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PubMed2002

Serum mannan binding protein inhibits mannosylated liposome-mediated transfection to macrophages.

The effects of serum mannan binding proteins (MBP) in the transfection of plasmid DNA/Man-liposome complex via mannose receptor-mediated endocytosis was studied in vitro using cultured mouse peritoneal macrophages. Plasmid DNA encoding luciferase gene was complexed with cationic mannosylated liposomes (Man-liposomes), composed of cholesten-5-yloxy-N-(4-((1-imino-2-D-thiomannosylethyl)amino)alkyl)formamide (Man-C4-Chol) and dioleoyl phosphatidylethanolamine (DOPE). The transfection efficiency, as well as the binding and uptake of the plasmid DNA/Man-liposome complex, was investigated with or without serum MBP. The in vitro transfection efficiency of the complex was significantly reduced on increasing the amount of serum MBP. In addition, the cellular association of the complex was also reduced. These results indicate that serum MBP specifically binds to the mannose moieties on the complex and suppresses its cellular uptake, resulting in inhibition of the gene transfection in macrophages. Such an interaction is an obstacle to mannose receptor-mediated in vivo gene transfer to mannose receptor-positive cells using mannosylated gene carriers.

Animals↗
PubMed1997

Modified Evans blue fluorimetry for determination of pulmonary vascular permeability in rats sustaining burns, and delayed fluid resuscitation of burn shock.

The present experiment used modified Evans blue fluorimetry to determine changes in pulmonary vascular permeability using a delayed resuscitation model of burn shock in rats. The results showed that pulmonary vascular permeability in the immediate resuscitation (IR) group regressed to normal 12-24 h following the burn whereas it regressed slowly in the delayed resuscitation (DR) group. The study showed that Evans blue fluorimetry is a reliable and sensitive method for determining pulmonary vascular permeability, and dimethyl formamide is a preferable extracting solution which provides a quick and convenient means for scientific research.

Animals↗
PubMed2000

Hyperthermia-induced changes in the vascular permeability of rats: a model system to examine therapeutic interventions.

Extravasation in the heart, liver, lung, kidney, spleen, gastrocnemius, and duodenum was quantified in normothermic and hyperthermic (core temperature (T(c))=41.5, 42, or 42.6 degrees C) rats. Following attainment of the target T(c), Evans blue (Eb) was administered via jugular cannula; the animals were anesthetized, exsanguinated, tissues removed and washed in saline, and Eb extracted with formamide. There was significantly (p<0.05) more Eb (µg/g of dry wt of tissue, mean+/-SD) in the tissues of severely hyperthermic (T(c)=42.6 degrees C) rats vs that of control rats: liver - 198+/-39 vs 125+/-28, kidney - 376+/-68 vs 176+/-60, and small intestine - 170+/-49 vs 106+/-20. This model may be useful in evaluating the efficacy of treatment modalities designed to sustain vascular integrity in the face of environmental insult.

Journal Article↗
PubMed1979

Polyadenylate-protein complexes in resting and growing 3T3 cells.

The properties of the ribonuclease resistant cytoplasmic ribonucleoprotein particles were studied in contact-inhibited and serum induced proliferating 3T3 cells. The RNP particles were fractionated by oligo (dT)-cellulose chromatography and banded in CsSO4 gradients. The main RNP fraction, eluted with 25% formamide, contained the major ribonuclease resistant RNA sequences in both resting and growing cells. The protein component of this fraction had a molecular weight of about 72,000 in contact-inhibited cells and 81,000 in serum induced cells.

Animals↗
PubMed2001

The enhancement of PCR amplification by low molecular-weight sulfones.

DNA amplification by polymerase chain reaction (PCR) is frequently complicated by the problems of low yield and specificity, especially when the GC content of the target sequence is high. A common approach to the optimization of such reactions is the addition of small quantities of certain organic chemicals, such as dimethylsulfoxide (DMSO), betaine, polyethylene glycol and formamide, to the reaction mixture. Even in the presence of such additives, however, the amplification of GC-rich templates is often ineffective. In this paper, we introduce a novel class of PCR-enhancing compounds, the low molecular-weight sulfones, that are effective in the optimization of high GC template amplification. We describe here the results of an extensive structure-activity investigation in which we studied the effects of a series of six different sulfones on PCR amplification. We identify two sulfones, sulfolane and methyl sulfone, that are especially potent enhancers of high GC template amplification, and show that these compounds often outperform DMSO and betaine, two of the most effective PCR enhancers currently used. We conclude with a brief discussion of the role that the sulfone functional group may play in such enhancement.

