Biomedical subjects

Klaus Jahnke

Publications and source records attributed to Klaus Jahnke.

9 recordsLinked to original sources

PubMed2006

Unusual aggressive course of a giant cell tumor of soft tissue during immunosuppressive therapy.

Giant cell tumor of soft tissue with low malignant potential (GCT-ST) is a low-grade, primary soft tissue sarcoma with histological and clinical features similar to giant cell tumor of the bone. The main tumor localizations are the extremities, but it may also occur in the head and neck region. GCT-ST shows a recurrence rate of approximately 15%, but it very rarely metastasizes. The risk of cancer development, especially of the skin, is up to fivefold increased in immunosuppressed patients after organ transplantation. The association of sarcomas and immunosuppressive therapy is best known for Kaposi sarcomas, whereas other types of sarcomas are rarely found. We report of a GCT-ST of low malignant potential, which developed under long-term immunosuppression in a patient 12 years after heart transplantation. The tumor presented with an unusual aggressive course and metastatic site: the parotid gland. Therefore, we suggest that in patients with immunosuppression, even low malignant cancerous lesions should be carefully observed, as their local behavior may be aggressive with development of metastasis.

Aged↗

PubMed2006

Prototype of a silicon nitride ceramic-based miniplate osteofixation system for the midface.

OBJECTIVE: The favorable properties of silicon nitride (Si3N4) ceramics, such as high mean strength level and fracture toughness, suggest biomedical use as an implant material. Minor reservations about the biocompatibility of Si3N4 ceramics were cleared up by previous in vitro and in vivo investigations. STUDY DESIGN AND SETTING: A Si3N4 prototype minifixation system was manufactured and implanted for osteosynthesis of artificial frontal bone defects in 3 minipigs. After 3 months, histological sections, computed tomography (CT) scans, and magnetic resonance imaging (MRI) scans were obtained. Finite element modeling (FEM) was used to simulate stresses and strains on Si3N4 miniplates and screws to calculate survival probabilities. RESULTS: Si3N4 miniplates and screws showed satisfying intraoperative workability. There was no implant loss, displacement, or fracture. Bone healing was complete in all animals. The formation of new bone was observed in direct contact to the implants. The implants showed no artifacts on CT and MRI scanning. FEM simulation confirmed the mechanical reliability of the screws, whereas simulated plate geometries regarding pullout forces at maximum load showed limited safety in a bending situation. CONCLUSIONS: Si3N4 ceramics show a good biocompatibility outcome both in vitro and in vivo. In ENT surgery, this ceramic may serve as a biomaterial for osteosynthesis (eg, of the midface including reconstruction the floor of the orbit and the skull base). To our knowledge, this is the first introduction of a ceramic-based miniplate-osteofixation system. Advantages compared with titanium are no risk of implantation to bone with mucosal attachment, no need for explantation, and no interference with radiologic imaging. Disadvantages include the impossibility of individual bending of the miniplates.

Animals↗

PubMed2005

Laser-tonsillotomy for treatment of obstructive tonsillar hyperplasia in early childhood: a retrospective review.

INTRODUCTION: Tonsillar hyperplasia leading to dyspnea, dysphagia and other symptoms of obstruction represents a common problem especially in young children where tonsillectomy should be avoided in order to preserve the immunological function of the tonsils. Aim of the study was to assess carbon-dioxide-laser-tonsillotomy as a considered alternative procedure to reduce the tonsillar volume in these children. METHODS: Between 1993 and 2004, 109 children with tonsillar hyperplasia without former episodes of tonsillitis received laser-tonsillotomy mostly (n=98) combined with adenoidectomy. The protruding part of the tonsil was reduced by a CO2-laser. Seventy-five children were available for follow-up with a standard questionnaire. Five patients required a subsequent tonsillectomy due to a recurrence of tonsillar hyperplasia. Histological investigations were performed. Twenty-two children were reevaluated by clinical examination. RESULTS: Most of the patients were relieved from obstructive symptoms. There was no occurrence of postoperative hemorrhage or peritonsillar abscesses. The histological investigations on the specimens from later performed tonsillectomy (n=5) showed no evidence of inflammation or scar formations, but open and deep crypts. The clinical examination did not reveal any signs of chronic infections. CONCLUSION: In this retrospective study tonsillotomy with CO2-laser in early childhood leads to a long-term elimination of obstructive symptoms due to tonsillar hyperplasia with minimal discomfort for the patient while preserving normally functioning immunocompetent tonsillar tissue. Further prospective studies are planned.

Child↗

PubMed2005

Antiphospholipid antibodies in patients with sensorineural hearing loss.

