Porous polyethylene implants in orbital floor reconstruction

The purpose of this article is to present the authors' experience with the use of porous polyethylene ultrathin sheets for orbital floor reconstruction. Thirty-two patients with orbital floor fractures were treated with porous polyethylene ultrathin sheets. Sixteen cases corresponded to orbitozygomatic fractures, 11 cases corresponded to pure orbital floor fractures, and five corresponded to panfacial fractures. The subciliary approach was used in 15 patients and the transconjunctival approach in nine; another three patients were operated on through a preexisting eyebrow wound, two were operated on with a subtarsal approach, two were operated on through an eyebrow extension of a facial wound, and one patient was operated on through the facial wound. Intraoperatively, all patients received a prophylactic dose of intravenous antibiotics. Postoperatively, 24 patients received amoxicillin clavulanate for 5 to 7 days, two patients received clindamycin, and six patients received no antibiotics. Enophthalmos was corrected in 15 of 24 patients (62.5 percent), and hypoglobus in nine of 11 (82 percent). Diplopia was resolved in 25 of 28 patients (89.3 percent) with preoperative impairment. Extrinsic eye movement impairment was resolved in 25 of 27 patients (92.6 percent). A preoperative visual acuity deficit was present in four patients (12.5 percent) and was resolved in one (from 20/100 to 20/20). Visual acuity improved in one patient (from 20/60 to 20/30). In the other two patients, visual acuity remained altered (from 20/30 to 20/30). One patient (3.1 percent) suffered blindness induced by surgery. Nine of 26 patients (34.6 percent) had residual infraorbital nerve hypesthesia and five (19.2 percent) had residual paresthesias. Postoperatively, epiphora was present in six patients (18.8 percent) and ectropion in five (15.6 percent). Although there was no statistical significance between the surgical approach and the presence of epiphora (p = 0.211) and ectropion (p = 0.422), patients who were treated using the transconjunctival approach suffered reduced ectropion (0 percent) compared with patients treated using the subciliary approach (20 percent). However, patients treated using the transconjunctival approach suffered increased epiphora (22.2 percent) compared with those treated with the subciliary approach (13.3 percent). There were four cases (12.5 percent) of postoperative facial infections. Two of these cases were resolved with systemic antibiotics, one was resolved with bone sequestrum resection, and one patient needed removal of the implant. Orbital infections were related in all cases to titanium osteosynthesis miniplates or skull bone graft. When comparing patients who were treated with and without antibiotics, no statistical differences (p = 0.958) were found relative to the presence of infections. Correction of hypoglobus is technically easier than enophthalmos, because enophthalmic correction requires a wide, deep subperiosteal dissection and implant positioning, posterior to the equator of the globe, with the inherent risk of orbital apex injury.     

Cytosolic N-terminal arginine-based signals together with a luminal signal target a type II membrane protein to the plant ER

Background  

In eukaryotic cells, the membrane compartments that constitute the exocytic pathway are traversed by a constant flow of lipids and proteins. This is particularly true for the endoplasmic reticulum (ER), the main "gateway of the secretory pathway", where biosynthesis of sterols, lipids, membrane-bound and soluble proteins, and glycoproteins occurs. Maintenance of the resident proteins in this compartment implies they have to be distinguished from the secretory cargo. To this end, they must possess specific ER localization determinants to prevent their exit from the ER, and/or to interact with receptors responsible for their retrieval from the Golgi apparatus. Very few information is available about the signal(s) involved in the retention of membrane type II protein in the ER but it is generally accepted that sorting of ER type II cargo membrane proteins depends on motifs mainly located in their cytosolic tails.     

Radical trapping properties of imidazolyl nitrones

The ability of ten imidazolyl nitrones to directly scavenge free radicals (R(*)) generated in polar ((*)OH, O(*)(2)(-), SO(*)(3)(-) cysteinyl, (*)CH(3)) or in apolar (CH(3)-(*)CH-CH(3)) media has been studied. When oxygen or sulfur-centered radicals are generated in polar media, EPR spectra are not or weakly observed with simple spectral features. Strong line intensities and more complicated spectra are observed with the isopropyl radical generated in an apolar medium. Intermediate results are obtained with (*)CH(3) generated in a polar medium. EPR demonstrates the ability of these nitrones to trap radicals to the nitrone C(alpha) atom (alpha radical adduct) and to the imidazol C(5) atom (5-radical adduct). Beside the nucleophilic addition of the radical to the C(alpha) atom, the EPR studies suggest a two-step mechanism for the overall reaction of R(*) attacking the imidazol core. The two steps seem to occur very fast with the (*)OH radical obtained in a polar medium and slower with the isopropyl radical prepared in benzene. In conclusion, imidazolyl nitrones present a high capacity to trap and stabilize carbon-centered radicals.     

