Mechanical plasticity of collagen directs branch elongation in human mammary gland organoids.

Epithelial branch elongation is a central developmental process during branching morphogenesis in diverse organs. This fundamental growth process into large arborized epithelial networks is accompanied by structural reorganization of the surrounding extracellular matrix (ECM), well beyond its mechanical linear response regime. Here, we report that epithelial ductal elongation within human mammary organoid branches relies on the non-linear and plastic mechanical response of the surrounding collagen. Specifically, we demonstrate that collective back-and-forth motion of cells within the branches generates tension that is strong enough to induce a plastic reorganization of the surrounding collagen network which results in the formation of mechanically stable collagen cages. Such matrix encasing in turn directs further tension generation, branch outgrowth and plastic deformation of the matrix. The identified mechanical tension equilibrium sets a framework to understand how mechanical cues can direct ductal branch elongation.

[A method for measuring the function of the organ of continence]. / Eine Methode zur Funktionsmessung des Kontinenzorgans.

For preoperative assessment of anal continence we developed a simple device to measure both anal sphincter function and sensitivity of the rectal ampulla. With this instrument anorectal function was studied in 19 males and 26 females without anorectal disorders. Anal resting tone and voluntary squeeze was higher in the males than in the females. Threshold of rectal sensation and critical volume, however, were higher in females. The new device appears to work precisely enough for accurate clinical evaluation. It is less time-consuming than electromanometric methods currently in use.

[Significance of the colon contrast enema in evaluating the importance of rectosigmoid polyps]. / Die Bedeutung des Kolon-Kontrasteinlaufes zur Dignitätsbeurteilung rektosigmoidaler Polypen.

The radiological appearance of mostly broad-based polyps in the rectosigmoid was studied in 35 patients. In all patients the diagnosis was histologically confirmed after surgical treatment. Conclusions on the histological tumour status could not be drawn either from surface structure, broadness of base and retraction of base, or from the base/height ratio. Stenosing growth, however, was seen relatively more often with carcinomas than with benign lesions. The discovery and identification of five carcinomas having a size of up to 2 cm illustrates the need for complete removal and histological processing of even seemingly negligible residues of polypous processes in the rectosigmoid.

[Transanal endoscopic microsurgery]. / Transanale endoskopische Mikrochirurgie.

A new endoscopic surgical method was developed for removal of large sessile adenomas of the rectum and lower sigmoid. Stereoscopic sight and magnifying glasses do allow precise surgery of these tumors. If adenomas are present they can be removed using the technique of mucosa excision; if on the other hand rectum carcinomas have to be removed the complete wall of the rectum in an appropriate extension can be excised. Hemorrhages which occur during preparation always can be stopped by diathermy. The surgical intervention is terminated by a transverse continuous suture of the defect. 33 patients were operated upon in this way from July 1983 to April 1985. Areas with an diameter of up to 10 cm could be removed, even located up to 18 cm in the colon. Suturing of the defect could always be performed without problem. In 1 patient a relapse occurred.

Endoscopic surgery in the rectum.

A new transanal endoscopic operative technique permits microsurgery in the rectal cavity and the placing of surgical sutures. Compared with other procedures this one is non-aggressive, and there were not postoperative complications in twelve cases. A stereoscopic optical system, a new operating rectoscope and special surgical instruments, as well as a modification to an insufflation device are necessary for the endoscopic operation.

The endoscopic multiple-diameter bougie--clinical results are after one year of application.

A new technique for dilation of the upper gastrointestinal tract permits complete endoscopic control of the whole procedure for the first time. 113 dilations have been carried out in 37 patients within a period of 15 months. The endoscopic guidance of the multiple diameter bougie positively excludes perforation resulting from the bougie's going the wrong way. With the steerable tip of the endoscope, kinking can be overcome and stenoses down to the duodenum can be dilated.

[Transanal endoscopic surgery of the rectum - testing a new method in animal experiments]. / Die transanale endoskopische Rektumoperation - Erprobung einer neuen Methode im Tierversuch.

Surgery of the lower third of the rectum can be done without difficulty through the anus using an endoscopical approach. Polyps or tumors located in the upper two thirds of the rectum can be removed using the Mason or Kraske procedure, or by the transabdominal approach. A new endoscopic technique has been developed with the aim, to allow surgery in the whole rectum through the anus. The rectum is being dilated by mechanical means and air insufflation. An oblique angle stereoscopic endoscope as well as modified surgical instruments are used. In animals 47 excisions of mucosa were done, and the incisions were closed by continuous suture. Application of this technique in a clinical setting is planned.

A multiple-diameter bougie fitted over a small-caliber fiberscope.

New instruments for dilatation of the upper gastrointestinal tract are described: 1. A hollow plastic bougie with an inside diameter of approximately 10 mm to allow a 9 mm endoscope to pass. The diameter of this tube-like bougie increases in four steps up to 16 mm. 2. A second-similar bougie employs a flexible bronchoscope for guidance of the bougie. This system permits bougienage from 4 to 11.5 mm. The system permits stepwise bougienage of stenoses using only two instruments. For the first time complete endoscopic control of bougienage is possible.

