Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 73
Filtrar
1.
Cureus ; 16(1): e52183, 2024 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-38264176

RESUMEN

This review examines the evolution, current status, and future potential of minimally invasive glaucoma surgeries (MIGS), a significant advancement in the treatment of glaucoma, a leading cause of irreversible blindness. MIGS offer a less invasive alternative to traditional glaucoma surgeries, primarily aimed at reducing intraocular pressure, minimizing tissue trauma, and providing a safer profile. With the emergence of devices such as the Trabectome, iStent, and others, MIGS have expanded the surgical toolkit, allowing personalized, patient-centered care. Despite their advantages, MIGS face challenges such as efficacy in severe cases, long-term data, and accessibility. Ongoing research and technological innovations continue to refine their capabilities and applications, promising to further transform glaucoma management and patient outcomes. This paper provides an in-depth analysis of MIGS, reflecting on their impact and contemplating future directions in this dynamically evolving field.

2.
Cureus ; 16(1): e52676, 2024 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-38264181

RESUMEN

Diabetic macular edema (DME) is a major cause of vision impairment in diabetic individuals, characterized by fluid accumulation in the macula due to a breakdown of the blood-retinal barrier (BRB). This review article explores the role of anti-vascular endothelial growth factor (anti-VEGF) therapies in the management of DME. Anti-VEGF treatments, including ranibizumab, bevacizumab, and aflibercept, have revolutionized DME management by targeting VEGF, a key mediator in DME pathogenesis. We critically examined the efficacy of these therapies in reducing macular edema and improving visual acuity, assessed their safety and tolerability, and explored the variability in treatment response. The review highlights the latest advancements and future directions in anti-VEGF therapy, including novel drug delivery systems and emerging treatment paradigms. By providing a comprehensive overview of current anti-VEGF therapies, this review seeks to inform clinical practice, guide future research, and contribute to improved patient outcomes in DME management.

3.
J Genet Eng Biotechnol ; 21(1): 163, 2023 Dec 07.
Artículo en Inglés | MEDLINE | ID: mdl-38060084

RESUMEN

BACKGROUND: Staphylococcus xylosus is a coagulase-negative, gram-positive coccus that is found in the environment and as a commensal organism on the skin and mucosal surfaces of animals. Despite the fact that S. xylosus is considered a nonpathogenic bacterium, several studies have linked S. xylosus to opportunistic infections in both animals and humans. During an investigation of mastitis-causing agents in the governorate of Basrah, Iraq, we identified an antibiotic-resistant strain of S. xylosus NM36 from a milk sample from a cow with chronic mastitis. In addition to robust biofilm formation, multiple antibiotic resistance phenotypes were found. To further understand the genetic background for these phenotypes, the full genome of S. xylosus NM36 was analyzed. RESULTS: The genome consisted of a single circular 2,668,086 base pairs chromosome containing 32.8% G + C. There were 2454 protein-coding sequences, 4 ribosomal RNA (rRNA) genes, and 50 transfer RNA (tRNA) genes in the genome. In addition, genetic variation was studied by searching sequence data against a representative reference genome. Consequently, single-nucleotide polymorphism analysis was conducted and showed that there were 46,610 single-nucleotide polymorphisms (SNPs), 523 insertions, and 551 deletions. In order to overcome antibiotics, S. xylosus NM36 had been armed with several antibiotic resistance genes from several groups and families. The genome annotation service in PathoSystems Resource Integration Center (PATRIC) and Rapid Annotation using Subsystem Technology (RAST) annotation servers showed that there are multiple antimicrobial resistance elements, including antibiotic inactivation enzymes (BlaZ family, FosB), antibiotic resistance gene clusters (TcaB, TcaB2, TcaR), proteins involved in methicillin resistance (LytH, FmtA, FemC, HmrB, HmrA), TetR family transcriptional regulators, and efflux pumps conferring antibiotic resistance (NorA). In addition, we investigated and categorized the biofilm and quorum-sensing elements of the NM36 strain and found that it has multiple subsets of biofilm regulators, confirming its pathogenic nature. CONCLUSIONS: These findings necessitate a reevaluation of microbial and clinical interventions when dealing with coagulase-negative staphylococci, particularly in the context of studies pertaining to public health. This is the first time, to our knowledge, that the entire genome of S. xylosus has been sequenced in Iraq.

