A dual-function fluorescent probe for the detection of pH values and formaldehyde

A dual-function fluorescent probe (Probe 1) was developed in this work for the separate detection of pH value and formaldehyde (HCHO). Probe 1 could recognize HCHO and the pH value from the amino group. The colour of the probe solution was changed from grey blue to light blue with the increase in the pH value, and luminous intensity became larger with the increase in formaldehyde concentration. The curve function relationship between fluorescence intensity and the pH value was also determined. A smartphone containing a colour detector for imaging was used to record the values of the three primary colours (R value, G value, and B value) for the probe solution in formaldehyde. Importantly, there was a linear functional relationship between the B*R/G value with HCHO concentration. Therefore, the probe could be used as a rapid tool for the detection of formaldehyde. More importantly, Probe 1 was successfully used to detect formaldehyde in an actual distilled liquor sample.     

Formaldehyde stress

Formaldehyde, one of the most toxic organic compounds, is produced and processed in human cells. The level of human endogenous formaldehyde is maintained at a low concentration (0.01–0.08 mmol L⁻¹ in blood) under physiological conditions, but the concentration increases during ageing (over 65 years old). Clinical trials have shown that urine formaldehyde concentrations are significantly different between elderly Alzheimer’s patients (n=91) and normal elderly volunteers (n=38) (P<0.001). Abnormally high levels of intrinsic formaldehyde lead to dysfunction in cognition such as learning decline and memory loss. Excess extracellular and intracellular formaldehyde could induce metabolic response and abnormal modifications of cellular proteins such as hydroxymethylation and hyperphosphorylation, protein misfolding, nuclear translocation and even cell death. This cellular response called formaldehyde stress is dependent upon the concentration of formaldehyde. Chronic impairments of the brain resulted from formaldehyde stress could be one of the mechanisms involved in the process of senile dementia during ageing.     

Whole blood fixation and permeabilization protocol with red blood cell lysis for flow cytometry of intracellular phosphorylated epitopes in leukocyte subpopulations.

BACKGROUND: Previous studies of intracellular expression of phospho-epitopes in human leukocytes using flow cytometry have used erythrocyte removal or lysis before fixation. Because many of the phospho-epitopes of interest are part of signaling networks that respond to the environment and turn over rapidly, the interval and manipulations used to eliminate erythrocytes from samples have the potential to introduce artifacts. We report a procedure to fix samples containing red blood cells with formaldehyde and then remove erythrocytes by lysis. Detection of phospho-Thr 202/Tyr 204-p44/42 extracellular-regulated kinase (ERK) after phorbol ester acetate (PMA) stimulation was used as a model to measure phospho-epitopes in leukocyte populations in whole blood. METHODS: Normal blood samples were activated with PMA followed by formaldehyde fixation and subsequent treatments with detergents and protein denaturants. The effects of each treatment were monitored by light scatter, selected CD expression intensity, and phosphorylated ERK (pERK) expression. RESULTS: Red cells could be lysed using 0.1% Triton X-100 after brief fixation of whole blood with 2% or 4% formaldehyde. Light scatter improved as a function of formaldehyde concentration and inversely with MeOH concentration. CD3 signal intensity increased when MeOH concentration was reduced. The ratio of pERK immunofluorescence in PMA-stimulated versus nonstimulated (control) samples was highest with high MeOH (90%) and lowest without MeOH treatment. This pattern is consistent with epitope unmasking by alcohol. The pERK epitope could also be unmasked by treatment with high salt, urea, acid, or heat, but none of these produced the level of unmasking of MeOH and each of these was associated with degradation of light scatter and CD3 staining intensity. The final procedure employed 4% formaldehyde, 0.1% Triton X-100, followed by 50% methanol denaturation. Samples prepared in this way demonstrated good preservation of light scatter and surface immunophenotypic patterns, similar to those obtained using a commercial whole blood/red blood cell lysing system (Q-Prep) and an acceptable PMA-stimulated pERK signal (essentially 100% of CD3+ cells that are pERK positive). CONCLUSIONS: Brief fixation of whole blood in 4% formaldehyde followed by treatment with Triton X-100 results in erythrocyte lysis and leukocyte light scatter and immunophenotypic features equivalent to those of other commercial lysis reagents. Intracellular pERK staining is significantly improved by treatment with methanol, but levels of MeOH above 50% degrade light scatter and CD3 expression. This protocol (formaldehyde/Triton X-100/MeOH) circumvents potential artifactual changes in phospho-epitopes due to removal of erythrocytes or erythrocyte lysis followed by fixation, and results in a pERK signal that resolves positive from negative cell populations.     

