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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 180 (1989), S. 383-391 
    ISSN: 1432-0568
    Keywords: Vasculature ; Wound healing ; Limb bud ; Chick
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Experimental analyses examining pattern formation in the developing chick limb have concentrated on the skeleton, muscles and nerves, and have rarely considered blood vessels. To investigate the relationship between the vasculature and limb development, posterior amputations were performed on 3.5–4 day chick limb-buds. It has been shown that the removal of the posterior half alters the developmental fate of the anterior tissue: it becomes necrotic and fails to differentiate into the complement of skeletal parts predicted by fate maps. The possibility that this developmental failure results from interference with the future arterial supply was examined by Indian ink injection between 3–48 h after operation. Scanning electron microscopy (SEM) and resin histology were used to examine the wound repair at similar post-operative intervals. Results from the Indian ink injections showed that within 6 h of operation a collateral circulation was established by means of a branch from the truncated primary subclavian artery. The capillary density in the operated limbs appeared normal when compared to the contralateral limb. The results support the view that the poor developmental performance of the anterior half is due to removal of the zone of polarising activity (ZPA) rather than to experimentally-induced alteration to the vascular supply. Histological and SEM examination of the wound healing process showed that epithelialization of the cut surface occurred within 24 h, and that the peridermal cells of the bilayered ectoderm appeared to initiate the regrowth. The wound site was not visible 48 h after operation, showing that wound healing at these developmental ages occurs quickly, with no scar tissue formation. These results show that the vasculature in the developing limb is labile, and that the cell death resulting from posterior-half amputation is not due to vascular insufficiency or ischaemia. In addition, this study of wound healing demonstrates the role of the ectoderm in establishing an avascular margin in the subjacent mesenchyme.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 182 (1990), S. 401-408 
    ISSN: 1432-0568
    Keywords: Meckel’s cartilage ; Wound healing ; Dysmorphogenesis ; Mandible ; Chick
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The embryonic chick mandibular arch was surgically sectioned in ovo on day 7 of incubation and the subsequent wound healing of the arch, together with the response of Meckel’s cartilage to fracture, was examined. The repair process observed (in contrast to that in adults) was characterised by minimal haematoma formation or cell death and the absence of formation of either cellular blastema or fracture callus. Re-epithelisation was complete within 48 h with no scar tissue formed. Continuity of Meckel’s cartilage, together with restoration of its histological appearance and that of the surrounding soft tissues, was re-established within 24 h in 88% of cases. In the case of the cartilage this was due to fusion of the matrix followed apparently by chondrocytic and perichondrial proliferation. This differs from the repair of embryonic long bone cartilages. In 12% of cases, however, mal-union or non-union of the cartilage resulted in mandibular arch deviation. This observation suggests that mandibular arch growth and morphogenesis may parallel the development of Meckel’s cartilage. Where cartilaginous non-union occurred, some irregularities in the pattern of the developing mandibular bones were evident, and it is argued that deformity in the cartilage may ultimately affect the length and shape of the adult mandible.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 188 (1993), S. 371-379 
    ISSN: 1432-0568
    Keywords: Skeletal ; Pattern ; Development ; Limb ; AER
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The mechanism of antero-posterior specification of limb skeletal pattern is still controversial. If, as proposed by the ZPA model, a diffusible morphogen does exist, its route of passage across the limb field has not been resolved. To investigate the contribution of the apical ectodermal ridge (AER) to the control of anteroposterior pattern formation, we examined the consequences of small wounds made to the AER. The wound response was investigated by means of resin histology and scanning electron microscopy; subsequent limb development and cartilage pattern were examined in wholemount preparations. Although regrowth of the bilaminate dorsal and ventral ectoderm over the wound occurred within 15 h, the more highly differentiated pseudostratified columnar epithelium of the AER did not reform, and there was subsequent retardation of limb outgrowth at the wound site. At 10–11 days of development, the appearance of the limbs allowed them to be placed into one of three categories; presence of supernumerary elements, accentuation of an inter-digital cleft, or normal. The first of these categories included limbs in which digit 3 had bifurcated such that the sum of the parts of the resultant digital skeleton was greater than that which forms in a normal limb. Since in all of the experimental limbs all skeletal elements were present, we propose that continuity of the AER is not a pre-requisite for anteroposterior skeletal pattern formation in the chick wing.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 189 (1994), S. 147-155 
    ISSN: 1432-0568
    Keywords: Chick ; Wing ; Development ; Staging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The purpose of a staging system is to stage embryos by morphology rather than chronology. This is particularly useful when embryos do not develop exactly synchronously, as in the case of the chick. At present the Hamburger and Hamilton (1951) series is universally used to stage chick embryos. The aim of the present study was to provide a series of morphological descriptions of the normal stages of development of the chick wing bud from stages 19 to 36, and to correct some errors of the original system which may be overlooked by those new to the chick wing bud as an experimental model, and who rely primarily on the Hamburger and Hamilton stage series. In addition, Summerbell's (1976) observations on the appearance of the cartilaginous elements made from alcian green-stained whole mounts have been correlated with the external appearance of the wing bud to provide a more complete understanding of the skeletal development that influences, and to some degree accounts for, the changes in external morphology. Scanning electron microscopy (SEM) has been used to obtain images of much greater resolution and detail than those available from Hamburger and Hamilton, whilst using comparable magnifications to those attainable using conventional dissecting microscopes. The number of somites across which the proximal part of the wing bud extends has been provided as a measure of the limb width at early stages (19–24). At certain stages there were clear differences between the characteristic wing bud features described by Hamburger and Hamilton and those observed in the present study. These included the finding that the zeugopod, stylopod and autopod regions of the wing were identifiable as early as stage 27 instead of stage 30. It is hoped the information provided in this study will serve to supplement the Hamburger and Hamilton staging system.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Inflammation research 39 (1993), S. C102 
