Biomedical subjects
Publications and source records attributed to V Stein.
The abduction orthosis presents a new variant in our treatment of Perthes' disease. The containment was obtained conservatively using this splint. This orthosis was tolerated very well by all children.
To provide the neurologist with a detailed and easily accessible neuroanatomical reference, we have developed a data bank including all relevant efferent and many afferent neuroanatomical pathways. NERVTRACK contains 4000 anatomical data items arranged in a tree-like manner reflecting structural and functional relationships. The program is able to address problems like the following: (1) What is the spinal, radicular, and peripheral innervation of a given muscle? (2) Which muscles are affected by a lesion of a given peripheral nerve, a root, or a segment of the spinal cord? (3) For a given muscle, what are synergists and antagonists, and which clinical test is applicable to evaluate its strength? NERVTRACK runs on IBM-compatible microcomputers, even on lap tops. It is a fast and comfortable reference for clinical practice and serves as a readily accessible teaching aid.
Numerous laboratory simulations and real-world events have demonstrated the thermal conversion of neat or high concentration of PCBs into the much more toxic PCDFs. Since millions of mineral oil transformers currently in service contain PCB concentrations in the 50 to 5000 ppm range, the thermal behavior of dilute PCB solutions is of practical and regulatory significance. In this work, neat Aroclor 1254 and 5000 ppm Aroclor 1254 in mineral oil were subjected to pyrolysis and combustion under a range of experimental conditions to define parameters resulting in maximal PCDF yields. The dependence of PCDF yield on Aroclor 1254 concentrations was then investigated in the 5000 to 50 ppm range. Combustion experiments demonstrated that PCDF yields expressed as micrograms PCDF/gram PCB were independent of concentration range, confirming that the process is kinetically first order in PCB. Much lower yields of PCDF were observed in the open tube pyrolysis experiments, as compared to combustion experiments and to earlier and concurrent sealed tube experiments. Slightly improved yields were observed in the pyrolysis experiments at lower concentrations, suggesting the existence of a PCB or PCDF destruction process of higher than first order kinetics. In all cases, yields expressed as micrograms PCDF/gram mixture were sharply and monotonically lower as concentrations decreased between neat or 5000 ppm Aroclor 1254 and 50 ppm Aroclor 1254.
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The effects of a solvent extract of the surface soil of the Love Canal chemical dump site, Niagara Falls, New York, and of a natural extract, or leachate, which is drained from the canal for treatment, on the maternal health and fetal development were determined in rats. The solvent extract, which was contaminated with 2,3,7,8-tetrachlorodibenzo-p-dioxin (2, 3,7,8-TCDD) at 170 ppb and numerous other chlorinated organic compounds with the primary identified components being the isomers of benzenehexachloride (BHC), was dissolved in corn oil and administered by gavage to pregnant rats at 0,25,75, or 150 mg crude extract/kg/day on Days 6-15 of gestation. A 67% mortality was observed at the highest dose. The rats were sacrificed on Day 20. Dose-related increases in relative liver weight accompanied by hepatocyte hypertrophy were observed at all dose levels. Fetal birthweight was decreased at 75 and 150 mg extract/kg/day. No major treatment-related soft tissue or skeletal malformations, except for delayed ossification, were observed. Based on literature values for BHC, all of the observed toxicity could be accounted for by the BHC contaminants of the extract. The crude organic phase of the leachate was administered to pregnant rats at 0,10,100, or 250 mg/kg/day as described above. Maternal weight gain decreased at 100 and 250 mg/kg/day, accompanied by 5 and 14% maternal mortality, and 1 and 3 dead fetuses, respectively. Early resorptions and the percentage of dead implants increased whereas fetal birthweights were decreased at 250 mg/kg/day. No major treatment-related soft tissue or skeletal malformations, except for delayed ossification, were observed. The primary components of the complex leachate by mass were tetrachloroethanes; however, 2,3,7,8-TCDD, which was present at 3 ppm, probably accounted for all the observed toxicity.
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Three female rhesus monkeys were given 14C-Mirex (5.23 mCi/mmol) iv (two animals) or po (one animal) in a dose of about 1 mg/kg for the purpose of determining the distribution and excretion of this polycyclic perchlorinated insecticide. Blood, plasma, urine, feces, and tissue samples were analyzed for 14C content. Monkeys were autopsied 23, 106, and 388 days after receiving 14C-Mirex. Following iv administration, plasma 14C showed a rapid decrease over the first few hours from the initial high levels. In the monkey given the compound orally, 14C first appeared in the plasma at 2 hr and reached a maximum at 5 hr. Thereafter, the decline in plasma radioactivity paralleled that found in the animals dosed i.v. After 2 weeks, the rate of decline in all animals was very slow. Excretion and tissue distribution of Mirex were essentially the same whether the compound was given po or iv. Less than 0.6% of the dose was found in the urine. 14C was excreted in the feces for the duration of the experiment with a maximum cumulative excretion of 7% after 388 days. At autopsy all tissues analyzed contained 14C. The highest concentration of 14C was found in the fat (estimated to contain at least 80% of the dose), followed by adrenal, peripheral nerve, thyroid, and skin. Chemical analysis of the nature of the radioactivity in fat and feces showed that at least 95% and was present as unchanged Mirex. There was a small amount of a compound more polar than Mirex in the feces, containing less than 3% of the fecal radioactivity.