Hydrogen peroxide contrast echocardiography

Several agents are used as echocardiographic contrast agents, but their unreliability discourages routine clinical use. Studies from the early 1960s suggest that dilute hydrogen peroxide (H₂O₂) is a safe intravascular agent. Its use was evaluated in contrast echocardiography. To obtain dense opacification reliably, H₂O₂ (3%) was passed through a sterile 0.2 μ Millipore filter and diluted with heparinized saline solution to make a 0.1 to 0.2% solution. A drop of blood was withdrawn from an indwelling peripheral venous needle into a syringe containing 0.5 to 2.0 ml of the dilute H₂O₂ and the contents injected. Studies in dogs, normal adults and 36 patients with noncyanotic congenital and acquired cardiac disorders produced dense opacification with no complications. In vitro mixture of H₂O₂ (0.3%) with leukocyte-poor blood or plasma produced only a few microbubbles, while addition to whole blood or buffy coat produced many, suggesting a role for leukocyte peroxidase. H₂O₂ contrast echocardiography is simple, inexpensive, and reliably provides dense, sustained opacification. This study and previous studies suggest that intravenous injection of 0.2% H₂O₂ can be done safely. Great caution should be exercised in patients with severe pulmonary hypertension or large right-to-left shunts because little clinical experience with H₂O₂ is available.     

High-dose etoposide and cyclophosphamide without bone marrow transplantation for resistant hematologic malignancy

Seventy-five patients with resistant acute leukemia or lymphoma received high-dose cyclophosphamide and etoposide to explore the activity of this combination in resistant hematologic malignancies, and to determine the maximum doses of these drugs that can be combined without bone marrow transplantation. Etoposide was administered over 29 to 69 hours by continuous infusion corresponding to total doses of 1.8 g/m2 to 4.8 g/m2. Cyclophosphamide, 50 mg/kg/d, was administered on 3 or 4 consecutive days total 150 to 200 mg/kg ideal body weight). At all dose levels myelosuppression was severe but reversible. Mucosal toxicity was dose-limiting with the maximum tolerated dose level combining etoposide 4.2 g/m2 with cyclophosphamide 200 mg/kg. Continuous etoposide infusion produced stable plasma levels that were lower than would be achieved after administration by short intravenous infusion, and this could explain our ability to escalate etoposide above the previously reported maximum tolerated dose. There were 28 complete (35%) and 12 partial (16%) responses. Median duration of complete response (CR) was 3.5 months (range 1.1 to 20+). Seventeen of 40 patients (42%) with acute myelogenous leukemia (AML) achieved CR, including 6 of 20 (30%) with high-dose cytosine arabinoside resistance. We conclude that bone marrow transplantation is not required after maximum tolerated doses of etoposide and cyclophosphamide. This regimen is active in resistant hematologic neoplasms, and the occurrence of CR in patients with high-dose cytosine arabinoside-resistant AML indicates a lack of complete cross-resistance between these regimens.     

Distributional Properties and Criterion Validity of a Shortened Version of the Social Responsiveness Scale: Results from the ECHO Program and Implications for Social Communication Research

Prior work proposed a shortened version of the Social Responsiveness Scale (SRS), a commonly used quantitative measure of social communication traits. We used data from 3031 participants (including 190 ASD cases) from the Environmental Influences on Child Health Outcomes (ECHO) Program to compare distributional properties and criterion validity of 16-item “short” to 65-item “full” SRS scores. Results demonstrated highly overlapping distributions of short and full scores. Both scores separated case from non-case individuals by approximately two standard deviations. ASD prediction was nearly identical for short and full scores (area under the curve values of 0.87, 0.86 respectively). Findings support comparability of shortened and full scores, suggesting opportunities to increase efficiency. Future work should confirm additional psychometric properties of short scores.