Complex dynamics of adaptation in a nonaxenic microcystis culture. 2. Computer simulation of dinotrophenol effects

A hypothesis was modeled to account for complex 20-day dynamics in a culture of blue-green algae Microcystis and heterotrophic bacteria exposed to 2,4-dinitrophenol (DNP). In trials with little or no added DNP, a limiting factor (light or CO(2)) may cause algal density to fluctuate after 14 days of increase. Such factors may be unimportant at levels of DNP that restrict photosynthesis. Bacterial growth may be limited by organic substrate, and bacteria may be more resistant to DNP than blue-green algae. Hence, at intermediate levels of DNP, substrate provided by increased algal death stimulates bacterial growth more than DNP retards it, causing a bacterial peak. Sorption of DNP to cells may cause the DNP decline. Greater growth and slower DNP decline in experiments with preexposed organisms indicate lower DNP sorption affinity in preexposed cells. Bacterial assimilation of DNP-containing substrate may cause the reappearance of DNP. The model reproduced the fluctuation in algal density after growth was limited and better growth and lower DNP decline with preexposed organisms. Reappearance of DNP occurred, but was not obvious. Bacterial dynamics were least well reproduced. Changes in bacterial constants most affected output. Despite model inadequacies, probable aspects of toxicant action in nature have been revealed. Ecological relationships among populations of different species and genetic differences among individuals may have led to lower than expected toxicity, adaptation, and even growth stimulation. Responses of single species tested in isolation may be inadequate to predict toxicant impact.     

Modeling patient service centers with simulation and system dynamics

We report on the use of simulation modeling for redesigning phlebotomy and specimen collection centers (or patient service centers) at a medical diagnostic laboratory. Research was performed in an effort to improve patient service, in particular to reduce average waiting times as well as their variability. Discrete-event simulation modeling provided valuable input into new facility design decisions and showed the efficacy of pooling sources of variation, particularly patient demand and service times. Initial performance of the redesigned facilities was positive; however, dynamic feedback within the system of service centers eventually resulted in unanticipated performance problems. We show how a system dynamics model might have helped predict these implementation problems and suggest some ways to improve results.     

深圳市铁岗社区基于系统动力学仿真全科团队模式的应用

目的探讨基于系统动力学仿真全科团队模式在社区卫生服务中心的应用。方法选取社区健康服务中心2014年2月—2017年2月收治的600例患者,随机分为实验组和对照组各300例,实验组实施基于系统动力学仿真全科团队模式服务,对照组实施传统全科团队模式服务,比较两组血脂参数变化情况、临床疾病控制效果及管理质量指标。计量资料比较采用t检验,P0.05为差异有统计学意义。结果干预后,实验组焦虑情况评分(AS)、健康档案建案评分(HFCR)、体重指数(BMI)、卫生知识知晓评分(KOHK)、疾病控制评分(DCS)、健康行为评分(HBS)、生活质量评分(QOLS)、合理应用抗生素评分(AUOAS)、治疗依从评分(TCS)、患者满意度评分(PSS)、生活方式评分(LS)均优于对照组,差异有统计学意义(均P0.05);实验组TG、TC、LDL-C低于对照组(均P0.05),HDL-C高于对照组(P0.05)。结论开展基于系统动力学仿真全科团队模式的管理模式,有利于提高患者对疾病的控制,改善患者血脂水平。     

Radioprotective effects of melatonin on radiation-induced cataract

One of the mechanisms proposed to explain lens opacification is the oxidation of crystallins, either by radiation or reactive oxygen species (ROS). It has been shown that melatonin has both an anti-peroxidative effect on several tissues and a scavenger effect on ROS. The purpose of this study was to determine the antioxidant role of melatonin (5 mg/kg/day) against radiation-induced cataract in the lens after total-cranium irradiation of rats with a single dose of 5 Gy. Sprague-Dawley rats were divided into four groups. Control group received neither melatonin nor irradiation. Irradiated rats (IR) and melatonin+irradiated rats (IR+Mel) groups were exposed to total cranium irradiation of 5 Gy in a single dose by using a cobalt-60 teletherapy unit. IR+Mel and melatonin (Mel) groups were administered 5 mg/kg melatonin daily by intraperitoneal injections during ten days. Chylack's cataract classification was used in this study. At the end of the 10th day, the rats were killed and their eyes were enucleated to measure the antioxidant enzymes i.e. the activity of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), and lipid peroxidation level (malondialdehyde (MDA)). Irradiation significantly increased the MDA level, as an end product of lipid peroxidation, and also significantly decreased SOD and GSH-Px activity, emphasizing the generation of increased oxidative stress. Rats injected with melatonin only did not cause cataract formation. Melatonin supplementation with irradiation significantly increased the activity of SOD and GSH-Px enzymes and significantly decreased the MDA level. Total cranium irradiation of 5 Gy in a single dose enhanced cataract formation, and melatonin supplementation protected the lenses from radiation-induced cataract formation. Our results suggest that supplementing cancer patients with adjuvant therapy of melatonin may reduce patients suffering from toxic therapeutic regimens such as chemotherapy and/or radiotherapy and may provide an alleviation of the symptoms due to radiation-induced organ injuries.     

