Preparation of Activated Biocarbons from Cones and their Potential Application for Adsorption of Antibiotics (Tetracycline).

The pine cones (PC), spruce cones (SC) and fir cones (FC) were used for biocarbons preparation. Chemical activation with sodium hydroxide was applied to prepare activated biocarbons. All the materials under investigation were characterized by the N2 adsorption, scanning electron microscopy (SEM), elemental analysis (CHNS), infrared spectroscopy (ATR FT-IR), and the Boehm's titration method. Moreover, pHpzc (the point of zero charge) was determined. It was shown that cones are a good, cheap precursor from which biocarbons with a developed porous structure, characterized by good adsorption properties, can be obtained. All the obtained adsorbents are characterized mainly by a microporous structure. Moreover, they contain both acidic and basic surface functional groups (acidic ones prevail over basic ones). The tested activated biocarbons have large specific surface area values ranging from 578 to 1182 m2 g-1. The efficacy of selected materials in the adsorption of an essential contaminant of increasing concern, tetracycline (TC), was investigated. The experimental data were described using the Langmuir and Freundlich adsorption isotherm models. The maximum adsorption capacity of the tested biocarbons ranges from 200 to 392 mg g-1. Thermodynamic studies proved that adsorption is a spontaneous and endothermic process. In summary, economical and environmentally friendly adsorbents were obtained.

Comparative analysis of Escherichia coli Nissle 1917 ghosts quality: a study of two chemical methods.

The gram-negative bacterium Escherichia coli Nissle 1917 (EcN) has long been recognized for its therapeutic potential in treating various intestinal diseases. Bacterial ghosts (BGs) are empty shells of non-living bacterial cells that demonstrate enormous potential for medicinal applications. Genetic and chemical techniques can create these BGs. In the current study, we produced Escherichia coli Nissle 1917 ghosts (EcNGs) for the first time using benzoic acid (BA) and sodium hydroxide (SH). BA is a feeble acidic chemical that enhances gram-negative bacteria's external membrane permeability, reduces energy production, and decreases internal pH. SH has shown success in producing BGs from some gram-negative and gram-positive organisms. This research aims to produce EcNGs using the minimum inhibitory concentration (MIC) of SH and BA, specifically 3.125 mg/mL. We assessed the bacterial quality of the BGs produced using quantitative PCR (qPCR) and Bradford protein assays. Field emission scanning electron microscopy (FE-SEM) showed the three-dimensional structure of EcNGs. The study confirmed the presence of tunnel-like pores on the outer surface, indicating the preservation of cell membrane integrity. Importantly, this investigation introduces BA as a novel chemical inducer of EcNGs, suggesting its potential alongside SH for efficient EcNG formation.

Cellobionate production from sodium hydroxide pretreated wheat straw by engineered Neurospora crassa HL10.

This study investigated cellobionate production from a lignocellulosic substrate using Neurospora crassa HL10. Utilizing NaOH-pretreated wheat straw as the substrate obviated the need for an exogenous redox mediator addition, as lignin contained in the pretreated wheat served as a natural mediator. The low laccase production by N. crassa HL10 on pretreated wheat straw caused slow cellobionate production, and exogenous laccase addition accelerated the process. Cycloheximide induced substantial laccase production in N. crassa HL10, enabling the strain to yield approximately 57 mM cellobionate from pretreated wheat straw (equivalent to 20 g/L cellulose), shortening the conversion time from 8 to 6 days. About 92% of the cellulose contained in the pretreated wheat straw is converted to cellobionate. In contrast to existing methods requiring pure cellobiose or cellulase enzymes, this process efficiently converts a low-cost feedstock into cellobionate at a high yield without enzyme or redox mediator supplementation.

Deciphering different effects of ZVI and NaOH on metabolic characteristics in the process of methanogenesis recovery from VFA suppression.

