Inter-patient variability upon induction with sevoflurane estimated by the time to reach predefined end-points of depth of anaesthesia

BACKGROUND AND OBJECTIVES

A difficult issue in anaesthesia is its titration for an individual patient to avoid over- and underdosage. Common practice is to use an initial dose and increase it subsequently if the defined end-point is not reached. This assumes that the end-point is reached after a similar interval of time in all patients given a similar dose. In order to test this hypothesis we measured the time to reach end-points such as loss of consciousness (LOC), a bispectral index (BIS) value of 60, the minimal BIS and the minimal mean arterial pressure (MAP) values.

METHODS

Thirty patients aged 18-60 yr scheduled for general surgery were included in this observational study. After preoxygenation, induction was performed with 6% inspired concentration of sevoflurane in 6 Lmin-1 oxygen using the SiBI connector and the tidal volume technique. Remifentanil was administered when the BIS value was 60 and tracheal intubation was performed 4 min later.

RESULTS

Time (median, minimum-maximum) to LOC, a BIS value of 60, the minimal BIS and MAP values were, respectively, 75 (45-135), 120 (75-270), 300 (120-720) and 450 (120-1200) seconds. The time to the minimal BIS value was significantly (P < 0.05) shorter than the time to reach the minimal MAP value.

CONCLUSIONS

These results demonstrate large inter-patient variability for the time necessary to reach defined end-points of depth of anaesthesia when a similar dose of anaesthetic is given. Measuring the time to reach a predefined BIS value would allow application of nociceptive stimuli only at adequate levels of hypnosis and would facilitate titration.

161 LIPID CONTENT, RESISTANCE TO CRYOPRESERVATION, AND SEX RATIO OF IN VITRO BOVINE BLASTOCYSTS PRODUCED IN A SERUM-FREE SYSTEM

In vitro-produced (IVP) bovine blastocysts are known to be more sensitive to cryopreservation than their in vivo counterparts. Removing serum from the culture medium decreases sanitary risk and could improve embryo resistance to cryopreservation by preventing the accumulation of intracellular lipids. Our objectives were to evaluate the lipid content, resistance to cryopreservation, and sex ratio of IVP embryos cultured in a serum-free system. Oocytes from slaughterhouse ovaries were matured in a serum-free enriched medium (Donnay et al. 2004 Reprod. Fertil. Dev. 16, 274) and cultured in 5% O2 in modified SOF supplemented with 5% FCS (FCS) or with insulin-transferrin-selenium (ITS) and 0.1 mg/mL polyvinylpyrrolidone (PVP) (ITS-PVP) or 4 mg/mL BSA (ITS-BSA) (Daniaux et al. 2005 Reprod. Fertil. Dev. 17, 217). Day 5 morulae were stained with the fluorescent dye Nile Red in order to evaluate their lipid content (Genicot et al. 2005 Theriogenology 63, 1181). Day 7 blastocysts (diameter ≥160 µm) were selected, classified according to their size, and frozen in HEPES-SOF containing 1.5 M ethylene glycol, 0.1 M sucrose, and 1.8 mg/mL wheat peptones (George et al. 2002 Reproduction 29, 51). The lipid content was significantly lower in morulae cultured in ITS-BSA compared with the two other media (320 ± 10 arbitrary fluorescence units vs. 383 ± 12 in FCS and 406 ± 10 in ITS-PVP; n = 271; ANOVA2: P < 0.01). After cryopreservation, a higher total hatching rate was found 24 h post-thawing in blastocysts cultured in ITS-BSA and for both serum-free conditions at 48 h (Table 1). In particular, embryos ≤180 µm cultured in FCS were less resistant to cryopreservation than embryos of the same size produced without serum. Expanded blastocysts cultured in ITS-BSA were sexed by PCR (Grisart et al. 1995 Theriogenology 43, 1097) and a higher proportion of male embryos was found (62.7%; n = 51). In conclusion, a complete serum-free system was set up from oocyte maturation to embryo cryopreservation that gave high quality embryos resistant to cryo-preservation. Embryos produced in ITS-BSA presented a lower lipid content, but a shift of the expanded blastocyst sex ratio toward males was observed. Table 1. Hatching rates post-thawing as a function of the blastocyst size and the culture medium

