Liquid chromatography with ultraviolet absorbance detection of ethylenethiourea in blood serum after microwave irradiation as an auxiliary cleanup step

The report describes a method of deproteinizing serum that combines the action of acids with microwave irradiation. The acid concentration is ten times smaller than in the usual acid deproteinization method and the results are similar. The main advantages of the proposed method are the maintenance of the pH of the supernatant at around 5, and the reduction of the concentration of the deproteinizing agent. The procedure was applied to the determination of ethylenethiourea in serum samples by HPLC with spectrophotometric detection. Using 0.5 ml of serum, 0.04 microgram of ethylenethiourea were determined with recoveries between 89 and 109%.     

Outcomes and failure patterns in childhood craniopharyngiomas

Past studies of craniopharyngiomas in children have shown overall survival (OS) up to 95% at 5 years and 80% progression-free survival (PFS) at 5 years, although many of these series predate modern neuroimaging and current therapeutic management. Moreover, little mention has been made of failure patterns for craniopharyngioma in children. To obtain a contemporary assessment of outcome among pediatric craniopharyngioma patients, and also to determine the failure patterns for this tumor, we completed a retrospective study of a consecutive cohort of all children with craniopharyngioma diagnosed at the Johns Hopkins Hospital from 1980 to 1996. Resection was performed in 30 children, in 8 of whom gross total resection (GTR) was achieved. Initial treatment took the form of GTR followed by observation for 8, subtotal resection (STR) plus observation in 11, and STR followed immediately by radiotherapy in 8. The timing of radiotherapy following STR was unclear for 3. OS was 95.2% (SE= 4.7%) at 5 years, with only 2 children dying after 4 years from diagnosis. Five-year PFS was 59.4% (SE=10.2%). Before surgery, 19 children had visual loss and 15, endocrine deficits; after surgery, 21 children had visual loss and 29, endocrine deficits. Median time to relapse was 0.98 years (SD=2.5 years). Radiographic (n=4) and clinical (n=7) relapses did not differ in time to progression (P=0.32), but radiographic relapses were significantly associated with age at diagnosis less than 5 years (P=0.02). Degree of resection was not significantly associated with PFS (P=0.32) or with postoperative visual or endocrine deficits. Absence of calcification on diagnostic neuroimaging (n=8) was significantly associated with improved PFS [5-year PFS 100% vs. 42.9% (SE=14.7%), P=0.02], even when adjusted for extent of resection (P=0.03). Preoperative visual loss was predictive of postoperative visual loss (P=0.03). Survival for children diagnosed with craniopharyngioma in the current era is outstanding, even with relapse, although postoperative visual and endocrinological morbidities are high. Failures occurred both radiographically and clinically, typically in the first 3-4 years after surgery, suggesting a need for close surveillance initially with neuroimaging, particularly in younger children, and also clinical examination. The short times to relapse observed here may stem from a tendency to delay radiotherapy until recurrence. Lack of calcification at diagnosis is associated with a tendency to remain free of relapse.     

A single STAT recruitment module in a chimeric cytokine receptor complex is sufficient for STAT activation

We established a system of receptor chimeras that enabled us to induce heterodimerization of different cytoplasmic tails. Fusion constructs were created that are composed of the extracellular parts of the interleukin-5 receptor alpha and beta chains, respectively, and the transmembrane and intracellular parts of gp130, the signal transducing chain of the interleukin-6 receptor complex. In COS-7 transfectants we observed a dose-dependent interleukin-5-inducible STAT1 activation for which the presence of both the alpha and the beta chain chimera was needed. No STAT activity was detected if one of the cytoplasmic tails of the receptor complex was deleted, indicating that STAT activity resulted from a receptor dimer rather than from higher receptor aggregates. We further investigated whether dimerization of STAT1 depends on the juxtaposition of two STAT recruitment modules in a receptor complex. We show that a receptor dimer with only a single STAT1 docking site was still able to lead to STAT1 activation. This indicates that the formation of a paired set of STAT binding sites in a receptor complex is not the prerequisite for STAT factor dimerization. Our findings are discussed in view of alternative STAT dimerization models.     

