Maria Geada - Academia.edu (original) (raw)
Papers by Maria Geada
Springer eBooks, 1997
This study investigates the effect of 10 pM cholecystokinin-octapeptide (CCK-8) on intracellular ... more This study investigates the effect of 10 pM cholecystokinin-octapeptide (CCK-8) on intracellular free magnesium [Mg2+h and calcium concentrations [Ca 2 +h in magfura-2-AM and fura-2-AM loaded single pancreatic acinar cells, respectively employing the technique of microspectrofluorimetry. CCK-8 evoked an initial sharp rise in [Mg2+h (Mg2+ release) followed by a decrease to a new steady-state level (Mg2+ efflux). On removal of CCK-8 [Mg2+h returned to the pre-stimulated basal level (Mg2+ reuptake). In contrast, CCK-8 gave rise to Ca 2 + oscillations. When acinar cells were co-loaded with BAPTA (10 JlM) and either magfura-2-AM or fura-2-AM, CCK-8 evoked only the normal decrease in [Mg2+]~ and a slight [Ca 2 +h elevation (10 nM). This results suggest that the initial rise in [Mg +h seen with CCK-8 in normal conditions may be due to Ca 2 + interfering with the magfura-2-AM signal. Both thapsigargin (0.5 JlM) and ionomycin (5 JlM) evoked a marked decrease in [Mg2+h in magfura-2-AM loaded acinar cells and an elevation in [Ca 2 +h from fura-2-AM loaded acinar cells. The results indicate that cytosolic Ca 2 + is associated with secretagogue-induced decrease in [Mg2+]j. When acinar cells were pre-treated with either forskolin (10 JlM), N,wNitro-Larginine (N-LA; 2 mM), 8-Bromo guanosine cyclic mono-phosphate (8 Br. Cyclic GMP; 100 JlM) or staurosporine (1 JlM), CCK-8 elicited only a small decrease in [Mg2+h compared to a much larger response with CCK-8 alone. In contrast, genestein (10 JlM) and 12-0-tetradeconyl phorbol l3-<1 acetate (TPA; 1 JlM) augmented the decrease in [Mg2+h evoked by CCK-8. The results indicate that Ca 2 + mobilising secretagogues can stimulate Mg2+ efflux which is also mediated by a number of intracellular mediators.
Journal of General Virology, Nov 1, 2001
Vaccinia virus produces several forms of infectious virions. Intracellular mature virions (IMV) a... more Vaccinia virus produces several forms of infectious virions. Intracellular mature virions (IMV) assemble in areas close to the cell nucleus. Some IMV acquire an envelope from intracellular membranes derived from the trans-Golgi network, producing enveloped forms found in the cytosol (intracellular enveloped virus ; IEV), on the cell surface (cell-associated enveloped virus) or free in the medium (extracellular enveloped virus ; EEV). Blockage of IMV envelopment inhibits transport of virions to the cell surface, indicating that enveloped virus forms are required for virion movement from the Golgi area. To date, the induction of actin tails that propel IEV is the only wellcharacterized mechanism for enveloped virus transport. However, enveloped virus transport and release occur under conditions where actin tails are not formed. In order to study these events, recombinant vaccinia viruses were constructed with GFP fused to the most abundant protein in the EEV envelope, P37 (F13L). The P37-GFP fusion, like normal P37, accumulated in the Golgi area and was incorporated efficiently into enveloped virions. These recombinants allowed the monitoring of enveloped virus movements in vivo. In addition to a variety of relatively slow movements (0n4 µm/s), faster, saltatory movements both towards and away from the Golgi area were observed. These movements were different from those dependent on actin tails and were inhibited by the microtubule-disrupting drug nocodazole, but not by the myosin inhibitor 2,3butanedione monoxime. Video microscopy (5 frames per s) revealed that saltatory movements had speeds of up to, and occasionally more than, 3 µm/s. These results suggest that a second, microtubule-dependent mechanism exists for intracellular transport of enveloped vaccinia virions.
Springer eBooks, 1997
... MOOREN1, MARIA MORENO GEADA2, JAIPAUL SINGH2, WOLFGANG BEIL3 AND WOLFRAM DOMSCHKE1 I Departme... more ... MOOREN1, MARIA MORENO GEADA2, JAIPAUL SINGH2, WOLFGANG BEIL3 AND WOLFRAM DOMSCHKE1 I Department of Medicine B, Westfalische Wilhelms-Universitat, Munster, Germany,^ Department of Applied Biology ... 29 T. Theophanides and J. Anastassopoulou (eds ...
