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Biomedical subjects

S Elias

Publications and source records attributed to S Elias.

At least 37 records · Page 2Linked to original sources
PubMed1999

Thalidomide and the Titanic: reconstructing the technology tragedies of the twentieth century.

The Titanic has become a metaphor for the disastrous consequences of an unqualified belief in the safety and invincibility of new technology. Similarly, the thalidomide tragedy stands for all of the "monsters" that can be inadvertently or negligently created by modern medicine. Thalidomide, once banned, has returned to the center of controversy with the Food and Drug Administration's (FDA's) announcement that thalidomide will be placed on the market for the treatment of erythema nodosum leprosum, a severe dermatological complication of Hansen's disease. Although this indication is very restricted, thalidomide will be available for off-label uses once it is on the market. New laws regarding abortion and a new technology, ultrasound, make reasonable the approval of thalidomide for patients who suffer from serious conditions it can alleviate. In addition, the FDA and the manufacturer have proposed the most stringent postmarketing monitoring ever used for a prescription drug, including counseling, contraception, and ultrasonography in the event of pregnancy. The Titanic/thalidomide lesson for the FDA and public health is that rules and guidelines alone are not sufficient to guarantee safety. Continuous vigilance will be required to ensure that all reasonable postmarketing monitoring steps are actually taken to avoid predictable and preventable teratogenic disasters.

Drug Approval↗
PubMed1998

Paraxial-fated mesoderm is required for neural crest induction in Xenopus embryos.

Neural crest induction is thought to occur by a two-step process. Axially fated mesoderm induces neural plate, which is then recruited to neural crest by nonneural epidermal ectoderm at the neural plate border. This model suggests a rather indirect role for mesoderm in inducing neural crest. We extensively examined the role of mesoderm in neural crest induction by determining which types of mesoderm induce neural crest cells in Xenopus embryos. We found that noggin-dorsalized ventral marginal zone (VMZ) explants differentiate as melanocytes in the absence of axial mesoderm. Dorsalized VMZ is also a potent inducer of melanocytes when juxtaposed to animal cap ectoderm in recombinant explants. Dorsalized VMZ is analogous to the dorsal-lateral marginal zone (DLMZ) region of the embryo. Neural crest-inducing activities of gastrula stage DLMZ and dorsal marginal zone (DMZ) were also compared in recombinant explants. DLMZ was a stronger inducer of neural crest than was DMZ; DLMZ induced high levels of XSlug expression and melanocyte formation in recombinants, whereas DMZ weakly induced neural crest. In whole embryos lacking DLMZ, XSlug expression and melanocyte formation were significantly reduced; in contrast, no significant reduction of XSlug expression or melanocyte formation was seen in embryos lacking a DMZ. These results suggest that paraxial-fated mesoderm plays a central role in neural crest formation by inducing a novel type of lateral neural plate. This lateral neural plate is then recruited to neural crest by adjacent nonneural epidermal ectoderm.

Animals↗
PubMed1998

Prenatal diagnosis with use of fetal cells isolated from maternal blood: five-color fluorescent in situ hybridization analysis on flow-sorted cells for chromosomes X, Y, 13, 18, and 21.

OBJECTIVE: Currently, prenatal diagnosis of chromosome abnormalities requires invasive techniques such as amniocentesis and chorionic villus sampling that carry small but finite risks of fetal loss. A noninvasive approach is to isolate fetal cells from maternal blood by flow sorting followed by genetic interphase analysis with fluorescence in situ hybridization. Because the ratio of fetal to maternal cells is relatively low after flow sorting and to detect 90% to 95% of fetal aneuploidies associated with serious birth defects, a 5-color fluorescent in situ hybridization strategy is necessary for simultaneous detection of chromosomes X, Y, 13, 18, and 21 in all flow-sorted nuclei recovered from a specimen. STUDY DESIGN: Fetal nucleated red blood cells were isolated from maternal blood in 40 cases (10.4 to 27.0 weeks' gestation) by flow cytometry on the basis of positive selection of CD71+ (transferrin receptor), CD45-, and LDS751 staining. Each case was evaluated for 5-color fluorescent in situ hybridization efficiency by determining the percentage of flow-sorted nuclei containing 8 hybridization signals for chromosomes X, Y, 13, 18, and 21. RESULTS: A total of 42,312 flow-sorted nuclei from maternal blood samples were analyzed. In 5 of 16 (31%) cases with a male fetus, 0.16% of nuclei scored were identified as fetal by the presence of 1 signal each for chromosomes X and Y. Fetal trisomy 21 nuclei were accurately detected in 2 cases with a female fetus, each of which was subsequently confirmed. CONCLUSIONS: Five-color interphase fluorescent in situ hybridization analysis can be used to effectively analyze rare fetal aneuploid nuclei in enriched flow-sorted cells isolated from maternal blood.