Studies on the function of blood-liquor barrier in newborn infants]

Simultaneous measurement of the electrolytic conductivity of the cerebrospinal fluid and the blood serum in newborns has revealed a concentration gradient suggesting an active transfer of electrolytes into the liquor space. The extent of this concentration drop is regarded as expressing the functional capacity of the blood-liquor barrier. Comparative investigations in healthy older children shown that constant values, corresponding to the adult age, are reached approximately at the end of the first year of life.     

Tumor Tissue-Derived Formaldehyde and Acidic Microenvironment Synergistically Induce Bone Cancer Pain

Background

There is current interest in understanding the molecular mechanisms of tumor-induced bone pain. Accumulated evidence shows that endogenous formaldehyde concentrations are elevated in the blood or urine of patients with breast, prostate or bladder cancer. These cancers are frequently associated with cancer pain especially after bone metastasis. It is well known that transient receptor potential vanilloid receptor 1 (TRPV1) participates in cancer pain. The present study aims to demonstrate that the tumor tissue-derived endogenous formaldehyde induces bone cancer pain via TRPV1 activation under tumor acidic environment.

Methodology/Principal Findings

Endogenous formaldehyde concentration increased significantly in the cultured breast cancer cell lines in vitro, in the bone marrow of breast MRMT-1 bone cancer pain model in rats and in tissues from breast cancer and lung cancer patients in vivo. Low concentrations (1∼5 mM) of formaldehyde induced pain responses in rat via TRPV1 and this pain response could be significantly enhanced by pH 6.0 (mimicking the acidic tumor microenvironment). Formaldehyde at low concentrations (1 mM to 100 mM) induced a concentration-dependent increase of [Ca²⁺]i in the freshly isolated rat dorsal root ganglion neurons and TRPV1-transfected CHO cells. Furthermore, electrophysiological experiments showed that low concentration formaldehyde-elicited TRPV1 currents could be significantly potentiated by low pH (6.0). TRPV1 antagonists and formaldehyde scavengers attenuated bone cancer pain responses.

Conclusions/Significance

Our data suggest that cancer tissues directly secrete endogenous formaldehyde, and this formaldehyde at low concentration induces metastatic bone cancer pain through TRPV1 activation especially under tumor acidic environment.     

Behaviour of DNA-RNase A complex in the presence of formaldehyde]

A formaldehyde-produced fixation of defects caused by a despiralizing action of a protein was studied in the case of DNA-RNAase A complex. The concentration of the defects fixed was measured by kinetic formaldehyde method (KF-method). It was shown that following processes take place in the complex in the presence of formaldehyde: (a) fixation of defects; (b) unwinding of DNA; (c) inactivation of the protein. The rates of all these processes depend on the concentration of formaldehyde, phi. At formaldehyde concentrations above some critical value phic the protein is inactivated before the defects are fixed. At phi less than phic the protein inactivation proceeds more slowly than the fixation of defects; at sufficiently low formaldehyde concentration no inactivation of protein occurs practically during the fixation time (20 min). The number of new defects formed during the time of fixation is linear with the formaldehyde concentration in the region where no inactivation of the protein occurs. Therefore the initial concentration of defects can be determined through an extrapolation to zero concentration of formaldehyde. On the basis of the data obtained a method is proposed for the evaluation of the number of defects in DNA caused by the despiralizing action of proteins. A model is proposed describing the behaviour of the complexes of DNA with despiralizing proteins in the presence of formaldehyde.     

Cytotoxic effects of methanol, formaldehyde, and formate on dissociated rat thymocytes: A possibility of aspartame toxicity

Aspartame is a widely used artificial sweetener added to many soft beverages and its usage is increasing in health-conscious societies. Upon ingestion, this artificial sweetener produces methanol as a metabolite. In order to examine the possibility of aspartame toxicity, the effects of methanol and its metabolites (formaldehyde and formate) on dissociated rat thymocytes were studied by flow cytometry. While methanol and formate did not affect cell viability in the physiological pH range, formaldehyde at 1–3 mmol/L started to induce cell death. Further increase in formaldehyde concentration produced a dose-dependent decrease in cell viability. Formaldehyde at 1 mmol/L or more greatly reduced cellular content of glutathione, possibly increasing cell vulnerability to oxidative stress. Furthermore, formaldehyde at 3 mmol/L or more significantly increased intracellular concentration of Ca²⁺([Ca²⁺]_i) in a dose-dependent manner. Threshold concentrations of formaldehyde, a metabolite of methanol, that affected the [Ca²⁺]_iand cellular glutathione content were slightly higher than the blood concentrations of methanol previously reported in subjects administered abuse doses of aspartame. It is suggested that aspartame at abuse doses is harmless to humans. This revised version was published online in August 2006 with corrections to the Cover Date.     

