Ricardo Dorr | Universidad de Buenos Aires/CONICET (original) (raw)
Papers by Ricardo Dorr
Healthcare Informatics Research
Objectives: Automated systems for information extraction are becoming very useful due to the enor... more Objectives: Automated systems for information extraction are becoming very useful due to the enormous scale of the existing literature and the increasing number of scientific articles published worldwide in the field of medicine. We aimed to develop an accessible method using the open-source platform KNIME to perform text mining (TM) on indexed publications. Material from scientific publications in the field of life sciences was obtained and integrated by mining information on hemolytic uremic syndrome (HUS) as a case study. Methods: Text retrieved from Europe PubMed Central (PMC) was processed using specific KNIME nodes. The results were presented in the form of tables or graphical representations. Data could also be compared with those from other sources. Results: By applying TM to the scientific literature on HUS as a case study, and by selecting various fields from scientific articles, it was possible to obtain a list of individual authors of publications, build bags of words an...
Medicina-buenos Aires, 2021
Medicina-buenos Aires, 2021
Medicina, 2021
In the present work we use text mining as a treatment tool for a large scientific database, with ... more In the present work we use text mining as a treatment tool for a large scientific database, with the aim of obtaining new information about all the publications signed by Argentine authors and indexed until 2019, in the area of life sciences. More than 75 000 articles were analysed, published in around 5000 media, signed by about 186 000 authors with a workplace in Argentina or in collaborations with Argentine laboratories. Using automated tools that were developed ad hoc, the text of around 70 800 abstracts was analysed, seeking, through non-supervised digital detection, the main topics addressed by the authors, and the relationship with health problems in Argentina and their treatment. Results are also presented regarding the number of publications per year, the journals that have published them, and their authors and collaborations. These results, together with the predictions that were obtained, could become a useful tool to optimize the management of resources dedicated to basi...
Medicina, 2021
In the present work we use text mining as a treatment tool for a large scientific database, with ... more In the present work we use text mining as a treatment tool for a large scientific database, with the aim of obtaining new information about all the publications signed by Argentine authors and indexed until 2019, in the area of life sciences. More than 75 000 articles were analysed, published in around 5000 media, signed by about 186 000 authors with a workplace in Argentina or in collaborations with Argentine laboratories. Using automated tools that were developed ad hoc, the text of around 70 800 abstracts was analysed, seeking, through non-supervised digital detection, the main topics addressed by the authors, and the relationship with health problems in Argentina and their treatment. Results are also presented regarding the number of publications per year, the journals that have published them, and their authors and collaborations. These results, together with the predictions that were obtained, could become a useful tool to optimize the management of resources dedicated to basi...
American Journal of Physiology-Renal Physiology, 1996
The ovarian oocytes from Bufo arenarum (BAO) but not those from Xenopus laevis (XLO) would have w... more The ovarian oocytes from Bufo arenarum (BAO) but not those from Xenopus laevis (XLO) would have water channels (WC). We now report that the injection of the mRNA from BAO into the oocytes from XLO increased their water osmotic permeability (Pi) (reduced by 0.3 mM HgCl2 and reversed by 5 mM beta-mercaptoethanol). A 30-min challenge with progesterone induced, 18 h later, a reduction of the mercury-sensitive fraction of Pf in the BAO (but not in XLO). The mRNA from BAO pretreated with progesterone lost its capacity to induce WC in the XLO, but the hormone did not affect the expression of the WC in XLO previously injected with the mRNA from BAO. Pf was also measured in urinary bladders of BAO. Eighteen hours after a challenge with progesterone, a reduction in the hydrosmotic response to oxytocin was observed. Finally, the mRNA from the urinary bladder of BAO was injected into XLO. An increase in Pf was observed. This was not the case if, before the mRNA extraction, the bladders were tre...
