Obstructive sleep apnea syndrome (OSAS) and hypertension: Pathogenic mechanisms and possible therapeutic approaches

Obstructive sleep apnea syndrome (OSAS), a chronic condition characterized by collapse of the pharynx during sleep, has been increasingly recognized as a health issue of growing importance over the last decade. Recently emerging evidence suggests that there is a causal link between OSAS and hypertension, and hypertension represents an independent risk factor in OSAS patients. However, the pathophysiological basis for patients with OSAS having an increased risk for hypertension remains to be elucidated. The main acute physiological outcomes of OSAS are intermittent hypoxia, intrapleural pressure changes, and arousal from sleep, which might induce endothelial dysfunction, sympathetic activation, renin–angiotensin–aldosterone system activation, lipid metabolism dysfunction, and increased oxidative stress. This brief review focuses on the current understanding of the complex association between OSAS and hypertension.     

医保支付和经济激励：整合的医疗服务系统形成的“引擎”

整合的医疗服务系统的基本内涵是在合适的费用激励约束下促成组织结构整合、服务合作机制建立及其医务人员行为互动而形成的一种动态均衡状态。本文在揭示目前我国医疗服务主体存在非整合行为主要问题的基础上,通过美英澳等国案例分别从组织结构整合、医师行为转变和病人就诊规制3个方面梳理了促进医疗服务系统整合的循证依据。最后还指出要保证这项措施的成功应注意其本身的科学设计与共享的保健路径、有效的评估机制以及其他措施有机结合,实施系统的政策安排。     

Mechanisms of Sublingual Immunotherapy

Allergen-specific sublingual immunotherapy is now recognized to be an efficacious and well-tolerated treatment for allergic rhinitis. Emerging treatment strategies are also aimed at the primary treatment of allergic asthma, particularly allergy to house dust mites. Knowledge of the exact mechanisms of action of sublingual immunotherapy is at a basic level, although there appear to be similarities to the immunological changes seen in subcutaneous immunotherapy. An improved understanding should allow the development of more effective treatment programs and widen the potential use of this form of immunotherapy. This review discusses the possible mechanism of action of sublingual immunotherapy, including data from animal and clinical studies, while comparing this with the current understanding of subcutaneous immunotherapy.     

On revenue maximization for selling multiple independently distributed items

Consider the revenue-maximizing problem in which a single seller wants to sell k different items to a single buyer, who has independently distributed values for the items with additive valuation. The case was completely resolved by Myerson’s classical work in 1981, whereas for larger k the problem has been the subject of much research efforts ever since. Recently, Hart and Nisan analyzed two simple mechanisms: selling the items separately, or selling them as a single bundle. They showed that selling separately guarantees at least a fraction of the optimal revenue; and for identically distributed items, bundling yields at least a fraction of the optimal revenue. In this paper, we prove that selling separately guarantees at least fraction of the optimal revenue, whereas for identically distributed items, bundling yields at least a constant fraction of the optimal revenue. These bounds are tight (up to a constant factor), settling the open questions raised by Hart and Nisan. The results are valid for arbitrary probability distributions without restrictions. Our results also have implications on other interesting issues, such as monotonicity and randomization of selling mechanisms.     

Effects of serum from trypsin inhibitor fed rats on enzyme secretion and protein synthesis by exocrine pancreatic cells

Oral feeding of trypsin inhibitor is known to stimulate rat pancreatic enzyme secretion and cause hypertrophy of the pancreas. In an attempt to detect a possible serum factor(s) responsible, the effects of serum from trypsin inhibitor fed rats on enzyme secretion and protein synthesis by isolated exocrine rat pancreatic cells in suspension were studied.

Serum from trypsin inhibitor fed rats stimulated the secretion of pancreatic enzymes significantly more than serum from control rats. The data suggest that a humoral factor or factors may be involved in the stimulation of pancreatic enzyme secretion by oral trypsin inhibitor.

Serum from trypsin inhibitor fed rats as well as serum from control rats stimulated the ³H-leucine incorporation into protein (protein synthesis) to a significant extent. There was, however, no difference in the effects of the two types of sera in this respect.     

