Effective Mechanisms for Improving Seed Oil Production in Pennycress (Thlaspi arvense L.) Highlighted by Integration of Comparative Metabolomics and Transcriptomics

Pennycress is a potentially lucrative biofuel crop due to its high content of long-chain unsaturated fatty acids, and because it uses non-conventional pathways to achieve efficient oil production. However, metabolic engineering is required to improve pennycress oilseed content and make it an economically viable source of aviation fuel. Research is warranted to determine if further upregulation of these non-conventional pathways could improve oil production within the species even more, which would indicate these processes serve as promising metabolic engineering targets and could provide the improvement necessary for economic feasibility of this crop. To test this hypothesis, we performed a comparative biomass, metabolomic, and transcriptomic analyses between a high oil accession (HO) and low oil accession (LO) of pennycress to assess potential factors required to optimize oil content. An evident reduction in glycolysis intermediates, improved oxidative pentose phosphate pathway activity, malate accumulation in the tricarboxylic acid cycle, and an anaplerotic pathway upregulation were noted in the HO genotype. Additionally, higher levels of threonine aldolase transcripts imply a pyruvate bypass mechanism for acetyl-CoA production. Nucleotide sugar and ascorbate accumulation also were evident in HO, suggesting differential fate of associated carbon between the two genotypes. An altered transcriptome related to lipid droplet (LD) biosynthesis and stability suggests a contribution to a more tightly-packed LD arrangement in HO cotyledons. In addition to the importance of central carbon metabolism augmentation, alternative routes of carbon entry into fatty acid synthesis and modification, as well as transcriptionally modified changes in LD regulation, are key aspects of metabolism and storage associated with economically favorable phenotypes of the species.

CNS Hypomyelination Disrupts Axonal Conduction and Behavior in Larval Zebrafish

Myelination is essential for central nervous system (CNS) formation, health and function. As a model organism, larval zebrafish have been extensively employed to investigate the molecular and cellular basis of CNS myelination, because of their genetic tractability and suitability for non-invasive live cell imaging. However, it has not been assessed to what extent CNS myelination affects neural circuit function in zebrafish larvae, prohibiting the integration of molecular and cellular analyses of myelination with concomitant network maturation. To test whether larval zebrafish might serve as a suitable platform with which to study the effects of CNS myelination and its dysregulation on circuit function, we generated zebrafish myelin regulatory factor (myrf) mutants with CNS-specific hypomyelination and investigated how this affected their axonal conduction properties and behavior. We found that myrf mutant larvae exhibited increased latency to perform startle responses following defined acoustic stimuli. Furthermore, we found that hypomyelinated animals often selected an impaired response to acoustic stimuli, exhibiting a bias toward reorientation behavior instead of the stimulus-appropriate startle response. To begin to study how myelination affected the underlying circuitry, we established electrophysiological protocols to assess various conduction properties along single axons. We found that the hypomyelinated myrf mutants exhibited reduced action potential conduction velocity and an impaired ability to sustain high-frequency action potential firing. This study indicates that larval zebrafish can be used to bridge molecular and cellular investigation of CNS myelination with multiscale assessment of neural circuit function.SIGNIFICANCE STATEMENT Myelination of CNS axons is essential for their health and function, and it is now clear that myelination is a dynamic life-long process subject to modulation by neuronal activity. However, it remains unclear precisely how changes to myelination affects animal behavior and underlying action potential conduction along axons in intact neural circuits. In recent years, zebrafish have been employed to study cellular and molecular mechanisms of myelination, because of their relatively simple, optically transparent, experimentally tractable vertebrate nervous system. Here we find that changes to myelination alter the behavior of young zebrafish and action potential conduction along individual axons, providing a platform to integrate molecular, cellular, and circuit level analyses of myelination using this model.

Vitrification in straws conserves motility features better than spheres in donkey sperm

Sperm vitrification as alternative to conventional freezing is increasing in popularity in many species. It has been achieved by direct exposure of diluted semen to liquid nitrogen in spheres or straws. Both techniques have been successfully developed, but they had not been compared yet in donkeys. The aim of this study was to compare these two methods of vitrification for donkey semen. Ejaculates from six Andalusian donkeys were collected and extended in Gent without glycerol supplemented with sucrose 0.1 M (Molar). Samples were slowly cooled at 5°C. For vitrification, 30 μl suspensions (spheres) were dropped directly into liquid nitrogen (LN₂ ) or filled in covered 0.25 ml straws and then plunged into the LN₂ (straws). For warming, straws and spheres were directly immersed in 3 ml of INRA-96 at 43°C. Total (TM, %) and progressive motility (PM, %) were objectively evaluated by computer-assisted sperm analysis and plasma membrane integrity (PMI, %) by epifluorescence microscopy. Results showed the straw method resulted in significantly higher values than spheres for: TM (54.7% ± 10.1 vs. 28.6% ± 6.5) and PM (44.2% ± 9.4 vs. 17.7% ± 6.4), but no significant differences were found between straws or spheres for PMI (31.5 ± 10.7 vs. 41.6 ± 14.3) respectively. In conclusion, donkey sperm could be vitrified in straws obtaining better sperm motility parameters after warming in comparison to the sphere method.

