PubMed Health⌕ Search

Biomedical subjects

R B Melles

Publications and source records attributed to R B Melles.

15 recordsLinked to original sources
PubMed1998

User interface preferences in a point-of-care data system.

Point-of-care data entry is an important part of a clinical information system. Unfortunately, many health care providers refuse to perform data entry because they feel computers are difficult to use and require more time than traditional paper based forms. We designed a user interface for entry of outpatient visit information that gives the health care provider several alternative methods of entering data. The system audits the use of the individual interface elements and measures the time required for completion of the data entry.

Ambulatory Care Information Systems↗
PubMed1994

Metipranolol-associated granulomatous iritis.

PURPOSE: Topical metipranolol therapy for primary open-angle glaucoma has been associated with anterior granulomatous uveitis in the United Kingdom. We studied granulomatous uveitis reactions to topical metipranolol 0.3% therapy for primary open-angle glaucoma in two patients in the United States. METHODS: Two patients, aged 71 and 81 years, were given topical metipranolol 0.3% therapy for primary open-angle glaucoma. RESULTS: Both developed granulomatous uveitis. The iritis was associated with an increase in intraocular pressure in both patients and resolved on discontinuation of the drug. One patient was inadvertently rechallenged with metipranolol, and the iritis recurred. CONCLUSIONS: Topical metipranolol 0.3% therapy may be associated with the development of granulomatous uveitis and a paradoxical increase in intraocular pressure.

Aged↗
PubMed1991

Neurophysiologic studies of the peripheral nervous system in nephropathic cystinosis.

Cystinosis is an autosomal recessive metabolic disorder in which nonprotein cystine accumulates within most body tissues due to a defect in lysosomal cystine transport. Neurologic declarations are only recently being recognized. We studied 13 cystinotic subjects (aged 5 to 21 years old), determining median motor and sensory nerve conduction velocities, F waves, peroneal motor nerve conduction velocities, sural sensory nerve conduction velocities, median sympathetic skin response, electrocardiogram R-to-R variability, and blink reflex analysis. The results were normal. We conclude that neurophysiologic testing suggests relative sparing of the peripheral nervous system in nephropathic cystinosis.

Adolescent↗
PubMed1990

Update on nephropathic cystinosis.

The cystine that accumulates within cystinotic lysosomes comes primarily from proteins which have been degraded within this organelle. The individual amino acids have specific transport mechanisms to exit the lysosome. The lysosomal cystine transporter is defective in all types of cystinosis. When cells from patients with nephropathic and benign cystinosis were fused, the defect was not corrected and the cystine level remained elevated. This strongly indicates that the genetic defects are allelic (i.e., on the same chromosome). Cysteamine is a weak base which enters the cystinotic lysosome and reacts with cysteamine. forming a mixed disulfide of half-cystine and cysteamine. This mixed disulfide rapidly exits the lysosome via the transport system for cationic amino acids which is normal in cystinosis. Because of the success of renal transplantation, many cystinosis patients are alive in their twenties and even early thirties. Unfortunately, these patients have developed damage to other organs including thyroid, eye, central nervous system, pancreas, and muscle. Cysteamine and its analog, phosphocysteamine, are very beneficial to cystinosis patients, especially when started early in life. These drugs may prevent the need for transplantation. It is too early to know if they will prevent damage to other organs.

Cystinosis↗
PubMed1990

Photic sneeze reflex in nephropathic cystinosis.

Photic induced sneeze is a reflex that occurs in certain individuals after exposure to bright light. Cystinosis is an autosomal recessive inborn error of metabolism in which nonprotein cystine accumulates within lysosomes. The pathognomonic ocular manifestation of cystinosis is corneal crystal deposition. We observed photic induced sneezes during ophthalmoscopic examination in five of 19 patients with nephropathic cystinosis (26%). We report on this observation and discuss possible pathophysiological mechanisms for photic induced sneezing in cystinosis.

Cystinosis↗
PubMed1989

Corneal thickness in nephropathic cystinosis.

Cystinosis is a rare autosomal recessive metabolic disorder in which non-protein cystine accumulates within cellular lysosomes owing to a defect in lysosomal cystine transport. The pathognomonic ocular manifestation of cystinosis is the deposition of distinctive iridescent crystals in the cornea, not associated with any inflammatory response or recognised change in corneal function. We measured corneal thickness in nine patients with infantile nephropathic cystinosis. We also studied a corneal button from one of these patients who underwent corneal transplantation. All nine patients had increased corneal thickness in comparison with an age matched control population. Electron microscopy analysis of the cystinotic button revealed structural changes of both epithelium and endothelium layers. Increased corneal thickness in patients with nephropathic cystinosis may reflect subclinical corneal oedema.

