A new way to approach ASD children in Dentistry.

AIM: To present an innovative dental approach for children with autism spectrum disorder to the scientific community, along with the 3 questionnaires formulated to evaluate its effectiveness. METHODS: Development of the 3 questionnaires occurred in five stages: observation of the behaviours of ADS children and their caregivers attending the Dental Department in the year 2021; issues detection: anxiety in parents, crying, difficulty in waiting and hyperactivity of the children, fear of both parents and children; formulation of the questionnaires in order to obtain all the information necessary to assess the patient's psychological well-being; validation with submission of the questionnaires to two specialists; modification and final drafting. CONCLUSION: Using the 3 questionnaires, the dentist will be able to assess the wellbeing of the patient and his/her family when attending the dental environment, monitor oral hygiene manoeuvres and verify the usefulness of the orthodontic approach to ADS child while creating a trusting relationship with the patient and his/her caregivers.

[Itraconazole 800 mg for the prophylaxis of fungal infections in patients with acute leukemia and severe neutropenia]. / Resultados de profilaxis con itraconazol 800 mg/día vía oral en adultos con leucemia aguda y neutropenia de alto riesgo: Hospital del Salvador 2006-2008.

BACKGROUND: Systemic fungal infections and specifically invasive aspergillosis (IA) are associated with a high morbi-mortality rate in patients with hematologic malignancies. Itraconazole kinetic studies show that plasma levels are not satisfactory, even though there is a reduction of the severity in clinical cases. AIM: To evaluate the results of oral prophylaxis with high dose itraconazole, 400 mg bid, among patients with adult acute leukemia. MATERIAL AND METHODS: Prospective analysis of 93 high risk febrile episodes (with an absolute neutrophil count of less than 500 x mm3 for more 10 days), that occurred in 76 patients. RESULTS: Seventy five percent of episodes occurred in patients with acute myeloid leukemia and 25% in patients with acute lymphoblastic leukemia. Fifty two percent occurred during the induction of chemotherapy. Median duration of severe neutropenia was 21 days (range 10-48). Median duration of itraconazole prophylaxis was 17 days (range 6-34). A low frequency of invasive fungal infections was observed (17%). According to diagnostic criteria, 5% of episodes corresponded to persistent fever , 1% and 11% of episodes, to probable or possible IA, respectively. No confirmed or proven IA was observed. Mortality of IA was 18%. No serious adverse events due to itraconazole were observed. CONCLUSIONS: The use of high dose itraconazole prophylaxis in adult patients with acute leukemia and severe neutropenia was associated to low incidence and mortality of invasive mycoses.

Oral surgery in paediatric dentistry: type of surgical treatment and age distribution in a Public Dental Service in Northern Italy.

AIM: To describe the organisation of the oral dental surgery service of the Department of Pediatric Odontostomatology and Orthodontics, "G. Gaslini" Hospital of Genoa (Italy), as well as type and frequency of the interventions carried out in the considered period of time. MATERIALS AND METHODS: Study design: Descriptive retrospective aepidemiological study about the access and surgery interventions in the years 2015-2018 and the first semester of 2019. This study was conducted at the Department of Pediatric Odontostomatology and Orthodontics of the "G. Gaslini" Hospital of Genoa, Italy, in which treatment is offered to children and adolescents aged between 0-14 years, to whom continuity of care is ensured also after this age range, and to special needs patients, even older that 18 years. The clinical data were extracted from the Hospital database and then statistically analysed with the SPSS programme. RESULTS: Out of a total of 27,663 subjects, the patients who required oral surgery were 1,928 corresponding to 6.96%, for a total of 2,499 surgical interventions of which 1,667 were performed as outpatient surgery (dental chair) and 832 in the operating theatre. All the surgeries were performed by the same three doctors. In the group of patients under 18 years (1,773 subjects) the average age is 9.22 years; it should be underscored that over 70% of oral surgeries are performed on subjects between 7 and 13 years. CONCLUSIONS: Given the low frequency of paediatric oral surgery, this type of intervention should be entrusted to operators and structures that have a wider experience in such cases in order to ensure the highest levels ofsafety.

