Clinical experience with single-nucleotide polymorphism-based non-invasive prenatal screening for 22q11.2 deletion syndrome

OBJECTIVES

To evaluate the performance of a single-nucleotide polymorphism (SNP)-based non-invasive prenatal test (NIPT) for the detection of fetal 22q11.2 deletion syndrome in clinical practice, assess clinical follow-up and review patient choices for women with high-risk results.

METHODS

In this study, 21 948 samples were submitted for screening for 22q11.2 deletion syndrome using a SNP-based NIPT and subsequently evaluated. Follow-up was conducted for all cases with a high-risk result.

RESULTS

Ninety-five cases were reported as high risk for fetal 22q11.2 deletion. Diagnostic testing results were available for 61 (64.2%) cases, which confirmed 11 (18.0%) true positives and identified 50 (82.0%) false positives, resulting in a positive predictive value (PPV) of 18.0%. Information regarding invasive testing was available for 84 (88.4%) high-risk cases: 57.1% (48/84) had invasive testing and 42.9% (36/84) did not. Ultrasound anomalies were present in 81.8% of true-positive and 18.0% of false-positive cases. Two additional cases were high risk for a maternal 22q11.2 deletion; one was confirmed by diagnostic testing and one had a positive family history. There were three pregnancy terminations related to screening results of 22q11.2 deletion, two of which were confirmed as true positive by invasive testing.

CONCLUSIONS

Clinical experience with this SNP-based non-invasive screening test for 22q11.2 deletion syndrome indicates that these deletions have a frequency of approximately 1 in 1000 in the referral population with most identifiable through this test. Use of this screening method requires the availability of counseling and other management resources for high-risk pregnancies.

Use of human stem cell derived cardiomyocytes to examine sunitinib mediated cardiotoxicity and electrophysiological alterations

Sunitinib, an oral tyrosine kinase inhibitor approved to treat advanced renal cell carcinoma and gastrointestinal stroma tumor, is associated with clinical cardiac toxicity. Although the precise mechanism of sunitinib cardiotoxicity is not known, both the key metabolic energy regulator, AMP-activated protein kinase (AMPK), and ribosomal S 6 kinase (RSK) have been hypothesized as causative, albeit based on rodent models. To study the mechanism of sunitinib-mediated cardiotoxicity in a human model, induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) having electrophysiological and contractile properties of native cardiac tissue were investigated. Sunitinib was cardiotoxic in a dose-dependent manner with an IC₅₀ in the low micromolar range, observed by a loss of cellular ATP, an increase in oxidized glutathione, and induction of apoptosis in iPSC-CMs. Pretreatment of iPSC-CMs with AMPK activators AICAR or metformin, increased the phosphorylation of pAMPK-T172 and pACC-S79, but only marginally attenuated sunitinib mediated cell death. Furthermore, additional inhibitors of AMPK were not directly cytotoxic to iPSC-CMs up to 250 μM concentrations. Inhibition of RSK with a highly specific, irreversible, small molecule inhibitor (RSK-FMK-MEA) did not induce cytotoxicity in iPSC-CMs below 250 μM. Extensive electrophysiological analysis of sunitinib and RSK-FMK-MEA mediated conduction effects were performed. Taken together, these findings suggest that inhibition of AMPK and RSK are not a major component of sunitinib-induced cardiotoxicity. Although the exact mechanism of cardiotoxicity of sunitinib is not known, it is likely due to inhibition of multiple kinases simultaneously. These data highlight the utility of human iPSC-CMs in investigating the potential molecular mechanisms underlying drug-induced cardiotoxicity.

Expression of the Bacillus subtilis trpEDCFBA operon is influenced by translational coupling and Rho termination factor

The trp RNA-binding attenuation protein (TRAP) regulates expression of the Bacillus subtilis trpEDCFBA operon by transcription attenuation and translational control mechanisms. Both mechanisms require binding of tryptophan-activated TRAP to 11 (G/U)AG repeats in the trp leader transcript. trpE translational control involves formation of a TRAP-dependent RNA structure that sequesters the trpE Shine-Dalgarno (SD) sequence (the SD blocking hairpin). By comparing expression levels from trpE'-'lacZ translational fusions controlled by the wild-type leader or by a leader that cannot form the SD blocking hairpin, we found that translational control requires a tryptophan concentration higher than that required for transcription attenuation. We also found that inhibition of trpE translation by the SD blocking hairpin does not alter the stability of the downstream message. Since the coding sequences for trpE and trpD overlap by 29 nucleotides, we examined expression levels from trpED'-'lacZ translational fusions to determine if these two genes are translationally coupled. We found that introduction of a UAA stop codon in trpE resulted in a substantial reduction in expression. Since expression was partially restored in the presence of a tRNA suppressor, our results indicate that trpE and trpD are translationally coupled. We determined that the coupling mechanism is TRAP independent and that formation of the SD blocking hairpin regulates trpD translation via translational coupling. We also constructed a rho mutation to investigate the role of Rho-dependent termination in trp operon expression. We found that TRAP-dependent formation of the SD blocking hairpin allows Rho access to the nascent transcript, causing transcriptional polarity.

Angiotensin converting enzyme inhibitors: structure-activity profile of 1-benzazepin-2-one derivatives

The preparation of a series of 3-amino-2-oxo-2,3,4,5-tetrahydro-1H-1-benzazepine-1-acetic acid derivatives 5a-y by reductive amination of 2,3,4,5-tetrahydro-1H-1-benzazepine-2,3-dione (7) with L-amino acid derivatives is described. The compounds were tested for inhibition of angiotensin converting enzyme. The structure-activity profile of the series is discussed. Compound 5a was especially potent when tested in dogs for inhibition of angiotensin I pressor response, having an ID50 = 0.07 mg/kg po.

Synthesis and biological properties of (carboxyalkyl)amino-substituted bicyclic lactam inhibitors of angiotensin converting enzyme

Syntheses of the potent angiotensin converting enzyme inhibitor (3S)-1-(carboxymethyl)-3-[[(1S)-1-carboxy-3-phenylpropyl]amino]- 2,3,4,5-tetrahydro-1H-[1]benzazepin-2-one (4b; CGS 14831) and the related monoester prodrug (17a; CGS 14824A) are described together with preparative details for six- and eight-membered ring analogues. Inhibitory potencies and in vivo biological activity of the compounds are discussed. The data indicate that 17a has a biological profile comparable to that of enalapril.

Angiotensin converting enzyme inhibitors: N-substituted monocyclic and bicyclic amino acid derivatives

The synthesis of N-(3-mercaptopropionyl)-N-arylglycines (14a-x),- N-arylalanines (15a,b),-N-cycloalkylglycines (16a-k), and -1,2,3,4-tetrahydroisoquinoline-3-carboxylic acids (17a-d), -1,2,3,4-tetrahydroquinoline-2-carboxylic acids (18a-f), and -indoline-2-carboxylic acids (19a-k) is described. In vitro inhibition of angiotensin converting enzyme (ACE) is reported for each compound, and the structure--activity relationship for each series is discussed. The in vivo inhibition of ACE and antihypertensive effects of representative compounds from each series are discussed. The most potent compound, 19d, had an in vitro ACE IC50 of 2.6 X 10(-9) M and lowered blood pressure in spontaneous hypertensive rats 85 mm at a dose of 10 mg/kg po.