Biochimica et biophysica acta. Molecular cell research, Oct 11, 1997
Žw 2q x. In the present study, the effects of extracellular magnesium concentration Mg on stimulu... more Žw 2q x. In the present study, the effects of extracellular magnesium concentration Mg on stimulus-secretion coupling ex Ž. processes were investigated in rat gastric parietal cells in vitro. Extracellular magnesium reduction resulted in 1 an Žw 2q x. Ž. increase of basal intracellular free calcium concentration Ca , 2 an enhancement of both carbachol and in Ž. Ž. thapsigargin-induced calcium responses, 3 an improved filling state of intracellular calcium stores, 4 an increase of both X X Ž. basal and carbachol-induced acid secretion, whereas intracellular adenosine 3 ,5-cyclic monophosphate cyclicAMP levels w 2q x and histamine stimulated acid secretion were not affected. The effects of high Mg were opposite to the described ex w 2q x results, except that high Mg was able to decrease significantly histamine-stimulated cyclicAMP levels and acid ex w 2q x secretion. These findings indicate a modulatory role of Mg on the intracellular signalling processes and acid secretory ex Ž. properties in rat parietal cells. These effects seemed to be mediated by regulating 1 calcium loading capacity of Ž. Ž. intracellular stores, 2 the permeability of the calcium influx pathway, and 3 the formation of cyclicAMP. q 1997 Elsevier Science B.V.
Journal of General Virology, 2001
Vaccinia virus produces several forms of infectious virions. Intracellular mature virions (IMV) a... more Vaccinia virus produces several forms of infectious virions. Intracellular mature virions (IMV) assemble in areas close to the cell nucleus. Some IMV acquire an envelope from intracellular membranes derived from the trans-Golgi network, producing enveloped forms found in the cytosol (intracellular enveloped virus; IEV), on the cell surface (cell-associated enveloped virus) or free in the medium (extracellular enveloped virus; EEV). Blockage of IMV envelopment inhibits transport of virions to the cell surface, indicating that enveloped virus forms are required for virion movement from the Golgi area. To date, the induction of actin tails that propel IEV is the only well-characterized mechanism for enveloped virus transport. However, enveloped virus transport and release occur under conditions where actin tails are not formed. In order to study these events, recombinant vaccinia viruses were constructed with GFP fused to the most abundant protein in the EEV envelope, P37 (F13L). The P...
Magnesium: Current Status and New Developments, 1997
... MOOREN1, MARIA MORENO GEADA2, JAIPAUL SINGH2, WOLFGANG BEIL3 AND WOLFRAM DOMSCHKE1 I Departme... more ... MOOREN1, MARIA MORENO GEADA2, JAIPAUL SINGH2, WOLFGANG BEIL3 AND WOLFRAM DOMSCHKE1 I Department of Medicine B, Westfalische Wilhelms-Universitat, Munster, Germany,^ Department of Applied Biology ... 29 T. Theophanides and J. Anastassopoulou (eds ...
Biochimica et Biophysica Acta (BBA) - Molecular Cell Research, 1997
Gastrointestinal secretions are controlled mainly by the gut hormones and by the neurotransmitter... more Gastrointestinal secretions are controlled mainly by the gut hormones and by the neurotransmitters released by the autonomic nervous system. The hormones and neurotransmitters (secretagogues) utilise different intracellular mediators to elicit enzyme and fluid secretion. One particular mediator is the second messenger calcium (Ca2+) and there is now much evidence that the abundant divalent cation magnesium (Mg 25 may play an important physiological role in regulating the mobilisation of cellular Ca 2t Thus, the present study was designed to investigate (a) the effect of a modification of extracellular Mg2 on secretagogue-evoked enzyme and hydrochloric acid (HCI) secretion and Ca 2 homeostasis in the pancreatic acinar cells and parietal cells and (b) to characterise the molecular mechanism of Mg 2 transport using fluorimetric and spectroscopic studies. The results have shown that application of either cholecystokinin-octapeptide (CCK-8) or acetylcholine (ACh) to rat pancreatic segmen...
