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Biomedical subjects

M E Tyler

Publications and source records attributed to M E Tyler.

13 recordsLinked to original sources
PubMed2000

The afferent neural response to electrotactile stimuli: preliminary results.

We recorded action potentials from three RA fibers innervating primate fingerpad, while applying electrotactile (electrocutaneous) stimulation. Negative pulses required 1.3-1.5 times more current than positive ones for entrainment. The strength-duration time constant was approximately 151 micros. Suprathreshold sinusoidal vibration synchronized to 30-Hz electrotactile pulses changed the electrotactile entrainment current slightly, indicating a possible electrical-mechanical transduction interaction.

Action Potentials↗
PubMed1998

Form perception with a 49-point electrotactile stimulus array on the tongue: a technical note.

Form perception with the tongue was studied with a 49-point electrotactile array. Five sighted adult human subjects (3M/2F) each received 4 blocks of 12 tactile patterns, approximations of circles, squares, and vertex-up equilateral triangles, sized to 4x4, 5x5, 6x6, and 7x7 electrode arrays. Perception with electrical stimulation of the tongue is better than with fingertip electrotactile stimulation, and the tongue requires 3% (5-15 V) of the voltage. The mean current for tongue subjects was 1.612 mA. Tongue shape recognition performance across all sizes was 79.8%. The approximate dimensions of the electrotactile array and the dimensions of compartments built into dental retainers have been determined. The goal is to develop a practical, cosmetically acceptable, wireless system for blind persons, with a miniature TV camera, microelectronics, and FM transmitter built into a pair of glasses, and the electrotactile array in a dental orthodontic retainer.

Adult↗
PubMed1998

Retrospective analysis of a novel method of transscleral suture fixation for posterior-chamber intraocular lens implantation in the absence of capsular support.

PURPOSE: To determine the safety and efficacy of an alternative method for transscleral fixation of a secondary posterior-chamber intraocular lens (pcIOL) during penetrating keratoplasty. METHODS: Eighty-nine eyes that underwent secondary pcIOL implantation by using a modified transscleral suture-fixation technique during penetrating keratoplasty were retrospectively evaluated. The surgical technique used suture fixation to the surface of the sclera 5 mm posterior to the limbus, with the knot buried beneath Tenon's capsule and conjunctiva. Patient records were reviewed for postoperative complications, including suture erosion, pcIOL subluxation, vitreous hemorrhage, and retinal detachment. Mean follow-up was 24.4 months, with a range of 4-68 months. RESULTS: All eyes had successful fixation of their pcIOL immediately after surgery. Three (3.3%) eyes had graft failure. Six (6.7%) of 89 eyes showed evidence of suture erosion or partial exposure. Postoperative suture breakage occurred in two (2.2%) eyes. Posterior-segment complications included retinal detachment in one (1.1%) eye, vitreous hemorrhage in one (1.1%) eye, and limited choroidal hemorrhage in two (2.2%) eyes. Median visual acuity at 1-year follow-up was 20/70 (range, 20/25 to light perception). CONCLUSION: This transscleral fixation technique provides a straightforward alternative to previously described techniques. Suture erosion, IOL dislocation, and posterior-segment complications occurred at relatively low rates compared with other pcIOL implantation techniques.

Adult↗
PubMed1997

Bilateral monocular diplopia associated with lid position during near work.

