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PubMed1990

Enhanced ultrastructural preservation of cartilage proteoglycans in the extended state.

We investigated the preservation of proteoglycan (PG) structure in rat epiphyseal cartilage using N-N-dimethylformamide (DMF) dehydration before embedding. After aldehyde fixation, specimens with and without routine osmium post-fixation were dehydrated in graded DMF and embedded in either Spurr's resin or Lowicryl K4M resin. Standard ethanol dehydration with Spurr or Lowicryl embedding techniques resulted in the formation of condensed PGs, called matrix granules. DMF dehydration before embedding greatly improved the preservation of PG structure and resulted in an extended appearance of PGs closely resembling the fine filamentous network of cartilage tissues processed by rapid freezing and freeze-substitution. However, en bloc staining of aldehyde-fixed specimens with cationic reagents before or during DMF dehydration induced the condensation of PGs and resulted in the formation of matrix granules. These observations demonstrate that DMF, a mild dehydration agent, dramatically improves PG preservation without a harmful effect on aldehyde-fixed PG structure and can be utilized regardless of routine post-fixation.

Animals↗

PubMed1984

Polar solvents: a novel class of antineoplastic agents.

It has been known for many decades that certain murine and human cancers can spontaneously mature to benign tissue. These observations have stimulated investigators to attempt to induce a state of more normal or benign differentiation in cancer cells using biologic substances or chemicals. Polar solvents including dimethylsulfoxide, dimethylformamide, and monomethylformamide have proven to be good inducers of maturational events in murine and human cancer cells. Moreover, several laboratories have demonstrated that polar solvents inhibit the growth of human tumor xenografts in nude mice. These findings have resulted in the entry of monomethylformamide into phase I clinical trials in America and Europe. Preclinical work further suggests that polar solvents may be useful agents in combination with conventional treatment modalities. The use of drugs such as monomethylformamide that can convert neoplastic cells to benign cells rather than kill the tumor cells represents an important conceptual departure from standard cytotoxic chemotherapy. The use of maturational-agent therapy should be considered as an important new development in the design of cancer treatment protocols.

Animals↗

PubMed1985

Synthesis and some properties of sulfate esters and sulfamates of iodothyronines.

In the present study, convenient methods have been developed for the synthesis of sulfate derivatives of iodothyronines. Reaction with chlorosulfonic acid in dimethylformamide gave rise to formation of the sulfate ester with the phenolic hydroxyl group. Reaction with the sulfurtrioxide-trimethylamine complex in alkaline medium afforded the sulfamate with the alpha-amino group of the alanine side chain. The sulfated products were isolated by adsorption onto Sephadex LH-20 in acidic medium, followed by desorption with water. Iodide was not retarded on these columns, whereas elution of native iodothyronines required alkaline ethanol mixtures. The yield of both reactions varied between 70-90%. The sulfates and sulfamates of T4, T3, rT3, and 3,3'-diiodothyronine could be separated by reverse phase HPLC. The sulfamates exhibited high cross-reactivities with antibodies against free iodothyronines, in contrast to the low activities of the sulfates. Products were further characterized by proton nuclear magnetic resonance, TLC, and hydrolysis by acid or sulfatase activity. The availability of large quantities of pure iodothyronine sulfates and sulfamates should facilitate the study of the importance of sulfate conjugation in the metabolism of thyroid hormone.

Chemical Phenomena↗

PubMed1991

Fluorometric determination of an inverse agonist to benzodiazepine receptors S-135 in monkey plasma by high performance liquid chromatography.

A high performance liquid chromatographic method for the determination of an agent of benzodiazepine receptor inverse agonist (S-135) was developed. S-135 in monkey plasma, after its administration, was assayed using the method. S-135 is ionized in alkaline N,N-dimethylformamide (DMF), and fluoresces strongly at 490 nm on excitation at 290 nm. Extracted S-135 from a plasma sample was separated with an Asahipak GS-310H polyvinyl alcohol gel column and detected fluorometrically, with the eluate being mixed with a triethylamine-DMF mixture. S-135 in plasma is assayable with a coefficient of variation being less than 3.5% (n = 11). The lower limit of the determination is 2 ng/ml. This method was applied as a highly sensitive and simple method to pharmacokinetic studies of S-135 after oral administration to cynomolgus monkeys.

Animals↗

PubMed1998

[Peptide synthesis aiming at elucidation and creation of protein functions].