4.
Orbit ; 42(2): 206-208, 2023 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-34602002

RESUMEN

Sarcoid-like granulomas are a rare adverse effect of TNF-α inhibitors that are becoming increasingly reported in the literature. A retrospective study in France estimated this adverse effect to occur in 0.04% patients. We report an important reversible cause that is more commonly being seen.A 70 year old lady presented with multiple lesions on her lids in the ophthalmology clinic. Histology confirmed that they were sarcoid-like granulomas. The patient had been started on etanercept (anti-TNF agent) a few months prior for rheumatoid arthritis. Investigations were undertaken to rule out differentials such as autoimmune conditions and infective causes like tuberculosis.After ruling out an active inflammatory disease and an autoimmune cause, etanercept induced granulomas were considered. Etanercept was stopped. This resulted in the resolution of granulomas over the course of a few months.Etanercept induced granulomas resolve when the anti-TNF agent is discontinued; however, some patients may require treatment with steroids.As this case demonstrates, ophthalmologists should be aware that anti-TNF agents can cause non-caseating granulomas, which can be cutaneous or pulmonary. This can help to result in more prompt diagnoses and appropriate treatment.


Asunto(s)
Párpados , Etanercept/efectos adversos , Femenino , Anciano , Humanos , Factor de Necrosis Tumoral alfa/antagonistas & inhibidores , Granuloma/inducido químicamente , Visión Ocular
5.
Nat Commun ; 13(1): 540, 2022 01 27.
Artículo en Inglés | MEDLINE | ID: mdl-35087057

RESUMEN

G protein-coupled receptors (GPCRs) activate G proteins and undergo a complex regulation by interaction with GPCR kinases (GRKs) and the formation of receptor-arrestin complexes. However, the impact of individual GRKs on arrestin binding is not clear. We report the creation of eleven combinatorial HEK293 knockout cell clones lacking GRK2/3/5/6, including single, double, triple and the quadruple GRK knockout. Analysis of ß-arrestin1/2 interactions for twelve GPCRs in our GRK knockout cells enables the differentiation of two main receptor subsets: GRK2/3-regulated and GRK2/3/5/6-regulated receptors. Furthermore, we identify GPCRs that interact with ß-arrestins via the overexpression of specific GRKs even in the absence of agonists. Finally, using GRK knockout cells, PKC inhibitors and ß-arrestin mutants, we present evidence for differential receptor-ß-arrestin1/2 complex configurations mediated by selective engagement of kinases. We anticipate our GRK knockout platform to facilitate the elucidation of previously unappreciated details of GRK-specific GPCR regulation and ß-arrestin complex formation.


Asunto(s)
Arrestina/metabolismo , Quinasas de Receptores Acoplados a Proteína-G/metabolismo , Receptores Acoplados a Proteínas G/metabolismo , Proteínas de Unión al GTP/metabolismo , Células HEK293 , Humanos , Fosforilación , Transducción de Señal/fisiología , beta-Arrestina 1/metabolismo , Arrestina beta 2/metabolismo
6.
Aerosp Med Hum Perform ; 91(11): 839-844, 2020 Nov 01.
Artículo en Inglés | MEDLINE | ID: mdl-33334403

