A Genetic Screen Identifies a Critical Role for the WDR81-WDR91 Complex in the Trafficking and Degradation of Tetherin

Tetherin (BST2/CD317) is a viral restriction factor that anchors enveloped viruses to host cells and limits viral spread. The HIV‐1 Vpu accessory protein counteracts tetherin by decreasing its cell surface expression and targeting it for ubiquitin‐dependent endolysosomal degradation. Although the Vpu‐mediated downregulation of tetherin has been extensively studied, the molecular details are not completely elucidated. We therefore used a forward genetic screen in human haploid KBM7 cells to identify novel genes required for tetherin trafficking. Our screen identified WDR81 as a novel gene required for tetherin trafficking and degradation in both the presence and absence of Vpu. WDR81 is a BEACH‐domain containing protein that is also required for the degradation of EGF‐stimulated epidermal growth factor receptor (EGFR) and functions in a complex with the WDR91 protein. In the absence of WDR81 the endolysosomal compartment appears swollen, with enlarged early and late endosomes and reduced delivery of endocytosed dextran to cathepsin‐active lysosomes. Our data suggest a role for the WDR81‐WDR91 complex in the fusion of endolysosomal compartments and the absence of WDR81 leads to impaired receptor trafficking and degradation.

Subtherapeutic voriconazole concentrations associated with concomitant dexamethasone: case report and review of the literature

WHAT IS KNOWN AND OBJECTIVE

Voriconazole has significant drug interactions due to metabolism by CYP enzymes. Subtherapeutic voriconazole concentrations associated with concomitant dexamethasone are not well described.

CASE DESCRIPTION

An 84-year-old male was started on voriconazole for a fungal brain abscess. He was readmitted due to clinical failure thought to be the result of subtherapeutic voriconazole concentrations. Dexamethasone was identified as a potential cause due to its induction of CYP enzymes. This interaction was substantiated by sequential troughs that demonstrated a rise in voriconazole concentrations as dexamethasone was tapered off.

WHAT IS NEW AND CONCLUSION

Therapeutic drug monitoring for patients on voriconazole and dexamethasone is essential to prevent suboptimal clinical outcomes.

High-performance hybrid Orbitrap mass spectrometers for quantitative proteome analysis: Observations and implications

We present basic workups and quantitative comparisons for two current generation Orbitrap mass spectrometers, the Q Exactive Plus and Orbitrap Fusion Tribrid, which are widely considered two of the highest performing instruments on the market. We assessed the performance of two quantitative methods on both instruments, namely label-free quantitation and stable isotope labeling using isobaric tags, for studying the heat shock response in Escherichia coli. We investigated the recently reported MS3 method on the Fusion instrument and the potential of MS3-based reporter ion isolation Synchronous Precursor Selection (SPS) and its impact on quantitative accuracy. We confirm that the label-free approach offers a more linear response with a wider dynamic range than MS/MS-based isobaric tag quantitation and that the MS3/SPS approach alleviates but does not eliminate dynamic range compression. We observed, however, that the choice of quantitative approach had little impact on the ability to statistically evaluate the E. coli heat shock response. We conclude that in the experimental conditions tested, MS/MS-based reporter ion quantitation provides reliable biological insight despite the issue of compressed dynamic range, an observation that significantly impacts the choice of instrument.

Arginine methylation and citrullination of splicing factor proline- and glutamine-rich (SFPQ/PSF) regulates its association with mRNA

Splicing factor proline- and glutamine-rich (SFPQ) also commonly known as polypyrimidine tract-binding protein-associated-splicing factor (PSF) and its binding partner non-POU domain-containing octamer-binding protein (NONO/p54nrb), are highly abundant, multifunctional nuclear proteins. However, the exact role of this complex is yet to be determined. Following purification of the endogeneous SFPQ/NONO complex, mass spectrometry analysis identified a wide range of interacting proteins, including those involved in RNA processing, RNA splicing, and transcriptional regulation, consistent with a multifunctional role for SFPQ/NONO. In addition, we have identified several sites of arginine methylation in SFPQ/PSF using mass spectrometry and found that several arginines in the N-terminal domain of SFPQ/PSF are asymmetrically dimethylated. Furthermore, we find that the protein arginine N-methyltransferase, PRMT1, catalyzes this methylation in vitro and that this is antagonized by citrullination of SFPQ. Arginine methylation and citrullination of SFPQ/PSF does not affect complex formation with NONO. However, arginine methylation was shown to increase the association with mRNA in mRNP complexes in mammalian cells. Finally we show that the biochemical properties of the endogenous complex from cell lysates are significantly influenced by the ionic strength during purification. At low ionic strength, the SFPQ/NONO complex forms large heterogeneous protein assemblies or aggregates, preventing the purification of the SFPQ/NONO complex. The ability of the SFPQ/NONO complex to form varying protein assemblies, in conjunction with the effect of post-translational modifications of SFPQ modulating mRNA binding, suggests key roles affecting mRNP dynamics within the cell.

