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Biomedical subjects

A Marie

Publications and source records attributed to A Marie.

At least 19 recordsLinked to original sources
PubMed2005

Proteomic study of Galectin-1 expression in human mesenchymal stem cells.

Bone marrow-derived mesenchymal stem cells (MSCs) are known to interact with hematopoietic stem cells (HSCs) and immune cells, and are of potential interest to be used as therapeutic agents for enhancing allogenic hematopoietic engraftment and preventing graft-versus-host disease (GVHD). Galectin 1 (Gal1) belongs to a family of structurally related molecules expressed in many vertebrate tissues that exert their functions both by binding to glycoconjugates, and by interaction with protein partners. In this work using a proteomic approach, we looked for the presence and the localization of Gal1 in short- and long-term culture of human (h) hMSC. We first determined, that Gal1 is one of the major proteins expressed in hMSC. We futher demonstrated that its expression is maintained when hMSC are expanded through a subculturing process up to five passages. Moreover, Gal1 is secreted and found at the cell surface of MSC, participating in extra cellular matrix (ECM)-cell interactions. Given the immunomodulatory properties of Gal1, its potential involvement in immunological functions of hMSC could be suggested.

Amino Acid Sequence↗
PubMed2003

Fluorinated matrix approach for the characterization of hydrophobic perfluoropolyethers by matrix-assisted laser desorption/ionization time-of-flight MS.

Characterization of fluorinated polymers in MALDI is often unsuccessful because commonly used matrixes, such as 2,5-dihydroxybenzoic acid, Indole acrylic acid, alpha-cyano-4-hydroxycinnamic acid, etc., do not desorb/ionize fluorinated polymers efficiently. This could be in part attributed to the unfavorable interaction between the matrix molecules and fluorinated oligomers due to differences in their hydrophobicities. Moreover, the relative cation affinity between the matrix molecules and the fluorinated oligomers may not favor the gas-phase cationization process of the fluorinated oligomers. To overcome these limitations, fluorinated derivates of benzoic acid (pentafluorobenzoic acid) and cinnamic acid (Pentafluoro cinnamic acid) were employed for the desorption/ionization of perfluoropolyethers. Presence of fluorine atoms in the matrix might improve the interaction between the matrix and perfluoroether during the crystallization or ionization step. With a pentafluorobenzoic acid matrix, intact silver cationized oligomers were desorbed, whereas with a pentafluorocinnamic acid matrix, loss of end group was observed. This loss could be rationalized by the dissociation of the silver cationized oligomers via an ion-dipole mechanism. This work shows the possibility of characterizing yet another important class of fluorinated polymer by MALDI-TOFMS.

Journal Article↗
PubMed2002

Collision-induced dissociation studies of poly(vinylidene) fluoride telomers in an electrospray-ion trap mass spectrometer.

Although fluorinated polymers are widely used in different applications, they are rarely investigated by "soft ionization" techniques such as matrix-assisted laser desorption/ionization and electrospray ionization (ESI). We report here, the desorption and fragmentation of poly(vinylidene) fluoride (PVDF) telomers in an ion trap mass spectrometer coupled to an ESI source. Protonated and lithiated telomers under collision-induced dissociation resonant excitation show mainly HF losses. Fragmentation of protonated telomers can be rationalized by a double proton-transfer mechanism and that of lithiated and anionic telomers by an ion-dipole mechanism. Both mechanisms predict the formation of a stable aromatic or a linear conjugated species, respectively. For lithiated telomers, we could determine the degree of polymerization (n) from the product ion abundance in MS2 experiments. The nature of the end group plays a substantial role in orienting the fragmentation of the PVDF ions. It is interesting to note that, in MS2 experiments, Li+ and F- act as catalysts in the fragmentation of PVDF telomers. Fragmentation of the PVDF telomer backbone was not observed under any experimental conditions.

Journal Article↗
PubMed2002

Post-source decay time-of-flight study of fragmentation mechanisms of protonated synthetic polymers under matrix-assisted laser desorption/ionization conditions.

