FBXW7 regulates DISC1 stability via the ubiquitin-proteosome system.

Disrupted in schizophrenia 1 (DISC1) is a multi-functional scaffolding protein that has been associated with neuropsychiatric disease. The role of DISC1 is to assemble protein complexes that promote neural development and signaling, hence tight control of the concentration of cellular DISC1 in neurons is vital to brain function. Using structural and biochemical techniques, we show for we believe the first time that not only is DISC1 turnover elicited by the ubiquitin proteasome system (UPS) but that it is orchestrated by the F-Box protein, FBXW7. We present the structure of FBXW7 bound to the DISC1 phosphodegron motif and exploit this information to prove that disruption of the FBXW7-DISC1 complex results in a stabilization of DISC1. This action can counteract DISC1 deficiencies observed in neural progenitor cells derived from induced pluripotent stem cells from schizophrenia patients with a DISC1 frameshift mutation. Thus manipulation of DISC1 levels via the UPS may provide a novel method to explore DISC1 function.

Human phosphodiesterase 4D7 (PDE4D7) expression is increased in TMPRSS2-ERG-positive primary prostate cancer and independently adds to a reduced risk of post-surgical disease progression.

BACKGROUND: There is an acute need to uncover biomarkers that reflect the molecular pathologies, underpinning prostate cancer progression and poor patient outcome. We have previously demonstrated that in prostate cancer cell lines PDE4D7 is downregulated in advanced cases of the disease. To investigate further the prognostic power of PDE4D7 expression during prostate cancer progression and assess how downregulation of this PDE isoform may affect disease outcome, we have examined PDE4D7 expression in physiologically relevant primary human samples. METHODS: About 1405 patient samples across 8 publically available qPCR, Affymetrix Exon 1.0 ST arrays and RNA sequencing data sets were screened for PDE4D7 expression. The TMPRSS2-ERG gene rearrangement status of patient samples was determined by transformation of the exon array and RNA seq expression data to robust z-scores followed by the application of a threshold>3 to define a positive TMPRSS2-ERG gene fusion event in a tumour sample. RESULTS: We demonstrate that PDE4D7 expression positively correlates with primary tumour development. We also show a positive association with the highly prostate cancer-specific gene rearrangement between TMPRSS2 and the ETS transcription factor family member ERG. In addition, we find that in primary TMPRSS2-ERG-positive tumours PDE4D7 expression is significantly positively correlated with low-grade disease and a reduced likelihood of progression after primary treatment. Conversely, PDE4D7 transcript levels become significantly decreased in castration resistant prostate cancer (CRPC). CONCLUSIONS: We further characterise and add physiological relevance to PDE4D7 as a novel marker that is associated with the development and progression of prostate tumours. We propose that the assessment of PDE4D7 levels may provide a novel, independent predictor of post-surgical disease progression.

The cAMP phosphodiesterase-4D7 (PDE4D7) is downregulated in androgen-independent prostate cancer cells and mediates proliferation by compartmentalising cAMP at the plasma membrane of VCaP prostate cancer cells.

BACKGROUND: Isoforms of the PDE4 family of cAMP-specific phosphodiesterases (PDEs) are expressed in a cell type-dependent manner and contribute to underpinning the paradigm of intracellular cAMP signal compartmentalisation. Here we identify the differential regulation of the PDE4D7 isoform during prostate cancer progression and uncover a role in controlling prostate cancer cell proliferation. METHODS: PDE4 transcripts from 19 prostate cancer cell lines and xenografts were quantified by qPCR. PDE4D7 expression was further investigated because of its significant downregulation between androgen-sensitive (AS) and androgen-insensitive (AI) samples. Western blot analysis, PDE activity assay, immunofluorescent staining and cAMP responsive FRET assays were used to investigate the sub-plasma membrane localisation of a population of PDE4D7 in VCaP (AS) and PC3 (AI) cell lines. Disruption of this localisation pattern using dominant-negative protein expression and siRNA knockdown showed that PDE4D7 acts in opposition to proliferative signalling as assessed by electrical impedance-based proliferation assays. RESULTS: Here we identify the differential regulation of the PDE4D7 isoform during prostate cancer progression. PDE4D7 is highly expressed in AS cells and starkly downregulated in AI samples. The significance of this downregulation is underscored by our finding that PDE4D7 contributes a major fraction of cAMP degrading PDE activity tethered at the plasma membrane and that displacement of PDE4D7 from this compartment leads to an increase in the proliferation of prostate cancer cells. PDE4D7 mRNA expression is not, however, directly regulated by the androgen receptor signalling axis despite an overlapping genomic structure with the androgen responsive gene PART1. PDE4D7, which locates to the plasma membrane, acts to supress aberrant non-steroidal growth signals within the prostate or AS metastasis. CONCLUSIONS: PDE4D7 expression is significantly downregulated between AS and AI cell phenotypes. This change in expression potentially provides a novel androgen-independent biomarker and manipulation of its activity or its expression may provide therapeutic possibilities and insights into contributory aspects of the complex molecular pathology of prostate cancer.

