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Biomedical subjects

P Minor

Publications and source records attributed to P Minor.

At least 19 recordsLinked to original sources
PubMed2001

Adventitious agent issues.

Characterised cell banks are likely to be the most virologically satisfactory production system. In the past there have been numerous examples of contamination of biologicals by agents which may be difficult to detect. The certainty with which a cell can be thought satisfactory depends on the efficacy of the available methods of examination.

Animals↗
PubMed2001

Characteristics of poliovirus strains from long-term excretors with primary immunodeficiencies.

Individuals who are deficient in humoral immunity are particularly at risk from infection with enteroviruses, and poliovirus in particular, where antibodies are the main source of protection from disease. Long-term excretion of vaccine strains of poliovirus has been documented for many years and instances of paralytic poliomyelitis in hypogammaglobulinaemic patients who were subsequently found to have been excreting virus for prolonged periods have been reported in the U.S.A., Germany and Japan. The identification of a healthy immunodeficient patient in the U.K. who has probably been excreting type 2 poliovirus for 15 years will be described, with the characteristics of the virus and the results of attempts at treatment so far. Such individuals pose a significant risk to the eradication programme unless they can be identified and treated.

Agammaglobulinemia↗
PubMed1997

Assessing the significance of reverse transcriptase activity in chick cell-derived vaccines.

A recent publication reported the detection of low levels of the enzyme reverse transcriptase (RTase) in live viral vaccines prepared in chick embryo cells. The enzyme was detected using an assay with greatly increased sensitivity compared to more conventional methods. The authors have confirmed the observation of RTase activity and demonstrate that the activity is not dependent on the production of viral vaccines in chick cells but is present ubiquitously in chick embryonic fluids. The authors have also been unable to transmit the RTase activity from chick cells to a wide variety of cells of human, monkey, rabbit and turkey origin, suggesting that the activity is not associated with an avian agent capable of infecting these cells. It is concluded that the data available present no cause for concern over the safety of vaccines derived in chick cells and current WHO requirements for such vaccines remain appropriate.

Animals↗
PubMed1997

Collaborative study to assess the suitability of a proposed working reagent for human parvovirus B19 DNA detection in plasma pools by gene amplification techniques. B19 Collaborative Study Group.

BACKGROUND AND OBJECTIVES: A collaborative study was done to examine the sensitivity and specificity of assays for the detection of human parvovirus B19 DNA in plasma pools by PCR techniques and to establish a working reagent for B19 DNA testing of plasma pools. MATERIALS AND METHODS: Duplicate samples consisting of a tenfold dilution series of a positive cryosupernatant diluted in B19 DNA-negative cryosupernatant were sent to 17 laboratories. RESULTS: The sensitivity of the assays varied: 2 laboratories were able to detect the 10(-7) dilution while 1 laboratory failed to detect B19 DNA in any samples. In addition, 5 laboratories obtained false-positive results. CONCLUSIONS: In general, laboratories using assays optimised for rapid detection of B19 DNA in serum samples did not perform well, indicating that such rapid methods are not adequate for examination of plasma pools. The 10(-6) dilution was detected by approximately half the laboratories and could be used as the working reagent.

DNA, Viral↗
PubMed1997

Presence of human immunodeficiency virus (HIV) type 1 subtype A infection in a New York community with high HIV prevalence: a sentinel site for monitoring HIV genetic diversity in North America. Centers for Disease Control and Prevention-Bronx Lebanon HIV Serosurvey Team.

To determine whether US residents are infected with subtypes of human immunodeficiency virus (HIV) type 1 other than subtype B (Western), the predominant North American subtype with a unique GPGR genetic sequence in the V3 loop, viruses from 22 HIV-infected adults were serotyped and subtyped. Twenty patients had subtype B (Western), of whom 15 had serotype B (Western), 3 had serotype A/C, 1 had serotype B (Thai), and 1 had a nontypeable serotype. Two had subtype A, both serotype A/C. Both subtype A-infected patients, only 1 of whom had been outside the United States, reported sex with persons traveling abroad, suggesting possible acquisition in the United States. Because US residents are infected with non-subtype B (Western) strains, US surveillance for HIV-1 diversity is needed to elucidate subtype-specific transmission patterns and pathogenesis and to guide evaluation and development of HIV diagnostic tests and vaccines.

Adolescent↗
PubMed1997

Behavioral risk factor surveillance of aged Medicare beneficiaries, 1995.

The Behavioral Risk Factor Surveillance System (BRFSS) is an ongoing State-based telephone survey of adults, administered through State health departments. The survey estimates health status and the prevalence of various risk factors among respondents, who include both fee-for-service and managed care Medicare beneficiaries. In this article the authors present an overview of the BRFSS and report 1995 regional results among respondents who were 65 years of age or over and who had health insurance. The advantages and disadvantages of using the BRFSS as a tool to monitor beneficiary health status and risk factors are also discussed.

Aged↗
PubMed1996

Detection of human parvovirus B19 DNA in plasma pools and blood products derived from these pools: implications for efficiency and consistency of removal of B19 DNA during manufacture.