Dosing zero valent iron (ZVI) or sodium hydroxide (NaOH) is the common method of addressing acidification in anaerobic digestion (AD) systems; however, few studies have discussed and compared their effects on microbial metabolism. In the present study, microbial syntrophy and metabolic pathways under ZVI and NaOH regulation are comparatively analyzed through microbial network analysis and metagenomic/metaproteomic analyses. CH4 yield in the ZVI reactor was 414 mL/gVS, an increase of 23% when compared with that in the reactor with NaOH dosing (336 mL/gVS). The methanogenesis recovery period in the ZVI reactor (37 days) was shorter than that in the NaOH reactor (48 days). Co-occurrence networks indicated that ZVI promoted Methanoculleus and Methanosarcina to establish a complex syntrophic association with SAO bacteria (Syntrophaceticus and Aminobacterium) and syntrophic acetogens (Syntrophomonas), strengthening SAO-hydrogenotrophic methanogenesis (HM) and acetoclastic methanogenesis (AM) pathways simultaneously. Metagenomic analysis showed that the relative abundance of mcrA and fwdB in the ZVI reactor was higher 27% than that in the NaOH reactor. Furthermore, through metaproteomics analysis, much more enzymes related to glucose degradation, bioconversion of butyric acid and pyruvate, conversion of formate and acetate to CO2, and production of CH4 from acetate and CO2 were significantly upregulated under ZVI regulation than under NaOH regulation (fold change relative to control [FC] > 1.5, p < 0.05). The results of the present study enhance our understanding of methanogenic mechanisms under the regulation of ZVI, providing a theoretical basis for its practical application in AD systems experiencing VFA suppression.

A New HPLC-UV Method Using Hydrolyzation with Sodium Hydroxide for Quantitation of Trans-p-Hydroxycinnamic Acid and Total Trans-p-Hydroxycinnamic Acid Esters in the Leaves of Ligustrum robustum.

Trans-p-hydroxycinnamic acid and its esters in the leaves of Ligustrum robustum might be a new resource to prevent diabetes and its complications. In the present study, a new HPLC-UV method using hydrolyzation with sodium hydroxide for quantitation of trans-p-hydroxycinnamic acid and total trans-p-hydroxycinnamic acid esters in the leaves of L. robustum was developed, since it was difficult and troublesome to analyze no less than 34 trans-p-hydroxycinnamic acid esters by usual HPLC. The extract of L. robustum was hydrolyzed with sodium hydroxide at 80 °C for 2 h, and then, hydrochloride was added. HPLC analysis was performed in reverse phase mode using a C-18 column, eluting with methanol-0.1% acetic acid aqueous solution (40:60, v/v) in isocratic mode at a flow rate of 1.0 mL·min-1 and detecting at 310 nm. The linear range for trans-p-hydroxycinnamic acid was 11.0-352.0 µg·mL-1 (r2 = 1.000). The limit of detection and limit of quantification were 2.00 and 6.07 µg·mL-1, respectively. The relative standard deviations of intra-day and inter-day variabilities for trans-p-hydroxycinnamic acid were less than 2%. The percentage recovery of trans-p-hydroxycinnamic acid was 103.3% ± 1.1%. It is the first HPLC method using hydrolyzation for quantification of many carboxylic esters. Finally, the method was used successfully to determine trans-p-hydroxycinnamic acid and total trans-p-hydroxycinnamic acid esters in various extracts of the leaves of L. robustum. The 60-70% ethanol extracts of L. robustum showed the highest contents of free trans-p-hydroxycinnamic acid (3.96-3.99 mg·g-1), and the 50-80% ethanol extracts of L. robustum displayed the highest contents of total trans-p-hydroxycinnamic acid esters (202.6-210.6 mg·g-1). The method can be applied also to the quality control of the products of L. robustum.

Optimization of Alkali Treatment for Production of Fermentable Sugars and Phenolic Compounds from Potato Peel Waste Using Topographical Characterization and FTIR Spectroscopy.

Potato peel waste (PPW) was utilized as a bio-template for the production of valuable compounds such as reducing sugars (RS), total sugar (TS) and total phenolic compounds (TPC). Two methods of alkali treatments, i.e., chemical (NaOH) and thermochemical (NaOH assisted with autoclaving) processes, were employed for the deconstruction of PPW. Response surface methodology (RSM) was used to study the effects of alkali concentration (0.6-1.0 w/v), substrate concentration (5-15 g) and time (4-8 h) on the extraction of RS, TS and TP from PPW. The application of alkali plus steam treatment in Box-Behnken design (BBD) with three levels yielded the optimum releases of RS, TS and TP as 7.163, 28.971 and 4.064 mg/mL, respectively, corresponding to 10% substrate loading, in 0.6% NaOH for 8 h. However, the alkali treatment reported optimum extractions of RS, TS and TP as 4.061, 17.432 and 2.993 mg/mL, respectively. The thermochemical pretreatment was proven a beneficial process as it led to higher productions of TP. FTIR and SEM were used to analyze the deterioration levels of the substrate. The present work was used to explore the sustainable management of PPW, which is a highly neglected substrate bioresource but is excessively dumped in open environment, raising environmental concerns. The cost-effective methods for the breakdown of PPW starch into fermentable sugars might be utilized to extract valuable compounds.

