Mathematical model of network dynamics governing mouse sleep-wake behavior

Recent work in experimental neurophysiology has identified distinct neuronal populations in the rodent brain stem and hypothalamus that selectively promote wake and sleep. Mutual inhibition between these cell groups has suggested the conceptual model of a sleep-wake switch that controls transitions between wake and sleep while minimizing time spent in intermediate states. By combining wake- and sleep-active populations with populations governing transitions between different stages of sleep, a "sleep-wake network" of neuronal populations may be defined. To better understand the dynamics inherent in this network, we created a model sleep-wake network composed of coupled relaxation oscillation equations. Mathematical analysis of the deterministic model provides insight into the dynamics underlying state transitions and predicts mechanisms for each transition type. With the addition of noise, the simulated sleep-wake behavior generated by the model reproduces many qualitative and quantitative features of mouse sleep-wake behavior. In particular, the existence of simulated brief awakenings is a unique feature of the model. In addition to capturing the experimentally observed qualitative difference between brief and sustained wake bouts, the model suggests distinct network mechanisms for the two types of wakefulness. Because circadian and other factors alter the fine architecture of sleep-wake behavior, this model provides a novel framework to explore dynamical principles that may underlie normal and pathologic sleep-wake physiology.     

Demand-oriented and demand-driven health care: the development of a typology

In most European countries, there is an increasing demand for demand-oriented and demand-driven approaches in the development of health care policy and the organization of health care services. Both approaches, in which the main focus is on 'the demand', are seen as counterparts of the supply-oriented approach, that has 'the supply' as point of departure. However, there is much confusion about the definition of the concepts. To identify the different views, and to examine to what extent there is consensus in the Netherlands about the concepts of demand-orientation and demand-driven care, a Delphi study was done among 26 experts; scientists, health care insurance companies, health care suppliers, the government, independent advisory bodies and client interest groups. The study resulted in a typology. The similarities and differences between the two concepts were demonstrated in five dimensions; responsibility, control, need-determination, formal embedment of vision in organization and choice. Furthermore, the typology was used to identify existing types of services as being either demand-oriented or demand-driven services. The typology provides an understanding of the similarities and differences between the two concepts, and appears to be a useful tool in identifying services to the extent that they are demand oriented or demand driven.     

Relationship between cigarette format and mouth-level exposure to tar and nicotine in smokers of Russian king-size cigarettes

Differences in length and circumference of cigarettes may influence smoker behaviour and exposure to smoke constituents. Superslim king-size (KSSS) cigarettes (17 mm circumference versus 25 mm circumference of conventional king-size [KS] cigarettes), have gained popularity in several countries, including Russia. Some smoke constituents are lower in machine-smoked KSSS versus KS cigarettes, but few data exist on actual exposure in smokers. We investigated mouth-level exposure (MLE) to tar and nicotine in Russian smokers of KSSS versus KS cigarettes and measured smoke constituents under machine-smoking conditions. MLE to tar was similar for smokers of 1 mg ISO tar yield products, but lower for smokers of 4 mg and 7 mg KSSS versus KS cigarettes. MLE to nicotine was lower in smokers of 4 mg KSSS versus KS cigarettes, but not for other tar bands. No gender differences were observed for nicotine or tar MLE. Under International Organization for Standardization, Health Canada Intense and Massachusetts regimes, KSSS cigarettes tended to yield less carbon monoxide, acetaldehyde, nitric oxide, acrylonitrile, benzene, 1,3-butadiene and tobacco-specific nitrosamines, but more formaldehyde, than KS cigarettes. In summary, differences in MLE were observed between cigarette formats, but not systematically across pack tar bands.     

Activation of ventrolateral preoptic neurons by the somnogen prostaglandin D2

Prostaglandin D₂ (PGD₂) is an extensively studied sleep-promoting substance, but the neuroanatomical basis of PGD₂-induced sleep is only partially understood. To determine potential regions involved in this response, we used Fos immunohistochemistry to identify neurons activated by infusion of PGD₂ into the subarachnoid space below the rostral basal forebrain. PGD₂ increased nonrapid eye movement sleep and induced striking expression of Fos in the ventrolateral preoptic area (VLPO), a cluster of neurons that may promote sleep by inhibiting the tuberomammillary nucleus, the source of the ascending histaminergic arousal system. Fos expression in the VLPO was positively correlated with the preceding amount of sleep and negatively correlated with Fos expression in the tuberomammillary nucleus. PGD₂ also increased Fos immunoreactivity in the basal leptomeninges and several regions implicated in autonomic regulation. These observations suggest that PGD₂ may induce sleep via leptomeningeal PGD₂ receptors with subsequent activation of the VLPO.     

Synthetic studies of roquefortine C: synthesis of isoroquefortine C and a heterocycle

The syntheses of isoroquefortine C and a related heterocycle were achieved by implementation of both intra- and intermolecular vinyl amidation reactions. These accomplishments represent a significant advance in the use of these strategies in the generation of complex molecules.     

护士为患有心力衰竭的移民提供自我照顾咨询的体验

目的 以往关于心力衰竭患者自我照顾的研究强调了其重要性,特别对移民患者而言.护士在为慢性病(如心力衰竭)患者提供相关信息并促进他们积极进行自我照顾方面发挥着重要作用.本研究旨在加强研究者及护士的认识,为患有心力衰竭的移民的自我照顾提供最佳支持.方法 采用质性研究方法.2020年10-12月,对瑞典西部不同类型机构心力衰...