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PubMed1982

The influence of the cryopreserving process on rubidium uptake by human spermatozoa.

The effect of cryopreservation and its phases on the netto-Rb+ uptake (analogous to the K+ uptake) of washed human spermatozoa was investigated under different conditions. The Rb+ uptake reached a steady state after almost 50-min incubation both before and after the cryopreserving process. The Rb+ uptake could be reduced to about 30% by ouabain and to about 80% by monoiodoacetate. The cryoprotective agents glycerol (G), ethylene glycol (EG), and particularly dimethylsulfoxide (DMSO) reduced the Rb+ uptake by a factor dependent on its concentration. The comparative cryopreservation with G, EG, DMSO,and dimethylformamide (DMFA) as cryoprotective agents caused an inhibition especially of the ouabain-sensitive netto-Rb+ uptake. This inhibitory effect became stronger from G to EG and from DMSO to DMFA. Within the course of cryopreservation especially the process of pelletation, Rb+ uptake was reduced, whereas the prolongation of the equilibration time up to 180 min moderated the effect of the cryopreservation on the Rb+ uptake. Beside the reduction of the absolute Rb+ uptake, the cryopreservation altered the dependence of the netto-Rb+ uptake on the extracellular Rb+ concentration in a sigmoid manner.

Dimethyl Sulfoxide↗

PubMed1982

Inhibition of the growth of human colon cancer xenografts by polar solvents.

The effects of N,N-dimethylformamide (DMF) and N-methyl-formamide (NMF) on the growth of two human colon cancer cell lines xenografted in nude mice were assessed. Toxicological studies with mice heterozygous for the nu/nu gene showed that with both compounds the limiting organ toxicity was hepatic. The 10% lethal doses for DMF and NMF given i.p. daily for 21 days were 2219 and 374 mg/kg, respectively. Nude mice (10/group) received s.c. transplants of HCT-15 or DLD- 2 human colon cancer cells. Mice were treated i.p. with the approximate 10% lethal doses of either DMF (daily for 21 days) or NMF (daily for 19 days) or with 0.9% NaCl solution when tumors became palpable. With the HCT-15 tumor, a growth inhibition of 65% was obtained using DMF compared to 0.9% NaCl solution-treated controls. Two independent experiments with DLD-2 demonstrated that DMF effected growth inhibitions of 45 and 67%. NMF treatment produced 48 and 75% growth inhibitions of HCT-15 and DLD-2 tumors, respectively. Weight loss of groups of treated mice in all experiments was between 2 and 14%, within the acceptable range for 10% lethal drug doses. Results indicate that some human cancer xenografts respond to the polar solvent DMF and to its metabolite NMF and that DMF may be acting at least in part by its metabolism to NMF. Furthermore, the data should alert clinical investigators to the possibility of hepatotoxicity when polar solvents are tested in Phase I clinical trials.

Animals↗

PubMed1980

A new class of inhibitors of lymphocyte mitogenesis: agents that induce erythroid differentiation in Friend leukemia cells.

Addition of the polar organic compounds, dimethylsulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, and butyric acid, to human lymphocyte cultures stimulated with the tumor-promoting agent, phorbol myristate acetate, results in greater than 90% inhibition of lymphocyte proliferation. Inhibition is achieved at concentrations of the organic compounds reported to be optimal for induction of erythroid differentiation in Friend leukemia cells. Butyric acid is the most potent compound tested. Compounds that are structurally related to butyric acid, but that do not induce erythroid differentiation, do not inhibit lymphocyte mitogenesis. Lymphocyte responses to other mitogens are also suppressed by the polar organic compounds, although higher concentrations are required. These agents are much less inhibitory when added 24 hr after initiation of the cultures, indicating that they may affect an early phase of lymphocyte activation. Compounds that induce erythroid differentiation in Friend leukemia cells constitute a new class of inhibitors of lymphocyte mitogenesis.

Acetamides↗

PubMed1980

Solubility properties of IgG immune complexes. Comparison between the effects of low molecular weight solvents and polyethylene glycols.

