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Biomedical subjects

E Brenner

Publications and source records attributed to E Brenner.

At least 19 recordsLinked to original sources

Visual depth processing in Williams-Beuren syndrome.

Patients with Williams-Beuren Syndrome (WBS, also known as Williams Syndrome) show many problems in motor activities requiring visuo-motor integration, such as walking stairs. We tested to what extent these problems might be related to a deficit in the perception of visual depth or to problems in using this information in guiding movements. Monocular and binocular visual depth perception was tested in 33 patients with WBS. Furthermore, hand movements to a target were recorded in conditions with and without visual feedback of the position of the hand. The WBS group was compared to a group of control subjects. The WBS patients were able to perceive monocular depth cues that require global processing, but about 49% failed to show stereopsis. On average, patients with WBS moved their hand too far when no visual feedback on hand position was given. This was not so when they could see their hand. Patients with WBS are able to derive depth from complex spatial relationships between objects. However, they seem to be impaired in using depth information for guiding their movements when deprived of visual feedback. We conclude that the problems that WBS patients have with tasks such as descending stairs are not due to an inability to judge distance.

Adolescent↗

Judging relative positions across saccades.

When components of a shape are presented asynchronously during smooth pursuit, the retinal image determines the perceived shape, as if the parts belong to the moving object that the eyes are pursuing. Saccades normally shift our gaze between structures of interest, so there is no reason to expect anything to have moved with the eyes. We therefore decided to examine how people judge the separation between a target flashed before and another flashed after a saccade. Subjects tracked a jumping dot with their eyes. Targets were flashed at predetermined retinal positions, with a 67-242 ms interval between the flashes. After each trial subjects indicated where they had seen the targets. We selected the trials on which subjects made a complete saccade between the presentations of the two targets. For short inter-target intervals, subjects' judgements depended almost exclusively on the retinal separation, even when there were conspicuous visual references nearby. Even for the longest intervals, only part of the change in eye orientation was taken into consideration. These findings cannot simply be accounted for on the basis of the mislocalisation of individual targets or a compression of space near saccades. We conclude that the retinal separation determines the perceived separation between targets presented with a short interval between them, irrespective of any intervening eye movements.

Discrimination, Psychological↗

Cartilage canals in the chicken embryo: ultrastructure and function.

In this study the detailed morphology and the function of cartilage canals in the chicken femur are investigated. Several embryonic stages (e 13.5, 16, 19, and 20) are examined by means of light microscopy, electron microscopy (TEM), and immunohistochemistry (VEGF, type I and II collagen). Our results show that cartilage canals originate from the perichondrium and form a complex pattern. Two types of canals are distinguishable: shell canals and communicating canals. Shell canals are in the reserve zone and are arranged in successive layers. Communicating canals spring from the shell canals and pass down into the proliferative zone and into the hypertrophic zone. These canals are conical shaped and are orientated nearly in parallel to the long axis of the femur. Cartilage canals comprise venules, arterioles, capillaries (mature and immature), and undifferentiated mesenchymal cells. No canal wall in the sense of an epithelium is elaborated. VEGF is detected in both types of canals and macrophages are found at the end of the cartilage canals. We conclude that the growth factor stimulates angiogenesis and that the latter cells erode the matrix ahead of the canals and thus enable the advancement of the vessels. The results clearly show that the canal matrix differs from the remaining cartilage matrix. The canal matrix contains type I collagen, few type II collagen fibrils and proteoglycans are lacking. In contrast, in the cartilage matrix type II collagen and proteoglycans are abundant but no type I collagen is found. Communicating canals are surrounded by a distinct layer of type I collagen indicating that osteoid is formed around these canals. Hypertrophic chondrocytes label for type I collagen and it seemed possible that chondrocytes adjacent to the communicating canals differentiate into bone-forming cells. Our results provide evidence that cartilage canals are involved in nourishment of the cartilage as well as in the ossification process.

Animals↗

The "enthesis organ" concept: why enthesopathies may not present as focal insertional disorders.

