Bone pattern formation in mouse limbs after amputation at the forearm level

Background: Although urodela amphibians completely regenerate amputated limbs, the potency of limb regeneration in mammalians is very low. In mice and humans, a digit tip regenerates, but no regeneration beyond the digit joint occurs. In this article, we describe the induction of bone formation by BMPs in the forearm, a more proximal region, of neonatal mice. Distal halves of the radius and ulna were removed from limbs amputated at the wrist level in advance, and gelatin rods containing BMPs were grafted in the space of the forearm. BMP‐7 and BMP‐2 were effective. Results: The induction of bone formation depended on the amount of BMP‐7 in grafted gelatin gels. BMP‐7 at over 320 ng/limb induced long bones within 10 days. Cartilage formation was always observed before the bone formation as in the case of normal limb development. The origin of cells responsive to BMP‐7 is not clear, but the formation of large bone tissues in a relatively short time suggests a wide distribution of precursor cells in the limbs. Grafting of dye‐stained mesenchymal tissue fragments suggested that mesenchymal tissues other than the dermis, bone, and joint cartilage are responsive to BMP‐7 and form cartilage/bone. Two long bones induced were arranged in parallel fashion in many cases like the radius and ulna. An agonist of hedgehog promoted the formation of bones in the presence of BMP‐7. Furthermore, bone elements were fused to stump bones to form a single bone. Conclusions: The results suggest the potency of bone pattern regeneration in the amputated forearm of a neonatal mouse. Developmental Dynamics 241:435–441, 2012. © 2012 Wiley Periodicals, Inc.     

Topographic relationship of the ventromedial lymphatic bundle and the superficial inguinal nodes to the subcutaneous veins

The relationships between lymph vessels and veins are of clinical importance for the prevention of injury to collectors and resulting edema after removal of veins. Injection preparations of the lymph vessels and veins showed that on the dorsum of the foot the collectors overcross the veins; however, in all remaining areas they undercross them. Only the great saphenous vein is overcrossed by lymph collectors. It also has accompanying lymph vessels but its vascular sheath, however, does not contain any lymph vessels. The position of the collectors depends on the thickness of the subcutaneous adipose tissue. On the dorsum of the foot the lymphatics are often closely bound up with the corium; on the lower leg, however, they are embedded in the adipose tissue. Some collectors are closely related to perforator veins. In the knee region the lymph bundle ascends dorsomedially to the medial condylus of the femur. On the thigh, where the subcutaneous fatty tissue is thick, the collectors form three layers. The superficial inguinal lymph nodes draining the leg and the external genitalia are situated around the saphenous opening and are closely related to the subinguinal venous star, so that in surgical intervention the collectors of this region are more exposed to danger than in other regions. © 1995 WiIey-Liss, Inc.     

Accessory limb induction on flank region and its muscle regulation in axolotl

Background : Urodele amphibians have high regeneration capability that has been studied for a long time. Recently, a new experimental system called the accessory limb model was developed and becomes alternative choice for amphibian limb regeneration study. Although the accessory limb model has many advantages, an improvement was needed for some specific analysis, such as studying muscle origin. For that purpose, an accessory limb induction on nonlimb regions was attempted. Results: Accessory limb induction on a nonlimb region (flank) was possible by nerve deviation and limb skin grafting. Retinoic acid injections improved the induction rate. The induced limb possessed the same tissue context as a normal limb. Muscle cells were also abundantly observed. It is speculated that the muscle cells are derived from flank muscle tissues, because limb muscle cells are a migratory cell population and the accessory limb was induced apart from the original limb. We also found that migration of the muscle cells was regulated by Hgf/cMet signaling as in other vertebrates. Conclusions: Accessory limb induction was possible even in the nonlimb flank region. The flank‐induced limb would be useful for further analysis of limb regeneration, especially for migratory cell populations such as muscle cells. Developmental Dynamics 242:932–940, 2013. © 2013 Wiley Periodicals, Inc.     

