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1.
Artículo en Chino | WPRIM (Pacífico Occidental) | ID: wpr-971229

RESUMEN

The advantages of lymph node dissection through total laparoscopic total gastrectomy (TLTG) seem to be more and more accepted by the academic community. However, reconstruction of digestive tract is challenging and remains a focus of debate and research. Which way is better for esophagojejunostomy, circular stapler or linear stapler,remains to be answered. The authors believe that, under the conditions of existing anastomosis instruments, using of linear stapler for esophagojejunal side-to-side anastomosis may be the most common choice, but it must be used with strict indications, because there are still many problems to be solved. It is believed that with the breakthrough in the development of the circular stapler suitable for esophagojejunostomy in TLTG, the application of circular stapler for digestive tract reconstruction will become the mainstream again in future. Thus, the current routine clinical practice of TLTG should be cautious and the surgical indications should be strictly evaluated.


Asunto(s)
Humanos , Laparoscopía , Neoplasias Gástricas/patología , Anastomosis Quirúrgica , Esofagoplastia , Gastrectomía , Estudios Retrospectivos
2.
Future Oncol ; 17(27): 3627-3636, 2021 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-34409859

RESUMEN

Solitary fibrous tumor (SFT) is a rare soft tissue sarcoma subtype which mainly affects adults in the fifth and sixth decades of life. Originally part of a spectrum of tumors called hemangiopericytomas, classification has been refined such that SFTs now represent a distinct subtype. The identification of NAB2-STAT6 fusion in virtually all SFTs has further aided to define this rare subgroup. SFTs have a spectrum of behavior from benign to malignant, with evidence suggesting risk of metastases related to age at diagnosis, extent of necrosis, mitotic rate and tumor size. The standard treatment for localized disease is surgical excision with or without radiotherapy. Retrospective and prospective evidence suggests antiangiogenic treatment is effective for unresectable disease. Further translational work is required to understand the biology driving the differential behavior and identify more effective treatments for patients with metastatic disease.


Asunto(s)
Sarcoma/genética , Sarcoma/terapia , Neoplasias de los Tejidos Blandos/genética , Neoplasias de los Tejidos Blandos/terapia , Tumores Fibrosos Solitarios/genética , Tumores Fibrosos Solitarios/terapia , Femenino , Fusión Génica , Humanos , Masculino , Persona de Mediana Edad , Proteínas Represoras/genética , Factor de Transcripción STAT6/genética , Sarcoma/patología , Neoplasias de los Tejidos Blandos/patología , Tumores Fibrosos Solitarios/patología , Resultado del Tratamiento
3.
Preprint en Inglés | medRxiv | ID: ppmedrxiv-21253235

RESUMEN

Wastewater-based disease surveillance is a promising approach for monitoring community outbreaks. Here we describe a nationwide campaign to monitor SARS-CoV-2 in the wastewater of 159 counties in 40 U.S. states, covering 13% of the U.S. population from February 18 to June 2, 2020. Out of 1,751 total samples analyzed, 846 samples were positive for SARS-CoV-2 RNA, with overall viral concentrations declining from April to May. Wastewater viral titers were consistent with, and appeared to precede, clinical COVID-19 surveillance indicators, including daily new cases. Wastewater surveillance had a high detection rate (>80%) of SARS-CoV-2 when the daily incidence exceeded 13 per 100,000 people. Detection rates were positively associated with wastewater treatment plant catchment size. To our knowledge, this work represents the largest-scale wastewater-based SARS-CoV-2 monitoring campaign to date, encompassing a wide diversity of wastewater treatment facilities and geographic locations. Our findings demonstrate that a national wastewater-based approach to disease surveillance may be feasible and effective.

4.
J Oral Biol Craniofac Res ; 10(4): 629-638, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32983857

RESUMEN

Implant stability quotients (ISQ values) are obtained in dental clinical practice on a non-invasive basis by resonance frequency measurement rapidly after surgical placement of implants. The ISQ-values are used as indicator for mechanical implant stability, and are believed to have predictive power for clinical outcome. It is the aim of this review to provide a synopsis of all factors described in the literature that influence ISQ measurements by performing an exhaustive literature review; moreover, this review aims at elucidating the key factors relevant for a rapid clinical predictive assessment. We searched systematically and exhaustively all major databases for publications relating to ISQ measurement methodology and for ISQ-influencing factor analyses. The reports identified were ordered in experimental (preclinical) studies and in clinical publications. We were able to identify 13 basic factors influencing ISQ-measurements. Among these, local bone quality, playing a key role in such measurements, was subdivided in four specific subfactors; thus a total of 17 individual factors was identified and reported to influence ISQ-measurements. A comprehensive list of these factors is provided in Table-form. A critical analysis points out that only 6 of these factors are of a sound predictive power useful for a rapid clinical assessment; and only two of these factors appear to have a well-documented scientific basis.