Animals↗
PubMed2001

Microarray analysis of hepatotoxins in vitro reveals a correlation between gene expression profiles and mechanisms of toxicity.

A rate-limiting step that occurs in the drug discovery process is toxicological evaluation of new compounds. New techniques that use small amounts of the experimental compound and provide a high degree of predictivity would greatly improve this process. The field of microarray technology, which allows one to monitor thousands of gene expression changes simultaneously, is rapidly advancing and is already being applied to numerous areas in toxicology. However, it remains to be determined if compounds with similar toxic mechanisms produce similar changes in transcriptional expression. In addition, it must be determined if gene expression changes caused by an agent in vitro would reflect those produced in vivo. In order to address these questions, we treated rat hepatocytes with 15 known hepatoxins (carbon tetrachloride, allyl alcohol, aroclor 1254, methotrexate, diquat, carbamazepine, methapyrilene, arsenic, diethylnitrosamine, monocrotaline, dimethyl-formamide, amiodarone, indomethacin, etoposide, and 3-methylcholanthrene) and used microarray technology to characterize the compounds based on gene expression changes. Our results showed that gene expressional profiles for compounds with similar toxic mechanisms indeed formed clusters, suggesting a similar effect on transcription. There was not complete identity, however, indicating that each compound produced a unique signature. These results show that large-scale analysis of gene expression using microarray technology has promise as a diagnostic tool for toxicology.

Animals↗
PubMed2001

Oxidation of N,N-dimethylformamide and N,N-diethylformamide by human liver microsomes and human recombinant P450s.

N-N, dimethyl- (DMF) and N-N, diethyl-formamide (DEF) are two hepatotoxic solvents, whose metabolism has not been investigated in humans. To identify the P450 isoforms involved in the microsomal oxidation of these solvents we used (a) 12 human liver samples; (b) human recombinant P450 isoforms (1A1, 1A2, 2B6, 2C10, 2E1, 3A4); (c) chemical and immunological inhibitions. When correlation analyses were performed using enzymatic markers in human liver microsomes, the p-nitrophenol hydroxylation rate significantly correlated (r=0.87) with the dealkylation rate of DMF but not with that of DEF. Among the tested recombinant P450s only 2E1 oxidised DMF, while DEF was oxidised by 2E1, 2C10 and 3A4. 4-Methylpyrazole and anti human 2E1 IgG strongly inhibited the DMF demethylation but only partially the DEF deethylation. These findings indicate that, in the DMF metabolism, the role of 2E1 is crucial and its expression may be an important factor in determining the susceptibility of human to this solvent.

Cell Culture Techniques↗
PubMed1984

Purification of synthetic oligodeoxyribonucleotides by ion-exchange high-performance liquid chromatography.

Synthetic oligodeoxyribonucleotides ranging from 11 to 37 nucleotides in length and with varying base compositions, prepared by both the phosphotriester and phosphite procedures, have been purified by ion-exchange high-performance liquid chromatography on Whatman Partisil 10/SAX columns using phosphate buffer gradients. The effects of different buffer systems on elution times and resolution have been evaluated. Oligomer composition and length had a marked effect on the resolution achieved. In general the use of formamide buffers gave the best results, particularly in the case of 2'-deoxyguanosine-rich sequences. These methods have also been successfully applied to the purification of mixtures of synthetic oligodeoxynucleotides.

Chromatography, High Pressure Liquid↗
PubMed1997

Determination of antisense phosphorothioate oligonucleotides and catabolites in biological fluids and tissue extracts using anion-exchange high-performance liquid chromatography and capillary gel electrophoresis.

