Biomarker profiling in plants to distinguish between exposure to chlorine gas and bleach using LC-HRMS/MS and chemometrics.

Since its first employment in World War I, chlorine gas has often been used as chemical warfare agent. Unfortunately, after suspected release, it is difficult to prove the use of chlorine as a chemical weapon and unambiguous verification is still challenging. Furthermore, similar evidence can be found for exposure to chlorine gas and other, less harmful chlorinating agents. Therefore, the current study aims to use untargeted high resolution mass spectrometric analysis of chlorinated biomarkers together with machine learning techniques to be able to differentiate between exposure of plants to various chlorinating agents. Green spire (Euonymus japonicus), stinging nettle (Urtica dioica), and feathergrass (Stipa tenuifolia) were exposed to 1000 and 7500 ppm chlorine gas and household bleach, pool bleach, and concentrated sodium hypochlorite. After sample preparation and digestion, the samples were analyzed by liquid chromatography high resolution tandem mass spectrometry (LC-HRMS/MS) and liquid chromatography tandem mass spectrometry (LC-MS/MS). More than 150 chlorinated compounds including plant fatty acids, proteins, and DNA adducts were tentatively identified. Principal component analysis (PCA) and linear discriminant analysis (LDA) showed clear discrimination between chlorine gas and bleach exposure and grouping of the samples according to chlorine concentration and type of bleach. The identity of a set of novel biomarkers was confirmed using commercially available or synthetic reference standards. Chlorodopamine, dichlorodopamine, and trichlorodopamine were identified as specific markers for chlorine gas exposure. Fenclonine (Cl-Phe), 3-chlorotyrosine (Cl-Tyr), 3,5-dichlorotyrosine (di-Cl-Tyr), and 5-chlorocytosine (Cl-Cyt) were more abundantly present in plants after chlorine contact. In contrast, the DNA adduct 2-amino-6-chloropurine (Cl-Ade) was identified in both types of samples at a similar level. None of these chlorinated biomarkers were observed in untreated samples. The DNA adducts Cl-Cyt and Cl-Ade could clearly be identified even three months after the actual exposure. This study demonstrates the feasibility of forensic biomarker profiling in plants to distinguish between exposure to chlorine gas and bleach.

Atrial arrhythmias and acute pericarditis triggered by bleach ingestion-associated oesophageal perforation: a case report.

Background: Acute pericarditis due to oesophageal perforation and caustic injury is a rare presentation of bleach ingestion. Cardiac arrhythmias such as atrial fibrillation and atrial flutter have been associated with certain aetiologies of acute pericarditis. This case report presents a unique occurrence of acute pericarditis following bleach ingestion and intermittent atrial fibrillation and atrial flutter triggered by liquid intake. Case summary: A 36-year-old male with no significant past medical history presented after attempted suicide by ingesting bleach. He had acute pericarditis resulting from caustic oesophageal perforation and extensive mediastinal injury. In the following days, he developed recurrent episodes of atrial fibrillation and atrial flutter following fluid intake, prompting treatment with metoprolol. On Day 5 of hospitalization, he underwent an oesophagogram and developed persistent atrial arrhythmia with haemodynamic instability requiring cardioversion. He underwent thoracoscopic surgery to address the oesophageal injury. A jejunostomy tube was placed and he had complete resolution of his recurrent atrial arrhythmia. Discussion: This case highlights a rare presentation of atrial arrhythmias and acute pericarditis caused by corrosive oesophageal injury due to bleach ingestion. The effective management of such cases necessitates a co-ordinated approach, involving the collaboration of cardiothoracic surgeons, cardiologists, and critical care specialists, with the aim of enhancing patient outcomes and mitigating the life-threatening risks associated with oesophageal perforation and cardiac arrhythmias. Furthermore, this case underscores the imperative for further research to better understand the relationship between traumatic acute pericarditis and atrial arrhythmias, offering the potential for improved patient care in these intricate clinical scenarios.

Hepatic Portal Venous Gas (HPVG) after Ingestion of Chlorine Bleach: A Transient Phenomenon.

