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At least 1,405 records · Page 78Linked to original sources
PubMed1998

Relationships between demethylase activity, formaldehyde and oxygen during incubation of Rhodococcus erythropolis with veratrate.

Relationships between demethylase activity, formaldehyde and oxygen were investigated. Demethylase activity was measured against the following substrates: veratric, vanillic, and isovanillic acids, as well as in the presence of guaiacol. The influence of ATP and GTP on demethylase activity was also checked. Demethylase activity was found to be dependent on the capability of the cells for endogenous oxygen uptake. In some cases ATP produced the opposite effect: instead of being taken up, oxygen was released, which suggested a reversibility of the demethylation reaction. Curiously enough, GTP demonstrated the same effect. Changes in enzyme activity were correlated with those occurring in the level of formaldehyde. The latter increased after addition of ATP, but decreased after addition of GTP.

Adenosine Triphosphate↗
PubMedDate not supplied

[Influence of formaldehyde on the melting temperature of DNA].

It has been shown that formaldehyde has no marked physical effect upon DNA resulting in lowering of its melting temperature. The effect of lowering of DNA melting temperature observed earlier by other authors resulted from the process of unwinding of DNA due to chemical reactions of formaldehyde with reactive base groups.

Chemical Phenomena↗
PubMed2000

[IgE allergy due to formaldehyde paste during endodontic treatment. Apropos of 4 cases: 2 with anaphylactic shock and 2 with generalized urticaria].

We report 4 cases of allergic reaction to formaldehyde-containing root canal sealant after endodontic care: 2 anaphylactic shocks and 2 local reactions with generalized urticaria. Allergic IgE mediated mechanisms were suggested by the clinical presentation, skin tests and high levels of anti-formaldehyde IgE. These infrequent but potentially severe reactions after canal treatment led us to examine the involved mechanisms, the diagnostic procedure and the possibility of prevention in odontostomatology.

Adult↗
PubMedDate not supplied

[Alternative mechanisms of detoxication of formaldehyde, formate, and hydrogen peroxide in methylotrophic yeasts].

A new concept based on own experimental results and published data and concerning the involvement under extreme conditions of additional (nontraditional) mechanisms of formaldehyde, formate and hydrogen peroxide detoxification in methylotrophic yeast has been proposed. It has been shown that neutralization of toxic effect of formaldehyde and formate, except the known ways, includes a system of energy-dependent extrusion of formic acid into extracellular space. Detoxification of hydrogen peroxide, besides of catalase way, can be realized by means of cytochrome c peroxidase reaction. The proposed concept has been built on the basis of physiological and biochemical analysis of specially constructed mutants strains of methylotrophic yeast with certain metabolic damages. The selected mutants, used as the instrument in fundamental studies of detoxification processes, also have been successfully used for practical purposes in construction of cell biosensors and creation of enzymatic kits.

Formaldehyde↗
PubMed1998

[Determination of formaldehyde in indoor air by gas chromatography].

Formaldehyde in indoor air was collected by water, derivatized with 2,4-dinitrophenylhydrazine and extracted by cyclohexane. The sample was separated on an OV-17 and QF-1 mixed chromatographic column and determined by electron capture detector. The detection limit was 0.02 mg/L (solution), the minimum detectable concentration was 0.01 mg/m3 while 10 L indoor air was collected. The results show that this is a rapid and sensitive method with less interferences and fairly good precision. The recoveries were 71.0%-90.4% and coefficients of variation were 4.1%-6.5%. The development of this method has made a reliable methodological foundation for the determination of formaldehyde in indoor air.

Air Pollutants↗
PubMed1998

The use of biofilters to improve indoor air quality: the removal of toluene, TCE, and formaldehyde.

A biofilter composed of a scrubber, a hydroponic planting system, and an aquatic system with green plants as a base maintained air quality within part of a modern office building. The scrubber was composed of five parallel fiberglass modules with external faces of porous lava rock. The face, largely covered with mosses, was wetted by recirculating water. Air was drawn through the scrubber and the immediately adjacent hydroponic region by a dedicated air handling system. The system was challenged for 4 weeks with three common indoor organic pollutants and removed significant amounts of all compounds. A single pass through the scrubber removed 10% of the trichloroethylene and 50% of the toluene. A single pass lowered formaldehyde air concentrations to 13 micrograms m-3 irrespective of influent levels (ranging between 30 and 90 micrograms m-3). The aquatic system accumulated trichloroethylene but neither toluene nor formaldehyde, suggesting the rapid breakdown of these materials. The botanical components removed some pollutants.

Air Conditioning↗
PubMed1979

The formation of serine from glycine and formaldehyde by cell free extracts of Clostridium acidi-urici.