Design and expression of recombinant toxins from Mexican scorpions of the genus Centruroides for production of antivenoms

This manuscript describes the design of plasmids containing the genes coding for four main mammalian toxins of scorpions from the genus Centruroides (C.) of Mexico. The genes that code for toxin 2 of C. noxius (Cn2), toxin 2 from C. suffusus (Css2) and toxins 1 and 2 from C. limpidus (Cll1 and Cll2) were included into individual plasmids carrying the genetic construction for expression of fusion proteins containing a leader peptide (pelB) that directs the expressed protein to the bacterial periplasm, a carrier protein (thioredoxin), the cleavage site for enterokinase, the chosen toxin and a poly-histidine tag (6xHis-tag) for purification of the hybrid protein by immobilized metal ion affinity chromatography after expression in Escherichia coli strain BL21 (DE3). The purified hybrid proteins containing the recombinant toxins (abbreviated Thio-EK-Toxin) were used for immunization of three independent groups of ten mice and four rabbits. Challenging the first group of mice, immunized with recombinant Thio-EK-Css2, with three median lethal doses (LD₅₀) of C. suffusus soluble venom resulted in the survival of all the test animals without showing intoxication symptoms. All control mice (none immunized) died. Similar results were obtained with mice previously immunized with Thio-EK-Cn2 and challenged with C. noxius venom. The third group of mice immunized with both Thio-EK-Cll1 and Thio-EK-Cll2 showed an 80% survival ratio when challenged with only one LD₅₀ of C. limpidus venom, all showing symptoms of intoxication. The sera from rabbits immunized with a combination of the four recombinant toxins were collected separately and used to assess their neutralization capacity in vitro (pre-incubating the serum with the respective scorpion venom and injecting the mixture into mice), using six mice for each serum/venom combination tested. The venoms from the six most dangerous scorpion species of Mexico were assayed: C. noxius, C. suffusus, C. limpidus, C. elegans, C. tecomanus and C. sculpturatus. Two hundred and 50 μL of serum from any of the immunized rabbits were enough to neutralize three LD₅₀ of any of the tested venoms, with mice showing no symptoms of intoxication. These results confirm that the recombinant forms of the main toxins from the most dangerous scorpions of Mexico are excellent immunogens for the production of antivenoms to treat scorpion intoxications.

Effects on the metabolism, growth, digestive capacity and osmoregulation of juvenile of Sub-Antarctic Notothenioid fish Eleginops maclovinus acclimated at different salinities

In this study we assessed the influence of three different environmental salinities (5, 15 and 31 psu during 90 days) on growth, osmoregulation, energy metabolism and digestive capacity in juveniles of the Notothenioid fish Eleginops maclovinus. At the end of experimental time samples of plasma, liver, gill, intestine, kidney, skeletal muscle, stomach and pyloric caeca were obtained. Growth, weight gain, hepatosomatic index and specific growth rate increased at 15 and 31 psu and were lower at 5 psu salinity. Gill Na(+), K(+)-ATPase (NKA) activity presented a "U-shaped" relationship respect to salinity, with its minimum rates at 15 psu, while this activity correlated negatively with salinity at both anterior and posterior intestinal portions. No significant changes in NKA activity were observed in kidney or mid intestine. Large changes in plasma, metabolite levels and enzymatic activities related to energy metabolism in liver, gill, intestine, kidney and muscle were generally found in the groups exposed to 5 and 31 psu compared to the 15 psu group. Only the pepsin activity (digestive enzymes) assessed enhanced with environmental salinity, while pyloric caeca trypsin/chymotrypsin ratio decreased. This study suggests that juvenile of E. maclovinus presents greater growth near its iso-osmotic point (15 psu) and hyperosmotic environment (31 psu). Acclimation to low salinity increased the osmoregulatory expenditure as seen by the gill and anterior intestine results, while at high salinity, branchial osmoregulatory activity was also enhanced. This requires the mobilization of lipid stores and amino acids, thereby holding the growth of fish back. The subsequent reallocation of energy sources was not sufficient to maintain the growth rate of fish exposed to 5 psu. Thus, E. maclovinus juveniles present better growth efficiencies in salinities above the iso-osmotic point and hyperosmotic environment of this species, showing their best performance at 15 psu as seen by the main osmoregulatory and energy metabolism enzymatic activities.

