[Avulsion of the inferior rectus muscle due to a dog-bite and reconstruction of its function]. / Durchtrennung des Musculus rectus inferior durch Hundebiss und Rekonstruktion der Muskelfunktion - eine Kasuistik.

BACKGROUND: Injuries of an extraocular muscle or of the globe due to a dog-bite are rare. PATIENT: An 43-year-old patient presented with an orbital dog bite. He had a complete avulsion of the inferior rectus muscle. During the primary surgical repair, the proximal part of the muscle could not be found. The distal part of the inferior rectus muscle was sutured to the tissue in the original region of the retracted inferior rectus muscle. After surgical repair the patient could read without complaint. We explain the unexpected remarkable postoperative result on the basis of high resolution MRI: Although the muscle belly was lost, some parts of the muscle sheath forming connections to Tenon's capsule had remained. These allowed a certain function of the muscle. CONCLUSIONS: If during the primary surgical repair of a traumatic avulsion of an extraocular muscle the proximal part of the muscle could not be found, it is worth to suture the distal part of the muscle to tissues (empty muscle sheath, connections to Tenon's capsule) in the original region of the lost muscle. This prevents a further retraction of the proximal part of the muscle and helps the finding and differentiation of the structures of the muscle during a prospectivly following surgical repair.

Protein-kinase-C iso-enzymes support DNA synthesis and cell survival in colorectal-tumor cells.

Protein-kinase-C signalling has been blocked in colorectal tumor cells by kinase inhibitors, by TPA down-regulation or by exposure to anti-sense oligonucleotides. This resulted in growth inhibition in all cell lines used. The kinase inhibitors H7 and calphostin induced apoptosis, demonstrated by the appearance of cells with characteristically condensed chromatin and the induction of stand-breaks in the DNA. A cell-death-inducing concentration of 15 microgram/ml H7 down-regulated the bcl-2 levels after 9 hr, while bak levels were not affected. Gö6976,-an inhibitor of Ca(++)-dependent PKC iso-enzymes, was not active in growth inhibition or induction of apoptosis. Analysis of DNA synthesis in inhibitor-treated cultures indicated that H7 caused strong inhibition in all cell lines, while the more specific inhibitor calphostin was effective only in VACO235 adenoma cells. When down-regulation by TPA or anti-sense oligonucleotides was used to block PKC, effects on cell numbers were smaller and delayed. However, induction of apoptosis was significantly increased in SW480 carcinoma cells 4 days after exposure to anti-epsilon and anti-zeta oligonucleotides in SW480 and T84 carcinoma cells. Apoptosis was preceeded by loss of PKC protein and of bcl-2 from day 1 after addition of the oligonucleotides. In VACO235 adenoma cells, no induction of apoptosis could be observed when anti-epsilon and anti-zeta oligonucleotides were used. On the other hand, the adenoma cells were more responsive to anti-alpha and anti-beta oligonucleotides, which strongly inhibited DNA-synthesis 3 days after addition to the culture medium. Our results indicate that the Ca(++)-dependent PKCs alpha and beta are involved in proliferation signals, while the Ca(++)-independent PKCs epsilon and zeta are involved in survival pathways of colorectal tumor cells.

Inhibition of epidermal-growth-factor-receptor-dependent signalling by tyrphostins A25 and AG1478 blocks growth and induces apoptosis in colorectal tumor cells in vitro.