A systematic study of the influence of organic solvents on the interaction between human IgG and rabbit anti-human IgG IgG++ has been conducted, using difference turbidity and sucrose gradient centrifugation methods. It was found that very small alcohols like methanol and ethanol increased the turbidity signal, whereas larger alcohols (propanol, isopropanol, propanediol and ethylene glycol) had no influence on the signal. Sucrose, dioxane, dimethylformamide and dimethylsulphoxide decreased the difference turbidity signal. Sucrose gradient centrifugation did not show any influence. Polyethylene glycols were investigated with regard to molecular weights as well as concentrations. In contrast to the low molecular weight solvents, polyethylene glycols with molecular weights from 600 up to 20,000 gave a clearly expressed increase in the development of turbidity as well as in the size of the final turbidity signal. By sucrose gradient centrifugation, it was found that polyethylene glycols of molecular weights from 1000 to 10,000 had a profound effect on the solubility of immune complexes. The influence depended on the molecular weight as well as on the concentration. By use of [14C]-labelled polyethylene glycol it was found that polyethylene glycols did not form stable complexes with immune complexes. Furthermore, it was found that the zoning phenomenon was retained in the presence of small concentrations of polyethylene glycols, but higher concentrations of polyethylene glycols caused even antigen-excess complexes to show turbidity.

Alcohols↗

PubMed1994

Tryptophanase from Escherichia coli: catalytic and spectral properties in water-organic solvents.

In water-methanol and water-dimethylformamide (DMF) (1:1 v/v) solutions tryptophanase from E.coli retains its abilities to form a quinonoid complex with quasisubstrates and to catalyze the decomposition of S-o-nitrophenyl-L-cysteine (SOPC). Both the KM and Vmax values decrease in water-organic media. The affinities of tryptophanase for L-alanine, L-tryptophan, oxindolyl-L-alanine and indole in aqueous methanol are decreased, the effect being stronger for the more hydrophobic substances. In a water solution tryptophanase catalizes the reaction of SOPC with indole to form L-tryptophan while in water-organic solvents only decomposition of SOPC is observed.

Alanine↗

PubMed1994

[Effect of organic solvents on functional nervous system disorders].

Examination of 953 workers exposed to low concentrations of chlorbenzene, tricresol and dimethylfonnamid revealed such functional neural disorders as cardiovascular neurosis. Chlorbenzene and tricresol resulted in hypertonic cardiovascular neurosis, dimethylformamid--in hypotonic one. Occurrence of cardiovascular neurosis grew with the longer length of service.

Adult↗

PubMedDate not supplied

[Isolation and selection of methylamines and dimethyl formamide degrading microorganisms].

From an activated sludge sample, microorganisms capable to degrade monomethylamine (MMA), dimethylamine (DMA), trimethylamine (TMA), and dimethylformamide (DMF) were isolated. These compounds are present in the wastewaters from a petrochemical plant. Microbial communities were cultivated, in aerobic conditions in a 2-liter bioreactor fed with the wastewater. Only four different kinds of microorganisms were obtained, but they could maintain their degradative capacity after several transfers. This microbial biomass was able to reduce 90% of the dissolved pollutants in a sample of industrial wastewater, mainly MMA, DMA, TMA, and DMF, measured as dissolved organic carbon, in approximately 5 days.

Biodegradation, Environmental↗

PubMed1994

A water-soluble fragment of Micrococcus lysodeikticus cell wall.

A fragment of Micrococcus lysodeikticus cell wall was obtained by extraction of walls with water, dimethylformamide or dimethyl sulfoxide. The water-soluble polymer was obtained from the cell walls prepared either with or without trypsin treatment of the cell. This fragment was studied by the Smith periodate oxidation, methylation, mild acid treatment and enzymic procedures. The polymer consists of polysaccharide chains composed of (1-->4)-O-(2-acetamido-2-deoxy-beta-D-mannopyranosyluronic acid)-(1-->6)-O-alpha-D-glucopyranosyl residues. The polysaccharide chain is linked to C-6 of a 2-acetamido-3-O-(D-1-carboxyethyl)-2-deoxy-beta-D-gluco-pyranosyl residue of a peptidoglycan chain composed of repeating (1-->4)-O-(2-acetamido-2-deoxy-beta-D-glucopyranosyl)-(1-->4)-[2-acet ami do-3-O-(D-1-carboxyethyl)-2-deoxy-beta-D-glucopyranosyl] residues. The water-soluble cell-wall fragment was also observed in the-culture medium of Micrococcus lysodeikticus and was also extractable from the cells in minor quantity.

