Application of Processing Guidance: Case Study of Cleaning Validations on Flexible Endoscopes.

In 2015, the Food and Drug Administration (FDA) updated its guidance on test methods for cleaning validations for reusable medical devices. The changes include the condition and contamination of devices, test samples and controls, cleaning process performed during validation, extraction methods, and endpoints. This article reviews the FDA's changes to cleaning validations. Examples are presented using flexible endoscopes in order to provide a practical guide to performing cleaning validations.

Dimensionality-Driven Photoproduction of Massive Dirac Pairs near Threshold in Gapped Graphene Monolayers.

Generation of quasiparticle-hole pairs in gapped graphene monolayers in the combined field of two counterpropagating light waves is studied. The process represents an analog of electron-positron pair production from the vacuum of quantum electrodynamics (QED) by the Breit-Wheeler effect. We show, however, that the two-dimensional structure of graphene causes some striking differences between both scenarios. In particular, contrary to the QED case, it allows for nonzero pair production rates at the energy threshold when the Breit-Wheeler reaction proceeds nonlinearly with absorption of three photons.

Nanocarrier-based systems for wound healing.

In general, the systems intended for the treatment and recovery of wounds, seek to act as a coating for the damaged area, maintaining an adequate level of humidity, reducing pain, and preventing the invasion and proliferation of microorganisms. Although many of the systems that are currently on the market meet the purposes mentioned above, with the arrival of nanotechnology, it has sought to improve the performance of these coatings. The variety of nano-systems that have been proposed is very extensive, including the use of very different materials (natural or synthetic) ranging from polymers or lipids to systems derived from microorganisms. With the objective of improving the performance of the systems, seeking to combat several of the problems that arise in a wound, especially when it is chronic, these materials have been combined, giving rise to nanocomposites or scaffolds. In recent years, the interest in the development of systems for the treatment of wounds is notable, which is reflected in the increase in publications related to the subject. Therefore, this document presents generalities of systems involving nanocarriers, mentioning some examples of representative systems of each case.

Bilateral symmetry of breast tissue composition by magnetic resonance in young women and adults.

BACKGROUND: Some reports suggest that there is a slightly higher frequency of breast cancer in the left breast compared with the right in middle-aged women. The reasons for this association are unknown. The water and fat content of both breasts was compared using magnetic resonance (MR). Breast water by MR reflects fibro-glandular tissue and is strongly positively correlated with percent mammographic density, a strong risk factor for breast cancer. METHODS: Magnetic resonance was used to measure fat and water content of the breast in 400 young women aged 15-30 years and a random sample of 100 of their mothers. All MR examinations were carried out using a 1.5T MR system, and 45 contiguous slices were obtained in the sagittal plane. One reader identified the breast tissue in the image, and subsequently, fat and water content was calculated using a three-point Dixon technique. Left- and right-sided images were read independently in random order. RESULTS: In young women, mean percent water was on average 0.84 % higher in the right compared with the left breast (p < 0.001) and total breast water was on average 6.42 cm(3) greater on the right side (p < 0.001). In mothers, there were no significant differences in any breast measure between right and left sides. CONCLUSION: The small differences in breast tissue composition in young women are unlikely to be associated with large differences in breast cancer risk between sides. The reported excess of left-sided breast cancer in older women is unlikely to be explained by differences in breast tissue composition.

Graph-based symbolic technique and its application in the frequency response bound analysis of analog integrated circuits.

A new graph-based symbolic technique (GBST) for deriving exact analytical expressions like the transfer function H(s) of an analog integrated circuit (IC), is introduced herein. The derived H(s) of a given analog IC is used to compute the frequency response bounds (maximum and minimum) associated to the magnitude and phase of H(s), subject to some ranges of process variational parameters, and by performing nonlinear constrained optimization. Our simulations demonstrate the usefulness of the new GBST for deriving the exact symbolic expression for H(s), and the last section highlights the good agreement between the frequency response bounds computed by our variational analysis approach versus traditional Monte Carlo simulations. As a conclusion, performing variational analysis using our proposed GBST for computing the frequency response bounds of analog ICs, shows a gain in computing time of 100x for a differential circuit topology and 50x for a 3-stage amplifier, compared to traditional Monte Carlo simulations.

Application of Raman spectroscopy for the determination of proteins denaturation and amino acids decomposition temperature.

