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Biomedical subjects

B Halliday

Publications and source records attributed to B Halliday.

7 recordsLinked to original sources
PubMed2000

Effects of steroids and retinoids on wound healing.

HYPOTHESIS: Anti-inflammatory corticosteroids significantly impair wound healing. Retinoids partially, but significantly, reverse this effect. Little is known about the mechanism of steroid retardation or retinoid reversal. We hypothesized that corticosteroids lower transforming growth factor-beta (TGF-beta) and insulin-like growth factor-I (IGF-I) levels and tissue deposition in wounds and that retinoids stimulate corticosteroid-impaired TGF-beta and IGF-I release and collagen production. DESIGN: Randomized controlled trial. SETTING: Wound healing research laboratory. PARTICIPANTS: Animal study. INTERVENTIONS: Four wire mesh wound cylinders were implanted subcutaneously into the backs of 72 male Sprague-Dawley rats. Wound healing was impaired by a single subcutaneous injection of 6 mg of methylprednisolone acetate (Depo-Medrol). Two preparations of retinoids were used in separate experiments: all-trans-retinoic acid and 9-cis-retinoic acid that were fed orally. MAIN OUTCOME MEASURES: Hydroxyproline content was measured in the healing tissue and TGF-beta and IGF-I levels were analyzed in the wound fluid. RESULTS: Methylprednisolone treatment significantly decreased TGF-beta and IGF-I levels in the wound fluid and hydroxyproline content in the tissue (P<.05). Oral all-trans- and 9-cis-retinoic acid partially reversed the TGF-beta and IGF-I decrease and significantly increased hydroxyproline content toward normal levels (P<.05). Oral all-trans-retinoic acid enhanced collagen deposition, TGF-beta and IGF-I levels over normal chow fed control animals (P<.05). CONCLUSIONS: Steroids and retinoids have antagonistic effects on growth factors and collagen deposition in wound healing. These effects can be relevant for treatment options in a clinical setting.

Alitretinoin↗
PubMed1993

The effects of phonophoresis with corticosteroids: a controlled pilot study.

Although physical therapists and physicians often treat patients with local musculoskeletal inflammation using topically applied steroids enhanced with ultrasound, there is a paucity of research confirming that phonophoresis significantly enhances drug diffusion. The purpose of this study was to determine if ultrasound enhances the diffusion of transdermally applied corticosteroids. Diffusion was measured secondarily in terms of collagen deposition [estimated by levels of hydroxyproline in polytetrafluroethylene (ePTFE) tubing] and cellular activity (measured by levels of DNA). Sixteen pieces of ePTFE tubing were subcutaneously implanted on the dorsum of five mini Yucatan pigs. Pairs of tubing were randomly assigned to sham control or treatment groups. Over the paired ePTFE tubes in the treatment groups, a single transdermal application of hydrocortisone acetate (HC) or dexamethasone (DX) was applied to the skin by rubbing, sonating with the drug mixed in the acoustic gel (1.5 W/cm2, 1 MHz, 5 minutes), or injecting the drug into the tubing. Four additional ePTFE tubes were threaded in the extremities, two submuscularly and two subtendinously, with random assignment to a sham control or a DX sonation treatment group. At the end of a week, the mean hydroxyproline levels in the swine were lower than expected (mean = 9.3 micrograms/cm compared to an expected mean = 22.2 micrograms/cm). Comparing the control and skin-applied groups with the injected and sonated treatment groups, the hydroxyproline was found to be 50% lower in the DX-injected, DX-sonated, and HC-injected sites. However, statistically there were no significant differences in DNA or hydroxyproline levels between the HC subcutaneous control and treatment groups or the DX submuscular and subtendinous groups. There was a significant main effect of group on hydroxyproline levels in the group of DX-treated, subcutaneously implanted ePTFE tubes (p = 0.001). Post hoc testing revealed a significant difference between the skin-rubbed and control groups together compared to the DX-injected and DX-sonated groups together (p = 0.001). These findings indicate that the effects of phonophoresed DX can be measured in terms of reduced collagen deposition as far down as the subcutaneous tissue but not in the submuscular or subtendinous tissue. However, a single application may not have a measurable effect on cellular activity after 7 days of healing. The unusually low level of hydroxyproline across all groups suggests that phonophoresis with steroids may have had a systemic as well as a local effect.

Administration, Cutaneous↗
PubMed1992

Thrombolytic therapy: impact on coronary care in a district general hospital.

The introduction of routine thrombolytic therapy in the Cardiac Care Unit (CCU) of a District General Hospital has resulted in an increased demand for admission particularly in the 70+ age group. Complications and side effects of such treatment have been similar to those reported in several large multicentre trials. The percentage of patients with myocardial infarction receiving thrombolysis has increased to 60% with the commonest reason for withholding of such treatment being the lack of ECG changes. Mortality rates have fallen and there has been an increased referral rate for urgent angiography. To maximise benefit CCU's should encourage early direct admission and ensure that, if not present on site, facilities for angiography can easily be arranged.

Aged↗
PubMed1986

Oxygen as an antibiotic. A comparison of the effects of inspired oxygen concentration and antibiotic administration on in vivo bacterial clearance.

Since prophylactic antibiotics and changes in tissue partial pressure of oxygen may affect bacterial clearance by different mechanisms, we tested the effects of hypoxia, hyperoxia, and normoxia with and without antibiotic administration on bacterial clearance. We found that improving tissue oxygenation by administration of normobaric oxygen decreased infectious necrosis as effectively as prophylactic antibiotic administration and that improved tissue oxygenation and antibiotic administration had an additive effect. We believe that a fraction of inspired oxygen of 45% should be added to prophylactic antibiotics as standard perioperative and postoperative care.

Ampicillin↗
PubMed1984

Oxygen as an antibiotic. The effect of inspired oxygen on infection.

Granulocytes' in vitro bactericidal capacity for certain bacteria depends on an adequate environmental oxygen supply. Oxygen available to granulocytes in infected tissue is decreased by local conditions and can be altered significantly by small changes in its inspired concentration. We modified Burke's and Miles' bacteria-injection model in animals to test the effect of breathing 12%, 21%, and 45% oxygen on the size of lesions produced by intradermal injections of Escherichia coli. Moderately increased inspired oxygen concentrations (fraction of inspired oxygen [Flo2]) significantly decreased the size and number of necrotic lesions, whereas hypoxia increased both. Increasing Flo2 to 45% after three and 24 hours of hypoxia also significantly decreased lesion size. Suppression of infection by moderate hyperoxia is comparable with that reported by Burke after timely, adequate doses of type-specific antibiotics.

Animals↗