[Improvement of Nitrite Analysis Method in Food Products].

The conventional analysis method has problems with extraction efficiency, operability, and reproducibility. In this study, we attempted to solve these problems and improve the analytical method to obtain sufficient extraction efficiency and good operability and accuracy. The conventional method was able to get sufficient extraction in dried meat products, where the extraction efficiency of the conventional method was low, by increasing the concentration of sodium hydroxide solution at the time of homogenization. Suction filtration after adding the defoaming agent was added allowed for accurate volume adjustment. The turbidity of the extract caused by insufficient addition of zinc acetate solution was removed by increasing the amount of zinc acetate solution that was added. Turbidity caused by starch was removed by adding pancreatin. The RSD of the quantitative values was improved by adding sodium hydroxide solution and 80-90℃ water and immediately homogenizing. Furthermore, by changing the dilution factor of the extract solution in the colorimetric method, the inhibition of coloration by reducing substances was suppressed, and more accurate quantitative values could be obtained than with the conventional method. The recovery rate was 78.5-105% (RSD 0.7-5.8%), which was a good result. This method was considered to be a useful analytical method that can contribute to improving the inspection accuracy of nitrite ion analysis.

Experimental Study on the Mechanical Properties and Microstructure of Metakaolin-Based Geopolymer Modified Clay.

Clay is found in some countries all over the world. It usually has low compressive strength and cannot be used as a bearing material for subgrade soil. In this paper, the influence of basicity on a metakaolin-based polymer binder to improve clay was studied. The effects of the molar concentration of the alkali activator, different concentration of the metakaolin-based geopolymer and curing time on unconfined compressive strength were studied. The alkali activator-to-ash ratio was maintained at 0.7. The percentage of metakaolin added to the soil relative to metakaolin and soil mixture was 6%, 8%, 10% and 12%. The sodium hydroxide concentrations are 2M, 4M, 6M and 8M. Unconfined compressive strength (UCS) was tested on days 3, 7, 14 and 28, respectively. Compared with original clay, the results show that the unconfined compressive strength increases with the increase in metakaolin content and molar concentration of NaOH. The maximum compressive strength of the sample with NaOH concentration of 8M and percentage of 12% was 4109 kN on the 28th day, which is about 112% higher than that of the original clay. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) results showed that the cementing compound covered the clay particles due to the reaction of the geopolymer with the clay, resulting in the formation of adhesive particles. The main purpose of this study is to verify the effectiveness and stability of metakaolin-based geopolymer binder polymerization under normal temperature and a strong alkali environment. The results can provide parameters for the application and promotion of metakaolin-based geopolymers in soil improvement engineering.

Surgical management of esophageal stenosis due to ingestion of corrosive substances.

BACKGROUND: Corrosive ingestion is a significant challenge for healthcare systems. Limited data are available regarding the best treatments, and there remains a lack of consensus about the optimal surgical approach and its outcomes. This study aims to review the current literature and show a single institution's experience regarding the surgical treatment of esophageal stenosis due to corrosive substance ingestion. METHODS: A retrospective review that accounted for demographics, psychiatric profiles, surgical procedures, and outcomes was performed. A systematic review of the literature was performed using PubMed. RESULTS: In total, 27 surgical procedures for esophageal stenosis due to corrosive substance ingestion were performed from 2010 to 2019. Depression and drug abuse were diagnosed in 30% and 22% of the included patients, respectively. Esophagectomies and esophageal bypasses were performed in 13 and 14 patients, respectively. No 30-day mortality was recorded. CONCLUSION: Surgical intervention either by esophagectomy or esophageal bypass results in durable relief from dysphagia. However, successful clinical outcomes depend on a high-quality multidisciplinary network of esophageal and thoracic surgeons, intensivists, psychologists, psychiatrists, and nutritional teams.

Comparison of Pollen Grain Treatments Without Mechanical Fracturation Prior to Protein Quantification.