    ISSN: 1420-908X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Thromboembolic complications have been described in graft recipients receiving cyclosporine (CS). Whether these individuals have a hypercoagulable state when compared to healthy controls was evaluated. Recalcification times (RT) of saline-incubated citrated whole blood and endotoxin-incubated whole blood of both control and transplant patients were determined. There was no difference between the RT saline or RT endotoxin groups in both patient groups. These data suggest that CS alone has no procoagulant effects, but that addtional factors such as endotoxin and/or graft-induced antigen production may provoke the thrombotic complications.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Inflammation research 39 (1993), S. C104 
    ISSN: 1420-908X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In this report we demonstrate that ET-2, in addition to its powerful vasoconstrictor properties and its role in hypertension, is capable of creating a hypercoagulable (prothrombotic) state. This study was facilitated by the utilization of a sensitive modified recalcification time (MRT) test that can measure coagulation at all points in the coagulation spectrum. The MRT was determined on aliquots (1 ml) of citrated blood which were added to saline (MRTS), to 10 μg of endotoxin (MRTE), and to 10 pg of ET-2 (MRT ET-2). The mean values of MRTS, MRTE, and MRT ET-2 were 4.3 ±0.8, 3.7 ± 1.0, and 3.9 ± 0.8 min, respectively. There was a statistically significant difference between MRTE vs. MRTS and MRT ET-2 vs. MRTS using the twotailedt-test (p〈0.02 andp〈0.005, respectively).
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 184 (1991), S. 171-178 
    ISSN: 1432-0568
    Keywords: Frontonasal process ; Facial development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The midfacial region in vertebrates may be considered as developing from five separate processes, namely the central frontonasal process (FNP) and the paired maxillary and lateral nasal processes. Relatively little is known about the mechanisms whereby these processes interact to produce structures of the neonatal/adult face. This study was undertaken to gain some insights into the events involved in this process, and involved observing the effects on facial development in the chick of surgical excision of the FNP, prior to its fusion with the other facial processes. In the absence of the FNP, outgrowth of the upper beak was dramatically reduced, agenesis of the primary palate occurred, and development of the maxillary processes and palatal shelves was impaired. Thus, in the chick, the frontonasal process plays a major role in midfacial morphogenesis. Not only does the FNP provide the primary palate and a contribution to the development of the nasal septum, it is also important in the ordered development of the maxillary processes and of the definitive secondary palate contributions which have not emerged clearly from in vitro and teratogenic studies.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Applied mathematics & optimization 2 (1975), S. 315-336 
    ISSN: 1432-0606
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract A system is controlled with the aid of uncertain state measurements, the errors of which are known to lie within a given, compact set. Control of the system incurs a cost of which it is desired that the largest value consistent with the measurements obtained be minimized. Two different measurement régimes are considered. In the first, measurements are obtained throughout the history of the process and, in the second, only an initial state measurement is obtained. Under certain circumstances, it is shown that the optimization problems for the two régimes are equivalent. The general solution of the problem for the second régime is given for the case when the dynamics are linear, and the cost function quadratic.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    ISSN: 1432-0800
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Cancer immunology immunotherapy 17 (1984), S. 83-89 
    ISSN: 1432-0851
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Co-culture of cancer patients' nonadherent peripheral blood lymphocytes with irradiated autologous fresh tumor cells, termed the mixed lymphocyte-tumor interaction (MLTI) test, resulted in significant stimulation of 3H-Tdr in corporation on day 6 in 19 of 37 autologous combinations. The MLTI test was performed in a microtiter wells (0.2 ml) and a variety of solid tumor cells (sarcomas and carcinomas) were used. Tumor cells were dissociated from the fresh biopsy tissue by nontrypsin enzymatic digestion (deoxyribonuclease, hyaluronidase, and collagenase) and the tumor cells enriched by depletion of macrophages using adherence procedures. Occasionally, further tumor cell purification was achieved by separation of cells on the basis of size on dis-continuous gradients. Positive MLTI resulted in stimulation as high as 20-fold over the backgrounds of PBL and tumor cells cultured alone. Mean positive MLTI was SI of 7.7. The negative MTLI were not a reflection of generalized immunosuppression, because tumor cell preparations that did not stimulate autologous PBL did stimulate allogeneic PBL. In an additional patient, PBL not responding in the autologous MLTI did respond to allogeneic tumors. MLTI using cryopreserved cells reproduced the MLTI results using fresh cells in 11 of 16 tests; the other five tests were all positive in the fresh MLTI and negative when using cryopreserved cells. Despite reports from many other groups it appears that positive MLTI were not tumor-specific. In 14 experiments we were able to simultaneously test the proliferative response to autologous tumor as well as to an autologous normal tissue (lung, liver, colon, and bowel). In eight of these experiments positive responses were obtained with tumor stimulators and in seven of these, positive proliferation was also obtained with normal tissue.
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