Cancer incidence in pet dogs: findings of the Animal Tumor Registry of Genoa, Italy.

BACKGROUND: The occurrence of spontaneous tumors in pet animals has been estimated in a few European and North American veterinary cancer registries with dissimilar methodologies and variable reference populations. OBJECTIVES: The Animal Tumor Registry (ATR) of Genoa, Italy, was established in 1985 with the aim of estimating the occurrence of spontaneous tumors in dogs. METHODS: Six thousand seven hundred and forty-three tumor biopsy specimens were received from local veterinarians in the Municipality of Genoa between 1985 and 2002. Three thousand and three hundred and three (48.9%) biopsy specimen samples were diagnosed as cancer and were coded according to the International Statistical Classification of Diseases (ICD-9). RESULTS: Mammary cancer was the most frequently diagnosed cancer in female dogs, accounting for 70% of all cancer cases. Incidence of all cancers was 99.3 per 100,000 dog-years (95% CI: 93.6-105.1) in male dogs and 272.1 (95% CI: 260.7-283.6) in female dogs. The highest incidence rates were detected for mammary cancer (IR = 191.8, 95% CI: 182.2-201.4) and for non-Hodgkin's lymphoma (IR = 22.9, 95% CI: 19.7-26.5) in bitches and for non-Hodgkin's lymphoma (IR = 19.9, 95% CI: 17.4-22.7) and skin cancer (IR = 19.1, 95% CI: 16.6-21.8) in male dogs. All cancer IR increased with age ranging between 23.7 (95% CI: 18.4-30.1) and 763.2 (95% CI: 700.4-830.1) in bitches and between 16.5 (95% CI: 12.8-21.1) and 237.6 (95% CI: 209.1-269.0) in male dogs aged < or =3 years and >9-11 years. CONCLUSION: This study summarizes the work done by the ATR of Genoa, Italy, between 1985 and 2002. All cancer incidence was 3 times higher in female than in male dogs, a difference explained by the high rate of mammary cancer observed in bitches. Because a biopsy specimen was required to make a cancer diagnosis, cancer rates for internal organs cancers, such as respiratory and digestive tract cancers may have been underestimated in the study population.

Water permeability in the human amnion: pH regulation of the paracellular pathway.

Human amnion was mounted, immediately after delivery, as a diaphragm between two lucite chambers and the net transepithelial water movement (Jw) was recorded minute by minute. When Jw was plotted against the applied transepithelial hydrostatic pressure (fetal side positive), in the absence of any other gradient, a linear relationship was observed (Phydr = 0.32 +/- 0.05 cm/s, n = 10). A linear relationship was also found when Jw was measured in the presence of an osmotic gradient, generated by adding (to the maternal side) different concentrations of poly(ethylene glycol) (Mr approximately equal to 3600; reflexion coefficient (sigma) = 1; Posm = 0.015 +/- 0.001 cm/s, n = 10). When sucrose, a paracellular marker, was used as the osmotic probe, the observed sigma was 0.5. Medium acidification in the presence of bicarbonate reduced in the same proportion both the hydrostatic and osmotic permeabilities. The effect was fully reversible, but was not observed when bicarbonate was replaced by Tris. To test the comparative role of transcellular versus paracellular paths, Jw and the [14C]sucrose permeability (Psuc) were simultaneously recorded minute by minute, in the presence of an osmotic or an hydrostatic gradient. In both cases, the percentage reductions in Jw and Psuc induced by medium acidification were similar. Quantification of theoretical and observed values for Jw and Psuc strongly suggests that effects of pH on both the osmotic and hydrostatic flux reflect a modification of the paracellular path.

Increased glucose transfer in the rat jejunum after dietary potassium loading: effect of amiloride.