Cholinergic deregulation in traumatic brain injury could be a pathophysiology-related biphasic epiphenomenon.

No abstract available.

Estimating reassortment rates in co-circulating Eurasian swine influenza viruses.

Swine have often been considered as a mixing vessel for different influenza strains. In order to assess their role in more detail, we undertook a retrospective sequencing study to detect and characterize the reassortants present in European swine and to estimate the rate of reassortment between H1N1, H1N2 and H3N2 subtypes with Eurasian (avian-like) internal protein-coding segments. We analysed 69 newly obtained whole genome sequences of subtypes H1N1-H3N2 from swine influenza viruses sampled between 1982 and 2008, using Illumina and 454 platforms. Analyses of these genomes, together with previously published genomes, revealed a large monophyletic clade of Eurasian swine-lineage polymerase segments containing H1N1, H1N2 and H3N2 subtypes. We subsequently examined reassortments between the haemagglutinin and neuraminidase segments and estimated the reassortment rates between lineages using a recently developed evolutionary analysis method. High rates of reassortment between H1N2 and H1N1 Eurasian swine lineages were detected in European strains, with an average of one reassortment every 2-3 years. This rapid reassortment results from co-circulating lineages in swine, and in consequence we should expect further reassortments between currently circulating swine strains and the recent swine-origin H1N1v pandemic strain.

Disruption of the cyclic AMP phosphodiesterase-4 (PDE4)-HSP20 complex attenuates the ß-agonist induced hypertrophic response in cardiac myocytes.

The small heat shock protein HSP20 is known to be cardioprotective during times of stress and the mechanism underlying its protective abilities depends on its phosphorylation on Ser16 by PKA (protein kinase A). Although the external stimuli that trigger Ser16 phosphorylation have been well studied, the events that modulate spatial and temporal control of this modification remain to be clarified. Here, we report that inhibition of cAMP phosphodiesterase-4 (PDE4) induces the phosphorylation of HSP20 in resting cardiac myocytes and augments its phosphorylation by PKA following ß-adrenergic stimulation. Moreover, using peptide array technology, in vitro binding studies, co-immunoprecipitation techniques and immunocytochemistry, we show that HSP20 binds directly to PDE4 within a region of the conserved catalytic domain. We also show that FRET-based, genetically-encoded cAMP reporters anchored to HSP20 exhibit a larger response to PDE4 inhibition compared to free cytosolic cAMP reporters, suggesting that the interaction with PDE4 is crucial in modulating the highly localised pool of cAMP to which HSP20 is exposed. Using information gleaned from peptide array analyses, we developed a cell-permeable peptide that serves to inhibit the interaction of PDE4 with HSP20. Disruption of the HSP20-PDE4 complex, using this peptide, suffices to induce phosphorylation of HSP20 by PKA and to protect against the hypertrophic response measured in neonatal cardiac myocytes following chronic ß-adrenergic stimulation.

Hematologic complications of anti-CMV therapy in solid organ transplant recipients.

