Nanomaterials induce DNA-protein crosslink and DNA oxidation: A mechanistic study with RTG-2 fish cell line and Comet assay modifications.

Genotoxic effects of nanomaterials (NMs) have been controversially reported in literature, and the mode of action (MoA) via DNA oxidation is cited as the main damage caused by them. Evidence of nano-silver as a crosslinker has been previously reported by the present research team in an in vivo fish genotoxicity study. Thus, aiming to confirm the evidence about NMs as crosslinker agent, the present investigation elucidated the genotoxic potential of NMs and their genotoxic MoA through in vitro assay with RTG-2 cells line (rainbow trout gonadal) by exposure to nano-silver (PVP-coated) and nano-titanium. The types and levels of DNA damage were assessed by the Comet assay (standard alkaline, hOGG1-modified alkaline, and two crosslink-modified alkaline versions). It was demonstrated that the use of the standard alkaline Comet assay alone may inaccurately predict the genotoxicity of NMs since oxidative and crosslink DNA damages were also verified in RTG-2 cells when assessed by the modified versions of the alkaline protocol. More importantly, it was confirmed that both nano-silver and nano-titanium acted as DNA-protein crosslinkers through the Comet assay version with proteinase K. As both nano-silver and nano-titanium present a great risk to aquatic life, these findings reinforce the need of genotoxicity testing strategies that encompass the assessment of different types of DNA damage, in order to ensure an accurate prediction of the genotoxic potential of NMs.

Plasma butyrylcholinesterase activity: a possible biomarker for differential diagnosis between Alzheimer's disease and dementia with Lewy bodies?

Butyrylcholinesterase (BChE) is an enzyme encoded by BCHE gene, responsible for secondary hydrolysis of the acetylcholine. K and -116A BCHE variants were associated with decrease in plasma BChE activity, and their influence has been investigated in diseases with a cholinergic deficit such as Alzheimer's disease (AD) and dementia with Lewy bodies (DLB). In order to check the influence of BCHE genetic variants on enzymatic activity, all patients and controls were genotyped for K and -116A variants. We found lower plasma BChE activity in DLB patients compared to elderly controls and to AD independent of the presence of K or -116A variants. Our results suggest that the reduction of total plasma BChE activity is probably associated with a feedback mechanism and provides a future perspective of using this enzyme as a possible plasmatic marker for differential diagnosis between AD and DLB.

Butyrylcholinesterase: K variant, plasma activity, molecular forms and rivastigmine treatment in Alzheimer's disease in a Southern Brazilian population.

Alzheimer's disease (AD) is a neurodegenerative disorder in which there is a decline of cholinergic function. The symptomatic AD treatment involves the use of ChEIs (cholinesterase inhibitors) as rivastigimine, a dual inhibitor. The human butyrylcholinesterase (BChE) is an enzyme that has specific roles in cholinergic neurotransmission and it has been associated with AD. In the serum, BChE is found in four main molecular forms: G1 (monomer); G1-ALB (monomer linked to albumin); G2 (dimer); and G4 (tetramer). The interaction between the products of BCHE gene and CHE2 locus results in CHE2 C5+ and CHE2 C5- phenotypes. CHE2 C5+ phenotype and BChE-K are factors that influence on BChE activity. This work aimed to verify the proportions of BChE molecular forms, total and relative activity in 139 AD patients and 139 elderly controls, taking into account K variant, CHE2 locus, rivastigmine treatment and clinical dementia rating (CDR) of AD patients. Phenotypic frequencies of CHE2 C5+ and frequency of the carriers of the K allele were similar between groups. Total BChE activity in plasma was significantly lower in AD patients than in elderly controls. Furthermore, we found that reduction on plasma BChE activity is associated directly with AD progression in AD patients and that rivastigmine treatment has a stronger effect on BChE activity within the CDR2 group. The reduction in BChE activity did not occur proportionally in all molecular forms. Multiple regression analysis results confirmed that AD acts as the main factor in plasma BChE activity reduction and that severe stages are related with an even greater reduction. These findings suggest that the reduction of total plasma BChE and relative BChE molecular forms activity in AD patients is probably associated with a feedback mechanism and provides a future perspective of using this enzyme as a possible plasmatic secondary marker for AD.