The glucose transfer across the jejunum was measured in Wistar rats under a high potassium diet (HKD). In 12 of 27 HKD animals the transfer coefficient for D-glucose was not significantly higher than in control ones, (7.38 +/- 0.88).10(-5) s-1. In the other 15 a clear increase in glucose transfer was observed, (23.31 +/- 2.50).10(-5) s-1. The D-glucose transfer in the first group (n = 12) was, as in the case of the control rats, insensitive to amiloride section (10(-4) M), while D-glucose transfer became sensitive to amiloride in the second group (mean inhibition 94 +/- 8%, n = 14). A smaller but significant increase in L-glucose and sucrose transfers was also observed when the D-glucose movement was increased. No differences in short-circuit current, transepithelial potential, resistance and mucosa to serosa Na+ fluxes were observed between control and HKD rats and no effects of amiloride (10(-4) M) on these parameters were observed either in control or in HKD animals. [3H]Glucose uptake as also performed in brush-border vesicles prepared from rat jejunum, under control and HKD conditions. The specific and Na(+)-dependent 'overshoot' in D-glucose concentration, in vesicles prepared from HKD rats, became sensitive to amiloride action (10(-5) M). It is concluded that, besides the cellular adaptation induced in the distal portion of the nephron and large intestine, dietary potassium loading induces important modifications in glucose transfer in the rat jejunum.

Electrical parameters and water permeability properties of monolayers formed by T84 cells cultured on permeable supports.

T84 is an established cell line expressing an enterocyte phenotype whose permeability properties have been widely explored. Osmotic permeability (POSM), hydraulic permeability (PHYDR) and transport-associated net water fluxes (JW-transp), as well as short-circuit current (ISC), transepithelial resistance (RT), and potential difference (deltaVT) were measured in T84 monolayers with the following results: POSM 1.3 +/- 0.1 cm.s-1 x 10-3; PHYDR 0.27 +/- 0.02 cm.s-1; RT 2426 +/- 109 omega.cm2, and deltaVT 1.31 +/- 0.38 mV. The effect of 50 microM 5,6-dichloro-1-ethyl-1,3-dihydro-2H-benzimidazol-2-one (DCEBIO), a "net Cl- secretory agent", on T84 cells was also studied. We confirm the reported important increase in ISC induced by DCEBIO which was associated here with a modest secretory deltaJW-transp. The present results were compared with those reported using the same experimental approach applied to established cell lines originating from intestinal and renal epithelial cells (Caco-2, LLC-PK1 and RCCD-1). No clear association between PHYDR and RT could be demonstrated and high PHYDR values were observed in an electrically tight epithelium, supporting the view that a "water leaky" barrier is not necessarily an "electrically leaky" one. Furthermore, the modest secretory deltaJW-transp was not consistent with previous results obtained with RCCD-1 cells stimulated with vasopressin (absorptive fluxes) or with T84 cells secreting water under the action of Escherichia coli heat stable enterotoxin. We conclude that, while the presence of aquaporins is necessary to dissipate an external osmotic gradient, coupling between water and ion transport cannot be explained by a simple and common underlying mechanism.

TRPV4 mediates flow-induced increases in intracellular Ca in medullary thick ascending limbs.

