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We constructed a single-chain Fv antibody library that permits human complementarity-determining region (CDR) gene fragments of any germline to be incorporated combinatorially into the appropriate positions of the variable-region frameworks VH-DP47 and VL-DPL3. A library of 2 x 109 independent transformants was screened against haptens, peptides, carbohydrates, and proteins, and the selected antibody fragments exhibited dissociation constants in the subnanomolar range. The antibody genes in this library were built on a single master framework into which diverse CDRs were allowed to recombine. These CDRs were sampled from in vivo-processed gene sequences, thus potentially optimizing the levels of correctly folded and functional molecules, and resulting in a molecule exhibiting a lower computed immunogenicity compared to naive immunoglobulins. Using the modularized assembly process to incorporate foreign sequences into an immunoglobulin scaffold, it is possible to vary as many as six CDRs at the same time, creating genetic and functional variation in antibody molecules.

BackgroundPhthalates may pose a risk for perinatal developmental effects. An important question relates to the choice of suitable biological matrices for assessing exposure during this period.ObjectivesThis study was designed to measure the concentrations of phthalate diesters or their metabolites in breast milk, blood or serum, and urine and to evaluate their suitability for assessing perinatal exposure to phthalates.MethodsIn 2001, 2–3 weeks after delivery, 42 Swedish primipara provided breast milk, blood, and urine samples at home. Special care was taken to minimize contamination with phthalates (e.g., use of a special breast milk pump, heat treatment of glassware and needles, addition of phosphoric acid).ResultsPhthalate diesters and metabolites in milk and blood or serum, if detected, were present at concentrations close to the limit of detection. By contrast, most phthalate metabolites were detectable in urine at concentrations comparable to those from the general population in the United States and in Germany. No correlations existed between urine concentrations and those found in milk or blood/serum for single phthalate metabolites. Our data are at odds with a previous study documenting frequent detection and comparatively high concentrations of phthalate metabolites in Finnish and Danish mothers’ milk.ConclusionsConcentrations of phthalate metabolites in urine are more informative than those in milk or serum. Furthermore, collection of milk or blood may be associated with discomfort and potential technical problems such as contamination (unless oxidative metabolites are measured). Although urine is a suitable matrix for health-related phthalate monitoring, urinary concentrations in nursing mothers cannot be used to estimate exposure to phthalates through milk ingestion by breast-fed infants.

Dietary uptake and effects of decabromodiphenyl ether (DeBDE), a widely used flame retardant, were studied in rainbow trout. Fish were fed for 16, 49, or 120 days with control or DeBDE-treated food (7.5−10 mg of DeBDE/kg of body weight/day). One group was fed DeBDE for 49 days and then control diet for 71 days to study depuration. Chemical analyses were performed using GC/MS(ECNI). Several physiological and biochemical variables were also measured. DeBDE concentrations in muscle increased from <0.6 ng/g of fresh weight to 38 (±14) ng/g after 120 days. Corresponding liver concentrations were <5 and 870 (±219) ng/g of fresh weight. Several hexa- to nonabromodiphenyl ethers, present in both liver and muscle, increased in concentration with exposure length. These congeners originate from metabolism of DeBDE and/or selective uptake of minor components in the DeBDE product. After depuration, DeBDE concentrations declined significantly, but concentrations of some lower brominated congeners were unaffected. Liver body index and plasma lactate concentrations were higher in fish exposed for 120 days and in the depuration group, indicating delayed chronic effects, possibly from lower brominated congeners. DeBDE uptake (0.02−0.13%) and possible metabolism seem not to be major sources of tetra- and pentabromodiphenyl ethers found in wild fish.

Fish and sediments from several places along the Swedish River Viskan, sampled in 1995, were analyzed for polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HBCD). The samples were collected up‐ and downstream from several possible point sources (textile industries) for these compounds. Tetrabromodiphenyl ethers (TeBDEs), pentabromodiphenyl ethers (PeBDEs), and decabromodiphenyl ether (DeBDE [BDE209]) were found in sediment. Tetrabromodiphenyl ethers and PeBDEs were also found in fish. Hexabromocyclododecane was identified in sediment and fish. Large fish to sediment ratios for TeBDE, PeBDEs, and HBCD indicate that these are highly bioavailable, whereas BDE209 seems not to be as bioavailable. The lowest PBDE and HBCD levels were found upstream of the industries and concentrations generally increased progressively further downstream as more industries were passed. This is in agreement with earlier investigations of PBDEs in fish from the same river. Many brominated compounds are photolabile, which can complicate their analysis. Under the conditions used in this investigation it was observed that BDE209 in a solvent that was subject to the clean‐up procedure partly decomposed to compounds with shorter retention times, whereas BDE209 seemed to be stable in the sample extracts. Another matrix effect could be observed in the increased sensitivity obtained for some of the investigated compounds in fish and sediment extracts as compared to standard solutions. This effect may obscure analytical results obtained with electron capture mass spectrometric detections.