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Biomedical subjects

M C Robson

Publications and source records attributed to M C Robson.

At least 109 records · Page 6Linked to original sources
PubMed1987

Experimental demonstration of the immunogenicity of silicone-protein complexes.

Although silicones, as a class, are nontoxic in animal and tissue studies, implanted silicone prostheses and medical devices are associated with various local and systemic host inflammatory reactions. They also have been associated with a form of autoimmune disease. To test the hypothesis that silicones may evoke an immunologically mediated inflammatory reaction, 10 guinea pigs were stimulated for 1 month with intraperitoneal injections of sterile medical-grade silicone oil admixed with homologous serum and complete Freund's adjuvant. Ten controls were stimulated with saline. Four additional animals were passively sensitized with splenic homogenates from four sensitized animals. Intradermal antigenic challenges consisted of silicone-homologous serum, pure silicone, saline-homologous serum, and purified protein derivative. Cutaneous reaction patterns were graded grossly and microscopically. Silicone-serum and purified protein derivative antigens evoked three to four times greater palpable lesions in all 10 actively and all 4 passively sensitized animals at approximately 24 h compared to controls. Biopsies showed a moderate to marked lymphocytic infiltrate. Control sites and naive animals showed only edema at the challenge sites. The data suggest that silicone-protein complexes are potentially immunogenic.

Animals↗
PubMed1987

Experimental and clinical observations on frostbite.

Experimental ischemia by the classic frostbite rabbit ear model clearly defined the role of thromboxane as a mediator of progressive dermal ischemia in frostbite injuries. The therapeutic groups consisted of the antiprostanoids, methylprednisolone, and aspirin combined with anti-thromboxane agents Aloe vera and methimazole, while the control group received no therapy. Survival was measured by planimetry for all groups. No tissue survival was evident in the frostbite control group. Methimazole treatment allowed 34.3% survival, Aloe vera 28.2% survival, aspirin 22.5% survival, and methylprednisolone 17.5% survival. The data compare the results of a modified frostbite protocol using ibuprofen with therapeutic modalities used by other clinical services. Of 154 patients treated for frostbite from 1982 to 1985, 56 were treated with our frostbite protocol; 98 were treated with other modalities. Of the 56 protocol patients, 18 suffered 1st degree frostbite, 25, 2nd degree frostbite, and 13, 3rd degree frostbite. For all degrees of frostbite, 67.9% healed without tissue loss, 25.0% healed with partial tissue loss, and 7% required amputation (P less than .001). Of the patients not on protocol, 11 suffered 1st degree frostbite, 51, 2nd degree frostbite, and 36, 3rd degree frostbite. Of these, 32.7% healed without tissue loss, 34.6% healed with tissue loss, and 32.7% required amputation. The morbidity of progressive dermal ischemia in frostbite may be decreased by the therapeutic use of inhibitors of the arachidonic acid cascade.

Adolescent↗
PubMed1987

The role of thromboxane in experimental inadvertent intra-arterial drug injections.

Inadvertent intra-arterial injection of drugs produces a well-defined clinical syndrome whose pathophysiology remains unclear. This study was designed to determine the role of the inflammatory mediator, thromboxane, in intra-arterial drug injections. The rabbit ear model, as described by Kinmonth and Sheppard, was used. Five of the experimental groups were treated with specific or nonspecific thromboxane blocking agents and two groups served as controls. Immunohistochemical staining of the control ears showed elevated levels of thromboxane within the first 6 hours postinjury. The specific thromboxane blocking agents, methimazole and Aloe vera, showed almost complete blockade of thromboxane production. The percentage of ear survival was significantly greater in the group treated with topical Aloe vera (p less than 0.05) and even greater survival was achieved in the combined Aloe vera/methimazole group (p less than 0.01). On the basis of these results, we have begun treatment of such injuries with specific and nonspecific thromboxane blocking agents.

Animals↗
PubMed1987

Squamous cell carcinoma occurring in hidradenitis suppurativa.

