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Biomedical subjects

R A Fields

Publications and source records attributed to R A Fields.

14 recordsLinked to original sources
PubMed1995

DNA-based X-enriched sperm separation as an adjunct to preimplantation genetic testing for the prevention of X-linked disease.

We report the world's first clinical pregnancy resulting from DNA-based enrichment for X-bearing human spermatozoa, for prevention of X-linked hydrocephalus. Sperm separation was followed by embryo biopsy and nested multiplex polymerase chain reaction (PCR) for gender determination. Enriched populations of X-bearing spermatozoa ranging from 80 to 89% pure as determined by fluorescence in-situ hybridization (FISH) resulted in in-vitro fertilization (IVF) rates indistinguishable from normal IVF procedures (65%). In two separate biopsy procedures, 7/9 and 15/16 of the resulting embryos were determined to be female by multiplex PCR. Embryo transfer resulted in a karyotypically normal female fetus. This technique should be widely applicable to gender selection for the prevention of genetic disorders.

Adult↗
PubMed1992

Reliable gender screening for human preimplantation embryos, using multiple DNA target-sequences.

Dependable methods were developed for preimplantation sexing of human IVF embryos, for use in clinical settings where prospective parents are at high risk for transmission of X-linked diseases. Using single cultured cells and blastomeres from human embryos as model systems, a multiplex protocol was developed for rapid analysis via nested polymerase chain reaction (PCR). Reliability was enhanced by co-amplification of conserved amelogenin gene segments from both X and Y chromosomes, as well as Y-linked DYZ1 repetitive elements. Each cell was manually isolated and individually washed to avoid potential contaminants. Multiplex amplification allowed recognition of spurious amplification failures specific to particular amelogenin single-copy targets. The X-linked internal control and multiple Y-linked markers allowed recognition and exclusion of most aberrant samples, thus averting potential misdiagnosis. The optimized single-cell protocol reduced experimental sexing errors to < 2% (1/60), but also revealed potential pitfalls of single-cell analysis. With human triploid embryos, separate sampling of individual blastomeres provided concordant female or male signals. Slight modification adapted the procedure for diagnosis of biopsy material from blastocyst stage embryos, allowing separate analysis of multiple tubes containing multiple cells for improved reliability.

Amelogenin↗
PubMed1990

Neuropsychiatric lupus erythematosus, cerebral infarctions, and anticardiolipin antibodies.

Anticardiolipin antibody (aCL) has been associated with thromboembolic phenomena, including stroke, in certain patients with systemic lupus erythematosus (SLE); however, the relation between this antibody and the central nervous system manifestations of SLE is unknown. Serum samples and cerebrospinal fluid from five patients with SLE and acute central nervous system manifestations were assayed for the presence of aCL. Anticardiolipin antibody was identified in sera from four of the five patients but in none of the cerebrospinal fluid samples. Nuclear magnetic resonance imaging showed 'infarct-like' lesions in these four patients. This preliminary study suggests that a correlation between serum aCL and cerebral infarcts in central nervous system lupus may potentially exist. From this limited study it seems unlikely that aCL has a direct pathogenic role in the diffuse encephalopathy of acute central nervous system lupus.

Adolescent↗
PubMed1989

The prevalence of anticardiolipin antibodies in a healthy elderly population and its association with antinuclear antibodies.

The presence of anticardiolipin antibodies (aCL) has been associated with arterial and venous thrombotic events in connective tissue diseases. Previous investigations have suggested an increased incidence of aCL in the elderly population. We have studied the prevalence of aCL in large groups of 300 healthy elderly (mean age 70) and 543 younger subjects. aCL were determined by ELISA for the presence of IgG and IgM antibodies and was detected in 37 individuals (12%). This compared with an overall prevalence in a younger population of 2%. In addition, aCL was detected in 23% of elderly individuals who were also positive test for antinuclear antibodies (ANA). There was, however, no correlation with the presence of rheumatoid factor or lymphocytotoxic antibodies in this elderly group. Therefore, aCL have increased prevalence in an elderly population, and were associated with a positive test for ANA.

Adult↗
PubMedDate not supplied

EDI implementation needs cooperation.

Electronic Data Interchange is defined as all-vendor and equal access computer-transmitted business exchanges between hospitals and their trading partners. This column examines the current EDI implementation situation, which needs leadership not to stall out.

Computer Communication Networks↗