Cytomegalovirus (CMV) infection complicates the post-operative course of patients receiving solid organ transplants. While ganciclovir has significantly reduced the direct effects of CMV infection, some patients cannot tolerate the optimal therapeutic exposure required for CMV prevention and treatment. Few reports directly address the incidence, consequences, and risk factors for hematologic toxicities related to ganciclovir therapy. Nevertheless, leukopenia, thrombocytopenia, and anemia occur in 5-50% of patients. Current strategies, focused on ganciclovir dose reduction, may increase the risk of CMV reactivation and drug-resistant disease. The current article reviews the incidence, risk factors, and consequences of ganciclovir-associated hematologic adverse events in transplant recipients. Management strategies, including ganciclovir dose reduction, and the addition of CMV hyperimmune globulin are discussed. Exposing this relatively frequently occurring, but uncommonly discussed, toxicity should lead to better avoidance and treatment strategies, without placing patients at increased risk of CMV disease.

The use of drotrecogin alfa (activated) in solid organ transplant patients: a case series.

BACKGROUND: Drotrecogin alfa (activated) (DAA), a recombinant human activated protein C, is indicated for the reduction of mortality in patients with severe sepsis who have a high risk of death. In the initial trial, DAA demonstrated a significant reduction in mortality at 28 days for patients treated with DAA in comparison with standard supportive treatment (placebo). However, solid organ transplant recipients were excluded from the study. Transplant recipients are at an increased risk for sepsis and there is minimal literature describing the safety and efficacy of DAA in the transplant population. METHODS: Thirteen solid organ transplant recipients who received DAA between November 2001 and January 2004 were included in this case series. Patients were prospectively identified and data collection occurred concurrently and by retrospective chart review. All patients met the DAA use criteria based on the institutional standard protocol. RESULTS: We report the outcomes of the 13 adult transplant patients who received a total of 14 courses of DAA for severe sepsis. At the time of DAA initiation, all patients required mechanical ventilation, 86% necessitated vasopressor support, and had a median of 3 dysfunctional organs. The median Acute Physiology and Chronic Health Evaluation (APACHE) II score at initiation was 30. Overall, hemodynamic stability and APACHE II score improved at the end of DAA infusion. Causes of early discontinuation were bleeding (57%), scheduled procedure (14%), increased international normalized ratio (14%), and death (14%). In-hospital, 28-day, and 1-year mortality was 69%, 62%, and 83%, respectively. CONCLUSION: DAA appears to be safe with appropriate monitoring. However, transplant recipients had a higher incidence of bleeding events leading to early discontinuation of DAA. Efficacy is difficult to assess without an appropriate control group for comparison.

Phosphorylation of PDE4A5 by MAPKAPK2 attenuates fibrin degradation via p75 signalling.

Phosphodiesterases (PDEs) shape local cAMP gradients to underpin the specificity of receptor function. Key to this process is the highly defined nature of the intra-cellular location of PDEs in the cell. PDE4A5 is a PDE isoform that specifically degrades cAMP and is known to associate with the p75 neurotrophin receptor (p75NTR) where it modulates cAMP signalling cascades that regulate extracellular matrix remodelling in the lungs. Here we map and validate novel protein-protein interaction sites that are important for formation of the PDE4A5-p75NTR complex and show, for the first time, that phosphorylation of PDE4A5 by MAPKAPK2 enhances PDE4A5 interaction with p75NTR and that this, in turn, serves to attenuate fibrin degradation.

Cannabidiol displays unexpectedly high potency as an antagonist of CB1 and CB2 receptor agonists in vitro.

