A validation study of a dedicated software for an automated in vivo dosimetry control in radiotherapy.

In vivo dosimetry (IVD) is the last step of a radiotherapy quality control program aimed to ensure that the dose delivered is in agreement with that prescribed. IVD procedures based on single detectors are time-consuming and impossible to use for the modern radiotherapy techniques, based on static or kinetic beams (modulated in intensity fluence); this means that more efficient and practical methods are highly recommended. The practical method SOFTDISO, based on the use of electronic portal image device (EPID), provides two tests (i) the R ratio between the reconstructed and the planned isocenter doses to verify an agreement within 5% and (ii) the γ-analysis of the EPID images, to verify γ% ≥ 90% and γmean ≤ 0.4. This paper reports the results of 11,357 IVD tests carried out for 823 patients treated by three-dimensional conformal radiation therapy and volumetric modulated arc therapy techniques. In particular, the dose disagreements are reported distinguishing two kinds of causes, those of (i) class 1 that includes the errors due to inadequate quality controls and (ii) the class 2, due to patient morphological changes. About the tests out of tolerance, 6% were by VMAT and 21% by 3DCRT, but taking into account the only class 1 of errors, i.e., removing the causes of class 2, only 7% of patients examined presented at least one of the three mean indexes out of tolerance. The workload for IVD on 9 patients/day per linac is about 52 min/day but recently, a new automated SOFTDISO version has been implemented to reduce the time to about 34 min/day.

Quasi real time in vivo dosimetry for VMAT.

PURPOSE: Results about the feasibility of a method for quasi real time in vivo dosimetry (IVD) at the isocenter point for volumetric modulated arc therapy (VMAT) are here reported. The method is based on correlations between the EPID signal and the dose on the beam central axis. Moreover, the γ-analysis of EPID images was adopted to verify off-axis reproducibility of fractionated plan delivery. METHODS: An algorithm to reconstruct in vivo the isocenter dose, D(iso), for RapidArc treatments has been developed. 20 VMAT plans, optimized with two opposite arcs, for prostate, pancreas, and head treatments have been delivered by a Varian linac both to a conic PMMA phantom with elliptical section and to patients. The ratios R between reconstructed D(iso) and the planned doses were determined for phantom and patient irradiations adopting an acceptance criterion of ±5%. In total, 40 phantom checks and 400 patient checks were analyzed. Moreover, 3% and 3 mm criteria were adopted for portal image γ-analysis to assess patient irradiation reproducibility. RESULTS: The average ratio R, between reconstructed and planned doses for the PMMA phantom irradiations was equal to 1.007 ± 0.024. When the IVD method was applied to the 20 patients, the average R ratio was equal to 1.003 ± 0.017 and 96% of the tests were within the acceptance criteria. The portal image γ-analysis supplied 88% of the tests within the pass rates γ(mean) ≤ 0.4 and P(γ<1) ≥ 98%. All the warnings were understood comparing the CT and the cone beam CT images and in one case a patient's setup error was detected and corrected for the successive fractions. CONCLUSIONS: This preliminary experience suggests that the method is able to detect dosimetric errors in quasi real time at the end of the therapy session. The authors intend to extend this procedure to other pathologies with the integration of in-room imaging verification by cone beam CT.

An in-vivo dosimetry procedure for Elekta step and shoot IMRT.

PURPOSE: The aim of this work was to extend an in-vivo dosimetry (IVD) method, previously developed by the authors for 3D-conformal radiotherapy, to step and shoot IMRT treatments for pelvic tumors delivered by Elekta linacs. MATERIALS AND METHODS: The algorithm is based on correlation functions to convert EPID transit signals into in-vivo dose values at the isocenter point, Diso. The EPID images were obtained by the so-called "IMRT Dosimetric Weighting" mode as a superposition of many segment fields. This way each integral dosimetric image could be acquired in about 10 s after the end of beam delivery and could be processed while delivering the successive IMRT beams. A specific algorithm for Diso reconstruction especially featured for step and shoot IMRT was implemented using a fluence inhomogeneity index, FI, introduced to describe the degree of beam modulation with respect to open beams. A γ-analysis of 2D-EPID images obtained day to day, resulted rapid enough to verify the plan delivery reproducibility. RESULTS: Fifty clinical IMRT beams, planned for patients undergoing radiotherapy of pelvic tumors, were used to irradiate a homogeneous phantom. For each beam the agreement between the reconstructed dose, Diso, and the TPS computed dose, Diso,TPS, was well within 5%, while the mean ratio R = Diso/Diso,TPS resulted for 250 tests equal to 1.006 ± 0.036. The same beams were checked in vivo, i.e. during patient treatment delivery, obtaining 500 tests whose average R ratio resulted equal to 1.011 ± 0.042. The γ-analysis of the EPID images with 5% 3 mm criteria supplied 85% of the tests with pass rates γ(mean) ≤ 0.5 and P(γ<1) ≥ 90%.