Raman spectroscopy was employed to study the thermal denaturation of three different proteins, bovine serum albumin (BSA), lysozyme, ovalbumin; and the decomposition temperature of three amino acids, l-glutamine, l-cysteine, and l-alanine, all of them as lyophilized powders. All the Raman bands observed in the spectra obtained were recorded and analyzed at preset heating temperatures. The results obtained for either protein denaturation temperature TD and amino acid decomposition temperatures TM-dc, were compared with those measured by differential scanning calorimetry (DSC). The DSC and Raman results were additionally corroborated with a thermogravimetric analysis (TGA) for the case of proteins. This exercise indicated almost complete coincidence in the determination of these transition temperatures between the three techniques, evidencing the applicability of Raman spectroscopy in the study of denaturation and decomposition temperatures of proteins and amino acids.

[Midazolam versus dexmedetomidine for sedation for upper gastrointestinal endoscopy]. / Midazolam versus dexmedetomidina en sedación para procedimientos endoscópicos de tubo digestivo alto.

BACKGROUND: The diagnostic upper gastrointestinal endoscopy (UGI) is a safe procedure although 50% to 60% morbidity and mortality due to cardiopulmonary complications. OBJECTIVE: To compare safety and efficacy of dexmedetomidine vs. midazolam in UGI. METHODS: We conducted a randomized controlled, double-blind, clinical trial to compare the two drugs. Patients with an indication of UGI were randomized to receive sedation with dexmedetomidine or midazolam during the procedure. We compared age, sex, physical status (ASA), body mass index (BMI), degree of sedation (Ramsay scale), recovery time and degree of satisfaction with the procedure. RESULTS: Forty patients with an indication of UGI were included (20 in each arm). Both groups showed a similar distribution by sex, age, BMI and ASA physical status. The level of sedation was similar starting and ending the procedure according to the Ramsay scale. The dexmedetomidine group had a shorter recovery time (7.1 vs. 15.8 min, p <0.05) and satisfaction (9.9 vs. 9.0, p <0.05). Adverse effects occurred in similar proportions in both groups. CONCLUSIONS: Midazolam and dexmedetomidine are suitable for endoscopic procedures of upper digestive tract. Dexmedetomidine offers shorter recovery time and better patient's satisfaction.

New rabies virus variant found during an epizootic in white-nosed coatis from the Yucatan Peninsula.

In February 2008, three white-nosed coatis (Nasua narica) were found dead in a recreational park in Cancun, Mexico. The diagnosis of rabies virus (RABV) infection was confirmed by direct immunofluorescence test. The phylogenetic analysis performed with the complete RABV nucleoprotein gene positioned this isolate close to a sequence of a human rabies case reported during 2008 from Oaxaca, Mexico, sharing 93% similarity. In turn, these two variants are related to another variant found in rabid Tadarida brasiliensis mexicana bats across North America. Anti-RABV neutralizing activity (1.3 IU/ml) was found in the serum of one white-nosed coati captured with another five that cohabited with the dead animals. Enhanced rabies surveillance and pathogenesis studies should be conducted in coatis and insectivorous bats of the region to clarify the role of these species as potential emergent or long-term unidentified RABV reservoirs.

Robust correction of spike noise: application to diffusion tensor imaging.

Echo-planar imaging (EPI) -based diffusion tensor imaging (DTI) is particularly prone to spike noise. However, existing spike noise correction methods are impractical for corrupted DTI data because the methods correct the complex MRI signal, which is not usually stored on clinical MRI systems. The present work describes a novel Outlier Detection De-spiking technique (ODD) that consists of three steps: detection, localization, and correction. Using automated outlier detection schemes, ODD exploits the data redundancy available in DTI data sets that are acquired with a minimum of six different diffusion-weighted images (DWIs) with similar signal and noise properties. A mathematical formulation, describing the effects of spike noise on magnitude images, yields appropriate measures for an outlier detection scheme used for spike detection while a normalization-dependent outlier detection scheme is used for spike localization. ODD performs accurately on diverse DTI data sets corrupted by spike noise and can be used for automated control of DTI data quality. ODD can also be extended to other MRI applications with data redundancy, such as dynamic imaging and functional MRI.

Evaluation of the effect of 1,3-bis-(4-phenyl-[1,2,3] triazole-1-il)2-propanol in comparison with metronidazole in an in vitro culture of Blastocystis in samples of patients with irritable bowel syndrome.

