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Biomedical subjects

A Eden

Publications and source records attributed to A Eden.

At least 19 recordsLinked to original sources
PubMed2006

The implementation of an anesthesia information management system.

BACKGROUND AND OBJECTIVE: Anaesthesia information management systems, though still not used widely, will inevitably replace handwritten records and may eventually serve as a core for the development of computerized decision support. We investigated staff expectations and the accuracy of data entry in a recently implemented commercially available anaesthesia information management system. METHODS: A structured questionnaire was administered to the staff before and 1 week and 3 months after implementation in order to assess their opinion. The quality of manual data entry, and of automatic data record was evaluated by looking for missing data and the prevalence of artefacts. RESULTS: Despite initial fears the users quickly accepted the system. Both automatic and manual data entry were found to be accurate and reliable while the prevalence of artefacts was relatively low. CONCLUSIONS: A commercially available anaesthesia information management system can be easily implemented and used instead of paper charts.

Adult↗
PubMed2003

Lack of association between B19 or V9 erythrovirus infection and ANCA-positive vasculitides: a case-control study.

OBJECTIVES: To examine the potential association of human B19 or V9 erythrovirus infection and onset of ANCA-positive vasculitides. METHODS: We tested the sera of 13 adults with newly diagnosed ANCA-positive vasculitides. Each was age- and sex-matched to three sera obtained from healthy controls. All samples were tested for B19- and V9-specific immunoglobulin (Ig) G and IgM antibodies (Ab) (third-generation ELISA), and B19 or V9 DNA was sought with the polymerase chain reaction. Statistical analysis was performed by conditional logistic regression. RESULTS: Patient diagnoses comprised six cases of Wegener's granulomatosis, six of microscopic polyangiitis and one of Churg-Strauss syndrome. IgG Ab to B19 were detected equally in patient and control sera (77 and 79% respectively) (odds ratio=0.84, P=0.84). All 13 cases and 39 controls were negative for IgM Ab and viral DNA. CONCLUSION: These results suggest that neither acute nor chronic B19 or V9 infection is an aetiological factor in ANCA-associated vasculitides.

Acute Disease↗
PubMed2001

Quantitation of soluble and skeletal alkaline phosphatase, and insoluble alkaline phosphatase anchor-hydrolase activities in human serum.

BACKGROUND: The current studies were intended to compare the circulating levels of total and anchorless (soluble) skeletal and hepatic ALP isoenzyme activities, and insoluble ALP anchor-hydrolase activity in serum of postmenopausal women. METHODS: Preliminary studies of the insoluble ALP anchor-hydrolase activity in serum revealed a pH optimum of pH 5-6.5, a sensitivity to inactivation by heat at temperatures >45 degrees C (t(1/2)=8-9 min at 60 degrees C), and an apparent K(M) (at pH 7.5) of 40-45 mU/ml of insoluble skeletal ALP activity. RESULTS: Serum analyses showed that 94.5+/-0.5% (mean+/-SEM) of the ALP activity in serum was in the anchorless, soluble form. The data were also consistent with the notion that the amount of insoluble ALP anchor-hydrolase activity in serum, 52.8+/-0.8 U/l (mean+/-SEM), was sufficient for the conversion of anchor-intact (insoluble) ALP into the anchorless, soluble form, assuming activation by serum lipids and/or bile salts. Distributions of results for total, skeletal, hepatic, and insoluble ALP anchor-hydrolase activity were skewed toward the higher range and leptokurtotic (p<0.01 for each). Total ALP activity ranged from 42% to 208% of the group mean value; skeletal, hepatic, and insoluble ALP anchor-hydrolase activities ranged from 5% to 306%, 33% to 277%, and 2% to 325%, respectively. In contrast, the soluble ALP fraction only ranged from 71% to 106% of the group mean value. CONCLUSIONS: The correlations between the total and both skeletal (r=0.711, p<0.001) and hepatic (r=0.782, p<0.001) ALP isoform activities were predictive. Although correlations were also observed between insoluble ALP anchor-hydrolase activity and total (r=0.197, p<0.001), hepatic (r=0.184, p<0.001) and skeletal ALP activities (r=0.118, p<0.05), those relationships were not predictive (r(2)<0.04).