The recent development of molecular biology has been elucidating outlines of the cross-talk of biomolecules. The understanding of the function of these biomolecules from the viewpoint of chemistry is now demanded not only for the understanding of biological systems but also for the creation of novel functional molecules. Here two topics are described about peptide synthesis aiming at the elucidation and the creation of protein functions. The first topic is the development of approaches for the synthesis of Tyr (SO3H)-containing peptides. Tyrosine sulfation is one of the most popular protein post-translational modifications. Synthetic peptides are of great help for the elucidation of the biological significance of tyrosine sulfation. We have developed two approaches for the efficient synthesis of tyrosine sulfate [Tyr (SO3H)]-containing peptides. The first approach employs a dimethylformamide-sulfur trioxide (DMF-SO3) complex as a sulfating agent and safety-catch protecting groups for the selective sulfation of tyrosine in the presence of serine. The second approach employs the direct introduction of Tyr(SO3H) into the peptide chain in the form of Fmoc-Tyr(SO3Na) followed by deprotection at 4 degrees C in trifluoroacetic acid. These approaches were successfully applied for the synthesis of cholecystokinin (CCK)-related peptides. The second topic deals with new approaches for the creation of artificial proteins through assembling alpha-helical peptides via selective disulfide or thioether formation. Approaches to assemble individual peptide segments on a peptide template were also developed. Four peptides corresponding to the transmembrane segments of the sodium channel (S4 in repeat I-IV) were assembled on a peptide template to give a protein having ion channel activity with rectification.

Amino Acid Sequence↗

PubMed1992

Characteristics of chymotrypsin modified with water-soluble acylating reagents and its peptide synthesis ability in aqueous organic media.

Several kinds of modified chymotrypsin were prepared with water-soluble acylating reagents, and their characteristics after hydrolyzing with unmodified chymotrypsin in aqueous-N,N'-dimethylformamide (DMF) media were compared. It was found that chymotrypsin (Csin), of which a 20% amino group was modified with a benzyloxycarbonyl group (Z(20)Csin), had more favorable characteristics than unmodified chymotrypsin with regard to hydrolytic activity in an aqueous DMF media. We also investigated the Z(20)Csin-catalyzed peptide synthesis in two different solution systems. In the one-layer system containing water and DMF, Z(20)Csin catalyzed the peptide bond formation in a higher yield than that by unmodifide chymotrypsin and enabled a synthetic reaction in even an 80% (v/v) DMF media, in which the hydrolytic reaction could not be carried out. Z(20)Csin catalyzed the condensation between some N-acyl amino acids or peptide derivatives and amino acids in 90% ethylacetate, 90% hexane or 50% benzene. This latter method employs a two-layer system, and the modified enzyme may be able to reduce the number of synthetic steps when preparing acyl peptides.

Acylation↗

PubMed2003

Polar organic solvent added to an aqueous solution changes hydrolytic property of lipase.

For developing further uses of lipase as a biocatalyst, its hydrolytic activity toward some esters was investigated in a miscible solution composed of a buffer and a polar organic solvent. Twenty percent dimethylformamide, 35% dimethylsulfoxide, 15% 1,4-dioxane, 15% dimethoxyethane, and 2% diethoxyethane promoted the hydrolysis by a lipase from Rhizomucor miehei toward some hydrophobic substrates, 4-methylumbelliferyl oleate, 4-methylumbelliferyl palmitate, and monoolein. While hydrolysis by this lipase toward the substrates with a relatively weak hydrophobicity (4-metylumbelliferyl heptanoate and 4-methylumbelliferyl nanoate) was suppressed by these solvents. A fluorometric analysis showed that the polar organic solvent in the buffer induced some conformational change around a tryptophan residue of R. miehei lipase. In addition to the influence of the miscible solvent on the solubility of the substrates, the conformational change of the protein induced by the miscible solvent would also affect the reactive properties of the lipase. Adding a polar organic solvent to an aqueous solution will be an efficient method for changing hydrolytic performance of lipases.

Dimethyl Sulfoxide↗

PubMedDate not supplied

Optimization of nb-4 and hl-60 differentiation for use in opsonophagocytosis assays.