Effect of prolonged treatment with tyramine on glucose tolerance in streptozotocin-induced diabetic rats

The biogenic amine tyramine has been reported to stimulate in vitro glucose transport in adipocytes, cardiomyocytes and skeletal muscle, and to improve in vivo glucose utilization in rats. These effects were dependent on amine oxidation, since they were blocked by inhibitors of monoamine oxidase (MAO) and semicarbazide-sensitive amine oxidase (SSAO). We thus tested in this work whether a prolonged treatment with tyramine could improve glucose tolerance in streptozotocin-induced diabetic rats. First, tyramine content of standard rodent chow was determined by HPLC and daily tyramine intake of control rats was estimated to be around 26 micromol/kg body weight. Then, tyramine was administred during 3 weeks in streptozotocin-induced diabetic rats at 29 micromol/kg by daily i.p. injection alone or together with vanadate 0.02 micromol/kg. In another group of diabetic rats, tyramine was subcutaneously delivered at 116 micromol/kg/day by osmotic minipumps. All tyramine treatments resulted in a decrease of the hyperglycemic responses to an i.p. glucose load. Adipocytes isolated from either untreated or treated diabetic rats were sensitive to the stimulation of glucose uptake by tyramine. However, diabetic animals receiving tyramine for three weeks did not recover from their hyperglycemia, hypoinsulinemia and glucosuria. These results show that the improvement of glucose tolerance induced by prolonged tyramine administration occurs in an insulin-depleted model and probably results from peripheral insulin-like actions of the oxidation of MAO/SSAO substrates, such as the stimulation of glucose uptake into adipocytes.     

Length and Sequence Variability in Mitochondrial Control Region of the Milkfish, <Emphasis Type="BoldItalic">Chanos chanos</Emphasis>

Extensive length variability was observed in the mitochondrial control region of the milkfish, Chanos chanos. The nucleotide sequence of the control region and flanking regions was determined. Length variability and heteroplasmy was due to the presence of varying numbers of a 41-bp tandemly repeated sequence and a 48-bp insertion/deletion (indel). The structure and organization of the milkfish control region is similar to that of other teleost fish and vertebrates. However, extensive variation in the copy number of tandem repeats (4–20 copies) and the presence of a relatively large (48-bp) indel, are apparently uncommon in teleost fish control region sequences reported to date. High sequence variability of control region peripheral domains indicates the potential utility of selected regions as markers for population-level studies. Received March 14, 2001; accepted June 29, 2001     

Glycosylation of Eag1 (Kv10.1) potassium channels: intracellular trafficking and functional consequences

N-Linked glycosylation is a common post-translational modification of membrane proteins. Here we report that mature Eag1 potassium channels carry sugar moieties linked to asparagines at positions 388 and 406. Asn-388 seems to undergo only core glycosylation, but complex sugars are bound to Asn-406. Correct complex glycosylation is required for proper trafficking of Eag1 to the plasma membrane but is also crucial for the correct function of channels already inserted in the membrane.     

International study to evaluate PCR methods for detection of Trypanosoma cruzi DNA in blood samples from Chagas disease patients

Background

A century after its discovery, Chagas disease still represents a major neglected tropical threat. Accurate diagnostics tools as well as surrogate markers of parasitological response to treatment are research priorities in the field. The purpose of this study was to evaluate the performance of PCR methods in detection of Trypanosoma cruzi DNA by an external quality evaluation.