Adolescent↗
PubMed1989

Amyloid ophthalmoplegia. Ophthalmoparesis secondary to primary systemic amyloidosis.

We report a patient with primary systemic amyloidosis and orbital involvement associated with ophthalmoparesis. We support this with the first demonstration of eye movement recordings and magnetic resonance imaging (MRI) of such a patient. The patient presented with a restrictive ophthalmoparesis. Eye movement recordings documented slowed horizontal saccades. MRI of orbital structures suggests that all extraocular muscles were enlarged, with possible involvement of their tendinous insertions.

Amyloidosis↗
PubMed1988

Night terrors and sudden unexplained nocturnal death.

A high incidence of sudden unexplained nocturnal deaths has been reported among young Asian males. These deaths are known as Pokkuri in Japan, Bangungut in the Philippines and Sudden Unexplained Nocturnal Death in the United States. Post mortem analysis has demonstrated cardiac conduction defects in many of the victims. Careful review of the terminal events surrounding these deaths suggests that the victims suffered from night terrors. Night terrors are a sleep disorder characterized by vocalization, motor activity, a nonarousable state, and severe autonomic discharge. The proposed recognition of both night terrors and cardiac anomalies in these patients offers a pathophysiologic mechanism for their sudden death.

Asia↗
PubMed1987

Spatial and temporal sequence of corneal crystal deposition in nephropathic cystinosis.

We studied 15 patients with infantile nephropathic cystinosis. We found that anterior corneal cystine crystal deposition began early in life and proceeded posteriorly as the patient aged; deposition advanced more rapidly in the periphery. Ultrastructural analysis of a corneal button obtained from a 20-year-old patient undergoing corneal transplantation confirmed our clinical observations that crystals were deposited throughout the entire central stroma.

Adolescent↗
PubMed1987

Corneal sensitivity in nephropathic cystinosis.

We measured corneal sensitivity in 14 patients with infantile nephropathic cystinosis and in 13 age-matched controls. All patients with cystinosis had the pathognomonic anterior segment findings of crystal deposition within conjunctiva and cornea. Transcutaneous stimulation of the supraorbital nerve and surface electromyographic recording of the orbicularis oculi muscle performed on four patients showed a normal afferent limb to the blink reflex. The corneal sensitivity in patients with cystinosis was 3.18 g/mm2; in the control subjects it was 0.43 g/mm2. This difference was statistically significant (P less than .001).

Adolescent↗
PubMed1987

Contrast sensitivity function in nephropathic cystinosis.

Cystinosis is a rare autosomal recessive metabolic disorder in which nonprotein cystine accumulates within most body organs due to a defect in lysosomal cystine transport. The pathognomonic ocular manifestations of cystinosis are the presence of distinctive iridescent crystals within ocular tissue and a pigmentary retinopathy. We measured spatial contrast sensitivity in seven patients with infantile-onset nephropathic cystinosis and compared their contrast sensitivity function with that measured in ten age-matched controls. Spatial contrast sensitivities in the patient group were significantly lower than those in the normal group. Loss of contrast sensitivity in the patients with nephropathic cystinosis was more pronounced at higher spatial frequencies. We speculate that this loss of contrast function is primarily a manifestation of corneal disease, with secondary contributions from retinal changes and central nervous system dysfunction.

Adolescent↗
PubMed1987

Glare disability in nephropathic cystinosis.

Cystinosis is a rare metabolic disorder in which nonprotein cystine accumulates within lysosomes due to a defect in lysosomal cystine transport. Although cystine accumulates within most ocular tissues, patients with cystinosis generally complain only of photophobia and glare. We measured glare sensitivity in 12 patients with infantile cystinosis and compared their results with an age-matched control population. Ten of the 12 patients with cystinosis had demonstrable glare disability when compared with the control group. Glare disability scores in the patients with cystinosis ranged from 5% to 50%. Dazzle glare resulting from the accumulation of cystine crystals in ocular tissue may account for glare disability seen in these patients and contribute to their complaints of photophobia.

Adolescent↗