Anti-inflammatory effect of Barringtonia angusta methanol extract is mediated by targeting of Src in the NF-κB signalling pathway

CONTEXT

Among the plants in the genus Barringtonia (Lecythidaceae) used as traditional medicines to treat arthralgia, chest pain, and haemorrhoids in Indonesia, Barringtonia racemosa L. and Barringtonia acutangula (L.) Gaertn. have demonstrated anti-inflammatory activity in systemic inflammatory models.

OBJECTIVE

The anti-inflammatory activity of Barringtonia angusta Kurz has not been investigated. We prepared a methanol extract of the leaves and stems of B. angusta (Ba-ME) and systemically evaluated its anti-inflammatory effects in vitro and in vivo.

MATERIALS AND METHODS

RAW264.7 cells stimulated with LPS or Pam3CSK4 for 24 h were treated with Ba-ME (12.5, 25, 50, 100, and 150 µg/mL), and NO production and mRNA levels of inflammatory genes were evaluated. Luciferase reporter gene assay, western blot analysis, overexpression experiments, and cellular thermal shift assay were conducted to explore the mechanism of Ba-ME. In addition, the anti-gastritis activity of Ba-ME (50 and 100 mg/kg, administered twice per day for two days) was evaluated using an HCl/EtOH-induced gastritis mouse model.

RESULTS

Ba-ME dose-dependently suppressed NO production [IC₅₀ = 123.33 µg/mL (LPS) and 46.89 µg/mL (Pam3CSK4)] without affecting cell viability. Transcriptional expression of iNOS, IL-1β, COX-2, IL-6, and TNF-α and phosphorylation of Src, IκBα, p50/105, and p65 were inhibited by Ba-ME. The extract specifically targeted the Src protein by binding to its SH2 domain. Moreover, Ba-ME significantly ameliorated inflammatory lesions in the HCl/EtOH-induced gastritis model.

DISCUSSION AND CONCLUSIONS

The anti-inflammatory activity of Ba-ME is mediated by targeting of the Src/NF-κB signalling pathway, and B. angusta has potential as an anti-inflammatory drug.

Step by step optimization of a sperm cryopreservation protocol for spotted wolffish (Anarhichas minor Olafsen, 1772)

Spotted wolffish Anarhichas minor reproduction in captivity is dependent on in vitro fertilization. However, low sperm volume with relatively low cell concentration and the lack of gametes synchronization (simultaneous availability of mature eggs and sperm) represent a challenge for the industry. Thus, the development of protocols for sperm storage are crucial. Four sequential experiments were conducted to optimize a sperm cryopreservation protocol for this species. First, three different cryoprotectants (DMSO; 1, 2-propanediol; and methanol) at different concentrations (5, 10, and 20%) were tested for their toxicity. No significant differences (p > 0.05) were detected between the control samples and cryoprotectants at concentration up to 10% DMSO, 10% propanediol, and 20% methanol in terms of motility parameters. Second, using the highest non-toxic concentrations of cryoprotectants, sperm was cryopreserved in 0.5 mL straws, at different distances from the liquid nitrogen (1.5, 2.5, 4.5, and 7.5 cm) that correspond to different freezing rates. Motility parameters after freezing/thawing decreased for all the cryoprotectants (p < 0.001), however, methanol had the lowest protective capacity while DMSO the highest. Afterwards, two different thawing rates (1 min at 5 °C; and 25 s at 10 °C) were tested using only 10% DMSO and 10% propanediol. Both for the DMSO and propanediol, there were no significant differences (p > 0.05) between the two thawing rates. The best results were obtained using 10% DMSO. Finally, the fertilization capacity of cryopreserved sperm (10% DMSO and thawed at 5 °C for 1 min) was tested against fresh sperm using two spermatozoa:egg ratios and 4 h gametes contact time. The ratio of eggs with normal cell cleavage, abnormal cleavage or undeveloped were counted at the 2-4 cell stage. Cryopreserved sperm showed lower fertilization capacity at a concentration of 5 × 10⁴ spermatozoa:egg compared with fresh sperm (p < 0.001). At a concentration of 5 × 10⁵ spermatozoa:egg, similar fertilizations rates to the fresh sperm were obtained. The presence of the cryoprotectant DMSO during the 4 h contact time did not affect the fertilization rate or the percentage of embryos with abnormal cleavage (p > 0.05). To cryopreserve spotted wolffish sperm it is recommended to use 10% DMSO, loaded in 0.5 mL straws, freeze at a height between 4.5 (-14.05 °C/min) and 7.5 cm (-5.9 °C/min) from liquid nitrogen for 10 min and thaw for 1 min at 5 °C (177.9 °C/min). In vitro fertilization with cryopreserved sperm should be performed with a concentration of at least 5 × 10⁵ spermatozoa per egg.

Step by step optimization of a sperm cryopreservation protocol for spotted wolffish (Anarhichas minor Olafsen, 1772)

Spotted wolffish Anarhichas minor reproduction in captivity is dependent on in vitro fertilization. However, low sperm volume with relatively low cell concentration and the lack of gametes synchronization (simultaneous availability of mature eggs and sperm) represent a challenge for the industry. Thus, the development of protocols for sperm storage are crucial. Four sequential experiments were conducted to optimize a sperm cryopreservation protocol for this species. First, three different cryoprotectants (DMSO; 1, 2-propanediol; and methanol) at different concentrations (5, 10, and 20%) were tested for their toxicity. No significant differences (p > 0.05) were detected between the control samples and cryoprotectants at concentration up to 10% DMSO, 10% propanediol, and 20% methanol in terms of motility parameters. Second, using the highest non-toxic concentrations of cryoprotectants, sperm was cryopreserved in 0.5 mL straws, at different distances from the liquid nitrogen (1.5, 2.5, 4.5, and 7.5 cm) that correspond to different freezing rates. Motility parameters after freezing/thawing decreased for all the cryoprotectants (p < 0.001), however, methanol had the lowest protective capacity while DMSO the highest. Afterwards, two different thawing rates (1 min at 5 °C; and 25 s at 10 °C) were tested using only 10% DMSO and 10% propanediol. Both for the DMSO and propanediol, there were no significant differences (p > 0.05) between the two thawing rates. The best results were obtained using 10% DMSO. Finally, the fertilization capacity of cryopreserved sperm (10% DMSO and thawed at 5 °C for 1 min) was tested against fresh sperm using two spermatozoa:egg ratios and 4 h gametes contact time. The ratio of eggs with normal cell cleavage, abnormal cleavage or undeveloped were counted at the 2-4 cell stage. Cryopreserved sperm showed lower fertilization capacity at a concentration of 5 × 10⁴ spermatozoa:egg compared with fresh sperm (p < 0.001). At a concentration of 5 × 10⁵ spermatozoa:egg, similar fertilizations rates to the fresh sperm were obtained. The presence of the cryoprotectant DMSO during the 4 h contact time did not affect the fertilization rate or the percentage of embryos with abnormal cleavage (p > 0.05). To cryopreserve spotted wolffish sperm it is recommended to use 10% DMSO, loaded in 0.5 mL straws, freeze at a height between 4.5 (-14.05 °C/min) and 7.5 cm (-5.9 °C/min) from liquid nitrogen for 10 min and thaw for 1 min at 5 °C (177.9 °C/min). In vitro fertilization with cryopreserved sperm should be performed with a concentration of at least 5 × 10⁵ spermatozoa per egg.