The developing limb and the control of the number of digits

Congenital malformations of the limbs are among the most frequent congenital anomalies found in humans, and they preferentially affect the distal part--the hand or foot. The presence of extra digits, a condition called polydactyly, is the most common limb deformity of the human hand and is the consequence of disturbances in the normal program of limb development. However, despite the extensive use of the developing limb as a classical developmental model, the cellular and genetic mechanisms that control the number and identity of the digits are not completely understood. The aim of this review is to introduce the reader to the current state of knowledge in limb development and to provide the necessary background for an understanding of how deviations from the normal developmental program may lead to polydactyly.     

Gaze direction effects on perceptions of upper limb kinesthetic coordinate system axes

The effects of varying gaze direction on perceptions of the upper limb kinesthetic coordinate system axes and of the median plane location were studied in nine subjects with no history of neuromuscular disorders. In two experiments, six subjects aligned the unseen forearm to the trunk-fixed anterior-posterior (a/p) axis and earth-fixed vertical while gazing at different visual targets using either head or eye motion to vary gaze direction in different conditions. Effects of support of the upper limb on perceptual errors were also tested in different conditions. Absolute constant errors and variable errors associated with forearm alignment to the trunk-fixed a/p axis and earth-fixed vertical were similar for different gaze directions whether the head or eyes were moved to control gaze direction. Such errors were decreased by support of the upper limb when aligning to the vertical but not when aligning to the a/p axis. Regression analysis showed that single trial errors in individual subjects were poorly correlated with gaze direction, but showed a dependence on shoulder angles for alignment to both axes. Thus, changes in position of the head and eyes do not influence perceptions of upper limb kinesthetic coordinate system axes. However, dependence of the errors on arm configuration suggests that such perceptions are generated from sensations of shoulder and elbow joint angle information. In a third experiment, perceptions of median plane location were tested by instructing four subjects to place the unseen right index fingertip directly in front of the sternum either by motion of the straight arm at the shoulder or by elbow flexion/extension with shoulder angle varied. Gaze angles were varied to the right and left by 0.5 radians to determine effects of gaze direction on such perceptions. These tasks were also carried out with subjects blind-folded and head orientation varied to test for effects of head orientation on perceptions of median plane location. Constant and variable errors for fingertip placement relative to the sternum were not affected by variations in gaze direction or head orientation. Thus, the perceived position of the trunk-fixed median plane is not altered by varying gaze direction. The implications of these results for mechanisms underlying kinesthetic perceptions and their potential roles in programming of upper limb movements to visual targets are discussed.     

前臂和肘的桥接再植

目的 在多发肢体离断伤中,利用废弃肢体重建一个有一定功能、外形完整的肢体,即桥接再植。方法 新鲜尸体9具,将一侧上肢的前臂或肘加前臂切除,再用对侧上肢的前臂或肘加前臂,下肢的小腿移植其间。临床实施两例上肢桥接再植。结果 前臂桥接再植和肘加前臂桥接两种方式在临床上切实可行。临床病例一成功,一失败。结论 多肢体离断伤若不能原位再植或移位再植,可以桥接再植。     

Anatomy of the Subcutaneous Lymph Vascular Network of the Human Leg in Relation to the Great Saphenous Vein

The anatomical relationship between lymphatic collectors and veins is of clinical importance for preventing lymphedema secondary to lymphatic collector injury during surgical procedures. To identify areas at risk during surgical interventions, we performed an anatomical study of human legs. The lymphatic collectors of 42 legs of human cadavers were injected with Berlin Blue solution or contrast medium. After fixation, the collectors were dissected and their distances from the great saphenous vein were determined. We found that the lymphatic collectors on the dorsum of the foot ran in close parallel with the corium, whereas in the groin a greater number of lymphatic collectors clustered around the great saphenous vein. The ventromedial bundle that drains into the superficial inguinal nodes included 5–20 lymphatic collectors. The average width of the ventromedial bundle varied between 116 mm at the middle of the lower leg and 32 mm at the groin. Our study cannot confirm the previous observation of a bottleneck of the ventromedial bundle occurring at the knee, but does support the finding of an elongated bottleneck at the thigh and groin draining into the superficial inguinal lymph nodes. In addition, the idea of one sentinel lymph node for a specific region of the leg is not supported by these data. These observations will help surgeons to plan incisions and dissections with respect to lymphatic collectors, thereby minimizing damage to them and reducing complications resulting from unnecessary lymphatic excisions. Anat Rec, 2009. © 2008 Wiley‐Liss, Inc.     

