Paederus dermatitis: An easy diagnosable but misdiagnosed eruption

Paederus dermatitis is a perculiar irritant contact dermatitis characterised by erythemato-bullous lesions of sudden onset on exposed areas of the body. The disease is provoked by an insect belonging to genusPaederus. This beetle does not bite or sting, but accidental brushing against or crushing the beetle over the skin provokes the release of its coelomic fluid which contains paederin, a potent vesicant agent. Due to the pathogenic mechanism, the morphology and location of the dermatitis change from case to case. The lesion usually resembles the accidental dropping of a caustic or hot liquid. The uncommon association of acute dermatitis with minimal or no complaints, which would be noteworthy in the case of chemical or thermal burns, facilitates diagnosis which is corroborated by the season and by the case history.     

A force transducer and a length-ramp generator for mechanical investigations of frog-heart myocytes

An apparatus for studying the mechanics of isolated frog heart myocytes is described. The cells are held horizontal in a through of Ringer solution by means of two suction micropipettes. Myocyte force is measured with an opto-electronic system recording the deflection of the tip of one micropipette, which acts as a cantilever force probe. The force probes are selected for compliance according to the force a myocyte is expected to develop in a given condition, so as to limit myocyte shortening during force development to no more than 1% of the slack cellular length (l ₀). The other micropipette, which is stiff relative to the forces measured, is mounted on an electromagnetic-loudspeaker motor by which controlled-velocity length changes, of preset size and in either direction, are imposed on myocytes. The force transducer has a sensitivity of 5–10 mV/nN, with a frequency response of 700–900 Hz in Ringer solution and a resolution of 0.5–1 nN. The motor with a suction micropipette can complete controlled-velocity length ramps within 1.5–2.0 ms, across a range of ±100 m at a resolution of 8.0 nm. These values correspond, for frog-heart myocytes 200 m and 400 m long, to 25%–50% l ₀ and 0.002%–0.004% l ₀ respectively.     

Change in the accommodative force on the lens of the human eye with age

The aim of the study was to determine the age-dependence of the accommodative force on the lens in order to make it clear whether the causes of presbyopia are due to lenticular or extralenticular changes. A finite element model of the lens of an 11-, 29- and 45-year-old human eye was constructed to represent the fully accommodated state. Subsequently, the force that was needed to mould the lens into its unaccommodated state was calculated. The force on the lens appeared to be preserved with age, with only a slight increase to a value of approximately 0.06N. In conclusion, the preservation of the net force delivered by the extralenticular ciliary body indicates that the causes of presbyopia must be ascribed to lenticular changes.     

普高与空军青航校毕业生抗荷体质差异

目的 对比青少年航空学校学员与普通高中生招飞抗荷体质相关指标差异,探索青少年航空学校抗荷体质训练成果并为训练方案优化提供科学依据。方法 随机抽取参加2022年空军招飞医学选拔定选阶段的部分青航校高三学员与同年级普通高中生作为研究对象,青航校学员按照既定培养方案,在高中阶段开展专项抗荷体质训练,并通过问卷调查收集普通高中生体育锻炼情况,纳入身体尺寸、身体成分、肌肉力量等指标进行对照研究,采用SPSS.26进行统计学分析。结果 青航校学员身高、四肢长、平静胸围、体质量均显著高于普通高中生(P＜0.05),二者坐高无统计学差异。青航校学员SMI显著高于普通高中生(P＜0.05),但体脂率对比无显著差异(P＞0.05);青航校学员背力与腿力均值/峰值显著高于普通高中生(P＜0.05);SMI与抗荷力量呈显著正相关,体脂率与抗荷力量不存在显著相关。青航校学员与普通高中生SMI分布存在差异,青航校学员的高SMI比例更高、低SMI比例更低(P＜0.05),而青航校与普通高中生体脂率分布无统计学差异(P＞0.05);结论 青航校抗荷体质训练在抗荷相关肌肉力量提高方面成效显著,但是在体脂率控制方面仍存在改进空间,未来青航校抗荷体质训练需要兼顾肌肉训练与体脂控制。     

