CERKL, a Retinal Dystrophy Gene, Regulates Mitochondrial Transport and Dynamics in Hippocampal Neurons.

Mutations in the Ceramide Kinase-like (CERKL) gene cause retinal dystrophies, characterized by progressive degeneration of retinal neurons, which eventually lead to vision loss. Among other functions, CERKL is involved in the regulation of autophagy, mitochondrial dynamics, and metabolism in the retina. However, CERKL is nearly ubiquitously expressed, and it has been recently described to play a protective role against brain injury. Here we show that Cerkl is expressed in the hippocampus, and we use mouse hippocampal neurons to explore the impact of either overexpression or depletion of CERKL on mitochondrial trafficking and dynamics along axons. We describe that a pool of CERKL localizes at mitochondria in hippocampal axons. Importantly, the depletion of CERKL in the CerklKD/KO mouse model is associated with changes in the expression of fusion/fission molecular regulators, induces mitochondrial fragmentation, and impairs axonal mitochondrial trafficking. Our findings highlight the role of CERKL, a retinal dystrophy gene, in the regulation of mitochondrial health and homeostasis in central nervous system anatomic structures other than the retina.

CERKL, a retinal dystrophy gene, regulates mitochondrial function and dynamics in the mammalian retina.

The retina is a highly active metabolic organ that displays a particular vulnerability to genetic and environmental factors causing stress and homeostatic imbalance. Mitochondria constitute a bioenergetic hub that coordinates stress response and cellular homeostasis, therefore structural and functional regulation of the mitochondrial dynamic network is essential for the mammalian retina. CERKL (ceramide kinase like) is a retinal degeneration gene whose mutations cause Retinitis Pigmentosa in humans, a visual disorder characterized by photoreceptors neurodegeneration and progressive vision loss. CERKL produces multiple isoforms with a dynamic subcellular localization. Here we show that a pool of CERKL isoforms localizes at mitochondria in mouse retinal ganglion cells. The depletion of CERKL levels in CerklKD/KO(knockdown/knockout) mouse retinas cause increase of autophagy, mitochondrial fragmentation, alteration of mitochondrial distribution, and dysfunction of mitochondrial-dependent bioenergetics and metabolism. Our results support CERKL as a regulator of autophagy and mitochondrial biology in the mammalian retina.

The Alter Retina: Alternative Splicing of Retinal Genes in Health and Disease.

Alternative splicing of mRNA is an essential mechanism to regulate and increase the diversity of the transcriptome and proteome. Alternative splicing frequently occurs in a tissue- or time-specific manner, contributing to differential gene expression between cell types during development. Neural tissues present extremely complex splicing programs and display the highest number of alternative splicing events. As an extension of the central nervous system, the retina constitutes an excellent system to illustrate the high diversity of neural transcripts. The retina expresses retinal specific splicing factors and produces a large number of alternative transcripts, including exclusive tissue-specific exons, which require an exquisite regulation. In fact, a current challenge in the genetic diagnosis of inherited retinal diseases stems from the lack of information regarding alternative splicing of retinal genes, as a considerable percentage of mutations alter splicing or the relative production of alternative transcripts. Modulation of alternative splicing in the retina is also instrumental in the design of novel therapeutic approaches for retinal dystrophies, since it enables precision medicine for specific mutations.

Analysis of the evolution of ultra-filtered water quality in a drinking water distribution system by particle size distribution: Influence of pre-ozonation.

An experimental drinking water distribution system (DWDS) was used to evaluate the evolution of particle size distribution (PSD) and basic quality parameters of ultrafiltered water with or without pre-ozonation. An ultrafiltration (UF) module was set up, associated with a pre-ozonation system (3.7 g O3 /m3 ). The permeate was circulated in the DWDS (300 m; 0.9 m/s) with 0.4 mg/L of chlorine, and the analysis of the PSD was performed using a ß-variable mathematical model. A better control of membrane fouling was obtained with pre-ozonation, and PSD was necessary to observe water quality differences between permeates and in the DWDS. A decrease in particle concentration of 1.8 logarithms was obtained with the application of UF membranes, while a decrease of only 1.2 logarithms was obtained with pre-ozonation. The system without pre-ozonation showed a higher efficiency at removing smaller particles (around 2 µm), with the absence of particles larger than 23 µm during both stages. The PSD revealed a worsening of water quality in the DWDS with an increase of particles smaller than 5 µm during the application of UF membranes, while with pre-ozonation, all particle sizes analyzed increased their concentration. PRACTITIONER POINTS: Pre-ozonation led to a better control of membrane fouling, but a worsening of permeate quality according to particle size distribution. Pre-ozonation does not improve the turbidity, dissolved organic carbon or UV254 removal capacity of ultrafiltration during drinking water treatment. Particles size distribution reveals the deterioration of water quality in a drinking water distribution system better than turbidity or DOC. Ozone prior to ultrafiltration membranes led to a worsening of permeate quality, more significant in the drinking water distribution system.