Evaluation of a 2% chlorhexidine gluconate in 70% isopropyl alcohol skin disinfectant

The efficacy of a new skin disinfectant, 2% (w/v) chlorhexidine gluconate (CHG) in 70% (v/v) isopropyl alcohol (IPA) (ChloraPrep), was compared with five commonly used skin disinfectants against Staphylococcus epidermidis RP62A in the presence or absence of protein, utilizing quantitative time-kill suspension and carrier tests. All six disinfectants [70% (v/v) IPA, 0.5% (w/v) aqueous CHG, 2% (w/v) aqueous CHG, 0.5% (w/v) CHG in 70% (v/v) IPA and 10% (w/v) aqueous povidone iodine (PI)] achieved a log(10) reduction factor of 5, in colony-forming units/mL, in a suspension test (exposure time 30s) in the presence and absence of 10% human serum. Subsequent challenges of S. epidermidis RP62A in a biofilm (with and without human serum) demonstrated reduced bactericidal activity. Overall, the most effective skin disinfectants tested against S. epidermidis RP62A were 2% (w/v) CHG in 70% IPA and 10% (w/v) PI. These results suggest that enhanced skin antisepsis may be achieved with 2% (w/v) CHG in 70% (v/v) IPA compared with the three commonly used CHG preparations [0.5% (w/v) aqueous CHG, 2% (w/v) aqueous CHG and 0.5% (w/v) CHG in 70% (v/v) IPA].

Effects of oligofructose on glucose and lipid metabolism in patients with nonalcoholic steatohepatitis: results of a pilot study

OBJECTIVE

In experimental animals, recent results suggest that the addition of inulin-type fructans such as oligofructose (OFS) in the diet decreases triacylglycerol accumulation in the liver tissue. Therefore, we have investigated the effect of daily ingestion of OFS in seven patients with nonalcoholic steatohepatitis (NASH), confirmed by liver biopsies.

DESIGN

They received 16 g/day OFS or maltodextrine (placebo) for 8 weeks in a randomized double-blind crossover design. Energy intake, body composition, liver steatosis and blood parameters were analysed after 4 and 8 weeks of dietary supplementation.

RESULTS

Compared to placebo, OFS decreased significantly serum aminotransferases, aspartate aminotransferase after 8 weeks, and insulin level after 4 weeks, but this could not be related to significant effect on plasma lipids.

CONCLUSION

This pilot study supports the putative interest of OFS in the management of liver diseases associated with abnormal lipid accumulation in humans.

Expression of the HPV16E7 oncoprotein by thymic epithelium is accompanied by disrupted T cell maturation and a failure of the thymus to involute with age

Transgenic mice expressing the E7 protein of HPV16 from the keratin 14 promoter demonstrate increasing thymic hypertrophy with age. This hypertrophy is associated with increased absolute numbers of all thymocyte types, and with increased cortical and medullary cellularity. In the thymic medulla, increased compartmentalization of the major thymic stromal cell types and expansion of thymic epithelial cell population is observed. Neither an increased rate of immature thymocyte division nor a decreased rate of immature thymocyte death was able to account for the observed hypertrophy.

Thymocytes with reduced levels of expression of CD4 and/or CD8 were more abundant in transgenic (tg) mice and became increasingly more so with age. These thymic SP and DP populations with reduced levels of CD4 and/or CD8 markers had a lower rate of apoptosis in the tg than in the non-tg mice. The rate of export of mature thymocytes to peripheral lymphoid organs was less in tg animals relative to the pool of available mature cells, particularly for the increasingly abundant CD4^lo population. We therefore suggest that mature thymocytes that would normally die in the thymus gradually accumulated in E7 transgenic animals, perhaps as a consequence of exposure to a hypertrophied E7-expressing thymic epithelium or to factors secreted by this expanded thymic stromal cell population. The K14E7 transgenic mouse thus provides a unique model to study effects of the thymic epithelial cell compartment on thymus development and involution.