RESUMEN

INTRODUCTION: Exposure to low oxygen environments (hypoxia) can impair cognitive function; however, the time-course of the transient changes in cognitive function is unknown. In this study, we assessed cognitive function with a cognitive test before, during, and after exposure to hypoxia.METHODS: Nine participants (28 4 yr, 7 women) completed Conners Continuous Performance Test (CCPT-II) during three sequential conditions: 1) baseline breathing room air (fraction of inspired oxygen, FIo2 0.21); 2) acute hypoxia (FIo2 0.118); and 3) recovery after exposure to hypoxia. End-tidal gas concentrations (waveform capnography), heart rate (electrocardiography), frontal lobe tissue oxygenation (near infrared spectroscopy), and mean arterial pressure (finger photoplethysmography) were continuously assessed.RESULTS: Relative to baseline, during the hypoxia trial end-tidal (-30%) and cerebral (-9%) oxygen saturations were reduced. Additionally, the number of commission errors during the CCPT-II was greater during hypoxia trials than baseline trials (2.6 0.4 vs. 1.9 0.4 errors per block of CCPT-II). However, the reaction time and omission errors did not differ during the hypoxia CCPT-II trials compared to baseline CCPT-II trials. During the recovery CCPT-II trials, physiological indices of tissue hypoxia all returned to baseline values and number of commission errors during the recovery CCPT-II trials was not different from baseline CCPT-II trials.DISCUSSION: Oxygen concentrations were reduced (systemically and within the frontal lobe) and commission errors were increased during hypoxia compared to baseline. These data suggest that frontal lobe hypoxia may contribute to transient impairments in cognitive function during short exposures to hypoxia.Uchida K, Baker SE, Wiggins CC, Senefeld JW, Shepherd JRA, Trenerry MR, Buchholtz ZA, Clifton HR, Holmes DR, Joyner MJ, Curry TB. A novel method to measure transient impairments in cognitive function during acute bouts of hypoxia. Aerosp Med Hum Perform. 2020; 91(11):839844.


Asunto(s)
Cognición , Hipoxia , Femenino , Humanos , Pruebas Neuropsicológicas , Oxígeno , Tiempo de Reacción
7.
Diabetes Res Clin Pract ; 153: 184-190, 2019 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-31063856

RESUMEN

AIMS: There is potential to provide public health interventions through text messaging for patients with Type 2 diabetes mellitus (T2DM). Our objective was to ascertain if lifestyle focused text messaging addressing cardiovascular risk factors in patients with coronary heart disease (CHD) and T2DM, was more effective than usual care. METHODS: This is a secondary analysis of the TEXT ME study, a randomised clinical trial of a 6-month text messaging intervention in patients with coronary heart disease. The measured outcomes include cholesterol, blood pressure (BP), body mass index (BMI), HbA1c, waist/hip circumference and smoking status. Our objective was to ascertain if lifestyle focused text messaging in patients with T2DM was more effective than usual care, and to determine if the intervention was more effective in patients with T2DM compared to those without. RESULTS: 229 participants in the TEXT ME study had T2DM (32%), 111 participants in the intervention group and 118 in the control group. At 6 months, the mean difference in systolic BP was -7.6 mmHg (95%CI -11.8, -3.37, p = 0.0003) and diastolic BP -3.7 mmHg (95%CI -6.12, -1.24, p = 0.0032). The mean difference in low density lipoprotein in the intervention arm, compared to the control arm, was -0.05 mmol/L (95%CI -0.27, 0.18, p = 0.813), and in triglycerides was -0.29 mmol/L (95%CI -0.59, 0.01, p = 0.035) respectively. The mean difference in BMI was -0.89 kg/m2 (95%CI -2.74, 0.95, p < 0.0001) in the intervention group, waist circumference -3.98 cm (95%CI -8.57, 0.61, p < 0.0001) and hip circumference -3.26 cm (95%CI -7.67, 1.16, p = 0.0006). Intervention subjects with diabetes were less likely to be smokers at 6 months. The mean difference in HbA1c between the control and intervention group was not significant (p = 0.126). The intervention was as effective in patients with diabetes, compared to those without. CONCLUSION: Among patients with coronary heart disease with T2DM, lifestyle-focused text messaging resulted in significant risk factor reduction.


