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PubMed1978

Immunogenicity of N-[-4-(5-nitro-2-furyl)-2-thiazolyl]formamide-induced bladder cancer.

Five transplantable TCC initially induced by the carcinogen FANFT were systematically tested for individual immunogenicity and then for the presence of cross-reacting tumor antigens. The classic amputation challenge technique was used. Three of the 5 tumors were immunogenic, as determined by their ability to reduce the growth of a challenge tumor dose in mice immunized with the same bladder tumor. Prior immunization with one of the immunogenic tumors failed to reduce the incidence or growth of primary bladder tumors induced by the ingestion of 0.1% FANFT in C3H/HeJ mice. The lack of cross-reacting tumor antigens has important implications for the use of allogeneic tumor cells as an antigen source in immunotherapy.

Animals↗
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↗
PubMed1992

Stability of a model beta-sheet in water.

We have used molecular dynamics simulations to determine the stability in water of a model beta-sheet formed by two alanine dipeptide molecules with two intermolecular hydrogen bonds in the closely spaced antiparallel arrangement. In this paper we describe our computations of the binding free energy of the model sheet and a portion of the free energy surface as a function of a reaction co-ordinate for sheet formation. We used the free energy surface to identify stable conformations along the reaction co-ordinate. To determine whether or not the model sheet with two hydrogen bonds is more stable than a single amide hydrogen bond in water, we compared the results of the present calculations to results from our earlier study of linear hydrogen bond formation between two formamide molecules (the formamide "dimer"). The free energy surfaces for the sheet and formamide dimer each have two minima corresponding to locally stable hydrogen-bonded and solvent-separated configurations. The binding free energies of the model sheet and the formamide dimer are -5.5 and -0.34 kcal/mol, respectively. Thus, the model sheet with two hydrogen bonds is quite stable while the simple amide hydrogen bond is only marginally stable. To understand the relative stabilities of the model sheet and formamide dimer in terms of solute-solute and solute-water interactions, we decomposed the free energy differences between hydrogen-bonded and solvent-separated conformations into energetic and entropic contributions. The changes in the peptide-peptide energy and the entropy are roughly twice as large for the sheet as they are for the formamide dimer. The magnitude of the peptide-water energy difference for the sheet is less than twice (by about 3.5 kcal/mol) that for the formamide dimer, and this accounts for the stability of the sheet. The presence of the side-chains and/or blocking groups apparently prevents the amide groups in the sheet from being solvated as favorably in the separated arrangement as in the formamide dimer, where the amide groups are completely exposed to the solvent.

Alanine↗
PubMed1988

The influence of prebiotic-type organic molecules on the crystallization of Al and Mg hydroxides.

It is now well accepted that clays could have concentrated prebiotic organic molecules, protected them from UV radiation and served as templates and catalysts in their prebiotic evolution. A complementary question is: How did prebiotic organics in the oceans, in ground water, or in hydrothermal solutions affect the formation and inorganic evolution of oxides, hydroxides, and clay minerals? In this study predominantly amorphous Al oxyhydroxides (Al gels) and crystalline Mg hydroxyoxides were synthesized, and then crystallized and recrystallized respectively, to Al and Mg hydroxides via wet and dry (w/d) cycling using both water and organic solutions. The products that resulted were examined using IR spectroscopy and X-ray diffraction (XRD). XRD scans of the products formed by w/d cycling of the Al gels with either water or 0.1 M aqueous solutions of methanol or formaldehyde showed that bayerite (alpha Al2O3) was the major phase formed. The acetonitrile treated sample exhibited the most defined XRD peaks, and no crystalline phase could be observed by XRD of the 0.1 M formamide solution treated sample. Cycling the Mg hydroxyoxide with water, or 0.1 M solutions of methanol, formamide, formaldehyde, or acetonitrile resulted in the formation of brucite (Mg(OH)2) (in varying amounts) and of three unidentified phases. One unidentified phase, 'phase II', was observed in the formaldehyde cycled sample (and tentatively identified in the methanol and formamide cycled samples), 'phase III' in the formamide and formaldehyde cycled sample, and 'phase IV' in only the formaldehyde. XRD peaks with a spacing of approximately 11.5 Angstrom (assigned to phase III) suggest intercalation of formamide and formaldehyde into the interlayer spaces of the brucite. Phosphate treatment, prior to w/d cycling with water, and also with the above mentioned organics, while totally preventing subsequent formation of any crystalline Al hydroxide, enhanced the formation of Mg phases, shown by XRD data. Formation of brucite was impeded only by w/d cycling using concentrated methanol solution, but even these effects were reversible. The XRD scans of the products resulting from the aqueous and organic solution cycling treatments of the Mg starting materials showed peaks due to brucite and three unidentified phases. Only the brucite is evident in oriented sample XRD scans of the Mg starting material when treated with methanol, formamide, and acetonitrile. In random powder sample XRD scans of the Mg starting material treated with: 1) methanol--the unidentified phase 11 is evident, 2) formamide--phase II and III are seen, and 3) formaldehyde--phases II, III, and IV are evident.