Analogues of virus resistance genes map to QTLs for resistance to sharka disease in Prunus davidiana

Plum pox virus (PPV), the causative agent of sharka disease in Prunoideae, is one of the most serious problems affecting stone fruit production in Europe and America. Resistance to PPV was previously described in a Prunus davidiana clone, P1908, and introduced into peach (Prunus persica) genotypes. Genetic resistance to PPV displays a complex pattern of quantitative inheritance. An analysis of quantitative trait loci (QTLs) for resistance was performed on an F1 interspecific peach population obtained from a cross between the susceptible nectarine cultivar Summergrand and P. davidiana. The hybrids were graft-inoculated with PPV in duplicate following a classical procedure. The incidence of infection was evaluated four times, over two vegetative cycles, by symptom observation and enzyme-linked immunoadsorbent assays (ELISA). Restriction of systemic downward movement of the PPV virus was also evaluated by testing the susceptible rootstocks. Using both analysis of variance and non-parametric tests, six genomic regions involved in PPV resistance were detected. Depending on the scoring data considered, between 22 and 51% of the phenotypic variance could be explained by the quantitative model. One QTL, located in the distal region of linkage group 1, maps in a genomic region that is syntenic to the location of a resistance gene previously identified in the apricot cv. Goldrich. Some QTLs appeared to be temporally specific, reflecting the environmental dependence of PPV-resistance scoring. Candidate gene fragments were amplified by PCR, isolated and mapped on the peach interspecific linkage map. We report here the co-localization of three analogues of virus resistance genes with two distinct genomic regions linked to PPV resistance in P. davidiana.

Surprising sun: a new step towards a complete picture?

Important revisions of the solar model ingredients have appeared recently. We first show that the updated CNO composition suppresses the anomalous position of the Sun in the known galactic enrichment. The following law, He/H = 0.075 + 44.6 O/H in number fraction, is now compatible with all the indicators. We then suggest some directions of investigation to solve the discrepancies between the standard model and solar seismic observations. We finally update our predicted neutrino fluxes using a seismic model and all the recent progress. We get 5.31 +/- 0.6 x 10(6)/cm2/s for the total 8B neutrinos, 66.5 +/- 4.4 SNU and 2.76 +/- 0.4 SNU for the gallium and chlorine detectors, all in remarkable agreement with the detected values including neutrino oscillations for the last two. So, the acoustic modes and detected neutrinos see the same Sun, but the standard model fails to reproduce them.

Hypoxaemia after cardiac surgery: clinical application of a model of pulmonary gas exchange

BACKGROUND AND OBJECTIVE

To investigate the clinical application of a mathematical model of pulmonary gas exchange, which ascribes hypoxaemia to shunt and ventilation/perfusion mismatch. Ventilation/perfusion mismatch is quantified by deltaPO2, which is the drop in oxygen pressure from alveoli to lung capillaries. Shunt and deltaPO2 were used to describe changes in oxygenation after coronary artery bypass grafting.

METHODS

Fourteen patients were studied 2-4 h after surgery and on postoperative days 2, 3 and 7. On each occasion inspired oxygen fraction was changed in four to six steps to obtain arterial oxygen saturation (SaO2) in the range of 90-100%, enabling construction of FEO2/SaO2 curves. Measurements of ventilation, circulation and oxygenation were entered in a previously described mathematical model of pulmonary gas exchange.

RESULTS

We found that oxygenation was most impaired 3 days after surgery. By fitting the mathematical model to the FEO2/SaO2 curve, we found that shunt remained constant throughout the study period. However, deltaPO2 increased from 0.5 kPa (median, range 0-3.8) 2-4 h after surgery, to 3.2 kPa (range 1.2-6.4, P < 0.05) on day 2, and to 4.0 kPa (range 1.2-8.3) on day 3. On day 7, deltaPO2 decreased to 2.2 kPa (range 0-3.5, P < 0.05).

CONCLUSIONS

Ventilation/perfusion mismatch (deltaPO2), rather than shunt, explains the changes in postoperative oxygenation. The model of pulmonary gas exchange may serve as a useful and potentially non-invasive clinical tool for monitoring patients at risk of postoperative hypoxaemia.