Carbohydrate Sequence↗

PubMed1993

Differentiation of pancreatic acinar cells into duct-like cells in vitro.

BACKGROUND: Previous studies have shown that a combination of both the extracellular matrix and secretagogues plays critical roles in the maintenance of well-differentiated pancreatic acinar cells in culture. In the present study, we have shown that, upon proper stimulation, acinar cells change their growth pattern and morphologic appearance to a duct like phenotype. EXPERIMENTAL DESIGN: Both rat and guinea pig acinar cells were cultured on or embedded into the Matrigel basement membrane, in the presence of differentiating agents such as dimethylsulfoxide (DMSO), hexamethyl-bis-acetamide, dimethylformamide, triiodothyronine, and butyric acid. The growth patterns, cell proliferation, ultrastructural appearance, intracellular contents, secretion and immunolocalization of amylase, as well as the expression of the ductal marker carbonic anhydrase II and lectin-binding specific sites were analyzed. Moreover, the effects of metabolic inhibitors such as cycloheximide and actinomycin D on the DMSO induced action were also examined. RESULTS: Isolated acinar cells from both rat and guinea pig pancreas showed an important modification of their growth pattern and morphologic appearance when culture embedded into Matrigel in the presence of 2% DMSO. They reaggregate and form isolated branched tubular structures lined by a single cell layer. These tubules can be maintained in culture for over a period of 21 days. The cells lining the tubules were originally acinar cells that became elongated and progressively lost their secretory granules. They displayed a lower number of apical microvilli and established long junctional complexes with elaborated interdigitations. The immunocytochemical localization and biochemical determination of intracellular and secreted amylase revealed a progressive decrease reaching minimal values by the 12th day of culture. The cells further expressed the duct cell marker carbonic anhydrase II and lost the Helix pomatia lectin-binding affinity characteristic of acinar cells. Cell proliferation by modified cells as measured by thymidine incorporation and the autoradiographic labeling index, was significantly lower than in control cultured acinar cells. The DMSO differentiating action was mimicked, but to a lesser extent, by the other agents except butyric acid. Since cycloheximide and actinomycin D inhibited the DMSO-induced changes, protein synthesis and DNA transcription seem to be required. CONCLUSIONS: Our results demonstrate that normal pancreatic acinar cells retain a morphogenetic plasticity and, upon particular stimulation, can change their differentiation commitment pattern toward that of the duct cell phenotype.

3,4-Methylenedioxyamphetamine↗

PubMed1996

Steady-state levels of mitochondrial messenger RNA species characterize a predominant pathway culminating in apoptosis and shedding of HT29 human colonic carcinoma cells.

A differentiated human colonic epithelial cell has undergone relatively stable molecular, biochemical, and cellular alterations resulting in the acquisition of structures, activities, and functions that characterize it as one of at least three mature phenotypes: a columnar absorptive, secretory, or enteroendocrine cell. We have shown previously that induction of HT29 cells with the short-chain fatty acid sodium butyrate elevates alkaline phosphatase activity, a marker of the absorptive cell phenotype, and increases mitochondrial gene expression. Furthermore, this induction is accompanied by subsequent apoptosis and cell shedding. In this report, we have investigated the effects of forskolin, a potent inducer of the MUC2 gene in HT29 cells, a marker of the secretory phenotype, and have shown that neither apoptosis nor mitochondrial gene expression are significantly stimulated. Thus, differentiation along the secretory cell lineage may not play a major role in apoptosis of colonic epithelial cells. Moreover, we have also investigated two polar solvents, DMSO and dimethylformamide, which have been reported to induce a more differentiated, but as yet not well characterized, phenotype in colonic carcinoma cells in culture. Although neither polar solvent induces alkaline phosphatase expression or MUC2 expression, both induce significant apoptosis, again associated with significant elevation of mitochondrial gene expression. Thus, elevation of mitochondrial gene expression appears to be an important pathway in the induction of apoptosis in colonic epithelial cells in culture, whether or not markers characteristic of differentiation along either the absorptive or secretory cell lineage are induced.