BACKGROUND AND PURPOSE: A nonpsychoactive constituent of the cannabis plant, cannabidiol has been demonstrated to have low affinity for both cannabinoid CB1 and CB2 receptors. We have shown previously that cannabidiol can enhance electrically evoked contractions of the mouse vas deferens, suggestive of inverse agonism. We have also shown that cannabidiol can antagonize cannabinoid receptor agonists in this tissue with a greater potency than we would expect from its poor affinity for cannabinoid receptors. This study aimed to investigate whether these properties of cannabidiol extend to CB1 receptors expressed in mouse brain and to human CB2 receptors that have been transfected into CHO cells. EXPERIMENTAL APPROACH: The [35S]GTPS binding assay was used to determine both the efficacy of cannabidiol and the ability of cannabidiol to antagonize cannabinoid receptor agonists (CP55940 and R-(+)-WIN55212) at the mouse CB1 and the human CB2 receptor. KEY RESULTS: This paper reports firstly that cannabidiol displays inverse agonism at the human CB2 receptor. Secondly, we demonstrate that cannabidiol is a high potency antagonist of cannabinoid receptor agonists in mouse brain and in membranes from CHO cells transfected with human CB2 receptors. CONCLUSIONS AND IMPLICATIONS: This study has provided the first evidence that cannabidiol can display CB2 receptor inverse agonism, an action that appears to be responsible for its antagonism of CP55940 at the human CB2 receptor. The ability of cannabidiol to behave as a CB2 receptor inverse agonist may contribute to its documented anti-inflammatory properties.

Use of bone health protocol to identify and prevent bone disease in kidney and pancreas transplant recipients.

BACKGROUND: Posttransplant bone disease is a well recognized and undertreated problem. The use of protocols within other populations has been shown to improve recognition and treatment of common disease states, but outcome studies involving the use of protocols within transplant patients are lacking. OBJECTIVE: To compare the appropriate screening for and the prevention and treatment of osteopenia and osteoporosis in transplant patients before and after a bone health protocol was implemented. METHODS: A retrospective analysis in a single institution was designed to determine whether the development and implementation of a comprehensive bone health protocol impacted disease outcomes in posttransplant kidney and simultaneous kidney-pancreas patients. RESULTS: There were 132 patients in the historical control group and 76 in the treatment group. The groups were well matched, with no statistically significant differences noted for any of the baseline characteristics that were compared, including the modifiable and nonmodifiable risk factors known to put a patient at increased risk for osteopenia or osteoporosis. Significantly more patients in the treatment group received proper screening and prevention compared with the historical control group (p < 0.001). Although more patients in the treatment group received proper bone disease treatment, this did not reach statistical significance (81% vs 66%; p < 0.22). Additionally, the dual energy X-ray absorptiometry scans were performed, on average, 19 days earlier in the treatment group, although this also did not achieve statistical significance (p = 0.149). CONCLUSIONS: The multidisciplinary development and implementation of a comprehensive bone health protocol improves the screening and prevention of osteopenia and osteoporosis within kidney and pancreas transplant recipients.

Prevention of cytomegalovirus disease in solid organ transplant patients: prophylactic versus preemptive therapy.

PURPOSE: The advantages and disadvantages of universal prophylaxis and preemptive therapy and current evidence-based recommendations for preventing cytomegalovirus (CMV) disease in solid organ transplant recipients are discussed. SUMMARY: Advantages of universal prophylaxis include the ease of implementation, a reduced incidence of CMV disease, and possibly fewer indirect effects of CMV infection. Disadvantages of universal prophylaxis may include prolonged antiviral drug exposure, resistance, toxicity, the development of late-onset CMV disease, and greater drug costs. Advantages of preemptive therapy may include reduced drug exposure and decreased risk for toxicity and resistance. Disadvantages include the logistic demands of laboratory testing, uncertainty about the impact on the indirect effects of CMV disease, and the costs associated with failure to prevent CMV disease. Evidence-based guidelines call for universal prophylaxis for patients at highest risk for CMV disease. Preemptive therapy may be most appropriate for those at a moderate or low risk of CMV. Antiviral drug regimens used for universal prophylaxis depend on the type of organ transplanted and the donor-recipient CMV serostatus. The optimal preemptive drug regimen and laboratory monitoring strategy are unknown. CONCLUSION: Selection of a strategy for preventing CMV disease in solid organ transplant patients requires consideration of patient-specific risk factors as well as practical considerations, such as available resources.

Does bioequivalence between modified cyclosporine formulations translate into equal outcomes?