Magnesium: Current Status and New Developments, 1997
Springer eBooks, 1997
This study investigates the effect of 10 pM cholecystokinin-octapeptide (CCK-8) on intracellular ... more This study investigates the effect of 10 pM cholecystokinin-octapeptide (CCK-8) on intracellular free magnesium [Mg2+h and calcium concentrations [Ca 2 +h in magfura-2-AM and fura-2-AM loaded single pancreatic acinar cells, respectively employing the technique of microspectrofluorimetry. CCK-8 evoked an initial sharp rise in [Mg2+h (Mg2+ release) followed by a decrease to a new steady-state level (Mg2+ efflux). On removal of CCK-8 [Mg2+h returned to the pre-stimulated basal level (Mg2+ reuptake). In contrast, CCK-8 gave rise to Ca 2 + oscillations. When acinar cells were co-loaded with BAPTA (10 JlM) and either magfura-2-AM or fura-2-AM, CCK-8 evoked only the normal decrease in [Mg2+]~ and a slight [Ca 2 +h elevation (10 nM). This results suggest that the initial rise in [Mg +h seen with CCK-8 in normal conditions may be due to Ca 2 + interfering with the magfura-2-AM signal. Both thapsigargin (0.5 JlM) and ionomycin (5 JlM) evoked a marked decrease in [Mg2+h in magfura-2-AM loaded acinar cells and an elevation in [Ca 2 +h from fura-2-AM loaded acinar cells. The results indicate that cytosolic Ca 2 + is associated with secretagogue-induced decrease in [Mg2+]j. When acinar cells were pre-treated with either forskolin (10 JlM), N,wNitro-Larginine (N-LA; 2 mM), 8-Bromo guanosine cyclic mono-phosphate (8 Br. Cyclic GMP; 100 JlM) or staurosporine (1 JlM), CCK-8 elicited only a small decrease in [Mg2+h compared to a much larger response with CCK-8 alone. In contrast, genestein (10 JlM) and 12-0-tetradeconyl phorbol l3-<1 acetate (TPA; 1 JlM) augmented the decrease in [Mg2+h evoked by CCK-8. The results indicate that Ca 2 + mobilising secretagogues can stimulate Mg2+ efflux which is also mediated by a number of intracellular mediators.
Journal of General Virology, Nov 1, 2001
Vaccinia virus produces several forms of infectious virions. Intracellular mature virions (IMV) a... more Vaccinia virus produces several forms of infectious virions. Intracellular mature virions (IMV) assemble in areas close to the cell nucleus. Some IMV acquire an envelope from intracellular membranes derived from the trans-Golgi network, producing enveloped forms found in the cytosol (intracellular enveloped virus ; IEV), on the cell surface (cell-associated enveloped virus) or free in the medium (extracellular enveloped virus ; EEV). Blockage of IMV envelopment inhibits transport of virions to the cell surface, indicating that enveloped virus forms are required for virion movement from the Golgi area. To date, the induction of actin tails that propel IEV is the only wellcharacterized mechanism for enveloped virus transport. However, enveloped virus transport and release occur under conditions where actin tails are not formed. In order to study these events, recombinant vaccinia viruses were constructed with GFP fused to the most abundant protein in the EEV envelope, P37 (F13L). The P37-GFP fusion, like normal P37, accumulated in the Golgi area and was incorporated efficiently into enveloped virions. These recombinants allowed the monitoring of enveloped virus movements in vivo. In addition to a variety of relatively slow movements (0n4 µm/s), faster, saltatory movements both towards and away from the Golgi area were observed. These movements were different from those dependent on actin tails and were inhibited by the microtubule-disrupting drug nocodazole, but not by the myosin inhibitor 2,3butanedione monoxime. Video microscopy (5 frames per s) revealed that saltatory movements had speeds of up to, and occasionally more than, 3 µm/s. These results suggest that a second, microtubule-dependent mechanism exists for intracellular transport of enveloped vaccinia virions.
Springer eBooks, 1997
... MOOREN1, MARIA MORENO GEADA2, JAIPAUL SINGH2, WOLFGANG BEIL3 AND WOLFRAM DOMSCHKE1 I Departme... more ... MOOREN1, MARIA MORENO GEADA2, JAIPAUL SINGH2, WOLFGANG BEIL3 AND WOLFRAM DOMSCHKE1 I Department of Medicine B, Westfalische Wilhelms-Universitat, Munster, Germany,^ Department of Applied Biology ... 29 T. Theophanides and J. Anastassopoulou (eds ...