Appendicular skeletal morphology of North American Martes reflect independent modes of evolution in conjunction with Pleistocene glacial cycles

Pleistocene glacial cycles are thought to have driven ecological niche shifts, including novel niche formation. North American pine martens, Martes americana and M. caurina, are exemplar taxa thought to have diverged molecularly and morphologically during Pleistocene glaciation. Previous research found correlations between Martes limb morphology with biome and climate, suggesting that appendicular evolution may have occurred via adaptation to selective pressures imposed by novel and shifting habitats. Such variation can also be achieved through non-adaptive means such as genetic drift. Here, we evaluate whether regional genetic differences reflect limb morphology differences among populations of M. americana and M. caurina by analyzing evolutionary tempo and mode of six limb elements. Our comparative phylogenetic models indicate that genetic structure predicts limb shape better than size. Marten limb size has low phylogenetic signal, and the best supported model of evolution is punctuational (kappa), with morphological and genetic divergence occurring simultaneously. Disparity through time analysis suggests that the tempo of limb evolution in Martes tracks Pleistocene glacial cycles, such that limb size may be responding to shifting climates rather than population genetic structure. Contrarily, we find that limb shape is strongly tied to genetic relationships, with high phylogenetic signal and a lambda mode of evolution. Overall, this pattern of limb size and shape variation may be the result of geographic isolation during Pleistocene glacial advance, while declines in disparity suggest hybridization during interglacial periods. Future inclusion of extinct populations of Martes, which were more morphologically and ecologically diverse, may further clarify Martes phenotypic evolution.     

Limb positioning and initiation: An evolutionary context of pattern and formation

Before limbs or fins, can be patterned and grow they must be initiated. Initiation of the limb first involves designating a portion of lateral plate mesoderm along the flank as the site of the future limb. Following specification, a myriad of cellular and molecular events interact to generate a bud that will grow and form the limb. The past three decades has provided a wealth of understanding on how those events generate the limb bud and how variations in them result in different limb forms. Comparatively, much less attention has been given to the earliest steps of limb formation and what impacts altering the position and initiation of the limb have had on evolution. Here, we first review the processes and pathways involved in these two phases of limb initiation, as determined from amniote model systems. We then broaden our scope to examine how variation in the limb initiation module has contributed to biological diversity in amniotes. Finally, we review what is known about limb initiation in fish and amphibians, and consider what mechanisms are conserved across vertebrates.     

Assessment of biochemical markers in patients with pain of vascular origin

The aim of this study was to analyse blood plasma biochemical parameters in patients with pain of vascular origin. Blood samples were taken from 62 patients (38-86 years of age) with critical limb ischaemia, claudication or lower limb embolism, and from a control group. The samples were taken at the time of hospital admission, 1 h after surgery, 24 h after surgery, and before discharge. Pain intensity was assessed as mild, moderate or intense. The following biochemical parameters were measured: C reactive protein, total protein, albumin, total cholesterol, HDL and LDL cholesterol, glucose, triglycerides, reduced glutathione, malondialdehyde (MDA), and total antioxidative capacity. In the control subjects, MDA increased postoperatively, whereas albumin, total protein, HDL and total cholesterol decreased. In patients with claudication triglycerides and LDL cholesterol also decreased postoperatively. In patients with critical limb ischaemia, reduced glutathione and antioxidative capacity decreased postoperatively and MDA increased. Except in patients with embolism, MDA and C reactive protein increased following surgery. Patients with critical limb ischaemia and embolism reported the worst preoperative pain. In patients with ischaemia, intense pain persisted during the whole postoperative period while in patients with embolism pain continuously decreased. At different time intervals, pain intensity was related to different biochemical markers. We suggest that the described blood plasma changes might play an important role in pain assessment and pain management.     

