ABSTRACT
Intercellular communication may be regulated by the differential expression of subunit gap junction proteins (connexins) which form channels with differing gating and permeability properties. Endothelial cells express three different connexins (connexin37, connexin40, and connexin43) in vivo. To study the differential regulation of expression and synthesis of connexin37 and connexin43, we used cultured bovine aortic endothelial cells which contain these two connexins in vitro. RNA blots demonstrated discordant expression of these two connexins during growth to confluency. RNA blots and immunoblots showed that levels of these connexins were modulated by treatment of cultures with transforming growth factor-ss1. To examine the potential ability of these connexins to form heteromeric channels (containing different connexins within the same hemi-channel), we stably transfected connexin43-containing normal rat kidney (NRK) cells with connexin37 or connexin40. In the transfected cells, both connexin proteins were abundantly produced and localized in identical distributions as detected by immunofluorescence. Double whole-cell patch-clamp studies showed that co-expressing cells exhibited unitary channel conductances and gating characteristics that could not be explained by hemi-channels formed of either connexin alone. These observations suggest that these connexins can readily mix with connexin43 to form heteromeric channels and that the intercellular communication between cells is determined not only by the properties of individual connexins, but also by the interactions of those connexins to form heteromeric channels with novel properties. Furthermore, modulation of levels of the co-expressed connexins during cell proliferation or by cytokines may alter the relative abundance of different heteromeric combinations.
Subject(s)
Cell Communication/physiology , Connexin 43/physiology , Connexins/physiology , Endothelium, Vascular/physiology , Animals , Aorta , Cattle , Cells, Cultured , Immunoblotting , Patch-Clamp Techniques , RNA, Messenger/analysis , Rats , Gap Junction alpha-5 Protein , Gap Junction alpha-4 ProteinABSTRACT
Surgery is the only treatment that can cure most patients with colorectal cancer. Radiation therapy (pre or postoperative) has been shown to improve results by decreasing local recurrence and improving survival. Our aim was to analyze whether postoperative radiation influenced long-term functional outcomes and the probability of stricture of anastomosis in patients who underwent coloanal anastomosis for rectal cancer. Methods: The records of 84 patients with coloanal anastomosis for rectal cancer were studied between 1980 and 1996. There were 82 males and 28 females. Mean age was 57.8 years (range 24 to 78 years). Mean distal resection margin was 2.6 cm (range 0 to 14cm). Twenty-three patients received postoperative irradiation therapy. Patients who received chemotherapy were not included in the study. Results were analysed by examination , telephone or questionnaire. Mean follow-up was 3.8 years (range 0 to 13 years). Results: There was no operative mortality. Functional variables were much better in non-irradiated patients. The irradiated group had more number of stools/day (p>0.05), more number of stools/ night (p>0.05), more incontinence/day (p<0.05) and more incontinence/night (p<0.05). Irradiated patients also wore more pads (p<0.05) than non-irradiated patients. The probability of remaining free of stricture at 5 years was slightly better in non-irradiated (72 percent) than in irradiated patients (65 percent, p>0.05). Conclusion: Postoperative irradiation after colo-anal anastomosis for rectal cancer is safe, but may increase the risk of stricture of anastomosis and does affect functional results adversely
Subject(s)
Humans , Male , Female , Adult , Middle Aged , Colorectal Neoplasms/radiotherapy , Anastomosis, Surgical , Colorectal Neoplasms/surgery , Postoperative Period , Treatment OutcomeABSTRACT
Surgery is the only treatment that can cure most patients with colorectal cancer. Radiation therapy (pre or postoperative) has been shown to improve results by decreasing local recurrence and improving survival. Our aim was to analyze whether postoperative radiation influenced long-term functional outcomes and the probability of stricture of anastomosis in patients who underwent coloanal anastomosis for rectal cancer. Methods: The records of 84 patients with coloanal anastomosis for rectal cancer were studied between 1980 and 1996. There were 82 males and 28 females. Mean age was 57.8 years (range 24 to 78 years). Mean distal resection margin was 2.6 cm (range 0 to 14cm). Twenty-three patients received postoperative irradiation therapy. Patients who received chemotherapy were not included in the study. Results were analysed by examination , telephone or questionnaire. Mean follow-up was 3.8 years (range 0 to 13 years). Results: There was no operative mortality. Functional variables were much better in non-irradiated patients. The irradiated group had more number of stools/day (p>0.05), more number of stools/ night (p>0.05), more incontinence/day (p 0.05) and more incontinence/night (p 0.05). Irradiated patients also wore more pads (p 0.05) than non-irradiated patients. The probability of remaining free of stricture at 5 years was slightly better in non-irradiated (72 percent) than in irradiated patients (65 percent, p>0.05). Conclusion: Postoperative irradiation after colo-anal anastomosis for rectal cancer is safe, but may increase the risk of stricture of anastomosis and does affect functional results adversely.