We present a case involving a 32-year-old man who ingested chlorine bleach with self-defeating intent. The ingestion of bleach can lead to a wide range of consequences, from mild mucosal burns to severe complications, rarely resulting in death. This case highlights the association between chlorine bleach ingestion and the development of hepatic portal venous gas (HPVG), a radiological finding traditionally thought to carry poor prognoses. The HPVG in this case resolved spontaneously within 24 h with conservative management, indicating its transient nature. The exact pathophysiological mechanisms responsible for HPVG after the ingestion of toxic substances .remain only partially understood. One hypothesis suggests that extensive damage to the gastrointestinal wall caused by caustic agent may allow enteric gas to enter the portal system. While HPVG after toxic ingestion is often transient, its consequences and potential risks should be carefully considered. Hyperbaric oxygen therapy is suggested in cases with neurological symptoms. In conclusion, HPVG is not a specific disease but rather a manifestation of various underlying factors, and its development in the context of chlorine bleach ingestion represents an additional insight to its understanding. It can be associated with severe medical conditions, but it is also found in less severe cases that can be managed conservatively.

Management of Discoloured Anterior Teeth With Radicular Cyst: A Case Report.

Dental trauma often has tooth discoloration and periapical lesion as its sequelae. Intracoronal bleaching restores the aesthetics, while a retrograde approach is required for non-healing lesions. A patient with discolored teeth, draining sinus, tenderness and a periapical lesion on the radiograph was treated initially with conventional root canal therapy and walking bleach technique. After four months, the sinus tract reappeared and on cone-beam computed tomography (CBCT) examination, a large periapical lesion with loss of buccal cortical plate was seen. A minimally invasive retrograde cystic enucleation, apicectomy, and filling with biodentine were then performed. The defect area was filled with synthetic nanocrystalline hydroxyapatite granules combined with platelet-rich-fibrin. Follow-ups after one, three, and six months were taken. The six-month CBCT revealed complete bone healing. Non-vital bleaching yields acceptable cosmetic results. Additionally, if the conventional procedures are not successful in treating radicular cyst, apical surgery must be the ultimate choice.

Evolution of light absorption properties during photochemical aging of straw open burning aerosols.

Straw burning comprises more than 30% of all types of burned biomass in Asia, while the estimation of the emitted aerosols' direct radiative forcing effect suffers from large uncertainties, especially when atmospheric aging processes are considered. In this study, the light absorption properties of primary and aged straw burning aerosols in open fire were characterized at 7 wavelengths ranging from 370 nm to 950 nm in a chamber. The primary rice, corn and wheat straw burning bulk aerosols together had a mass absorption efficiency (MAE) of 2.43 ± 1.36 m2 g-1 at 520 nm and an absorption Ångström exponent (AAE) of 1.93 ± 0.71, while the primary sorghum straw burning bulk aerosols were characterized by a relatively lower MAE of 0.95 ± 0.54 m2 g-1 and a higher AAE of 4.80 ± 0.68. Both the MAE and AAE of primary aerosols can be well parameterized by the (PM-BC)/BC ratio (in wt.). The MAE of black carbon (BC) increased by 11-190% during photoreactions equivalent to 16-60 h of atmospheric aging, which was positively correlated with the (PM-BC)/(BC) ratio. The MAE of organic aerosols first slightly increased or leveled off, and then decreased. Specifically, at 370 nm, the first growth/plateau stage lasted until OH exposure reached 0.47-1.29 × 1011 molecule cm-3 s, and the following period exhibited decay rates of 1.0-2.8 × 10-12 cm3 molecule-1 s-1 against the OH radical, corresponding to half-lives of 46-134 h in a typical ambient condition. During photoreactions, competition among the lensing effect, growth/bleach of organic chromophores, and particle mass and size growth complicated the evolution of the direct radiative forcing effect. It is concluded that rice and corn straw burning aerosols maintained a warming effect after aging, while the cooling effect of fresh sorghum straw burning aerosols increased with aging.

Behavior of Isocyanic Acid and Other Nitrogen-Containing Volatile Organic Compounds in The Indoor Environment.

