Search PubMed⌕ Search

Biomedical subjects

D J Coleman

Publications and source records attributed to D J Coleman.

At least 73 records · Page 4Linked to original sources
PubMed1991

Histologic effects of contact ultrasound for the treatment of glaucoma.

The histologic effects of a contact ultrasound applicator were compared with those of the immersion applicator that is currently used clinically for the treatment of glaucoma. The applicator coupling cone uses a distensible rubber membrane that can be inflated to control stand-off distance relative to the surface of the eye. This feature allows the focal point of the therapeutic beam to be placed at selective depths. Histologic comparisons of lesions in rabbit and pig eyes showed lesions in the sclera and ciliary body that were similar to those produced by the immersion transducer when the same focal position was used. Moving the focal point to a greater depth resulted in less superficial damage, yet still produced ciliodestruction. Damage to the blood supply of the ciliary body, as found in human cadaver eyes, may be an additional mechanism of action of therapeutic ultrasound, and perhaps of other transscleral high-energy modalities.

Animals↗
PubMed1990

Correlations of acoustic tissue typing of malignant melanoma and histopathologic features as a predictor of death.

Forty-six eyes with uveal melanoma were scanned with a computerized diagnostic ultrasound system before enucleation, and light microscope sections were obtained. Tumors were characterized by ultrasonically measured dimensions and power spectrum analysis, which provided information not available in conventional A- or B-scan ultrasonography. Histopathologic features, including cell clustering pattern, cell type, pigmentation, vascularity, and necrosis, were quantified. Statistically significant correlations were found between parameters derived from the power spectrum and histologic characteristics. Patients were followed up for up to ten years with 14 deaths occurring because of metastases. Using a Cox relative risk model with histopathologic data, a risk model comprising pigmentation and cell type (P less than .0001) was obtained. Using ultrasonic characteristics, a model comprising tumor volume and scatterer concentration (P = .0062) was obtained. The results suggest that ultrasonic tissue characterization and three-dimensional biometry may provide improved in vivo prognostic indicators for uveal melanoma.

Eye Enucleation↗
PubMed1990

Cost effectiveness of three child mental health assessment methods: computer-assisted assessment is effective and inexpensive.

In order to survive severe funding reductions, community mental health centers (CMHCs) have implemented a number of systems-level interventions that attempt to minimize the impact of budget cuts on treatment effectiveness. The present study focused on ways to maintain the effectiveness of clinical assessment while lowering the assessment cost. The present study evaluated the relative cost effectiveness of three methods for collecting information and developing clinical assessment reports on children at a CMHC: (a) a traditional narrative clinical assessment report; (b) a form-style clinical assessment; and (c) a computer-assisted clinical assessment. The results revealed that the computer-assisted assessments was at least as effective as the two alternative assessment methods and only 20 percent to 45 percent as costly. The effect of using the computer-assisted assessments was reported to be favorable by therapists. While computer technology can be used to cut service delivery costs, the use of computers in CMHCs has generally been limited to administrative tasks, and clinical applications have been ignored.

Child↗
PubMed1990

Production of corneal lesions using high-intensity focused ultrasound.

In order to study the potential use of ultrasound as a noninvasive system for altering corneal curvature, we used high-density focused ultrasound at a frequency of 4.8 MHz and 7.9 MHz to produce corneal lesions in the rabbit eye. Intensity and duration threshold exposure conditions were determined for the production of minimally visible lesions. Threshold lesions were initially apparent as discrete white opacities resulting from stromal edema and disruption. Light and scanning electron microscopy of higher-energy, suprathreshold lesions revealed more extensive disruption, including the formation of a superficial stromal depression and a larger zone of edema and disorganization surrounding each lesion. Posterior stromal lamellae, endothelium, and Descemet's membrane were intact. Healing and reepithelialization resulted in a smooth corneal surface with no residual opacification. Threshold determinations predict safe exposure levels to the cornea during insonification of other ocular structures. Selective heating of the peripheral cornea using focused ultrasound may be a useful technique for correcting astigmatism.

Animals↗
PubMed1989

In vivo thickness of the human detached retina by ultrasonic signal processing.

Fourier operations on digitized radio-frequency (rf) data can provide the most sensitive measure of the thickness of thin, deterministic structures such as membranes. After deconvolution against the system transfer function, the cepstrum and the analytic signal magnitude can provide measures of membrane thickness on the order of a half-wavelength. A total of 19 patients with rhegmatogenous retinal detachments were scanned using a diagnostic ultrasound system adapted for analog to digital conversion of rf data. Data were analyzed using the signal processing techniques described above to measure retinal thickness. Recent retinal detachments tended to be significantly thicker than normal attached retinas, and thickness decreased with the age of detachment. A statistically significant correlation was found to exist between retinal thickness and the duration of detachment.