American Journal of Physiology-Renal Physiology, 1996
The ovarian oocytes from Bufo arenarum (BAO) but not those from Xenopus laevis (XLO) would have w... more The ovarian oocytes from Bufo arenarum (BAO) but not those from Xenopus laevis (XLO) would have water channels (WC). We now report that the injection of the mRNA from BAO into the oocytes from XLO increased their water osmotic permeability (Pi) (reduced by 0.3 mM HgCl2 and reversed by 5 mM beta-mercaptoethanol). A 30-min challenge with progesterone induced, 18 h later, a reduction of the mercury-sensitive fraction of Pf in the BAO (but not in XLO). The mRNA from BAO pretreated with progesterone lost its capacity to induce WC in the XLO, but the hormone did not affect the expression of the WC in XLO previously injected with the mRNA from BAO. Pf was also measured in urinary bladders of BAO. Eighteen hours after a challenge with progesterone, a reduction in the hydrosmotic response to oxytocin was observed. Finally, the mRNA from the urinary bladder of BAO was injected into XLO. An increase in Pf was observed. This was not the case if, before the mRNA extraction, the bladders were tre...
Journal of Membrane Biology
Volume changes were studied in Beta vulgaris storage root vacuoles, using video microscopy, when ... more Volume changes were studied in Beta vulgaris storage root vacuoles, using video microscopy, when exposed to hypotonic conditions. The osmotic gradient was either step-applied or progressively imposed in perfusion experiments. Preincubation at low pH (6.6) or with HgCl2 strongly reduced the vacuoles' water permeability, measured in step experiments. Furthermore, the volumetric response depended on the rate with which the aniso-osmotic condition was established. In perfusion experiments a "plateau value" (osmotic equilibrium or steady-state volume value) was observed, which was significantly lower than the theoretically expected one. Furthermore, if vacuoles were preincubated in presence of HgCl2 or at low pH and then the hypo-osmotic challenge was applied in perfusion experiments, a still lower "plateau value" was observed. This reduction was concentration-dependent and completely reversible. In these conditions, when HgCl2 concentration was 300 mM or medium p...
Life Sciences, 1992
Toad bladders sacs were placed inside quartz cuvettes. When fura-2 AM was added to the mucosal co... more Toad bladders sacs were placed inside quartz cuvettes. When fura-2 AM was added to the mucosal compartment, low temperature (4 degrees C) almost completely blocked the transepithelial transfer of fluorescence observed at 20 degrees C (20 degrees C = 371 +/- 56, 4 degrees C = 29 +/- 29 fluorescence intensity in arbitrary units (FIAU), excitation at 340 nm, emission at 510 nm). Simultaneously, fluorescence accumulation inside the tissue was significantly higher (20 degrees C = 25 +/- 5, 4 degrees C = 91 +/- 24% increase on basal levels (%IBL)). When fura-2 AM was added to the serosal side, low temperature also reduced the serosal to mucosal transfer (20 degrees C = 149 +/- 36, 4 degrees C = 61 +/- 35 FIAU). Nevertheless, in this situation tissue accumulation, that was significantly higher that the one observed when fura-2 AM was added to the mucosal side, was reduced at low temperature (20 degrees C = 300 +/- 30, 4 degrees C = 48 +/- 7 %IBL). Spectral analysis of the mucosal and serosal compartments indicated that free fura-2 was transferred from the intracellular to the serosal compartment, but not to the mucosal one. These results indicate that fura-2 appears as a useful tool to evaluate the cellular distribution and traffic of polycyclic charged and non-charged molecules.
Journal of Biochemical and Biophysical Methods, 2005
Membrane water permeability is habitually calculated from volume changes in Xenopus laevis oocyte... more Membrane water permeability is habitually calculated from volume changes in Xenopus laevis oocytes during external osmotic challenges. Nevertheless, this approach is limited by the uncertainty on the oocyte internal composition. To circumvent this limitation a new experimental set up is introduced where the cell membrane of an emptied-out oocyte was mounted as a diaphragm between two chambers. In its final configuration the oocyte membrane was part of a closed compartment and net water movements induced swelling or shrinking of it. Volume changes were followed by videomicroscopy and digitally recorded. In this manner, water movements could be continuously monitored while controlling chemical composition and hydrostatic pressure on both sides of the membrane. Using this novel experimental approach an increasing hydrostatic pressure gradient was applied to both mature (stage VI) and immature (stage IV) oocytes. The relative maximal volume change tolerated before disruption was similar in both cases (1.26 F 0.07 and 1.27 F 0.03 respectively) and similar to those previously reported under maximal osmotic stress. Nevertheless the osmotic permeability coefficient (P OSM) in mature oocytes ((1.72 F 0.58) Â 10 À 3 cm s À 1 ; n = 6) was significantly lower than in immature oocytes ((5.18 F 0.59) Â 10 À 3 cm s À 1 , n = 5; p b 0.005).