Post-source decay (PSD) of three different nylon oligomers desorbed under matrix-assisted laser desorption/ionization (MALDI) conditions was studied and their fragmentation pathways were investigated. The fragmentation of the protonated oligomers is very similar to that of peptides. The b(n)(+), y(n)(+) and z(n)(+) series of ions were observed in abundance in the PSD spectrum. The end groups and the length of the spacer in the repeating unit influence the fragmentation of the different polyamides and the relative abundances of the product ions. Competitive dehydration and deamination reactions were observed, and depend on the nature of the end groups and the repeating units. The PSD spectra are very similar to collision-induced dissociation (CID) spectra obtained under low-energy conditions, implying that the selected precursor ions possess similar average internal energies. All the peaks observed in the PSD spectrum can be rationalized by reasonable fragmentation mechanisms.

Journal Article↗
PubMed2001

The mere exposure effect in patients with schizophrenia.

The mere exposure effect refers to the development of an emotional preference for previously unfamiliar material because of frequent exposure to that material. This study compared schizophrenia subjects (n = 20) to normal controls (n = 21) to determine whether implicit memory, as demonstrated by the mere exposure effect, was intact. Patients with schizophrenia demonstrated a normal preference for both verbal and visual materials seen earlier relative to novel materials, despite impaired performance on a recognition task for explicit memory using similar materials. Previous studies of schizophrenia subjects have shown a dissociation between implicit and explicit memory on verbal tasks. We found a similar dissociation demonstrated by normal functioning on an implicit memory task and impaired functioning on an explicit memory task. Potential implications of these findings are discussed with regard to treatment and rehabilitation.

Adult↗
PubMed2000

Characterization of synthetic polymers by MALDI-TOF/MS: investigation into new methods of sample target preparation and consequence on mass spectrum finger print

Characterization of synthetic polymers by Matrix assisted laser desorption (MALDI) is limited by the solubility of different oligomers in a suitable solvent, and the fingerprint of the mass spectrum is affected by the properties of solvents employed (eg., pH, secondary solvents, evaporation) during sample target preparation. If solvents are not used during sample target preparation, then solvent properties should not play an important role in determining the quality of the MALDI mass spectrum. We report here two solventless approaches for sample target preparation. It was observed that Poly(ethylene glycol) 6000 (PEG) showed the same molecular mass distribution in different modes of sample target preparation. Fluorinated polymer used in these studies was affected by sample target preparation protocol and by target surface. Pyrolysis of PEG oligomers was observed in all the methods of sample target preparation. The desorbed high mass neutral oligomers fragment to give small oligomers which are then cationized by the desolvation of the cationized matrix clusters. Moreover, the origin of the matrix clusters (i.e., formed in the condensed phase or in the gas phase) determines the relative intensities of PEG oligomers cationized by sodium or potassium.

Journal Article↗
PubMed2000

Cancer risk and mortality in users of calcium channel blockers. A cohort study.

BACKGROUND: Data regarding the association between the use of calcium channel blockers and cancer risk have been conflicting. In the current study, the authors examined the cancer risk and mortality in users of calcium channel blockers in North Jutland County, Denmark. METHODS: The authors conducted a cohort study using record linkage between a population-based prescription database, the Danish Cancer Registry, and the Danish Death Registry including 23, 167 users of calcium channel blockers who received >/=2 prescriptions between January 1, 1989 and December 31, 1995. The authors calculated the standardized incidence ratios and standard mortality ratios for cancer, along with corresponding 95% confidence intervals (95% CI). RESULTS: Overall, 967 incident cases of cancer occurred, resulting in a standardized incidence ratio of 1.04 (95% CI, 0.98-1.11). There was a slightly elevated nonsignificant risk of tobacco-related cancer. No increased risk of breast or colon carcinoma was observed. The cancer mortality was close to that expected in the background population (standardized mortality ratio of 0.97; 95% CI, 0.89-1.04). CONCLUSIONS: This large-scale, population-based cohort study adds to the increasing evidence indicating no substantial association between the use of calcium channel blockers and the incidence rate of cancer or cancer mortality.

Adolescent↗
PubMed2000

Complementary and alternative medicine use among elderly persons: one-year analysis of a Blue Shield Medicare supplement.