Isocyanic acid (HNCO) and other nitrogen-containing volatile chemicals (organic isocyanates, hydrogen cyanide, nitriles, amines, amides) were measured during the House Observation of Microbial and Environmental Chemistry (HOMEChem) campaign. The indoor HNCO mean mixing ratio was 0.14 ± 0.30 ppb (range 0.012-6.1 ppb), higher than outdoor levels (mean 0.026 ± 0.15 ppb). From the month-long study, cooking and chlorine bleach cleaning are identified as the most important human-related sources of these nitrogen-containing gases. Gas oven cooking emits more isocyanates than stovetop cooking. The emission ratios HNCO/CO (ppb/ppm) during stovetop and oven cooking (mean 0.090 and 0.30) are lower than previously reported values during biomass burning (between 0.76 and 4.6) and cigarette smoking (mean 2.7). Bleach cleaning led to an increase of the HNCO mixing ratio of a factor of 3.5 per liter of cleaning solution used; laboratory studies indicate that isocyanates arise via reaction of nitrogen-containing precursors, such as indoor dust. Partitioned in a temperature-dependent manner to indoor surface reservoirs, HNCO was present at the beginning of HOMEChem, arising from an unidentified source. HNCO levels are higher at the end of the campaign than the beginning, indicative of occupant activities such as cleaning and cooking; however the direct emissions of humans are relatively minor.

1,4-Bis((9H-Carbazol-9-yl)Methyl)Benzene-Containing Electrochromic Polymers as Potential Electrodes for High-Contrast Electrochromic Devices.

Four 1,4-bis((9H-carbazol-9-yl)methyl)benzene-containing polymers (PbCmB, P(bCmB-co-bTP), P(bCmB-co-dbBT), and P(bCmB-co-TF)) were electrosynthesized onto ITO transparent conductive glass and their spectral and electrochromic switching performances were characterized. The PbCmB film displayed four types of color variations (bright gray, dark gray, dark khaki, and dark olive green) from 0.0 to 1.2 V. P(bCmB-co-bTP) displayed a high transmittance variation (∆T = 39.56% at 685 nm) and a satisfactory coloration efficiency (η = 160.5 cm2∙C-1 at 685 nm). Dual-layer organic electrochromic devices (ECDs) were built using four bCmB-containing polycarbazoles and poly(3,4-ethylenedioxythiophene) (PEDOT) as anodes and a cathode, respectively. PbCmB/PEDOT ECD displayed gainsboro, dark gray, and bright slate gray colors at -0.4 V, 1.0 V, and 2.0 V, respectively. The P(bCmB-co-bTP)/PEDOT ECD showed a high ∆T (40.7% at 635 nm) and a high coloration efficiency (η = 428.4 cm2∙C-1 at 635 nm). The polycarbazole/PEDOT ECDs exhibited moderate open circuit memories and electrochemical redox stability. The characterized electrochromic properties depicted that the as-prepared polycarbazoles had a satisfactory application prospect as an electrode for the ECDs.

A multiphase intervention of novel color additive for bleach disinfectant wipes improves thoroughness of cleaning in an academic medical center.

Surface disinfection is critical for preventing health care-associated infections; however, sustaining high-quality cleaning technique is challenging without constant feedback and training of staff. A novel color additive to bleach wipes, Highlight, indicates where surfaces have been wiped and fades to colorless to provide real-time visual feedback of cleaning. In a multiphase interventional study, Highlight reduced failure rates of cleaning based on fluorescent marker removal (15.0%-4.5%) and adenosine triphosphate bioluminescence assay (3.6%-2.5%).

Nitinol Release of Nickel under Physiological Conditions: Effects of Surface Oxide, pH, Hydrogen Peroxide, and Sodium Hypochlorite.

Nitinol is a nickel-titanium alloy widely used in medical devices for its unique pseudoelastic and shape-memory properties. However, nitinol can release potentially hazardous amounts of nickel, depending on surface manufacturing yielding different oxide thicknesses and compositions. Furthermore, nitinol medical devices can be implanted throughout the body and exposed to extremes in pH and reactive oxygen species (ROS), but few tools exist for evaluating nickel release under such physiological conditions. Even in cardiovascular applications, where nitinol medical devices are relatively common and the blood environment is well understood, there is a lack of information on how local inflammatory conditions after implantation might affect nickel ion release. For this study, nickel release from nitinol wires of different finishes was measured in pH conditions and at ROS concentrations selected to encompass and exceed literature reports of extracellular pH and ROS. Results showed increased nickel release at levels of pH and ROS reported to be physiological, with decreasing pH and increasing concentrations of hydrogen peroxide and NaOCl/HOCl having the greatest effects. The results support the importance of considering the implantation site when designing studies to predict nickel release from nitinol and underscore the value of understanding the chemical milieu at the device-tissue interface.

