Possible Role of Formaldehyde in the Apoptotic and Mitotic Effect of 1-Methyl-Ascorbigen

Formaldehyde-Crosslinked Nontoxic Aβ Monomers to Form Toxic Aβ Dimers and Aggregates: Pathogenicity and Therapeutic Perspectives

Alzheimer's disease (AD) is characterized by the presence of senile plaques in the brain. However, medicines targeting amyloid-beta (Aβ) have not achieved the expected clinical effects. This review focuses on the formation mechanism of the Aβ dimer (the basic unit of oligomers and fibrils) and its tremendous potential as a drug target. Recently, age-associated formaldehyde and Aβ-derived formaldehyde have been found to crosslink the nontoxic Aβ monomer to form the toxic dimers, oligomers and fibrils. Particularly, Aβ-induced formaldehyde accumulation and formaldehyde-promoted Aβ aggregation form a vicious cycle. Subsequently, formaldehyde initiates Aβ toxicity in both the early-and late-onset AD. These facts also explain why AD drugs targeting only Aβ do not have the desired therapeutic effects. Development of the nanoparticle-based medicines targeting both formaldehyde and Aβ dimer is a promising strategy for improving the drug efficacy by penetrating blood-brain barrier and extracellular space into the cortical neurons in AD patients.

Human Endogenous Formaldehyde as an Anticancer Metabolite: Its Oxidation Downregulation May Be a Means of Improving Therapy

Malignant cells are characterized by an increased content of endogenous formaldehyde formed as a by-product of biosynthetic processes. Accumulation of formaldehyde in cancer cells is combined with activation of the processes of cellular formaldehyde clearance. These mechanisms include increased ALDH and suppressed ADH5/FDH activity, which oncologists consider poor and favorable prognostic markers, respectively. Here, the sources and regulation of formaldehyde metabolism in cancer cells are reviewed. The authors also analyze the participation of oncoproteins such as fibulins, FGFR1, HER2/neu, FBI-1, and MUC1-C in the control of genes related to formaldehyde metabolism, suggesting the existence of two mutually exclusive processes in cancer cells: 1) production and 2) oxidation and elimination of formaldehyde from the cell. The authors hypothesize that the study of the anticancer properties of disulfiram and alpha lipoic acid - which affect the balance of formaldehyde in the body - may serve as the basis of future anticancer therapy.

Effective stimulation of the biotechnological potential of the medicinal white rot fungus: Phellinus pini by menadione-mediated oxidative stress

The effect of menadione (MQ; 2-methyl-1,4-naphtoquinone), a superoxide-generating agent, on the natural biodegradation system in the medicinal white rot fungus Phellinus pini was determined. While measuring the activities of extracellular manganese-dependent peroxidase (MnP) and intracellular chitinase, it was found that the application of MQ (0.75 mM) distinctly stimulated the activities of these enzymes in comparison to the control values (without MQ). Using the capillary electrophoresis (CE) method, an increase in the extracellular oxalic acid (OXA) concentration was detected during the first days after the addition of MQ. It was observed that the rate of intracellular proteolysis at pH 3.5 evidently decreased under oxidative stress conditions. Contrary to these results, the activities of serine proteases at pH 9.5 measured against fluorogenic peptide substrates distinctly increased in stressed cultures. The MQ treatment also caused an evident increase in the catalase (CAT) activity, as well as the levels of superoxide anion radicals (SORs), formaldehyde (FA), and phenolic compounds (PHC) in the experimental cultures. The results obtained confirm that prooxidants may find application as an effective way to stimulate biotechnological production of MnP and chitinase by white rot fungi.

Formaldehyde and some fully n-methylated substances in boar seminal fluids. Short communication

On the basis of recent observations it is supposed that seminal fluids may contain--mainly in hydroxymethyl groups--formaldehyde (HCHO) and quaternary ammonium compounds as potential HCHO generators, therefore, preliminary investigations were carried out for the identification of these compounds in pig seminal fluids using OPLC, HPLC and MALDI MS techniques. The fresh pig seminal fluid was frozen in liquid nitrogen, powdered and aliquots (0.25 g) were treated with 0.7 ml ethanolic dimedone solution. The suspension was centrifuged and the clear supernatant was used for analysis by OPLC or after dilution with HPLC or MALDI MS technique. After OPLC separation of formaldemethone the fully N-methylated compounds which are stayed on the start point were separated by OPLC using an other eluent system. It has been established that the HCHO is really a normal component of the pig seminal fluid, as well. It can be isolated and identified in dimedone adduct form. The measurable amount of HCHO depended on the concentration applied of dimedone. According to OPLC and MALDI MS investigations L-carnitine is the main quaternary ammonium compound in pig seminal fluid which can generate a protection of the sperm cells against environmental and other influences. Considerable differences have been found among individuals concerning concentrations of quaternary ammonium compounds in the seminal fluid of pigs.

