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Michael J Francis

Publications and source records attributed to Michael J Francis.

5 recordsLinked to original sources

The strictured anastomosis: successful treatment by corticosteroid injections--report of three cases and review of the literature.

Clinically significant anastomotic strictures usually only occur with very low colorectal anastomoses below the level of the peritoneal reflection. The reported rate averages 8 percent and has been attributed to tissue ischemia, localized sepsis, anastomotic leak, proximal fecal diversion, radiation injury, inflammatory bowel disease, and recurrent rectal cancer. Most patients will have symptoms of obstipation, frequent small bowel movements, and bloating. Symptomatic strictures are often approached by dilation (balloon or Hegar) or less often repeat resection. Many of these patients have anastomoses that are too low to consider repeat resection. Strictureplasty with linear stapling devices, stricture resection by use of the circular stapling device, and repeat dilations have all been described. Steroid injections into the stricture have been described in strictured esophagogastric anastomoses but have not been commonly used for strictured coloproctostomies. We describe three cases of coloanal stricture following resections that were complicated by postoperative pelvic abcesses, anastomatic leaks, and pelvic fibrosis. Two cases had undergone low coloanal anastomosis that was protected by a loop ileostomy and developed as significant stricture in the early postoperative period. The third case was managed without a protective loop ileostomy. These were initially managed by repeated dilation of the anastomosis. Each episode was followed by rapid recurrence of the stricture. All patients underwent subsequent dilation with injection of 40 mg of triamcinolone acetate (divided dose in four quadrants) into the stricture and subsequent complete resolution of the stricture. Those patients with loop ileostomies had them taken down and all have been followed for up to 12 months without clinical or endoscopic evidence of recurrent stricture.

Abscess↗

Genomic studies of gene expression: regulation of the Wilson disease gene.

Bacterial artificial chromosomes (BACs) have many advantages over other large-insert cloning vectors and have been used for a variety of genetic applications, including the final contigs of the human genome. We describe the utilization of a BAC construct to study gene regulation in a tissue culture-based system, using a 170-kb clone containing the entire Wilson disease (WND) locus as a model. A second BAC construct that lacked a putative negatively regulating promoter sequence was created. A nonviral method of gene delivery was applied to transfect three human cell lines stably with each construct. Our results show correct WND gene expression from the recombinant locus and quantification revealed significantly increased expression from the clone lacking the negative regulator. Comparison with conventional methods confirms the reliability of the genomic approach for thorough examination of gene expression. This experimental system illustrates the potential of BAC clones in genomic gene expression studies, new gene therapy strategies, and validation of potential molecular targets for drug discovery.

Adenosine Triphosphatases↗

CypHer 5: a generic approach for measuring the activation and trafficking of G protein-coupled receptors in live cells.

GPCRs are one of the most popular classes of therapeutic drug targets. It is therefore important to design specific assay formats to readily identify ligands at these receptors. CypHer 5 technology utilizes the general ability of GPCRs to be internalized into the endosomal pathway of a cell in response to agonist ligands. The CypHer 5 dye is fluorescent in acidic environments, but nonfluorescent at neutral pH. When CypHer 5 is bound to a receptor on the extracellular surface of the cell, it is essentially nonfluorescent. On internalization into a cell, it displays a significant increase in fluorescence. Here we demonstrate the detection of agonist activation of two GPCRs in stably transfected live cells using CypHer 5 technology. The G(q)-coupled TRHR-1 and the G(s)-coupled beta(2)-adrenoceptor were both N-terminally tagged with VSV-G. Following addition of CypHer 5-labeled anti-VSV-G antibodies to HEK 293 cells stably expressing the beta(2)-adrenoceptor or CHO-K1 cells stably expressing the TRHR-1, the cells were treated with agonists and then imaged on Amersham Biosciences' IN Cell Analyzer 3000. Data were quantified using a granularity analysis module. Concentration-response curves were obtained with signal-to-background ratios of 7:1 for both receptors. An EC(50) of 0.52 nM was observed on TRH stimulation of the TRHR-1, and an EC(50) of 30 nM was obtained on isoprenaline stimulation of the beta(2)-adrenoceptor. These results demonstrated that the CypHer technology was capable of measuring high-potency agonist responses. The beta(2)-adrenoceptor antagonist, alprenolol, competed for isoprenaline with an IC(50) of 30 nM, indicating that a high-potency antagonist inhibition curve could also be observed using CypHer. CypHer 5 provides a generic tool to measure GPCR activation in a live cell, homogeneous assay format, and may be equally suitable for detecting activation of other classes of cell surface receptors.

Animals↗

Novel membrane traffic steps regulate the exocytosis of the Menkes disease ATPase.

The Menkes disease protein (ATP7A or MNK) is a P-type transmembrane ATPase that regulates translocation of cytosolic copper ions across intracellular membranes of compartments along the secretory pathway. In this study, we show that endogenous MNK in cultured cell lines is localized to the distal Golgi apparatus and translocates to the plasma membrane in response to exogenous copper ions. This transport event is not blocked by expression of a dominant-negative mutant protein kinase D, an enzyme implicated in regulating constitutive trafficking from the trans-Golgi network (TGN) to the plasma membrane, whereas constitutive transport of CD4 is inhibited. In contrast, protein kinase A inhibitors block copper-stimulated MNK delivery to the plasma membrane. Expression of constitutively active Rho GTPases such as Cdc42, Rac1 and RhoA reveals a requirement for Cdc42 in the trafficking of MNK, to the cell surface. Furthermore, overexpression of WASp inhibits anterograde transport of MNK, further supporting regulation by the Cdc42 GTPase. These findings define a novel step in TGN-to-plasma membrane traffic required to export MNK to the cell surface.

Actins↗