Alkaline Phosphatase↗
PubMed2001

Induced neuronal differentiation of human embryonic stem cells.

Human embryonic stem (ES) cells are pluripotent cells capable of forming differentiated embryoid bodies (EBs) in culture. We examined the ability of growth factors under controlled conditions to increase the number of human ES cell-derived neurons. Retinoic acid (RA) and nerve growth factor (betaNGF) were found to be potent enhancers of neuronal differentiation, eliciting extensive outgrowth of processes and the expression of neuron-specific molecules. Our findings show that human ES cells have great potential to become an unlimited cell source for neurons in culture. These cells may then be used in transplantation therapies for neural pathologies.

Antineoplastic Agents↗
PubMed2001

Involvement of branched-chain amino acid aminotransferases in the production of fusel alcohols during fermentation in yeast.

Organoleptic compounds produced by yeast during the fermentation of wort have a great impact on beer smell and taste. Among them, fusel alcohols are the major abundant volatile compounds. The availability of Saccharomyces cerevisiae mutants in which the genes coding for the two branched-chain amino acid aminotransferases have been deleted offers the possibility of further defining the role of these enzymes in the formation of higher alcohols. Comparing the production profiles of different strains, it is clear that they are not all influenced in the same way by branched-chain amino acid aminotransferase mutations. First of all, as propanol is synthesised from alpha-ketobutyrate, the first metabolic intermediate in the anabolic pathway of isoleucine, neither the eca39 nor eca40 mutations have any effect on the production of this higher alcohol. On the other hand, it can be concluded that the eca40 mutation has a drastic effect on the production of isobutanol. To a certain extent, the same conclusion can be made for the production of active amyl alcohol and isoamyl alcohol, although the results suggest that another route could lead to the formation of these two higher alcohols.

1-Propanol↗
PubMed2000

Dynamic relocalization of histone MacroH2A1 from centrosomes to inactive X chromosomes during X inactivation.

Histone variant macroH2A1 (macroH2A1) contains an NH(2)-terminal domain that is highly similar to core histone H2A and a larger COOH-terminal domain of unknown function. MacroH2A1 is expressed at similar levels in male and female embryonic stem (ES) cells and adult tissues, but a portion of total macroH2A1 protein localizes to the inactive X chromosomes (Xi) of differentiated female cells in concentrations called macrochromatin bodies. Here, we show that centrosomes of undifferentiated male and female ES cells harbor a substantial store of macroH2A1 as a nonchromatin-associated pool. Greater than 95% of centrosomes from undifferentiated ES cells contain macroH2A1. Cell fractionation experiments confirmed that macroH2A1 resides at a pericentrosomal location in close proximity to the known centrosomal proteins gamma-tubulin and Skp1. Retention of macroH2A1 at centrosomes was partially labile in the presence of nocodazole suggesting that intact microtubules are necessary for accumulation of macroH2A1 at centrosomes. Upon differentiation of female ES cells, Xist RNA expression became upregulated and monoallelic as judged by fluorescent in situ hybridization, but early Xist signals lacked associated macroH2A1. Xi acquired macroH2A1 soon thereafter as indicated by the colocalization of Xist RNA and macroH2A1. Accumulation of macroH2A1 on X chromosomes occurred with a corresponding loss of centrosomal macroH2A1. Our results define a sequence for the loading of macroH2A1 on the Xi and place this event in the context of differentiation and Xist expression. Furthermore, these results suggest a role for the centrosome in the X inactivation process.

Animals↗
PubMed2000

Differentiation of human embryonic stem cells into embryoid bodies compromising the three embryonic germ layers.

