The cystic fibrosis transmembrane conductance regulator (CFTR) is a chloride channel that is regulated by phosphorylation of the R domain and ATP hydrolysis at two nucleotide-binding domains (NBDs). It is controversial whether CFTR conducts ATP or whether CFTR might be closely associated with a separate ATP conductance. To characterize ATP channels associated with CFTR, we analyzed Cl- and ATP single channel-currents in excised inside-out membrane patches from MDCK epithelial cells transiently expressing CFTR. With 100 mM ATP in the pipette and 140 mM Cl- in the bath, ATP channels were associated with CFTR Cl- channels in two-thirds of patches that included CFTR. CFTR Cl- channels and CFTR-associated ATP channels had slope conductances of 7.4 pS and 5.2 pS, respectively, and had distinct reversal potentials and sensitivities to channel blockers. CFTR-associated ATP channels exhibited slow gating kinetics that depended on the presence of protein kinase A and cytoplasmic ATP, similar to CFTR Cl- channels. Gating kinetics of the ATP channels as well as the CFTR Cl- channels were similarly affected by non-hydrolyzable ATP analogues and mutations in the CFTR R domain and NBDs. Our results indicate that phosphorylation- and nucleotide-hydrolysis-dependent gating of CFTR is directly involved in gating of an associated ATP channel. However, the permeation pathways for Cl- and ATP are distinct and the ATP conduction pathway is not obligatorily associated with the expression of CFTR.
β-catenin forms complexes with Tcf and Lef-1 and functions as a transcriptional activator in the Wnt signalling pathway. Although recent investigations have been focused on the role of the adenomatous polyposis coli (APC)/ β-catenin/Tcf pathway in human tumorigenesis, there have been very few reports on mutations of the β-catenin gene in a variety of tumour types. Using PCR and single-strand conformational polymorphism analysis, we examined 93 lung, 9 breast, 6 kidney, 19 cervical and 7 ovarian carcinoma cell lines for mutations in exon 3 of the β-catenin gene. In addition, we tested these same samples for mutations in the NH 2 -terminal regulatory region of the γ-catenin gene. Mutational analysis for the entire coding region of β-catenin cDNA was also undertaken in 20 lung, 9 breast, 5 kidney and 6 cervical carcinoma cell lines. Deletion of most β-catenin coding exons was confirmed in line NCI-H28 (lung mesothelioma) and a silent mutation at codon 214 in exon 5 was found in HeLa (cervical adenocarcinoma). A missense mutation at codon 19 and a silent mutation at codon 28 in the NH 2 -terminal regulatory region of the γ-catenin gene were found in H1726 (squamous cell lung carcinoma) and H1048 (small cell lung carcinoma), respectively. Neither deletions nor mutations of these genes were detected in the other cell lines examined. These results suggest that β- and γ-catenins are infrequent mutational targets during development of human lung, breast, kidney, cervical and ovarian carcinomas. © 2001 Cancer Research Campaign http://www.bjcancer.com
The recent discovery of mammalian bitter, sweet, and umami taste receptors indicates how the different taste qualities are encoded at the periphery. However, taste representations in the brain remain elusive. We used a genetic approach to visualize the neuronal circuitries of bitter and sweet tastes in mice to gain insight into how taste recognition is accomplished in the brain. By selectively expressing a transsynaptic tracer in either bitter- or sweet and/or umami-responsive taste receptor cells, and by comparing the locations of the tracer-labeled neurons in the brain, our data revealed the potential neuronal bases that underlie discrimination of bitter versus sweet.
Of the five types, swelled-front-type, bow-shaped-type, and projecting-type fractures had a poor prognosis with late collapse and often showing a vacuum cleft. On the other hand, concave-type and dented-type fractures had a good prognosis and almost achieved fusion. Clinical results of 28 patients with vacuum clefts were fair at the final follow-up. Nineteen patients had little back pain, and nine patients experienced moderate back pain. Regarding the activities of daily living, four patients had difficulty walking.
To determine the impact of transplantation-associated injury on the clearance mechanisms of pulmonary edema, we created a canine single lung transplant model. After 3 hours of preservation and 4 hours of reperfusion, right native lungs and left transplanted lungs were used to measure alveolar liquid clearance (ALC) in ex vivo liquid-filled lung preparations. We also examined the role of the pulmonary circulation in edema clearance in in vivo liquid-filled lungs between 4 and 8 hours of reperfusion. To study molecular modifications in ALC, we also measured expression levels of the epithelial sodium channel (ENaC) and sodium-potassium-adenosine triphosphatase (ATPase). We found that ALC was significantly lower in transplanted than in right native lungs ex vivo (p < 0.05) and that transplanted lungs did not respond to the beta-adrenergic agonist terbutaline. Our in vivo study confirmed the ex vivo results. Molecular analyses revealed that ENaC messenger RNA but not sodium-potassium-ATPase was significantly decreased in transplanted lungs (p < 0.01). Furthermore, there was a significant decrease in ENaC protein expression. Therefore, we conclude that the current investigation indicates that the lung injury caused by lung preservation and transplantation significantly reduces the edema clearance ability of transplanted lungs.
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