Development of a Multiplexed LC-MS/MS Assay for the Quantitation of Podocyte Injury Biomarkers Nephrin, Podocalyxin, and Podocin in Human Urine.

CKD is frequently diagnosed only after a significant progression. GFR is the most common indicator of kidney function but is limited in detecting early CKD cases and distinguishing glomerular, tubular, and global CKD. Aiming to provide a glomeruli specific biomarker assay, we developed a peptide immunoaffinity targeted mass spectrometry method for the quantitation of three podocyte specific proteins in human urine: nephrin, podocalyxin, and podocin.

Improving the Sensitivity of Protein Quantification by Immunoaffinity Liquid Chromatography─Triple Quadrupole Mass Spectrometry Using an Iterative Transition Summing Technique.

The desire to reach ever-diminishing lower limits of quantification (LLOQ) to probe changes in low abundance protein targets has led to enormous progress in sample preparation and liquid chromatography-tandem mass spectrometry (LC-MS/MS) instrumentation. To maximize signal and reduce noise, many approaches have been employed, including specific immunoaffinity (IA) enrichment and reducing the LC flow to the nanoflow (nLC) level; however, additional sensitivity gains may still be required. Recently, a technique termed "echo summing" has been described for small-molecular-weight analytes on a triple quadrupole (QqQ) MS where multiple iterations of the same, single selected reaction monitoring (SRM) transition are collected, summed, and integrated, yielding significant analyte dependent signal-to-noise (S/N) improvements.

Evaluation of an AAV9-mini-dystrophin gene therapy candidate in a rat model of Duchenne muscular dystrophy.

Duchenne muscular dystrophy (DMD) is an X-linked disease caused by loss-of-function mutations in the gene and is characterized by muscle wasting and early mortality. Adeno-associated virus-mediated gene therapy is being investigated as a treatment for DMD. In the nonclinical study documented here, we determined the effective dose of fordadistrogene movaparvovec, a clinical candidate adeno-associated virus serotype 9 vector carrying a human mini-dystrophin transgene, after single intravenous injection in a dystrophin-deficient (DMD) rat model of DMD.

Analysis of β-nerve growth factor and its precursor during human pregnancy by immunoaffinity-liquid chromatography tandem mass spectrometry.

β-Nerve growth factor (NGF) is a neurotrophin that plays a critical role in fetal development during gestation. ProNGF is the precursor form of NGF with a distinct biological profile. In order to investigate the role of NGF and proNGF in pregnant human females, a sensitive and selective immunoaffinity liquid chromatography-tandem mass spectrometry assay was developed and qualified to simultaneously measure the levels of total NGF (tNGF; sum of mature and proNGF) and proNGF using full and relative quantification strategies, respectively.

Single-Fiber Transducer Arrays for 3-D Ultrasound Computed Tomography: From Requirements to Results.

A potential method for future breast cancer screening is 3-D ultrasound computed tomography (USCT). The utilized image reconstruction algorithms require transducer characteristics fundamentally different from conventional transducer arrays, leading to the necessity of a custom design. This design has to provide random transducer positioning, isotropic sound emission as well as a large bandwidth and wide opening angle.