Development of a sensitive enzyme immunoassay for plasma and salivary steroids

The development of an enzyme-labelled immunoassay (EIA) of sufficient range and sensitivity for determination of plasma and salivary steroids is described. The method is based on competition in the solid phase. A fixed amount of a specific antibody is immobilized on polystyrene beads, its amount being enough to bind about 50% of a steroid-enzyme conjugate (covalently linked steroid Jhorseradish peroxidase conjugate). The initial incubation at 25 degrees of serum sample or extract with the conjugate in presence of the immobilized antibody is followed by washing and the addition of a substrate for measurement of the enzyme activity either colorimetrically by the H(2)O(2)/o-phenylenediamine method or by the luminescence reaction based on the use of H(2)O(2)/luminol. The method is precise and accurate (CV < 10% for both the intra- and inter-assay studies). The sensitivity of the colorimetric determination is similar to that of radioimmunoassay, but the luminescence method is more sensitive. Radioimmunoassay and EIA gave results in good agreement (r > 0.97). The method has also been applied to salivary steroids: the procedure is direct and only a few mu1 of saliva are required. The levels of these steroids in saliva are only about a tenth of those in serum but directly correlated with them (r > 0.85). The enzyme immunoassay proposed is sensitive and precise enough to measure these steroids accurately in saliva and plasma.

Spatial distributions of the red palm mite, Raoiella indica (Acari: Tenuipalpidae) on coconut and their implications for development of efficient sampling plans

The red palm mite (Raoiella indica), an invasive pest of coconut, entered the Western hemisphere in 2004, then rapidly spread through the Caribbean and into Florida, USA. Developing effective sampling methods may aid in the timely detection of the pest in a new area. Studies were conducted to provide and compare intra tree spatial distribution of red palm mite populations on coconut in two different geographical areas, Trinidad and Puerto Rico, recently invaded by the mite. The middle stratum of a palm hosted significantly more mites than fronds from the upper or lower canopy and fronds from the lower stratum, on average, had significantly fewer mites than the two other strata. The mite populations did not vary within a frond. Mite densities on the top section of the pinna had significantly lower mite densities than the two other sections, which were not significantly different from each other. In order to improve future sampling plans for the red palm mite, the data was used to estimate the variance components associated with the various levels of the hierarchical sampling design. Additionally, presence-absence data were used to investigate the probability of no mites being present in a pinna section randomly chosen from a frond inhabited by mites at a certain density. Our results show that the most precise density estimate at the plantation level is to sample one pinna section per tree from as many trees as possible.

Host plant range of Raoiella indica (Acari: Tenuipalpidae) in areas of invasion of the New World

Raoiella indica has spread rapidly through the Neotropical region where the mite damages economically and ecologically important plants. Three studies were conducted to determine the host plant range of R. indica, using the presence of colonies containing all life stages as an indicator of reproductive suitability. Periodic surveys at the Fairchild Tropical Botanic Garden (Miami Dade County, FL, USA) and the Royal Botanical Gardens (Port of Spain, Trinidad and Tobago) identified 27 new reproductive host plants. The reproductive suitability of two dicotyledonous species and three native Florida palm species was examined. An updated list of reproductive host plants of R. indica is presented. All reported reproductive hosts (91 plant species) of R. indica are monocots from the orders Arecales (Arecaceae), Zingiberales (Heliconiaceae, Musaceae, Strelitziaceae, Zingiberaceae) and Pandanales (Pandanaceae). Most are palms of the family Arecaceae that originated in areas of the Eastern Hemisphere; about one fourth of the reported hosts are native to the New World and could be considered new host associations of R. indica. Six years after the initial detection in the Caribbean, R. indica has expanded its host plant range. Here we report 27 new reproductive host of R. indica that represent 30% of increase on previous host plant records. As this mite continues spreading in the Neotropical region a great diversity of plants is potentially affected.

