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C Ripoll

Publications and source records attributed to C Ripoll.

At least 19 recordsLinked to original sources
PubMed2006

Relative sensitivity factors of inorganic cations in frozen-hydrated standards in secondary ion MS analysis.

We describe the measurement, at 100 K, of the SIMS relative sensitivity factors (RSFs) of the main physiological cations Na+, K+, Mg2+, and Ca2+ in frozen-hydrated (F-H) ionic solutions. Freezing was performed by either plunge freezing or high-pressure freezing. We also report the measurement of the RSFs in flax fibers, which are a model for ions in the plant cell wall, and in F-H ionic samples, which are a model for ions in the vacuole. RSFs were determined under bombardment with neutral oxygen (FAB) for both the fibers and the F-H samples. We show that referencing to ice-characteristic secondary ions is of little value in determining RSFs and that referencing to K is preferable. The RSFs of Na relative to K and of Ca relative to Mg in F-H samples are similar to their respective values in fiber samples, whereas the RSFs of both Ca and Mg relative to K are lower in fibers than in F-H samples. Our data show that the physical factors important for the determination of the RSFs are not the same in F-H samples and in homogeneous matrixes. Our data show that it is possible to perform a SIMS relative quantification of the cations in frozen-hydrated samples with an accuracy on the order of 15%. Referencing to K permits the quantification of the ionic ratios, even when the absolute concentration of the referencing ion is unknown. This is essential for physiological studies of F-H biological samples.

Journal Article↗
PubMed2006

Increased intrahepatic and circulating levels of endoglin, a TGF-beta1 co-receptor, in patients with chronic hepatitis C virus infection: relationship to histological and serum markers of hepatic fibrosis.

Endoglin, a transforming growth factor (TGF)-beta1 co-receptor, has been associated with renal and cutaneous fibrosis, as overexpression of this protein has been observed in biopsies from patients with glomerulosclerosis and scleroderma, respectively. Our aim was to evaluate whether endoglin may be associated with hepatic fibrosis featuring chronic hepatitis C virus (HCV) infection. Fifty-two anti-HCV+ patients, five anti-HCV- patients and 27 healthy subjects were studied. Western blot and immunohistochemistry were used to quantify the expression levels of endoglin and TGF-beta1 in liver biopsy samples, and serum concentrations of endoglin and hyaluronic acid were determined by enzyme-linked immunosorbent assays (ELISAs). In patients with advanced fibrosis, intrahepatic expression levels of endoglin and TGF-beta1 were significantly higher than those in patients with early fibrosis (mean: 3- and 5.8-fold, respectively) and normal liver (mean: 3.9- and 12-fold, respectively). Interestingly, activated hepatic stellate cells as well as portal and septal myofibroblasts expressed endoglin. Serum levels of endoglin were also significantly higher in patients with advanced fibrosis than in those with early fibrosis (55.5 +/- 1.6 vs 47.5 +/- 0.9 ng/mL, P < 0.001), showing a positive correlation with serum hyaluronic acid concentrations (r = 0.57, P = 0.01). In conclusion, increased intrahepatic endoglin and TGF-beta1 expression is significantly associated with progressive hepatic fibrosis in chronic HCV infection. Circulating endoglin levels are elevated in HCV patients showing a significant correlation with histological and serum markers of hepatic fibrosis. These data suggest an active role for endoglin in the fibrotic process featuring chronic HCV infection.

Adult↗
PubMed2005

Possible interplay between vitamin C deficiency and prolactin in pregnant women with premature rupture of membranes: facts and hypothesis.