Efectividad de sustancias químicas en el clareamiento y biopelícula dental aplicado en el consultorio y ambulatorio / Effectiveness of chemical substances in bleaching and dental biofilm applied in the office and outpatient

El blanqueamiento dental está considerado como pieza fundamental en el embellecimiento de los seres humanos, ya que permite la restauración de la "sonrisa perfecta". Este proceso en sí, es poco invasivo y juega como un gran papel como aliado en la restauración satisfactoria de la sonrisa y autoestima del paciente. Es un procedimiento que debe ser aplicado cuidadosamente para lograr los efectos positivos del mismo. El fundamento de esta técnica es aclarar la tonalidad que han sufrido los dientes por diversos factores: extrinsecos, intrínsecos y decoloraciones internas. Durante el procedimiento, es usual el uso de peróxido de hidrógeno (H2O2) en concentraciones que van del 10 al 32 % en volumen o el peróxido de carbamida, un compuesto conformado por peróxido de hidrógeno y urea concentraciones del 10 al 22 %. El uso de peróxido de hidrógeno se lleva a cabo fundamentalmente en los consultorios, mientras que el uso del peróxido de carbamida es un procedimiento doméstico. A pesar de los excelentes resultados que se obtiene al usar ambos blanqueadores, su uso puede ocasionar erosiones dentales y sensibilidad dentaria. El primer caso, puede llevar a la adherencia de bacterias cariogénicas como el Strepctococus mutans responsable de caries. Los resultados obtenidos, demostraron que el peróxido de hidrógeno es un agente más agresivo que el peróxido de carbamida, lo cual origina mayor sensibilidad dentaria y un mayor control bacteriano; en cambio el peróxido de carbamida fue mejor blanqueador y originó menor sensibilidad dental(AU)

Tooth whitening is considered a fundamental piece in the beautification of human beings, since it allows the restoration of the "perfect smile". This process itself is minimally invasive and plays a great role as an ally in the satisfactory restoration of the patient's smile and self-esteem. It is a procedure that must be carefully applied to achieve its positive effects. The basis of this technique is to clarify the shade that the teeth have suffered due to various factors: extrinsic, intrinsic and internal discoloration. During the procedure, the use of hydrogen peroxide (H2O2) in concentrations ranging from 10 to 32% by volume or carbamide peroxide, a compound made up of hydrogen peroxide and urea concentrations of 10 to 22%, is usual. The use of hydrogen peroxide is mainly carried out in offices, while the use of carbamide peroxide is a home procedure. Despite the excellent results obtained by using both whiteners, their use can cause dental erosion and tooth sensitivity. The first case can lead to the adherence of cariogenic bacteria such as Streptococcus mutans responsible for caries. The results obtained showed that hydrogen peroxide is a more aggressive agent than carbamide peroxide, which causes greater dental sensitivity and greater bacterial control; On the other hand, carbamide peroxide was a better whitener and caused less dental sensitivity(AU)

BioChemPen for a Rapid Analysis of Compounds Supported on Solid Surfaces.

We present BioChemPen, a portable wireless biosensor device for rapid analysis of substances adsorbed on solid surfaces. The device takes advantage of (bio)luminescent reactions taking place in a hydrogel matrix. In a typical embodiment, the active element of this device is a hydrogel disk (chemotransducer) containing enzyme(s), electrolyte solution, and all of the necessary substrates. When the hydrogel is exposed to a solid sample surface containing the target analyte, light is produced. A photoresistor (phototransducer), placed in close proximity to the hydrogel disk, detects the light. The operation of the BioChemPen is enabled by a MicroPython PyBoard microcontroller board and other low-cost electronic modules. The obtained results are immediately uploaded to the Internet cloud. In one application, we demonstrate an analysis of hypochlorite-containing cleaning agents present on the surfaces of daily use objects by an assay based on hydrogel embedded with luminol and hydrogen peroxide. In another application, we use hydrogel embedded with luciferin, luciferase, and pyruvate kinase to detect adenosine triphosphate (ATP), and adenosine diphosphate (ADP), and link the ATP content with meat freshness. Lastly, we demonstrate the detection of organophosphate pesticides present on vegetables with the hydrogel containing acetylcholinesterase, choline oxidase, and horseradish peroxidase. The limits of detection for sodium hypochlorite, ATP, ADP, and chlorpyrifos-methyl (a pesticide) were 7.95 × 10-11, 2.73 × 10-13, 2.35 × 10-12, and 2.59 × 10-10 mol mm-2, respectively.