BACKGROUND: Embryonic stem (ES) cells are lines of cells that are isolated from blastocysts. The murine ES cells were demonstrated to be true pluripotent cells as they differentiate into all embryonic lineages. Yet, in vitro differentiation of rhesus ES cells was somewhat inconsistent and disorganized. The recent isolation of human ES cells calls for exploring their pluripotential nature. MATERIALS AND METHODS: Human ES cells were grown in suspension to induce their differentiation into embryoid bodies (EBs). The differentiation status of the human ES cells and EBs was analyzed by following the expression pattern of several lineage-specific molecular markers using reverse transcription polymerase chain reaction (RT-PCR) and in situ hybridization. RESULTS: Here we report the induction in vitro of cystic embryoid bodies from human ES cells. Our findings demonstrate induction of expression of cell-specific genes during differentiation of the human ES cells into EBs. In the human EBs, we could show a characteristic regional expression of embryonic markers specific to different cellular lineages, namely, zeta-globin (mesoderm), neurofilament 68Kd (ectoderm), and alpha-fetoprotein (endoderm). Moreover, we present a synchronously pulsing embryoid body that expresses the myocardium marker alpha-cardiac actin. In addition, dissociating the embryoid bodies and plating the cells as monolayers results in multiple morphologies, among them cells with neuronal appearance that express neurofilament 68Kd chain. CONCLUSION: Human ES cells can reproducibly differentiate in vitro into EBs comprising the three embryonic germ layers. The ability to induce formation of human embryoid bodies that contain cells of neuronal, hematopoietic and cardiac origins will be useful in studying early human embryonic development as well as in transplantation medicine.

Animals↗
PubMed1999

Involvement of branched-chain amino acid aminotransferase (Bcat1/Eca39) in apoptosis.

The branched-chain amino acid aminotransferase, Bcat1/Eca39, catalyzes the first step of branched-chain amino acid catabolism. Bcat1/Eca39 was originally isolated from a c-myc-induced tumor and was proven to be a direct target for c-Myc regulation. The gene is highly conserved in evolution and disruption of its yeast homolog affects cell growth. To assess the role of Bcat1/Eca39 in mammalian cells, we overexpressed Bcat1/Eca39 in murine cells and studied effects on cell growth. Overexpression of Bcat1/Eca39 had no apparent effect on the proliferation of cells grown with high serum concentrations, but under serum deprivation conditions, led to a decrease in cell viability. Cell death under these conditions displayed apoptotic features. The branched-chain keto acid, alpha-ketoisocaproate, a metabolite of leucine catabolism produced by BCAT1/ECA39, was previously found to inhibit cell growth. We show that alpha-ketoisocaproate can induce rapid apoptotic cell death. This observation suggests that the growth inhibitory effect of BCAT1/ECA39 and its apoptosis promoting effect may be mediated by the levels of the products of BCAT1/ECA39 activity, namely, branched-chain keto acids.

3T3 Cells↗
PubMed1998

Characterization of a branched-chain amino-acid aminotransferase from Schizosaccharomyces pombe.

The Saccharomyces cerevisiae genes for the cytosolic and mitochondrial branched-chain amino-acid aminotransferases (BCAT) were isolated recently. These genes show significant homology to mammalian ECA39, originally isolated as a gene regulated by the c-myc oncogene. We now report the isolation of the Schizosaccharomyces pombe eca39/BCAT gene. The S. pombe protein shows 47-52% identity to other eukaryotic BCAT proteins isolated from S. cerevisiae, nematode, mouse and man. A genetic growth assay for BCAT activity was established using an S. cerevisiae strain disrupted in both BCAT isoenzymes. Consequently, the activity of the S. pombe BCAT was demonstrated by genetic and biochemical means. Possible applications of BCAT-encoding genes as selection markers in yeast transformation are proposed.

Amino Acid Sequence↗
PubMed1997

Erythroblastic inclusions in dominantly inherited beta thalassemias.

