Environment affects amino acid preference for secondary structure

Three equivocal amino acid sequences were synthesized that are predicted to be alpha-helical from amino acid preference but are found to be primarily beta-strand from x-ray diffraction of their respective proteins. In some solvent systems we recover the alpha-helical structure predicted by amino acid preference, whereas in other systems we mimic the interior of the protein and produce a beta-strand. These results are experimental proof that the environment is important in determining the secondary structure formed by an amino acid sequence; therefore schemes that predict secondary structure from amino acid sequence alone can never be totally successful.

[Investigation on high risk factors of neonatal necrotizing enterocolitis]

In order to evaluate the factors in high-risk neonatal necrotizing enterocolitis (NEC) and predict the prognosis of NEC, a retrospective analysis of 32 factors was made in 42 neonates with NEC. The cases were divided into a low-risk (survival) group and a high-risk (death) group. Of 32 factors compared between these two group, eight were found to be of significance in evaluating the severity of NEC, and six of them were used in the development of a NEC scores (1) number of days before beginning of artificial feeding; (2) neonatal asphyxia or distress; (3) immature form in WBC differential; (4) CO2 combining power; (5) abdominal tenderness; (6) presence of portal vein air (PVA). All laboratory values and physical and radiographic signs were collected during initial presentation of NEC. Neonates with a score of 3 or more are at an increased risk of developing severe NEC with a 83% mortality.

[Various methods for purification of urine Tamm-Horsfall protein]

The measurements of serum, urine Tamm-Horsfall protein (THP) and its antibody are essential to the early diagnosis of tubulointerstitial diseases and acute rejection after renal transplantation. The purification of THP proves to be the key procedure for the production of diagnostic kit. Once, twice and three times salt precipitation with 0.58 mol/L NaCl and chromatography with Sephadax G-200 were adopted to purify urine THP. Enzyme immunoassay was used to detect the antigenicity of the products, SDS-PAGE to determine the molecular weight (MW) and the electrophoretic purity (EP), Beckman DU-7 model spectrophotometer to scan the ultraviolet absorption spectrum. Evaluation of the four methods was based on the purity and the antigenicity of the produced THP, the output, the complexity of procedure, and the cost of required materials. Results show that the MW of THP is 93.0 kd; the ultraviolet absorption maximum is at lambda = 278 nm; the outputs are 7.5, 5.5, 3.8, and 0.4 mg/L; the concentrations of THP with antigenicity are 65%, 75%, 98% and 100%, respectively, and the EPs of three times salt precipitation and chromatography are better. It is concluded that three times salt precipitation should be recommended because of its excellence in purity and antigenicity of the produced THP, the simplicity of manipulation, and the cheapness of the materials needed.