Production of effective vaccine formulations is dependent on the availability of assays for the measurement of protective immune responses. The development and standardization of in vitro human cell-based assays for functional opsonophagocytic antibodies require critical evaluation and optimization of the preparation of cells for the assay. We report evaluation of a number of protocols with two continuous cell lines (NB-4 and HL-60) for the provision of differentiated cells for use in functional assays. Flow cytometric analysis of CD11b antigen expression, as a marker of differentiation, indicated that all-trans-retinoic acid (ATRA) gave improved differentiation (>80% of cells differentiated at 96 h) when compared with dimethylformamide (DMF) (<60% of cells differentiated at 96 h). Morphological changes during differentiation toward a neutrophil-like phenotype were assessed by scanning electron microscopy. HL-60 and NB-4 cells treated with ATRA showed more spreading and flattening than cells treated with DMF, further evidence that they may have achieved a more differentiated phenotype. The number of cell divisions in culture appeared to be critical because cell lines maintained in exponential growth for >40 passages failed to express CD11b antigen or show morphological changes associated with differentiation after exposure to either differentiation-inducing reagent. Late-passage cells also demonstrated increased tolerance to DMF. Our results indicated that ATRA supplemented with vitamin D(3) and granulocyte colony-stimulating factor affords robust, rapid, and reproducible differentiation of both cell types.

Analysis of Variance↗

PubMed1981

[A modified FEP (free erythrocyte protoporphyrin) test (author's transl)].

In order to simplify FEP (free erythrocyte protoporphyrin) test, we studied on the Piomelli's method, specially on the preparation of standard solution and on the role of celite-saline. N,N-dimethylformamide (DMFA) was used as the solvent of protoporphyrin standard (protoporphyrin IX dimethylester, Sigma Chemical Co.). The stock solution was stable for over 6 months at 4 degrees C. To examine the recovery and extraction efficiency, the stock solution (PP) diluted with DMFA was also added to blood. Ten microliter of DMFA added to 40 microliter blood had no effect on the FEP extraction. In the absence or at low concentrations of protein components, fluorescence intensity of added protoporphyrin extremely decreased in the extract with celite-saline. It seems to be due to the adsorption of protoporphyrin to celite. In the presence of proteins, there was no difference between fluorescence intensity of protoporphyrin with celite-saline dilution extraction and that with distilled water dilution extraction. The FEP levels in 128 lead workers (blood lead levels, 4.9-80.8 micrograms/100 g) with celite-saline extraction were almost the same as with distilled water dilution extraction. Thus celite-saline dilution was able to be displaced by the distilled water dilution, and the extraction procedure was slightly simplified. With our method, the average recovery was 93% and extraction efficiency was 80-90%.

Dimethylformamide↗

PubMed2006

[Evaluation of individual exposure to organic solvents using a portable VOC monitor].

Analysis by gas chromatograph after collection of personal samples is the most common method of evaluating individuals' exposures to organic solvents. This method provides us time-weighted averages (TWA) only, and does not measure fluctuating concentrations of organic solvents. A portable VOC monitor is widely used as a rapid screening instrument for volatile organic compounds (VOCs) in houses, schools, etc. The VOC monitor equipped with a photoionization detector can measure real-time concentrations of VOCs. In this study, the author investigated whether the VOC monitor can evaluate individuals' exposures to organic solvents. First, standard organic solvent gases were prepared and the gas concentrations were measured by a passive air sampler and the VOC monitor. Correction factors (CF) were obtained for the response of the isobutylene calibrated VOC monitor to equal concentrations of the organic solvents. Methyl ethyl ketone's CF was 0.5952, toluene's CF was 0.4418, and N,N-dimethylformamide's CF was 0.9017. Then, a mixed standard organic solvents gas was prepared and the gas concentration was measured by both methods. A significant correlation between both methods was obtained (p < 0.001). Subsequently, 37 male workers in a synthetic-leather factory were examined for solvent exposure using both the VOC and a passive sampler, Similar results were obtained by both methods (p < 0.001). Real-time data can be obtained using the VOC monitor and high exposure tasks can be identified. The VOC monitor will be useful for reducing occupational exposure. Since the VOC monitor provides detailed data of individuals' exposures to organic solvents.

Adult↗

PubMed1983

Preparation of high-potency, non-aggregating insulins using a novel sulfation procedure.