Reliability and accuracy of quantitative sensory testing for oxaliplatin-induced neurotoxicity

OBJECTIVES

Thermal quantitative sensory testing (QST) is a non-invasive procedure helpful in the assessment of the function of small Aδ and C nerve sensory fibres. Oxaliplatin (OXA) is an effective chemotherapeutic agent, but is frequently associated with neurotoxic dose-limiting side effects. This controlled clinical trial evaluated the reliability and accuracy of thermal QST for assessing the OXA-induced acute neuropathic syndrome, whose clinical hallmark is cold-triggered painful paraesthesia.

MATERIALS & METHODS

A testing protocol with the Thermal Sensory Analyzer (Medoc) was carried out in 20 colorectal cancer patients during the initial four cycles of OXA-based chemotherapy and in 20 age- and sex-matched healthy volunteers. Testing was carried out on the hands and included the determination of thermal detection and pain thresholds and the intensity of pain evoked by cold stimuli. Calculations were made of: coefficients of test-retest and inter-rater reliability, indices of responsiveness and parameters that quantify diagnostic accuracy.

RESULTS

Thermal thresholds showed moderate to good reliability (ρ ≥ 0.383), but were not consistently responsive to the effects of chemotherapy (cold pain thresholds decreased in both groups, although almost twice in patients compared to healthy volunteers). Conversely, the intensity of pain evoked by suprathreshold cold stimuli was reliable (ρ ≥ 0.822), responsive (detected changes over time) and discriminated between patients and healthy volunteers (area under the ROC curve = 0.700).

CONCLUSIONS

The procedure was reliable and accurate to evaluate cold hyperalgesia resulting from OXA administration. The data provided may be used to define efficacy endpoints for future clinical trials of therapies for OXA-induced neuropathies and calculate appropriate sample sizes.

Scorpion and spider venom peptides: gene cloning and peptide expression

This communication reviews most of the important findings related to venom components isolated from scorpions and spiders, mainly by means of gene cloning and expression. Rather than revising results obtained by classical biochemical studies that report structure and function of venom components, here the emphasis is placed on cloning and identification of genes present in the venomous glands of these arachnids. Aspects related to cDNA library construction, specific or random ESTs cloning, transcriptome analysis, high-throughput screening, heterologous expression and folding are briefly discussed, showing some numbers of species and components already identified, but also shortly mentioning limitations and perspectives of research for the future in this field.

Interaction of Rab31 and OCRL-1 in oligodendrocytes: its role in transport of mannose 6-phosphate receptors

Rab31, a protein that we cloned from an oligodendrocyte cDNA library, is required for transport of mannose 6-phosphate receptors (MPRs) from the trans-Golgi network (TGN) to endosomes and for Golgi/TGN organization. Here we extend the knowledge of the mechanism of action of Rab31 by demonstrating its interaction with OCRL-1, a phosphatidylinositol 4,5-diphosphate 5-phosphatase (PI(4,5)P(2) 5-phosphatase) that regulates the levels of PI(4,5)P(2) and PI(4)P, molecules involved in transport and Golgi/TGN organization. We show that Rab31 interacts with OCRL-1 in a yeast two-hybrid system, GST-Rab31 pull-down experiments, and coimmunoprecipitation of OCRL-1 using oligodendrocyte culture lysates. Rab31 and OCRL-1 colocalize in the TGN, post-TGN carriers, and endosomes. Cation-dependent MPR (CD-MPR) is sorted to OCRL-1-containing carriers, but CD63 and vesicular stomatitis virus G (VSVG) are not. siRNA-mediated depletion of endogenous Rab31 causes collapse of the TGN apparatus and markedly decreases the levels of OCRL-1 in the TGN and endosomes. Our observations indicate that the role of Rab31 in the Golgi/TGN structure and transport of MPRs depends on its capability to recruit OCRL-1 to domains of the TGN where the formation of carriers occurs. The importance of our observations is highlighted by the fact that mutation of OCRL-1 causes demyelination in humans.

Immunogenicity and safety of a pentavalent diphtheria, tetanus, acellular pertussis, inactivated poliovirus, Haemophilus influenzae type B conjugate combination vaccine (Pentaxim) with hepatitis B vaccine

OBJECTIVE

To obtain immunogenicity and safety data for a pentavalent combination vaccine (diphtheria, tetanus, acellular pertussis, inactivated poliovirus, Hib polysaccharide-conjugate).

DESIGN

Multicenter, open, Phase III clinical study. A DTaP-IPV//PRP approximately T vaccine (Pentaxim) was given at 6,10,14 weeks of age; and Hepatitis B vaccine at 0,6,14 or at 6,10,14 weeks of age. Immunogenicity assessed 1 month post-3rd dose; safety assessed for 30 minutes by the investigator, then by parents and investigators to 8 days and 30 days post-vaccination.

SETTING

Tertiary-care hospitals.

PARTICIPANTS/PATIENTS

226 healthy Indian infants (6 weeks of age).

