Color Doppler echography in the study of pseudo-occlusion of the internal carotid

The differentiation of pseudo-occlusion from complete internal carotid artery occlusion may have important clinical consequences for patients with the former tend not to benefit from reconstructive surgery. The Authors report a case in which color-Doppler duplex-scanner revealed a persisting string-like lumen that was not demonstrated by angiography. The Authors believe that ultrasonography may in future permit the reliable differentiation of pseudo-from complete carotid occlusion, thereby reducing the need for angiography.     

Neurotoxicity of the drug Ecstasy. Functional consequences of serotonergic hypoactivity

Ingestion of the increasingly popular designer drug, ecstasy, results in an acute increase in the brain's monoamines: serotonin, dopamine, and noradrenaline. Animal research involving ecstasy has shown lasting damage to serotonergic axons and terminals, leading to reduced serotonin transmission in the CNS. Moreover, several studies suggest that the ingestion of ecstasy may be toxic to the human serotonin system. In animals repeated ecstasy administration has not shown persistent behavioural changes. In humans long lasting alterations in sleep pattern, mental state, personality, and cognition have been reported after repeated ecstasy use. However, these results have not been replicated, and most of them originate from uncontrolled studies of rather small populations.     

In vitro assessment of a collagen sponge for engineering urothelial grafts

OBJECTIVE: To investigate the deposition of urinary crystals and the growth characteristics of urothelial cells on a collagen sponge, as a preliminary step in engineering urothelial autologous grafts. MATERIALS AND METHODS: Collagen sponges were exposed to a continuous flow of urine at pH 5.3 and 6.3 for 1 week. The sponges were examined microscopically for crystal deposition and analysed for their calcium content. Two cell lines, RT112, derived from a well-differentiated transitional cell carcinoma, and UROtsa, an immortalized urothelial cell line, were seeded on the collagen sponges. Cells were cultured for 6, 12 and 21 days. The pattern of growth was analysed by histology and immunostaining with a pan-cytokeratin antibody. Growth was assayed to quantify cell proliferation on the sponges. RESULTS: No crystals were evident on any of the collagen sponges. Calcium deposition was negligible at pH 5.3. Although calcium levels were measurable at pH 6.3, the levels were very low. Both cell lines attached and grew in a stratified manner on the collagen sponge, RT112 forming a layer 6-8 cells thick, and UROtsa a layer 4-6 cells thick; cell proliferation was maximal at 5-10 days. The sponge remained easy to handle after 3 weeks in culture. CONCLUSION: These findings show that collagen sponges support the growth and stratification of urothelial cells, and indicate that the collagen sponge is a suitable substrate for developing urothelial autologous grafts.     

Compensatory neutral mutations and the evolution of RNA

There are many examples of RNA molecules in which the secondary structure has been strongly conserved during evolution, but the base sequence is much less conserved, e.g., transfer RNA, ribosomal RNA, and ribonuclease P. A model of compensatory neutral mutations is used here to describe the evolution of the base sequence in RNA helices. There are two loci (i.e., the two sides of the pair) with four alleles at each locus (corresponding to A, C, G, U). Watson-Crick base pairs (AU, CG, GC, and UA) are each assigned a fitness 1, whilst all other pairs are treated as mismatches and assigned fitness 1-s. A population of N diploid individuals is considered with a mutation rate of u per base. For biologically reasonable parameter values, the frequency of mismatches is always small but the frequency of the four matching pairs can vary over a wide range. Using a diffusion model, the stationary distribution for the frequency x of any of the four matching pairs is calculated. The shape depends on the combination of variables beta = 8Nu2/9s. For small beta, the distribution diverges at the two extremes, x = 0 and x = 1-z, where z is the mean frequency of mismatches. The population typically consists almost entirely of one of the four types of matching pairs, but occasionally makes shifts between the four possible states. The mean rate at which these shifts occur is calculated here. The effect of recombination between the two loci is to decrease the probability density at intermediate x, and to increase the weight at the extremes. The rate of transition between the four states is slowed by recombination (as originally shown by Kimura in a two-allele model with irreversible mutation). A very small recombination rate r approximately u2/s is sufficient to increase the mean time between transitions dramatically. In addition to its application to RNA, this model is also relevant to the 'shifting balance' theory describing the drift of populations between alternative equilibria separated by low fitness valleys. Equilibrium values for the frequencies of the different allele combinations in an infinite population are also calculated. It is shown that for low recombination rates the equilibrium is symmetric, but there is a critical recombination rate above which alternative asymmetric equilibria become stable.     