Cells of Clostridium acidi-urici which were grown in a medium containing uric acid were harvested, disrupted by sonication and centrifuged. After centrifugation the supernatant which served as the cell free extract was used to study the synthesis of serine from 2-14C glycine and formaldehyde. Serine was isolated from the reaction mixture by column chromatography. After identification by paper chromatography, serine was degraded carbon by carbon to locate the position of the labelled carbon. Radioactivity was confined almost exclusively to the alpha carbon of serine which was derived from the alpha carbon of glycine. Formaldehyde, therefore, binds at the alpha carbon of glycine to form serine. Conversion of serine to pyruvate was prevented by adding EDTA to the reaction mixture.

Cell-Free System↗
PubMedDate not supplied

Spectrofluorimetric determination of formaldehyde in maple syrup.

A quick and simple method was developed for determination of formaldehyde in maple syrup. In this method, formaldehyde reacts with Fluoral P to form a complex which is chemically extracted by isobutanol and determined by spectrofluorimetry. Performance, as gauged by the limits of detection (0.16 mg/kg) and quantitation (0.21 mg/kg), recovery (>79%), and variability (1.9-16.1%, depending on fortification level and class of syrup) were superior to the current official AOAC standard method.

Calibration↗
PubMed2002

Endodontic treatment of permanent teeth in children with a new calcium-carbamide-formaldehyde paste.

UNLABELLED: AIM, MATERIAL AND METHODS: Endodontic treatment of a total of 303 teeth with pulpitis and periodontitis was performed with a new calcium-carbamide-formaldehyde paste. In three children with fractured teeth with complications, the applied treatment was combined (2 teeth with apical osteotomy and 1 with cystectomy). Control examinations were carried out at months 6, 12 and 24 and clinically healthy teeth and teeth with complications were registered. RESULTS: In the pulpitis group the clinically healthy teeth were 97.55% +/- 1.08 at the 6th month; 96.85% +/- 1.26 at the 12th month and 92.92% +/- 2.41 at the 24th month. In teeth with periodontitis 91.56% +/- 3.05 were clinically healthy at the 6th month; 93.83% +/- 2.67 at the 12th month and 98.03% +/- 1.98 at the 24th month. No statistical significance of the differences between pulpites and periodontites was found (P > 0.05). Recovery of the bone structure was observed in the teeth with combined endodontic and surgical treatment at the 12th month. CONCLUSIONS: The calcium-carbamide-formaldehyde paste stimulates bone regeneration and closing of the apex without coloring the hard dental tissues.

Adolescent↗
PubMed1992

[Activity of selected enzymes of peripheral blood erythrocytes and serum haptoglobin levels in workers occupationally exposed to styrene and formaldehyde].

In 48 and 30 workers exposed to styrene and formaldehyde respectively activities of erythrocyte acetylcholinesterase lactate dehydrogenase and glucose-6-phosphate dehydrogenase, were determined. Hematocrit, haemoglobin concentration, red blood cell count and serum haptoglobin levels were also determined. Significant decrease in erythrocyte acetylcholinesterase activity in workers exposed to styrene for 61-180 months was stated. Moreover, increased erythrocyte lactate dehydrogenase activity and decreased serum haptoglobin level was found in workers exposed to formaldehyde for 3-24 months. There were no differences in basic hematological parameters and erythrocyte glucose-6-phosphate dehydrogenase activity in both groups studied as compared to the control group.

Acetylcholinesterase↗
PubMed1957

Inactivation of poliovirus by formaldehyde: theoretical and practical aspects.

Since formaldehyde, either alone or in combination with other inactivating agents, is at present used in the production of all so-called "killed" poliovirus vaccines, a thorough knowledge of the kinetics of the reaction between the chemical agent and the virus, and of the mechanisms involved, is of great practical importance. In this paper the problem is discussed against the background of present knowledge of the structure of the virus and the chemical nature of the action of formaldehyde.

Formaldehyde↗
PubMedDate not supplied

Neutrophil chemiluminescence following exposure to formaldehyde in healthy subjects and in patients with contact dermatitis.

13 formaldehyde-sensitive contact dermatitis patients and 5 healthy subjects were exposed to formaldehyde (FM) at a concentration 0.5 mg/m3, in an exposure chamber for 2 hours. There was no significant decrease of the ventilatory parameters either in healthy subjects or in contact dermatitis patients following the exposure Bronchial hyperreactivity to histamine (PC20) increased in one healthy and two patients with contact dermatitis. Neutrophils were isolated from whole venous blood before the test and 30 minutes and 24 hours after the exposure. All subjects with allergic contact dermatitis had chemiluminescence higher before the FM provocation in a comparison with the healthy ones. It increased significantly 30 minutes post the exposure and was much higher 24 hours after the exposure in the comparison with the neutrophil chemiluminescence before the test.

Adult↗
PubMed2003

[Determination of dissociate formaldehyde in cosmetics by derivative gas chromatography analysis].