Sensorineural hearing loss can be associated with autoimmune diseases and the presence of antiphospholipid antibodies. Sixty patients (mean age 47 years, range 18-76 years) with sudden sensorineural hearing loss were studied with audiograms, stapedial thresholds, otoacoustic emissions, positional and caloric testing. The serologic testing included antibodies against phosphatidylserine and beta(2)-glycoprotein. Additionally, a group of 34 patients (mean age 65 years, range 31-81 years) with normal tension glaucoma was examined because in a previous study these patients were reported to have elevated concentrations of antiphospholipid antibodies with a coincidence of progressive sensorineural hearing loss. The baseline for antiphospholipid antibody levels was established in a control group of 40 healthy blood donors. In 12 of the 60 patients with sudden sensorineural hearing loss, levels of antiphospholipid antibodies were elevated. Antiphosphatidylserine IgM antibodies were significantly lower compared to controls and patients with the combination of hearing loss and normal tension glaucoma (Fisher's exact two-sided test, P < 0.01). Our data suggest that antibodies against beta2-glycoprotein seem to coincidence with an acute event, such as sudden sensorineural hearing loss, whereas antibodies against phosphatidylserine IgG are detectable in the prolonged sequel, such as in patients with progressive sensorineural hearing loss and normal tension glaucoma.

Adolescent↗

PubMed2005

Hyperfractionated accelerated chemoradiation with concurrent fluorouracil-mitomycin is more effective than dose-escalated hyperfractionated accelerated radiation therapy alone in locally advanced head and neck cancer: final results of the radiotherapy cooperative clinical trials group of the German Cancer Society 95-06 Prospective Randomized Trial.

PURPOSE: To report the results and corresponding acute and late reactions of a prospective, randomized, clinical study in locally advanced head and neck cancer comparing concurrent fluorouracil (FU) and mitomycin (MMC) chemotherapy and hyperfractionated accelerated radiation therapy (C-HART; 70.6 Gy) to hyperfractionated accelerated radiation therapy alone (HART; 77.6 Gy). PATIENTS AND METHODS: Three hundred eighty-four stage III (6%) and IV (94%) oropharyngeal (59.4%), hypopharyngeal (32.3%), and oral cavity (8.3%) cancer patients were randomly assigned to receive either 30 Gy (2 Gy every day) followed by 1.4 Gy bid to a total of 70.6 Gy concurrently with FU (600 mg/m(2), 120 hours continuous infusion) days 1 through 5 and MMC (10 mg/m(2)) on days 5 and 36 (C-HART) or 14 Gy (2 Gy every day) followed by 1.4 Gy bid to a total dose of 77.6 Gy (HART). The data were analyzed on an intent-to-treat basis. RESULTS: At 5 years, the locoregional control and overall survival rates were 49.9% and 28.6% for C-HART versus 37.4% and 23.7% for HART, respectively (P = .001 and P = .023, respectively). Progression-free and freedom from metastases rates were 29.3% and 51.9% for C-HART versus 26.6% and 54.7% for HART, respectively (P = .009 and P = .575, respectively). For C-HART, maximum acute reactions of mucositis, moist desquamation, and erythema were lower than with HART, whereas no differences in late reactions and overall rates of secondary neoplasms were observed. CONCLUSION: C-HART (70.6 Gy) is superior to dose-escalated HART (77.6 Gy) with comparable or less acute reactions and equivalent late reactions, indicating an improvement of the therapeutic ratio.

Actuarial Analysis↗

PubMed2003

Connexin30 (Gjb6)-deficiency causes severe hearing impairment and lack of endocochlear potential.

The gap junction protein connexin30 (Cx30) is expressed in a variety of tissues that include epithelial and mesenchymal structures of the inner ear. We generated Cx30 (Gjb6) deficient mice by deletion of the Cx30 coding region. Homozygous mutants (Cx30((-/-))) were born at the expected Mendelian frequency, developed normally and were fertile. However, they exhibit a severe constitutive hearing impairment. From the age of hearing onset, these mice lack the electrical potential difference between the endolymphatic and perilymphatic compartments of the cochlea, i.e. the endocochlear potential, which plays a key role in the high sensitivity of the mammalian auditory organ. In addition, after postnatal day 18, the cochlear sensory epithelium starts to degenerate by cell apoptosis. This degeneration process is likely to account for the concomitant decrease of the endolymphatic potassium concentration and the aggravation of the hearing loss in adult Cx30((-/-)) mice. The Cx30 ((-/-)) phenotype thus reveals the critical role of Cx30 both in generating the endocochlear potential and for survival of the auditory hair cells after the onset of hearing. The Cx30 deficient mice may represent a valuable model to study the mechanism of the hearing loss in human patients carrying a homozygous deletion of the CX30 gene (del Castillo et al., 2002, New Engl. J. Med., 346, 243-249).

