Chemiluminescent detection of RFLP patterns in forensic DNA analysis.

DNA testing by restriction fragment length polymorphism (RFLP) analysis is an extremely important technique used in forensic science laboratories. While RFLP testing is a highly informative method, it traditionally has had several disadvantages. It is time consuming and involves work with radioactive phosphorous. A detection method that is faster and safer than isotopic detection is presented. Various membranes, fixation methods and transfer procedures were evaluated for DNA retention and sensitivity using alkaline phosphatase conjugated oligonucleotide probes and a chemiluminescent substrate. Blood samples and evidentiary material from forensic casework were analyzed by both chemiluminescent and isotopic detection. Results of each method were compared for pattern appearance, band size, and composite profile frequency. The chemiluminescent system had very good sensitivity, detecting 3-25 ng K562 DNA. Most patterns developed by both methods appeared the same. The variation observed between band sizes and frequency estimates generated by each method was as expected for an inter-gel comparison. The chemiluminescent detection procedure described here is suitable for use in forensic casework.

Detection of prostate specific antigen by ELISA.

A method for the detection of prostate specific antigen (PSA or P30) by enzyme linked immunosorbent assay (ELISA) has been developed. The method was evaluated for sensitivity and specificity and compared to other methods of semen identification on numerous casework samples. A sensitivity of less than 1 ng/mL PSA is routinely achieved. Numerous domestic contaminants and body fluids were tested and none were found to give a false-positive result. However, false-negative results did occur in samples contaminated with detergents. Additionally, some poorly preserved items of evidence did not give positive results where expected. In spite of these minor limitations, this method was found to be highly sensitive and specific and an efficient method for identifying semen in forensic casework.

Alterations of skin microcirculatory rhythmic oscillations in different positions of the lower extremity.

Microcirculatory vasomotion is considered to be an important mechanism promoting and facilitating the transfer of blood cells through skin capillaries. Since skin vulnerability of the leg is closely associated with gravitational factors and skin micro-circulation, we investigated by a laser Doppler apparatus influence of postural changes on skin blood flow oscillations in lower limbs of healthy volunteers. Our data show a marked decrease in microcirculatory oscillation amplitudes at a frequency 7.6 (+/- 0.6) min-1 after lowering the leg. This could be reversed by the application of compressive bandage. Our study points toward a potentially important mechanism of microcirculatory impairment during orthostasis.

Typing of urine in the ABO and Lewis systems.

A study was conducted to investigate the reliability of determining the ABO type and Lewis group from urine samples stored for prolonged periods under different conditions. Urine samples were successfully typed regardless of storage conditions and storage duration.

The use of microspectrophotometry to characterize microscopic amounts of blood.

The use of a Nanospec 10 S microspectrophotometer to examine minute bloodstains is discussed. To satisfy criteria for chemical identity, absorption spectra were recorded before and after treatment of the blood with Takayama reagent. The technique is of value where only tiny particulate bloodstains are available for testing and in other specialized instances.

Superconducting multicontact rotary switch.

A compact mechanical multiposition superconducting switch, suitable for a wide variety of cryoelectronic applications, has been developed. The switch is easy to fabricate in laboratory conditions. Its design is based on principles used in normal rotary switches and offers the same ease in stacking together multiple sections.