Citations

AbstractBackground: Newborn screening for maple syrup urine disease (MSUD) relies on finding increased concentrations of the branched-chain amino acids (BCAAs) leucine, isoleucine, and valine by tandem mass spectrometry (MS/MS). d-Alloisoleucine (allo-Ile) is the only pathognomonic marker of MSUD, but it cannot be identified by existing screening methods because it is not differentiated from isobaric amino acids. Furthermore, newborns receiving total parenteral nutrition often have increased concentrations of BCAAs. To improve the specificity of newborn screening for MSUD and to reduce the number of diet-related false-positive results, we developed a LC-MS/MS method for quantifying allo-Ile.Methods: Allo-Ile and other BCAAs were extracted from a 3/16-inch dried blood spot punch with methanol/H2O, dried under nitrogen, and reconstituted into mobile phase. Quantitative LC-MS/MS analysis of allo-Ile, its isomers, and isotopically labeled internal standards was achieved within 15 min. To determine a reference interval for BCAAs including allo-Ile, we analyzed 541 dried blood spots. We also measured allo-Ile in blinded samples from 16 MSUD patients and 21 controls and compared results to an HPLC method.Results: Intra- and interassay imprecision (mean CVs) for allo-Ile, leucine, isoleucine, and valine ranged from 1.8% to 7.4%, and recovery ranged from 91% to 129%. All 16 MSUD patients were correctly identified.Conclusions: The LC-MS/MS method can reliably measure allo-Ile in dried blood spots for the diagnosis of MSUD. Applied to newborn screening as a second-tier test, it will reduce false-positive results, which produce family anxiety and increase follow-up costs. The assay also appears suitable for use in monitoring treatment of MSUD patients.

Elasticity imaging is an emerging medical imaging modality. Methods involving acoustic radiation force excitation and pulse-echo ultrasound motion detection have been investigated to assess the mechanical response of tissue. In this work new methods for dynamic radiation force excitation and motion detection are presented. The theory and model for harmonic motion detection of a vibrating reflective target are presented. The model incorporates processing of radio frequency data acquired using pulse-echo ultrasound to measure harmonic motion with amplitudes ranging from 100to10,000nm. A numerical study was performed to assess the effects of different parameters on the accuracy and precision of displacement amplitude and phase estimation and showed how estimation errors could be minimized. Harmonic pulsed excitation is introduced as a multifrequency radiation force excitation method that utilizes ultrasound tonebursts repeated at a rate fr. The radiation force, consisting of frequency components at multiples of fr, is generated using 3.0MHz ultrasound, and motion detection is performed simultaneously with 9.0MHz pulse-echo ultrasound. A parameterized experimental analysis showed that displacement can be measured with small errors for motion with amplitudes as low as 100nm. The parameterized numerical and experimental analyses provide insight into how to optimize acquisition parameters to minimize measurement errors.

Abstract Rationale Adenotonsillectomy, the first line of treatment of sleep-disordered breathing (SDB), is the most commonly performed pediatric surgery. Predictors of the recurrence of SDB after adenotonsillectomy and its impact on cardiovascular risk factors have not been identified. Objectives Demonstrate that gain velocity in body mass index (BMI) defined as unit increase in BMI/year confers an independent risk for the recurrence of SDB 1 year after adenotonsillectomy. Methods Children with SDB and hypertrophy of the tonsils and a comparison group of healthy children were followed prospectively for 1 year. Measurements and Main Results Serial polysomnographies, BMI, and blood pressure were obtained before adenotonsillectomy and 6 weeks, 6 months, and 1 year postoperatively. Gain velocity in BMI, BMI and being African American (odds ratios, 4–6/unit change/yr; 1.4/unit and 15, respectively) provided equal amounts of predictive power to the risk of recurrence of SDB. In the group that experienced recurrence, systolic blood pressure at 1 year was higher than at baseline and higher than in children who did not experience recurrence. Conclusions Three clinical parameters confer independent increased risk for high recurrence of SDB after adenotonsillectomy: gain velocity in BMI, obesity, and being African American. A long-term follow-up of children with SDB and monitoring of gain velocity in BMI are essential to identifying children at risk for recurrence of SDB and in turn at risk for hypertension.

