Reliable procedures to evaluate and repair crosstalk for bioanalytical MS/MS assays

Louis-Philippe Morin is a senior instrument application specialist at Algorithme Pharma, a CRO located in Laval, Canada. He has been working in the bioanalysis industry for the past 10 years where he became a subject matter expert in analytical instrumentation, especially in the MS field. His responsibilities in his current position are to optimize the workflow of the laboratory and to find new procedures, or approaches, to fix complex analytical problems. Louis-Philippe's expertise acquired over the years has led him to multiple publications regarding instrumentation. LC-MS/MS is the analytical technique of choice for the quantification of drugs in biological fluids. In recent years, MS/MS detection has been impacted by the rapid evolution of bioanalysis industry requirements. The availability of fast chromatographic systems, the demand for wider dynamic ranges and the extensive use of stable isotope-labeled internal standards in bioanalysis has pushed some triple quadrupole detectors to their limits of operation. Consequently, this situation has led to a re-evaluation of the problem of crosstalk as a potential cause of issues in bioanalysis. In this article, the importance of crosstalk verification on the MS/MS instrument will be demonstrated. Additionally, procedures to identify, evaluate and fix possible crosstalk issues during bioanalytical assays on MS/MS instruments are proposed.     

Effects of chronic renal failure on brain drug transporters in rats

Studies demonstrated that chronic renal failure (CRF) affects the expression and activity of intestinal, hepatic, and renal drug transporters. Such drug transporters are expressed in brain cells and at the blood-brain barrier (BBB), where they limit the entry and distribution of drugs in the brain. Perturbations in brain drug transporter equilibrium by CRF could lead to central drug toxicity. This study evaluates how CRF affects BBB drug transporters using a 5/6 nephrectomized rat model. Protein and mRNA expression of influx transporters [organic anion-transporting polypeptide (Oatp), organic anion transporter (Oat)] and efflux transporters [P-glycoprotein (P-gp), multidrug resistance-related protein (Mrp), breast cancer resistance protein (Bcrp)] were measured in CRF and control rat brain. Intracerebral accumulation of radiolabeled benzylpenicillin, digoxin, doxorubicin, and verapamil was used to evaluate BBB drug permeability. Protein expression of the transporters was evaluated in rat brain endothelial cells (RBECs) and astrocytes incubated with control and CRF rat serum. We demonstrated significant decreases (30-50%) in protein and mRNA levels of Bcrp, Mrp2 to -4, Oat3, Oatp2 and -3, and P-gp in CRF rat brain biopsies, as well as in astrocytes and RBECs incubated with CRF serum. These decreases did not correlate with in vivo changes because BBB permeability of benzylpenicillin was decreased by 30% in CRF rats, whereas digoxin, doxorubicin, and verapamil permeabilities were unchanged. It thus seems that even with decreased drug transporters, BBB integrity and function is conserved in CRF.     

Influencing clinical practice regarding the use of antiepileptic medications during pregnancy: Modeling the potential impact on the prevalences of spina bifida and cleft palate in the United States

Selected antiepileptic drugs (AEDs) increase the risk of birth defects. To assess the impact of influencing AED prescribing practices on spina bifida and cleft palate we searched the literature for estimates of the association between valproic acid or carbamazepine use during pregnancy and these defects and summarized the associations using meta-analyses. We estimated distributions of the prevalence of valproic acid and carbamazepine use among women of childbearing age based on analyses of four data sets. We estimated the attributable fractions and the number of children born with each defect that could be prevented annually in the United States if valproic acid and carbamazepine were not used during pregnancy. The summary odds ratio estimate for the association between valproic acid and spina bifida was 11.9 (95% uncertainty interval (UI): 4.0–21.2); for valproic acid and cleft palate 5.8 (95% UI: 3.3–9.5); for carbamazepine and spina bifida 3.6 (95% UI: 1.3–7.8); and for carbamazepine and cleft palate 2.4 (95% UI: 1.1–4.5) in the United States. Approximately 40 infants (95% UI: 10–100) with spina bifida and 35 infants (95% UI: 10–70) with cleft palate could be born without these defects each year if valproic acid were not used during pregnancy; 5 infants (95% UI: 0–15) with spina bifida and 5 infants (95% UI: 0–15) with cleft palate could be born without these defects each year if carbamazepine were not used during pregnancy. This modeling approach could be extended to other medications to estimate the impact of translating pharmacoepidemiologic data to evidence-based prenatal care practice. Published 2011 Wiley-Liss, Inc.     

