QuantiFERON®-TB Gold In-Tube reliability for immigrants with parasitic infections in Boston, USA

<sec id="st1"> <title>SETTING</title> Accurate testing and treatment for latent tuberculous infection is necessary for tuberculosis elimination. Certain parasite infections are associated with increased tuberculin skin test positivity; species-specific effects on QuantiFERON^®-TB Gold In-Tube (QGIT) have not been described. </sec> <sec id="st2"> <title>OBJECTIVE</title> To determine whether infection with helminths or protozoa affects QGIT results. </sec> <sec id="st3"> <title>DESIGN</title> We retrospectively analyzed QGIT and parasite testing results for immigrants screened in Boston, MA, USA, from 2012 to 2017. We also prospectively measured cytokines in QGIT supernatants for a subset (n = 68) with 1) helminths, 2) Blastocystis hominis, 3) other protozoa, and 4) no parasites. </sec> <sec id="st4"> <title>RESULTS</title> Of 527 immigrants screened, 141 (26.8%) were QGIT-positive and 229 (43.4%) had parasites detected: 27/527 (5.1%) had helminths and 202/527 (38.3%) protozoa. Cytokine analysis revealed increased interleukin-10 concentrations with protozoa (P = 0.04), and non-significantly higher T-helper 2 concentrations with helminths compared with no parasites. No significant differences emerged in QGIT positivity or interferon-gamma concentrations in any group. </sec> <sec id="st5"> <title>CONCLUSION</title> Study results support the use of QGIT in parasite-endemic settings. </sec>.

International Validation Study for the Determination of Chloramphenicol in Bovine Muscle

A gas chromatographic (GC) procedure for the quantitation and GC/negative ion chemical ionization mass spectrometric (NICIMS) confirmation of chloramphenicol in calf muscle tissue was the subject of a validation study. Five analysts representing 5 laboratories in 4 countries participated in the quantitative method and analyzed 7 randomly numbered blind triplicates at 4 fortified and 3 incurred tissue concentrations on 3 separate days. The chloramphenicol concentrations ranged from 0 to 2.5 ppb. All data were reported to 3 significant figures. The coefficients of variation were 9.5-28.7% for repeatability and 14.6-38% over the study range for reproducibility. NICIMS data representing 3 laboratories in 3 countries successfully confirmed chloramphenicol in samples at 0.6 ppb or greater with no false positives in blank tissues.

Chlortetracycline, Oxytetracycline, and Tetracycline in Edible Animal Tissues, Liquid Chromatographic Method: Collaborative Study

Thirteen laboratories analyzed samples of edible animal tissues for tetracycline residues. The method included extraction of analytes into buffer, elution from a C18 solid-phase extraction (SPE) cartridge, and reversed-phase liquid chromatographic (LC) analysis, including use of a confirmation column. An additional laboratory, using an alternative LC assay based on a different sample cleanup, also analyzed the samples. Results showed the 2 methods are comparable. The LC method for determination of cholortetracycline, oxytetracycline, and tetracycline in edible animal tissues has been adopted by AOAC INTERNATIONAL. Results from 13 laboratories indicate that the method under study provides generally better results at the higher concentrations tested than at concentrations near the detection limit and that there is less problem with interferences in muscle tissue than in kidney. The method can achieve reliable results for analytes and matrixes studied at concentrations from 0.1 to 0.6 ppm and above, depending on the analyte-matrix combination, with generally better performance to be expected with muscle than with kidney. The poorer performance for fortified samples, particularly kidney, was attributed to additional homogenization steps required to prepare these samples. Recovery of analytes from different

Chlortetracycline, oxytetracycline, and tetracycline in edible animal tissues, liquid chromatographic method: collaborative study

