Field processes in stereovision

There is, as yet, no satisfactory theory of stereopsis, despite the fact that our overt knowledge of solid seeing is now about 150 years old, and that contributions to our understanding come today from many fields: ophthalmology, psychology, psychophysics, neurophysiology, computer modelling, and optical-TV display technology. We review herein, and demonstrate for the reader whenever possible, certain key perceptual properties of the stereoscopic event of which any general theory must take account: vector stereoscopy and the neural grid, depth in empty visual fields, the relationship between stereoscopic and cognitive contours, stereoscopic contour formation in the presence of blur (thus, at low levels of central visual acuity), the phenomenon of cortical locking and of neural grid evocation in the presence of either peripheral or central rivalry, certain unusual ranges of figural mismatch and the concept of the horopter in relation to modern single cell electroneurophysiology in animals and to the constancy of visual directions. Some comments are also made on the concept of disparity processing by single cortical neurons, together with a short discussion of the implications of certain views of the genetics of stereovision for the perception of novel random texture sine-wave stereograms.We conclude that any theory pertinent to ophthalmology and visual science must combine the global concepts of cortical integration, the neural lock and the neural grid, herein introduced, with the more classical concepts of particulate or local binocular cortical correspondence. Certain preliminary steps in this direction are presented.     

Isolation and characterization of a cDNA coding for a novel human 17.3K myelin basic protein (MBP) variant

Human fetal spinal cord poly A (+) mRNA was found to direct the synthesis of three major myelin basic protein (MBP) variants with molecular weights of 17K, 18.5K, and 21.5K when translated in reticulocyte lysates. In order to investigate the structural relationships between these MBP variants and their corresponding mouse variants, human fetal spinal cord and mouse brain cDNA libraries were constructed and screened for MBP cDNAs. A number of MBP cDNA clones were isolated and characterized. One of these, PP535 contained the entire coding region of the mouse 14K MBP; and another mouse cDNA clone, PP1.85, was almost full-length and coded for either the 21.5K MBP or the 18.5K MBP. A human clone (KK36), 1,173 nucleotides in length, contained the entire coding region of an MBP variant with a molecular weight of 17,342. The structure of this clone within its coding region is significantly different from the corresponding mouse 17K MBP cDNA. It is missing two sequences found in the mouse 17K MBP cDNA (exons 2 and 5); and it contains a sequence (exon 6) that is missing from the mouse 17K MBP cDNA. Thus, this human 17.3K cDNA codes for a "17K" human MBP variant that is quite different from the corresponding mouse variant and is identical to the human 18.5K MBP except for a deletion of a peptide consisting of 11 amino acids that includes the single tryptophan residue of the 18.5K MBP. An analysis of the structure of this 17.3K human MBP cDNA suggests that the major pathway for splicing the primary human MBP gene product may be different from that in the mouse.     

神经生长因子对脊髓损伤后脊髓组织一氧化氮生成的影响

目的 :探讨神经生长因子 ( NGF)对脊髓损伤保护作用的机制 ,为临床应用提供理论依据。方法 :采用 Allen法以 2 5 g/cm3力致伤大鼠 T8脊髓 ,插蛛网膜下隙导管于术后即刻、2、4、8、12、2 4 h各注入神经生长因子 ( NGF)溶液 ,并与生理盐水组和正常对照组作对照。采用免疫组化法 ( ABC法 )和原位杂交法检测神经元型固有型一氧化氮合成酶 ( nc NOS)在脊髓中的表达。结果 :大鼠伤后脊髓前角运动神经元出现 nc NOS蛋白和 nc NOS m RNA异常表达 ,NGF组与生理盐水组相比较 ,nc NOS蛋白和nc NOS m RNA异常表达明显减少 ( P<0 .0 1或 P<0 .0 5 )。结论 :NGF能通过抑制脊髓损伤 nc NOS的异常表达 ,抑制一氧化氮( NO)过多释放所致的神经毒性作用 ,从而保护了损伤的神经组织。     

恩丹西酮预防椎管内阻滞后寒战的效果

①目的观察麻醉前静脉注射恩丹西酮预防椎管内阻滞后寒战的效果和对腋温的影响.②方法选择腰麻-硬膜外联合麻醉下行经腹全子宫切除术病人160例,随机分为两组,实验组(n=80)麻醉前静脉注射恩丹西酮8mg;对照组(n=80)麻醉前静脉注射生理盐水4mL,观察两组术中平均动脉压、心率、腋温变化和寒战发生情况.③结果实验组8例出现寒战(10.0%),对照组26例出现寒战(32.5%),两组比较差异有显著性(x2=7.05,P＜0.01).两组平均动脉压、心率、腋温变化差异无显著性(t=0.14～1.71,P均＞0.05).④结论恩丹西酮可预防椎管内阻滞后寒战的发生,但对腋温无影响.     