The marked propensity of insulin to self-associate into large aggregates causes significant mechanical problems in insulin delivery devices and may also stimulate production of a tissue-amyloid A precursor in some patients. Although conventionally prepared sulfated insulin (SI) resists aggregation, clinical application has been limited by major insulin bioactivity losses that occur during synthesis. To eliminate this problem, insulin sulfation was carried out in the organic solvent dimethylformamide in the presence of condensing agents such as N,N'-dicyclohexyl carbodiimide (DCC) and a sulfate donor. With this new procedure, the degree of sulfation could be controlled over an eightfold range by varying the amount of condensing agent. The bioactivity of these new SI derivatives varied between 78% and 87% of unmodified insulin. Insulin aggregation, induced by passage through a syringe and needle, did not occur with derivatives having two or more sulfate moieties per insulin molecule. Diffusion velocity studies using "non-aggregated" insulin solutions demonstrated that aggregates were present in crystalline zinc and sodium porcine insulin. In contrast, SI having more than 0.5 mole sulfate per mole of insulin dialyzed as it were predominantly in the monomeric form. Results from the studies described in this report now provide the means for selectively designing and preparing specific high-potency, non-aggregating insulins, which may be necessary for optimal use of current and future insulin delivery devices.

Animals↗

PubMedDate not supplied

Activity of differentiation-inducing agents and conventional drugs in head and neck cancer xenografts.

Three putative differentiation inducing agents and five conventional drugs which have been shown to be active in patients with squamous cell carcinoma of the head and neck (HNSCC), were tested for activity against HNSCC transplanted in nude mice. Drugs were administered at a maximum tolerated dose level. By testing the effect of conventional drugs the value of the nude mouse xenograft model for testing new drugs was assessed. Bleomycin as well as cisplatin showed antitumour effects in nude mice, although toxicity and thereby the effectiveness of cisplatin varied during the 5-year period in which the experiments were performed. Bleomycin caused responses in 4 out of 13 tumour lines and cisplatin, when administered at a high dose, was active in 2 out of 5 tumours. 5-Fluorouracil and cyclophosphamide were only moderately active, while methotrexate was inactive. These data indicate that the model might be of value in the detection of new anticancer drugs although it may have a tendency to underestimate the activity of some drugs. We used the nude mouse xenograft model to test the antitumour activity of three differentiation inducing agents, the polar-planar solvents hexamethylene bisacetamide (HMBA) and N,N-dimethylformamide (DMF) and the antimetabolite 5-aza-2'-deoxycytidine (5-aza-dCyd). HMBA appeared to be inactive. In contrast, DMF was active in 1 out of 4 tumour lines while 5-aza-dCyd was active in 2 out of 5 lines tested. Furthermore, the whole panel of differentiation inducers and conventional drugs was tested for antitumour activity against three HNSCC tumour lines.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetamides↗

PubMed1991

The interactions of superoxide ion(O2-.) with metallo-porphyrins [(C1(8)TPP)M, M = Fe,Mn,Co Zn]; models for biological systems and superoxide dismutases.

In dimethylformamide superoxide ion forms a 1:1 adduct with tetrakis (2,6-dichlorophenyl) porphinato-iron, (C1(8)TPP)FeOO-, as well as with its manganese analogue, (C1(8)TPP)MnOO-. On the basis of their electrochemical, spectroscopic, and magnetic properties these adducts have a metal-oxygen covalent bond (PorM-OO-), oxygen-centered redox chemistry, and reactivities that are similar to the hydroperoxide ion (HOO-). Addition of -OH to a solution of PorFe and O2 results in the formation of PorFe(OH)(OO-), which can be electrochemically oxidized to PorFeOH plus O2 (-0.2 V vs SCE). Addition of protons to the PorM-OO- adducts promotes their rapid decomposition to PorM, HOOH, and O2. This chemistry provides insight to the reactions of biological superoxide and superoxide dismutases.

Cobalt↗

PubMed1992

Electrochemical characteristics of nitroheterocyclic compounds of biological interest. VIII. Stability of nitro radical anions from cyclic voltammetric studies.

The stability of the one electron addition product of four biologically important nitroheterocyclic compounds has been examined electrochemically. Using cyclic voltammetry the tendency of the nitro radical anion to undergo disproportionation was studied by two methods of analysis. The first was based on determining the voltammetric time-constant required for half of the reduction product, RNO2-., to react further. The second concerned the minimum volume of dimethylformamide which had to be added to the aqueous electrolytic medium to give a specific cyclic voltammetric response. Both methods were found to compare well with the results obtained for RNO2-. stabilities using a theoretically derived procedure for a second order reaction following a charge-transfer step. The use of these alternative approaches for quantifying the reactivity of reduction products is discussed. The time-constant method in particular may be useful in studying complex reaction pathways.