Chromosome Aberrations↗
PubMed1998

A POU protein regulates mesodermal competence to FGF in Xenopus.

XLPOU91, a POU-homeobox gene is expressed in a narrow window during early Xenopus development. We show that ectopic expression of XLPOU91 RNA causes severe posterior truncations in embryos without inhibiting the formation of Spemann's organizer. Ectopic XLPOU91 expression also inhibits mesoderm induction by fibroblast growth factor (FGF) and activin in animal cap explants. Using antisense RNA, we depleted endogenous XLPOU91 protein in animal caps. Gastrula-stage animal caps expressing XLPOU91 antisense RNA do not lose competence to FGF, unlike controls, these animal caps express XBra after FGF treatment. Endogenous XLPOU91 levels are peaking when FGF mesoderm-inducing competence is lost in animal caps. Thus XLPOU91 protein may act as a competence switch during early development, as XLPOU91 levels increase in the embryo, the mesoderm response to FGF is lost.

Animals↗
PubMed1998

BMP regulates vegetal pole induction centres in early xenopus development.

BACKGROUND: Bone morphogenetic protein (BMP) plays an important role in mesoderm patterning in Xenopus. The ectopic expression of BMP-4 protein hyperventralizes embryos, whereas embryos expressing a BMP-2/4 dominant-negative receptor (DNR) are hyperdorsalized. Mesoderm is initially induced in the marginal zone by cells in the underlying vegetal pole. While much is known about BMP's expression and role in patterning the marginal zone, little is known about its early role in regulating vegetal mesoderm induction centre formation. RESULTS: The role of BMP in regulating formation of vegetal mesoderm inducing centres during early Xenopus development was examined. Ectopic BMP-4 expression in vegetal pole cells inhibited dorsal mesoderm induction but increased ventral mesoderm induction when recombined with animal cap ectoderm in Nieuwkoop explants. 32-cell embryos injected with BMP-4 RNA in the most vegetal blastomere tier were not hyperdorsalized by LiCl treatment. The ectopic expression of Smad or Mix.1 proteins in the vegetal pole also inhibited dorsal mesoderm induction in explants and embryos. Expression of the BMP 2/4 DNR in the vegetal pole increased dorsal mesoderm induction and inhibited ventral mesoderm induction in explants and embryos. CONCLUSIONS: These results support a role for BMP signalling in regulating ventral vegetal and dorsal vegetal mesoderm induction centre formation during early Xenopus development.

Animals↗
PubMed1998

Human leukocyte antigen matching and fetal loss: results of a 10 year prospective study.

The role that maternal and fetal human leukocyte antigen (HLA) genes play in pregnancy is unknown, but it has been suggested that fetuses whose HLA alleles do not differ from maternal alleles (i.e. histocompatible fetuses) are more likely to be aborted than fetuses with HLA alleles that differ from maternal alleles (i.e. histoincompatible fetuses). To elucidate the role of HLA compatibility in pregnancy, we tested the hypothesis that couples who match for HLA alleles or haplotypes would have reduced fertility because only these couples could produce histocompatible fetuses. We conducted a 10 year prospective study of HLA matching and pregnancy outcome in 111 Hutterite couples, providing information on 251 pregnancies. A logistic regression analysis was performed to determine the effects of HLA matching at HLA regions and loci on pregnancy outcome (fetal loss versus delivery). Significantly increased fetal loss rates were observed among couples matching for the entire 16-locus haplotype (P = 0.002). Among the individual loci, loss rates were increased among couples matching for HLA-B (P = 0.019), HLA-C (P = 0.033) and the complement component, C4 (P = 0.043). We interpret these results as evidence that matching for the entire 16-locus haplotype and/or alleles at an HLA-B-linked locus confers significant risk for fetal loss.

Abortion, Spontaneous↗
PubMed1998

Optimized fixation and storage conditions for FISH analysis of single-cell suspensions.

