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C Hoke

Publications and source records attributed to C Hoke.

At least 19 recordsLinked to original sources
PubMed2000

Precision and comparability of Abuscreen OnLine assays for drugs of abuse screening in urine on Hitachi 917 with other immunochemical tests and with GC/MS.

Abuscreen OnLine assays for drugs of abuse screening in urine have recently been developed for use on Hitachi 917 analyzers (Roche Diagnostics GmbH). The assays are based on the kinetic interaction of microparticles as measured by changes in light transmission. Drug in a sample inhibits the formation of particle aggregates and diminishes absorbance change increases. It was the goal of this study to evaluate precision and comparability of the new asssys with CEDIA drugs of abuse tests on Hitachi 917 in different laboratories (three European and three US). The assays were calibrated in the nonlinear mode with four to six standards (semiquantitative application). Initial within-run (21 replicates, four labs) and between-day (10 days, two labs) imprecision studies using Abuscreen OnLine tests and commercial negative (0.5 x cut-off) and positive (1.5 x cut-off) controls revealed the following median CVs [withinrun neg./pos. control/between-day neg./pos. control]: amphetamines 1.9/1.3/3.4/2.4, barbiturates 3.0/1.6/3.9/3.1, benzodiazepines 4.7/1.5/6.3/3.0, cocaine metabolite 1.8/0.9/2.4/1.7, methadone 5.4/1.6/5.5/2.2, opiates 5.5/2.8/5.3/2.7, THC 8.9/4.8/21.8/12.1. CVs < 10% were obtained for the THC test using controls with concentrations closer to the cut-off. An identical set of 170 GC/MS analyzed urine samples was distributed to the six laboratories and measured with Abuscreen OnLine tests on Hitachi 917. The median values for each individual sample were calculated and compared with the results obtained on individual Hitachi 917 analyzers by Passing-Bablok regression analysis. A good agreement between the laboratories was found with less than +/- 11% slope deviation and intercepts below 7% of the cut-off except for benzodiazepines (one slope 17%, one slope--26%) and THC (one slope 34%, one slope--18%). The comparability with CEDIA tests was analyzed by concordance plots using randomized routine samples in three laboratories. The following results were obtained in one of the participating laboratories [cut-off ng/mL] (No. of positive/negative/discrepant samples): amphetamines [500] 2/147/0, barbiturates [200] 1/148/0, benzodiazepines [100] 52/91/7, cocaine metabolite [300] 17/129/3, methadone [300] 113/34/2, opiates [300] 31/114/4, THC [50] 66/81/2. GC/MS was performed for clarification of the discrepant results. In summary, Abuscreen OnLine tests on Hitachi 917 give precise results which compare well when analyzed in different laboratories. They can be rated as convenient and flexible methods for drugs of abuse screening in the routine.

Amphetamines↗
PubMed1998

Evaluation and interference study of hemoglobin A1c measured by turbidimetric inhibition immunoassay.

The technical performance of the turbidimetric immunoinhibition (TI) assay for hemoglobin (Hb) A1c (Tina-quant Hb A1c, Boehringer Mannheim, Indianapolis, Ind) was evaluated by using the BM/Hitachi 911 analyzer. Intra-assay imprecision was less than 2.7%, and interassay imprecision was less than 2.8% as measured by coefficient of variation. In 93 subjects with diabetes who did not have hemoglobin variants, results of the TI assay for Hb A1c correlated strongly with those obtained by using a high-performance liquid chromatography analyzer (Diamat, BioRad Laboratories, Hercules, Calif). Among 241 subjects who had or did not have hemoglobin variants, the TI assay for Hb A1c correlated strongly with results of affinity chromatography for total glycated hemoglobin (Glyc-Affin GHb, IsoLab, Akron, Ohio). We also studied the effect of various percentages of hemoglobin S, C, E, and F on the accuracy of the TI Hb A1c assay. Only high hemoglobin F percentages caused interference. More than 14 times as many samples can be analyzed per hour by using the TI Hb A1c assay than can be analyzed by using the HPLC assay. For high-volume reference laboratories, using the fully automated TI Hb A1c assay to monitor glycemic control in patients with diabetes may be preferable to using the conventional ion-exchange high-performance liquid chromatography Hb A1c assay because the TI assay measures Hb A1c more accurately in patients with diabetes who have hemoglobin variants, and it requires less time.

Autoanalysis↗
PubMed1998

Leishmaniasis in the United States military.

Leishmaniasis is a recurrent health problem for the U.S. and other militaries. Health care workers may be unfamiliar with the risk factors, transmission, clinical features, diagnosis, and treatment of this disease. A team of highly trained specialists is required to properly manage service members with leishmaniasis. Such care is available only in a few medical centers. Although there are no prophylactic drugs to prevent this disease, control of insect populations and use of personal protection measures can minimize arthropod-related casualties. The impact of leishmaniasis on military operations and research initiatives to better prevent, diagnose, and treat infection are discussed.

Humans↗
PubMed1997

Identification of hepatitis E virus in clinical specimens: amplification of hydroxyapatite-purified virus RNA and restriction endonuclease analysis.