Characterization and identification of the Detroit River mystery oil spill (2002)

In this paper, a case study of the Detroit River mystery oil spill (2002) is presented that demonstrates the utility of detailed and integrated oil fingerprinting in investigating unknown or suspected oil spills. The detailed diagnostic oil fingerprinting techniques include determination of hydrocarbon groups and semi-quantitative product screening, analysis of oil-characteristic biomarkers and the extended suite of parent and alkylated polycyclic aromatic hydrocarbons (PAHs), and quantitative determination of a variety of diagnostic ratios of "source-specific marker" compounds. The detailed chemical fingerprinting data and results highlight the followings: (1) The spill samples were largely composed of used lube oil mixed with smaller portion of diesel fuel. (2) The diesel in the samples had been weathered and degraded. (3) Sample 3 collected from N. Boblo Island on 14 April was more weathered (most probably caused by more evaporation and water-washing) than samples 1 and 2. (4) All fingerprinting results clearly demonstrated oils in three samples were the same, and they came from the same source. (5) Most PAH compounds were from the diesel portion in the spill samples, while the biomarker compounds were largely from the lube oil. (6) Input of pyrogenic PAHs to the spill samples was clearly demonstrated. The pyrogenic PAHs were most probably produced from combustion and motor lubrication processes, and the lube oil in these spill samples was waste lube oil.

Genetic linkage maps of two apricot cultivars ( Prunus armeniaca L.) compared with the almond Texas x peach Earlygold reference map for Prunus

Several genetic linkage maps have been published in recent years on different Prunus species suggesting a high level of resemblance among the genomes of these species. One of these maps (Joobeur et al., Theor Appl Genet 97:1034-1041 [(1998); Aranzana et al., Theor Appl Genet 106:819-825 (2002b)] constructed from interspecific almond Texas x peach Earlygold F(2) progeny (TxE) was considered to be saturated. We selected 142 F(1) apricot hybrids obtained from a cross between P. armeniaca cvs. Polonais and Stark Early Orange for mapping. Eighty-eight RFLP probes and 20 peach SSR primer pairs used for the 'reference map' were selected to cover the eight linkage groups. One P. davidiana and an additional 14 apricot simple sequence repeats (SSRs) were mapped for the F(1) progeny. Eighty-three amplified fragment length polymorphisms were added in order to increase the density of the maps. Separate maps were made for each parent according to the 'double pseudo-testcross' model of analysis. A total of 141 markers were placed on the map of Stark Early Orange, defining a total length of 699 cM, and 110 markers were placed on the map of Polonais, defining a total length of 538 cM. Twenty-one SSRs and 18 restriction placed in the TxE map were heterozygous in both parents (anchor loci), thereby enabling the alignment of the eight homologous linkage groups of each map. Except for 15 markers, most markers present in each linkage group in apricot were aligned with those in TxE map, indicating a high degree of colinearity between the apricot genome and the peach and almond genomes. These results suggest a strong homology of the genomes between these species and probably between Prunophora and Amygdalus sub-genera.

A literature review of portable fluorescence-based oil-in-water monitors

The results of a literature search on fluorescence-based portable detectors to measure the real-time concentration of oil are reported. For more than two decades, fluorometers have been commonly employed to monitor dispersed oil levels at oil spills on water. The focus of this paper has been to extract specific information from references about how the instruments were used, including set up and calibration procedures, the oil and dispersant measured, the approximate concentration range of the oil in the water column, and how the real-time data compared to traditional laboratory techniques.

Field fluorometers as dispersed oil-in-water monitors

A laboratory study of the Turner Instrument flow-through models 10AU and 10 fluorometers was conducted to review their ability to measure real-time oil-in-water concentrations, to compare the results to other total petroleum hydrocarbon (TPH) procedures and to improve the understanding of the relationship of the fluorescence to the chemical composition of the oils. Comparison of the fluorometer results to standard infrared and gas chromatography laboratory procedures showed all methods capable of detecting and differentiating between small changes in oil concentration. The infrared and gas chromatography generated similar values while the fluorometer values were of the same order of magnitude but typically 20-80% higher. The chemical composition of the oils was determined by gas chromatographic techniques and compared to the signal outputs of the fluorometers. It was found that the fluorometer data could not be directly linked to the concentration of any specific aromatic hydrocarbon such as naphthalene or to the sum of the polycyclic aromatic hydrocarbon (PAH) compounds. Evidence suggests that the fluorescence signal is generated by a combination of PAH compounds. Also, the response of the fluorometers may also be influenced by the presence of volatile aromatic compounds such as benzene, toluene, ethyl benzene and xylene (BTEX) and C3-benzenes (BTEX + C3B) in combination with the PAH compounds.

