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Biomedical subjects

A Thiede

Publications and source records attributed to A Thiede.

At least 307 records · Page 17Linked to original sources
PubMed1978

[Experimental microsurgery in rats (author's transl)].

Experimental microsurgical techniques using a magnifying glass and surgical microscope enable nearly all abdominal operations and organ transplantations to be performed in rats. Vascular and prosthetic segment implantations, portocaval anastomoses, heterotopic heart-, kidney-, spleen-, pancreas-, and liver transplantations some with superselective organangiography, are excellently demonstrated. Continuing research in microsurgery has considerably expanded experimental surgery and given new impulse to clinical surgery.

Abdomen↗
PubMed1978

[Significance of the hemodynamics for the extent of the rejection. Comparison of immunological reactions in artery transplantation in high pressure and vein transplantation in low pressure systems in matching inbred rat strain combinations].

Systemic sensitization is induced by arterial transplants in the high pressure system and by venous transplants in the low pressure system. In aorta transplantation the severity of the rejection corresponds directly to the immunogenetic differences between donor and recipient; the efferent limb is triggered into action. For application of allogeneic veno-venous transplants this is not the case: despite systemic sensitization, even strongly allogeneic venous transplants are maintained over long periods. A threshold value is not reached unless there is presensitization with strong antigens, after which morphologically comprehensible rejection reactions, i.e. round cell infiltration, are demonstrated even in veno-venous transplants.

Animals↗
PubMed1976

[Postoperative changes in immunoglobulin-concentrations after splenectomy. A prospective survey series (author's transl)].

The three immunoglobulin classes A, G and M were quantitatively determined through immune diffusion preoperatively as well as in the first 60 days in 31 patients after splenectomy and the results were statistically evaluated. In comparison with the initial preoperative values, a temporary, significant elevation of the serum concentration of the IgA and IgG was found, whereby the IgA concentration on the 60th postoperative day corresponded already to the preoperative initial values, whilst the IgG were at this time still significantly elevated. There was a beginning significant decrease in serum concentration of the IgM between the 15th and 20th postoperative day, which was very pronounced on the 60th day. This determination coincides with the half-life time of the IgM and can be regarded as an indication for a localisation of the IgM producing cells in the spleen.

Female↗
PubMed1976

[Significance of various implantate localizations of Sparks prostheses, experimental studies in rats].

Our investigations show that Sparks prostheses after subcutaneous implantation are suitable for vascular grafting. At the end of the organization period the connective tissue becomes strong, and after the third and fourth weeks collagenous and elastic fibers can be seen. Ten weeks after s.c. implantation, collagenous fibers predominate. After this the Sparks prostheses can be used as a vascular graft. Intraperitoneal implantation, however, shows a histologically different picture with characteristic findings: only fat cells can be observed, a strong granulation tissue with elastic and collagenous fibers is not present. After intraperitoneal implantation Sparks prostheses are therefore unsuitable for vascular grafts.

Animals↗
PubMed1976

[Allogeneic small intestine transplantation in inbred rats. Transplantation technic and morphological findings].

In a RtH-1-incompatible in-bred rat strain combination (Brown Norway leads to LEWIS), small intestinal transplantations were carried out using the bypass technique. 5, 10 and 12 days after grafting, the transplanted intestines were histologically examined. On the 5th day primarily granulocyte cell infiltration was found. On day 10 and 12 there was an increase of lymphocyte plasma cellular infiltration. The small intestine showed increasing congestion of the lymphatic vessels, an edematous saturation of the stroma as well as loss of the small intestinal-specific epithelial layer.

Animals↗
PubMed1976

[Value of formalin-fixed, allogeneic veins for vessel substitution in long-term tests. Experimental studies of the problem of immunological reactions on RtH-1-incompatible various rat-donor-recipient combinations].

Experiments on an immunogenetically standardized inbred rat strain combination were necessary to determine whether immunological reactions have an effect on the increase and transformation processes of allogeneic formalin-fixed venous implants. By using a RtH-1-incompatible allogeneic strain combination we found that immunological mechanisms-humoral or cellbound-are insignificant to such venous implants. The formalin-fixing procedure caused the antigenicity to lose its effectiveness. Thus, the submitted material shows that immunological reactions are not responsible for delayed alterations in such venous implants.

Animals↗
PubMed1975

[Allogenic and xenogenic aortic segmental transplants in inbred rats angiographically demonstrable vascular changes (author's transl)].

In order to make a systematic study of the significance of immunological reactions in vascular grafts, segments of abdominal aorta (4-5 mm long) were grafted into inbred rats. Four experimental combinations were used: I. syngeneic (CDF leads to CDF), II. weakly allogeneic (LEW leads to CDF), III. strongly allogeneic (BD 5 leads to CDF), IV. xenogeneic (guinea pig leads to CDF). After 100 days the gaft was macroscopically evaluated, angiographed and measured. Whereas no alterations of the vascular wall were found in group I, the degree of aneurysm formation increased significantly corresponding to the degree of histoincompatibility in the other groups: group II showed little aneurysm formation (medicum size 1.27 fold), group III more pronounced (1.71 fold) and group IV very pronounced (3.9 fold) with partial thrombosis in 3/5 of the cases. These findings are interpreted, as functional and morphological consequences of the immunogenicity of the aorta tissue. The conclusion was reached that the degree of histoincompatibility should be more carefully considered, also in vascular grafting.

Animals↗
PubMed1975

[Histological and histochemical evaluation of the cellular infiltration of s.c. implanted sparks prothesis. Experiments on rats (authors transl)].

Sparks-prothesis of 3 mm diameter were implanted into inbred rats and withdrawn after one to ten weeks. They were then fixed in Formalin and embedded in Paraffin and Metachrylat. After cutting (2.5 mu), the histological and histochemical parameters were examined. Cellular infiltration was studied after a certain period of time. The basic results of the genesis of that infiltration are given as follows: during the first two weeks following the s.c. implantation, derivates of monocytes (cells which play an imminent and important role during arterial replacement) were found. After the third and fourth week collagenous and elastic fibers could be seen, the connective tissue became stronger. The most favorable time for grafting can be evaluated by these experiments.

Animals↗