoperative parathyroid localization is of paramount importance in remedial cervical explorations. Real-time sSVS is a sensitive localization technique for patients with persistent or recurrent primary hyperparathyroidism, when traditional noninvasive imaging studies fail. These results validate the utility and benefit of real-time sSVS in guiding remedial parathyroid surgery.

Evaluation of Diffuse Reflection Infrared Spectrometry for End-of-Shift Measurement of α-quartz in Coal Dust Samples.

The inhalation of toxic substances is a major threat to the health of miners, and dust containing respirable crystalline silica (α-quartz) is of particular concern, due to the recent rise in cases of coal workers' pneumoconiosis and silicosis in some U.S. mining regions. Currently, there is no field-portable instrument that can measure airborne α-quartz and give miners timely feedback on their exposure. The U.S. National Institute for Occupational Safety and Health (NIOSH) is therefore conducting studies to investigate technologies capable of end-of-shift or real-time measurement of airborne quartz. The present study focuses on the potential application of Fourier transform infrared (FT-IR) spectrometry conducted in the diffuse reflection (DR) mode as a technique for measuring α-quartz in respirable mine dust. A DR accessory was used to analyze lab-generated respirable samples of Min-U-Sil 5 (which contains more than 90% α-quartz) and coal dust, at mass loadings in the ranges of 100-600 µg and 600-5300 µg, respectively. The dust samples were deposited onto three different types of filters, borosilicate fiberglass, nylon, and polyvinyl chloride (PVC). The reflectance, R, was calculated by the ratio of a blank filter and a filter with deposited mine dust. Results suggest that for coal and pure quartz dusts deposited on 37 mm PVC filters, measurements of -log R correlate linearly with known amounts of quartz on filters, with R(2) values of approximately 0.99 and 0.94, respectively, for samples loaded up to ∼4000 µg. Additional tests were conducted to measure quartz in coal dusts deposited onto the borosilicate fiberglass and nylon filter media used in the NIOSH-developed Personal Dust Monitor (PDM). The nylon filter was shown to be amenable to DR analysis, but quantification of quartz is more accurate when the filter is "free," as opposed to being mounted in the PDM filter holder. The borosilicate fiberglass filters were shown to produce excessive interference, making quartz quantification impossible. It was concluded that, while the DR/FT-IR method is potentially useful for on-filter measurement of quartz in dust samples, the use of PVC filters produced the most accurate results.

Modern experience with aggressive parathyroid tumors in a high-volume New England referral center.

BACKGROUND: Parathyroid carcinoma (PTCA) is an exceptionally rare malignancy, often with a clinical presentation similar to that of benign atypical parathyroid adenoma. Its low incidence portends unclear guidelines for management. Accordingly, thorough examination of clinical and pathologic variables was undertaken to distinguish between PTCA and atypical adenomas. STUDY DESIGN: This was a retrospective analysis of a prospective database at a tertiary academic referral center. Between September 2001 and April 2014, 3,643 patients were referred for surgical treatment of PHPT. Of these, 52 harbored aggressive parathyroid tumors: parathyroid carcinomas (n=18) and atypical adenomas (n=34). We analyzed the surgical and clinicopathologic tumor characteristics, and did a statistical analysis. We measured preoperative and intraoperative variables, and postoperative and pathologic outcomes. RESULTS: Parathyroid carcinoma patients present with significantly increased tumor size (3.5 cm vs 2.4 cm, respectively; p=0.002), mean serum calcium (13.0 vs 11.8 mg/dL, respectively; p=0.003) and intact parathyroid hormone (iPTH) levels (489 vs 266 pg/mL, respectively; p=0.04), and a higher incidence of hypercalcemic crisis, compared with patients with atypical adenomas (50% vs 19%, respectively; p=0.072). Parathyroid carcinoma more frequently lacks a distinct capsule (47.1% vs 12.9%, respectively; p=0.03) and adheres to adjacent structures (77.8% vs 20.6%, respectively; p=0.017). Of note, there was no significant difference in loss of parafibromin expression between groups. CONCLUSIONS: Clinical distinction between PTCA and atypical adenomas is of critical importance in determining the appropriate extent of resection and follow-up. Loss of parafibromin has not been shown to distinguish between PTCA and atypical adenoma; clearer definition of clinicopathologic criteria for PTCA is warranted and may lead to improved postoperative management.

Heart block and acute kidney injury due to hyperparathyroidism-induced hypercalcemic crisis.

We describe a patient who presented with multi-system organ failure due to extreme hypercalcemia (serum calcium 19.8 mg/dL), resulting from primary hyperparathyroidism. He was found to have a 4.8 cm solitary atypical parathyroid adenoma. His course was complicated by complete heart block, acute kidney injury, and significant neurocognitive disturbances. Relevant literature was reviewed and discussed. Hyperparathyroidism-induced hypercalcemic crisis (HIHC) is a rare presentation of primary hyperparathyroidism and only a small minority of these patients develop significant cardiac and renal complications. In cases of HIHC, a multidisciplinary effort can facilitate rapid treatment of life-threatening hypercalcemia and definitive treatment by surgical resection. As such, temporary transvenous cardiac pacing and renal replacement therapy can provide a life-saving bridge to definitive parathyroidectomy in cases of HIHC.

Lateralizing sensorimotor deficits in a case of pseudopheochromocytoma.

Pseudopheochromocytoma is a poorly understood, rare cause of severe paroxysmal hypertension that mimics the symptomatology of pheochromocytoma in the absence of biochemical evidence of this tumor. Symptoms such as headache, nausea, sweating, and palpitations during hypertensive episodes have been described. In this paper, we describe previously unreported findings of lateralizing sensorimotor deficits in a patient with pseudopheochromocytoma. These changes presented during a hypertensive episode and were concerning for stroke but were not accompanied by acute radiologic abnormalities. The deficits improved over 1.5 weeks as blood pressure stabilized with beta-blockade. We also review relevant literature on the clinical features, pathophysiology, and management of pseudopheochromocytoma.