OBJECTIVE: The Achilles tendon insertion is associated with a complex of adjacent fibrocartilages, a bursa, and a fat-pad, and is functionally much more than a focal insertion. This has important implications for a better understanding of the spondylarthropathies (SpA). However, the degree to which other insertions form comparable "enthesis organs" has not been established. The aim of this study was to demonstrate the applicability of the enthesis organ concept to other insertion sites. METHODS: Both joint-related (articular) and extraarticular entheses were removed from 28 sites in the limbs of formalin-fixed cadavers (age at death 70-101 years) that had been donated for anatomic study. The samples were prepared for paraffin histologic analysis and sectioned longitudinally. The presence and extent of enthesis organs was evaluated at each site in serial sections stained with Masson's trichrome and toluidine blue. RESULTS: Articular enthesis organs were found at 14 entheses, including the attachments of the digital extensor tendons and collateral ligaments, the cruciate ligaments, tibialis anterior, the lateral collateral ligament of the knee, and the popliteal tendon. Extraarticular enthesis organs were seen at 2 sites, the biceps brachii and patellar tendon insertions. In all enthesis organs, sesamoid and/or periosteal fibrocartilage was present in close association with synovium. CONCLUSION: The concept of an enthesis organ is of general significance in understanding attachment sites and may explain the diverse pathologic changes, including synovitis, bursitis, and extracapsular changes, seen adjacent to tendon/ligament entheses in SpA. These findings may provide insight into the reason the target tissues in SpA are apparently so diverse.

Aged↗

Clinical anatomy of the pelvic floor.

The study presented here comparing cross-sectional anatomy of the fetal and the adult pelvic connective tissue with the results of modern imaging techniques and actual surgical techniques shows that the classical concepts concerning the subdivision of the pelvic connective tissue and muscles need to be revised. According to clinical requirements, the subdivision of the pelvic cavity into anterior, posterior, and middle compartments is feasible. Predominating connecting tissue structures within the different compartments are: Paravisceral fat pad within the anterior compartment (Fig. 17, I), rectal adventitia or perirectal tissue within the posterior compartment (Fig. 17, II), and uterosacral ligaments within the middle compartment. The nerve-vessel guiding plate can be found in all of these compartments; it starts within the posterior compartment and it ends within the anterior one. It constitutes the morphological border between the anterior and posterior compartments in the male. This border is supplied by the uterosacral ligaments in the female. Whereas in gross anatomy no further border is discernable between anterior and posterior or middle compartment, the rectal fascia (hardly visible in embalmed cadavers) demarcates the rectal adventitia and is one of the most important pelvic structures for the surgeon. In principle, the outlined subdivision of the pelvic connective tissue is identical in the male and in the female; facts that become clear from early human life and that are already established during this period (Fig. 18). The uterus is interposed between the bladder and rectum and subdivides the pelvic peritoneum into two pouches thus establishing the only real difference between male and female pelvic cavity. The preferential direction of the pelvic connective tissue fibers is not changed by the interposition of the uterovaginal complex. The pelvic floor muscles are composed of the portions of the levator ani muscle, the muscles of the cavernous organs and the deep transverse perineal muscle in the male. The latter does not exist in the female. We have clearly shown that the different muscles can already be found in early human life and that they are never intermingled with the muscular walls of the pelvic organs. The levator ani muscle of the female, however, is intermingled with connective tissue long before the female sexual hormones exert influence. We have also shown that the distinct sexual differences within the pelvic floor muscles as well as within the sphincter muscles can already be found in early human life. Both the external urethral and the external anal sphincter muscles are not completely circular. The external anal sphincter is intimately connected with the internal sphincter as well as with the longitudinal muscle. Whereas the innervation and function of the urethral sphincter muscles are mostly clear, cloacal development, innervation, and function of all parts of anal sphincter complex are not completely clarified. As to the support of the pelvic viscera, we believe that intact pelvic floor muscles, an undisturbed topography of the pelvic organs, and an undisturbed perineum are of more importance than the so-called pelvic ligaments. Our hypothesis points to the fact that the support of pelvic viscera is multistructural. Thus in pelvic surgery, a lot of techniques have to be revised with the aim to preserve or to reconstruct all the structures mentioned. This is a multidisciplinary task that can only be solved by cooperation of morphologists, urologists, gynecologists, and coloproctologic surgeons or by creating a multidisciplinary pelvic floor specialist.