Protein and amino acids in pollen are important nutritional components for larval development in several insect species, especially in Apoidea. The Bradford assay is a widely used method to measure relative protein content of pollen, which can shed light on pollen quality and consequences to fitness. Prior to using the Bradford assay, protein must be released from pollen grains, often using a mixture of chemical and mechanical fracturation methods. In this study, we tested the efficacy of protein extraction without using mechanical fracturation. We used pollen collected by the solitary bee Osmia lignaria Say to compare two known buffers associated with pollen protein analysis: phosphate-buffered saline and sodium hydroxide, and deionized water, and with different pollen weights from which we quantified protein using the Bradford assay. While all buffers and deionized water were useful in releasing protein from pollen grains collected by O. lignaria, the use of sodium hydroxide resulted in significantly higher protein quantification across all pollen weights. This methodological study can inform future studies of pollen nutrition in pollen-foraging species.

Comparison of Chemical Matricectomy with Trichloroacetic Acid, Phenol, or Sodium Hydroxide for Ingrown Toenails: A Systematic Review and Network Meta-Analysis.

is missing (Short communication).

Statistical modeling of phosphorus solubilization from chemical sludge and evaluation of optimal sodium hydroxide dose.

Phosphorus (P) recovery from sludge has drawn widespread attention across the world to minimize the P load to the watershed, a concern for eutrophication, and to meet the stringent effluent discharge regulations in some countries. Waste activated sludge (WAS) and dewatered sludge (DS) were treated with a wide range of NaOH doses (0-0.75 g g-1 TS). The WAS sludge was diluted to 4.5%-2.25% of TS before the treatment to make comparable amount of TS as of DS (2.25%-1.5%). The kinetic study illustrated that P solubilization reached equilibrium within the first 20 min of treatment duration. Significant positive correlation was found between solution pH and P solubilization, whereas effect of TS was mostly insignificant. The experimental data was well fitted to the exponential models and exhibited maximum P solubilization of about 67% and 56% from the DS and WAS at NaOH doses of 0.71 and 0.27 g g-1 TS, respectively. The optimal NaOH application dose of 0.36 g g-1 TS for DS and 0.20 g g-1 TS for WAS were obtained with 64% and 48% of P solubilization, respectively. The modeling approach and the optimal dose of NaOH illustrated in this study could be utilized for other types of sludges having similar P to TS ratio and P solubilization mechanisms could be further extended to other type of P recovery techniques.

An eco-friendly HPLC-UV method for the determination of risedronate in its bulk and tablet dosage form with application to content uniformity, dissolution and stability testing.

Risedronate is a nitrogen-containing bisphosphonate for the treatment and prevention of postmenopausal osteoporosis. The current work aims to develop a novel green HPLC-UV method for the rapid analysis of risedronate sodium in bulk and tablet formulation. The analyzed samples were separated on Waters Atlantis dC18 (150 mm × 3.9 mm; 5 µm) column using a green mobile phase consisting of potassium phosphate buffer pH 2.9 and potassium edetate buffer pH 9.5 in a ratio of 1:2, the final pH was adjusted to 6.8 with phosphoric acid, the mobile phase was pumped at a rate of 1.0 mL/min, with column temperature set at 30 °C, eluted samples were detected at 263 nm and the chromatographic run time was 3.0 min. The method was found to be linear over the concentration range of 14-140 µg/mL with a correlation coefficient (r2) of 0.9994. Accuracy and precision were evaluated from three QC samples (LQC, MQC and HQC) together with the five calibrators where the percentage accuracy was found to be 101.84%. Processed quality control samples of risedronate sodium were tested for stability at different conditions, short term, long term and freeze- thaw stability. The current method was further extended to study the content uniformity of Actonel® tablets following United States Pharmacopoeia (USP) guidelines. The proposed method was fully validated as per ICH guidelines.

The potential of Atorvastatin for chronic lung diseases therapy.

Atorvastatin (ATO) is of the statin class and is used as an orally administered lipid-lowering drug. ATO is a reversible synthetic competitive inhibitor of 3-hydroxy-3-methyl-glutaryl-CoA (HMG-CoA) reductase thus leading to a reduction in cholesterol synthesis. It has recently been demonstrated that ATO has different pharmacological actions, which are unrelated to its lipid-lowering effects and has the ability to treat chronic airway diseases. This paper reviews the potential of ATO as an anti-inflammatory, antioxidant, and anti-proliferative agent after oral or inhaled administration. This paper discusses the advantages and disadvantages of using ATO under conditions associated with those found in the airways. This treatment could potentially be used to support the formulating of ATO as an inhaler for the treatment of chronic respiratory diseases.