MassUntangler: a novel alignment tool for label-free liquid chromatography-mass spectrometry proteomic data

Liquid chromatography-mass spectrometry (LC-MS) has become an important analytical tool for quantitative proteomics and biomarker discovery. In the label-free differential LC-MS approach computational methods are required for an accurate alignment of peaks extrapolated from the experimental raw data accounting for retention time and m/z signals intensity, which are strongly affected by sample matrix and instrumental performance. A novel procedure "MassUntangler" for pairwise alignment has been developed, relying on a pattern-based matching algorithm integrated with filtering algorithms in a multi-step approach. The procedure has been optimized employing a two-step approach. Firstly, low-complexity LC-MS data derived from the enzymatic digestion of two standard proteins have been analyzed. Then, the algorithm's performance has been evaluated by comparing the results with other achieved using state-of-the-art alignment tools. In the second step, our algorithm has been used for the alignment of high-complexity LC-MS data consisting of peptides obtained by an Escherichia coli lysate available from a public repository previously used for the comparison of other alignment tools. MassUntangler gave excellent results in terms of precision scores (from 80% to 93%) and recall scores (from 68% to 89%), showing performances similar and even better than the previous developed tools. Considering the mass spectrometry sensitivity and accuracy, this approach allows the identification and quantification of peptides present in a biological sample at femtomole level with high confidence. The procedure's capability of aligning LC-MS data previously corrected for distortion in retention time has been studied through a hybrid approach, in which MassUntangler was interfaced with the OpenMS TOPP tool MapAligner. The hybrid aligner yielded better results, showing that an integration of different bioinformatic approaches for accurate label-free LC-MS data alignment should be used.

A new gastric-emptying mouse model based on in vivo non-invasive bioluminescence imaging

BACKGROUND

Different techniques were used to assess gastric emptying (GE) in small animals; most of them require sophisticated equipment, animal sacrifice and are expensive. In the present investigation a simple, non-invasive method based on bioluminescence imaging (BLI) is reported to study GE, using light-emitting Escherichia coli cells as a marker of the gastric content.

METHODS

A new thermostable red-emitting luciferase was chosen as reporter gene to transform E. coli cells. Bioluminescent (BL) bacteria were administered to fasting mice, after a solid meal, and in response to different doses of metoclopramide (MET) and hyoscine butylbromide (HY). Bioluminescence imaging allowed to evaluate the real time 2D spatial and temporal distribution of bacteria along the gastrointestinal tract in animals and to calculate GE rate in basal conditions and following pharmacological stimulation.

KEY RESULTS

  The administered BL bacteria were easily imaged and localized in the stomach and subsequently followed in the duodenum and upper intestine allowing to accurately calculate GE. Gastric emptying after the test meal was significantly slower (T(1/2) 16 ± 3 min) than that obtained in fasting conditions (T(1/2) 2 ± 1 min); administration of HY (1 mg kg(-1) b.w.) significantly (P < 0.05) increased T(1/2) that was delayed up to 25 ± 4 min; MET (1 mg kg(-1) b.w.) significantly (P < 0.05) accelerated T(1/2), that was achieved within 8 ± 2 min.

CONCLUSION & INFERENCES

The reported model is simple, inexpensive, reliable, sensitive and accurate; it can detect both acceleration and slowdown of GE. The model is useful in the investigation of new drug-induced alterations of gastric motility allowing to reduce the number of experimental animals.

Development and validation of a HPLC-ES-MS/MS method for the determination of glucosamine in human synovial fluid

A new HPLC method for the determination of glucosamine (2-amino-2-deoxy-D-glucose) in human synovial fluid was developed and validated. Synovial fluid samples were analyzed after a simple protein precipitation step with trichloroacetic acid using a polymer-based amino column with a mobile phase composed of 10 mM ammonium acetate (pH 7.5)-acetonitrile (20:80, v/v) at 0.3 mL/min flow rate. D-[1-13C]glucosamine was used as internal standard. Selective detection was performed by tandem mass spectrometry with electrospray source, operating in positive ionization mode and in multiple reaction monitoring acquisition (m/z 180-->72 and 181-->73 for glucosamine and internal standard, respectively). The limit of quantification (injected volume=3 microL) was 0.02 ng, corresponding to 10 ng/mL in synovial fluid. Calibration curves obtained using matrix-matched calibration standards and internal standard at 600 ng/mL were linear up to 2000 ng/mL. Precision values (%R.S.D.) were < or = 14% in the entire analytical range. Accuracy (%bias) ranged from -11% to 10%. The recoveries measured at three concentration levels (50, 800, and 1500 ng/mL) were higher than 89%. The method was successfully applied to measure endogenous glucosamine levels in synovial fluid samples collected from patients with knee osteoarthritis and glucosamine levels after oral administration of glucosamine sulfate (DONA) at the dose of 1500 mg/day for 14 consecutive days (steady-state).