Alleles↗

PubMed2003

Type III tympanoplasty applying the palisade cartilage technique: a study of 61 cases.

OBJECTIVE: To determine the morphologic and hearing results of the combined application of the palisade cartilage technique and titanium ossicular replacement prostheses in Type III tympanoplasty. STUDY DESIGN: Retrospective review of 61 tympanoplasties. SETTING: Tertiary referral center. PATIENTS: 59 patients (39 women and 20 men, mean age 36 years, range 7-81 years) consecutively operated on because of cholesteatoma, adhesive otitis, chronic otitis media, subtotal tympanic membrane defects, and tympanofibrosis requiring tympanoplasty with ossiculoplasty. INTERVENTIONS: Tympanoplasty Type III, with application of the palisade cartilage technique and total or partial titanium ossicular replacement prosthesis. MAIN OUTCOME MEASURES: Otoscopic findings and hearing results using a four-frequency pure tone average air-bone gap. RESULTS: A recurrent defect was seen in 1 ear (1.6%). The graft take rate was 100%. There were no extrusions of prostheses. Preoperatively, a pure tone average air-bone gap of 0 to 10 dB was seen in 1 ear, 11 to 30 dB in 30, and 31 to 50 dB in another 30 ears. Postoperatively, the corresponding numbers were 11, 41, and 9 ears, respectively. Hearing results were better in the total ossicular replacement prosthesis group. CONCLUSIONS: The palisade cartilage technique is suitable to manage difficult pathologic conditions in middle ear surgery. It was demonstrated that the palisade cartilage technique can be combined safely with titanium ossicular replacement prostheses. Regarding postoperative hearing results, the negative preselection of pathologic conditions must be considered.

Adolescent↗

PubMed2003

Immunohistochemical investigations on external auditory canal cholesteatomas.

OBJECTIVE: The aim of the study was to analyze the biological behavior of external auditory canal cholesteatoma (EACC). The expression and distribution of relevant markers such as transforming growth factor-alpha (TGF-alpha), epidermal growth factor-receptor (EGFR), and the proliferation marker MIB 1 were studied in comparison with normal auditory meatal skin. BACKGROUND: EACC are uncommon and knowledge concerning etiology and pathogenesis is limited. Whether this is a unique entity remains controversially discussed. MATERIALS AND METHODS: Immunohistochemical methods were used to study the expression and distribution TGF-alpha, EGFR, and the proliferation marker MIB 1 on 15 tissues samples. Only the spontaneous form of EACC was included in this study. RESULTS: Positive immunoreactivity for the proliferation marker MIB 1 could be demonstrated in keratinocytes in the basal and suprabasal layers of the epithelium. The number of MIB 1-positive proliferating cells in cholesteatoma was significantly higher than in normal external auditory skin. Cholesteatoma epithelium also showed an enhanced expression of TGF-alpha and EGFR. Inflammatory infiltrate was observed in the perimatrix to various degrees. CONCLUSION: These results suggest that similar to the middle ear cholesteatoma, a chronic inflammatory process underlies the EACC, and the inflammatory stimuli may alter keratinocyte proliferation.

Adult↗

PubMedDate not supplied

Reconstruction of the stapes superstructure with a combined glass-ceramic (Bioverit) implant in guinea pigs.

BACKGROUND: Reconstruction of the stapes superstructure continues to be a problem for otologists. Optimal fixation of implants on the stapes footplate has not yet been achieved. METHODS: We postulated that bony fixation, between implant and stapes, could be confined exclusively to the footplate region by modifying the bioactivity of the implant material. Therefore, after removal of the superstructure in guinea pigs a combined biovitro ceramic implant (Bioverit I and Bioverit II) was placed on the stapes footplate in 10 guinea pigs. As a control, we employed a group of 6 animals in which the stapes superstructure was removed without placing any implant. RESULTS: After 25 weeks the implants were found to be dislocated laterally. We observed fixation with the wall of the middle ear. In the control group we also found new bone formation and even a bow shaped regeneration of the stapes superstructure. CONCLUSION: Combined Bioverit stapedial implants were found to routinely fix to the middle ear wall of the guinea pig. The guinea pigs' enormous potential for bone regeneration in the middle ear ossicular chain make this species unsuitable for exploring hypotheses on human middle ear reconstruction.

Animals↗