SummaryAntithrombin III (AT-III) was isolated by heparin affinity chromatography from adult venous and newborn term and preterm umbilical cord blood. The purified proteins were compared by SDS-PAGE, rocket immuno-electrophoresis, protein concentration by microbiuret relative to optical density at 280 nm, heparin cofactor specific activity, progressive neutralization of thrombin and factor Xa at 37°C and pH related antithrombin kinetics. The structural evaluations revealed a fetal AT-III of molecular weight, charge and electrophoretic migration indistinguishable from adult AT-III. The functional studies showed that, on an equimolar basis, the rates of thrombin and Xa interactions with fetal AT-III were as rapid as those with adult AT-III. The catalytic rates of various concentrations of heparin were also equal. The newborn infant, therefore, displays a quantitative but not qualitative deficiency of AT-III.

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A 29-yr-old white female has suffered from recurrent venous thromboses over the last 12 yr. Plasma antithrombin III (AT-III) levels were 48% of normal by immunoelectrophoresis and 56% by chromogenic assay. Three of four siblings and the father had similar AT-III levels without associated venous thromboses. Heparin-Sepharose chromatography demonstrated normal behavior of the patient's AT-III. Her purified AT- III could not be distinguished from AT-III purified from a normal control either by SDS polyacrylamide gel electrophoresis or by crossed immunoelectrophoresis, and the heparin cofactor activity and the progressive antithrombin activity of both AT-III samples were identical. Turnover studies were made in the patient using her own purified AT-III labeled with 131I, (*I). The results did not differ significantly from studies made with autologous *I-AT-III in two normal control women. Her fractional breakdown rate of 0.54 total plasma AT- III per day compared with 0.45 and 0.52 in the controls. These studies indicate that the patient synthesizes a normal AT-III molecule at half normal rates.

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This paper presents the results of a series of tests run on specimens of a low-plasticity clay (LL = 34, PI = 12) with a calcite content of approximately 25 percent by weight. The naturally occurring clay tested is from playa lake deposits in southern Idaho. This test program investigated the strength of labratory compacted specimens as a function of time and curing conditions. Specimens of 33.3 mm (1.3 in.) diameter were prepared using the Harvard miniature kneading compaction device. Specimens for strength testing were prepared with water contents at optimum (16.5 percent) and 4.5 percent dry of optimum (12 percent). The latter value is approximately the water content of the material as-sampled. After compaction, specimens were allowed to cure under either air-dry or moist conditions prior to strength testing. The unconfined strength [ASTM Tests for Unconfined Compressive Strength of Cohesive Soil (D 2166-66)] of replicated specimens was measured at times ranging from several minutes to three months after compaction. The results of these tests showed substantial strength gain with loss of moisture. Most of the increase in strength was experienced within the first 8 h of air-drying while the increase was more gradual for the moist cured specimens. The specimens compacted at optimum water content exhibited higher strengths than those compacted dry of optimum after curing. In the as-molded condition, however, the dry-of-optimum specimens were stronger.