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Biomedical subjects

J M Lewis

Publications and source records attributed to J M Lewis.

At least 37 records · Page 2Linked to original sources
PubMed1998

Conservation of T cell receptor conformation in epidermal gammadelta cells with disrupted primary Vgamma gene usage.

A feature that distinguishes gammadelta T cell subsets from most alphabeta T cells and B cells is the association of expression of single T cell receptor (TCR) gamma and delta variable (V) region gene segments with specific anatomic sites. Mice lacking the TCR Vgamma5 chain normally expressed by most dendritic epidermal T cells were shown to retain a conformational determinant (idiotype) ordinarily expressed exclusively by such Vgamma5+ cells. Conservation by shuffled gammadelta TCR chains of an idiotype associated with a specific anatomic site indicates that for TCRgammadelta, as for immunoglobulin, conformation is associated to a greater extent with the function or development of lymphocyte repertoires than is the use of particular gene segments.

Animals↗
PubMed1998

Pneumatic displacement of subretinal hemorrhage without tissue plasminogen activator.

OBJECTIVE: To assess the efficacy and complications of intravitreal injection of perfluoropropane gas for displacement of subretinal hemorrhage (SRH), without the use of tissue plasminogen activator. PATIENTS AND METHODS: Pure perfluoropropane gas (0.4-0.5 mL) was injected into the vitreous cavity in 5 patients with SRH involving the fovea because of age-related macular degeneration (4 eyes) or ruptured retinal arterial macroaneurysm (1 eye). The patients were instructed to maintain a prone position. RESULTS: Visual acuity ranged from 20/300 to 20/2000 before gas injection. On the day after gas injection, SRH was dramatically displaced in 3 eyes and slightly displaced with a reduction in the thickness of subfoveal hemorrhage in the remaining 2 eyes. Final visual acuity improved in all cases, ranging from 20/15 to 20/220. Three eyes had a final visual acuity of 20/50 or better. Vitreous hemorrhage caused by migration of SRH into the vitreous cavity and retinal detachment each occurred in 1 eye, and both complications were successfully treated by vitrectomy. CONCLUSIONS: Gas injected into the vitreous cavity can displace SRH without the use of tissue plasminogen activator in some cases. Visual acuity after gas injection may be improved, making this treatment an alternative to evacuation of SRH with vitrectomy.

Aged↗
PubMed1998

Chorioretinal damage caused by the excision of choroidal neovascularization.

PURPOSE: To determine whether choroidal neovascularization excision causes mechanical damage to the neurosensory retina, retinal pigment epithelium, or choriocapillaris. METHODS: Prospectively, 18 eyes of 18 consecutive patients who underwent choroidal neovascularization excision were observed. Preoperatively and postoperatively, the integrity of the choriocapillaris circulation in the pathway of choroidal neovascularization extraction was studied by fluorescein and indocyanine green angiography. Using static scanning laser ophthalmoscope microperimetry, the presence of iatrogenic scotomas that developed postoperatively in the pathway of choroidal neovascularization extraction was also investigated. RESULTS: Postoperatively, a choriocapillaris defect was detected in 17 (94.4%) of 18 cases. In 15 cases (83.3%), the choriocapillaris defect had a clear relationship to the pathway of choroidal neovascularization extraction. Postoperatively, a scotoma was present in 16 (88.9%) of 18 cases. In 14 cases (77.8%), the location of the scotoma had a clear relationship to the pathway of choroidal neovascularization extraction. CONCLUSION: Surgical excision of choroidal neovascularization leads to severe damage of the choroid and retina in the pathway of the extracted choroidal neovascularization. The injury involves the neurosensory retina, retinal pigment epithelium, and choriocapillaris.

Adult↗
PubMed1998

Extrusion of an anterior chamber intraocular lens complicated by Haemophilus endophthalmitis.

