Harnessing active biofilm for microbial corrosion protection of carbon steel against Geobacter sulfurreducens

Microbiologically influenced corrosion (MIC) caused by corrosive microorganisms poses significant economic losses and safety hazards. Conventional corrosion prevention methods have limitations, so it is necessary to develop the eco-friendly and long-term effective strategies to mitigate MIC. This study investigated the inhibition of Vibrio sp. EF187016 biofilm on Geobacter sulfurreducens on carbon steel. Vibrio sp. EF187016 biofilm reduced the corrosion current density and impeded pitting corrosion. A thick and uniform Vibrio sp. EF187016 biofilm formed on the coupon surfaces, acting as a protective layer against corrosive ions and electron acquisition by G. sulfurreducens. The pre-grown mature Vibrio sp. EF187016 biofilms, provided enhanced protection against G. sulfurreducens corrosion. Additionally, the extracellular polymeric substances from Vibrio sp. EF187016 was confirmed to act as a green corrosion inhibitor to mitigate microbial corrosion. This study highlights the potential of active biofilms for eco-friendly corrosion protection, offering a novel perspective on material preservation against microbial corrosion.

Simulated aging of draught beer line tubing increases biofilm contamination

Craft brewing is continually gaining popularity in the United States. Craft brewers are committed to producing a wide variety of products and have a vested interest in product quality. Therefore, these brewers have the expectation that the beer poured at the tap will match the quality product that left the brewery. The presence of biofilm in draught lines is hypothesized as a contributing factor when this expectation is not achieved. Clean in place strategies based on the Sinner's Circle of Cleaning are used to remediate organic and inorganic accumulation in beer draught lines, including controlling biofilm accumulation. A study was conducted to determine if repeated exposure to chemical cleaning of vinyl beer tubing impacted biofilm growth, kill/removal, and subsequent regrowth of a mixed species biofilm. The tubing was conditioned to simulate one, two, and five years of use. The data collected demonstrates a clear trend between simulated age of the tubing and biofilm accumulation on the surface. Bacterial log densities ranged from 5.6 Log10(CFU/cm2) for the new tubing to 6.6 Log10(CFU/cm2) for tubing aged to simulate five years of use. The counts for the yeast were similar. Caustic cleaning of the tubing, regardless of starting biofilm coverage, left less than 2.75 Log10(CFU/cm2) viable bacteria and yeast cells remaining on the tubing surface. This demonstrated the effectiveness of the caustic at controlling biofilm accumulation in the simulated beer draught line. The biofilm that accumulated in the five-year aged tubing was able to recover more quickly, reaching 3.6 Log10(CFU/cm2) within 24 h indicating the treatment did not fully eradicate the biofilm, suggesting that the strong chemistry used in this study would cease to be as effective over time.

Antibiofilm activity of electrochemically activated water (ECAW) in the control of Salmonella Heidelberg biofilms on industrial surfaces

Owing to its antimicrobial activity, electrochemically activated water (ECAW) is a potential alternative to chemical disinfectants for eliminating foodborne pathogens, including Salmonella Heidelberg, from food processing facilities. However, their antibiofilm activity remains unclear. This study aimed to evaluate the antibiofilm activity of ECAW against S. Heidelberg biofilms formed on stainless steel and polyethylene and to determine its corrosive capacity. ECAW (200 ppm) and a broad-spectrum disinfectant (0.2%) were tested for their antibiofilm activity against S. Heidelberg at 25 °C and 37 °C after 10 and 20 min of contact with stainless steel and polyethylene. Potentiostatic polarization tests were performed to compare the corrosive capacity of both compounds. Both compounds were effective in removing S. Heidelberg biofilms. Bacterial counts were significantly lower with ECAW than with disinfectant in polyethylene, regardless the time of contact. The time of contact and the surface significantly influenced the bacterial counts of S. Heidelberg. Temperature was not an important factor affecting the antibiofilm activities of the compounds. ECAW was less corrosive than the disinfectant. ECAW demonstrated a similar or even superior effect in the control of S. Heidelberg biofilms, when compared to disinfectants, reducing bacterial counts by up to 5 log10 CFU cm-2. The corrosion of stainless steel with ECAW was similar to that of commercial disinfectants. This technology is a possible alternative for controlling S. Heidelberg in the food production chain.

Synthesis of silver nanoparticles from Indian red yeast rice and its inhibition of biofilm in copper metal in cooling water environment

The development of environmentally acceptable benign techniques using purely natural methods is a cost-effective procedure with long-term benefits in all areas. With this consideration, myco synthesized silver nano particles (AgNPs) were studied and it acted as an impending corrosion inhibitor in the environment. Initially, AgNPs were evaluated by physical and surface characterizations and this evidence demonstrated that RYRE's water-soluble molecules played an essential role in the synthesis of AgNPs in nano spherical size. The myco synthesized of AgNPs has showed an antibacterial activity against corrosive bacteria in cooling water system (CWS). Hence, the AgNPs were used in biocorrosion studies as an anticorrosive agent along with AgNO₃ and RYRE was also checked. For this experiment, the copper (Cu) metal (CW024) which is commonly used was selected, the result of corrosion rate was decreased, and inhibition efficiency (82%) was higher in the presence of AgNPs in system IV. Even though, AgNO₃ and RYRE had contributed significant inhibition efficiency on Cu at 47% and 61%, respectively. According to XRD, the reaction of AgNPs on Cu metal resulted in the formation of a protective coating of Fe₂O₃ against corrosion. EIS data also indicated that it could reduce the corrosion on the Cu metal surface. All of these findings point out the possibility that the myco-synthesized AgNPs were an effective copper metal corrosion inhibitor. As a result, we encourage the development of myco-synthesized AgNPs, which could be useful in the industrial settings.