Metronidazole is the most-used pharmaceutical for the treatment of infection by Blastocystis. However, studies have reported resistance of the microorganism towards this pharmaceutical. In Mexico, studies concerning the prevalence of this parasite and its relationship to Irritable Bowel Syndrome have been carried out. To evaluate the in vitro effect of metronidazole and the compound 1,3-bis-(4-phenyl-[1,2,3] triazole-1-il)2-propanol over Blastocystis, as well as the prevalence of Blastocystis in patients with Irritable Bowel Syndrome. A prospective, transversal design study (April 2016-April 2017) of 51 samples of patients with Irritable Bowel Syndrome, obtained from the ISSEMyM Medical Center in Toluca, Mexico. For the identification of Blastocystis was done in three serial stool samples through direct microscopic examination and the Ritchie technique. The in vitro susceptibility test towards metronidazole and the triazolic compound was done through a microculture in concentrations of 1 to 1000 µg/mL, each one in triplicate. A 31.3% prevalence of Blastocystis was observed in the population, with greater prevalence in women (30.2%) than in men (25%). In the susceptibility test, a CL50 of 64 µg/mL was obtained for metronidazole, in comparison to the CL50 of 250 µg/mL for 1,3-bis-(4-phenyl-[1,2,3] triazole-1-il)2-propanol. This molecule in development has an effect for the treatment of infection by Blastocystis in vitro in patients with IBS and therefore, more studies should be performed.

Caracterización de la mortalidad por fractura de cadera como causa básica en el periodo 2017-2022 en Chile / Characterization of mortality due to hip fracture as the underlying cause in the period 2017-2022 in Chile

Introducción: La fractura de cadera (FC) es una solución de continuidad en el extremo proximal del fémur, con consecuencias significativas para quien la padece. Este estudio busca comparar descriptivamente la tasa de mortalidad por FC en el periodo 2017-2022, en Chile. Metodología: Estudio descriptivo observacional sobre defunciones por FC entre 2017 y 2022, en Chile (n= 3.190), según datos del Departamento de Estadísticas e Información de Salud de Chile. Se calcularon tasas de mortalidad por FC por variable, índice de sobremortalidad e índice de Swaroop, utilizando datos del Censo 2017. No requirió comité de ética. Resultados: La mayor tasa de mortalidad por FC se observó en el año 2018 (3,23), en el grupo de 100 años y más (2.264,15), la región de Valparaíso (28,31) y el sexo femenino (4,32) reflejandose en su índice de sobremortalidad (2,589). La menor tasa de mortalidad por FC ocurrió en el año 2021 (2,76), en el grupo de entre 0 y 19 años (0,04) y en la región de Atacama (12,58). El índice de Swaroop fue 100% en la mayoría de las regiones. Discusión: La tendencia a la baja desde el año 2019 podría explicarse por el confinamiento por COVID-19 que limitó la movilidad de las personas mayores. Los cambios postmenopausicos y un mayor riesgo de caídas podrían explicar una mayor tasa de mortalidad por FC en mujeres y pacientes de edad avanzada, respectivamente. El análisis por región podría relacionarse con la proporción demográfica de personas mayores.

Introduction: The hip fracture (HF) is a discontinuity in the proximal end of the femur, with significant consequences for those who suffer from it. This study aims to descriptively compare the HF mortality rate in the period 2017-2022 in Chile. Methodology: This is an observational descriptive study on deaths due to HF between 2017 and 2022 in Chile (n=3,190), according to data from the Department of Statistics and Health Information of Chile. HF mortality was calculated by variable, excess mortality rate, and Swaroop index, using data from the 2017 Census. No ethics committee was required. Results: The highest HF mortality rate was in 2018 (3,23), in the age group of 100 years and older (2.264,15), the Valparaíso region (28,31) and the female sex (4,32) reflected in its excess mortality rate (2,589). The lowest HF mortality rate occurred in 2021 (2,76), in the group between 0 and 19 years (0,04) and in the Atacama region (12,58). The Swaroop index was 100% in most regions. Discussion: The downward trend since 2019 could be explained by the COVID-19 lockdown that limited the mobility of elderly adults. Postmenopausal changes and a higher risk of falls could explain higher HF mortality rate in women and old people patients, respectively. The regional analysis could be related to the demographic proportion of elder people.

Hpr1 is preferentially required for transcription of either long or G+C-rich DNA sequences in Saccharomyces cerevisiae.

Hpr1 forms, together with Tho2, Mft1, and Thp2, the THO complex, which controls transcription elongation and genome stability in Saccharomyces cerevisiae. Mutations in genes encoding the THO complex confer strong transcription-impairment and hyperrecombination phenotypes in the bacterial lacZ gene. In this work we demonstrate that Hpr1 is a factor required for transcription of long as well as G+C-rich DNA sequences. Using different lacZ segments fused to the GAL1 promoter, we show that the negative effect of lacZ sequences on transcription depends on their distance from the promoter. In parallel, we show that transcription of either a long LYS2 fragment or the S. cerevisiae YAT1 G+C-rich open reading frame fused to the GAL1 promoter is severely impaired in hpr1 mutants, whereas transcription of LAC4, the Kluyveromyces lactis ortholog of lacZ but with a lower G+C content, is only slightly affected. The hyperrecombination behavior of the DNA sequences studied is consistent with the transcriptional defects observed in hpr1 cells. These results indicate that both length and G+C content are important elements influencing transcription in vivo. We discuss their relevance for the understanding of the functional role of Hpr1 and, by extension, the THO complex.