Thirteen laboratories analyzed samples of edible animal tissues for tetracycline residues. The method included extraction of analytes into buffer, elution from a C18 solid-phase extraction (SPE) cartridge, and reversed-phase liquid chromatographic (LC) analysis, including use of a confirmation column. An additional laboratory, using an alternative LC assay based on a different sample cleanup, also analyzed the samples. Results showed the 2 methods are comparable. The LC method for determination of cholortetracycline, oxytetracycline, and tetracycline in edible animal tissues has been adopted by AOAC INTERNATIONAL. Results from 13 laboratories indicate that the method under study provides generally better results at the higher concentrations tested than at concentrations near the detection limit and that there is less problem with interferences in muscle tissue than in kidney. The method can achieve reliable results for analytes and matrixes studied at concentrations from 0.1 to 0.6 ppm and above, depending on the analyte-matrix combination, with generally better performance to be expected with muscle than with kidney. The poorer performance for fortified samples, particularly kidney, was attributed to additional homogenization steps required to prepare these samples. Recovery of analytes from different lots of solid-phase extraction (SPE) cartridges was an important variable.

Relative effectiveness of topical ketorolac and topical diclofenac on discomfort after radial keratotomy

Two prospective, randomized, double-masked studies were conducted evaluating the analgesic effect of topical eyedrops after radial keratotomy (RK). One study of 117 consecutive initial RK procedures compared topical ketorolac (Acular) with topical diclofenac (Voltaren), and another study of 23 consecutive initial RK procedures compared topical ketorolac with a control medication (HypoTears). Topical ketorolac was significantly more effective than the control but not significantly different from topical diclofenac. The onset of analgesic effect of these topical nonsteroidal anti-inflammatory drugs is longer than one hour. The analgesic effect of oral acetaminophen #3 significantly augments that of topical diclofenac drops for those experiencing any discomfort by six hours after surgery.

Effect of topical diclofenac solution on discomfort after radial keratotomy

The eyes of 65 consecutive radial keratotomy patients were treated topically with either diclofenac sodium 0.1% (Voltaren) solution or with Tears Naturale (control group) preoperatively and postoperatively in a prospective, randomized, double-masked study. During the first postoperative day, patients completed a questionnaire on discomfort level present at 15 minutes and at one, three, six, and 18 hours after surgery. Patients treated with topical diclofenac were generally more comfortable than patients in the control group. They had a significantly lower rate of "moderate" or "severe" discomfort and a higher rate of less than "mild" discomfort. Peak discomfort occurred at three hours in both groups. The prescribed optional oral analgesic was taken by 48.5% of patients in the diclofenac group and by 71.9% of those in the control group.

International validation study for the determination of chloramphenicol in bovine muscle

A gas chromatographic (GC) procedure for the quantitation and GC/negative ion chemical ionization mass spectrometric (NICIMS) confirmation of chloramphenicol in calf muscle tissue was the subject of a validation study. Five analysts representing 5 laboratories in 4 countries participated in the quantitative method and analyzed 7 randomly numbered blind triplicates at 4 fortified and 3 incurred tissue concentrations on 3 separate days. The chloramphenicol concentrations ranged from 0 to 2.5 ppb. All data were reported to 3 significant figures. The coefficients of variation were 9.5-28.7% for repeatability and 14.6-38% over the study range for reproducibility. NICIMS data representing 3 laboratories in 3 countries successfully confirmed chloramphenicol in samples at 0.6 ppb or greater with no false positives in blank tissues.

