Biology Application Brief
Human Inferility
The Solution
Davis and colleagues use
DADiSP to help them implement an
alternative approach to sperm motion analysis. They believe that their
new method gives a more accurate characterization of sperm motion than
traditional methods.
Adjustable Averaging
Applying the fixed-length running average (FLRA) analysis method to
sperm has the effect of overly smoothing some trajectories and
insufficiently smoothing others. These errors are compounded further
when scientists try to produce average values for an entire cell
population. The new method for analysis pioneered by Dr. Davis and
colleagues adapts the width of the running average of a sperm cell's
path to the changing wavelengths of the major spatial oscillations of
each curvilinear trajectory. This new method of measurement may
provide more accurate modeling of sperm paths so that more accurate
judgments can be made about the healthiness of the sperm.
Kinematic Data Reduction
A high-speed video camera and recorder running at 200 frames per second
make a first observation of sperm swimming in seminal plasma at 37
degrees C. The trajectories are recorded and digitized, then analyzed
for kinematic parameters for one second (200 data points). The
trajectory data are then imported into PathTool, a program written in
the lab, which computes their average lengths and two vectors which are
exported to DADiSP for harmonic analysis. These new measurements,
which reveal the frequencies and amplitudes that occur in highly
irregular motion, are based on fast Fourier transforms (FFTs). They
include the fundamental harmonic of motion (HAR), the magnitude of HAR
(MAG), and the power bandwidth of HAR (PWB), which are basic window
calculations in a DADiSP worksheet.
Exploratory Data Analysis
Dr. Russel Davis states that he considers DADiSP's ease of use "one of
its most important features." He says he likes being able to use it to
design a number of signal processing pathways to use with different
signals: "For exploratory data analysis it is very useful." DADiSP
allows Dr. Davis and colleagues to discover patterns and periodicities
in sperm motion that until now have been obscured.
DADiSP, an Ingredient for Success
As a result of their findings, Davis and colleagues have recommended
vigorous empirical testing of their methods, and have made suggestions
for new CASA instruments. Ultimately these research efforts will
result in greater refinement of the methods used to investigate
infertility, and DADiSP will have been a part of the success.