PubMed Health⌕ Search

Biomedical subjects

A D Lighten

Publications and source records attributed to A D Lighten.

6 recordsLinked to original sources
PubMed1998

Routine addition of human insulin-like growth factor-I ligand could benefit clinical in-vitro fertilization culture.

Animal studies suggest that the insulin-like growth factors play an important role in preimplantation embryo development. Human preimplantation embryos express mRNA for insulin-like growth factor-I receptor (IGF-IR) but the ligand, insulin-like growth factor-I (IGF-I), is not expressed by the embryo until after implantation. We tested the hypothesis that IGF-I produced by the female reproductive tract may bind to these receptors, augmenting embryo survival, growth and development. Transcripts of mRNA for IGF1 were detected using reverse transcription-polymerase chain reaction in midcycle human Fallopian tube. Immunohistochemistry localized immunoreactive IGF-I to the cytoplasm of all the major structures of the Fallopian tube, with the most intense staining seen in the tubal epithelial lining. Maternally produced IGF-I was present in the fluid found in the human tube and uterus at concentrations of 8.0 and 10.9 nM respectively. Supplementation of culture medium with IGF-I increased the proportion of embryos developing to the blastocyst stage from 35% in controls to 60% in the presence of IGF-I. In addition the total number of cells in day 6 blastocysts was increased by 19% (64.44 versus 54.08% in control, not significant), due entirely to a statistically significant 59% increase (25 versus 15.75%, P = 0.020) in the number of cells in the inner cell mass. The effect of IGF-I was mediated through the IGF-I receptor. Immunocytochemistry using an alphaIR3 antibody confirmed the presence of IGF-I receptor in human blastocysts and the same antibody completely inhibited the stimulation of blastocyst formation by IGF-I. These data suggest that human preimplantation development is enhanced by maternal IGF-I. Mimicking this in-vivo paracrine relationship may improve clinical in-vitro embryo culture and IVF pregnancy rates.

Blastocyst↗
PubMed1997

Expression of mRNA for the insulin-like growth factors and their receptors in human preimplantation embryos.

Insulin, insulin-like growth factor-I (Igf-I), and insulin-like growth factor-II (Igf-II) are known to enhance growth in mouse preimplantation embryos. The addition of insulin, Igf-I, and Igf-II to mouse embryos in culture results in an increase in protein synthesis, cell number, and the proportion of embryos developing to the blastocyst stage. To study the role of the insulin-like growth factors in early human development, the timing of gene expression of insulin, IGF1, IGF2, and their receptors was analysed. Reverse transcription polymerase chain reaction (RT-PCR) was used to examine the presence of transcripts in preimplantation embryos. Following reverse transcription, strategically designed nested primers were used for amplification from cDNA. Transcripts for all three receptors (insulin receptor, IGF1R, IGF2R) were present in human oocytes and preimplantation embryos. However, of the ligands, only IGF2 transcripts were detected. This is consistent with expressed patterns seen in the mouse. As in the human, mouse Igf2 is the only ligand in the family expressed and has been shown to have an autocrine effect on preimplantation development. It has previously been shown that insulin and Igf-I are produced by the mouse maternal reproductive tract and have a paracrine effect on the preimplantation embryo. We speculate that a similar relationship exists in the human and that preimplantation development may be regulated by IGFs from both embryonic (IGF-II) and maternal (insulin and IGF-I) sources.

Animals↗
PubMed1996

Prenatal diagnosis by minimally invasive first-trimester transcervical sampling is unreliable.

OBJECTIVE: We investigated whether reliable prenatal diagnosis is possible from fetal cells harvested transcervically in first-trimester pregnancies. STUDY DESIGN: Fetal cells were obtained transcervically from 87 women undergoing pregnancy termination. Fetal gender was determined in 51 pregnancies with three different polymerase chain reaction techniques and in 36 pregnancies with fluorescent in situ hybridization. In known male pregnancies the number of male fetal cells present was also determined. RESULTS: Polymerase chain reaction detected male deoxyribonucleic acid in up to 79% of cases in male pregnancies and up to 45% of cases in female pregnancies. Fetal gender was correctly predicted in up to 72% of cases with fluorescent in situ hybridization. However, fetal cells were identified in < 40% of informative male pregnancies and were present in low numbers-0.7% to 3.4% in swabs and 4.4% to 24.8% in flushes. CONCLUSION: The use of fetal cells obtained by minimally invasive first-trimester transcervical sampling is unreliable for prenatal diagnosis.

Base Sequence↗
PubMed1995

Rhesus D typing.

Explore the source record for details and available documents.

Blood Grouping and Crossmatching↗
PubMed1995

Accuracy of prenatal determination of RhD type status by polymerase chain reaction with amniotic cells.

OBJECTIVE: Our purpose was to determine the accuracy of RhD typing by use of amniocytes obtained at amniocentesis in RhD-negative women. STUDY DESIGN: One hundred thirty-five RhD-negative women undergoing amniocentesis for management of suspected alloimmunization (n = 95) or routine second-trimester cytogenetic indications (n = 40) were studied. Amniocytes were then used as template to amplify specific portions of the Rh D and Rh CcEe genes by polymerase chain reaction. The fetal RhD type was confirmed by serologic techniques either after fetal blood sampling or cord blood samples at birth. RESULTS: Thirty-six fetuses were serologically typed as RhD negative and all 36 were typed RhD negative by polymerase chain reaction. Ninety-eight fetuses were serologically typed as RhD positive; of these, 96 were correctly typed as RhD positive and two were incorrectly typed as RhD negative, with an overall error rate of 1.4%. Both of the errors occurred in a single batch of six samples tested at the same time. In one of these cases the fetus had mild Rh alloimmune disease and required exchange transfusion at birth. In the second case the fetus had severe hydrops fetalis and died in utero at 28 weeks. Deoxyribonucleic acid isolated from fetal blood was tested with the same polymerase chain reaction technique after delivery, and in both cases the fetus was correctly typed as RhD positive. Deoxyribonucleic acid amplification repeatedly failed in one case. CONCLUSION: Prenatal fetal RhD typing by polymerase chain reaction with amniotic fluid cells is accurate and reliable. In sensitized pregnancies it allows early management of Rh disease and avoids invasive procedures in RhD-negative fetuses. In nonsensitized pregnancies it avoids the use of anti-RhD immunoglobulin after invasive procedures or during pregnancy. To eliminate the possibility of genetic and laboratory sources of errors, we suggest using different sets of primers at two different loci (e.g., exon 4 to 5 and exon 10).

Amniocentesis↗