踝间线足背动脉在全膝关节置换术髓外定位中的临床应用

目的探讨踝关节力学中心体表标志点,为全膝关节置换术(TKA)下肢力线的准确定位提供依据。方法对64例膝骨关节炎(OA)终末期患者实施初次TKA治疗,股骨侧采用髓内定位,胫骨侧采用髓外定位,实验组(34例)踝关节力学中心位于踝间线足背动脉处,对照组(30例)定位则按传统方法进行。术后测量患者胫骨假体胫骨角及后倾角。结果患者均获得随访,时间4~6年。胫骨假体胫骨角平均度数:实验组为(2.1±0.2)°,对照组为(2.6±0.1)°,差异有统计学意义(P0.05);胫骨假体后倾角:实验组为(3.1±0.2)°,对照组为(3.3±0.1)°,差异无统计学意义(P0.05)。实验组胫骨假体力线优于对照组。结论踝间线足背动脉定位可靠,其标示简单易行,能提高胫骨假体力线的精确度,不失为TKA术中踝关节力学中心定位的理想参考。     

早产与足月小于胎龄儿第1年体格生长差异的队列研究

目的 探讨早产小于胎龄儿(small for gestational age,SGA)在生后1年内的体格生长变化趋势是否与足月SGA存在差异,为早产SGA生后体格生长随访监测提供参考依据.方法 采用前瞻性队列研究,收集2013年9月至2015年6月在重庆医科大学附属儿童医院儿童保健科随访的早产SGA 54人,足月SGA 181人.分别在1、3、6、12月龄(早产SGA在纠正胎龄的1、3、6、12月龄)测量体质量、身长、头围,采用Z积分计算体格水平和生长速度.结果 ①早产SGA生后快速追赶生长发生在纠正年龄1月龄后,而足月SGA在生后即开始;早产和足月SGA在前6个月追赶生长率均达63.0％.②早产SGA未纠正胎龄的体质量Z值在6、12月龄(t=-1.189、-0.911,P=0.236、0.363),身长、头围Z值在12月龄(t=-0.855、-1.078,P=0.394、0.282)与足月SGA比较差异无统计学意义.③早产SGA的体质量增长速度在1～3、＞3～6月龄(t=4.685、3.787,P＜0.01),身长、头围在1～3、＞3～6、＞6～ 12月龄追赶速度明显快于足月SGA(t=3.487、3.626、4.179,t=5.158、3.001、4.641,P＜o.o1).但在1月龄内体质量、身长追赶速度均慢于足月SGA(t=-6.384、-4.821,P＜0.01),甚至低于出生时Z值水平(△Z＜0).结论 早产SGA追赶生长的发生晚于足月SGA,体格生长水平可在1岁时追赶上足月SGA,在1岁内生长潜力大于足月SGA,在纠正年龄1月龄内易发生宫外生长迟缓.     

辣椒素对超重及肥胖成人体成分的影响

目的 探讨辣椒素对超重及肥胖成人的骨骼肌肉和脂肪分布等体成分指标的影响.方法 选取体质指数(BMI) ≥24的研究对象20例,随机双盲分为辣椒素组和对照组各10例,分别给予辣椒素4 mg/d和0.05 mg/d.干预前和干预4周后,检测人体体成分.结果 干预4周后,辣椒素组研究对象的BMI、肥胖程度、内脏脂肪区域、体脂百分比和臀围较干预前明显降低(P＜0.05),右下肢肌肉量明显上升(P＜0.05).结论 辣椒素可能通过增加肌肉量和减少体脂聚积,从而减轻超重和肥胖.     

Decreased heat tolerance is associated with hypothalamo-pituitary-adrenocortical axis impairment