Inhibition performances of graphene oxide/silver nanostructure for the microbial corrosion: molecular dynamic simulation study

Steel is one of the mainly used materials in the oil and gas industry. However, it is susceptible to the marine corrosion, which 20% of the total marine corrosion is caused by microbiologically influenced corrosion (MIC). The economic and environmental impacts of corrosion are significant, and it is crucial to fight against corrosion in a proper sustainability context and environmental-friendly methods. In this study, the graphene oxide/silver nanostructure (GO-Ag) inhibitory effect on the corrosion of steel in the presence of sulfate reducing bacteria (SRB) was investigated, via weight loss (WL) and Tafel polarization measurements. Moreover, molecular dynamic (MD) simulations were performed to obtain a deep understanding of the corrosion inhibition effect of GO-Ag. GO-Ag showed a significant antibacterial effect at 80 ppm. Moreover, WL and Tafel polarization measurements illustrated a great inhibition efficiency, which reached up to 84% reduction of WL and 98% reduction of corrosion current density (I_corr) after 7 days of incubation with GO-Ag. Based on MD simulations, bonding energy reached to the larger value in the presence of GO-Ag, which indicated the ability of graphene oxide nanosheets to be adsorbed on the steel surface and prevent the access of corrosive agents to the steel surface. The radial distribution function (RDF) results implied distance between corrosive agent (water and SRB) and steel surface (Fe atoms), which indicated protection of the steel surface due to the effective adsorption of GO nanosheets through the active sites of the steel surface. The mean square displacement (MSD) result showed smaller displacement of the corrosive particles on the surface of steel, resulting that the GO-Ag molecules bonded with Fe molecules on the surface of steel.

Investigating the effects of environment, corrosion degree, and distribution of corrosive microbial communities on service-life of refined oil pipelines

Although the potential corrosive microbial communities of the refined oil pipelines can cause pipeline failure which directly threatens on soil and water environment, few studies have been published in this field. Therefore, the long-distance on-site internal corrosion detection and high-throughput sequencing techniques were employed in this study to investigate the distribution shifts of the corrosive microbial communities on the inner wall of a refined oil pipeline and its impact on the internal corrosion. The microorganisms colonizing on the inner wall of the pipeline showed significant distribution differences between the axial direction of the relative elevation and radial direction of the cross-section. On the inner wall, the high diversity and the abundance of the corrosive microbial communities induced serious microbiologically influenced corrosion (MIC), while the chemical corrosion and the synergy of the corrosive microbial communities accelerated the internal corrosion of the refined oil pipeline. A corrosion zone model has been proposed, which divides the pipeline cross-section into the sediment, the water-oil interface, the gas-oil interface, and the oil fully immersed zones. Therefore, the relationships between the environment, corrosion degree, and distribution characteristics of the corrosive microbial communities in the pipeline were analyzed. This research exhibited the importance of the distribution characteristics of the corrosive microorganisms on the inner wall of the refined oil pipelines. Its internal corrosion behavior was accurately explored, while providing a basis for controlling the corrosive microbial communities.

Microbial Corrosion in Orthodontics

Even with the exponential popularity of the contemporary clear aligners, the main stream of orthodontic practice still remains to be metal braces especially in adolescent age-group.¹ Along with the advantages of metal braces such as lower cost, reduced friction, etc., there goes the disadvantages such as corrosion possibility, reduced esthetics, etc. Corrosion of orthodontic appliances is a widely researched topic.^2-5 It is surprising to learn that microbially induced corrosion (MIC) has not been addressed in orthodontic literature till date. Microbial corrosion is an interesting arena which requires knowledge of both corrosion science and microbiology. The microorganisms capable of corrosion include various bacteria, fungi, and algae. The most common among them which has been widely indicated in MIC are the bacteria belonging to the sulfur cycle especially the sulfate-reducing bacteria (SRB). The connecting knot with orthodontics is the reported prevalence of these SRB in the oral cavity. SRB is prevalent in healthy individuals,^6,7 patients associated with periodontitis^6-11 and patients with gastrointestinal issues.^12-14 The prevalence of SRB in the oral cavity has a greater clinical implication since the SRB have been proven to cause corrosion of stainless steel.^15-24 There is literature attributing SRB as a potential cause in periodontal diseases^7-11 as well as gastrointestinal diseases such as ulcerative colitis, inflammatory bowel diseases, and Crohn's disease.¹² With its presence in the healthy oral environment already reported in the previous studies,^6,7,25,26 it further emphasizes the absolute need to be researching on its corrosion possibility in the intra oral environment. The genus generally found intraorally was Desulfovibrio and Desulfobacter¹⁰ which is commonly regarded as the most "opportunistic" and ubiquitous group of sulfate reducers.^6,7 There is an interesting literature on the inhibition of Desulfovibrio spp. by human saliva, the reason being quoted as salivary nitrate and nitrite.¹⁴ The mechanism behind the antimicrobial action of nitrate and nitrite is that they increase the oxidative stress on the bacteria.²⁷ However, concentrations of salivary nitrate vary depending on the food intake, endogenous production, and salivary flow rate.^28,29 Despite there exist natural inhibitors, the prevalence in oral cavity is high, 22% in healthy and 86% in patients associated with periodontitis.⁷ There is a predilection for the bacteria to grow when favorable conditions exist. Biofilms is one such favorable medium for the growth of SRB. Paster et al.²⁶ identified SRB in biofilms of patients associated with refractory periodontitis, periodontitis, acute necrotizing ulcerative gingivitis (ANUG), and also in healthy subjects. Biofilm is a surface film composed of organic and inorganic saliva components that are colonized with microorganisms in extracellular polymeric substances adsorbed on all surfaces in the oral cavity.³⁰ The oral biofilm formation is a complex process involving interspecies aggregation, which is surrounded by a cohesive matrix, forms a complex structure which in turn facilitates anaerobic growth. It is the intrinsic nature of oral biofilms which make the survival of facultative anaerobes such as SRB in the oral cavity possible. Literatures^31-35 report that there are increased biofilm formations in orthodontic patients due to increased retentive areas caused by the brackets, ligatures, wires, mini implants, force components, and archwires. Bacteria in dental plaque function as a metabolically, functionally, and physically integrated community.³⁶ The study by Mystkowska et al.³⁷ mentioned that biofilm per se play a critical role in corrosion process by forming corrosive microcells. With time-dependent association, the microbes in the biofilm, along with saliva acting as an electrolyte and components from food, causes a decreased pH in the areas immediately under the biofilms. The decreased pH along with a change of oxygenation releases metal oxides and hydroxides from the metal surface ultimately leading to the corrosion of metallic structures.^37-41 The initial roughness also acts in a vicious form promoting more biofilm adherence and the process repeats causing more corrosion. With the biofilm itself serving to initiate and propagate corrosion, the increased prevalence of SRB in patients associated with orthodontics treatment all the more increases the possibility of MIC of orthodontic materials.