Asunto(s)
Enfermedad Coronaria/psicología , Diabetes Mellitus Tipo 2/psicología , Telemedicina/métodos , Envío de Mensajes de Texto/instrumentación , Femenino , Humanos , Estilo de Vida , Masculino , Persona de Mediana Edad , Factores de Riesgo
8.
Zoonoses Public Health ; 65(4): 459-463, 2018 06.
Artículo en Inglés | MEDLINE | ID: mdl-29516663

RESUMEN

A serosurvey for Tahyna virus (TAHV), a mosquito-borne California encephalitis orthobunyavirus (Peribunyaviridae) endemic to Europe, was performed to estimate the activity of TAHV on a broad geographic scale. Sera from wild boar (Sus scrofa), roe deer (Capreolus capreolus) and red deer (Cervus elaphus) were collected from Austria, Hungary and Romania. Samples were tested for neutralizing antibodies against TAHV using a virus microneutralization assay. The results demonstrate that TAHV transmission to mammals is widespread in Europe, particularly in the wild boar population where the mean rate of seroconversion is 15.2%.


Asunto(s)
Animales Salvajes/virología , Anticuerpos Neutralizantes/sangre , Virus de la Encefalitis de California/inmunología , Encefalitis de California/veterinaria , Vigilancia Inmunológica , Animales , Austria/epidemiología , Ciervos/inmunología , Ciervos/virología , Encefalitis de California/epidemiología , Encefalitis de California/transmisión , Encefalitis de California/virología , Hungría/epidemiología , Pruebas de Neutralización , Rumanía/epidemiología , Estudios Seroepidemiológicos , Pruebas Serológicas , Sus scrofa/inmunología , Sus scrofa/virología
9.
Am J Ophthalmol ; 185: 94-100, 2018 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-29101008

RESUMEN

PURPOSE: To develop a neural network for the estimation of visual acuity from optical coherence tomography (OCT) images of patients with neovascular age-related macular degeneration (AMD) and to demonstrate its use to model the impact of specific controlled OCT changes on vision. DESIGN: Artificial intelligence (neural network) study. METHODS: We assessed 1400 OCT scans of patients with neovascular AMD. Fifteen physical features for each eligible OCT, as well as patient age, were used as input data and corresponding recorded visual acuity as the target data to train, validate, and test a supervised neural network. We then applied this network to model the impact on acuity of defined OCT changes in subretinal fluid, subretinal hyperreflective material, and loss of external limiting membrane (ELM) integrity. RESULTS: A total of 1210 eligible OCT scans were analyzed, resulting in 1210 data points, which were each 16-dimensional. A 10-layer feed-forward neural network with 1 hidden layer of 10 neurons was trained to predict acuity and demonstrated a root mean square error of 8.2 letters for predicted compared to actual visual acuity and a mean regression coefficient of 0.85. A virtual model using this network demonstrated the relationship of visual acuity to specific, programmed changes in OCT characteristics. When ELM is intact, there is a shallow decline in acuity with increasing subretinal fluid but a much steeper decline with equivalent increasing subretinal hyperreflective material. When ELM is not intact, all visual acuities are reduced. Increasing subretinal hyperreflective material or subretinal fluid in this circumstance reduces vision further still, but with a smaller gradient than when ELM is intact. CONCLUSIONS: The supervised machine learning neural network developed is able to generate an estimated visual acuity value from OCT images in a population of patients with AMD. These findings should be of clinical and research interest in macular degeneration, for example in estimating visual prognosis or highlighting the importance of developing treatments targeting more visually destructive pathologies.


Asunto(s)
Mácula Lútea/diagnóstico por imagen , Redes Neurales de la Computación , Tomografía de Coherencia Óptica/métodos , Agudeza Visual/fisiología , Degeneración Macular Húmeda/diagnóstico , Anciano , Femenino , Angiografía con Fluoresceína , Fondo de Ojo , Humanos , Masculino , Persona de Mediana Edad , Reproducibilidad de los Resultados , Estudios Retrospectivos , Degeneración Macular Húmeda/fisiopatología
10.
Prog Urol ; 27(2): 58-67, 2017 Feb.
Artículo en Francés | MEDLINE | ID: mdl-28169121