MAIN OUTCOME MEASURES

Immunogenicity and safety.

RESULTS

Immunogenicity was high for each vaccine antigen, and similar to a historical control study (France) following a 2,3,4 month of age administration schedule. Post-3rd dose, 98.6% of subjects had anti-PRP >0.15 mg/mL and 90.0% had titers >1.0 mg/mL; the anti-PRP GMT was 4.1 micrograms/mL. Seroprotection rates for diphtheria and tetanus (>0.01 IU/mL) were 99.1% and 100%; and 100%, 99.1% and 100%, for polio types 1,2 and 3 (>8 [1/dil]) respectively. Anti-polio GMTs were 440.5,458.9, and 1510.7 (1/dil) for types 1,2 and 3 respectively. The vaccine response rates to pertussis antigens (4-fold increase in antibody concentration) were 93.7% for PT and 85.7% for FHA; the 2-fold increase was 97.1% and 92.4%. Vaccine reactogenicity was low with adverse reaction incidence not increasing with subsequent doses.

CONCLUSION

The DTaP-IPV//PRP approximately T vaccine, given concomitantly with monovalent hepatitis B vaccine, was highly immunogenic at 6, 10 and 14 weeks of age in infants in India. The vaccine was well tolerated.

Verification of fetal brain responses by coregistration of fetal ultrasound and fetal magnetoencephalography data

Fetal magnetoencephalography (fMEG) is used to study neurological functions of the developing fetus by measuring magnetic signals generated by electrical sources within the fetal brain. For this aim either auditory or visual stimuli are presented and evoked brain activity or spontaneous activity is measured at the sensor level. However a limiting factor of this approach is the low signal to noise ratio (SNR) of recorded signals. To overcome this limitation, advanced signal processing techniques such as spatial filters (e.g., beamformer) can be used to increase SNR. One crucial aspect of this technique is the forward model and, in general, a simple spherical head model is used. This head model is an integral part of a model search approach to analyze the data due to the lack of exact knowledge about the location of the fetal head. In the present report we overcome this limitation by a coregistration of volumetric ultrasound images with fMEG data. In a first step we validated the ultrasound to fMEG coregistration with a phantom and were able to show that the coregistration error is below 2 cm. In the second step we compared the results gained by the model search approach to the exact location of the fetal head determined on pregnant mothers by ultrasound. The results of this study clearly show that the results of the model search approach are in accordance with the location of the fetal head.

The CDR1 of the human λVI light chains adopts a new canonical structure

We performed a comparative analysis of the conformation of the CDR1 of the human lambdaVI variable domains JTO and WIL and the equivalent loop of the lambdaI light chains RHE and KOL, which are representative of the type I canonical structure for lambda light chains. On the basis of the differences found in the main chain conformation, as well as the identity of the residues at key positions, we showed that the L1 of some lambdaVI light chains adopts a conformation that represents a new type of canonical structure. The conformation of the L1 of those lambdaVI light chains, is primarily determined by the presence of an Arg residue at position 25. The analysis of the lambdaVI light chain sequences so far reported, showed that near 25% of those proteins have Gly at position 25 instead of Arg, which represents an allotypic variant of the lambdaVI variable locus. The presence of Gly at position 25 in the L1 of lambdaVI light chains would imply a different conformation for this loop. Additionally, the position 68 in lambdaVI light chains, which is at the top of the FR3 loop, showed such spatial orientation and variability that suggested its participation in the conformation of the antigen recognition surface in this subgroup of lambda chains.

Effect of manipulation of iron storage, transport, or availability on myelin composition and brain iron content in three different animal models

Several observations suggest that iron is an essential factor in myelination and oligodendrocyte biology. However, the specific role of iron in these processes remains to be elucidated. This role could be as an essential cofactor in metabolic processes or as a transcriptional or translational regulator. In this study, we used animals models each with a unique defect in iron availability, storage, or transfer to test the hypothesis that disruptions in these mechanisms affect myelinogenesis and myelin composition. Disruption of iron availability either by limiting dietary iron or by altering iron storage capacity resulted in a decrease in myelin proteins and lipids but not the iron content of myelin. Among the integral myelin proteins, proteolipid protein was most consistently affected, suggesting that limiting iron to oligodendrocytes results not only in hypomyelination but also in a decrease in myelin compaction. Mice deficient in transferrin must receive transferrin injections beginning at birth to remain viable, and these mice had increases in all of the myelin components and in the iron content of the myelin. This finding indicates that the loss of endogenous iron mobility in oligodendrocytes could be overcome by application of exogenous transferrin. Overall, the results of this study demonstrate how myelin composition can be affected by loss of iron homeostasis and reveal specific chronic changes in myelin composition that may affect behavior and attempts to rescue myelin deficits.