Chemically modified phosphorothioate oligodeoxynucleotides (ODNs) have become critical tools for research in the fields of gene expression and experimental therapeutics. Bioanalytical assays were developed that utilized fast anion-exchange high-performance liquid chromatography (HPLC) and capillary gel electrophoresis (CGE) for the determination of 20-mer ODNs in biological fluids (plasma and urine) and tissues. A 20 mer ODN in the antisense orientation directed against DNA methyltransferase (denoted as MT-AS) was studied as the model ODN. The anion-exchange HPLC method employed a short column packed with non-porous polymer support and a ternary gradient elution with 2 M lithium bromide containing 30% formamide. Analysis of the MT-AS is accomplished within 5 min with a detection limit of approximately 3 ng on-column at 267 nm. For plasma and urine, samples were diluted with Nonidet P-40 in 0.9% NaCl and directly injected onto the column, resulting in 100% recovery. For tissue homogenates, a protein kinase K digestion and phenol-chloroform extraction were used, with an average recovery of about 50%. Since the HPLC assay cannot provide one-base separation, biological samples were also processed by an anion-exchange solid-phase extraction and a CGE method to characterize MT-AS and its catabolites of 15-20-mer, species most relevant to biological activity. One base separation, under an electric field of 400 V/cm at room temperature, was achieved for a mixture of 15-20-mer with about 50 pg injected. Assay validation studies revealed that the combined HPLC-CGE methods are accurate, reproducible and specific for the determination of MT-AS and its catabolites in biological fluids and tissue homogenates, and can be used for the pharmacokinetic characterization of MT-AS.

Animals↗
PubMed1999

Transdermal delivery of naloxone: ex vivo permeation studies.

The purpose of this investigation was to study the feasibility of transdermal drug delivery of the potent opioid antagonist naloxone. The pharmacokinetic profile of naloxone makes it a suitable candidate for transdermal delivery. Ex vivo permeation of naloxone through excised rat skin was studied using a diffusion cell. Radiochemical assay of drug concentration and the use of rat as an animal model were adopted in this study. Naloxone possesses characteristics favorable to percutaneous absorption: i.e. a low molecular weight (327.37), water solubility and a good lipid-water partition coefficient of 12.94+/-1.29 at pH 7.4. The flux (microg/cm2/h) values varied from 6.59+/-0.72 in control to 27. 18+/-4.26 in dimethyl formamide. The affinity of naloxone to skin in the presence of propylene glycol was decreased by 6.2 times compared to the control. Fourier transform infrared spectroscopy was used to study the effect of various sorption promoters on intercellular lipid pathways in skin. A change in lipid fluidization corresponding to broadening for both C-H symmetric (near 2850 cm-1) and C-H asymmetric (near 2920 cm-1) stretching was observed. An attempt was made to correlate the molecular weight of sorption promoters with skin affinity values of naloxone.

Administration, Cutaneous↗
PubMed2002

Identification and synthesis of some contaminants present in 4-methoxyamphetamine (PMA) prepared by the Leuckart method.

The clandestine synthesis of ring and side chain modified phenylisopropylamines continues to be a major source of these drugs of abuse. One method used for the synthesis of the amphetamine and related compounds involves the treatment of the appropriate ketone with formamide or ammonium formate followed by acid hydrolysis of intermediate N-formyl derivative. In this paper the synthesis of 4-methoxyamphetamine (PMA, 1) by the Leuckart method is investigated. The identification by means of gas chromatography-mass spectrometry (GC-MS) of methoxy derivative of N-(beta-phenylisopropyl)benzaldimine 9, methoxy derivative of N-(beta-phenylisopropyl)benzyl methyl ketimine 5, 1-(4-methoxyphenyl)-N-(4-methoxybenzyl)-2-propanamine 10, (RR/SS) and (RS) 1-(4-methoxyphenyl)-N-[2-(4-methoxyphenyl)-1-methylethyl]-2-propanamine 6a-6c, (RR/SS) and (RS)-1-(4-methoxyphenyl)-N-methyl-N-[2-(4-methoxyphenyl)-1-methylethyl]-2-propanamine 7a-7c, (RR/SS) and (RS)-1-(4-methoxyphenyl)-N-formyl-N-[2-(4-methoxyphenyl)-1-methylethyl]-2-propanamine 8a-8c in crude PMA, are reported. The identity of these compounds was confirmed by independent synthesis of reference compounds. The NMR, MS, IR data, stereochemistry and some chromatographic properties of synthesized compounds are discussed. Finally, the results of the GC-MS analysis of illicitly prepared tablets, containing PMA 1 and 4-methoxymethamphetamine (PMMA, 2), are outlined. The presence of 4-methoxydimethylamphetamine 11, 4-methoxyethylamphetamine 12, and 4-hydroxymethamphetamine 13 are reported in these tablets. The identity of 2, 11, and 12 was confirmed by their independent synthesis.

Amphetamines↗
PubMed2000

Optimization of reverse hybridization in microplates coated with rRNA targeted oligonucleotide probes.