Reactive Chlorine Species Reversibly Inhibit DnaB Protein Splicing in Mycobacteria.

Intervening proteins, or inteins, are mobile genetic elements that are translated within host polypeptides and removed at the protein level by splicing. In protein splicing, a self-mediated reaction removes the intein, leaving a peptide bond in place. While protein splicing can proceed in the absence of external cofactors, several examples of conditional protein splicing (CPS) have emerged. In CPS, the rate and accuracy of splicing are highly dependent on environmental conditions. Because the activity of the intein-containing host protein is compromised prior to splicing and inteins are highly abundant in the microbial world, CPS represents an emerging form of posttranslational regulation that is potentially widespread in microbes. Reactive chlorine species (RCS) are highly potent oxidants encountered by bacteria in a variety of natural environments, including within cells of the mammalian innate immune system. Here, we demonstrate that two naturally occurring RCS, namely, hypochlorous acid (the active compound in bleach) and N-chlorotaurine, can reversibly block splicing of DnaB inteins from Mycobacterium leprae and Mycobacterium smegmatis in vitro. Further, using a reporter that monitors DnaB intein activity within M. smegmatis, we show that DnaB protein splicing is inhibited by RCS in the native host. DnaB, an essential replicative helicase, is the most common intein-housing protein in bacteria. These results add to the growing list of environmental conditions that are relevant to the survival of the intein-containing host and influence protein splicing, as well as suggesting a novel mycobacterial response to RCS. We propose a model in which DnaB splicing, and therefore replication, is paused when these mycobacteria encounter RCS. IMPORTANCE Inteins are both widespread and abundant in microbes, including within several bacterial and fungal pathogens. Inteins are domains translated within host proteins and removed at the protein level by splicing. Traditionally considered molecular parasites, some inteins have emerged in recent years as adaptive posttranslational regulatory elements. Several studies have demonstrated CPS, in which the rate and accuracy of protein splicing, and thus host protein functions, are responsive to environmental conditions relevant to the intein-containing organism. In this work, we demonstrate that two naturally occurring RCS, including the active compound in household bleach, reversibly inhibit protein splicing of Mycobacterium leprae and Mycobacterium smegmatis DnaB inteins. In addition to describing a new physiologically relevant condition that can temporarily inhibit protein splicing, this study suggests a novel stress response in Mycobacterium, a bacterial genus of tremendous importance to humans.

A Bacterial Inflammation Sensor Regulates c-di-GMP Signaling, Adhesion, and Biofilm Formation.

Bacteria that colonize animals must overcome, or coexist, with the reactive oxygen species products of inflammation, a front-line defense of innate immunity. Among these is the neutrophilic oxidant bleach, hypochlorous acid (HOCl), a potent antimicrobial that plays a primary role in killing bacteria through nonspecific oxidation of proteins, lipids, and DNA. Here, we report that in response to increasing HOCl levels, Escherichia coli regulates biofilm production via activation of the diguanylate cyclase DgcZ. We identify the mechanism of DgcZ sensing of HOCl to be direct oxidation of its regulatory chemoreceptor zinc-binding (CZB) domain. Dissection of CZB signal transduction reveals that oxidation of the conserved zinc-binding cysteine controls CZB Zn2+ occupancy, which in turn regulates the catalysis of c-di-GMP by the associated GGDEF domain. We find DgcZ-dependent biofilm formation and HOCl sensing to be regulated in vivo by the conserved zinc-coordinating cysteine. Additionally, point mutants that mimic oxidized CZB states increase total biofilm. A survey of bacterial genomes reveals that many pathogenic bacteria that manipulate host inflammation as part of their colonization strategy possess CZB-regulated diguanylate cyclases and chemoreceptors. Our findings suggest that CZB domains are zinc-sensitive regulators that allow host-associated bacteria to perceive host inflammation through reactivity with HOCl. IMPORTANCE Immune cells are well equipped to eliminate invading bacteria, and one of their primary tools is the synthesis of bleach, hypochlorous acid (HOCl), the same chemical used as a household disinfectant. In this work, we present findings showing that many host-associated bacteria possess a bleach-sensing protein that allows them to adapt to the presence of this chemical in their environment. We find that the bacterium Escherichia coli responds to bleach by hunkering down and producing a sticky matrix known as biofilm, which helps it aggregate and adhere to surfaces. This behavior may play an important role in pathogenicity for E. coli and other bacteria, as it allows the bacteria to detect and adapt to the weapons of the host immune system.