Adherence to the 2007 cystic fibrosis pulmonary guidelines: a national survey of CF care centers

OBJECTIVE

To examine cystic fibrosis (CF) physician adherence to the 2007 CF Foundation (CFF) Pulmonary Guidelines for Chronic Medications. Specifically adherence and barriers to prescribing level A medication recommendations (i.e., inhaled tobramycin and dornase alfa) and level B medication recommendations (i.e., macrolide antibiotics and hypertonic saline) were studied.

METHODS

During Spring 2010, the CFF emailed survey invitations to directors of 136 accredited CF care centers treating 50+ CF patients. Directors were asked to forward the invitations to their physician colleagues. One hundred thirty-three surveys were included in the analyses, representing 92 centers. Barriers were conceptualized based on Cabana et al.'s framework for adherence to guidelines. Adherence was assessed via a case vignette.

RESULTS

Logistic regression analysis revealed that higher outcome expectancy (OR = 1.099, CI 1.010-1.196) and fewer environmental/system barriers (OR = 1.484, CI 1.158-1.902) were significantly associated with Vignette Adherence. A trend for an association between Familiarity and Vignette Adherence (OR = 1.642, CI 0.953-2.828) was evident, while no demographic variables were significantly associated with Vignette Adherence.

CONCLUSION

Targeting outcome expectancy and external barriers with multifaceted, ongoing interventions may improve guideline adherence. Pulmonologists are clearly looking for empirical evidence that these medications benefit their patients over the long-term and offset patient treatment burden with improved health.

Primary care physician attitudes and practice patterns in the management of obese adults: results from a national survey

PURPOSE

Obesity remains a serious public health problem. The purpose of this study was to identify the current attitudes and practices of primary care physicians (PCPs) with respect to obesity.

METHODS

A survey was systematically developed and administered electronically to PCPs, who received a small honorarium for their time. Results were analyzed to identify specific attitudes and practices and their associations with each other and with demographic and other variables.

RESULTS

Physicians expressed little confidence in their ability to manage obesity. In general, however, they believed that obesity could be successfully managed. Lifestyle changes were perceived to be the most effective available method for patients to lose weight, and respondents were more likely to recommend this approach over pharmacotherapy or bariatric surgery. Respondents perceive the greatest barrier to managing obese patients to be a lack of patient motivation. Physicians were significantly more likely to initiate discussions with obese patients about their weight if they believed they had positive attitudes about and knowledge of weight management, and adequate resources to manage the problem.

CONCLUSIONS

Physicians report a lack of confidence in managing obesity. Lack of patient motivation is perceived to be the greatest barrier. Physicians with greater knowledge, more positive attitudes toward obesity management, and access to more resources are more likely to provide weight management in primary care settings.

Barriers to adherence to chronic obstructive pulmonary disease guidelines by primary care physicians

Purpose:

Even with the dissemination of several clinical guidelines, chronic obstructive pulmonary disease (COPD) remains underdiagnosed and mismanaged by many primary care physicians (PCPs). The objective of this study was to elucidate barriers to consistent implementation of COPD guidelines.

Patients and methods:

A cross-sectional study implemented in July 2008 was designed to assess attitudes and barriers to COPD guideline usage.

Results:

Five hundred US PCPs (309 family medicine physicians, 191 internists) were included in the analysis. Overall, 23.6% of the surveyed PCPs reported adherence to spirometry guidelines over 90% of the time; 25.8% reported adherence to guidelines related to long-acting bronchodilator (LABD) use in COPD patients. In general, physicians were only somewhat familiar with COPD guidelines, and internal medicine physicians were significantly more familiar than family physicians (P < 0.05). In a multivariate model controlling for demographics and barriers to guideline adherence, we found significant associations with two tested guideline components. Adherence to spirometry guidelines was associated with agreement with guidelines, confidence in interpreting data, ambivalence to outcome expectancy, and ability to incorporate spirometry into patient flow. Adherence to LABD therapy guidelines was associated with agreement with guidelines and confidence in gauging pharmacologic response.

Conclusions:

Adherence to guideline recommendations of spirometry use was predicted by agreement with the recommendations, self-efficacy, perceived outcome expectancy if recommendations were adhered to, and resource availability. Adherence to recommendations of LABD use was predicted by agreement with guideline recommendations and self-efficacy. Increasing guideline familiarity alone may have limited patient outcomes, as other barriers, such as low confidence and outcome expectancy, are more likely to impact guideline adherence.