When rats are exposed to heat, they adapt themselves to the stressor with a wide inter-individual variability. Such differences in heat tolerance may be related to particularities in the hypothalamo-pituitary-adrenocortical (HPA) axis activation. To further this hypothesis, 80 rats instrumented with a telemetric device for abdominal temperature (Tabd) measurement were separated into two groups. Sixty-eight rats were exposed during 90 min at an ambient temperature of 40 degrees C, and 12 rats to an ambient temperature of 22 degrees C. Heat-exposed rats were then divided into three groups using the a posteriori k-means clustering method according to their Tabd level at the end of heat exposure. Heat tolerant rats (Tol, n=30) exhibiting the lowest Tabd showed a slight dehydration, a moderate triglyceride mobilization, but the highest plasma adrenocorticotropic-hormone (ACTH) and corticosterone levels. Conversely, heat exhausted rats (HE, n=14) presented the highest Tabd, a higher degree of dehydration, a greater metabolic imbalance with the lowest plasma triglyceride level and the highest lactate concentration, as well as a lowest plasma corticosterone and ACTH levels. The fact that the proopiomelanocortin (POMC) mRNA content within the pituitary was low despite of a high c-fos mRNA level is also relevant. Current inflammatory processes in HE rats were underlined by lower inhibitory factor kappaBalpha (IkappaBalpha) mRNA and higher tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta) mRNA. In conclusion, data show that intolerance to heat exposure is associated to an HPA axis impairment, possibly related to changes occurring in the IkappaBalpha and TNF-alpha mRNA levels.     

Dopamine D2 receptor stimulation inhibits cold-initiated thermogenesis in brown adipose tissue in conscious rats

Dopamine D(2)-like receptor agonists cause hypothermia. We investigated whether inhibiting heat production by interscapular brown adipose tissue (iBAT), a major thermogenic organ in rats, contributes to hypothermia caused by dopamine D(2)-like receptor agonists. Temperature of iBAT and tail artery blood flow were measured in conscious rats. Activity in postganglionic sympathetic nerves supplying iBAT was assessed in anesthetized rats. Conscious rats were housed in a warm cage maintained at 26-28 degrees C and then transferred to a cold cage at 5-10 degrees C to induce iBAT thermogenesis. Cold exposure increased iBAT temperature (+0.7+/-0.1 degrees C, 30 min after transferring to the cold cage, P<0.01, n=54). The mixed dopamine D(2)/D(3) receptor agonist, 7-hydroxy-2-(di-n-propylamino)tetralin (7-OH-DPAT, 0.5 mg/kg s.c.) reversed the cold-induced increase in iBAT temperature (-2.8+/-0.2 degrees C at 30 min after 7-OH-DPAT treatment during cold exposure vs. +0.3+/-0.1 degrees C at 30 min after vehicle treatment during cold exposure, n=8). These temperature changes were blocked by pre-treatment with the D(2) receptor antagonists spiperone (20 microg/kg i.p.) and L-741,626 (2.5 mg/kg i.p.), but not by the selective D(3) receptor antagonist SB-277011A (10 mg/kg i.p.). Another mixed dopamine D(2)/D(3) receptor agonist, quinpirole (0.5 mg/kg s.c.) also reversed cold-induced iBAT thermogenesis, and this effect was also prevented by pre-treatment with spiperone, but not with a peripherally acting dopamine receptor antagonist, domperidone (2 mg/kg s.c.). Neither 7-OH-DPAT nor quinpirole reversed cutaneous vasoconstriction elicited by cold exposure. In anesthetized rats, quinpirole (0.5 mg/kg i.v.) abolished iBAT sympathetic nerve discharge elicited by cooling the trunk, and this change was reversed by spiperone (20 microg/kg i.v.). These results demonstrate that activation of CNS dopamine D(2) receptors inhibits sympathetically-mediated iBAT thermogenesis in response to cold exposure. Furthermore, they suggest that in rats hypothermia induced by dopamine D(2) receptor agonists in cold environments is mainly due to decreased heat production rather than to increased heat loss.     

Optimal ICSI timing after the first polar body extrusion in in vitro matured human oocytes

BACKGROUND: This study was conducted to investigate the fertilization and embryo development of human oocytes injected at different time intervals after extrusion of the first polar body (PB) following in vitro maturation (IVM) in IVM cycles. Also, we evaluated whether spindle imaging could serve as a tool to determine the optimal ICSI time. METHODS: Oocytes were collected from 43 women with polycystic ovary syndrome. Metaphase I (MI) oocytes after in vitro culture for 24 h from germinal vesicle stage were subjected to ICSI according to time after first PB extrusion. The intervals were: within 1 h (n=38); 1-2 h (n=30); 2-4 h (n=26);4-6 (n=28) and 6-8 h (n=40). In some MI oocytes, viable spindle location was evaluated using Polscope microscopy at different time intervals after first PB extrusion. RESULTS: Fertilization rate of the MI oocytes injected within 1 h after first PB extrusion was low (15.8; 6/38) (P<0.01 versus all other times). In contrast, the fertilization rate was 80, 92.3, 82.1 and 85% for oocytes injected 1-2, 2-4, 4-6 and 6-8 h after first PB extrusion, respectively. Development of good-quality embryos was not significantly different among all the groups. Interestingly, all the oocytes injected within 1 h after first PB extrusion were in Telophase I. CONCLUSIONS: Human oocytes matured in vitro needed at least 1 h after first PB extrusion to complete nuclear maturation. Use of a live spindle imaging system can help to decide the timing of ICSI for oocytes matured in vitro.     

