The effects of controlled exposure to formaldehyde vapour on spores of Bacillus globigii NCTC 10073

The effects of exposure of spores of Bacillus globigii NCTC 10073 to controlled levels of formaldehyde vapour under varying environmental conditions are reported. The death rate of the micro-organism varies with the humidity and formaldehyde concentration and can be predicted for conditions within the limits of the information available. A mathematical model for the effects of formaldehyde is proposed which can be used to calculate the effects of known conditions and as the basis of a controlled formaldehyde fumigation process. Results of practical tests of such a process are described.     

Understanding microwave-stimulated Romanowsky-Giemsa staining of plastic embedded bone marrow

Summary Bone marrow smears were made and fixed in methanol or formaldehyde. Marrow sections of various thicknesses were also prepared from formaldehyde fixed marrows embedded in paraffin or plastic (glycol methacrylate). The different smears and sections were then stained by a Romanowsky-Giemsa procedure. Some specimens were stained using a standard microwave-stimulated method previously used diagnostically. The effects of technical variations were studied, including degree of microwave irradiation and the staining time. Comparisons of the resulting staining outcomes showed that microwave stimulated Romanowsky-Giemsa staining of plastic sections is a rate controlled process. Unusual aspects of the staining pattern of plastic sections (namely the purple basophilic cytoplasms and nucleoli, and blue chromatin) are due to microwave stimulation and formaldehyde fixation respectively.     

Ozone decontamination of bioclean rooms.

To establish a convenient method for decontaminating bioclean rooms, the effect of ozone at 80 mg/m3 for 72 h was compared with formaldehyde vaporization at an initial concentration of 150 mg/m3 with a gradual decrease to 20 mg/m3 during 72 h. Ozone was found to be inferior to formaldehyde in activity. When the bioclean room was decontaminated twice with ozone, the mean colony count per 10 cm2 was decreased to about the same level as when formaldehyde was used. Ozone had a strong caustic effect upon rubber materials. Despite these disadvantages, ozone decontamination was demonstrated to be superior to formaldehyde vaporization because of convenience, insignificant inhalation of the disinfectant by the hospital staff, and very rapid expulsion of the gas after ventilation. Because the disadvantages of ozone can be easily controlled, this study suggests that ozone decontamination is a promising method for maintaining bioclean rooms.     

Link between the Membrane-Bound Pyridine Nucleotide Transhydrogenase and Glutathione-Dependent Processes in Rhodobacter sphaeroides

The presence of a glutathione-dependent pathway for formaldehyde oxidation in the facultative phototroph Rhodobacter sphaeroides has allowed the identification of gene products that contribute to formaldehyde metabolism. Mutants lacking the glutathione-dependent formaldehyde dehydrogenase (GSH-FDH) are sensitive to metabolic sources of formaldehyde, like methanol. This growth phenotype is correlated with a defect in formaldehyde oxidation. Additional methanol-sensitive mutants were isolated that contained Tn5 insertions in pntA, which encodes the alpha subunit of the membrane-bound pyridine nucleotide transhydrogenase. Mutants lacking transhydrogenase activity have phenotypic and physiological characteristics that are different from those that lack GSH-FDH activity. For example, cells lacking transhydrogenase activity can utilize methanol as a sole carbon source in the absence of oxygen and do not display a formaldehyde oxidation defect, as determined by whole-cell (13)C-nuclear magnetic resonance. Since transhydrogenase can be a major source of NADPH, loss of this enzyme could result in a requirement for another source for this compound. Evidence supporting this hypothesis includes increased specific activities of other NADPH-producing enzymes and the finding that glucose utilization by the Entner-Doudoroff pathway restores aerobic methanol resistance to cells lacking transhydrogenase activity. Mutants lacking transhydrogenase activity also have higher levels of glutathione disulfide under aerobic conditions, so it is consistent that this strain has increased sensitivity to oxidative stress agents like diamide, which are known to alter the oxidation reduction state of the glutathione pool. A model will be presented to explain the role of transhydrogenase under aerobic conditions when cells need glutathione both for GSH-FDH activity and to repair oxidatively damaged proteins.     