Exacerbated response to oxidative stress in the Retinitis Pigmentosa CerklKD/KO mouse model triggers retinal degeneration pathways upon acute light stress.

The retina is particularly vulnerable to genetic and environmental alterations that generate oxidative stress and cause cellular damage in photoreceptors and other retinal neurons, eventually leading to cell death. CERKL (CERamide Kinase-Like) mutations cause Retinitis Pigmentosa and Cone-Rod Dystrophy in humans, two disorders characterized by photoreceptor degeneration and progressive vision loss. CERKL is a resilience gene against oxidative stress, and its overexpression protects cells from oxidative stress-induced apoptosis. Besides, CERKL contributes to stress granule-formation and regulates mitochondrial dynamics in the retina. Using the CerklKD/KO albino mouse model, which recapitulates the human disease, we aimed to study the impact of Cerkl knockdown on stress response and activation of photoreceptor death mechanisms upon light/oxidative stress. After acute light injury, we assessed immediate or late retinal stress response, by combining both omic and non-omic approaches. Our results show that Cerkl knockdown increases ROS levels and causes a basal exacerbated stress state in the retina, through alterations in glutathione metabolism and stress granule production, overall compromising an adequate response to additional oxidative damage. As a consequence, several cell death mechanisms are triggered in CerklKD/KO retinas after acute light stress. Our studies indicate that Cerkl gene is a pivotal player in regulating light-challenged retinal homeostasis and shed light on how mutations in CERKL lead to blindness by dysregulation of the basal oxidative stress response in the retina.

Noninvasive early detection of colorectal cancer by hypermethylation of the LINC00473 promoter in plasma cell-free DNA.

BACKGROUND: Current noninvasive assays have limitations in the early detection of colorectal cancer. We evaluated the clinical utility of promoter methylation of the long noncoding RNA LINC00473 as a noninvasive biomarker to detect colorectal cancer and associated precancerous lesions. METHODS: We evaluated the epigenetic regulation of LINC00473 through promoter hypermethylation in colorectal cancer cell lines using bisulfite genomic sequencing and expression analyses. DNA methylation of LINC00473 was analyzed in primary colorectal tumors using 450K arrays and RNA-seq from The Cancer Genome Atlas (TCGA). Tissue-based findings were validated in several independent cohorts of colorectal cancer and advanced colorectal polyp patients by pyrosequencing. We explored the clinical utility of LINC00473 methylation for the early detection of colorectal cancer in plasma cell-free DNA by quantitative methylation-specific PCR and droplet digital PCR. RESULTS: LINC00473 showed transcriptionally silencing due to promoter hypermethylation in colorectal cancer cell lines and primary tumors. Methylation of the LINC00473 promoter accurately detected primary colorectal tumors in two independent clinical cohorts, with areas under the receiver operating characteristic curves (AUCs) of 0.94 and 0.89. This biomarker also identified advanced colorectal polyps from two other tissue-based clinical cohorts with high diagnostic accuracy (AUCs of 0.99 and 0.78). Finally, methylation analysis of the LINC00473 promoter in plasma cell-free DNA accurately identified patients with colorectal cancer and advanced colorectal polyps (AUCs of 0.88 and 0.84, respectively), which was confirmed in an independent cohort of patients. CONCLUSIONS: Hypermethylation of the LINC00473 promoter is a new promising biomarker for noninvasive early detection of colorectal cancer and related precancerous lesions.

Overexpression of CERKL Protects Retinal Pigment Epithelium Mitochondria from Oxidative Stress Effects.

The precise function of CERKL, a Retinitis Pigmentosa (RP) causative gene, is not yet fully understood. There is evidence that CERKL is involved in the regulation of autophagy, stress granules, and mitochondrial metabolism, and it is considered a gene that is resilient against oxidative stress in the retina. Mutations in most RP genes affect photoreceptors, but retinal pigment epithelium (RPE) cells may be also altered. Here, we aimed to analyze the effect of CERKL overexpression and depletion in vivo and in vitro, focusing on the state of the mitochondrial network under oxidative stress conditions. Our work indicates that the depletion of CERKL increases the vulnerability of RPE mitochondria, which show a shorter size and altered shape, particularly upon sodium arsenite treatment. CERKL-depleted cells have dysfunctional mitochondrial respiration particularly upon oxidative stress conditions. The overexpression of two human CERKL isoforms (558 aa and 419 aa), which display different protein domains, shows that a pool of CERKL localizes at mitochondria in RPE cells and that CERKL protects the mitochondrial network-both in size and shape-against oxidative stress. Our results support CERKL being a resilient gene that regulates the mitochondrial network in RPE as in retinal neurons and suggest that RPE cell alteration contributes to particular phenotypic traits in patients carrying CERKL mutations.