The precise etiologic mechanisms involved in the premature rupture of membranes (PROM) during pregnancy, the main cause of preterm delivery worldwide, are unknown. Previous studies have shown that: (a) the rupture of chorioamniotic membranes is related to an imbalance between synthesis and degradation of collagen induced by the overexpression/activity of various matrix metalloproteinases (MMP); (b) during human labor and delivery the expression of prolactin receptors (PRL-R) increases in chorioamniotic membranes, decidua and placenta; (c) prolactin (PRL) can influence the synthesis of prostaglandins, the expression of some MMP (MMP-2, MMP-9 and decysin) and tissue inhibitors of MMP in general; (d) vitamin C deficiency induces the expression/activity of extracellular MMP and is considered a risk factor for PROM; and (e) vitamin C potentiates the dopamine-mediated inhibition of PRL in rats. The present hypothesis proposes that a decreased hypothalamic dopaminergic tone-and thus an increased synthesis/release of pituitary PRL - is induced by vitamin C deficiency below a critical threshold (<18 microg/10(8) leukocytes) and that both factors, in turn, would cause upregulation of the expression/activity of several MMP. The increased PRL concentrations (acting like a Th1-type cytokine) along with the overexpression of other proinflammatory cytokines would induce a premature switch from a favorable Th2-type immune response to a noxious Th1-type immune response in the intrauterine environment. This change, in conjunction with the upregulation of MMP-2 and MMP-9, would cause a premature imbalance between synthesis/degradation of collagen in chorioamniotic membranes (an "anticipation" of the normal parturition cascade?), which favors extracellular matrix degradation, proposed as the most relevant event in the genesis of PROM. This hypothesis represents a new dimension in the study of the etiology of PROM.

Ascorbic Acid Deficiency↗
PubMed2004

A logical (discrete) formulation for the storage and recall of environmental signals in plants.

When subjected to an appropriate asymmetric stimulus, seedlings of Bidens pilosa L. "store" a symmetry-breaking instruction that will finally take effect (in the form of a differential growth of the cotyledonary buds) only if the plants are in a state in which they can "recall" this information. The ability of the plants to recall the stored symmetry-breaking instruction may be switched "on" or "off" by the application of a variety of stimuli. Although its detailed phenomenology is rather complicated, the overall behaviour of the plant storage/recall system can be modelled by use of an asynchronous, logical (discrete) description involving positive and negative feedback circuits, which are required for the existence of multi-stationarity and stability, respectively. The state tables, as used in this formalism, give a concise and easy-to-handle description of the evolution of the system and make it particularly easy to determine its stable states. This modelling approach may be extended to the formulation of many other experimental systems.

Biological Clocks↗
PubMed2004

Safety and efficacy of argon plasma coagulator ablation therapy for flat colorectal adenomas.

INTRODUCTION: argon-plasma coagulation (APC) has been used safely and efficaciously in multiple settings including colon polyp treatment. The aim of this study was to evaluate APC efficacy and safety in the treatment of flat colorectal adenomas. MATERIALS AND METHODS: APC ablation was prospectively performed and evaluated in 22 consecutive patients with colorectal adenomas, 11 of which had large sessile adenomas that were treated with piecemeal polypectomy and APC ablation of residual adenomatous tissue, whereas the remaining eleven patients with flat or carpet-like adenomas were only treated with APC. The mean initial longitudinal extension of adenomas to be treated with APC was 22 mm (range, 20 to 40 mm). RESULTS: the mean age of patients was 70 years. Adenomas were found most frequently in the rectum (50%) and cecum (23%). Complete ablation was achieved in 90.9% of adenomas. Recurrence was observed in 20% of patients, all of them in the rectum, after a mean follow-up period of 16.3 months (range, 8 to 35). All recurrences were managed satisfactorily. No major complications were seen. CONCLUSIONS: argon plasma coagulator ablation of flat colorectal adenomas is an efficacious and safe technique, specially in the right colon, but results must be confirmed in controlled trials with a higher number of patients.

Adenoma↗
PubMed2004

[Esophagic varices].

Explore the source record for details and available documents.

Esophageal and Gastric Varices↗
PubMed2003

Liver transplantation for autoimmune hepatitis: fulminant versus chronic hepatitis presentation.