Toxicity and biodegradation of formaldehyde in anaerobic methanogenic culture

Formaldehyde is present in several industrial wastewaters including petrochemical wastes. In this study, the toxicity and degradability of formaldehyde in anaerobic systems were investigated. Formaldehyde showed severe toxicity to an acetate enrichment methanogenic culture. As low as 10 mg/L (0.33 mM) of formaldehyde in the reactor completely inhibited acetate utilization. Formaldehyde, however, was degraded while acetate utilization was inhibited. Degradation of formaldehyde (Initial concentration /=60 mg/L), formaldehyde degradation was inhibited and partial degradation was possible. The initial formaldehyde to biomass ratio, S(0)/X(0), was useful to predict the degradation potential of high formaldehyde concentrations in batch systems. When S(0)/X(0) /= 0.29, formaldehyde at higher than 60 mg/L was only partially degraded. The inhibition of formaldehyde degradation in batch systems could be avoided by repeated additions of low concentrations of formaldehyde (up to 30 mg/L). Chemostats (14-day retention time) showed degradation of 74 mg/L-d (1110 mg/L) of influent formaldehyde with a removal capacity of 164 mg/g VSS-day. A spike of 30 mg/L (final concentration in the chemostat) formaldehyde to the chemostat caused only a small increase in effluent acetate concentration for 3 days. But a spike of 60 mg/L (final concentration in the chemostat) formaldehyde to the chemostat resulted in a dramatic increase in acetate concentration in the effluent. The results also showed that the acetate enrichment culture was not acclimated to formaldehyde even after 226 days. (c) 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 55: 727-736, 1997.     

Initial microbial adhesion is a determinant for the strength of biofilm adhesion

Abstract A considerable amount of methylformate accumulated in the culture medium of methanol-grown methylotrophic yeasts. Methylformate is considered as an intermediate in a novel formaldehyde oxidation pathway. Through investigations with Pichia methanolica , methylformate formation was found to be catalysed by a new type of alcohol dehydrogenase, which was named methylformate synthase. When cells were grown on a relatively high concentration of methanol or exposed to a high concentration of formaldehyde, formation of methylformate was enhanced and the level of methylformate synthase in the cells increased. How methylformate synthase is involved in formaldehyde oxidation and formaldehyde detoxification is discussed.     

Mechanism of the cytotoxic action of formaldehyde on cultured mammalian cells

Induction and repair of DNA lesions cell inactivation and repair of potentially lethal damages (PLD) were studied after the treatment of cultured cells with formaldehyde. Formaldehyde induced the appearance of a rapidly sedimentating DNA--membrane complex. This complex may contain up to 50% of choline and no more than 3-5% of leucine or lysine incorporated in the acid insoluble cell fraction, Inhibition of DNA synthesis, induction of single strand DNA breaks and/or alkali-labile sites increased with the raise of formaldehyde concentration. A good correlation is observed between with the raise of formaldehyde concentration. A good correlation is observed between with the raise of formaldehyde concentration. A good correlation is observed between the increasing DNA quantities in the rapid sedimentation complex and the cell lethality.     

甲醛对DNA损伤的彗星实验研究

甲醛是一种遗传毒性物质。国内外学者的大量研究证实,甲醛可以引起DNA-DNA、DNA-蛋白质分子交联,但对于甲醛是否能够引起DNA分子的断裂,学界却存在分歧。本实验以颊黏膜细胞作为实验材料,通过彗星实验对甲醛的遗传毒性——尤其是DNA分子断裂作用进行了系统的研究。结果显示甲醛在较低浓度(5μmol／L,7,5μmol／L,10μmol／L)时具有断裂作用,在较高浓度(15μmol／L,30μmol／L,50μmol／L)时则具有交联作用。根据本实验的结果,本文还首次论证了甲醛断裂作用的断裂峰值(7．5μmol／L)。     