Genetic diversity in apricot revealed by AFLP markers: species and cultivar comparisons

The genetic diversity of apricot ( Prunus armeniaca; 2n = 16) was studied using AFLP markers. Forty seven apricot cultivars were selected from the following geographic regions: Europe, North America, North Africa, Turkey, Iran and China. Five EcoRI- MseI AFLP primer combinations revealed 416 legible bands, of which 379 were polymorphic markers. A similarity matrix was prepared using the simple matching coefficient of similarity. A UPGMA dendrogram demonstrated a gradient of decreasing genetic diversity of varieties from the former USSR to Southern Europe. This is coherent with the historical dissemination of apricot from its center of origin in Asia. The American cultivars were intermediate demonstrating a different genetic base than the European and/or Mediterranean cultivars. Euclidean distances from the first ten Factorial Component Analysis coordinate axes were used to generate a tree using the Ward algorithm. The results of these analyses were evaluated based on the known geographic origins and agronomic characteristics of the cultivars studied. Four cultivar groups were identified: Diversification, Geographically Adaptable, Continental Europe and Mediterranean Basin. To evaluate the relationship of the common apricot with some closely related species, one or two accessions of the following related species or sub-species from within the section Armeniaca were included in the analysis: Prunus armeniaca var. ansu, Prunus mume, Prunus brigantiaca, Prunus dasycarpa, and Prunus holosericea. A Neighbour Joining dendrogram was made using the similarity matrix. The P. holosericea accession fell well within the cultivar group, thus supporting its classification as a variant of P. armeniaca. The P. armeniaca var. ansu accession was sister to the common apricot cluster with a bootstrap value of 96%. P. mume was farther removed. P. brigantiaca was the most-distant from the common apricots. P. dasycarpa was intermediate between P. brigantiaca and P. mume, in accord with its plum-apricot hybrid origin. The results have a direct application for the selection of new breeding progenitors.

Effect of concentration and biochemical assay on the accuracy of urine dipsticks in hypertensive pregnancies

OBJECTIVE

To assess how urine concentration and biochemical assay influence the assessment of proteinuria.

METHODS

This was a prospective study to assess the accuracy of detection and quantification of proteinuria within the day assessment unit and antenatal ward of a teaching hospital in Leicester, United Kingdom. We studied hypertensive pregnancies (of mixed parity) referred to day care assessment or attending the antenatal hypertension clinic after 20 completed weeks of gestation (n = 197). Aliquots of a well-mixed 24-h urine collection were tested by routine dipstick urinalysis and then assayed for protein using the Benzethonium Chloride and the Bradford assays (n = 197).

MAIN OUTCOME MEASURES

Total protein excretion in 24 h and protein concentration per liter of urine for both biochemical assays were compared to semiquantitative dipstick protein measurement.

RESULTS

The prevalence of proteinuria in the study group varied according to the method used for testing. Dipstick urinalysis recorded the lowest prevalence (16.2%) and the Benzethonium Chloride assay measuring total protein excretion in 24 h recorded the highest (70.1%). When the positive and negative predictive values for dipstick urinalysis were calculated, performance was found to be dependent on both the units of measurement compared and the type of assay used as the "gold standard." Positive predictive values ranged from 87.5% to 96.9% and negative predictive values ranged from 35.2% to 92.1%.

CONCLUSIONS

The prevalence of proteinuria in hypertensive pregnancies is dependent on the method used to detect it. The amount of protein assessed quantitatively is further dependent on the biochemical assay employed. However, regardless of the quantitative assessment, dipstick urinalysis has a significant false-negative rate. This first reporting of a variation in performance between dipstick urinalysis and two different biochemical assays in pregnancy may be explained in relation to protein assay specificity and the observed protein compositions of the samples on electrophoretic analysis. The significance of proteinuria should be considered in light of the method used to detect it, but, ultimately, it must be related to clinical outcome.