Birthweight in infants conceived through in vitro fertilization following blastocyst or cleavage-stage embryo transfer: a national registry study

Purpose

In vitro fertilization (IVF) infants have lower birthweights than their peers, predisposing them to long-term health consequences. Blastocyst transfer (BT), at day 5–6 post-fertilization, is increasing in usage, partially due to improved pregnancy outcomes over cleavage-stage transfer (CT, day 2–3). Data to date, however, have been inconclusive regarding BT’s effects on birthweight.

Methods

Participants included all US autologous, single-gestation, fresh embryo transfer cycles initiated from 2007 to 2014 that resulted in a term infant (N?=?124,154) from the National Assisted Reproductive Technology Surveillance System. Generalized linear models including obstetric history, maternal demographics, and infant sex and gestational age were used to compare birthweight outcomes for infants born following BT (N?=?67,169) with infants born following CT (N?=?56,985) and to test for an interaction between transfer stage and single embryo transfer (SET).

Results

Infants born following BT were 6 g larger than those born following CT (p?=?0.04), but rates of macrosomia (RR 1.00, 95% CI 0.96–1.04) and low birthweight (LBW, RR 1.00, 95% CI 0.93–1.06) were not different between the groups. The interaction between SET and transfer stage was significant (p?=?0.02). Among SET infants, BT was associated with 19.26 g increased birthweight compared to CT (p?=?0.008).

Conclusions

The increase in birthweights identified following BT is unlikely to be clinically relevant, as there were no differences in rates of macrosomia or LBW. These findings are clinically reassuring and indicate that the increasing use of BT is unlikely to further decrease the on average lower birthweights seen in IVF infants compared to their naturally conceived peers.

     

Live birth and multiple birth rates in US in vitro fertilization treatment using donor oocytes: a comparison of single-embryo transfer and double-embryo transfer

Objective

To compare live birth rates (LBRs) and multiple birth rates (MBRs) between elective single-embryo transfer (eSET) and double-embryo transfer (DET) in donor oocyte in vitro fertilization (IVF) treatments in both a cycle-level and clinic-level analysis.

Methods

Donor oocyte IVF treatments performed by US IVF clinics reporting to the Centers for Disease Control and Prevention in 2013–2014 were included in the analysis. Primary outcomes included LBR and MBR. Secondary outcomes included gestational age at delivery (GA) and birth weight (BW) of offspring. These outcomes were evaluated on an individual cycle level as well as on the clinic level.

Results

In multivariable models, LBR did not change significantly as clinics utilized eSET more frequently. MBR decreased significantly as utilization of eSET increased, from 39% MBR in clinics that utilized eSET 0–9% of the time to 7% MBR in clinics that used eSET 70% of the time (P?<?.0001). Mean BW and GA of IVF-conceived offspring both increased as clinics utilized eSET more frequently (2778 to 3185 g [P?<?.0001] and 37.5 to 38.5 weeks [P?=?.02] for clinics with the lowest and highest eSET utilization, respectively).

Conclusions

US IVF clinics utilizing eSET with higher frequencies have clinically comparable LBRs and significantly lower MBRs than clinics with lower-frequency eSET utilization. Mean offspring BW and GA increased with higher eSET utilization, further confirming the improved safety of this practice.

     

The contribution of international medical graduates to diversity in the U.S. physician workforce: graduate medical education

PURPOSE: To describe the ethnicity/race and gender distribution of the international medical graduates (IMGs) qualified to enter graduate medical education (GME) and those who are actually in GME. METHODS: The Educational Commission for Foreign Medical Graduates (ECFMG) database and the American Medical Association's Masterfile provided ethnicity/race and gender data for the pool of IMGs qualified to enter GME (ECFMG certificants from 2000-2005) and those in GME in 2005. Data for U.S. medical graduates come from Association of American Medical Colleges' publications. RESULTS: Compared with USMGs, both the pool of available IMGs and those in graduate training have a larger percentage of Asians and Hispanics, a lower percentage of Blacks and American Indian/Pacific Islanders, and a much lower percentage of Whites. The groups had comparable percentages of women. CONCLUSIONS: International medical graduates provide much-needed diversity in GME. Since most IMGs remain in the U.S. after training, this diversity can lead to a richer training environment, increased access to health care, and better health care outcomes.