Metal-based bifunctional methane activators are modeled utilizing density functional theory. The impact upon activation barriers of the metal among the late 3d metal M-II ions (Co - Zn) is quite pronounced, ca. 7 kcal/mol. Alteration of the metal's coordination environment without changing the supporting ligand types (e.g., comparing cis and trans coordination isomers) has a computed impact on methane activation barriers of +/- 1 kcal/mol. One significant result involves the varying impact of fluorination of the imidazole, which serves as a simple mimic of a histidine side chain. Sequentially fluorinating the 3C-H bonds of imidazole produces a range in the calculated Delta H+ of 4 1/2 kcal/mol, an effect greater than any other modeled herein apart from the impact of changing the central metal ion of the active site. As such, the present research yields insight into possible avenues for bio-inspired methane activators.

This article is dedicated to the late long-time Editor-in-Chief of Analytical Biochemistry, William Jakoby. As a graduate student, I remember reading many articles in Analytical Biochemistry and Methods in Enzymology, both volumes that Bill edited. I first met him as a graduate student presenting at the American Society of Biochemistry (and Molecular Biology) meetings. My Ph.D. advisor, Alton Meister, would bring over well-known biochemists and introduce me as Dr. Anderson, leaving me a bit tongue-tied being that I was still actually a humble graduate student! I next met Bill at my first Analytical Biochemistry Executive Editors meeting in San Diego when he was Editor-in-Chief Emeritus; I felt honored to be on the same board with him and serving the journal to which he had brought to prominence. His eyes were piercing and he was so sharp; his knowledge was both broad and deep. Since much of the large body of Bill's research was on glutathione S-transferases, my article focuses on the assay of the enzymes that synthesize glutathione, a substrate for glutathione S-transferases.

Bifunctional methane activation by M(II)-N2S motif.

Density functional theory and ab initio calculations indicate that nucleophiles can significantly reduce enthalpic barriers to methane C-H bond activation. Valence bond analysis suggests the formation of a two-center three-electron bond as the origin for the catalytic nucleophile effect. A predictive model for methane activation catalysis follows, which suggests that strongly electron-attracting and electron-rich radicals, together with both a negatively charged and strongly electron-donating outer sphere nucleophile, result in the lowest reaction barriers. It is corroborated by the sensitivity of the calculated C-H activation barriers to the external nucleophile and to continuum solvent polarity. More generally, from the present studies, one may propose proteins with hydrophobic active sites, available strong nucleophiles, and hydrogen bond donors as attractive targets for engineering novel methane functionalizing enzymes.

p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 12.0px 'Helvetica Neue'}Density functional theory and ab initio calculations indicate that nucleophiles can significantly reduce enthalpic barriers to methane C–H bond activation. Different pieces of evidence point to an electrostatic origin for the nucleophile effect such as the sensitivity of the C–H activation barriers to the external nucleophile and to continuum solvent polarity. The data further imply a transition state with significant charge build-up on the active hydrogen of the hydrocarbon substrate. From the present modeling studies, one may propose proteins with hydrophobic active sites, available nucleophiles, and hydrogen bond donors as attractive targets for the engineering of novel methane functionalizing enzymes.

Background Pleomorphic dermal sarcoma is the cutaneous variant of undifferentiated pleomorphic sarcoma. It is a rare malignancy of unclear histogenesis; it is a diagnosis of exclusion that requires extensive use of immunohistochemistry to rule out other malignancies. Pleomorphic dermal sarcoma typically presents as a solitary tumor in sun-exposed areas and may have unpredictable clinical behavior, with some tumors associated with metastasis and death. Case presentation We present an unusual case of multifocal pleomorphic dermal sarcoma arising in the areas of alpha-1-antitrypsin deficiency panniculitis in a lung transplant patient. Our patient was a 58-year-old white woman whose initial presentation was consistent with alpha-1-antitrypsin deficiency panniculitis. She then developed extensive multifocal, bleeding, and ulcerated nodules in the areas of the panniculitis. A skin biopsy was consistent with a diagnosis of pleomorphic dermal sarcoma. Her immunosuppressive regimen was decreased, and she was treated with liposomal doxorubicin 40 mg/m(2) every 3 weeks with some initial improvement in the size of her tumors. However, soon after beginning therapy, she developed pneumonia and septic shock and ultimately died from multi-organ failure. Conclusions We hypothesize that chronic, multifocal inflammation in the skin in the setting of immunosuppression led to simultaneous, malignant transformation in numerous skin lesions. We discuss the challenges of diagnosing pleomorphic dermal sarcoma, therapeutic options, and stress the need for multidisciplinary management of these cases.