Journal of Neuroscience Methods, 2007
Water channels (aquaporins) family members have been identified in central nervous system cells. ... more Water channels (aquaporins) family members have been identified in central nervous system cells. A classic method to measure membrane water permeability and its regulation is to capture and analyse images of Xenopus laevis oocytes expressing them. Laboratories dedicated to the analysis of motion images usually have powerful equipment valued in thousands of dollars. However, some scientists consider that new approaches are needed to reduce costs in scientific labs, especially in developing countries. The objective of this work is to share a very low-cost hardware and software setup based on a well-selected webcam, a hand-made adapter to a microscope and the use of free software to measure membrane water permeability in Xenopus oocytes. One of the main purposes of this setup is to maintain a high level of quality in images obtained at brief intervals (shorter than 70 ms). The presented setup helps to economize without sacrificing image analysis requirements.
Journal of Experimental Botany, 1999
To evaluate the contribution of transcellular, apo-Radial and axial water pathways in plant roots... more To evaluate the contribution of transcellular, apo-Radial and axial water pathways in plant roots are plastic and symplastic pathways to water movements, central elements in the soil-plant-atmosphere continuum horizontal (axial pathway) and vertical (radial pathway) (Newman, 1976; Passioura, 1988). Nevertheless, even sugar beet root (Beta vulgaris L.) slices were studied. when osmotic and hydraulic pressure gradients are at the Volume flows (J v) were measured under hydrostatic origin of water movements (Steudle, 1989, 1997), their and/or osmotic gradients, using a computer-based specific role in each case is not yet clarified. The evaluation data-acquisition system. When tissues were tested of the contribution of the apoplastic versus the protounder hydrostatic gradients (0.3 MPa m−1) a much plasmic pathway has been controversial (Passioura, 1988; more important permeability was observed in the axial Steudle 1989, 1997) and a recent work in parenchyma pathway, as compared with the radial one. Negative potato slices reinforces the role of flux through cell walls, pressure gradients (tensions) were as effective as circumventing the protoplasts, in living tissues (Michael positive ones in inducing a net water movement. After et al., 1997). the establishment of a concentration gradient in the The discovery of proteins that specifically facilitate the radial pathway (obtained by adding 300 M m−3 mannipermeation of water across membranes (water channels tol to the employed solution) an osmotic flux, sensitive or aquaporins, Agre et al., 1993) has reopened the debate to HgCl 2 , was observed. The inhibitory effect of merof the role of the protoplasmic or cell-to-cell routes. curial compounds was reversed by b-mercaptoethanol Water channels have been localized in the tonoplast as while [14C] mannitol unidirectional fluxes were not well as in the plasma membrane of higher plant cells affected by mercurial agents. In the axial pathway, the (Maurel et al., 1993; Chrispeels and Maurel, 1994; Martypresence of a mannitol gradient did not develop a Mazars et al., 1995; Schäffner, 1998). A large group of sustained osmotic flux. After an initial J v in the these family members is reversibly blocked by mercurial expected direction, the J v reversed and moved in the compounds, which facilitates its study. An inhibitory opposite way. It is concluded that, in the sugar beet effect of mercury chloride on water movements in the root, water channels play a significant role in water tomato (Maggio and Joly, 1995) and wheat roots has transfers in the radial pathway. On the other side, been reported (Carvajal et al., 1996). water and solutes are transported by a hydrostatic A computer-based data-acquisition system designed for gradient in the xylem vessels. In general, these results the measurement of net volume fluxes (J v) across bioextend and adapt to a storage root the 'composite logical structures (Dorr et al., 1996) has recently been transport model' first proposed by Steudle et al. developed. The system was employed with success in different animal tissues (
Journal of Biological Physics, 2007
This review focuses on studies of water movement across biological membranes performed over the l... more This review focuses on studies of water movement across biological membranes performed over the last 50 years. Different scientific approaches had tried to elucidate such intriguing mechanism, from hypotheses emphasizing the role of the lipid bilayer to the cloning of aquaporins, the ubiquitous proteins described as specific water channels. Pioneering and clarifying biophysical work are reviewed beside results obtained with the help of recent sophisticated techniques, to conclude that great advances in the subject live together with old questions without definitive answers.