BACKGROUND: Large scale surveys in the United States and abroad suggest that 35-60% of adults have used some form of complementary/alternative medicine (CAM). However, no studies to date have focused on predictors and patterns of CAM use among elderly persons. METHODS: The population surveyed were Californians enrolled in a Medicare risk product that offers coverage for acupuncture and chiropractic care. Surveys were mailed to 1597 members in 1997 and responses received by 728 (51% response rate). Health risk assessment data were also obtained at baseline and 12-15 months following enrollment in the plan. Multiple logistic regression analyses were carried out to examine predictors of CAM use. RESULTS: Forty-one percent of seniors reported use of CAM. Herbs (24%), chiropractic (20%), massage (15%), and acupuncture (14%) were the most frequently cited therapies. CAM users tended to be younger, more educated, report either arthritis and/or depression/anxiety, not be hypertensive, engage in exercise, practice meditation, and make more frequent physician visits. Use of CAM was not associated with any observed changes in health status. Respondents also expressed considerable interest in receiving third-party coverage for CAM. Although 80% reported that they had received substantial benefit from their use of CAM, the majority (58%) did not discuss the use of these therapies with their medical doctor. CONCLUSIONS: Findings suggest that there is significant interest in and use of complementary/alternative medicine among elderly persons. These results suggest the importance of further research into the use and potential efficacy of these therapies within the senior population.

Aged↗
PubMed1999

A new class of proteins capable of binding transition metals.

Ion uptake, transport, and sequestration are essential to meet the nutritional requirements for plant growth and development. Furthermore, regulation of these processes is critical for plants to tolerate toxic levels of ions. The examination of isoprenylated proteins encoded by Arabidopsis thaliana and Glycine max cDNAs revealed a unique family of proteins containing putative metal-binding motifs (the core sequence is M/LXCXXC). Here, we describe this new class of proteins, which are capable of being isoprenylated and binding transition metal ions. Members of this family contain consensus isoprenylation (CaaX) sites, which we demonstrate are efficiently isoprenylated in vitro. ATFP3, a representative of the Arabidopsis family, was expressed in Escherichia coli and examined for metal-binding activity in vitro. Analysis of the interaction of ATFP3 with metal-chelating columns (IMAC) suggested that it binds to Cu2+, Ni2+, or Zn2+. To test whether proteins with these characteristics are present in other plant species, tobacco BY2 cells were labeled in vivo with [14C]mevalonate and the resulting mevalonate-labeled proteins were tested for metal-binding activity. Several soluble, isoprenylated proteins which bound copper-IMAC columns were revealed. Consistent with a wide-spread distribution of these proteins in plants, their presence was observed in Arabidopsis, soybean, and tobacco.

Amino Acid Sequence↗
PubMed1998

A review of the incorporation of complementary and alternative medicine by mainstream physicians.

BACKGROUND: Studies suggest that between 30% and 50% of the adult population in industrialized nations use some form of complementary and/or alternative medicine (CAM) to prevent or treat a variety of health-related problems. METHOD: A comprehensive literature search identified 25 surveys conducted between 1982 and 1995 that examined the practices and beliefs of conventional physicians with regard to 5 of the more prominent CAM therapies: acupuncture, chiropractic, homeopathy, herbal medicine, and massage. Six studies were excluded owing to their methodological limitations. RESULTS: Across surveys, acupuncture had the highest rate of physician referral (43%) among the 5 CAM therapies, followed by chiropractic (40%) and massage (21%). Rates of CAM practice by conventional physicians varied from a low of 9% for homeopathy to a high of 19% for chiropractic and massage therapy. Approximately half of the surveyed physicians believed in the efficacy of acupuncture (51%), chiropractic (53%), and massage (48%), while fewer believed in the value of homeopathy (26%) and herbal approaches (13%). CONCLUSIONS: This review suggests that large numbers of physicians are either referring to or practicing some of the more prominent and well-known forms of CAM and that many physicians believe that these therapies are useful or efficacious. These data vary considerably across surveys, most likely because of regional differences and sampling methods, suggesting the need for more rigorous surveys using national, representative samples. Finally, outcomes studies are needed so that physicians can make decisions about the use of CAM based on scientific evidence of efficacy rather than on regional economics and cultural norms.

Acupuncture Therapy↗
PubMed1997

Cortical and hippocampal volume deficits in temporal lobe epilepsy.

