[The malignancy potential of colorectal polyps--histomorphometric, histochemical and immunohistochemical study of the dysplasia-carcinoma sequence]. / Malignitätspotential kolorektaler Polypen--histomorphometrische, histochemische und immunhistochemische Untersuchung zur Dysplasie-Karzinom-Sequenz.

Colorectal polyps are usually diagnosed endoscopically and are simultaneously removed. Since adenomatous polyps tend to become malignant, these deserve special attention. In order to prevent carcinomas arising from pre existing adenomas, a precise analysis of the lesions in the mucous membrane of the polyps with regard to their malignancy potential is very important. Morphometric methods and determination of proliferation kinetics enable the dignity of a neoplasia to be assessed. Sporadic colorectal polyps were examined to what extent the morphometric analysis of nuclear area, the silver staining of nucleolar organizer regions (AgNORs) and the immunohistochemical staining of the Ki67 antigen permit further differentiation of the growth pattern of the tumor. Tissue from 50 hyperplastic polyps, 50 tubular and 50 tubulovillous adenomas was endoscopically removed and investigated, whereas pure villous adenomas were not examined due to their relative infrequency. These tissues were compared with biopsies of normal colonic mucosa and also with invasive adenocarcinomas. The Ki67 score shows that the proliferative activity is not significantly different between normal colonic mucosa and hyperplastic polyps, however there is a noticeable difference between the proliferation of the former types and colorectal neoplasias. The staining of the NORs does not reveal differences between the various grades of dysplasia in the adenomas, and therefore proves to be inadequate for differentiation, whereas morphometric and immunohistochemical measurements reveal appreciable selectivity. No correlation is observed between the parameters from the morphometric, histochemical and immunohistochemical analysis. Using the methods mentioned above the dysplasia-carcinoma-sequence can be clearly differentiated, however the validity of the different measurements is very variable.(ABSTRACT TRUNCATED AT 250 WORDS)

Free transplantation of fat autografts expanded by tissue expanders in rats.

Inguinal fat pads of 28 rats were expanded by tissue expanders for 10 days and transplanted to the back of the same animal. The non-expanded contralateral inguinal fat pads were also transplanted and served as controls. Histology showed that adipocytes lose their lipid droplets under mechanical pressure; the expanded adipocytes have an elongated contour with a central nucleus. By the end of the expansion period, the thickness of the fat pads had decreased by 53%. One week after transplantation, expanded fat grafts had regained their previous volume with little sign of necrosis. Among normal adipocytes numerous smaller cells, containing multiple vacuoles, were seen. In contrast, about 25% of the substance of the non-expanded control fat graft consisted of necrotic oil cysts. These findings indicate that pre-expanded fat grafts survive better.

[Microsurgical heterotopic ovary transplantation. A preclinical study]. / Mikrochirurgische heterotope Ovartransplantation. Eine präklinische Studie.

Free heterotopic autologous ovary transplantation might be a method to prevent iatrogenic radiocastration in case of Hodgkin's disease. Though first promising clinical case reports have been published, almost no experimental basic data are available. It was the aim of this study to develop a transplantation model in order to evaluate and improve operative technique and perioperative management preclinically. Whereas results in pilot transplantations on minipigs were impaired by the disposition to wound infections on the implantation site, transplantation on Beagle dogs proved to be a suitable model. Eleven transplantations have been performed (five in minipigs, six in Beagle dogs). The success rate of intact preserved transplants was 45% with an observation time of three months for the minipigs and 9 +/- 3.7 months for the dogs.

An improved model for rat liver transplantation including arterial reconstruction and simplified microvascular suture techniques.

For experimental liver transplantation in the rat, the models that have been used most frequently do not include reconstruction of the arterial blood supply to the liver. In these procedures, specially developed cuff anastomoses rather than the conventional microvascular suture technique are used almost exclusively in the recipient operation, so that the anhepatic time is minimized. In this study the technical details of an improved rat model for orthotopic liver transplantation are described. During the donor operation in this experimental method, the liver is prepared with an arterial pedicle that includes the abdominal segment of the aorta, permitting perfusion in situ of the portal vein as well as the hepatic artery. The transplantation of the excised donor organ into the recipient site is carried out with simplified microvascular suture techniques and includes reconstruction of the arterial supply to the liver. Anastomosis of the bile duct is accomplished by choledocho-choledochostomy with a splint technique and supplemental suturing. For the entire procedure, magnifying glasses with 2- to 2.5-fold magnification are sufficient. When this technique has been mastered, the average duration of the anhepatic phase is about 20 min, well below the critical 30-min limit for survival of the experimental animals. As proficiency increased, the perioperative mortality was reduced to 9.2% (n = 130). With the combination of portal and arterial in situ flushing during the donor operation and the rearterialization of the transplant during the recipient operation, the clinical conditions can be approximated more closely than is possible when the transplanted rat liver is supplied only by the portal vein. Use of microvascular suture techniques, without cuff anastomoses, reduces the need for ex situ handling of the donor organ.