Cardiovascular Effects of Pharmacological Targeting of Sphingosine Kinase 1

High blood pressure is a risk factor for cardiovascular diseases. Ang II (angiotensin II), a key pro-hypertensive hormone, mediates target organ consequences such as endothelial dysfunction and cardiac hypertrophy. S1P (sphingosine-1-phosphate), produced by Sphk1 (sphingosine kinase 1), plays a pivotal role in the pathogenesis of hypertension and downstream organ damage, as it controls vascular tone and regulates cardiac remodeling. Accordingly, we aimed to examine if pharmacological inhibition of Sphk1 using selective inhibitor PF543 can represent a useful vasoprotective and cardioprotective anti-hypertensive strategy in vivo. PF543 was administered intraperitoneally throughout a 14-day Ang II-infusion in C57BL6/J male mice. Pharmacological inhibition of Sphk1 improved endothelial function of arteries of hypertensive mice that could be mediated via decrease in eNOS (endothelial nitric oxide synthase) phosphorylation at T495. This effect was independent of blood pressure. Importantly, PF543 also reduced cardiac hypertrophy (heart to body weight ratio, 5.6±0.2 versus 6.4±0.1 versus 5.9±0.2 mg/g; P<0.05 for Sham, Ang II+placebo, and Ang II+PF543-treated mice, respectively). Mass spectrometry revealed that PF543 elevated cardiac sphingosine, that is, Sphk1 substrate, content in vivo. Mechanistically, RNA-Seq indicated a decreased expression of cardiac genes involved in actin/integrin organization, S1pr1 signaling, and tissue remodeling. Indeed, downregulation of Rock1 (Rho-associated coiled-coil containing protein kinase 1), Stat3 (signal transducer and activator of transcription 3), PKC (protein kinase C), and ERK1/2 (extracellular signal-regulated kinases 1/2) level/phosphorylation by PF543 was observed. In summary, pharmacological inhibition of Sphk1 partially protects against Ang II-induced cardiac hypertrophy and endothelial dysfunction. Therefore, it may represent a promising target for harnessing residual cardiovascular risk in hypertension.

Methanol induces cytosolic calcium variations, membrane depolarization and ethylene production in arabidopsis and tobacco

Background and Aims

Methanol is a volatile organic compound released from plants through the action of pectin methylesterases (PMEs), which demethylesterify cell wall pectins. Plant PMEs play a role in developmental processes but also in responses to herbivory and infection by fungal or bacterial pathogens. However, molecular mechanisms that explain how methanol could affect plant defences remain poorly understood.

Methods

Using cultured cells and seedlings from Arabidopsis thaliana and tobacco BY2 expressing the apoaequorin gene, allowing quantification of cytosolic Ca2+, a reactive oxygen species (ROS) probe (CLA, Cypridina luciferin analogue) and electrophysiological techniques, we followed early plant cell responses to exogenously supplied methanol applied as a liquid or as volatile.

Key Results

Methanol induces cytosolic Ca2+ variations that involve Ca2+ influx through the plasma membrane and Ca2+ release from internal stores. Our data further suggest that these Ca2+ variations could interact with different ROS and support a signalling pathway leading to well known plant responses to pathogens such as plasma membrane depolarization through anion channel regulation and ethylene synthesis.

Conclusions

Methanol is not only a by-product of PME activities, and our data suggest that [Ca2+]cyt variations could participate in signalling processes induced by methanol upstream of plant defence responses.

STUDIES ON WOUND HEALING ACTIVITY OF SOME EUPHORBIA SPECIES ON EXPERIMENTAL RATS

BACKGROUND

Plants of Euphorbiaceae are used in folkloric medicines in variety of ailments and well known for chemical diversity of their isoprenoid constituents. This study was carried out to explore the preliminary wound healing potential of four Euphorbia species (E. consorbina 1, E. consorbina 2, E. inarticulata, E. balsamifera and E. schimperi).

MATERIALS AND METHODS

Excision wound surface of the animals were topically treated with ethyl acetate and methanol extracts of plants at a dose of 400 mg/kg body weight for twenty days. Povidone-iodine ointment was used as a reference drug. Wound contraction measurement and period of epithelialization were used to assess the effect of plants extracts on wound repairing.

RESULTS

The groups treated with methanol extracts of E. balsamifera and E. schimperi showed profound effects, high rate of wound contraction (100%) and decrease in epithelization period 19.00±0.40 and 18.50±0.64 respectively, followed by methanol extracts of E. consorbina 2, ethyl acetate extract of E. inarticulata and ethyl acetate extracts of E. consorbina 2 which showed significant (P <0.001) wound contraction and decrease in epithelization period. Conversely ethyl acetate extract of E. consorbina 1, E. balsamifera and E. schimperi and methanol extract of E. Consorbina 1 and E. Inarticulata treated groups was not showing significant wound healing. Methanol extracts of E. balsamifera and E. schimperi were also tested for their safety margin and found safe up to dose of 2000mg/kg body weight.

CONCLUSION

Topical application of methanol extracts of E. balsamifera and E. schimperi have potential wound healing activity which is identical with standard drug Povidone-iodine.

Novel strategy of using methyl esters as slow release methanol source during lipase expression by mut+ Pichia pastoris X33

One of the major issues with heterologous production of proteins in Pichia pastoris X33 under AOX1 promoter is repeated methanol induction. To obviate repeated methanol induction, methyl esters were used as a slow release source of methanol in lipase expressing mut⁺ recombinant. Experimental design was based on the strategy that in presence of lipase, methyl esters can be hydrolysed to release their products as methanol and fatty acid. Hence, upon break down of methyl esters by lipase, first methanol will be used as a carbon source and inducer. Then P. pastoris can switch over to fatty acid as a carbon source for multiplication and biomass maintenance till further induction by methyl esters. We validated this strategy using recombinant P. pastoris expressing Lip A, Lip C from Trichosporon asahii and Lip11 from Yarrowia lipolytica. We found that the optimum lipase yield under repeated methanol induction after 120 h was 32866 U/L, 28271 U/L and 21978 U/L for Lip C, Lip A and Lip 11 respectively. In addition, we found that a single dose of methyl ester supported higher production than repeated methanol induction. Among various methyl esters tested, methyl oleate (0.5%) caused 1.2 fold higher yield for LipA and LipC and 1.4 fold for Lip11 after 120 h of induction. Sequential utilization of methanol and oleic acid by P. pastoris was observed and was supported by differential peroxisome proliferation studies by transmission electron microscopy. Our study identifies a novel strategy of using methyl esters as slow release methanol source during lipase expression.

Endogenous methanol regulates mammalian gene activity

We recently showed that methanol emitted by wounded plants might function as a signaling molecule for plant-to-plant and plant-to-animal communications. In mammals, methanol is considered a poison because the enzyme alcohol dehydrogenase (ADH) converts methanol into toxic formaldehyde. However, the detection of methanol in the blood and exhaled air of healthy volunteers suggests that methanol may be a chemical with specific functions rather than a metabolic waste product. Using a genome-wide analysis of the mouse brain, we demonstrated that an increase in blood methanol concentration led to a change in the accumulation of mRNAs from genes primarily involved in detoxification processes and regulation of the alcohol/aldehyde dehydrogenases gene cluster. To test the role of ADH in the maintenance of low methanol concentration in the plasma, we used the specific ADH inhibitor 4-methylpyrazole (4-MP) and showed that intraperitoneal administration of 4-MP resulted in a significant increase in the plasma methanol, ethanol and formaldehyde concentrations. Removal of the intestine significantly decreased the rate of methanol addition to the plasma and suggested that the gut flora may be involved in the endogenous production of methanol. ADH in the liver was identified as the main enzyme for metabolizing methanol because an increase in the methanol and ethanol contents in the liver homogenate was observed after 4-MP administration into the portal vein. Liver mRNA quantification showed changes in the accumulation of mRNAs from genes involved in cell signalling and detoxification processes. We hypothesized that endogenous methanol acts as a regulator of homeostasis by controlling the mRNA synthesis.