Possible healing effects of Salvadora persica extract (MISWAK) and laser therapy in a rabbit model of a caustic-induced tongue ulcers: histological, immunohistochemical and biochemical study

Caustic ingestion is a potentially detrimental event that can cause serious devastating damage on contact with tissues. Local exposure is associated with severe pain, swelling and ulceration. Caustics-induced oral ulcers can be painful enough to compromise the patient's quality of life. Treatment of oral ulcers is crucial in clinical practice. Albeit, some ulcers do not respond adequately to the conventional treatment. The current study was conducted to evaluate the potential healing effects of topical Salvadora persica (SP) extract, low-level laser (LLL) and high-level laser (HLL) therapies in a rabbit model of caustic-induced tongue ulcers and explore the underlying mechanisms. Fifty male rabbits with a caustic induced tongue ulcers were included in the study. Rabbits were equally divided into four groups: positive control (ulcer) group, SP, LLL and HLL groups in addition to the negative control (healthy) group. All treatments were given thrice weekly for 14 days. Results showed that acetic acid-induced tongue ulcers caused extensive structural tongue damage secondary to overexpression of apoptotic BAX, pathological angiogenesis indicated by VEGF overexpression, marked collagen fibers deposition as well as upregulation of tissue pro-inflammatory TNF-α and upregulation of tissue anti-inflammatory IL-10. The healing potential of topical SP, LLL and HLL therapy are mostly comparable. In conclusion, acetic acid-induced extensive tongue damage. Topical SP extract, LLL and HLL are equally effective therapies against caustics-induced tongue ulcers. However, we recommend SP extract, owing to its safety, non-invasiveness, availability and low cost.

Purification of native Argonaute complexes from the fission yeast Schizosaccharomyces pombe

Small interfering (si) RNAs, produced by the RNA interference (RNAi)-mediated processing of long double-stranded (ds) RNAs, can inhibit gene expression by post-transcriptional or transcriptional gene silencing mechanisms. At the heart of all small RNA-mediated silencing lies the key RNAi effector protein Argonaute, which once loaded with small RNAs can recognize its target transcript by siRNA-RNA Watson-Crick base pairing interactions. In the fission yeast Schizosaccharomyces pombe, the formation of the epigenetically heritable centromeric heterochromatin requires RNAi proteins including the sole fission yeast Argonaute homolog, Ago1. Two distinct native Ago1 complexes have been purified and studied extensively, both of which are required for siRNA production and heterochromatin formation at the fission yeast centromeres. The purification and analysis of the Argonaute siRNA chaperone (ARC) complex and RNA-induced transcriptional silencing (RITS) complex have provided insight into the mechanism of siRNA-Ago1 loading and the cis recruitment of silencing complexes at fission yeast centromeres, respectively. These discoveries have been instrumental in shaping the current models of RNA-mediated epigenetic silencing in eukaryotes. Below, we describe the protocol used for affinity purification of the native Ago1 complexes from S. pombe.

Detecting cellulase penetration into corn stover cell walls by immuno-electron microscopy

In general, pretreatments are designed to enhance the accessibility of cellulose to enzymes, allowing for more efficient conversion. In this study, we have detected the penetration of major cellulases present in a commercial enzyme preparation (Spezyme CP) into corn stem cell walls following mild-, moderate- and high-severity dilute sulfuric acid pretreatments. The Trichoderma reesei enzymes, Cel7A (CBH I) and Cel7B (EG I), as well as the cell wall matrix components xylan and lignin were visualized within digested corn stover cell walls by immuno transmission electron microscopy (TEM) using enzyme- and polymer-specific antibodies. Low severity dilute-acid pretreatment (20 min at 100 degrees C) enabled <1% of the thickness of secondary cell walls to be penetrated by enzyme, moderate severity pretreatment at (20 min at 120 degrees C) allowed the enzymes to penetrate approximately 20% of the cell wall, and the high severity (20 min pretreatment at 150 degrees C) allowed 100% penetration of even the thickest cell walls. These data allow direct visualization of the dramatic effect dilute-acid pretreatment has on altering the condensed ultrastructure of biomass cell walls. Loosening of plant cell wall structure due to pretreatment and the subsequently improved access by cellulases has been hypothesized by the biomass conversion community for over two decades, and for the first time, this study provides direct visual evidence to verify this hypothesis. Further, the high-resolution enzyme penetration studies presented here provide insight into the mechanisms of cell wall deconstruction by cellulolytic enzymes.

Dissolution of porcine incisor pulps in sodium hypochlorite solutions of varying compositions and concentrations

BACKGROUND

The solubility of dental pulp tissue in sodium hypochlorite has been extensively investigated but results have been inconsistent; due most likely to variations in experimental design, the volume and/or rate of replenishment of the solutions used and the nature of the tissues assessed. Traditionally, the sodium hypochlorite solutions used for endodontic irrigation in Australia have been either Milton or commercial bleach, with Milton being the most common. Recently, a range of Therapeutic Goods Administration (TGA) approved proprietary sodium hypochlorite solutions, which contain surfactant, has become available. Some domestic chlorine bleaches now also contain surfactants. The purpose of this study was to perform new solubility assessments, comparing Milton with new TGA approved products, Hypochlor 1% and Hypochlor 4% forte, and with a domestic bleach containing surfactant (White King).

METHODS

Ten randomly assigned pulp samples of porcine dental pulp of approximately equal dimensions were immersed in the above solutions, as well as representative concentrations of sodium hydroxide. Time to complete dissolution was measured and assessed statistically.

RESULTS

White King 4% showed the shortest dissolution time, closely followed by Hypochlor 4% forte. White King 1% and Hypochlor 1% each took around three times as long to completely dissolve the samples of pulp as their respective 4% concentrations, while Milton took nearly 10 times as long. The sodium hydroxide solutions showed no noticeable dissolution of the pulp samples.