Tissue sulfonamide concentration and correlation in turkeys

Nineteen hen turkeys (10 to 12 kg each) were used in a feeding study to determine sulfadimethoxine and sulfaquinoxaline concentrations in blood serum, liver, and skeletal muscle, as well as the respective ratios at selected withdrawal intervals. Two feeds were prepared by use of premixes to achieve 60 mg of sulfadimethoxine/kg and 100 mg of sulfaquinoxaline/kg, respectively. Each of the medicated feeds was given to 9 turkeys for 7 days. The turkeys were then fed nonmedicated feed at intervals from 24 to 56 hours and were slaughtered. One turkey was used as control. The serum/liver and serum/muscle ratios for sulfaquinoxaline were 60 to 70% higher than for sulfadimethoxine. However, the liver/muscle ratio for both sulfonamides was equivalent, approximately 3. Disposition of both sulfonamides approximated first-order pharmacokinetics. The calculated half-life of sulfadimethoxine was half that of sulfaquinoxaline, approximately 16 vs 30 hours. The coefficients of variation in the serum/tissue ratios for both sulfonamides were between 13% and 25% for serum/liver and less than 15% for serum/muscle, indicating excellent potential for using serum as a predictor of actionable concentrations of sulfonamide residues.

Determination of melengestrol acetate in bovine tissues by automated coupled-column normal-phase high-performance liquid chromatography

A method has been developed for the determination of melengestrol acetate in bovine tissues at lower levels than previously reported. Liquid-liquid extraction of tissue homogenates provided crude clean-up while final isolation, screening, and quantification was done on-line with an automated, normal-phase, coupled-column high-performance liquid chromatographic system. The chromatographic system included phenyl and silica analytical columns for the purposes of isolation and final separation, respectively. These columns provided a large difference in selectivity when operated under normal-phase conditions which allowed for the efficient isolation of melengestrol acetate from the complex tissue extracts. Mobile phases were composed of hexane and dichloromethane modified with methanol and water. Transfer and enrichment of the analyte from the primary phenyl column to the silica column was via a short (12 mm x 4 mm I.D.) silica column. Regeneration and equilibration of the phenyl column was performed after the injection of each tissue extract and was accomplished simultaneously while analytical separation occurred on the final silica column. Routing of the mobile phases and regeneration solvent was performed with automated switching valves. The total time required for each analysis was 12 min. Quantification is demonstrated using external standards with UV detection at 287 nm. The overall recovery of the method was 86% with a coefficient of variation of 9.84% at the 10 ppb [the American billion (10(9] is used in this article] level in bovine liver extracts.

Validation Study of Gas Chromatographic Determination of Pentachlorophenol in Animal Liver

A validation study was conducted of a gas chromatographic procedure for the determination of pentachlorophenol (PCP) in chicken, pork, and beef liver. Five analysts representing 5 laboratories analyzed randomly numbered blind duplicates at 3 fortified tissue concentrations and one incurred tissue on 2 consecutive days. The PCP concentrations ranged from approximately 40 to 400 parts per billion (ppb). All data were reported to 3 significant figures in ppb. The coefficients of variation for repeatability were between 2.8 and 8.5%, except for the beef liver, at a mean value of 80 ppb PCP, where the CV was 11.3%. The CVs for reproducibility were in the range of 9.7- 16.5% with little significant difference by species. The CV asymptotically approached 10% as the PCP level increased.

Validation study of gas chromatographic determination of pentachlorophenol in animal liver

A validation study was conducted of a gas chromatographic procedure for the determination of pentachlorophenol (PCP) in chicken, pork, and beef liver. Five analysts representing 5 laboratories analyzed randomly numbered blind duplicates at 3 fortified tissue concentrations and one incurred tissue on 2 consecutive days. The PCP concentrations ranged from approximately 40 to 400 parts per billion (ppb). All data were reported to 3 significant figures in ppb. The coefficients of variation for repeatability were between 2.8 and 8.5%, except for the beef liver, at a mean value of 80 ppb PCP, where the CV was 11.3%. The CVs for reproducibility were in the range of 9.7-16.5% with little significant difference by species. The CV asymptotically approached 10% as the PCP level increased.

