Biomedical subjects

Michael Walker

Publications and source records attributed to Michael Walker.

26 records · Page 2Linked to original sources

PubMed2003

Antimicrobial properties of silver-containing wound dressings: a microcalorimetric study.

The studies reported here have been undertaken to assess the potential use of isothermal microcalorimetry in studying the antimicrobial efficacy of wound dressings that contain antimicrobial agents. The microcalorimetric technique allows non-invasive and non-destructive analysis to be performed directly on a test sample, regardless of whether it is homogeneous or heterogeneous in nature. Microcalorimetry is an established procedure that offers quantitative measurements and has the distinct advantage over traditional antimicrobial test methodologies in that calorimetric measurements are made continuously over real-time, thus the dynamic response of microorganisms to an antimicrobial agent is observed in situ. The results described in this paper are for interaction of two silver-containing wound care products AQUACEL Ag Hydrofiber (ConvaTec, Deeside, UK) and Acticoat 7 with SILCRYST (Smith and Nephew Healthcare, UK) with the wound pathogenic organisms Staphylococcus aureus and Pseudomonas aeruginosa. Both dressings are shown, microcalorimetrically, to have the capacity to kill these common wound pathogens within 1-2 h of contact. A dose-response study was conducted with the AQUACEL Ag dressing. Microcalorimetry is shown to be rapid, simple and effective in the study of the antimicrobial properties of gel forming wound dressings.

Anti-Infective Agents↗

PubMed2003

Osteomyelitis secondary to trauma involving the proximal end of the radius in horses: five cases (1987-2001).

OBJECTIVE: To determine clinical, radiographic, and scintigraphic abnormalities in and treatment and outcome of horses with trauma-induced osteomyelitis of the proximal aspect of the radius. DESIGN: Retrospective study. ANIMALS: 5 horses. PROCEDURE: Data collected from the medical records included signalment; history; horse use; degree of lameness; radiographic, ultrasonographic, and scintigraphic findings; treatment; and outcome. RESULTS: Duration of lameness prior to referral ranged from 14 to 60 days. Mean severity of lameness was grade 3 of 5, and all horses had a single limb affected. All horses had signs of pain during elbow joint manipulation and digital palpation over the lateral aspect of the proximal end of the radius. Radiographic lesions consisted of periosteal proliferation, osteolysis, and subchondral bone lysis. Scintigraphy in 3 horses revealed intense pharmaceutical uptake diffusely involving the proximal end of the radius. Two horses had sepsis of the elbow joint. All horses were treated with antimicrobials long-term; 1 horse was also treated by local perfusion of the radial medullary cavity through an indwelling cannulated screw. At follow-up, all horses had returned to their previous function. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that osteomyelitis of the proximal end of the radius can result from a traumatic injury to the antebrachium. Because lesions may be an extension of septic arthritis, a thorough examination of the wound area and elbow joint is recommended. Prolonged systemic antimicrobial treatment can result in a successful outcome.

Animals↗

PubMed2003

A pilot study of exercise training in adult patients with repaired tetralogy of Fallot.

BACKGROUND: Positive effects of physical training in adults with acquired heart disease have been reported. The role of exercise training in adults with congenital heart disease, however, is less well defined. OBJECTIVES: To assess the level of physical activity in adult patients with repaired tetralogy of Fallot (TOF), as well as the safety and effect of exercise training in these patients. PATIENTS AND METHODS: A questionnaire of physical activity was filled upon entering the study by the participants. Eighteen adult patients with repaired TOF were then randomly assigned to participate in a three-month structured exercise program (exercise group, nine patients) or to continue their usual exercise routine (control group, nine patients). Each patient in the exercise group received an individualized exercise program to be performed three times a week, whereas the control group was told to continue living their life as usual. Cardiopulmonary testing was performed in all patients at baseline (before randomization) and at the end of the study. RESULTS: No death or incidents occurred during the study period. All patients but one were physically inactive at the onset of the study. There was a significant increase in peak oxygen consumption in the exercise group by the end of the study (22.1 mL/kg/min [6 metabolic equivalents (METS)] versus 24.3 mL/kg/min [7 METS], P=0.049), whereas it remained unchanged in the control group (21.8 mL/kg/min [6 METS] versus 22.1 mL/kg/min [6 METS], P=0.825). CONCLUSION: In clinically stable adult patients with repaired TOF, a moderate level of exercise training improves aerobic capacity. Regular exercise should be encouraged in these sedentary patients.