AIMS: The aim of this study was to analyse long-term outcomes of patients with liver transplantation for autoimmune hepatitis and to determine if fulminant/subfulminant hepatic failure (FSHF) at presentation was a predictor of outcome after ortothopic liver transplantation. PATIENTS AND METHODS: Between April 1990 and October 2002, 18 patients with autoimmune hepatitis underwent 21 liver transplants. Three patients were excluded because of coexisting causes of hepatitis. Seven patients had FSHF and eight patients had chronic disease. The initial immunosuppressive regimen was cyclosporine based in 80%, and all but one patient received steroids or azathioprine. RESULTS: Mean age at time of transplant was 44.2+/-15.5 years. Patients were followed for 38.9+/-29.6 months. Five patients (33.3%) had seven episodes of acute rejection (two steroid-resistant). Three patients developed chronic rejection. One patient displayed histologically proven recurrent autoimmune hepatitis. Actuarial patient and graft survival rates at 1 and 5 years were 80% and 56% and 78.6% and 51%, respectively. No differences in the clinical characteristics of the patients, rates of acute or chronic rejection episodes, end biliary or arterial complications were observed between FSHF and chronic autoimmune hepatitis. The study suggests a better survival for autoimmune FSHF (P=.003). CONCLUSIONS: Liver transplant is indicated for patients displaying autoimmune chronic liver disease and FSHF with similar clinical courses at however, patients with FSHF at presentation had better survivals.

Acute Disease↗
PubMed2002

[Idiopathic cholestasis associated with progressive ductopenia in two patients with hodgkin's disease].

INTRODUCTION: Jaundice in Hodgkin's disease can be due to several causes. Ductal lesions and ductopenia, which we describe below, have rarely been reported. CASE REPORT: We describe 2 cases of idiopathic cholestasis associated with Hodgkin's disease in which duction lesions and ductopenia were found. In one case, the ductal lesion progressed to ductopenia and the patient died from complications of her oncological disease while in the second case, outcome was favorable with improvement of cholestasis and remission of Hodgkin's lymphoma. DISCUSSION: Ductopenia should be included in the differential diagnosis of cholestasis associated with Hodgkin's disease, for which a high degree of suspicion is required. Hodgkin's disease should be suspected when ductopenia is found.

Adult↗
PubMed2000

Engineering pancreatic islets.

Pancreatic islets are neuroendocrine organs that control blood glucose homeostasis. The precise interplay of a heterogeneous group of cell populations (beta, alpha, delta and PP cells) results in the fine-tuned release of counterbalanced hormones (insulin, glucagon, somatostatin and pancreatic polypeptide respectively). Under the premises of detailed knowledge of the physiological basis underlying this behaviour, two lines of investigation might be inferred: generating computational and operational models to explain and predict this behaviour and engineering islet cells to reconstruct pancreatic endocrine function. Whilst the former is being fuelled by new computational strategies, giving biophysicists the possibility of modelling a system in which new "emergent" properties appear, the latter is benefiting from the useful tools and strategic knowledge achieved by molecular, cell and developmental biologists. This includes using tumour cell lines, engineering islet cell precursors, knowledge of the mechanisms of differentiation, regeneration and growth and, finally, therapeutic cloning of human tissues. Gaining deep physiological understanding of the basis governing these processes is instrumental for engineering new pancreatic islets.

Animals↗
PubMed2000

Long-distance transport, storage and recall of morphogenetic information in plants. The existence of a sort of primitive plant 'memory'.

An asymmetrical treatment of Bidens seedlings (pricking one of the seedling cotyledons) causes the cotyledonary buds to grow asymmetrically after release of apical dominance by decapitation of the seedlings. The symmetry-breaking signal propagates within the seedlings at a rate of at least a fraction of a millimetre per second. This information may be 'stored' (STO function) within the seedlings, without taking effect, for at least 2 weeks; then the information may be 'recalled' (RCL function), thus permitting transduction of the signal into the final response (differential growth of the buds), as a consequence of subjecting the seedlings to various symmetrical or asymmetrical treatments. A similar behaviour was observed with stimuli other than pricking (including non-traumatic stimuli), with plants other than Bidens (flax, tomato), and with responses other than cotyledonary-bud growth (hypocotyl elongation, induction of meristems, thigmomorphogenesis). There are indications that storage may involve the activation of elements implicated in cell cycle control, and that the last steps of the final response involve genes such as tch1 and hsp70. The adaptive advantage for plants in possessing STO/RCL functions is discussed. Manipulating the STO/RCL functions may have interesting practical applications, e.g. in the resistance of plants to natural stresses. The existence of the STO/RCL functions in plants constitutes an elementary form of 'memory' which may provide an experimental system simpler than the animal brain to test the validity of the theoretical models of interpretation of important features such as memory storage and evocation.