Constitutive repression and nuclear factor I-dependent hormone activation of the mouse mammary tumor virus promoter in Saccharomyces cerevisiae.

To study the influence of various transactivators and the role of nucleosomal structure in gene regulation by steroid hormones, we have introduced mouse mammary tumor virus (MMTV) promoter sequences along with expression vectors for the glucocorticoid receptor (GR) and nuclear factor I (NFI) in Saccharomyces cerevisiae, an organism amenable to genetic manipulation. Both in the context of an episomal multicopy vector and in a centromeric single-copy plasmid, the MMTV promoter was virtually silent in the absence of inducer, even in yeast strains expressing GR and NFI. Induction was optimal with deacylcortivazol and required both GR and NFI. The transactivation function AF1 in the N-terminal half of GR is required for ligand-dependent induction and acts constitutively in truncated GR lacking the ligand binding domain. A piece of the MMTV long terminal repeat extending from -236 to +111 is sufficient to position a nucleosome, B, over the regulatory region of the promoter from -45 to -190 and another nucleosome over the transcription start region. The rotational orientation of the DNA on the surface of nucleosome B is the same as that previously found in animal cells and in reconstitution experiments. This orientation is compatible with binding of GR to two sites, while it should preclude binding of NFI and hence be responsible for constitutive repression. Upon ligand induction, there is no major chromatin rearrangement, but the proximal linker DNA, including the TATA box, becomes hypersensitive to nucleases. The transcriptional behavior of the MMTV promoter was unaffected by deletions of the genes for zuotin or SIN1/SPT2, two proteins which have been claimed to assume some of the functions of linker histones. Thus, despite the lack of histone H1, yeast cells could be a suitable system to study the contribution of nucleosomal organization to the regulated expression of the MMTV promoter.

Trophoblast differentiation: progenitor cells, fusion and migration -- a workshop report.

Challenge lies ahead in unravelling the role played by trophoblast and its repertoire of expressed genes in normal human placental development, growth and pathology. Specific technical advances will clearly be required for characterisation of function. In particular, improvements in our repertoire of in vitro models are needed before many of the key questions can be answered. Recent advances in the study of human trophoblast differentiation are discussed.

Straightforward production of encoded microbeads by Flow Focusing: potential applications for biomolecule detection.

Fluorescently encoded polymeric microparticles are acquiring great importance in the development of simultaneous multianalyte screening assays. We have developed a very versatile and straightforward method for the production of dye-labeled microparticles with a very reproducible size distribution and freely-chosen and discernible fluorescent properties. Our method combines Flow Focusing technology with a solvent evaporation/extraction procedure in a single step, yielding spherical, non-aggregate and non-porous particles. We have designed a multi-coloured bead array which includes the possibility of modifying the surface properties of the microparticles, which offer excellent properties for covalent attachment of biomolecules such as peptides, oligonucleotides, proteins, etc. We also show the potential of the fluorescently labeled microspheres for the detection of biomolecule (peptides and oligonucelotides) interactions using flow cytometry.

The yeast HRS1 gene is involved in positive and negative regulation of transcription and shows genetic characteristics similar to SIN4 and GAL11.

We provide genetic evidence that HRS1/PGD1, a yeast gene previously identified as a suppressor of the hyper-recombination phenotype of hpr1, has positive and negative roles in transcriptional regulation. We have analyzed three differently regulated promoters, GAL1, PHO5 and HSP26, by beta-galactosidase assays of lacZ-fused promoters and by Northern analysis of the endogenous genes. Transcription of these promoters was derepressed in hrs1delta mutants under conditions in which it is normally repressed in wild type. Under induced conditions it was either strongly reduced or significantly enhanced depending on the promoter system analyzed. Constitutive transcription was not affected, as determined in ADH1 and TEF2. In addition, Hrs1p was required for mating-factor expression, telomere-linked DNA silencing and DNA supercoiling of plasmids. Furthermore, hrs1delta suppressed Ty-insertion mutations and conferred a Gal- phenotype. Many of these phenotypes also result from mutations in GAL11, SIN4 or RGR1, which encode proteins of the RNA polII mediator. We also show that gal11delta and sin4delta partially suppress the hyper-rec phenotype of hpr1 mutants, although to a lesser extent than hrs1delta. Our results provide new evidence for the connection between hpr1delta-induced deletions and transcription. We discuss the possibility that Hrs1p might be a component of the RNA polII transcription machinery.