A patient is described who had severe hidradenitis suppurativa of the perineum for three years. Excision of the involved area demonstrated a well-defined squamous cell carcinoma. A review of the literature shows only 12 reported cases of squamous cell carcinoma occurring in patients with hidradenitis suppurativa; most patients developing cancer in chronic inflammatory lesions have had longstanding disease. In this case there was a short interval between disease onset and the occurrence of a squamous cell carcinoma.

Carcinoma, Squamous Cell↗
PubMed1987

Biosynthetic skin substitute versus frozen human cadaver allograft for temporary coverage of excised burn wounds.

During the past 2 years a multicenter study was performed comparing Biobrane (Woodroof) and frozen cadaver allograft as temporary dressings on freshly excised full-thickness burns before the application of autograft. Each biologic dressing was evaluated with respect to the other on the same patient. Seventy-one patients were evaluated. The mean burn size was 35 +/- 20% with a mean full-thickness burn of 28 +/- 20%. Mean patient age was 34 +/- 21 years. Overall survival was 82%. The mean time of wound coverage was 10.2 +/- 6.7 days. There was no significant difference in the number of dressing changes, area changed, purulence, autograft take, and final results between allograft- and Biobrane-covered sites. There were no complications following use of either Biobrane or allograft. We conclude that Biobrane is as effective as frozen human cadaver allograft for the temporary coverage of freshly excised full-thickness burn wounds before autografting.

Adult↗
PubMed1987

Control of burn wound sepsis: a comparison of in vitro topical antimicrobial assays.

The Minimal Inhibitory Concentration (MIC) and the Nathan's Agar Well Diffusion (NAWD) tests are bacterial antimicrobial susceptibility predictors. Some suggest that the NAWD is not as reliable as the MIC test. We compared the MIC and NAWD tests as to how well they agree to bacterial sensitivity or resistance and predicted clinical outcome of burn wound infections. Using 65 bacterial isolates from burned patients, the MIC and NAWD tests agreed in 60.0% of the isolates (vs. a perfect agreement of 100%, p less than 0.001), implying that these tests are not interchangeable. From 18 burned patients treated with nitrofurazone or mafenide acetate, 28 infectious isolates were evaluated. The outcome of these infections was correctly predicted by NAWD in 92.8% and the MIC in 72.0% of the cases (p less than 0.05). It seems that for burns treated with topical antimicrobials, the NAWD is a more reliable predictor of bacterial susceptibility.

Bacteria↗
PubMed1987

Statistical analysis and study design in plastic and reconstructive surgical research.

Appropriate study design and proper statistical analysis are necessary ingredients for improving the quality and reliability of the information in journal articles. General surgery and plastic surgery articles were compared for principal author's academic degree, a Ph.D.'s presence as a coauthor, the study type, the presence of statistical analysis, the analysis' appropriateness, and the types of errors in study design or statistical analysis. Ph. D. authorship was associated with increased percentage of articles using statistical analysis. When compared with general surgery articles, plastic surgery articles performed four times fewer statistical analyses. However, when statistical analyses were performed, there were few differences between these two specialties. Although there were no differences in the types of statistical analysis errors, there were differences in the types of study design errors. The causes of these discrepancies may lie in the nature of plastic surgery; they may be reduced by adherence to Feinstein's principles of study design and result interpretation.

Authorship↗
PubMed1986

Antithrombin, prekallikrein, and fibronectin levels in surgical patients.

Antithrombin (AT), prekallikrein (PK), and fibronectin (FN) levels were measured in the plasma of 290 patients. The mean (+/- SD) lowest AT level measured in 287 patients was 70% +/- 18% (normal, 75% to 120% of control). The mean lowest AT level in 81 septic patients (49% +/- 17%) was significantly lower than in the 206 patients without sepsis (78% +/- 22%). The mean AT level in 60 patients who died (42% +/- 22%) was significantly lower than in 227 patients who lived (78% +/- 19%). The mean lowest PK level measured in 71 patients was 42% +/- 17% (normal, 80% to 120%). The mean PK level in 32 septic patients (26% +/- 12%) was significantly lower than in 39 patients who were not septic (54% +/- 19%). The mean lowest FN level measured in 45 patients was 193 +/- 86 micrograms/mL (normal, 160 to 240 micrograms/mL). The mean FN level in 15 septic patients (128 +/- 72 micrograms/mL) was significantly lower than in the 30 nonseptic patients (266 +/- 84 micrograms/mL). Following AT, PK, and FN levels in critically ill surgical patients may allow earlier diagnosis and more effective treatment of sepsis.