Range of motion of foot joints following total ankle replacement and subtalar fusion

BackgroundIn severe cases of ankle and subtalar arthritis, arthrodesis of the subtalar joint is performed in combination with ankle arthroplasty. In these special cases gait analysis reveals real motion at the replaced tibiotalar joint.MethodsTwenty-three patients affected by ankle and subtalar arthritis, treated either with a 3-component or a 2-component prosthesis in combination with subtalar arthrodesis, were clinically evaluated preoperatively and at a minimum of 1-year follow-up. Gait analysis was performed postoperatively using a multi-segment foot protocol. Foot kinematics were compared to corresponding data from a healthy control group.ResultsClinical scores significantly improved from preoperative to follow-up. The clinically measured passive ankle dorsiflexion/plantarflexion significantly improved at the follow-up. Patients’ normalized walking speed and stride length were significantly lower than those in control. With exception of the ankle frontal-plane motion, sagittal-plane mobility of foot joints was about 50% than that in healthy joints.ConclusionsImprovement in clinical scores was found for both prostheses. Normal spatio-temporal parameters were not restored. In these patients, fusion of the subtalar joint appeared to be compensated by larger frontal-plane motion at the tibiotalar joint.Level of evidenceLevel III- retrospective comparative study.The study was approved by the local Ethics Committee as protocol MAT (protocol registration at clinicaltrials.gov NCT03356951).     

Vascular anatomy of the first metatarsal bone and surgical implications according to the severity of hallux valgus deformity: A cadaveric study

BackgroundVascular injury after hallux valgus surgery is a rare condition but serious complications can ensue.MethodsWe performed an anatomical study using 26 cadaveric lower extremities. We enhanced first metatarsal bone’s (FMB) vascularization by injecting latex. Each specimen was classified according to the severity of hallux valgus deformity (HVD). Then we measured two distances: one between the first tarsometatarsal joint (FTMJ) to the first dorsal branch’s origin, the other between the first metatarsophalangeal joint (MTP) to the dorsal plexus’s origin.ResultsThe distance between the FTMJ and the first dorsal branch to the FMB ranges from 10 mm in normal feet to 15 mm in severe deformed feet. The distance between the MTP and the dorsal plexus’ origin ranges from 20 mm in normal feet to 25 mm in severe deformed feet.ConclusionsUnderstanding the foot’s vascular anatomy has allowed us to adapt surgical landmarks to the severity of the HVD and to avoid post-operative complications.     

凝血酶对人重组内皮细胞衍生IL—8融合蛋白转换作用

本文报道利用基因工程技术在大肠杆菌中表达出入内皮细胞衍生IL-8(EDhIL-8)与细菌蛋白lacZ 的融合蛋白lac-hIL-8和lac-T-hIL-8,后者含有一个人工合成凝血酶切点。EDhIL-8上含有一个凝血酶切点,凝血酶可以将lac-hIL-8及以前表达的MS2-hIL-8水解为有生物活性的天然IL-8,而对含有两个凝血酶切点的lac-T-hIL-8无水解作用。这些结果提示凝血酶的功能不仅依赖于所识别的氨基酸,而且依赖于这些氨基酸形成的构象。     

以骨间背侧动脉为蒂逆行岛状皮瓣的应用解剖学

在60侧灌注血管染料的新鲜成人上肢标本上,观察了骨间背侧血管在前臂背侧的起点、走行和分支,发现该动脉终末支在腕上2.5cm 水平,与骨间掌侧动脉背侧支之间有恒定的吻合支相连,并以此吻合支为蒂,设计了前臂骨间背侧血管逆行岛状皮瓣。