Sulfamethazine blood/tissue correlation study in swine

Seventy market-weight hogs (90 to 113 kg) were used in a feeding study to determine the correlation of serum sulfamethazine concentrations with sulfamethazine concentrations in liver and muscle at time of slaughter. Test groups were fed medicated feeds prepared from commercial medicated premixes containing 110 g of sulfamethazine/metric ton for 30 days. Fifteen days before hogs were slaughtered, test groups were given maintenance feeds containing 1.1 to 13.9 g of sulfamethazine/metric ton and were fed these diets until slaughtered. Comparison of data from positive- and negative-control groups indicated that total withdrawal of sulfamethazine in the feed was not necessary for the liver to contain less than the allowed tolerance of 0.1 mg of sulfamethazine/kg of liver at slaughter. Feed concentrations of up to 2 g of sulfamethazine/metric ton could be tolerated in withdrawal feeds before liver sulfamethazine values exceeded 0.1 mg/kg of liver. Serum/tissue sulfamethazine ratios were erratic in hogs given 1.1 to 2.7 g of sulfamethazine/metric ton, but became less variable in hogs given greater than 5.7 g/metric ton. Feed concentrations greater than 8 g of sulfamethazine/metric ton produced values greater than 0.1 mg/kg of muscle and values of about 0.4 mg/kg of liver. When serum sulfamethazine concentrations alone were used as a predictor for tissue sulfamethazine values, 100% of the liver values exceeded 0.10 mg/kg of liver when sulfamethazine in serum was greater than 0.45 mg/L. However, 57.4% of samples having serum concentrations between 0.10 and 0.45 mg/L had associated sulfamethazine values greater than 0.1 mg/kg of liver. All hogs having serum sulfamethazine concentrations less than 0.1 mg/L had sulfamethazine concentrations less than 0.1 mg/kg of liver.

Chloramphenicol concentrations in calf muscle tissue

Twenty-five 9- to 11-week-old calves were administered 2 doses of chloramphenicol prepared in propylene glycol (13.6 mg/kg of body weight IV; 6.8 mg/kg IM; or 13.6 mg/kg IM) at 24-hour intervals. Calves were euthanatized at designated times from 2 to 72 hours after the last dose was administered. Muscle tissues were collected immediately after euthanasia, and chloramphenicol concentrations in the tissues were determined.

Interaction of reovirus with cell surface receptors. IV. The reovirus type 3 receptor is expressed predominantly on murine Lyt-2,3+ and human T8+ cells

Reovirus type 3 binds to approximately 20% of murine and human T cells via the viral hemagglutinin, a small outer capsid polypeptide. By using purified viral particles as a ligand in a standard plate separation technique, we have been able to enrich human peripheral blood and murine splenic T cells for reovirus receptor-positive cells (reovirus 3+) to levels of 88 to 92%. Analysis of reovirus 3+ T cells with monoclonal antibodies that identify inducer and suppressor/cytotoxic cells demonstrated that in the mouse, 68% of reovirus 3+ cells were Lyt-2+, and in the human, 60% were T8+. In reciprocal experiments, when subpopulations of murine and human T cells were prepared with the use of monoclonal anti-T cell reagents, 16% of Lyt-1+ and 81% of Lyt-2+ cells bound reovirus, whereas 30% of T4+ and 65% of T8+ cells bound reovirus. To determine whether reovirus type 3 identified a functional as well as a phenotypic category of cells, an antigen-specific cytotoxic T cell assay was employed. There was complete loss of cytotoxic activity in the reovirus 3+ cell population and slight enhancement of cytotoxic activity in the cell population from which reovirus 3+ cells were removed. This suggested that reovirus was binding to functionally active suppressor cells. Furthermore, adoptive transfer of antigen-specific T cells that were enriched for reovirus 3+ cells demonstrated suppression of cytoxic T cell activity. These results suggest that reovirus type 3 may identify a structure common to a subclass of murine and human T cells and that by using the virus as a natural biologic probe for cell surface receptors, one may be able to functionally segregate murine cytotoxic from suppressor T cells.