UNLABELLED: Medullary thick ascending limbs (mTAL) regulate Na balance and therefore blood pressure. We previously showed that cell swelling and luminal flow activates the mechanosensitive channel TRPV4 in mTAL. AIM: We hypothesized that TRPV4 mediates flow-induced increases in intracellular Ca (Cai) in rat mTALs. METHODS: We performed ratiometric measurements of Cai in perfused mTALs. RESULTS: Increasing luminal flow from 0 to 20 nL min(-1) caused Cai to peak 231 ± 29 nmol L(-1) above basal concentrations (n = 18). The general TRPV inhibitor ruthenium red at 15 and 50 µmol L(-1) reduced peak Cai by 41 ± 9 (P < 0.01; n = 5) and 77 ± 10% (P < 0.02; n = 6). The selective TRPV4 inhibitor RN1734 at 10 and 50 µmol L(-1) reduced peak Cai by 46 ± 11 (P < 0.01; n = 7) and 76 ± 5% (P < 0.02; n = 5) respectively. To specifically target TRPV4, mTALs were transduced with adenoviruses expressing TRPV4 small hairpin (sh) RNA. In non-transduced control mTALs, luminal flow generated a peak increase in Cai of 111 ± 21 nmol L(-1) (n = 8). In TRPV4shRNA-transduced mTALs, the Cai peak was reduced to 56 ± 8 nmol L(-1) (P < 0.03, n = 9). Removing extracellular Ca completely abolished flow-induced increases in Cai. Increasing luminal flow in the presence of hexokinase 20 (U mL(-1) ) to scavenge extracellular ATP did not modify significantly the increases in Cai induced by luminal flow. Finally, we studied the effect of the TRPV4 selective agonist GSK1016790A on Cai. In the absence of luminal flow, GSK1016790A (10 nmol L(-1) ) increased Cai from 60 ± 11 nmol L(-1) to 262 ± 71 nmol L(-1) (P < 0.05; n = 7). CONCLUSION: We conclude that flow-induced increases in Cai are mediated primarily by TRPV4 in the rat mTAL.

Biophysical properties of epithelial water channels.

The biophysical models describing the structure of water pores or channels have evolved, during the last forty years, from a pure 'black box' approach to a molecular based proposal. The initial 'sieving pore' in which water and other molecules were moving together was replaced by a more restrictive model, where water is moving alone in a 'single file' mode. Aquaporins discovery and cloning [G.M. Preston, T.P. Carroll, W.B. Guggino, P. Agre, Science 256 (1992) 365] leaded to the 'hour-glass model' and other alternative proposals, combining information coming from molecular biology experiments and two dimensional crystallography. Concerning water transfers in epithelial barriers the problem is quite complex, because there are at least two alternative pathways: paracellular and transcellular and three different driving forces: hydrostatic pressure, osmotic pressure or 'transport coupled' movements. In the case of ADH-sensitive epithelia it is more or less accepted that regulated water channels (AQP2), that can be inserted in the apical membrane, coexist with basolateral resident water channels (AQP3). The mechanism underlying the so-called 'transport associated water transfer' is still controversial. From the classical standing gradient model to the ion-water co-transport, different hypothesis are under consideration. Coming back to hormonal regulations, other than the well-known regulation by neuro-hypophysis peptides, a steroid second messenger, progesterone, has been recently proposed [P. Ford, G. Amodeo, C. Capurro, C. Ibarra, R. Dorr, P. Ripoche, M. Parisi, Am. J. Physiol. 270 (1996) F880].

Fibroblasts regulate the migration of MCF7 mammary carcinoma cells in hydrated collagen gel.

We have defined a tissue culture method suitable to study cell-cell interactions in an environmental set close to in vivo conditions. It consists of heterotypic cell populations mixed together inside a collagen gel in a chamber slide for a period of up to 14 days. When the three-dimensional system is saturated, cells will start to move on the plastic surface as monolayers surrounding the gel, with a characteristic speed depending on cell type. Usually fibroblasts move fast, while epithelial cells demonstrate a much lower pace of migration. At any given time gel contraction can be measured, and thus the rate of cell expansion, by knowing the distance from the edge of the gel to the leading edge of cell migration. By using this approach it was found that MCF7 mammary carcinoma cells display a great variety of morphologies following their mixture with different fibroblastic cell lines. In particular, when MCF7 cells were mixed with fibroblasts from human fetus, dog thymus and rat kidney, they migrated up to the leading edge of the fibroblastic front as isolated single cells or as cellular aggregates, many of which became necrotic in time, or took on an elongated morphology. Selective necrosis of MCF7 cells was also induced with serum concentration of 15% and 20% FCS, but only when they were mixed with fibroblasts. No necrosis was induced in MCF7 cells cultured alone. From these observations it is suggested that necrosis may sometimes favor the detachment and infiltration of resistant epithelial tumor cells by increasing their autonomous behaviour. Fibroblasts seem to be instrumental in regulating this process.