Acetonitriles↗
PubMed2006

A novel Z-groove index characterizing myocardial surface structure.

OBJECTIVE: The role of t-tubule structures in excitation-contraction coupling of ventricular myocytes has been investigated by disruption using prolonged culture, or osmotic shock with formamide. We have used a new method, the Scanning Ion Conductance Microscope (SICM), to investigate in more detail the changes in surface structure of live myocytes during these interventions and to relate them to contractile effects. METHODS: Freshly isolated ventricular myocytes from adult rat hearts were either incubated with formamide, then washed to produce osmotic shock, or put into culture for 2, 4 and 7 days. Contractile characteristics of single myocytes were then measured using the IonOptix system, and in parallel imaged using the SICM which produces a 3-dimensional topographical representation of the cell surface. Loss of t-tubules was quantitated with confocal microscopy after staining with the membrane dye di-8-ANNEPS, and sarcomere structure revealed by immunocytochemical detection of alpha-actinin. RESULTS: Detubulation was produced by either method, with formamide equivalent to 4 day culture in quantitative measures of ANNEPS t-tubule/membrane ratio. SICM images confirmed the loss of t-tubule indentations. Disruption of the Z-groove structure and flattening of the surface were also noted with formamide and, to a lesser extent, culture. A novel Z-groove index was introduced to describe this effect more quantitatively. Contraction and relaxation were impaired by the detubulation methods, but formamide had a markedly greater depressant effect on contraction amplitude than equivalent detubulation by culture. CONCLUSION: Changes in contraction amplitude after detubulation with formamide were more closely related to the alteration in Z-groove structure than loss of t-tubules alone. As well as disrupting t-tubule-induced excitation and calcium movements, formamide may alter the transmission of contraction in the myocyte by interference with sarcomere attachment at the Z-line.

Animals↗
PubMed2004

Evaluation of cell death and proliferation in psoriatic epidermis.

BACKGROUND: Previous studies of psoriatic epidermis using the terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-biotin nick-end labeling (TUNEL) method, a type of apoptotic detection method, showed that TUNEL-positive keratinocytes were abundantly distributed in all layers of the psoriatic epidermis, although psoriasis is a hyperproliferative disorder. OBJECTIVE: We sought to clarify the nature of cell kinetics in a psoriatic epidermis on the basis of differences in the reactivities in TUNEL and formamide-induced DNA denaturation assay combined with the detection of denatured DNA with a monoclonal antibody (MAb) against single-stranded DNA (formamide-MAb assay) between the normal and psoriatic epidermides. METHODS: The kinetics of keratinocytes was evaluated by the immunohistochemistry of Ki-67 for proliferation activity and by TUNEL, TUNEL combined with transmission electron microscopy (TUNEL/TEM), and formamide-MAb assay for apoptosis. RESULTS: The number of Ki-67-positive cells in the psoriatic epidermis was significantly higher than that in the normal epidermis. In the normal epidermis, both TUNEL and formamide-MAb assay showed a similar distribution pattern, that is, both TUNEL and formamide-MAb assay-positive keratinocytes were present only in the upper granular layer. In the psoriatic epidermis, most keratinocytes were negative for the formamide-MAb assay, while TUNEL-positive cells were abundantly distributed in all layers of the psoriatic epidermis. TUNEL/TEM method clearly demonstrated that many immunogold particles that stain the sites of 3'-OH DNA ends were evenly distributed on the euchromatin in psoriatic keratinocyte nuclei, in contrast to their presence on the peripheral condensed chromatin in normal keratinocyte nuclei. CONCLUSION: The increased TUNEL reactivity in psoriatic lesions is due to the increase in the number of DNA nicks resulting from active DNA replication but not due to DNA double-strand breaks produced during the apoptotic process, and the formamide-MAb assay is a reliable method for the detection of apoptosis, particularly in the epidermis.

