Sporadic Contamination Of Pcr Tubes

The Forensic Science Service recently noted that sporadic contamination of consumables used in DNA testing, such as the small tubes in which the PCR amplification is performed, can introduce extraneous DNA profiles (Howitt et al. 2003). The FSS observed 11 casework-contaminating DNA profiles in running over one million samples in a three-year period. These contaminating profiles were identified in negative controls and quality control testing of select tubes examined to indicate general batch quality. An analysis of anonymous samples provided by 300 employees of the tube manufacturer revealed complete matches to 10 of the 11 identified casework-contaminating DNA profiles (Howitt et al. 2003). Communication with the tube manufacturer resulted in implementation of additional anti-contamination measures in the production process, which has significantly lowered the number of contamination events attributable to their manufacturing staff.

The use of negative control log information and elimination databases for forensic laboratory personnel, manufacturing staff of the suppliers of DNA consumables, and police officers handling crime scene evidence help identify potential sources of contaminating DNA. In addition, increased used of robotics for process automation (see Chapter 17) help reduce the risk of contamination occurring since people have less direct contact with samples in the laboratory.

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Stammering Its Cause and Its Cure

Stammering Its Cause and Its Cure

This book discusses the futility of curing stammering by common means. It traces various attempts at curing stammering in the past and how wasteful these attempt were, until he discovered a simple program to cure it. The book presents the life of Benjamin Nathaniel Bogue and his struggles with the handicap. Bogue devotes a great deal of text to explain the handicap of stammering, its effects on the body and psychology of the sufferer, and its cure.

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