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Biomedical subjects

C Schwartz

Publications and source records attributed to C Schwartz.

At least 19 recordsLinked to original sources
PubMed2006

Road soil retention of Pb leached from MSWI bottom ash.

Municipal solid waste incinerator (MSWI) bottom ash may be used as a road construction material; it potentially contains however a sizable quantity of heavy metals, which under the effect of rainfall infiltration through the road structure can be leached out from the material and infiltrate into the underlying soil. An eco-compatibility assessment of MSWI bottom ash reuse in road construction applications necessitates examining the solubility and retention of heavy metals in road soils. This study is dedicated to Pb transfer, sorption and desorption (NEN 7341 standard test) within various soils. These experiments yield results relative to the interaction between road soils and an MSWI bottom ash leachate representative of a "fresh" product, with a high leaching potential. For the soils investigated, the sorption of lead varies between 90% and 99%. For an extraction at pH 7, Pb release is very low (<2%) for all soils, while at pH 4 leaching varies between 4% and 47%. This work shows that Pb may be fixed by some types of road soil in mostly stable forms.

Conservation of Natural Resources↗
PubMed2003

X-linked creatine transporter defect: an overview.

In 2001 we identified a new inborn error of metabolism caused by a defect in the X-linked creatine transporter SLC6A8 gene mapped at Xq28 (SLC6A8 deficiency, McKusick 300352). An X-linked creatine transporter defect was presumed because of (1) the absence of creatine in the brain as indicated by proton magnetic resonance spectroscopy (MRS); (2) the elevated creatine levels in urine and normal guanidinoacetate levels in plasma, ruling out a creatine biosynthesis defect; (3) the absence of an improvement on creatine supplementation; and (4) the fact that the pedigree suggested an X-linked disease. Our hypothesis was proved by the presence of a hemizygous nonsense mutation in the male index patient and by the impaired creatine uptake by cultured fibroblasts. Currently, at least 7 unrelated families (13 male patients and 13 carriers) with a SLC6A8 deficiency have been identified. Four families come from one metropolitan area. This suggests that SLC6A8 deficiency may have a relatively high incidence. The hallmarks of the disorder are X-linked mental retardation, expressive speech and language delay, epilepsy, developmental delay and autistic behaviour. In approximately 50% of the female carriers, learning disabilities of varying degrees have been noted.

Biological Transport↗
PubMed2003

Life satisfaction of people with intellectual disability living in community residences: perceptions of the residents, their parents and staff members.

BACKGROUND: Within the literature on quality of life (QoL), life satisfaction (LS) has emerged as a key variable by which to measure perceived well-being, which is referred to as subjective QoL. The LS self-reports of 93 residents with intellectual disability (ID) living in community-based residences were compared with reports about their LS completed by their staff and parents. METHOD: The residents were interviewed on their LS by social workers who did not belong to the staff of the interviewee's residence. The instrument used was the Life Satisfaction Scale (LSS). Staff and parents completed the short version of the LSS. RESULTS: Residents and staff's LS reports were positively correlated. However, significant differences were found between these two groups of informants when the residents were characterized as high functioning, had a low score in challenging behaviour, worked in an integrative employment setting and lived in an apartment. As opposed to staff/resident discrepancies, no differences were found between parents' and residents' LS reports. CONCLUSIONS: If residents cannot to be interviewed about their LS, then the parent is the preferred person to respond on behalf of the resident. The current study highlights the importance of including both objective measures (e.g. functional assessment characteristics) and subjective measures (e.g. LS) in order to get a better understanding of the QoL of people with ID.

Adolescent↗
PubMed2003

A third MRX family (MRX68) is the result of mutation in the long chain fatty acid-CoA ligase 4 (FACL4) gene: proposal of a rapid enzymatic assay for screening mentally retarded patients.

BACKGROUND: The gene encoding fatty acid CoA ligase 4 (FACL4) is mutated in families with non-specific X linked mental retardation (MRX) and is responsible for cognitive impairment in the contiguous gene syndrome ATS-MR (Alport syndrome and mental retardation), mapped to Xq22.3. This finding makes this gene a good candidate for other mental retardation disorders mapping in this region. METHODS: We have screened the FACL4 gene in eight families, two MRX and six syndromic X linked mental retardation (MRXS), mapping in a large interval encompassing Xq22.3. RESULTS: We have found a missense mutation in MRX68. The mutation (c.1001C>T in the brain isoform) cosegregates with the disease and changes a highly conserved proline into a leucine (p.P375L) in the first luciferase domain, which markedly reduces the enzymatic activity. Furthermore, all heterozygous females showed completely skewed X inactivation in blood leucocytes, as happens in all reported females with other FACL4 point mutations or deletions. CONCLUSIONS: Since the FACL4 gene is highly expressed in brain, where it encodes a brain specific isoform, and is located in hippocampal and cerebellar neurones, a role for this gene in cognitive processes can be expected. Here we report the third MRX family with a FACL4 mutation and describe the development of a rapid enzymatic assay on peripheral blood that we propose as a sensitive, robust, and efficient diagnostic tool in mentally retarded males.