How does older age influence oncologists' cancer management?

BACKGROUND

Over half of new cancer cases occur in patients aged > or = 65 years. Many older patients can benefit from intensive cancer therapies, yet evidence suggests that this population is undertreated.

METHODS

To assess preferences and influential factors in geriatric cancer management, practicing U.S. medical oncologists completed a survey containing four detailed vignettes exploring colon, breast, lung, and prostate cancer treatment. Participants were randomly assigned one of two surveys with vignettes that were identical except for patient age (<65 years or >70 years).

RESULTS

Physicians in each survey group (n = 200) were demographically similar. Intensive therapy was significantly less likely to be recommended for an older than for a younger, but otherwise identical, patient in two of the scenarios. For a woman with metastatic colon cancer (Eastern Cooperative Oncology Group [ECOG] score, 1) for whom chemotherapy was recommended, nearly all oncologists chose an intensive regimen if the patient's age was 63; but if her age was 85, one fourth of the oncologists chose a less intensive treatment. Likewise, for stage IIA breast cancer (ECOG score, 0), 93% recommended intensive adjuvant treatment for a previously healthy patient aged 63; but only 66% said they would do so if the patient's age was 75. Oncologists commonly identified patient age as an influence on treatment choice, but were even more likely to cite performance status as a determining factor.

CONCLUSIONS

Advanced age can deter oncologists from choosing intensive cancer therapy, even if patients are highly functional and lack comorbidities. Education on tailoring cancer treatment and a greater use of comprehensive geriatric assessment may reduce cancer undertreatment in the geriatric population.

Heavy metal fractionation during the co-composting of biosolids, deinking paper fibre and green waste

Due to the introduction of the European Union Landfill Directive, composting has become a potentially viable disposal route for some organic wastes. As waste-derived compost is frequently added to soil to improve soil quality, it is important to quantify the environmental risk posed by potentially toxic elements contained within it. Here we used a sequential chemical extraction procedure to investigate the temporal dynamics of heavy metals (Cu, Zn, Pb and Ni) during the co-composting of biosolids, deinking paper fibre and green waste. Overall, composting over 26 weeks reduced the availability of Ni, had no effect on Pb and slightly increased the availability of Cu and Zn. We conclude that although the total Cu and Ni concentrations in the compost exceed legislative guidelines for land application, due to their recalcitrant nature within the compost, this compost posed very little threat to soil or plant quality if used in agriculture or land restoration.

Contaminated land clean-up using composted wastes and impacts of VOCs on land

This paper describes experiments that demonstrate the effects and potential for remediation of a former steelworks site in Wales polluted with polycyclic aromatic hydrocarbons (PAHs) and volatile organic compounds (VOCs). Under field conditions, PAH-contaminated soil was composted in-vessel, with or without organic feedstocks, receiving forced aeration for 80 days followed by 4 months maturation. Treatments compared PAH removal in contaminated soil to contaminated soil mixed with three different organic waste mixes after composting and after composts were spread to land. After composting, PAH concentrations declined in all treatments, by up to 38%. Sixteen months after the composts were landspread and vegetation was established, only those containing contaminated soil with organic additions exhibited further PAH removal, by up to 29%. Composting resulted in a decline in the relative concentration of small PAHs, whereas the landspreading-vegetation phase saw a decline in the relative concentration of medium PAHs in two of the three composts exhibiting PAH removal. Under controlled glasshouse conditions, vegetated soil columns of differing depths were exposed to VOCs from beneath. VOC vapour affected both shoot and root growth and soil microbial activity; effects varied with distance from the VOC source. This work demonstrated that on-site remediation of aged PAH-contaminated land can be successfully initiated by in-vessel co-composting followed by land spreading and vegetation, within a practical timeframe.

Initial tree establishment on blocky quarry waste ameliorated with hydrogel or slate processing fines