5.
Preprint en Inglés | medRxiv | ID: ppmedrxiv-20117747

RESUMEN

Current estimates of COVID-19 prevalence are largely based on symptomatic, clinically diagnosed cases. The existence of a large number of undiagnosed infections hampers population-wide investigation of viral circulation. Here, we use longitudinal wastewater analysis to track SARS-CoV-2 dynamics in wastewater at a major urban wastewater treatment facility in Massachusetts, between early January and May 2020. SARS-CoV-2 was first detected in wastewater on March 3. Viral titers in wastewater increased exponentially from mid-March to mid-April, after which they began to decline. Viral titers in wastewater correlated with clinically diagnosed new COVID-19 cases, with the trends appearing 4-10 days earlier in wastewater than in clinical data. We inferred viral shedding dynamics by modeling wastewater viral titers as a convolution of back-dated new clinical cases with the viral shedding function of an individual. The inferred viral shedding function showed an early peak, likely before symptom onset and clinical diagnosis, consistent with emerging clinical and experimental evidence. Finally, we found that wastewater viral titers at the neighborhood level correlate better with demographic variables than with population size. This work suggests that longitudinal wastewater analysis can be used to identify trends in disease transmission in advance of clinical case reporting, and may shed light on infection characteristics that are difficult to capture in clinical investigations, such as early viral shedding dynamics.

6.
Int J Cardiol Heart Vasc ; 26: 100449, 2020 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-31909177

RESUMEN

Sigma-1 receptors are ligand-regulated chaperone proteins, involved in several cellular mechanisms. The aim of this systematic review was to examine the effects that the sigma-1 receptor has on the cardiovascular system. The interaction targets and proposed mechanisms of action of sigma-1 receptors were explored, with the aim of determining if the sigma-1 receptor is a potential pharmacological target for cardiac pathologies. This systematic review was conducted according to the PRISMA guidelines and these were used to critically appraise eligible studies. Pubmed and Scopus were systematically searched for articles investigating sigma-1 receptors in the cardiovascular system. Papers identified by the search terms were then subject to analysis against pre-determined inclusion criteria. 23 manuscripts met the inclusion criteria and were included in this review. The experimental platforms, experimental techniques utilised and the results of the studies were summarised. The sigma-1 receptor is found to be implicated in cardioprotection, via various mechanisms including stimulating the Akt-eNOS pathway, and reduction of Ca2 + leakage into the cytosol via modulating certain calcium channels. Sigma-1 receptors are also found to modulate other cardiac ion channels including different subtypes of potassium and sodium channels and have been shown to modulate intracardiac neuron excitability. The sigma-1 receptor is a potential therapeutic target for treatment of cardiac pathologies, particularly cardiac hypertrophy. We therefore suggest investigating the cardioprotective mechanisms of sigma-1 receptor function, alongside proposed potential ligands that can stimulate these functions.

7.
Semin Cancer Biol ; 61: 56-70, 2020 04.
Artículo en Inglés | MEDLINE | ID: mdl-31722230

RESUMEN

Sarcomas are a rare group of mesenchymal cancers comprising over 70 different histological subtypes. For the majority of these diseases, the molecular understanding of the basis of their initiation and progression remains unclear. As such, limited clinical progress in prognosis or therapeutic regimens have been made over the past few decades. Proteomics techniques are being increasingly utilised in the field of sarcoma research. Proteomic research efforts have thus far focused on histological subtype characterisation for the improvement of biological understanding, as well as for the identification of candidate diagnostic, predictive, and prognostic biomarkers for use in clinic. However, the field itself is in its infancy, and none of these proteomic research findings have been translated into the clinic. In this review, we provide a brief overview of the proteomic strategies that have been employed in sarcoma research. We evaluate key proteomic studies concerning several rare and ultra-rare sarcoma subtypes including, gastrointestinal stromal tumours, osteosarcoma, liposarcoma, leiomyosarcoma, malignant rhabdoid tumours, Ewing sarcoma, myxofibrosarcoma, and alveolar soft part sarcoma. Consequently, we illustrate how routine implementation of proteomics within sarcoma research, integration of proteomics with other molecular profiling data, and incorporation of proteomics into clinical trial studies has the potential to propel the biological and clinical understanding of this group of complex rare cancers moving forward.