Multiplex chemiluminescence microscope imaging of P16(INK4A) and HPV DNA as biomarker of cervical neoplasia

Classification of cervical intraepithelial neoplasia (CIN) lesions in low-grade (CIN1) or high-grade (CIN2-3) ones is crucial for optimal patient management, but current histological diagnosis on bioptic samples is often hampered by inter-observer variability. To allow objective classification, we have exploited the peculiar characteristics of chemiluminescence detection, such as high sensitivity and easy quantification of the luminescence signal, to perform sequentially in the same tissue section both an immunohistochemical quantitative detection of p16(INK4A) (a protein marker of high-grade CIN lesions) and an in situ hybridization for human papillomavirus (generally accepted as a necessary but insufficient cause of cervical carcinoma). Different label enzymes (alkaline phosphatase and horseradish peroxidase) were employed in order to avoid any interference between the two assays, and quantitative chemiluminescence image analysis was used to obtain objective evaluation of sample positivity. The multiplexed method allowed detection of two complementary biomarkers and provided discrimination between different lesions (non-neoplastic, low-grade and high-grade CIN). This assay might thus represent an accurate and objective diagnostic test providing important information for counseling, selection of therapy and follow up after surgical treatment.

Synovial and plasma glucosamine concentrations in osteoarthritic patients following oral crystalline glucosamine sulphate at therapeutic dose

OBJECTIVE

We investigated the synovial and plasma glucosamine concentrations in osteoarthritic patients following oral administration of crystalline glucosamine sulphate at the therapeutic dose of 1500mg once-a-day for 14 days.

DESIGN

Twelve osteoarthritic patients (six males and six females) received 14 consecutive once-daily oral administrations of crystalline glucosamine sulphate soluble powder (1500mg), in an open fashion. Plasma and synovial fluid were collected simultaneously from the same patient, at baseline and, at steady state (3h after the last dose). Glucosamine was determined in plasma and synovial fluid by liquid chromatography-tandem mass spectrometry.

RESULTS

Median endogenous glucosamine concentrations in plasma and synovial fluid were 52.0ng/ml (0.29microM) and 36.5ng/ml (0.21microM), respectively (P=0.001), and varied substantially among patients (41-121ng/ml and <10-67ng/ml, respectively). Three hours after the last dose, glucosamine concentrations resulted increased from baseline in all patients with median increases of 20.5 and 21.5 folds in plasma and synovial fluid, respectively, the difference being not statistically significant (P=0.11). In plasma, the median post-treatment value was 1282ng/ml (7.17microM) and ranged from 600 to 4061ng/ml (3.35-22.7microM). The median post-treatment synovial glucosamine concentration was 777ng/ml (4.34microM), i.e., significantly lower than in plasma (P=0.001), and ranged from 577 to 3248ng/ml (3.22-18.1microM). Plasma and synovial glucosamine concentrations were highly correlated and were in the 10microM range.

CONCLUSIONS

Glucosamine is bioavailable both systemically and at the site of action (the joint) after oral administration of crystalline glucosamine sulphate in ostaeoarthritis patients. Steady state glucosamine concentrations in plasma and synovial fluid were correlated and in line with those effective in selected in vitro studies.

Assessment of the presence of mucosal human papillomaviruses in malignant melanomas using combined fluorescent in situ hybridization and chemiluminescent immunohistochemistry

BACKGROUND

The vast majority of studies aimed at detecting human papillomavirus (HPV) DNA in skin cancer have used sensitive polymerase chain reaction (PCR) methods but the PCR technique, despite its high sensitivity, is not suitable to ascertain whether (i) the presence of HPV can be related only to few cells harbouring the virus, (ii) the presence of HPV is due to a tumour surface contamination and (iii) the presence of HPV is localized in cancer cells, rather than in normal keratinocytes present in the tumour biopsy. In a recent work we have found mucosal high-risk (HR) HPV genotypes in primary melanoma by PCR.