Pocket planting reclamation techniques developed in the 1970s for revegetating blocky quarrying waste have met with very limited success, often because the low water-holding capacity of the waste and limited root development within a small volume of planting pocket material result in severe drought mortality. We tested pocket planting approaches for waste tip reclamation at Europe's largest slate quarry, and compared materials for enhancing the continuity of water- and nutrient-holding down into the interior of the waste tip. When small compost-filled pocket planting bags were placed above slate processing fines (SPF) or water absorbent cross-linked polyacrylamide gel ("hydrogel"), tree growth rates increased in comparison with pocket planting bags alone. The SPF significantly improved tree survival especially during severe drought, but survival was not enhanced by the use of hydrogel. The sorption characteristics of hydrogel indicated that its presence may help to reduce nutrient leaching, but that it may have a negative effect on nitrogen availability. A more likely explanation for the poor performance of pure hydrogel is that it did not maintain sufficient available water, because of discontinuities caused by shrinkage and movement of the hydrogel, and/or degradation of water-holding capacity with environmental exposure. However, the root growth observed in the hydrogel treatments suggests that this technique, if adapted to reduce the effects of hydrogel shrinkage by using finer-grade hydrogel, mixing it with other soil-forming material, and reducing its exposure to extremes of temperature or sunlight, might have the potential to improve the growth and survival of trees planted on sites where delivery of heavy materials such as SPF is impractical. Fine mineral processing waste is freely available at active quarries and should be seen as a key resource for reclamation schemes.

Oxacillin-resistant Staphylococcus aureus endophthalmitis after ganciclovir intraocular implant

PURPOSE

To describe a patient who developed oxacillin-resistant Staphylococcus aureus endophthalmitis after insertion of a ganciclovir intraocular implant.

METHOD

Case report.

RESULTS

A 42-year-old man with acquired immunodeficiency syndrome (AIDS) and a history of cytomegalovirus retinitis was admitted with right-sided eye pain and decreased visual acuity 10 days after receiving a second ganciclovir intraocular implant in the right eye. A therapeutic vitrectomy, right eye, was performed on the day of admission. A vitreal tap produced frank pus and white, fluffy debris. Cultures of the vitreal fluid grew oxacillin-resistant S aureus, sensitive only to vancomycin, rifampin, and trimethoprim/sulfamethoxazole. The patient was successfully treated with removal of both ganciclovir implants in the right eye and a 4-week course of vancomycin and rifampin. However, the infection left the patient blind in the infected eye.

CONCLUSION

Bacterial endophthalmitis is an infrequent but serious complication of the ganciclovir intraocular implant.

Stability of cefepime in peritoneal dialysis solution

OBJECTIVE

To determine the stability of cefepime in peritoneal dialysis solution.

DESIGN

Cefepime HCl was added to premade bags of Delflex peritoneal dialysis solution with 1.5% dextrose to produce a cefepime concentration of approximately 100 microg/mL. Peritoneal dialysis solution bags were stored at 4, 25, and 37 degrees C to simulate refrigeration, room temperature, and body temperature, respectively. Samples were drawn at scheduled times up to 336, 168, and 48 hours, respectively, after the addition of cefepime HCl. Cefepime concentrations were measured by HPLC.

SETTING

This study was performed at a university-affiliated tertiary care hospital.

OUTCOME MEASURE

If the mean concentration of the samples at a given time and condition was >90% of the initial concentration, cefepime was considered stable at that time and condition.

RESULTS

The mean HPLC results for samples drawn at each time and condition were all >90%.

CONCLUSIONS

Cefepime is stable in peritoneal dialysis solution with dextrose 1.5% for 14 days refrigerated, seven days at room temperature, and 48 hours at 37 degrees C.

Bovine immunodeficiency virus tat gene: cloning of two distinct cDNAs and identification, characterization, and immunolocalization of the tat gene products

cDNAs encoding the bovine immunodeficiency virus (BIV) transactivator gene (tat) were cloned from virally infected cells and characterized. BIV expresses two distinct tat mRNAs composed of three exons that are derived by alternative splicing. The BIV tat mRNA splice variants encode Tat proteins of 103 (Tat103) and 108 (Tat108) amino acids. The Tat103 coding region is specified only by exon 2, while that of Tat108 is specified by a truncated exon 2 and the first 30 nt of exon 3. Thus, the first 98 amino acids of each Tat are identical, and have amino terminal, cysteine-rich, conserved core, basic, and carboxyl-terminal domains similar to Tats encoded by primate lentiviruses. BIV-infected bovine cells express a 14-kDa phosphorylated Tat protein identical in size to recombinant Tat expressed in bacteria. BIV Tat was shown to localize exclusively in the nucleoli of virally infected and Tat-expressing cells. Reporter gene assays indicated that Tat103 and Tat108 can strongly transactivate the BIV long terminal repeat (LTR) in virally permissive canine Cf2Th and nonpermissive HeLa and mouse NIH 3T3 cells, but not in permissive lapine EREp cells. However, an intact BIV tat gene is required for viral replication in both Cf2Th and EREp cells. Strong LTR activation by BIV Tat requires a TAR (transactivation responsive) element delimited by viral nt +1 to +31 and the Tat basic domain. BIV Tat strongly cross-transactivates the HIV-1 LTR in a TAR-dependent manner in Cf2Th, but not in EREp, HeLa, or NIH 3T3 cells. In contrast, strong, TAR-dependent cross-transactivation of the BIV LTR by HIV-1 Tat could not be demonstrated in any of these cell types. In Cf2Th cells Tat108 effects a moderately stronger transactivation of the BIV LTR than Tat103, indicative of a functional difference in BIV Tat proteins encoded by the mRNA splice variants. The present studies demonstrate that BIV Tat parallels the primate lentiviral Tats in structure and biochemistry but is not interchangeable with the latter.