Methodology/Findings

An international collaborative study was launched by expert PCR laboratories from 16 countries. Currently used strategies were challenged against serial dilutions of purified DNA from stocks representing T. cruzi discrete typing units (DTU) I, IV and VI (set A), human blood spiked with parasite cells (set B) and Guanidine Hidrochloride-EDTA blood samples from 32 seropositive and 10 seronegative patients from Southern Cone countries (set C). Forty eight PCR tests were reported for set A and 44 for sets B and C; 28 targeted minicircle DNA (kDNA), 13 satellite DNA (Sat-DNA) and the remainder low copy number sequences. In set A, commercial master mixes and Sat-DNA Real Time PCR showed better specificity, but kDNA-PCR was more sensitive to detect DTU I DNA. In set B, commercial DNA extraction kits presented better specificity than solvent extraction protocols. Sat-DNA PCR tests had higher specificity, with sensitivities of 0.05–0.5 parasites/mL whereas specific kDNA tests detected 5.10⁻³ par/mL. Sixteen specific and coherent methods had a Good Performance in both sets A and B (10 fg/µl of DNA from all stocks, 5 par/mL spiked blood). The median values of sensitivities, specificities and accuracies obtained in testing the Set C samples with the 16 tests determined to be good performing by analyzing Sets A and B samples varied considerably. Out of them, four methods depicted the best performing parameters in all three sets of samples, detecting at least 10 fg/µl for each DNA stock, 0.5 par/mL and a sensitivity between 83.3–94.4%, specificity of 85–95%, accuracy of 86.8–89.5% and kappa index of 0.7–0.8 compared to consensus PCR reports of the 16 good performing tests and 63–69%, 100%, 71.4–76.2% and 0.4–0.5, respectively compared to serodiagnosis. Method LbD2 used solvent extraction followed by Sybr-Green based Real time PCR targeted to Sat-DNA; method LbD3 used solvent DNA extraction followed by conventional PCR targeted to Sat-DNA. The third method (LbF1) used glass fiber column based DNA extraction followed by TaqMan Real Time PCR targeted to Sat-DNA (cruzi 1/cruzi 2 and cruzi 3 TaqMan probe) and the fourth method (LbQ) used solvent DNA extraction followed by conventional hot-start PCR targeted to kDNA (primer pairs 121/122). These four methods were further evaluated at the coordinating laboratory in a subset of human blood samples, confirming the performance obtained by the participating laboratories.

Conclusion/Significance

This study represents a first crucial step towards international validation of PCR procedures for detection of T. cruzi in human blood samples.     

Sequence analysis of the internal transcribed spacer 2 (ITS2) from Philornis seguyi (García, 1952) and Philornis torquans (Nielsen, 1913) (Diptera: Muscidae)

Philornis Meinert, 1890 (Diptera: Muscidae) is a genus of Neotropical dipterans that parasitise birds. The currently used external morphological characters to distinguish between species within this genus present some limitations. We used the second internal transcribed spacer region (ITS2) of the rRNA gene as a molecular marker to differentiate adult specimens of Philornis identified morphologically as Philornis torquans and Philornis seguyi from different localities. Specimens identified as P. seguyi from Magdalena (Buenos Aires Province) showed an ITS2 sequence different from that for P. torquans, whereas all other specimens of P. seguyi had sequences identical to those for P. torquans. These findings do not necessarily confirm that specimens from Magdalena indeed belong to P. seguyi, nor that P. seguyi is a valid species. Instead, they alert us about the potential for species misidentification when using morphological characters alone. The use of molecular approaches to aid the identification of Philornis spp. will shed light on the systematics of this group. P. torquans is reported for the first time in Mendoza Province and Uruguay.     

Growth and biochemical characterization of microalgal biomass produced in bubble column and airlift photobioreactors: studies in fed-batch culture

Relatively large (0.19 m column diameter, 2 m tall, 0.06 m³ working volume) outdoor bubble column and airlift bioreactors (a split-cylinder and a draft-tube airlift device) were compared for monoseptic fed-batch culture of the microalga Phaeodactylum tricornutum. The three photobioreactors produced similar biomass versus time profiles and final biomass concentration (4 kg m⁻³). The maximum specific growth rate observed within a daily illuminated period in the exponential growth phase, had a value of 0.08 h⁻¹ on the third day of culture. Because of night-time losses of biomass, the specific growth rate averaged over the 4-days of exponential phase was 0.021 h⁻¹ for the three reactors.

The biomass in the vertical column reactors did not experience photoinhibition under conditions (photosynthetically active daily averaged irradiance value of 1150±52 μE m⁻² s⁻¹) that are known to cause photoinhibition in conventional thin-tube horizontal loop reactors. Because of good gas-liquid mass transfer, the dissolved oxygen concentration in the reactors at peak photosynthesis remained <120% of air saturation; thus, oxygen inhibition of photosynthesis and photo-oxidation of the biomass did not occur. Carbohydrate accumulation (up to 13% w/w) by the biomass was favored during light-limited linear growth. A declining light intensity caused a more than five-fold increase in cellular carotenoids but the chlorophylls increased only by about 2.5-fold during the course of the culture. In the stationary phase, up to 2% of the biomass was chlorophylls and carotenoids constituted up to 0.5% of the biomass dry weight.