Blood Vessels↗

Adipose tissue at entheses: the rheumatological implications of its distribution. A potential site of pain and stress dissipation?

OBJECTIVES: To describe the distribution of adipose tissue within and adjacent to entheses in order to assess its functional significance at attachment sites. METHODS: Entheses were removed from 29 different sites in the limbs of formalin fixed, elderly, dissecting room cadavers and the samples prepared for paraffin and/or methylmethacrylate histology. Entheses from four young volunteers with no history of significant musculoskeletal injury were examined by magnetic resonance imaging using T(1) weighted sequences. RESULTS: Adipose tissue was present at several different sites at numerous entheses. Many tendons/ligaments lay on a bed of well vascularised, highly innervated, "insertional angle fat". Endotenon fat was striking between fascicles, where entheses flared out at their attachments. It was also characteristic of the epitenon, where it occurred in conjunction with lamellated and Pacinian corpuscles. Fat filled, meniscoid folds often protruded into joint cavities, immediately adjacent to attachment sites. CONCLUSION: Adipose tissue is a common feature of normal entheses and should not be regarded as a sign of degeneration. It contributes to the increase in surface area of attachment sites, promotes movement between tendon/ligament and bone, and forms part of an enthesis organ that dissipates stress. The presence of numerous nerve endings in fat at attachment sites suggests that it has a mechanosensory role and this could account for the rich innervation of many entheses. Because damage to fat is known to lead to considerable joint pain, our findings may be important for understanding the site of pain in enthesopathies.

Adipose Tissue↗

The trapezoid form of the trochlea tali.

The wedge-shaped superior surface of the trochlea tali may be seen in a proximal view as a trapezium. The angle of this trapezium was calculated by measuring the length, and the smallest and largest widths of the trochlea, and was found to be 16.04 degrees for the left talus and 12.48 degrees for the right talus, respectively. The difference between these angles is highly significant. Due to biomechanical features of the talocrural joint an increase in the angle of the trochlea tali also intensifies the incongruency of this joint in plantar-flexion. Thus, this incongruency is larger on the left side. With this diminution of the joint-surface contact, increased internal rotation or "wobbling" movements are possible. An explanation for these facts might be found in footedness, similar to handedness. When constructing a prosthesis one has to consider that the trochlea tali cannot be exactly mirrored from one side to the other but may have to be calculated separately for each side. The fact that footedness seems to correlate with the angle of the trochlea tali can be also helpful.

Age Factors↗

The intersesamoidal ridge of the first metatarsal bone: anatomical basics and clinical considerations.

The first metatarsal shows a ridge at the plantar side of the head, aligned nearly longitudinally. On 100 macerated first metatarsals (53 right, 47 left) the existence and alignment of this ridge was examined. On the basis of a regression formula, the specimens were assigned to the genders; accordingly, 29 bones were female, the remaining 71 bones male. The intersesamoidal ridge existed in 95 cases (50 right, 45 left); all 29 female bones showed this ridge, male ones in 66 cases. The ridge deviated on average 7.99 degrees from the longitudinal axis of the first metatarsal towards distal-lateral (from -3 degrees to 19 degrees ). Significant differences ( p=0.001) were found for side (left: 6.04 degrees, right: 9.74 degrees ) but not for gender (female: 8.14 degrees, male: 7.92 degrees ). Noticeable correlations with the length of the first metatarsal and the size of the head could not be determined. The mean values of the alignment of the intersesamoidal ridge seem also not to correlate with the metatarsophalangeal angle. The ridge separates the joint surfaces for the sesamoid bones, which are built-in to the tendons of the two heads of the flexor hallucis brevis muscle. Thus, from the alignment of the ridge, the functional direction of this muscle can be concluded. Since the alignment deviates from the longitudinal axis of the first metatarsal, an adduction, in addition to the flexion, can be concluded. Operative techniques for the correction of hallux valgus often change the alignment of the ridge, and therefore also the biomechanical properties of the flexor hallucis brevis muscle. This could explain failures in several surgical therapies.