Brain-derived neurotrophic factor rapidly enhances phosphorylation of the postsynaptic N-methyl-D-aspartate receptor subunit 1

Although neurotrophins have traditionally been regarded as neuronal survival factors, recent work has suggested a role for these factors in synaptic plasticity. In particular, brain-derived neurotrophic factor (BDNF) rapidly enhances synaptic transmission in hippocampal neurons through trkB receptor stimulation and postsynaptic phosphorylation mechanisms. Activation of trkB also modulates hippocampal long-term potentiation, in which postsynaptic N-methyl-D-aspartate glutamate receptors play a key role. However, the final common pathway through which BDNF increases postsynaptic responsiveness is unknown. We now report that BDNF, within 5 min of exposure, elicits a dose-dependent increase in phosphorylation of the N-methyl-D-aspartate receptor subunit 1. This acute effect occurred in hippocampal synaptoneurosomes, which contain pre- and postsynaptic elements, and in isolated hippocampal postsynaptic densities. Nerve growth factor, in contrast, caused no enhancement of phosphorylation. These results suggest a potential mechanism for trophin-induced potentiation of synaptic transmission.     

Robust, but transient expression of adeno-associated virus-transduced genes during human T lymphopoiesis

Recombinant adeno-associated viruses (rAAV) have been proposed to be gene transfer vehicles for hematopoietic stem cells with advantages over other virus-based systems due to their high titers and relative lack of dependence on cell cycle for target cell integration. We evaluated rAAV vector containing a LacZ reporter gene under the control of a cytomegalovirus (CMV) promoter in the context of primary human CD34+CD2- progenitor cells induced to undergo T-cell differentiation using an in vitro T-lymphopoiesis system. Target cells from either adult bone marrow or umbilical cord blood were efficiently transduced, and 71% to 79% CD2+ cells expressed a LacZ marker gene mRNA and produced LacZ-encoded protein after exposure to rAAV-CMV-LacZ. The impact of transgene expression on the differentiation of T cells was assessed by sequential quantitation of immunophenotypic subsets of virus-exposed cells and no alteration was noted compared with control. The durability of transgene expression was assessed and found to decay by day 35 with kinetics dependent on the multiplicity of infection. In addition, vector DNA was absent from CD4 or CD8 subselected CD3+ cells by DNA-polymerase chain reaction. These data suggest that rAAV vectors may result in robust transgene expression in primitive cells undergoing T-cell lineage commitment without toxicity or alteration in the pattern of T-cell differentiation. However, expression is transient and integration of the transgene unlikely. Recombinant AAV vectors are potentially valuable gene transfer tools for the genetic manipulation of events during T-cell ontogony but their potential in gene therapy strategies for diseases such as acquired immunodeficiency syndrome is limited.     

Purification and characterization of a cysteine protease produced by pathogenic luminous Vibrio harveyi

A histologic and biochemical comparison of interface membranes around femoral components of bipolar endoprostheses (n = 17) and total hip prostheses (n = 17) inserted without cement was conducted. The patients' profiles were similar in both groups with respect to age, sex, primary diagnosis, weight, and the interval between primary and revision arthroplasty. Macroscopically, marked circumferential abrasion of the polyethylene insert in the retrieved bipolar cups was noted. Histologic analysis revealed significantly larger amounts of polyethylene debris in the bipolar group. The membranes from the bipolar group also produced significantly greater amounts of prostaglandin E2 (P < .05). The inflammatory membranes associated with large amounts of polyethylene debris may have contributed to aseptic loosening and osteolysis in patients with a bipolar hip prosthesis.     