PURPOSE: To use quantitative magnetic resonance imaging (MRI) methods to examine the extent of volume abnormalities in the hippocampus and in extrahippocampal brain regions in localization-related epilepsy of temporal lobe origin (TLE). METHODS: Hippocampal, temporal lobe, and extratemporal lobe volumes were examined with 3-mm spin-echo coronal MRI scans in patients with unilateral TLE who were candidates for temporal lobe resection. Measures were adjusted for normal variation due to intracranial volume and age based on 72 healthy male controls. Group differences between 14 male TLE [7 left TLE (LTLE), 7 right TLE (RTLE)] patients and a subset of 49 age range-matched controls were examined with analysis of variance (ANOVA). RESULTS: As compared with controls, patients with TLE had smaller temporal lobe and frontoparietal region gray matter volumes, bilaterally, smaller temporal lobe white matter volumes bilaterally, and larger ventricular volumes. In contrast to these bilateral tissue volume deficits, hippocampal volume deficits in TLE were ipsilateral to the epileptogenic temporal lobe. CONCLUSIONS: Extrahippocampal volume abnormalities were bilateral and occurred in both temporal and extra-temporal cortical regions in TLE, whereas hippocampal deficits were related to the side of the epileptogenic focus. These data suggest that brain abnormalities in TLE are not limited to the epileptogenic region.

Adolescent↗
PubMed1996

Up-regulation of GABAA receptor binding on neurons of the prefrontal cortex in schizophrenic subjects.

Recent investigations have reported a reduced density of interneurons and an increase of GABAA receptor binding occurring preferentially in layer II of the anterior cingulate cortex of schizophrenic subjects [Benes F.M. et al. (1992) J. Neurosci. 12, 924-929]. Since a reduction in the density of interneurons has also been found in layer II of the prefrontal cortex, this study has sought to determine whether an un-regulation of the GABAA receptor binding activity might also be found in this region of schizophrenics. A high-resolution autoradiographic analysis of bicuculline-sensitive [3H]muscimol (GABAA) receptor binding on individual neuron cell bodies in layers II, III, IV and VI has been applied to Brodmann area 10 from normal controls (n = 16) and schizophrenic (n = 7) subjects. A computer-assisted technique has been used under strictly blind conditions to determine whether differences in binding occur in the schizophrenic group. A significant increase of GABAA receptor binding activity has been observed in layers II, III, V and VI in the schizophrenic group. When the binding is expressed as a density with respect to neuronal cell size, there is a gradient of binding across layers II, III, V and VI, with neuronal cell bodies in layer II having the greatest density of grains. When different subpopulations of neurons distinguished according to size criteria are examined separately, large (pyramidal) neurons show significantly higher binding, particularly in layer II, where it was increased by 90% in schizophrenics. Small (non-pyramidal) cells do not show significant differences in binding in schizophrenics, except in layer VI, where there was a 135% increase. Potential confounding effects from age and post mortem interval do not explain the differences between the two groups, because both young and old schizophrenics, as well as schizophrenics with long and short post mortem intervals, showed increased GABAA receptor binding activity when compared to control cases distinguished in a corresponding fashion. These data suggest that there may be a preferential reduction of inhibitory GABAergic inputs to pyramidal neurons, particularly in layer II of the preferential cortex, in schizophrenia. This change could potentially result in an increased excitatory outflow from the prefrontal area to other cortical regions of the schizophrenic brain. Overall, these results are consistent with the idea that reduced amounts of GABAergic activity in the prefrontal cortex could be related to a perinatal disturbance and could be a potentially important component of the pathophysiology of psychosis.

Adult↗
PubMed1994

Adynamic bone disease in patients with uremia.