Asunto(s)
Proteoma , Proteómica , Sarcoma/metabolismo , Animales , Antineoplásicos/farmacología , Antineoplásicos/uso terapéutico , Biomarcadores , Descubrimiento de Drogas , Humanos , Terapia Molecular Dirigida , Proteómica/métodos , Sarcoma/diagnóstico , Sarcoma/tratamiento farmacológico , Sarcoma/etiología
8.
Artículo en 0 | WPRIM (Pacífico Occidental) | ID: wpr-834301

RESUMEN

Background and Objectives@#Hyaluronan preserves the proliferation and differentiation potential of mesenchymal stem cells. Supplementation of low-concentration hyaluronan (SHA) in stem cells culture medium increases its proliferative rate, whereas coated-surface hyaluronan (CHA) maintains cells in a slow-proliferating mode. We have previously demonstrated that in CHA, the metabolic proliferative state of stem cells was influenced by upregulating mitochondrial biogenesis and function. However, the effect of SHA on stem cells’ energetic status remains unknown. In this study, we demonstrate the effect that low-concentration SHA at 0.001 mg/ml (SHA0.001) and high-concentration SHA at 5 mg/ml (SHA5) exert on stem cells’ mitochondrial function compared with CHA and noncoated tissue culture surface (control). @*Methods@#and Results: Fast-proliferating human placenta-derived mesenchymal stem cells (PDMSCs) cultured on SHA0.001 exhibited reduced mitochondrial mass, lower mitochondrial DNA copy number, and lower oxygen consumption rate compared with slow-proliferating PDMSCs cultured on CHA at 5.0 (CHA5) or 30 μg/cm2 (CHA30). The reduced mitochondrial biogenesis observed in SHA0.001 was accompanied by a 2-fold increased ATP content and lactate production, suggesting that hyaluronan-induced fast-proliferating PDMSCs may rely less on mitochondrial function as an energy source and induce a mitochondrial functional switch to glycolysis. @*Conclusions@#PDMSCs cultured on both CHA and SHA exhibited a reduction in reactive oxygen species levels. The results from this study clarify our understandings on the effect of hyaluronan on stem cells and provide important insights into the effect of distinct supplementation methods used during cell therapies.

9.
Neurointervention ; : 116-124, 2019.
Artículo en Inglés | WPRIM (Pacífico Occidental) | ID: wpr-760595

RESUMEN

PURPOSE: The Pipeline embolization device (PED) is approved in the USA for treating giant and large aneurysms arising from the petrous to superior hypophyseal segments of the internal carotid artery in patients older than 21 years of age. This study investigates off-label PED results in a large cohort. MATERIALS AND METHODS: Retrospective, single-center review of all patients who had off-label PED surgery. RESULTS: Sixty-two aneurysms (48 patients) underwent off-label PED treatment from 2012–2017. There were 44 females and four males (age 21 to 75 years; mean/median, 54.3/55.0 years). The most common presenting symptom was headache (47/62, 75.8%). All aneurysms were in the anterior circulation. Aneurysm size ranged from 1.4 to 25.0 mm (mean/median, 7.6/6.9 mm). Fifty-two aneurysms had post-operative imaging with total/near-complete occlusion of 84.6% (44/52). Aneurysm-based operative near-term complication rate was 9.7% while there were no permanent complications. For aneurysms and headache, 86.7% improved/resolved after embo-surgery, and were four times more likely to have a better clinical outcome (resolved or improved symptoms) after surgery (odds ratio [OR], 4.333; P=0.0325). Left-sided aneurysms had a higher occlusion rate (OR, 20; P=0.0073). Hypertension (OR, 4.2; P=0.0332) and smoking (OR, 7; P=0.0155) were more prone towards aneurysm occlusion. Patients without a family history were 14 times more likely to have favorable imaging outcome (P=0.0405). There is no difference of occlusion rates between untreated and previously treated aneurysms (P=0.6894). Overall, occlusion rate decreased by 14% with an increase of aneurysm size by 1 mm (P=0.0283). CONCLUSION: For anterior circulation aneurysms, the off-label application of PED is as effective and safe as reported for on-label intracranial aneurysms.