European Biophysics Journal, 2011
This work studies water permeability properties of human aquaporin 1 (hAQP1) expressed in Xenopus... more This work studies water permeability properties of human aquaporin 1 (hAQP1) expressed in Xenopus laevis oocyte membranes, applying a technique where cellular content is replaced with a known medium, with the possibility of measuring intracellular pressure. Consequences on water transport-produced by well-known anisotonic gradients and by the intracellular effect of probable aquaporin inhibitors-were tested. In this way, the specific intracellular inhibition of hAQP1 by the diuretic drug furosemide was demonstrated. In addition, experiments imposing anisotonic mannitol gradients with a constant ionic strength showed that the relationship between water flux and the applied mannitol gradient deflects from a perfect osmometer response when the gradient is higher than 150 mosmol kg W-1. These results would indicate that the passage of water molecules through hAQP1 may have a maximum rate. As a whole, this work demonstrates the technical advantage of controlling both intracellular pressure and medium composition in order to study biophysical properties of hAQP1, and contributes information on water channel behavior under osmotic challenges and the discovery of new inhibitors. Keywords hAQP1 Á Intracellular inhibition Á Furosemide Á Anisotonic gradients Á Xenopus oocytes Electronic supplementary material The online version of this article (
Healthcare Informatics Research
Objectives: Automated systems for information extraction are becoming very useful due to the enor... more Objectives: Automated systems for information extraction are becoming very useful due to the enormous scale of the existing literature and the increasing number of scientific articles published worldwide in the field of medicine. We aimed to develop an accessible method using the open-source platform KNIME to perform text mining (TM) on indexed publications. Material from scientific publications in the field of life sciences was obtained and integrated by mining information on hemolytic uremic syndrome (HUS) as a case study. Methods: Text retrieved from Europe PubMed Central (PMC) was processed using specific KNIME nodes. The results were presented in the form of tables or graphical representations. Data could also be compared with those from other sources. Results: By applying TM to the scientific literature on HUS as a case study, and by selecting various fields from scientific articles, it was possible to obtain a list of individual authors of publications, build bags of words an...
Medicina-buenos Aires, 2021
Medicina-buenos Aires, 2021
Medicina, 2021
In the present work we use text mining as a treatment tool for a large scientific database, with ... more In the present work we use text mining as a treatment tool for a large scientific database, with the aim of obtaining new information about all the publications signed by Argentine authors and indexed until 2019, in the area of life sciences. More than 75 000 articles were analysed, published in around 5000 media, signed by about 186 000 authors with a workplace in Argentina or in collaborations with Argentine laboratories. Using automated tools that were developed ad hoc, the text of around 70 800 abstracts was analysed, seeking, through non-supervised digital detection, the main topics addressed by the authors, and the relationship with health problems in Argentina and their treatment. Results are also presented regarding the number of publications per year, the journals that have published them, and their authors and collaborations. These results, together with the predictions that were obtained, could become a useful tool to optimize the management of resources dedicated to basi...