RESUMEN

INTRODUCTION AND OBJECTIVE: Percutaneous nephrolithotomy (PCNL) is the gold standard treatment for kidney stones regardless of age. Elderly patients (EP)≥65years old, in growing numbers, have more comorbidities than the general population, may alter results of PCNL. The aim of this meta-analysis was to compare efficacy and complications of this procedure between EP and young patients (YP). METHODS: Original studies of prospective and historical cohorts, in English or French, presenting PCNL series published on PubMed until 2015 were identified using the keywords percutaneous nephrolithotomy, elderly patients, kidney stones and staghorn calculi. Our analysis focused on therapeutic efficacy, defined by absence of residual fragment or the presence of residual fragments<4mm at 3 postoperative months, and postoperative complications according to patient age: YP<65 years old and EP≥65 years old. Binary qualitative data were analyzed using odds ratio (OR) and quantitative data by estimating the difference of means. RESULTS: In total 397 studies were identified among which 23 were checked and 8 included in the meta-analysis for methodological quality corresponding to 4995 YP and 820 EP. No efficacy difference (OR=0.96; [IC95 %: 0.80; 1.17]; P=0.71), operating time (+1.15min in EP [IC95 %: -2.83; 5.12]; P=0.57) and average length of stay (+0.29 days in EP [IC95 %: -0.14; 0.72]; P=0.19) has been reported. It was a trend to more urinary infections (OR=2.24; [IC95 %: 0.74-6.80]; P=0.16) and a significantly increase of postoperative blood transfusions in EP (OR=1.41; [IC95 %: 1.00-1.97]; P=0.04). CONCLUSIONS: PCNL for kidney stones n EP is effective with a significantly increase the risk of postoperative blood transfusions compared to YP.


Asunto(s)
Cálculos Renales/cirugía , Nefrostomía Percutánea , Anciano , Humanos
11.
Saudi J Ophthalmol ; 29(4): 249-54, 2015.
Artículo en Inglés | MEDLINE | ID: mdl-26586973

RESUMEN

AIMS: To determine the short-term efficacy of corneal collagen crosslinking (CXL) treatment in patients with progressive Keratoconus (KCN) in comparison with no treatment. SETTINGS AND DESIGN: This controlled clinical trial study was carried out at a tertiary eye hospital, Eastern Province, Saudi Arabia. METHODS AND MATERIAL: A prospective controlled clinical study of patients being treated for Keratoconus at a tertiary eye care hospital in the Eastern province of Saudi Arabia. 51 eyes of 43 patients with progressive KCN who received corneal collagen crosslinking (treatment group) and 50 eyes of 34 patients with KCN and no treatment (control group) were included in our study. A one year clinical data were collected preoperatively as well as at 1, 3, 6 and 12 months postoperatively for the treatment group patients. A baseline and 1 year clinical data were collected for the control group patients. The short-term efficacy of the treatment in preventing progression of KCN in comparison with no treatment was analysed at one year. RESULTS: At one year after crosslinking there was significant flattening of the average keratometry by 0.61 D (p = 0.001) [95% CI: 0.25, 0.97] compared to 0.40 D (p = 0.210) steepening in the control group; difference between treatment and control was 1.01 D (p = 0.006) [95%CI: 0.29, 1.72]. Pachymetry in treatment group thinned by 20.21 µm (p < 0.0001) [95% CI: 12.77, 27.66] compared to 0.32 µm (p = 0.912) in the control group. Visual acuity remained stable at the preoperative level of 20/30 (p = 0.397) in the treatment group and 20/40 (p = 0.553) in the control group at one year. CONCLUSIONS: Corneal CXL is an effective treatment for halting the progression of KCN as shown by reduced keratometry and stability of vision.

