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Biomedical subjects

M W Barrett

Publications and source records attributed to M W Barrett.

At least 19 recordsLinked to original sources
PubMed1999

In vitro inhibition of tumour growth in a helium-rich environment: implications for laparoscopic surgery.

BACKGROUND: The recent results of several experimental studies have suggested that tumour implantation after laparoscopic surgery for intra-abdominal malignancy may be partly related to the chemical composition of the insufflation gas used during surgery. These studies have demonstrated that the use of helium as a laparoscopic insufflation agent for cancer surgery results in less tumour implantation and growth at port sites. To further investigate these findings, the present study was performed to compare the growth of cultured tumour cells after exposure to simulated laparoscopic environments, rich in helium, carbon dioxide (CO2), or air. METHODS: A rat mammary adenocarcinoma cell suspension was exposed to a simulated laparoscopic environment for 40 min in one of the following groups: (i) control (atmospheric air, equivalent to a 'gasless' laparoscopic environment); (ii) a CO2-rich environment; and (iii) a helium-rich environment. Cells were then cultured for 18 h and optical density readings were used to assess the number of viable tumour cells at the end of this period. The experiment was performed twice using an identical protocol to ensure consistency in the results. In a further study, pH was continuously measured using an antimony probe during a 40 min insufflation period and for 10 min after insufflation. RESULTS: Cell growth was significantly lower after incubation in the helium-rich environment compared to both the CO2 and control groups (P < 0.001). There was a significant decrease in pH in the CO2 group which was not observed during exposure to either air or helium. CONCLUSIONS: The inhibition of tumour growth in a helium-rich environment demonstrated by this study, and the reduced incidence of port-site metastases seen in other experimental studies, suggests that the clinical use of helium as an insufflation gas may have important advantages over CO2.

Adenocarcinoma↗
PubMed1998

Chemoradiation for rectal cancer: current methods.

The options available for the surgeon treating patients with rectal cancer have multiplied over the last decade, allowing varied approaches to the disease for individual patients. The development of effective adjuvant therapy in the form of radiotherapy and chemotherapy has led to exciting results-and yet more questions to be answered. The decision to employ adjuvant therapy has led to the development of better staging modalities to improve patient selection for the various treatment protocols. The basic issue of timing of therapy-preoperative vs. postoperative-remains hotly contested, and good, prospective, randomized trials are needed before the questions can be answered. The utility of preoperative multimodality therapy in the downstaging of tumors to make curative resection or sphincter preservation possible must be examined. Advances in surgical therapy have been significant, and groups have reported excellent results with total mesorectal excision (TME) in patients without the addition of adjuvant therapy. Other important surgical issues include ultralow anterior resections with colo-anal or J-pouch anal anastomosis, and the efficacy of sphincter preservation through local excision of invasive rectal cancers with or without adjuvant therapy. Each of these issues needs further study and will have great impact on the treatment of rectal cancer as further experience is gained.

Anal Canal↗
PubMed1995

Downsizing: doing it rationally.

In the hope of achieving greater efficiency and effectiveness, many businesses are streamlining operations. Industry-specific factors and economics-driven global philosophical shifts have put hospitals under pressure to downsize. Although eliminating staff positions is a painful and emotional process, it can be done rationally.

Efficiency, Organizational↗
PubMed1993

Evaluation of the Bionic trap to quickly kill fisher (Martes pennanti) in simulated natural environments.

The Bionic trap equipped with a 10 cm aperture bait cone and cocked to eight notches quickly killed nine of nine fishers (Martes pennanti) in simulated natural conditions. Mean (+/- SE) estimated times to loss of consciousness and heartbeat were < or = 55 sec and 305 (+/- 8) sec, respectively after firing the trap. This study confirmed that the Bionic trap can be expected to render > or = 70% of captured fishers irreversibly unconscious in < or = 3 min (P < 0.05).

Animal Welfare↗
PubMed1993

Evaluation of mechanically improved Conibear 220 traps to quickly kill fisher (Martes pennanti) in simulated natural environments.

Mechanically improved Conibear 220 traps failed to render irreversibly unconscious in < or = 3 min fishers single-struck in the head-neck region, or double-struck in the neck and thorax regions. Although the Conibear 220 trap is often recommended as an alternative to the steel leghold trap, it is unlikely that it has the potential to humanely kill fisher.

Animal Welfare↗
PubMed1991

Evaluation of the Bionic trap to quickly kill mink (Mustela vison) in simulated natural environments.

The Bionic trap, with a bait placed at the back of a 6 cm aperture plastic cone, successfully killed nine of nine wild mink (Mustela vison) in simulated natural conditions. The average times to loss of consciousness and heartbeat were estimated at less than 60 (+/- 26) sec and 340 (+/- 55) sec, respectively, after firing the trap. This study confirmed that the Bionic trap can be expected to render greater than 79% of captured mink unconscious in less than or equal to 3 min (P less than 0.05).

Animal Welfare↗
PubMed1990

The C120 Magnum with pan trigger: a humane trap for mink (Mustela vison).

