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Internal Positive Control (internal + positive_control)

Distribution by Scientific Domains
Medical Sciences40%

Selected Abstracts

Evaluation of an internal positive control for Cryptosporidium and Giardia testing in water samples

LETTERS IN APPLIED MICROBIOLOGY, Issue 3 2003
M. Warnecke
Abstract Aims: An internal positive control for Cryptosporidium and Giardia monitoring was evaluated for use in routine water monitoring quality control. The control, known as ColorSeed C&G (BTF Pty Ltd, Sydney, Australia), is a suspension containing exactly 100 Cryptosporidium oocysts and 100 Giardia cysts that have been modified by attachment of Texas Red to the cell wall, allowing them to be differentiated from unmodified oocysts and cysts. The control enables recovery efficiencies to be determined for every water sample analysed. Methods and Results: A total of 494 water samples were seeded with ColorSeed C&G and with unlabelled Cryptosporidium and Giardia and then analysed. Additionally, the robustness of the ColorSeed labelling was challenged with various chemical treatments. Recoveries were significantly lower for the ColorSeed Texas Red labelled Cryptosporidium and Giardia than recoveries of unlabelled Cryptosporidium and Giardia. However, the differences in recoveries were small. On average ColorSeed Cryptosporidium recoveries were 3·3% lower than unlabelled Cryptosporidium, and ColorSeed Giardia recoveries were 4% lower than unlabelled Giardia. Conclusions: ColorSeed C&G is suitable for use as an internal positive control for routine monitoring of both treated and raw water samples. Significance and Impact of the Study: The small differences in recoveries are unlikely to limit the usefulness of ColorSeed C&G as an internal positive control. The ColorSeed labelling was found to be robust after different treatments. [source]

A simple method for detecting genetically modified maize in common food products

BIOCHEMISTRY AND MOLECULAR BIOLOGY EDUCATION, Issue 1 2004
Chris Brinegar
Abstract A commercially available leaf DNA extraction and amplification kit has been adapted for the detection of genetically modified material in common food products containing maize. Amplification using published primer pairs specific for the Bacillus thuringiensis delta-endotoxin and maize invertase genes results in a 226-bp invertase PCR product in all samples (an internal positive control) plus a 184-bp product in samples that are genetically modified with the endotoxin gene. The ease and rapidity of DNA extraction and PCR make this exercise especially suitable for advanced-placement high school or lower division college biology students. [source]

Annexin VII as a Novel Marker for Invasive Phenotype of Malignant Melanoma

CANCER SCIENCE, Issue 1 2000
Tatsuki R. Kataoka
Both F10 and BL6 sublines of B16 mouse melanoma cells are metastatic after intravenous injection, but only BL6 cells are metastatic after subcutaneous injection. While examining the genetic difference between the two sublines, we found a marked reduction of annexin VII expression in BL6 cells. In addition, fusion cell clones of both sublines, were as poorly metastatic as F10 cells after subcutaneous injection, and contained the annexin VII message as abundantly as F10 cells. Hence, we examined whether the annexin VII expression was correlated with the less malignant phenotype of clinical cases by immunohistochemistry. Immunoreactivities to anti-annexin VII antibody in melanoma cells were evaluated quantitatively by using skin mast cells as an internal positive control. Eighteen patients with malignant melanoma were divided into two groups: lymph node metastasis-negative and positive groups. The ratio of numbers of patients positive versus negative to the antibody was significantly larger in the former than in the latter group. These results not only indicated that annexin VII serves as a marker for less invasive phenotype of malignant melanoma, but also suggested a possible role of annexin VII in tumor suppression. [source]

New multiplex PCR method for the detection of Clostridium difficile toxin A (tcdA) and toxin B (tcdB) and the binary toxin (cdtA/cdtB) genes applied to a Danish strain collection

CLINICAL MICROBIOLOGY AND INFECTION, Issue 11 2008
S. Persson
Abstract Isolates of Clostridium difficile from 159 hospitalized Danish patients (2005) were analysed by a new 5-plex PCR method targeting the toxin genes tcdA, tcdB, cdtA and cdtB, and 16S rDNA as an internal positive control. Additionally, the toxin-regulating gene tcdC was partially sequenced by a new sequencing-based method that revealed genetic changes that may render the gene product inactive. Finally tcdA was analysed using a previously published method for the detection of internal deletions. The 5-plex PCR revealed four different toxin gene profiles: 36 tcdA+, tcdB+, cdtA+/cdtB+; one tcdA+, tcdB,, cdtA+/cdtB+; 98 tcdA+, tcdB+, cdtA,/cdtB,; and 24 non-toxigenic tcdA,, tcdB,, cdtA,/cdtB,. Deletion studies revealed that 26 strains contained a c. 700-bp deletion in tcdA, and 39 strains contained at least one possible inactivation feature in tcdC. The prevalence of the binary toxin genes was 23%. All strains with the tcdA+, tcdB+, cdtA+/cdtB+ profile were investigated by PCR ribotyping, and this revealed eight different ribotypes, none of which were 027. The 5-plex PCR method offers a one-step, rapid and specific screening method for C. difficile toxin genes. This toxin gene profiling, together with deletion studies in tcdA and tcdC, may allow an evaluation of the pathogenic potential of C. difficile. [source]