The potential role of viruses as oncogenic triggers in cutaneous T-cell lymphoma (CTCL) pathogenesis is a subject of ongoing investigation. CTCL occurs with an increased incidence in immunosuppressed patients (Nikolaou et al., 2015Nikolaou V. Papadavid E. Economidi A. Marinos L. Moustou E. Karampidou K. et al.Mycosis fungoides in the era of antitumour necrosis factor-alpha treatments.Br J Dermatol. 2015; 173: 590-593Crossref PubMed Scopus (23) Google Scholar, Pomerantz et al., 2010Pomerantz R.G. Campbell L.S. Jukic D.M. Geskin L.J. Posttransplant cutaneous T-cell lymphoma: case reports and review of the association of calcineurin inhibitor use with posttransplant lymphoproliferative disease risk.Arch Dermatol. 2010; 146: 513-516Crossref PubMed Scopus (22) Google Scholar, Wilkins et al., 2006Wilkins K. Turner R. Dolev J.C. LeBoit P.E. Berger T.G. Maurer T.A. Cutaneous malignancy and human immunodeficiency virus disease.J Am Acad Dermatol. 2006; 54: 189-206Abstract Full Text Full Text PDF PubMed Scopus (110) Google Scholar). Spectratyping studies have shown depleted T-cell receptor diversity in CTCL patients similar to that seen in patients with advanced HIV, and Ingenuity Pathway Analysis (Qiagen, Hilden, Germany) shows increased expression of genes critical to host viral response (Yawalkar et al., 2003Yawalkar N. Ferenczi K. Jones D.A. Yamanaka K. Suh K.Y. Sadat S. et al.Profound loss of T cell receptor repertoire complexity in cutaneous T-cell lymphoma.Blood. 2003; 102: 4059-4066Crossref PubMed Scopus (140) Google Scholar). However, no consistent association between a viral pathogen and CTCL has been established (Mirvish et al., 2013Mirvish J.J. Pomerantz R.G. Falo Jr., L.D. Geskin L.J. Role of infectious agents in cutaneous T-cell lymphoma: facts and controversies.Clin Dermatol. 2013; 31: 423-431Abstract Full Text Full Text PDF PubMed Scopus (46) Google Scholar). The development of high-throughput sequencing (HTS) has provided powerful new tools for pathogen discovery, yet HTS studies have not identified viral sequences in CTCL (Dereure et al., 2013Dereure O. Cheval J. Du Thanh A. Pariente K. Sauvage V. Claude Manuguerra J. et al.No evidence for viral sequences in mycosis fungoides and Sezary syndrome skin lesions: a high throughput sequencing approach.J Invest Dermatol. 2013; 133: 853-855Abstract Full Text Full Text PDF PubMed Scopus (17) Google Scholar, Dulmage et al., 2015Dulmage B.O. Feng H. Mirvish E. Geskin L. Black cat in a dark room: the absence of a directly oncogenic virus does not eliminate the role of an infectious agent in cutaneous T-cell lymphoma pathogenesis.Br J Dermatol. 2015; 172: 1449-1451Crossref PubMed Scopus (10) Google Scholar, Lee et al., 2012Lee C.S. Ungewickell A. Bhaduri A. Qu K. Webster D.E. Armstrong R. et al.Transcriptome sequencing in Sezary syndrome identifies Sezary cell and mycosis fungoides-associated lncRNAs and novel transcripts.Blood. 2012; 120: 3288-3297Crossref PubMed Scopus (71) Google Scholar). One explanation for failure is that viral burden in samples may be below the threshold for detection in complex backgrounds of host nucleic acid. To address this possibility, we used a positive selection method for HTS with enhanced sensitivity (Briese et al., 2015Briese T. Kapoor A. Mishra N. Jain K. Kumar A. Jabado O.J. et al.Virome capture sequencing enables sensitive viral diagnosis and comprehensive virome analysis.MBio. 2015; 6 (e01491–15)Crossref PubMed Scopus (209) Google Scholar). The Virome Capture Sequencing Platform for Vertebrate Viruses (VirCapSeq-VERT; Roche, Pleasanton, CA) is a positive-selection probe-based method that targets all 207 known vertebrate viruses, allowing for a 100- to 10,000-fold increase in the number of viral reads over traditional HTS, a degree of sensitivity comparable to targeted real-time PCR. Over 90% of genome recovery can be achieved with only 100 viral copies in 50 ng of whole-blood nucleic acid. Superior to real-time PCR, however, VirCapSeq-VERT can detect viruses that differ from known sequences by 40% (Briese et al., 2015Briese T. Kapoor A. Mishra N. Jain K. Kumar A. Jabado O.J. et al.Virome capture sequencing enables sensitive viral diagnosis and comprehensive virome analysis.MBio. 2015; 6 (e01491–15)Crossref PubMed Scopus (209) Google Scholar). We used VirCapSeq-VERT to search for viral sequences in mononuclear cells derived from the peripheral blood of leukemic CTCL patients with Sézary syndrome. In total, 27 million paired-end reads were generated using Illumina MiSeq, with an average of 2.25 million paired-end reads per sample. An average of 11% of the reads were removed after filtration; 74% of the reads were removed after host subtraction. Overall, 49,349 sequences showed partial homology to 23 unique viral species including human endogenous retroviruses (HERVs) H and K, human herpesvirus (HHV) 4 and 5, HIV, human T-lymphotropic virus-1 (HTLV-1), Lassa virus, Luna virus, bovine viral diarrhea virus, and Ngari virus (Table 1).Table 1Potential viral species counts from MegaBLASTViral SpeciesSample IDMaximum Sequence Length (nt)1Maximum sequence length and contig depth are in sample 1.Maximum Contig Depth (Number of Reads)1Maximum sequence length and contig depth are in sample 1.Significance123456BVDV8,264108,844—14—1,837108Library preparation artifactHERV-H/env598———9101452Proviral sequencesHERV-H/env62158————HERV-K60199641455287514Proviral sequencesHHV-424—————1453Low abundance/prevalenceHHV-512—————HIV-110—————844Nonfunctional pol polymerase protein geneHTLV-1153282869221452Proviral sequencesLassa virus118——26201451Likely misannotationLuna virus3,9123,8043,6731113723,53343226Likely misannotationNgari virus332026—18161452Likely misannotationAbbreviations: BVDV, bovine viral diarrhea virus; contig, contiguous sequence; HERV, human endogenous retrovirus; HHV, human herpes virus; HTLV-1, human lymphotropic virus 1; ID, identification; nt, nucleotide.1 Maximum sequence length and contig depth are in sample 1. Open table in a new tab Abbreviations: BVDV, bovine viral diarrhea virus; contig, contiguous sequence; HERV, human endogenous retrovirus; HHV, human