Kinematic effects of inertia and friction added by a robotic knee exoskeleton after prolonged walking.

The capabilities of robotic gait assistive devices are ever increasing; however, their adoption outside of the lab is still limited. A critical barrier for the functionality of these devices are the still unknown mechanical properties of the human leg during dynamic conditions such as walking. We built a robotic knee exoskeleton to address this problem. Here, we present the effects of our device on the walking pattern of four subjects. We assessed the effects after a short period of acclimation as well as after a 1.5h walking protocol. We found that the knee exoskeleton decreased (towards extension) the peak hip extension and peak knee flexion of the leg with the exoskeleton, while minimally affecting the non-exoskeleton leg. Comparatively smaller changes occurred after prolonged walking. These results suggest that walking patterns attained after a few minutes of acclimation with a knee exoskeleton are stable for at least a couple of hours.

Optimum design of family structure and allocation of resources in association mapping with lines from multiple crosses.

Family mapping is based on multiple segregating families and is becoming increasingly popular because of its advantages over population mapping. Athough much progress has been made recently, the optimum design and allocation of resources for family mapping remains unclear. Here, we addressed these issues using a simulation study, resample model averaging and cross-validation approaches. Our results show that in family mapping, the predictive power and the accuracy of quatitative trait loci (QTL) detection depend greatly on the population size and phenotyping intensity. With small population sizes or few test environments, QTL results become unreliable and are hampered by a large bias in the estimation of the proportion of genotypic variance explained by the detected QTL. In addition, we observed that even though good results can be achieved with low marker densities, no plateau is reached with our full marker complement. This suggests that higher quality results could be achieved with greater marker densities or sequence data, which will be available in the near future for many species.

Control of early seed development.

Seed development requires coordinated expression of embryo and endosperm and has contributions from both sporophytic and male and female gametophytic genes. Genetic and molecular analyses in recent years have started to illuminate how products of these multiple genes interact to initiate seed development. Imprinting or differential expression of paternal and maternal genes seems to be involved in controlling seed development, presumably by controlling gene expression in developing endosperm. Epigenetic processes such as chromatin remodeling and DNA methylation affect imprinting of key seed-specific genes; however, the identity of many of these genes remains unknown. The discovery of FIS genes has illuminated control of autonomous endosperm development, a component of apomixis, which is an important developmental and agronomic trait. FIS genes are targets of imprinting, and the genes they control in developing endosperm are also regulated by DNA methylation and chromatin remodeling genes. These results define some exciting future areas of research in seed development.

Dynamics of callose deposition and beta-1,3-glucanase expression during reproductive events in sexual and apomictic Hieracium.

Callose accumulates in the walls of cells undergoing megasporogenesis during embryo sac formation in angiosperm ovules. Deficiencies in callose deposition have been observed in apomictic plants and causal linkages between altered callose deposition and apomictic initiation proposed. In apomictic Hieracium, embryo sacs initiate by sexual and apomictic processes within an ovule, but sexual development terminates in successful apomicts. Callose deposition and the events that lead to sexual termination were examined in different Hieracium apomicts that form initials pre- and post-meiosis. In apomictic plants, callose was not detected in initial cell walls and deficiencies in callose deposition were not observed in cells undergoing megasporogenesis. Multiple initial formation pre-meiosis resulted in physical distortion of cells undergoing megasporogenesis, persistence of callose and termination of the sexual pathway. In apomictic plants, callose persistence did not correlate with altered spatial or temporal expression of a beta-1,3-glucanase gene (HpGluc) encoding a putative callose-degrading enzyme. Expression analysis indicated HpGluc might function during ovule growth and embryo sac expansion in addition to callose dissolution in sexual and apomictic plants. Initial formation pre-meiosis might therefore limit the access of HpGluc protein to callose substrate while the expansion of aposporous embryo sacs is promoted. Callose deposition and dissolution during megasporogenesis were unaffected when initials formed post-meiosis, indicating other events cause sexual termination. Apomixis in Hieracium is not caused by changes in callose distribution but by events that lead to initial cell formation. The timing of initial formation can in turn influence callose dissolution.

Complex orthodontic problems: the orthognathic patient with temporomandibular disorders.

The diagnosis and treatment of temporomandibular disorders (TMD) remain controversial despite considerable research and publication in this area. The relationship of these problems to dental and skeletal malocclusion is equally debatable. Recent studies suggest that although malocclusion may have a role, it is a small one. Accordingly, treatment of TMD with occlusion-altering therapy, such as orthodontics and orthognathic surgery, should be limited to specific situations. This report discusses the management of patients with coexisting TMD and skeletal malocclusion. Current concepts in clinical and radiographic diagnosis are discussed, as well as an overview of noninvasive therapy. A case report is used to illustrate an approach to diagnosis and treatment planning in an individual with active TMD and a skeletal malocclusion requiring orthognathic surgery for correction.