OBJECTIVES

To localize mucosal HR-HPV nucleic acids and tumoural melanocytic marker in the same sections of primary melanoma samples in order to understand the relationship between HPVs and melanoma cells.

METHODS

We have developed a very sensitive method that combines an enzyme-amplified fluorescent in situ hybridization (ISH) for the detection of HPV nucleic acids (types 16 and 18) with a chemiluminescent immunohistochemistry (IHC) method for the detection of the tumoural melanocytic marker HMB-45 sequentially in the same section. Digital images of fluorescent ISH and chemiluminescent IHC were separately recorded, assigned different colours and merged using specific software for image analysis.

RESULTS

The combined fluorescent ISH and chemiluminescent IHC demonstrated a sharp colocalization (in the range 60-80%) of HPV nucleic acids and melanoma marker inside the same sections of melanoma biopsies, with a strong specificity and sensitivity.

CONCLUSIONS

The strong colocalization of mucosal HR-HPV nucleic acids and HMB-45 melanocytic marker emphasized that viral nucleic acids were specifically present in melanoma cells and supported a possible active role of HPV in malignant melanoma.

Molecular adsorbent recirculating system (MARS) application in liver failure: clinical and hemodepurative results in 22 patients

PURPOSE

Acute liver failure (ALF) and acute on chronic liver failure (ACLF) still show a poor prognosis. MARS was used in 22 patients with ALF or ACLF to prolong patient survival for liver function recovery or as a bridge to transplantation.

DESIGN

Evaluation of depurative efficiency, biocompatibility, hemodynamics, encephalopathy (HE) and clinical outcome.

PROCEDURES

During 71 five-hour sessions we evaluated (0', 60', 120', 180', 240', 300'): bilirubin, ammonia, cholic acid (CCA), chenodeoxycholic acid (CCDCA), leukocytes, platelets, hemoglobin and mean arterial pressure (MAP). Serum creatinine, electrolytes, cardiac output, cardiac index (bioimpedence) and HE (West Haven Criteria score) were evaluated at 0' and 300'. STATISTICAL METHODS AND OUTCOME MEASURES: Student's t-test for pre- vs. end-session values was used. For bilirubin and ammonia the correlation test was made between pre- and end-session values and between pre-session values and removal rates (RRS).

MAIN FINDINGS

Survival was 90.9% at 7 days, 40.9% at 30 days. Pre- vs. end-session: bilirubin from 37.2 +/- 12.5 mg/dL to 24.9 +/- 8.9 mg/dL (p < 0.01), ammonia from 88.0 +/- 60.4 micromol/L to 43.6 +/- 32.9 micromol/L (p < 0.01), CCA from 42.8 +/- 21.0 micromol/L 18.2 +/- 9.8 micromol/L (p < 0.01), CCDCA from 26.3 +/- 6.3 micromol/L to 15.7+/-7.6 micromol/L (p<0.01). The correlation test between pre-session values of bilirubin and ammonia vs. RR S was respectively 0.32 (p = 0.01) and 0.30 (p = 0.04). Leukocytes, platelets and hemoglobin remained stable. MAP increased from 82.0 +/- 12.0 mmHg to 87.0 +/- 13.0 mmHg (p < 0.05), West Haven Criteria score decreased from 2.7 +/- 0.7 to 0.7 +/- 0.7 (p < 0.001).

CONCLUSION

MARS treatment led in all patients to an improvement of clinical, hemodynamic and neurological conditions, with significant reduction in the hepatic toxins blood level. Treatment biocompatibility and tolerance were satisfactory.

