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Age-related diseases for which there are no effective treatments include cardiovascular diseases; neurodegenerative diseases such as Alzheimer's disease; eye disorders such as cataract and age-related macular degeneration; and, more recently, Severe Acute Respiratory Syndrome (SARS-CoV-2). These diseases are associated with plasma and/or tissue increases in cholesterol derivatives mainly formed by auto-oxidation: 7-ketocholesterol, also known as 7-oxo-cholesterol, and 7ß-hydroxycholesterol. The formation of these oxysterols can be considered as a consequence of mitochondrial and peroxisomal dysfunction, leading to increased in oxidative stress, which is accentuated with age. 7-ketocholesterol and 7ß-hydroxycholesterol cause a specific form of cytotoxic activity defined as oxiapoptophagy, including oxidative stress and induction of death by apoptosis associated with autophagic criteria. Oxiaptophagy is associated with organelle dysfunction and in particular with mitochondrial and peroxisomal alterations involved in the induction of cell death and in the rupture of redox balance. As the criteria characterizing 7-ketocholesterol- and 7ß-hydroxycholesterol-induced cytotoxicity are often simultaneously observed in major age-related diseases (cardiovascular diseases, age-related macular degeneration, Alzheimer's disease) the involvement of these oxysterols in the pathophysiology of the latter seems increasingly likely. It is therefore important to better understand the signalling pathways associated with the toxicity of 7-ketocholesterol and 7ß-hydroxycholesterol in order to identify pharmacological targets, nutrients and synthetic molecules attenuating or inhibiting the cytotoxic activities of these oxysterols. Numerous natural cytoprotective compounds have been identified: vitamins, fatty acids, polyphenols, terpenes, vegetal pigments, antioxidants, mixtures of compounds (oils, plant extracts) and bacterial enzymes. However, few synthetic molecules are able to prevent 7-ketocholesterol- and/or 7ß-hydroxycholesterol-induced cytotoxicity: dimethyl fumarate, monomethyl fumarate, the tyrosine kinase inhibitor AG126, memantine, simvastatine, Trolox, dimethylsufoxide, mangafodipir and mitochondrial permeability transition pore (MPTP) inhibitors. The effectiveness of these compounds, several of which are already in use in humans, makes it possible to consider using them for the treatment of certain age-related diseases associated with increased plasma and/or tissue levels of 7-ketocholesterol and/or 7ß-hydroxycholesterol.
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COVID-19 , Envejecimiento , Humanos , Hidroxicolesteroles , Cetocolesteroles , Nutrientes , Aceites , SARS-CoV-2RESUMEN
Vitamin A is essential for human health, but current intake levels in many developing countries such as India are too low due to malnutrition. According to the World Health Organization, an estimated 250 million preschool children are vitamin A deficient globally. This number excludes pregnant women and nursing mothers, who are particularly vulnerable. Efforts to improve access to vitamin A are key because supplementation can reduce mortality rates in young children in developing countries by around 23%. Three key genes, BCMO1, BCO2, and SCARB1, have been shown to be associated with the amount of ß-carotene (BC) in milk. Whole-genome sequencing reads from the coordinates of these 3 genes in 202 non-Indian cattle (141 Bos taurus, 61 Bos indicus) and 35 non-Indian buffalo (Bubalus bubalis) animals from several breeds were collected from data repositories. The number of SNP detected in the coding regions of these 3 genes ranged from 16 to 26 in the 3 species, with 5 overlapping SNP between B. taurus and B. indicus. All these SNP together with 2 SNP in the upstream part of the gene but already present in dbSNP (https://www.ncbi.nlm.nih.gov/projects/SNP/) were used to build a custom Sequenom array. Blood for DNA and milk samples for BC were obtained from 2,291 Indian cows of 5 different breeds (Gir, Holstein cross, Jersey Cross, Tharparkar, and Sahiwal) and 2,242 Indian buffaloes (Jafarabadi, Murrah, Pandharpuri, and Surti breeds). The DNA was extracted and genotyped with the Sequenom array. For each individual breed and the combined breeds, SNP with an association that had a P-value <0.3 in the first round of linear analysis were included in a second step of regression analyses to determine allele substitution effects to increase the content of BC in milk. Additionally, an F-test for all SNP within gene was performed with the objective of determining if overall the gene had a significant effect on the content of BC in milk. The analyses were repeated using a Bayesian approach to compare and validate the previous frequentist results. Multiple significant SNP were found using both methodologies with allele substitution effects ranging from 6.21 (3.13) to 9.10 (5.43) µg of BC per 100 mL of milk. Total gene effects exceeded the mean BC value for all breeds with both analysis approaches. The custom panel designed for genes related to BC production demonstrated applicability in genotyping of cattle and buffalo in India and may be used for cattle or buffalo from other developing countries. Moreover, the recommendation of selection for significant specific alleles of some gene markers provides a route to effectively increase the BC content in milk in the Indian cattle and buffalo populations.