Antithrombins↗
PubMed1986

The effect of microbial contamination on musculocutaneous and random flaps.

Although musculocutaneous flaps have been shown to have the ability to withstand a greater inoculum of bacteria than random flaps, it has not been shown that the musculocutaneous flap has any greater ability to decrease the bacterial population in a contaminated wound. In this series of experiments, granulating wounds were developed containing 10(4), 10(5), or 10(6) bacteria per gram of tissue. These contaminated wounds were then covered either with musculocutaneous flaps, random flaps, or left uncovered as a control. In the heavily contaminated wounds containing 10(6) bacteria per gram of tissue, neither type of flap was able to prevent bacterial proliferation and all flaps dehisced. In the minimally contaminated wounds containing 10(4) bacteria per gram of tissue, both the musculocutaneous and random flaps achieved wound healing and decreased the bacterial level in the wound. However, in the intermediate group containing 10(5) bacteria per gram of tissue, musculocutaneous flaps lowered the bacterial count and allowed wound closure, whereas the random flaps did not control the bacterial growth and failed. Therefore, in the moderately contaminated wound, musculocutaneous flaps are advantageous and can decrease bacterial counts and obtain successful closure when random flaps cannot.

Animals↗
PubMed1986

Bioprosthesis in hand surgery.

In 1965, Carpentier coined the term bioprosthesis to distinguish the characteristics of glutaraldehyde-treated porcine heart valves from untreated or synthetic valves. Observation that the valves functioned normally but were not incorporated by the host has stimulated interest in similarly preserved materials for use in hand surgery. This report outlines work that was initiated to learn the effects of glutaraldehyde treatment on tendon and a reticular substitute. In over 56 experiments with a chicken model, experience with glutaraldehyde-treated tendon grafts shows no acute rejection. There is good function clinically by 8 weeks with proximal fibrous ingrowth seen histologically. By 12 weeks, distal ingrowth has occurred. There is no ingrowth into the tendon graft within the fibro-osseous tunnel. Mechanical testing of the implant system shows a peak load at failure of 1.86 +/- 0.43 pounds and at 24 weeks it is 6.53 +/- 2.6 pounds. The failure site at time zero was distal. By 12 weeks, the distal attachment strengthened and the proximal attachment failed at a greater load. An interpositional substance with potential uses in hand surgery has been prepared by glutaraldehyde treatment of mammalian pericardium. Possible uses include interposition between fractured phalanx and the extensor tendon. This has been evaluated in feasibility studies in a rabbit model.

Animals↗
PubMed1986

Combined prostacyclin and thromboxane synthetase inhibitor UK 38485 in flap survival.

Thromboxane, a prostanoid derivative, is a central mediator of the progressive dermal ischemia seen in the distal dying flap. Prostacyclin; a vasoactive prostanoid derivative, has been found to enhance ischemic flap survival. This study examines the effects of prostacyclin and UK 38485 (specific thromboxane synthetase inhibitor), separately and combined, in axial flap survival in the pig. Each increased flap survival over control flaps; their combined use demonstrated an even greater flap survival (p less than 0.005).

Animals↗
PubMed1986

Mandibular fractures in an urban trauma center.