Simplified microvascular suture techniques for rat liver transplantation as a microsurgical model with arterial blood supply.

The methods for liver transplantation in the rat mainly used do not include reconstruction of the arterial blood supply to the liver. Furthermore, to ensure a short anhepatic phase these methods almost all entail specially developed cuff anastomoses in the recipient operation instead of the conventional microvascular suture technique. Thus an acceptable survival rate can be attained in the experimental animals. This detailed description of simplified microvascular suture techniques is intended to present an alternative to the cuff anastomoses used almost exclusively. In the donor operation with this method, the liver is dissected with an arterial pedicle including the abdominal segment of the aorta, and the liver is flushed in situ not only via the portal vein, but also via the hepatic artery. The organ is implanted in the recipient animal using simplified microvascular suture reconstruction of the arterial blood supply to the liver. Use of telescopic spectacles with 2-fold magnification has proven to be adequate for the entire procedure. With mastery of this method of rat liver transplantation, the average duration of the anhepatic phase is about 20 min, substantially below the 30-min limit which is critical for the survival of the experimental animals. The donor operation requires about 60 min, and the recipient operation 70 to 80 min. With this method, the spectrum of investigations on liver transplantation which are possible in the rat is substantially extended in that clinical conditions can be reproduced very much more exactly by combination of portal and arterial in-situ flushing in the donor operation and rearterialization of the transplant in the recipient operation, as compared to the transplanted rat liver being supplied only with portal venous blood.

[Effects of a retrograde arterial perfusion by arteriovenous anastomosis on normal and postischemic skeletal muscles. Clinical observations and morphologic studies of the hind leg of the rat]. / Auswirkungen einer retrograden arteriellen Perfusion durch arterio-venöse Anastomosierung auf normale und postischämische Skelettmuskulatur. Klinische Beobachtungen und morphologische Untersuchungen am Hinterlauf der Ratte.

Arterio-venous anastomosis were recommended by some authors for tens of years especially in the revascularisation of acute and chronic ischemic extremities. A retrograde arterial perfusion was produced by microsurgical end-to-end anastomosis of the proximal femoral artery with the distal femoral vein in the pelvic extremity of rat in an experimental study. The morphologic consequences of the arterio-venous anastomosis were investigated with reference to the normal skeletal muscle structure and the muscular recovery phase after acute ischemic damage. The light microscopic changes of the muscular morphology were served as indirect proof of the effect, because the skeletal muscles showed the slightest tolerance in face of ischemia of all tissues of an extremity. The arterio-venous anastomosis for prophylaxis of postischemic skeletal muscle damages appears unfit in this experiment similar to clinical conditions. The light microscopic investigations of the skeletal muscles demonstrated an involution of the pathohistologic changes in combination of acute ischemic loading and adjunctive arteriovenous anastomosis.

[The effect of arteriovenous fistulas on the metabolism and morphology of striated muscles]. / Der Einfluss arterio-venöser Fisteln auf Metabolismus und Morphologie quergestreifter Muskulatur.

The revascularization of ischemic extremities by retrograde arterial perfusion has been reported in clinical and experimental studies. The effect of retrograde perfusion on hemodynamics and metabolism of skeletal muscle was investigated in 86 rabbits with various types of AV-fistulas. Since blood flow was markedly reduced, levels of energy phosphates (ATP, CP) stabilized on a lower level. In all groups, lactate raised significantly. Focal morphological lesions were seen in all groups in a various degree. A high incidence of thrombosis was found at dissection. Maintenance of blood flow and metabolism after retrograde perfusion seems to be possible on a low level.

[Experimental studies of the effect of an arteriovenous fistula on postischemic skeletal muscle]. / Experimentelle Untersuchungen zum Einfluss einer arterio-venösen Fistel auf postischämische Skelettmuskulatur.

Arteriovenous fistulas have clinically been used for revascularization of ischemically damaged extremities. Therefore in an experimental study on hind legs of rats, the histomorphological changes on the M. tibialis anterior and the M. soleus following arteriovenous shunts in the femoral level with and without an ischemic lesion were performed. The results show that it is unlikely, to expect postischemic muscle protection by iatrogenic arteriovenous shunting.