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Biomedical subjects

D Stock

Publications and source records attributed to D Stock.

At least 37 records · Page 2Linked to original sources
PubMed1992

Auditory filter bandwidths as a function of level at low frequencies (125 Hz-1 kHz)

Auditory filter bandwidths were measured using the symmetric notched-noise method in five normally hearing listeners at four masker levels (40-70 dB SPL/Hz in 10-dB steps) and four probe frequencies (125-1000 Hz in octave steps). Accurate stimulus spectrum shape and level were ensured by use of a headphone monitoring technique. Auditory filter bandwidths decreased with decreasing frequency from 1 kHz down to 125 Hz. On the whole, bandwidths increased with increasing level, but the effect of level on bandwidth was greater as frequency increased, with little or no effect of level at 125 Hz. Insofar as the results from the notched-noise method reflect basilar membrane vibration patterns, basilar membrane mechanics appear to become less nonlinear as one approaches the apex of the cochlea.

Adult↗
PubMed1989

Biomechanical considerations on some postoperative problems of directly anchored total hip replacements.

Uncemented total hip replacements have resulted in a higher incidence of postoperative complaints than cemented ones. The theoretical explanation of these not well defined discomforts is based on the differences of the stress and strain fields around the distal portions of the femoral components. While the noncemented stems are press-fitted and most of them tapered distally, thus creating hoop stresses and strains in the surrounding cortical bone, the shrinkage of the cement prevents these mechanical irritations. The relatively sudden disappearance of these discomforts within the first 2 postoperative years is attributed to the shift of the main zone of load transmission from the distal to the proximal portion of the stems following bone remodeling.

Biomechanical Phenomena↗
PubMed1987

NCL-5D3: a new monoclonal antibody recognizing low molecular weight cytokeratins effective for immunohistochemistry using fixed paraffin-embedded tissue.

Production of a new monoclonal antibody designated NCL-5D3 is described. The antibody recognizes several low molecular weight cytokeratins, in particular cytokeratin Moll number 8 as determined by immunoblotting studies, and is highly effective for immunocytochemistry using routinely processed paraffin-embedded material. Staining is enhanced by prior treatment of the sections with trypsin. Assessment using a wide variety of normal and neoplastic tissue indicates reactivity with all tissues of simple or glandular epithelial origin, and in addition with many squamous carcinomas. Thus the antibody should prove of value in diagnostic histopathology.

Antibodies, Monoclonal↗
PubMed1983

[Detection of gamma globulin and Inv markers in vaginal secretions].

The Gm 1, Gm 2, and Inv 1-factors in the vaginal secretion are in accordance with the corresponding serum features to be expected basically. Deviations are possible. They are either caused by interference factors in the vaginal secretion or other factors which are not, however, always detectable in each case. It is important to test in advance the appropriate dilutions for the particular antiserum charges and to examine extracts of the samples to find out whether they have the necessary concentration.

Female↗
PubMed1982

[Detection of hereditary enzyme characteristics in vaginal secretion].

Upon investigation of semen- and blood-free vaginal swabs using starch gel electrophoresis the Phosphoglucomutase type was clearly identified in about 40%. Using cellulose acetate membrane electrophoresis PGM could not be demonstrated. In all cases the results correspond with those obtained in blood. No relation was found between secretor type (determined in saliva) and PGM typing. In vaginal material the following could not be determined: Adenylatkinase (AK) using starch gel electrophoresis, Esterase D (EsD) using cellulose acetate membrane electrophoresis, and Glyoxalase I (GLO) using agarose gel thin-layer electrophoresis.

Adenylate Kinase↗
PubMed1982

The influence of fine surface structures on the osseo-integration of implants.

The availability of inert materials like dense, pure Al2O3-ceramic or titanium allows the study of purely biomechanical influences of surface modulations or lacune on the osseo-integration of implants at different locations of the skeleton. The discovery of the "load-line-shadow" phenomenon in lacune of dental implants and the observation of the same effect in the grooves of hip sockets (Lindenhof type) indicate the general validity of the rules controlling the remodelling ability of bony tissue. Their application to the problems concerned with load transmission via surfaces which are mainly loaded by shear can contribute to achieve a well defined anchorage of implants.