Human single chain Fv antibodies and a complementarity determining region-derived peptide binding to amyloid-beta 1–42

A library of phage-displayed human single-chain Fv (scFv) antibodies was selected against the human amyloid-beta peptide (Abeta42). Two new anti-Abeta42 phage-displayed scFvs antibodies were obtained, and the sequences of their V(H) and Vkappa genes were analyzed. A synthetic peptide based on the sequence of Ig heavy chain (V(H)) complementarity-determining region (HCDR3) of the clone with the highest recognition signal was generated and determined to bind to Abeta42 in ELISA. Furthermore, we showed for the first time that an HCDR3-based peptide had neuroprotective potential against Abeta42 neurotoxicity in rat cultured hippocampal neurons. Our results suggest that not only scFvs recognizing Abeta42 but also synthetic peptides based on the V(H) CDR3 sequences of these antibodies may be novel potential candidates for small molecule-based Alzheimer's disease (AD) therapy.

Anti-nucleosome antibodies in patients with systemic lupus erythematosus of recent onset. Potential utility as a diagnostic tool and disease activity marker

OBJECTIVE

To compare the utility of anti-chromatin antibodies for the diagnosis of systemic lupus erythematosus (SLE) and as markers of disease activity.

METHODS

We included 73 consecutive patients (62 female) with SLE (four or more ACR criteria) of recent onset (<1 yr since diagnosis). As control groups we included 130 healthy blood donors and 261 patients with 11 systemic autoimmune diseases (SAD). Disease activity was assessed using the Systemic Lupus Erythematosus Disease Activity Index (SLEDAI). A venous blood sample was drawn to measure three anti-chromatin antibodies [anti-nucleosome (anti-NCS), anti-double-stranded DNA (anti-dsDNA) and anti-histones (anti-HST)] by enzyme-linked immunosorbent assay.

RESULTS

The prevalence of anti-chromatin antibodies in SLE patients and healthy controls was 100 and 3% respectively for anti-NCS, 63 and 5% for anti-dsDNA, and 15 and 3% for anti-HST. Anti-NCS had a sensitivity of 100% and specificity of 97% for SLE diagnosis. When SLE and SAD patients were compared [excluding mixed connective tissue disease (MCTD)], the sensitivity of anti-NCS, anti-dsDNA and anti-HST antibodies for SLE diagnosis was 93, 71 and 40% respectively and the specificity was 97, 98 and 98%. Anti-chromatin antibodies were not useful in differentiating between SLE and MCTD patients. Anti-NCS antibodies showed the highest correlation with disease activity (r = 0.45, P < 0.0001), especially in patients negative for anti-dsDNA antibodies (r = 0.58, P = 0.001). Anti-NCS antibodies also showed strong association with renal damage (odds ratio 4.1, 95% confidence interval 1.2-13.6, P = 0.01).

CONCLUSION

Anti-NCS antibodies could be a useful tool in the diagnosis and assessment of disease activity in SLE patients, especially in patients who are negative for anti-dsDNA antibodies.

[Orthotopic liver transplant in rats. Surgical technique, complications and treatment]

The orthotopic rat liver transplant model is a widely used technique in transplantation research. It has many advantages over other animal transplant models because of its availability and low cost. However, it must be emphasized that success with the rat model requires thorough training. The aim of this paper is to describe the microsurgical technique involved in 60 rat liver transplants and to discuss the complications and their treatments. Forty-nine liver transplants were performed at the Experimental Laboratory of the University Hospital, Ontario, Canada (ELUH) and 11 were performed at the Laboratorio de Trasplante de Organos de la Facultad de Ciencias Médicas de La Plata, Buenos Aires. Argentina (LTO). Among the transplants performed at the ELUH, the observed complications were haemorrhage (n = 4), pneumothorax (n = 1), anastomotic failure (n = 15), bile leak (n = 3), and bile duct necrosis (n = 9). The remaining 17 rats at the ELUH were healthy at day 7 after surgery. Animal survival immediately postop, at 24 hours postop and at 7 days postop was achieved with the 9th, 20th and 21st transplants respectively. At the LTO, 3 rats died as a result of anaesthetic complications. Seven-day animal survival was achieved with the 11th transplant. We beleive that the description of the orthotopic rat liver transplantation technique, as well as the discussion regarding complications and their management, can be useful for researchers interested in performing liver transplantation in rats.