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Búfalos/genética , Bovinos/genética , Marcadores Genéticos , Leche/química , beta Caroteno/análisis , Alelos , Animales , Femenino , Genotipo , India , Polimorfismo de Nucleótido Simple , Embarazo , Especificidad de la Especie , beta Caroteno/genéticaRESUMEN
AIM: This study was conducted to evaluate the impact of summer and winter season on physiological, biochemical, hormonal, and antioxidant parameters in Indigenous sheep. MATERIALS AND METHODS: The research was carried out during summer and winter season. 8 adult apparently healthy female sheep (aged 2-4 years) of similar physiological status were selected. Daily ambient temperature and relative humidity were recorded to calculate the temperature-humidity index (THI). The THI value of summer and winter season were 82.55 and 59.36, respectively, which indicate extreme hot condition during summer season and extreme cold condition during winter season. Physiological parameters were recorded daily during the experimental periods. Blood samples were collected at weekly interval and analyzed for biochemical, hormonal, and antioxidant parameters. The results were analyzed using completely randomized design. RESULTS: From data obtained in this study, we found that higher THI during summer have significant effect over various physiological, biochemical, hormonal, and enzymatic indices of indigenous sheep. The physiological response such as rectal temperature, respiration rate (RR), pulse rate (PR), and skin temperature (ST) was increased significantly. We also found a significant increase in some biochemical parameters such as blood urea nitrogen (BUN), uric acid, creatinine (Cr), alanine transaminase (ALT), aspartate transaminase (AST), sodium (Na), and potassium (K). The level of cortisol hormone and superoxide dismutase (SOD), glutathione peroxidase (GPx), and lipid peroxidase (LPO) antioxidants increased significantly during summer. Whereas, some parameters such as glucose, cholesterol, calcium (Ca), inorganic phosphorus (IP), triiodothyronine (T3), and thyroxine (T4) were decreased significantly during summer season. CONCLUSION: It was concluded that the THI is a sensitive indicator of heat stress and is impacted by ambient temperature more than the relative humidity in Indigenous sheep. Higher THI is associated with significant increase in RT, RR, PR, ST, BUN, uric acid, Cr, ALT, AST, Na, K, cortisol, SOD, GPx, and LPO and with a significant decrease in glucose, cholesterol, Ca, IP, T3 and T4.