A method for determination of dissociate formaldehyde in cosmetics by derivative gas chromatography analysis was presented in the paper. The lowest detection limit of analysis was 5.75 pg; the linear calibration curve for formaldehyde were measured within the range of 8.3-166 micrograms/L, and the correlative coefficient was 0.9996. It was showed that this method was simple and easy to handle, and interferential factors were less, and accuracy was high.

Chromatography, Gas↗
PubMedDate not supplied

Liquid chromatographic determination of urea in water-soluble urea-formaldehyde fertilizer products and in aqueous urea solutions: collaborative study.

Water soluble urea-formaldehyde (UF) fertilizers, manufactured by complex reaction of urea and formaldehyde, typically contain varying amounts of unreacted urea. A liquid chromatography method for the analysis of urea in these products, and in aqueous urea solutions, was collaboratively studied. An amine chromatography column was used to separate the unreacted urea from numerous UF reaction products present in these liquid fertilizers. Unreacted urea was determined by using external urea standards with UV detection at 195 nm. The standards and test samples were prepared in the mobile phase of 85% (v/v) acetonitrile in water. Ten laboratories analyzed 5 different UF-based commercial products containing unreacted urea in the range of 6 to 17% by weight, and 5 different concentrations of urea in water equivalent to commercial products of that nature. The aqueous urea solutions contained 2-20% urea (w/w). The range of s(R) values for the 5 UF-based commercial fertilizers was 0.49-1.02 and the %RSD(R) was 1.94-6.14. The s(R) range for the 5 urea solutions was 0.10 to 0.79 and the %RSD(R) range was 2.54 to 4.88. The average recovery of urea from the aqueous urea solutions was 96-103%. Therefore, this method is capable of monitoring urea nitrogen manufacturers' label claims and total nitrogen claims in those cases where urea is the sole source of plant food nitrogen. Based on the collaborative study data, the authors recommend this method be approved for AOAC Official First Action status.

Chromatography, Liquid↗
PubMed1992

Studies on dressings for dental surgery use. Part 3: Effect of gamma-radiation and of formaldehyde on properties of gelatinous dental dressings.

Gelatinous dressings were exposed to gamma-radiation or treated with formaldehyde to improve their resistance to the proteolytic effects of trypsin. After aging of the preparations, both gamma-irradiated and blank samples of gelatinous dressings were etched at a constant rate. Etching rate of the formaldehyde treated dressings decreases during storage.

Cross-Linking Reagents↗
PubMed2004

Diagnosis and treatment of dermatitis due to formaldehyde resins in clothing.

An increasing number of cases of allergic contact dermatitis secondary to formaldehyde resins used for textile finishes have been seen in our office over the last several years. Although previously reported to be more common in women, we have seen almost as many men as we have seen women with this condition, possibly because men are more likely to be occupationally sensitized to formaldehyde. We have found that patch-test reactions of only questionable strength may be clinically relevant. It has been our experience that many of these cases are of long duration before referral for patch testing. A low index of suspicion leads to a delayed diagnosis, and avoidance after diagnosis is difficult owing to the lack of labeling requirements for textile finishes. Patch testing with the textile resins Fixapret AC and Fixapret CPN most often identified patients with textile allergies. We have prepared a handout to give patients more definitive recommendations.

Allergens↗
PubMed2006

Development of carcinogenicity classifications and evaluations: the case of formaldehyde.

In this paper carcinogenicity classification and evaluations case of formaldehyde made by national and international agencies and organizations (such as European Union, International Agency for Research on Cancer, World Health Organization) both in occupational (such as American Conference of Government Industrial Hygienists, National Institute of Occupational Safety and Health and Occupational Health and Safety Administration) and non occupational environment (such as United States Environmental Protection Agency) are proposed. The differences in the database and consequently in the conclusion are described in a short historical review since formaldehyde was considered for the first time as regard as health effects.

Carcinogens↗
PubMed2006

[Formaldehyde in air of indoor and outdoor environments of urban area, relationships man's exposure].

This study presents the results of man's exposure to formaldehyde, carried out in indoor and outdoor environments in the city of Ferrara. The processes were obtained on average concentration measurements carried out for one month by indoor, outdoor and personal samplings. Concentration values obtained by personal samplings (PE) were compared to both outdoor and indoor values, the latter including domestic and working environments. The results showed that there was a significant difference between formaldeyde concentrations outdoor and PE (p = 0,03 < alpha = 0,05), while a significant difference was not found between indoor and PE. Indoor values (values as average of 38 samples) were 19,5 microg/m3, outdoor ones were 6,9 microg/m3 and PE 19,9 microg/m3. The average indoor value in domestic environments (20,7 microg/m3) was higher than the value found in working environments (17,9 microg/m3). Binary comparisons showed that indoor and outdoor, together with indoor and personal samplings, display the same variability of formaldehyde concentrations.

Air Pollutants, Occupational↗