A case of acute inhalation injury caused by premeditated chlorine gas exposure.

Chlorine is a toxic gas that causes severe inhalation injury. We report the case of a 43-year-old woman who inhaled chlorine gas generated by mixing household bleach and vinegar. She was referred to our hospital because she had developed respiratory failure. Chest computed tomography (CT) showed diffuse ground-glass opacity and the tree-in-bud pattern. We diagnosed acute inhalation injury compatible with that due to chlorine gas exposure. Six days after admission, her respiratory symptoms and abnormal CT findings fully resolved without the use of bronchodilators or corticosteroids. This is the first report of a patient with acute inhalation injury caused by intentional chlorine gas exposure. It is considered that chlorine gas reached her respiratory tract and induced widespread injury from bronchioles to alveoli.

Bleach-concentrated direct sputum smear microscopy procedure for diagnosis of pulmonary tuberculosis in poverty areas / Microscopia direta de amostra de escarro concentrado em água sanitária para diagnóstico de tuberculose pulmonar

ABSTRACT INTRODUCTION: Pulmonary tuberculosis caused by Mycobacterium tuberculosis is a serious public health problem affecting millions of people worldwide. The development of easy and low-cost diagnostic methods is crucial for disease control in rural remote and poverty areas and among vulnerable groups. OBJECTIVE: To evaluate the accuracy of laboratory methods for the diagnosis of Pulmonary tuberculosis. MATERIAL AND METHODS: Sputum samples from patients with clinical signs and symptoms were analyzed by microscopy after chemical treatment and spontaneous sedimentation and compared with methods employed routinely: direct sputum smear microscopy, culture, and GeneXpert®MTB/RIF. RESULTS: From the samples analyzed, 16% were positive by microscopy in the processed samples, 18% by both culture and Xpert®MTB/RIF, while 13% in the direct microscopy. The processed samples showed a 31% increase in positivity (57 samples) compared to conventional direct microscopy. In the analysis of the accuracy of the evaluated methods, all the results were statistically significant proving that they were not randomly positive or negative and confirming that there is a tendency for these results. CONCLUSION: Chemical treatment and spontaneous sedimentation of the sputum samples procedure represent an effective diagnostic tool in situations where more advanced technologies are not feasible. Besides the higher accuracy and greater detection of positive cases regarding the direct smear, the procedure strengthens biosafety by decreasing the risks of aerial contamination by Mycobacterium tuberculosis for laboratory professionals.