Apoptosis↗

PubMedDate not supplied

[Quenching of triplet states by Fe(II)- and Fe(III)-porphyrins].

The quenching of triplet states of metalloporphyrin molecules differing in the position of the lowest triplet state (from 9.000 to 15.000 cm-1) by ion complexes of octaethylporphin (OEP) has been investigated. High-spin ferric complex FeCl-OEP in dimethylformamide, toluene and ethanol, low-spin ferric complex FeCl(imidazole)2-OEP in toluene and diamagnetic ferrous complex Fe(piperidine)2-OEP in pyridine-piperidine (25:1) were used as quenchers. It has been found that all iron complexes investigated are effective quenchers of triplet states. The values of bimolecular quenching constants fall within the limits of (1 divided by 4) X 10(9) M-1 sec-1. Energy transfer to low-lying excited levels of iron porphyrins which are due to the presence of 3d electrons of ferric (ferrous) ion has been shown to play an essential role in the quenching process.

Chemical Phenomena↗

PubMed1997

Toxin-induced increase in survival factor receptors: modulation of the threshold for apoptosis.

The threshold at which toxins induce cell death is thought to directly relate to the amount of injury sustained. We show that the threshold at which a cell initiates toxin-induced death may vary in response to changes in the trophic environment. Treatment of Rat-1 fibroblasts with 50-175 mM dimethylformamide (DMF) induced cell death by apoptosis. Addition of insulin-like growth factor 1 (IGF-1; 100 ng/ml) and/or overexpression of the IGF-1 receptor (IGF-1R) attenuated the cytotoxicity of DMF. Furthermore, 95-99% of cells were protected from DMF-induced apoptosis if cells were pretreated with platelet-derived growth factor (5 ng/ml) for 16 h before treatment with DMF in the presence of IGF-1. Platelet-derived growth factor induced the expression of IGF-1R mRNA. The ability of cells to proliferate and survive after a 24-h treatment with DMF was determined by colony formation; whereas treatment with concentrations of >130 mM DMF reduced cellular survival, exposure to concentrations of <130 mM unexpectedly increased the colony-forming ability of treated cells when compared to that of controls. Treatment of Rat-1 fibroblasts with 75 and 130 mM DMF induced IGF-1R mRNA as determined by reverse transcription-PCR analysis. Serum withdrawal also transiently increased the expression of IGF-1R mRNA in Rat-1 fibroblasts. These results show that cells can actively adapt to pathological and physiological stress by up-regulating receptors that provide signals for cellular survival. We suggest that the threshold for toxin-induced apoptosis is determined not only by the extent of cytotoxic damage but also by the trophic environment and the ability of a cell to modulate survival signals that attenuate toxicity.

Animals↗

PubMed1997

Role of the apoprotein in the catalytic peroxidase-like function of ferritin.

The thermal inactivation of horse spleen ferritin was studied over a range of temperatures (36-52 degrees C) in 0.1 M acetate buffer (pH 4.2) as a decrease of its peroxidase activity during tetramethylbenzidine (TMB) oxidation by hydrogen peroxide. The activation energy of this process was 163.3 kJ/mole. Thermodynamic activation parameters for the loss of peroxidase activity of ferritin were calculated. The influence of various detergents on ferritin-dependent oxidation of TMB, ortho-tolidine, and ortho-phenylenediamine (PDA) by hydrogen peroxide was studied in 0.1 M phosphate buffer (pH 6.0) at 20 degrees C. Relatively high concentrations of charged detergents (SDS and cetyltrimethylammonium bromide) decreased the peroxidase activity of ferritin with all three amines, whereas moderate concentrations of the nonionic detergent Triton X-100 did not influence oxidation of these substrates. Increase of dimethylformamide concentration in 0.02 M acetate buffer (pH 4.2) from 5 to 40% strongly decreased the rate of TMB and PDA oxidation by hydrogen peroxide or cumene hydroperoxide. Decrease in the activity of thermally inactivated ferritin with TMB as substrate, reduction of alpha-helical content of the protein at 40-50 degrees C, an inactivating effect of charged surfactants and organic co-solvent on the peroxidase activity of ferritin indicate a very important role of the apoprotein in peroxidase function. A possible mechanism of apoferritin participation in peroxidase catalysis is discussed.