A multi-site nested reverse transcription and polymerase chain reaction (RT-PCR) followed by restriction endonuclease analysis (REA) was developed to identify hepatitis E virus (HEV) in clinical specimens. Four sets of primers were selected to amplify regions in the HEV genome supposed to encode the helicase, polymerase, and parts of the viral capsid protein. Digestion of the nested PCR products with HinfI, HaeII, AvaII, BglI, KpnI, SmaI, or EcoRI generated readily recognizable profiles that confirm the HEV sequences and/or distinguish the unique Mexico genotype (our positive control) from all other isolates (Asian genotype). In addition, the hydroxyapatite (HA) adsorption method was compared to other adsorption and extraction methods widely used to purify viral RNA from clinical specimens for RT-PCR. All methods presented the same sensitivity of recovery of HEV RNA, but only the adsorption methods efficiently removed fecal enzymatic inhibitors. The HA method gave the best results and was the most economic in terms of time, cost, manipulations and reagents. The method was validated by screening a small number of serum and fecal specimens available from patients with acute non-A,B,C hepatitis in Nepal. HEV RNA was identified in half (5/11) of the fecal specimens obtained from patients with evidence of recent HEV infection, but in none of the 14 patients without a serological marker for hepatitis E.

DNA Restriction Enzymes↗
PubMed1996

Immunogenic and protective response in mice immunized with a purified, inactivated, Dengue-2 virus vaccine prototype made in fetal rhesus lung cells.

The feasibility of a purified, inactivated vaccine (PIV) against dengue type 2 (DEN-2) virus was explored. Dengue-2 virus strain 16681 was used for producing a monotypic PIV. Virus adapted to fetal rhesus lung (FRhL-2) cells was harvested from roller bottle culture supernatant fluids, concentrated, and purified on sucrose gradients. Analysis of purified virus preparations by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blotting showed primarily envelope (E) and premembrane (prM) antigens. These preparations had a purity, estimated from silver-stained gels, of approximately 70%, and a yield, based on recovery of virus and viral antigen, of 10-20%. The purified virus was inactivated with 0.05% formalin at 22 degrees C, or alternatively, with 7 mRads from a 60Co source. Vaccinated mice developed high titers of anti-DEN-2 virus neutralizing antibody and were partially protected from virus challenge. These results warrant further testing and development of PIVs for the other DEN virus serotypes.

Animals↗
PubMed1996

Technical performance evaluation of BM/Hitachi 747-200 serum fructosamine assay.

The technical performance of serum fructosamine assay as a short-term index of diabetic control was evaluated by using the BM/Hitachi 747-200 Automatic Analyzer (Boehringer Mannheim Corp). Intra- and interassay precisions (CV) were <2%. Linearity was confirmed up to 1000 micromol/L. Lipemia, produced artificially or from hypertriglyceridemia in vivo, did not interfere with measurement of serum fructosamine concentration. However, hemoglobin (Hb) interfered with measurement substantially at concentrations >15.5 micromol/L, and bilirubin interfered substantially at concentrations >68.4 micromol/L. A normal reference range of up to 282 micromol/L (mean +/- 2SD = 242 +/- 40) was derived from results obtained from 228 nondiabetic subjects. In 222 diabetic subjects, serum fructosamine concentration correlated well with fasting glucose concentration (r = 0.74) and with Hb A1c concentration (r = 0.80). This automated fructosamine assay has the advantages of technical simplicity, low cost, and reduced analytical time compared with the Hb A1c method.

Autoanalysis↗
PubMed1993

Depression of the immune response to an inactivated hepatitis A vaccine administered concomitantly with immune globulin.

Inactivated hepatitis A virus (HAV) vaccine is given in a three-dose schedule. When rapid protection is needed, injection of immune globulin (IG) concomitantly with the first dose could provide passive protection until adequate active antibody response has developed. A possible effect of IG on the immune response to the vaccine was studied in healthy volunteers; 28 received vaccine alone, and 34 received the first dose simultaneously with 5 mL of IG. A control group received hepatitis B vaccine, and a fourth group received IG alone. Four weeks after the first vaccine dose, all subjects had detectable ELISA anti-HAV antibodies. Several weeks after each vaccine dose, the geometric mean titer of antibodies was significantly lower in those who received vaccine with IG but higher than in those who received IG alone. Results for neutralizing antibodies yielded a similar trend. If IG is given with HAV vaccine, a further booster vaccine dose may be required to ensure long-lasting immunity.

Adult↗
PubMed1992

Clinical and laboratory observations following oral or intramuscular administration of a live attenuated hepatitis A vaccine candidate.

Clinical observations made after immunising volunteers with a live attenuated hepatitis A vaccine are described. The candidate vaccine was prepared with the HM175 strain of hepatitis A virus and shown to be safe, immunogenic and efficacious in experimental animals. When the candidate vaccine was tested by oral administration in humans at increasing doses--10(4), 10(5), 10(6) and 10(7) median tissue culture infective doses (TCID50)--an antibody response was not observed at any dose. Volunteers who received similar doses by the intramuscular route developed antibody to hepatitis A three weeks after immunization with 10(6) or 10(7) TCID50. The antibody response was sustained for the 12 weeks of the observation period. All volunteers remained healthy with normal results from liver tests throughout the monitoring period. Further clinical observations of this product are in progress.