Adolescent↗
PubMed1989

Non-suture external cuff techniques for microvascular anastomosis.

Microvascular anastomosis can be achieved by eversion of the upstream vessel end over an external cuff and insertion of this into the downstream vessel. This technique, first described in 1900, was initially tested in 13 rat femoral vein anastomoses using small polythene cuffs. Two anastomoses failed and 11 were patent at 7 days. After control studies, in 16 rat epigastric flaps the femoral vein in the vascular pedicle was divided and anastomosed using an external cuff. Thirteen flaps survived. The principles underlying this method appear sound, and form the basis for microvascular anastomotic devices currently being developed.

Anastomosis, Surgical↗
PubMed1989

Ultrasonically induced disruption and hemolysis of vitreous hemorrhages.

High-intensity focused ultrasound was used to insonify simulated vitreous hemorrhages in two in vitro models and one in vivo animal model. Histopathologic evaluation of the treatment effect was performed with light and electron microscopy. Ultrasonic parameters resulting in histopathologically proven disruption and hemolysis of intravitreal blood were investigated. Most important in obtaining this effect were the temporal average acoustic power and pulse repetition rate of the applied ultrasonic beam. Accurate positioning of the therapeutic beam and visualization of internal spatio-temporal response patterns in the blood during insonification were monitored via simultaneous diagnostic B-mode imaging. Results suggested that high-intensity focused ultrasound might facilitate the two major mechanisms involved in the natural resorption process of vitreous hemorrhages namely hemolysis and surface-dependent phagocytosis.

Animals↗
PubMed1989

Perfluorocarbon liquids in the management of traumatic retinal detachments.

Low viscosity perfluorocarbon liquids were used as an intraoperative tool during vitrectomy for retinal detachment (RD) after penetrating ocular trauma. These liquids are immiscible with water and have specific gravities from 1.8 to 1.9. Intraoperatively, the perfluorocarbon liquids flattened the retina in 14 eyes by displacing the subretinal fluid through peripheral breaks. Posterior retinotomy was not required for internal drainage of subretinal fluid. Pooled subretinal fluid was displaced from the macular area in five patients. The perfluorocarbon bubble mechanically stabilized the retina during epiretinal membrane dissection. The perfluorocarbon liquid was removed and replaced perfluorocarbon gas or silicone oil. In 11 patients followed for more than 6 months after the final surgery, eight (73%) eyes were anatomically successful, with six (54.5%) gaining visual acuity of 20/400 or better.

Adolescent↗
PubMed1989

A christening party outbreak of haemorrhagic colitis and haemolytic uraemic syndrome associated with Escherichia coli O 157.H7.

A point source outbreak of haemorrhagic colitis due to Escherichia coli O 157.H7 producing verocytotoxin (VT), took place following a christening party in Birmingham in June 1987. Twenty-six people were affected, six were admitted to hospital and one developed haemolytic uraemic syndrome: there were no deaths. VT + E. coli O 157.H7 was isolated from 13 (57%) of 23 faecal specimens from affected people and from 3 (9%) of 33 specimens from asymptomatic people. Free VT was detected in the faeces of one further asymptomatic person. Illness was associated with eating turkey-roll sandwiches (P less than 0.001) suggesting that cold meats might be an important source of infection.

Adolescent↗
PubMed1988

Custom-made nipple-areola prostheses in breast reconstruction.

The nipple-areola prosthesis is a useful temporary or permanent adjunct to breast reconstruction. The commercially available prostheses, however, are unable to reflect the remarkable normal variation in this anatomical feature. We describe the production and use of custom-made prostheses using the remaining nipple-areola complex as a template. Their success in 72 patients has led us to adopt such prostheses as routine in breast reconstruction.

Breast↗
PubMed1988

Histopathologic effects of ultrasonically induced hyperthermia in intraocular malignant melanoma.