13.
Saudi J Ophthalmol ; 29(2): 135-6, 2015.
Artículo en Inglés | MEDLINE | ID: mdl-25892933

RESUMEN

The aim of this communication is to report the incidence of endophthalmitis following the use of intravitreal Bevacizumab (IVB) at a tertiary care hospital in the Eastern province of Saudi Arabia. A total of 2769 intravitreal Bevacizumab injections were carried out between January 2009 and April 2014. During this period, one case of endophthalmitis following IVB injection occurred. The overall incidence of clinical endophthalmitis was 0.036% (1/2769; 95% confidence interval: 0.0001-0.002%). This compares favorably with studies reported from other parts of the world.

14.
Prog Urol ; 25(2): 75-82, 2015 Feb.
Artículo en Francés | MEDLINE | ID: mdl-25555503

RESUMEN

PURPOSE: Elastography is a novel imaging technology that shows promise in the identification of anatomic structures. The widespread use of ultrasound for screening testicular tumors in patients with cancer risk factors highlights unclassified testicular micronodules. We investigated the ability of elastography to accurately diagnose testicular nodules. MATERIAL: Patients with clinical testicular nodules were assigned to undergo elastography in a prospective study. The imaging was carried out by a single radiologist using a static elastography unit with a 9-14MHz frequency linear transducer, to identify hardness score, loss of architecture of testicular parenchyma, and surrounding effect. When orchidectomy was required, the corresponding specimens were subjected to hematoxylin and eosin staining for histologic correlation. RESULTS: We imaged 34 testicular lesions: 26/34 (76%) malignant tumors and 8/34 (24%) non-tumor lesion including 4 hematomas, 3 orchitis and 1 ischemia. Se, Sp, PPV and NPV of hardness in elastography in differentiating between malignant and benign tissue was found to be 96.2%, 37.5%, 83%, and 75%, respectively. Further, for recognizing cancer, the loss of architecture of the testicular parenchyma detecting in elastography was 92.3%, 75%, 92.3%, and 75%, respectively, and the surrounding effect was 84.6%, 87.5%, 95.6% and 63.6%, respectively. CONCLUSION: Elastography may be a promising tool at diagnosing testicular tumor when the loss of architecture and the surrounding effect were present. Further studies are needed to evaluate whether the utility of elastography is worth pursuing to identify of unclassified testicular micronodules. LEVEL OF EVIDENCE: 3.


Asunto(s)
Diagnóstico por Imagen de Elasticidad , Neoplasias Testiculares/diagnóstico por imagen , Adolescente , Adulto , Humanos , Masculino , Persona de Mediana Edad , Estudios Prospectivos , Adulto Joven
15.
Int J Ophthalmol ; 7(2): 251-5, 2014.
Artículo en Inglés | MEDLINE | ID: mdl-24790866

RESUMEN

AIM: To report the visual outcome based on various patterns of optical coherence tomography (OCT) morphology in diabetic macular edema (DME), following treatment with anti-VEGF intravitreal bevacizumab (IVB) injection. METHODS: Sixty-seven consecutive subjects with centre involving DME underwent intravitreal injection of Bevacizumab (1.25 mg/0.05 mL) in this retrospective, comparative, non randomized study. The DME was classified into one of four categories: focal, diffuse, focal cystoid and neurosensory detachment based on OCT. Best corrected visual acuity (BCVA), macular appearance, and OCT findings were used to decide whether the subject should have a repeat injection of intravitreal bevacizumab. Outcome measures were a change in mean BCVA (Snellen converted to logMAR) and central macular thickness (CMT) in each group during the six month follow-up period. RESULTS: The mean BCVA improved to logMAR 0.23 at final follow-up from a baseline of 0.32 logMAR (P=0.040) in the focal group, logMAR 0.80 at final follow-up from a baseline of 0.82 logMAR (P=0.838) in the diffuse group, worsened to logMAR 0.53 at final follow-up from a baseline of 0.43 logMAR (P=0.276) in the focal cystoid group, and improved to logMAR 0.79 at final follow-up from a baseline of 0.93 logMAR (P=0.490) in the neurosensory detachment group. The mean CMT before treatment were 298.8±25.03 µm in the focal group, 310.8±40.6 µm in the diffuse group, 397.15±31.05 µm in the focal cystoid group and 401.03±75.1 µm in the neurosensory detachment group. A mean of 2.05 (range: 1-5) injections in the focal group, 1.32 (range: 1-2) in the diffuse group, 2.6 (range: 1-6) in the focal cystoid group and 2.6 (range: 1-6) in the neurosensory detachment group were performed during the six month follow-up period. Following intravitreal bevacizumab treatment, vision improved, remained unchanged or worsened in 11, 7 and 2 subjects in focal group; 11, 9 and 8 in diffuse group; 0, 2 and 4 in focal cystoid group and 5, 5 and 3 subjects respectively in neurosensory detachment group. CONCLUSION: OCT morpholgy patterns in DME may predict the effects of intravitreal bevacizumab treatment, and patients with focal DME are most likely to benefit from the improvent of visual acuity from this treatment.