Corrosive ingestion managements in children.

Corrosive (caustic) material ingestion remains a major health issue, particularly in developing countries. The management strategy after corrosive ingestion should be planned according to the signs and symptoms. The management of corrosive ingestion based on endoscopic grading, nothing by mouth, and barium studies should be abandoned. With the new management protocol, esophageal stricture can be predicted with high accuracy using the simple new prognostic DROOL score (≤ 4) rather than endoscopic grading, reduced by immediate oral feeding as soon as the patient can swallow saliva instead of nothing by mouth, diagnosed earlier (10-14 days) by fluoro-endoscopic balloon-assisted esophageal examination for patients with persistent dysphagia instead of relying on a barium study (≥ 21 days), and adequately treated by initiating balloon dilation earlier during the same anesthesia procedure. Fluoroscopically guided balloon dilatation with large balloons (18-20 mm) seems to be safe, with a low frequency of complications and a high success rate. If dilatation fails after a few months, esophagectomy and replacement surgery using the stomach should be considered. The increased risk of developing esophageal carcinoma after ingestion of corrosive substances should be kept in mind.

Detection of latent infections caused by Colletotrichum sp. in olive fruit.

AIMS: To set up a practical method to detect latent infections of Colletotrichum sp., the causal agent of olive anthracnose, on olives before the onset of disease symptoms. METHODS AND RESULTS: Freezing, sodium hydroxide (NaOH), ethanol and ethylene treatments were evaluated to detect latent infections on inoculated and naturally infected olive fruit by Colletotrichum sp. as non-hazardous alternatives to paraquat. Treatments were conducted using fruit of cultivars Arbequina and Hojiblanca. The disease incidence and T50 were calculated. Dipping in NaOH 0·05% solution and the paraquat method were the most effective treatments on both inoculated and naturally infected fruit, although the value of T50 was lower for the NaOH method than for the paraquat method in one of the experiments. Subsequently, the dipping time in NaOH 0·05% was evaluated. Longer dipping times in NaOH 0·05% were better than shorter ones in cultivar Arbequina, with 72 h being the most effective in cultivar Hojiblanca. CONCLUSIONS: NaOH solution is a practical method to detect latent infections of Colletotrichum sp. on immature olive fruit. SIGNIFICANCE AND IMPACT OF THE STUDY: This study is relevant because we set up a viable, non-hazardous alternative to paraquat to detect latent infections of Colletotrichum sp. using NaOH. The use of NaOH is a simple and eco-friendly tool that allows the determination of the level of latent infections by Colletotrichum in olives. Therefore, our method will be useful in decision-making processes for disease management before the appearance of the first visible symptoms.

Surface treated Pteris vittata L. pinnae powder used as an efficient biosorbent of Pb(II), Cd(II), and Cr(VI) from aqueous solution.

Biosorption is a surface-dependent phenomenon. Surface modifications by chemical treatment methods could either improve or reduce the biosorption capacity of potential biosorbents. In the present work, pristine Pteris vittata L. pinnae (PPV) powder was treated separately with sodium hydroxide (NaOH), calcium chloride (CaCl2), and nitric acid (HNO3). The pristine and treated biosorbents were used to assess the biosorption of Pb(II), Cd(II), and Cr(VI) as a function of pH. Kinetics and adsorption isotherms were studied. Attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy and scanning electron microscope combined with energy dispersive x-ray (SEM-EDX) spectroscopic techniques were used to characterize the biosorbents before and after chemical treatments. The possible functional groups contributing to the metal sorption were identified. Results revealed favorable biosorption of Pb(II), Cd(II), and Cr(VI) described by pseudo-second order kinetics. NaOH-treated P. vittata (NPV) showed higher biosorption capacity for Pb(II) and Cd(II) compared to that of PPV. ATR-FTIR studies indicated that -OH, -COOH, and -NH2 groups were mainly involved in Cr(VI) and -OH in Pb(II) and Cd(II) biosorption. The enhanced efficiency of NPV and CaCl2 treated P. vittata (CPV) in the uptake of Pb(II) and Cd(II) compared to PPV can be associated with their altered physicochemical characters.

Evaluation of extraction methods for the identification of proteins from date palm (Phoenix dactylifera L.) seed and flesh.

