A novel organic solvent-based coupling method for the preparation of covalently immobilized proteins on gold

A novel organic solvent-based coupling method has been developed for the covalent immobilization of biological material to gold surfaces. The method employs the polar organic solvent anhydrous 2,2,2-trifluoroethanol as the reaction medium and involves dissolution of the protein (catalase) in the solvent allowing protein coupling to proceed under basic conditions in a dry organic environment. The advantage of this method is that protein attachment is favored over hydrolysis of the coupling reagent. We have shown qualitatively and quantitatively that following attachment to the gold surface a significant proportion of the enzyme catalase remains catalytically active (at least 20-31%).     

Radioimmunoassay of gastrin--dextran-coated charcoal method and polyethylene glycol method

Experiments were performed to determine whether the luteotropic effect of decidual tissue (DT) in the rat is attributable to the secretion of progesterone by DT, and the effects of ligation on utero-ovarian connections. No marked differences in progesterone levels in the uterine and jugular vein blood on Days 8 and 10 of pseudopregnancy in DT-bearing rats were voted. Pseudopregnant, DT-bearing rats receiving an injection of 2-Br-alpha-ergocryptine (CB-154) on Day 9 had markedly higher peripheral serum progesterone levels than in similarly treated hysterectomized pseudopregnant rats. The luteotropic action of DT was not altered by ligation and severing of the oviducts and/or the uterine-ovarian vasculature, or by the presence of 1 DT-bearing uterine horn contralateral to 1 remaining ovary. The findings support the notion of a luteotropic action of DT that is most likely exerted via hormonal pathways.     

Molecular barriers to biomaterial thrombosis by modification of surface proteins with polyethylene glycol

For cardiovascular biomaterials, thrombosis, thromboembolism and vascular graft occlusion are believed to be precipitated by the adsorption of proteins containing adhesive ligands for platelets. Polyethylene-glycol-diisocyanate (PEG-diisocyanate, 3400 MW) may potentially react with protein amines to form molecular barriers on adsorbed proteins on biomaterials, thereby masking adhesive ligands and preventing acute surface thrombosis. To test this notion, PE, PTFE, and glass microconduits were pre-adsorbed with fibrinogen and treated with PEG-diisocyanate, non-reactive PEG-dihydroxyl, or remained untreated. Following perfusion of 111In-labeled platelets in whole human blood for 1 min (wall shear rate = 312 s(-1)), PEG-diisocyanate treated surfaces experienced 96% (PE), 97% (PTFE) and 94% (glass) less platelet deposition than untreated surfaces. Similar reductions were seen for PEG-diisocyanate versus PEG-dihydroxyl treatment. Low shear perfusions of plasma for 1 h prior to blood contact did not reduce the inhibitory effect of PEG-diisocyanate. Platelet adhesion onto collagen-coated glass coverslips and platelet deposition onto preclotted Dacron were also reduced by treatment with PEG-diisocyanate (93 and 91%, respectively). Protein-reactive PEG may thus have utility in forming molecular barriers on surface-associated proteins to inhibit acute thrombosis on cardiovascular biomaterials.     

Effectiveness of polyethylene glycol antegrade gut lavage bowel preparation for colonoscopy--timing is the key!

PURPOSE: Polyethylene glycol gut lavage is an effective bowel preparation for colonoscopy. The quality of the preparation is not uniform however, and most studies report a rate of suboptimal cleansing of 10 percent or more. One of the possible reasons for a poor preparation is the length of time between the lavage and the examination. The aim of this study was to assess the effect of timing of polyethylene glycol gut lavage on the quality of the preparation achieved. METHODS: Patients referred for elective outpatient colonoscopy with afternoon appointments were randomized to take polyethylene glycol gut lavage either the same morning as their examination (Group 1) or the afternoon of the day before (Group 2). The colonoscopist was unaware of the preparation timing until after the examination was over. During the examination the endoscopist scored the quality of bowel preparation in the cecum, ascending colon, and transverse and left colon. Patient demographics and clinical data were recorded. RESULTS: There were 157 patients in Group 1 (colonoscopy complete in 152 patients) and 160 in Group 2 (colonoscopy complete in 159 patients). The groups were similar in age and gender, indication for colonoscopy, and previous colonic surgery. Patients who drank gut lavage on the morning of their colonoscopy had a greatly better preparation in all areas of the colon than the patients who took their preparation the night before. In the cecum, 97 Group 1 patients had an excellent preparation (vs. 14 Group 2 patients), 45 had a good preparation (vs. 103 Group 2 patients), and 10 had a fair preparation (vs. 33 Group 2 patients). In the ascending colon, numbers of patients with excellent, good, fair, and poor results were 103, 45, 5, and 0 for Group 1 and 12, 107, 32, and 7 for Group 2. Results in the transverse and left colons were 102, 50, 5, 0 and 93, 55, 7, 2 for Group 1 and 15, 116, 27, 5 and 18, 114, 24, 3 for Group 2, respectively. CONCLUSION: The timing of administration of polyethylene glycol-based gut lavage is a major determinant of the quality of the bowel preparation achieved.     