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CASE HISTORY: An investigation was conducted to identify the cause of mortalities in freshwater reared Chinook salmon (Oncorhynchus tshawytscha). Mortalities occurred in juvenile salmon, at a salmon rearing facility in the South Island of New Zealand. The affected fish were from a pen inside the facility with no surrounding pens or other year classes affected. CLINICAL FINDINGS: Clinically affected fish presented with skin lesions. The majority of skin lesions were unruptured, boil-like, raised circular masses up to 4â cm in diameter, particularly on the dorsolateral aspects and the flank. A number of fish presented with large ulcers resulting from rupturing of the raised lesions described above. This clinical presentation showed similarities to that of furunculosis caused by typical Aeromonas salmonicida, a bacterium exotic to New Zealand. LABORATORY FINDINGS: Samples were taken from two representative fish in the field for histopathology, bacterial culture and molecular testing. Histopathological findings included granulomatous lesions in the kidney, liver, spleen and muscle. When stained with Fite-Faraco modified acid fast stain filamentous branching rods were identified within these granulomas. Following bacterial culture of kidney swabs pure growth of small white matt adherent colonies was observed. This isolate was identified as a Nocardia species by biochemical testing and nucleotide sequencing of the partial 16S rRNA gene. All samples were negative for A. salmonicida based on bacterial culture and PCR testing. DIAGNOSIS: Nocardiosis caused by a Nocardia species. CLINICAL RELEVANCE: Nocardiosis in these fish was caused by a previously undescribed Nocardia species that differs from the species known to be pathogenic to fish: N. asteroides, N. salmonicida and N. seriole. This bacterium is likely to be a new or unnamed environmental species of Nocardia that has the potential to cause disease in Chinook salmon under certain conditions. The clinical presentation of this Nocardia species manifested as raised, boil-like skin lesions which has similarities to the presentation of furunculosis caused by the bacterium typical A. salmonicida, a species exotic to New Zealand.
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Enfermedades de los Peces/microbiología , Nocardiosis/veterinaria , Nocardia/aislamiento & purificación , Salmón/microbiología , Animales , Bases de Datos de Ácidos Nucleicos , Enfermedades de los Peces/genética , Enfermedades de los Peces/patología , Agua Dulce , Genes de ARNr , Nueva Zelanda , Nocardia/genética , Nocardiosis/genética , Nocardiosis/patología , Reacción en Cadena de la PolimerasaRESUMEN
India being a tropical country, parasitic infections especially with Plasmodium species are very common in this region. The present case report is that of Plasmodium vivax, Plasmodium falciparum and dengue co-infection in a 6 months pregnant lady who was timely diagnosed and appropriately treated followed by a complete recovery along with feto-maternal well-being.
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AIM: Cardiovascular autonomic neuropathy (CAN) is a common but often overlooked complication of diabetes. Sympathetic C-fibers innervating sweat glands can be impaired early on in patients with diabetes. In this study, SUDOSCAN, a new non-invasive device that assesses sudomotor function was compared to methods generally used for the investigation of CAN. PATIENTS: A total of 232 patients with diabetes were measured for heart rate variability (HRV) at rest and during moderate activity. Time and frequency domain analysis techniques, including measurement of the low-frequency (LF) domain component, were assessed during HRV testing. Ewing tests, as recommended by the French Health Authority, were also done. Electrochemical sweat conductance (ESC) was measured on the hands and feet, and a risk-score was calculated. RESULTS: Using two abnormal Ewing tests as a reference for the area under the curve (AUC) of the receiver operating characteristics (ROC) curve for SUDOSCAN, the risk-score was 0.74, with a sensitivity of 92% and specificity of 49% for a risk-score cut-off value of 35%. For the ROC curve analysis using the LF power component during moderate activity at a threshold of 90 ms(2) (first quartile) as reference, the AUC was higher for the SUDOSCAN risk-score (0.77) compared with the standard Ewing tests [E:I ratio (0.62), 30:15 ratio (0.76) and blood pressure change on standing (0.55)]. Using a cut-off value of 35%, risk-score sensitivity and specificity were 88 and 54%, respectively. CONCLUSION: SUDOSCAN, which allows quick quantitative assessment of sudomotor function, may be used for early screening of CAN in everyday clinical practice before resorting to the more sophisticated and specific, but ultimately more time-consuming, Ewing tests.