Bone allografts and adjuvant cisplatin for the treatment of canine appendicular osteosarcoma in 18 dogs.

The results achieved in 18 dogs following the use of frozen bone cortical allografts for limb-sparing resection of non-metastatic canine appendicular osteosarcoma are presented. Three to five cisplatin doses (70 mg/m2) were administered, starting the day after surgery. The mean and median survival times were 478 and 266 days (range 80 to 2,611 days), respectively. The survival rate was 94 per cent at three months, 78 per cent at six months, 35 per cent at 12 months, 23 per cent at 18 months and 19 per cent at 24 months; the disease-free interval was 80 to 1,246 days (mean 365 days, median 266 days). Lung metastasis developed in 55 per cent of the dogs within one year. Complications were observed in 14/18 dogs (78 per cent), comprising local recurrence (28 per cent), allograft infection (39 per cent) and implant failure (11 per cent). Despite complications, limb sparing is a useful alternative to amputation in selected cases of appendicular osteosarcoma.

Role of AQP2 in activation of calcium entry by hypotonicity: implications in cell volume regulation.

We previously reported in a rat cortical collecting duct cell line (RCCD(1)) that the presence of aquaporin 2 (AQP2) in the cell membrane is critical for the rapid activation of regulatory volume decrease mechanisms (RVD) (Ford et al. Biol Cell 97: 687-697, 2005). The aim of our present work was to investigate the signaling pathway that links AQP2 to this rapid RVD activation. Since it has been previously described that hypotonic conditions induce intracellular calcium ([Ca(2+)](i)) increases in different cell types, we tested the hypothesis that AQP2 could have a role in activation of calcium entry by hypotonicity and its implication in cell volume regulation. Using a fluorescent probe technique, we studied [Ca(2+)](i) and cell volume changes in response to a hypotonic shock in WT-RCCD(1) (not expressing aquaporins) and in AQP2-RCCD(1) (transfected with AQP2) cells. We found that after a hypotonic shock only AQP2-RCCD(1) cells exhibit a substantial increase in [Ca(2+)](i). This [Ca(2+)](i) increase is strongly dependent on extracellular Ca(2+) and is partially inhibited by thapsigargin (1 muM) indicating that the rise in [Ca(2+)](i) reflects both influx from the extracellular medium and release from intracellular stores. Exposure of AQP2-RCCD(1) cells to 100 muM gadolinium reduced the increase in [Ca(2+)](i) suggesting the involvement of a mechanosensitive calcium channel. Furthermore, exposure of cells to all of the above described conditions impaired rapid RVD. We conclude that the expression of AQP2 in the cell membrane is critical to produce the increase in [Ca(2+)](i) which is necessary to activate RVD in RCCD(1) cells.

Resultados de profilaxis con itraconazol 800 mg/día vía oral en adultos con leucemia aguda y neutropenia de alto riesgo: Hospital del Salvador 2006-2008 / Itraconazole 800 mg for the prophylaxis of fungal infections in patients with acute leukemia and severe neutropenia

Background: Systemic fungal infections and specifically invasive aspergillosis (IA) are associated with a high morbi-mortality rate in patients with hematologic malignancies. Itraconazole kinetic studies show that plasma levels are not satisfactory, even though there is a reduction of the severity in clinical cases. Aim: To evaluate the results of oral prophylaxis with high dose itraconazole, 400 mg bid, among patients with adult acute leukemia. Material and Methods: Prospective analysis of 93 high risk febrile episodes (with an absolute neutrophil count of less than 500 x mm3 for more 10 days), that occurred in 76 patients. Results: Seventy five percent of episodes occurred in patients with acute myeloid leukemia and 25 percent in patients with acute lymphoblastic leukemia. Fifty two percent occurred during the induction of chemotherapy. Median duration of severe neutropenia was 21 days (range 10-48). Median duration of itraconazole prophylaxis was 17 days (range 6-34). A low frequency of invasive fungal infections was observed (17 percent). According to diagnostic criteria, 5 percent of episodes corresponded to persistent fever , 1 percent and 11 percent of episodes, to probable or possible IA, respectively. No confirmed or proven IA was observed. Mortality of IA was 18 percent. No serious adverse events due to itraconazole were observed. Conclusions: The use of high dose itraconazole prophylaxis in adult patients with acute leukemia and severe neutropenia was associated to low incidence and mortality of invasive mycoses.