Interaction of reovirus with cell surface receptors. IV. The reovirus type 3 receptor is expressed predominantly on murine Lyt-2,3+ and human T8+ cells

Reovirus type 3 binds to approximately 20% of murine and human T cells via the viral hemagglutinin, a small outer capsid polypeptide. By using purified viral particles as a ligand in a standard plate separation technique, we have been able to enrich human peripheral blood and murine splenic T cells for reovirus receptor-positive cells (reovirus 3+) to levels of 88 to 92%. Analysis of reovirus 3+ T cells with monoclonal antibodies that identify inducer and suppressor/cytotoxic cells demonstrated that in the mouse, 68% of reovirus 3+ cells were Lyt-2+, and in the human, 60% were T8+. In reciprocal experiments, when subpopulations of murine and human T cells were prepared with the use of monoclonal anti-T cell reagents, 16% of Lyt-1+ and 81% of Lyt-2+ cells bound reovirus, whereas 30% of T4+ and 65% of T8+ cells bound reovirus. To determine whether reovirus type 3 identified a functional as well as a phenotypic category of cells, an antigen-specific cytotoxic T cell assay was employed. There was complete loss of cytotoxic activity in the reovirus 3+ cell population and slight enhancement of cytotoxic activity in the cell population from which reovirus 3+ cells were removed. This suggested that reovirus was binding to functionally active suppressor cells. Furthermore, adoptive transfer of antigen-specific T cells that were enriched for reovirus 3+ cells demonstrated suppression of cytoxic T cell activity. These results suggest that reovirus type 3 may identify a structure common to a subclass of murine and human T cells and that by using the virus as a natural biologic probe for cell surface receptors, one may be able to functionally segregate murine cytotoxic from suppressor T cells.

Binding of 125I-labeled reovirus to cell surface receptors

Quantitative studies of 125I-labeled reovirus binding at equilibrium to several cell types was studied, including (1) murine L cell fibroblasts; (2) murine splenic T lymphocytes; (3) YAC cells, a murine lymphoma cell line; and (4) R1.1 cells, a murine thymoma cell line. Competition and saturation studies demonstrated (1) specific, saturable, high-affinity binding of reovirus types 1 and 3 to nonidentical receptors on L cell fibroblasts; (2) high-affinity binding of type 3 reovirus to murine splenic lymphocytes and R1.1 cells; (3) low-affinity binding of reovirus type 1 to lymphocytes and R1.1 cells; and (4) no significant binding of either serotype to YAC cells. Differences in the binding characteristics of the two reovirus serotypes to L cell fibroblasts were found to be a property of the viral hemagglutinin, as demonstrated using a recombinant viral clone. The equilibrium dissociation constant (Kd) for viral binding was of extremely high affinity (Kd in the range of 0.5 nM), and was slowly reversible. Experiments demonstrated temperature and pH dependence of reovirus binding and receptor modification studies using pronase, neuraminidase, and various sugars confirmed previous studies that reovirus receptors are predominantly protein in structure. The reovirus receptor site density was in the range of 2-8 X 10(4) sites/cell. These studies demonstrate that the pseudo-first-order kinetic model for ligand-receptor interactions provides a useful model for studying interactions of viral particles with membrane viral receptors. They also suggest that one cell may have distinct receptor sites for two serotypes of the same virus, and that one viral serotype may bind with different kinetics depending on the cell type.

Quantitative thin layer chromatographic multi-sulfonamide screening procedure: collaborative study

A thin layer chromatographic procedure suitable for detection of multiple sulfonamides at 0.1 ppm was studied in an interlaboratory collaborative study. Sulfamethazine, sulfadimethoxine, and sulfaquinoxaline were variously analyzed in liver and muscle tissues from swine, turkey, and duck. The average recovery for all drugs across all tissues was 95%. The corresponding repeatability and reproducibility were 7.7% and 10.5%, respectively.