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Sistema Nervioso Autónomo/fisiopatología , Diabetes Mellitus Tipo 2/fisiopatología , Neuropatías Diabéticas/fisiopatología , Piel/fisiopatología , Glándulas Sudoríparas/fisiopatología , Adulto , Anciano , Diabetes Mellitus Tipo 2/complicaciones , Diabetes Mellitus Tipo 2/metabolismo , Neuropatías Diabéticas/diagnóstico , Neuropatías Diabéticas/metabolismo , Femenino , Respuesta Galvánica de la Piel , Frecuencia Cardíaca , Humanos , Masculino , Persona de Mediana Edad , Valor Predictivo de las Pruebas , Reproducibilidad de los Resultados , Umbral Sensorial , Índice de Severidad de la Enfermedad , Piel/inervación , Piel/metabolismo , Glándulas Sudoríparas/inervación , Glándulas Sudoríparas/metabolismo , SudoraciónRESUMEN
Sheeppox and goatpox outbreaks occur often in India incurring huge economic loss to the small ruminant industry. This paper describes two sheeppox outbreaks, of which one occurred in an organized sheep breeding farm at Makhdoom (Uttar Pradesh), India, during 2007 and another in goats at the Central Institute of Research on Goats, Makhdoom (Uttar Pradesh), India during 2008. In the first outbreak, a local Muzaffarnagari sheep breed was affected (n=477) with morbidity and mortality rates, respectively, of 100% and 53.9% accompanied by significant productivity losses. In the 2008 outbreaks, a small number of goats were affected without any mortality. The tissue and swabs collected from both the outbreaks were processed and inoculated onto Vero cells, and the causative agent of the outbreaks, capripox virus (CaPV), was isolated. The identity of the virus was confirmed as CaPV based on electron microscopy, experimental pathogenesis in sheep, capripox-specific conventional and real-time PCRs. Sequence analysis of the P32 envelope protein gene revealed that the causative agent of both outbreaks was confirmed as sheeppox virus (SPPV) implying SPPV infection not only in sheep but also goats in India.
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Capripoxvirus/aislamiento & purificación , Enfermedades de las Cabras/virología , Infecciones por Poxviridae/veterinaria , Enfermedades de las Ovejas/virología , Animales , Brotes de Enfermedades/veterinaria , Enfermedades de las Cabras/epidemiología , Cabras , Infecciones por Poxviridae/epidemiología , Infecciones por Poxviridae/mortalidad , Infecciones por Poxviridae/virología , Ovinos , Enfermedades de las Ovejas/epidemiologíaRESUMEN
A total of 50 patients with advanced pancreatic cancer were enrolled in a phase II study of bevacizumab 15 mg kg(-1), capecitabine 1300 mg m(-2) daily for 2 weeks and gemcitabine 1000 mg m(-2) weekly 2 times; cycles were repeated every 21 days. Radiological response rate was 22%; progression-free survival and over survival were 5.8 and 9.8 months respectively. Grade 3 or 4 toxicities included neutropaenia (22%), thrombocytopaenia (14%), thromboembolic events (12%), hypertension (8%) and haemorrhage (6%).
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Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Neoplasias Hepáticas/tratamiento farmacológico , Neoplasias Pulmonares/tratamiento farmacológico , Neoplasias Pancreáticas/tratamiento farmacológico , Adulto , Anciano , Anciano de 80 o más Años , Anticuerpos Monoclonales/administración & dosificación , Anticuerpos Monoclonales Humanizados , Bevacizumab , Capecitabina , Desoxicitidina/administración & dosificación , Desoxicitidina/análogos & derivados , Femenino , Fluorouracilo/administración & dosificación , Fluorouracilo/análogos & derivados , Humanos , Neoplasias Hepáticas/secundario , Neoplasias Pulmonares/secundario , Metástasis Linfática , Masculino , Persona de Mediana Edad , Neoplasias Pancreáticas/patología , Pronóstico , Tasa de Supervivencia , Resultado del Tratamiento , GemcitabinaRESUMEN
Sheeppox virus from an outbreak of sheeppox that occurred in Srinagar (Jammu and Kashmir, India) in 2000 was isolated by inoculation of susceptible sheep and further re-isolated in cell culture. The field virus, adapted to grow in lamb testes culture, was evaluated for its potential use as challenge virus in potency testing of sheeppox vaccine currently in use. The virus (passage 6) produced severe disease in susceptible sheep when inoculated subcutaneously with a dose of 106.2 TCID50. The virus identity was confirmed by PCR, sequencing of P32 gene and species-specific signature residues identified in deduced aa sequence of the gene. The virus was successfully evaluated for its virulence using two batches of sheep pox vaccines. Use of this field virus enables consistent potency experiments of sheeppox vaccines avoiding use of animals for its propagation and titration.