PURPOSE: To describe a common pattern of topographic changes and clinical signs of six patients presenting with a complaint of monocular diplopia after reading and to investigate the cause of this topographic disturbance. METHODS PATIENT POPULATION: Subject group of six patients with monocular diplopia complaints after reading and 20 patients without such complaints. Examinations performed before and after a reading period of 30 min: videokeratoscopic examination, red reflex examination, position of the lids in primary gaze and in reading position. DATA ANALYSIS: inspection of keratoscopic rings, qualitative analysis of topography maps, comparison of SAI and SRI of control and subject groups before and after reading, comparison of lid position of control and subject group. RESULTS: Half of the subject group and none of the control group developed subtle ring distortions of keratoscopic rings. SAI and SRI values increased significantly in the subject group compared with the control group (p = 0.02 and p < 0.001, respectively) corresponding to the development of a focal distortion in the entrance pupil of the videokeratoscopic image. Each subject developed a horizontal band on red reflex located at the superior, middle, or inferior aspect of the pupil after near work. Two controls developed faint bands in the red reflex outside the entrance pupil. The interpalpebral fissure in down gaze was narrower in the subject group compared with the control group (p = 0.001). CONCLUSIONS: Some individuals may develop monocular diplopia after reading. We hypothesize that during near work these corneal topographic alterations occur primarily related to the position of the lids and tear film interaction with the corneal surface.

Adult↗
PubMed1984

Cavernous hemangioma of the retina, cutaneous angiomas, and intracranial vascular lesion by computed tomography and nuclear magnetic resonance imaging.

In a 32-year-old man with a right-sided retinal cavernous hemangioma and cutaneous angiomas, computed tomography and nuclear magnetic resonance imaging confirmed the presence of cerebrovascular lesions. This supports the inclusion of cavernous hemangioma of the retina in the established group of neuro-oculo-cutaneous phacomatoses.

Adult↗
PubMed1982

L-arabinose metabolism in Azospirillum brasiliense.

An oxidative pathway by which L-arabinose is converted to alpha-ketoglutarate in crude extracts of Azospirillum brasiliense is demonstrated. Specific activities of enzymes involved in the pathway were determined, and several pathway intermediates were identified.

Arabinose↗
PubMed1982

Rubella retinopathy and subretinal neovascularization.

A case of rubella retinopathy associated with macular scarring from subretinal neovascularization is presented. Ophthalmoscopic findings included diffuse mottling of the retinal pigment epithelium throughout the macula and into the postequatorial areas, atrophic "rings" around both optic discs, and a solid white and slightly raised macular cicatrix in the right eye. The patient has been followed for three years; her visual acuity remains at 20/20 and there has been no change in the appearance of her retinae. Rubella retinopathy should be considered in the differential diagnosis of young patients with subretinal neovascularization.

Adolescent↗
PubMed1980

Choroidoretinal vascular anastomoses.

Three cases of choroidoretinal anastomosis had unusual etiologic and hemodynamic features. In two cases the anastomoses, one caused by ocular histoplasmosis and one by diabetic maculopathy, shunted retinal venous drainage into the choroid. In the third case, the congenital arterial choroidoretinal anastomosis should probably be termed retinochoroidal arteriovenous anastomosis. Prospective photographic and fluorangiographic studies of these patients suggest that our understanding of many basic features of retinal-choroidal circulatory hemodynamics is incomplete.

Adult↗
PubMed1979

Ophthalmomyiasis interna posterior. Subretinal tracks and intraocular larvae.

Only seven cases of identifiable intraocular botfly larva infestation have been reported in North America--five since 1969. Two additional cases, both from the same institution, are documented here. The offending maggot or larva was visible in both instances. The findings in each case were diagnostically and morphologically striking. The characteristic funduscopic finding of subretinal tracks, along with the appearance of the larva--encysted in one patient and free-floating in the other-deserves emphasis, since this condition is not always benign and may not be as rare as previously assumed.

Adolescent↗
PubMed1979

Isolation of Azospirullum from diverse geographic regions.

We have isolated Azospirillum (Spirullum lipoferum) from roots of grasses of several genera collected from a number of tropical and subtropical-temperate locations. Pure cultures were obtained from a small percentage of samples; no higher percentage was secured from tropical than from other grasses. Acetylene reduction and distinctive growth in N-free soft agar deeps were inadequate to identify this genus, although helpful in initial screening. Fluorescent antibody tests with antiserum against characterized strains were helpful. There is some evidence that this genus of bacteria may be favored in the rhizoplane.

Africa↗