RESUMEN INTRODUCCIÓN: La tuberculosis pulmonar causada por Mycobacterium tuberculosis es un grave problema de salud pública que afecta millones de individuos en el mundo. El desarrollo de métodos de diagnóstico fáciles y de bajo costo es esencial para el control de la enfermedad en zonas rurales remotas y pobres y entre los grupos vulnerables. OBJETIVO: Evaluar la exactitud de métodos de laboratorio para el diagnóstico de tuberculosis pulmonar. MATERIAL Y MÉTODO: Las muestras del esputo de pacientes con signos y síntomas clínicos fueron analizadas por microscopía luego de tratamiento químico y sedimentación espontánea y comparados con métodos empleados ordinariamente: baciloscopía directa de esputo, cultivo y GeneXpert® MTB/RIF. RESULTADOS: Entre las muestras analizadas, 16% fueron positivas por microscopía en las muestras procesadas; 18% por cultivo y Xpert® MTB/RIF; y 13% por microscopía directa. Las muestras procesadas presentaran un aumento de 31% de positividad (57 muestras) con respecto a la microscopía directa convencional. En el análisis de los métodos, todos los resultados fueron estadísticamente significativos, comprobando que no eran aleatoriamente positivos o negativos y confirmando que hay una tendencia para esos resultados. CONCLUSIÓN: El tratamiento químico y la sedimentación espontánea de las muestras de esputo representan una herramienta diagnóstica eficaz en las situaciones en las cuales tecnologías más avanzadas no son viables. Además de la mayor precisión y mayor detección de casos positivos de lo que hace el frotis directo, el procedimiento fortalece la bioseguridad, disminuyendo los riesgos de contaminación del aire por Mycobacterium tuberculosis para el personal de laboratorio.

RESUMO INTRODUÇÃO: A tuberculose pulmonar causada por Mycobacterium tuberculosis é um grave problema de saúde pública que afeta mundialmente milhões de indivíduos. O desenvolvimento de métodos de diagnóstico fáceis e de baixo custo é essencial para o controle da doença nas áreas rurais remotas e de pobreza e entre os grupos vulneráveis. OBJETIVO: Avaliar a acurácia dos métodos laboratoriais para o diagnóstico de tuberculose pulmonar. MATERIAL E MÉTODOS: As amostras de escarro de pacientes com sinais e sintomas clínicos foram analisadas por microscopia após tratamento químico e sedimentação espontânea e comparadas com métodos empregados rotineiramente: baciloscopia direta do escarro, cultura e GeneXpert® MTB/RIF. RESULTADOS: Das amostras analisadas, 16% foram positivas por microscopia nas amostras processadas; 18%, por cultura e Xpert® MTB/RIF; e 13%, por microscopia direta. As amostras processadas apresentaram um aumento de 31% de positividade (57 amostras) em relação à microscopia direta convencional. Na análise dos métodos avaliados, todos os resultados foram estatisticamente significativos, comprovando que não eram positivos ou negativos aleatoriamente e confirmando que há uma tendência para esses resultados. CONCLUSÃO: O tratamento químico e a sedimentação espontânea das amostras de escarro representam uma ferramenta diagnóstica eficaz nas situações em que tecnologias mais avançadas não são viáveis. Além da maior precisão e maior detecção de casos positivos em relação ao esfregaço direto, o procedimento reforça a biossegurança, diminuindo os riscos de contaminação aérea por Mycobacterium tuberculosis para profissionais de laboratório

Surviving Reactive Chlorine Stress: Responses of Gram-Negative Bacteria to Hypochlorous Acid.

Sodium hypochlorite (NaOCl) and its active ingredient, hypochlorous acid (HOCl), are the most commonly used chlorine-based disinfectants. HOCl is a fast-acting and potent antimicrobial agent that interacts with several biomolecules, such as sulfur-containing amino acids, lipids, nucleic acids, and membrane components, causing severe cellular damage. It is also produced by the immune system as a first-line of defense against invading pathogens. In this review, we summarize the adaptive responses of Gram-negative bacteria to HOCl-induced stress and highlight the role of chaperone holdases (Hsp33, RidA, Cnox, and polyP) as an immediate response to HOCl stress. We also describe the three identified transcriptional regulators (HypT, RclR, and NemR) that specifically respond to HOCl. Besides the activation of chaperones and transcriptional regulators, the formation of biofilms has been described as an important adaptive response to several stressors, including HOCl. Although the knowledge on the molecular mechanisms involved in HOCl biofilm stimulation is limited, studies have shown that HOCl induces the formation of biofilms by causing conformational changes in membrane properties, overproducing the extracellular polymeric substance (EPS) matrix, and increasing the intracellular concentration of cyclic-di-GMP. In addition, acquisition and expression of antibiotic resistance genes, secretion of virulence factors and induction of the viable but nonculturable (VBNC) state has also been described as an adaptive response to HOCl. In general, the knowledge of how bacteria respond to HOCl stress has increased over time; however, the molecular mechanisms involved in this stress response is still in its infancy. A better understanding of these mechanisms could help understand host-pathogen interactions and target specific genes and molecules to control bacterial spread and colonization.