Meta-analysis and cost comparison of polyethylene glycol lavage versus sodium phosphate for colonoscopy preparation

Alpha-MSH, a proopiomelanocortin (POMC)-derived peptide, is known to be produced in the pituitary, the skin, and melanoma tumors and to possess many biological effects, mainly on melanocyte pigmentation and growth. Moreover, the melanocyte expresses adhesion molecules, including ICAM-1. The latter has been reported to play a role in melanoma spread and associated metastatic process. We conducted a study in order to evaluate the possible effect of MSH on ICAM-1 expression in human cultured malignant and normal melanocytes. Our data show that alpha-MSH inhibits ICAM-1 expression stimulated by TNF in a concentration-dependent manner, both at the protein and gene expression level. Ninety percent inhibition was obtained with 10 nM MSH, while 50% inhibition was achieved with 1 nM. Endogenous cAMP elevation with forskolin as well as an exogenous cAMP stable analogue (Sp-cAMPS) produced the same inhibitory effect. A screening of malignant melanocytes showed that inhibition of ICAM-1 expression could be achieved only in those cells expressing detectable MSH receptors and seemed to correlate with the number of binding sites. In conclusion, our data strongly suggest alpha-MSH as a potent inhibitor of ICAM-1 expression in malignant melanocytes acting through MSH receptor stimulation and subsequent cAMP increase.     

A simplified method for measuring fetal hemoglobin

Despite confirmation of the placental location by ultrasound examination, bloody tap during diagnostic and therapeutic amniocentesis may occur. If the blood originates from the fetus, such unfavorable complications as fetomaternal transfusion or maternal sensitization may result. Thus, it is necessary to determine immediatley the origin of the blood by the presence of fetal hemoglobin (HbF) in the specimen. To meet an urgent demand for a simpler and faster method for measuring HbF within a few minutes at bedside without requiring complicated procedures or instrumentation, a method has been developed which uses the alkali denaturation technic.     

Novel method for coupling of poly(ethyleneglycol) to carboxylic acid moieties of proteins

Lack of toxicity, excellent solubility and superb biocompatibility make polyethylene glycol (PEG) one of the most popular modifiers of biologicals. The most common method for attachment of PEG is based on modification of amino groups of proteins with methoxy- or succinimide-derivatives of PEG. In the case of proteins with amino groups important for biological activity, this modification can lead to inactivation of proteins. A new strategy for covalent attachment of PEG to carboxylic groups of proteins using O,O-bis-(2-aminopropyl)polyethylene glycol and carbodiimide/N-hydroxysuccinimide-mediated reaction was developed. The reaction is carried out under mild aqueous conditions. The attached PEG serves as a hydrophilic spacer for further bioconjungation with biomolecules and haptens. Lipase from Candida rugosa was used as a model protein. Characteristic data of the modified protein such as activity, isoelectric points and stability were compared with that of the unmodified protein.     

A simplified method for increasing mail-sorting efficiency.

Compared the number of pieces of mail sorted in a specified time for 2 groups of 10 undergraduates each. 1 group used standard post office department sorting techniques while the other used color-coded street names. Using a t test, the null hypothesis of no difference was rejected at the .05 level of confidence. The innovative technique was found to be superior to the conventional one. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A simplified method of nasolacrimal irrigation

A simplified method of nasolacrimal irrigation is presented. Use of the air cannula minimizes possible edema and trauma because it usually eliminates the need for dilation. In addition, its smaller diameter reduces the possibility of injury during the actual irrigation.     

Assessment of a method for measuring serum thyroxine by radioimmunoassay, with use of polyethylene glycol precipitation

We assessed the efficacy of a new thyroxine radioimmunoassay kit (Abott) in which polyethylene glycol is used to separate bound from free hormone. Mean serum thyroxine was 88 +/- 15 (+/-SD) microgram/liter for 96 normal persons. Results for hypothyroid and hyperthyroid persons were clearly separated from those for normal individuals. Women taking oral contraceptive preparations showed variable increases in their serum thyroxine values. The coefficient of variation ranged from 1 to 3% within assay and from 5.4 to 11% among different assays. Excellent parallelism was demonstrated between thyroxine values estimated by this method and those obtained either by competitive protein binding or by a separate radioimmunoassay for the hormone.     