Adynamic (or aplastic) bone disease is a bone histologic pattern characterized by decreased bone formation rate, low cellularity, and normal or decreased osteoid thickness. It was first described in symptomatic patients undergoing dialysis who were overloaded with aluminum because of contaminated dialysate or chronic ingestion of aluminic phosphate binders; the evidence of the overload was extensive coloration (more than 25%) with aurin tricarboxylic acid, whereas the Perls stain coloration for iron was negative. We have, however, reported these histologic changes in asymptomatic patients with uremia who were never exposed to aluminum, in two patients before end-stage renal failure and in six patients undergoing dialysis. The main step in the prevention of adynamic bone disease is the absolute exclusion of aluminum exposition even by so-called "safe doses" of aluminum phosphate binders because in the long term they are never actually safe. Because idiopathic adynamic bone disease may nevertheless occur, parathyroid hormone suppressive treatment by oral calcium taken with meals as phosphate binders (+/- 1 alpha-hydroxyvitamin D3 derivatives) should be carefully monitored by measurements of plasma concentrations of not only calcium and phosphate but also of intact parathyroid hormone levels. In order to have normal bone formation rate levels, patient intact parathyroid hormone levels should be between one and three times the upper limit of the normal level. Although adynamic bone disease may not be a true bone disease when not due to aluminum, it is a risk factor for increased incidence of hypercalcemia and hyperphosphatemia and therefore for metastatic calcifications. Therefore, when hypercalcemia occurs with hyperphosphatemia and normal intact parathyroid hormone in patients treated with 1 alpha-hydroxyvitamin D3, it is proposed that the latter drug should be discontinued first, whereas oral calcium is increased to correct hyperphosphatemia, and calcium concentration is decreased in the dialysate to prevent hypercalcemia, even though plasma parathyroid hormone may increase up to three times the upper limit of the normal level. In patients previously exposed to aluminum, a deferoxamine test should be performed and a deferoxamine treatment started if the test is positive.

Aluminum↗
PubMed1992

Non-aluminic adynamic bone disease in non-dialyzed uremic patients: a new type of osteopathy due to overtreatment?

Adynamic bone disease, characterized by a low bone formation rate with normal or reduced amount of unmineralized osteoid, is supposed to be the consequence of aluminum intoxication in uremic patients. However, the emergence of adynamic bone disease has been recently reported in hemodialyzed patients in the total absence of aluminum overload. This study was aimed to assess whether such a histological pattern of adynamic bone disease was already present in uremic patients not yet on dialysis. Twenty-seven asymptomatic uremic patients (mean age +/- SD 43 +/- 10 years, mean creatinine clearance 19 +/- 3 ml/mm) were studied and bone biopsies were repeated in 16 of them after 18 +/- 10 months of treatment with oral calcium carbonate (1-3 g of elemental calcium/day) and calcidiol (21 +/- 14 micrograms/day). None of the patients received aluminum hydroxide, and the search for bone aluminum deposits was negative in all patients both before and after treatment. Two patients fulfilled the criteria of adynamic bone disease on their post-treatment biopsies. They originated from patients classified as having normal bone histology before treatment. Comparison with the other patients showed that they had comparable plasma C-terminal PTH but higher plasma creatinine than patients with normal bone histology and lower plasma C-terminal PTH than patients with osteitis fibrosa but comparable plasma creatinine. The plasma levels of 1,25(OH)2D reached values above normal after treatment in these two patients. It is suggested that adynamic bone disease not related to aluminum intoxication can develop in uremic patients independently of dialysis, and is favored by a relative hypoparathyroidism for the degree of renal failure, possibly induced by elevated plasma concentrations of calcitriol.

Adult↗
PubMed1991

Destructive spondyloarthropathy with beta 2-microglobulin amyloid deposits in a uremic patient before chronic hemodialysis.

We report a case of erosive arthropathies discovered radiologically before dialysis in a uremic patient with Alport syndrome. This patient had no hereditary amyloidosis or causes of acquired generalized amyloidosis (no chronic infections or inflammatory disease, neoplasia, lymphoma or monoclonal gammapathy). Erosive spondyloarthropathies of the cervical spine at the C5-C6 and C6-C7 levels, erosive arthropathy of the right acromioclavicular joint, metacarpal lacuna of the right hand, and lacuna of the left femoral neck were discovered 24 months before starting dialysis in this patient with chronic renal insufficiency of 17 years duration. Puncture of the vertebral disc before starting dialysis took a fragment showing amyloid deposits with permanganate-sensitive Congo red staining and positive staining with anti-beta 2-microglobulin antibodies. This observation suggests that beta 2-microglobulin amyloidosis in uremia may not be exclusively related to chronic kidney replacement therapy, but to uremia per se, especially when the latter is of long duration.

Amyloid↗