Continuous decolorization of bleached kraft effluents byCoriolus versicolor in the form of pellets

Summary Continuous decolorization of kraft black liquor by mycelial pellets ofCoriolus versicolor in the presence of glucose as co-substrate is discussed. A linear relationship was developed between the rate of decolorization and the liquor concentration. The rate constant was equal to 0.00961 gmyc^–1 h^–` at 22°C. During the continuous experiments the pellets exhibited no apparent loss of activity when the liquor concentration was in the range of 400 CU l^–1 to 5000 CU l^–1. However, in the repeated batch experiments a loss of activity was observed which was dependent on the initial liquor concentration. The half-life of pellets was equal to 4.7, 9.4 and 20.2 days for the initial liquor concentration of 1380, 31 780 and 6990 CU l^–1, respectively. The production of the extracellular enzyme, laccase, was followed but could not be used as an indicator of the ligninolytic activity. The involvement of the intracellular enzymes ofC. versicolor in the decolorization process is described.     

高效降解甲醛菌株的分离鉴定及其特性

首先对新分离的、能高效降解甲醛的两菌株A1和A2在形态学特征、生理生化特性及16S rDNA序列分析等方面进行了系统研究; 随后通过测定在液体培养过程中甲醛浓度的变化, 确定新分离菌株A1、A2降解溶液中甲醛的性能; 最后利用菌株A1、A2分别进行生物填料塔的挂膜实验, 确定其对甲醛气体的净化性能。结果表明: 菌株A1属于假单胞菌属(Pseudomonas), 菌株A2为鞘氨醇单胞菌属(Sphingomonas); 当甲醛初始浓度<1 200 mg/L时,菌株A1、A2都能完全降解溶液中的甲醛, 当甲醛浓度增高至1 600 mg/L时, 菌株A1在48 h后的甲醛降解率为50%, 菌株A2在104 h后的甲醛降解率为74.3%; 菌株A1、A2对甲醛气体的净化效率均能达到99%以上, 菌株A1的甲醛生化去除量能达到26.4 mg/(L?h), 菌株A2的甲醛生化去除量可达20.6 mg/(L?h)。     

响应面分析法优化黑根霉胞外多糖发酵工艺

实验以商品化的马铃薯葡萄糖液体培养基为基础培养基,以胞外粗多糖产量为考察指标,运用响应面分析法考察玉米浆浓度、KH₂PO₄浓度和发酵时间3个因素对胞外多糖发酵产量的影响,以获得黑根霉胞外多糖发酵最优工艺,建立高产、稳定、可控的胞外多糖发酵生产工艺技术方案。经响应面分析,各因素按照对响应值的影响顺序为：玉米浆浓度>发酵时间> KH₂PO₄浓度,且玉米浆浓度、发酵时间对胞外多糖产量的影响极显著,KH₂PO₄浓度对胞外多糖产量的影响不显著。胞外多糖发酵最优工艺为：玉米浆3.2mg/mL、KH₂PO₄ 1.5mg/mL和发酵时间132h,在此条件下胞外多糖的最大预测产量为0.824mg/mL。实验重复性好,是一个高产、稳定、可控的胞外多糖发酵生产工艺技术方案,可以指导黑根霉胞外多糖发酵。     

Selective binding of a monoclonal antibody to Aspergillus niger glucose oxidase by formaldehyde fixed human polymorphonuclear leukocytes

BACKGROUND: Many of the procedures used in handling neutrophils may affect the expression of surface antigens, and hence their quantitation by flow cytometry. METHODS: Because the enzyme glucose oxidase of Aspergillus niger is absent in human tissues, an IgM against it (mAb GO) was used as negative control in a study involving the normal expression of neutrophil specific BH2-Ag in different age groups. RESULTS: When peripheral blood leukocytes (PBL) were freshly prepared, processed and stained with FITC-mAb GO without fixation or when the cells were stained with FITC-mAb GO prior to fixation with 2% formaldehyde, both median fluorescent intensity (MFI) and per cent of positively stained polymorphonuclear leukocytes (PMN) were similar to that obtained with a background sample without any antibody. However, when PBL were fixed after isolation with different concentrations of formaldehyde and for varying durations, MFI and per cent of positively stained PMN but not of monocytes or lymphocytes with FITC-mAb GO increased in a time and concentration dependent manner. Saturation was achieved at a finite concentration of the antibody. In a competition assay unlabelled mAb GO reduced binding of FITC-mAb GO to PMN by 79% and 95% at concentrations 100 and 200 times that of FITC labelled antibody, respectively. CONCLUSIONS: These observations strongly suggest that formaldehyde fixation causes the expression or accessibility of an epitope on PMN that is specifically recognized by the mAb GO.     