A form of rabbit liver cytochrome P-450 that catalyzes the 7 alpha-hydroxylation of cholesterol.

A form of cytochrome P-450 which comigrates with cytochrome P-450LM4 (molecular weight, 55 000) on SDS-polyacrylamide gel was purified from liver microsomes of cholestyramine-treated rabbits. This form of cytochrome P-450 catalyzed the 7 alpha-hydroxylation of cholesterol with an activity of 37.5 pmol/min per nmol cytochrome P-450 in the reconstituted enzyme system containing cytochrome P-450 and NADPH-cytochrome P-450 reductase. The substrate specificity of this form of cytochrome P-450 was compared with cytochrome P-450LM4 isolated from phenobarbital- and beta-naphthoflavone-treated rabbit liver microsomes. The latter two isoenzymes do not catalyze 7 alpha-hydroxylation of cholesterol, but are more active in O-deethylation of 7-ethoxycoumarin and p-nitrophenetole. Ouchterlony double diffusion revealed cross-reactivity between anti-P-450LM4 (phenobarbital) IgG and cytochrome P-450 isolated from cholestyramine- or beta-naphthoflavone-treated rabbit liver microsomes. A two-dimensional iodinated tryptic peptide fingerprint indicated only minor structural differences among these three cytochrome P-450LM4 preparations.

The identification of cytochrome P-450-LM2 synthesized in vitro from a rabbit liver polysomal mRNA template.

We demonstrate the in vitro synthesis of cytochrome P-450-LM2 (phenobarbital-inducible form of liver microsomal cytochrome P-450) from a rabbit liver polysomal mRNA template by specific immunoprecipitation of the product. The in vitro synthesized cytochrome P-450-LM2 comigrates with authentic cytochrome P-450-LM2 on sodium dodecyl sulphate-polyacrylamide gels, and is also selectively competed by authentic purified cytochrome P-450-LM2. In addition, we demonstrate that phenobarbital increases the amount of translatable mRNA for cytochrome P-450-LM2 but not for albumin, suggesting that phenobarbital has selective effects on the amount of available translatable mRNA or on mRNA biosynthesis.

Effects of cytochrome p-448 and p-450 inducers on microsomal dimethylnitrosamine demethylase activity and the capacity of isolated microsomes to activate dimethylnitrosamine to a mutagen.

The relationship between microsomal dimethylnitrosamine (DMN) demethylase activity and the capacity of isolated hepatic microsomes to activate DMN to a mutagen was examined using microsomes from C57 and DBA/2 mice which had been exposed to three different types of microsomal enzyme inducers: phenobarbital, which induces cytochrome P-450, 3-methylcholanthrene, which induces cytochrome P-448, and the polychlorinated biphenyl, Aroclor 1254 which appears to induce both types of cytochromes. DNM induced mutagenesis was assayed by a Salmonella auxotroph reversion test. With the C57 mice all three inducers increased both the activity of microsomal DMN demethylase and the capacity of the microsomes to activate DMN mutagenicity. In each case, however, the increase in mutagenicity was disproportionately greater than the increase in DMN demethylase activity. This was particularly evident with microsomes prepared from Aroclor induced mice. Microsomes from 3-methylcholanthrene treated DBA/2 mice were not induced for DMN demethylase or the activation of DMN mutagenicity. In addition the capacity of Aroclor to function as an inducer was relatively poor in this strain. Both DMN demethylation and mutagenesis were inhibited by the addition of either SKF 525-A or benzo (a)pyrene to the reaction mixtures. Thus microsomal activation of DMN to a mutagen and DMN demethylase appear to involve both cytochromes P-450 and P-448.

Cytochrome P-450 in the activation and inactivation of carcinogens.

The capacity of isolate mouse liver microsomes to alter the mutagenicity for bacteria of the primary carcinogen N-methyl-N'-nitro-N-nitrosoguanisine (MNNG) and the secondary one dimethylnitrosamine (DMN) was studied. Microsomal activation of DMN and inactivation of MNNG were decreased by protein- and protein-cholinedeficient diets and were increased by pretreatment with microsomal enzyme inducers. The decrease and increase paralleled the content of cytochrome P-450 present in the different microsomal preparations. With human liver microsomes of differing cytochrome P-450 contents similar correlation was obtained, whereas normal rat liver microsomes did not activate or inactivate DMN or MNNG. Oxidative demethylation of DMN by mouse liver microsomes and the activation of DMN to a mutagen followed similar kinetics. Both reactions were inhibited by carbon monoxide and the inhibition was maximally reversed by monochromatic light at 450 nm. These observations indicate that at least some carcinogens are activated or inactivated by the unspecific cytochrome P-450 dependent enzyme system, suggesting that the extent of this biotransformation may be one factor influencing human carcinogenesis.