Asunto(s)
Femenino , Humanos , Masculino , Aneurisma , Arteria Carótida Interna , Estudios de Cohortes , Cefalea , Hipertensión , Aneurisma Intracraneal , Estudios Retrospectivos , Humo , Fumar
10.
Chinese Journal of Epidemiology ; (12): 180-185, 2019.
Artículo en Chino | WPRIM (Pacífico Occidental) | ID: wpr-738236

RESUMEN

Objective: To study the dose-response relationship between maternal thyroid hormone levels in the first twenty weeks of pregnancy and the infant physical and neuropsychological development. Methods: In this prospective cohort study, a total of 945 women and their children were included. Maternal serum samples during first half of the pregnancy were collected and analyzed for levels of thyroid hormones by using the electro-chemiluminescence immunoassay. Maternal social demographic information was collected by using the a self-administered questionnaire. Physical measurements of newborns and neuropsychological evaluation of infants were performed by doctors of maternal and child health care. Results: The differences in newborns' birth length and head circumference were significant among the newborns of mothers with different percentiles of maternal serum (thyroid-stimulating hormone, TSH) levels (P<0.05). Newborns with maternal TSH level ≥P(95) or <P(5) had significantly lower birth length and birth head circumference, compared with the newborns with maternal TSH level between P(25)-P(75) (P<0.05). Newborns' birth head circumferences showed an inverted U-shaped association with maternal serum TSH level (Y=33.940+0.003X-0.109X(2), F=4.685, P=0.009). The difference in mental development index (MDI) of the infants at 18-30 months were significant among the infants of mothers with different percentiles of maternal serum TSH level (P<0.05). Infants with maternal TSH level ≥P(90) showed lower MDI (6.39, 95%CI: 2.29-10.49, P=0.002) compared with the infants with maternal TSH level between P(25)-P(75). Infant's MDI at 18- 30 months also showed an inverted U-shaped association with maternal serum TSH level (Y=103.249-1.524X-0.939X(2), F=6.616, P=0.001). Conclusions: Maternal TSH level was associated with newborn's birth length, birth head circumference and infant's MDI at 18-30 months. Newborn's birth head circumference and infant's MDI at 18-30 months showed an inverted U-shaped association with maternal serum TSH-Z score.


Asunto(s)
Niño , Femenino , Humanos , Lactante , Embarazo , Peso al Nacer/fisiología , Desarrollo Infantil/fisiología , China , Sangre Fetal/metabolismo , Recién Nacido/sangre , Efectos Tardíos de la Exposición Prenatal/sangre , Estudios Prospectivos , Glándula Tiroides/fisiología , Hormonas Tiroideas/metabolismo , Tirotropina/sangre
11.
Artículo en Inglés | WPRIM (Pacífico Occidental) | ID: wpr-691027

RESUMEN

The American trauma system is designed to provide an organized response to injury. It draws its foundations from lessons learned from America's involvement in the wars of the 20th century as well as principles developed in urban community hospitals. Although run at the local and state government level, it is guided by national societies and has become a world class example. It also currently faces challenges with declining reimbursement and providing equal access to care for all Americans. Professional societies and legislative bodies are continuing to work together for fair and equitable solutions to these issues.


Asunto(s)
Humanos , Centros Traumatológicos , Estados Unidos
12.
Chinese Journal of Epidemiology ; (12): 387-390, 2018.
Artículo en Chino | WPRIM (Pacífico Occidental) | ID: wpr-737967

RESUMEN

Non-syndromic oral clefts (NSOC) are among the most common birth defects. The prevalence of NSOC is 1.13-1.30 per 1 000 live births in China, which is higher than those in other major ethnic groups. The etiology of NSOC is complex and heterogeneous, which involves both genetic and environmental risk factors. Although genome-wide association studies have identified a number of risk loci, these loci can only account for a small proportion of the heritability of NSOC. The next-generation sequencing research provides new ideas for further exploring the genetic risk factors of NSOC. This paper summaries the progress in the next-generation sequencing research of NSOC.