Corneal topographic evaluation of decentration in photorefractive keratectomy: treatment displacement vs intraoperative drift

Paraoxon (diethyl-p-nitrophenylphosphate) is the toxic, but non-mutagenic metabolite of the organophosphorus ester (OP) insecticide parathion. Although this agent has been used as a deacetylase inhibitor in many studies, we discovered a mutagenic synergy with paraoxon and plant-activated m-phenylenediamine or with direct-acting 2-acetoxyacetylaminofluorene in Salmonella typhimurium cells [Gichner T et al. (1996): Environ Mol Mutagen 27; 59-66]. In the present study, mammalian-activated m-phenylenediamine, o-phenylenediamine, p-phenylenediamine, benzidine, 2,3-diaminophenazine or 2-aminofluorene, as well as plant-activated benzidine or 2-aminofluorene expressed an elevated mutagenic potency when assayed with S. typhimurium strain YG1024 in the presence of paraoxon. Under non-toxic conditions, paraoxon amplified the S. typhimurium mutant yield induced by these aromatic amines between 1.9-fold and 8.4-fold. Spectrophotometric analysis demonstrated that the rate of degradation of 2-acetoxyacetylaminofluorene was not significantly different in phosphate buffer with or without paraoxon or with S. typhimurium cytosol with or without paraoxon. Also paraoxon-mediated mutagenic synergy does not appear to be due to a direct reaction with aromatic amines. Mutagenic synergy between aromatic amines and OP oxon products may be a cause of concern because people are chronically exposed to environmental and dietary aromatic amines, and a significant segment of the U.S. population tested positive for OP insecticide residues.     

Partial purification of embryotrophic factors from human oviductal cells

Embryotrophic factors from human oviductal cells were partially purified by liquid chromatographic methods. The conditioned medium from human oviductal cell culture was fractionated successively by concanavalin A (Con-A) affinity chromatography, ion-exchange chromatography and gel filtration. The presence of the embryotrophic activity in the eluates was determined by the stimulatory effects on the development of mouse embryos in vitro. The fraction that did not bind to the lectin Con-A possessed no embryotrophic activity. Ion-exchange chromatography separated the glycoproteins that bound to Con-A into five fractions. Three of them significantly enhanced blastulation as well as conceptus formation. Gel filtration further separated these embryotrophic fractions into five fractions. Three of them with molecular weights of 154 +/- 1, 164 +/- 0.2 and 207 +/- 0.3 kDa significantly stimulated blastulation of mouse embryos. The results of this study demonstrated that several embryotrophic factors with different biochemical properties contributed to the embryotrophic effect of the human oviductal cell/mouse embryo co-culture system.     

Prophylactic effect of bovine anti-Cryptosporidium hyperimmune colostrum immunoglobulin in healthy volunteers challenged with Cryptosporidium parvum

Bovine hyperimmune anti-Cryptosporidium colostrum immunoglobulin (BACI) decreases the intensity of Cryptosporidium parvum infection in vitro. We investigated the prophylactic effect of BACI in healthy adults challenged with C. parvum. After we established an oocyst dose that resulted in 100% infection in four volunteers (baseline group), 16 volunteers were randomized to receive (1) BACI prior to C. parvum challenge (BACI group) and a nonfat milk placebo 30 minutes later, (2) BACI prior to and 30 minutes after challenge (reinforced BACI group), or (3) nonfat milk placebo prior to and 30 minutes after challenge. Subjects received BACI (10 g) or nonfat milk placebo three times a day for a total of 5 days and were followed for clinical symptoms and oocyst excretion for 30 days. A trend toward less diarrhea (P = .08) was observed for subjects receiving BACI in comparison with occurrences in placebo recipients. Subjects receiving BACI or nonfat milk placebo had a 100-fold reduction in oocyst excretion as compared with excretion in the baseline group.     

PC钢棒生产工艺及其对钢棒性能的影响

对PC钢棒的生产工艺及其对钢棒性能的影响进行了初步探讨,对不同性能要求的钢棒热处理工艺提出了建议。