PURPOSE: To describe a case of late postoperative endophthalmitis in a patient who had undergone anterior chamber intraocular lens implantation 6 years previously. METHOD: Onset, course, and outcome of the patient's eye disease are presented. RESULTS: The patient was initially examined with erosion of the eyewall, extrusion of the lens haptic, and endophthalmitis. Intraocular cultures disclosed the pathogenic organism to be Haemophilus influenzae. CONCLUSION: Anterior chamber intraocular lens haptic extrusion can have grave consequences, including endophthalmitis and severe visual loss.

Aged↗
PubMed1998

For better or worse: interpersonal relationships and individual outcome.

At a time of strong biological emphasis in psychiatry, it is important to emphasize that relationships with important others may play a crucial role in individual outcome. Psychoanalytic theories in the form of object relations, self psychology, and relational psychoanalysis reflect this emphasis, and at a broader level, the interpersonal school of psychiatry focuses selectively on the role of relationships in health and illness. Ten central premises of the interpersonal school are presented, followed by brief, selective reviews of three bodies of empirical data: studies of well-functioning marriages and families, the role of adult relationships in undoing the adult consequences of destructive childhood experiences, and the relationship of marital variables to the onset and course of depressive disorders. Clinical experience and research findings suggest that clinicians treating couples and families may be helpful by using techniques designed to both increase the intensity of affective bonds and repair the inevitable disruptions of those bonds. It is also noted that recent psychophysiologic studies suggest that derivatives of intense affective bonds and their disruptions, in the form of confiding and conflict, may influence both vascular reactivity and cellular immune competence. These studies suggest that "for better or worse" may have physiologic as well as psychological implications.

Adult↗
PubMed1998

Pearls in the management of submacular hematoma.

Subretinal hemorrhage (SRH), complicated by choroidal neovascularization such as age-related macular degeneration, often reduces central vision in middle-aged patients. Although the visual results of SRH removal by surgery seem to have improved recently, the efficacy has not yet been confirmed in a prospective, controlled fashion. Therefore, it cannot be stated with certainty that surgery for SRH is more beneficial than the natural course of the disease. However, we believe surgery is beneficial in selected patients. Herein, we describe our technique for the surgical removal of SRH. The development of safer, more effective techniques should further improve patient outcomes.

Fluorescein Angiography↗
PubMed1997

Insulin-like growth factor receptor cooperates with integrin alpha v beta 5 to promote tumor cell dissemination in vivo.

Tumor cell interactions with adhesion proteins and growth factors likely contribute to the metastatic cascade. Evidence is provided that insulin or insulin-like growth factor-mediated signals cooperate with the commonly expressed integrin alpha v beta 5 to promote spontaneous pulmonary metastasis of multiple tumor cell types in both the chick embryo and severe combined immune deficiency mouse/human chimeric models. Expression of alpha v beta 5 in tumor cells promoted their adhesion to vitronectin in vitro. However, cell motility required cytokine stimulation, which caused redistribution of alpha-actinin to membrane-adhesive sites containing alpha v beta 5. Significantly, ligation of alpha v beta 5 and cytokine receptors were both required for spontaneous pulmonary metastasis of multiple tumor types even though it was not necessary for primary tumor growth. Thus, tumor cell metastasis can be regulated by a functional cooperation between cytokine signaling events and the adhesion receptor alpha v beta 5 in a manner independent of tumor cell growth. These findings provide evidence that integrin ligation, in conjunction with cytokine activation, plays an important role in the dissemination of malignant tumor cells.

Actinin↗
PubMed1997

The double-mirror gonioscopic lens for surgery of the anterior chamber angle.

Intraoperative examination of the anterior chamber angle is necessary during several glaucoma procedures, including goniosynechialysis and goniotomy. Many of the available lenses for this purpose are difficult to use because they require oblique illumination and their size interferes with surgical manipulations at the limbus. We have developed a double-mirror gonioscopic lens that uses direct illumination; provides an upright image of angle structures; and has a small diameter, allowing simultaneous access to the entire limbal region. We compared our lens with the Posner goniomirror (Ocular Instruments, Bellvue, Wash) and found that it provides an equal view of angle structures. The double-mirror gonioscopic lens facilitates the intraoperative visualization of the anterior chamber angle and should allow surgeons who treat glaucoma to more accurately and safely perform angle-related procedures.