Vision loss after accidental methanol intoxication: a case report

BACKGROUND

Methanol intoxication is a dangerous situation because it often results in permanent problems such as visual deterioration, metabolic disturbances, neurological dysfunction, and even death. We present, to the best of our knowledge, the first case of irreversible bilateral blindness due to methanol intoxication caused by accidental ingestion of rubbing liquid.

CASE PRESENTATION

A 49-year-old Greek man developed bilateral irreversible blindness after accidental methanol intoxication. He underwent complete ophthalmological examination, including electroretinogram, visual evoked potentials, multifocal-visual evoked potentials, and optical coherence tomography scan of the optic nerve. Complete laboratory evaluation, urine drug testing, neurological examination, and computed tomography scans were also performed. Visual acuity demonstrated no light perception bilaterally, pupils were semi-dilated and unreactive to light, while the retina was normal in both eyes. Electroretinogram was normal, while visual evoked potentials, multifocal-visual evoked potentials recording, and optical coherence tomography scanning of both optic nerve heads were pathological in both eyes. The neurological examination and the computed tomography scans did not reveal any abnormalities. The laboratory evaluation was normal and the urine drug test was negative for benzodiazepines, opiates, cocaine, amphetamines, salicylates, barbiturates, and phencyclidine.

CONCLUSION

This is the first case report of methanol intoxication which documents both anatomical and functional abnormalities by means of optical coherence tomography and electrophysiological tests correspondingly. The ocular findings and the reported electrophysiological changes support the hypothesis that methanol affects photoreceptors, Müller cells, and the retrolaminar portion of the optic nerve.

Electroretinogram and histopathologic changes of the retina after methanol intoxication

In order to study the functional and structural alterations of the retina in SD rat model after methanol intoxication, 35 rats were divided randomly into five groups administrated with saline, 3-day high dose, 7-day high dose, 3-day low dose and 7-day low dose methanol separately. The retinal function of each group was assessed by flash electroretinogram (F-ERG) 3 and 7 days after methanol poisoning. The microstructure and ultrastructure of the retina were observed at the same time. The high-dose methanol intoxication induced irreversible retinal functional and structural damages 3 days after poisoning, which included prolonged latency and reduced amplitude of the Max-reaction of F-ERG. These injuries were aggravated 7 days after poisoning. Meanwhile, the latency and amplitude of the Cone-reaction of F-ERG were also affected 3 days after poisoning, but there were no further worsening tendency 7 days after poisoning. The retinal histological analysis showed cellular edema, heteromorphy and disarrangement, tissular loosen of the inner nuclear layer and photoreceptors layer. The mitochondrial damage began at the photoreceptors layer and developed further into the inner nuclear layer. The low-dose methanol intoxication only caused transient damage of the retina. Our results showed that the function and structure of the photoreceptor and inner nuclear layer were the primary target of methanol intoxication and that the rod cells were more sensitive to methanol intoxication than the cone cells. The mitochondrial damage developed from outer layer to inner layer of the retina.

Transdermal methyl alcohol intoxication cause of pain relief

A 60-year old female patient was found comatosed at home and taken to the hospital's Emergency Department by her relatives. It was learnt that she wrapped her knees with spirit-impregnated cotton pad for pain for one week. On physical examination, only a colour change of purple violet on her knees was noted. Metabolic acidosis with increased anion gap was detected by arterial blood analysis. The patient underwent haemodialysis. She was discharged from the hospital with no complaints, alert and rational following five days of follow-up treatment, with the diagnosis of methyl alcohol poisoning.

The effect of chilling and cryoprotectants on hard coral (Echinopora spp.) oocytes during short-term low temperature preservation

Understanding chilling sensitivity and chilling injury of coral oocytes, in the presence and absence of a cryoprotectant, is important in developing cryopreservation protocols, as well as for short-term storage and transport (e.g., for species conservation). The objective of this study was to investigate the chilling sensitivity of hard coral (Echinopora spp.) oocytes and the effectiveness of methanol (as a cryoprotectant) in protecting these oocytes during short-term, low temperature preservation. Oocytes were exposed to 0.5, 1, or 2 m methanol at 5, 0, or -5 °C for 1, 2, 4, 6, 8, 16, or 32 h, and their quality determined based on adenosine triphosphate (ATP) content. Methanol at 0.5 m was the most effective means to reduce chilling-induced reduction in ATP concentrations. Coral oocytes can be stored at room temperature for 4 h in filtered nature seawater with no detrimental effect on oocyte quality; however, in the present study, oocyte survival was extended for 8 h by addition of methanol in low concentrations (0.5 or 1 m) at low temperatures (5 and 0 °C). These findings should enhance conservation efforts and facilitate low-temperature transport of endangered and threatened coral species.

Effect of starch addition on the biological conversion and microbial community in a methanol-fed UASB reactor during long-term continuous operation

The effect of starch addition on the microbial composition and the biological conversion was investigated using two upflow anaerobic sludge bracket (UASB) reactors treating methanolic wastewater: one reactor was operated with starch addition, and another reactor was operated without starch addition. Approximately 300 days of operation were performed at 30 kg COD/m(3)/d, and then, the organic load of the reactors was gradually increased to 120 kg COD/m(3)/d. Successful operation was achieved at 30 kg COD/m(3)/d in both reactors; however, the methanol-fed reactor did not perform well at 120 kg COD/m(3)/d while the methanol-starch-fed reactor did. The granule analysis revealed the granule developed further only in the methanol-starch-fed reactor. The results of the microbial community analysis revealed more Methanosaeta cells were present in the methanol-starch-fed reactor, suggesting the degradation of starch produced acetate as an intermediate, which stimulated the growth of Methanosaeta cells responsible for the extension of granules.

Safety evaluation of long term oral treatment of methanol sub-fraction of the seeds of Carica papaya as a male contraceptive in albino rats

ETHNOPHARMACOLOGICAL RELEVANCE

The manuscript is one of the series of attempts in authenticating scientific documentation of the seeds of Carica papaya being traditionally used for contraception.

AIMS OF THE STUDY

To establish safety of the methanol sub-fraction (MSF) of the seeds of Carica papaya as a male contraceptive following long term oral treatment.

MATERIALS AND METHODS

MSF was administered orally to albino rats at multiples of contraceptive dose (CD) at 50 (1x), 100 (2x), 250 (5x) and 500 (10x)mg/kg body weight daily for 52 weeks. Body weight, organs weight, morbidity, mortality, clinical chemistry, sperm analysis, histopathology and serum testosterone were evaluated to assess the safety and contraceptive efficacy.

RESULTS

MSF treatment at various dose regimens, daily for 52 weeks did not show significant changes in body weight, organs weight, food and water intake and pre-terminal deaths compared to those of control animals. Sperm count and viability in 50mg/kg body weight treated animals and the weight of epididymis, seminal vesicle and prostate of all the treated animals showed significant reduction compared to control. Cauda epididymal spermatozoa of 50mg/kg body weight treated animals were immotile. Azoospermia was observed in 100, 250 and 500 mg/kg body weight treated animals. Serum clinical parameters, serum testosterone and histopathology of vital organs were comparable to those of control animals. Histology of testis revealed adverse effects on the process of spermatogenesis, while the histology of epididymis, seminal vesicles and ventral prostate showed no changes compared to control.