测试新鲜猪股骨干钻削进给力

目的 采集新鲜猪股骨干不同骨质层和骨段的钻削进给力数据,为骨科虚拟现实手术系统钻削力反馈信号的输出提供依据。方法 改装万能材料试验机和手持可调速电钻(Φ5.0 mm钻头),构建生物骨骼钻削性能参数采集系统,分别以转速n ＝500,800,1 200 r/min和进给速度v ＝30,50,70 mm/min采集6具新鲜成熟猪股骨干162个标记点的钻削进给力f,分析其与相应组织和部位的关系。结果 新鲜猪股骨干同一标记点双侧骨皮质处进给力最大（fmax＝103.63~142.59 N）,髓腔处最小（接近于0）,股骨干中段进给力（f4,5,6＝124.69N）较两端（f1,2,3,7,8,9＝121.84 N）大;当v ＝30 mm/min、n ＝1 200 r/min时,钻削进给力最小（fmin＝106.04 N）;当v ＝ 70 mm/min、n ＝500 r/min时,钻削进给力最大（fmax＝139.84 N）。结论 改装的生物骨骼切削性能参数采集系统能有效采集生物骨骼的钻削进给力数据;骨骼钻削进给力与骨质的组织结构、电钻转速及进给速度有密切关系,其中骨质结构越密、电钻转速越小、进给速度越大,骨骼钻削进给力越大,反之越小。实验所获得新鲜猪股骨干钻削进给力数据及其变化趋势,可为虚拟骨科手术系统力反馈输出信号设置提供依据。     

Quantitative determination of the contact pressure distribution in the hip joint during gait

Summary The objective of this investigation was the experimental determination of the contact pressures in the hip joint for characteristic phases of the gait cycle. The joint forces determined in vivo with telemetric endoprosthesis by Bergmann et al. (1993) were converted into a pelvic reference system, based on kinematic gait analysis. In eight cadaveric hip joints (age 18–75 yrs.) the reaction forces were applied corresponding to four phases of the gait cycle (heel strike, mid-stance, heel off, toe off) and the pressure distribution determined with FUJI pressure sensitive film. We found maxima of 10 MPa during mid stance. The areas of highest pressure were located in the ventro-superior aspect of the acetabulum (anterior part of the acetabular roof) and in the dorso-inferior aspect of the lunate surface. The pressure distribution was relatively constant during the four phases and the maxima did not vary proportional to the applied load. The normal pressure distribution in the hip appears to be determined by the physiological incongruity of the articular surfaces and the inhomogeneous bony support of the acetabulum. During operative interventions this normal load transfer should be restored as accurately as possible.      

飞行员直立位前后心率变异时域与频域的变化

为了探讨体位变化对心血管自主神经调节机制及心率变异（ＨＲＶ）特征的影响，对６０名健康男性战斗机飞行员进行了直立位（９０°）前后短时（５ｍｉｎ）时域与频域ＨＲＶ指标相关性研究，结果显示：直立位前后短时ＨＲＶ指标（包括时域和频域）存在明显差异，某些短时ＨＲＶ时域与频域指标，如卧位，５ｍｉｎＲ－Ｒ间期均值（ＭＲＲ５）与高频（ＨＦ）呈明显正相关，与高频／低频（ＨＦ／ＬＦ）呈明显负相关；直立位；ＭＲＲ５与低     

应用苯妥英钠后急性低压缺氧条件下大鼠脑单胺递质的变化

目的探讨苯妥英钠（Ｄｉｐｈｅｎｙｌｈｙｄａｎｔｏｉｎ，ＤＰＨ）在急性缺氧条件下的脑保护作用。方法给大鼠应用ＤＰＨ，用荧光分光法检测其在低压舱模拟升空７．５ｋｍ后１ｈ、２ｈ的脑匀浆单胺递质含量，同时观察脑细胞形态学改变。结果ＤＰＨ实验组在缺氧１ｈ及２ｈ时脑多巴胺和５－羟色胺含量升高（Ｐ＜０．０５），而脑去甲肾上腺素在缺氧１ｈ时降低（Ｐ＜０．０５），缺氧２ｈ恢复正常。电镜形态学观察，低压缺氧条件下对照组大鼠脑细胞水肿，线粒体嵴严重缺失，细胞核明显变形；应用ＤＰＨ的实验组细胞形态基本正常。结论给大鼠应用苯妥英钠后，在急性缺氧条件下，动物脑单胺递质含量的变化可能与缺氧适应或耐受的形成有关。     

Relation between vertical orientation and stability of acetabular component in the dysplastic hip simulated by nonlinear three-dimensional finite element method

In acetabular dysplasia, more vertical orientation of the acetabular component is often used to minimize the superolateral bone grafting. This study was designed to determine the effects of vertical orientation of the cup on the stability and polyethylene wear of the acetabular component in uncemented total hip arthroplasty (THA). Three-dimensional finite element models of the hemipelvis with dysplastic acetabulum were developed. Metal-backed hemispherical cups were placed in the true acetabulum with abduction angles of 35, 45, 55, and 65 degrees. It was found that more vertical orientation of the cup was associated with larger relative motion of the metal shell between the acetabulum and metal shell. Furthermore, tilting and torsional shear stresses in the model of the cup abduction angle of 65 degrees were found to be 1.7 times larger than that in the model with 35 degrees at the bone-metal shell interface. More vertically oriented cups caused larger contact stresses at the articulating surfaces of the polyethylene liners. The results suggest that the abduction angle of the acetabular component significantly influences cup loosening and polyethylene wear in THA.