A comparative study using 32P-labeling techniques on Schwann cell and skeletal muscle metabolism after repair of divided rat sciatic nerve by anastomosis with either microneurosurgical sutures or fibrinogen tissue adhesive shows no significant difference between the two repair modes. The successful measurement of functional muscle regeneration in the experimental study of nerve repair techniques is still hampered by the absence of definitive functional and physiologic criteria, despite an apparent normal anatomic restitution of the muscle.
Collection of human term placentae for research purposes is generally limited during working hours. Preserving placental tissue overnight might help to postpone experiments and, by extent, to increase material availability. In this study, fragments from normal placentae were incubated at 37 degrees C either immediately after delivery or after preservation at 4 degrees C in a HEPES-buffered solution or in a Roswell Park Memorial Institute (RPMI) 1640 culture medium. Protein, human chorionic gonadotrophin (HCG), human placental lactogen (HPL) and lactate dehydrogenase (LDH) contents within preserved explants were similar to those within freshly delivered ones. In contrast, HCG and HPL amounts released during incubation of preserved tissue were lower than with freshly delivered tissue. Differences were significant only during the first 3 h of incubation. Hormone releases were similarly Ca(2+)-stimulated, and Co(2+)- and low temperature-inhibited in preserved and freshly delivered tissues. After preservation, LDH leakage was also reduced. Furthermore, before and after 37 degrees C incubation during 6 h, preserved tissue was morphologically indistinguishable from freshly delivered tissue and showed neither higher incidence of DNA fragmentation, nor elevated caspase-3 activity, both of which are markers of apoptosis. This study validates an original, useful and rapid method to preserve placental tissue. Consequently, this preservation model may facilitate the study of physiological processes regulating placental hormone secretion in normal and pathological conditions.
Apoptosis in human placental villi is reported to increase until close to delivery. However, the involvement of the apoptotic process in the initiation of labor, and more particularly in relation to the decrease in placental perfusion during uterine contractions, remains unknown. The purpose of the study was to examine the reactivity of the apoptotic machinery in term placentae obtained before or after the onset of labor and after in vitro incubations. The incidence of apoptotic nuclei (< 1%) as evidenced by the terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) method, and the histological distribution of immunoreactive Bcl-2, Bax, and Bcl-x proteins, were similar in placentae collected after delivery and before the onset of labor and in placental explants maintained overnight at 4 degrees C in a minimal salt-Hepes medium. By contrast, 28% of nuclei contained fragmented DNA when placental explants were incubated overnight at 37 degrees C. This marked increase was associated with a decrease in the intensity of the Bcl-2 immunostaining and an increase in the intensity of Bax and Bcl-x immunostaining. In conclusion, the present study clearly evidences the presence of an active apoptotic machinery in term placental cells that is not involved in normal parturition.
Objectives-Structural impairment of the renal proximal tubular epithelium induced by cadmium (Cd) was investigated by measuring the concentration of neutral endopeptidase 24.11 (NEP), an ectoenzyme of the apical brush border, in the urine of 106 male workers employed in a Cd smelter (among whom 52 were occupationally exposed to Cd), and by comparing it with other tubular markers (low molecular weight proteins, lysosomal enzymes).Methods-NEP (EC 3.4.24.11), P-Nacetyl-glucosaminidase (NAG) (EC 3.2.1.
Peripheral nerve anastomoses using either epiperineurial sutures or a fibrinogen adhesive technique have been compared in the rat sciatic nerve model. Evaluation of results was made using radiolabelling of the metabolically active acid-soluble phosphate fractions of both nerve and muscle. In none of the situations tested--traumatic degeneration and regeneration in the sciatic nerve proximal segment, Wallerian degeneration and regeneration in its distal segment, atrophy and regeneration of the fast gastrocnemius muscle, and atrophy and regeneration of the slow soleus muscle--was one repair method significantly superior to the other. A significant degree of cross-reinnervation was shown to take place after anastomosis, altering the characteristics of the regenerating muscles. Both repair methods were equally inferior to the spontaneous repair occurring after a simple nerve crush.
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