Basic statistics of PM2.5 and PM10 in the atmosphere of Mexico City

The high levels of fine particulate matter in Mexico City are of concern since they may induce severe public health effects as well as the attenuation of visible light. Sequential filter samplers were used at six different sites from 23 February to 22 March 1997. The sampling campaign was carried out as part of the project 'Investigación sobre Materia Particulada y Deterioro Atmosferico-Aerosol and Visibility Evaluation Research'. This research was a cooperative project sponsored by PEMEX and by the US Department of Energy. Sampling sites represent the different land uses along the city, the northwest station, Tlalnepantla, is located in a mixed medium income residential and industrial area. The northeast station, Xalostoc, is located in a highly industrialized area, Netzahualcoyotl is located in a mixed land use area, mainly commercial and residential. Station La Merced is located in the commercial and administrative district downtown. The southwest station is located in the Pedregal de San Angel, in a high-income neighborhood, and the southeast station located in Cerro de la Estrella is a mixed medium income residential and commercial area. Samples were collected four times a day in Cerro de la Estrella (CES), La Merced (MER) and Xalostoc (XAL) with sampling periods of 6 h. In Pedregal (PED), Tlalnepantla (TLA) and Netzahualcoyot1 (NEZ) sampling periods were every 24 h. In this paper the basic statistics of PM2.5 and PM10 mass concentrations are presented. The average results showed that 49, 61, 46, 57, 51 and 44% of the PM10 consisted of PM2.5 for CES, MER, XAL, PED, TLA and NEZ, respectively. The 24-h average highest concentrations of PM25 and PM10 were registered at NEZ (184 and 267 microg/m3) and the lowest at PED (22 and 39 microg/m3). The highest PM10 correlations were between XAL-CES (0.79), PED-TLA (0.80). In contrast, the highest PM2.5 correlations were between CES-PED (0.74), MER-CES (0.73) and TLA-PED (0.72), showing a lower correlation than the PM10 one. The results of the PM10 from 12.00 to 18.00 h at CES and MER presented the highest variability and also the highest median concentrations, meanwhile XAL showed them from 06.00 to 12.00 h. The highest variability and median concentrations of PM2.5 were from 06.00 to 12.00 h for the three stations.

Personal exposure to benzene, toluene and xylene in different microenvironments at the Mexico City metropolitan zone

The Mexico City Metropolitan Zone (ZMCM) population's exposure to benzene, toluene and xylene was measured at different microenvironments to establish basic indicators of the presence and effects of these characteristic volatile organic compounds (VOC). In particular, VOC personal exposures were measured in different microenvironments during a 5-day working week, with 12-h daily periods. We have found a good agreement of our results with the registered VOC levels of the Metropolitan Automated Monitor System (RAMA) for the corresponding period. From our results, we expect to generate useful information to evaluate the health effects of these VOCs on exposed people.

Experimental measurement of the statistics of the scattered intensity from particles on surfaces

We analyze the statistics of the co-polarized and cross-polarized scattered intensity from a flat substrate contaminated with spherical particles including multiple scattering between them. Both Gaussian and non-Gaussian regimes are considered. In particular, we focus on both the cross-polarized component and the probability of detecting zeros in the cross-polarized intensity, P(Icross=0). As it is shown, the latter gives information about particle interaction and can be measured with higher accuracy than other statistical parameters. A theoretical model for P(Icross=0) is presented for spherical Rayleigh scatterers. An scattering experiment was carried out to verify this model.

Quantitative determination of the loop diuretic bumetanide in urine and pharmaceuticals by high-performance liquid chromatography with amperometric detection

A high-performance liquid chromatographic method with amperometric detection has been developed for the determination of the diuretic bumetanide using a microBondapak C18 column. The mobile phase consists of a 50:50 acetonitrile-water mixture containing 5mM KH2PO4-K2HPO4 (pH 4.0). The compound is monitored at +1350 mV with an amperometric detector equipped with a glassy carbon working electrode. A liquid-liquid or solid-liquid extraction is done prior to chromatographic analysis in order to avoid the interferences found in the urine matrix. The percentages of recovery obtained are 71%+/-1% for liquid-liquid extraction and 84.2%+/-0.7% for solid-liquid extraction. The method developed has a linear concentration range from 50 to 499 ng/mL with a reproducibility in terms of relative standard deviation of 1.73% and 3.85% for a concentration level of 70 ng/mL and 237 ng/mL, respectively, and a detection limit of 0.25 ng/mL (3:1 signal-to-noise ratio). The method is applied to the determination of bumetanide in pharmaceutical formulations and urine obtained from hypertensive patients and healthy volunteers after the ingestion of a therapeutic dose of Fordiuran (1 mg bumetanide).

Validity of the Agency for Healthcare Research and Quality clinical practice guidelines: how quickly do guidelines become outdated?

CONTEXT

Practice guidelines need to be up-to-date to be useful to clinicians. No published methods are available for assessing whether existing practice guidelines are still valid, nor does any empirical information exist regarding how often such assessments need to be made.

OBJECTIVES

To assess the current validity of 17 clinical practice guidelines published by the US Agency for Healthcare Research and Quality (AHRQ) that are still in circulation, and to use this information to estimate how quickly guidelines become obsolete.