Gamma rays induce a p53-independent mitochondrial biogenesis that is counter-regulated by HIF1α.

Mitochondrial biogenesis is an orchestrated process that presides to the regulation of the organelles homeostasis within a cell. We show that γ-rays, at doses commonly used in the radiation therapy for cancer treatment, induce an increase in mitochondrial mass and function, in response to a genotoxic stress that pushes cells into senescence, in the presence of a functional p53. Although the main effector of the response to γ-rays is the p53-p21 axis, we demonstrated that mitochondrial biogenesis is only indirectly regulated by p53, whose activation triggers a murine double minute 2 (MDM2)-mediated hypoxia-inducible factor 1α (HIF1α) degradation, leading to the release of peroxisome-proliferator activated receptor gamma co-activator 1ß inhibition by HIF1α, thus promoting mitochondrial biogenesis. Mimicking hypoxia by HIF1α stabilization, in fact, blunts the mitochondrial response to γ-rays as well as the induction of p21-mediated cell senescence, indicating prevalence of the hypoxic over the genotoxic response. Finally, we also show in vivo that post-radiotherapy mitochondrial DNA copy number increase well correlates with lack of HIF1α increase in the tissue, concluding this may be a useful molecular tool to infer the trigger of a hypoxic response during radiotherapy, which may lead to failure of activation of cell senescence.

Real-time dose reconstruction for wedged photon beams: a generalized procedure.

A practical and accurate generalized procedure to reconstruct the isocenter dose D(iso) for 3D conformal radiotherapy (3DCRT) has been developed for X-ray open beams supplied by linacs of different manufacturers and equipped with aSi electronic portal imaging devices (aSi EPIDs). This paper reports an extension of the method, to be applied at the wedged X-ray beams characterized by the wedge attenuation factor W(AF). Using water-equivalent solid phantoms (SPs) of different thicknesses, w, and photon square fields of sizes, L, the generalized midplane doses D(0)(W(AF), w/2,L) and generalized transit signals s(t)(0)(W(AF),w,L) by 38 beams of six different linacs were determined. The generalized data were fitted by surface equations and used together with the information of the 'record & verify' network of the centers. In this manner, for every beam, the D(iso) reconstruction was obtained in about 25 seconds after the treatment. To test the in vivo dosimetric procedure, six pelvic treatments that used conformed wedged beams were carried out with three linacs of different manufacturers. For every beam, the comparison between the reconstructed D(iso) and the D(iso,TPS) computed by the TPS, resulted in an acceptable tolerance level of ±5%, estimated for this kind of treatment. Generally the in vivo dosimetry methods that use EPIDs require: (i) a special effort for the dosimetric commissioning with SPs of different thicknesses, and (ii) extra time for the analysis of the EPID signals. The proposed procedure simplifies the commissioning step and supplies for Varian, Elekta, and Siemens linacs equipped with the aSi EPIDs a quasi-real time in vivo dosimetry for open and wedged 3DCRT fields.

The antioxidant function of Bcl-2 preserves cytoskeletal stability of cells with defective respiratory complex I.

Human thyroid carcinoma XTC.UC1 cells harbor a homoplasmic frameshift mutation in the MT-ND1 subunit of respiratory complex I. When forced to use exclusively oxidative phosphorylation for energy production by inhibiting glycolysis, these cells triggered a caspase-independent cell death pathway, which was associated to a significant imbalance in glutathione homeostasis and a cleavage of the actin cytoskeleton. Overexpression of the anti-apoptotic Bcl-2 protein significantly increased the level of endogenous reduced glutathione, thus preventing its oxidation after the metabolic stress. Furthermore, Bcl-2 completely inhibited actin cleavage and increased cell adhesion, but was unable to improve cellular viability. Similar effects were obtained when XTC.UC1 cells were incubated with exogenous glutathione. We hence propose that Bcl-2 can safeguard cytoskeletal stability through an antioxidant function.