herpes virus; HTLV-1, human lymphotropic virus 1; ID, identification; nt, nucleotide. Bovine viral diarrhea virus sequences are common in bovine serum products used in sample collection and thus were excluded from further analysis. HERV-H/env62 and HERV-H/env59 sequences were present in 2 of 6 and 3 of 6 samples, respectively, matching to a proviral copy. The HHV-4 and HHV-5 sequences were present in 1 of 6 samples tested; 36 reads matched to the partial HHV genome. HIV-1 sequences were present in 1 of 6 samples, partially matching to a nonfunctional pol protein gene. Short sequences with partial homology to Lassa, Ngari, and Luna viruses were present in 4 of 6, 5 of 6, and 6 of 6 samples, respectively. Detailed analysis indicated that these sequences were 100% homologous to human genomic sequences (accession number KF478765.1 for Lassa, KJ716849.1 for Ngari, and AB972431.1 and KX121618.1 for Luna). Thus, the reference sequences likely represent misannotations. HERV-K and HTLV-1 sequences were present in 6 of 6 samples. The HERV-K sequences comprised partially coding proviral sequences, and the HTLV-1 sequences matched to defective proviral sequences, both showing high similarity to the host genome. We conducted this study using VirCapSeq-VERT to search for viral sequences in patients with CTCL. VirCapSeq-VERT's ability to detect all known vertebrate viruses offers the most sensitive detection methods compared with conventional HTS and targeted reverse transcription PCR. No substantive coding sequences for viral pathogens or unknown viruses, or evidence for active infection, were obtained. All six Sézary syndrome samples expressed partial, noncoding sequences for HERV-K and HTLV-1, but these sequences had low read counts and contiguous sequence (contig) depths, and were thus insufficient to be considered as positive results. Nevertheless, their presence is of interest, because both viruses have been previously implicated in CTCL. HTLV-1's role in CTCL has been debated at length (Mirvish et al., 2013Mirvish J.J. Pomerantz R.G. Falo Jr., L.D. Geskin L.J. Role of infectious agents in cutaneous T-cell lymphoma: facts and controversies.Clin Dermatol. 2013; 31: 423-431Abstract Full Text Full Text PDF PubMed Scopus (46) Google Scholar). HERVs are expressed in all human tissues but have been implicated in cancer pathogenesis, and increased expression of HERVs has been seen in CTCL patients (Fava et al., 2016Fava P. Bergallo M. Astrua C. Brizio M. Galliano I. Montanari P. et al.Human endogenous retrovirus expression in primary cutaneous T-cell lymphomas.Dermatology. 2016; 232: 38-43Crossref PubMed Scopus (17) Google Scholar, Maliniemi et al., 2013Maliniemi P. Vincendeau M. Mayer J. Frank O. Hahtola S. Karenko L. et al.Expression of human endogenous retrovirus-w including syncytin-1 in cutaneous T-cell lymphoma.PLoS One. 2013; 8: e76281Crossref PubMed Scopus (42) Google Scholar). Sequencing of healthy control patient samples with matched demographics was not available for this pilot study for direct comparison, but further investigation may elucidate the significance of these partial noncoding sequences and whether these viruses could play a genuine role in CTCL pathogenesis. Six Sézary syndrome patients diagnosed according to the World Health Organization-European Organization for Research and Treatment of Cancer criteria were enrolled after receiving Columbia University Medical Center Institutional Review Board approval. Written informed patient consent was obtained from all patients (5 women, 1 man; age range = 58–82 years; 3 Caucasian, 2 Hispanic, and 1 African American). Whole blood from each patient was collected. Peripheral blood mononuclear cells were isolated via density gradient centrifugation (Ficoll-Plaque; Millipore Sigma, St. Louis, MO), and plasma was isolated via centrifugation. Total nucleic acid (TNA) was extracted from the plasma and peripheral blood mononuclear cells using NucliSENS easyMAG (BioMérieux, Marcy l'Etoile, France). TNAs were processed according to Center for Infection and Immunity standard operating procedures for VirCapSeq-VERT. Briefly, the VirCapSeq-VERT probe library was added to the TNAs. Positively selected and enriched sequences underwent PCR amplification and sequencing using the Illumina (San Diego, CA) MiSeq platform. The 150-nucleotide–long paired end reads were generated (an average of more than 2 million reads per sample). HTS data were analyzed using the Center for Infection and Immunity bioinformatics viral discovery pipeline: the de-multiplexed fastq files were filtered for low-quality and low-complexity reads, adaptors were removed, reads were trimmed, and short reads were discarded. These pre-processed reads were subjected to computational subtraction against human reference databases from the National Center for Biotechnology Information (NCBI) to remove host background sequences. The databases used for host subtraction include human genomic, ribosomal, and mitochondrial sequences. The host-subtracted reads were then assembled de novo using MIRA (Bastien Chevreux, Lexington, MA) assembler, version 4.0. Contigs and singletons were annotated using homology search program BLAST+ from NCBI (Silver Spring, MD). The sequences were screened for highly similar sequences using megaBLAST against the GenBank nucleotide database. To ensure that mutant viral sequences were not discarded, sequences with low/no homology to the GenBank viral nucleotide database were reblasted using Blastx against the GenBank database. Contigs and reads were then mapped to reference genomes identified from BLAST using Geneious, version 6.0.6 (Biomatters INC, Newark, NJ). The sequence data supporting the results of this article are available in NCBI under accession number PRJNA415045 with biosample accession numbers SAMN07812478–83. Mary Elizabeth Anderson: http://orcid.org/0000-0003-1364-1248 Christina Chung Patrone: http://orcid.org/0000-0001-8906-7460 The authors state no conflict of interest. We thank Lisa Keller and Saky Yakas for their philanthropic support of cutaneous lymphoma research at Columbia University.

