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Biomedical subjects

B P O'Donnell

Publications and source records attributed to B P O'Donnell.

6 recordsLinked to original sources
PubMed2004

Coronary stent strut size dependent stress-strain response investigated using micromechanical finite element models.

Cardiovascular stents are metal scaffolds that are used in the treatment of atherosclerosis. These devices are typically composed of very thin struts (< or = 100 microm thickness, for coronary applications). At this size-scale the question arises as to the suitability of using bulk material properties in stent design. This paper investigates the use of finite element analysis to predict the mechanical failure of stent struts, typical of the strut size used in coronary stents. 316 L stainless steel in uniaxial loading was considered. To accurately represent the constitutive behavior of the material at this size-scale, a computational micromechanics approach was taken involving an explicit representation of the grain structure in the steel struts, and the use of crystal plasticity theory to represent the constitutive behavior of the individual grains. The development of the finite element models is discussed and results are presented for the predictions of tensile mechanical behavior as a function of strut thickness. The results showed that using this modelling approach, a size effect, already seen experimentally, is produced. This has significant implications for stent design, especially in the context of the desire to produce smaller stents for small bore neurovascular and peripheral artery applications.

Biocompatible Materials↗
PubMed1999

The surgical treatment of traumatic hematoma of the auricle.

BACKGROUND: The auricular hematoma occurs secondary to trauma and can present a therapeutic dilemma for clinicians. Early intervention can be limited to simple incision and drainage. Delay in treatment may allow the growth of ectopic fibroneocartilage derived from the damaged perichondrium. Removal of this abnormal tissue is imperative to avoid permanent ear deformity. OBJECTIVE: Surgical intervention was utilized to treat auricular hematomas in two teenage boys. METHODS: The auricular hematomas were treated by raising a cutaneous flap over the injury site. The clot and serosanguinous fluid were drained and, because the injuries were 1 month old, the developing plate of fibroneocartilage and associated perichondrium was extirpated. The exposed cartilage was fenestrated prior to repairing the cutaneous flap. RESULTS: Both auricles healed without evidence of fibrosis or distortion. CONCLUSION: Appropriate surgical intervention can avoid the cosmetic deformity associated with an auricular hematoma (ie, cauliflower ear).

Adolescent↗
PubMed1995

Thin tangential excision of tattoos.

BACKGROUND: There are many techniques used to remove professional tattoos. Each method can be complicated by hypertrophic scarring, pigmentary changes, and/or insufficient pigment removal. OBJECTIVE: To study the results of precise, thin, tangential excisions of professional tattoos. The posttreatment migration of dermal tattoo pigment was also evaluated. METHODS: Five healthy white males had their professionally placed tattoos excised at a depth of 0.008 in (0.2 mm) using a Brown dermatome. Pre- and posttreatment biopsies were used to measure the depth of the tattoo pigment. RESULTS: At 3 months posttreatment, four patients had no significant scarring and three patients retained only scattered flecks of tattoo pigment. Each patients demonstrated migration of the deeper dermal pigment to a more superficial level. CONCLUSION: A superficial, tangential excision of a professional tattoo by a Brown dermatome is a viable, low-risk, inexpensive procedure.

Adult↗
PubMed1992

Rapp-Hodgkin ectodermal dysplasia.

Rapp-Hodgkin syndrome is a rare condition that is characterized by ectodermal dysplasia and palatal abnormalities. We describe a 24-year-old white woman who has Rapp-Hodgkin syndrome that is associated with a chronic palmar keratoderma, which is a finding that has not been previously reported. We review the literature, assign the clinical features into major and minor categories, and suggest therapeutic interventions to limit the significant sequelae of this autosomal dominant syndrome.

Adult↗
PubMed1992

Suramin-induced skin reactions.

BACKGROUND AND DESIGN: Suramin sodium, a polysulfonated naphthylurea, has been used for more than 70 years as a chemotherapeutic agent for a variety of diseases. In a phase II trial of suramin, 20 patients with metastatic prostate carcinoma refractory to hormonal manipulation were evaluated retrospectively for evidence of skin toxicity. RESULTS: Three types of skin reaction were noted: generalized, erythematous, maculopapular eruption (10 patients); keratoacanthoma (two patients); and disseminated superficial actinic porokeratosis (one patient). A total of 15 episodes of some form of skin reaction occurred in 13 patients. The maculopapular eruptions resolved in 3 to 5 days despite continued treatment with suramin. CONCLUSIONS: Cutaneous toxicity was a frequent and, often, self-limited side effect of suramin therapy, occurring in 13 (65%) patients. Keratoacanthoma and disseminated superficial actinic porokeratosis have not previously been reported to occur with suramin therapy. The immunosuppressive effect of suramin may induce the keratoacanthoma and disseminated superficial actinic porokeratosis lesions.

Carcinoma↗