The APC/C activator Cdh1 regulates the G2/M transition during differentiation of placental trophoblast stem cells

Differentiation of placental trophoblast stem (TS) cells to trophoblast giant (TG) cells is accompanied by transition from a mitotic cell cycle to an endocycle. Here, we report that Cdh1, a regulator of the anaphase-promoting complex/cyclosome (APC/C), negatively regulates mitotic entry upon the mitotic/endocycle transition. TS cells derived from homozygous Cdh1 gene-trapped (Cdh1^GT/GT) murine embryos accumulated mitotic cyclins and precociously entered mitosis after induction of TS cell differentiation, indicating that Cdh1 is required for the switch from mitosis to the endocycle. Furthermore, the Cdh1^GT/GT TS cells and placenta showed aberrant expression of placental differentiation markers. These data highlight an important role of Cdh1 in the G2/M transition during placental differentiation.     

The localization of calcium by X-ray microanalysis in myopathic muscle fibers

An electron histochemical study was undertaken to localize calcium with ammonium oxalate precipitation technique in soleus muscle of rat in normal cases and in myopathy induced experimentally by a prolonged treatment of 2,4-dichlorophenoxyacetate (2,4-D). The calcium content of precipitates was detected by energy-dispersive X-ray microanalysis. In normal cases, the electron dense precipitates containing calcium were mainly found in the vesicles of sarcoplasmic reticulum, whereas in 2,4-D induced myopathy the deposits were shifted near the Z line into the myofibrils. Calcium, because the uptake into sarcoplasmic vesicles was inhibited by 2,4-D, could attach to other binding sites, such as to the troponin-C.A long-lasting binding of calcium might lead to a prolonged activation of the actin-myosin system.     

POSTPARTUM PHLEBECTOMY

Saphenous vein ligation and stripping was performed on 27 patients in the immediate postpartum period without complications. Doing the operation at this time saves time and money. Technically it is easier to do postpartum than during pregnancy, and the patients have less postoperative discomfort than is usual with phlebectomy at other times.     

Distinct alpha-noradrenergic receptors differentiated by binding and physiological relationships.

Adult mice received two 70 μg doses of 6-hydroxydopamine intracisternally 72 hours apart, and the muscarinic binding properties of discrete brain regions were then investigated at various time intervals. Three days after the second injection, ³H-norepinephrine uptake was drastically reduced in all brain regions studied, and a distinct decrease in muscarinic receptor density was observed in the striatum (?18%), medulla-pons (?17%) and cerebellum (?15%) of lesioned animals as compared with controls. No changes were detected in muscarinic receptor density in the cortex or the hippocampus of treated animals, nor were any changes seen in the affinity of the labelled ligand for its receptor or in the displacement properties of the muscarinic binding by agonists in any of the regions studied. These effects still persisted after 60 days, with a further reduction in striatal muscarinic density to 74% of control values. Data are interpreted with respect to the proposed model for cholinergic modulation of central catecholamine release and cholinergic-catecholaminergic interactions in the striatum.