Ustekinumab is a human interleukin (IL)12/23 antagonist with US Food and Drug Administration indications to treat moderate to severe plaque psoriasis, psoriatic arthritis, and Crohn's disease. Because of the blockade of the IL-12/IL-13 pathway, which mediates antitumor and antiviral responses, ustekinumab has significant immunosuppressive characteristics and can lead to an increased risk of infection, reactivation of latent infection, and malignancy in patients. We present a case of a patient with psoriasis and psoriatic arthritis on ustekinumab who had disseminated verrucae shortly after initiating treatment.

CONTEXTFragmentation in geriatric hip fracture care is a growing concern because of the aging population. Patients with hip fractures at our institution historically were admitted to multiple different services and units, leading to unnecessary variation in inpatient care. Such inconsistency contributed to delays in surgery, discharge, and functional recovery; hospital-acquired complications; failure to adhere to best practices in osteoporosis management; and poor coordination with outpatient practitioners.OBJECTIVETo describe a stepwise approach to systems redesign for this patient population.DESIGNWe designed and implemented a comprehensive geriatric hip fracture program for patients aged 65 years and older at our academic Medical Center in October 2014. Key interventions included admission of all ward-status patients to the Orthopedics Service with hospitalist comanagement; geographic placement on the Orthopedics Unit; and standardized, evidence-based electronic order sets bundling geriatric best practices and a streamlined workflow for discharge planning.MAIN OUTCOME MEASURESHospital length of stay.RESULTSWe identified 271 admissions among 267 patients between January 1, 2012, and March 31, 2016; of those, 154 were before and 117 were after program implementation. Mean hospital length of stay significantly improved from 6.4 to 5.5 days (p = 0.004). The 30-day all-cause readmission rate and discharge disposition remained stable. The percentage of patients receiving osteoporosis evaluation and treatment increased significantly. The rate of completed 30-day outpatient follow-up also improved.CONCLUSIONOur comprehensive geriatric hip fracture program achieved and sustained gains in the quality and efficiency of care by improving fragmentation in the health care system.

