Release by phenobarbital of the repression of UDP-glucuronyltransferase activity in ovo

UDP-Glucuronyltransferase activity in chick-embryo liver and kidney, known to be induced by hatching or by culture, appears to be repressed in ovo. Injection of phenobarbital into the egg overcomes this repression. Chick-embryo liver and kidney cells can thus exhibit high transferase levels whilst still in ovo. Response to phenobarbital by liver tissue occurs in situ or when grafted on to the chorioallantoic membrane, and can be elicited by 96 hr of age. The ability of phenobarbital to over-ride the natural regulation of liver UDP-glucuronyltransferase development in ovo is contrasted with its inability in utero. Overall glucuronidation, as well as the transferase, is elicited by phenobarbital in ovo; differences between regulation of glucuronidating and hydroxylating enzymes are noted.     

(14C)Glucosamine incorporation into specific products in the nerve ending fraction in vivo and in vitro

The products ofin vivo andin vitro incorporation of radioactive glucosamine into glycoproteins associated with the nerve ending (synaptosome) fraction were studied by polyacrylamide gel electrophoresis and also by gel filtration of glycopeptides derived from these glycoproteins by pronase digestion.Afterin vivo labeling for 1 h a heterogeneous group of [¹⁴C]glucosamine labeled glycoproteins was found associated with the nerve ending fraction. The predominant [¹⁴C]glucosamine containing glycopeptide derived by pronase digestion of the nerve ending fraction had an apparent molecular weight of 1250. It constituted a larger percentage of the labeled glycopeptides associated with the nerve ending fraction, as compared with other subcellular fractions. After 4 h ofin vivo labeling other glycopeptides constituted a greater percentage of the total labeled glycopeptides derived from the nerve ending fraction. This suggests that a different group of [¹⁴C]glucosamine containing glycoproteins were now relatively abundant in nerve endings. Presumably they had arrived by axoplasmic transport to the nerve endings.Afterin vitro labeling the nerve ending fraction incorporated [¹⁴C]glucosamine more actively than the microsomal or mitochondrial fractions. The radioactive products found upon polyacrylamide gel electrophoresis of the nerve ending fraction appeared to be less heterogeneous than afterin vivo labeling. Upon pronase digestion a single class of labeled glycopeptides was found with the same apparent molecular weight as the predominant labeled glycopeptide in the nerve ending fraction afterin vivo labeling.The results indicate that some [¹⁴C]glucosamine is incorporated into specific products by components of the nerve ending fraction and that this glycosylation cannot readily be attributed to contamination with other particles containing glycosyl transferases. Other glucosamine containing products are apparently transported to the nerve endings after glycosylation in the nerve cell body.     

Characterizing the need for mechanical ventilation following cervical spinal cord injury with neurologic deficit

BACKGROUND: Patients who sustain cervical spinal cord injury (C-SCI) with neurologic deficit may require a definitive airway and/or prolonged mechanical ventilation. The purpose of this study was to characterize factors associated with a high risk for respiratory failure and/or the need for mechanical ventilation in C-SCI patients. METHODS: Patients with C-SCI and neurologic deficit admitted to a Level I Trauma Center between July 1, 2000 and June 30, 2002 were retrospectively reviewed for demographics, level and completeness of neurologic deficit, need for definitive airway, need for tracheostomy, need for mechanical ventilation at hospital discharge (MVDC), and outcomes. The level and completeness of injury were defined by American Spinal Injury Association standards. RESULTS: One hundred nineteen patients with C-SCI and neurologic deficit were identified over this period. Of these, 45 were identified as complete C-SCI: 12 (27%) patients had levels of C1 to C4; 19 (42%) had a level of C5; and 14 (31%) had levels of C6 and below. There were 37 males and 8 females. There were 36 blunt and 9 penetrating injuries. The average age of these patients was 40 +/- 21, and the average ISS was 45+/-22. Eight of the patients with complete C-SCI died, for a mortality of 18%. Of the 37 survivors, 92% received a definitive airway, 81% received tracheostomy, and 51% required MVDC. All patients with complete injuries at the C5 level and above required a definitive airway and tracheostomy, and 71% of survivors required MVDC. Of the patients with complete injuries of C6 and below, 79% received a definitive airway, 50% required tracheostomy, and 15% of survivors required MVDC. Only 35% of incomplete injuries required a definitive airway, and only 7% required tracheostomy. CONCLUSIONS: The need for definitive airway control, tracheostomy, and ventilator dependence is significant, especially for patients with high complete C-SCI. Based on these results we recommend consideration of early intubation and tracheostomy for patients with complete C-SCI, especially for those with levels of C5 and above.