PubMed · 5463294
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M Pestel. 1970-05-09. [Genetic advice].. https://pubmed.ncbi.nlm.nih.gov/5463294/
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In fetuses with lower obstructive uropathy, sonography cannot establish the cause of obstruction. We assessed whether percutaneous fetal cystoscopy could be useful in the evaluation and treatment of obstructive defects in utero. We inserted a fibreoptic endoscope through the lumen of the needle or trocar into the fetal bladder at the time of vesicocentesis or vesicoamniotic-shunt placement and looked at the the urethra, bladder neck, and ureteral orifices. Urethral vesicoamniotic shunting was considered in suitable cases; otherwise a percutaneous shunt was inserted. Fetal cystoscopy was possible in 11 of 13 patients referred. The bladder mucosa appeared haemorrhagic or oedematous in three. The ureteral orifices were seen in 9/11 fetuses, dilation was seen in five, but was only suspected in two by ultrasound. Ureteral webs were noted in two other fetuses. Two of seven fetuses underwent urethral vesicoamniotic shunting; urethral patency was achieved with urethral probing alone in one fetus. The remaining four fetuses were shunted with a standard technique. Fetal cystoscopy helps define the underlying conditions responsible for sonographic findings of lower obstructive uropathy, and allows the introduction of new treatments.
Epidermal growth factor (EGF) is a 53-amino-acid mitogenic polypeptide present in a variety of tissues and fluids including kidney, urine, and amniotic fluid. An EGF isoform, des-Arg53-EGF, has been identified in urine and is the earliest metabolite generated in target cells upon EGF binding. In this study, purified carboxypeptidase M efficiently released the COOH-terminal arginine residue from EGF with a Km = 56 microM, kcat = 388 min-1, and kcat/Km = 6.9 microM-1 min-1. When EGF was incubated with urine or amniotic fluid, des-Arg53-EGF was the only metabolite detected. This conversion was blocked by immunoprecipitation with specific antiserum to carboxypeptidase M or by 10 microM DL-2-mercaptomethyl-3-guanidinoethylthiopropanoic acid (a carboxypeptidase M inhibitor), indicating that the major EGF metabolizing enzyme in these fluids is carboxypeptidase M. When incubated on a confluent monolayer of Madin-Darby canine kidney (MDCK) cells, EGF was readily converted to a single metabolite, des-Arg53-EGF, by carboxypeptidase M. To investigate one possible functional consequence of this conversion, mitogenic activities of EGF and des-Arg53-EGF were tested. Both peptides were equipotent in stimulating [3H]thymidine incorporation in MDCK cells at all doses tested. In addition, inhibition of the conversion of EGF to des-Arg53-EGF by the carboxypeptidase M inhibitor did not affect the mitogenic potency of EGF. These data indicate that carboxypeptidase M, present in a variety of cells and biological fluids, can convert EGF to des-Arg53-EGF. However, in contrast to many other peptide hormones whose activity depends on a final carboxypeptidase processing step, removal of Arg53 of EGF is not required for its mitogenic activity.
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