Early Regulation of Axolotl Limb Regeneration

Amphibian limb regeneration has been studied for a long time. In amphibian limb regeneration, an undifferentiated blastema is formed around the region damaged by amputation. The induction process of blastema formation has remained largely unknown because it is difficult to study the induction of limb regeneration. The recently developed accessory limb model (ALM) allows the investigation of limb induction and reveals early events of amphibian limb regeneration. The interaction between nerves and wound epidermis/epithelium is an important aspect of limb regeneration. During early limb regeneration, neurotrophic factors act on wound epithelium, leading to development of a functional epidermis/epithelium called the apical epithelial cap (AEC). AEC and nerves create a specific environment that inhibits wound healing and induces regeneration through blastema formation. It is suggested that FGF‐signaling and MMP activities participate in creating a regenerative environment. To understand why urodele amphibians can create such a regenerative environment and humans cannot, it is necessary to identify the similarities and differences between regenerative and nonregenerative animals. Here we focus on ALM to consider limb regeneration from a new perspective and we also reported that focal adhesion kinase (FAK)–Src signaling controlled fibroblasts migration in axolotl limb regeneration. Anat Rec, 2012. © 2012 Wiley Periodicals, Inc.     

Differential cardiorespiratory response to combined exercise with different combinations of forearm and calf exercise

The purpose of this study was to examine whether cardiorespiratory responses to combined rhythmic exercise (60 contractions · min^–1) was affected by different combinations of upper and lower limb exercise in seven healthy women. Six different rhythmic exercises were compared: 6-min rhythmic handgrip at 10% of isometric maximal voluntary contraction (MVC) (H10); 6-min rhythmic plantar flexion at 10% MVC (P10); exhausting rhythmic handgrip at 50% MVC (H50); exhausting rhythmic plantar flexion at 50% MVC (P50); H50 was added to P10 (P1OH50); and P50 was added to H10 (H10P50). Exercise duration, after handgrip was combined with plantar flexion (P10H50), was shorter than that of H50, although the exercise duration of HIOP50 was not significantly different from P50. No significant difference was found between the difference from rest in oxygen uptake ( O₂) during H10P50 and the sum of O₂ during H10 and P50. Also, the differences from rest in forearm blood flow ( FBF) and calf blood flow ( CBF) during H10P50 were not significantly different from FBF in H10 and from CBF in P50. In contrast, O₂ in P10H50 was lower than the sum of O₂ in P10 and H50 (P < 0.05), and J FBF in P10H50 was lower than that in H50 (P < 0.05) , while CBF was not significantly different between P1OH50 and P10. The changes in heart rate from rest (d HR) during the combined exercises were lower than the sums of HR in the corresponding single exercises (P < 0.05). These results demonstrated an inhibitory summation of several cardiorespiratory responses to combined exercise resulting in a reduction in exercise performance which would seem to occur easily when upperlimb exercise is added to lower limb exercise.     