Animals↗

PubMed1998

Evaluation of the selectivity of In vitro probes and suitability of organic solvents for the measurement of human cytochrome P450 monooxygenase activities.

There is a need for methodology to predict clinically significant drug-drug interactions so that clinical studies can be directed toward interactions which are likely to be clinically relevant. To this end, we evaluated selective assays for the seven drug-metabolizing cytochrome P450 (P450) isozymes 1A2 (caffeine N3-demethylation), 2A6 (coumarin 7-hydroxylation), 2C9 (tolbutamide hydroxylation), 2C19 (S-mephenytoin 4-hydroxylation), 2D6 (dextromethorphan O-demethylation), 2E1 (chlorzoxazone 6-hydroxylation), and 3A4/5 (dextromethorphan N-demethylation). Using initial rate conditions, we determined the Km and Vmax values of each reaction in human liver microsomes from three individuals. Because organic solvents (usually methanol) are frequently used as solubilization aids for drugs/inhibitors, we also screened several solvents for inhibitory activity. Methanol was the least inhibitory toward P450s 2A6, 2D6, and 3A4, dimethylformamide was the least inhibitory toward P450s 1A2 and 2C9, and acetonitrile was the least inhibitory toward P450s 2C19 and 2E1. Using substrate concentrations close to the determined Km and an appropriate solvent (where necessary), we used the selective inhibitors furafylline (1A2), 8-methoxypsoralen (2A6), sulfaphenazole (2C9), S-mephenytoin (2C19), quinidine (2D6), diethyldithiocarbamate (2E1), and troleandomycin (3A4) to assess the limitations of each probe assay as an indicator of the P450 isoform in question. Our results were consistent with these inhibitors and probes, being selective tools for studying P450 drug metabolism.

Acetonitriles↗

PubMed1998

[Free amino acids in the synthesis of peptides. Effect of inorganic compounds on the solubility of amino acids in aprotic solvents].

In order to increase the solubility of free amino acids so that they could be used in peptide synthesis, a system consisting of dimethylformamide, an inorganic additive, and pyridine was suggested. Compounds BF3, AlCl3, SnCl2, SiCl4, ZnCl2, SbCl3, CaCl2, BaI2, CdI2, and NaI can serve as the additives. Acylation of amino acids in such a solution (pH 5.2-5.3) with pentafluorophenyl esters of N alpha-protected amino acids gave N alpha-protected di- and tripeptides in a yield of more than 90%.

Acylation↗

PubMed1997

A simple procedure for sulfation and 35S radiolabelling of paralytic shellfish poisoning (PSP) gonyautoxins.

A method is described to sulfate PSP toxins at various positions in the molecule and to prepare 35S labelled compounds using H2(35)SO4 in the presence of dicyclohexylcarbodiimide (DCC). The 11-sulfates of saxitoxin and neosaxitoxin, known as gonyautoxins, are often the most abundant of the PSP toxins in algae and contaminated shellfish. Receptor site binding and antibody assays based on these analogues should, therefore, better reflect toxicity than those in which saxitoxin is used. Although the specific activity of 35S-gonyautoxins is lower than that of commercially available 3H-saxitoxin, the label is strongly bound and is not lost through proton exchange with water as occurs with tritiated saxitoxin. The labelling procedure is rapid, inexpensive and can be done on a small scale. Sulfate can be removed from the 11-position of GTX's in methanolic-HCl and from the 21-position by mild acid hydrolysis and H2(35)SO4 added in 5-10-fold excess. Addition or exchange occurs rapidly on mixing DCC in dimethylformamide with dry toxin and sulfate. Reaction conditions were optimized and reaction products identified by capillary electrophoresis, autoradiography and ionspray mass spectrometry. Together with methods for selective removal of sulfate, the sulfation reaction provides an additional way to prepare some of the naturally occurring derivatives of saxitoxin, many of which are sulfates.