Animals↗
PubMed1997

Exotropia secondary to vitreous hemorrhage.

BACKGROUND: Diplopia after cataract surgery has been reported by several authors, but diplopia after recovery from vitreous hemorrhage (VH) has not been described. METHODS: We examined eight patients with manifest exotropia and binocular diplopia after recovery from dense VH by vitreous surgery. VH was bilateral in three patients and unilateral in five, and lasted for an average of 7.7 years. RESULTS: Visual acuity before vitrectomy ranged from 20/200 to light perception; that after vitrectomy ranged from 20/20 to 20/60. Exotropia was present in all patients after vitrectomy. Additionally, seven out of eight patients had vertical strabismus with an average deviation of 6 prism diopters (delta). Fusion was confirmed in four patients with an average amplitude of 13 delta. Four patients underwent horizontal strabismus surgery. Fusion was present in two before strabismus surgery and in all four after surgery; however, unstable diplopia persisted in three of the four after surgery. CONCLUSION: Diplopia after vitrectomy for longstanding VH may occur due to fusion impairment comparable to that occasionally seen after surgery for traumatic cataract.

Adolescent↗
PubMed1997

Diamond-dusted silicone cannula for epiretinal membrane separation during vitreous surgery.

PURPOSE: To report a diamond-dusted silicone cannula as a tool for membrane separation during vitreous surgery. METHODS: A diamond-dusted silicone cannula was fashioned from flexible silicone tubing with a beveled tip and coated with diamond fragments for use during vitreous surgery. RESULTS: The instrument was used successfully in seven eyes with idiopathic macular hole and was found to be particularly useful for removing residual vitreous cortex and epiretinal membranes from around the hole. It was also effective in removing "immature membranes" in three eyes with proliferative vitreoretinopathy. CONCLUSION: The diamond-dusted silicone cannula is a useful tool for removing thin epiretinal membranes and vitreous cortex that may be difficult or nearly impossible to remove safely using other techniques.

Catheterization↗
PubMed1997

Retinal detachment after branch retinal vein occlusion: influence of the type of break on the outcome of vitreous surgery.

BACKGROUND: Branch retinal vein occlusion (BRVO) is occasionally complicated by two types of retinal breaks (retinal holes without vitreous traction or retinal traction tears) that may lead to a rhegmatogenous retinal detachment (RRD). The authors describe surgical results of vitrectomy for RRD after BRVO and investigate whether there is any difference between clinical features or surgical results from eyes with the two types of retinal breaks. PATIENTS AND METHODS: The authors retrospectively studied 25 patients (25 eyes) who underwent vitrectomy for RRD after BRVO. Twelve of 25 eyes (48%) had a detachment secondary to one or more retinal holes (group I), and 13 of the eyes (52%) had one or more retinal tears (group II). RESULTS: Seventeen of the eyes (68%) achieved total retinal reattachment after the initial surgery; 22 (88%) did so by the time of final examination. Patients with retinal holes achieved more favorable final vision than those with retinal tears (P = 0.0391). A higher rate of preoperative macular detachment (P = 0.0112) and a higher rate of recurrent retinal detachment after initial vitrectomy (P = 0.0302) were the factors associated with the reduced final visual acuity in patients with retinal tears. The increased rate of recurrent retinal detachment in patients with retinal tears was associated with a higher rate of existing preretinal neovascular membranes (P = 0.0112) and a trend toward an increased incidence of intraoperative iatrogenic retinal breaks. CONCLUSION: Among patients who undergo vitrectomy for RRD after BRVO, better surgical results are expected in eyes with retinal holes without vitreous traction than in those with retinal traction tears. This difference is thought to be due to the difference in vitreoretinal anatomy between eyes with the two types of retinal breaks.

Aged↗
PubMed1997

Ophthalmomyiasis interna posterior. Report of a case with optic atrophy.