Large idiopathic unilateral adrenal hematoma in a young woman.

This is a case report on a young woman with a large idiopathic unilateral adrenal hematoma (AH). Only few cases of AH which were not associated with any trauma, previous surgery, coagulative or any other systemic disorders have been described. The mass was discovered by abdominal ultrasound which was performed for a recent flank pain. Magnetic resonance imaging (MRI) confirmed the presence of a 13-cm sized lesion in the right hemi-abdomen; T1 and T2 weighed imaging was compatible with subacute-to-chronic adrenal hematoma. The lesion dislocated the liver and right kidney. Positron emission tomography (PET) did not show any significant radiotracer uptake by the mass. Serum cortisol, aldosterone, renin activity and DHEA-S were normal. Urinary catecholamines and free cortisol excretion were within the normal range too. The lesion was removed by transabdominal laparoscopic adrenalectomy without any complication. The histological exam confirmed a large subacute- to-chronic organized AH. In conclusion, in the absence of known risk factors, differential diagnosis of a large AH may not be easy. The possibility of an underlying pheochromocytoma, malignant adrenal or metastatic tumor must always be considered. In our patient, computed tomography (CT) scan and MRI suggested the presence of a large subacute-to-chronic AH, and PET excluded metabolic activity of the mass. Laparoscopic adrenalectomy can be the surgical treatment of choice in organized symptomatic AH. The correct diagnosis, early recognition and treatment of complications including adrenal insufficiency may decrease patient morbidity and mortality.

Caspase-independent death of Leber's hereditary optic neuropathy cybrids is driven by energetic failure and mediated by AIF and Endonuclease G.

Leber's hereditary optic neuropathy (LHON) is associated with mitochondrial DNA point mutations affecting different subunits of complex I. By replacing glucose with galactose in the medium, cybrids harboring each of the three LHON pathogenic mutations (11778/ND4, 3460/ND1, 14484/ND6) suffered a profound ATP depletion over a few hours and underwent apoptotic cell death, which was caspase-independent. Control cybrids were unaffected. In addition to cytochrome c, apoptosis inducing factor (AIF) and endonuclease G (EndoG) were also released from the mitochondria into the cytosol in LHON cybrids, but not in control cells. Exposure of isolated nuclei to cytosolic fractions from LHON cybrids maintained in galactose medium caused nuclear fragmentation, which was strongly reduced by immuno-depletion with anti-AIF and anti-EndoG antibodies. In conclusion, the caspase-independent death of LHON cybrids incubated in galactose medium is triggered by rapid ATP depletion and mediated by AIF and EndoG.

[Minilaparoscopy and open laparoscopy: prevention of laparoscopic complications]. / Minilaparoscopie e "open-laparoscopy". Prevenzione delle complicanze laparoscopiche.

BACKGROUND: The study aimed to compare laparoscopy, open-laparoscopy and mini-laparoscopy and to correlate the results of each technique with the respective percentages of laparotomic conversion. METHODS: A total of 101 laparoscopies were performed between November 1997 and April 1999: 18.8% were diagnostic and 81.2% operative. The latter included 54 traditional laparoscopies (65.9%), 18 open-laparoscopies (21.9%) and 10 minilaparoscopies (12.2%). RESULTS: Laparotomic conversion was required in 5.5% of laparoscopies. No laparotomic conversion was necessary for the open-laparoscoples and for mini-laparoscopies. CONCLUSIONS: The possibility of resorting to open-laparoscopy and mini-laparoscopy may represent a valid tool when the patient has previously undergone laparoscopic or laparotomic surgery, with the supposition of pelvo-abdominal adherences that would increase the risk of traditional laparoscopy.

The phorbol ester PMA and cyclic AMP activate different Cl(-) and HCO3(-) fluxes in C127 cells expressing CFTR.

In mouse mammary epithelial C127 cells expressing wild-type cystic fibrosis transmembrane conductance regulator (CFTR), chloride efflux, measured with the Cl(-)-sensitive dye 6-methoxy-N-(3-sulfopropyl)quinolinium (SPQ), was stimulated by activation of protein kinase A with cyclic AMP elevating agents forskolin plus 3-isobutyl-1-methyl-xanthine (IBMX) and, to a less extent, by activation of protein kinase C with the phorbol 12-myristate 13-acetate (PMA). Conversely, bicarbonate influx, determined by intracellular alkalinization of cells incubated with the pH-sensitive dye 2',7'-bis(2-carboxyethyl)-5(6)-carboxyfluoresceintetraacetoxymethyl ester (BCECF-AM), was stimulated by cyclic AMP elevation, but not by PMA. Patch clamp analysis revealed that PMA activated a Cl(-) current with the typical biophysical characteristics of swelling-activated current and not of CFTR.