CONCLUSION

The long term daily oral administration of MSF affects sperm parameters without adverse side effects and is clinically safe as a male contraceptive.

[An infant with unexplained epilepsy]

A 6-month-old male infant with an unremarkable past medical history was admitted to the emergency department in an epileptic state. The seizures were resistant to treatment with conventional drugs. The child was sedated, intubated and admitted to the intensive care department. Despite extensive investigations no underlying disease was found. The seizures persisted and the child was repeatedly admitted to the hospital. Four months after the first presentation, ventricular fibrillation occurred from which the child was successfully resuscitated. His stomach appeared to contain a disinfectant and a severe ethanol-intoxication was found, leading to the diagnosis "Munchausen syndrome by proxy". The incidence of this syndrome is underestimated. Recognition of this potentially fatal phenomenon is often difficult, resulting in a delay in diagnosis. Paediatricians and general practitioners should be aware of this syndrome in children presenting with an unusual disease or an unusual medical history reported by the parents or care providers.

Synergistically enhanced transdermal permeation and topical analgesia of tetracaine gel containing menthol and ethanol in experimental and clinical studies

The aim of this study is to observe the synergistically enhanced percutaneous penetration and skin analgesia of tetracaine gel containing menthol and ethanol through experimental and clinical studies. Four anesthetic gels containing 4% tetracaine in carbomer vehicle named T-gel (containing no menthol or ethanol), 5%M/T-gel (containing 5% menthol), 70%E/T-gel (containing 70% ethanol, an optimal concentration for antiseptic), and 5%M+70%E/T-gel (containing both 5% menthol and 70% ethanol), respectively, were fabricated. The in vitro mouse skin permeation was investigated using a Franz diffusion cell. The mouse skin morphology was examined by a scanning electron microscope. The in vivo skin analgesic effect in mice was evaluated using the von Frey tests. To determine the efficacy of tetracaine gels for managing the pain in human volunteers, a paralleled, double-blinded, placebo-controlled, randomized controlled trial design combined with verbal pain scores (VPS) was performed. The combination of menthol and ethanol (5%M+70%E/T-gel) conferred significantly higher tetracaine diffusion across full-thickness mouse skin than 5%M/T-gel, 70%E/T-gel, and T-gel. The ultra structure changes of mouse skin stratum corneum treated with 5%M+70%E/T-gel were more marked compared with those of any other tetracaine gel. von Frey tests in mice showed a synergistically enhanced effect of menthol and ethanol on the analgesia of tetracaine gel. The mean VPS were significantly lower for volunteers treated with 5%M+70%E/T-gel than those receiving other gels or the EMLA cream. 5%M+70%E/T-gel possessed the shortest anesthesia onset time, the longest anesthesia duration and the strongest anesthesia efficacy. Seventy percent ethanol in 5%M+70%E/T-gel not only improved the analgesic efficacy of the tetracaine gel through synergistically enhanced percutaneous permeation with menthol but also served as an antiseptic agent keeping drug application site from infection. 5%M+70%E/T-gel is a potential topical anesthesia preparation for clinical use.

[Studies on optimal extraction conditions of flavonoid from the flowers of Edgeworthia chrysantha]

OBJECTIVE

To study the optimum extraction process of the total flavonoids from the flowers of Edgeworthia chrysantha Lindl.

METHODS

The effect of the concentration of ethanol, extraction time and ratio of material to liquid on the total flavonoid contents were investigated by the orthonogal test with the content of tiliroside as the chemical reference.

RESULTS

The optimum extraction condition was established as follows: the concentration of ethanol 75%, extraction time 1. 5 hours and the ratio of material to liquid 1:9.

CONCLUSION

The method is simple and feasible, and is the optimum extraction process of the total flavonoids from flowers of Edgeworthia Chrysantha Lindl.

Zebrafish embryos (Danio rerio) using microinjection

Low membrane permeability is one of the major obstacles to the successful cryopreservation of zebrafish embryos. The aim of the present study was to explore if this could be overcome by yolk modification with different cryoprotectants by micro-injection. Initial investigation of two cryoprotectants, methanol and sucrose, was undertaken to determine their suitability for micro-injection supplementation of the yolk mass. Intact zebrafish embryos at 50% epiboly stage were injected with Hanks' solution, 5.2 M methanol or 1.3 M sucrose yielding approximate final concentrations of 2.0 and 0.5 M of the cryoprotectants within the yolk sac respectively. After micro-manipulation, the embryos were cultured at 28 degree C for three days and their survival assessed at the hatching stage. All micro-manipulations performed in the present study resulted in a significant decrease in embryo survival (P < 0.05). Embryos micro-injected with methanol or sucrose were also subjected to a cooling procedure. They were placed in 3M methanol + 0.5 M sucrose at room temperature for 30 min and then cooled from 20 degree C to 0 degree C at 2 degree/min, from 0 degree C to -7.5 degree/min at 1 degree/min, seeded at -7.5 degree C and held for 10 min, before cooling at 0.3 degree/min to - 20 degree C or until full crystallization in all embryos. The processes of extra- and intracellular crystallization were studied by cryomicroscopy. The temperature of intracellular crystallization did not differ significantly between control and injected embryos. However, it was found that intracellular crystallization did not always happen instantly after extracellular crystallization.

Methanol-Induced Tertiary and Secondary Structure Changes of Granulocyte-Colony Stimulating Factor

We have studied methanol-induced conformational changes in rmethuG-CSF at pH 2.5 by means of circular dichroism (CD), fluorescence and infrared (IR) spectroscopy, and 8-anilino-1-naphthalene sulfonic acid (ANS) binding. Methanol has little effect on the secondary and tertiary structures of rmethuG-CSF when its concentration is in the range of 0 to 20% (v/v). At 30% (v/v) methanol, rmethuG-CSF has ANS binding ability. In the methanol concentration range of 30 to 70% (v/v) the amount of alpha-helix decreases a little, and the tertiary structure decreases significantly. At methanol concentrations above 70% (v/v), a transition to a more helical state occurs, while there is little change in the tertiary structure, and no ANS binding ability. Thermal denaturation studies involving CD have demonstrated that as the methanol concentration increases the melting temperature and the cooperativity of transition decrease, and the transition covers a much wider range of temperature. It seems that the decreased cooperativity means an increase in the concentration of partially folded intermediate states during the unfolding of rmethuG-CSF.

Methanol‐Induced Oxidative Stress in Rat Lymphoid Organs

Methanol is primarily metabolized by oxidation to formaldehyde and then to formate. These processes are accompanied by formation of superoxide anion and hydrogen peroxide. This paper reports data on the effect of methanol on antioxidant status and lipid peroxidation in lymphoid organs such as the spleen, thymus, lymph nodes and bone marrow of rats. Male Wistar albino rats were intoxicated with methanol (2.37 g/kg b.w intraperitoneally) for detecting toxicity levels for one day, 15 d and 30 d, respectively. Administration of methanol at 15 and 30 d significantly (p<0.05) increased lipid peroxidation and decreased the enzymatic (superoxide dismutase, catalase, glutathione peroxidase) and non-enzymatic antioxidants (reduced glutathione and vitamin C) in lymphoid organs. However, lipid peroxidation and enzymatic and non-enzymatic antioxidants in the acute methanol exposed group animals were found to be significantly (p<0.05) increased. In one day methanol intoxication, the levels of free radicals initially increased, and to remove these free radicals, antioxidants levels were elevated, which generally prevented oxidative cell damage. But in longer periods of intoxication, when the generation of reactive free radicals overwhelmed the antioxidant defense, lipid peroxidation increased. Further, decreased antioxidants in 15 and 30 d methanol intoxication may have been due to overutilization of non-enzymatic and enzymatic antioxidants to scavenge the products of lipid peroxidation. In addition, the liver and kidney markers of serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), urea and creatinine significantly increased. This study concludes that exposure to methanol causes oxidative stress by altering the oxidant/antioxidant balance in lymphoid organs of the rat.