Adolescent↗
PubMed2002

Abnormal expression of the KLF8 (ZNF741) gene in a female patient with an X;autosome translocation t(X;21)(p11.2;q22.3) and non-syndromic mental retardation.

Non-syndromic X linked mental retardation (MRX) is a heterogeneous group of conditions in which all patients have mental retardation as the only constant phenotypic feature. We have identified a female patient with mental retardation and a balanced translocation involving chromosomes X and 21, t(X;21)(p11.2;q22.3). Physical mapping of the translocation breakpoint on the human X chromosome was performed using fluorescence in situ hybridisation. We have mapped the X chromosome breakpoint to a 21 kb DNA fragment upstream of the first exon of the KLF8 (ZNF741) gene in Xp11.21. We have subsequently shown that the KLF8 transcript is no longer detected in cells from the patient, although KLF8 expression is otherwise normally present in control lymphoblasts. Mutation screening of probands from 20 unrelated XLMR families linked to the proximal short arm of the human X chromosome failed to show any mutation in the coding region of the KLF8 gene.

Child, Preschool↗
PubMed2001

Crosstalk between Myc and activating transcription factor 2 (ATF2): Myc prolongs the half-life and induces phosphorylation of ATF2.

Myc is a key regulator of cell growth, differentiation and apoptosis, and affects cell fate decisions by activating as well as by inhibiting the expression of cellular genes. Myc is a member of the basic region-helix-loop-helix-leucine zipper (b-HLH-Zip) class of transcription factors, which heterodimerizes with the Max protein and recognizes a consensus Myc binding motif. Stimulation of gene expression by Myc is thought to be mediated by direct binding of Myc-Max heterodimers to specific target genes. So far, only a few genes have been identified as direct binding targets of Myc, raising the possibility that Myc affects gene expression also by indirect mechanisms. In this work we present evidence that v-Myc encoded by the avian retrovirus MC29 stimulates activating transcription factor 2 (ATF2)-dependent transcription. Analysis of the effect of Myc on ATF2 shows that v-Myc prolongs the half-life of ATF2 and induces the phosphorylation of N-terminal sites of ATF2 (Thr-69 and Thr-71) which have previously been identified as the target sites of stress-activated protein kinases and implicated in the regulation of ATF2 activity. Taken together, our results suggest that v-Myc can affect gene expression indirectly by modulating the activity of ATF2.

Activating Transcription Factor 2↗
PubMed2001

Measurement of in situ phytoextraction of zinc by spontaneous metallophytes growing on a former smelter site.

This work was undertaken to measure the in situ phytoextraction of zinc using a former zinc-smelter site where metallophyte plants have been growing for 30 years. The site exhibited a gradient in the total metal concentration in the upper horizon (from 3230 to 8530 mg Zn kg(-1)). Soils were sampled from four different sectors (I-IV), and plant shoots were harvested, identified, their biomass weighed and analysed for zinc. The results showed that three plant species were dominant on the site, including Arabidopsis halleri (cress), Armeria maritima (seathrift), and Arrhenatherum elatius (fromental). A. maritima was the predominant species according to the biomass production on the most polluted sector 1. As the concentration of metals in soils decreased. A. maritima disappeared and A. halleri increased. The biomass of A. elatius was the highest on the less polluted soils. Concentrations in zinc in the aerial parts of plants varied from 73 (sector IV) to 6269 mg kg(-1) DM (sector 1). The concentration of Zn in A. halleri decreased with the decrease in concentration of zinc in soil. Phytoextraction was calculated from the biomass and its concentration of metal. It was at a maximum in sector III with a high contribution of A. halleri and A. elatius and reached 10 kg Zn ha(-1), a promising amount for phytoextraction considering the absence of any agricultural practices. In sector 1, phytoextraction was four times lower despite a 2.6 times higher concentration of Zn in the upper horizon. In conclusion, phytoextraction was strongly dependent on the concentration of the available metal in soils which may limit the growth of plants, and favour tolerant but low biomass plant species such as A. maritima.

Biological Availability↗
PubMed2001

Genomic organization and embryonic expression of Suppressor of Fused, a candidate gene for the split-hand/split-foot malformation type 3.

