Epidemiology and Self-Organized Critical Systems: An Analysis in Waiting Times and Disease Heterogeneity

The dominant paradigm in epidemiology is characterized by the absence of a theory of disease that is capable of informing epidemiologic praxis and challenging conventional linear statistical reasoning. This paper has two main objectives: first, it is a reflection over the pathologic process (transition from health to disease state) in line with the nonlinear dynamic paradigm of self-organized critical systems. According to the latter, dynamic processes are characterized by phase transitions, emergence, robustness, far-from-equilibrium dynamics, punctuated equilibria, historically-based mechanic, nonlinearity, irreversibility, and heterogeneity. Further, complex adaptive systems have outcomes with inverse power law (IPL) fits. The article second objective is to test the theory of self-organized critical systems along two paths of epidemiologic investigations. The first path takes the form of a study in waiting times (WT) and attempts to show that their distribution complies with an IPL. The second application shows that hierarchies of patients (generated by cluster analysis) with a complex disease process (diabetes) featuring coupling of their component units (biologic markers of glucose handling) also fit an IPL. The IPL fit is compared with that of a lognormal, the more likely benchmark model for WTs. It is concluded that both the WTs and hierarchies of patients can be interpreted in terms of self-organized critical systems with possible fractal significance. The paper culminates with a theory of disease emphasizing the properties of self-organized complex systems in the epidemiologic context.     

Effects of control measures on the dynamics of COVID-19 and double-peak behavior in Spain

Nonlinear Dynamics - The COVID-19 disease significantly has threatened the human lives and economy. It is a dynamic system with transmission and control as factors. Modeling the dynamics of the...     

Marfan syndrome in Europe

OBJECTIVES: Marfan syndrome (MFS) is a relatively frequent systemic connective tissue disorder with an important physical morbidity and mortality. The influences of MFS on physical problems, perception of severity, and impact on the quality of life and psychosocial well-being have been studied only limitedly. The aim of this study was to assess the association between the severity derived from the reported symptoms and subjectively experienced severity of MFS (expressed as a global judgment), with special emphasis regarding impact on relationships and pregnancies, psychosocial adjustment, and differences between the seven European countries. METHODS: A questionnaire designed specifically for this study and translated in each of the native languages was sent to 2,080 members of one of the patient support groups in Belgium, Denmark, France, Germany, The Netherlands, Switzerland, and the United Kingdom. 857 MFS patients of 13 years and older completed the questionnaire and were included in the data analysis. RESULTS: Physical impairments were scored by perception of severity of physical symptoms by the patients (physical severity perception score) and by their perception of the influence of MFS on their life (subjective severity score). Main discrepancy between physical severity perception and subjective severity score was the higher percentage of patients scoring in physical severity perception as severe (53.5%) compared to subjectively severe (26.5%). 61% of those who scored on the physical severity score as severely affected were designated as being mildly-moderately affected on subjective scoring. Both severity scores increased significantly with age. Two hundred-twenty women have carried 430 pregnancies (1.95 pregnancies/woman), with cardiovascular complications in 1.6%. Prenatal studies for MFS were rejected by 7.6% of MFS patients of 25 years and older, 33.6% were undecided, and 48.5% favored prenatal diagnosis for MFS if available. A positive general self-image was reported by 91.5% of patients. However, more than 90% stated that MFS had a negative influence on their sexual relationships, which they ascribed to negative perception of their body image. CONCLUSIONS: MFS has significant impact on daily life activities, but the majority of patients come to terms with their condition. Acceptance is mainly determined by subjective severity, and less by physical symptoms as reported by the patients themselves. It is important to stimulate a positive attitude towards MFS.     