Utilización de verde de indocianina fluorescente intraoperatorio en cirugía biliar: Factibilidad del método: experiencia inicial

Introducción: El verde de indocianina es un colorante hidrofílico que une a la albúmina y tiene propiedades fluorescentes al ser excitado con luz de 780 nm (infrarrojo cercano) y captado con un filtro de longitud de onda de 830 nm. Es excretado exclusivamente por vía biliar, lo que lo haría apto como método colangiográfico. Objetivo: Evaluar la factibilidad de la utilización del verde de indocianina como colorante fluorescente para la visualización del hígado y la vía biliar mediante la estimulación con infrarrojo cercano. Lugar de aplicación: Centro de Cirugía Experimental Hospital de Clínicas José de San Martín. Diseño: Estudio prospectivo, descriptivo, experimental. Población: 10 ratas Wistar de laboratorio, de 350 gramos. Método: Se realizó anestesia de los de los ejemplares con ketamina xylasina intraperitoneal. Se llevó a cabo una inguinotomía, disección de vena ilíaca e inyección endovenosa del contraste verde de indocianina. Posteriormente se procedió con una laparotomía. Durante la cirugía se evaluó la anatomía del hígado y vía biliar intercalando la exposición del campo con luz de xenón blanca e infrarroja. Resultados: Al evaluar el campo operatorio se observó con luz de xenón el hígado y el duodeno de los ejemplares, no pudiendo identificarse claramente en ningún caso la vía biliar. Cuando se utilizó posteriormente el prototipo de óptica y cámara con visión infrarroja con el filtro de 830 nm, se visualizaron en todos los casos la vía biliar en toda su extensión extra hepática y el duodeno de color azul fluorescente. Las estructuras vasculares del hilio hepático, tanto vena porta como arteria hepática, se visualizaron como estructuras tubulares de color negro. Conclusión: La exposición del verde de indocianina a luz infrarroja de 780 nanómetros genera una proyección fluorescente de color azul insensible a la visión humana pero sensible a un filtro de 830 nanómetros. Al ser inyectado por vía endovenosa y tener excreción exclusivamente por vía biliar, permite la visualización anatómica hepatobiliar de manera fluorescente.

Introduction: Indocyanine green dye is hydrophilic due to albumin binding. The dye has fluorescent properties when excited with light of 780 nm (near infrared) and captured with a filter wavelength of 830 nm. It is excreted exclusively via the bile, which would make it suitable as cholangiographic method. Objective: To evaluate the feasibility of using indocyanine green as fluorescent dye for visualization of the liver and bile ducts by near-infrared stimulation. Application: Experimental Surgery Center University Hospital de Clínicas José de San Martín. Design: Prospective, descriptive, experimental. Population: 10 wistar rats of 350 grams laboratory. Method: Anesthesia with ketamine intraperitoneal xylasina. Then performed an inguinotomy, iliac vein dissec-tion intravenous injection of indocyanine green contrast and then we proceeded with a laparotomy. During surgery we evaluated the anatomy of the liver and bile duct field exposure alternating with white xenon light and infrared. Results: In evaluating the operative field with xenon light was observed the liver and duodenum of the rats but could not be clearly identified in any case, the bile duct. When we used optical and infrared vision camera with 830 nm filter were visualized in all cases the bile duct in its entirety and duodenum extrahepatic fluorescent blue color. The hepatic vascular structures of the hilium, both hepatic artery and portal vein, were visualized as tubular structures in black color. Conclusion: Exposure of indocyanine green to infrared light of 780 nm generates a blue fluorescent projection insensitive to human vision but sensitive to 830 nanometer filter. When injected intravenously and with its exclusively biliary excretion, allows viewing on a fluorescent hepatobiliary anatomy.