Study on fish embryo responses to the treatment of cryoprotective chemicals using impedance spectroscopy

Investigations using electrical impedance spectroscopy to measure the responses of fish embryos to the cryoprotective chemicals, methanol and dimethyl sulphoxide (DMSO), were carried out. Zebrafish (Danio rerio) embryos were used as a model to study the newly proposed technique. The normalised permittivity and conductivity changes of the embryos were measured continuously over a 20-min period in a customised embryo-holding chamber. The normalised permittivity and conductivity spectra were obtained during embryo exposure to different concentrations of methanol (1.0, 2.0 and 3.0 M) and DMSO (0.5, 1.0 and 2.0 M) solutions. The results showed significant permittivity and conductivity changes after embryo exposure to methanol and DMSO at the optimum embryo loading level (six embryos). Embryos in different concentrations of methanol and DMSO also resulted in quantitative responses shown in the normalised permittivity and conductivity spectra. The results demonstrated that fish embryo membrane permeability to cryoprotective chemicals could be monitored in real-time. The measurement of permittivity at a lower frequency range (10-10(3) Hz) and conductivity at a higher frequency range (10(4)-10(6) Hz) during fish embryo exposure to cryoprotective chemicals using impedance spectroscopy can be used as a new tool for the fast screening of most effective cryoprotective chemicals. The results from the present study also demonstrated the possibility of quantifying the level of cryoprotective chemicals penetrating the fish embryos.

Effect of methanol on endogenous and exogenous carnitine levels in rat plasma

The effect of methanol on the levels of endogenous carnitine and its derivatives was studied in male Sprague-Dawley rats aged three months. In addition, the effect of L-carnitine supplementation on metabolic disturbances caused by methanol intoxication was studied. The rats were randomized into six groups, including two control groups. Methanol was given at 1/4 LD(50) and 1/2 LD(50)/kg b.w. (or water in control) through an intragastric tube, and L-carnitine (or 0.9% NaCl in the control) was injected intraperitoneally. The levels of plasma L-carnitine and its derivatives were measured at selected time points for four days. Following methanol administration, the rats exhibited dose-dependent increases in L-carnitine levels and altered ratios of L-carnitine and its derivatives. L-carnitine supplementation accelerated the normalization of metabolic disturbances, as indicated by the acylcarnitine to free carnitine ratio (AC/FC). The protective effect of L-carnitine is supported by the fact that 100% of the methanol-treated rats supplemented with carnitine survived, while 8/60 rats and 27/101 rats died at methanol doses of 1/4 LD(50) and 1/2 LD(50), respectively, in groups without L-carnitine supplementation.

Toxicity and protective efficiency of cryoprotectants to flounder (Paralichthys olivaceus) embryos

With the purpose of finding an ideal cryoprotectant or combination of cryoprotectants in a suitable concentration for flounder (Paralichthys olivaceus) embryo cryopreservation, we tested the toxicities, at culture temperature (16 degrees C), of five most commonly used cryoprotectants-dimethyl sulfoxide (Me2SO), glycerol, methanol (MeOH), 1,2-propylene glycol (PG) and ethylene glycol (EG). In addition, cryoprotective efficiency to flounder embryos of individual and combined cryoprotectants were tested at -15 degrees C for 60 min. Five different concentrations of each of the five cryoprotectants and 20 different combinations of these cryoprotectants were tested for their protective efficiency. The results showed that the toxicity to flounder embryos of the five cryoprotectants are in the following sequence: PG < MeOH < Me2SO < glycerol < EG (P < 0.05); whereas the protective efficiency of each cryoprotectant, at -15 degrees C for a period of 60 min, are in the following sequence: PG > Me2SO approximately MeOH approximately glycerol > EG (greater symbols mean P < 0.05, and approximate symbols mean P > 0.05). Methanol combined with any one of the other cryoprotectants gave the best protection, while ethylene glycol combined with any one of the other cryoprotectants gave the poorest protection at -15 degrees C. Toxicity effect was concentration dependent with the lowest concentration being the least toxic for all five cryoprotectants at 16 degrees C. For PG, MeOH and glycerol, 20% solutions gave the best protection at -15 degrees C; whereas a 15% solution of Me2SO, and a 10% solution of EG, gave the best protection at -15 degrees C.

Intestinal villus histological alterations in piglets fed dietary charcoal powder including wood vinegar compound liquid

To investigate the effects of dietary charcoal powder including wood vinegar compound liquid (CWVC, 4 : 1) on intestinal villus histology, piglets were fed 0, 1, 3 and 5% dietary CWVC diets for 30 days. Feed intake and body weight gain were measured during the experimental period. At the end of the experiments, intestinal villus height, epithelial cell area and cell mitosis were examined using light microscopy (LM), and the duodenal villus tip surface was observed using scanning electron microscopy (SEM). Feed efficiency tended to be improved in the CWVC group. The 3% CWVC group showed the highest value, followed by 1% CWVC group of most LM parameters in most intestinal parts, but the 5% CWVC group showed the almost similar value compared with the control. In addition, on the duodenal villus tip surface, the 3% CWVC group showed a clearer cell outline, larger cells and cells protuberated further into the lumen than those of the 1% CWVC group. However, the 5% CWVC group showed faint SEM features than the 1% CWVC group. The present trend of improved feed efficiency after feedings of dietary CWVC demonstrates that the CWVC could be incorporated into piglet diets up to 3% level, and that the CWVC might activate intestinal functions both at villus and cellular levels.

The influence of L-carnitine on methanol biotransformation in rats

There persists a need for potent and safe inhibitors of alcohol dehydrogenase (ADH), to effectively treat methanol poisoning by slowing its rate of biotransformation to there toxic products, formaldehyde and formic acid. Only a few former papers have reported on the significant effectiveness of L-carnitine in treating ethanol poisoning as well as alcohol abuse. As are no reports on the effectiveness of L-carnitine in treating methanol poisoning till now, the current studies were conducted to investigate the influence of L-carnitine on both oxydative metabolism and elimination of methanol in rats. Male Sprague-Dawley rats, aged 3 months with the body weight of 200-230 g were divided into 6 groups at random, with two of the groups considered to be control. Rats were given drinking water (control) or methanol in two different doses of 3220 mg/kg b.m. or 6440 mg/kg b.m. intragastrically and 0.9% NaCl (control) or 6.2 mmol/kg b.m. of L-carnitine intraperitionelly. Within 96 hours after the administration of methanol and 0.9% NaCl or L-carnitine, the urine was collected and then the animals were decapitated. To determine methanol there were taken blood samples for clot, and to determine carnitine and its derivatives blood was taken into heparinized test tubes. During the autopsy liver was also secured. In all the experimental time points stated the methanol concentrations in blood, urine and liver homogenate were determined by a head-space gas chromatography.