Abstract 1. Metabolic acidosis due to accumulation of l-5-oxoproline is a rare, poorly understood, disorder associated with acetaminophen treatment in malnourished patients with chronic morbidity. l-5-Oxoprolinuria signals abnormal functioning of the γ-glutamyl cycle, which recycles and synthesises glutathione. Inhibition of glutathione synthetase (GS) by N-acetyl-p-benzoquinone imine (NAPQI) could contribute to 5-oxoprolinuric acidosis in such patients. We investigated the interaction of NAPQI with GS in vitro. 2. Peptide mapping of co-incubated NAPQI and GS using mass spectrometry demonstrated binding of NAPQI with cysteine-422 of GS, which is known to be essential for GS activity. Computational docking shows that NAPQI is properly positioned for covalent bonding with cysteine-422 via Michael addition and hence supports adduct formation. 3. Co-incubation of 0.77 μM of GS with NAPQI (25–400 μM) decreased enzyme activity by 16–89%. Inhibition correlated strongly with the concentration of NAPQI and was irreversible. 4. NAPQI binds covalently to GS causing irreversible enzyme inhibition in vitro. This is an important novel biochemical observation. It is the first indication that NAPQI may inhibit glutathione synthesis, which is pivotal in NAPQI detoxification. Further studies are required to investigate its biological significance and its role in 5-oxoprolinuric acidosis.