[Ureaplasma urealyticum vaginosis and premature rupture of membranes. What is its role?]. / Vaginosi da ureaplasma urealyticum e rottura prematura delle membrane. Quale ruolo?

BACKGROUND: The aim of this study was to evaluate a correlation between PROM and genital infections. METHODS: A total of 308 vaginal swabs were made in randomized study group composed by 184 pregnant women aged between 26 and 32 years with an extreme age of 19 (one) and 40 years (one). Three vaginal swabs and one cervical swab (searching for Chlamydia) were made for every patient. Sixteen patients were excluded during this study, because they decided to have their babies in other hospitals. Therefore, the patients totally included in the study were 166: 109 at the first pregnancy, 33 at the second pregnancy and 5 at the third pregnancy. No one of them had any spontaneous abortion in the past. All possible other factor which ca be considered responsible and/or inductive of premature ruptures, such as cervical incontinence, cigarette smoke and coitus were excluded. RESULTS: 280 vaginal swabs were made in this study: 134 were positive, with a global positivity percentage of 47.85%. Premature rupture of membranes (PROM) was observed in 38 cases with an incidence of 23.03%: 26 were PROM and 12 were pPROM. The extreme pPROMs occurred, respectively, at the 21st and at 34th gestational week; 29 of the 38 cases of PROM, were associated with positive cultures. The results obtained show an evident correlation between PROM and Ureaplasma urealyticum vaginosis: this fact is improved by the high incidence percentage of this mycobacter in pregnant women and also by an absolute predomination of Ureplasma urealyticum in PROM cases (72.41%). CONCLUSIONS: These data obtained confirm the importance of this microorganism in PROM genesis, according to some recent studies. It is suggested that Ureaplasma urealyticum infection can contribute to a premature start of labour.

Sphingosine-1-phosphate activates phospholipase D in human airway epithelial cells via a G protein-coupled receptor.

Sphingosine-1-phosphate (SPP) acts as a first messenger in immortalized human airway epithelial cells (CFNPE9o(-)), possibly interacting with an Edg family receptor. Expression of the SPP receptors Edg-1 and Edg-3, as well as a low level of Edg-5/H218, was detected in these cells, in agreement with their ability to specifically bind SPP. The related lipids, lysophosphatidic acid and sphingosylphosphorylcholine, were unable to displace SPP from its high affinity binding sites, suggesting that the biological responses to these different lysolipids are mediated by distinct receptors. SPP markedly inhibited forskolin-stimulated cAMP accumulation in a dose-dependent manner and caused a remarkable elevation of intracellular calcium, both effects being sensitive to pertussis toxin treatment. Most importantly, SPP stimulated phosphatidic acid formation, which was maximal after 2 min and decreased within 8-10 min. In the presence of butan-1-ol, suppression of SPP-induced phosphatidic acid formation and production of phosphatidylbutanol were found, clearly indicating activation of phospholipase D (PLD). This finding was also confirmed by analysis of the fatty acid composition of phosphatidic acid, showing an increase in the monounsaturated oleic acid only. The decrease of phosphatidic acid level after 8-10 min incubation with SPP was accompanied by a parallel increase of diacylglycerol production, which was abolished in the presence of butan-1-ol. This result indicates that activation of phospholipase D is followed by stimulation of phosphatidate phosphohydrolase activity. Phosphatidic acid formation was insensitive to protein kinase C inhibitors and almost completely inhibited by pertussis toxin treatment, suggesting that SPP activates phospholipase D via a G(i/o) protein-coupled receptor.

[Cure of female sterility. Treatment of hydrosalpinx]. / Cura della sterilità femminile. Trattamento dell'idrosalpinge.