How Exciton and Single Carriers Block the Excitonic Transition in Two-Dimensional Cadmium Chalcogenide Nanoplatelets.

Cadmium chalcogenide nanoplatelets (NPLs) possess unique properties and have shown great potential in lasing, light-emitting diodes, and photocatalytic applications. However, the exact natures of the band-edge exciton and single carrier (electron and hole) states remain unclear, even though they affect the key properties and applications of these materials. Herein, we study the contribution of a single carrier (electron or hole) state to phase space filling of single exciton states of cadmium chalcogenide NPLs. With pump fluence dependent TA study and selective electron removal, we determine that a single electron and hole states contribute 85% and 12%, respectively, to the blocking of the excitonic transition in CdSe/ZnS core/shell NPLs. These observations can be rationalized by a model of band-edge exciton and single carrier states of 2D NPLs that differs significantly from that of quantum dots.

Visualization of the Retina in Intact Eyes of Mice and Ferrets Using a Tissue Clearing Method.

Purpose: Visualization of specific cells and structures in intact organs would greatly facilitate our knowledge about pathological changes; therefore, a tissue clearing method applicable to the intact eye may be valuable. Here we report a novel imaging method for the retina using the hyperhydration-based tissue clearing technique CUBIC (Clear, Unobstructed Brain/Body Imaging Cocktails and Computational Analysis). Methods: Eyes of Institute of Cancer Research (ICR) mice, C57BL/6 mice, and normally pigmented sable ferrets (Mustela putorius furo) were used. Intact eyes were subjected to CUBIC, melanin bleaching with H2O2, and immunostaining. Images of the retina in intact eyes were taken using epifluorescence microscopes and confocal microscopes. Results: The combination of melanin bleaching and CUBIC efficiently made the eyes of C57BL/6 mice transparent. By combining melanin bleaching, CUBIC, and immunostaining, we succeeded in visualization of retinal structures from the outside of the intact eyes of mice. Furthermore, we found that our methods were applicable not only to mouse eyes but also to ferret eyes, which are much larger than those of mice. Conclusions: Our method was useful for visualizing specific cells and structures in the retina of intact eyes with single-cell resolution without making tissue sections. Translational Relevance: This simple and efficient method can be applicable to various rodent models, including those associated with glaucoma or myopia, and will facilitate evaluating the effects of novel therapy for relevant eye diseases by visualizing changes from the retina to the sclera at both molecular and macroscopic levels simultaneously in a whole-eye preparation.

Pigmented lateral periodontal cyst: A case report and review of pigmented odontogenic cysts.

Pigmented odontogenic cysts are uncommon and to date, only 37 cases have been reported in the English literature. Here, we report a case of a pigmented lateral periodontal cyst (LPC) in the maxilla of a 48-year-old female. The patient presented with clinical swelling in the maxillary anterior region. Microscopic features of the biopsied specimen were consistent with a diagnosis of LPC. The epithelial cyst lining exhibited numerous coarse granules of melanin pigment, which was confirmed by S-100 immunohistochemistry and Fontana-Masson bleach histochemical method. Almost all documented cases of pigmented odontogenic cysts have occurred in Asians and African-Americans, with only three cases in white patients. Racial pigmentation may have a role in the pathogenesis of these lesions. Although the origin and pathologic significance of melanocytes in these pigmented intraosseous lesions cannot be explained, it may be something to consider for investigation in future.

Stress-induced chaperones: a first line of defense against the powerful oxidant hypochlorous acid.

Hypochlorous acid (HOCl; bleach) is a powerful weapon used by our immune system to eliminate invading bacteria. Yet the way HOCl actually kills bacteria and how they defend themselves from its oxidative action have only started to be uncovered. As this molecule induces both protein oxidation and aggregation, bacteria need concerted efforts of chaperones and antioxidants to maintain proteostasis during stress. Recent advances in the field identified several stress-activated chaperones, like Hsp33, RidA, and CnoX, which display unique structural features and play a central role in protecting the bacterial proteome during HOCl stress.