Formalin-fixed tumor cells effectively induce antitumor immunity both in prophylactic and therapeutic conditions

BACKGROUND

Autologous whole tumor cell-based vaccinations would seem to be ideal since such vaccinations, in contrast to vaccination with a single defined antigen, have the potential to elicit a broad type of T-cell immune response to tumor-associated antigens.

OBJECTIVE

We modified formaldehyde (formalin)-fixed mouse melanoma cells and investigated the utility of those cells as sources of tumor antigens for immunotherapy.

METHODS

C57BL/6 or the proteasome activator PA28alpha-knockout mice were intradermally inoculated with 1% formalin-fixed B16 cells three times at weekly intervals either before or after tumor challenge. Simultaneously, interleukin-12 gene was transferred into the skin around immunization sites using gene gun technology. The effects were evaluated by tumor growth, antigen-specific interferon-gamma production in splenic lymphocytes, and activation of dendritic cells.

RESULTS

Fixed cells directly induced production of tumor necrosis factor-alpha in dendritic cells more effectively than did frozen and thawed cells. More than 60% of the mice immunized with fixed cells and interleukin-12 rejected the challenged B16 tumor. CD4+ T cells from those mice produced a significant amount of interferon-gamma in response to melanoma cells. Furthermore, this combined treatment showed antitumor immunity initiated by CD8+ and CD4+ T cells in the therapeutic experiments. PA28alpha/beta appeared not to be required for the development of CD8+ T cells, although it is known to be essential for the development of CD8+ T cells specific for tyrosinase-related protein-2, one of melanocyte-lineage differentiated antigens.

CONCLUSION

These results suggest that formalin-fixed autologous melanoma cells have a potential to function as effective antigen sources for immunotherapy.

Embryo toxicity and teratogenicity of formaldehyde

C-14 formaldehyde crosses the placenta and enters fetal tissues. The incorporated radioactivity is higher in fetal organs (i.e., brain and liver) than in maternal tissues. The incorporation mechanism has not been studied fully, but formaldehyde enters the single-carbon cycle and is incorporated as a methyl group into nucleic acids and proteins. Also, formaldehyde reacts chemically with organic compounds (e.g., deoxyribonucleic acid, nucleosides, nucleotides, proteins, amino acids) by addition and condensation reactions, thus forming adducts and deoxyribonucleic acid-protein crosslinks. The following questions must be addressed: What adducts (e.g., N-methyl amino acids) are formed in the blood following formaldehyde inhalation? What role do N-methyl-amino adducts play in alkylation of nuclear and mitochondrial deoxyribonucleic acid, as well as mitochondrial peroxidation? The fact that the free formaldehyde pool in blood is not affected following exposure to the chemical does not mean that formaldehyde is not involved in altering cell and deoxyribonucleic acid characteristics beyond the nasal cavity. The teratogenic effect of formaldehyde in the English literature has been sought, beginning on the 6th day of pregnancy (i.e., rodents) (Saillenfait AM, et al. Food Chem Toxicol 1989, pp 545-48; Martin WJ. Reprod Toxicol 1990, pp 237-39; Ulsamer AG, et al. Hazard Assessment of Chemicals; Academic Press, 1984, pp 337-400; and U.S. Department of Health and Human Services. Toxicological Profile of Formaldehyde; ATSDR, 1999 [references 1-4, respectively, herein]). The exposure regimen is critical and may account for the differences in outcomes. Pregnant rats were exposed (a) prior to mating, (b) during mating, (c) or during the entire gestation period. These regimens (a) increased embryo mortality; (b) increased fetal anomalies (i.e., cryptochordism and aberrant ossification centers); (c) decreased concentrations of ascorbic acid; and (d) caused abnormalities in enzymes of mitochondria, lysosomes, and the endoplasmic reticulum. The alterations in enzymatic activity persisted 4 mo following birth. In addition, formaldehyde caused metabolic acidosis, which was augmented by iron deficiency. Furthermore, newborns exposed to formaldehyde in utero had abnormal performances in open-field tests. Disparities in teratogenic effects of toxic chemicals are not unusual. For example, chlorpyrifos has not produced teratogenic effects in rats when mothers are exposed on days 6-15 (Katakura Y, et al. Br J Ind Med 1993, pp 176-82 [reference 5 herein]) of gestation (Breslin WJ, et al. Fund Appl Toxicol 1996, pp 119-30; and Hanley TR, et al. Toxicol Sci 2000, pp 100-08 [references 6 and 7, respectively, herein]). However, either changing the endpoints for measurement or exposing neonates during periods of neurogenesis (days 1-14 following birth) and during subsequent developmental periods produced adverse effects. These effects included neuroapoptosis, decreased deoxyribonucleic acid and ribonucleic acid synthesis, abnormalities in adenylyl cyclase cascade, and neurobehavioral effects (Johnson DE, et al. Brain Res Bull 1998, pp 143-47; Lassiter TL, et al. Toxicol Sci 1999, pp 92-100; Chakraborti TK, et al. Pharmacol Biochem Behav 1993, pp 219-24; Whitney KD, et al. Toxicol Appl Pharm 1995, pp 53-62; Chanda SM, et al. Pharmacol Biochem Behav 1996, pp 771-76; Dam K, et al. Devel Brain Res 1998, pp 39-45; Campbell CG, et al. Brain Res Bull 1997, pp 179-89; and Xong X, et al. Toxicol Appl Pharm 1997, pp 158-74 [references 8-15, respectively, herein]). Furthermore, the terata caused by thalidomide is a graphic human example in which the animal model and timing of exposure were key factors (Parman T, et al. Natl Med 1999, pp 582-85; and Brenner CA, et al. Mol Human Repro 1998, pp 887-92 [references 16 and 17, respectively, herein]). Thus, it appears that more sensitive endpoints (e.g., enzyme activity, generation of reactive oxygen species, timing of exposure) for the measurement of toxic effects of environmental agents on embryos, fetuses, and neonates are more coherent than are gross terata observations. The perinatal period from the end of organogenesis to the end of the neonatal period in humans approximates the 28th day of gestation to 4 wk postpartum. Therefore, researchers must investigate similar stages of development (e.g., neurogenesis occurs in the 3rd trimester in humans and neonatal days occur during days 1-14 in rats and mice, whereas guinea pigs behave more like humans). Finally, screening for teratogenic events should also include exposure of females before mating or shortly following mating. Such a regimen is fruitful inasmuch as environmental agents cause adverse effec