Aluminum Oxide↗
PubMed1980

Results of endoprosthetic hip joint replacement with the aluminum ceramic-metal composite prosthesis "Lindenhof".

The first clinical results of the Lindenhof ceramic-metal composite prosthesis implanted in our hospital in Freiburg are presented. We observed that same favorable early results as the conventional prostheses in a correct position. The implants are incorporated into the bone within 8-12 weeks. The radiographic films show the adaptation of the supporting bone around the ceramic socket. We explain the failures due to our initial lack of technical experience and/or anatomical deformation of the pelvic bone. complications caused by the post-operative treatment during the 12 weeks following surgery did not occur. The combination of a cemented metal femoral component with a ceramic head seems to be a reasonable compromise to use the favorable physical and biochemical properties of the bioceramic material as long as there is no satisfactory solution for a stable cementless fixation of the femoral stem in to the bone. The advantages of the Lindenhof prosthesis predominate the disadvantages: expensive instruments and a post-operative treatment of several months.

Adult↗
PubMed1979

The treatment of osteoarthritis with unconstrained and constrained knee prostheses.

The first cases of knee prosthesis implantation at the orthopaedic department of the Freiburg university hospital are discussed. Surgery was indicated by advanced osteoarthritis which showed no improvement under conservative treatment. Indications concerning the choice of knee joint replacement with unconstrained or constrained prostheses are also discussed. Considerations of these indications as well as operative technique and consequent functional treatment usually produced good results. Follow up studies show equally good results for the GSB-total knee endoprosthesis (constrained) as for the surface type prosthesis (unconstrained).

Female↗
PubMed1977

[The ball deformation method, a new method in oryhopedics for the quantitative threedimensional force flow determination in bone models].

The long term results of 1135 followed up patients after coxarthrosis-operations showed, besides being very effective, typical complications and problems. The bone bearing strength and strain has to be known exactly. In the past there was no method known for quantitative 3dimensional measurement of strength flow in case of biomechanical alteration by operations. The ball deformation system is introduced which was tested on bone models.

Arthritis↗
PubMed1977

[Results of surgical correction of valgus deformity in childhood (author's transl)].

After surgical correction of valgus deformity in childhood by varus-rotations-osteotomy an increased incidence of recurrence of valgus is reported. The present analysis was performed to defind the indication for varus-rotations-osteotomy. 152 cases with operated hip joints were reviewed with regard to the clinical and radiological development. We found out that "postoperative insufficiency of the gluteal muscles = pathological revalgisation" does not induce revalgisation as postulated by other authors. Also discharging limping of the hip joint does not cause revalgisation. Postsurgical insuffiency of adductor muscles is not an obligatory but a potential cause for development of pathological revalgisation. And there is not correlation between the less frequent recurrence of anteversion and the pathological revalgisation, also there could not be found a correlation to lesions of the a trochanteric epiphysis due to the operation, or to the time of metal removing. According to our results the complication rate of recurrence of valgus becomes less frequent by age corresponding alteration of the CCD angle, even when it cannot be prevented.

Adolescent↗
PubMed1977

[Radiological aspects of knee prostheses (author's transl)].

The radiological evaluation of knee prostheses has its own criteria. Exact implantation of prosthetic components, correction of axial deviations between femure and tibia, bone density near to the prosthesis, width of the radiolucent zone, and the degree of femoropatellar arthrosis are important features. The analysis of 47 knee prostheses showed a less periarticular soft tissue calcifications than in hip prosthesis. Fracture of palacos is not rare and may lead to intraarticular loose bodie's.

Aged↗
PubMed1976

[Perthe's disease, results of conservative treatment (author's transl)].

