An Incidental Finding of Retrocaval Ureter Causing Hydroureteronephrosis.

Retrocaval ureter is a rare, congenital anomaly of the inferior vena cava. Due to an abnormal process in embryogenesis, the ureter descends posterior to the inferior vena cava. Although the anomaly can be found in pediatric patients, it most commonly manifests symptoms between the third and fourth decade of life that are typically due to ureteric obstruction, such as hydronephrosis. Retrocaval ureter can be asymptomatic and may be the reason for unreported cases and low incidence in the world. In this case, we reviewed the record of a patient with the diagnosis of retrocaval ureter incidentally found during admission for a lower gastrointestinal bleed.

Acute Respiratory Distress in a Pediatric Patient With Prader-Willi and Moebius Syndromes.

Although acute respiratory infections or diseases such as asthma commonly cause respiratory distress in a pediatric patient, neuromuscular disorders must be considered as a possible etiology in patients with significant hypotonia, neurological deficits, and gross developmental delay. We present a case where a patient's lack of response to initial asthma exacerbation therapy led to a reconsideration of the original diagnosis and adaptation of the management plan. Our patient presented with a rare combination of two congenital disorders that cause hypotonia: Prader-Willi syndrome and Moebius syndrome. This case underlines the importance of considering atypical etiologies in pediatric patients with respiratory distress, while also illustrating the effectiveness of the atypical use of Dornase alfa in a patient with underlying neuromuscular disorders.

Discovery and targeted monitoring of polychlorinated biphenyl metabolites in blood plasma using LC-TIMS-TOF MS.

In the present work, the potential for rapid, targeted analysis of hydroxylated metabolites of polychlorinated biphenyls (OH-PCBs) in diluted human blood plasma using liquid chromatography coupled with trapped ion mobility spectrometry and TOF high resolution mass spectrometry (LC-TIMS-TOF MS) was evaluated. Experimental OH-PCB collisional cross section (CCSN2) and gas-phase candidate structures (<3% error) are reported for the first time and used, in addition to the LC retention time and accurate m/z, as OH-PCB identification features in order to increase the detection selectivity. The proposed LC-TIMS-TOF MS workflow combines a "dilute-and-shoot" sample preparation strategy, a robust liquid chromatography step, a high-resolving power mobility separation (R ~ 150-250) and high-resolution mass spectrometry (R ~ 30-40k) for the separation, identification and quantification of common OH-PCB isomers with limits of detection comparable to traditional workflows (e.g., LOD and LOQ of ~10 pg/mL and ~50 pg/mL, respectively). The higher selectivity and low detection limits provides multiple advantages compared to current methodologies that typically require long, labor-intensive preparation and/or derivatization steps prior to gas or liquid chromatography-mass spectrometry.

Analysis of isomeric opioids in urine using LC-TIMS-TOF MS.

In the present work, a fast separation, identification and quantification workflow based on liquid chromatography coupled to trapped ion mobility in tandem with mass spectrometry (LC-TIMS-MS) is described for the analysis of common isomeric drugs of abuse and their metabolites in human urine. In particular, the analytical performance of LC-TIMS-MS is shown for identification based on retention time, collision cross section and accurate mass for three sets of common isomeric opioids and their deuterated analogs in urine. The LC-TIMS-MS analysis provided limits of detection of 1.4-35.2 ng/mL with demonstrated linearity up to 500 ng/mL, enabling discovery and targeted monitoring (DTM) of opioids in urine, with high precision in retention times (RT) (< 0.3%), collision cross sections (CCS) (< 0.6%) and mass accuracy (< 1 ppm) across multiple measurements using external calibration. A good agreement was observed between theoretical and experimental CCS from candidate structures optimized at the DFT/B3LYP level. The need for complementary liquid and mobility separations prior to mass analysis is shown for the analysis of complex mixtures, with mobility resolving power of 80-130. The reproducibility and high speed of LC-TIMS-MS analysis provides a powerful platform for drug and metabolite screening in biological matrices with higher precision and confidence than traditional LC-multiple reaction monitoring (MRM) approaches.