骨质疏松性椎体骨折模型的建立

目的:建立大鼠的骨质疏松性椎体骨折模型,探讨骨折愈合程度与X射线、骨结构和力学性能的相互关系,以期能为临床治疗提供科学的指导和理论依据。方法:实验于2005-07/2006-07在解放军兰州军区总医院骨研所完成。实验动物:选择雌性SPF级8个月龄SD大鼠54只。实验分组:采用随机数字法将大鼠分为2组:骨质疏松组和对照组,每组27只。实验干预:骨质疏松组经双背侧手术切除卵巢,对照组行伪手术。术后3个月,所有动物麻醉下,采用L5椎体手术开窗刮除术区内松质骨方法建立人工椎体骨折模型。实验评估:于术后1,2,4,6,8,12周观察两组大鼠腰椎影像学、骨组织切片组织学与受累椎体力学性能。结果:54只SD大鼠全部进入结果分析。①影像学观察:术后两组X射线片示L5椎体有一骨折缺损透光区。对照组在术后6周时原透光区与周围骨质无明显差别,而骨质疏松组原透光区仍清晰可见,于8周时无明显差别。②组织学观察:两组软骨细胞在骨愈合1周时出现,形成软骨岛,但骨质疏松组软骨细胞每高倍视野数量明显少于对照组,另外,软骨细胞改建成成熟骨细胞,骨小梁形成数量,胶原纤维排列与对照组比较有显著性差异。③力学性能:在骨质愈合6～12周,L5椎体的最大载荷、弹性模量、最大应力明显低于同期对照组,差异有显著性意义(P<0.05)。结论:骨质疏松性椎体骨折SD大鼠模型,符合动物模型标准,可用于研究新骨形成与正常骨质结构关系,观察骨质疏松性椎体骨折愈合机制,并证明骨质疏松性松质骨骨折修复过程中,骨折愈合质量降低。     

All currently used measurements of recirculation in blood access by chemical methods are flawed due to intradialytic disequilibrium or recirculation at low flow

Blood flows and recirculations with standard and reversed direction of lines were measured by chemical (urea and creatinine) and ultrasound dilution (saline) methods in 47 chronic hemodialysis patients. Thirty-seven patients had 47 dual-lumen, central vein (CV) catheters: 32 were PermCath (Quinton Instruments Company, Seattle, WA), 6 were Access Cath (MEDCOMP, Harleysville, PA), 3 were Soft Cell PC (Vas Cath, Mississauga, Ontario, Canada) and 6 were SNIJ (experimental catheters). Three of these last catheters had the tip staggered 7 mm, and three had flush tips; PermCath, Access Cath, and Soft Cell PC catheters have the tips staggered 23 to 25 mm. Forty-six catheters were implanted into the superior vena cava/right atrium, and one catheter was implanted through the left saphenous vein into the left iliac vein. The catheters were studied 1 to 31 months after implantation (median, 3.0 months). Ten patients with arteriovenous (AV) graft access were also studied. The stop-flow method was used in catheter dialysis, and the slow-flow method was used to calculate recirculations in AV access dialysis with samples for systemic blood concentrations taken from arterial line both before and after samples from the arterial and venous lines. At 500 mL/min pump speed, actual blood flow was 436+/-18 mL/min (mean+/-SD; range, 407 to 464 mL/min) with standard direction of catheter lines. At 500 mL/min pump speed, the arterial chamber pressure was -330+/-48 mm Hg (mean+/-SD; range, -380 to -225 mm Hg, and the venous chamber pressure was 259+/-48 mm Hg (mean+/-SD; range, 140 to 310 mm Hg). Arterial chamber pressure was less negative, and venous chamber pressure was less positive with SNIJ catheters, which had larger internal diameter (2.1 mm) compared with the other catheters (2.0 mm). Recirculation varied with the catheter design and the location of the catheter tip. In the catheters with tip staggered more than 20 mm and with standard line connection at pump speeds of 50 mL/min and 500 mL/min, recirculations were approximately 1 % and 5%, respectively, when measured by the chemical method. In the same catheters with reversed lines, the recirculations were approximately 5% and 27%, respectively. Inflow failure catheters with reversed lines had similar recirculation values to those of well-functioning catheters with reversed lines. In catheters with tips staggered 7 mm, and with standard connection of lines, recirculations were approximately 3% and 8%, respectively, at pump speeds of 50 and 500 mL/min. With reversed lines, at the same pump speeds, the values were 7% and 12%, respectively. In flush-tip catheters, the recirculation was higher at a 50 mL/min pump speed (approximately 17%) than at a pump speed of 500 mL/min (approximately 13%). The ultrasound dilution method usually gave lower values than the chemical methods, most likely because of overestimation of recirculation by chemical methods. At least triplicate measurements are needed because single measurements by the ultrasound dilution method are associated with substantial variation. We conclude that both currently used methods (stop flow and slow flow) of taking systemic samples for measurements of recirculation by chemical methods are flawed because of disequilibrium and recirculation at low flow.     

