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Biomedical subjects

A Eckardt

Publications and source records attributed to A Eckardt.

At least 19 recordsLinked to original sources
PubMed1992

[Differential indication of tracheotomy in oral and maxillofacial surgery].

In the hospital for Oral and Maxillofacial Surgery at the Medical University Hannover 105 tracheostomies were performed between 1980 and 1990. We see a limited indication for a general prophylactic tracheotomy in patients with ablative surgery and microvascular reconstructive procedures. The indication for tracheotomy must be considered in each individual case.

Airway Obstruction↗
PubMed1991

[DNA cytophotometric studies of central giant-cell lesions of the jaw region].

Giant cell nuclear DNA, in 30 giant cell lesions of the jaws, was quantitated by computer-assisted image analysis. DNA content was then used to predict clinical behavior and outcome. Four.nuclei in each of 25 giant cells (total = 100 nuclei) were randomly selected and DNA content was quantitated by the LEITZ Texture-Analysis-System-Plus. DNA in nuclei of normal appearing stromal fibroblasts (n = 20) was similarly measured. DNA index was calculated as the mean nuclear DNA content of giant cells divided by mean DNA content of control fibroblasts. The mean DNA index of aggressive lesions (1.09, S. D. = 0.12) was not significantly different from that of non-aggressive lesions (1.18, S. D. = 0.15) (p = 0.093). The results indicate that nuclear DNA content of giant cells is not useful as a predictor of clinical behavior of giant-cell lesions of the jaws.

Adolescent↗
PubMed1990

Histomorphometric results after late microsurgical nerve grafting of the inferior alveolar nerve of the rabbit.

An experimental study was conducted to evaluate the regenerative potential of the inferior alveolar nerve after nerve transection and microsurgical reconstruction at different intervals. Histomorphometric parameters of regenerating axons were assessed using a computer-assisted image analysis system. A continuous decrease in axon density and a reduction in axon diameter was noted in all groups. The average regeneration rate ranged from 42% to 60%. The results of this study indicate that microsurgical reconstruction of the inferior alveolar nerve is even possible 12 months after nerve transection.

Anastomosis, Surgical↗
PubMed1989

Separation of different receptor-mediated effects of a prostaglandin H2 analogue (U46619) on human platelets by means of human granulocytic elastase and chymotrypsin.

Previous investigations indicated two classes of thromboxane A2/prostaglandin H2 (TXA2/PGH2) receptors on human platelets and suggested that shape change and myosin light chain phosphorylation correlated with the occupancy of high affinity receptors while serotonin release was related to a putative low affinity binding component (Morinelli TA et al., Am J Physiol 253: H1035-H1043, 1987). The current study shows that chymotrypsin destroyed three receptor-mediated responses of platelets to U46619 (a TXA2/PGH2 agonist), i.e. shape change, myosin light chain phosphorylation and serotonin release. Human granulocyte elastase selectively inactivated platelet ability to release serotonin following stimulation with U46619, but it did not affect significantly shape change and myosin light chain phosphorylation. In conclusion, it is possible to separate different receptor-mediated effects of U46619 on human platelets by means of human granulocytic elastase and chymotrypsin.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed1989

Structural and functional characterization of major platelet membrane components derived by limited proteolysis of glycoprotein IIIa.

The authors isolated a product of proteolytic degradation of glycoprotein IIIa (GPIIIa) which is formed on the surface of human platelets during incubation with chymotrypsin and which was previously described as the 66 kDa platelet membrane component. This component migrated with an apparent Mr 62,400 in a non-reduced system of sodium dodecyl sulfate polyacrylamide gel electrophoresis. In a reduced system it yielded two major subunits migrating with apparent Mr 14,000-17,000 and 65,000. The low-molecular weight component began with the NH2-terminal sequence of GPIIIa (GPNICTTR...) and the larger component with residue 348 of GPIIIa (GKIRSKKA...) as deduced from a cDNA clone of this glycoprotein. The two subunits appeared to be linked by one or more S-S bridges supporting the contention that GPIIIa is a highly folded molecule on the platelet membrane. In contrast to GPIIIa, the '66 kDa component' did not bind to GRGDSPK-agarose, to fibrinogen-agarose nor to insolubilized monoclonal antibody recognizing the GPIIb/IIIa complex. The exposure of fibrinogen receptors during the course of incubation of platelets with chymotrypsin preceded the formation of the '66 kDa component' characterized in this study. An intermediate product of GPIIIa proteolysis migrating with an apparent Mr 120,000 in a non-reduced system and Mr 80,000 in a reduced system was identified as a precursor of the '66 kDa component'. The '120 kDa component' was not retained on GRGDSPK-agarose or on fibrinogen-agarose but it was retained on insolubilized antibody recognizing the GPIIb/IIIa complex. Incubation of platelets with porcine pancreatic elastase or human granulocytic elastase resulted in the formation of similar proteolytic degradation fragments.