Environment↗
PubMed2000

Secondary ion mass spectrometry imaging of the fixation of 15N-labelled NO in pollen grains.

We used secondary ion mass spectrometry to image cellular targets of nitrogen oxides (widespread air pollutants) in pollen grains of birch (Betula verrucosa Ehrh.) and cockfoot (Dactylis glomerata L.). The pollen samples were exposed to air supplemented with high doses of 15NO. The pollen grains were then fixed, dehydrated using a newly developed 'vapour phase' preparation method and embedded in LRW resin. Semithin sections were then analysed. Imaging was performed in scanning mode. As usual, the two isotopes 14N and 15N were imaged as 12C14N- and 12C15N-, respectively. The isotopic percentages of 15N were quantitatively determined either by image processing or by direct analysis. We show that the preferential areas of NO fixation in the pollen cell are the sporoderm and discrete intracytoplasmic structures that we tentatively describe as globoid-like structures similar to those encountered in seeds.

Air Pollutants↗
PubMed2000

[Regenerative potential in the organ of Corti after otic intoxication].

The auditory sensory cells are sensitive to a variety of influences such as noise, ototoxic drugs and aging. In the cochlea of mammals, the destroyed sensory cells are not replaced by new sensory cells. That leads to cochlear deafness, a frequent disease in human. Unfortunately, such auditory impairment is out of reach of treatment. The development of new therapeutic strategies in this field requires a precise knowledge of the mechanisms involved in auditory sensory cells disappearance and in organ of Corti's degeneration. The aim of our study was to characterize cellular and molecular changes in the cochlea of rats which had been intoxicated with the ototoxic antibiotic amikacin. The animals were sacrificed at different survival times during and after the antibiotic treatment and their cochleas were investigated using transmission and scanning electron microscopy and using confocal microscopy after tissue labellings with different fluorescent probes. The results revealed the existence of three periods. The first one corresponds to the disappearance of the sensory cells which die by apoptosis. During the second period, the organ of Corti undergoes a scarring process; concomitantly, a contingent of nonsensory supporting cells attempts to transdifferentiate directly into sensory cells. This process however fails, and the supporting cells never reach the status of hair cells. A general process of dedifferentiation of all the epithelial cells of the organ of Corti followed by a massive apoptosis of numerous epithelial cells and of most ganglion cells occurs during the third period. After that, the organ of Corti is definitely reduced to a simple monolayered epithelium. On the basis of these data, experimental strategies aimed i) to protect the sensory cells against apoptosis and ii) to promote sensory cell regeneration are now under study. They might have important implications in human therapy.

Amikacin↗
PubMed1999

Non-genomic actions of 17beta-oestradiol in mouse pancreatic beta-cells are mediated by a cGMP-dependent protein kinase.

1. Intracellular calcium concentration ([Ca2+]i) was measured in mouse whole islets of Langerhans using the calcium-sensitive fluorescent dye Indo-1. 2. Application of physiological concentrations of 17beta-oestradiol in the presence of a stimulatory glucose concentration (8 mM) potentiated the [Ca2+]i signal in 83 % of islets tested. Potentiation was manifested as either an increase in the frequency or duration of [Ca2+]i oscillations. 3. The effects caused by 17beta-oestradiol were mimicked by the cyclic nucleotide analogues 8-bromoguanosine-3',5'-cyclic monophosphate (8-Br-cGMP) and 8-bromoadenosine-3',5'-cyclic monophosphate (8-Br-cAMP). 4. Direct measurements of both cyclic nucleotides demonstrated that nanomolar concentrations of 17beta-oestradiol in the presence of 8 mM glucose increased cGMP levels, yet cAMP levels were unchanged. The increment in cGMP was similar to that induced by 11 mM glucose. 5. Patch-clamp recording in intact cells showed that 8-Br-cGMP reproduced the inhibitory action of 17beta-oestradiol on ATP-sensitive K+ (KATP) channel activity. This was not a membrane-bound effect since it could not be observed in excised patches. 6. The action of 17beta-oestradiol on KATP channel activity was not modified by the specific inhibitor of soluble guanylate cyclase (sGC) LY 83583. This result indicates a likely involvement of a membrane guanylate cyclase (mGC). 7. The rapid decrease in KATP channel activity elicited by 17beta-oestradiol was greatly reduced using Rp-8-pCPT-cGMPS, a specific blocker of cGMP-dependent protein kinase (PKG). Conversely, Rp-cAMPS, which inhibits cAMP-dependent protein kinase (PKA), had little effect. 8. The results presented here indicate that rapid, non-genomic effects of 17beta-oestradiol after interaction with its binding site at the plasma membrane of pancreatic beta-cells is a cGMP-dependent phosphorylation process.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1999

Expression pattern of mammalian cochlea outer hair cell (OHC) mRNA: screening of a rat OHC cDNA library.