Regulation phenomena in methanol consuming yeasts: An experiment with model discrimination

Assimilation as well as dissimilation of methanol in yeasts takes place through its oxidative intermediate formaldehyde which is several times more toxic to the growth of microorganisms than methanol itself. Still, the role of formaldehyde, produced during methanol assimilation, upon growth of yeasts is not clear. In the present paper, an attempt has been made to throw some light upon this aspect. Starting with a basic frame work for methanol uptake by yeasts, several models were developed assuming different modes of regulation of key enzymes by methanol and/or formaldehyde. The main feature of the basic framework consists in consideration of two routes for oxidation of formaldehyde to CO₂, one associated and the other not associated with production of energy. Further, the rate of energy production form the energy-associated oxidation of formaldehyde is assumed to be controlled by the rate of energy consumption by anabolic reactions. The models were discriminated by subjecting these to biological constraints. As a result, the successful model suggests that in spite of higher inherent toxicity of formaldehyde, methanol exerts the controlling influence upon growth under normal conditions.     

Importance of fixation in immunohistochemistry: use of formaldehyde solutions at variable pH for the localization of tyrosine hydroxylase

Adequate fixative in immunohistochemistry requires not only a rapid and total immobilization of the antigen, but also a sufficient preservation of its immunoreactivity and maintenance of its accessibility to the immunochemical reagents for localization. Thus, the optimal fixation condition for a specific antigen necessitates a compromise between these opposing variables and can be determined by the preparation of a series of tissues with a progressively increasing degree of fixation. Unless the results of localization using such a series is available, one must be satisfied with adequate but less than optimal results. In the present study, this principle is demonstrated using the localization of tyrosine hydroxylase in the dopaminergic system with formaldehyde as the fixative. The rate and degree of fixation with formaldehyde was shown to be highly pH dependent. By perfusing the tissue with formaldehyde at pH 6.5 (where the rate of fixation is extremely slow) it is possible to rapidly distribute the fixative homogeneously into the tissue. By suddenly changing to a formaldehyde perfusate of higher pH, the cross-linking reaction is rapidly increased. This two-step fixation procedure provides a means of obtaining a rapid and uniform immobilization of the antigen, so that its translocation can be avoided. The final degree of fixation is controlled by the duration and pH of the second fixative solution. The results obtained by increasing the pH of the second solution demonstrated that complete fixation of tyrosine hydroxylase in the dopaminergic system with formaldehyde maybe obtained using a very basic formaldehyde solution (pH 11) while still retaining immunoreactivity of the enzyme. The localization that was achieved at lower pH appeared adequate until it was compared to the results obtained by perfusion at pH 11 in the second step.     

A study of conventional formaldehyde fumigation methods

The currently recommended methods for the formaldehyde fumigation of rooms have been studied with the aid of an instrument designed to monitor the temperature, humidity and formaldehyde concentration. The results show that although the procedures are generally effective as measured by microbiological methods the conditions within the areas treated are not those expected from calculations based on the room volume and the amount of formaldehyde used. The measured formaldehyde levels in particular are much lower than predicted and indicate that formaldehyde vapour may be effective at lower concentrations than previously supposed.     

A study of conventional formaldehyde fumigation methods

The currently recommended methods for the formaldehyde fumigation of rooms have been studied with the aid of an instrument designed to monitor the temperature, humidity and formaldehyde concentration. The results show that although the procedures are generally effective as measured by microbiological methods the conditions within the areas treated are not those expected from calculations based on the room volume and the amount of formaldehyde used. The measured formaldehyde levels in particular are much lower than predicted and indicate that formaldehyde vapour may be effective at lower concentrations than previously supposed.     

Denaturation of deoxyribonucleic acid in situ effect of formaldehyde.