In our protocol to isolate and identify fetal cells in maternal peripheral blood, antibody (Ab)-stained cells are preserved with paraformaldehyde (PF) before batch flow cytometric sorting. However, PF fixation compromises the quality of subsequent interphase fluorescence in situ hybridization (FISH). We therefore examined the effect of PF concentrations and storage time in phosphate-buffered saline (PBS) on the quality of FISH signals. Cells were analyzed for changes in light scatter, morphology, and accessibility of target cell DNA. Fixation in 3% PF for 1 hr was ideal for both flow cytometry and subsequent FISH detection. However, beyond 10 days of storage, FISH quality deteriorated. (J Histochem Cytochem 46:971-973, 1998)

Buffers↗
PubMed1997

Detection of chromosomal aneuploidy in endometriosis by multi-color fluorescence in situ hybridization (FISH).

Endometriosis affects 10-15% of women of reproductive age and is a common cause of infertility and pelvic pain. Although endometriosis is characterized by abnormal growth or turn-over of cells, the genetic changes involved remain unclear. We employed a multi-color fluorescence in situ hybridization (FISH) strategy to determine the incidence of somatic chromosomal numeric alterations in severe/late stage endometriosis. Using alpha-satellite sequence-specific DNA probes for chromosomes 7, 8, 11, 12, 16, 17, and 18, simultaneous two- and three-color FISH were performed to evaluate the frequency of monosomic, disomic, and trisomic cells in normal control and endometriotic tissue specimens. In one of four endometriosis samples studied, a significantly higher frequency of monosomy for chromosome 17 (14.8%, chi 2(4) = 53.3, P < 0.0001) and 16 (8.8%, chi 2(4) = 11.4, P < 0.05) was observed. An increased number of cells with chromosome 11 trisomy (14.8%, chi 2(4) = 96.2, P < 0.0001) were detected in a second case. In a third case, a distinct colony of nuclei with chromosome 16 monosomy (14.1%, chi 2(4) = 21.39, P < 0.005) was detected. Acquired chromosome-specific aneuploidy may be involved in endometriosis, reflecting clonal expansion of chromosomally abnormal cells. That candidate tumor suppressor genes and oncogenes have been mapped to chromosomes 11, 16, and 17 suggests that chromosomal loss or gain plays a role in the development and/or progression of endometriosis.

Aneuploidy↗
PubMed1997

Maternal serum screening for fetal genetic disorders.

Maternal serum analyte screening is an integral component of contemporary antenatal care. Based on elevated MSAFP levels, 85% to 90% of NTDs (e.g., anencephaly or spina bifida) can be detected. Using a combination of serum analytes (e.g., MSAFP, hCG, UE3) 55% to 60% of fetal Down's syndrome can be detected. Future strategies for Down's syndrome screening may include the use of new markers such as dimeric inhibin-A and urinary beta-core fragment of hCG, as well as first-trimester screening, particularly with PAPP-A and free beta-hCG.

Chorionic Gonadotropin↗
PubMed1997

HLA and mate choice in humans.

Evidence from studies in rodents suggests that mate selection is influenced by major-histocompatibility-complex haplotypes, with preferences for dissimilar partners. This study was initiated to determine whether avoidance of a mate with the same HLA haplotype as one's own might be occurring in the Hutterites, a North American reproductive isolate of European ancestry, notable for their large sibships, communal lifestyle, and limited number of five-locus HLA haplotypes (HLA-A, -B, -C, -DR, and -DQ). HLA haplotypes were known for 411 Hutterite couples. The number of couples expected to match for a haplotype was calculated in two ways: first, from population genotype frequencies, with account being taken of the nonrandom mating pattern with respect to colony lineages, and, second, from computer simulations using conservative founder assumptions and the exact genealogy of the 411 couples. We observed fewer matches for HLA haplotypes between spouses than expected (first method, P = .005; second method, P = .020-.067). Among couples who did match for a haplotype, the matched haplotype was inherited from the mother in 29 cases and from the father in 50 cases (P = .018). These results are consistent with the conclusion that Hutterite mate choice is influenced by HLA haplotypes, with an avoidance of spouses with haplotypes that are the same as one's own.

Adult↗
PubMed1996

Rare event selection of fetal nucleated erythrocytes in maternal blood by flow cytometry.