Neoral was replaced with a generic cyclosporine formulation on our hospital formulary. We compared outcomes for de novo kidney transplant recipients who either received Gengraf (n=88) or Neoral (n=100) in a single-center, retrospective review. As compared to patients who received Neoral, patients who received Gengraf were significantly more likely to have an acute rejection episode (39% vs. 25%, P=0.04), more likely to have a second rejection episode (13% vs. 4%; P=0.03), or to have received an antibody preparation to treat acute rejection (19% vs. 8%; P=0.02). Patients treated with Gengraf had a higher degree of intrapatient variability for cyclosporine trough concentrations as determined by %CV (P<0.05). The incidence of acute rejection at 6 months posttransplant was significantly higher in patients who received Gengraf compared to Neoral. A larger, prospective analysis is warranted to compare these formulations of cyclosporine in de novo kidney transplant recipients.

Pharmacokinetics of antiviral agents for the treatment of cytomegalovirus infection.

PURPOSE: The mechanism of action, pharmacokinetics, and other advantages and disadvantages of ganciclovir and valganciclovir are discussed. SUMMARY: Shortcomings of oral ganciclovir include low bioavailability, large pill burden, patient nonadherence, and the emergence of resistance. Valganciclovir, an oral prodrug of ganciclovir, has a nearly tenfold greater absolute bioavailability than ganciclovir. Dosage adjustment is required for both drugs in patients with renal impairment. CONCLUSION: The pharmacokinetic profile of valganciclovir offers significant advantages for its use in cytomegalovirus (CMV) prophylaxis.

Long-term outcome of sirolimus rescue in kidney-pancreas transplantation.

Sirolimus (SRL) rescue in kidney-pancreas transplantation has not been well described. We reviewed 112 KPTxs performed at our institution between December 3, 1995 and June 27, 2002. All patients received antibody induction, tacrolimus (TAC), mycophenolate mofetil (MMF), and steroids. In 35 patients, SRL was substituted for MMF for the following reasons: acute rejection (AR) of kidney or pancreas despite adequate TAC levels, MMF intolerance, increasing creatinine levels, and TAC-induced hyperglycemia. Three-year kidney and pancreas graft survivals were 97% and 90%, respectively. Of 10 patients who were switched to SRL because of AR, one kidney failed because of antibody-resistant AR, and one kidney developed borderline AR; the other eight patients remain AR-free. AR developed in seven other patients despite therapeutic SRL levels; six had TAC levels less than 4.5 ng/mL. The mean creatinine levels overall and for the group with increasing creatinine remained stable. All patients who were switched to SRL for TAC-induced hyperglycemia or MMF intolerance improved. Kidney-pancreas transplant recipients can be safely switched to SRL with excellent graft and patient survival.

Sub-family selective actions in the ability of Erk2 MAP kinase to phosphorylate and regulate the activity of PDE4 cyclic AMP-specific phosphodiesterases.

Expressed in intact cells and in vitro, PDE4B and PDE4C isoenzymes of cyclic nucleotide phosphodiesterase (PDE), in common with PDE4D isoenzymes, are shown to provide substrates for C-terminal catalytic unit phosphorylation by the extracellular signal-regulated kinase Erk2 (p42(MAPK)). In contrast, PDE4A isoenzymes do not provide substrates for C-terminal catalytic unit phosphorylation by Erk2. Mutant PDE4 enzymes were generated to show that Erk2 phosphorylation occurs at a single, cognate serine residue located within the C-terminal portion of the PDE4 catalytic unit. PDE4 long-form isoenzymes were markedly inhibited by Erk2 phosphorylation. The short-form PDE4B2 isoenzyme was activated by Erk2 phosphorylation. These functional changes in PDE activity were mimicked by mutation of the target serine for Erk2 phosphorylation to the negatively charged amino acid, aspartic acid. Epidermal growth factor (EGF) challenge caused diametrically opposed changes in cyclic AMP levels in COS1 cells transfected to express the long PDE4B1 isoenzyme compared to cells expressing the short PDE4B2 isoenzyme. We suggest that PDE4 enzymes may provide a pivotal point for integrating cyclic AMP and Erk signal transduction in cells with 4 genes encoding enzymes that are either insensitive to Erk2 action or may either be activated or inhibited. This indicates that PDE4 isoenzymes have distinct functional roles, giving credence to the notion that distinct therapeutic benefits may accrue using either PDE4 subfamily or isoenzyme-selective inhibitors.

