Imaging reticulospinal neurons in the lamprey brainstem using calcium indicator

Abstract only availableImaging reticulospinal neurons in the lamprey brainstem using calcium indicator In the lamprey, a lower vertebrate, reticulospinal (RS) neurons in the brain are the output elements of the command system that activate spinal pattern generators and initiate swimming. In order to better understand the locomotor command system in the lamprey, it is necessary to determine the locations of neurons in the network, as well as their connectivity and patterns of activity. Calcium indicator dyes are an important technique for labeling and monitoring neuron activity. During impulse, calcium enters neurons and binds to the dye, increasing the fluorescence of the dye and creating an optical image that can be recorded and analyzed. In the present study, Calcium Green dextran amine was applied to the transected spinal cord at 20% body length (BL). After retrograde transport of the dye and labeling of RS neurons, the brain and spinal cord were removed and placed on a slide for viewing under a microscope equipped for fluorescence. Electrical stimulation of the spinal cord activated labeled RS neurons in the brain, resulting in a fluorescence increase that was recorded by an S-VHS video camera. The next step will be to image RS neuron activity during actual swimming movements. For this purpose, RS neurons will be labeled in a semi-intact preparation in which the brain and upper spinal cord are exposed and the lower half of the body is free to produce swimming movements. As a control experiment, the spinal cord was transected and Calcium Green applied at 60% BL. Semi-intact preparations were observed to produce swimming movements. Imaging of the isolated brain and rostral spinal cord showed RS neuron labeling and fluorescent changes similar to when tracer was applied at 20% BL. These results lay the groundwork for imaging brain neuron activity during actual swimming behavior.Life Sciences Undergraduate Research Opportunity Progra

Assessing biocompatibility of porcine tissue for hernia repair using flow cytometry [abstract]

Abstract only availableThe current standard for abdominal hernia repair uses synthetic meshes, which often break down, leading to complications and a high rate of recurrence. A biologic prosthetic, derived from animal tissue, would provide a more natural substrate for tissue remodeling and an improved host response. The success of a biologic material for tissue repair first depends on preventing an immune reaction post implantation. Engineering an appropriate construct requires removal of cells from the donor tissue, stabilization of the resulting collagen matrix with cross-linkers, and sterilization prior to implantation. The central tendon of the porcine diaphragm is a novel material for use as a biologic implant. This study is a preliminary investigation of the biocompatibility of porcine diaphragm as a hernia mesh material. Diaphragm tissue was de-cellularized by one of two methods and cross-linked with one of two chemical agents. Combinations of these two treatments were cultured with mouse fibroblast cells. Viability was assessed with flow cytometry, using propridium iodine to stain non-vital cells. Cell viability on treated tissue was compared to untreated tissue and control cell sets. Results indicate superior biocompatibility of one preparation, with viability high enough to warrant further studies. The next step will be implantation of the material into an animal model. With successful preparation, biological constructs can improve the host tissue response and reduce the need for revision surgery, thereby replacing conventional synthetic meshes for hernia repair.College of Engineering Undergraduate Research Optio

Insight into SUCNR1 (GPR91) structure and function

SUCNR1 (or GPR91) belongs to the family of G protein-coupled receptors (GPCR), which represents the largest group of membrane proteins in human genome. The majority of marketed drugs targets GPCRs, directly or indirectly. SUCNR1 has been classified as an orphan receptor until a landmark study paired it with succinate, a citric acid cycle intermediate. According to the current paradigm, succinate triggers SUCNR1 signaling pathways to indicate local stress that may affect cellular metabolism. SUCNR1 implication has been well documented in renin-induced hypertension, ischemia/reperfusion injury, inflammation and immune response, platelet aggregation and retinal angiogenesis. In addition, the SUCNR1-induced increase of blood pressure may contribute to diabetic nephropathy or cardiac hypertrophy. The understanding of SUCNR1 activation, signaling pathways and functions remains largely elusive, which calls for deeper investigations. SUCNR1 shows a high potential as an innovative drug target and is probably an important regulator of basic physiology. In order to achieve the full characterization of this receptor,more specific pharmacological tools such as small-molecules modulators will represent an important asset. In this review, we describe the structural features of SUCNR1, its current ligands and putative binding pocket. We give an exhaustive overview of the known and hypothetical signaling partners of the receptor in different in vitro and in vivo systems. The link between SUCNR1 intracellular pathways and its pathophysiological roles are also extensively discussed

Targeting chloride transport in autosomal dominant polycystic kidney disease.