Background and Purpose— Recombinant-activated factor VII (rFVIIa) is an investigational treatment for intracerebral hemorrhage (ICH). We have evaluated the drug’s treatment effect based on time to treatment. Methods— ICH patients treated up to 4 hours from symptom onset were divided based on time to treatment: ≤3 hours (3H) and 3 to 4 hours (4H). Head CT was done at baseline and 24 hours. Outcome measures included: ICH growth at 24 hours, mortality, favorable outcome and discharge disposition. A cohort of nontreated matched ICH patients was used to asses the clinical efficacy. Results— Forty-six patients were treated with rFVIIa: 24 in the 3H group (range 70 to 180 minutes), 22 in the 4H group (range 181 to 300). One hundred and forty-eight patients formed the control group. Mean baseline ICH volume was 8.8 mL for 3H and 10.1 mL for 4H. Mean 24-hour volume was 9.3 mL for 3H (absolute increase 1.05 mL, relative increase 11.9%) and 11.5 mL for 4H (absolute increase 1.1 mL, relative increase 10.9%); P =0.47 is for the difference in relative increase. Mortality was 12.5% for 3H group, 13.6% for 4H, and 13.1% for the control. In the 3H group, 58.3% were discharged with a poor outcome, compared with 54.5% in 4H and 54.1% in the control. Thrombotic adverse events occurred in 11.1% of patients treated with rFVIIa. Conclusions— In our off-label with rFVIIa, we did not find evidence of a treatment effect based on time to treatment. Other criteria should be sought to identify patients who might benefit clinically from rFVIIa.

Background— Current risk models predict in-hospital mortality after either coronary artery bypass graft surgery or percutaneous coronary interventions separately, yet the overlap suggests that the same variables can define the risks of alternative coronary reperfusion therapies. Our goal was to seek a preprocedure risk model that can predict in-hospital mortality after either percutaneous coronary intervention or coronary artery bypass graft surgery. Methods and Results— We tested the ability of the recently validated, integer-based Mayo Clinic Risk Score (MCRS) for percutaneous coronary intervention, which is based solely on preprocedure variables (age, creatinine, ejection fraction, myocardial infarction ≤24 hours, shock, congestive heart failure, and peripheral vascular disease), to predict in-hospital mortality among 370 793 patients in the Society of Thoracic Surgeons database undergoing isolated coronary artery bypass graft surgery from 2004 to 2006. For the Society of Thoracic Surgeons coronary artery bypass graft surgery population studied, the median age was 66 years (quartiles 1 to 3, 57 to 74 years), with 37.2% of patients ≥70 years old. A high prevalence of comorbid conditions, including diabetes mellitus (37.1%), hypertension (80.5%), peripheral vascular disease (15.3%), and renal disease (creatinine ≥1.4 mg/dL; 11.8%), was present. A strong association existed between the MCRS and the observed mortality in the Society of Thoracic Surgeons database. The in-hospital mortality ranged between 0.3% (95% confidence interval 0.3% to 0.4%) with a score of 0 on the MCRS and 33.8% (95% confidence interval 27.3% to 40.3%) with an MCRS score of 20 to 24. The discriminatory ability of the MCRS was moderate, as measured by the area under the receiver operating characteristic curve (C-statistic=0.715 to 0.784 among various subgroups); performance was inferior to the Society of Thoracic Surgeons model for most categories tested. Conclusions— This model, which is based on 7 preprocedure risk variables, may be useful for providing patients with individualized, evidence-based estimates of procedural risk as part of the informed consent process before percutaneous or surgical revascularization.

Abstract Purpose: The purpose of the present study was to investigate whether it is possible to achieve truly systemic delivery of oncolytic reovirus, in immunocompetent hosts, using cyclophosphamide to overcome some of the barriers to effective intratumoral delivery and replication of i.v. injected virus. Experimental Design: I.v. delivery of reovirus was combined with different regimens of i.p. administered cyclophosphamide in C57Bl/6 mice bearing established s.c. B16 tumors. Intratumoral viral replication, tumor size, and survival were measured along with levels of neutralizing antibody (NAb) in the blood. Finally, differential toxicities of the virus/cyclophosphamide regimens were monitored through viral replication in systemic organs, survival, and cardiac damage. Results: Repeated i.v. injection of reovirus was poorly effective at seeding intratumoral viral replication/oncolysis. However, by combining i.v. virus with cyclophosphamide, viral titers of between 107 and 108 plaque-forming units per milligram were recovered from regressing tumors. Doses of cyclophosphamide that ablated NAb were associated with severe toxicities, characterized by viral replication in systemic organs—toxicities that are mirrored by repeated reovirus injections into B-cell knockout mice. Next, we restructured the dosing of cyclophosphamide and i.v. virus such that a dose of 3 mg cyclophosphamide was administered 24 h before reovirus injection, and this schedule was repeated every 6 days. Using this protocol, high levels of intratumoral viral access and replication (∼107 plaque-forming units per milligram tumor) were maintained along with systemically protective levels of NAb and only very mild, non–life-threatening toxicity. Conclusion: NAb to oncolytic viruses play a dual role in the context of systemic viral delivery; on one hand, they hinder repeated administration of virus but on the other, they provide an important safety mechanism by which virus released from vigorous intratumoral replication is neutralized before it can disseminate and cause toxicity. These data support the use of cyclophosphamide to modulate, but not ablate, patient NAb, in development of carefully controlled clinical trials of the systemic administration of oncolytic viruses.