Production of extracellular matrix by Candida albicans biofilms.

Growth of Candida albicans biofilms and production of extracellular matrix were monitored by dry weight, colorimetric and radioisotope assays, and by scanning electron microscopy. Under static incubation conditions synthesis of matrix material was minimal, but increased dramatically when developing biofilms were subjected to a liquid flow with the result that the cells were enveloped in extracellular polymer. These findings suggest that production of matrix material could contribute to the resistance of biofilm cells to antifungal agents in vivo.

Influence of mild obesity on outcome of simultaneous pancreas and kidney transplantation.

The influence of body mass index (BMI) on outcome of simultaneous pancreas-kidney transplantation (SPK) has not been well described. We retrospectively reviewed 88 consecutive primary SPKs performed at our institution between March 15, 1995 and August 28, 2001. All patients received antibody induction and maintenance immunosuppression with tacrolimus, mycophenolate mofetil, and steroids. Systemic-enteric implantation was performed in all patients. Primary end points were patient, pancreas, and kidney survival. Secondary end points were rates of anastomotic leakage, pancreas thrombosis, major infection, rejection, repeat laparotomy, and length of hospital stay. Values are shown as mean+/-standard deviation, range, or percentage. Fifty-two patients (59.1%) were nonobese with a BMI < or =24.9 (mean 21.7+/-2.2, range 15.4 to 24.9). Thirty-six patients were mild to moderately obese with a BMI > or =25 (mean 27.7+/-2.2, range 25 to 35.1). Distribution of recipient age, sex, and ethnicity was similar between groups. Kidney and pancreas preservation times were similar between nonobese and obese patients. One-, three-, and five-year actuarial patient (nonobese: 95%, 95%, 95% vs. obese: 95%, 95%, 89%), kidney graft (nonobese: 91%, 91%, 87% vs. obese: 97%, 91%, 85%), and pancreas graft (nonobese: 78%, 78%, 73% vs. obese: 70%, 62%, 62%) survival were comparable between nonobese and obese (P=NS). The mean rates of pancreas thrombosis, major infection, pancreas rejection, kidney rejection, relaparotomy, and length of hospital stay were similar in the two groups. The overall duodenojejunal anastomotic leakage rate was 8%. Obese patients had a 17% incidence of leakage (6 of 36) compared to a 2% incidence of leakage in nonobese patients (P=0.012). Six of seven leaks occurred in obese patients. Mean BMI in the seven patients with a leak (27+/-1.9) was significantly higher than in patients who did not develop a leak (24+/-3.7; P=0.05). Although obesity had no effect on patient or graft survival, it was associated with a significantly higher leakage rate. There should therefore be a higher degree of suspicion for the presence of duodenojejunal anastomotic leaks in obese SPK recipients.

Bradycardia associated with intravenous administration of tacrolimus in a liver transplant recipient.

Cardiotoxicity due to tacrolimus is documented infrequently in the medical literature. Sinus bradycardia associated with intravenous tacrolimus occurred in a 15-year-old orthotopic liver transplant recipient. The mechanism of this adverse effect is unknown; however, it does not appear to be concentration dependent, and in this patient it resolved on changing to oral therapy. Practitioners should be aware that intravenous administration of tacrolimus may be associated with adverse cardiac events including sinus bradycardia.

Phaeohyphomycosis from Exphiala jeanselmei with concomitant Nocardia asteroides infection in a renal transplant recipient: case report and review of the literature.

A 59-year-old black man who received a cadaveric renal transplant 15 months earlier developed subcutaneous nodules on his right upper extremity that were identified as phaeohyphomycosis caused by Exophiala jeanselmei. The man was admitted 4 weeks later with a swollen left arm and had Nocardia asteroides in this area and in the apex of his left lung. He was treated with surgical excision, and itraconazole, imipenem-cilastatin, and trimethoprim-sulfamethoxazole. With the potential presence of more than one microorganism in an immunocompromised patient, it is important to identify and differentiate them correctly to direct appropriate therapy.