Autosomal dominant polycystic kidney disease (ADPKD) is the most frequent inherited kidney disease. Transepithelial fluid secretion is one of the key factors of cystogenesis in ADPKD. Multiple studies have suggested that fluid secretion across ADPKD cyst-lining cells is driven by the secretion of chloride, essentially mediated by the CFTR channel and stimulated by increased intracellular levels of 3',5'-cyclic adenosine monophosphate. This review focuses on the pathophysiology of fluid secretion in ADPKD based on the pioneering studies of Jared Grantham and colleagues, and on the follow-up investigations from the molecular level to the potential applications in ADPKD patients. Altogether, the studies of fluid and chloride transport in ADPKD paved the way for innovative therapeutic targets to prevent cyst volume expansion and thus, kidney disease progression.Peer reviewe

Decreased renal accumulation of aminoglycoside reflects defective receptor-mediated endocytosis in cystic fibrosis and Dent's disease

The clinical use of aminoglycoside (AG) antibiotics is limited by their renal toxicity, which is caused by drug accumulation in proximal tubule (PT) cells. Clinical studies reported that renal clearance of AG is enhanced in cystic fibrosis (CF) patients, which might reflect the role of CFTR in PT cell endocytosis. In order to assess the role of chloride transporters on the renal handling of AG, we investigated gentamicin uptake and renal accumulation in mice lacking functional CFTR (Cftr ∆F/∆F) or knock-out for the Cl−/H+ exchanger ClC-5 (Clcn5 Y/− ). The latter represent a paradigm of PT dysfunction and defective receptor-mediated endocytosis. As compared with controls, Cftr ∆F/∆F and Clcn5 Y/− mice showed a 15% to 85% decrease in gentamicin accumulation in the kidney, respectively, in absence of renal failure. Studies on primary cultures of Cftr ∆F/∆F and Clcn5 Y/− mouse PT cells confirmed the reduction in gentamicin uptake, although colocalization with endosomes and lysosomes was maintained. Quantification of endocytosis in PT cells revealed that gentamicin, similar to albumin, preferentially binds to megalin. The functional loss of ClC-5 or CFTR was reflected by a decrease of the endocytic uptake of gentamicin, with a more pronounced effect in cells lacking ClC-5. These results support the concept that CFTR, as well as ClC-5, plays a relevant role in PT cell endocytosis. They also demonstrate that the functional loss of these two chloride transporters is associated with impaired uptake of AG in PT cells, reflected by a decreased renal accumulation of the dru

Impact of timing administration of mesenchymal stromal cells on serum creatinine following renal ischemia/ reperfusion in rats