Administration, Oral↗
PubMed1992

Purification of native dengue-2 viral proteins and the ability of purified proteins to protect mice.

Both the envelope structural protein and the non-structural NS1 protein have been purified from the flavivirus dengue-2 by high-pressure liquid chromatography. These purified proteins maintain their reactivity with monoclonal antibodies. When tested in mice, the envelope protein elicited neutralizing antibodies and partially protected the animals against a lethal viral challenge. The mice responded to the non-structural protein by producing antibodies; however, these antibodies were not neutralizing and the mice were not protected.

Animals↗
PubMed1991

Dengue-1 virus envelope glycoprotein gene expressed in recombinant baculovirus elicits virus-neutralizing antibody in mice and protects them from virus challenge.

In order to test the feasibility of baculovirus (Autographa californica nuclear polyhedrosis virus, AcNPV) expression vectors for making immunogens against dengue-1 (DEN-1) virus, a portion of the envelope (E) glycoprotein gene of DEN-1 virus was cloned and expressed. The recombinant baculovirus contains 107 nucleotides from the 3' terminus of the DEN-1 matrix (M) gene, which encodes a hydrophobic signal peptide and extends through the first 1, 245 nucleotides of E, terminating 243 nucleotides before the 3' terminus of E. When the recombinant virus was grown in Spodoptera frugiperda cells, about 1 mg of E antigen was made per 10(9) cells. Recombinant E antigen reacted with E protein-specific monoclonal antibodies and stimulated production of DEN-1 virus neutralizing antibody in BALB/c mice. Mice immunized with recombinant E antigen or with heat-inactivated DEN-1 virus were protected significantly against lethal DEN-1 virus challenge. A dose/response effect was observed, with increasing amounts of recombinant antigen leading to increased survival. These results demonstrate the utility of baculovirus for producing immunogens against DEN-1 virus.

Animals↗
PubMed1990

Protection of mice against lethal Japanese encephalitis with a recombinant baculovirus vaccine.

Genes coding for the E and NS1 glycoproteins of Japanese encephalitis virus (JEV) were cloned into baculovirus expression vectors. The recombinant baculoviruses obtained were used to infect Spodoptera frugiperda cells. The infected cells were used to immunize C57/B mice, which were then challenged with live JEV. Survival was increased from about 30% in unimmunized mice to 70% in E and polyprotein recipients (P less than 0.005), but was not increased in NS1 recipients despite the development of antibody against NS1 by these mice. Virus neutralizing antibody was demonstrated in 18/20 E glycoprotein recipients and 15/20 polyprotein recipients. The baculovirus expressed E glycoprotein stimulated antibody which was protective and neutralizing in this system.

Animals↗
PubMed1989

Human T cell responses to dengue virus antigens. Proliferative responses and interferon gamma production.

The severe complications of dengue virus infections, hemorrhagic manifestations and shock, are more commonly observed during secondary dengue virus infections than during primary infections. It has been speculated that these complications are mediated by cross-reactive host-immune responses. We have begun to analyze human T cell responses to dengue antigens in vitro to explain the possible role of T lymphocytes in the pathogenesis of these complications. Dengue antigens induce proliferative responses of PBMC from dengue antibody-positive donors, but do not induce specific proliferative responses of PBMC from dengue antibody-negative donors. IFN gamma is detected in the culture fluids of dengue-immune PBMC stimulated with dengue antigens. The cells that proliferate in the dengue antigen-stimulated bulk cultures have CD3+, CD4+, CD8-, CD16-, and CD20- phenotypes. Dengue-specific T cell lines were established using limiting dilution techniques. They have CD3+, CD4+, and CD8- phenotypes, and produce IFN gamma in response to dengue antigens. Culture fluids from dengue-immune PBMC stimulated with dengue antigens, which contain IFN gamma, augment dengue virus infection of human monocytes by dengue virus-antibody complexes. These results indicate that PBMC from dengue-immune donors contain CD4+ T cells that proliferate and produce IFN gamma after stimulation with dengue antigens, and suggest that the IFN gamma that is produced by these stimulated dengue-specific T cells may contribute to the pathogenesis of dengue hemorrhagic fever and dengue shock syndrome by increasing the number of dengue virus-infected monocytes in the presence of cross-reactive anti-dengue antibodies.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1982

Characterization of atypical aerobic gram-negative cocci isolated from humans.

Six atypical aerobic gram-negative cocci, isolated from humans, were classified taxonomically by genetic relatedness (DNA base pairs and DNA homology), fatty acid content, pigment absorption profile, and other physiological and biochemical characteristics. One strain (M448), which produced acid only from glucose, was identified as Neisseria meningitidis; one strain (CH), which produced acid from glucose, maltose, and sucrose, was identified as N. gonorrhoea; Branhamella catarrhalis was confirmed in a case of acute meningitis; N. canis was identified in a cat bite wound; and representative isolates of a proposed new pigmented species were found to have genetic affinities with N. meningitidis and N. perflava.

Base Sequence↗