A New Cerkl Mouse Model Generated by CRISPR-Cas9 Shows Progressive Retinal Degeneration and Altered Morphological and Electrophysiological Phenotype.

Purpose: Close to 100 genes cause retinitis pigmentosa, a Mendelian rare disease that affects 1 out of 4000 people worldwide. Mutations in the ceramide kinase-like gene (CERKL) are a prevalent cause of autosomal recessive cause retinitis pigmentosa and cone-rod dystrophy, but the functional role of this gene in the retina has yet to be fully determined. We aimed to generate a mouse model that resembles the phenotypic traits of patients carrying CERKL mutations to undertake functional studies and assay therapeutic approaches. Methods: The Cerkl locus has been deleted (around 97 kb of genomic DNA) by gene editing using the CRISPR-Cas9 D10A nickase. Because the deletion of the Cerkl locus is lethal in mice in homozygosis, a double heterozygote mouse model with less than 10% residual Cerkl expression has been generated. The phenotypic alterations of the retina of this new model have been characterized at the morphological and electrophysiological levels. Results: This CerklKD/KO model shows retinal degeneration, with a decreased number of cones and progressive photoreceptor loss, poorly stacked photoreceptor outer segment membranes, defective retinal pigment epithelium phagocytosis, and altered electrophysiological recordings in aged retinas. Conclusions: To our knowledge, this is the first Cerkl mouse model to mimic many of the phenotypic traits, including the slow but progressive retinal degeneration, shown by human patients carrying CERKL mutations. This useful model will provide unprecedented insights into the retinal molecular pathways altered in these patients and will contribute to the design of effective treatments.

Plasma MicroRNA Signature Validation for Early Detection of Colorectal Cancer.

OBJECTIVES: Specific microRNA (miRNA) signatures in biological fluids can facilitate earlier detection of the tumors being then minimally invasive diagnostic biomarkers. Circulating miRNAs have also emerged as promising diagnostic biomarkers for colorectal cancer (CRC) screening. In this study, we investigated the performance of a specific signature of miRNA in plasma samples to design a robust predictive model that can distinguish healthy individuals from those with CRC or advanced adenomas (AA) diseases. METHODS: Case control study of 297 patients from 8 Spanish centers including 100 healthy individuals, 101 diagnosed with AA, and 96 CRC cases. Quantitative real-time reverse transcription was used to quantify a signature of miRNA (miRNA19a, miRNA19b, miRNA15b, miRNA29a, miRNA335, and miRNA18a) in plasma samples. Binary classifiers (Support Vector Machine [SVM] linear, SVM radial, and SVM polynomial) were built for the best predictive model. RESULTS: Area under receiving operating characteristic curve of 0.92 (95% confidence interval 0.871-0.962) was obtained retrieving a model with a sensitivity of 0.85 and specificity of 0.90, positive predictive value of 0.94, and negative predictive value of 0.76 when advanced neoplasms (CRC and AA) were compared with healthy individuals. CONCLUSIONS: We identified and validated a signature of 6 miRNAs (miRNA19a, miRNA19b, miRNA15b, miRNA29a, miRNA335, and miRNA18a) as predictors that can differentiate significantly patients with CRC and AA from those who are healthy. However, large-scale validation studies in asymptomatic screening participants should be conducted.

Validation of miR-1228-3p as Housekeeping for MicroRNA Analysis in Liquid Biopsies from Colorectal Cancer Patients.

