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PubMed1977

Chromatographic determination of aromatic hydrocarbons in ambient air.

A gas chromatographic method has been developed for the determination of aromatic hydrocarbons in solvent mixtures. Bulk solvents and charcoal tube air samples may be analyzed. The procedure utilizes the unique separation characteristics of a gas chromatographic column containing a highly selective stationary liquid phase, N,N-bis (2-cyanoethyl) formamide. The interfering oxygenated solvents are extracted using 75 percent H2SO4. An 11-foot, 35 percent CEF column may be used to qualitatively analyze the lower boiling aromatic hydrocarbons (benzene, toluene, xylenes). Total or specific aromatics are then quantitated using a 3-foot, 35 percent CEF column with an internal standard. Applications of liquid chromatographic concepts to this analysis were also investigated.

Air Pollutants↗
PubMed2001

DMF effects on frozen gander semen.

1. The objective of the present study was to determine if the age of semen donors affects the susceptibility of spermatozoa to freezing and whether DMF (dimethyl formamide) inseminated with freeze-thawed gander semen decreases fertility. 2. Semen was collected 3 times a week by dorsal-abdominal massage from two groups of White Italian ganders: 3 and 2 years-old. Both samples were diluted, mixed with DMF to a final concentration of 6% (v/v), pre-frozen and transferred into LN2. 3. Twice a week, the freeze-thawed semen was used for insemination of two groups of geese at a dose of 4 to 16 million live morphologically normal spermatozoa. One group was inseminated immediately after thawing, the 2nd with semen from which the DMF was removed. 4. Donor age had no effect on the spermatozoa's aptitude for freezing. The differences in quality and quantity of fresh and freeze-thawed semen produced by 3 or 2 year-old ganders were not significant. 5. The presence of DMF in the inseminated freeze-thawed semen did not affect the reproductive efficiency of spermatozoa. The fertility rate obtained with semen inseminated either with or without the cryoprotectant averaged 92.9% and 87.2% respectively. The hatchability of set eggs was 81.1% and 79.9% and, the hatchability of fertile eggs amounted to 87.3% and 89.4%.

Age Factors↗
PubMed1982

Improved preparation of poly(A) Sepharose and the isolation of oligo(U) containing heterogeneous nuclear RNA from Friend erythroleukemic cells.

When poly(A) sepharose (prepared according to previously published procedures) was stored in aqueous buffer at 4 degrees C for 5 days or longer, it bound nonspecifically a high percentage of the input RNA which could not be eluted with formamide. We have found that treatment with ethanolamine, followed by dehydration with ethanol yielded poly(A) sepharose which was stable for many months and possessed a low degree of nonspecific binding. Chromatography on poly(A) sepharose permitted the specific isolation of that fraction of Friend erythroleukemic cell heterogeneous nuclear RNA (hnRNA) which contained oligo(U) sequences. Approximately 10% of the hnRNA which contained a poly(A) sequence [poly(A+)] also contained an oligo(U) sequence. Interestingly, prior HCHO denaturation of the hnRNA enhanced binding of the poly(A+) oligo(U+) hnRNA to poly(A) sepharose by tenfold. This suggested that the oligo(U) sequence may be in a region with secondary structure, possibly an intramolecular duplex with the 3' poly(A). Friend cell oligo(U) sequences ranged from 20 to 50 nucleotides in length and, thus, were similar to the oligo(U) sequences which heretofore had only been shown to be present in HeLa cell hnRNA. These results established that rodent cell hnRNA contain oligo(U) sequences and demonstrate, for the first time, that hnRNA containing both a poly(A) and an oligo(U) sequence can be separated from other classes of hnRNA. In addition, conditions are presented for the removal of HCHO from nucleic acid.

Animals↗
PubMed2006

Occurrence of ivermectin in bovine milk from the Brazilian retail market.