Among the modern molecular techniques for the identification of microorganisms the most straightforward way is through direct hybridization with rRNA/rDNA targeted probes. In this study, the optimization of the experimental procedures for the reverse hybridization technique in 96-well microplates is described using both synthetic model oligonucleotides (18 b) and amplified DNA (app. 4500 bp). Three different types of plates were compared (Maxi Sorp, NucleoLink, CovaLink). Plates made from nonchemically modified polystyrene which are conventionally used in immunoassays (MaxiSorp) proved to be an economic alternative for plates offering chemically modified tailor-made surfaces. Phosphorylation of the oligonucleotide probe was not necessary for successful immobilization whereas with 5'-terminal hexa-deoxyadenosine tailed capture oligonucleotides an enhanced sensitivity of the assay was observed. Variation of the stringency by adjusting different concentrations of formamide during the washing step ensures high probe specificity and therefore allows reliable identification of the microorganisms. The assay can be performed in less than 4 hours using pre-coated plates which can be stored for several weeks. After dissociation of the target DNA/capture probe duplex with an alkaline denaturing solution rehybridization is possible.

DNA Probes↗
PubMed2000

Headspace SPME method development for the analysis of volatile polar residual solvents by GC-MS.

A solid-phase microextraction (SPME) method has been developed and optimized for the polar residual solvent determination in pharmaceutical products. Five different polymer-coated fibers were investigated and the Carboxen/polydimethylsiloxane was found to be the most sensitive for all components. Two Headspace SPME methods were developed and optimized: one for the extraction from aqueous solutions, and the other for the extraction from organic solutions (N,N-dimethyl formamide (DMF) and dimethyl sulfoxide (DMSO). The optimum equilibration time for all components and all systems was 30 min. It was found that the sample headspace volume has an important effect on method sensitivity and precision. At low headspace volumes (less than one-third of the vial volume), sensitivity improves but at the same time, precision worsens. For 10 ml headspace vials, the optimum headspace volume was found to be 3 ml. The total volatile organic content in the sample also has an important effect on method sensitivity and precision. At low organic content, sensitivity increases but precision drops significantly. Over 0.5% volatile organic content in the sample, the system becomes unstable due to stationary phase swelling by the organic components, and also the sensitivity of the method is drastically reduced. The optimum range for total volatile organic content was found to be between 0.01 and 0.1%. The added Na2SO4 quantity increases the extraction yield. It was found that slightly pressurizing the headspace vial improves the sensitivity of the method by a factor of 2. For the organic system, it was found that the addition of 100 microl DMSO or DMF to 50 mg drug substance and slightly pressurizing the headspace vial gives good results in terms of sensitivity and reproducibility. The measured detection limits were between 0.4 and 200 ng/ml, and the relative standard deviation data were between 2 and 9%. The Headspace SPME from aqueous solutions was found to be ten times more sensitive than Immersion SPME and Headspace SPME from organic solutions.

Dimethyl Sulfoxide↗
PubMed1998

Reduction of capillary permeability in the fructose-induced hypertensive rat.

Impaired insulin transcapillary transport and the subsequent decrease in insulin delivery to target organs have been suggested to play a role in insulin resistance. These defects were studied in fructose-fed rats, an animal model with insulin resistance. For this study, male Sprague-Dawley rats were fed with either a 60% fructose enriched (F) or a standard chow diet (N) for a total of 2, 4, or 8 weeks. Capillary permeability to albumin was assessed at the end of each dietary period by quantifying the extravasation of albumin-bound Evans blue (EB) dye in different organs. Unanesthetized animals were injected with Evans blue dye (20 mg/kg) in the caudal vein 10 min before being killed and EB dye was extracted by formamide from selected organs collected after exsanguination. As expected, rats had an increase in blood pressure upon feeding with fructose at 4 and 8 weeks (F, 149 +/- 3 mm Hg; N, 139 +/- 3 mm Hg; P < .05). Using this technique, we showed a 56% and a 51% reduction in capillary permeability in skeletal muscles at 4 and 8 weeks of fructose feeding, respectively (4 weeks: N, 44.5 +/- 5.0 microg/g of dry tissue; F, 19.8 +/- 4.2 microg/g of dry tissue; P < .01 and 8 weeks: N, 23.3 +/- 3.7 microg/g of dry tissue; F, 11.3 +/- 4.0 microg/g of dry tissue; P < .05). Similar changes were observed at 4 weeks in the thoracic aorta (N, 82.8 +/- 8.8 microg/g of dry tissue; F, 53.0 +/- 5.1 microg/g of dry tissue; P < .02) and skin (N, 36.0 +/- 5.3 microg of dry tissue; F, 15.0 +/- 2.3 microg/g of dry tissue; P < .02) and at 8 weeks in the liver (N, 107.5 +/- 4.3 microg/g of dry tissue; F, 80.9 +/- 3.2 microg/g of dry tissue; P < .01). In conclusion, fructose feeding is accompanied by a significant and selective reduction of Evans blue leakage primarily in skeletal muscle and liver, and transiently in the skin and aorta, consistent with a role for decreased tissue insulin delivery in insulin resistance.