BACKGROUND: Circulating microRNA (miRNA) analysis is a growing research field. However, it usually requires an endogenous control or housekeeping (HK) in order to normalize expression of specific miRNAs throughout different samples. Unfortunately, no adequate HK for circulating miRNA analysis is still known in the colorectal cancer (CRC) context whereas several have been suggested. Hence, our aims were to validate the previously suggested miR-1228-3p as HK for CRC studies, to compare its suitability with the widely used miR-16-5p, and to evaluate the influence of hemolysis on both miRNAs. METHODS: We analyzed by quantitative reverse-transcription polymerase chain reaction (qRT-PCR) the expression of miR-1228-3p, miR-16-5p and the spike-in cel-miR-39 in a set of 297 plasmas (92 CRC, 101 advanced adenomas -AA-, and 100 controls) and 213 serum samples (59 CRC, 74 AA and 80 controls). We also analyzed both miRNAs depending on the hemolysis degree in 7 plasmas and 31 serums. RESULTS: Levels of miR-1228-3p and miR-16-5p did not show significant differences between groups although miR-16-5p exhibited more variability in plasma and serum samples. Importantly, the combination of cel-miR-39 and miR-1228-3p was the most stable one. Moreover, we observed that miR-16-5p was significantly influenced by hemolysis in contrast with miR-1228-3p that exhibited no correlation with this confounding factor in both biofluids. CONCLUSION: MiR-1228-3p has been validated as an adequate endogenous control for circulating miRNA analysis in CRC and AA liquid biopsies.

Tratamiento de COVID-19 en Panamá. La historia del inicio, estudio PanaCovid2020

Antecedentes En Panamá, durante los primeros cinco meses de pandemia, se reportaron 65,256 casos y 1,421 fallecimientos por COVID-19. Los tratamientos utilizados en pacientes hospitalizados durante este periodo fueron variando en la medida que surgía evidencia científica. Metodología Presentamos un estudio multicéntrico observacional, descriptivo, de corte transversal y retrospectivo de la terapéutica administrada en pacientes hospitalizados con COVID-19 en siete centros estatales de la República de Panamá, entre el 1 de marzo al 31 de julio de 2020. Se analizó el resultado de recuperado o fallecido en relación al uso de hidroxicloroquina, heparinas y esteroides. Resultados Se revisaron 837 expedientes. 60.7% pacientes eran hombres y la mediana de edad fue 53.6 años. Los tratamientos más utilizados fueron heparinas 84.7%, esteroides sistémicos 76.5%, azitromicina 65.5% e hidroxicloroquina en 41.1%. La frecuencia de uso de oxigenoterapia fue de cánula nasal 73,2%, máscara facial con reservorio 39%, cánula de alto flujo 8.9%, ventilación mecánica no invasiva 11.1% y ventilación invasiva en el 15.3%. Los esteroides mostraron mayor tasa de recuperación (OR 1.72 [1.16-2.54). Conclusiones El reto de abordar una nueva enfermedad, sin tratamiento conocido, con evolución y desenlace variable, llevó a la comunidad médica a utilizar medicamentos empíricos con potencial terapéutico incierto. Destacamos que desde muy temprano se administró esteroides sistémicos, heparinas y tocilizumab; actualmente con beneficios para pacientes con requerimientos de hospitalización. Además, se empleó técnicas de oxigenación, como la cánula de alto flujo y ventilación mecánica no invasiva, con dudosa efectividad; pero que hoy ya tienen un rol estudiado en la falla respiratoria por COVID-19. (provisto por Infomedic International)

Background: In Panama, during the first five months of the pandemic, 65,256 cases and 1,421 deaths due to COVID-19 were reported. The treatments used in hospitalized patients during this period varied as scientific evidence emerged. Methodology: We present a retrospective, descriptive, cross-sectional, observational, descriptive, multicenter study of the therapeutics administered in hospitalized patients with COVID-19 in seven state centers in the Republic of Panama, between March 1 and July 31, 2020. The outcome of recovered or deceased was analyzed in relation to the use of hydroxychloroquine, heparins and steroids. Results: A total of 837 files were reviewed. 60.7% of patients were men and the median age was 53.6 years. The most commonly used treatments were heparins 84.7%, systemic steroids 76.5%, azithromycin 65.5% and hydroxychloroquine in 41.1%. The frequency of oxygen therapy use was nasal cannula 73.2%, face mask with reservoir 39%, high-flow cannula 8.9%, noninvasive mechanical ventilation 11.1% and invasive ventilation in 15.3%. Steroids showed higher recovery rate (OR 1.72 [1.16-2.54). Conclusions: The challenge of dealing with a new disease, without known treatment, with variable evolution and outcome, led the medical community to use empirical drugs with uncertain therapeutic potential. We highlight the early administration of systemic steroids, heparins and tocilizumab; currently with benefits for patients requiring hospitalization. In addition, oxygenation techniques were used, such as high-flow cannula and noninvasive mechanical ventilation, with doubtful effectiveness, but which today have a studied role in respiratory failure due to COVID-19.   (provided by Infomedic International)

