A non-invasive test for prenatal diagnosis based on fetal DNA present in maternal blood: a preliminary study.

Background: Use of free fetal DNA to diagnose fetal chromosomal abnormalities has been hindered by the inability to distinguish fetal DNA from maternal DNA. Our aim was to establish whether single nucleotide polymorphisms (SNPs) can be used to distinguish fetal DNA from maternal DNA-and to determine the number of fetal chromosomes-in maternal blood samples.

Methods: Formaldehyde-treated blood samples from 60 pregnant women and the stated biological fathers were analysed.

Methods to increase the percentage of free fetal DNA recovered from the maternal circulation.

Context: Noninvasive prenatal diagnostic tests using free fetal DNA provide an alternative to invasive tests and their attendant risks; however, free fetal DNA exists in the maternal circulation at low percentages, which has hindered development of noninvasive tests.

Objective: To test the hypothesis that using formaldehyde to reduce cell lysis could increase the relative percentage of free fetal DNA in samples of maternal blood.

Design, Setting, And Patients: The first phase of the study was conducted from January through February 2002 at a single US clinical site; 2 samples of blood were collected from each of 10 pregnant women, and the percentage of free fetal DNA in formaldehyde-treated and untreated samples was determined.

A new subunit of the cyclic nucleotide-gated cation channel in retinal rods.

Retinal rods respond to light with a membrane hyperpolarization produced by a G-protein-mediated signalling cascade that leads to cyclic GMP hydrolysis and the consequent closure of a cGMP-gated channel that is open in darkness. A protein that forms this channel has recently been purified from bovine retina and molecularly cloned, suggesting that the native cGMP-gated channel might be a homo-oligomer. Here we report the cloning of another protein from human retina which has only about 30% overall identity to the rod channel subunit.

Human rod photoreceptor cGMP-gated channel: amino acid sequence, gene structure, and functional expression.

Phototransduction in retinal rods involves a G-protein-mediated signaling cascade that leads to cGMP hydrolysis and the closure of a cGMP-gated channel. This channel has recently been purified from bovine retina and molecularly cloned (Kaupp et al., 1989).

Primary structure and functional expression of a cyclic nucleotide-activated channel from olfactory neurons.

Odorant signal transduction occurs in the specialized cilia of the olfactory sensory neurons. Considerable biochemical evidence now indicates that this process could be mediated by a G protein-coupled cascade using cyclic AMP as an intracellular second messenger. A stimulatory G protein alpha subunit is expressed at high levels in olfactory neurons and is specifically enriched in the cilia, as is a novel form of adenylyl cyclase.

Angiotensin II increases spontaneous contractile frequency and stimulates calcium current in cultured neonatal rat heart myocytes: insights into the underlying biochemical mechanisms.

The effect of angiotensin II on cultured neonatal rat heart myocytes was studied by measuring changes in cell length, the magnitude and kinetics of the calcium current, and changes in cyclic adenosine 3',5'-monophosphate (cAMP) and phosphoinositide metabolism. Spontaneous beating frequency of multicellular networks was increased by angiotensin II with a maximal increase of 100% above control values at concentrations of 5 nM or greater. The half-maximal response occurred at 0.

Phorbol ester increases calcium current and simulates the effects of angiotensin II on cultured neonatal rat heart myocytes.

The effects of increased protein kinase C activity were studied in neonatal rat myocytes grown in primary culture. The changes in mechanical and electrical behavior, as well as protein phosphorylation, that followed the apparent activation of protein kinase C by the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) were examined. As spontaneous beating frequency was increased minimally by 10 nM TPA and by 100% with 85 nM TPA, shortening amplitude, shortening velocity, and relaxation velocity decreased concomitantly.