Carbapenem-resistant Acinetobacter and role of curtains in an outbreak in intensive care units

Multiple-antibiotic-resistant Acinetobacter baumanii, including meropenem resistance, was first isolated from a patient in the general intensive care unit of a tertiary-referral university teaching hospital in Birmingham in December 1998. Similar strains were subsequently isolated from 12 other patients, including those on another intensive care unit within the hospital. The outbreak followed an increase in the use of meropenem in both the units. Environmental screening revealed the presence of the multiple-resistant Acinetobacter species on fomite surfaces in the intensive care unit and bed linen. The major source appeared to be the curtains surrounding patients' beds. Typing by pulsed field gel electrophoresis demonstrated that the patients' isolates and those from the environment were indistinguishable. Rigorous infection control measures including increased frequency of cleaning of the environment with hypochlorite (1000 ppm) and twice-weekly changing of curtains were implemented, along with restriction of meropenem use in the units. Isolation of the multiple-resistant Acinetobacter spp. subsequently diminished and it was not detected over a follow-up period of 18 months. To our knowledge, this is the first reported outbreak of carbapenem-resistant Acinetobacter spp. from the UK. This outbreak also highlights environmental sources, particularly dry fabrics such as curtains, as an important reservoir for dissemination of acinetobacters.

Tolerance or immunity to a tumor antigen expressed in somatic cells can be determined by systemic proinflammatory signals at the time of first antigen exposure

Mice transgenic for the E7 tumor Ag of human papillomavirus type 16, driven from a keratin 14 promoter, express E7 in keratinocytes but not dendritic cells. Grafted E7-transgenic skin is not rejected by E7-immunized mice that reject E7-transduced transplantable tumors. Rejection of recently transplanted E7-transgenic skin grafts, but not of control nontransgenic grafts or of established E7-transgenic grafts, is induced by systemic administration of live or killed Listeria monocytogenes or of endotoxin. Graft recipients that reject an E7 graft reject a subsequent E7 graft more rapidly and without further L. monocytogenes exposure, whereas recipients of an E7 graft given without L. monocytogenes do not reject a second graft, even if given with L. monocytogenes. Thus, cross-presentation of E7 from keratinocytes to the adaptive immune system occurs with or without a proinflammatory stimulus, but proinflammatory stimuli at the time of first cross-presentation of Ag can determine the nature of the immune response to the Ag. Furthermore, immune effector mechanisms responsible for rejection of epithelium expressing a tumor Ag in keratinocytes are different from those that reject an E7-expressing transplantable tumor. These observations have implications for immunotherapy for epithelial cancers.

Enhancement of the p300 HAT activity by HIV-1 Tat on chromatin DNA

HIV-1 Tat is able to form a ternary complex with P/CAF and p300 and increase the affinity for CDK9/P-TEFb CTD kinase complex. Our previous study demonstrated that Tat binds to p300/CBP in the minimal HAT domain (aa 1253-1790) and that the interaction results in a change of conformation on p300/CBP. Here, we show that the Tat-p300 interaction increases the HAT activity of p300 on histone H4 that is associated with nucleosomal DNA and not with free histones. Nucleosomal histone H4 was acetylated on lysines 8, 12, and 16. Acetylation of H4 was inhibited by Lys-coenzyme A (CoA), a selective inhibitor of p300 acetyltransferase activity. Unexpectedly, we also found that Tat could autoacetylate itself, which was specific to lysine residues 41 and 71. Peptides lacking these two lysines could not enhance the HAT activity of p300. Comparison of the sequences of Tat with other HIV-1 clades and HAT containing transcription factors indicated sequence identity in the acetyl-CoA binding motif A, KGXG. Furthermore, when utilizing an in vitro transcription assay, as well as a Tat mutant virus, we found that ectopic expression of only wild-type Tat in the presence of p300, and not a lysine 41 Tat mutant, could activate HIV-1 chromatin DNA, as evidenced by the absence of HIV-1 virion antigen. Therefore, transcription of integrated viral DNA in vivo requires the HAT activity of coactivators that are modulated by Tat to derepress the HIV-1 chromatin structure and aid in activated transcription.

