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.     

Paraneoplastic and oncologic profiles of patients seropositive for type 1 antineuronal nuclear autoantibodies

The association of propofol with excitatory motor activity, such as myoclonic jerking and opisthotonus, in humans and in animals suggests that it may aggravate clinical seizure activity in some circumstances, although evidence suggests that under other circumstances, propofol inhibits seizure activity. In the current study, we assessed the effect of sedating doses of propofol on lidocaine-induced seizure activity in spontaneously breathing rats receiving no other anesthetics. Adult Sprague-Dawley male rats, 300-400 g, were divided into a control group and three experimental groups representing three graded levels of propofol sedation. The control rats then received a lidocaine infusion at the rate of 150 mg x kg(-1) x h(-1), resulting in a slow, progressive increase in systemic lidocaine concentrations. At the onset of electroencephalographic (EEG) seizure activity, arterial lidocaine concentrations were obtained. The treated rats received propofol according to three different dose schedules: Dose 1 = 10 mg x kg(-1) x h(-1) after a 2.5-mg/kg bolus; Dose 2 = 20 mg x kg(-1) x h(-1) after a 5-mg/kg bolus; Dose 3 = 40 mg x kg(-1) x h(-1) after a 10-mg/kg bolus. After 30 min, a steady level of sedation, dependent on the dose of propofol, was achieved. The lidocaine infusion was then started, and systemic lidocaine levels were obtained at the onset of EEG seizure activity. The lidocaine was continued until the onset of death by cardiac arrest. Plasma lidocaine was measured by gas chromatography. Analysis of variance and Dunnett's t-test were used for comparisons with the control values. Continuous propofol sedation increased the seizure dose of lidocaine from 37.7 +/- 3.5 mg/kg (mean +/- SEM) to 52.5 +/- 2.6 mg/kg (Dose 1, P < 0.05) and 67.9 +/- 8.6 mg/kg (Dose 2, P < 0.05), and completely abolished lidocaine seizures at Dose 3. The lethal dose of lidocaine, 89.4 +/- 10.5 mg/kg control versus 108.7 +/- 10.3 mg/kg (Dose 1), 98.3 +/- 10.1 mg/kg (Dose 2), and 93.5 +/- 10.4 mg/kg (Dose 3) did not differ among groups. The lidocaine levels at seizure threshold were increased in the propofol-treated rats: 16.9 +/- 0.5 microg/mL control versus 19.2 +/- 0.7 microg/mL (Dose 1, P = not significant) and 23.7 +/- 1.8 microg/mL (Dose 2, P < 0.05). Continuous propofol sedation in spontaneously breathing rats receiving no other anesthetics exerts a protective effect against lidocaine-induced seizures in a monotonic, dose-dependent fashion. The cardiac arrest dose of lidocaine is unaffected by propofol under these conditions. IMPLICATIONS: The i.v. anesthetic drug propofol, given to rats to produce sedation, was found to suppress seizure activity caused by overdosage of the local anesthetic lidocaine.     

Localization of neuroendocrine tumours with [111In] DTPA-octreotide scintigraphy (Octreoscan): a comparative study with CT and MR imaging

Hyperoxia has deleterious effects on lung form and function; however, the molecular events initiated by oxygen exposure remain unclear. We hypothesized that macrophages function as important intermediaries in the protective response of lung tissues after exposure to hyperoxia. This hypothesis was tested by exposing cultured macrophages (RAW 264.7 cells) to hyperoxia for 24 h and then applying the conditioned medium from these cells to cultured pulmonary epithelial cells or to pulmonary microvascular endothelial cells. We observed that the expression of manganese superoxide dismutase mRNA increased in both target cell lines. Therefore, we next hypothesized that exposure of these macrophages to hyperoxia results in a change in gene expression which could be detected by differential display PCR (ddPCR). This hypothesis was tested by exposing RAW 264.7 cells to > or = 95% oxygen (or normoxia) for 24 h, harvesting RNA, and performing ddPCR. A cDNA fragment upregulated by hyperoxia was identified and reamplified. Verification of differential expression of mRNA was done by Northern analysis. A mRNA which was reproducibly upregulated by hyperoxia, as well as by lipopolysaccharide and interferon gamma, was identified. The differentially expressed PCR product was cloned and sequenced, revealing a product with 99% identity to mouse urokinase mRNA. We speculate that one function of pulmonary macrophages following a hyperoxic exposure is to secrete urokinase.     

A preceptorship program in an Israeli bone marrow transplantation unit

Pheochromocytoma is a rare tumor which causes increased levels of circulating catecholamines. During pregnancy, this condition is life threatening to both mother and fetus. A case report of pheochromocytoma diagnosed in the third trimester is presented along with a review of the diagnosis and treatment of pheochromocytoma in pregnancy.