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Biomedical subjects

D Agnew

Publications and source records attributed to D Agnew.

6 recordsLinked to original sources
PubMed1998

Ultrasonographic monitoring of artificially stimulated ejaculation in three rhinoceros species (Ceratotherium simum, Diceros bicornis, Rhinoceros unicornus).

Manual massage of the penis and rectal electroejaculation methods have been minimally effective for collecting semen from the rhinoceros. These two methods for stimulating ejaculation were evaluated by rectal ultrasonography. One individual each of three rhinoceros species (Ceratotherium simum simum, Rhinoceros unicornis and Diceros bicornis) was stimulated by manual massage of the penis and two black rhinoceroses (Diceros bicornis) were electroejaculated. On ultrasonography, neither manual massage nor rectal electroejaculation affected the accessory glands. The pelvic urethra remained empty during manual massage of unconditioned animals; however, this area was filled before commencement of massage of conditioned animals. The pelvic urethra also filled during electroejaculation. Semen accumulated in the pelvic urethra during pauses between electrical stimulations and was moved distally into the penile urethra by rectal and penile massage. The volumes of seminal fluid recovered from electroejaculation in this study exceeded previously reported attempts. This study demonstrated the potential of transrectal imaging for improving the recovery of semen by these methods.

Animals↗
PubMed1995

3T3 cell motility and morphology before, during, and after exposure to extremely-low-frequency magnetic fields.

Automated image cytometry techniques were used to measure motility and morphology in 3T3 fibroblasts exposed to extremely-low-frequency (ELF) magnetic fields. Cell motility and morphology were measured as a function of time before, during, and after 3-4 hour exposures to vertically oriented, 100 microTRMS sinusoidal magnetic fields at various frequencies in the 10-63 Hz range. Sham exposures were also carried out. No static DC fields were applied, but the geomagnetic field was almost vertical and, therefore, had a large component (28.3 microT) parallel to the applied AC field. The morphology and motile behavior of the cells were characterized by mathematically defined descriptors, which were calculated and averaged for the exposure period as well as for control periods that preceded and followed the exposure period. Each experiment involved the tracking of 100 cells that were subjected to one of the test frequencies (unless a sham exposure was being conducted). Statistical analysis of the results showed that even small changes of 10-20% could be significant at the P < .05 level. Changes on this order were measured in a significant proportion of the experiments. However, because such results were seen for both the sham-exposed and the ELF-exposed cells, and because the range of values that was obtained for the sham exposures was the same as that obtained for the ELF exposures, we concluded that there was no evidence to show that any of the measured changes were attributable to the applied ELF magnetic field.

3T3 Cells↗
PubMed1992

The effects of continuous exposure to 20-kHz sawtooth magnetic fields on the litters of CD-1 mice.

Mated CD-1 mice were exposed to 20-kHz sawtooth magnetic fields similar to those associated with video display terminals (VDT). Four groups of animals were continuously exposed from day 1 to day 18 of pregnancy to field strengths of 0, 3.6, 17, or 200 microT. There were no less than 185 mated dams in each exposure group. On day 18, the dams were sacrificed and assessed for weight gain and pregnancy. The litters were evaluated for numbers of implantations, fetal deaths and resorptions, gross external, visceral and skeletal malformations, and fetal weights. There were no less than 140 pregnant females in each group, and there were no significant differences between any of the exposure groups and the sham group (0 microT) for any of the end points. The results of this study do not support the hypothesis that the 20-kHz VLF magnetic fields associated with video display terminals are teratogenic in mammals.

Abnormalities, Radiation-Induced↗