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Dive into the research topics where Hans-Christian Jacobsen is active.

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Featured researches published by Hans-Christian Jacobsen.


Clinical Oral Investigations | 2011

Altered expression of cell–cell adhesion molecules β-catenin/E-cadherin and related Wnt-signaling pathway in sporadic and syndromal keratocystic odontogenic tumors

Samer G. Hakim; Hartwig Kosmehl; Peter Sieg; Thomas Trenkle; Hans-Christian Jacobsen; Geza Attila Benedek; Julika Ribbat; Oliver Driemel

Differential diagnosis of the keratocystic odontogenic tumor (KCOT) still represents a challenging problem especially if compared with the dentigerous cyst, which is similar in clinical and radiological course. Histological assessment of this entity may therefore draw crucial attention since various radical procedures are recommended for such lesions in contrast to dentigerous cysts. Since recent reports could prove the involvement of wingless(Wnt)-signaling pathway and β-catenin in the pathogenesis of many odontogenic and neoplastic lesions indicating impairment of cell–cell adhesion, we investigated the expression of two Wnt-signaling pathways, Wnt-1 and Wnt-10A as well as β-catenin and E-cadherin along with other related proteins in both lesions. We found a significant down-regulation in the expression of cell adhesion proteins β-catenin and E-cadherin along with alteration of Wnt-1 and Wnt-10A expression in the epithelium of KCOT. We assessed a specific focal distribution pattern of p63 in the suprabasal cell layer and a significant up-regulation of cyclin D1. Furthermore, laminin α-2 was a characteristic marker labelling only the basement membrane of dentigerous cysts. These results provide a new hypothesis explaining a molecular mechanism to understand initiating and development of KCOTs and an alternative therapeutic approach, especially for syndromal patients, where these multilocal lesions may involve and destroy wide orofacial bony structures.


Head and Neck-journal for The Sciences and Specialties of The Head and Neck | 2006

Superficial ulnar artery: Curse or blessing in harvesting fasciocutaneous forearm flaps

Peter Sieg; Hans-Christian Jacobsen; Samer G. Hakim; Dirk Hermes

Superficial ulnar artery is a well‐known vascular anomaly that may cause special risks because of possible impairment of the vessel by mistake during harvesting fasciocutaneous forearm flaps.


Plastic and Reconstructive Surgery | 2004

Rare facial clefts : Treatment during charity missions in developing countries

Peter Sieg; Samer G. Hakim; Hans-Christian Jacobsen; Bassam Saka; Dirk Hermes

During 10 charity missions in developing countries, 14 patients of a total of 374 children with cleft lip and palate deformities were treated for rare facial clefts. There were three midline clefts (Tessier no. 0 cleft, n = 1; Tessier no. 14 cleft, n = 2), four oblique facial clefts (Tessier no. 3 cleft, n = 2; Tessier no. 5 cleft, n = 2), and seven lateral facial clefts (Tessier no. 7 cleft). Surgical treatment focused on cleft repair by soft-tissue reconstruction apart from two Tessier no. 14 clefts, in which the bony gap was also closed using bone grafts from the iliac crest. The postoperative course was uneventful except for one local wound infection that was treated successfully using oral antibiotics. This article summarizes the authors’ experience with the surgical management of these malformations and considers the limitations under conditions of charity missions in developing countries. Furthermore, some rare forms of cleft formation are added to the existing literature.


International Journal of Experimental Pathology | 2006

Early and late immunohistochemical and ultrastructural changes associated with functional impairment of the lachrymal gland following external beam radiation

Samer G. Hakim; Christina Schröder; Gerd Geerling; Isabel Lauer; Thilo Wedel; Hartwig Kosmehl; Oliver Driemel; Hans-Christian Jacobsen; Thomas Trenkle; Dirk Hermes; Peter Sieg