Hatching of common carp (Cyprinus carpio L.) embryos stored at 4 and −2 °C in different concentrations of methanol and sucrose

The hatching performance of common carp (Cyprinus carpio L.) embryos was examined after 12-72-h storage at 4 and -2 degrees C using different concentrations of sucrose (0.1, 0.25, 0.5 and 1.0 M or 3.42, 8.55, 17.10 and 34.2%), methanol (MeOH) (0.5, 1.0, 1.5, 2.0, 2.5, 3.0 and 3.5 M or 1.6, 3.2, 4.8, 6.4, 8.0, 9.6 and 11.2%), or varying concentrations of methanol in 0.5 M (17.10%) sucrose. For sucrose, 0.5 M (17.10%) showed the maximum survival (41+/-1% (12 h) to 11+/-1.5% (72 h)) at 4 degrees C. No survival was observed at -2 degrees C with any concentration of sucrose. At both temperatures employed, hatching was higher with mixed combination of methanol (1.5 M or 4.8%) and 0.5 M (17.10%) sucrose (4 degrees C: 41+/-1.5% (12 h), 38+/-1.2% (72 h); -2 degrees C: 33+/-1.7% (12 h), 28+/-1.2% (72 h)) compared to methanol alone (4 degrees C: 38+/-1.5% (12 h), 35+/-2.5% (72 h); -2 degrees C: 31+/-2.5% (12 h), 25+/-2% (72 h)). The combination of 1.5 M (4.8%) methanol and 0.5 M (17.10%) sucrose produced the best results among all the concentrations tested at both temperatures.

A proposed inhalation reference concentration for methanol

A biologically based approach was taken to developing an inhalation Reference Concentration (RfC) for methanol, a high production volume chemical with many commercial applications, including use as an alternative fuel for motor vehicles and as a hydrogen source for fuel cells. Benchmark Dose methodology was applied to the most sensitive toxic endpoint for assessing potential health risks in humans, cervical rib malformation data obtained using CD-1 mice. The concentration of methanol in circulating blood was employed as the dose metric, and the maximum likelihood estimate of the blood methanol increment causing a 10% extra risk of these malformations, was 215.4 mg/L, with a lower 95% confidence bound of 97.4 mg/L. A "Reference Increment" for blood methanol was then determined by dividing this value by a 3-fold factor for residual pharmacodynamic uncertainty between species and a 10-fold factor for interindividual variation in human sensitivity to methanol. The resulting Reference Increment in blood methanol was then converted to an equivalent inhalation Reference Concentration with a physiologically based pharmacokinetic model evaluated for continuous exposure conditions. The resulting maximum likelihood estimate for the inhalation RfC was 298 mg/m3, with a 95% lower confidence bound of 135 mg/m3.

Effects of taurine deficiency and chronic methanol administration on rat retina, optic nerve and brain amino acids and monoamines

A chronic methanol (MeOH) intoxication scheme (2 g/kg/day ip for 2 weeks) was carried out in Sprague-Dawley rats, previously depleted of folates with methotrexate (MTX). beta-Alanine (beta-Ala), 5%, was also administered to some animals in the drinking water. Amino acids were determined in plasma, retina, optic nerve, hippocampus and posterior cortex by HPLC with fluorescence detection and monoamines in retina, hippocampus and posterior cortex by electrochemical detection. Beta-Ala administration reduced taurine (Tau) levels in plasma, hippocampus and posterior cortex, but not in retina and optic nerve. Aspartate (Asp) concentration in the optic nerve was increased in MTX-MeOH treated animals, and the administration of beta-Ala did not modify this elevation. The association of beta-Ala with MTX-MeOH produced an increase of threonine, and a decrease of 5-hydroxytryptamine (5-HT) in the retina without modifying 5-hydroxyindoleacetic acid, whereas in the hippocampus an elevation of asparagine was observed. We conclude that, in the retina, beta-Ala in combination with MTX-MeOH increased serotonin and decreased dopamine (DA) turnover rate, and resulted in changes in the amino acid balance, that could affect glycinergic activity. On the other hand, in the hippocampus, Asp metabolism could be affected by Tau depletion with beta-Ala.

Free radical changes in methanol toxicity

Role of free radicals in methanol toxicity was evaluated in methanol treated albino rats. Methanol intoxication increased lipid peroxidation and depleted the free radical scavenging enzyme systems. The free radical quenching effect of vitamin E protected the animals from methanol induced free radical damage.

Inhalational methanol toxicity in pregnancy treated twice with fomepizole

We describe a pregnant patient with a long history of inhalant abuse who came to our hospital twice during her pregnancy. In both admissions, she was treated with fomepizol (4-MP), a newly available alcohol dehydrogenase antagonist for treatment of ethylene glycol poisoning.

Effect of chronic methanol administration on amino acids and monoamines in retina, optic nerve, and brain of the rat

The clinical and electroretinographic features of chronic methanol intoxication are scarce, and neurotransmitter studies have not been conducted. In addition, most of the studies in the field include results after acute administration. In the present work, a chronic methanol intoxication scheme (2 g/kg/day ip for 2 weeks) was carried out in Sprague-Dawley rats previously depleted of folates with methotrexate. Taurine (2%) in drinking water was also administered in two groups of animals. Blood formate levels were increased in methotrexate-methanol-treated animals with respect to controls (0.98 +/- 0.09 and 0.30 +/- 0.03 mM, respectively). Amino acids and monoamines were determined in plasma and in retina, optic nerve, hippocampus, and posterior cortex by HPLC with fluorescence or electrochemical detection. The main finding was an increased aspartate content in the optic nerve in methotrexate methanol-treated animals. Methanol alone increased glutamate, aspartate, glutamine, taurine, 5-hydroxytryptamine, and 5-hydroxyindoleacetic acid levels in the hippocampus and 5-hydroxytryptamine in the retina. Taurine administration had no significant effect on changes induced by methanol treatment. We concluded that chronic methanol administration produced accumulation of aspartate, an excitotoxic amino acid, in the optic nerve. These findings contribute to the understanding of methanol neurotoxicity and might indicate a relationship between chronic methanol consumption and the development of optic neuropathies.

Exposure to 200 ppm of methanol increases the concentrations of interleukin-1beta and interleukin-8 in nasal secretions of healthy volunteers

This study was designed to investigate subclinical irritating effects of methanol on functional and immunologic parameters in human respiratory epithelia. Twelve healthy, nonsmoking individuals were exposed to concentrations of 20 and 200 ppm of methanol in an exposure chamber. The concentrations of interleukin (IL)-8, IL-1beta, IL-6, and prostaglandin E2 (PGE2) were monitored. The saccharin transport time test was used to evaluate mucociliary transport. Video interference contrast microscopy was used to determine the ciliary beat frequency of nasal epithelial cells. Subjective symptoms were assessed with a questionnaire. The median concentrations of IL-8 and IL-1beta were significantly elevated after exposure to 200 ppm of methanol as compared to exposure to 20 ppm (IL-1beta, 21.4 versus 8.3 pg/mL, p = .001; IL-8, 424 versus 356 pg/mL, p = .02). The release of IL-6 and PGE2 did not change significantly (IL-6, 10.3 versus 6.5 pg/mL, p = .13; PGE2, 13.6 versus 13.4 pg/mL), nor did the ciliary beat frequency or the saccharin transport time. Both IL-8 and IL-1beta proved to be sensitive indicators for subclinical irritating effects of methanol in vivo. The German threshold limit of 200 ppm of methanol does not prevent subclinical inflammatory reactions of the nasal respiratory mucosa.