Down syndrome and parity

OBJECTIVE: To investigate the effect of parity on Down syndrome (DS). METHODS: The study was conducted on data from Northeast Italy (NEI) (1981-1996) and Sicily (ISMAC) (1991-1996) Congenital Malformation Registries. In these areas, all DS births are recorded and confirmed by chromosomal analysis; the NEI Registry also registers pregnancy terminations (TOPs) after prenatal diagnosis of DS. In order to estimate the effect of parity independently of the mother's age and to reduce the truncation effect, different age classes and three classes of parity (1, 2-4, >4) were defined. RESULTS: The study sample consisted of 1,088 consecutive newborns and 169 consecutive fetuses affected by DS. In both NEI and ISMAC samples, we found a significantly increased risk of having a DS child for multiparas > or =35 years of age. In the NEI sample, the inclusion of TOP data did not seem to modify this finding. In the ISMAC sample, a significantly reduced risk for primiparas was found at all ages. CONCLUSIONS: Our data confirm a higher risk of having a DS child in women with parity >4. As this effect is evident only in women > or =35 years age, its practical impact is null because these women are usually offered prenatal diagnosis in any case. However, the mechanisms involved, if this association is true, are very intriguing and the observation should stimulate scientific studies allowing a better knowledge of the nondisjunction mechanism.     

A cytogenetic register of down syndrome in Lebanon

OBJECTIVES: To provide data on the cytogenetics and epidemiology of Down syndrome in our community. METHODS: All cases of Down syndrome diagnosed cytogenetically were entered over a period of 5 years together with data regarding age at referral, parental ages and parity. RESULTS: A total of 280 cases were entered. In postnatal cases, the mean maternal age was 32.19 years and 41.5% of mothers were over 35 years. Only 47.3% of Down syndrome children were diagnosed at less than 1 month of age. The male to female sex ratio of 1.66 is significantly more elevated than that reported in larger registers. CONCLUSIONS: Because of problems inherent to Lebanon, this register does not have a high level of ascertainment, however it appears that the emphasis in a potential prevention programme should be placed on education, information and family planning.     

腕管综合征及其生物力学研究进展

腕管综合征(carpal tunnelsyndrome, CTS)是腕部正中神经受到卡压而引起的一种神经病症. 它所带来的高昂的社会和经济花费使得腕管综合征的研究应运而生, 并且在过去的10年里得到突飞猛进的发展. 常规的手术方式是将腕横韧带(transversecarpal ligament)切开, 以释放正中神经(mediannerve)所受到的压力. 本文不仅对腕管的解剖结构、腕管综合征的症状和发病机理、以及诊断和治疗等方面作了简要概述,还主要从以下几个方面探讨了近年来与腕管综合征相关的生物力学研究工作及其进展: (1)影响腕管内压力的因素,包括腕部姿势, 手指、肌腱或手掌所受外荷载的大小, 以及手工劳作的不同频率等; (2)腕管结构的稳定性研究, 如切开腕横韧带或腕骨间掌横韧带对腕刚度的影响, 以及从动力学角度分析腕管减压手术会导致的腕骨失稳现象; (3)腕管内容物(如肌腱、正中神经)的运动及内容物之间以及腕管内容物与腕横韧带之间的相互作用;(4)腕横韧带的延展实验, 如利用外荷载或移位搭接的方法拉长腕横韧带, 以达到降低腕管内压力的目的. 本文旨在加强人们对腕管综合征尤其是对与腕管综合征相关的生物力学研究进展的了解, 并从生物力学的观点提出利用有限元方法对腕管结构进行三维建模与分析将有可能成为腕管综合征进一步研究的一个重要发展方向.      

Numerical analysis for the efficacy of nasal surgery in obstructive sleep apnea hypopnea syndrome

In the present study, we reconstructed upper airway and soft palate models of 3 obstructive sleep apnea-hypopnea syndrome（OSAHS） patients with nasal obstruction. The airflow distribution and movement of the soft palate before and after surgery were described by a numerical simulation method. The curative effect of nasal surgery was evaluated for the three patients with OSAHS. The degree of nasal obstruction in the 3 patients was improved after surgery. For 2 patients with mild OSAHS, the upper airway resistance and soft palate displacement were reduced after surgery. These changes contributed to the mitigation of respiratory airflow limitation. For the patient with severe OSAHS, the upper airway resistance and soft palate displacement increased after surgery, which aggravated the airway obstruction. The effcacy of nasal surgery for patients with OSAHS is determined by the degree of improvement in nasal obstruction and whether the effects on the pharynx are beneficial. Numerical simulation results are consistent with the polysomnogram（PSG） test results, chief complaints, and clinical findings, and can indirectly reflect the degree of nasal patency and improvement of snoring symptoms, and further,provide a theoretical basis to solve relevant clinical problems.     