High-performance liquid chromatography (HPLC) with fluorescence detection was used for the quantification of ivermectin residues in bovine milk intended for human consumption. After liquid-liquid extraction of ivermectin and purification of the extract, the compound was derivatized with 1-methylimidazol in N,N-dimethyl formamide to form a fluorescent derivative, which was separated by HPLC, using reversed-phase C18, with methanol : water (96 : 4 v/v) mobile phase at a flow rate 0.7 ml min-1. The excitation and emission wavelengths of the fluorescence detector were adjusted at 360 and 470 nm, respectively. The linearity of the method was in the range 10-100 ng ivermectin ml-1. Based on a sample of 5.0 ml, the limit of detection and the limit of quantification for ivermectin in milk were 0.6 and 2 ng ml-1, respectively. The recovery rate varied from 76.4 to 87.2%, with an average of 77.9 +/- 3.2%, at four fortification levels. The inter-day precision of the method was 13% (n = 5). Of 168 samples analysed, 17.8% contained ivermectin above the limit of quantification. Nevertheless, none of the samples contained ivermectin above the maximum residue limit (10 ng ml-1) established by the Brazilian Ministry of Agriculture.

Animals↗
PubMed2007

Synthesis and evaluation of molecularly imprinted polymers as sorbents of moniliformin.

Moniliformin is a low molecular weight mycotoxin that has worldwide potential to contaminate cereal grains. Although several traditional methods have been developed to detect moniliformin, the lack of anti-moniliformin antibodies has created a need for materials that recognize moniliformin at the molecular level through a binding mechanism. To address this issue, the authors synthesized molecularly imprinted polymers that bind moniliformin. Imprinted and non-imprinted polymers were evaluated by equilibrium binding assays and moniliformin concentrations were measured by LC analysis using ultraviolet light detection. Successful polymers were imprinted with toxin analogues as the templates; non-imprinted polymers exhibited minimal binding in acetonitrile under the assay conditions. Selected imprinted polymers also bound moniliformin in ethanol, methanol and dimethyl formamide. Significant differences in moniliformin binding by the polymers were dependent on polymer composition, and these differences were highly dependent on the template used to imprint the polymer. Polymers were further evaluated as sorbents for molecularly imprinted solid-phase extraction (MISPE), and an imprinted polymer was used for preconcentration and clean-up of a moniliformin spiked corn extract.

Chromatography, Liquid↗
PubMedDate not supplied

Biodistribution characteristics of mannosylated and fucosylated O/W emulsions in mice.

Cell-specific drug delivery is one of the most promising strategies for improving therapeutic efficiency and minimizing systemic toxicity. Carrier systems devoted to receptor-mediated targeting need to be developed. In the case of liver-non-parenchymal cell-specific targeting systems, glycosylated emulsions have been developed as carriers for lipophilic drugs and/or peptides. This present study demonstrates the in vivo disposition behaviour and pharmacokinetic characteristics of mannosylated (Man-) and fucosylated (Fuc-) emulsions incorporated with cholesten-5-yloxy-N-(4-((1-imino-2-D-thiomannosylethyl)amino)alkyl)formamide (Man-C4-Chol) and its fucosylated derivatives (Fuc-C4-Chol), respectively. Man- (or Fuc-) emulsions are composed of soybean oil, EggPC and Man-C4-Chol (or Fuc-C4-Chol) in a weight ratio of 70:25:5. After intravenous administration to mice, these two types of [(3)H]cholesteryl hexadecyl ether (CHE)-labelled glycosylated emulsions were rapidly eliminated from the blood circulation and preferentially recovered in the liver. In contrast, bare (Bare-) emulsions composed of soybean oil:EggPC:cholesterol (Chol) in a weight ratio of 70:25:5 were more retained in the blood circulation. The hepatic uptake clearances of Man- and Fuc-emulsions were 3.3- and 4.0-times greater than that of Bare-emulsions. Interestingly, the hepatic uptake clearance of Fuc-emulsions was significantly higher that that of Man-emulsions. The uptake ratios by non-parenchymal cells (NPC) and parenchymal cells (PC) (NPC/PC ratio) for Bare-, Man- and Fuc-emulsions were found to be 0.4, 2.0 and 2.9, respectively. The hepatic uptakes of [(3)H]CHE-labelled Man- and Fuc-emulsions were reduced by pre-dosing with glycosylated proteins and liposomes. These results clearly support the conclusion that Man- and Fuc-emulsions are promising carrier systems for liver NPC-specific targeting via receptor-mediated mechanism.