Female↗

Lateral arm flap: analysis of its anatomy and modification using a vascularized fragment of the distal humerus.

Soft tissue injuries with associated bone defects are difficult to manage and often require prolonged treatment with repeated interventions. Frequently, a free flap is applied as a first step and bone grafting is carried out in a second procedure. Ideally, these two procedures are combined in one operation, utilizing a soft tissue flap with an attached vascularized bone fragment. The lateral arm flap can provide such an osteoseptocutaneous flap and has been utilized clinically with success; however, the vascular anatomy of the flap, especially the humeral fragment, has not been described in detail previously, and there is broad disagreement concerning its innervation. In this study, the arteries and nerves of 24 fresh cadaver arms were dissected after injection of colored latex. The levels of origin of the periosteal arteries of the humerus were also documented. The lateral arm flap has a consistent arterial supply from three septocutaneous perforating branches that are arranged in a predictable pattern. The lateral supracondylar ridge of the humerus is vascularized by direct branches of the posterior branch of the radial collateral artery and by arteries that arise from muscular branches supplying adjacent muscles. The innervation of the lateral arm flap is by the inferior lateral cutaneous nerve of the arm. Knowledge of the consistent vascular anatomy of the lateral humerus and soft tissue of the donor site allows an osteoseptocutaneous flap to be raised safely with an appropriate technique. We recommend use of the lateral arm flap with a humeral fragment for the treatment of combined soft tissue and bone defects when a single step surgical solution is indicated.

Aged↗

Relationship between the descending branch of the inferior gluteal artery and the posterior femoral cutaneous nerve applicable to flap surgery.

Flap surgery in the distal part of the gluteal region has to deal with a lack of detailed descriptions of the inferior gluteal artery and the posterior femoral cutaneous nerve. The existing papers are mainly clinical studies, based on low numbers of observations. Our study includes 118 cadaveric gluteal regions. The descending branch was present in 91% and gave rise to a cutaneous branch. When the descending branch was absent, this cutaneous branch came from the medial or lateral femoral circumflex artery or as a perforator of the deep artery of the thigh. The posterior femoral cutaneous nerve was found in a common sheath of connective tissue with the descending branch of the inferior gluteal artery in 72% of cases. Nerve loops around the vessel are present in 29%. Our results show that a cutaneous or fasciocutaneous flap, either local or free, in this region can be reliably lifted on a cutaneous branch of the descending branch of the inferior gluteal artery without loss of sensitivity. However, the close relationship of the artery and nerve limits the arc of rotation in the case of a local flap.

Aged↗

New, simple, ultrasound-guided infiltration of the pudendal nerve: topographic basics.

PURPOSE: We report the topographic relationship of the pudendal nerve to the accompanying pudendal vessels and the ischial spine and provide the basics for an ultrasonographic depiction of these structures. METHODS: Twenty-nine female and 29 male adult human cadavers were positioned prone to expose the deep gluteal region. In 58 left and 58 right pelves the course of the pudendal nerve and vessels at the ischial spine were evaluated and analyzed statistically (n = 116). RESULTS: Multitrunked pudendal nerves were found in 40.5 percent with a left-vs.-right ratio of 1:1.5. The diameters of the single-trunked nerves ranged from 1.3 to 6.8 (mean 3.6 +/- 1.1) mm. In 75.9 percent the pudendal nerve was found medial to the accompanying internal pudendal artery. The distance to the artery ranged from 17.2 mm medial to 8 mm lateral (mean, 3.4 mm medial +/- 4.1 mm). The distance to the tip of the ischial spine ranged from 13.4 mm medial to 7.4 mm lateral (mean, 2.1 mm medial +/- 3.7 mm). CONCLUSIONS: The knowledge of the close spatial relationship between the pudendal nerve and the internal pudendal artery is important for any infiltration technique and even surgical release. It demands real-time, visually controlled infiltration techniques, such as with ultrasound.

Aged↗