Formaldehyde promotes and inhibits the proliferation of cultured tumour and endothelial cells

Formaldehyde was applied in various doses (0.1-10.0 mM) to HT-29 human colon carcinoma and HUV-EC-C human endothelial cell cultures. Cell number, apoptotic and mitotic index as well as proportion of cells in S-phase was investigated by morphological methods and flow cytometry. Ten mM of formaldehyde caused high degree of cell damage and practically eradicated the cell cultures. One mM of formaldehyde enhanced apoptosis and reduced mitosis in both types of cell cultures, in a moderate manner. The low dose (0.1 mM) enhanced cell proliferation and decreased apoptotic activity of the cultured cells, the tumour cells appeared to be more sensitive. The possible role of this dose-dependent effect of formaldehyde in various pathological conditions, such as carcinogenesis and atherogenesis is discussed with emphasis on the eventual interaction between formaldehyde and hydrogen peroxide.

Development of highly selective and stable potentiometric sensors for formaldehyde determination

Two types of biosensors selective to formaldehyde have been developed on the basis of pH-sensitive field effect transistor as a transducer. Highly or partially purified alcohol oxidase (AOX) and the permeabilised cells of methylotrophic yeast Hansenula polymorpha (as a source of AOX) have been used as sensitive elements. The response time in steady-state measurement mode is in the range of 10-60 s for the enzyme-based sensors and 60-120 s for the cell-based sensor. When measured in kinetic mode the response time of all biosensors developed was less than 5 s. The linear dynamic range of the sensor output signals corresponds to 5-200 mM formaldehyde for highly and partially purified alcohol oxidase, and 5-50 mM formaldehyde for the cells. The operational stability of the biosensors is not less than 7 h, and the relative standard deviation of intra-sensor response is approximately 2 and 5% for the enzyme- and cell-based sensors, respectively. When stored at 4 degrees C, the enzyme and cell sensor responses have been found stable for more than 60 and 30 days, respectively. Both types of biosensors demonstrate a high selectivity to formaldehyde with no potentiometric response to primary alcohols, including methanol, or glycerol and glucose. The possible reasons of such unexpected high selectivity of AOX-based FET-sensors to formaldehyde are discussed. The influence of the biomembrane composition and the effect of different buffers on the sensor response to formaldehyde are also discussed.

Measurement of formaldehyde as dimedone adduct and potential formaldehyde precursors in hard tissues of human teeth by overpressured layer chromatography

Simple, automatic overpressured layer chromatographic methods for the parallel determination of endogenous formaldehyde in the form of dimedone adduct and potential formaldehyde generators (betaines) in hard tissues of human teeth are described together with an efficient densitometric evaluation. These simple procedures involve the special preparation of teeth and extraction of formaldehyde, of different binding force in teeth, with methanol containing dimedone, and the isolation of betaines with an aqueous solution of methanol.