17.
J Eval Clin Pract ; 19(2): 358-62, 2013 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-22409210

RESUMEN

BACKGROUND: Development of chronic disease risk prediction models has become a growing area of research in recent years. The internal validity of such models is sometimes lower than estimated from the development sample. Overfitting or overoptimism of the developed model and/or differences between the samples are likely causes for this. For modelling of an uncommon outcome, bootstrapping for overoptimism is the preferred method for afterwards shrinking of regression coefficients and the model's discrimination and calibration for overoptimism. However, computer programs for different types of bootstrap validation are not readily available. We developed two SAS macro programs--one for the simple bootstrap that compares the discriminatory performance of the Cox proportional hazards model from the original sample in bootstrap samples; and another (which is more efficient), known as stepwise bootstrap validation, that makes the same comparison but from models developed by variable selection from bootstrap samples in the original sample. These are illustrated through an example from cardiovascular disease (CVD) risk prediction. METHODS: Two SAS macro programs for Cox proportional hazards model using Proc PHREG were developed for estimating overoptimism in Harrell's C and Somers' D statistics. The computer programs were applied to data on CVD incidence for a Framingham cohort that combined both the original and offspring exams. The risk factors considered were current smoking, diabetes, age, sex, systolic blood pressure, diastolic blood pressure, total cholesterol, high-density lipoprotein cholesterol, triglycerides and body mass index. RESULTS: The degree of overoptimism in both Harrell's C and Somers' D statistics were low. Both these statistics were corrected for overoptimism by subtracting overoptimism from their observed values. Between the two bootstrap validation algorithms, the degree of overoptimism was estimated to be higher for stepwise bootstrap validation. CONCLUSION: The programs are very useful for evaluating the 'overoptimism corrected' predictive performance of Cox proportional hazards model.


Asunto(s)
Enfermedades Cardiovasculares/etiología , Modelos Estadísticos , Medición de Riesgo/métodos , Programas Informáticos , Humanos , Modelos de Riesgos Proporcionales , Medición de Riesgo/estadística & datos numéricos , Factores de Riesgo , Victoria
18.
Prev Med ; 56(1): 41-5, 2013 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-23153691

RESUMEN

OBJECTIVES: As population ages and treatment for cardiovascular disease improves the risk of all-cause mortality has become a more meaningful outcome. We develop all-cause mortality equations for predicting long term risk using cardiovascular risk factors. METHODS: The 24-year risk of all-cause mortality was evaluated using Cox model for participants aged 40-81 years at the 10th or 11th examination of the Framingham original cohort and the first examination of the offspring cohort-all of whom were free of major chronic diseases. RESULTS: The predictors of all-cause mortality were age, sex, systolic blood pressure, total cholesterol/HDL ratio and smoking status. Risk prediction improved significantly when intensity of smoking and time since quitting were included into smoking status. A reduced model based on non-laboratory risk factors also demonstrated good predictive performance. CONCLUSIONS: All-cause mortality risk equations incorporating cardiovascular risk factors provide an improved tool to quantify risk and guide prevention of mortality. There are great potentials for prevention of the CVD epidemic and for increased longevity with health, through improved life-styles and consequent lower levels of blood pressure, cholesterol and smoking.


