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Biomedical subjects

M Barrett

Publications and source records attributed to M Barrett.

65 records · Page 4Linked to original sources
PubMed1981

Hydration and percutaneous absorption II: Influence of hydration on water and alkanol permeation through Swiss mouse skin; comparison with hairless mouse.

In vitro permeation studies with biological membranes often involve long, aqueous maceration of the tissue. The present investigation examined the possible effects of hydration on barrier integrity of Swiss mouse skin; using water, methanol, ethanol, and butanol as permeants and a previously developed procedure involving multiple, sequential permeation runs on each piece of skin. The permeation rate of water increased almost linearly up to 30 hr of hydration and then tended to level off. Transport rates of methanol and ethanol increased asymptotically and then plateaued at approximately 15 hr. These results contrast with earlier findings on hairless mouse skin where the permeabilities of these three compounds were unaffected by aqueous immersion. The permeation rate of butanol also increased during the first 15 hr of hydration but gradually declined over the next 25 hr. This result again contrasts with the hairless mouse species in which butanol permeability doubled in 10 hr and then plateaued. The species differences in the hydration profiles appear related to the vastly dissimilar pellages and, in the Swiss mouse, may indicate greater involvement of the transfollicular pathway.

Alcohols↗
PubMed1980

Trypanosoma murmanensis: its effects on the longhorn sculpin, Myoxocephalus octodecemspinosus.

A study was undertaken to ascertain the effects of Trypanosoma murmanensis, on adult longhorn sculpins (Myoxocephalus octodecemspinosus) following experimental infection. Blood samples, taken at intervals after infection, indicated a decrease in hematocrit, hemoglobin and total plasma protein levels which did not return to normal for at least 72 days. An increase of lymphocytic cells occurred about 42 and 58 days but reverted later to normal levels. Anemia persisted despite low parasitemias and might be attributed to lytic factors released directly or indirectly by the parasite and/or an inability of the erythropoietic system to respond following the initial blood loss.

Anemia↗
PubMedDate not supplied

Comparative field evaluation of divided-dosing and reduced feed intake upon treatment efficacy against resistant isolates of Teladorsagia circumcincta in sheep and goats.

The effects of modifying drug administration and food intake upon the efficacy of fenbendazole against resistant isolates of Teladorsagia (Ostertagia) circumcincta were investigated using naturally infected sheep and goats. Administration of the manufacturer's recommended dose (MRD) as two 2.5 mg kg(-1) bodyweight doses divided by a 12-hour interval resulted in an apparent increase in efficacy of over 28 per cent compared with conventionally treated sheep. Withholding feed for 24 hours before treatment at the MRD resulted in respective increases of 39.7 per cent (P<0.05) and 25.2 per cent compared with conventionally treated sheep and goats. A combination of food withdrawal and divided dosing did not further increase treatment efficacy in goats. It is suggested that withholding feed, divided-dosing or combining these methods may extend the useful life of the broad spectrum class of anthelmintics.

Animals↗
PubMedDate not supplied

Resectional arthroplasty: treatment for calcaneonavicular coalition.

In a 10-year retrospective review of one practitioner's experience with calcaneonavicular tarsal coalitions, a diagnostic procedure based on clinical and radiographic examination is described. What typically may present as heel pain, on thorough clinical examination, may be identified more specifically as midtarsal pain. Radiographically degenerative changes may be identified through computed tomography as well as magnetic resonance imaging, bone scan, and plain radiographs. Treatment modalities are based on the degree of symptomatic degenerative changes present. In early stages, steroid injection is used to diminish inflammation at the midtarsal joint. Typically, this is performed with orthotic therapy to limit the motion at the calcaneonavicular coalition. More advanced stages will require surgical intervention. Based on the degree of degeneration at the more proximal subtalar joint, arthroplasty of the calcaneonavicular coalition without interposition of the extensor digitorum brevis has produced acceptable long-term results. If the subtalar joint has advanced degeneration and there has been failure of more conservative treatments, rearfoot arthrodesis has been performed.

Adolescent↗
PubMedDate not supplied

Development and evaluation of an in vivo mouse model for studying myocutaneous flap microcirculation and viability before and after suturing or stapling.

A model was developed in albino hairless mice to study microcirculation and viability of dorsal distally based myocutaneous flaps. The efficacy of this model was tested in 120 mice by evaluating the effects of excessive crimping and tension attributed to Proximate or Signet staples or to simple or mattress nylon sutures. Microhemodynamics were assessed using computer-assisted intravital videomicroscopic and electro-optical methods. Volumetric rates of blood flow were calculated within terminal arterioles from measurements of internal diameter and mean centerline cellular velocity. The viability was determined on day 5 by measuring the areas of necrosis (mm2) along the cut edges of these flaps. In 80 mice, flaps were elevated and examined at 0 h and then again at 24 or 48 h. There were 40 mice in each of these disturbed groups. In a third group of 40 mice, flaps were raised at 0 h without videomicroscopic examination at 0, 24, or 48 h (undisturbed group). All flaps were stapled or sutured to the original donor site with one of the four methods of closure. The results of this study indicate that sutures produce the highest incidence of necrosis at 5 days when compared to staples in the undisturbed groups of mice. However, no significant differences in necrosis were observed when flaps were disturbed at 48 h despite videomicroscopic evidence of depressed blood flow along their cut edges. In contrast, results at 24 h were equivocal and statistically not significant. These data suggest that the phenomenon of delay and/or flap recirculation following removal and reapproximation of sutures or staples drastically improves perfusion and viability of disturbed flaps.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