The aim of this study was to investigate scintigraphic, immunohistological and ultrastructural changes associated with radiation‐induced dysfunction of the lachrymal gland in an established experimental animal model. Ten rabbits were randomized into two groups and used for the study; in the control as well as experimental group, the Schirmer‐test, lachrymal gland scintigraphy, and immunohistological and ultrastructural investigations were carried out prior to irradiation and 72 h as well as 1 month after single‐dose irradiation with 15 Gy. Seventy‐two hours after irradiation, secretion reduction evaluated by the Schirmer‐test was evident. At this phase, we could observe a decrease in the expression of α‐SMA and a re‐distribution of tenascin‐C matrix. Ultrastructural changes of acinar and myoepithelial cells were noticed; simultaneously, disturbance in the primary 99mTcO4– uptake as well as significant reduction of the lachrymal ejection fraction was assessed scintigraphically. These changes were still evident 1 month following irradiation but became less intensive. Single‐dose irradiation with 15 Gy implicates a functional impairment of the lachrymal gland, which is associated with early immunohistological and ultrastructural alterations. These changes may represent objective surrogate parameters for radiogenic dysfunction and prerequisites for further investigations on radioprotection of lachrymal glands during radiotherapy of the periorbital region.


Head and Neck-journal for The Sciences and Specialties of The Head and Neck | 2012

Long‐term functional donor site morbidity after ulnar forearm flap harvest

Peter Sieg; Mete Dericioglu; Cathrin Hansmann; Hans-Christian Jacobsen; Thomas Trenkle; Samer G. Hakim

The purpose of this study was to evaluate long‐term functional donor site morbidity following ulnar forearm flap harvest taking both subjective and objective criteria into consideration.


British Journal of Oral & Maxillofacial Surgery | 2014

Comparative biomechanical study on three miniplates osteosynthesis systems for stabilisation of low condylar fractures of the mandible

Samer G. Hakim; Melanie Wolf; Robert Wendlandt; Harald Kimmerle; Peter Sieg; Hans-Christian Jacobsen

Open reduction and fixation of low condylar fractures of the mandible can be achieved by many osteosynthesis systems that differ in size, shape, and site of placement according to the surgical approach. We investigated the maximum load and rigidity of 4 osteosynthesis systems: the standard double 4-hole straight miniplates, the inverted y-miniplate (with and without self-drilling screws), and the TriLock Delta condyle trauma plate. The standard double 4-hole straight miniplate osteosynthesis achieved the best fixation and resistance in view of a mean (SD) maximum load of 539.8 (100.2)N, followed by the inverted y-miniplate with the self-drilling screws (246.5 (23.8)N), the inverted y-miniplate with standard screws (242.4 (27.2)N), and finally the TriLock Delta plate (167.4 (39.2)N). Analysis of the slope of the force-displacement diagram from 80N to 100N in each group showed that the TriLock Delta miniplate had the highest values for rigidity (17.3 (5.1)N/μm), followed by the inverted y-miniplate groups with self-drilling screws (14.1 (6.4)N/μm), and with standard screws (12.6 (2.5)N/μm). The double 4-hole straight miniplate osteosynthesis had the lowest rigidity (8.7 1.4)N/μm). Despite the significant difference in the maximum load between the double 4-hole miniplates and other investigated osteosynthesis patterns, all groups had sufficient load for the fixation of low condylar fractures of the mandible when postoperative bite forces and the slowly increasing voluntary clenching during healing were considered.


Journal of Cranio-maxillofacial Surgery | 2014

Unilateral cleft lip/nose repair using an equal bows /straight line advancement technique - A preliminary report and postoperative symmetry-based anthropometry.

Samer G. Hakim; Horst Heinrich Aschoff; Hans-Christian Jacobsen; Peter Sieg

In the evolution of cleft lip repair there has been continuous attempt to minimize local trauma, improve lip and nasal appearance and, especially, prevent conspicuous scars. The surgical technique presented meets these criteria, resulting in an appropriate scar course in children with a specific philtral ridge shape. Postoperative digital anthropometry was performed in 18 patients who underwent unilateral cleft lip repair using the equal bows/straight line advancement technique and in matched healthy control individuals. Symmetry values were assessed for lip length, philtral ridge length, vermilion height, width of the alar base, nasocanthal length, circumference of the nostrils, nostril width and height in both cleft and control groups. Evaluation revealed no significant differences in the symmetry values between cleft patients and control group (lip length: p = 0.71, philtral ridge length: p = 0.52, vermilion height: p = 0.23, alar base width: p = 0.69, nasocanthal length: p = 0.25, nostril circumference: p = 0.17, nostril width: p = 0.34, nostril height: p = 0.33). Principles of cleft lip repair can be achieved using the described technique which provides adequate lip length and natural nasal appearance in patients with a parallel-shaped philtral ridge.