Date fruits are well known to be very nutritious. Nevertheless, the protein contents of the fruit, particularly the seed and flesh, are still understudied, largely due to their difficult physical characteristics. This study was conducted to compare three different protein extraction methods which were the trichloroacetic acid (TCA)-acetone (TCA-A), phenol (Phe), and TCA-acetone-phenol (TCA-A-Phe), and to perform proteomic analysis on date palm seed and flesh. Phe extraction method showed the highest protein yields for both seed (8.26 mg/g) and flesh (1.57 mg/g). Through sodium dodecyl sulfate-polyacrylamide gel electrophoresis, Phe, and TCA-A-Phe extraction methods were shown to be efficient in removing interfering compounds and gave well-resolved bands over a wide range of molecular weights. Following liquid chromatography-tandem mass spectrometry analysis, about 50-64% of extracted proteins were identified with known functions including those involved in glycolysis, Krebs cycle, defense, and storage. Phe protein extraction method was proven to be the optimal method for date flesh and seed.

Characterization of Chemically-Induced Bacterial Ghosts (BGs) Using Sodium Hydroxide-Induced Vibrio parahaemolyticus Ghosts (VPGs).

Acellular bacterial ghosts (BGs) are empty non-living bacterial cell envelopes, commonly generated by controlled expression of the cloned lysis gene E of bacteriophage PhiX174. In this study, Vibrio parahaemolyticus ghosts (VPGs) were generated by chemically-induced lysis and the method is based on minimum inhibitory concentration (MIC) of sodium hydroxide (NaOH), acetic acid, boric acid, citric acid, maleic acid, hydrochloric acid, and sulfuric acid. The MIC values of the respective chemicals were 3.125, 6.25, <50.0, 25.0, 6.25, 1.56, and 0.781 mg/mL. Except for boric acid, the lysis efficiency reached more than 99.99% at 5 min after treatment of all chemicals. Among those chemicals, NaOH-induced VPGs appeared completely DNA-free, which was confirmed by quantitative real-time PCR. Besides, lipopolysaccharides (LPS) extracted from the NaOH-induced VPGs showed no distinctive band on SDS-PAGE gel after silver staining. On the other hand, LPS extracted from wild-type bacterial cells, as well as the organic acids-induced VPGs showed triple major bands and LPS extracted from the inorganic acids-induced VPGs showed double bands. It suggests that some surface structures in LPS of the NaOH-induced VPGs may be lost, weakened, or modified by the MIC of NaOH. Nevertheless, Limulus amoebocyte lysate assay revealed that there is no significant difference in endotoxic activity between the NaOH-induced VPGs and wild-type bacterial cells. Macrophages exposed to the NaOH-induced VPGs at 0.5 × 106 CFU/mL showed cell viability of 97.9%, however, the MIC of NaOH did not reduce the cytotoxic effect of wild-type bacterial cells. Like Escherichia coli LPS, the NaOH-induced VPGs are an excellent activator of pro-inflammatory cytokines (IL-1ß and iNOS), anti-inflammatory cytokine (IL-10), and dual activities (IL-6) in the stimulated macrophage cells. On the other hand, the induction of TNF-α mRNA was remarkable in the macrophages exposed with wild-type cells. Scanning electron microscopy showed the formation of trans-membrane lysis tunnel structures in the NaOH-induced VPGs. SDS-PAGE and agarose gel electrophoresis also confirmed that cytoplasmic proteins and genomic DNA released from the VPGs to culture medium through the lysis tunnel structures. Taken together, all these data indicate that the NaOH-induced VPGs show the potency of a safe, economical, and effective inactivated bacterial vaccine candidate.

Autopsy results of a case of ingestion of sodium hydroxide solution.

Sodium hydroxide is a strongly corrosive alkali. We describe herein a case of suicide by ingestion of sodium hydroxide. A man in his 80s was found dead with a mug and a bottle of caustic soda. Macroscopically, liquefaction and/or disappearance of esophagus, trachea and lung tissue and a grayish discoloration of the mucosa of the stomach were seen along with blackish brown coloration of the skin, mouth, and oral cavity. The contents of the gastrointestinal tract showed a pH level of 7-8 on pH indicator strips. Histopathologically, liquefactive necrosis of remnant lung tissue and the stomach were seen. As biological reactions such as vasodilatation and inflammation were not detected in these organs, only a short number of hours must have passed between ingestion and death. This human case provides valuable information concerning the direct irritation induced by systemic exposure to corrosive substances.