In situ denaturation of nuclear deoxyribonucleic acid (DNA) is studied by use of acridine orange to differentially stain native versus denatured DNA, and a flow-through cytofluorometer for measurements of cell fluorescence. Thermal- or acid-induced DNA denaturation is markedly influenced by formaldehyde. Two mechanisms of the formaldehyde action are distinguished. If cells are exposed to the agent during heating, DNA denaturation is facilitated, most likely by the direct action of formaldehyde as a "passive" denaturing agent on DNA. If cells are pretreated with formaldehyde which is then removed, DNA resistance to denaturation increases, presumably due to chromatin cross-linking. It is believed that both effects occur simultaneously in conventional techniques employing formaldehyde to study DNA in situ, and that the extent of each varies with the temperature and cell type (chromatin condensation). Thus, profiles of DNA denaturation of cells heated with formaldehyde do not represent characteristics of DNA denaturation in situ; DNA denaturation under these conditions is modulated by the reactivity of chromatin components with formaldehyde rather than by DNA interactions with the macromolecules of nuclear mileu.     

The fumigant action of formaldehyde incorporated in a semisynthetic diet on the granulosis virus of Pieris brassicae and its evaporation from the diet

If Pieris brassicae eggs contaminated with granulosis virus ¹ in the form of intact inclusion bodies are exposed to formaldehyde gas under suitable conditions, the virus can be inactivated without preventing the eggs from hatching. The formaldehyde may be derived from formalin solutions, but it is more convenient to enclose the 1-day-old eggs with the diet containing formaldehyde on which the young larvae are intended to feed and to open the jar the day before they hatch. This involves less handling than washing the eggs. As would be expected, transovarially transmitted infection is not reduced.     

The separation of vanillate o-demethylase from protocatechuate 3,4-oxygenase by ultracentrifugation

1. Protocatechuate 3,4-oxygenase in the soluble part of a cell-free extract of Pseudomonas fluorescens (strain T) sedimented more rapidly than vanillate O-demethylase under specified conditions in a preparative ultracentrifuge. 2. The supernatant from this process contained vanillate O-demethylase and formaldehyde dehydrogenase, and when supplemented with NADH oxidized vanillate with an uptake of 1 mole of oxygen/mole of substrate and accumulation of protocatechuate. 3. This uptake was decreased to 0.5mole/mole of substrate in the presence of semicarbazide as trapping agent for formaldehyde. 4. Reasons are presented for the process of methyl group removal from vanillate being oxidative demethylation.     

Studies on the mutagenic action of formaldehyde in Drosophila

Summary Drosophila males were exposed to a sublethal concentration of cyanide gas prior to the injection of formaldehyde solutions. Compared to the controls which only received formaldehyde the frequency of sex-linked lethals was increased after the cyanide pretreatment in altogether six independent experiments. These results are taken as further proof that formaldehyde exerts at least part of its mutagenic effects via the formation of peroxides. It is suggested that an excessive amount of hydrogen peroxide, due to inhibition of the cytochrome and catalase enzyme systems, favours the formation of a mutagenic, organic peroxide, presumably dihydroxydimethyl peroxide. The fact that formaldehyde exerts an inhibiting effect on catalase in its own right might be of importance for the interpretation of its mutagenic action.It was also observed that after cyanide pretreatment, the mutagenic effectiveness of a mixture of formaldehyde and hydrogen peroxide was lower than that of formaldehyde alone. These findings can be interpreted by assuming that high concentrations of dihydroxydimethyl peroxide or of a combination of cyanide and this peroxide, eliminate selectively germ cells with induced mutations. It is possible that the same explanation applies to the low mutagenic effectiveness of a mixture of formaldehyde and hydrogen peroxide compared with that of formaldehyde alone when both are preceded by cyanide.With 3 figures in the text     

Evaluation of Hot Water Treatments for Management of Ditylenchus dipsaci and Fungi in Daffodil Bulbs