Computer simulation of industrial hazards

Knox, E. G. (1973).Brit. J. industr. Med.,30, 54-63. Computer simulation of industrial hazards. A computer simulation system for a range of industrial hazards provided for model experiments which manipulated (a) the sub-structure of an exposed population in terms of age-distributions and levels of exposure, (b) the nature of the dose/response relationship, (c) the latent interval and its variability, (d) normal life-table expectations, and (e) employment turnover rates. The development of the system led to clarification of terms and concepts with ambiguous current usages, notably in relation to latency. Distinction is made between the notions of `biological' and `observable' latent intervals.

Hypothetical exercises with the model tested its technical validity and at the same time demonstrated in quantitative terms the relationships between `biological' and `observable' latent intervals, employment turnover rates, total mortalities, and the distribution of illnesses and death between those currently employed in the exposing industry, those employed elsewhere, and those retired. Prospects of success for personnel engineering techniques, which manipulate age-distributions of exposed work people in relation to diseases with long latent intervals, were examined.

Published asbestos cancer data were used as a basis for specific model fitting and resulted in a numerical formulation of the exposure/response relationships. Severe exposure results in an increment of risk of death of about 0·02 unit per person per annum for those exposed for around six years, but with higher rates for shorter exposures and lower rates for longer ones. The mean biological latent interval was about 25 years with a coefficient of variation of about 25%. These suppositions explained a range of published data comprehensively and at the same time predicted that (a) persons exposed at severe levels for a working lifetime of 50 years have a 40% risk of dying from asbestos cancer, and (b) industrial populations with moderate to high turnover rates effect a form of extended dose sharing, and non-linearity of the exposure/response relationship results in substantially more deaths than would be the case if the turnover rate were lower.

     

Computer simulation of the effects of errors in birth registration on age-dependent anthropometric methods.

In developing countries birth registration is likely to be delayed, leading to official ages which systematically underestimate the true ages. A computer simulation showed that such official ages underestimate the incidence of malnutrition in a community and lead to misclassification of the nutritional status of many subjects. These errors are more marked below than above 2 years of age. Estimation of the mean delay and its addition to the official ages led to improvement of the results. Above 2 years such estimated ages gave acceptable results; below that age the results were still not acceptable. It is suggested that one method of improving age estimates in large scale anthropometric studies in areas where birth records exist might be to carry out a preliminary survey to estimate the"mean delay in registration. This mean dealy would be added to all official ages and results above 2 years would be accepted. Below 2 years the estimated birth date would be used as a starting point from which the true birth date can be obtained by careful questioning of the parents. Anthropometric results referred to the ages so obtained would give better results than those of uncorrected ages or age-independent anthropometric methods.     

基于系统动力学的2型糖尿病管理模型构建与初步仿真

目的 探索系统动力学模型用于评价2型糖尿病健康管理的可行性,构建适用于本地人口的模型。 方法 以2型糖尿病人口动力为研究对象,参考美国疾病预防控制中心相似模型,通过确定边界、绘制流图,编写方程式,构建系统动力学模型,根据徐汇区的情况调整了亚裔人糖尿病的风险比、人口数、患病数、诊断率、管理率等参数后进行模型初始仿真。 结果 构建了适用于本地人口的2型糖尿病管理系统模型,初始仿真结果显示,从2010－2020年,徐汇区2型糖尿病患病率将从6.6%上升到11.6%,上升趋势未放缓,同期因病死亡率则从32/10万上升到70/10万,上升趋势有所放缓。 结论 系统动力学模型能对2型糖尿病的患病率和因病死亡率等指标进行有条件预测,为评价和调整健康管理机制提供了一种新视角、新方法。     