Amino Acid Sequence↗
PubMed1989

Polyurethane-coated Dacron mesh tray for temporary mandibular reconstruction following resection of oral cancer: clinical results of 27 cases.

During a 3-year period from 1983 to 1986, a polyurethane-coated Dacron mesh tray (Xomed Inc, Jacksonville, FL) was used in 27 cases for temporary mandibular reconstruction in patients who had undergone jaw resection for oral carcinoma. Delayed mandibular reconstruction using the Dacron mesh tray combined with rib grafts was performed in three cases. The Dacron mesh tray technique provides good functional and esthetic results and offers several advantages when compared with metal trays. The success rate was 74%; intraoral perforation was the main reason for early removal of the tray.

Adult↗
PubMed1989

Central giant cell granulomas of the jaws. Nuclear DNA analysis using image cytometry.

Giant cell nuclear DNA, in 30 giant cell lesions of the jaws, was quantified by computer-assisted image analysis. DNA content was then used to predict clinical behavior and outcome. 4 nuclei in each of 25 giant cells (total = 100 nuclei) were randomly selected and the DNA content was quantified by the Leitz Texture-Analysis-System-Plus. DNA in nuclei of normal appearing stromal fibroblasts (n = 20) was similarly measured. The DNA index was calculated as the mean nuclear DNA content of giant cells divided by the mean DNA content of control fibroblasts. The mean DNA-index of aggressive lesions (1.09, SD = 0.12) was not significantly different from that of non-aggressive lesions (1.18, SD = 0.15) (p = 0.093). The results indicate that the nuclear DNA content of giant cells is not useful as a predictor of the clinical behavior of giant cell lesions of the jaws.

Adolescent↗
PubMed1988

Granulocyte-platelet interactions and platelet fibrinogen receptor exposure.

We have examined the interaction of human granulocyte elastase with human platelets. Incubation of human platelets with human granulocyte elastase exposed active fibrinogen-binding sites as evidenced by 125I-labeled fibrinogen binding and spontaneous fibrinogen-induced platelet aggregation. The aggregation of platelets by fibrinogen occurred at low concentrations of human granulocyte elastase (0.5-1 microgram/ml). Platelets pretreated with human granulocyte elastase exposed an average of 10,500 fibrinogen binding sites per platelet, i.e., about one-third the number of binding sites exposed by optimal concentrations of ADP. With the use of a polyclonal antiplatelet membrane antibody, the glycoproteins IIb (GPIIb), IIIa (GPIIIa), and a 60,000-Da (60 kDa) protein (66 kDa in a reduced system) derived from GPIIIa were immunoprecipitated from the surface of detergent extracts of human 125I-radiolabeled platelets pretreated with increasing concentrations of human granulocyte elastase. Experiments performed by immunoblotting with use of polyclonal and monoclonal antibodies directed to GPIIIa showed that pretreatment of human platelets with granulocyte elastase resulted in the appearance of an additional proteolytic derivative of GPIIIa migrating with an apparent molecular mass of 120 kDa in a nonreduced system. GPIIIa appears to be the preferred substrate of elastase, since GPIIb was not degraded by human granulocyte elastase. We conclude that 1) the proteolytic action of human granulocyte elastase on platelet GPIIIa results in the formation of two major hydrolytic products, and 2) human granulocyte elastase exposes active fibrinogen-binding sites associated with the GPIIb/GPIIIa complex, resulting in direct platelet aggregation by fibrinogen.

Adenosine Triphosphate↗
PubMed1978

[Long-term study with the novel cardiac glycoside meproscillarin (author's transl)].

In a multicentre open therapeutic study 64 physicians provided 650 questionnaires of patients who had been treated with the new cardiac glycoside 14-Hydroxy-3beta-[(4-O-methyl-alpha-L-rhamnopyranosyl)oxy]-14beta-bufa-4,20,22-trienolide (meproscillarin, Clift) for more than 3 months; 647 questionnaires had been filled in completely and could be evaluated. The major part of all patients suffering from heart failure of the severity degrees I--III required 2 tablets of 0.25 mg, a smaller part 3 tablets to achieve complete recompensation and/or maintenance of compensation, which was possible in 79% of all cases. The rate of side effects corresponded to that of other cardiac glycosides.

Adult↗