BACKGROUND: The aim of this study was to show how a laparoscopic salpingectomy can positively modify infertile patients pregnancy rate after a diagnosis of hydrosalpinx, obtaining, through successive assisted procreation programs, a pregnancy rate equal to the pregnancy rate obtained in good conditions. METHODS: A group of 19 women under infertility treatment was evaluated: of these women, 11 were included less than three times in an assisted procreation program and 8 were included three or more times in these programs, for a total of 41 cycles of assisted reproduction: all these cycles were characterized by a negative result. All 19 patients were treated by diagnostic-operative laparoscopy: a salpingectomy was carried out after a hydrosalpinx in all these cases. RESULTS: All patients were treated with 2 assisted reproduction cycles, which were made with a variable range of time from 3 to 6 months after laparoscopic surgery, totalizing 38 cycles. At present, 4 pregnancies have been obtained (pregnancy rate = 22%): this value is comparable to the values obtained in the best assisted reproduction programs. CONCLUSIONS: Many studies showed that hydrosglpinx presence reduces very much FIVET procedures. There are many cases showing that the hydrosalpinx become worse, if it has not been preventively treated, during assisted reproduction programs. Moreover complications during FIVET programs in the presence of hydrosalpinx are observed. Even if this study is based on data related to a small number of patients, it's clear that surgical treatment of severe tubarian pathology can give the best results where an assisted reproduction program will be surely unsuccessful.

[Partial hydatidiform mmole at the 17th week of pregnancy]. / Mola incompleta alla 17a settimana di gestazione.

A 36-year-old woman, at the 17th week +5 days gestational age, who was already admitted to the nephrology department for gestational hypertension, proteinuria and legs oedema, was admitted to our Institute. About three weeks before her admission to the nephrology dept., the patient presented heart palpitations and exertional dyspnoea related to the first evidence of the legs oedema, weight gain (about 5 kg during only one month) and normal blood pressure values. During the following days, an antihypertensive therapy was made, but hypertensive crisis and strong headache were also persistent. Vulvar oedema was observed, the uterus was moderately contracted and its dimensions were similar to an uterus at the 21st week; beta-hCG serum values were more than 500,000 IU/lt. An echography confirmed the diagnostic suspicion of hydatidiform the presence of a fetus developed as much as the gestational time. beta-hCG serum values increased to 1,200,000 IU/lt; the molar abortion induction was made thru prostaglandins: fetal extrusion occurred after three hours. The placenta was instrumentally extracted and it showed evident hydatidiform moles a uterine curettage. Patient temperature was very high (39 degrees C) in the immediate postoperative period and three hematologic pockets were transfused. After a week, we made a second elective uterine curettage with the extraction of a little quantity of gestational material; the patient was still hospitalised for ten days: during this time there was a progressive decrease of the beta-hCG serum values (last value at discharge: 7,200 IU/lt). The patient had also positive beta-hCG serum values after about one year.

HIV-1 nef expression inhibits the activity of a Ca2+-dependent K+ channel involved in the control of the resting potential in CEM lymphocytes.

The HIV-1 Nef protein plays an important role in the development of the pathology associated with AIDS. Despite various studies that have dealt with different aspects of Nef function, the complete mechanism by which it alters the physiology of infected cells remains to be established. Nef can associate with cell membranes, therefore supporting the hypothesis that it might interact with membrane proteins as ionic channels and modify their electrical properties. By using the patch-clamp technique, we found that Nef expression determines a 25-mV depolarization of lymphoblastoid CEM cells. Both charybdotoxin (CTX) and the membrane-permeable Ca2+ chelator BAPTA/AM depolarized the membrane of native cells without modifying that of Nef-transfected cells. These data suggested that the resting potential in native CEM cells is settled by a CTX- and Ca2+-sensitive K+ channel (KCa,CTX), whose activity is absent in Nef-expressing cells. This was confirmed by direct measurements of whole-cell KCa,CTX currents. Single-channel recordings on excised patches showed that a KCa,CTX channel of 35 pS with a half-activation near 400 nM Ca2+ was present in both native and Nef-transfected cells. The measurements of free intracellular Ca2+ were not different in the two cell lines, but Nef-transfected cells displayed an increased Ca2+ content in ionomycin-sensitive stores. Taken together, these results indicate that Nef expression alters the resting membrane potential of the T lymphocyte cell line by inhibiting a KCa,CTX channel, possibly by intervening in the regulation of intracellular Ca2+ homeostasis.

Arachidonic acid release by ionomycin and phorbol ester is similar in C127 epithelial cells expressing wild-type or mutated (delta F508) cystic fibrosis transmembrane conductance regulator.

