Homologous crossovers among molecules of brome mosaic bromovirus RNA1 or RNA2 segments in vivo

Previously we demonstrated frequent homologous crossovers among molecules of the RNA3 segment in the tripartite brome mosaic bromovirus (BMV) RNA genome (A. Bruyere, M. Wantroba, S. Flasinski, A. Dzianott, and J. J. Bujarski, J. Virol. 74:4214-4219, 2000). To further our knowledge about mechanisms of viral RNA genome variability, in this paper we have studied homologous recombination in BMV RNA1 and RNA2 components during infection. We have found that basal RNA-RNA crossovers could occur within coding regions of both RNAs, although recombination frequencies slightly varied at different RNA sections. In all cases, the frequencies were much lower than the rate observed for the intercistronic recombination hot spot in BMV RNA3. Probability calculations accounted for at least one homologous crossover per RNA molecule per replication cycle. In addition, we have demonstrated an efficient repair of mutations within the conserved 3' and 5' noncoding regions, most likely due to error-prone BMV RNA replication. Overall, our data verify that homologous crossovers are common events a during virus life cycle, and we discuss their importance for viral RNA genetics.

Tubular and Glomerular Proteinuria in Diagnosing Chronic Allograft Nephropathy With Relevance to the Degree of Urinary Albumin Excretion

The diagnosis of chronic allograft nephropathy (CAN) is based on pathological examination according to Banff 97 schema. The aim of the study was to evaluate the usefulness of tubular and glomerular proteinuria for noninvasive recognition of CAN. One hundred and thirty renal allograft recipients (at least 90 days after transplantation) who had undergone diagnostic allograft biopsy were included in the study. Beta2-microglobulin, alpha1-microglobulin, albumin, immunoglobulin G, total protein, and creatinine concentrations were obtained from the second morning urine specimen. Raw data and values calculated per 1 g of creatinine excreted in urine along with time after transplantation, serum creatinine, and its change over a period of 2 months prior to biopsy were taken for analysis. Urine proteins were measured using a nephelometric method. Statistical calculations were performed using MANOVA and stepwise discriminant analysis (SDA). Statistical diagnosis and staging of CAN matched the pathological method in 68% of a preliminary SDA. Therefore patients were divided into normoalbuminuric, microalbuminuric, and macroalbuminuric groups. There was no significant differences between protein excretion, except alpha1-microglobulinuria (CAN 0 vs 2, P = .018; CAN 1 vs 2, P = .041), beta2-microglobulinuria (CAN 0 vs 2, P = .026; CAN 1 vs 2, P = .0033), and total proteinuria (CAN 0 vs 2, P = .042) in the normoalbuminuric group. Nevertheless, diagnoses obtained using SDA were 89%, 91%, and 92% identical to the results of pathological examinations, for normoalbuminuric, microalbuminuric, and macroalbuminuric groups, respectively. In conclusion, tubular and glomerular proteinuria measurements may be useful for a noninvasive CAN diagnosis and staging only with regard to degree of urinary albumin excretion.

Two types of non-homologous RNA recombination in brome mosaic virus

Non-homologous RNA recombination is a process enabling the exchange of genetic material between various (related or unrelated) RNA-based viruses. Despite extensive investigations its molecular mechanism remains unclear. Studies on genetic recombination in brome mosaic virus (BMV) have shown that local hybridization between genomic RNAs induces frequent non-homologous crossovers. A detailed analysis of recombinant structures suggested that local complementary regions might be involved in two types of non-homologous recombination in BMV: site-specific and heteroduplex-mediated. To verify the above hypothesis and better recognize the mechanism of the phenomenon studied we have tested how the putative types of recombination are affected by a specific mutation in the BMV polymerase gene or by changes in RNA structure. The experiments undertaken revealed substantial differences between site-specific and heteroduplex-mediated recombination, indicating that they occur according to different mechanisms. The former can be classified as homology-assisted, and the latter as homology-independent. In addition to local RNA/RNA hybridization, short regions of homology are required for site-specific crossovers to occur. They are most efficiently mediated if one homologous sequence is located at the beginning of and the second just before a double-stranded region. At present it is difficult to state what is the mechanism of heteroduplex-mediated recombination. Earlier it was postulated that strong RNA/RNA interaction enforces template switching by the viral replicase. There are, however, several observations questioning this model and indicating that some other factors, which are still unknown, may influence heteroduplex-mediated crossovers.

Assessment of some porcine strains as donors of islets of langerhans

Mass isolation of viable porcine islets is a difficult task because of their fragility, and because of donor variability with respect to strain, age, sex, feeding, and methods of slaughtering. Not all strains are equally suitable for islet separation. The aim of this study was to evaluate porcine pancreata as an alternative source of islets for clinical transplantation. Pancreata were digested from pig strains available in Poland: 248 market weight slaughterhouse pigs and 42 pigs, belonging to the Polish Large White (WBP, 14 sows and 3 males), Polish White Pendant-Ears (PBZ; 16 sows), Pietrain (8 sows), and Yorkshire (1 sow) races. Prepurification data of recoverable islets/g and islet equivalents/g were considered as representative for the number of recoverable islets. Acceptable results namely, islet and/or islet-equivalent (IE) number of at least 1000/g, were obtained from only 56 of 248 slaughterhouse pigs, namely 2073 +/- 137.4 SE (median 1767/g) islets with values of IE of 2994 +/- 303 SE (median 1874/g). Our data support Krickhahn et al suggesting that only pancreata with an average islet size exceeding 199 microm should be digested and that only from 1 of 3 to 5 porcine pancreata is an adequate amount of islets generated.

Distribution of compound potentials recorded from the surface of isolated stellate ganglia following stimulation of postganglionic branches, in rats and cats

The experiments were performed on 9 cat and 18 rat isolated stellate ganglia. Rats and cats were anesthetized with alpha-glucochloralose or urethane, respectively. The ganglia, isolated with their branches, were transferred to a recording chamber and constantly superfused with artificial extracellular fluid bubbled with 95% O2 and 5% CO2. Branches of the ganglion were one by one placed in suction electrodes and stimulated. Antidromic evoked potentials were systematically recorded from numerous points on the ganglion surface. The area under the curve of the negative wave of each recorded potential was considered proportional to the number of neurons located in the vicinity of the recording electrode, projecting to the stimulated nerve. We have found that: (1) cardiac sympathetic neurons are located in the lower, caudal half of the ganglia; (2) vertebral sympathetic neurons occupy the cranial, upper half of the ganglia; (3) neurons with axons in the ansae are positioned near the point of exit of the respective ansa from the ganglion; (4) localization of neurons projecting to the same branches is very similar on both sides--right and left; (5) this localization is also similar in rats compared to cats.

Antagonistic effect of MR2266 and MR2267 on morphine or nalbuphine analgesia at the spinal levels in rats

The aim of this paper was to study the effect of two benzomorphan derivatives MR2266 and MR2267 with predominant antagonism to kappa-opioid receptors administered intrathecally on the analgesic action of morphine and nalbuphine. Both compounds attenuated the analgesia elicited by examined opioid agonists. Our results support the hypothesis that the spinal opioid receptors take part in analgesic effect of morphine and nalbuphine. It was for the first time described that MR2267, considered as inactive enantiomer of MR2266, is an active opioid antagonist when administered intrathecally.