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Capripoxvirus/patogenicidad , Vacunas Virales/análisis , Adaptación Fisiológica , Alternativas a las Pruebas en Animales , Animales , Capripoxvirus/genética , Capripoxvirus/inmunología , Capripoxvirus/fisiología , Células Cultivadas , Efecto Citopatogénico Viral , Genes Virales , Masculino , Infecciones por Poxviridae/prevención & control , Infecciones por Poxviridae/veterinaria , Infecciones por Poxviridae/virología , Ovinos , Enfermedades de las Ovejas/prevención & control , Enfermedades de las Ovejas/virología , VirulenciaRESUMEN
Esophageal adenocarcinoma (EAC) is one of the fastest growing malignancies in the US. The long-term survival of patients with this cancer remains poor; only 25% of patients undergoing surgical excision are alive after 5 years. Multimodal programs that incorporate radiotherapy, chemotherapy and surgery for localized tumors may result in a modest survival advantage. However, significant strides in this disease can result from the inclusion of targeted therapies. The epidermal growth factor receptor (EGFR) family represents one such target and is receiving increasing attention due to the advent of specific inhibitors. Studies conducted by us and others have shown that the overexpression of EGFR family signaling intermediates is common in Barrett's esophagus and EAC. In the latter case, EGFR expression may have prognostic significance. EGFR inhibitors, including oral tyrosine kinase inhibitors and monoclonal antibodies, result in a synergistic antitumor effect with chemotherapeutic agents or with radiotherapy. Therefore, several ongoing studies include EGFR-directed therapy either alone or in combination with chemoradiotherapy for this disease. Our study of gefitinib, oxaliplatin and radiotherapy suggested that gefitinib can be safely incorporated into an oxaliplatin-based chemoradiation program for esophageal cancer, although the clinical activity of this combination is modest. Herein, we review the current literature on this subject.
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Adenocarcinoma/tratamiento farmacológico , Receptores ErbB/antagonistas & inhibidores , Neoplasias Esofágicas/tratamiento farmacológico , Adenocarcinoma/epidemiología , Adenocarcinoma/mortalidad , Adenocarcinoma/cirugía , Anticuerpos Monoclonales/uso terapéutico , Anticuerpos Monoclonales Humanizados , Antineoplásicos/uso terapéutico , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Esófago de Barrett/tratamiento farmacológico , Esófago de Barrett/epidemiología , Clorhidrato de Erlotinib , Neoplasias Esofágicas/epidemiología , Neoplasias Esofágicas/mortalidad , Neoplasias Esofágicas/cirugía , Gefitinib , Humanos , Incidencia , Neoplasias Pulmonares/tratamiento farmacológico , Quinazolinas/uso terapéutico , Análisis de SupervivenciaRESUMEN
A total of 12 patients with malignant localized renal or ureteral neoplasms underwent multi-slice computed tomography. Imaging data were sent to the dedicated workstation to create volume rendering and virtual laparoscopic images of the kidney which was displaced ventrally with retroperitoneal balloon. These findings were compared with video images obtained during retroperitoneal laparoscopic nephrectomy. The kidney displacement simulator depicted all renal arteries (100% sensitivity) and 13 of 14 renal veins (93% sensitivity). Hilar anatomy, including the tumor, major vessels and their relationships were visualized as in the actual laparoscopic views. The desired portions of major vessels as well as the left adrenal and gonadal veins visualized with this system completely corresponded with the actual laparoscopic images during surgery. The kidney displacement simulator is useful to foresee desired portions of major vessels and branched small vessels such as the adrenal or gonadal veins in advance of surgery. It is thus able to guide surgeons and reduce operative risks and possible complications.