Production and characterisation of monoclonal antibodies specific for Escherichia coli O157:H7

Seven monoclonal antibodies (MAbs) specific for Escherichia coli O157:H7, one of the major causes of haemorrhagic colitis in humans, were produced by immunising Balb/c mice with the strain E. coli O157:H7. These monoclonal antibodies do not cross-react with other bacteria such as Salmonella enterica serovar Typhimurium, E. coli O14, E. coli JM109, S. enterica serovar Enteritidis, S. panama, S. saintpaul, S. derby, S. muenchen, S. bredeney, S. hadar, Yersinia enterocolitica, Proteus vulgaris, Shigella flexneri, Listeria ivanovii, L. monocytogenes 13M, L. innocua, Enterobacter cloacae, E. agglomerans, E. amnigenus, Citrobacter freundii, Escherichia fergussoni or Klebsiella pneumoniae. Of the seven MAbs obtained, MAb 8B8C3 was selected to prepare a high-sensitivity sandwich ELISA method specific for O157:H7.

Olfactory Discrimination among Sex Pheromone Stereoisomers: Chirality Recognition by Pink Hibiscus Mealybug Males

Our previous field studies suggested that the two chiral centers in the sex pheromone of pink hibiscus mealybug, Maconellicoccus hirsutus, could elicit different male responses. The chiral center in the acid moiety of the pheromone seemed to be more critical than the alcohol portion of the pheromone molecule for attractiveness. The objective of the current study was to test this hypothesis by deploying stereoisomeric blends in pheromone traps. Captures of male M. hirsutus showed that pheromone with the naturally occurring (R)-maconelliyl (S)-2-methylbutanoate and (R)-lavandulyl (S)-2-methylbutanoate [R-S configuration] was most attractive and that pheromone with the unnatural S-S configuration was less attractive. In addition, the RS-R blend (containing R-R and S-R stereoisomers) yielded captures of male M. hirsutus that were comparable to blank controls, and an inhibitory effect was observed when R-R and S-R were combined with naturally occurring R-S blend. These results suggest a unique chirality recognition mechanism; olfactory discrimination among different pheromone stereoisomers depends upon both asymmetric centers. The S configuration on the acid moiety elicits attraction, whereas the R configuration induces inhibition. However, the attractive activity shows some degree of tolerance toward chirality change in the alcohol portion of the pheromone molecules.

Development and validation of a sensitive and fast chemiluminescent enzyme immunoassay for the detection of genetically modified maize

Proteins from the Cry 1 family, in particular Cry 1Ab, are commonly expressed in genetically modified Bt maize in order to control chewing insect pests. A sensitive chemiluminescent sandwich enzyme immunoassay for the detection of Cry1Ab protein from genetically modified Bt maize has been developed and validated. A Cry1Ab protein-specific antibody was immobilized on 96- or 384-well microtiter plates in order to capture the Cry1Ab toxin in the sample; the bound toxin was then detected by employing a second anti-Cry1Ab antibody and a horseradish peroxidase-labeled anti-antibody, followed by measurement of the enzyme activity with an enhanced chemiluminescent system. The chemiluminescent assay fulfilled all the requirements of accuracy and precision and exhibited limits of detection of a few pg mL(-1) Cry1Ab (3 or 5 pg mL(-1), depending on the assay format), which are significantly lower than that achievable using conventional colorimetric detection of peroxidase activity and also represent an improvement compared to previously developed Cry1Ab immunoassays. High-throughput analysis can be performed using the 384-well microtiter plate format immunoassay, which also allows one to reduce the consumption of samples and reagents. Validation of the assay, performed by analyzing certified reference materials, proved that the immunoassay is able to detect the presence of the Cry1Ab protein in certified reference samples containing as low as 0.1% of MON 810 genetically modified Bt maize. This value is below the threshold requiring mandatory labeling of foods containing genetically modified material according to the actual EU regulation.

Glucosamine oral bioavailability and plasma pharmacokinetics after increasing doses of crystalline glucosamine sulfate in man

OBJECTIVE

Pharmacokinetic data on glucosamine are scant, limiting the understanding of glucosamine sulfate mechanism of action in support of its treatment effects in osteoarthritis. This study investigated the oral pharmacokinetics and dose-proportionality of glucosamine after administration of the patented crystalline glucosamine sulfate in man.

METHODS

Twelve healthy volunteers received three consecutive once-daily oral administrations of glucosamine sulfate soluble powder at the doses of 750, 1,500, and 3,000 mg, in an open, randomised, cross-over fashion. Glucosamine was determined in plasma collected up to 48 h after the last dose by a validated Liquid Chromatography method with Mass Spectrometry detection. Pharmacokinetic parameters were calculated at steady state.