While the precipitation of unstable variant beta-globin chains has been implicated as a major pathogenic mechanism in dominantly inherited beta thalassemia, their instability and presence in intra-erythroblastic inclusions have not been conclusively shown. We report the investigation of two cases of dominantly inherited beta thalassemia due to heterozygosity for the beta-codon 121 G-T mutation. In one case, we were able to demonstrate the presence of an abnormal beta-globin chain in both peripheral blood reticulocytes and bone marrow erythroblasts, and to assess its stability in relation to the substantial amounts of mutant beta mRNA transcript. The serum transferrin receptor (TfR) level was markedly increased, an indication of increased erythropoietic activity. In both cases, we could show by immunoelectron microscopy that the intra-erythroblastic inclusion bodies, a prominent feature of diseases in this category, contained not only precipitated alpha-globin chains, but also beta chains. The data confirm previous suggestions that the cellular pathology underlying this group of beta thalassemias is related to the synthesis of highly unstable beta-globin chain variants, which fail to form functional tetramers and precipitate intracellularly with the concomitant excess alpha chains, leading to increased ineffective erythropoiesis.

Adult↗
PubMed1996

Two yeast homologs of ECA39, a target for c-Myc regulation, code for cytosolic and mitochondrial branched-chain amino acid aminotransferases.

ECA39 was isolated as a target gene for c-Myc regulation in mice. We identified two homologs for the murine ECA39 in the yeast Saccharomyces cerevisiae, ECA39 and ECA40, as well as two human homologs. These genes show a significant homology to prokaryotic branched-chain amino acid aminotransferase (BCAT) (EC). To understand the function of eukaryotic ECA39 and ECA40, we deleted either gene from the yeast genome. Activity of branched-chain amino acid aminotransferase was measured in the wild-type and mutants with either leucine, isoleucine, or valine as substrates. The results demonstrate that in S. cerevisiae ECA39 and ECA40 code for mitochondrial and cytosolic branched-chain amino acid aminotransferases, respectively. ECA39 is highly expressed during log phase and is down-regulated during the stationary phase of growth, while ECA40 shows an inverse pattern of gene expression. In agreement with these results, while we previously showed that deletion of ECA39 affected the cell cycle in proliferating cells, we do not observe a growth phenotype in eca40Delta cells. We suggest that BCAT is a target for c-Myc activity and discuss the evolutionary conservation of prokaryotic and eukaryotic BCATs and their possible involvement in regulation of cell proliferation.

Amino Acid Sequence↗
PubMed1996

ECA39, a conserved gene regulated by c-Myc in mice, is involved in G1/S cell cycle regulation in yeast.

The c-myc oncogene has been shown to play a role in cell proliferation and apoptosis. The realization that myc oncogenes may control the level of expression of other genes has opened the field to search for genetic targets for Myc regulation. Recently, using a subtraction/coexpression strategy, a murine genetic target for Myc regulation, called EC439, was isolated. To further characterize the ECA39 gene, we set out to determine the evolutionary conservation of its regulatory and coding sequences. We describe the human, nematode, and budding yeast homologs of the mouse ECA39 gene. Identities between the mouse ECA39 protein and the human, nematode, or yeast proteins are 79%, 52%, and 49%, respectively. Interestingly, the recognition site for Myc binding, located 3' to the start site of transcription in the mouse gene, is also conserved in the human homolog. This regulatory element is missing in the ECA39 homologs from nematode or yeast, which also lack the regulator c-myc. To understand the function of ECA39, we deleted the gene from the yeast genome. Disruption of ECA39 which is a recessive mutation that leads to a marked alteration in the cell cycle. Mutant haploids and homozygous diploids have a faster growth rate than isogenic wild-type strains. Fluorescence-activated cell sorter analyses indicate that the mutation shortens the G1 stage in the cell cycle. Moreover, mutant strains show higher rates of UV-induced mutations. The results suggest that the product of ECA39 is involved in the regulation of G1 to S transition.

Amino Acid Sequence↗