Asymmetry in the osmotic response of a rat cortical collecting duct cell line: role of aquaporin-2.

Transition from antidiuresis to diuresis exposes cortical collecting duct cells (CCD) to asymmetrical changes in environment osmolality, inducing an osmotic stress, which activates numerous membrane-associated events. The aim of the present work was to investigate, either in the presence or not of AQP2, the transepithelial osmotic water permeability (P(osm)) following cell exposure to asymmetrical hyper- or hypotonic gradients. For this purpose, transepithelial net volume fluxes were recorded every minute in two CCD cell lines: one not expressing AQPs (WT-RCCD(1)) and another stably transfected with AQP2 (AQP2-RCCD(1)). Our results demonstrated that the rate of osmosis produced by a given hypotonic shock depends on the gradient direction (osmotic rectification) only in the presence of apical AQP2. In contrast, hypertonic shocks elicit P(osm) rectification independently of AQP2 expression, and this phenomenon may be linked to modulation of basolateral membrane permeability. No asymmetry in transepithelial resistance was observed under hypo- or hypertonicity, indicating that rectification cannot be attributed to a shunt through the tight junction path. We conclude that osmotic rectification may be explained in terms of dynamical changes in membrane permeability probably due to activation/incorporation of AQPs or transporters to the plasma membrane via some mechanism triggered by osmolality.

Water handling in the rat jejunum: effects of acidification of the medium.

The minute-by-minute net water movement (Jw) in the rat jejunum was studied in relation to the diffusive water (Pw) and mannitol (Ps) permeabilities with the following results. (a) Jw was a linear function of the applied hydrostatic and osmotic transepithelial gradients (hydrostatic permeability coefficient, Phydr = 0.052 +/- 0.011 cm s-1; osmotic permeability coefficient, Posm = 0.0069 +/- 0.0014 cm s-1. (b) A fraction of this absorptive Jw (transport-associated Jw, Jwt = 0.086 +/- 0.024 microliter min-1 cm-2) was independent of the presence of any osmotic, hydrostatic or chemical gradient. (c) In the absence of Na+, Jwt was not significantly different from zero and there was an increase in Phydr but no change in Posm. (d) In the presence of a hydrostatic gradient (10 cm H2O, mucosal side), acidification of the medium (95% CO2 bubbling, pH 6.2) simultaneously and reversibly increased Jw and decreased Pw. (e) When an osmotic gradient was present (40 mM polyethyleneglycol on the serosal side) a net increase in Jw was observed. CO2 bubbling in these conditions reversibly reduced Jw while increasing Ps. (f) These effects were not observed when the serosal or mucosal pH was reduced in the presence of a nonpermeant buffer (HEPES/TRIS; MES/TRIS). If we accept that Ps is a good marker of paracellular movements and that Pw mainly reflects transcellular water movements, we may conclude that acidification of the medium, in the presence of bicarbonate, modifies both paracellular and transcellular routes. The experimental evidence indicates that an increase in proton concentration opens the paracellular pathway and probably has a blocking effect on a transcellular route.

Water permeability in different epithelial barriers.