The effect of formaldehyde containing fixatives on ribonuclease activity

Summary 1. The inactivation of crystalline ribonuclease by formaldehyde and formaldehyde containing fixatives (Serra's solution) is demonstrated.2. The rate of inactivation is shown to be dependent uponph, formaldehyde concentration, and time of action of the fixative.3. The effect of formaldehyde containing fixatives on the RNase activity in sections from fixed tissues is discussed, and the inactivation of that enzyme system in rat pancreas is demonstrated.With 2 Figures in the Text     

Protozoan biomass relation to nutrient and chemical oxygen demand removal in activated sludge mixed liquor

The relationship between biomass concentration to nutrient and chemical oxygen demand (COD) removal in mixed liquor supplemented with sodium acetate was investigated, using three protozoan isolates and three different initial biomass concentrations (10(1), 10(2) and 10(3) cells/mL). The study was carried out in a shaking flask environment at a shaking speed of 100 rpm for 96 h at 25 degrees C. Aliquot samples were taken periodically for the determination of phosphate, nitrate, COD and dissolved oxygen, using standard methods. The results revealed remarkable phosphate removal of 82-95% at biomass concentration of 10(3)cells/mL. A high nitrate removal of over 87% was observed at all initial biomass concentration in mixed liquor. There was an observed COD increase of over 50% in mixed liquor in at the end of 96-h incubation and this was irrespective of initial biomass concentration used for inoculation. The study shows the trend in nutrient and COD removal at different biomass concentrations of the test isolates in mixed liquor.     

Motility and eosin uptake of formaldehyde-treated ram spermatozoa

A concentration of 0.005% formaldehyde in phosphate-buffered saline (PBS) achieved complete immobilization of ram spermatozoa while also yielding good recovery of sperm motility after removal by washing. At a higher formaldehyde concentration (0.01%) recovery rate declined with increasing dilution rate. Incubation of spermatozoa in PBS containing 0.005% formaldehyde beyond 6 h at 5, 15 or 25 degrees C resulted in poor recovery rates. Of the incubation temperatures, eosin uptake was lowest at 25 degrees C. During 4 h post-wash incubation at 30 degrees C sperm motility was significantly (P less than 0.001) affected by pre-wash formaldehyde concentration which had no effect on the proportion of eosinophilic spermatozoa.     

Age-related characteristics of relationships between brain blood flow, liquor dynamics and biomechanical properties of human cranium

The peculiarities of relationships between changes of cerebral blood flow, intracranial liquor dynamics and skull biomechanics in humans were studied in an age aspect. For this aim, a non-invasive method was proposed based on concomitant registration of rheoencephalogram and transcranial dopplerogram and evaluation of relationships between intracranial volume and pulse pressure changes (P-V index). The data obtained were analyzed by pattern-phase computer processing and compared with the blood flow parameters. The investigation was carried out on healthy volunteers of 18-25, 40-50 and 65-75 years of age. It was shown that circulatory-metabolic supplying of human brain was supported by such factors as volume brain blood flow, intracranial liquor dynamics in cooperation with skull biomechanics. The cerebral blood flow decrease at aging could be compensated by increase of the reserve-compensatory abilities of the system of cranial-spinal liquor dynamics.     

Determination of formaldehyde in blood plasma by high-performance liquid chromatography with fluorescence detection

An HPLC method was developed for the determination of formaldehyde in human blood plasma. The method was based on the determination of the fluorescent product of the chemical reaction between formaldehyde and ampicillin. A 0.2-ml aliquot of blood plasma was reacted directly with ampicillin under acidic and heating conditions. The reaction product was extracted from the matrix with diethyl ether and analyzed by reversed-phase HPLC with fluorescence detection. Recoveries of spiked formaldehyde at the low ppm (μg/ml) level were between 93% and 102% with relative standard deviations less than 8%. The limits of detection and quantitation of formaldehyde in blood plasma samples were 0.46 μg/ml and 0.87 μg/ml, respectively.