Growth effects of tyrphostins A25 and AG1478 on colorectal tumor cells were studied to explore therapeutic potential. Cell number, DNA synthesis and apoptotic index were measured as growth parameters and cell-death-associated proteins Bcl-2 and Bak and protein phosphorylation were analyzed. Both tyrphostins inhibited DNA synthesis and induced apoptosis in tumor cell cultures with different patterns of activity. A25 displayed strong selectivity for the cell lines expressing high levels of epidermal growth factor (EGF), HT29/HI1 and SW480. Inhibition of DNA synthesis was efficient in all cells except T84, and the apoptotic index increased two- to fivefold. By contrast, AG1478 was highly effective in all cell lines. In addition, it caused cell loss in VACO235 adenoma cells at concentrations lower than those necessary to inhibit BrdU incorporation, reflecting preferential retention of cells actively synthesizing DNA. Induction of apoptosis was more efficient with AG1478 than with A25 (tenfold in VACO235). Insulin-like growth factor (IGF1) did not rescue cells exposed to A25 or to high concentrations of AG1478, but was effective with suboptimal amounts of AG1478. Both compounds inhibited phosphorylation of the EGF receptor as well as additional proteins. AG1478 induced expression of Bak and down-regulated Bcl-2. In summary, tyrphostins may provide alternatives for colorectal tumor treatment. Their broader range of activities and the lower susceptibility to interactions with IGF1 can be an advantage over receptor antibodies.

Apoptosis in human colorectal tumours: ultrastructure and quantitative studies on tissue localization and association with bak expression.

Apoptotic cell death in human tumours has been demonstrated by electron and light microscopy. In adenomas, fragmented and apoptotic nuclei and signs of phagocytosis have been observed close to the basement membrane. In carcinomas the characteristic structures were apoptotic bodies with small fragments of chromatin. DNA fragmentation was shown by in situ end-labelling. Quantitative assessment of apoptosis and proliferation revealed a high apoptotic index (AI) in all types of adenoma (tubular: 1.77+/-0.35%, tubulovillous: 2.38+/-0.41%; villous: 3.3+/-0.39%) as well as loss of compartmentalization of proliferating and dying cells. In carcinomas a shift towards proliferation was evident, as shown by lower AIs than in adenomas (0.9+/-0.68% and 1.1+/-0.12% for moderately and poorly differentiated tumours), higher Ki67 indices (38.32+/-2.23% and 57+/-3.89%, respectively) and higher mitosis (0.9+/-0.56% and 1.21+/-0.17%, respectively). However, apoptosis was observed in all tumours and is available as a target for therapeutic intervention. Expression of the apoptosis related proteins bcl-2 and bak also reflected loss of compartmentalization. While bcl-2 did not show a consistent relationship to AI in tumour specimens, bak was positively correlated with apoptosis in 4 of 8 adenomas and 4 of 7 carcinomas, suggesting a role for this protein in the induction of apoptosis in a subset of tumours.

In vitro studies on subtypes and regulation of active cell death.

Active cell death (ACD) comprises several subtypes as indicated by morphology at light- and electron-microscopical level: for example type I ACD or apoptosis, with nuclear condensation, fragmentation, cytoplasmic condensation; type II ACD, nuclear pyknosis, cytoplasmic autophagy. Morphologically different types of cell death are considered to reflect differences in the underlying biochemical and molecular events eventually leading to cell collapse. However, currently no simple biochemical or molecular marker for detection of ACD subtypes is available and, therefore, morphological methods are still required to classify ACD. Sometimes, distinction of ACD from necrosis may be equivocal. Type I ACD occurs in primary hepatocyte cultures treated with TGF-beta1 and in colonie adenoma cell cultures treated with the proteinkinase C inhibitor H7 (1[5-iso-quinolylsulfonyl]-2-methylpiperazine). The anti-survival activity of TGF-beta1 was confirmed in vivo as TGF-beta1 strongly induced apoptosis in normal tissue and in preneoplastic lesions of rat liver. Type II ACD was observed in human mammary carcinoma cells (MCF-7) after treatment with tamoxifen. The anti-survival activity of H7 and of the anti-oestrogens tamoxifen, 4-hydroxy-tamoxifen, ICI 164384 could be dissociated from their anti-proliferative action. In conclusion, cell culture studies provide a means to select compounds with high anti-survival activity for further exploration in preclinical and clinical testing.