The aim of this study was to characterize the mRNA content of mammalian cochlear outer hair cells (OHCs) and to search for specific genes possibly involved in their unique properties. Indeed, OHCs, which feature high-frequency electromotility, are responsible for the exquisite sensitivity and frequency selectivity of the cochlea. Damage to these cells, which occurs in various conditions, causes a reduction in the cochlear sensitivity by about 50 dB and the alteration of frequency discrimination. Total RNA was extracted from about 2000 mechanically dissociated OHCs, and a polymerase chain reaction (PCR) amplified cDNA library was constructed. The presence of the alpha-9 acetylcholine receptor subunit, preferentially expressed in OHCs, was found by direct PCR amplification of the library. A systematic sequencing of 218 clones showed 78% known genes, 11% EST-related sequences, and 11% unknown genes. The known-gene group was characterized by two main features: a large proportion (55%) of mitochondrial transcripts and an abundance in calcium-binding proteins, such as calmodulin and calbindin, for which expression has already been demonstrated in OHCs. Another protein, the oncomodulin recently shown to be OHC specific, was also found, and its mRNA expression was confirmed by in situ hybridization. Among the 24 unknown genes, 7 were expressed in a restricted pattern, including one expressed in cochlea and spleen and, to a lesser extent, in lungs.

Animals↗
PubMed1999

Mechanisms of glucose hypersensitivity in beta-cells from normoglycemic, partially pancreatectomized mice.

Increased beta-cell sensitivity to glucose precedes the loss of glucose-induced insulin secretion in diabetic animals. Changes at the level of beta-cell glucose sensor have been described in these situations, but it is not clear whether they fully account for the increased insulin secretion. Using a euglycemic-normolipidemic 60% pancreatectomized (60%-Px) mouse model, we have studied the ionic mechanisms responsible for increased beta-cell glucose sensitivity. Two weeks after Px (Px14 group), Px mice maintained normoglycemia with a reduced beta-cell mass (0.88 +/- 0.18 mg) compared with control mice (1.41 +/- 0.21 mg). At this stage, the dose-response curve for glucose-induced insulin release showed a significant displacement to the left (P < 0.001). Islets from the Px14 group showed oscillatory electrical activity and cytosolic Ca2+ ([Ca2+]i) oscillations in response to glucose concentrations of 5.6 mmol/l compared with islets from the control group at 11.1 mmol/l. All the above changes were fully reversible both in vitro (after 48-h culture of islets from the Px14 group) and in vivo (after regeneration of beta-cell mass in islets studied 60 days after Px). No significant differences in the input resistance and ATP inhibition of ATP-sensitive K+ (K(ATP)) channels were found between beta-cells from the Px14 and control groups. The dose-response curve for glucose-induced MTT (C,N-diphenyl-N''-4,5-dimethyl thiazol 2 yl tetrazolium bromide) reduction showed a significant displacement to the left in islets from the Px14 group (P < 0.001). These results indicate that increased glucose sensitivity in terms of insulin secretion and Ca2+ signaling was not due to intrinsic modifications of K(ATP) channel properties, and suggest that the changes are most likely to be found in the glucose metabolism.

Adenosine Triphosphate↗
PubMed1999

[Flow cytometry and pathology AFC-089. Fluorescence recovery after photobleaching: principle and applications. An example: research of gap junctions between immature sensory cells of the cochlea].

In image cytometry, fluorescence recovery after photobleaching (FRAP) is wildly used to study molecular displacements at tissular, cellular or infracellular levels. The principle and the main applications of FRAP are presented. An example is given: the investigation of functional communications between cochlea's immature sensory cells.

Cochlea↗