Asunto(s)
Humanos , Pueblo Asiatico/genética , China , Labio Leporino/genética , Fisura del Paladar/genética , Etnicidad/genética , Predisposición Genética a la Enfermedad , Estudio de Asociación del Genoma Completo , Secuenciación de Nucleótidos de Alto Rendimiento , Polimorfismo de Nucleótido Simple
13.
Chinese Journal of Epidemiology ; (12): 487-490, 2018.
Artículo en Chino | WPRIM (Pacífico Occidental) | ID: wpr-737987

RESUMEN

Objective: To understand the dynamic variation of BMI and influencing factors among HIV/AIDS patients receiving highly active anti-retroviral therapy (HAART) in Liuzhou, Guangxi Zhuang Autonomous Region (Guangxi). Methods: HIV/AIDS patients receiving HAART for the first time since 1 January 2013 were selected. Data on BMI was analyzed among patients receiving HAART at baseline,6 months and 12 months after treatment. By using the general linear model repeated measures of analysis of variance, BMI dynamic variations and influencing factors were described and analyzed. Results: The average BMI of 2 871 patients at baseline, 6th months and 12th months appeared as (20.65±3.32), (20.87±3.22) and (21.18±3.20), respectively, with differences all statistically significant (F=18.86, P<0.001). BMI were increasing over time with treatments (F=37.25, P<0.001). Main influencing factors were noticed as: age, sex, marital status, baseline data of CD(4)(+)T cells and the WHO classification on clinical stages. Conclusions: Higher proportion of BMI malnutrition counts was seen among patients before receiving HAART in Liuzhou. BMI of the patients that were on HAART seemed being influenced by many factors. It is necessary to select appropriate treatment protocols on different patients so as to improve the nutritional status of the patients.


Asunto(s)
Humanos , Síndrome de Inmunodeficiencia Adquirida , Terapia Antirretroviral Altamente Activa , Índice de Masa Corporal , Recuento de Linfocito CD4 , China/epidemiología , Infecciones por VIH/tratamiento farmacológico , Modelos Lineales , Estado Civil , Estado Nutricional , Linfocitos T
14.
Chinese Journal of Epidemiology ; (12): 1402-1407, 2018.
Artículo en Chino | WPRIM (Pacífico Occidental) | ID: wpr-738159

RESUMEN

Objective: To describe the study design, the characteristics of participants as well as the pedigrees included in the baseline survey of Fujian Tulou Family Cohort Study. Methods: Fujian Tulou Family Cohort Study was a prospective open cohort study with a biological sample bank. A baseline survey was conducted in Tulou areas of Nanjing county in Fujian province from 2015 to 2018, including questionnaire survey, physical and biochemical indicators examinations, and blood sample collection in adults aged ≥18 years. In addition, family relationship of the participants was also recorded. The pedigree information of the juveniles under 18 years old were also collected. Results: The baseline survey included 2 727 individuals in two clans, of whom 2 373 (87.0%) were adults, and 2 126 participants completed questionnaires, physical examinations and biochemical tests. The average age of the 2 126 participants was (57.9±13.3) years, with 39.4% being males. The current smoking rates in male and female participants were 41.2% and 2.1%, respectively. The corresponding rates of current alcohol consumption were 19.0% and 2.6%. For common chronic diseases, the prevalence rates were 51.3% for hypertension, 9.7% for diabetes and 26.7% for hyperlipemia according to the self-reported disease diagnoses, health examination results and biochemical examination results in class Ⅱ or Ⅲ hospitals. Based on the family relationship information and genealogical data, 710 pedigrees were finally identified, consisting of 5 087 family members. The numbers of five, four, three, and two generations pedigrees were 3, 88, 238 and 381, respectively. The pairs of the first to the fifth degree relatives were 12 039, 2 662, 1 511, 202 and 31, respectively. Conclusion: The establishment of Fujian Tulou Family Cohort provides valuable resources for exploring the genetic risk factors, environmental risk factors and gene-environment interactions contributing to the risk of common chronic diseases.


Asunto(s)
Adolescente , Adulto , Anciano , Femenino , Humanos , Masculino , Persona de Mediana Edad , China/epidemiología , Enfermedad Crónica/etnología , Estudios de Cohortes , Diabetes Mellitus/etnología , Salud de la Familia , Interacción Gen-Ambiente , Predisposición Genética a la Enfermedad/etnología , Hiperlipidemias/etnología , Hipertensión/etnología , Linaje , Estudios Prospectivos , Factores de Riesgo , Encuestas y Cuestionarios
15.
Neurointervention ; : 116-121, 2017.
Artículo en Inglés | WPRIM (Pacífico Occidental) | ID: wpr-730356

RESUMEN

Endovascular embolization or embosurgery of brain tumors can be used to reduce neoplasm vascularity prior to surgical resection. Two challenges with embosurgery relate to insufficient perfusion pressure into the tumor and inadvertent escape of infused agents into parenchymal branches of the adjacent brain. This report describes a multi-catheter and coil technique to improve tumor perfusion and prevent reflux into normal branches.