Four cases of human intraocular malignant melanoma were treated with ultrasonically induced hyperthermia immediately before enucleation. Tumors were treated in two regimens: 30 minutes at 43 degrees to 45 degrees C and 5 minutes at greater than 50 degrees C. Temperatures were estimated from applied power levels, based on empirical data and mathematical models. Histopathologic changes observed in human tumors were compared with changes seen in malignant melanoma xenografts in athymic nude mice which were treated with ultrasonically induced hyperthermia for 30 minutes at 42 degrees to 46 degrees C. The effects of treatment were similar to changes seen in the animal model treated under analogous conditions: increased intercellular spacing, cytoplasmic vacuole formation, clumping of chromatin, breaks in cell membranes, and swelling and collapse of cells. Perivascular and peripheral zones sometimes showed decreased damage levels. The high temperature (greater than 50 degrees C) technique is presently being used as a means of "sterilizing" tumors before planned enucleation. The moderate temperature (43 degrees-45 degrees C) technique has been used in combination with radiotherapy to treat tumors when vision can be salvaged.

Animals↗
PubMed1988

A biologic tissue adhesive for vitreoretinal surgery.

Commercially available tissue glue was injected subretinally under mechanically induced retinal detachments in rabbit eyes resulting in chorioretinal adhesions at the injection site. After serial enucleation all eyes underwent histologic evaluation. Results were encouraging, but pooled fibrinogen is not acceptable for human use. A substitute for the pooled fibrinogen fraction, an adhesive using autologous plasma was prepared and studied after subretinal and intravitreal injection into rabbit and pig eyes. Postoperative clinical follow-up was one year for the rabbit eyes and one month for the pig eyes, after which all globes were enucleated. Histopathologic evaluation demonstrated circumscribed chorioretinal adhesions at the injection site. The autologous bioadhesive was applied as an adjunct in vitreoretinal surgery over macular holes and large retinal tears. As it is relatively short acting (ie, 4-6 days), it may be considered as a possible addition to existing techniques, facilitating difficult surgical procedures.

Adult↗
PubMed1987

Use of therapeutic ultrasound to restore failed trabeculectomies.

We treated 20 recently postoperative eyes with nonfunctioning trabeculectomies at the site of the failed bleb with two to four ultrasound applications, each of five seconds duration, at an intensity level of 10 kW/cm2. Fifteen of the eyes demonstrated a long-term decrease in intraocular pressure to 21 mm Hg or below. The mean intraocular pressure of all patients fell from a preultrasound mean (+/- S.D.) of 32 +/- 8 mm Hg to 20 +/- 10 mm Hg at a mean time of 236 +/- 204 days postultrasound. Complications included an immediate postultrasound rise in pressure over 10 mm Hg in 13 eyes, and the immediate development of a cataract in one patient.

Combined Modality Therapy↗
PubMed1987

Use of expanded temporal flaps to resurface the skin grafted forehead.

The forehead flap, whilst providing a reliable method of intra-oral reconstruction, leaves an unsightly donor defect in the skin grafted forehead. We describe a technique of resurfacing the forehead using tissue expansion. Axial pattern flaps of expanded hairless temporal scalp are transposed to the forehead. This technique is likely to have wide applications since no other satisfactory method of resurfacing the entire forehead exists.

Adult↗
PubMed1987

Management of intraocular foreign bodies.

Thirty-five consecutive cases of perforating ocular injuries with retained intraocular foreign body (IOFB) are examined in this retrospective study. Of the 35 cases with injuries, 30 (86%) were due to metallic foreign bodies. Of these, 25 (83%) involved foreign bodies of ferromagnetic origin. Magnetic extraction in combination with pars plana vitrectomy (or when possible, magnetic extraction alone) was successfully used to remove these foreign bodies. Even in cases where posterior vitrectomy is indicated, magnetic extraction allows good control of the foreign body during removal minimizing surgical trauma and the subsequent postoperative inflammatory response.

Eye Foreign Bodies↗
PubMed1987

Histologic changes in porcine eyes treated with high-intensity focused ultrasound.

High-intensity focused ultrasound (HIFU) has recently been described in the treatment of patients with glaucoma. However, despite previous studies in animal and mathematical models, the mechanisms of action are not completely understood. We therefore undertook a histologic study of 15 porcine eyes to evaluate the effect of HIFU and, in particular, the changes seen after sequential insonification on previously treated areas of sclera. We demonstrated initial scleral swelling that was followed by scleral thinning. The scleral thinning could be maximized by a second superimposed course of HIFU. The most consistent change in the ciliary body was necrosis of the pars plana. Some treated animals developed a hemorrhagic retinal detachment that we believe to be due to the presence of a circumferential blood vessel, which runs in the ora serrata of the pig but which is not present in humans. Based on our observations, possible mechanisms of action of this treatment are discussed.

Animals↗