The reversible conversion of leukotriene C4 to leukotriene D4 and of'the latter to leukotriene E4 were studied with highly purified homogeneous preparations of y-glutamyl transpeptidase, dipeptidase, and aminopeptidase M. The conver- sion of leukotriene C4 to leukotriene D4, catalyzed by y-glutamyl transpeptidase, is significantly more rapid when carried out in the presence of an amino acid mixture closely approximating that found in blood plasma and is accompanied by y-glutamyl amino acid formation. Because y-glutamyl transpeptidase is bound to the external surface of cell membranes and thus is readily accessible to plasma amino acids, it appears that conversion of leukotriene C4 to leukotriene D4 under physiological conditions is coupled with the formation of y-glutamyl amino acids. The apparent Km value for leukotriene C4 in this reaction is about 6 x 10-6 M, a value close to that found for glutathione. Conversion of leuko- triene D4 to leukotriene C4 is effectively catalyzed by y-glutamyl transpeptidase in the presence of relatively low concentrations of glutathione. The conversion of leukotriene D4 to leukotriene E4 is catalyzed much more rapidly by renal dipeptidase than by renal aminopeptidase M. Incubation of leukotriene E4 with y-glutamyl transpeptidase and glutathione leads to formation of a compound with the properties of y-glutamyl leukotriene E4; this reaction is analogous to that shown previously in which y-glutamyl cystine is formed by transpeptidation between glutathione and cystine.

BACKGROUND Medicaid is often associated with longer hospitalizations and higher in-hospital mortality than other insurance types. OBJECTIVE To characterize the impact of state Medicaid expansion status under the Affordable Care Act (ACA) on payer mix, length of stay (LOS), and in-hospital mortality. DESIGN/SETTING/PATIENTS Retrospective cohort study of general medicine patients discharged from academic medical centers (AMCs) within the University HealthSystem Consortium from October 1, 2012 to September 30, 2015. INTERVENTION/MEASUREMENTS Hospitals were stratified according to state Medicaid expansion status. The proportion of discharges by primary payer, LOS index, and mortality index were compared between Medicaid-expansion and nonexpansion hospitals before and after ACA implementation. ACA implementation was defined as January 1, 2014, for all states except Michigan, New Hampshire, Pennsylvania, and Indiana, which had unique dates of Medicaid expansion. RESULTS We identified 3,144,488 discharges from 156 hospitals in 24 Medicaid-expansion states and Washington, DC, and 1,114,464 discharges from 55 hospitals in 14 nonexpansion states during the study period. Hospitals in Medicaid-expansion states experienced a significant 3.7% increase in Medicaid discharges (P = 0.013) and a 2.9% decrease in uninsured discharges (P < 0.001) after ACA implementation, whereas hospitals in nonexpansion states saw no significant change in payer mix. In a difference-in-differences analysis, the changes in LOS and mortality indices pre- to post-ACA implementation did not differ significantly between hospitals in Medicaid-expansion versus nonexpansion states. CONCLUSIONS The differential shift in payer mix between Medicaid-expansion and nonexpansion states under the ACA did not influence LOS or in-hospital mortality for general medicine patients at AMCs in the United States. Journal of Hospital Medicine 2015;11:847-852. © 2015 Society of Hospital Medicine.

Targeting patients with prolonged hospitalizations may represent an effective strategy for reducing average hospital length of stay (LOS). We sought to characterize predictors of prolonged hospitalizations among general medicine patients to guide future improvement efforts. We conducted a retrospective cohort study using administrative data of general medicine patients discharged from inpatient status from our academic medical center between 2012 and 2014. Multivariable logistic regression was performed to assess the association between sociodemographic and clinical variables with prolonged LOS, defined as >21 days. Of 18,363 discharges, 416 (2.3%) demonstrated prolonged LOS. Prolonged hospitalizations accounted for 18.6% of total inpatient days and contributed 0.8 days to an average LOS of 4.8 days during the study period. Prolonged hospitalizations were associated with younger age (odds ratio [OR]: 0.80 per 10-year increase in age, 95% confidence interval [CI]: 0.73-0.87) and Medicaid insurance (OR: 1.99, 95% CI: 1.29-3.05, REF = Medicare). Compared to patients without prolonged LOS, prolonged LOS patients were more likely to have methicillin-resistant Staphylococcus aureus septicemia (OR: 8.83, 95% CI: 1.72-45.36); require a palliative care consult (OR: 4.63, 95% CI: 2.86-7.49), ICU stay (OR: 6.66, 95% CI: 5.22-8.50), or surgery (OR: 5.04, 95% CI: 3.90-6.52); and be discharged to a post-acute-care facility (OR: 10.37, 95% CI: 6.92-15.56). Prolonged hospitalizations in a small proportion of patients were an important contributor to overall LOS and particularly affected Medicaid enrollees with complex hospital stays who were not discharged home. Further studies are needed to determine the reasons for discharge delays in this population.