Treatment of daffodil (Narcissus pseudonarcissus) bulbs in a 0.37% formaldehyde water solution at 44 C for 240 minutes is a standard practice in California for management of the stem and bulb nematode, Ditylenchus dipsaci. Recent concern over the safety of formaldehyde and growers'' requests for a shorter treatment time prompted a reevaluation of the procedure. The time (Y, in minutes) required to raise the temperature at the bulb center from 25 to 44 C was related to bulb circumference (X, in cm) and is described by the linear regression Y = -15 + 3.4X. The time required for 100% mortality of D. dipsaci in vitro without formaldehyde was 150, 60, and 15 minutes at 44, 46, and 48 C, respectively. Hot water treatment (HWT) with 0.37% formaldehyde at 44 C for 150 minutes controlled D. dipsaci and did not have a detrimental effect on plant growth and flower production. Shorter formaldehyde-HWT of 90, 45, and 30 minutes at 46, 48, and 50 C, respectively, controlled D. dipsaci but suppressed plant growth and flower production. Fungal genera commonly isolated from the bulbs in association with D. dipsaci were Penicillium sp., Fusarium oxysporum f. sp. narcissi, and Mucor plumbeus, representing 60, 25, and 5%, respectively, of the total fungi isolated. These fungi caused severe necrosis in daffodil bulbs. HWT at 44 C for 240 minutes reduced the number of colonies recovered from bulbs. The effects of formaldehyde, glutaraldehyde, and sodium hypochlorite in reducing the population of fungi within bulbs were variable. Satisfactory control of D. dipsaci within bulbs can be achieved with HWT of bulbs at 44 C for 150 minutes with 0.37% formaldehyde or at 44 C for 240 minutes without chemicals.     

THE PARTIAL REACTIVATION OF FORMOLIZED TOBACCO MOSAIC VIRUS PROTEIN

A marked reactivation of tobacco mosaic virus protein that has been partially or completely inactivated by formaldehyde was obtained by dialysis at pH 3. The activity of partially inactivated virus proteins was generally increased about 10-fold by the reactivation process. It was also found possible to reactivate completely inactive preparations to an appreciable extent. It was shown that the inactivation and the subsequent reactivation cannot be explained by the toxicity of the formaldehyde or of the formolized protein or by aggregation. Inactivation was accompanied by a decrease in amino groups as indicated by Van Slyke gasometric determinations and by colorimetric estimations using ninhydrin. Inactivation also causes a decrease in the number of groups that react with Folin''s reagent at pH 7.7. The latter are probably the indole nuclei of tryptophane, for it was demonstrated that tryptophane, glycyltryptophane, and indole propionic acid react with formaldehyde in a similar manner, while tyrosine and glycyltyrosine do not. Evidence that reactivation is accompanied by an increase in amino nitrogen and in groups that react with Folin''s reagent was obtained by colorimetric estimation. The demonstration that the addition of formaldehyde to the virus protein results in a simultaneous decrease of activity, of amino groups, and of groups that react with Folin''s phenol reagent, and that under conditions favorable for the removal of formaldehyde the virus activity is regained and the number of such groups increases, indicates that certain of these groups play at least a partial role in the structure necessary for virus activity. These changes can best be interpreted on the basis of known chemical reactions and are considered as evidence that virus activity is a specific property of the protein.     