PURPOSE: The prognosis for patients with ophthalmomyiasis Interna posterior is variable. In many patients the larva remains in the eye for years without inducing inflammation or loss of vision. Sometimes, however, the migrating larva involves the macula and optic nerve and results in permanent visual loss or even blindness. METHODS: Our patient presented with sudden painless loss of vision in the right eye that was caused by ophthalmomyiasis interna posterior. Hemorrhage of the optic nerve head suggested that the fly larva had entered the vitreous cavity from the optic nerve head. Subretinal tracts were sequelae of the subretinal migration of the organism. Sequential photographs documented the fly larva migration into the optic nerve head head from the vitreous cavity. The organism was removed by pars plana vitrectomy and retinectomy. RESULTS: In spite of the successful removal of the first stage fly larva, the visual acuity remained poor because of optic nerve atrophy. CONCLUSION: We suggest early removal of fly larvae to prevent damage and visual loss in cases of ocular myiasis interna posterior.

Blindness↗
PubMed1997

Accessibility of and client satisfaction with dental services in Melbourne.

Public dental clinics play an important role in delivering dental services to Australian adults on low incomes. Our objective was to compare the accessibility of and client satisfaction with the two main types of public dental service providers in Victoria and with private practice services. Clients attending the Royal Dental Hospital of Melbourne, Northcote Community Health Centre and private practices in Melbourne were surveyed. The hospital's clients faced the greatest ecological and organisational obstacles, while private clients faced the greatest financial and desirability obstacles. Community centre clients faced fewer ecological and organisational obstacles than hospital clients, with the exception of long waiting times. Private practice clients were more satisfied overall, and had better continuity of care. Private practice clients were more satisfied with access, availability and convenience than community centre clients, who in turn were more satisfied than hospital clients. There was no distinction between private practice and hospital clients on satisfaction with 'pain and treatment', but community centre clients were less satisfied. There was no significant difference between client group evaluations of interaction with the dentist. Regardless of the effects of the Commonwealth Dental Health Program, distinctions between various service types and public clinic types are likely to remain, because of their different settings. The contrast between a central hospital and a community health centre, in terms of the ecological and organisational obstacles to care, points to the advantages of putting dental services close to the communities they serve.

Adult↗
PubMed1997

Secondary vitrectomy for the treatment of macular holes occurring after vitrectomy.

Tangential foveal traction by the posterior vitreous cortex is regarded as the main cause of full-thickness macular holes. This report documents two cases of full-thickness macular holes that developed after vitrectomy for other diseases in the apparent absence of the cortical vitreous traction. Autologous serum with pars plana vitrectomy was used to treat these cases. Anatomic closure of the holes was achieved. Macular holes developing after vitrectomy may have an etiology other than tangential vitreous traction, and secondary vitrectomy is useful in treating such holes.

Adult↗
PubMed1997

An applicator-shaped scleral depressor for vitreoretinal surgery.

This article describes an instrument that combines a standard T-shaped scleral depressor at one end with a cotton applicator-shaped depressor at the other end. The applicator-shaped depressor has a matted surface to prevent slippage. This simple instrument has several advantages over depressors now available for intraoperative use.

Eye Diseases↗
PubMed1997

Subretinal fluid drainage with the erbium:YAG laser in rabbit eyes.

BACKGROUND AND OBJECTIVE: To evaluate the efficacy and safety of the erbium:yttrium-aluminum-garnet (Er:YAG) laser for choroidotomy as a means of performing external drainage of subretinal fluid with less risk of choroidal bleeding. MATERIALS AND METHODS: The authors tested this application in a rabbit model of retinal detachment by evaluating the effects of Er:YAG laser energy on the bare choroid at various energy settings (1, 2, 3, or 5 mJ/pulse) and repetition rates (2, 4, 10, or 30 Hz). RESULTS: Although the choroid was not perforated at low energy and frequency settings, choroidotomy was successfully achieved as energy and repetition rate were increased. Through higher energy levels per pulse and higher repetition rates, choroidotomy was achieved at lower total energy levels. No retinal damage was detected after laser choroidotomy. Choroidal bleeding was noted in 2 of 97 eyes; however, no subretinal hemorrhage occurred. CONCLUSION: These results indicate that the Er:YAG laser may be a clinically useful tool for retinal reattachment surgery.

Animals↗