Animals↗
PubMed2003

Characterization of solid-state forms of celecoxib.

This study deals with the generation and characterization of various solid-state forms of celecoxib, a selective cyclooxygenase-2 (COX-2) inhibitor. The drug was subjected to polymorphic screen using different solvents to explore the possibility of existence of different solid forms. N,N-Dimethyl acetamide (DMA) and N,N-dimethyl formamide (DMF) yielded solvates in 1:1 stoichiometric ratio. Quench cooling of the melt resulted in amorphous form of the drug. All these solid-state forms were characterized by thermoanalytical (DSC, TGA, HSM), crystallographic (XRD), microscopic (polarized, SEM), spectroscopic (FTIR), and elemental analysis techniques. Solubility and van't Hoff studies were carried out for their thermodynamic interpretation. Influence of morphology of different solid-state forms on flow behavior was also investigated. Molecular modeling studies were used to elucidate the interaction between solute and solvent molecules in the solvate.

Celecoxib↗
PubMed1993

Distribution of capsular types 1 to 28 and further characteristics of Streptococcus suis isolates from various European countries.

Most of the 150 Streptococcus suis isolates from pigs and ruminants used in this study grew under aerobic conditions and were alpha-hemolytic on sheep blood agar. Part of the cultures required an increased CO2 concentration. These cultures, representing the CO2- dependent ecovar of S. suis, were mainly beta-hemolytic on sheep and horse blood agar and gave a synergistic hemolytic reaction with staphylococcal beta-lysin. Similar to S. suis reference cultures, the routine isolates showed typical biochemical properties of this species. Few cultures, mostly those from ruminants, could be classified as the sorbitol and mannitol-positive ecovar. Formamide extracts of 81% of the cultures reacted with group D-specific antisera. Serotyping of the S. suis isolates revealed mainly capsular types 2, 1/2, 1, 5, 11, 13, 23, 3 and 15. The determination of antibiotic susceptibility revealed a high number of cultures to be resistant to clindamycin, erythromycin, kanamycin, neomycin, streptomycin and tetracycline. Cultural, biochemical and serological properties together with antibiotic resistance patterns could be used to characterize individual isolates of S. suis. This could be of importance in epidemiological studies.

Animals↗
PubMed2003

Preparation of aluminium-magnesium alloys and some valuable salts from used beverage cans.

The purpose of this work is to recover standard aluminium-magnesium alloy(s) and some valuable salts from used beverage cans (UBCs). The suggested method updated the current recycling technology by augmenting removal of the coating paint, decreasing magnesium loss during melting process and improving hydrochloric acid leaching of the formed slag. Iron impurity present in the leaching solution, was removed by oxidation using oxygen gas or hydrogen peroxide and filtered as goethite. Results obtained revealed that a mixture of methyl ethyl ketone/dimethyl formamide entirely removes the paint coating at room temperature. The process compares favorably to the current methods involving firing or swell peeling. The coating decomposes to titanium dioxide by heating at 750 degrees C for 30 min. Standard compositions of Al-Mg alloys are formulated using secondary magnesium. The extent of recovery (R) of these alloy(s) is a function of the melting time and temperature and type of the flux. The maximum (R) value amounts to 94.4%. Sodium borate/chloride mix decreases magnesium loss to a minimum. The extent of leaching valuable salts from the slag increases with increasing the molarity, stoichiometric ratio and leaching temperature of the acid used. Removal of iron is a function of the potential of the oxidation process. Stannous chloride has been recovered from the recovered and dried salts by distillation at 700-750 degrees C.

Alloys↗