Point mutation in the ligand-binding domain of the progesterone receptor generates a transdominant negative phenotype.

A short conserved alpha-helix in the carboxyl-terminal activation function of the ligand-binding domain of steroid hormone receptors, called AF2, is important for ligand-dependent transactivation of inducible genes. We have generated two AF2 mutants of the B isoform of human progesterone receptor (PRB): a point mutant, PRBE911A, and a short deletion, PRB delta907-913R. The two mutants are expressed at levels comparable to the wild type receptor in transfected cells. The PRBE911A mutant showed similar hormone- and DNA- binding affinities as the wild type receptor, whereas the PRB delta907-913R mutant was defective in hormone and DNA binding. Both mutants were inactive when transiently transfected in CV-1 cells, which do not express endogenous PR. However, the point mutant, but not the deletion mutant, inhibited transactivation by cotransfected wild type PRB in a hormone-dependent fashion. The activity of endogenous PR in T47D cells or of endogenous glucocorticoid receptor in HeLa cells was also inhibited by the PRBE911A, but not by the deletion mutant. The point mutant was less active when introduced into an N-terminal truncated form of PR, where it gave rise to proteins that formed homodimers with poor affinity for DNA, but were able to form heterodimers with PRB. The negative dominant phenotype of the PRBE911A mutant likely originates from competition with wild type receptors for binding to DNA and will be useful for mechanistic studies of receptor function.

Tumores fibroóseos de cavidades paranasales: experiencia en el Hospital Clínico de la Universidad de Chile y revisión de la literatura / Fibro-osseous tumors of paranasal cavities: experience in the Hospital Clínico de la Universidad de Chile and review of the literature

Los tumores de cavidades paranasales presentan una baja frecuencia. Dentro de éstos, entre los benignos destacan las lesiones fibroóseas que se caracterizan por el reemplazo de hueso normal por estroma celular fibroso. Dentro de estas lesiones se describen osteoma, displasia fibrosa y fibroma osificante. Se revisan 3 casos de pacientes del Hospital Clínico de la Universidad de Chile y se presenta una revisión bibliográfica en cuanto a las lesiones fibroóseas, su clínica, diagnóstico, imagenología y tratamiento.

The tumors of paranasal cavities present a low frequency. Among the benign tumors are fibro-osseous lesions characterized by the replacement of normal bone by fibrous cell stroma. Osteoma, fibrous dysplasia, and ossifying fibroma are described within these lesions. Three cases of patients from the Hospital Clínico de la Universidad de Chile are reviewed and a bibliographic review is presented regarding the fibro-osseous lesions, their clinical features, diagnosis, imaging and treatment.

An NAD-specific glutamate dehydrogenase from cyanobacteria. Identification and properties.

The unicellular cyanobacterium Synechocystis sp. PCC 6803 presents a hexameric NAD-specific glutamate dehydrogenase with a molecular mass of 295 kDa. The enzyme differs from the NADP-glutamate dehydrogenase found in the same strain and is coded by a different gene. NAD-glutamate dehydrogenase shows a high coenzyme specificity, catalyzes preferentially glutamate formation and presents Km values for ammonium, NADH and 2-oxoglutarate of 4.5 mM, 50 microM and 1.8 mM respectively. An animating role for the enzyme is discussed.

Cloning and correct expression in E. coli of the petJ gene encoding cytochrome c6 from Synechocystis 6803.

Cytochrome c6 from the cyanobacterium Synechocystis 6803 has been isolated and purified to electrophoretic homogeneity. The gene coding for such a heme protein (petJ) has been cloned and properly expressed in E. coli. This procedure yields a protein preparation completely identical to that obtained from the cyanobacterial cells. The N-terminal amino acid sequences of cytochrome c6 synthesized in both organisms are the same, thus allowing us to conclude that the petJ gene product is correctly processed in E. coli. To the best of our knowledge, this is the first time that any cytochrome c6 is produced in the enterobacterium. The identical physicochemical and kinetic properties of the proteins isolated from both sources confirm that expression of the petJ gene in E. coli is an adequate tool to address the study of Synechocystis cytochrome c6 by site-directed mutagenesis in a parallel way to that carried out with plastocyanin from the same organism.