cGMP-dependent protein kinase Iα associates with the antidepressant-sensitive serotonin transporter and dictates rapid modulation of serotonin uptake

<p>Abstract</p> <p>Background</p> <p>The Na⁺/Cl^--dependent serotonin (5-hydroxytryptamine, 5-HT) transporter (SERT) is a critical element in neuronal 5-HT signaling, being responsible for the efficient elimination of 5-HT after release. SERTs are not only targets for exogenous addictive and therapeutic agents but also can be modulated by endogenous, receptor-linked signaling pathways. We have shown that neuronal A3 adenosine receptor activation leads to enhanced presynaptic 5-HT transport <it>in vitro </it>and an increased rate of SERT-mediated 5-HT clearance <it>in vivo</it>. SERT stimulation by A3 adenosine receptors derives from an elevation of cGMP and subsequent activation of both cGMP-dependent protein kinase (PKG) and p38 mitogen-activated protein kinase. PKG activators such as 8-Br-cGMP are known to lead to transporter phosphorylation, though how this modification supports SERT regulation is unclear.</p> <p>Results</p> <p>In this report, we explore the kinase isoform specificity underlying the rapid stimulation of SERT activity by PKG activators. Using immortalized, rat serotonergic raphe neurons (RN46A) previously shown to support 8-Br-cGMP stimulation of SERT surface trafficking, we document expression of PKGI, and to a lower extent, PKGII. Quantitative analysis of staining profiles using permeabilized or nonpermeabilized conditions reveals that SERT colocalizes with PKGI in both intracellular and cell surface domains of RN46A cell bodies, and exhibits a more restricted, intracellular pattern of colocalization in neuritic processes. In the same cells, SERT demonstrates a lack of colocalization with PKGII in either intracellular or surface membranes. In keeping with the ability of the membrane permeant kinase inhibitor DT-2 to block 8-Br-cGMP stimulation of SERT, we found that DT-2 treatment eliminated cGMP-dependent kinase activity in PKGI-immunoreactive extracts resolved by liquid chromatography. Similarly, treatment of SERT-transfected HeLa cells with small interfering RNAs targeting endogenous PKGI eliminated 8-Br-cGMP-induced regulation of SERT activity. Co-immunoprecipitation studies show that, in transporter/kinase co-transfected cells, PKGIα specifically associates with hSERT.</p> <p>Conclusion</p> <p>Our findings provide evidence of a physical and compartmentalized association between SERT and PKGIα that supports rapid, 8-Br-cGMP-induced regulation of SERT. We discuss a model wherein SERT-associated PKGIα supports sequentially the mobilization of intracellular transporter-containing vesicles, leading to enhanced surface expression, and the production of catalytic-modulatory SERT phosphorylation, leading to a maximal enhancement of 5-HT clearance capacity.</p

Overdiagnosis and overtreatment of breast cancer: Is overdiagnosis an issue for radiologists?

Overdiagnosis is diagnosis of cancers that would not present within the life of the patient and is one of the downsides of screening. This applies to low-grade ductal carcinoma in situ and some small grade 1 invasive cancers. Radiologists are responsible for cancer diagnosis, but at the time of diagnosis they cannot determine whether a particular low-grade diagnosis is one to which the definition of overdiagnosis applies. Overdiagnosis is likely to be driven by technological developments, including digital mammography, computer-aided detection and improved biopsy techniques. It is also driven by the patient's fear that cancer will be missed and the doctor's fear of litigation. It is therefore an issue of importance for radiologists, presenting them with difficult fine-tuned decisions in every assessment clinic that are ultimately counted later by those who evaluate their screening

What counts as reliable evidence for public health policy: the case of circumcision for preventing HIV infection

<p>Abstract</p> <p>Background</p> <p>There is an ongoing controversy over the relative merits of randomized controlled trials (RCTs) and non-randomized observational studies in assessing efficacy and guiding policy. In this paper we examine male circumcision to prevent HIV infection as a case study that can illuminate the appropriate role of different types of evidence for public health interventions.</p> <p>Discussion</p> <p>Based on an analysis of two Cochrane reviews, one published in 2003 before the results of three RCTs, and one in 2009, we argue that if we rely solely on evidence from RCTs and exclude evidence from well-designed non-randomized studies, we limit our ability to provide sound public health recommendations. Furthermore, the bias in favor of RCT evidence has delayed research on policy relevant issues.</p> <p>Summary</p> <p>This case study of circumcision and HIV prevention demonstrates that if we rely solely on evidence from RCTs and exclude evidence from well-designed non-randomized studies, we limit our ability to provide sound public health recommendations.</p

Surgery for fistula-in-ano in a specialist colorectal unit: a critical appraisal

ABSTRACT

Mobility and other predictors of hospitalization for urinary tract infection: a retrospective cohort study

