One selection pressure shaping sequence evolution is the requirement that a protein fold with sufficient stability to perform its biological functions. We present a conceptual framework that explains how this requirement causes the probability that a particular amino acid mutation is fixed during evolution to depend on its effect on protein stability. We mathematically formalize this framework ...

abstract : avian influenza virus (aiv) infection is a major cause of influenza mortality in birds and can cause human mortality and morbidity. although the risk of infection with avian influenza virus (aiv) is generally low for most people, the pathogenic virus can cross the species barrier and acquires the ability to infect and be transmitted among the human population; therefore the rapid ide...

Equine infectious anemia (EIA) virus which was propagated on an equine dermal cell line agglutinated guinea pig erythrocytes. Viral fluids containing about 10(7.5) mean tissue culture infective doses/ml showed hemagglutinating (HA) titers ranging from 16 to 32 units/0.05 ml. Results of cesium chloride equilibrium density gradient centrifugation revealed that the hemagglutinin was inseparable fr...

The sensitive and tightly regulated feedback control system, thyroid gland autoregulation, and the large intrathyroidal and extrathyroidal storage pools of thyroid hormone serve to provide a constant supply of thyroid hormone to peripheral tissues in the face of perturbations imposed by the external environment, chemicals and drugs, and a variety of diseases processes. The thyroid is subject to...

Measurements of serum thyrotropin (TSH) concentrations were conducted in maternal and fetal blood during labor and delivery and the early postnatal and neonatal periods. Mean TSH concentration was significantly higher in cord blood (9.5 muU/ml) than maternal blood (3.9 muU/ml), a finding suggesting a fetal-maternal TSH gradient at term. Serum TSH concentration in the newborn increased rapidly t...

Serum thyrotropin (TSH) concentrations were measured serially in 14 heart-transplant recipients (group 1) and 21 patients undergoing coronary artery bypass surgery (group 2), all without thyroid disease, and randomly in 158 patients hospitalized for various other nonthyroidal illnesses, including 144 judged euthyroid (group 3), six with increased FT4 and (or) T3 (group 4), and eight classified ...

Escherichia coli isolates from diseased piglets (n = 89) and chickens (n = 71) in China were characterized for O serogroups, virulence genes, antimicrobial susceptibility, class 1 integrons, and mechanisms of fluoroquinolone resistance. O78 was the most common serogroup identified (63%) among the chicken E. coli isolates. Most isolates were PCR positive for the increased serum survival gene (is...

Differentiating between virulent and avirulent avian Escherichia coli isolates continues to be a problem for poultry diagnostic laboratories and the study of colibacillosis in poultry. The ability of a laboratory to conduct one simple test that correlates with virulence would simplify studies in these areas; however, previous studies have not enabled researchers to establish such a test. In thi...

We evaluated a new, highly sensitive time-resolved fluoroimmunoassay for thyrotropin (TSH) in serum. This direct immunometric "sandwich"-type assay involves two monoclonal antibodies against TSH, one immobilized, the other labeled with europium. Extremely high specific activity of the label and the use of labeled antibody in large excess make the method sensitive enough to measure TSH values fa...

We evaluated the effects of temperature and humidity on thyroid hormones (T4, T3) and thyrotropin (TSH) measured in blood spots dried on filter paper. RIAs for T4 and T3 blood spots were optimized to measure these analytes over the neonatal and euthyroid adult reference intervals. Sensitivities of the T3 and T4 assays were 0.5 and 10 nmol/L, respectively. A blood-spot immunoradiometric assay fo...