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Biomedical subjects

T W Lewis

Publications and source records attributed to T W Lewis.

5 recordsLinked to original sources
PubMed2004

Copper/metal ratios in the gills of rainbow trout (Oncorhynchus mykiss) provide evidence of copper exposure under conditions of mixed-metal exposure.

Previous work has suggested that the ratio of copper residues to zinc in the gills of rainbow trout may indicate short-term exposure to increased levels of waterborne copper. However, the effect of exposure to a combination of increased copper and zinc concentrates in the water column was unknown. We exposed rainbow trout to 8 +/- 2 microg L(-1), 40 +/- 2 microg L(-1) and 90 +/- 9 microg L(-1) of waterborne copper and 21 +/- 3 microg L(-1), 129 +/- 40 microg L(-1), and 202 +/- 40 microg L(-1) of waterborne zinc in a 2-factor experiments and gill copper and zinc residues were examined. Other gill parameters analyzed included the concentrations of calcium, magnesium, sodium, and potassium, liver copper and zinc concentrations and plasma copper, calcium, sodium, and potassium are also reported here. Copper residues in the gill filaments were significantly higher in the highest level of copper exposure (high Cu, 4.06 microg g(-1); low Cu 2.41 microg g(-1); 0 Cu 2.01 microg g(-1); P = 0.001), whereas no differences were seen in zinc concentrations at any treatment level. Gill sodium and plasma calcium concentrations were also decreased at the highest waterborne copper concentrations. Although copper-zinc ratios in the gills were significantly different between the highest and lowest copper treatments (P = 0.002, F = 6.59), copper-sodium and copper-magnesium ratios were more sensitive to waterborne copper exposure (P = 0.001, F = 17.91 and P = 0.002, F = 15.45, respectively). These copper-metal ratios may be better indicators of copper loading in the water column.

Animals↗
PubMed2001

A novel interactive electronic protocol review system.

This report describes a new protocol review system which was designed as a Lotus Notes database. This system encompasses all elements of investigator protocol generation, review and approval by the laboratory animal veterinarian and institutional animal care and use committee (IACUC), and notification of approval to personnel responsible for animal ordering. Unique features of the system are interactive dialog between IACUC members and the investigator and confidential protocol discussion among IACUC members. The advantages of the system are multiple: 1. it allows for interactive protocol discussion online; 2. it is an essentially paperless process; 3. inclusion of the outside IACUC member is easily accomplished by using an offsite personal computer and secure remote local-area network access; 4. the time required for protocol generation, review, and approval is streamlined due to the automatic features of the database and the speed of e-mail; and 5. all documentation relating to the protocol and the approval process is archived online.

Animals↗
PubMed1993

A comparison of peripheral nerve repair using an absorbable tubulization device and conventional suture in primates.

Median nerve regeneration was studied in 30 adult primates after repair by microsurgical suture or tubulization with a nonwoven, bioabsorbable, polyglycolic acid device. The two methods were compared electrophysiologically and histologically 6 and 12 months after repair. The electrophysiology included recording of electrically evoked compound action potentials and subsequent determination of threshold, conduction velocity, amplitude, and area above the baseline for each component. Measurements were obtained before nerve transection and at the time of biopsy by stimulating both proximal and distal to the transection site. Analysis of all electrophysiological parameters revealed no statistically significant differences (p less than 0.05) between the two repair techniques. Histopathology included examination of cross sections proximal and distal to the repair sites and longitudinal sections through the coaptation site. End organs (Meissner's and Pacinian corpuscles and muscle) were sectioned to determine the degree of reinnervation. No significant differences between the repair techniques were observed by histological analysis of these sections. These evaluations indicated that the tubulization repair technique produced results comparable to that of the suture technique.

Electrophysiology↗
PubMed1990

Evaluation of the Unilink microvascular anastomotic device in the dog.

This experimental study reports the evaluation of a mechanical, non-suture technique for the repair of small blood vessels under the operating microscope. The method uses the Unilink implantable pinned rings on which the vessel ends are everted 90 degrees and impaled on small pins. An instrument approximates the rings and completes the anastomosis. The device was used for the end-to-end anastomosis of 80 vessels in ten beagle dogs. Both arteries (ulnar and saphenous) and veins (cephalic and saphenous) were included in the study. Vessels were assessed for patency and harvested for histologic examination and scanning electron microscopy at 4-, 16-, and 32-week implantation times. Both longitudinal and cross sections were stained using hematoxylin and eosin, Verhoeff-Van Gieson techniques for elastin, and a modified Masson's trichrome for muscle and collagen, and examined under light microscopy. Scanning electron microscopy (SEM) was completed on longitudinally bisected anastomoses. Patency rates, histology, and SEM at all implantation times of the mechanical anastomoses compared favorably with experimental investigations of suturing techniques that have appeared in the literature. This microvascular anastomotic technique provided a rapid, safe, and efficacious method for the end-to-end repair of severed peripheral arteries and veins in the dog model.

Anastomosis, Surgical↗