Medicina, 2021
In the present work we use text mining as a treatment tool for a large scientific database, with ... more In the present work we use text mining as a treatment tool for a large scientific database, with the aim of obtaining new information about all the publications signed by Argentine authors and indexed until 2019, in the area of life sciences. More than 75 000 articles were analysed, published in around 5000 media, signed by about 186 000 authors with a workplace in Argentina or in collaborations with Argentine laboratories. Using automated tools that were developed ad hoc, the text of around 70 800 abstracts was analysed, seeking, through non-supervised digital detection, the main topics addressed by the authors, and the relationship with health problems in Argentina and their treatment. Results are also presented regarding the number of publications per year, the journals that have published them, and their authors and collaborations. These results, together with the predictions that were obtained, could become a useful tool to optimize the management of resources dedicated to basi...
American Journal of Physiology-Renal Physiology, 1996
The ovarian oocytes from Bufo arenarum (BAO) but not those from Xenopus laevis (XLO) would have w... more The ovarian oocytes from Bufo arenarum (BAO) but not those from Xenopus laevis (XLO) would have water channels (WC). We now report that the injection of the mRNA from BAO into the oocytes from XLO increased their water osmotic permeability (Pi) (reduced by 0.3 mM HgCl2 and reversed by 5 mM beta-mercaptoethanol). A 30-min challenge with progesterone induced, 18 h later, a reduction of the mercury-sensitive fraction of Pf in the BAO (but not in XLO). The mRNA from BAO pretreated with progesterone lost its capacity to induce WC in the XLO, but the hormone did not affect the expression of the WC in XLO previously injected with the mRNA from BAO. Pf was also measured in urinary bladders of BAO. Eighteen hours after a challenge with progesterone, a reduction in the hydrosmotic response to oxytocin was observed. Finally, the mRNA from the urinary bladder of BAO was injected into XLO. An increase in Pf was observed. This was not the case if, before the mRNA extraction, the bladders were tre...
American Journal of Physiology-Renal Physiology, 1996
The ovarian oocytes from Bufo arenarum (BAO) but not those from Xenopus laevis (XLO) would have w... more The ovarian oocytes from Bufo arenarum (BAO) but not those from Xenopus laevis (XLO) would have water channels (WC). We now report that the injection of the mRNA from BAO into the oocytes from XLO increased their water osmotic permeability (Pi) (reduced by 0.3 mM HgCl2 and reversed by 5 mM beta-mercaptoethanol). A 30-min challenge with progesterone induced, 18 h later, a reduction of the mercury-sensitive fraction of Pf in the BAO (but not in XLO). The mRNA from BAO pretreated with progesterone lost its capacity to induce WC in the XLO, but the hormone did not affect the expression of the WC in XLO previously injected with the mRNA from BAO. Pf was also measured in urinary bladders of BAO. Eighteen hours after a challenge with progesterone, a reduction in the hydrosmotic response to oxytocin was observed. Finally, the mRNA from the urinary bladder of BAO was injected into XLO. An increase in Pf was observed. This was not the case if, before the mRNA extraction, the bladders were tre...
Journal of Membrane Biology
Volume changes were studied in Beta vulgaris storage root vacuoles, using video microscopy, when ... more Volume changes were studied in Beta vulgaris storage root vacuoles, using video microscopy, when exposed to hypotonic conditions. The osmotic gradient was either step-applied or progressively imposed in perfusion experiments. Preincubation at low pH (6.6) or with HgCl2 strongly reduced the vacuoles' water permeability, measured in step experiments. Furthermore, the volumetric response depended on the rate with which the aniso-osmotic condition was established. In perfusion experiments a "plateau value" (osmotic equilibrium or steady-state volume value) was observed, which was significantly lower than the theoretically expected one. Furthermore, if vacuoles were preincubated in presence of HgCl2 or at low pH and then the hypo-osmotic challenge was applied in perfusion experiments, a still lower "plateau value" was observed. This reduction was concentration-dependent and completely reversible. In these conditions, when HgCl2 concentration was 300 mM or medium p...