Synthesis and assembly of chimeric human immunodeficiency virus gag pseudovirions

Expression of the HIV Gag precursor in insect cells by recombinant baculoviruses results in the assembly and budding of noninfectious pseudovirions that resemble immature virus. Three strategies for packaging additional viral epitopes into pseudovirions were examined: coinfection of insect cells with individual baculoviruses encoding separate Gag and Env structural genes, inframe Gag-Env fusion proteins, and Gag-frameshift-Env fusion proteins. Electron microscopy and Western blot analysis indicated that neither the coinfection nor the inframe fusion strategies reliably produced large quantities of structurally stable chimeric pseudovirions. The frameshift fusion method utilized the retroviral Gag-Pol ribosomal frameshift mechanism for the coexpression of Gag and Gag-frameshift-Env fusion proteins. Large quantities of pseudovirions containing both the Gag and Env epitopes were produced in insect cells. Mice inoculated with the Gag-frameshift-Env pseudovirions developed cytotoxic lymphocyte responses to both HIV Gag and Env epitopes. Vaccine and immunotherapeutic applications of chimeric pseudovirions are discussed.

Acid-base disorders: classification and management strategies

Acid-base disorders are common in clinical practice. Simple acid-base disturbances include metabolic acidosis, metabolic alkalosis, respiratory acidosis and respiratory alkalosis. Each can be clearly identified using a common clinical approach. Proper understanding of acid-base disorders requires knowledge of normal physiology. Each of the simple acid-base disorders can be diagnosed by obtaining a good history and performing a physical examination, followed by determinations of electrolyte levels, anion gap and pH. The degree and nature of compensation should then be analyzed. Finally, the ratio of the change in anion gap to the change in serum bicarbonate (delta AG/delta HCO3-) should be determined. When this diagnostic process is applied, proper identification of the disorder can be made and management can be undertaken. Mixed acid-base disorders can also be identified and managed using this method.

Diagnostic assay for Helicobacter hepaticus based on nucleotide sequence of its 16S rRNA gene

Conserved primers were used to PCR amplify 95% of the Helicobacter hepaticus 16S rRNA gene. Its sequence was determined and aligned to those of related bacteria, enabling the selection of primers to highly diverged regions of the 16S rRNA gene and an oligonucleotide probe for the development of a PCR-liquid hybridization assay. This assay was shown to be both sensitive and specific for H. hepaticus 16S rRNA gene sequences.

Characterization of bovine immunodeficiency virus rev cDNAs and identification and subcellular localization of the Rev protein

One of the six putative accessory genes of bovine immunodeficiency virus (BIV) is similar to those identified as rev in the human immunodeficiency virus and visna virus genomes. To further analyze the BIV rev gene locus, protein, and function, rev cDNAs were cloned and characterized. BIV rev mRNA is derived from the full-length transcript by multiple splicing events and consists of three exons, including the untranslated leader sequence and two coding exons. BIV rev cDNA was expressed in bacteria and in a mammalian in vitro translation expression system. A 23-kDa Rev protein (p23rev) was immunologically detected in lysates from both systems by using an antiserum made to a synthetic Rev peptide. Recombinant p23rev made in bacteria was purified and used to make a polyvalent antiserum. Antisera to Rev peptide and recombinant p23rev immunoprecipitated p23rev from BIV-infected mammalian cells but not from virions. A mammalian expression vector using the BIV rev cDNA was constructed; p23rev was immunoprecipitated with anti-Rev serum from 32P-labeled lysates of monkey cells transfected with this plasmid, demonstrating that BIV Rev is phosphorylated. Immunofluorescence and immunoelectron microscopy with anti-BIV Rev antisera localized Rev in the nucleus and, particularly, in the nucleoli of BIV-infected cells. In functional studies, the expression of BIV Rev was shown to positively regulate the appearance both of Gag protein, which is translated from the unspliced primary viral transcript, and of singly spliced env mRNA but not that of the multiply spliced tat mRNA. These results demonstrate that BIV Rev activity correlates with the known function of lentivirus Rev proteins.