Experimental infection of pigs with the newly identified swine hepatitis E virus (swine HEV), but not with human strains of HEV

A novel virus of pigs, swine hepatitis E virus (swine HEV), was recently identified and shown to be antigenically and genetically related to human HEV. In the present study, we attempted to infect specific-pathogen-free (SPF) pigs experimentally with swine HEV or with human strains of HEV. Serum samples collected from naturally infected pigs were used as the source of swine HEV. Pigs inoculated intravenously with serum samples containing swine HEV seroconverted to anti-HEV 4 to 8 weeks postinoculation, and the virus spread to an uninoculated pig. Swine HEV was detected in nasal and rectal swab materials as early as 2 weeks postinoculation and for 4 to 8 weeks thereafter. Viremia appeared 4 to 6 weeks postinoculation and lasted 1 to 3 weeks. The inoculated pigs appeared clinically normal and serum liver enzymes were not significantly elevated. In contrast, pigs were not infected when inoculated intravenously with about 10(5) monkey infectious doses of one of two human strains of HEV (Sar-55 or Mex-14).     

Effects of exogenous recombinant ovine interferon tau on circulating concentrations of progesterone, cortisol, luteinizing hormone, and antiviral activity; interestrous interval; rectal temperature; and uterine response to oxytocin in cyclic ewes

Interferon tau (IFN tau) is the conceptus-produced antiluteolytic signal in ruminants. Three experiments examined the effects of s.c. administration of recombinant ovine (ro)IFN tau on interestrous interval (IEI), oxytocin (OT)-induced uterine prostaglandin F2alpha metabolite (PGFM) production, rectal temperature (RT), respiration rate (RR), and plasma concentrations of progesterone, cortisol, LH, and antiviral activity (AVA) in plasma and uterine flushings. In experiment I, 20 ewes were treated s.c. with either 0, 1, 2, or 4 mg/day roIFN tau (0.7 x 10(8) U/mg; 5 ewes/dosage) from Days 11 to 15 of the estrous cycle (estrus = Day 0) and were challenged with OT (30 IU) on Day 15. Jugular blood samples were collected at -10, 0, 10, 20, 30, 40, 50, and 60 min relative to the OT challenge and assayed for PGFM. Recombinant oIFN tau increased IEI (16.7, 18.7, and 22.6 +/- 0.6 days for 0, 2, and 4 mg roIFN tau, respectively, p < 0.01). Recombinant oIFN tau did not affect peak PGFM response to OT (2309 +/- 172 pg/ml; p > 0.1). However, the 4 mg/day dosage delayed the time to peak PGFM (32.4 vs. 47.5 +/- 3.4 min; p < 0.01, 0 vs. 4 mg) and resulted in approximately 200% higher concentrations of PGFM at 60 min post-OT (0 vs. 4 mg/day, p < 0.07). Experiment II was similar to experiment I, except that only the 0- and 4-mg/day dosages of roIFN tau were administered. Ewes were hysterectomized on Day 16, and assay of uterine flushes detected no AVA from ewes treated with either 0 or 4 mg/day roIFN tau. In experiment III, 20 ewes were treated s.c. with either 0, 2, 4, or 6 mg roIFN tau on Day 12. Blood samples, RT, and RR were obtained at frequent intervals for 24 h, and plasma was assayed for progesterone, cortisol, LH, and AVA. Plasma AVA, which increased in a dose-dependent manner, was detectable within 60 min and remained elevated at 24 h compared to control values. RT (elevated 0.5-1.0 degrees C), RR, and cortisol increased in response to all dosages of roIFN tau, with peak values occurring 150-180 min postinjection. For all dosages of roIFN tau, plasma progesterone declined from 120 to 360 min posttreatment and then returned to pretreatment values by 24 h (p < 0.01) as compared to controls. Overall, exogenous roIFN tau altered uterine PGFM response to OT from a pulse to a gradual and sustained elevation and extended IEI with only a transient decline in progesterone and mild hyperthermia, effects that are not expected to compromise pregnancy.