The Ca2+ ionophore ionomycin induced cytosolic [Ca2+ ]i elevation as well as strong activation of Cl- efflux in mouse mammary epithelial cell lines expressing wild-type or mutated (deletion of phenylalaline 508) cystic fibrosis transmembrane conductance regulator (CFTR) or vector. Ionomycin-induced Cl- efflux was abolished by the intracellular Ca2+ chelator 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid, whereas both activators and inhibitors of phospholipase A2 had no effect, indicating the involvement of Ca2+-dependent Cl- channels. Stimulation of arachidonic acid release by ionomycin and phorbol ester was not significantly different between wild-type or mutated cell lines, whereas vector-transfected cells exhibited a significant higher release, which was shown to be due to larger amount of immunoreactive cytosolic phospholipase A2. These results indicate that phospholipase A2 activity of C127 cells was not influenced by the presence of wild-type or mutated CFTR.

Intracellular calcium mobilization and phospholipid degradation in sphingosylphosphorylcholine-stimulated human airway epithelial cells.

Extracellular sphingosylphosphorylcholine (SPC) caused a remarkable elevation in the intracellular Ca2+ concentration ([Ca2+]i) in immortalized human airway epithelial cells (CFNP9o-). An increase in total inositol phosphates formation was determined; however, the dose responses for [Ca2+]i elevation and inositol phosphates production were slightly different and, furthermore, PMA and pertussis toxin almost completely inhibited [Ca2+]i mobilization by SPC, whereas inositol phosphates production was only partially reduced. The possible direct interaction of SPC with Ca2+ channels of intracellular stores was determined by experiments with permeabilized cells, where SPC failed to evoke Ca2+ release, whereas lysophosphatidic acid was shown to be effective. The level of phosphatidic acid was increased by SPC only in the presence of AACOCF3, a specific inhibitor of phospholipase A2 (PLA2) and blocked by both pertussis toxin and R59022, an inhibitor of diacylglycerol kinase. R59022 enhanced diacylglycerol production by SPC and also significantly reduced [Ca2+]i mobilization. Only polyunsaturated diacylglycerol and phosphatidic acid were generated by SPC. Lastly, SPC caused stimulation of arachidonic acid release, indicating the involvement of PLA2. Taken together, these data suggest that, after SPC stimulation, phospholipase C-derived diacylglycerol is phosphorylated by a diacylglycerol kinase to phosphatidic acid, which is further hydrolysed by PLA2 activity to arachidonic and lysophosphatidic acids. We propose that lysophosphatidic acid might be the intracellular messenger able to release Ca2+ from internal stores.

Sphingosylphosphorylcholine and sphingosine-1-phosphate mobilize cytosolic calcium through different mechanisms in human airway epithelial cells.

The sphingosine derivatives sphingosylphosphorylcholine (SPC) and sphingosine-1-phosphate (S1P) caused a similar elevation of the intracellular Ca2+ concentration ([Ca2+]i) in an immortalized airway epithelial cell line (CFNP9o-) incubated in Ca(2+)-free medium. The maximal effect was obtained with 2 microM SPC and 0.1 microM S1P and was sensitive to pre-incubation with pertussis toxin, indicating the involvement of a Gi/G(o) type of G protein. In Ca2+ containing medium, [Ca2+]i elevation by SPC was significantly higher than that by S1P, due to the fact that SPC was able to stimulate Mn2+ entry, whereas S1P was ineffective. SPC, but not S1P, caused a dose-dependent production of total inositol phosphates. Conversely, S1P, but not SPC, increased the level of phosphatidic acid. These findings suggest the presence of two distinct receptors, specific for SPC and S1P, respectively. Depletion of intracellular Ca2+ stores by SPC makes cells unable to respond to a subsequent addition of S1P. Conversely, cells do respond to SPC after a challenge with S1P, suggesting that the two receptors likely share one or more intracellular signalling component(s).

Role of CFTR and anion exchanger in bicarbonate fluxes in C127 cell lines.

C127 cell lines transfected with wtCFTR, delta F508CFTR or vector were employed to determine HCO3- fluxes in the presence or absence of functional CFTR, using the pH-sensitive dye BCECF. Both cytosolic alkalinization and acidification were due to activity of anion exchanger and were similar in the three cell lines, indicating that expression of CFTR did not influence anion exchanger activity. In C127wt cells only, cAMP elevating agents significantly stimulated HCO3- fluxes, insensitive to the inhibitor of anion exchanger 4,4'-diisothiocyanate dihydrostilbene-2,2'-disulfonic acid, suggesting that activated CFTR directly mediates both HCO3- influx and efflux and therefore can contribute to intracellular and extracellular pH regulation.