Chloramphenicol↗

PubMed1976

Electrochemical properties of polycyclic compounds studied by the polarographic method in anhydrous systems. III. Polarographic reduction potentials of carcinogenic nitrogen compounds in dimethylsulfoxide.

The polarographic reduction of a series carcinogenic and noncarcinogenic polycyclic nitrogen compounds in anhydrous dimethylsulfoxide containing tetrabuthylammonium perchlorate as supporting electrolyte has been studied. The obtained results were compared with the number or with the position of nitrogen atoms in the molecules and with their carcinogenic activity. The values of half-waves potentials generally confirmed the mechanism proposed for the reduction of aromatic polycyclic carcinogenic hydrocarbons based on the polarographic experiments in dimethylsulfoxide. Agreement of the obtained results with the data reported by polarographic study in anhydrous dimethylformamide indicates, that the polarographic behavior of polycyclic nitrogen compounds in dimethylsulfoxide is very similar.

Acridines↗

PubMed1999

Structure of lysozyme dissolved in neat organic solvents as assessed by NMR and CD spectroscopies.

The structure of the model protein hen egg-white lysozyme dissolved in water and in five neat organic solvents (ethylene glycol, methanol, dimethylsulfoxide (DMSO), formamide, and dimethylformamide (DMF)) has been examined by means of 1H NMR and circular dichroism (CD) spectroscopies. The NMR spectra of lysozyme reveal the lack of a defined tertiary structure in all five organic solvents, although the examination of line widths suggests the possibility of some ordered structure in ethylene glycol and in methanol. The near-UV CD spectra of the protein suggest no tertiary structure in lysozyme dissolved in DMSO, formamide, and DMF, while a distinctive (albeit less pronounced than in water) tertiary structure is seen in ethylene glycol and a drastically changed one in methanol. A highly developed secondary structure was observed by far-UV CD in ethylene glycol and methanol; interestingly, the alpha-helix content of the protein in both was greater than in water, while the beta-structure content was lower. (Solvent absorbance in the far-UV region prevents conclusions about the secondary structure in DMSO, formamide and DMF.)

Animals↗

PubMed1976

The interaction of salts, amides, and water.

Infrared and Raman spectra are presented for salt solutions in N-methyl formamide and N,N'-dimethylformamide. Viscosities are reported for many of these solutions. Spectroscopic and viscosity data are also given for amide-salt solutions containing water. The three-component systems exhibit a hydrogen-bonding strength of water proton greater than amide proton, and an acceptor strength of Cl- greater than amide carbonyl oxygen greater than water oxygen. The salt cation is deduced by means of viscosity measurements to interact strongly with the amide carbonyl oxygen, even in the presence of appreciable quantities of water. Association of amides by hydrogen bonding through halide ions is also indicated.

Amides↗

PubMed1999

Experimental studies on application of small-caliber vascular prosthesis produced by polyurethane.

It has been suggested that a microporous structure enhances fast and complete endothelialization. For long-term patency, antithrombogenicity and microporous structure are very important factors. In this paper, we have developed a new technique to give a micro-porous structure to small-caliber vascular prosthesis produced by polyurethane which has favorable antithrombogenecity. A mixed solution (tetrahydrofuran: dimethylformamide = 1:1) containing 13 wt% of segmented polyurethane and a variable amount of calcium carbonate (mean particle size of 8 mm in diameter) was dip-coated on a glass mandril of 3 mm and 6 mm in diameter and placed into distilled water for 24 hours. After the glass mandrill was removed, this polyurethane tube was placed into 1 mmol hydrochloric acid for 1 hour, and a microporous polyurethane vascular prosthesis of 20 mm in length was completed. These prostheses of 3 mm and 6 mm in diameter were implanted into the femoral and the carotid arteries, and the abdominal aorta of the dogs, respectively. Patency was recognized by arteriography and Duplex scanning and the removed grafts were inspected macro- and microscopically. Greater hydraulic permeability of this graft was obtained with an increase in the quantity of calcium carbonate mixed with polyurethane. In elasticity, this graft was more similar to the canine jugular vein than the polytetrafluoroethylene graft. Patency was observed 8 weeks after implantation on the arteriogram, and neointima was observed microscopically on the smooth and lustrous lumen. The new polyurethane vascular prosthesis we developed might provide a potential prosthesis for small-caliber vascular reconstruction.

Animals↗