Biochimica et biophysica acta. Molecular cell research, Oct 11, 1997
Žw 2q x. In the present study, the effects of extracellular magnesium concentration Mg on stimulu... more Žw 2q x. In the present study, the effects of extracellular magnesium concentration Mg on stimulus-secretion coupling ex Ž. processes were investigated in rat gastric parietal cells in vitro. Extracellular magnesium reduction resulted in 1 an Žw 2q x. Ž. increase of basal intracellular free calcium concentration Ca , 2 an enhancement of both carbachol and in Ž. Ž. thapsigargin-induced calcium responses, 3 an improved filling state of intracellular calcium stores, 4 an increase of both X X Ž. basal and carbachol-induced acid secretion, whereas intracellular adenosine 3 ,5-cyclic monophosphate cyclicAMP levels w 2q x and histamine stimulated acid secretion were not affected. The effects of high Mg were opposite to the described ex w 2q x results, except that high Mg was able to decrease significantly histamine-stimulated cyclicAMP levels and acid ex w 2q x secretion. These findings indicate a modulatory role of Mg on the intracellular signalling processes and acid secretory ex Ž. properties in rat parietal cells. These effects seemed to be mediated by regulating 1 calcium loading capacity of Ž. Ž. intracellular stores, 2 the permeability of the calcium influx pathway, and 3 the formation of cyclicAMP. q 1997 Elsevier Science B.V.
Journal of General Virology, 2001
Vaccinia virus produces several forms of infectious virions. Intracellular mature virions (IMV) a... more Vaccinia virus produces several forms of infectious virions. Intracellular mature virions (IMV) assemble in areas close to the cell nucleus. Some IMV acquire an envelope from intracellular membranes derived from the trans-Golgi network, producing enveloped forms found in the cytosol (intracellular enveloped virus; IEV), on the cell surface (cell-associated enveloped virus) or free in the medium (extracellular enveloped virus; EEV). Blockage of IMV envelopment inhibits transport of virions to the cell surface, indicating that enveloped virus forms are required for virion movement from the Golgi area. To date, the induction of actin tails that propel IEV is the only well-characterized mechanism for enveloped virus transport. However, enveloped virus transport and release occur under conditions where actin tails are not formed. In order to study these events, recombinant vaccinia viruses were constructed with GFP fused to the most abundant protein in the EEV envelope, P37 (F13L). The P...
Magnesium: Current Status and New Developments, 1997
... MOOREN1, MARIA MORENO GEADA2, JAIPAUL SINGH2, WOLFGANG BEIL3 AND WOLFRAM DOMSCHKE1 I Departme... more ... MOOREN1, MARIA MORENO GEADA2, JAIPAUL SINGH2, WOLFGANG BEIL3 AND WOLFRAM DOMSCHKE1 I Department of Medicine B, Westfalische Wilhelms-Universitat, Munster, Germany,^ Department of Applied Biology ... 29 T. Theophanides and J. Anastassopoulou (eds ...
Biochimica et Biophysica Acta (BBA) - Molecular Cell Research, 1997
Gastrointestinal secretions are controlled mainly by the gut hormones and by the neurotransmitter... more Gastrointestinal secretions are controlled mainly by the gut hormones and by the neurotransmitters released by the autonomic nervous system. The hormones and neurotransmitters (secretagogues) utilise different intracellular mediators to elicit enzyme and fluid secretion. One particular mediator is the second messenger calcium (Ca2+) and there is now much evidence that the abundant divalent cation magnesium (Mg 25 may play an important physiological role in regulating the mobilisation of cellular Ca 2t Thus, the present study was designed to investigate (a) the effect of a modification of extracellular Mg2 on secretagogue-evoked enzyme and hydrochloric acid (HCI) secretion and Ca 2 homeostasis in the pancreatic acinar cells and parietal cells and (b) to characterise the molecular mechanism of Mg 2 transport using fluorimetric and spectroscopic studies. The results have shown that application of either cholecystokinin-octapeptide (CCK-8) or acetylcholine (ACh) to rat pancreatic segmen...
Magnesium: Current Status and New Developments, 1997