The C120 Magnum trap, equipped with a 66 x 69 mm pan trigger, which favored double strikes in the neck and thorax regions, successfully killed nine of nine wild mink (Mustela vison) in simulated natural conditions. Average times to loss of consciousness and heartbeat were estimated at less than 72 (+/- 24) sec and 158 (+/- 48) sec, respectively, after firing of the trap. This study confirmed that the C120 Magnum trap can be expected to render greater than 79% of all captured mink unconscious in less than or equal to 3 min (P less than 0.05). This is the first mink kill trap to meet the requisites of the Canadian General Standards Board regarding killing traps.

Animal Welfare↗
PubMed1987

A study of predominant aerobic microflora of black bears (Ursus americanus) and grizzly bears (Ursus arctos) in northwestern Alberta.

Swab specimens were obtained from nasal, rectal, and preputial or vaginal areas of 37 grizzly and 17 black bears, captured during May to June of 1981 to 1983, to determine the types and frequency of predominant aerobic microflora. Bacterial genera most frequently isolated from bears were Escherichia, Citrobacter, Hafnia, Proteus, Staphylococcus, and Streptococcus species, comprising about 65% of the isolates. Erwinia, Xanthomonas, Agrobacterium, Rhizobium, and Gluconobacter/Acetobacter were also isolated but at lower frequencies (less than 5%). Comparison of bacterial generic composition using similarity quotient values showed no appreciable differences between grizzly and black bear flora. Also, no outstanding differences in bacterial generic composition were observed among grizzly bear samples; however, differences were noted among black bear samples. Fungal genera most commonly encountered included Cryptococcus, Rhodotorula, Cladosporium, Penicillium, Sporobolomyces, and Candida. In general, the microflora of both bear types were marked by generic diversity and random distribution. The majority of microorganisms isolated from the plant samples in the study area were also found in bear samples. This observation and the presence of certain water and soil bacteria in samples from bears suggest that the predominant microflora of both grizzly and black bears were transient and probably influenced by their foraging habits and surrounding environments.

Alberta↗
PubMed1979

Myopathy and myoglobinuria in feedlot cattle.

Myopathy and myoglobinuria occurred in a group of feedlot cattle in Alberta following transportation. The condition was associated with a deficiency of selenium (Se) in grain and hay fed to these animals on their premises of origin. Clinical findings in affected animals were characterized by a normal body temperature, stiffness, sternal recumbency and the passage of red or coffee-colored urine. Treatment with injectable Se-vitamin E was followed by the recovery of most affected animals within two weeks.

Animal Feed↗
PubMed1978

Chemical modifications of the protein of carcinoembryonic antigen: associated changes in immunological activity and conformation.

Chemical substitution of the exposed residues of tryptophan, tyrosine, histidine and arginine in carcinoembryonic antigen (CEA), using appropriately selective reagents, caused no significant change in the capacity of the antigen to bind to anti-CEA serum. However, treatments of CEA with 2-hydroxy-5-nitrobenzyl bromide and tetranitromethane, both in the presence of guanidine HCl, caused a large reduction in binding capacity. Measurement of the circular dichroism spectra of all of the products showed that retention of conformation of the molecular correlated well with retained antigenic activity, whereas the large losses in capacity to bind to anti-CEA sera were accompanied by a probably the result of gross conformational changes. The tyrosine residues of CEA may be classified into three categories: (i) 3 freely reacting residues, (ii) 7 or 8 moderately buried residues and (iii) 15 unreactive residues.

Amino Acids↗
PubMed1977

Capture myopathy in pronghorns in Alberta, Canada.

From 1971 to 1975, inclusive, 594 pronghorns (Antilocapra americana) were drive trapped in Alberta; subsequently, 74 of these animals were transported to enclosures. Deaths attributable to capture myopathy (CM) occurred in 20 of the trapped pronghorns and in 17 of the pronghorns that were trapped and subsequently transported. Two neonatal pronghorns that had been pursued died with signs and lesions similar to those seen in adult pronghorns affected with CM. The diagnosis of CM was based on history, clinical signs, clinico-pathologic findings, and gross and histologic lesions. Clinical signs of CM included depression, stiffness, weakness, incoordination, recumbency, and paralysis; myoglobinuria was observed in 1 neonatal animal. Of the pronghorns that died, fewer than one-half died acutely during processing, whereas the remainder died from 1 to 13 days following their release. Gross and histologic lesions were observed in the large muscles of the hindlimbs of most affected pronghorns. Values for serum enzymes, potassium, glucose, and creatinine, were higher for drive-trapped pronghorns than for tame, hand-reared pronghorns. These findings indicated extensive damage to muscle and to other organs as a result of the capture procedures.

Alberta↗
PubMed1977

Capture myopathy in Elk in Alberta, Canada: a report of three cases.

Acute capture myopathy was diagnosed in 3 elk (Cervus canadensis). In 2 of the elk, hindlimb lameness developed within 10 days of capture. Clinical signs were not observed in the third elk, which was found dead 7 days after its capture. Elks 1 and 2 were euthanatized and all 3 animals were necropsied. In elks 1 and 2, rupture of the semi-membranosus muscle was associated with massive hemorrhage and swelling. Microscopic findings included hemorrhage, edema, myofibril fragmentation, and evidence of attempted muscular regeneration. In elk 3, several of the large muscles of the hindlimbs as well as the biceps brachii muscles of the forelimbs appeared pale, dry, and friable. Except for lack of hemorrhage and edema, microscopic findings in this elk were similar to those of elks 1 and 2.

Alberta↗