Sex hormones, sleep, and core body temperature in older postmenopausal women

STUDY OBJECTIVES: Assessment of relationships between polysomnographic sleep, sex hormones, and core body temperature in postmenopausal women. DESIGN AND PARTICIPANTS: Ten women aged 57 to 71 years, at least 5 years past menopause. SETTING: Laboratory of Human Chronobiology at Weill Cornell Medical College. INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: Lower estradiol (E2) and higher luteinizing hormone (LH) levels were significantly correlated with indices of poor sleep quality. Relationships between LH and polysomnographic variables were more robust than those for E2. Significant increases from basal LH levels (i.e., LH pulses) occurred more frequently after sleep onset than prior to sleep onset, and 30 of 32 of these LH pulses occurred prior to long awakenings from sleep. In addition, higher body core temperature prior to and during sleep was significantly correlated with poorer sleep efficiency and higher LH levels. CONCLUSIONS: Most investigations of relationships between sleep, sex hormones, and body temperature have focused on perimenopausal women, menopausal phenomena such as hot flashes, the role of declining estrogen, and treatment with exogenous estrogen. The current results suggest that altered levels of both sex steroids and gonadotropins may contribute to sleep disturbance in older women and confirm the results of previous studies indicating that higher body core temperature is associated with poorer sleep quality, even in women without vasomotor symptoms. The findings also raise the possibility of alternate treatment avenues for menopause- and age-related sleep disturbance that focus on altering LH levels.     

A Recruitment Model of Quasi-Linear Power-Law Stress Adaptation in Lung Tissue

When lung tissue is subjected to a step in strain, it exhibits a stress adaptation profile that is a power function of time. Furthermore, this power function is independent of the strain, even though the quasi-static stress–strain relationship of the tissue is highly nonlinear. Such behavior is known as quasi-linear viscoelasticity, but its mechanistic basis is unknown. We describe a model of soft tissue rheology based on the sequential recruitment of Maxwell bodies. The model is homogeneous in its elemental constitutive properties, yet predicts both power-law stress relaxation and quasi-linear viscoelasticity even when the stress–strain behavior of the model is nonlinear. The model suggests that stress relaxation in lung tissue could occur via a sequence of micro-rips that cause stresses to be passed from one local stress bearing region to another.     

Regional Variations in the Apparent and Tissue-Level Mechanical Parameters of Vertebral Trabecular Bone with Aging Using Micro-Finite Element Analysis

The aim of this study was to obtain the apparent and tissue-level mechanical parameters of vertebral cancellous bones using micro-finite element analysis, and to identify the regional variations and their relative differences with respect to aging. Ninety trabecular specimens were obtained from six normal L4 vertebral bodies of six male cadavers in two age groups, three aged 62 years and three aged 69 years, and then were scanned using a high-resolution micro-Computed Tomography (micro-CT) system. The obtained micro-CT reconstruction models were then converted to micro-finite element models. Micro-finite element analyses were done to determine the apparent Young’s moduli and tissue-level Von Mises stress distribution for each trabecular specimen on the longitudinal direction, and medial–lateral and anterior–posterior directions (transverse directions), respectively. Regional variations about the mechanical parameters at both apparent and tissue levels in different transverse layers and vertical columns within and between the two age groups were then analyzed. The results showed significant decreases in the apparent Young’s moduli in each direction with aging, and those in the two transverse directions decreased more with aging compared with the longitudinal direction. Furthermore, there were no statistically significant differences between the mechanical parameters in the two transverse directions in both age groups. This study offered an insight into the distributions and variations of mechanical properties within a vertebral body. The mechanical parameters calculated from this study may help in a better understanding of regional fracture risks and the vertebral fracture mechanism in the prevention of osteoporotic fracture in elder individuals.