Adult↗

PubMed2002

Reservoir boundaries in Brownian dynamics simulations of ion channels.

Brownian dynamics (BD) simulations provide a practical method for the calculation of ion channel conductance from a given structure. There has been much debate about the implementation of reservoir boundaries in BD simulations in recent years, with claims that the use of improper boundaries could have large effects on the calculated conductance values. Here we compare the simple stochastic boundary that we have been using in our BD simulations with the recently proposed grand canonical Monte Carlo method. We also compare different methods of creating transmembrane potentials. Our results confirm that the treatment of the reservoir boundaries is mostly irrelevant to the conductance properties of an ion channel as long as the reservoirs are large enough.

Biophysical Phenomena↗

PubMed2002

Cavernous sinus involvement by extramedullary plasmacytoma of the sphenoid sinus. An argument for the use of adjuvant chemotherapy.

A 63-year-old man with cavernous sinus involvement from extramedullary plasmacytoma (EMP) of the sphenoid sinus is described. Transient resolution of retro-orbital headache and continued progression of the locally extensive tumor were noted after chemotherapy was given following a poor response to 5400 cGy of local irradiation. To determine whether adjunctive chemotherapy will improve the outcome of these particular patients, we propose that a randomized trial comparing radiotherapy to chemoradiation be conducted.

Aged↗

PubMedDate not supplied

Controlling wound bioburden with a novel silver-containing Hydrofiber dressing.

Clinicians now recognize that both aerobic and anaerobic microorganisms have the ability to degrade or damage host tissue at a wound site through the production of a variety of enzymes and toxins. Silver-containing dressings offer one method for controlling this polymicrobial wound bioburden, and research efforts are currently ongoing to determine their efficacy against aerobic, anaerobic, and antibiotic-resistant microorganisms. The current study aimed to determine the antimicrobial activity of a new silver-containing Hydrofiber dressing (AQUACEL Ag) on both aerobic and anaerobic microorganisms, using the zone-of-inhibition method. This method provides a measure of the ability of the dressing to make available a sufficient concentration of silver to have an antimicrobial effect. To some extent this test mimics the clinical use of the dressing and predicts its microbicidal activity at the wound-dressing interface. The results show that the silver-containing dressing makes silver available at a dressing-agar interface at a concentration that is effective against a broad range of aerobic, anaerobic, and antibiotic-resistant microorganisms. In the context of wound healing, the results showing antimicrobial activity against antibiotic-resistant microorganisms are particularly important, as the control and eradication of these organisms is a major concern within the health care profession.

Administration, Topical↗

PubMedDate not supplied

Meniscal ossicles in large non-domestic cats.

Radiographs of the stifles of 6 species of 34 large, non-domestic cats were reviewed foremost for the presence of meniscal ossicles and then for the presence of the other potential four sesamoids. The animals in the review included 12 lions, 7 tigers, 7 cougars, 3 leopards, 3 bobcats, and 2 jaguars. Fluoroscopy, arthrography, computed tomography, necropsy, and histology were also used to evaluate the stifles of one tiger after euthanasia. Ossicles were found in the region of the cranial horn of the medial meniscus in most of the lions, tigers, leopards, and jaguars. These ossicles were found in half of the cougars but in none of the bobcats. Among the large, non-domestic cats, meniscal ossicles had been reported previously only in Bengal tigers. The lions, tigers, and leopards having meniscal ossicles appeared to have a lateral but often not a medial fabella of the gastrocnemius muscle, an observation previously unreported. Popliteal sesamoids and patellas were present in all the skeletally mature cats.

Animals↗

PubMedDate not supplied

Play-Doh and water-soaked gauze sponges as alternative bolus material for cobalt-60 teletherapy.

A study was performed to determine if carefully made boluses of either Play-Doh, or water-soaked cotton gauze sponges differed from the commercial bolus material, Superflab, in producing maximum radiation dose when irradiated with cobalt-60 photons. The radiation doses were measured with thermoluminescent dosimeters calibrated to be accurate for cobalt-60 photon energies at doses less than 10.0 cGy. The resulting radiation doses were similar when using Play-Doh, water-soaked sponges, or Superlab. Doses resulting from Play-Doh boluses more consistently approximated those of Superflab. The results of this study suggest that either Play-Doh or water-soaked cotton gauze sponges can suffice as material for carefully made bolus for cobalt-60 teletherapy.

Animals↗