The hatching of common carp (Cyprinus carpio L.) embryos in response to exposure to different concentrations of cryoprotectant at low temperatures

The hatching performance of embryos of the common carp (Cyprinus carpio L.) was examined after 1, 7, 14, 21, or 28 days of storage at -8, -6, -4, -2, 0, 2, or 4 degrees C with different concentrations of methanol (0.5-7.0 M in 0.5 M steps) or varying concentrations of methanol in 0.1 M sucrose or trehalose. Preserved embryos failed to hatch after storage at -8 and -6 degrees C, regardless of the duration of storage or the concentrations tested. Likewise, there was no hatching out above 5.0 M concentration of methanol, even with the addition of sucrose or trehalose. After storage at 2 or 4 degrees C, the hatching rate was higher with mixtures of methanol (1.5 M) and trehalose (0.1 M) than with methanol plus sucrose or methanol alone. At 4 degrees C, the solution containing 1.5 M methanol supplemented with trehalose gave the highest hatching response of embryos stored for 14 days. Comparison of hatching after 24h of storage at the effective temperatures (-4, -2, 0, 2, and 4 degrees C) revealed that low concentrations of methanol were effective at high temperatures and high concentrations at sub-zero temperatures. The combination of 0.1 M trehalose with 1.5 M methanol gave the highest percentage hatching out both at 4 and 2 degrees C. At 0 degrees C, the highest percentage hatching occurred with 0.1 M trehalose plus 2.5 M methanol and at -2 and 4 degrees C, the best results were with 0.1 M trehalose plus 3.0 M methanol.

Ethanol and N-acetylcysteine influence on the development of liver changes in experimental methanol intoxication

The evaluation of ethanol and N-Acetylcysteine (NAC) influence on histopathological changes in rat liver intoxicated with 3 g of methanol/kg b.w. was conducted, based on morphological examinations in light and electron microscope. The rats received intragastrically 3.0 g of methanol/kg b.w. as a 50% solution, 10% ethanol for 24 hours before methanol and next 48 hours after methanol ingestion and NAC (150 mg/kg b.w.) after 15 min. methanol administrated. The results indicate that methanol intoxication causes pronounced morphological changes in the examined organ. Ethanol administered to methanol-intoxicated rats caused intensification of certain parameters of hepatocytes morphological damage. A simultaneous administration of methanol and NAC resulted in a lower degree of parenchymal damage.

Ocular changes after intravitreal injection of methanol, formaldehyde, or formate in rabbits

We evaluated the effects of intravitreal injection of methanol, formaldehyde, or formate on rabbit eyes. One hundred microl of 1% methanol, 1% or 0.1% formaldehyde, or 1% formate was injected in the vitreous cavity of the right eyes of rabbits. The eyes were examined by biomicroscopy and ophthalmoscopy weekly. One month after injection, the eyes were enucleated and examined histologically. One week after treatment the animals that received 0.1% formaldehyde showed retinal vessel dilation, and the rabbits that received 1% formaldehyde showed mild posterior subcapsular cataract and retinal vessel dilation and haemorrhages. One month after treatment, the animals that received 0.1% or 1% formaldehyde developed mild posterior subcapsular cataract and retinal lesions. Animals that received 1% methanol or 1% formate showed nearly normal optical media and fundi. Histologically disorganized retina and optic nerve were seen in eyes that received 0.1% or 1% formaldehyde. Eyes that received 1% methanol or 1% formate appeared histologically normal. Our findings indicate that intravitreal injection of formaldehyde causes retinal and optic nerve damage, while methanol and formate are not or less toxic to ocular tissues.

Optimization of the high-level production of Rhizopus oryzae lipase in Pichia pastoris

The lipases of the Rhizopus species family are important and versatile enzymes that are mainly used in fat and oil modification due to their strong 1,3-regiospecificity. Inexpensive synthetic medium was used for the production of Rhizopus oryzae lipase in the methylotrophic yeast Pichia pastoris. Methanol accumulation inside the bioreactor has previously been shown to negatively influence the production level. Three different methanol fed-batch strategies for maintaining the methanol concentration within optimal limits have been assayed in high-density cultures. One methanol feeding strategy, which is based on the monitoring of the methanol concentration by gas chromatography, resulted in a 2.5-fold higher productivity compared to an initial cultivation, where the feeding rate was adjusted according to the dissolved oxygen concentration (DO) in the supernatant. Finally, productivity could be further increased by introducing a transition phase that involved the simultaneous feeding of glycerol and methanol followed by a single methanol feed. This optimized strategy resulted in the highest productivity (12888 U l(-1) h(-1)), which is 13.6-fold higher than the DO-based strategy.

Acute effects on the human EEG after an external exposure to 200 ppm methanol

OBJECTIVES

Even low concentrations of organic solvents may cause acute effects on the human central nervous system. The German MAK (threshold limit value) of methanol is 200 ppm. The aim of this study was to investigate whether acute exposure to 200 ppm methanol causes adverse effects, measured by EEG, and moreover, whether it is possible to differentiate between sedative and excitatory effects with this method.

METHODS

Twelve healthy subjects were exposed for 4 h to 200 ppm and to 20 ppm (control) in an exposure chamber in a cross-over design. The EEG was recorded before (reference) and at the end of each exposure with, the subject's eyes closed and opened and during a choice reaction test (color word stress test). Spectral power was calculated by fast Fourier transformation. Subjective symptoms and effects of blinding with 20 ppm methanol were assessed by questionnaires.

RESULTS

The study was a single-blind one. During subjects' exposure to 200 ppm, their scores for prenarcotic and irritating symptoms were not different from controls. In the closed-eye condition of subjects, the spectral power of the theta-band and of some electrodes of the delta-band was significantly less at the end of exposure to 200 ppm, than that of controls. In the open-eye condition and during the color word stress test no significant changes were found.

CONCLUSION

The changes in the theta-band suggest a slight excitatory effect of 200 ppm methanol. The effect was weak, as scores of acute symptoms did not change. With respect to our results, it is not necessary for the MAK value to be decreased.

Effect of repeated exposure to methanol and toluene vapor on the metabolism of rats

Wistar male rats were repeatedly exposed to methanol and toluene vapors individually and simultaneously by inhalation 6 hours a day, five days a week for 4 weeks. Blood was obtained from the tail of the rats up to 23 hours after the end of 4-week exposure and the methanol and toluene concentrations were measured. Major metabolites of methanol and toluene, that is, formic acid and hippuric acid in urine were measured up to 6 days after the end of 4-week exposure. The biological half time of toluene in blood in the simultaneous exposure group was shorter than that in the toluene exposure group. This tendency was almost the same as that for one-day exposure, although the biological half time of solvents in the rat blood was prolonged. The half times of methanol were also longer than those for one-day exposure.

Invasion and distribution of methanol

After the enzyme systems responsible for methanol oxidation were blocked by ethanol, five test persons were given methanol at a dose of approximately 10 mg/kg weight, once orally and once parenterally. Taking into account the endogenous blood methanol levels detectable before the administration of methanol, C0 concentrations of 11.1-15.9 mg/kg were reached. This corresponds to a distribution volume of approximately 0.77 +/- 0.07 l/kg, which is comparable to the 0.78 +/- 0.09 l/kg obtained for ethanol. After parenterally administering methanol as a bolus, the distribution half-life was on average 8 min (range: 3.8-13.8 min). After oral administration of methanol diluted in 100 ml water on an empty stomach, invasion took place with a half-life of approximately 5 min (3.8-6.9 min). In one case, however, due to vegetative disturbances the invasion half-life was 23.1 min.

