Epstein-Barr virus-associated leiomyosarcomas in liver transplantation recipients. Origin from either donor or recipient tissue

BACKGROUND: Leiomyosarcoma, a mesenchymal malignancy with smooth muscle differentiation, is extremely rare in children. Immunosuppression, due to either antirejection medication in organ transplantation recipients or human immunodeficiency virus infection (HIV), appears to constitute a predisposition. METHODS: Two cases of leiomyosarcoma in pediatric liver transplantation recipients were investigated and compared clinically with respect to site of origin and course of the disease and pathologically by routine histology and electron microscopy, by forensic DNA methodology for origin from donor or recipient tissue, and by EBER-1 in situ hybridization for evidence of latent Epstein-Barr virus (EBV) infection. RESULTS: A 9-year-old male developed a high grade, poorly differentiated leiomyosarcoma in his allografted liver 2 years after transplantation, and despite antineoplastic chemotherapy, he died of metastatic disease. The genotype of his tumor indicated an origin from allografted tissue. A 12-year-old female had a low grade retroperitoneal leiomyosarcoma involving the superior mesenteric vein. After resection, she remained disease free without chemotherapy. The genotype of her tumor indicated an origin from native tissue. In both tumors, latent EBV infection was documented. CONCLUSIONS: Neoplastic smooth muscle proliferation in immunosuppressed liver transplantation recipients is analogous to the more common posttransplantation lymphoproliferative disorder in involving transformation of either engrafted donor tissue or recipient tissue elsewhere in the body, in displaying a wide spectrum of histologic differentiation, grade and clinical behavior, and in exhibiting evidence of latent EBV infection.     

Serum amyloid A protein in humans and four animal species: a comparison by two dimensional electrophoresis

Two-dimensional electrophoresis and N-terminal analysis were used to study serum amyloid A protein (SAA) from humans, mink, fox, goat and rabbit. Previously uncharacterized SAA variants were demonstrated in fox, goat and rabbit, and considerable interspecies homology was seen. In rabbit, two novel SAAs were characterized, and SAA1 and SAA2 were demonstrated in mink and rabbit sera. The results confirm previous cDNA studies and indicate that SAA do possess an important function also in fox and goat.     

Molecular motion and order in single-bilayer vesicles and multilamellar dispersions of egg lecithin and lecithin-cholesterol mixtures. A deuterium nuclear magnetic resonance study of specifically labeled lipids

Deuterium (2H) nuclear magnetic resonance (NMR) quadrupole splittings and relaxation times have been measured for a variety of specifically deuterated lipids intercalated in lamellar-multibilayer dispersions and single-bilayer vesicles of egg lecithin and lecithin-cholesterol mixtures. The deduced order parameters and relaxation times vary with position of deuteration, acyl chain length, unsaturation, and temperature. The order parameters and spinlattice relaxation times T1 indicate rapid intramolecular motions of restricted amplitude in both the choline head group and hydrocarbon chains. The ordering profile for the acyl chains is similar to that predicted by statistical-mechanical theory. The order parameters yield estimates of the bilayer thickness and linear coefficient of expansion in close agreement with the x-ray determinations. A comparison of the deuterium and electron spin resonance spinprobe order parameters demonstrates the perturbation of the bilayer by the bulky nitroxide probe. The transverse relaxation time T2 for single-bilayer vesicles is quantitatively accounted for by a simple modification of classical relaxation theory which takes into account the modulation of the static quadrupole interaction by rapid local molecular motions and the modulation of the residual quadrupole interaction by the slower overall tumbling of the vesicle. It is unambiguously demonstrated that molecular motion and order in single-bilayer vesicles are very similar to those in lamellar multibilayers. Significant differences occur only for a few segments near the terminal methyl groups of the acyl chains, where the order parameters for vesicles are 10-30% smaller than those found for lamellae. The incorporation of cholesterol in lecithin bilayers is shown to increase the degree of orientational order in vesicles and lamellae, and to increase the hydrodynamic radius of vesicles. Thus, single-bilayer vesicles and multilamellar dispersions of phospholipids are equally useful models for biological membranes. They yield equivalent information about the internal organization and mobility of lipid bilayers, when the spectral manifestations of overall vesicle motion are correctly taken into account.     

Two components of transmitter release at a central synapse

After the arrival of a presynaptic nerve impulse at an excitatory synapse in hippocampal neurons, the rate of neurotransmitter release increases rapidly and then returns to low levels with a biphasic decay. The two kinetically distinct components are differentially affected when Sr2+ is substituted for Ca2+ ions. Our findings are comparable to those of the classical studies for the frog neuromuscular junction, and thus the basic aspects of Ca(2+)-activated transmitter release machinery appear to be conserved in central synapses. The method we have used, in addition, permits us to estimate the average neurotransmitter release rate for a single bouton. The observation of differential Ca2+/Sr2+ sensitivity is consistent with a release mechanism mediated by two Ca2+ sensors with distinct Ca2+ affinities: the low-affinity Ca2+ sensor facilitates the fast synchronous phase of release, whereas the high-affinity sensor sustains the slow asynchronous phase of release.