DESIGN, SETTING, AND PARTICIPANTS

We developed criteria for defining when a guideline needs updating, mailed surveys to members of the original AHRQ guideline panels (n = 170; response rate, 71%), and searched the literature for evidence through March 2000 (n = 6994 titles yielding 173 articles plus 159 new guidelines on the same topics).

MAIN OUTCOME MEASURES

Identification of new evidence calling for a major, minor, or no update of the 17 guidelines; survival analysis of the rate at which guidelines became outdated.

RESULTS

For 7 guidelines, new evidence and expert judgment indicated that a major update is required; 6 were found to be in need of a minor update; 3 were judged as still valid; and for 1 guideline, we could reach no conclusion. Survival analysis indicated that about half the guidelines were outdated in 5.8 years (95% confidence interval [CI], 5.0-6.6 years). The point at which no more than 90% of the guidelines were still valid was 3.6 years (95% CI, 2.6-4.6 years).

CONCLUSIONS

More than three quarters of the AHRQ guidelines need updating. As a general rule, guidelines should be reassessed for validity every 3 years.

Value of limited necropsy in HIV-positive patients

We performed limited autopsy with histological examination of tissue cores obtained percutaneously using the Tru-Cut needle and the Jamshidi trocar in 150 adult HIV-positive patients. Data were compared retrospectively with the antemortem clinical diagnosis. Eighty-one percent of the patients were male, and 78% were intravenous drug users. Specimens were obtained from the brain, liver, lung, bone marrow, and kidney of most patients. The main findings included liver cirrhosis in 22 cases (associated with HCV infection in 81%), Pneumocystis carinii pneumonia in 21, Cytomegalovirus (CMV) infection in 19, Mycobacterium avium-intracellulaire (MAI) infection in 17, bacterial pneumonia in 14, tuberculosis in 12, and lymphoma in 13 cases. Forty-six (30.6%) patients had at least one clinical diagnosis that was confirmed by autopsy, i.e., there was 40.6% agreement between pre- and postmortem findings. Forty-six (30.6%) patients had at least one clinical diagnosis that was not confirmed at autopsy, whereas 41 (27.3%) had at least one AIDS-related or unrelated disease that was not suspected clinically. The results obtained by limited autopsy are principally comparable to those achieved by full necropsy, with the advantages of decreasing the contagious risk, saving cost and time, including a rapid final diagnosis, and easily obtaining the consent for postmortem examination so that necropsy studies may be performed on a larger number of patients, thus contributing to a better understanding of the spectrum of HIV infection in our environment.

[Antiganglioside antibodies: when, which and for what]

BACKGROUND

We report our experience in the study of antiganglioside antibodies and define their clinical value establishing associations between clinical syndromes and immunological findings.

METHODS

We analysed 275 sera: Guillain-Barré syndrome (GBS) (78), Miller-Fisher syndrome (MFS) (37), chronic inflammatory demyelinating polyneuroapthy (CIDP) (17), multifocal motor neuropathy (NMM) (42), chronic axonal mixed polyneuropathy (PNP) (54), amyotrophic lateral sclerosis (ALS) (28) and lower motor neuron disease (LMND) (17). We have studied the presence of IgG and IgM antibodies to 9 gangliosides using ELISA and TLC.

RESULTS

We have detected anti-GQ1b antibodies in 36/37 (97,3%) of patients with MFS, being undetectable after 4 weeks in 83%. A 34 % (26/78) of patients with GBS were positive for several antiganglioside specificities being GalGalNAc the most frequent (54%). Two out of three sera positive for GD1a corresponded to axonal Guillain-Barré. IgM class anti-GM1 antibodies were positive in 10/12 patients with MMN, while only a 3-9% of patients with ALS, CIDP, PNP and LMND presented antiganglioside antibodies.

CONCLUSIONS

Analysis of anti-GQ1b antibodies confirms the diagnosis of MFS, excluding other acute brainstem pathologies and, in this study, detection of anti-GD1a antibodies indicates axonal damage in GBS and suggest a worse prognosis. IgM anti-GM1 antibodies are only found in MMN. These findings confirm a disease specific correlation between specific neuropathies and antiganglioside antibodies clinically useful.

[Anti-GQ1b antibodies: usefulness of its detection for the diagnosis of Miller-Fisher syndrome]

BACKGROUND

To study the presence of anti-GQ1b antibodies as a tool for the diagnosis of Miller-Fisher syndrome (MFS).

PATIENTS AND METHOD

We studied 54 patients with probable diagnosis of MFS and 10 patients diagnosed as Guillain-Barré syndrome plus ophthalmoplegia (1 case), Bickerstaff's encephalitis (1 case), relapsing ophthalmoplegia (7 cases) and relapsing diplopia (1 case). Results were compared with 130 patients with other disimmune neuropathies. Antibodies were detected by ELISA and checked by thin layer chromatography. Campylobacter jejuni serology was studied using a complement fixation test.