不同分娩方式对晚期早产儿呼吸系统疾病的影响研究

目的探讨不同分娩方式对晚期早产儿呼吸系统疾病发生及预后的影响。方法以2010年1月-2015年12月在石嘴山市第一人民医院产科出生的晚期早产儿作为研究对象,将符合入选条件的早产儿按照出生胎龄分成34、35和36周3组,然后根据分娩方式再次进行分类,将选择性剖宫产(ECS)的252例早产儿作为ECS组,358例阴道分娩的早产儿作为阴道分娩组,124例急诊剖宫产的早产儿作为急诊剖宫产组。分析分娩方式与不同胎龄的晚期早产儿呼吸系统并发症发生及预后的相关性。结果 ECS组早产儿发生呼吸系统疾病105例,发病率41.7%,急诊剖宫产组早产儿发生呼吸系统疾病56例,发病率45.2%,与ECS组发病率比较,差异无统计学意义(P0.05);358例阴道分娩的早产生儿发生呼吸系统疾病72例,发病率20.1%,ECS组比阴道分娩组具有更高的呼吸系统疾病发病率,差异有统计学意义(P0.05)。34和35周组的晚期早产儿,ECS者比阴道分娩者呼吸窘迫综合征(RDS)发病率更高,差异有统计学意义(P0.05);34、35及36周组的晚期早产儿RDS和湿肺(TTN)发病率比较均是ECS者比阴道分娩者更高,差异有统计学意义(P0.05)。34、35及36周组的晚期早产儿ECS者与阴道分娩者相比,住院时间更长、新生儿重症监护室(NICU)入住率和持续正压通气(CPAP)使用率更高,差异有统计学意义(P0.05)。结论 ECS和急诊剖宫产晚期早产儿呼吸系统疾病发病风险相当;相对于阴道分娩,ECS会增加晚期早产儿呼吸系统疾病发生率及预后不良,临床需尽量控制ECS率。     

Computer simulation of dental professionals as a moral community

Current empirical studies of moral behavior of healthcare professionals are almost entirely focused on self-reports, usually collected under the assumption that an ethical disposition characterizes individuals across various contexts. It is well known, however, that individuals adjust their behavior to what they see being done by those in their peer group. That presents a methodological challenge to traditional research within a community of peers because the behavior of each individual is both the result of norms and a contributor to the norms of others. Computer simulations can be used to address this methodological challenge. A Markov replicator model that runs on an Excel spreadsheet was used to investigate a community with four agent types in the dental community: devious practitioners, ethical practitioners who avoid involvement in the poor ethics of others, ethical practitioners who accept it as part of their professional responsibility to challenge colleagues who act unprofessionally, and those who enforce ethical standards. A panel of leaders in the profession independently estimated parameters for the model and criteria for a possible distribution of agent types in the community. The simulation converged on distributions of the agent types that were very similar to the expectations of the panel. The simulation suggests the following characteristics of such moral communities: The structure of such communities is robust across a wide distribution. It appears that reduction in unethical behavior is more sensitive to the way ethical practitioners interact with each other than to sanctions the enforcement community imposes on unethical practitioners, and that large external interventions will be short lived.     

电脑成了脱发的“罪魁祸首”

使用电脑时间越长的男性越易脱发,这是上海复旦大学附属医院对多名脱发男性进行的调查结果,在电脑前长期工作成了脱发的"罪魁祸首"。此次接受调查的男性为     

Promotion of radiation-induced liver neoplasia by ethanol.

The risk of americium-induced liver cancer in beagle dogs that received long-term dietary ethanol was two to three times that of their nonalcoholic cohorts, even though the radionuclide retention time in hepatic tissue was shortened by the alcohol treatment. Liver malignancies did not occur in the ethanol-treated, nonirradiated controls. An ethanol-induced tumor-promoting effect was not observed in organs or tissues other than the liver.     

Opposite effects on regulation of urea synthesis by early and late uraemia in rats

BACKGROUND & AIMS: Acute and chronic kidney failure lead to catabolism with loss of lean body mass. Up-regulation of hepatic urea synthesis may play a role for the loss of body nitrogen and for the level of uraemia. The aims were to investigate the effects of early and late experimental renal failure on the regulation of hepatic urea synthesis and the expression of urea cycle enzyme genes in the liver. METHODS: We examined the in vivo capacity of urea nitrogen synthesis, mRNA levels of urea cycle enzyme genes, and N-balances 6 days and 21 days after 5/6th partial nephrectomy in rats, and compared these data with pair- and free-fed control animals. RESULTS: Compared with pair-fed animals, early uraemia halved the in vivo urea synthesis capacity and decreased urea gene expressions (P<0.05). In contrast, late uraemia up-regulated in vivo urea synthesis and expression of all urea genes (P<0.05), save that of the flux-generating enzyme carbamoyl phosphate synthetase. The N-balance in rats with early uraemia was markedly negative (P<0.05) and near zero in late uraemia. CONCLUSIONS: Early uraemia down-regulated urea synthesis, so hepatic ureagenesis was not in itself involved in the negative N-balance. In contrast, late uraemia up-regulated urea synthesis, which probably contributed towards the reduced N-balance of this condition. These time-dependent, opposite effects on the uraemia-induced regulation of urea synthesis in vivo were not related to food restriction and probably mostly reflected regulation on gene level.     