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Imagenología Tridimensional , Riñón/anatomía & histología , Laparoscopía , Nefrectomía , Tomografía Computarizada Espiral , Cateterismo , Simulación por Computador , Humanos , Procesamiento de Imagen Asistido por Computador , Neoplasias Renales/diagnóstico por imagen , Neoplasias Renales/cirugía , Espacio Retroperitoneal , Neoplasias Ureterales/diagnóstico por imagen , Neoplasias Ureterales/cirugíaRESUMEN
We have investigated the role of glycosylation of the envelope glycoprotein E2 of bovine viral diarrhoea virus (BVDV), produced in insect cells, in BVDV infection. When amino acids predicated to code for the C-terminal N-linked glycosylation site were mutated the resulting protein was less efficient than wild type protein at preventing infection of susceptible cells with BVDV. In addition, mutational analysis showed that a further two predicted N-terminal N-linked glycosylation sites of E2 are required for efficient production of recombinant protein.
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Baculoviridae/metabolismo , Virus de la Diarrea Viral Bovina/patogenicidad , Proteínas Recombinantes/metabolismo , Proteínas del Envoltorio Viral/metabolismo , Animales , Baculoviridae/genética , Bovinos , Células Cultivadas , Virus de la Diarrea Viral Bovina/genética , Virus de la Diarrea Viral Bovina/metabolismo , Glicosilación , Masculino , Mutagénesis Sitio-Dirigida , Proteínas Recombinantes/genética , Spodoptera/virología , Testículo/citología , Testículo/virología , Proteínas del Envoltorio Viral/genéticaRESUMEN
Acetylation polymorphism, although discovered 40 years ago, still holds interest not only because many drugs and carcinogens are metabolized by acetylation in the liver but also because advances have been made in the understanding of the molecular genetics of acetylation. It is this genetic variation of drug metabolism that is one of the causes of inter-individual variation of the effect of a drug. Acetylation polymorphism relates to the metabolism of a number of arylamine and hydrazine drugs and carcinogens by cytosolic N-acetyltransferase--NAT2. In humans, 2 genes--NAT1 and NAT2--are responsible for the N-acetyltransferase activity. Studies have revealed several allelic variants of both NAT1 and NAT2. It has been suggested that some of these variants modify the individual susceptibility to disease.
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Arilamina N-Acetiltransferasa/genética , Biotransformación/genética , Farmacogenética , Polimorfismo Genético/genética , Acetilación , Neoplasias Colorrectales/inducido químicamente , Genotipo , Humanos , Isoniazida/efectos adversos , Lupus Vulgar/inducido químicamente , Enfermedades del Sistema Nervioso Periférico/inducido químicamente , Fenotipo , Neoplasias de la Vejiga Urinaria/inducido químicamenteRESUMEN
A lump is the first symptom in over 80 percent of all patients with cancer of the breast. Consequently, the finding of any lump in the breast is a highly significant sign and warrants a thorough investigation. The present study was undertaken to study the predictive value of ultrasonography in the diagnosis of palpable breast lumps. Fifty-two female patients with palpable breast lumps that were unilateral underwent ultrasonography of the breast. Thirty-six of these patients who had solitary, unilateral, solid lumps were followed up with FNAC/biopsy/mammography and the findings were compared. The mean age group was seen to be 41 years. The youngest patient was 17 years old and the oldest was 80 years. The validity of USG in the diagnosis of palpable breast lumps was calculated. A sensitivity value of 95%, specificity of 94.10%, positive and negative predictive values of 95.50% and 93.75% were noted and were comparable to other similar studies. The sensitivity, specificity, positive and negative predictive values were statistically significant (p=0.0000006) and were comparable to the values obtained by different studies conducted elsewhere. Among the multiple USG parameters, shape, margins, vascularity, surrounding tissue character, sound transmission through the lump were more significant in the diagnosis of benign vs. malignant lumps. Echogenicity and echotexture were of less significance.