RESULTS

Diagnosis of MFS was confirmed in 38 patients. A 97.3% were positive for GQ1b, being all negative for Campylobacter jejuni serology. A second test after 4-5 weeks of nadir was negative in 84.2% (16/19), concomitant with clinical recovery.

CONCLUSIONS

Anti-GQ1b antibodies are useful markers for the differential diagnosis of MFS, specially with some acute brainstem disorders. Testing must be performed during the first four weeks of clinical course. This correlation between the triad ataxia, arreflexia and ophthalmoplegia and anti-GQ1b antibodies confirms that they are highly specific of MFS.

Determination of the antihypertensive drug cilazapril and its active metabolite cilazaprilat in pharmaceuticals and urine by solid-phase extraction and high-performance liquid chromatography with photometric detection

A liquid chromatographic method with photometric detection for the determination of cilazapril and its active metabolite and degradation product cilazaprilat in urine and pharmaceuticals has been developed. The chromatographic method consisted of a microBondapak C18 column maintained at 30+/-0.2 degrees C, using a mixture of methanol-10 mM phosphoric acid (50:50 v/v) as mobile phase at a flow-rate of 1.0 ml/min. Enalapril maleate was used as internal standard. The detection was performed at a wavelength of 206 nm. A study of the retention of cilazapril and cilazaprilat using solid-liquid extraction has been carried out in order to optimise the clean-up procedure for urine samples, which consisted of a solid-liquid extraction using C(R) cartridges. Recoveries greater than 85% are obtained for both compounds. The method was sensitive, precise and accurate enough to be applied to the determination of urine samples obtained from three hypertensive patients up to 24 h after intake of a therapeutic dose (detection limit of 70 ng/ml for cilazapril and cilazaprilat in urine). A comparison of the method developed using photometric and amperometric detection has been carried out.

The role of clinical informatics in the Agency for Healthcare Research and Quality's efforts to improve patient safety

In 1998, the Institute of Medicine (IOM) issued a report on medical errors, which estimated that up to 98,000 people die in U.S. hospitals each year from errors. This report raised concerns that medical errors have become a national public health problem that should be addressed in the same manner as other epidemics such as heart disease, diabetes, and obesity. In 2001, the IOM released a follow-up report encompassing a broader range of quality issues. They concluded that the U.S. healthcare system is outmoded and incapable of providing consistent, high-quality care. They outlined a strategy for redesigning U.S. healthcare delivery to achieve safe, dependable, high-quality care, which emphasizes information technology as an integral part of the solution. AHRQ's fiscal year 2001 appropriation included an increase of $50 million dollars for initiatives to reduce medical errors and improve patient safety. AHRQ responded to this mandate by developing a series of research solicitations that form an integrated set of activities to design and test best practices for reducing errors in multiple health care settings. This paper discusses the components of this program and the central role of medical informatics research in the Agency's efforts to improve the safety of medical care in America.

Primary vaccination of infants with diphtheria-tetanus-acellular pertussis-hepatitis B virus- inactivated polio virus and Haemophilus influenzae type b vaccines given as either separate or mixed injections

OBJECTIVE

The aim of this open, multicenter, randomized trial was to evaluate the immunogenicity and reactogenicity of a candidate combined diphtheria-tetanus-acellular pertussis-hepatitis B virus-inactivated polio virus (DTaP-HBV-IPV) vaccine when given as either a mixed or as separate concomitant injections with Haemophilus influenzae type b (Hib) vaccine.

STUDY DESIGN

A total of 359 subjects were randomized to receive either DTaP-HBV-IPV/Hib (mixed administration - 180 subjects) or DTaP-HBV-IPV + Hib (separate administration in opposite limbs - 179 subjects) at 2, 3, and 4 months of age.

RESULTS

After vaccination, seroprotective antibody concentrations against diphtheria, tetanus, hepatitis B, and polio viruses and a high (> or = 97%) pertussis vaccine response were seen in almost all study participants. All subjects except one in the mixed administration group had postvaccination Hib anti-PRP antibody concentrations > or = 0.15 microg/mL. Of subjects in the mixed and separate group, 77.2% (geometric mean antibody concentration, 2. 62 microg/mL) and 88.6% (geometric mean antibody concentration, 4.45 microg/mL) had Hib anti-PRP concentrations > or = 1 microg/mL, respectively. The addition of the Hib component to the 5-component vaccine did not increase the incidence of local or general reactions.

CONCLUSION

Both administrations of the candidate vaccine were found to be safe, immunogenic, and well tolerated. Although anti-PRP geometric mean antibody concentrations and the percent of subjects achieving the 1 microg/mL seroprotective level were lower after the mixed administration, they were in the range seen with monovalent Hib vaccines or with other DTaP-based/Hib combinations licensed in some European countries. Therefore both administrations have the potential to simplify childhood immunization.