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Biomedical subjects

F E Lindsay

Publications and source records attributed to F E Lindsay.

At least 19 recordsLinked to original sources
PubMed2005

Development of a biologically relevant dermal sampler.

There are currently no appropriate methods for measuring dermal exposure to volatile agents. To address this we have produced a prototype Institute of Occupational Medicine (IOM) dermal sampler consisting of an adsorbent sandwiched between a permeable membrane and an impervious backing. The concentration of solvent on the membrane surface may be estimated from the mass collected on the adsorbent and the known permeation rate through the membrane. We have developed the prototype IOM dermal sampler for measurement of toluene exposures. Evaluation of the prototype sampler was undertaken in two stages: laboratory performance in controlled exposure situations and two short-field evaluations, which included simultaneous measurement of inhalation exposure. In all cases we compared the prototype IOM dermal sampler with activated charcoal cloth (ACC). Laboratory trials were split into spray, pour and immersion tests. The data from these suggest that the sampler responds to concentration rather than the mass on the surface of the sampler. The field study showed that the prototype sampler was suitable for measuring dermal exposure. However, the mean permeation rate of the best membrane was 78 000 mug cm(-2) h(-1), which is higher than the permeation rate through skin. This high permeation rate created difficulties throughout the study, particularly as it allowed the adsorbent to become rapidly saturated. The prototype IOM dermal sampler is the first practical dermal exposure sampler to mimic uptake through the skin. The sampler gave reproducible results in the laboratory and field trials. Future work is required to identify a less permeable membrane, which has characteristics closer to that of human skin. Additionally, a higher capacity adsorbent would be desirable. We have demonstrated a major difference when calculating the total contribution to body burden via the dermal exposure pathway using the prototype IOM dermal sampler and ACC patches, 1.5% of the total body burden compared with 95%. The prototype IOM dermal sampler provides a more biologically relevant exposure metric than the alternatives.

Air Pollutants, Occupational↗
PubMed1989

Ovulation detection and timing of insemination based on hormone concentrations, vaginal cytology and the endoscopic appearance of the vagina in domestic bitches.

The fertilization period, the time when fertilization can occur, can best be determined using a combination of vaginal cytology and morphology of the vaginal mucosa, behaviour and endocrinology. Neither vaginal cytological changes nor standing oestrus are reliable indicators of the fertilization period per se although with natural mating or when using AI with fresh semen there may be enough biological leeway for pregnancy to follow insemination timed using these parameters alone. This is indicated by the well recognized fecundity of bitches mated early or late in oestrus. Precise discrimination of the fertilization period, which is often required and is necessary for AI using frozen semen, can be achieved by using vaginoscopy to detect the onset of shrinkage with angulation of the mucosal folds. Vaginoscopy is also useful to determine the probable end of the fertilization period and the transition to a 'metoestrous' vaginal smear is also useful in this regard. Detection of the LH peak enables the start of the fertilization period to be forecast quite precisely but, in lieu of practical assays with which to measure plasma LH, a rise in plasma progesterone concentration to 6-8 ng/ml may be more practical.

Animals↗
PubMed1987

Further studies on the response to transplanted adult Ostertagia ostertagi in calves.

Calves infected by surgical transplantation of adult Ostertagia ostertagi had raised levels of plasma pepsinogen and those in which the largest number of worms established also had elevated plasma gastrin concentrations. Despite the elevated plasma pepsinogen values, the abomasal pH of the animals did not change significantly, and there was no significant difference in the percentage establishment of adult parasites in calves previously infected with O ostertagi third stage larvae and those which had been maintained parasite-naive before transplant.

Abomasum↗
PubMed1986

Selection of a dye for use in semen transport studies in the cow.

A series of experiments was carried out to select a dye and diluent that would facilitate identification of bovine inseminate in the uterus of the live cow when using hysteroscopic techniques. Of the dyes tested, Aniline Blue and the permitted food dye Green S as 1% solutions were the most suitable when added to semen with milk buffer diluent. Neither stained the uterine mucosa nor adversely affected the equipment, and both were visually distinctive during hysteroscopy. Using 1% concentrations of these dyes, sperm motility scores were acceptable before and after slow and fast freezing processes.

Journal Article↗
PubMed1986

An anatomical and endoscopic study of the nasopharynx and larynx of the donkey (Equus asinus).

Using histological techniques, anatomical dissection, fibre optic endoscopy and radiography, the nasopharynx and larynx of the donkey were examined and described. Compared with horses, donkeys have a much deeper pharyngeal recess extending 4.0-6.0 cm caudally from a constricted orifice, through which it communicates with the nasopharynx. Movements of the membranous lining of the recess reflect pressure changes in the upper airways. A shallow, thumb shaped depression on the rostral face of each vocal fold corresponds in position to the lateral ventricle in the horse. In the donkey, large paired laryngeal saccules, interposed between the thyroarytenoideus muscle and the thyroid cartilage, open into the laryngeal cavity through small circular orifices near the rostroventral extremity of the vestibular folds. The large thyroarytenoideus muscle is subdivided into vestibular and vocal parts, which are thought to control the expression of secretion from the laryngeal saccules. The unusual characteristics of vocalisation in the donkey may be related to the shape and orientation of the resonance chambers of the upper airways. In comparison with the horse, the asinine nasopharynx is markedly constricted in its middle part and the laryngeal airway has a more acute angulation relative to the nasopharynx. Vocalisation in the donkey was observed to have an inspiratory and an expiratory component.

Animals↗
PubMed1983

Observational study of "urine testing" in the horse and donkey stallion.

Although "urine testing" is said to enable the male equid to assess the sexual status of the mare, there are no reports in the literature of any detailed study of this behavioural response of the stallion. Behavioural response to conspecific urine was studied in two horse stallions and one donkey stallion. The relevant nasopalatine anatomy is described. Events observed during urine testing included head, neck, lip, jaw, tongue movements, penile changes and nasal secretion. Nasal endoscopy indicated that the source of part of the nasal secretion was the secretory glands of the vomeronasal organ complex. The significance and probable function of these events in urine testing is discussed.

Animals↗