After a survey of causation, symptoms and therapy of Perthe's disease, clinical and radiographic findings of 62 children treated conservatively are described. For evaluation the "plumpness quotient" is introduced, in addition to the known radius-, joint-surface- and epiphysus quotients, as a measure of deformity of head and neck of femur. Besides consequential avoidance of weight-bearing, age, length of history and first radiologic findings are of decisive importance. The results of conservative treatment are no worse than those of surgery.

Age Factors↗
PubMedDate not supplied

[Indomethacin--short-term therapy vs. single low dosage radiation for prevention of periarticular ossifications after total hip endoprosthesis].

INTRODUCTION: With a general incidence of about 40% periarticular ossifications (PAO) constitute one of the more frequent complications after total hip arthroplasty. A prospective, randomized therapy--study investigates the prophylactic values of Indomethacin-Short-Term-Therapy and Single-Dose-Radiatio, respectively. MATERIAL AND METHODS: Consecutive patients for elective, cementless THA were randomized; the Indomethacin-Group (A, n = 31 at the end of the study) was admitted 100 mg Indomethacin/supp. at the day of operation and 3 x 25 mg orally from postoperative day 1 to 10. Other NSAID were not given. The Radiatio-group (B; n = 19) was irradiated by a single dose of 6 Gy within postoperative days 1 to 4; no NSAID were admitted. Follow up was at dismissal and after 6 (NU 1) and 12 (NU 2) months. Incidence and severity of PAO and the clinical objective and subjective results were registered. RESULTS: Age- and side-distribution as well as the etiologies were comparable in both groups. All patients took part in NU 1 and 90% in NU 2. There were no major differences in the incidence of postoperative PAO in both groups. In 68% (A) and 53% (B), resp., there were no PAO at dismissal and after six months, PAO of Brooker Grade I and II were seen in 30 (A) and 47% (B), resp., PAO of Grade III and IV--those having generally clinical relevance--did not occur at all. These results were confirmed after 12 months. The clinical objective result ameliorated between admission and dismissal by an average of 3.5 points and by another 2 points between dismissal and NU 2. DISCUSSION: The results show that Indomethacin-Short-Term-Therapy as well as Single-Dose-Radiatio with 6 Gy can reliably prevent the occurrence of severe PAO. Both therapeutic concepts therefore can be employed as prophylaxis in primary endoprosthetic operations. The choice between the two procedures will then mainly be determined by given logistic conditions in the clinic, specific contraindications of the patient and financial considerations.

Adult↗
PubMedDate not supplied

[Further development of the graded-shaft fixation principle].

A new concept is presented for the design of total hip prostheses. After the discussion of the commonly used gliding materials the use of ceramic-ceramic gliding surfaces is justified in respect to its minimal wear rate. The most important biomechanical recommendations concerning the design of femoral stems and ceramic acetabular cups are summarized. Own clinical results with a ceramic-ceramic cementless hip endoprostheses are presented. A new concept of femoral stem fixation is introduced in consequence of those biomechanical recommendations and of own clinical experiences. 4 photographs are showing the new stem design.

Biomechanical Phenomena↗
PubMedDate not supplied

[Aggressive fibromatoses in orthopedics].

Aggressive fibromatoses which may develop either in soft tissue or in the bone present considerable problems for the pathologist trying to establish a diagnosis as well as for the radiologist and surgeon. In radiographs, a destruction of the soft and osseous tissue is seen which suggests a malignant tumor. Histologically a monomorphic connective tissue prevails in the biopsy showing no essential signs of malignancy. Under pathoanatomical aspects often a benign proliferation of the connective tissue is assumed. Surgically the tumor may either be removed in a too radical and mutilating way, or the excision may remain incomplete. Two cases of desmoplastic bone fibroma (aggressive fibromatosis in the ulna and in the sacrum) are described in which the complete tumor removal led to healing, whereas the incomplete excision of the tumor resulted in recurrences. Aggressive fibromatosis represents a semimalignant tumor which has a locally destructive and invasive growth tendency but does not metastasize. The various fibromatoses are defined with regard to their biological growth tendency and the therapeutic consequences are discussed.

Adolescent↗