Photochemical synthesis of biomolecules under anoxic conditions

We report the long-wavelength UV anoxic photosynthesis of uracil, various sugars (including deoxyribose and glycoaldehyde), amino acids, and other organic photoproducts. These reactions occur in mixtures of water, calcium carbonate, formaldehyde and hydrazine. Our data demonstrate that under several sets of conditions biomolecules can be formed in variety and abundance from reduced compounds (formaldehyde and hydrazine) derived from anoxic dinitrogen/carbon dioxide environments. The formaldehyde concentrations were varied from 10 mM to 0.005 mM, and the hydrazine concentrations were varied from 1 mM to 0.01 mM. The highest of these reactant concentrations were 500 and 6 times greater than those reported for earlier experiments upon the synthesis of these precursors from CO₂ or N₂, while the lowest of reactant concentrations employed here were 0.5 (formaldehyde) and 0.006 (hydrazine). Product yields were greatest when the hydrazine/formaldehyde ratio was 1, and when the reactant concentrations were low. These data suggest that organic products can be formed in variety from those amounts of formaldehyde and hydrazine precursors which are themselves formed under anoxic UV photochemical conditions. Hence these various reactions would seem to have prebiotic relevance. The UV 254 nm photon flux employed was 100 times higher than unattenuated solar flux. Durations of UV exposure were 24 hrs and 72 hrs. No experiments have been addressed to the possibility of UV flux dependency.     

Formaldehyde metabolism and formaldehyde‐induced stimulation of lactate production and glutathione export in cultured neurons

Formaldehyde is endogenously produced in the human body and brain levels of this compound are elevated in neurodegenerative conditions. Although the toxic potential of an excess of formaldehyde has been studied, little is known on the molecular mechanisms underlying its neurotoxicity as well as on the ability of neurons to metabolize formaldehyde. To address these topics, we have used cerebellar granule neuron cultures as model system. These cultures express mRNAs of various enzymes that are involved in formaldehyde metabolism and were remarkably resistant toward acute formaldehyde toxicity. Cerebellar granule neurons metabolized formaldehyde with a rate of around 200 nmol/(h × mg) which was accompanied by significant increases in the cellular and extracellular concentrations of formate. In addition, formaldehyde application significantly increased glucose consumption, almost doubled the rate of lactate release from viable neurons and strongly accelerated the export of the antioxidant glutathione. The latter process was completely prevented by inhibition of the known glutathione exporter multidrug resistance protein 1. These data indicate that cerebellar granule neurons are capable of metabolizing formaldehyde and that the neuronal glycolysis and glutathione export are severely affected by the presence of formaldehyde.     

2012年食用菌“平菇甲醛”事件浅析

对2012年4月媒体报道的青岛平菇中检测发现甲醛所引发的争论进行了剖析。综合分析国内外对食用菌和其他天然食品中甲醛含量的研究结果,以及甲醛自身的理化特性,作者认为食用菌中含有微量甲醛是食用菌自身新陈代谢的产物,从食品安全的角度考虑是安全的。文中介绍了国内外对部分食用菌中甲醛含量的测定、代谢机理和风险评估情况,其中食用菌甲醛的代谢机理值得进一步关注和探讨。     

Zinc, copper and iron concentrations in cerebral cortex of male rats exposed to formaldehyde inhalation

Retrospective cohort studies and clinical findings have suggested effects of formaldehyde exposure on the central nervous system in anatomists, embalmers and pathologists. On the other hand, harmful effects of formaldehyde inhalation on the nervous system are not well documented. The concentrations of elements such as zinc, copper and iron within the cerebral cortex indicate whether physiological conditions are maintained. In this study, adult male albino Wistar rats were exposed to formaldehyde at different concentrations (0; 6.1; 12.2 mg x m(-3)) and during different periods of time (subacute-subchronic), and body weights were recorded weekly. Zinc, copper and iron concentrations were measured in the parietal cortex using atomic absorption spectrometry after wet ashing. We conclude that subacute or subchronic exposure to formaldehyde may cause growth retardation and alter zinc, copper and iron levels in the cerebral cortex.     

An Ecological Risk Assessment of Formaldehyde

A multi-tiered environmental risk assessment of formaldehyde determined the possibility of harmful effects on organisms in certain environmental compartments in Canada. A review of the relevant information indicates that biota are exposed to formaldehyde primarily in air and, to a lesser extent, in water. Worst-case scenarios predict that the estimated exposure values likely to be encountered in Canada for water and air are not expected to exceed estimated no-effects values. Therefore, the environmental risks associated with concentrations of formaldehyde likely to be found in Canada are low.