Biomedical subjects

G Bruce Schaalje

Publications and source records attributed to G Bruce Schaalje.

4 recordsLinked to original sources

PubMed2005

Treatment of biofilm infections on implants with low-frequency ultrasound and antibiotics.

Medical implants are sometimes colonized by biofilm-forming bacteria, which are very difficult to treat effectively. The combination of gentamicin and ultrasonic exposure for 24 hours was previously shown to reduce the viability of Escherichia coli biofilms in vivo. This article shows that such treatment for 48 hours reduced viable E coli bacteria to nearly undetectable levels. However, when Pseudomonas aeruginosa biofilms were implanted and treated for 24 and 48 hours, no significant ultrasonic-enhanced reduction of viable bacteria was observed. The difference in response of these 2 organisms is attributed to greater impermeability and stability of the outer membrane of P aeruginosa.

Animals↗

PubMed2005

Aerobic and resistance exercise sequence affects excess postexercise oxygen consumption.

Excess postexercise oxygen consumption (EPOC) may describe the impact of previous exercise on energy metabolism. Ten males completed Resistance Only, Run Only, Resistance-Run, and Run-Resistance experimental conditions. Resistance exercise consisted of 7 lifts. Running consisted of 25 minutes of treadmill exercise. Vo(2) was determined during treadmill exercise and after each exercise treatment. Our findings indicated that treadmill exercise Vo(2) was significantly higher for Resistance-Run compared with Run-Resistance and Resistance Only at all time intervals. At 10 minutes postexercise, Vo(2) was greater for Resistance Only and Run-Resistance than for Resistance-Run. At 20 and 30 minutes, Vo(2) following Resistance Only was significantly greater than following Run Only. In conclusion, EPOC is greatest following Run-Resistance; however, treadmill exercise is more physiologically difficult following resistance exercise. Furthermore, the sequence of resistance and treadmill exercise influences EPOC, primarily because of the effects of resistance exercise rather than the exercise combination. We recommend performing aerobic exercise before resistance exercise when combining them into 1 exercise session.

Adult↗

PubMed2004

Ultrasonic-enhanced gentamicin transport through colony biofilms of Pseudomonas aeruginosa and Escherichia coli.

The hypothesis that ultrasound increases antibiotic transport through biofilms of Escherichia coli and Pseudomonas aeruginosa was investigated using colony biofilms. Biofilms grown on membrane filters were transferred to nutrient agar containing 50 microg/ml gentamicin. A smaller filter was placed on top of the biofilm and a blank concentration disk was situated atop the filter. Diffusion of antibiotic through the biofilms was allowed for 15, 30, or 45 min at 37 degrees C. Some of these biofilms were exposed to 70-kHz ultrasound and others were not. Each concentration disk was then placed on a nutrient agar plate spread with a lawn of E. coli. The resulting zone of inhibition was used to calculate the amount of gentamicin that was transported through the biofilm into the disk. The E. coli and P. aeruginosa biofilms grown for 13 and 24 h were exposed to two different ultrasonic power densities. Ultrasonication significantly increased the transport of gentamicin through the biofilm. Insonation of biofilms of E. coli for 45 min more than doubled the amount of gentamicin compared to their noninsonated counterparts. For P. aeruginosa biofilms, no detectable gentamicin penetrated the biofilm within 45 min without ultrasound; however, when insonated (1.5 W/cm2) for 45 min, the disks collected more than 0.45 microg antibiotic. Ultrasonication significantly increased transport of gentamicin across biofilms that normally blocked or slowed gentamicin transport when not exposed to ultrasound. This enhanced transport may be partially responsible for the increased killing of biofilm bacteria exposed to combinations of antibiotic and ultrasound.

Anti-Bacterial Agents↗

PubMed2003

Combination therapy with folic acid and methionine in the prevention of retinoic acid-induced cleft palate in mice.

BACKGROUND: During formation of the secondary palate, clefting may result when critical developmental events are altered. The purpose of this study was to reduce the incidence of retinoic acid (RA)-induced cleft palate (CP) in mice by the co-administration of folic acid (FA), methionine (ME) or a combination of both. METHODS: Four groups of time-pregnant Swiss Webster mice were injected intraperitoneally with 50 mg/kg RA on gestational day (GD) 10. Likewise, 4.0 mg/kg FA and 187 mg/kg ME were administered on GD 8-11. The experiment included a control group (RA plus H2O) and three experimental groups, (RA plus therapeutic doses of FA, ME, or FA + ME). Necropsies were carried out on GD 18 and pups were analyzed for teratogenic effects. RESULTS: Litters that received no therapy exhibited 100% CP with individual pups showing 76% susceptibility. Each therapy administered separately reduced the frequency of CP to approximately 6%, and the combination of FA and ME completely prevented the occurrence of RA-induced cleft palate (0%). A second experiment was conducted in which therapy levels were decreased by 25%. Litters that did not receive therapy experienced 100% clefting and individual pups exhibited CP at 86%. These therapies administered separately did not alter significantly the frequency of cleft palate. The combined doses of FA and ME, however, lowered significantly the frequency of cleft palate to 46%. Decreases in limb and tail defects with FA + ME therapy were also observed in both experiments. CONCLUSIONS: Although FA and ME, at appropriate levels, can reduce individually the frequency of RA-induced cleft palate and other defects in mice, the results from the present study suggest that there is an additive interaction between the two therapeutic agents that can reduce further the teratogenic impact of RA. Further studies are needed to assess the mechanism of action of concomitant doses of FA and ME in the reduction of drug-induced birth defects.

Abnormalities, Drug-Induced↗