Background Care coordination between adult hospitalists and primary care providers (PCPs) is a critical component of successful transitions of care from hospital to home, yet one that is not well understood. Objective The purpose of this study was to understand the challenges in coordination of care, as well as potential solutions, from the perspective of hospitalists and PCPs in North Carolina. Design and Participants We conducted an exploratory qualitative study with 58 clinicians in four hospitalist focus groups ( n = 32), three PCP focus groups ( n = 19), and one hybrid group with both hospitalists and PCPs ( n = 7). Approach Interview guides included questions about care coordination, information exchange, follow-up care, accountability, and medication management. Focus group sessions were recorded, transcribed verbatim, and analyzed in ATLAS.ti. The constant comparative method was used to evaluate differences between hospitalists and PCPs. Key Results Hospitalists and PCPs were found to encounter similar care coordination challenges, including (1) lack of time, (2) difficulty reaching other clinicians, (3) lack of personal relationships with other clinicians, (4) lack of information feedback loops, (5) medication list discrepancies, and (6) lack of clarity regarding accountability for pending tests and home health. Hospitalists additionally noted difficulty obtaining timely follow-up appointments for after-hours or weekend discharges. PCPs additionally noted (1) not knowing when patients were hospitalized, (2) not having hospital records for post-hospitalization appointments, (3) difficulty locating important information in discharge summaries, and (4) feeling undervalued when hospitalists made medication changes without involving PCPs. Hospitalists and PCPs identified common themes of successful care coordination as (1) greater efforts to coordinate care for “high-risk” patients, (2) improved direct telephone access to each other, (3) improved information exchange through shared electronic medical records, (4) enhanced interpersonal relationships, and (5) clearly defined accountability. Conclusions Hospitalists and PCPs encounter similar challenges in care coordination, yet have important experiential differences related to sending and receiving roles for hospital discharges. Efforts to improve coordination of care between hospitalists and PCPs should aim to understand perspectives of clinicians in each setting.

The obligate homodimer human glutathione synthetase (hGS) provides an ideal system for exploring the role of protein–protein interactions in the structural stability, activity and allostery of enzymes. The two active sites of hGS, which are 40 Å apart, display allosteric modulation by the substrate γ-glutamylcysteine (γ-GC) during the synthesis of glutathione, a key cellular antioxidant. The two subunits interact at a relatively small dimer interface dominated by electrostatic interactions between S42, R221, and D24. Alanine scans of these sites result in enzymes with decreased activity, altered γ-GC affinity, and decreased thermal stability. Molecular dynamics simulations indicate these mutations disrupt interchain bonding and impact the tertiary structure of hGS. While the ionic hydrogen bonds and salt bridges between S42, R221, and D24 do not mediate allosteric communication in hGS, these interactions have a dramatic impact on the activity and structural stability of the enzyme.

Human glutathione synthetase (hGS) catalyzes the second step in the synthesis of the key antioxidant glutathione. The homodimeric enzyme displays negative cooperativity towards the ɣ‐glutamylcysteine substrate. The presented work probes the significance of residues within the substrate binding loop of hGS responsible for loop motion throughout the catalytic cycle and provides insight into the precise mechanism of communication between active sites. Molecular dynamics simulations and docking studies elucidate the interactions that mediate binding. Experimental point mutations, coupled activity assays, kinetic studies, and differential scanning calorimetry provide information on the role of these residues in activity, cooperativity and thermal stability. A deeper understanding of the residues responsible for loop motion within the substrate binding loop of hGS shows that interactions at the active site have significant impact on the structure and function of the enzyme.Grant Funding Source: Supported by NIH R15GM086833, Research Enhancement Program Grant (TWU), UNT Faculty Research Grant