Dietary nucleotides: effects on the immune and gastrointestinal systems

Nucleotides (NT) and their related metabolic products play key roles in many biological processes. NT can be synthesized endogenously and thus are not considered essential nutrients. Studies have demonstrated, however, that dietary NT can have beneficial effects; the term "conditionally essential" has been used to describe their role in human nutrition. These nutrients may become essential when the endogenous supply is insufficient for normal function, even though their absence from the diet does not lead to a classic clinical deficiency syndrome. Most dietary NT are rapidly metabolized and excreted. However, some are incorporated into tissues, particularly at younger ages and with fasting. Under conditions of limited NT intake, rapid growth or certain disease states, dietary NT may spare the cost of de novo NT synthesis and optimize the function of rapidly dividing tissues such as those of the gastrointestinal and immune systems. Animals fed NT-supplemented versus non-NT supplemented diets have enhanced gastrointestinal growth and maturation, and improved recovery following small and large bowel injury. Indices of humoral and cellular immunity are enhanced, and survival rates are higher following infection with pathogens. Infants receive NT in human milk, where they are present as nucleic acids, nucleosides, nucleotides and related metabolic products. The NT content of human milk is significantly higher than most cow's milk-based infant formulae. Dietary NT are reported to enhance the gastrointestinal and immune systems of formula-fed infants. Infants fed NT-supplemented versus non-supplemented formula have a lower incidence of diarrhea, higher antibody titers following Haemophilus influenzae type b vaccination and higher natural killer cell activity. These data suggest that human milk NT may contribute to the superior clinical performance of the breastfed infant.     

The Professionalization of International Disaster Response: It Is Time for Midwives to Get Ready

Disasters and humanitarian emergencies due to natural or human origins result in severe and often prolonged suffering of the affected population. Midwives have a role to play in providing assistance because women and their infants experiencing such crises have unique vulnerabilities and needs. This article introduces midwives and other women's health care practitioners to international humanitarian emergency response efforts and describes preparation and training activities they can undertake to get ready to volunteer with an international health aid agency. Various clinical realities and challenges are discussed, including recommended priorities for providing reproductive health care in disaster zones. Common ethical dilemmas in crisis health care settings are also reviewed. By arriving in the field well prepared to participate and collaborate, midwives can make substantial contributions to the safety, health, and comfort of women and their families who have experienced a natural disaster, armed conflict, or disease epidemic.     

School Policies and Practices That Improve Indoor Air Quality*

BACKGROUND: To determine whether schools with a formal indoor air quality management program were more likely than schools without a formal program to have policies and practices that promote superior indoor air quality. METHODS: This study analyzed school-level data from the 2006 School Health Policies and Programs Study, a national study of school health programs and policies at the state, district, and school levels. Using chi-square analyses, the rates of policies and practices that promote indoor air quality were compared between schools with and schools without a formal indoor air quality program. RESULTS: The findings of this study show that 51.4% of schools had a formal indoor air quality management program, and that those schools were significantly more likely than were schools without a program to have policies and use strategies to promote superior indoor air quality. CONCLUSIONS: These findings suggest that schools with a formal indoor air quality program are more likely support policies and engage in practices that promote superior indoor air quality.     

Cholera in India: an analysis of reports, 1997�C2006

Objective

To more accurately define the annual incidence of cholera in India, believed to be higher than reported to the World Health Organization (WHO).

Methods

We searched the biomedical literature to extract data on the cases of cholera reported in India from 1997 to 2006 and compared the numbers found to those reported annually to WHO over the same period. The latter were obtained from WHO’s annual summaries of reported cholera cases and National health profile 2006, published by India’s Central Bureau of Health Intelligence.

Findings

Of India’s 35 states or union territories, 21 reported cholera cases during at least one year between 1997 and 2006. The state of West Bengal reported cases during all 10 years, while the state of Maharashtra and the union territory of Delhi reported cases during nine, and Orissa during seven. There were 68 outbreaks in 18 states, and 222 038 cases were detected overall. This figure is about six times higher than the number reported to WHO (37 783) over the same period. The states of Orissa, West Bengal, Andaman and Nicobar Islands, Assam and Chhattisgarh accounted for 91% of all outbreak-related cases.

Conclusion

The reporting of cholera cases in India is incomplete and the methods used to keep statistics on cholera incidence are inadequate. Although the data are sparse and heterogeneous, cholera notification in India is highly deficient.