Quantitative Thin Layer Chromatographic Multi-Sulfonamide Screening Procedure: Collaborative Study

A thin layer chromatographic procedure suitable for detection of multiple sulfonamides at 0.1 ppm was studied in an interlaboratory collaborative study. Sulfamethazine, sulfadimethoxine, and sulfaquinoxaline were variously analyzed in liver and muscle tissues from swine, turkey, and duck. The average recovery for all drugs across all tissues was 95%. The corresponding repeatability and reproducibility were 7.7% and 10.5%, respectively.

Interaction of viruses with cell surface receptors

This chapter discusses the interaction of viruses with cell surface receptors. The rigorous characterizations of receptor–ligand interactions have been derived from binding studies of radiolabeled ligands in neuropharmacology and endocrinology. The definition of viral recognition sites as receptors involves three major criteria that are derived from models of ligand–receptor interactions: saturability, specificity, and competition. A variety of approaches have been used to study the interaction of viral particles with cell surface receptors or reception sites. A rigorous study of viral–receptor interactions requires the use of more than one technique as different approaches provide complementary information about viral binding. The chapter discusses membrane components that interact with viruses. The identification of the subviral components that are responsible for the binding of viruses to cell surfaces has preceded the structural understanding of the cellular receptors themselves. The chapter summarizes current data concerning the viral attachment protein (VAP) of selected viruses.

Interaction of reovirus with cell surface receptors. III. Reovirus type 3 induces capping of viral receptors on murine lymphocytes

We have previously shown that there are receptors for the hemagglutinin of reovirus type 3 on a subset of both murine T and B cells. Using purified reovirus type 3 particles as a ligand, followed by FITC-labeled antiviral antibody we have now been able to demonstrate viral induced capping of the reovirus receptor on both B and T cells. Kinetic studies and inhibition experiments using cytochalasin B and colchicine demonstrate that reovirus-induced capping of the viral receptor on both B and T cells has characteristics identical to the capping of immunoglobulin on B cells by anti-immunoglobulin reagents. Removal of the viral receptor and reexpression after overnight culture was demonstrated after membrane treatment by proteolytic enzymes (trypsin, pronase) or after viral induced modulation of receptor. Protein synthesis was required for reexpression since cyclohexamide prevented the reexpression of receptor in culture. Co-capping studies utilizing 2-color immunofluorescence failed to identify and association between the reovirus receptor and a variety of known surface structures on either B or T cells, but demonstrated independent modulation of the viral receptor from other surface structures. These studies suggest that the lymphocyte surface binding site for reovirus type 3 is a distinct structure that behaves identically in capping studies of both B and T cells, is protein in nature, and is intimately linked to the cell cytoskeleton.

Interaction of reovirus with cell surface receptors. III. Reovirus type 3 induces capping of viral receptors on murine lymphocytes

We have previously shown that there are receptors for the hemagglutinin of reovirus type 3 on a subset of both murine T and B cells. Using purified reovirus type 3 particles as a ligand, followed by FITC-labeled antiviral antibody we have now been able to demonstrate viral induced capping of the reovirus receptor on both B and T cells. Kinetic studies and inhibition experiments using cytochalasin B and colchicine demonstrate that reovirus-induced capping of the viral receptor on both B and T cells has characteristics identical to the capping of immunoglobulin on B cells by anti-immunoglobulin reagents. Removal of the viral receptor and reexpression after overnight culture was demonstrated after membrane treatment by proteolytic enzymes (trypsin, pronase) or after viral induced modulation of receptor. Protein synthesis was required for reexpression since cyclohexamide prevented the reexpression of receptor in culture. Co-capping studies utilizing 2-color immunofluorescence failed to identify and association between the reovirus receptor and a variety of known surface structures on either B or T cells, but demonstrated independent modulation of the viral receptor from other surface structures. These studies suggest that the lymphocyte surface binding site for reovirus type 3 is a distinct structure that behaves identically in capping studies of both B and T cells, is protein in nature, and is intimately linked to the cell cytoskeleton.