Asunto(s)
Neoplasias Encefálicas , Encéfalo , Catéteres , Perfusión , Naciones Unidas
16.
J Gen Physiol ; 138(1): 73-93, 2011 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-21670208

RESUMEN

Skeletal muscle activation requires action potential (AP) initiation followed by its sarcolemmal propagation and tubular excitation to trigger Ca(2+) release and contraction. Recent studies demonstrate that ion channels underlying the resting membrane conductance (G(M)) of fast-twitch mammalian muscle fibers are highly regulated during muscle activity. Thus, onset of activity reduces G(M), whereas prolonged activity can markedly elevate G(M). Although these observations implicate G(M) regulation in control of muscle excitability, classical theoretical studies in un-myelinated axons predict little influence of G(M) on membrane excitability. However, surface membrane morphologies differ markedly between un-myelinated axons and muscle fibers, predominantly because of the tubular (t)-system of muscle fibers. This study develops a linear circuit model of mammalian muscle fiber and uses this to assess the role of subthreshold electrical properties, including G(M) changes during muscle activity, for AP initiation, AP propagation, and t-system excitation. Experimental observations of frequency-dependent length constant and membrane-phase properties in fast-twitch rat fibers could only be replicated by models that included t-system luminal resistances. Having quantified these resistances, the resulting models showed enhanced conduction velocity of passive current flow also implicating elevated AP propagation velocity. Furthermore, the resistances filter passive currents such that higher frequency current components would determine sarcolemma AP conduction velocity, whereas lower frequency components excite t-system APs. Because G(M) modulation affects only the low-frequency membrane impedance, the G(M) changes in active muscle would predominantly affect neuromuscular transmission and low-frequency t-system excitation while exerting little influence on the high-frequency process of sarcolemmal AP propagation. This physiological role of G(M) regulation was increased by high Cl(-) permeability, as in muscle endplate regions, and by increased extracellular [K(+)], as observed in working muscle. Thus, reduced G(M) at the onset of exercise would enhance t-system excitation and neuromuscular transmission, whereas elevated G(M) after sustained activity would inhibit these processes and thereby accentuate muscle fatigue.


Asunto(s)
Músculo Esquelético/fisiología , Potenciales de Acción/fisiología , Animales , Femenino , Potenciales de la Membrana/fisiología , Ratas , Ratas Wistar , Sarcolema/fisiología
17.
J Cardiovasc Electrophysiol ; 16(2): 151-61, 2005 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-15720453

RESUMEN

UNLABELLED: Simulating paced electrogram fractionation. INTRODUCTION: Paced electrogram fractionation analysis (PEFA) may identify a re-entrant substrate in patients at risk of ventricular fibrillation (VF) by detecting prolonged, fractionated ventricular electrograms ("fractionation") in response to premature extrastimuli. Numerical simulations of action potential (AP) propagation through human myocardium following such premature stimulation were performed to study the relationship between electrogram fractionation, fibrosis, and changes in AP currents. METHODS AND RESULTS: Activation in a resistive monodomain 2 cm2 sheet of myocardium containing nonconducting fibrous tissue was modeled using standard numerical methods for solutions of partial differential equations using the Priebe-Beukelmann (PB) AP equations. Myocardial fibrosis significantly influenced electrogram morphology. High densities of closely spaced fibrous septa caused functional block and altered propagation paths at short coupling intervals, and produced large increases in electrogram duration similar to those associated with increased risk of VF in clinical studies. Prolongation of the cardiac AP using the heart failure variant of the PB model further increased the amount of fractionation and thereby replicated clinical recordings more closely than did fibrosis alone. Increasing AP dispersion by a variable reduction in the potassium current I(Kr) simulated results seen in patients with the long QT syndrome with an abrupt increase in electrogram duration, while a uniform reduction in I(Kr) alone did not result in fractionated electrograms. In contrast, increases in cytosolic Ca2+ and Ca2+ buffering by troponin to simulate HCM had little effect on fractionation. CONCLUSIONS: These results relate the effects of fibrosis, AP abnormalities, and dispersion of AP duration to the characteristic electrograms recorded in patients at risk of sudden death.


Asunto(s)
Potenciales de Acción , Fibrosis , Corazón/fisiología , Miocardio/patología , Fibrilación Ventricular/diagnóstico , Muerte Súbita Cardíaca/prevención & control , Electrofisiología , Humanos , Modelos Teóricos
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