The genes for human and mouse Suppressor of Fused (SU(FU)/Su(Fu)) in the Hedgehog signaling pathway were characterized and found to contain 12 exons. Human SU(FU) localized on chromosome 10q24-25 between the markers D10S192 and AFM183XB12. We detected three additional SU(FU) isoforms, two of which have lost their ability to interact with the transcription factor GLI1. Expression analysis using whole mount in situ hybridization revealed strong expression of Su(Fu) in various mouse embryonic tissues. SU(FU) was considered a candidate gene for the split-hand/split-foot malformation type 3 (SHFM3). However, no alterations in the SU(FU) gene were found in SHFM3 patients.

Amino Acid Sequence↗
PubMed2001

Role of a pineal cAMP-operated arylalkylamine N-acetyltransferase/14-3-3-binding switch in melatonin synthesis.

The daily rhythm in melatonin levels is controlled by cAMP through actions on the penultimate enzyme in melatonin synthesis, arylalkylamine N-acetyltransferase (AANAT; serotonin N-acetyltransferase, EC ). Results presented here describe a regulatory/binding sequence in AANAT that encodes a cAMP-operated binding switch through which cAMP-regulated protein kinase-catalyzed phosphorylation [RRHTLPAN --> RRHpTLPAN] promotes formation of a complex with 14-3-3 proteins. Formation of this AANAT/14-3-3 complex enhances melatonin production by shielding AANAT from dephosphorylation and/or proteolysis and by decreasing the K(m) for 5-hydroxytryptamine (serotonin). Similar switches could play a role in cAMP signal transduction in other biological systems.

14-3-3 Proteins↗
PubMed2001

Glucocorticoid receptors and serotonin N-acetyltransferase activity in the fish pineal organ.

This study aimed to determine whether glucocorticoid receptors are expressed in the photosensitive trout pineal organ, and whether glucocorticoids modulate melatonin secretion. On Western blots from pineal extracts, an antibody directed against trout glucocorticoid receptor labeled a single band at the expected size (approximately 100 kDa). Dexamethasone inhibited pineal arylalkylamine N-acetyltransferase activity (AANAT2; serotonin --> N-acetylserotonin) in a dose-dependent manner after 6 h of culture in the dark (IC50 2.10(-8) M). RU486 (10(-7) M) alone had a partial agonistic activity, whereas it antagonized the effects of 10(-8) M dexamethasone. Hydroxyindole-O-methyltransferase activity (N-acetylserotonin --> melatonin) remained unaffected. This is the first demonstration that glucocorticoid receptors are present in the pineal organ and that glucocorticoids modulate melatonin production.

Acetylserotonin O-Methyltransferase↗
PubMed2001

Mutations in the X-linked RSK2 gene (RPS6KA3) in patients with Coffin-Lowry syndrome.

RSK2 is a growth factor-regulated serine-threonine protein kinase, acting in the Ras-Mitogen-Activated Protein Kinase (MAPK) signaling pathway. Mutations in the RSK2 gene (RPS6KA3) on chromosome Xp22.2, have been found to cause Coffin-Lowry syndrome (CLS), an X-linked disorder characterized by psychomotor retardation, characteristic facial and digital abnormalities, and progressive skeletal deformations. By screening of 250 patients with clinical features suggestive of Coffin-Lowry syndrome, 71 distinct disease-associated RSK2 mutations have been identified in 86 unrelated families. Thirty-eight percent of mutations are missense mutations, 20% are nonsense mutations, 18% are splicing errors, and 21% are short deletion or insertion events. About 57% of mutations result in premature translation termination, and the vast majority are predicted to cause loss of function of the mutant allele. These changes are distributed throughout the RSK2 gene and show no obvious clustering or phenotypic association. However, some missense mutations are associated with milder phenotypes. In one family, one such mutation was associated solely with mild mental retardation. It is noteworthy that nine mutations were found in female probands, with no affected male relatives, ascertained through learning disability and mild but suggestive facial and digital dysmorphisms.

Abnormalities, Multiple↗
PubMed2001

Subliminal messages for increasing self-esteem: placebo effect.

Although experimental research has confirmed the capacity of the human cognitive system to process information that does not reach consciousness (unconscious perception), empirical evidence of the incidence of subliminal verbal messages included on audiotapes claiming to improve human resources and correct some behavioral problems is meager and inconsistent. Our study assesses the influence of "subliminal tapes" designed to increase self-esteem. Participants were randomly assigned to four experimental conditions. One group listened to a tape of music with supra- and subliminal messages; another listened to a tape of music with only subliminal messages; the third group's tape had only music, although the participants believed that it also included subliminal messages; a fourth ("waiting") group heard no tapes, but filled in the same self-esteem scales. Participants in the first three groups filled in the Tennessee Self-Concept Scale (Fitts, 1965) before and after listening to the tape for several days. All groups showed a similar pretest-posttest improvement in self-esteem (p < or = .003), except for the waiting group, which did not improve (p = .311). This implies that only a placebo effect took place. Our data are not in accordance with those obtained by other authors. We comment upon the possible reasons for these discrepancies.