Asunto(s)
Enfermedades Cardiovasculares/etiología , Causas de Muerte/tendencias , Medición de Riesgo/métodos , Adulto , Anciano , Anciano de 80 o más Años , Femenino , Humanos , Masculino , Massachusetts/epidemiología , Persona de Mediana Edad , Modelos Estadísticos , Modelos de Riesgos Proporcionales , Medición de Riesgo/estadística & datos numéricos , Factores de Riesgo
19.
Aust N Z J Public Health ; 36(6): 557-63, 2012 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-23216497

RESUMEN

OBJECTIVE: To project prevalence of normal weight, overweight and obesity by educational attainment, assuming a continuation of the observed individual weight change in the 5-year follow-up of the national population survey, the Australian Diabetes, Obesity and Lifestyle study (AusDiab; 2000-2005). METHODS: Age-specific transition probabilities between BMI categories, estimated using logistic regression, were entered into education-level-specific, incidence-based, multi-state life tables. Assuming a continuation of the weight change observed in AusDiab, these life tables estimate the prevalence of normal weight, overweight and obesity for Australian adults with low (secondary), medium (diploma) and high (degree) levels of education between 2005 and 2025. RESULTS: The prevalence of obesity among individuals with secondary level educational attainment is estimated to increase from 23% in 2000 to 44% in 2025. Among individuals with a degree qualification or higher, it will increase from 14% to 30%. If all current educational inequalities in weight change could be eliminated, the projected difference in the prevalence of obesity by 2025 between the highest and lowest educated categories would only be reduced by half (to a 6 percentage point difference from 14 percentage points). CONCLUSION: We predict that almost half of Australian adults with low educational status will be obese by 2025. Current trends in obesity have the potential to drive an increase in the absolute difference in obesity prevalence between educational categories in future years. IMPLICATIONS: Unless obesity prevention and management strategies focus specifically on narrowing social inequalities in obesity, inequalities in health are likely to widen.


Asunto(s)
Escolaridad , Obesidad/epidemiología , Factores Socioeconómicos , Adulto , Distribución por Edad , Anciano , Anciano de 80 o más Años , Australia/epidemiología , Índice de Masa Corporal , Femenino , Encuestas Epidemiológicas , Humanos , Incidencia , Tablas de Vida , Modelos Logísticos , Estudios Longitudinales , Masculino , Persona de Mediana Edad , Vigilancia de la Población , Prevalencia , Adulto Joven
20.
Water Res ; 46(15): 4861-9, 2012 Oct 01.
Artículo en Inglés | MEDLINE | ID: mdl-22763291

RESUMEN

The aim of the current study was to investigate the feasibility of membrane contactors for continuous ammonia (NH3-N) removal in an anaerobic digestion process and to counteract ammonia inhibition. Two laboratory anaerobic digesters were fed slaughterhouse wastes with ammonium (NH4⁺) concentrations ranging from 6 to 7.4 g/L. One reactor was used as reference reactor without any ammonia removal. In the second reactor, a hollow fiber membrane contactor module was used for continuous ammonia removal. The hollow fiber membranes were directly submerged into the digestate of the anaerobic reactor. Sulfuric acid was circulated in the lumen as an adsorbent solution. Using this set up, the NH4⁺-N concentration in the membrane reactor was significantly reduced. Moreover the extraction of ammonia lowered the pH by 0.2 units. In combination that led to a lowering of the free NH3-N concentration by about 70%. Ammonia inhibition in the reference reactor was observed when the concentration exceeded 6 g/L NH4⁺-N or 1-1.2 g/L NH3-N. In contrast, in the membrane reactor the volatile fatty acid concentration, an indicator for process stability, was much lower and a higher gas yield and better degradation was observed. The chosen approach offers an appealing technology to remove ammonia directly from media having high concentrations of solids and it can help to improve process efficiency in anaerobic digestion of ammonia rich substrates.


Asunto(s)
Amoníaco/aislamiento & purificación , Membranas Artificiales , Anaerobiosis
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA