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Biomedical subjects

K Jahnke

Publications and source records attributed to K Jahnke.

At least 19 recordsLinked to original sources
PubMed1992

[Tympanoplasty].

The first goal of tympanoplasty as treatment for chronic otitis media is to obtain a clean, disease-free ear, the second one hearing improvement. Prerequisite for success is the sufficient functioning of the inner ear as well as of the Eustachian tube. Therefore, patients very often have to undergo adjuvant treatment such as adenotomy, rhino-surgery and surgery of the paranasal sinuses. Microsurgery of the ear has become very refined. Thus even after removal of extensive inflammation it is now possible to rebuild the middle ear using various proved as well as newly developed biomaterials. Often a two-stage procedure is advisable for cholesteatoma surgery. In this disease meticulous postoperative care and longterm follow-ups are very important.

Cholesteatoma↗
PubMed1992

[Diagnostic aspects of isolated sphenoid sinusitis].

The clinical occurrence of isolated sphenoid sinusitis is rare. Due to a long history and few initial symptoms, diagnosis of this potentially fatal infections can be difficult. Radiological aspects in 10 patients are presented (e.g. type and design of examination and whether inflammatory or destructive changes could be shown), as well as clinical aspects (cranial nerve palsy, concurrent inflammation, duration of disease and therapy). CT proved to be superior in diagnosing the extent of any bony changes, while MRI was more useful in detecting inflammation.

Adolescent↗
PubMed1992

[New ceramic implants for reconstruction of the ear ossicle chain].

Due to new technologies it is now possible to produce more ingeniously shaped ceramic implants. The essential characteristics of our newly designed implants are perforations at the distal end of the shaft which allow a better medial anchorage. Intraoperatively they will be filled with small pieces of connective tissue or periosteum to improve the position of the implant on the stapes head or the foot plate. We also want to comment on the fundamental importance of a stable reconstruction of the tympanic membrane level, e.g. in cases of a missing handle of the malleus. With a judicious indication and correct techniques the functionel long-term results of ceramic implants will be excellent.

Aluminum Oxide↗
PubMed1991

E-cadherin expression in squamous cell carcinomas of head and neck: inverse correlation with tumor dedifferentiation and lymph node metastasis.

Tissue sections of 32 squamous cell carcinomas (SCCs) of the head and neck were investigated for the expression of the epithelium-specific cell adhesion molecule E-cadherin. We found that E-cadherin expression is inversely correlated both with the loss of differentiation of the tumor and with lymph node metastasis. The well-differentiated SCCs expressed E-cadherin, often as strongly as the normal stratified epithelium (12 cases were tested); the moderately differentiated SCCs expressed intermediate amounts of E-cadherin or were heterogeneous (15 cases were analyzed); whereas the poorly differentiated SCCs were all E-cadherin-negative (five cases were investigated). Furthermore, seven of eight infiltrated lymph nodes of SCCs were E-cadherin-negative. These data indicate that the loss of the cell adhesion molecule E-cadherin in fact plays an important role in the progression of human squamous cell carcinomas, i.e., that down-regulation of expression is associated with dedifferentiation and metastasis of the tumor cells in vivo.

Adult↗
PubMed1991

[Computerized tomography in persisting stapedial artery].

About 30 cases of a persistent stapedial artery have been described in the literature so far. It is usually associated with other malformations, suggesting an inhibition of normal embryonic development. For the first time, it was possible to demonstrate this using high-resolution computed tomography.

Adult↗
PubMed1991

Freeze-fracture studies on vestibular secretory cells and melanocytes.

The fine structure of dark cells and melanocytes of the crista ampullaris was studied by using the freeze-fracture technique. For these studies we used normally pigmented guinea pigs, as well as those with experimentally induced endolymphatic hydrops. The results suggest the vestibular secretory region to be an area of unusually high dynamics. In the experimental animals the cell processes of the melanocytes gain closer contact with the dark cells as well as with the subepithelial capillaries. There is considerable evidence of secretory transfer of different substances, especially ions.

Animals↗
PubMed1990

[Hearing ability after cholesteatoma surgery].

Five years after cholesteatoma surgery (primary operation in 1981 and 1982) we examined 112 patients to determine the hearing and clinical results in follow-up. In 12 (10.7%) patients Cholesteatoma recurred. During the period of follow-up 28 (25%) ears underwent second surgery. Comparing the open (50.9%) with the closed (49.1%) technique a better air bone gap was gained for the closed technique procedures. This was confirmed when the different types of tympanoplasty were compared between the two groups. In 69.5% of the closed procedures the air bone gap was less than 20 dB, whereas the value for the open technique was 51.1%. In 30 patients a second-look operation was recommended, which was performed in 15 persons; 8 recurrent cholesteatoma were detected. Reducing the application of the closed procedures from a rate of 78.1% in the years 1971/1972 to 49.1% in 1981/1982, we saw a distinct reduction of cholesteatoma recurrence from 25% in 1971/1972 to 10.7% in the present study. The data show that the advice for a second-look operation should be seriously considered. Furthermore, the study indicates that due to modern tympanoplastic techniques also in longterm follow-up good hearing results can be obtained.

Adolescent↗
PubMed1990

Vitreous carbon: a new material for middle ear ventilation tubes.

Synthetic allotropic carbons have been used for nearly 20 years as biomedical implants. Vitreous carbons in particular appear to possess very favourable biocompatibility characteristics. The middle ear compatibility of Sigradur has been tested in the mastoid bulla of gerbils. The period of implantation varied from 1 to 13 months. Light and electron-microscopic examination revealed good middle ear tolerance of the material, especially when the surface had not been modelled. Our animal experiments suggest that this material could be suitable for ventilation tubes, but was less ideal for ossicular replacement prostheses, particularly because of the specific surface properties. Consequently, we have used such carbon ventilation tubes in 38 patients. The results obtained using this material were excellent thanks to the favourable biocompatibility, advantageous surface properties, and low weight.

Animals↗
PubMed1990

Crystallization of prostaglandin-H synthase for X-ray structure analysis.

Prostaglandin-H (PGH) synthase from ram seminal vesicles is a dimeric integral membrane protein of molecular weight 140 kDa. PGH synthase is a key enzyme in the biosynthesis of prostaglandins, has cyclooxygenase and peroxidase activities, and contains heme as a coenzyme. In the peroxidation step of its reaction. PGH synthase can use xenobiotics as co-substrates and can catalyze the metabolic activation of carcinogens such as diethylstilbestrol. To gain a detailed understanding of the inner workings of PGH synthase, we are investigating its three-dimensional structure by X-ray crystallography. A purification procedure was established that yields stable homogeneous PGH synthase that is at least 80% holoenzyme. The crucial aspect is the proper choice of type and concentration of detergent in all steps of the procedure. Single crystals can be obtained from concentrated solutions of PGH synthase in the presence of polyethylene glycol 4000 as a precipitant. Crystallization occurs during gas phase equilibration with a concentrated salt solution. The enzyme solution becomes turbid and forms a second liquid phase in which PGH synthase crystals grow up to 0.2 mm in length in the course of days. Manipulation of these crystals is very difficult due to the small volume of the growth phase. The crystals dissolved rapidly in all aqueous media into which they were transferred for mounting in X-ray capillaries. Therefore, we have not yet been able to demonstrate their true X-ray scattering power. A crystal provisionally dry mounted diffracted to about 8 A resolution.

Animals↗
PubMed1989

[Lermoyez syndrome. Clinical aspects and follow-up].

The clinical data and follow-up of five patients with Lermoyez syndrome are reported. Three of them presented with marked lesions of the cervical spine. Serological antibodies against nuclei and sarcolemma as well as against heart muscle and gastric cells were found. Tests of the sera against guinea pig cochlear tissue showed antinuclear antibodies in one patient and against basilar membrane structures in another. Three sera were negative despite positive heterologous finding. Therapy included infusions active on the inner ear, decompression of the saccus endolymphaticus in two cases and physiotherapy for the cervical spine. These achieved marked improvement or long term relief. The available literature supports the conclusions based on pathophysiological considerations of our results. We cannot postulate an independent immunopathogenesis for Lermoyez Syndrome, but we think that the immunological findings conform with the clinical and experimental data found in the literature.

Autoantibodies↗
PubMed1988

[Microsurgically revascularized transplants for covering defects in the midface area].

Radical or palliative resection of tumours in the region of the midface often require a combined approach by maxillary-facial surgeons, as well as by oto-rhino-laryngologists. This holds true not only for the excision of the tumour, but also for adequate reconstructive measures. These are necessary to alleviate as much disfiguration as possible, and to ensure correct physiological and mechanical function, i.e. nasal patency and chewing ability. We are aware of the increasingly important rôle of microsurgically transplanted myocutaneous and osteomyocutaneous flaps. In this paper we demonstrate our operative technique by means of several selected cases, primarily in the use of the following pegged-vascularized flaps: 1. free myocutaneous latissimus dorsi flaps, 2. iliac osteomyocutaneous flaps and 3. modified rectus abdominis flaps.

Aged↗
PubMed1987

Light and electronmicroscopic studies on Polycel ossicular replacement prostheses.

Recently, a new form of porous high density polyethylene (Polycel) has been promoted for use in ossicular chain reconstruction. However, we have found no reports of investigation of the fate of this material used for this purpose in either animals or man. This study was undertaken to look at the tissue tolerance and fate of Polycel in the middle ear of gerbils before its extensive use in humans. We present the light and transmission electromicroscopic findings from these prostheses, removed from the middle ear between 1 and 5 months post-implantation. The results are similar to those found with Plastipore, showing a strong foreign body reaction and the likelihood of phagocytic consumption. As with the other porous plastics, we have reservations about the use of Polycel for ossicular reconstruction.

Animals↗
PubMed1987

[Ultrastructure of the vestibular apparatus in patients with Meniere's disease].

The vestibular labyrinth of eight patients with Menière's disease obtained by translabyrinthine vestibular neurectomy or transtympanal labyrinthectomy was studied with the light microscope and transmission electron microscope. Previous invasive therapy was transtympanal application of gentamicin in one patient and endolymphatic sac surgery in two patients. Some of the pathological findings were unspecific, e.g. mucoid degeneration of the subepithelial spaces, fibrous long spacing collagen and high amount of lipofuscin in different cell types. Cuticular laminated structures were seen in some of the specimen. A most interesting finding was the discrepancy of large numbers of sub- and intraepithelial nerve fibers and a significant degeneration of vestibular sensory cells with vacuoles and filament bundles. This points out the importance of combining labyrinthectomy and vestibular neurectomy in late stages of unilateral Menière's disease.

Adult↗
PubMed1987

[The importance of electron microscopy in research and clinical otorhinolaryngology].

The current state of electronmicroscopy in research and clinical applications in otorhinolaryngology is reviewed. The recognition of cytoarchitectonic relationships by means of transmission electronmicroscopy, tracer studies and freeze fracture technique provides functionally interesting findings on the sensory epithelium and the permeability barriers of the inner ear. Knowledge of the fine structure of the animal and human ear also facilitates the understanding of the pathomechanism of the inner ear. Experimental and clinical findings of seromucotympanon are also described, as well as the morphology of normal and diseased respiratory mucosa. A viral origin for laryngeal papilloma is clearly confirmed. New findings in the pathohistology of otosclerosis are described. Finally, the use of electronmicroscopy in the diagnosis of ENT tumours is considered. The demonstration of pathognomonic cell organelles is useful not only in the diagnosis of rare tumours, e.g. esthesioneuroblastoma or carcinoid. The epithelial origin of anaplastic tumours can also be shown or excluded. Electronmicroscopy also offers important clues in the case of neck metastases from an unknown primary tumour.

Animals↗