CONCLUSIONS

The composition and content of sodium hypochlorite solutions had a profound effect on the ability of these solutions to dissolve pulp tissue in vitro. Greater concentrations provided more rapid dissolution of tissue. One per cent solutions with added surfactant and which contained higher concentrations of sodium hydroxide were significantly more effective in dissolution of pulp tissue than Milton.

Induction of PDGF-B in TCA-treated epidermal keratinocytes

Trichloroacetic acid (TCA) is one of the most widely used peeling agents, and induces full necrosis of the whole epidermis, followed by reconstitution of the epidermis and the matrix of the papillary dermis. The cytotoxic effects of TCA, such as suppressing proliferation of keratinocytes and fibroblasts and protein synthesis by fibroblasts, have already been reported. However, the entire biological mechanism responsible for TCA peeling has yet to be determined. Hypothetical activation effects of TCA treatment on epidermal cells to induce production of growth factors and cytokines are examined, and are compared with its cytotoxic effects in terms of time course and applied TCA concentrations. After various periods of incubation with TCA, viability of Pam212 murine keratinocytes was investigated with MTT assay and dye exclusion assay, and production of growth factors and cytokines with reverse transcription-polymerase chain reaction (RT-PCR). Changes in platelet-derived growth factor (PDGF)-B mRNA expression and protein production in the human skin specimens after TCA application were then examined by RT-PCR and immunohistochemistry, respectively. Incubation with TCA showed cytotoxicity and induced death of Pam212 cells, depending on the incubation period and the TCA concentration. In addition, expressions of PDGF-B, tumor growth factor (TGF)-alpha, TGF- beta1 and vascular endothelial growth factor, which are the growth factors reportedly secreted from keratinocytes during wound healing, were all detected in Pam212 cells after short-term treatment with TCA. Expressions of inflammatory cytokines such as interleukin (IL)-1 and IL-10 were also induced. In TCA-treated NIH-3T3 fibroblasts, in contrast, observed was upregulation of only keratinocyte growth factor, which is reportedly secreted from fibroblasts, as well as the similar cytotoxic effect. In human skin, PDGF-B mRNA expression became significantly upregulated after TCA application, and then immediately downregulated. Immunoreactive PDGF-B in the cytoplasm of keratinocytes became detectable throughout the epidermis after TCA application, reached maximum after the peak of mRNA expression, and then declined significantly over 24 h when the epidermis became completely necrotic. The TCA-treated epidermis acts as a major source of growth factors, including PDGF-B, before undergoing full necrosis. This effect might contribute to a promotion of re-epithelialization and dermal regeneration without wound contraction and scarring.

Scanning electron microscopy of vascular corrosion casts--standard method for studying microvessels

Scanning electron microscopy (SEM) of vascular corrosion casts (microvascular corrosion casting/SEM method) is a standard method, which allows three-dimensional visualization with good resolution of the normal and abnormal microvessels, including the capillaries of various organs and tissues. SEM of vascular corrosion casts can obtain qualitative as well as quantitative informations important to anatomists, pathologists and clinicians. Considering these, the history, the advantages and the main steps of this technique including general morphological characteristics of vascular casts observed in SEM are reviewed in this paper. Corrosion casts done by the author representing the microvascular organization of the rat liver and kidney observed in SEM are, also, presented.

Preparation of mycobacteria-containing artificial sputum for TB panel testing and microscopy of sputum smears

SETTING

Panel testing, blinded cross rechecking and on-site evaluation are the three methods for external quality assessment (EQA) of acid-fast bacilli (AFB) smear microscopy. Panel testing can provide data on laboratory capabilities prior to implementing a rechecking programme, assess the current status of laboratory performance and detect problems associated with diagnostic performance. Thus far, two methods for preparing panel test slides have been reported: these use real AFB-positive and -negative sputum treated with sodium hydroxide (NaOH) or N-acetyl-L-cysteine (NALC).

OBJECTIVE

To evaluate the above methods and to develop a new method to prepare panel test slides with artificial sputum.

DESIGN

Panel test slides were prepared using the NaOH and NALC methods. New artificial sputum preparation methods were developed and examined using a cultured monocyte cell line, cultured avirulent mycobacteria and methylcellulose or polyacrylamide gel as substrate. Smears prepared by the four methods were compared.

RESULTS

Panel test slides prepared with NaOH and NALC methods are not macroscopically or microscopically similar to real smears. Our new artificial sputum is similar to real sputum in viscosity and macroscopic and microscopic appearance; it is also consistent in panel positivity grades.

CONCLUSION

The artificial sputum described here could contribute to the EQA and training in tuberculosis laboratories or microscopy centres.

Production of Rice Protein by Alkaline Extraction Improves Its Digestibility

Rice seed endosperm has two types of protein bodies (PB). Type I protein body (PB-I) accumulates prolamin and is hard to digest, while type II protein body (PB-II) mainly consists of glutelin, an easily digestible protein. A simple method to process rice protein and improve its digestibility was tested from the viewpoint of its application to food manufacturing. Rice protein prepared by alkaline extraction followed by neutralization sedimentation (AE-RP) was compared with that prepared by starch degradation by alpha-amylase (SD-RP). The crude protein content of AE-RP and SD-RP was 84.7% and 78.2%, respectively. There were no major differences in protein composition among AE-RP, SD-RP and rice flour by SDS-PAGE, except 16 kDa polypeptide. With respect to amino acids, all the groups showed quite similar compositions, although cysteine and methionine were lower in AE-RP. In an in vitro digestion study with pepsin and pancreatin, both the SDS-PAGE analysis of protein pattern and the crude protein content of undigested residue clearly demonstrated that AE-RP has a higher digestibility than SD-RP. To find the cause of the difference in digestibility, the structural property of protein bodies by two production methods was compared using electron microscopy. PB-II of AE-RP was transformed into small, amorphous granules, while that of SD-RP was still kept partial protein body structures. PB-I of AE-RP kept its protein body structure, but produced double layers. From the finding that glutelin-gold was detected by immunochemistry not only in small, amorphous granules but also in PB-I, mainly the cortex layer, in AE-RP, it became clear that PB-I was swollen and fragile as a result of alkali treatment. These results strongly indicate that the improvement in digestibility of AE-RP is a result of the structural change of PB-I and -II caused by alkaline extraction.

Calf response to caustic paste and hot-iron dehorning using sedation with and without local anesthetic

Dairy producers require effective methods of reducing the pain associated with dehorning. Previous work has shown that analgesics can reduce pain associated with hot-iron dehorning, but these interventions may not be practical for some producers. Some producers favor the use of caustic paste (to cause a chemical burn as opposed to thermal burn), but little is known about how to treat pain caused by caustic burns. In 2 experiments, head shaking and head rubbing behaviors were used to evaluate pain following dehorning using caustic paste. In experiment 1, sedated calves were dehorned using a caustic paste, with or without a lidocaine local block. Calves treated with lidocaine showed no evidence of reduced pain response in the hours after the caustic paste was applied. In experiment 2, response to caustic paste dehorning with a sedative only was compared with hot-iron dehorning using a sedative and local anesthetic. In the first 4 h after dehorning, calves dehorned with a hot iron showed more head shaking than calves dehorned with caustic paste. These results indicate that dehorning with caustic paste combined with a sedative results in less pain to calves than dehorning with a hot iron combined with a sedative and a local anesthetic.

Prion diseases and iatrogenic infections II. Decontamination

We have by now methods for the safe decontamination of medical devices. They include (a) NaOH, preferably combined with autoclaving in a simultaneous process at 121-134 C (b) NaOCl, alone at ambient temperature for some delicate instruments or combined with autoclaving (but separately); (c) autoclaving alone at 134 C for 18 minutes (Consensus in most European countries); (d) chemical decontamination using alkaline detergents (pH 11-12), proteases (properase, proteinase K, pronase or others) in combination with SDS for temperature-sensitive instruments, i.e. endoscopes and (e) combination of chemicals with autoclaving for temperature-resistant devices. The way of instruments from the operation room to the department of sterilisation (decontamination) is of considerable importance to avoid dessication and fixation of proteins onto instrument surfaces. For these purpose polypropylene pans willed with 0.1N NaOH or appropriate chemicals are very useful for immersion of devices immediately after being used-and then, after transport, transferred into the autoclave using the same fluid, with some fluid added, if necessary for instruments to be immersed. Temperature-sensitive devices in pans with chemicals must not be autoclaved but treated as proposed by the chemicals producer-at ambient or low temperature. In any case devices must not be cleaned in automated washers if not previously decontaminated. The empty pans must finally be autoclaved at 134 C 18 minutes as well.

Induction of cytokine (interleukin-1alpha and tumor necrosis factor-alpha) and chemokine (CCL20, CCL27, and CXCL8) alarm signals after allergen and irritant exposure

The immune system is called into action by alarm signals generated from injured tissues. We examined the nature of these alarm signals after exposure of skin residential cells to contact allergens (nickel sulfate and potassium dichromate) and a contact irritant [sodium dodecyl sulfate (SDS)]. Nickel sulfate, potassium dichromate, and SDS were applied topically to the stratum corneum of human skin equivalents. A similar concentration-dependent increase in chemokine (CCL20, CCL27, and CXCL8) secretion was observed for all three chemicals. Exposure to nickel sulfate and SDS was investigated in more detail: similar to chemokine secretion, no difference was observed in the time- and concentration-dependent increase in pro-inflammatory cytokine [interleukin-1alpha (IL-1alpha) and tumor necrosis factor-alpha (TNF-alpha)] secretion. Maximal increase in IL-1alpha secretion occurred within 2 h after exposure to both nickel sulfate and SDS and prior to increased chemokine secretion. TNF-alpha secretion was detectable 8 h after chemical exposure. After allergen or irritant exposure, increased CCL20 and CXCL8, but not CCL27, secretion was inhibited by neutralizing human antibodies to either IL-1alpha or TNF-alpha. Our data show that alarm signals consist of primary and secondary signals. IL-1alpha and TNF-alpha are released as primary alarm signals, which trigger the release of secondary chemokine (CCL20 and CXCL8) alarm signals. However, some chemokines, for example, CCL27 can be secreted in an IL-1alpha and TNF-alpha independent manner. Our data suggest that skin residential cells respond to both allergen and irritant exposure by releasing mediators that initiate infiltration of immune responsive cells into the skin.

The fingernails of Mary Sullivan: developing reliable methods for selectively isolating endogenous and exogenous DNA from evidence

The fingernails of Mary Sullivan, the last victim of the Boston Strangler, were examined to determine if any genetic information about the murderer could be obtained. The nails were extremely friable necessitating the development of new techniques for isolating and purifying DNA. DNA yields from nails were optimized by using a NaOH-based preparation technique, which was simple, efficient, and minimized handling. Methods for selectively and thoroughly removing exogenous material on nails were also developed through use of a species-specific PCR assay, wherein mitochondrial DNA from the nail could easily be differentiated from DNA of contaminating cells.

Scientific analysis of phenol nail surgery

Chemical matrixectomy using phenol is one of the most common surgical procedures for the permanent removal of toenails. The concentration of phenol solution and duration of its application have varied widely and have not been subjected to scientific study. The authors studied the histologic effects of phenol on the nail matrix and determined the optimal concentration of phenol and time the phenol solution needs to be in contact with the nail bed.

L-arginine potentiates negative inotropic and metabolic effects to myocardium partly through the amiloride sensitive mechanism

Recently, cytokines have been proposed to cause cellular injury by nitric oxide (NO.) mediated pathway and L-arginine has been proposed to impair intracellular pH (pH(i)) regulation via vacuolar type H(+)-ATPase in macrophage. We conducted this investigation on Langendorff perfused hearts of rabbits to elucidate the mechanisms involving the NO. precursor L-arginine on myocardial contractile function, glycolysis, mitochondrial respiration, and intracellular alkalinization and tested the effects of amiloride. L-Arginine caused a significant loss of contractile function (96+/-4 mmHg in control, 53+/-16 during L-arginine perfusion, p<0.01) and a significant increase of pH(i) (7.01+/-0.02 prearginine infusion, 7.08+/-0.03 at the end of L-arginine infusion, p<0.01) along with decreased oxygen consumption (MVO(2)) (0.94+/-0.32 ml/min/g dry wt.), increased lactate release, and a loss of creatine phosphate (15% loss). Amiloride could prevent the cell alkalinization and contractile dysfunction, but not the derangement of oxidative metabolism caused by L-arginine in myocytes. We conclude that L-arginine has two distinct effects upon the myocardium: (1) an amiloride-sensitive loss of contractile function associated with intracellular alkalinization; and (2) an amiloride-insensitive inhibition of oxidative metabolism, possibly because of increased myocardial NO. production.

Purification and structure elucidation of the N-acetylbacillosamine-containing polysaccharide from Bacillus licheniformis ATCC 9945

The exopolysaccharide of Bacillus licheniformis ATCC 9945 (formerly B. subtilis ATCC 9945) contains among other glycoses 4-acetamido-2-amino-2,4,6-trideoxy-D-glucose, termed N-acetylbacillosamine (Bac2N4NAc). A similar diamino glycose, 2-acetamido-4-amino-2,4,6-trideoxy-D-glucose, was found in a surface layer (S-layer) glycoprotein preparation of Clostridium symbiosum HB25. Electron microscopic studies, however, showed that B. licheniformis ATCC 9945 is not covered with an S-layer lattice, indicating that the N-acetylbacillosamine present in that organism might be a constituent of a cell wall-associated polymer. For elucidation of the structure of the N-acetylbacillosamine-containing polysaccharide, it was purified from a trichloroacetic acid extract of B. licheniformis ATCC 9945 cells. Using different hydrolysis protocols and a hydrolysate of the S-layer glycoprotein preparation from C. symbiosum HB25 as reference, the purified polysaccharide was found to contain 2,4-diamino-2,4,6-trideoxy-glucose, 2-acetamido-2-deoxy-glucose, 2-acetamido-2-deoxy-galactose and galactose in a molar ratio of 1 : 1 : 1 : 2. One- and two-dimensional NMR spectroscopy, including 800 MHz proton magnetic resonance measurements, in combination with chemical modification and degradation experiments, revealed that the polysaccharide consists of identical pyruvylated pentasaccharide repeating units with the structure: [-->3)-[(S)Py-(3,4)-beta-D-Galp-(1-->6)]-alpha-D-GlcpNAc-(1-->3)-beta-D-Bacp2N4NAc-(1-->3)-[(S)Py-(3,4)-beta-D-Galp-(1-->6)]-beta-D-GalpNAc-(1-->](n)

Formic acid dissolves aggregates of an N-terminal huntingtin fragment containing an expanded polyglutamine tract: applying to quantification of protein components of the aggregates

Huntington's disease (HD) is caused by an expansion of the CAG repeat that encodes polyglutamine in huntingtin. Transient expression of an N-terminal huntingtin fragment containing an expanded polyglutamine tract induced formation of protein aggregates in cultured cells. The turnover of protein components in such aggregates has been difficult to study because of their insolubility in aqueous solutions. Here we describe a method of solubilizing the aggregates and quantifying their protein components. Insoluble pellets were collected from COS7 cells expressing an N-terminal huntingtin fragment containing an expanded polyglutamine tract and subjected to treatment with various detergent, acid, and alkaline reagents. Treatment with 100% formic acid at 37 degrees C for 30 min induced essentially complete dissociation of the aggregates to monomer. We used this solubilization technique to quantify huntingtin fusion protein in the aggregates formed in transient expression experiments. The frequency of aggregate formation increased when the proteasome inhibitor beta-lactone was added to culture media. However, the total amount of accumulated huntingtin fusion protein did not differ between cells cultured with or without beta-lactone. These results suggest that other protein components which are degraded by the proteasome, in addition to huntingtin, might be related to the dynamics of polyglutamine protein aggregates.

Assessment of iron absorption from ferric trimaltol

Therapeutic iron compounds have limited absorption and often have side-effects, which limits patient compliance. Iron trimaltol is a novel, stable complex, formed between ferric iron (Fe3+) and maltol (3-hydroxy-2-methyl-4-pyrone), and is effective in the treatment of iron deficiency anaemia with few side-effects. However, the kinetics of iron absorption from ferric trimaltol and the reliability of normal colorimetric analysis in detecting iron absorbed from this complex have not been established. We measured increases in serum iron levels in 12 volunteers following oral challenge with four different pharmaceutical formulations of ferric trimaltol in a double-blind, cross-over, randomized study. The conventional colorimetric method for detecting serum iron was compared with thermal analyses after trichloroacetic acid (TCA) treatment of serum. Measurements of serum iron levels by TCA treatment and thermal analysis closely agreed with measurements by colorimetry. For all formulations, serum iron levels peaked at 90 min with a plateau of at least 5 h [mean (standard deviation) peak absorption 8.3% (6.3%) of ingested dose, n=48]. Absorption of iron, based on peak serum values or area under the serum curve, was not different for the four formulations (n=12 each) and correlated with the individual's iron status, as assessed by serum ferritin values (r = -0.6; P < 0.001). Normal colorimetry is suitable for analysis of serum iron levels following ingestion of ferric trimaltol. There is rapid and sustained absorption of iron from ferric trimaltol and, as with ferrous iron, uptake appears to be controlled through normal mechanisms of iron acquisition that depend upon body iron stores.

Comparative caustic and biological activity of trichloroacetic and glycolic acids on keratinocytes and fibroblasts in vitro

OBJECTIVES

Beside their causticity, the biological mechanism by which trichloroacetic acid (TCA) and glycolic acid (GA), two agents extensively used for chemical peeling, might act remains unknown. The purpose of this study was to examine in vitro the effect of TCA and GA on human keratinocytes and the influence of the released epithelial mediators on collagen and matrix metalloproteinases (MMPs) production by human dermal fibroblasts.

METHOD

Cultured keratinocytes were treated by TCA and GA at 10 mg/ml brought to pH 3, 5 and 7, and the conditioned media neutralized to pH 7 were added to human normal skin fibroblasts.

RESULTS

TCA was cytotoxic for keratinocytes at each tested pH. The conditioned medium depressed protein and collagen synthesis and the expression of MMPs when added to fibroblasts as did also TCA when added directly to fibroblasts. GA was not cytotoxic for keratinocytes at neutral pH and the conditioned medium obtained at each pH applied to fibroblasts did not alter protein, collagen nor MMPs production while causing an elevated secretion of IL-6.

CONCLUSION

TCA exerts a toxic effect on keratinocytes and fibroblasts while GA does not alter the metabolism of fibroblasts but induces the secretion of IL-6.

[Risk prevention of transmissible subacute spongiform encephalopathies]

The risk assessment of transmissible spongiform encephalopathies (TSEs or prion diseases) can be managed at three levels: 1. control of source material that could be potentially infected (biological products of human or animal origin, instruments in contact with these products); 2. control of the processes for the purification of biological products and instrument decontamination techniques; 3. evaluation of invasive medical or surgical acts. Highest infectivity is found in central nervous system. TSE agents do resist to almost all usual decontamination procedures. National recommended procedures include sodium hypochlorite 18,500 ppm or sodium hydroxide 1N for 1 hour and autoclaving at at least 134 degrees C for at least 18 min.

Early repeeling--a matter of time

BACKGROUND

Repeeling after a short interval in medium-depth or deep peeling is considered by most experts as hazardous, and is generally contraindicated. Most experts recommend an interval of 6 months or more before repeating the same level of peel. The results are presented of four patients who underwent repeeling after a short interval.

METHODS AND RESULTS

All four patients were dissatisfied with their first peel (medium-depth peel performed with trichoroacetic acid (TCA) 35%). Repeelings were performed using two methods: TCA 30-35% (Cases 1-3) and unoccluded Baker phenol peel (Case 4). On three occasions (Cases 1-3), the patients underwent three peelings at short intervals. All four cases gave excellent objective results.

CONCLUSIONS

The risk of a second peel shortly after the first is not as high as indicated in the literature, and should not be automatically ruled out. In a selected group of patients who, for various reasons, be persuaded to wait, repeeling after a short interval (2-3 weeks) may solve certain problems and may even make the difference between an unhappy patient and a satisfied one. In performing repeeling after a short interval, one should take into consideration that the skin, particularly the keratin layer, is thinner, so that the degree of penetration of the second peel solution and the peel depth will be greater. It is possible that the scarring reported after repeeling is a result of the disregard of this important factor and, consequently, the use of too high a concentration of peel solution in the second peel procedure.

Differential sensitivity of chromium-mediated DNA interstrand crosslinks and DNA-protein crosslinks to disruption by alkali and EDTA

Some compounds of hexavalent chromium are well-established carcinogens. Chromium enters mammalian cells in the hexavalent form and is reduced to chromium (III). Treatment of purified DNA with chromium (III) produces DNA-DNA interstrand crosslinks (DDC) which obstruct the progression of DNA polymerases in vitro. DDC were also detected in chromate-treated cultured normal human lung cells using the renaturing agarose gel electrophoresis (RAGE) assay and correlated with base-specific inhibition of DNA replication. Curiously, DDC have gone undetected in studies of cultured cells using the alkaline elution (AE) technique, whereas chromium-mediated DNA-protein crosslinks (DPC) were readily detected by AE. We tested the hypothesis that AE conditions [60 mM tetraethyl ammonium hydroxide (TEA), 20 mM EDTA, pH 12.6, for 16 h at room temperature] dissociate DDC but not DPC using chromium(III)-treated plasmid DNA and the RAGE assay. Dose-dependent chromium-induced DDC were unaffected by TEA (pH 11.8) alone or by more rigorous alkaline denaturation conditions (200 mM NaOH, pH 13.5, for 16 h). DDC were, however, completely disrupted by EDTA (pH 12.6) alone or the combination of TEA and EDTA (pH 12.6). In contrast, DPC remained largely intact under these conditions. Therefore, past AE-based studies which have failed to detect chromium-induced DDC do not prove the absence of this lesion. AE may not be suitable for detecting DDC induced by EDTA-chelatable agents such as metals.

The structure of interfibrillar proteoglycan bridges (shape modules') in extracellular matrix of fibrous connective tissues and their stability in various chemical environments

Collagen fibrils in extracellular matrices of connective tissues (tendon, cornea, etc.) are bridged and linked by the anionic glycosaminoglycans (AGAGs) of the small proteoglycans (decoron, etc.). It was proposed that these bridges and ties maintain the collagen fibril dispositions in relation to each other, helping to define tissue shape, and hence called shape modules. This investigation describes chemical and physicochemical conditions in which these structures are stable and what treatments cause their disruption. The effects on fixed and unfixed sections of tendon, cornea, lung and ear from rat, mouse and rabbit of pH, electrolyte concentration, EDTA, mercaptoethanol, hydrogen peroxide, free radicals, periodate, acetylation, urea, nonionic detergent and organic solvents were assessed by staining with Cupromeronic blue or Alcec blue in CEC techniques to localise AGAG bridges or their disintegration products. Ca2+ was not involved in the structures, oxidation/reduction had no effect and Triton X100, a nonionic detergent did not damage them. They were stable between pH 4.5 and 9.5. Periodate as a glycol-cleaving reagent did not affect them. High concentrations of urea (> 2.0 M) and MgCl2 (0.5 M) disrupted the tissues. The combination of Triton and urea at concentrations too low to cause damage separately was disruptive. Free radicals in periodate solutions were damaging. Organic solvents caused collapse and rearrangements of the AGAG filaments. Acetylation caused considerable disruption of shape modules. Dermochondan but not keratan sulphate AGAGs were removed by treatment with NaOH. After fixing with glutaraldehyde only free radical and NaOH treatments were severely disruptive of shape modules. The results are compatible with a previously proposed structure for the shape modules, stabilised by hydrophobic and hydrogen bonding.

Thermal characteristics of neutralization therapy and water dilution for strong acid ingestion: an in-vivo canine model

OBJECTIVE

To determine whether in-vivo neutralization therapy for acid ingestions will superimpose a thermal injury upon tissue already damaged by acid.

METHODS

An in-vivo canine model was used with repeated measures of tissue and luminal temperatures. All dogs were placed under halothane general anesthesia. The stomach was exteriorized and temperature probes were placed in the lumen and mucosa. 25 mL of 0.5 N HCl (25 degrees C) was placed in the gastric lumen followed 5 minutes later by 75 mL of either 8% NaHCO3 neutralization (25 degrees C, n = 10) or water dilution (25 degrees C, n = 10). Temperature measurements were recorded at specified intervals for 5 minutes post HCl acid exposure and for 30 minutes post treatment. Temperature profiles were analyzed by repeated-measures ANOVA. Post-treatment changes were evaluated using signed-rank tests.

RESULTS

In both treatment groups, treatment resulted in significant decreases in initial mucosa and intraluminal temperatures. Both the mucosa and intraluminal temperatures decreased immediately after treatment with HCO3 by an average of 1.6 degrees C (p = 0.05). In the water dilution treatment group, both temperatures decreased by 1.1 degrees C (p = 0.05). Ensuing post-treatment temperatures increased but did not reach baseline temperatures at any time up to 30 minutes post treatment.

CONCLUSIONS

In the in-vivo setting, there is no evidence of hazardous temperature elevation when a weak alkali or dilution therapy is used to neutralize strong acid-induced injury. Contraindication of this form of emergency treatment should not be based on the preconceived idea that a resultant exothermic reaction will cause a superimposed thermal injury. Further clinical study is needed to determine the clinical utility of this emergency therapeutic modality.

Effectiveness of sodium hydroxide as a pleural sclerosing agent in rabbits: influence of concomitant intrapleural lidocaine

The two agents that have been used most commonly to produce a pleurodesis are tetracycline and bleomycin. Tetracycline is no longer generally available because of more stringent requirements on the manufacturing process. Bleomycin is very expensive. Therefore, alternative agents are necessary particularly in developing countries. The objective of this project was to determine whether 0.5% sodium hydroxide is an effective sclerosant in an experimental model in rabbits. Sodium hydroxide (NaOH) (2 ml of 0.5%) was instilled intrapleurally in 24 anesthetized male rabbits. Half the rabbits received 1 ml of 2% lidocaine 3-5 min before the NaOH. Twenty-eight days after the instillation, the animals were sacrificed, and the pleural spaces were assessed grossly for evidence of pleurodesis and microscopically for evidence of fibrosis and inflammation. The results indicated that the intrapleural injection of NaOH was effective in creating a pleurodesis only if the animals were not premedicated with lidocaine. The mean (+/- S.D.) degree of gross pleurodesis after NaOH alone 2.8 (1.0) was significantly (p < 0.001) greater than after that following the combination 1.3 (0.5). We conclude that NaOH is an effective pleural sclerosant but that it is ineffective if it is injected concomitantly with lidocaine.

[Gastric injury by caustics: a case report]

The authors get the idea from the observation of a case of ingestion of muriatic acid, recently happened by Clinical Surgery II of the IRCCS Polyclinic "San Matteo" of Pavia in order to examine carefully the matter. The rareness of the shown case is given by the whole involvement of only the stomach, without damages for the oropharynx and the esophagus. The total gastrectomy executed 6 months after the ingestion of the acid has given to the patient the whole recovery. The follow-up checked for a periodical time of 6 months for a period of about five years, permits to observe the normal intestinal canalization without stenitical symptoms or zonas with degenerative risk.

[Results of chewing and ruminant activity of cows fed rations of cereal straw of various physical forms and after chemical treatment with sodium lye]

3 trials were conducted with adult cows. The animals received different types of coarse fodder (straw, lucerne) which was subjected to chemical treatment (liquid NaOH) and mechanical treatment (pelleting, wafering); then, the chewing and ruminating activity of the cows was measured. Different criteria were used, i.e. movements of the jaws during food intake and rumination and number of regurgitated bits of food. On the average, one movement of jaws lasted 0.94 sec. and swallowing and regurgitation took 5.5 sec. From this, the duration of the rumination process was determined. No differences in ruminating activity were found between lucerne and chopped/chaffed food while the the case of wheat straw about 30% of additional ruminating activity was performed in comparison with pelleted lucerne and chaffed food. This structural effect was even a bit more pro nounced when the straw was first ground and then wafered. Preceding chemical treatment of the straw with liquid NaOH reduced the ruminating activity in the case of chopped food by 53%, with pellets by 40% and with straw pressed into blocks by 62%. The finess of the feed was in no case found to be related to rumination activities, while hardness of the food particles as well as physical and chemical treatment of the food had an importent influence on the rumination activity.

Comparative studies on the detoxification of aflatoxins by sodium hypochlorite and commercial bleaches

Cultures of Aspergillus flavus and aflatoxins were destroyed by a commercial bleach (Clorox; active ingredient, NaOCl) or analytical reagent grade NaOCl at 7.0 x 10(-3) M NaOCl in 5 days. Addition of Clorox or NaOCl at 2.8 x 10(-3) M to the fungal growth medium prior to inoculation completely inhibited the fungal growth. Aflatoxin production was inversely proportional to the logarithm of NaOCl concentration and time of treatment. Clorox and NaOCl were equally effective on aflatoxins, but fungal cells were lysed more readily by Clorox than by NaOCl. Mycelia older than 8 days lysed more readily than younger ones. Most conidia survived concentrations below 1.4 x 10(-3) M. The lowest effective concentration for a 2-hr treatment was 8.8 x 10(-3) M which is well below the Clorox concentration recommended for routine laboratory decontamination of aflatoxins. Mice and rats injected with aflatoxins and aflatoxins incompletely destroyed by Clorox died within 72 hr and had typical liver and kidney damage caused by aflatoxins. However, animals injected with NaOCl or Clorox or Clorox-destroyed aflatoxin extracts survived and showed no obvious liver or kidney damage.

Corrosive damage to stomach simulating carcinoma

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