Relieved residual damage in the hematopoietic system of mice rescued by radiation-induced adaptive response (Yonezawa Effect)

Existence of adaptive response (AR) was previously demonstrated in C57BL/6J mice. Irradiations were performed by delivering a priming low dose of X-rays (0.50 Gy) in combination with a challenge high dose of accelerated carbon or neon ion particles. AR was characterized by significantly decreased mortality in the 30-day survival test. This mouse AR model (‘Yonezawa Effect’) was originally established by using X-rays as both the priming and challenge irradiations. The underlying mechanism was due to radio-resistance occurring in blood-forming tissues. In this study, we verified the existence of AR and further investigated residual damage in the hematopoietic system in surviving animals. Results showed that the priming low dose of X-rays could relieve the detrimental effects on the hematopoietic system. We observed both an improvement in the blood platelet count and the ratio of polychromatic erythrocytes (PCEs) to the sum of PCEs and normochromatic erythrocytes (NCEs) and a marked reduction of the incidences of micronucleated PCEs and micronucleated NCEs. These findings suggest that the priming low dose of low linear energy transfer (LET) X-rays induced a protective effect on the hematopoietic system, which may play an important role in both rescue from acute lethal damage (mouse killing) and prevention of late detrimental consequences (residual anhematopoiesis and delayed genotoxic effects) caused by exposure to a high challenge dose from low-LET (X-ray) or high-LET (carbon and neon ion) irradiations. These findings provide new knowledge of the characterization of the Yonezawa Effect by providing new insight into the mechanistic study of AR in vivo.     

Protective effects of Korean red ginseng against radiation-induced apoptosis in human HaCaT keratinocytes

Radiation-induced oral mucositis is a dose-limiting toxic side effect for patients with head and neck cancer. Numerous attempts at improving radiation-induced oral mucositis have not produced a qualified treatment. Ginseng polysaccharide has multiple immunoprotective effects. Our aim was to investigate the effectiveness of Korean red ginseng (KRG) on radiation-induced damage in the human keratinocyte cell line HaCaT and in an in vivo zebrafish model. Radiation inhibited HaCaT cell proliferation and migration in a cell viability assay and wound healing assay, respectively. KRG protected against these effects. KRG attenuated the radiation-induced embryotoxicity in the zebrafish model. Irradiation of HaCaT cells caused apoptosis and changes in mitochondrial membrane potential (MMP). KRG inhibited the radiation-induced apoptosis and intracellular generation of reactive oxygen species (ROS), and stabilized the radiation-induced loss of MMP. Western blots revealed KRG-mediated reduced expression of ataxia telangiectasia mutated protein (ATM), p53, c-Jun N-terminal kinase (JNK), p38 and cleaved caspase-3, compared with their significant increase after radiation treatment. The collective results suggest that KRG protects HaCaT cells by blocking ROS generation, inhibiting changes in MMP, and inhibiting the caspase, ATM, p38 and JNK pathways.     

The late effects of exposure to lead fluoride]

Effect of lead fluoride dust on the micronuclear reticulocyte content in the bone marrow was shown. Some functional changes in the testicles and increase in the fetal death rate in exposure to 50 mg/m3 of lead fluoride dust were noted.     

有氧运动和黑果枸杞多糖对慢性脑缺血小鼠的干预及Notch通路相关因子的组织差异表达

目的 了解枸杞多糖对放射性脑损伤海马神经元的保护作用并观察其与氧化应激和PI3K/Akt/mTOR信号通路的关系。 方法 体内实验：SD大鼠,分为对照A（ConA）组、模型A（ModA）组和枸杞多糖A（LBPA）组,每组16只。LBPA组在照射前2周开始采用枸杞多糖50 mg/kg灌胃,ConA组和ModA组予以等剂量生理盐水灌胃,ConA组不予照射。水迷宫检测认知功能,海马组织行尼氏染色,TUNEL染色和检测氧化应激指标MDA、SOD、GSH-Px。体外实验（B）：原代胎鼠海马神经元培养,分组为对照B（ConB）组,模型B（ModB）组,枸杞多糖B（LBPB）组。对ModB组和LBPB组进行放射性处理,ConB组不处理。MTT测细胞活性,annexin V-FITC/PI流式细胞仪检测细胞凋亡,Western blot检测PI3K、Akt、mTOR、Bcl-2、Bax、caspase-3蛋白表达水平。 结果 与ConA组比较,LBPA组大鼠逃避潜伏期和空间探索时间明显缩短,海马神经元细胞形态改善显著,细胞凋亡率显著减少;LBPA组较ModA组MDA含量明显降低,SOD和GSH-Px活性明显升高;与ModB组比较,LBPB组细胞存活率增高,凋亡率降低,PI3K、pAkt、mTOR和Bcl-2表达明显增高,Bax和caspase-3的表达下降。 结论 枸杞多糖能够抑制放射性脑损伤海马神经元的凋亡,其作用可能与PI3K/Akt/mTOR信号通路和氧化应激有关,具备神经保护作用。