Head and Neck-journal for The Sciences and Specialties of The Head and Neck | 2014

Ulnar artery-based free forearm flap: review of specific anatomic features in 322 cases and related literature.

Samer G. Hakim; Thomas Trenkle; Peter Sieg; Hans-Christian Jacobsen

The ulnar free forearm flap (UFFF) represents a variant of soft tissue transplants for orofacial reconstruction with specific topographic anatomy of the donor‐site, which has to be considered during flap raising.


International Journal of Oral and Maxillofacial Surgery | 2009

Including the platysma muscle in a cervicofacial skin rotation flap to enhance blood supply for reconstruction of vast orbital and cheek defects: Anatomical considerations and surgical technique

Samer G. Hakim; Hans-Christian Jacobsen; H.H. Aschoff; Peter Sieg

The surgical technique introduced in this work describes a modification of the rotation skin flap that includes the platysma muscle in order to improve the blood supply of the flap. This modified rotation flap enables sufficient reconstruction of extended regions following ablative surgery of the head and neck. The anatomy and clinical application of a bilayer cervicofacial skin-platysma rotation flap is described in 6 patients. Flap design ensures sufficient blood perfusion mainly via the occipital artery, the superficial cervical artery and the transverse cervical artery; venous drainage is achieved by the external jugular vein and by randomised vascularisation. The surgical procedures led to sufficient and successful reconstruction of the orbital and cheek region. Further oncological management, such as neck dissection and total parotidectomy could be performed through the flap approach because of the adequate exposure of neck structures. Due to the sensory supply reaching the flap dorsally, sensibility in the reconstructed region could be regained in all patients. This modified skin-platysma rotation flap represents an appropriate surgical technique for safe and simple closure of vast orbital and cheek defects with enhanced blood supply, which enables the extended mobilization required after ablative surgery of the orofacial region.


Journal of Cranio-maxillofacial Surgery | 2013

Allogenic submandibular gland transplantation following hematopoietic stem cell transplantation

Hans-Christian Jacobsen; Samer G. Hakim; Thomas Trenkle; Martin Nitschke; Philipp Steven; Peter Sieg

BACKGROUND Autologous submandibular gland transfer for treatment of progressive dry eye symptoms requires a functionally intact submandibular gland. In cases of total function loss of both lacrimal and submandibular glands this procedure has to be modified. Here we report on the first two cases of the allogenic transplantation of a submandibular gland to treat patients suffering from complete functional loss of both glands due to graft-versus-host disease (GvHD) following stem cell transplantation. METHODS We carried out allogenic transplantation of the submandibular gland of the matched former stem cell donor to the temporal fossa of the stem cell recipient suffering from GvHD-induced dry eye. The treatment was carried out in two male patients who showed complete donor chimerism to the stem cell donors, so that no immunosuppressive therapy was applied. RESULTS Postoperative clinical assessment of the patients revealed primary success of the procedure. The ocular surface showed improvement of lubrication and reduction of inflammatory signs. In the long-term follow-up sialoscintigraphy revealed lower tracer activity than expected and secretion of saliva-tears decreased. CONCLUSION Even though the so-called total donor chimerism was assessed allogenic transplantation of the submandibular gland following GvHD-induced dry eye showed signs of organ rejection and therefore initial immunosuppressive therapy after allogenic transplantation has to be considered.

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Hartwig Kosmehl

École Polytechnique Fédérale de Lausanne

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Oliver Driemel

University of Regensburg

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