A simplified method to measure the diffusion tensor from seven MR images

Analytical expressions of the diffusion tensor of water, D, and of scalar invariants derived from it, are given in terms of the intensities of seven diffusion-weighted images (DWIs). These formulas simplify the post-processing steps required in diffusion tensor imaging, including estimating D in each voxel (from the set of b-matrices and their corresponding DWIs), and then computing its eigenvalues, eigenvectors, and scalar invariants. In a study conducted using artifact-free DWIs with high diffusion weighting (bmax approximately 900 s/mm2, maps of Trace(D) and the Relative and Lattice Anisotropy indices calculated analytically and by multivariate linear regression showed excellent agreement in brain parenchyma of a healthy living cat. However, the quality of the analytically computed maps degraded markedly as diffusion weighting was reduced. Although diffusion tensor MRI with seven DWIs may be useful for clinical applications where rapid scanning and data processing are required, it does not provide estimates of the uncertainty of the measured imaging parameters, rendering it susceptible to noise and systematic artifacts. Therefore, care should be taken when using this technique in radiological applications.     

A convenient method for the preparation of hapten phosphoramidites

Total midsagittal area and seven subdivisions of the corpus callosum were measured on magnetic resonance images of 114 healthy boys and girls, aged 4 to 18. Striking variability of size was noted for all measures. Total midsagittal corpus callosum area increased in a robust and linear fashion from ages 4 to 18 (slope = 13.1 mm2/year, P = 0.0001 and slope = 11.1 mm2/year, P = 0.0001 for females and males, respectively). Posterior and mid regions demonstrated greater age-related changes than anterior regions with the rostrum and genu (anterior regions) having reached adult sizes in the youngest of our subjects. There were no significant effects of sex for any measures. These findings support anatomical studies indicating ongoing myelination of higher association areas throughout adolescence, but raise intriguing questions about anterior-posterior gradients of interhemispheric myelination.     

A pilot-plant method for the preparation of complex carbides

Conclusions A study was made of the conditions of preparation of the complex carbides Ta_0.4W_0.6C, V_0.4W_0.6C, Nb_0.4W_0.6C, and Ta_0.4Mo_0.6C on a pilot-plant scale. It was found that the optimum method for the preparation of these complex carbides consists in sintering, for 4 h, charges containing a simple carbide, tungsten (molybdenum), and carbon black in a resistance furnace with a graphite heating element at 2500° C for Ta_0.4W_0.6C, Nb_0.4W_0.6C and Ta_0.4Mo_0.6C and at 2200° C for V_0.4W_0.6C.Translated from Poroshkovaya Metallurgiya, No. 2 (146), pp. 92–95, February, 1975.     

A magnesium-thermic method for the preparation of metal borides

Powder Metallurgy and Metal Ceramics -     

Quantitative analysis of polyethylene glycol (PEG) in PEG-modified proteins/cytokines by aqueous two-phase systems

Covalent attachment of poly(ethylene glycol) (PEG) to proteins produces conjugates with altered/improved physicochemical and biological properties which depend upon the number of PEG chains linked. Quantification of the attached PEG is however not a trivial issue. The partition coefficient, K, of the PEG-protein conjugate in PEG/dextran two-phase systems provides a quantitative measure for the degree of modification. A linear relationship between log K and the number of PEG chains was observed in fractionated PEG-modified-granulocyte-macrophage colony stimulating factor conjugates having 1 to 3 substitutions. Furthermore, in mixtures of PEG-bovine-serum-albumin conjugates with increasing degrees of modification, a linear relationship was found between log K and n, the average substitution. The increment in log K per PEG chain added is protein specific and this suggests that the interactions between the PEG-protein conjugate and the polymers in the phase system are more complex than just a simple affinity of the PEG for the PEG-rich top phase. Increasing the polymer concentration in the phase system produces larger increments in log K per PEG molecule attached and the proportionality between log K and number of PEG molecules is only compromised for conjugates with high degree of substitution when partitioned in biphasic systems of high concentration of polymers.     

Use of polyethylene glycol for the microinjection of exogenous protein into cultured murine cells

Polyethylene glycol was applied to microinject two exogenous proteins: bovine serum albumin and non-histone protein derived from mouse spleen chromatin, into the mouse L-cells. The effectiveness of fusion of mammal (human, in the given case) erythrocytes in which hemoglobin is substituted for the protein under study was shown to be higher than when Sendai virus was used. The microinjected proteins preserve their specificity to subcellular structures.