Orthognathic surgery versus orthodontic camouflage in the treatment of mandibular deficiency.

Surgical correction of Class II malocclusions, when associated with mandibular deficiency, often has improved results with combined orthodontic and surgical correction compared with orthodontic treatment alone. Strong consideration of surgical correction of mandibular deficiency should be based on the following questions: 1) Do the patient's goals for treatment place a high priority on improvement in facial esthetics? As a corollary, even patients who are not particularly concerned with facial esthetics, but who may have a worsening in facial appearance as a result of orthodontic camouflage, should be considered for surgical correction. This may include patients with lack of upper lip support, an obtuse nasolabial angle, a large nose, and a long lower face height, all of which may become more apparent as a result of orthodontic camouflage treatment. 2) Are the orthodontic movements required in excess of the envelope of discrepancy so that adequate orthodontic correction may not be achieved? 3) Could orthodontic-surgical treatment result in a significant decrease in treatment time? An example would be when surgical treatment in combination with orthodontics could be accomplished without extraction, whereas orthodontic treatment alone would require extraction and space closure. 4) Is there adequate patient compliance? Would orthodontic treatment alone be as ineffective without adequate patient cooperation? 5) Are the risks of surgery within acceptable levels? Are the benefits of surgical treatment, as previously described, obvious?

Current concepts in management of facial trauma.

Open reduction and internal fixation have become routine in facial fracture treatment. Methodical evaluation and treatment planning should be based on the patient's injuries, extenuating factors, and the surgeon's experience. After initial treatment, patients with facial trauma may require orthodontic alignment of teeth, endodontic therapy, osteotomies, implants, vestibuloplasties, and scar revisions to achieve an acceptable functional and cosmetic result. The oral and maxillofacial surgeon is best qualified to coordinate and help deliver this interdisciplinary approach to treatment.

[Autogenous auricular cartilage grafts after TMJ discectomy. A comparative study with and without silastic implants]. / Autogener Ohrknorpel nach Diskektomie des Kiefergelenkes. Eine Vergleichsstudie mit und ohne Silastikimplantation.

Following TMJ discectomy an interposed autogenous graft is to be preferred. In our study we examined the effect of short-term Silastic grafts on the surrounding tissue. When the silicone material was removed 12 weeks after surgery, foreign body granulations were present only in those cases where the Silastic surface had been mechanically roughened.

[Fixation screws and tension bolt technique for osteotomies. Stability study]. / Fixationsschrauben- und Zugschraubentechnik bei Osteotomien. Eine Stabilitätsstudie.

Following sagittal mandibular osteotomy the mandibles of Class II patients were stabilized using two different fixation techniques. It was the goal of this study to delineate the effects of these two techniques on stability. The patient population was approximately the same on both groups. 1 year after surgery differences in stability were not found. The functional and esthetic results, too, were equal in both groups.

Autogenous auricular cartilage graft for temporomandibular joint repair. A comparison of technique with and without temporary silastic implantation.

Four Macaca fascicularis monkeys underwent bilateral temporomandibular joint surgery including disc removal, condyle recontouring and disc replacement using autogenous auricular cartilage grafts. One side was treated with the cartilage graft alone while the other side was treated with a cartilage graft combined with a temporarily implanted 0.02 inch dacron-reinforced silastic sheet. The silastic sheeting was removed at twelve weeks after the initial surgery. The monkeys were sacrificed at fourteen, twenty-four, thirty-six and fifty-two weeks after the initial disc removal and cartilage grafting. The joints treated with cartilage grafts alone showed significant fibrous connective tissue adhesions which had formed between the inferior surface of the graft and the articulating surface of the condyle. In the joints treated with a cartilage graft and silastic sheeting a joint space was clearly maintained between the cartilage graft and condylar surface without the formation of fibrous connective tissue adhesions. It appears that temporary implantation of a thin silastic sheet combined with autogenous cartilage grafting may prevent the formation of fibrous connective tissue adhesions within the joint.

Subcutaneous emphysema producing airway compromise after anesthesia for reduction of a mandibular fracture. A case report and review of the literature.

Subcutaneous emphysema can occur as the result of trauma, surgery, and anesthesia. A case is presented of extensive subcutaneous emphysema after anesthesia for oral surgical reduction of a mandibular fracture. A discussion of the diagnosis, pathophysiology, and treatment of subcutaneous emphysema follows.

Lag screw versus position screw techniques for rigid internal fixation of sagittal osteotomies: a comparison of stability.