The hospital records of 307 patients sustaining mandibular fractures between 1980 and 1984 were reviewed. The patient population consisted of 79% males, with precipitating events usually being fist fights (47%) and assaults with a blunt object (18%). The most common fracture involved the body (30%), followed by the angle (21%) and the condyles (19%). Intermaxillary fixation (IMF) was the preferred method of treatment (42%); however, a large number of patients were treated by internal fixation (31%) or external stabilization (11%). Despite the large number with internal fixation procedures, the complication rate was relatively low (18%). This review suggests changing trends in mandibular fractures. Motor vehicle accidents no longer comprise the most common etiology, so that condylar fractures are no longer the most common, and fractures of the body and angle are more common. Although most patients still are initially treated by intermaxillary fixation, the number of open reductions appears to be increasing. Despite this trend, the complication rate has remained relatively low.

Adult↗
PubMed1986

Diabetic foot infections: fate of the contralateral foot.

Following an initial report urging conservative management of severe diabetic foot infections, the authors have managed 45 patients with a minimum 3-year follow-up. By using standard principles for soft-tissue infection, 78 percent of the patients healed minor amputation sites and maintained biped ambulation following the initial foot involvement. Only 22 percent required a major amputation at the time of the initial foot involvement. The 45 patients were followed and 22 (or 49 percent) developed a severe infection involving the contralateral foot within 18 months. Although 15 of the 22 patients developing contralateral infection (or 33 percent of the total series) required some type of amputation on the contralateral foot, the conservative approach allowed 64 percent of the patients with severe infections in both feet to maintain biped ambulation. This included 40 percent of the patients who required amputation of some portion of both feet.

Adult↗
PubMed1986

Therapeutic efficacy of Biobrane in partial- and full-thickness thermal injury.

Cadaver allograft skin, porcine xenograft skin, and amniotic membranes have been proved to be adequate temporary thermal wound coverings in four clinical situations: coverage of shallow wounds while awaiting epithelialization (SW), coverage of deep wounds after eschar excision (DEW), coverage of widely meshed autograft while awaiting closure of interstices (AC), and coverage of massive donor sites (DS). This study was undertaken to evaluate the therapeutic efficacy of a new biosynthetic bilaminate dressing, Biobrane. Two hundred one applications of Biobrane were studied in 82 SW, 46 DEW, 19 AC, 54 DS. A total of 124 applications were left in place until healing occurred, with a mean healing time of 12.8 days. Sixty of SW, 10/46 DEW, 10/19 AC, and 44/54 DS remained intact until complete healing. Only four DEW, two SW, and 0 AC applications had to be removed because of suppuration. Twenty five of the applications (SW and DEW) with the Biobrane glove had rare complications.

Adhesiveness↗
PubMed1986

Infection control in burn patients.

The article primarily deals with infection control practices relating to the burn patient. Burn infections have an endogenous origin rather than an exogenous one. Infection control practices are similar to routine infection surveillance but are also distinctly different.

Anti-Bacterial Agents↗
PubMed1985

Cefoxitin concentration in wound fluid.

The concentration of cefoxitin was determined in fluid obtained from human surgical wounds during the first postoperative day. Intravenous administration of cefoxitin sodium at a dosage of 1 or 2 g every six hours rapidly produced wound-fluid concentrations greater than the minimal inhibitory concentration for most susceptible organisms. After three hours, wound-fluid concentrations surpassed the serum concentrations of cefoxitin. The higher dosage resulted in higher wound-fluid levels.

Cefoxitin↗
PubMed1985

Surgical delay and arachidonic acid metabolites: evidence for an inflammatory mechanism: an experimental study in rats.

In a rat skin flap model, surgical delay produced an increase in the production of arachidonic acid metabolites, with a derangement of the normal equilibrium between PGE2 and PGF2 alpha and a marked increase in the vasoconstrictive substance, thromboxane. During the delay period, there is a gradual decrease in tissue levels toward normal. Subsequent elevation of the delayed flap produces a blunted response in thromboxane production, an increase in PGE2 levels and increased flap survival. Acute elevation of an undelayed flap produced more marked elevation of all metabolites, with prolonged elevation of the vasoconstrictive PGF2 alpha and thromboxane, progressive ischemia and decreased flap survival. A key role in inflammation, mediated by these inflammatory mediators, is postulated in the mechanism of delay.

Animals↗