Antibodies, Monoclonal↗
PubMed2004

Evaluation of alternative cryoprotectants for preserving stallion spermatozoa.

Although use of cryopreserved stallion spermatozoa is currently accepted by many breed registries, utilization of this technique remains limited due to poor fertility for some stallions. One reason for these results is osmotic stress that spermatozoa experiences when the cryoprotectant (glycerol) is added to the cells prior to freezing and removal from the cells after thawing. In an effort to minimize osmotic damage, alternative cryoprotectants, having lower molecular weights and greater membrane permeability than glycerol, were evaluated to determine their effectiveness for cryopreserving stallion spermatozoa. In the first experiment, equal molar concentrations of several amides were compared to determine if they could preserve the motility of sperm as well as glycerol. At 0.55 M concentration, addition of glycerol to a skim milk-egg yolk (SMEY) diluent resulted in higher percentages of motile sperm (61%) than methyl formamide (40%) or dimethyl formamide (38%, P<0.05), while formamide, acetamide, and methyl acetamide resulted in recovery of less than 20% motile cells (P<0.05). When methyl formamide or dimethyl formamide were increased to 0.6 or 0.9 M they resulted in percentages of motile cells (48-54%) similar to that achieved with glycerol (52%). Similarly, 0.9 M ethylene glycol also resulted in similar percentages of motile cells (43%). Replacing the glucose and fructose in the SMEY diluent with either raffinose or trehalose did not result in higher percentages of motile sperm (65 and 66%, respectively) than the control SMEY (63%). Similarly, addition of methyl cellulose also did not increase the percentages of motile spermatozoa in the samples, after cryopreservation (P>0.05). In conclusion, both methyl formamide and dimethyl formamide protected stallion spermatozoa from cryodamage as effectively as glycerol. Since these compounds permeate the plasma membrane more effectively than glycerol, they should cause less osmotic damage to stallion spermatozoa than glycerol. Therefore, these compounds may prove very effective in the cryopreservation of stallion spermatozoa, and may be particularly useful for spermatozoa from stallions that produce spermatozoa that have poor post-thaw characteristics when glycerol is used as the cryoprotectant.

Acetamides↗
PubMed2007

Development of thermodynamic models for simulating probe dissociation profiles in fluorescence in situ hybridization.

Stringency in ribosomal RNA (rRNA)-targeted fluorescence in situ hybridization (FISH) is typically adjusted with formamide, and the optimum formamide concentration at which the probe can hybridize with the target rRNA, but not with rRNAs with mismatches, is to be found experimentally. This is a difficult task when target or closest non-target organisms are not available in pure culture, or when there are numerous non-targets of concern. The objective of this work was to formulate mechanistic models capable of simulating the effect of formamide on probe dissociation. Using a previously described equilibrium model of FISH [Yilmaz and Noguera (2004) Applied and Environmental Microbiology 70(12):7126-7139] as the basis, the effect of formamide on free energy changes of probe-target duplex formation (DeltaG(1)(0)) and folding of target region (DeltaG(3)(0)) was simulated to be linear, and models differing in the definitions of the slopes of these relationships (m(1) and m(3)) were calibrated using experimental dissociation profiles for 27 probes targeting the 16S rRNA of Escherichia coli (E. coli). A good level of predictive power was obtained when m(1) was linearly related to probe length and when m(3) was made proportional to DeltaG(3)(0). The effect of single mismatches on probe dissociation with formamide was also studied, although at a preliminary level. The expected changes in DeltaG(1)(0) with the introduction of mismatches were not sufficient to capture the overall trends of mismatched dissociation profiles. In conclusion, this study offers the first theoretical method to calculate dissociation profiles for perfectly matched probes, and suggests a direction to systematically evaluate the effect of formamide on mismatched probes.

Base Pair Mismatch↗
PubMed1982

N-methylformamide: antitumour activity and metabolism in mice.

The antitumour activities of N-methylformamide, N-ethylformamide and formamide against a number of murine tumours in vivo (Sarcoma 180, M5076 ovarian sarcoma and TLX5 lymphoma) have been estimated. In all cases N-methyl-formamide had significant activity, formamide had marginal or no activity and N-ethylformamide had no significant activity. N-methylformamide and N-ethylformamide were equitoxic to the TLX5 lymphoma in vitro. Formamide was found as a metabolite in the plasma and urine of animals given N-methylformamide and N-ethylformamide, but excretion profiles do not support the hypothesis that formamide is an active antitumour species formed from N-alkylformamides. No appreciable metabolism of N-methylformamide occurred under a variety of conditions with liver preparations in vitro. N-methylformamide, but not N-ethylformamide or formamide, reduced liver soluble non-protein thiols by 59.8% 1 h after administration of an effective antitumour dose.