Both lag screw and position screw techniques have potential advantages and disadvantages when used for securing sagittal osteotomies of the mandible. This study evaluated 56 patients undergoing bilateral sagittal split osteotomies for mandibular advancements. Osteotomies were fixed with either a position screw or lag screw technique using 2-mm self-threading screws. Five cephalometric points and two angles were used to evaluate skeletal changes. There were no statistically significant differences in the postsurgical movement of point B or the mandibular incisor. There were slight statistically significant differences in the horizontal and vertical movements of gonion. Overall, similar postoperative stability existed in both groups. Gonion and gonial angle changes were detected cephalometrically but had no effect on the clinical outcome.

Cortical thickness in human mandibles: clinical relevance to the sagittal split ramus osteotomy.

Human cadaver hemimandibles were subjected to sagittal split ramus osteotomy, and the cortical thickness of each mandible was then measured in several areas. A measurable difference in morphology was found in the proximal segment of the mandible. Because cortical bone thickness is directly related to bone-screw holding strength, these results have important implications for the use of rigid internal fixation. The results suggested that the areas that coincide with the most anterior and superior extent of the osteotomy would be the ideal locations for screw placement.

Management of delayed union and nonunion of maxillary osteotomies.

Delayed union and nonunion of maxillary osteotomies are unusual, but have been seen with a variety of surgical moves. Management of these problems can be divided into early and late therapy. Four cases are presented illustrating some of these methods of treatment.

The effect of repetitive screw hole use on the retentive strength of pretapped and self-tapped screws.

Multiple systems for internal screw fixation are presently in use in oral and maxillofacial surgery. These systems differ in screw diameter, material, and design. This study evaluated the uniaxial pullout strength of five screw systems. Two-millimeter, 2.7-mm, and 3.5-mm screws were initially evaluated for pullout strength. Pretapped and self-tapped screws were then inserted into the same hole multiple times before pullout testing. Results of pullout testing revealed no significant difference in pullout strength of pretapped and self-tapped screws of equal diameter (P greater than .05). Increased screw diameter produced increased pullout strength. No significant difference in pullout strength was noted in pretapped or self-tapped screws inserted into the same hole one, two, or three times before pullout testing (P greater than .05).

The effectiveness of flumazenil in reversing the sedation and amnesia produced by intravenous midazolam.

In this double-blind study 31 outpatients undergoing third molar extraction were randomly assigned to one of two groups. All patients were sedated with intravenous midazolam (IV) by titration method. The flumazenil group (n = 20) received an average of 0.8 +/- 0.17 mg of flumazenil IV. The placebo patients (n = 11) each received 10 mL of normal saline. By both observer and patient alertness ratings, patients receiving flumazenil appeared significantly more alert than placebo patients at 5, 15, 30, and 60 minutes following reversal. After reversal the flumazenil group had significantly higher scores than the placebo group at all intervals through 60 minutes. All the patients receiving flumazenil were able to walk without assistance at 5 minutes, compared with only one patient in the placebo group, and more patients in the flumazenil group recognized the picture card shown to them at 5, 15, 30, and 60 minutes postreversal. Flumazenil is effective in terminating the amnestic properties of midazolam, but this appears to occur to a lesser extent than the reversal of its sedative properties.

Autogenous auricular cartilage implantation following discectomy in the primate temporomandibular joint.

The purpose of this study was to evaluate the histologic changes in primate temporomandibular joints (TMJ) treated with autogenous auricular cartilage grafts following total discectomy. Four Macaca fascicularis monkeys underwent bilateral TMJ disc removal and high condylar shaves. One TMJ in each monkey was treated by grafting autogenous auricular cartilage to the glenoid fossa; the contralateral joint served as a control. Monkeys were killed at 6, 12, 16, and 24 weeks postoperatively. Viable auricular cartilage was found in all grafted joints. There was a variable amount of fibrous connective tissue surrounding the cartilage grafts, with some grafts being directly fused to the glenoid fossa. One joint showed significant fibrous connective tissue adhesions between the condylar surface and the inferior portion of the graft. Degenerative changes in the grafted joint appeared grossly to be less severe than in the control joints. The cartilaginous tissues appeared to be a suitable autogenous tissue graft, maintaining its viability and functioning as an interpositioning material between the condyle and fossa.

Temporary silastic implantation following discectomy in the primate temporomandibular joint.

Silastic (Dow Corning, Midland, MI) has been used in the surgical treatment of a variety of temporomandibular joint (TMJ) disorders as either a permanent or temporary implant. In this study four Macaca fascicularis monkeys underwent bilateral TMJ discectomies and high condylar shaves. The experimental side was treated with a Silastic sheet implant which was removed at 3 months postdiscectomy. The contralateral side was left without an implant and served as a control. Animals were killed at 3, 4, 5, and 6 months postoperatively. A fibrous connective tissue capsule was found around the Silastic implant at all time intervals. This capsule formed a single joint space between the inferior surface of the glenoid fossa and articulating surface of the condyle. Three months following implant removal, the capsule was still present and there was no significant inflammatory cell infiltrate. The severity of the degenerative changes was decreased on the implant side.