RESULTS

Endogenous plasma levels of glucosamine were detected (10.4-204 ng/ml, with low intra-subject variability). Glucosamine was rapidly absorbed after oral administration and its pharmacokinetics were linear in the dose range 750-1,500 mg, but not at 3,000 mg, where the plasma concentration-time profiles were less than expected based on dose-proportionality. Plasma levels increased over 30-folds from baseline and peaked at about 10 microM with the standard 1,500 mg once-daily dosage. Glucosamine distributed to extravascular compartments and its plasma concentrations were still above baseline up to the last collection time. Glucosamine elimination half-life was only tentatively estimated to average 15 h.

CONCLUSIONS

Glucosamine is bioavailable after oral administration of crystalline glucosamine sulfate, persists in circulation, and its pharmacokinetics support once-daily dosage. Steady state peak concentrations at the therapeutic dose of 1,500 mg were in line with those found to be effective in selected in vitro mechanistic studies. This is the only glucosamine formulation for which pharmacokinetic, efficacy and safety data are now available.

Individual variability in herbivore-specific elicitors from the plant's perspective

Lepidopteran larvae oral secretions and regurgitant (R), which contain a plethora of potential elicitors, are known to dramatically change a plant's wound response. We demonstrate, with a detailed microarray and secondary metabolite analysis, that the two most abundant fatty acid-amino acid conjugates (FACs) in the R of the specialist herbivore Manduca sexta (Lepidoptera, Sphingidae) can account for all measured direct (trypsin proteinase inhibitor: TPI) and indirect (cis-alpha-bergamotene) defences, the endogenous jasmonic acid burst that elicits them, and 86% of the induced transcriptional changes (89% up and 83% down) in its native host Nicotiana attenuata and hence are necessary and sufficient for the Manduca-specific modulation of the wound response. FACs were not found in eggs, but detected in larvae of all instars after their first meal. FACs were found in all regions of the alimentary canal and in the frass, but did not occur in salivary or mandibular glands, extracts of which were not active in any assay. Individual larvae differed substantially in their FAC composition and two FAC chemotypes were discernible: N-linolenoyl-L-glutamine biased R and N-linolenoyl-L-glutamate biased R. We created synthetic blends of FACs to mimic these chemical phenotypes and determined whether plants respond differently to the different R chemotypes. Micorarray and TPI analysis revealed that plants do not differentiate. N. attenuata plants use FACs from feeding caterpillars to tailor their wound responses but do not use the variability in FAC ratios to recognize attack from an individual caterpillar.

Pharmacokinetics and bioavailability of four modified-release ursodeoxycholic acid preparations for once-a-day administration

Ursodeoxycholic acid (UDCA) is currently used for the treatment of cholestatic liver disease and for cholesterol gallstone dissolution. Various formulations have been designed to enhance its intestinal absorption or to improve patient compliance through once-a-day administration. The pharmacokinetics and bioavailability of four commercially available modified-release UDCA formulations (450 mg) were studied in 12 healthy subjects randomly receiving the four drugs under study. Serum samples were collected hourly for a 12-h period after administration and UDCA concentrations were measured using a specific enzyme immunoassay. For each formulation, Cmax, tmax, and the area under the curve (AUC) were determined and compared. Although all formulations were designed to provide sustained release, we observed different pharmacokinetics among the studied formulations. One of the formulations (sustained-release ursodeoxycholic acid Ratiopharm 450 mg tablets) showed high bioavailability, but failed to produce sustained release. In contrast, two other formulations (modified-release ursodeoxycholic acid Dorom 450 mg capsules and controlled-release Ursobil HT 450 mg capsules) provided sustained release, but did not offer efficient bioavailability. A fourth formulation (Ursilon retard 450 mg) exhibited gradual UDCA release lasting over 10 h, with efficient bioavailability, similar to that of conventional prompt-release formulations administered at the same dose. These data highlight the variability of commercially available sustained-release formulations. Manufacturers should be encouraged to provide drug kinetics and bioavailability data to further support the claimed pharmacokinetics.