Adolescent↗
PubMed2001

On-line sulfur isotope analysis of organic material by direct combustion: preliminary results and potential applications.

Sulfur isotopes have received little attention in ecology studies because plant and animal materials typically have low sulfur concentrations (< 1 wt.%) necessitating labor-intensive chemical extraction prior to analysis. To address the potential of direct combustion of organic material in an elemental analyzer coupled with a mass spectrometer, we compared results obtained by direct combustion to results obtained by sulfur extraction with Eschka's mixture. Direct combustion of peat and animal tissue gave reproducibility of better than 0.5/1000 and on average, values are 0.8/1000 higher than values obtained by Eschka extraction. Successful direct combustion of organic material appears to be a function of sample matrix and sulfur concentration. Initial results indicate that direct combustion provides fast, reliable results with minimal preparation. Pilot studies underway include defining bear diets and examining fluctuations between freshwater and brackish water in coastal environments.

Ecosystem↗
PubMed2001

Monitoring end-tidal carbon dioxide during weaning from cardiopulmonary bypass in patients without significant lung disease.

End-tidal carbon dioxide tension (PETCO(2)) changes with fluctuations in cardiac output (CO). We compared PETCO(2) to pulmonary artery blood flow (PAQt) during weaning from cardiopulmonary bypass (CPB) in normothermic patients without significant pulmonary disease. Fifteen consecutive adult cardiac surgical patients were prospectively studied during and shortly after weaning from CPB. Before separation from CPB, PETCO(2) and PAQt were measured, the latter by transesophageal Doppler echocardiography. At the time of measurements patients were normothermic, and ventilated at 6 breaths/min with tidal volumes of 10 mL/kg. After separation from CPB, thermodilution cardiac output (TDCO) was measured in addition to PAQt and PETCO(2). Regression and bias analyses were used to compare PETCO(2), PAQt, and TDCO. Seventy measurements were recorded; 31 before separation from CPB and 39 after separation from CPB. A good correlation was seen between PAQt and PETCO(2) (r = 0.88) and between TDCO and PAQt (r = 0.93; mean bias 0.03 L/min; SD 0.52 L/min). The regression analysis of PAQt on PETCO(2) showed greater variability at PETCO(2) levels > 34 mm Hg (n = 22; r = 0.14). Increases in PETCO(2) plateaued at this level, although PAQt continued to increase. When PETCO(2) was more than 30 mm Hg, all PAQt and TDCO values were >4.0 L/min (>2.0 L/min/m(2)). When PETCO(2) exceeded 34 mm Hg, all values of PAQt, and 28/29 values of TDCO were more than 5 L/min (>2.5 L/min/m(2)). One patient had TDCO of 4.69 L/min (2.39 L/min/m(2)). In normothermic patients without significant pulmonary disease, PETCO(2) is a useful index of PAQt during separation from CPB. Under the clinical settings in this study, a PETCO(2) greater than 30 mm Hg was invariably associated with a CO more than 4.0 L/min or a cardiac index >2.0 L/min/m(2).

Aged↗
PubMed2000

Melatonin synthesis: arylalkylamine N-acetyltransferases in trout retina and pineal organ are different.

Serotonin N-acetyltransferase (AANAT) is the first enzyme in the conversion of serotonin to melatonin. Changes in AANAT activity determine the daily rhythm in melatonin secretion. Two AANAT genes have been identified in the pike, pAANAT-1 and pAANAT-2, expressed in the retina and in the pineal, respectively. The genes preferentially expressed in these tissues encode proteins with distinctly different kinetic characteristics. Like the pike, trout retina primarily expresses the AANAT-1 gene and trout pineal primarily expresses the AANAT-2 gene. Here we show that the kinetic characteristics of AANAT in these tissues differ as in pike. These differences include optimal temperature for activity (pineal: 12 degrees C; retina: 25 degrees C) and relative affinity for indoleethylamines compared to phenylethylamines. In addition, retinal AANAT exhibited substrate inhibition, which was not seen with pineal AANAT. The kinetic differences between AANAT-1 and AANAT-2 appear to be defining characteristics of these gene subfamilies, and are not species specific.

Acetyl Coenzyme A↗