Animals↗
PubMedDate not supplied

The effect of RMP-7 and its derivative on transporting Evans blue liposomes into the brain.

To investigate the effect of RMP-7 and its derivative on drug transport across blood brain barrier (BBB), RMP-7 and DSPE-PEG-NHS [1,2-dioleoyl-sn-glycero-3-phosphoethanolamine-n-[poly(ethyleneglycol)]-hydroxy succinamide, PEG M 3400] were conjugated under mild conditions and the reaction ratio was determined using MALDI-TOF-MS (matrix-assisted laser desorption-ionization time-of-flight mass spectrometry). An endothelial cell monolayer in vitro BBB model was established and used to determine the bioactivity of RMP-7 and its derivative "opening BBB." Horse radish peroxide (HRP), liposome (HRP-L-PEG), and Evans blue (EB) liposome (EB-L-PEG) were prepared using the reverse-phase evaporation method. HRP-L-PEG-RMP-7 and EB-L-PEG-RMP-7 were obtained by inserting DSPE-PEG-RMP-7 into the surface of liposome. The bioactivity of RMP-7 and DSPE-PEG-RMP-7 opening BBB were evaluated to determine their effect on the permeation ratio of HRP and HRP liposome across the in vitro BBB model. To evaluate the in vivo bioactivity of RMP-7 and DSPE-PEG-RMP-7 on EB transport across BBB into the brain, the indicated compounds were administered to rats. Then, brain slices were analyzed using confocal laser scanning microcopy and the EB concentration in the brain, liver, spleen, lung, and kidney was determined using the formamide-extraction-ultraviolet-spectrophotometric method. The results demonstrated that RMP-7 was conjugated with DSPE-PEG-NHS at the molecular ratio of 1:1 and the product is DSPE-PEG-RMP-7. Compared with adding HRP alone, RMP-7 and DSPE-PEG-RMP-7 improved 2- to 3-fold the transport of HRP in the in vitro BBB model. The in vivo experiments showed that DSPE-PEG-RMP-7 was better at facilitating EB transport into brain than RMP-7. The reason may be that DSPE-PEG-RMP-7 can "open BBB" as soon as the EB-L-PEG-RMP-7 reaches BBB.

Amides↗
PubMed1984

The cytoplasmic 4S translation inhibitory RNA species of chick embryonic muscle: fractionation of biologically active subspecies by high performance liquid chromatography.

A 4S RNA species (iRNA) isolated from chick embryonic muscle which is a potent inhibitor of mRNA translation in vitro shows heterogeneity in the 70-100 nucleotide size range (Sarkar, S., Mukherjee, A.K., and Guha, C. (1981) J. Biol. Chem., 256, 5077-5086). The iRNA was fractionated by HPLC on different size exclusion columns using a variety of elution conditions. Chromatography of iRNA on a TSK 4000 SW column and elution with a low ionic strength buffer gave three components, one of which contained a pure subspecies of about 90-100 nucleotides size, as shown by a single band on PAGE analysis in 99% formamide. The biological activity of this purified subspecies showed that this is a more potent inhibitor of globin mRNA translation than unfractionated iRNA (Sarkar, S., Mukherjee, A.K., and Guha, C., (1981) J. Biol. Chem. 256, 5077-5086). Partial resolution of three additional low molecular weight iRNA subspecies in the 70-80 nucleotide size range in biologically active form was obtained on chromatography of unfractionated iRNA on TSK 4000 SW column in the presence of 0.5 M NaCl or on TSK 3000 SW column in the presence of low salt. The fractionation of iRNA by HPLC appears to be primarily based on size. These results strongly suggest that HPLC may also be useful for the fractionation of a variety of low molecular weight eukaryotic nuclear and cytoplasmic RNAs with retention of biological activity.