Effect of conventional controlled-rate freezing and vitrification on morphology and metabolism of bovine blastocysts produced in vitro

This study compares the effects of conventional controlled-rate freezing and vitrification on the morphology and metabolism of in vitro-produced bovine blastocysts. Day 7 expanded blastocysts cultured in synthetic oviduct fluid with 5% fetal calf serum were frozen in 1.36 M glycerol, 0.25 M sucrose or vitrified in 25% glycerol, 25% ethylene glycol. Cell alterations and in vitro development were evaluated immediately after thawing or after 72 h. The effect of cryopreservation on inner cell mass and trophectoderm (TE) cell number as well as glucose, pyruvate, and oxygen uptakes, and lactate release by blastocysts were evaluated. Immediately after thawing, blastocysts showed equivalent cell membrane permeabilization after both cryopreservation procedures, while alterations in nuclear staining were more frequent in vitrified embryos. After culture, similar survival and hatching rates were observed. Both procedures decreased cell number immediately after thawing and after 72 h. However, the number of TE cells was lower in frozen embryos than in vitrified ones. In relation to this, frozen blastocysts showed a decrease in glucose, pyruvate, and oxygen uptake, although those parameters were not altered in vitrified embryos. An increased glycolytic activity was also observed in frozen embryos, indicating a stress response to this procedure.

Nonspecific down-regulation of CD8+ T-cell responses in mice expressing human papillomavirus type 16 E7 oncoprotein from the keratin-14 promoter

The E7 oncoprotein of human papillomavirus 16 (HPV16) transforms basal and suprabasal cervical epithelial cells and is a tumor-specific antigen in cervical carcinoma, to which immunotherapeutic strategies aimed at cytotoxic T-lymphocyte (CTL) induction are currently directed. By quantifying major histocompatibility complex class I tetramer-binding T cells and CTL in mice expressing an HPV16 E7 transgene from the keratin-14 (K14) promoter in basal and suprabasal keratinocytes and in thymic cortical epithelium, we show that antigen responsiveness of both E7- and non-E7-specific CD8+ cells is down-regulated compared to non-E7 transgenic control mice. We show that the effect is specific for E7, and not another transgene, expressed from the K14 promoter. Down-regulation did not involve deletion of CD8+ T cells of high affinity or high avidity, and T-cell receptor (TCR) Vbeta-chain usage and TCR receptor density were similar in antigen-responsive cells from E7 transgenic and non-E7 transgenic mice. These data indicate that E7 expressed chronically from the K14 promoter nonspecifically down-regulates CD8+ T-cell responses. The in vitro data correlated with the failure of immunized E7 transgenic mice to control the growth of an E7-expressing tumor challenge. We have previously shown that E7-directed CTL down-regulation correlates with E7 expression in peripheral but not thymic epithelium (T. Doan et al., J. Virol. 73:6166-6170, 1999). The findings have implications for the immunological consequences of E7-expressing tumor development and E7-directed immunization strategies. Generically, the findings illustrate a T-cell immunomodulatory function for a virally encoded human oncoprotein.

Solvent vapour monitoring in work space by solid phase micro extraction

Solid phase micro extraction (SPME) is a fast, solvent-less alternative to conventional charcoal tube sampling/carbon disulfide extraction for volatile organic compounds (VOC). In this work, SPME was compared to the active sampling technique in a typical lab atmosphere. Two different types of fibre coatings were evaluated for solvent vapour at ambient concentration. A general purpose 100 microm film polydimethylsiloxane (PDMS) fibre was found to be unsuitable for VOC work, despite the thick coating. The mixed-phase carboxen/PDMS fibre was found to be suitable. Sensitivity of the SPME was far greater than charcoal sorbent tube method. Calibration studies using typical solvent such as dichloromethane (DCM), benzene (B) and toluene (T) showed an optimal exposure time of 5 min, with a repeatability of less than 20% for a broad spectrum of organic vapour. Minimum detectable amount for DCM is in the range of 0.01 microg/l (0.003 ppmv). Variation among different fibres was generally within 30% at a vapour concentration of 1 microg DCM/l, which was more than adequate for field monitoring purpose. Adsorption characteristics and calibration procedures were studied. An actual application of SPME was carried out to measure background level of solvent vapour at a bench where DCM was used extensively. Agreement between the SPME and the charcoal sampling method was generally within a factor of two. No DCM concentration was found to be above the regulatory limit of 50 ppmv.