Numerical analysis for the effcacy of nasal surgery in obstructive sleep apnea hypopnea syndrome

In the present study, we reconstructed upper airway and soft palate models of 3 obstructive sleep apnea–hypopnea syndrome(OSAHS) patients with nasal obstruction. The airflow distribution and movement of the soft palate before and after surgery were described by a numerical simulation method. The curative effect of nasal surgery was evaluated for the three patients with OSAHS. The degree of nasal obstruction in the 3 patients was improved after surgery. For 2 patients with mild OSAHS, the upper airway resistance and soft palate displacement were reduced after surgery. These changes contributed to the mitigation of respiratory airflow limitation. For the patient with severe OSAHS, the upper airway resistance and soft palate displacement increased after surgery, which aggravated the airway obstruction. The effcacy of nasal surgery for patients with OSAHS is determined by the degree of improvement in nasal obstruction and whether the effects on the pharynx are beneficial. Numerical simulation results are consistent with the polysomnogram(PSG) test results, chief complaints, and clinical findings, and can indirectly reflect the degree of nasal patency and improvement of snoring symptoms, and further,provide a theoretical basis to solve relevant clinical problems.     

猪生殖与呼吸综合征病毒TaqMan荧光定量RT-PCR检测方法的建立

根据GenBank登录的PRRSV保守基因序列设计合成了引物和探针,并对其进行了筛选;对荧光定量PCR的反应条件进行了优化,建立了TaqMan荧光定量RT-PCR检测方法。同时用建立的检测方法对组织病料进行了检测,并与常规RT-PCR做了对比。结果显示,所建立的TaqMan荧光定量RT-PCR方法灵敏度可达5.0×100拷贝/μL,比常规RT-PCR灵敏度高100倍。用该方法对东莞、增城、湛江等地的猪血清和多种组织样品进行了检测。结果,该方法与常规RT-PCR检测方法的阳性符合率为100%。用该方法对3份不同的组织样品进行了重复检测,结果表明,该方法具有良好的重复性,可满足当前PRRS的诊断需要。     

Parents' satisfaction with medical and social assistance provided to children with Down syndrome: experience in Estonia

OBJECTIVE: Parents of children with mental or physical disabilities have been assumed to live more stressful lives than other parents, and people with Down syndrome (DS) may get second-rate care because of their diagnosis. The aim of this work is to investigate the extent of parents' satisfaction with medical and social services in Estonia provided for the DS individuals and their families. METHODS: From 1999 to 2001, fifty-nine DS families answered questionnaires in which we inquired about their satisfaction with medical and social assistance. RESULTS: We found that satisfaction with the quality of the information about DS is low, and most of the parents are not satisfied with the social benefits and rehabilitation options. CONCLUSIONS: The DS families need more medical information about this syndrome.The medical staff has to learn more about how to deliver bad news and how to support parents. More work needs to be done in the area of rehabilitation options and social assistance.     

Economic evaluation of prenatal population screening for fragile X syndrome

OBJECTIVES: This paper models costs and benefits of a population screening programme for pregnant women to detect fragile X syndrome. Given the high lifetime costs of fragile X and the high sensitivity and specificity of testing, such a programme may seem attractive. METHODS: Economic evaluation. RESULTS: Our base case results indicate that such a programme seems close to cost neutral, so may indeed seem attractive for this reason. However, sensitivity analysis shows that assumptions regarding lifetime costs are crucial to results; our results suggest if lifetime costs are under AUD 2.5 million, costs of screening will exceed future costs avoided. CONCLUSIONS: Economic modelling of screening programmes reveals valuable information which might have an influence on the debate on the social value of a population screening programme for fragile X in pregnant women.     

