Biomedical subjects

William Staines

Publications and source records attributed to William Staines.

4 recordsLinked to original sources

PubMed2006

The use of rapid assessment of enteric ICC and neuronal morphology may improve patient management in pediatric surgery: a new clinical pathological protocol.

Alterations in interstitial cells of Cajal (ICC) distribution and density may seriously influence gut motility. We and others have documented a disturbance of ICC and neurons in Hirschsprung's disease (HD), intestinal ischemia, and inflammation. The ability to remove intestine with permanent dysmotility improves significantly the prognosis. This may be important in the developing intestine especially in HD. More complete pathological information increases the accuracy of surgical decisions. Therefore we sought to develop a rapid, intraoperative immunohistochemical protocol for ICC and neurons in surgical specimens for routine diagnostic and therapeutic assessment of pediatric patients. To date, cKit is the only reliable immunohistochemistry for ICC identification. There are multiple antibodies in use for neuronal identification. A comparison of fixation methods and immunostaining using cKit and multiple intestinal neuronal antibodies was done. Fresh segments of surgically resected intestine were sectioned and stained using antibodies for ICC cell identification (anti-cKit) and for neuronal characterization. By carefully changing tissue fixation methods, different neuronal antibodies were tested to determine an optimal rapid protocol. Each suggested protocol was tested on normal and pathological intestinal tissue and compared to the previous overnight immunostaining of the same tissue. A new rapid tissue fixation and immunostaining protocol using cKit for ICC identification and NF 68 was developed. By employing this protocol, we could obtain ICC and neuro-immunohistochemistry in unfixed frozen sections within 1 h with tissue vibration to diminish the time for immunostaining. Without vibration the protocol takes 3 h. ICC and enteric neuronal changes could be readily observed and the quality of staining was comparable to standard immunohistochemistry. Each gut pathology displayed characteristic changes in ICC and neuronal density/distribution in the affected bowel. The time-scale of the 1-h immunoprocessing is still longer than the standard clinical pathological "quick" sections using H&E staining; however, the protocol duration is within the surgery timescale. Standard H&E stain used in combination with our rapid neuronal and ICC immunohistochemistry protocol enables a fast, comprehensive, and accurate assessment of the pathophysiology of signaling networks controlling gut motility while the patient is still in the operating room. We propose that the addition of this simple and rapid immunohistochemical assessment in the pathologist evaluation of surgical specimens would result in a more complete characterization for diagnosis and prognosis of the pediatric patient. Specifically, we propose that this test will differentiate good versus poor prognosis HD patients based on their neuron/ICC ratio and present a rapid, standardized method for use in general pathology.

Colon↗

PubMed2005

Molecular mechanisms involved in the adenosine A and A receptor-induced neuronal differentiation in neuroblastoma cells and striatal primary cultures.

Adenosine A1 receptors (A1Rs) and adenosine A(2A) receptors (A(2A)Rs) are the major mediators of the neuromodulatory actions of adenosine in the brain. In the striatum A1Rs and A(2A)Rs are mainly co-localized in the GABAergic striatopallidal neurons. In this paper we show that agonist-induced stimulation of A1Rs and A(2A)Rs induces neurite outgrowth processes in the human neuroblastoma cell line SH-SY5Y and also in primary cultures of striatal neuronal precursor cells. The kinetics of adenosine-mediated neuritogenesis was faster than that triggered by retinoic acid. The triggering of the expression of TrkB neurotrophin receptor and the increase of cell number in the G1 phase by the activation of adenosine receptors suggest that adenosine may participate in early steps of neuronal differentiation. Furthermore, protein kinase C (PKC) and extracellular regulated kinase-1/2 (ERK-1/2) are involved in the A1R- and A(2A)R-mediated effects. Inhibition of protein kinase A (PKA) activity results in a total inhibition of neurite outgrowth induced by A(2A)R agonists but not by A1R agonists. PKA activation is therefore necessary for A(2A)R-mediated neuritogenesis. Co-stimulation does not lead to synergistic effects thus indicating that the neuritogenic effects of adenosine are mediated by either A1 or A(2A) receptors depending upon the concentration of the nucleoside. These results are relevant to understand the mechanisms by which adenosine receptors modulate neuronal differentiation and open new perspectives for considering the use of adenosine agonists as therapeutic agents in diseases requiring neuronal repair.

Adenosine↗

PubMed2005

Adenosine A2A and dopamine D2 heteromeric receptor complexes and their function.

The existence of A2A-D2 heteromeric complexes is based on coimmunoprecipitation studies and on fluorescence resonance energy transfer and bioluminescence resonance energy transfer analyses. It has now become possible to show that A2A and D2 receptors also coimmunoprecipitate in striatal tissue, giving evidence for the existence of A2A-D2 heteromeric receptor complexes also in rat striatal tissue. The analysis gives evidence that these heteromers are constitutive, as they are observed in the absence of A2A and D2 agonists. The A2A-D2 heteromers could either be A2A-D2 heterodimers and/or higher-order A2A -D2 hetero-oligomers. In striatal neurons there are probably A2A-D2 heteromeric complexes, together with A2A-D2 homomeric complexes in the neuronal surface membrane. Their stoichiometry in various microdomains will have a major role in determining A2A and D2 signaling in the striatopallidal GABA neurons. Through the use of D2/D1 chimeras, evidence has been obtained that the fifth transmembrane (TM) domain and/or the I3 of the D2 receptor are part of the A2A-D2 receptor interface, where electrostatic epitope-epitope interactions involving the N-terminal part of I3 of the D2 receptor (arginine-rich epitope) play a major role, interacting with the carboxyl terminus of the A2A receptor. Computerized modeling of A2A-D2 heteromers are in line with these findings. It seems likely that A2A receptor-induced reduction of D2 receptor recognition, G protein coupling, and signaling, as well as the existence of A2A-D2 co-trafficking, are the consequence of the existence of an A2A-D2 receptor heteromer. The relevance of A2A-D2 heteromeric receptor complexes for Parkinson's disease and schizophrenia is emphasized as well as for the treatment of these diseases. Finally, recent evidence for the existence of antagonistic A2A-D3 heteromeric receptor complexes in cotransfected cell lines has been summarized.

Animals↗

PubMed2002

Expression of the Ste20-like kinase SLK during embryonic development and in the murine adult central nervous system.

Cell growth and terminal differentiation are controlled by complex signaling cascades that regulate the expression of specific subsets of genes controlling cell fate and morphogenic processes. We have recently cloned and characterized a novel Ste20-like kinase termed SLK (Sabourin et al., Mol. Cel. Biol. 20 (2000) 684). However, the specific function of SLK is poorly understood. To gain further insights into the role of SLK we have characterized its activity, expression and distribution in the CNS during embryonic development and in the adult brain. Although SLK is expressed ubiquitously in adult tissues, our results show that it is expressed preferentially in neuronal lineages during development. We find that SLK is preferentially expressed in the neurons and neuroepithelium of the developing embryo and can be detected at 10.5 and 12.5 days post-coitum (dpc) in the forebrain, midbrain and hindbrain of the developing CNS. At later stages (14.5 dpc), SLK is expressed in the hypothalamus region, all layers of the neural tube, dorsal root ganglion and in the proliferating ependymal layers. Surprisingly, following middle cerebral artery occlusion, SLK expressing neuronal cells are lost and SLK is localized to phagocytic macrophages/microglia. These results suggest a functional role for SLK in early neuronal development as well as in the adult CNS.

Animals↗