peer reviewedExperimental models of renal ischemia/reperfusion (I/R) have suggested protective effects of mesenchymal stromal cells (MSC) therapy. Still, param- eters of MSC injection, including volume, route and timing of cell administration, remain largely debated. Particularly, MSC infusion in mouse has been shown to be beneficial “a priori” but deleterious “a posteriori” of renal I/R injury. In order to further investigate the influence of the timing of MSC administration, we used 10-week-old Lewis rats categorized in 4 groups. Groups 1 (MSC D-7, n = 10) and 2 (MSC D + 1, n = 7) received caudal i.v. injection of MSC (1.5 9 106 in 1 ml of saline) 7 days before or 1 day after renal I/R, respectively. Control groups 3 (saline D-7, n = 6) and 4 (saline D + 1, n = 6) received equal volume of saline at similar time points. Left renal ischemia (by clamping of the renal pedicle) lasted 45 min. Right nephrectomy was simultaneously performed. Blood sample was collected from inferior vena cava at 48 h post reperfusion. MSC phenotype was confirmed by FACS analysis. In groups 1 and 3, serum creatinine (SCr) reached 1.4 ` 0.7 versus 2.4 ` 0.8 mg/dl, respectively (p < 0.05). In groups 2 and 4, SCr was 4.9 ` 0.7 versus 3.3 ` 0.9 mg/dl, respectively (p < 0.001). Furthermore, SCr levels were statistically worse when MSC were administered after renal I/R in comparison to a priori infusion (p < 0.0001). In conclusion, MSC administration 7 days prior to renal I/R attenuates kidney injury in comparison to (i) saline infusion or (ii) MSC infusion 1 day after renal I/R. Conversely, on the basis of SCr levels, MSC therapy performed after renal I/R worsens kidney injury in rats

Diagnosis of cyst infection in patients with autosomal dominant polycystic kidney disease: attributes and limitations of the current modalities.

Cyst infection is a diagnostic challenge in patients with autosomal dominant polycystic kidney disease (ADPKD) because of the lack of specific manifestations and limitations of conventional imaging procedures. Still, recent clinical observations and series have highlighted common criteria for this condition. Cyst infection is diagnosed if confirmed by cyst fluid analysis showing bacteria and neutrophils, and as a probable diagnosis if all four of the following criteria are concomitantly met: temperature of >38 degrees C for >3 days, loin or liver tenderness, C-reactive protein plasma level of >5 mg/dL and no evidence for intracystic bleeding on computed tomography (CT). In addition, the elevation of serum carbohydrate antigen 19-9 (CA19-9) has been proposed as a biomarker for hepatic cyst infection. Positron-emission tomography after intravenous injection of 18-fluorodeoxyglucose, combined with CT, proved superior to radiological imaging techniques for the identification and localization of kidney and liver pyocyst. This review summarizes the attributes and limitations of these recent clinical, biological and imaging advances in the diagnosis of cyst infection in patients with ADPKD

Positron-emission computed tomography in cyst infection diagnosis in patients with autosomal dominant polycystic kidney disease.

BACKGROUND: Cyst infection remains a challenging issue in patients with autosomal dominant polycystic kidney disease (ADPKD). In most patients, conventional imaging techniques are inconclusive. Isolated observations suggest that (18)fluorodeoxyglucose ((1)(8)FDG) positron-emission computed tomography (PET/CT) might help detect cyst infection in ADPKD patients. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: Comparative assessment of administrative databases from January 2005 to December 2009 identified 27 PET/CT scans performed in 24 ADPKD patients for suspicion of abdominal infection. Cyst infection was definite if confirmed by cyst fluid analysis. Cyst infection was probable if all four of the following criteria were met: temperature of >38 degrees C for >3 days, loin or liver tenderness, C-reactive protein plasma level of >5 mg/dl, and no CT evidence for intracystic bleeding. Episodes with only two or three criteria were grouped as "fever of unknown origin". RESULTS: Thirteen infectious events in 11 patients met all criteria for kidney (n = 3) or liver (n = 10) cyst infection. CT was contributive in only one patient, whereas PET/CT proved cyst infection in 11 patients (84.6%). In addition, 14 episodes of "fever of unknown origin" in 13 patients were recorded. PET/CT identified the source of infection in nine patients (64.3%), including 2 renal cyst infections. Conversely, PET/CT showed no abnormal (1)(8)FDG uptake in 5 patients, including 2 intracystic bleeding. The median delay between the onset of symptoms and PET/CT procedure was 9 days. CONCLUSIONS: This retrospective series underscores the usefulness of PET/CT to confirm and locate cyst infection and identify alternative sources of abdominal infection in ADPKD patients