High distress in parents whose children undergo predictive testing for long QT syndrome

OBJECTIVES: To assess the psychological effect of predictive testing in parents of children at risk for long QT syndrome (LQTS) in a prospective study. METHODS: After their child was clinically screened by electrocardiography and blood was taken for DNA analysis, and shortly after delivery of the DNA test result, 36 parents completed measures of psychological distress. RESULTS: 24 parents were informed that at least one of their children is a mutation carrier. Up to 50% of the parents of carrier children showed clinically relevant high levels of distress. Parents who were familiar with the disease for a longer time, who had more experiences with the disease in their family and who received positive test results for all their children were most distressed. CONCLUSIONS: Predictive ECG testing together with DNA testing has a profound impact on parents whose minors undergo predictive testing for LQTS.     

Age at postnatal diagnosis of down syndrome in the northern Netherlands for the period 1981-2000

BACKGROUND: In live-born children with Down syndrome it may be very difficult for the clinician or midwife assisting at the delivery to recognise Down syndrome in newborn babies due to varying physical appearances. Meanwhile more and more therapeutical interventions become available that should start early in life. We were interested in the age at the postnatal diagnosis of Down syndrome, and found no literature on the subject. METHODS: We studied the age at the diagnosis of Down syndrome for live-born babies born in the period of 1981-2000 and registered by the European Registration of Congenital Anomalies in the northern part of The Netherlands. RESULTS: For 289 children, data on the age at the postnatal diagnosis were available, in 70.8% of whom there was suspicion of DS on the day of birth. In 1.7% of the cases, the diagnosis was made after 1 year. Place of birth and the specialty of the health worker assisting at the delivery were associated with age at diagnosis. When the child was delivered at hospital, 96.4% of the Down syndrome cases had been diagnosed within 1 month compared to 81.3% following home delivery. CONCLUSION: In some cases of Down syndrome in live-born babies, the diagnosis is made only after months or a year. The diagnosis was made faster in babies born in hospital compared to those born at home.     

Modeling the posture of a cerebral palsy patient with hamstring syndrome after surgical correction by the Zhuravlev procedure

Cerebral palsy patients with hamstring syndrome are characterized by an increased tension in the posterior two-joint muscles of the thigh. The upright posture of such patients takes the Z-shaped form. The operations according to the procedure proposed by Eggers and the tendon plastic operations proposed by Zhuravlev help the limbs to straighten. In this paper a mathematical model of the patient posture after a Zhuravlev operation is proposed. The numerical results obtained show that a patient underwent such an operation can maintain a relatively upright posture even with an increased tonus of the rectus muscle of the thigh. This is impossible for a patient after an Eggers operation.     

《国民百科》机械条目在中、日的翻译与传播1）

钱伯斯的《国民百科》（Chambers's Information for the People）是传入中国的第一部西方百科全书,但只传入少数条目,其中机械条目于1857年传入中国,译为《重学浅说》.《国民百科》1871年传入日本,机械条目译为《重学》.本文通过机械条目中译本《重学浅说》,日译本《重学》与底本Chambers's Information for the People的对比研究,认为中译本《重学浅说》没有完整翻译且遗漏信息较多,日译本《重学》较为完整地反映了底本;日译本的术语及一些表达方式借鉴了中译本,也有自己的特点.另外,还有新的发现,对以往的部分研究成果予以补充及更正.     

《国民百科》机械条目在中、日的翻译与传播

钱伯斯的《国民百科》（Chambers's Information for the People）是传入中国的第一部西方百科全书,但只传入少数条目,其中机械条目于1857年传入中国,译为《重学浅说》.《国民百科》1871年传入日本,机械条目译为《重学》.本文通过机械条目中译本《重学浅说》,日译本《重学》与底本Chambers's Information for the People的对比研究,认为中译本《重学浅说》没有完整翻译且遗漏信息较多,日译本《重学》较为完整地反映了底本;日译本的术语及一些表达方式借鉴了中译本,也有自己的特点.另外,还有新的发现,对以往的部分研究成果予以补充及更正.