Abstract Background Many hospitalizations for residents of skilled nursing facilities are potentially avoidable. Factors that could prevent hospitalization for urinary tract infection (UTI) were investigated, with focus on patient mobility. Methods A retrospective cohort study was conducted using 2003–2004 data from the Centers for Medicare and Medicaid Services. The study included 408,192 residents of 4267 skilled nursing facilities in California, Florida, Michigan, New York, and Texas. The patients were followed over time, from admission to the skilled nursing facility to discharge or, for those who were not discharged, for 1 year. Cox proportional hazards regression was conducted with hospitalization for UTI as the outcome. Results The ability to walk was associated with a 69% lower rate of hospitalization for UTI. Maintaining or improving walking ability over time reduced the risk of hospitalization for UTI by 39% to 76% for patients with various conditions. For residents with severe mobility problems, such as being in a wheelchair or having a missing limb, maintaining or improving mobility (in bed or when transferring) reduced the risk of hospitalization for UTI by 38% to 80%. Other potentially modifiable predictors included a physician visit at the time of admission to the skilled nursing facility (Hazard Ratio (HR), 0.68), use of an indwelling urinary catheter (HR, 2.78), infection with Clostridium difficile or an antibiotic-resistant microorganism (HR, 1.20), and use of 10 or more medications (HR, 1.31). Patient characteristics associated with hospitalization for UTI were advancing age, being Hispanic or African-American, and having diabetes mellitus, renal failure, Parkinson's disease, dementia, or stroke. Conclusion Maintaining or improving mobility (walking, transferring between positions, or moving in bed) was associated with a lower risk of hospitalization for UTI. A physician visit at the time of admission to the skilled nursing facility also reduced the risk of hospitalization for UTI.http://deepblue.lib.umich.edu/bitstream/2027.42/112369/1/12877_2008_Article_125.pd

Identification of epithelialization in high transsphincteric fistulas

textabstractBackground At present, transanal advancement flap repair (TAFR) is the treatment of choice for transsphincteric fistulas passing through the upper and middle third of the external anal sphincter. It has been suggested that epithelialization of the fistula tract contributes to the failure of the treatment. The aim of this study was to assess the prevalence of epithelialization of the fistula tract and to study its effect on the outcome of TAFR and TAFR combined with ligation of the intersphincteric fistula tract (LIFT). Methods Forty-four patients with a high transsphincteric fistula of cryptoglandular origin underwent TAFR. Nine of these patients underwent a combined procedure of TAFR with LIFT. In all patients the fistula tract was excised from the external opening up to the outer border of the external anal sphincter. In patients undergoing TAFR combined with LIFT an additional central part of the intersphincteric fistula tract was excised. A total of 53 specimens were submitted. Histopathological examination of the specimens was carried out by a pathologist, blinded for clinical data. Results Epithelialization of the distal and intersphincteric fistula tract was observed in only 25 and 22% of fistulas, respectively. There was no difference in outcome between fistulas with or without epithelialization. Conclusions Epithelialization of high transsphincteric fistulas is rare and does not affect the outcome of TAFR and TAFR combined with LIFT

A new method for determining physician decision thresholds using empiric, uncertain recommendations

<p>Abstract</p> <p>Background</p> <p>The concept of risk thresholds has been studied in medical decision making for over 30 years. During that time, physicians have been shown to be poor at estimating the probabilities required to use this method. To better assess physician risk thresholds and to more closely model medical decision making, we set out to design and test a method that derives thresholds from actual physician treatment recommendations. Such an approach would avoid the need to ask physicians for estimates of patient risk when trying to determine individual thresholds for treatment. Assessments of physician decision making are increasingly relevant as new data are generated from clinical research. For example, recommendations made in the setting of ocular hypertension are of interest as a large clinical trial has identified new risk factors that should be considered by physicians. Precisely how physicians use this new information when making treatment recommendations has not yet been determined.</p> <p>Results</p> <p>We derived a new method for estimating treatment thresholds using ordinal logistic regression and tested it by asking ophthalmologists to review cases of ocular hypertension before expressing how likely they would be to recommend treatment. Fifty-eight physicians were recruited from the American Glaucoma Society. Demographic information was collected from the participating physicians and the treatment threshold for each physician was estimated. The method was validated by showing that while treatment thresholds varied over a wide range, the most common values were consistent with the 10-15% 5-year risk of glaucoma suggested by expert opinion and decision analysis.</p> <p>Conclusions</p> <p>This method has advantages over prior means of assessing treatment thresholds. It does not require physicians to explicitly estimate patient risk and it allows for uncertainty in the recommendations. These advantages will make it possible to use this method when assessing interventions intended to alter clinical decision making.</p

Haste Makes Waste: Accelerated Molt Adversely Affects the Expression of Melanin-Based and Depigmented Plumage Ornaments in House Sparrows

. Costly life-history events are adaptively separated in time, thus, when reproduction is extended, the time available for molt is curtailed and, in turn, molt rate is accelerated.We experimentally accelerated the molt rate by shortening the photoperiod in order to test whether this environmental constraint is mirrored in the expression of plumage ornaments. Sparrows which had undergone an accelerated molt developed smaller badges and less bright wing-bars compared to conspecifics that molted at a natural rate being held at natural-like photoperiod. There was no difference in the brightness of the badge or the size of the wing-bar.These results indicate that the time available for molt and thus the rate at which molt occurs may constrain the expression of melanin-based and depigmented plumage advertisements. This mechanism may lead to the evolution of honest signaling if the onset of molt is condition-dependent through the timing of and/or trade-off between breeding and molt