Use of a portable infra-red analyzer for low-level hydrocarbon emissions

During some on-site tests, a portable infra-red (IR) analyzer was used successfully to monitor for hydrocarbon vapors. The detection limit of the IR analyzer is much lower than that of most other hydrocarbon vapor monitors and can be used in situations where, as in most ambient air monitoring situations, the levels are often less than a milligram per cubic metre (mg/m(3)). Traditional procedures used to measure hydrocarbon concentrations at lower levels involves the collection of samples on-site, which are then transported to a laboratory for analysis. The advantage of providing continuous sampling data is that it may indicate trends in the hydrocarbon vapor emissions that may not be apparent using a grab-type sample. The initial tests were designed to determine if the IR analyzer was capable of monitoring the low-level hydrocarbons in a field situation. The findings from that initial work was followed by modification of the test procedure to include an upwind IR analyzer, shortened sampling cycles to produce more data, and additional canister samples collected outside the burn period. The metered grab samples, using Summa canisters, were collected over a 1h period and any results would therefore, reflect an average value over the hour. The IR analyzer, with a sampling cycle of approximately 1min, was able to produce a near real-time distribution of the hydrocarbon vapors in the test site emissions. Because the testing parameters and methods are quite different, it is difficult to compare these two methods, but indications suggest strongly that the use of this portable IR instrument could help to describe the hydrocarbon emissions downwind from a source, as well as to monitor for these hydrocarbons continuously, including situations where the levels are below detection limits of most portable detectors.

An evaluation of field total petroleum hydrocarbon (TPH) systems

An evaluation of several field kits and petroleum hydrocarbon measuring systems was conducted. The field kits were the immunoassay based EnviroGard petroleum fuels in soil test kit (EnviroGard, Millipore Canada, Mississauga, Ont., Canada), the turbidimetric based PetroFlag hydrocarbon test kit for soil (Dexsil, Hamden, CT, USA), a DR/2000 field kit (Hach Company, Loveland CO, USA) employing colorimetric test procedures and a total organic carbon (TOC) analysis instrument (Dohrmann Division, Rosemount Analytical Inc., Santa Clara, CA, USA) using oxidation principles. These procedures were compared to the traditional technique of extraction of the petroleum hydrocarbons using trichlorotrifluoroethane (Freon 113) as the solvent and subsequent infrared (IR) analysis using a portable fixed wavelength analyzer (Buck Scientific, East Norwalk, CT, USA). The EnviroGard kit was affected by the sample matrix. The soil type and the presence or lack thereof specific chemical components affected the capability to detect the petroleum hydrocarbon concentration. The PetroFlag soil test kit tended to generate results higher than the accepted concentration. The IR method was better capable of producing results similar to the expected concentration values of the prepared samples. Results indicate that the total organic carbon analysis technique evaluated is best suited for samples containing dissolved hydrocarbons in water and is not a preferred procedure for water samples containing dispersed or floating oil. At low concentrations of 10ppm and less, the TOC method and IR method have concentration values within a few parts-per-million (ppm) of each other, however, an examination of the trends in the results for all samples shows no similarity. This would indicate that the traditional extraction and infrared method and the total organic carbon method are not measuring the same parameter.Finally, the colorimetric field kit was capable of quantifying the concentration of oil in water samples within limits. The results from the oil-in-water method built into the unit at the factory were not comparable with analysis carried out by the infrared technique. With specific methods for each oil incorporated into the spectrophotometer, the comparability of data increased significantly. Results generated by the kit are dependent upon the color and amount of the oil in the sample. The kit is best suited for dark colored oils and the water samples with concentrations in the range of 10 to 85ppm by weight.