Animals↗
PubMedDate not supplied

The nonenzymatic hydrolysis of oligoribonucleotides. VII. Structural elements affecting hydrolysis.

Several elements of oligoribonucleotide structure are important for efficient hydrolysis. We have found that the following factors influence oligoribonucleotide hydrolysis: (i) single-stranded structure of RNA flanking the scissile phosphodiester bond, (ii) the substituent on atom C-5 of the uridine adjacent to the cleaved internucleotide bond, (iii) the position of the scissile UA phosphodiester bond within a hairpin loop, (iv) the concentration of formamide, urea, ethanol and sodium chloride.

Chromatography, High Pressure Liquid↗
PubMed1987

Development of a sampling and analytical method for measuring the epoxy content of aerosols: II. Application of the method to epoxy-containing aerosols.

Aerosols generated by epoxy spray painting consist of droplets containing partially-cured mixtures of epoxy resins and curing agents, as well as pigments, solvents and diluents. A sampling and analytical method has been developed to measure the epoxy content of these aerosols. The method collects the aerosol in a midget impinger containing dimethyl formamide, which inhibits the curing reaction between the epoxy and curing agent, preserving the unreacted epoxy functional groups present in the aerosol. The impinger contents are analyzed by reacting the epoxy with an excess of bromide generated in situ from tetraethylammonium bromide, and measuring the unreacted bromide in the reaction mixture by normal pulse polarography. The precision and accuracy of the method have been evaluated using a pure epoxy resin as a model compound. The method was applied to aerosols containing mixtures of epoxy resin and amine curing agents in various degrees of cure, to aerosols containing large quantities of nonepoxy compounds, and to aerosols of epoxy surface coatings. The method is capable of precise and accurate measurement of epoxide functionality, and it applicable to the measurement of epoxy-containing aerosols in spray finishing operations.

Aerosols↗
PubMed2002

Cellulose amphiphilic adsorbent for the removal of low density lipoprotein.

Cellulose adsorbent with amphiphilic ligands for adsorption of low density lipoprotein (LDL) was prepared by the following procedures: Cellulose beads were reacted with cholesterol N-(6-isocyanatohexyl) carbamate in the presence of pyridine in DMSO at 80 degrees C in order to introduce the hydrophilic moiety, it was then reacted with chlorosulfonic acid in dimethyl formamide, which introduced the sulfonic group. Adsorption capacity of adsorbent was studied, which showed the removal of LDL, TC, TG to be 0.857 mg/ml, 1.317 mg/ml, 1.002 mg/ml respectively without significantly affecting total protein levels in the plasma. Moreover, it has a better selectivity in removing LDL, TC, TG compared with cellulose adsorbent with only hydrophobic or hydrophilic ligand.

Adsorption↗
PubMed2004

An efficient route to novel 4,5-di- and 2,4,5-tri substituted imidazoles from imidazo[1,5-a]-1,3,5-triazine (5,8-diaza-7,9-dideazapurine) derivatives.

Two new types of imidazole derivatives: N-(2-R1-5-R2-1H-imidazol-4-yl) thioureas 7a-g and N-(2-R1-5-R2-1H-imidazol-4-yl) formamides 8b,c,g were obtained in high yields by the hydrolytic degradation of 6-R1-8-R2-2-thioxo-2,3-dihydroimidazo[1,5-a]-1,3,5-triazin-4(1H)-ones 5a-g and 6-R1-8-R2-imidazo[1,5-a]-1,3,5-triazin-4(3H)-ones 6b,c,d, respectively. The tautomeric preferences of the new imidazoles were determined.