The water permeability properties of a series of epithelial barriers (the toad urinary bladder [TUB], the rat caecum [RC], the distal human colon [DHC], and the human amnion [HA] were studied in different experimental conditions. Three parameters were simultaneously determined: the water permeability coefficient in the presence of a transepithelial hydrostatic gradient (Phydr); the water permeability coefficient in the presence of an osmotic gradient (Posm); and the transepithelial potential difference (dV). All experiments were performed with the same experimental device, allowing comparison of the permeability properties of the barriers tested. The results obtained were: (1) TUB (N = 8): Phydr = 0.079 +/- 0.008 cm/s; Posm = 0.0004 +/- 0.0002 cm/s; dV = 31 +/- 5 mV; (2) TUB after ADH (N = 8): Phydr = 0.093 +/- 0.012 cm/s; Posm = 0.0065 +/- 0.0011 cm/s; dV = 52 +/- 8; (3) RC (N = 10): Phydr = 0.18 +/- 0.02 cm/s; Posm = 0.0019 +/- 0.0004 cm/s; dV = 3.9 +/- 0.1 mV; (4) RC adapted to a high K diet (N = 10): Phydr = 0.21 +/- 0.02 cm/s; Posm = 0.0018 +/- 0.0006 cm/s; dV = 4.5 +/- 0.5 mV; (5) DHC (N = 6): Phydr = 0.22 +/- 0.03 cm/s; Posm = 0.002 +/- 0.05 cm/s; dV = 15 +/- 3 mV; (6) HA (N = 10): Phydr = 0.32 +/- 0.05 cm/s; Posm = 0.0154 +/- 0.0015; dV = 0. The results show a good correlation between Phydr and dV, but not between dV and Posm or between Posm and Phydr.

Water and ion coupling in the rat cecum during dietary potassium loading.

The transepithelial net water movement (Jw) was minute by minute recorded in the cecum of Wistar rats adapted to a high potassium diet (HKD). The potential difference (PD), short circuit current (SCC) and unidirectional 22Na, 36Cl, and 89Rb fluxes were also measured. The hydrostatic and osmotic permeabilities were not modified by potassium adaptation when a standard bicarbonate buffer was employed. Potassium adaptation implicated the development of a secretory, transport-associated Jw (Jwt), associated to an increase in transepithelial PD, SCC and net sodium transport. Contrary to the case of control rats, no net chloride transport was observed in HKD rats. The secretory Jwt compensated, in the presence of sodium, chloride and bicarbonate, an absorptive Jwt. Water secretion was coupled to net potassium secretion. Replacement of chloride by sulphate ions was paralleled by the development of a net absorptive Jw and by increases in the transepithelial Pd and hydrostatic permeability. Replacement of the bicarbonate buffer by a tris-hepes buffer made drop both the observed absorptive Jw and PD amiloride sensitive Na+ entry was observed.

Distribution of mRNA encoding the FA-CHIP water channel in amphibian tissues: effects of salt adaptation.

A water channel, the frog aquaporin-CHIP (FA-CHIP) was recently cloned from Rana esculenta urinary bladder. The 28.9 kDa encoded protein shows 78.8%, 77.4%, 42.4% and 35.6% identity with rat CHIP28, human CHIP28, rat WCH-CD and gamma-TIP, other members of the new transmembrane water channel family (Aquaporin-CHIP). We have now studied membranes from different frog (R. esculenta) organs employing semiquantitative PCR using FA-CHIP specific primers and an internal standard to quantify the PCR products. The FA-CHIP mRNA was abundantly expressed in the frog urinary bladder, skin, lung and gall bladder, while a lower expression was detected in the colon, liver and oviduct. FA-CHIP mRNA was not detected in the frog kidney, erythrocytes and brain but its expression was observed in the toad (Bufo arenarum) urinary bladder and skin, showing that FA-CHIP is probably a general amphibian water channel. Salt acclimation is known to increase the water permeability of frog and toad epithelia. We have now observed that salt acclimation for 1, 3, 4 or 5 days markedly increased skin and urinary bladder FA-CHIP mRNA expression. It is generally accepted that water permeability is controlled in these tissues by the rate of water channel transfer from subapical vesicles (aggrephores) to the apical membrane. Our results indicate that water permeability is also regulated at the level of the FA-CHIP transcription.