The polymerase chain reaction (PCR) assay was used to detect human parvovirus B19 DNA in 38 blood products and start plasma pools from five different manufacturers. The products examined were albumin, factor VIII, intravenous (i.v.) and intramuscular (i.m) immunoglobulin batches. The majority of pools from all the manufacturers had detectable B19 DNA (64/75:85%; ranging from 60% to 100% for individual manufacturers). B19 DNA was found in 3/12 albumin samples, in 7/7 factor VIII samples, 3/15 IVIG samples and 3/4 IMIG samples. The levels of B19 DNA in pools varied from 10(2) to 10(9) genome equivalents/ml, whereas the levels in products varied from 10(2) to 10(6) genome equivalents/ml, but there was no clear relationship between the levels of B19 DNA in start pools and final products. The levels of B19 DNA varied between different batches of the same product from a single manufacturer, possibly due to small variations in the processing parameters. In addition, there was some indication from the study of IVIG samples that treatment at low pH may result in removal of PCR-detectable B19 DNA.

Base Sequence↗
PubMed1996

Collaborative study to assess the suitability of an HCV RNA reference sample for detection of an HCV RNA in plasma pools by PCR.

A collaborative study was undertaken to examine the sensitivity and reproducibility of hepatitis C virus (HCV) RNA PCR assays of plasma pools in order to establish a reference sample for HCV PCR testing of plasma pools. Samples consisting of an HCV-RNA-positive donation diluted tenfold in an HCV-RNA-negative cryosupernatant were sent to 16 participating laboratories (including blood product manufacturers and control authorities). The results of the in-house assays indicate that a 10(-4) dilution of the positive donation in the cryosupernatant could be used as the reference sample as this was the highest dilution of the positive donation that was detected in all assays. In contrast, the results obtained with a commercially available assay, designed for use with single-donation plasma or serum (Roche Amplicor TM HCV test), were not so clear-cut and the assay appeared to be ten-fold less sensitive than the in-house assays.

Hepacivirus↗
PubMed1994

A sensitive PCR method for detecting HCV RNA in plasma pools, blood products, and single donations.

Although current manufacturing processes appear to efficiently inactivate hepatitis C virus (HCV), it is possible that contaminated blood products may result from failure of some stage during manufacture or from virus overload of plasma pools used for preparation of products. While antibody screening probably removes the majority of HCV positive donations, some donations which are antibody-negative but HCV positive may be included in pools. The HCV RNA content of plasma pools from paid and voluntary donors was investigated by polymerase chain reaction (PCR). A sensitive PCR method using a single pair of primers from the 5' non-coding region of the HCV genome and a "hot-start" was established and shown to be as sensitive as the more conventional nested PCR (which uses two pairs of primers). The majority of pools from paid donors (prescreening) were HCV RNA positive, while all pools from voluntary donors were both antibody and RNA negative. Intravenous immunoglobulins prepared from contaminated pools were RNA negative despite having high antibody levels, indicating satisfactory clearance of the virus during manufacture. The virus load of the pools was at least a thousand-fold lower than that of single donations, possibly as a result of treatment during the production of the pools or the presence of factors in pools which reduce the sensitivity of some part of the PCR assay. The HCV content of a plasma donation was determined as 3.6 x 10(6) genomes/ml by an end point dilution method. Thus a simple and sensitive PCR assay was established for detecting HCV RNA in plasma pools and blood products.

Base Sequence↗
PubMed1993

Shedding of virulent poliovirus revertants during immunization with oral poliovirus vaccine after prior immunization with inactivated polio vaccine.

Fecal shedding of virulent revertant polioviruses was examined in isolates from infants previously immunized with > or = 1 dose of orally administered live attenuated polio vaccine (OPV) alone, enhanced-potency inactivated polio vaccine (EIPV) alone, or a combination of both. After administration of OPV alone, vaccine poliovirus serotypes were recovered in feces within 1 week and for as long as 31-60 days in 30%-80% of subjects after 1 or 2 doses and in 30%-50% after immunization with > or = 3 doses. No revertant poliovirus shedding was observed after OPV challenge in subjects immunized previously with > or = 3 doses of OPV. However, fecal shedding of revertant poliovirus after OPV challenge was observed in 50%-100% of subjects previously immunized with > or = 3 doses of the EIPV. These findings suggest that prior immunization with EIPV does not prevent fecal shedding of revertant polioviruses after subsequent reexposure to OPV.

Feces↗
PubMed1992

A bioassay for antiestrogenic activity--potential utility in drug development and monitoring effective in vivo dosing.

Monitoring effective antiestrogenic activity of the triphenylethylenes in patients with breast cancer is usually determined by the duration of response. The pharmacokinetics of toremifene and tamoxifen have been shown to be highly variable but patient specific. In the present study, we developed a method to accurately assess the antiestrogenic activity of these agents using plasma specimens, cell culture, and cell cycle measurements. Plasma specimens (4-5mls) obtained from patients receiving toremifene (360mg/day for 5 days in a phase I trial) or tamoxifen (20mg/day) were extracted and reconstituted in tissue culture media (4-5mls), and growth inhibition was determined in estrogen responsive MCF-7 cells. Additionally, plasma specimens were quantified for toremifene or tamoxifen concentrations using HPLC. Growth inhibition of plasma specimens containing either toremifene or tamoxifen and their metabolites was also examined. Cell cycle measurements were determined following in vitro exposure with flow cytometric techniques. Our results show that a dose-response relationship exists between cell growth inhibition and cell cycle measurements for human plasma with added toremifene or tamoxifen, and also for human plasma specimens containing drug and its metabolites after treatment. Our antiestrogenic bioassay can address clinical research problems such as patient-specific pharmacokinetics, dosing compliance, and acquired antiestrogen resistance.

Breast Neoplasms↗