Animals↗

PubMed1998

Determination of 15N isotopic enrichment and concentrations of allantoin and uric acid in urine by gas chromatography/mass spectrometry.

A method for the determination of 15N enrichment and concentration of allantoin and uric acid simultaneously in urine using gas chromatography/mass spectrometry (GC/MS) is described. The urine samples contained [1,3-15N2] uric acid and its oxidation product allantoin. The uric acid and allantoin were isolated using an AG1-X8 (Cl-form) anion-exchange column and heated with a mixture containing 1:1 dimethylformamide and N-(tert-butyldimethylsilyl)-N-methyltrifluoroacetamide (MTBSTFA). The tert-butyldimethylsilyl (TBDMS) derivatives of allantoin and uric acid formed were injected into a gas chromatograph interfaced with a mass spectrometer operated under electron impact ionization conditions. Isotope ratio measurements were made from the abundance of the M-57 ions at m/z 398, 399 and 400 for allantoin and at m/z 567 and 569 for uric acid. 15N2 allantoin (99 at.%) was produced from [1,3-15N2] uric acid by treatment with uricase and used as a standard. Quantitation of allantoin and uric acid was based on isotopic dilution by spiking the urine sample with known quantities of 99 at.% [15N] uric acid and allantoin internal standards. The observed isotope ratio measurements from the prepared standards matched the theoretical values. Coefficients of variation in measurements of isotope ratio and concentration were 0.2 and 0.5%, respectively. The method was applied in a study to measure the urinary recovery of [1,3-15N2] uric acid continuously infused for 8-10 h into the blood of four sheep each on two occasions. Within 24 h, 65.9 +/- 9.1% of the tracer was excreted in the urine unchanged. Little was converted into allantoin (approximately 7% of the dose). The total recovery (5 days) of the infused tracer averaged 69.5 +/- 7.6% as uric acid and 76.8 +/- 9.3% as the sum of uric acid and allantoin. Uricase activities in plasma, liver and kidney of sheep were also measured using [1,3-15N2] uric acid as a substrate. Uricase activity was estimated to be 0.6 mU g-1 wet tissue in the liver and there appeared to be none in plasma and kidney. The low uricase activities in sheep tissues appeared to explain the limited conversion of the intravenously administered [15N] uric acid to allantoin but did not explain the large quantities of allantoin excreted in urine (8.96 +/- 0.86 and 1.36 +/- 0.25 mmol d-1 for allantoin and uric acid, respectively). The GC/MS method for the determination of 15N enrichment and concentration of allantoin and uric acid in urine is accurate and precise and provides a useful tool for studies on uric acid and allantoin metabolism.

Allantoin↗

PubMed2000

Amphipathic structure of theonellapeptolide-Id, a hydrophobic tridecapeptide lactone from the Okinawa marine sponge Theonella swinhoei.

Theonellapeptolide-Id (TNLP), a cyclic tridecapeptide lactone, was crystallized from dimethylformamide-water solution. In the asymmetric unit, two peptide molecules were combined with solvent molecules, and the total molecular weight was over 3000 Dalton. The crystal structure including solvent molecules was finally determined at 0.80 A resolution using synchrotron radiation. The conformations of two independent molecules were similar to each other and were also similar to the previously reported structure (Doi, Ishida, Kobayashi, Deschamps and Flippen-Anderson, 1999, Acta Crystallogr Sect C, 55, 796-798). About 13 hydrated water molecules were found at disordered 19 sites; they were located at a certain region to avoid contact with aliphatic side-chains of peptolide in the crystal. The spatial disposition of the solvent molecules and peptides subsequently caused the formation of the amphipathic layer.

Animals↗