Animals↗
PubMed1999

Some Remarks on the Components of the Liquid Surface Free Energy.

Measurements of the contact angle for water, glycerol, formamide, and ethylene glycol on paraffin, polytetrafluoroethylene (PTFE), polyethylene (PE), polyvinyl chloride (PVC), polymethyl methacrylate (PMMA), and polyethylene terephthalate, for diiodomethane on PE, PVC, PMMA, and PET, and for a series of n-alkanes from n-heptane to n-hexadecane on PTFE were made. On the basis of the contact angles obtained on paraffin, PTFE, and PE the Lifshitz-van der Waals components of the glycerol, formamide, and ethylene glycol surface free energy were determined. Next, by using the contact angle values of water, glycerol, formamide, ethylene glycol, and diiodomethane, the values of the electron-acceptor and electron-donor parameters of the acid-base components of the surface free energy of glycerol, formamide, and ethylene glycol were calculated and compared with the values taken from the literature. It was found that the Lifshitz-van der Waals component of the formamide surface free energy and the electron-acceptor and electron-donor parameters of the glycerol, formamide, and ethylene glycol surface free energy determined in the above-mentioned way differ from those determined by van Oss et al. and by Lee. They are closer to those determined on the basis of interfacial tension measurements. Using the newly determined components and parameters it was found that PVC has an electron-acceptor character in contrast to an electron-donor character in the literature. Copyright 1999 Academic Press.

Journal Article↗
PubMed2006

Theoretical studies of the transition-state structures and free energy barriers for base-catalyzed hydrolysis of amides.

The transition-state structures and free energy barriers for the rate-determining step (i.e. the formation of a tetrahedral intermediate) of base-catalyzed hydrolysis of a series of amides in aqueous solution have been studied by performing first-principle electronic structure calculations using a hybrid supermolecule-polarizable continuum approach. The calculated results and a revisit of recently reported experimental proton inventory data reveal that the favorable transition-state structure optimized for the tetrahedral intermediate formation of hydroxide ion-catalyzed hydrolysis of formamide may have three solvating water molecules remaining on the attacking hydroxide oxygen and two additional water molecules attached to the carbonyl oxygen of formamide. The calculated results have also demonstrated interesting substituent effects on the optimized transition-state geometries, on the transition-state stabilization, and on the calculated free energy barriers for the base-catalyzed hydrolysis of amides. When some or all of the hydrogen atoms of formamide are replaced by methyl groups, the total number of water molecules hydrogen-bonding with the attacking hydroxide in the transition state decreases from three for formamide to two for N-methylacetamide, N,N-dimethylformamide (DMF), and N,N-dimethylacetamide (DMA). The larger substituents of the amide hinder the solvent water molecules approaching the attacking hydroxide oxygen in the transition state and, therefore, destabilize the transition-state structure and increase the free energy barrier. By using the optimized most favorable transition-state structures, the calculated free energy barriers, i.e., 21.6 (or 21.7), 22.7, 23.1, and 26.0 kcal/mol for formamide, N-methylacetamide, DMF, and DMA, respectively, are in good agreement with the available experimental free energy barriers, i.e., 21.2, 21.5, 22.6, and 24.1 kcal/mol for formamide, N-methylacetamide, DMF, and DMA, respectively.

Acetamides↗
PubMed1994

Nonaqueous capillary electrophoresis.

This paper reports an investigation of performing capillary electrophoresis (CE) in formamide. Formamide has a higher dielectric constant than water and can solubilize many supporting electrolytes. It is commonly used in mixtures with water in electrophoretic buffers. It has higher viscosity than water and hence ions exhibit lower mobilities in formamide. As a result, higher electrolyte concentrations and electric field strengths can be used. The linearity between current and the applied voltage is better in formamide. The implications of using larger ionic strength and higher electric field strength on efficiency and analysis times in CE are demonstrated in this paper. Higher efficiencies and shorter analysis times were obtained using formamide, under similar conditions, as compared with aqueous media. Other possible implications of using nonaqueous media on Joule heating, extending the workable range of the capillary diameter, sample sizes, and detectability, are discussed.

Electrochemistry↗