Imidazoles↗
PubMed2004

Sample purification for analysis of organochlorine pesticides in sediment and fish muscle.

The methods of sample purification for determinations of organochlorine pesticides (OCPs) in sediment and fish muscle were investigated in this study. A two-step procedure with preliminary cleanup and florisil column fraction was adopted. The working conditions of florisil column were firstly optimized. As to preliminary cleanup, liquid-liquid extraction by mixture of dimethyl formamide (DMF) and hexane and sulphonation by concentrated sulfuric acid were applied respectively and compared for the studied samples. The results indicated that liquid-liquid distribution could effectively separate lipids from fish muscle extracts, while failed in elimination of chlorophyll extracted from the relicts of hydrophytes in the sediment sample. In view of the sample appearance and clarity of gas chromatogram, sulphonation was more suitable to purify the sediment sample, however, the recoveries of the spiked standards were poor. The use of eluting solvent with stronger polarity could improve the corresponding recoveries significantly. Due to complete loss of Dieldrin, Endrin, and Endrin aldehyde after sulphonation, this pretreatment was improper to the three components. Sulfur, as the particular disturbing element in sediment, could be removed sufficiently by addition of activated copper powder. The relevant detection limits of the selected methods for OCPs in the studied substrates were also provided.

Animals↗
PubMed1973

Single strand-containing replicating molecules of circular mitochondrial DNA.

Mitochondrial DNAs (mtDNAs) from Chang rat solid hepatomas and Novikoff rat ascites hepatomas were examined in the electron microscope after preparation by the aqueous and by the formamide protein monolayer techniques. MtDNAs from both tumors were found to include double-forked circular molecules with a form and size suggesting they were replicative intermediates. These molecules were of two classes. In molecules of one class, all three segments were apparently totally double stranded. Molecules of the second class were distinguished by the fact that one of the segments spanning the region between the forks in which replication had occurred (the daughter segments) was either totally single stranded, or contained a single-stranded region associated with one of the forks. Daughter segments of both totally double-stranded and single strand-containing replicating molecules varied in length from about 3 to about 80% of the circular contour length of the molecule. Similar classes of replicating molecules were found in mtDNA from regenerating rat liver and chick embryos, indicating them to be normal intermediates in the replication of mtDNA All of the mtDNAs examined included partially single-stranded simple (nonforked) circular molecules. A possible scheme for the replication of mtDNA is presented, based on the different molecular forms observed

Animals↗
PubMed1974

Mitochondrial DNA replication in sea urchin oocytes.

Mitochondrial DNA (mtDNA) replicative intermediates from Strongylocentrotus purpuratus oocytes were isolated by ethidium bromide-CsCl density gradient centrifugation and examined by electron microscopy after formamide spreading. In some experiments, the mtDNA was radioactively labeled by exposing isolated oocytes to [(3)H]thymidine. Oocyte mtDNA replication appears to follow the displacement loop model outlined in mouse L cells. There are differences in detail. The frequency of D-loop DNA is much lower in oocytes, suggesting that the relative holding time at the D-loop stage is shorter. Duplex synthesis on the displaced strand occurs early and with multiple initiations. The frequency of totally duplex replicative forms, or Cairns' forms, is the highest reported for mtDNA. The differences may be related to the fact that oocyte mtDNA replication occurs in the absence of cell division and need not be coordinated with a cell cycle. Molecules with expanded D loops banded in the intermediate region between the lower and upper bands in an ethidium bromide-CsCl gradient, supporting the notion that displacement replication proceeds on a closed circular template which is subject to nicking-closing cycles. In mature sea urchin eggs, replicative forms are absent and virtually all the mtDNA is stored as clean circular duplexes. Some novel structural variants of superhelical circular DNA (molecules with denaturation loops and double branch-migrated replicative forms) are reported.