Infección por COVID-19 en pacientes en Hemodiálisis en Panamá 2020

Antecedentes y objetivo: Los pacientes con Enfermedad Renal Crónica (ERC) en Hemodiálisis son pacientes que tienen condiciones que los hacen pacientes de riesgo para la infección por COVID-19. Los pacientes en hemodiálisis han sido un grupo muy afectado, debido a que no pueden suspender sus tratamientos para mantener el aislamiento domiciliario, lo que aumenta su exposición y riesgo a infección por COVID-19. Para evaluar el comportamiento de la infección por SARS-CoV-2 en los pacientes en hemodiálisis crónica en Panamá, realizamos un estudio prospectivo de los pacientes infectados por COVID-19 en las Unidades de Hemodiálisis de la CSS de todo el país, para determinar las características de los pacientes afectados, los síntomas que presentaron, su evolución clínica y el desenlace de los pacientes infectados. Materiales y Médodos: Realizamos un estudio longitudinal descriptivo prospectivo multicéntrico de los casos positivos que se diagnosticaron desde el 15 de julio hasta el 31 de diciembre de 2020 en las 14 Unidades de Hemodiálisis de la CSS del país.  Resultados y conclusiones: Fueron incluidos un total de 333 pacientes en hemodiálisis con diagnóstico positivo para  infección  por SARS-CoV-2, de un total de 2194 pacientes que realizan hemodiálisis en las Unidades de la Caja de Seguro Social.  El 59.5% de los afectados fueron de sexo masculino.  La edad promedio fue de 56.75 años (DS 15.1 años).  La Tasa de Mortalidad encontrada en nuestro estudio fue de 26%. La incidencia acumulada de COVID-19 en pacientes en Hemodiálisis fue de 16% para el período de estudio del 2020. (provisto por Infomedic International)

Background and objective: Patients with Chronic Kidney Disease (CKD) on Hemodialysis are patients who have conditions that make them patients at risk for COVID-19 infection. Hemodialysis patients have been a highly affected group because they cannot stop their treatments to maintain home isolation, which increases their exposure and risk of COVID-19 infection. To evaluate the behavior of SARS-CoV-2 infection in patients on chronic hemodialysis in Panama, we conducted a prospective study of patients infected by COVID-19 in hemodialysis units throughout the country, to determine the characteristics of the affected patients, the symptoms they presented, their clinical evolution and the outcome of the infected patients. Materials and Methods: We conducted a multicenter prospective descriptive longitudinal study of the positive cases that were diagnosed from July 15, 2020 to December 31, 2020 in the 14 Hemodialysis Units of the Social Security Fund of the country. Results and conclusions: A total of 333 hemodialysis patients with a positive diagnosis for SARS-CoV-2 infection were included, out of a total of 2194 patients undergoing hemodialysis in the Units of the Social Security Fund. Fifty nine percet of those affected were male.  The mean age was 56.75 years (DS 15.1 years).  The Mortality Rate found in our study was 26%. The cumulative incidence of COVID-19 in hemodialysis patients was 16% for the 2020 study period. (provided by Infomedic International)

Antioxidant properties and protective effects of a standardized extract of Hypericum perforatum on hydrogen peroxide-induced oxidative damage in PC12 cells.

Free radical scavenging and antioxidant activities of a standardized extract of Hypericum perforatum (SHP) were examined for inhibition of lipid peroxidation, for hydroxyl radical scavenging activity and interaction with 1,1-diphenyl-2-picrylhydrazyl stable free radical (DPPH). Concentrations between 1 and 50 microg/ml of SHP effectively inhibited lipid peroxidation of rat brain cortex mitochondria induced by Fe2+/ascorbate or NADPH system. The results showed that SHP scavenged DPPH radical in a dose-dependent manner and also presented inhibitory effects on the activity of xanthine oxidase. In contrast, hydroxyl radical scavenging occurs at high doses. The protective effect of the standardized extract against H2O2-induced oxidative damage on the pheochromocytoma cell line PC 12 was investigated by measuring cell viability via 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), lactate dehydrogenase (LDH) assays, caspase-3-enzyme activity and accumulation of reactive oxygen species [2',7'-dichlorofluorescin (DCF) assay]. Following 8-h cell exposure to H2O2 (300 microM), a marked reduction in cell survival was observed, which was significantly prevented by SHP (pre-incubated for 24 h) at 1-100 microg/ml. In a separate experiment, different concentrations of the standardized extract (0.1-100 microg/ml) also attenuated the increase in caspase-3 activity and suppressed the H2O2 -induced reactive oxygen species generation. Taken together, these results suggest that SHP shows relevant antioxidant activity both in vitro and in a cell system, by means of inhibiting free radical generation and lipid peroxidation.