Acute methanol intoxication generates free radicals in rats: an ESR spin trapping investigation

Electron spin resonance (ESR) spectroscopy has been used to investigate free radical generation in rats with acute methanol poisoning. The spin trapping technique was used where a spin trapping agent, alpha-(4-pyridyl 1-oxide)-N-tert-butylnitrone (POBN), reacted with the corresponding alcohol-derived or alcohol-dependent radical to form radical adducts. One radical adduct was detected in both bile and urine samples 2 h after acute methanol poisoning in male Sprague Dawley rats. The hyperfine coupling constants for the radical adduct from [(13)C]-labeled methanol detected in the bile were a(N) = 15.58, a(beta)(H) = 2.81 G, and a(beta)(13C) = 4.53 G, which unambiguously identified this species as POBN/*CH@OH. The same radical adduct was detected in urine. The identification of a methanol-derived radical adduct in samples from bile and urine provided strong direct evidence for the generation of the alcohol-derived radicals during acute intoxication by methanol. Simultaneous administration of the alcohol dehydrogenase inhibitor 4-methylpyrazole and methanol resulted in an increase in the generation of the free radical metabolite detected in the bile. This is the first ESR evidence of methanol-derived free radical generation in an animal model of acute methanol intoxication.

Analysis of methanol or formic acid in body fluids by headspace solid-phase microextraction and capillary gas chromatography

Methanol and its metabolite formic acid have been found extractable from human whole blood and urine by headspace solid-phase microextraction (SPME) with a Carboxen/polydimethylsiloxane fiber. The headspace SPME for formic acid was carried out after derivatization to methyl formate under acidic conditions. The determinations of both compounds were made by using acetonitrile as internal standard (IS) and capillary gas chromatography (GC) with flame ionization detection. The headspace SPME-GC gave sharp peaks for methanol, methyl formate and I.S.; and low background noises for whole blood and urine samples. Extraction efficiencies were 0.25-1.05% of methanol and 0.38-0.84% formic acid for whole blood and urine. The calibration curves for methanol and formic acid showed excellent linearity in the range of 1.56 to 800 and 1.56 to 500 microg/0.5 ml of whole blood or urine, respectively. The detection limits were 0.1-0.5 microg/0.5 ml for methanol and 0.6 microg/0.5 ml for formic acid for both body fluids. The within-day relative standard deviations in terms of extraction efficiency for both compounds in whole blood and urine samples were not greater than 9.8%. By using the established SPME method, methanol and formic acid were successfully separated and determined in rat blood after oral administration of methanol.

Reproductive and offspring developmental effects following maternal inhalation exposure to methanol in nonhuman primates

INTRODUCTION

In an effort to improve air quality and decrease dependence on petroleum, the federal government, industry, and other groups have encouraged development of alternative fuels such as methanol to substitute for gasoline or diesel fuel. Methanol is also a candidate to provide the hydrogen for fuel cells, which are being developed for a variety of power sources (including motor vehicle engines). Before people are exposed to increased concentrations of methanol, the potential health effects of such exposures require study. Methanol, a simple alcohol containing one carbon atom, occurs naturally in plants and animals and participates in human metabolism. People regularly consume low doses of methanol in fruits, vegetables, and fermented beverages as well as soft drinks and foods sweetened with aspartame (which breaks down to methanol in the gastrointestinal tract). Despite its ubiquitous presence, methanol can be highly toxic if sufficient quantities are consumed. Ingestion of methanol (usually in the form of wood alcohol or tainted alcoholic beverages) can result in metabolic acidosis, blindness, and even death. Although the body has the capacity to metabolize the low doses of methanol to which people are regularly exposed, it cannot handle high doses because too much methanol overwhelms the body's ability to remove a toxic metabolite (formate). When formate accumulates, methanol poisoning occurs. One factor that regulates the rate at which formate is removed is the liver level of a derivative of the vitamin folic acid. People who are deficient in folic acid (including 15% to 30% of pregnant women) may be particularly susceptible to the toxic effects of methanol. If methanol were to be widely adopted as a fuel, environmental exposures would increase through ingestion of contaminated drinking water, inhalation of vapors from evaporative and other emissions, and dermal contact. Current concentrations of methanol in ambient air are very low, 1 to 30 parts per billion (ppb). If all motor vehicles in the United States were converted to 100% methanol fuel, methanol levels in ambient air are estimated to increase approximately 1,000-fold (to 1 to 10 ppm in cities) and in a worst-case situation could occasionally reach concentrations as high as 200 ppm in enclosed spaces (HEI 1987). Inhaling these concentrations of methanol for short periods of time is not predicted to affect formate production and thus should not present a health risk. However, little is known about the consequences of long-term inhalation of methanol vapors, especially in susceptible populations of pregnant women and developing fetuses. HEI, therefore, developed a research program to address this information gap.

APPROACH

Dr. Thomas Burbacher and colleagues of the University of Washington studied the effects of long-term exposure to methanol vapors on metabolism and reproduction in adult female monkeys (Macaca fascicularis) and developmental effects in their offspring, who were exposed prenatally to methanol. The investigators exposed adult female monkeys (11 to 12 animals/group) to one of four concentrations of methanol vapors (0, 200, 600, and 1,800 ppm) for 2.5 hours a day, seven days a week during the following periods: (1) before breeding, (2) during breeding, and (3) during pregnancy. They collected blood from the adults at regular intervals to monitor methanol levels (which served as a marker of internal dose) and formate concentrations. They also conducted pharmacokinetic studies to determine whether methanol disposition (which includes absorption, distribution, metabolism, and excretion) was altered as a result of repeated methanol exposures and to assess pregnancy-related changes. Because high doses of methanol damage the central nervous system, the infants (8 to 9 animals/group) were examined at regular intervals during the first nine months of life to assess their growth and neurobehavioral development.

RESULTS

Exposure to methanol vapors did n

Determination of capsaicin and dihydrocapsaicin by micellar electrokinetic capillary chromatography and its application to various species of Capsicum, Solanaceae

An easy, rapid and sensitive method of analysis for capsaicin and dihydrocapsaicin and its application for determination of these two amides in fruit extracts of different varieties of Capsicum frutescens by micellar electrokinetic capillary chromatography has been developed. Optimum separation was achieved with a fused-silica capillary column (600 mm x 0.075 mm I.D) and a running buffer at pH 9.0 prepared from 15 mM sodium tetraborate and 15 mM sodium dihydrogenphosphate, and 67.5 mM sodium dodecyl sulphate. Addition of 15% (v/v) methanol in the running buffer was found to be essential for the separation. The applied voltage was +22.5 kV. The compounds were detected by UV at 214 nm. Both capsaicin and dihydrocapsaicin were detected within 11 min, with an excellent resolution.

The comparison of the antioxidant defense potential of brain to liver of rats after methanol ingestion

The antioxidant enzymatic and nonenzymatic potential in the brain of rats given methanol orally was investigated for 7 days consecutively and compared to that one in the liver. Glutathione (GSH) and the activities of superoxide dismutase (Cu, Zn-SOD), glutathione peroxidase (GSH-Px) and glutathione reductase (GSSG-R) were reduced in the brain after the first 24 h, whereas in the liver these parameters were diminished after 6 h. The brain catalase (CAT) activity was very low and constant in contrast to high and changeable CAT in the liver. At the beginning of intoxication, the activities of Cu, Zn-SOD and CAT in the liver were increased; after 5 days they were restored to normal values while Cu, Zn-SOD diminished gradually in the brain. An early change that occurred 6 h after intoxication was a decrease of ascorbate in the brain and in the liver. The increase in thiobarbituric acid-reactive substances (TBA-rs) in the liver was preceded by their increase in the brain. Our findings indicate decreased antioxidative potential both in the brain and in the liver of rats after methanol ingestion. The regulatory mechanisms of the antioxidant enzymes in the brain of intoxicated rats differ from those ones in the liver.