Animals↗
PubMed1981

Structure and function of rat liver polysome populations. I. Complexity, frequency distribution, and degree of uniqueness of free and membrane-bound polysomal polyadenylate-containing RNA populations.

Free and membrane-bound polysomes were isolated from rat liver in high yields with minimal degradation, cross-contamination, or contamination by nuclear or nonpolysomal cytoplasmic ribonucleoprotein. Poly(A)+ RNA fractions isolated from free and bound polysomal RNA (poly(A)+ RNAfree and poly(A)+ RNAbound) by oligo(dT) cellulose chromatography exhibited number-average lengths of 1,600 and 1,200 nucleotides, respectively, on formamide sucrose gradients. Poly(A)+ RNAfree and poly(A)+ RNAbound contain 9.1 +/- 0.55 and 10.7 +/- 0.50% poly(A) as measured by hybridization to [3H]poly(U) and comprise 2.37 and 1.22% of their respective polysomal RNA populations. Homologous poly(A)+ RNA-cDNA hybridizations revealed that greater than 95% of the mass of poly(A)+ RNAfree and poly(A)+ RNAbound contain nucleotide complexities of about 3.4 x 10(7) and 6.0 x 10(6), respectively. This represents about 20,000 and 5,000 poly(A)+ RNA species of average sizes. Heterologous hybridizations suggested that considerable overlap exists between poly(A)+ RNAfree and poly(A)+ RNAbound sequences that cannot be attributed to cross-contamination. This was confirmed by conducting heterologous reactions using kinetically enriched cDNA populations. Heterologous hybridizations involving poly(A)+ RNA derived from tightly bound polysomes and cDNAfree indicated tha most of the overlapping sequences are not contributed by loosely bound (high-salt releasable) polysomes. The ramifications of these findings are discussed.

Animals↗
PubMed1955

Aspermatogenesis, anaphylaxis, and cutaneous sensitization induced in the guinea pig by homologous testicular extract.

Guinea pig testicles were extracted with acetic acid; the extract was purified by removing material in consecutive precipitations with 30 per cent saturated ammonium-sulfate, trichloracetic acid, and chloroform. The solution so purified, when administered with complete adjuvants, was highly active in inducing impairment of spermatogenesis in guinea pigs. The activity resisted autoclaving at 15 pounds' pressure for 20 minutes, proteolytic enzymes, and formamide. Anaphylactic shock and cutaneous reaction to the purified homologous extract occurred in guinea pigs sensitized by the extract combined with adjuvants. For the production of aspermatogenesis it was essential to incorporate killed mycobacteria into the water-in-oil emulsion containing the antigen; but anaphylactic sensitization did not require the presence of mycobacteria.

Adjuvants, Immunologic↗
PubMed1960

Immunological studies on a C polysaccharide complex of group A streptococci having a direct toxic effect on connective tissue.

A macromolecular complex of C polysaccharide and peptide derived from Group A streptococcal cells produces a multinodular, remittent, and intermittent lesion of dermal connective tissue following a single intradermal injection. This lesion is greatly modified, both in the gross and microscopically, in rabbits hyperimmunized with a Group A streptococcal vaccine. The immune serum, absorbed to yield only antibodies against C polysaccharide as indicated by agar diffusion techniques, will precipitate and neutralize the toxic material. This neutralization and in vitro precipitation can be inhibited with formamide-isolated C polysaccharide hapten and with N-acetylglucosamine, the primary directive group of this antigen. This clearly demonstrates that antibodies against the group-specific C polysaccharide are responsible for resistance to this toxic material. The immunological and other properties of the toxic C polysaccharide complex, the fact that it is a product of Group A streptococci, the gross and microscopic features of the experimental lesion produced with this substance, and the observations on the chronic course of the experimental lesion, indicate that this toxic material should be investigated as a possible factor in the pathogenesis of the non-suppurative sequelae associated with Group A streptococci.

Animals↗