Life Sciences, 1992
Toad bladders sacs were placed inside quartz cuvettes. When fura-2 AM was added to the mucosal co... more Toad bladders sacs were placed inside quartz cuvettes. When fura-2 AM was added to the mucosal compartment, low temperature (4 degrees C) almost completely blocked the transepithelial transfer of fluorescence observed at 20 degrees C (20 degrees C = 371 +/- 56, 4 degrees C = 29 +/- 29 fluorescence intensity in arbitrary units (FIAU), excitation at 340 nm, emission at 510 nm). Simultaneously, fluorescence accumulation inside the tissue was significantly higher (20 degrees C = 25 +/- 5, 4 degrees C = 91 +/- 24% increase on basal levels (%IBL)). When fura-2 AM was added to the serosal side, low temperature also reduced the serosal to mucosal transfer (20 degrees C = 149 +/- 36, 4 degrees C = 61 +/- 35 FIAU). Nevertheless, in this situation tissue accumulation, that was significantly higher that the one observed when fura-2 AM was added to the mucosal side, was reduced at low temperature (20 degrees C = 300 +/- 30, 4 degrees C = 48 +/- 7 %IBL). Spectral analysis of the mucosal and serosal compartments indicated that free fura-2 was transferred from the intracellular to the serosal compartment, but not to the mucosal one. These results indicate that fura-2 appears as a useful tool to evaluate the cellular distribution and traffic of polycyclic charged and non-charged molecules.
Journal of Biochemical and Biophysical Methods, 2005
Membrane water permeability is habitually calculated from volume changes in Xenopus laevis oocyte... more Membrane water permeability is habitually calculated from volume changes in Xenopus laevis oocytes during external osmotic challenges. Nevertheless, this approach is limited by the uncertainty on the oocyte internal composition. To circumvent this limitation a new experimental set up is introduced where the cell membrane of an emptied-out oocyte was mounted as a diaphragm between two chambers. In its final configuration the oocyte membrane was part of a closed compartment and net water movements induced swelling or shrinking of it. Volume changes were followed by videomicroscopy and digitally recorded. In this manner, water movements could be continuously monitored while controlling chemical composition and hydrostatic pressure on both sides of the membrane. Using this novel experimental approach an increasing hydrostatic pressure gradient was applied to both mature (stage VI) and immature (stage IV) oocytes. The relative maximal volume change tolerated before disruption was similar in both cases (1.26 F 0.07 and 1.27 F 0.03 respectively) and similar to those previously reported under maximal osmotic stress. Nevertheless the osmotic permeability coefficient (P OSM) in mature oocytes ((1.72 F 0.58) Â 10 À 3 cm s À 1 ; n = 6) was significantly lower than in immature oocytes ((5.18 F 0.59) Â 10 À 3 cm s À 1 , n = 5; p b 0.005).
Journal of Neuroscience Methods, 2007
Water channels (aquaporins) family members have been identified in central nervous system cells. ... more Water channels (aquaporins) family members have been identified in central nervous system cells. A classic method to measure membrane water permeability and its regulation is to capture and analyse images of Xenopus laevis oocytes expressing them. Laboratories dedicated to the analysis of motion images usually have powerful equipment valued in thousands of dollars. However, some scientists consider that new approaches are needed to reduce costs in scientific labs, especially in developing countries. The objective of this work is to share a very low-cost hardware and software setup based on a well-selected webcam, a hand-made adapter to a microscope and the use of free software to measure membrane water permeability in Xenopus oocytes. One of the main purposes of this setup is to maintain a high level of quality in images obtained at brief intervals (shorter than 70 ms). The presented setup helps to economize without sacrificing image analysis requirements.