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Neoplasias de la Mama/diagnóstico por imagen , Adolescente , Adulto , Neoplasias de la Mama/diagnóstico , Neoplasias de la Mama/patología , Humanos , Mamografía , Valor Predictivo de las Pruebas , UltrasonografíaRESUMEN
The cysteine residues of the gamma crystallins, a family of ocular lens proteins, are involved in the aggregation and phase separation of these proteins. Both these phenomena are implicated in cataract formation. We have used bovine gammaB crystallin as a model system to study the role of the individual cysteine residues in the aggregation and phase separation of the gamma crystallins. Here, we compare the thermodynamic and kinetic behavior of the recombinant wild-type protein (WT) and the Cys18 to Ser (C18S) mutant. We find that the solubilities of the two proteins are similar. The kinetics of crystallization, however, are different. The WT crystallizes slowly enough for the metastable liquid-liquid coexistence to be easily observed. C18S, on the other hand, crystallizes rapidly; the metastable coexisting liquid phases of the pure mutant do not form. Nevertheless, the coexistence curve of C18S can be determined provided that crystallization is kinetically suppressed. In this way we found that the coexistence curve coincides with that of the WT. Despite the difference in the kinetics of crystallization, the two proteins were found to have the same crystal forms and almost identical X-ray structures. Our results demonstrate that even conservative point mutations can bring about dramatic changes in the kinetics of crystallization. The implications of our findings for cataract formation and protein crystallization are discussed.
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Sustitución de Aminoácidos/genética , Cristalinas/química , Cristalinas/metabolismo , Cristalización , Cisteína/metabolismo , Serina/metabolismo , Animales , Catarata/metabolismo , Bovinos , Cristalinas/genética , Cristalografía por Rayos X , Cisteína/genética , Cinética , Modelos Moleculares , Mutación Puntual/genética , Conformación Proteica , Proteínas Recombinantes/química , Proteínas Recombinantes/metabolismo , Serina/genética , Solubilidad , Termodinámica , gamma-CristalinasRESUMEN
Ventricular fibrillation, the major reason behind sudden cardiac death, is turbulent cardiac electrical activity in which rapid, irregular disturbances in the spatiotemporal electrical activation of the heart make it incapable of any concerted pumping action. Methods of controlling ventricular fibrillation include electrical defibrillation as well as injected medication. Electrical defibrillation, though widely used, involves subjecting the whole heart to massive, and often counterproductive, electrical shocks. We propose a defibrillation method that uses a very low-amplitude shock (of order mV) applied for a brief duration (of order 100 ms) and over a coarse mesh of lines on our model ventricle.
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Cardioversión Eléctrica/métodos , Modelos Cardiovasculares , Fibrilación Ventricular/terapia , Desfibriladores Implantables , HumanosRESUMEN
Several human genetic cataracts have been linked recently to point mutations in the gammaD crystallin gene. Here we provide a molecular basis for lens opacity in two genetic cataracts and suggest that the opacity occurs because of the spontaneous crystallization of the mutant proteins. Such crystallization of endogenous proteins leading to pathology is an unusual event. Measurements of the solubility curves of crystals of the Arg-58 to His and Arg-36 to Ser mutants of gammaD crystallin show that the mutations dramatically lower the solubility of the protein. Furthermore, the crystal nucleation rate of the mutants is enhanced considerably relative to that of the wild-type protein. It should be noted that, although there is a marked difference in phase behavior, there is no significant difference in protein conformation among the three proteins.