Protein Concentration and Hydrostatic Pressure in Subcutaneous Tissue of Rats in Hypoproteinemia

Protein concentration and hydrostatic pressure were measured in subcutaneous tissue of rats during development of aminonucleoside nephrosis. Samples of interstitial fluid for protein analysis were collected from subcutaneous tissue by a wick method, and hydrostatic pressure was measured by a modified Scholander technique. When the serum protein concentration was reduced from 6.1 to 4.8 g/100 ml, interstitial fluid protein concentration fell from 3.0 to 1.1 g/100 ml. This corresponds to a reduction of calculated oncotic pressures from 18.0 to 13.0 mm Hg and from 7.8 to 3.0 mm Hg in serum and interstitial fluid, respectively, thus leaving a nearly constant net transcapillary oncotic pressure. When serum protein concentration was further reduced to 3.8 g/100 ml, interstitial fluid protein concentration was reduced to 0.5 g/100 ml, reducing net transcapillary oncotic pressure by 2–3 mm Hg. The average hydrostatic pressure in subcutis was 1.0 mm Hg sub-atmospheric under control conditions and did not change during hypoproteinemia. The results indicate that a reduction of interstitial protein concentration is an important factor in preventing edema formation in hypoproteinemia.     

Evidence for a reflex provoking contraction of the renal pelvis (with some comments on its clinical implications)

The effect of swallowing a small quantity of water or of solid food (biscuit) on the renogram curve was observed in 177 patients. Swallowing provoked contraction of the renal pelvis in 63% of the kidneys with a pelvicalyceal system which was neither obstructed nor dilated, with expulsion of a substantial fraction of the contents within 30 s. This did not occur in obstructed or denervated kidneys, nor in patients with a high transection of the spinal cord. Evidence is adduced that this contraction is mediated reflexly. This effect may be used diagnostically to distinguish physiological dilatation from obstruction. The implications when performing and interpreting renography are discussed. Correspondence to: M.V. Merrick     

Epidemiology of injuries in gymnastics

A prospective one-year epidemiological study was carried out to determine the injury incidence and the injury mechanisms in different groups of gymnasts and to identify possible risk factors. A total of 115 gymnasts with a median age of 16 (8-25) were followed through a whole season of median 48 weeks (ranges 40–51). The overall injury incidence was 85 per 100 gymnasts per season, ranging from 27 in subelite males to 157 in subelite females. This high incidence is partly explained by the use of a sensitive injury definition, the high exposure time, and the large proportion of highly competitive gymnasts in the population. Considering the exposure time, however, the incidence is lower than in most other sports, 1.6 per 1000 h of gymnastic activity. Subelite female gymnasts were more commonly injured than other artistic gymnasts, in particular in relation to balance beam exercises and inadequate spotting. Injuries were predominantly localized to the lower extremities (64%) for the whole population of gymnasts. A siwcantly large proportion of the male artistic gymnasts, nevertheless, sustained upper extremity injuries corresponding to their apparatus performance. Most injuries were of mild or moderate severity, the recovery time was, however, considerable (median 30 days, ranges 1–365), and the injuries sustained during competition had a median recovery period of 180 days (7-270). Twenty-two per cent of the injuries resulted in a recovery period of more than 6 months. Re-evaluation of the criteria of the score system for dismount as well as an increased use of spotters during practice and high-risk events are possible measures to prevent serious injuries.     

Effects of Q-switched Nd:YAG Laser on Calcified Tissues

. This study evaluated the effects of the Q-switched Nd:YAG (1064 nm) laser on four types of calcified tissues (dentine, enamel, bone and cementum) at frequencies of 1, 5 and 10 Hz for irradiation times of 100, 100 and 50 s, respectively. Laser fluences per pulse ranged from 30 to 50 J/cm², and pulse duration was 15 ns. To evaluate morphological modifications after laser irradiation, specimens were examined by scanning electron microscopy. Chemical modifications in residual tissues were studied by Raman spectroscopy, and the depth of craters produced by laser impact was analysed as a function of laser fluences. The results showed that tissues were ablated essentially by a photoacoustic mechanism which produced no carbonisation or high melting zone in residual tissues, even though cracks and fractures appeared around craters. Crater depth per pulse was 1–5 μm/pulse depending on the frequency used. Statistical analysis showed that increasing the number of pulses, thereby increasing crater depth led to a decrease in the ablation rate. Raman spectroscopy showed none of the chemical modifications in residual tissues known to occur in heat-treated enamel, dentine and bone after laser irradiation. Paper received 5 June 1997; accepted following revision 11 February 1999.