Journal of Experimental Botany, 1999
To evaluate the contribution of transcellular, apo-Radial and axial water pathways in plant roots... more To evaluate the contribution of transcellular, apo-Radial and axial water pathways in plant roots are plastic and symplastic pathways to water movements, central elements in the soil-plant-atmosphere continuum horizontal (axial pathway) and vertical (radial pathway) (Newman, 1976; Passioura, 1988). Nevertheless, even sugar beet root (Beta vulgaris L.) slices were studied. when osmotic and hydraulic pressure gradients are at the Volume flows (J v) were measured under hydrostatic origin of water movements (Steudle, 1989, 1997), their and/or osmotic gradients, using a computer-based specific role in each case is not yet clarified. The evaluation data-acquisition system. When tissues were tested of the contribution of the apoplastic versus the protounder hydrostatic gradients (0.3 MPa m−1) a much plasmic pathway has been controversial (Passioura, 1988; more important permeability was observed in the axial Steudle 1989, 1997) and a recent work in parenchyma pathway, as compared with the radial one. Negative potato slices reinforces the role of flux through cell walls, pressure gradients (tensions) were as effective as circumventing the protoplasts, in living tissues (Michael positive ones in inducing a net water movement. After et al., 1997). the establishment of a concentration gradient in the The discovery of proteins that specifically facilitate the radial pathway (obtained by adding 300 M m−3 mannipermeation of water across membranes (water channels tol to the employed solution) an osmotic flux, sensitive or aquaporins, Agre et al., 1993) has reopened the debate to HgCl 2 , was observed. The inhibitory effect of merof the role of the protoplasmic or cell-to-cell routes. curial compounds was reversed by b-mercaptoethanol Water channels have been localized in the tonoplast as while [14C] mannitol unidirectional fluxes were not well as in the plasma membrane of higher plant cells affected by mercurial agents. In the axial pathway, the (Maurel et al., 1993; Chrispeels and Maurel, 1994; Martypresence of a mannitol gradient did not develop a Mazars et al., 1995; Schäffner, 1998). A large group of sustained osmotic flux. After an initial J v in the these family members is reversibly blocked by mercurial expected direction, the J v reversed and moved in the compounds, which facilitates its study. An inhibitory opposite way. It is concluded that, in the sugar beet effect of mercury chloride on water movements in the root, water channels play a significant role in water tomato (Maggio and Joly, 1995) and wheat roots has transfers in the radial pathway. On the other side, been reported (Carvajal et al., 1996). water and solutes are transported by a hydrostatic A computer-based data-acquisition system designed for gradient in the xylem vessels. In general, these results the measurement of net volume fluxes (J v) across bioextend and adapt to a storage root the 'composite logical structures (Dorr et al., 1996) has recently been transport model' first proposed by Steudle et al. developed. The system was employed with success in different animal tissues (
Journal of Biological Physics, 2007
This review focuses on studies of water movement across biological membranes performed over the l... more This review focuses on studies of water movement across biological membranes performed over the last 50 years. Different scientific approaches had tried to elucidate such intriguing mechanism, from hypotheses emphasizing the role of the lipid bilayer to the cloning of aquaporins, the ubiquitous proteins described as specific water channels. Pioneering and clarifying biophysical work are reviewed beside results obtained with the help of recent sophisticated techniques, to conclude that great advances in the subject live together with old questions without definitive answers.
European Biophysics Journal, 2011
This work studies water permeability properties of human aquaporin 1 (hAQP1) expressed in Xenopus... more This work studies water permeability properties of human aquaporin 1 (hAQP1) expressed in Xenopus laevis oocyte membranes, applying a technique where cellular content is replaced with a known medium, with the possibility of measuring intracellular pressure. Consequences on water transport-produced by well-known anisotonic gradients and by the intracellular effect of probable aquaporin inhibitors-were tested. In this way, the specific intracellular inhibition of hAQP1 by the diuretic drug furosemide was demonstrated. In addition, experiments imposing anisotonic mannitol gradients with a constant ionic strength showed that the relationship between water flux and the applied mannitol gradient deflects from a perfect osmometer response when the gradient is higher than 150 mosmol kg W-1. These results would indicate that the passage of water molecules through hAQP1 may have a maximum rate. As a whole, this work demonstrates the technical advantage of controlling both intracellular pressure and medium composition in order to study biophysical properties of hAQP1, and contributes information on water channel behavior under osmotic challenges and the discovery of new inhibitors. Keywords hAQP1 Á Intracellular inhibition Á Furosemide Á Anisotonic gradients Á Xenopus oocytes Electronic supplementary material The online version of this article (