A noninvasive method of prenatal genetic diagnosis requires fetal cell selection from the maternal circulation that allows efficient recovery for analysis by fluorescence in situ hybridization (FISH). We have solved several problems that negatively affect the isolation and FISH analysis of fetal nucleated red blood cells (nRBCs) in the maternal circulation. The use of glycophorin A (Gly A) antibodies (Abs) for selection is problematic because all five monoclonal antibodies (mAbs) tested caused agglutination of non-nRBCs, thereby changing both light scatter and fluorescence properties of cells by flow cytometry. Because the number of non-nRBCs is variable after Ficoll separation, isolation of nRBCs could be compromised severely by agglutination of nucleated cells with nonnucleated cells, causing them to shift light scatter and fluorescence properties. Several methods for the removal of unwanted maternal white blood cells with CD45 mAbs were also evaluated. Magnetic bead depletion was found to interfere with FISH detection because of residual bead debris after sorting. By contrast, removal of CD45+ cells by a panning technique eliminated this problem. Positive selection methods based on CD71, CD45, and LDS-751 staining and detection of fetal cells by gamma globin expression were also analyzed. Fetal cells were detected by FISH in 11 of 19 (CD71 selection) and in 13 of 15 (gamma selection) random pregnancies. These data support the possibility of a noninvasive method for isolation and analysis of fetal cells for prenatal diagnosis.

Antigens, CD↗
PubMed1995

Characterization of an unbalanced de novo rearrangement by microsatellite polymorphism typing and by fluorescent in situ hybridization.

Unbalanced de novo rearrangements, difficult to characterize by conventional cytogenetic techniques, may be elucidated by molecular approaches. By dinucleotide repeat polymorphism typing and fluorescence in situ hybridization (FISH), we have defined the composition of an unbalanced de novo translocation (46,XX,15p+) in a child with multiple congenital anomalies. Use of a microsatellite repeat D5S208 (localized to 5p15) and polymerase chain reaction (PCR) analysis confirmed that the extra segment originated from the short arm of chromosome 5. Amplification of the patient's DNA with primers for dinucleotide repeats D5S350 and D5S118 showed that the entire 5p (from 5pter to 5q11) was present in 3 copies. FISH confirmed the trisomic status of 5p, and further revealed the presence of centromeres of both chromosomes 5 and 15 on the rearranged chromosome thus delineating its dicentric nature. This information allowed us to redefine the de novo rearrangement in this patient as 46,XX,dic der(15)t(5;15)(q11;p11).

Base Sequence↗
PubMed1995

Degradation of ornithine decarboxylase by the mammalian and yeast 26S proteasome complexes requires all the components of the protease.

Ornithine decarboxylase (ODC), a key enzyme in the biosynthesis of polyamines, is an extremely short-lived protein. This attribute is important for the regulation of the activity of the enzyme and implies that the mechanisms involved in its degradation play an important role in the control of the cellular processes in which the enzyme is involved. Recently, it has been shown that ODC is degraded by the 26S proteasome complex in a process that requires antizyme, but not ubiquitin. With one reported exception, ODC, the 26S complex recognizes and degrades specifically ubiquitinated proteins. Their unconjugated counterparts are not targeted. The 26S complex is composed of a core catalytic unit, the 20S proteasome complex, and two additional, and apparently distinct, subcomplexes. The two additional subcomplexes are regulatory subunits that are required in order to confer specificity and control. In this study, we demonstrate that, like the degradation of ubiquitin-conjugated proteins, ubiquitin-independent degradation of ODC also requires prior assembly of the mammalian 26S proteasome from all the three subunits, the 20S proteasome and the two subcomplexes. The combination of any two subunits does not support generation of a proteolytically active complex. This is also true for the yeast 26S complex. Like the mammalian 20S proteasome, the yeast 20S complex can cleave short peptides in an ATP-independent mode, but cannot degrade ODC or ubiquitin-conjugated proteins. These proteins are degraded only following addition of the regulatory subunits and generation of the high-molecular-mass 26S complex. In a distinct, but related, set of experiments, we demonstrate that the degradation of ODC by the assembled 26S proteasome in vitro reproduces faithfully proteolysis of the enzyme in the intact cell. Namely, (a) a C-terminal-deleted mouse ODC and trypanosome ODC are stable both in vitro and in vivo, and (b) like proteolysis in the intact cell, degradation in the reconstituted cell-free system is also dependent upon the addition of antizyme.

Animals↗