Effects of an alternate dissection schedule on gross anatomy laboratory practical performance

The current medical curricula reform that is taking place in many medical schools throughout the world has resulted in less time for gross anatomy laboratory instruction. In response, anatomists are using a variety of approaches (e.g., peer teaching, prosections, plastinated anatomical models, etc.) to adapt to these changes. To accommodate recent curricular reform at the University of Health Sciences College of Osteopathic Medicine, an alternating dissection schedule was implemented. The purpose of this study is to examine the effects of the alternating schedule on gross anatomy laboratory practical performance. Using a Mann-Whitney Rank Sum test, back and upper limb (back-upper limb), and lower extremity laboratory practical performance for students who dissected in every laboratory (EL group; n = 227) is compared to students who dissected in every other laboratory (EOL group; n = 254). For the back-upper limb part of the anatomy laboratory practical, the mean percentage scores for the EL and EOL groups were 74.5% and 68.1%, respectively (P < 0.001). The mean percentage scores for the EL and EOL groups on the lower limb portion of the anatomy lab practical were 75.9% and 75.6%, respectively (P = 0.994). These data suggest that the use of an alternating dissection schedule had an equivocal effect on the students' gross anatomy laboratory practical performance for these two sections. The reasons for these conflicting results may have been related to regional complexity or volume of information, and the sequence in which the regions were taught.     

Prospects for human digit regeneration

The phenomenon of limb regeneration is briefly described, and factors empirically known to enhance regeneration are reviewed. Regeneration is compared to the initial development of the limb, with which it shares many similarities. Recent advances in understanding of the control mechanisms underlying regeneration are described; in particular, the role of retinoids, and their relationship with homeobox-containing genes are considered. The long-term prospects of inducing regeneration in human amputees are considered, and a cautious “thumbs up” is given to this notion, at least in a limited form.     

Why study human limb malformations?

Congenital limb malformations occur in 1 in 500 to 1 in 1000 human live births and include both gross reduction defects and more subtle alterations in the number, length and anatomy of the digits. The major causes of limb malformations are abnormal genetic programming and intra-uterine disruption to development. The identification of causative gene mutations is important for genetic counselling and also provides insights into the mechanisms controlling limb development. This article illustrates some of the lessons learnt from the study of human limb malformation, organized into seven categories. These are: (1) identification of novel genes, (2) allelic mutation series, (3) pleiotropy, (4) qualitative or (5) quantitative differences between mouse and human development, (6) physical and teratogenic disruption, and (7) unusual biological phenomena.     

The femur, fibula, ulna (FFU) complex in siblings

Two siblings affected with the Femur, Fibula, Ulna (FFU) complex are reported. The FFU complex is relatively common, but was not previously reported in relatives.     

单侧损伤大鼠感觉运动皮层引起的前爪运动功能障碍

单侧损伤大脑皮层感觉运动区在8例大鼠引起对侧前爪运动障碍,表现为抓食成功率的明显下降,其中6例还出现前肢优势的转移。这些变化在术后两个月内未见恢复。4例对照大鼠损伤-侧大脑皮层后部均未引起对侧上述指标的改变,表明感觉运动皮层在支配前爪肌肉运动中的重要作用。     

A homozygous ROR2 variant in a family with atypical Robinow syndrome and tetramelic transverse deficiency of autopods

We present five members of a consanguineous Pakistani kinship with the most severe familial tetramelic transverse autopod deficiency reported to date and additionally having some of the common autosomal recessive Robinow syndrome-1 (RRS1) features including short stature, short neck, severe vertebral anomalies of kyphoscoliosis, hemivertebrae, fusion of thoracic vertebrae, broad forehead, and dental crowding. We mapped the locus of this atypical RRS and detected homozygous 8-nucleotide deletion c.1353_1360del (p.(Met452Alafs*4)) in ROR2, the gene responsible for RRS1. We did not find any other variant shared by all affected individuals that could possibly act as a modifier of limb defect. Autopods are affected in RRS1, but severe autopod deficiency is not a characteristic feature. Over 30 biallelic variants dispersed throughout the gene are known in ROR2-related RS, with no genotype–phenotype correlation for specific RRS1 features. Considering together with the sporadic case homozygous for variant p.(Arg442*) and the case homozygous for p.(Arg441Thrfs*16) in a family where heterozygous members have brachydactyly type B1, we propose that homozygous truncating variants that originate at residues 441–452 can cause severe autopod reduction anomalies, suggesting some genotype–phenotype correlation for this particular phenotype.