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Biomedical subjects

C G Summers

Publications and source records attributed to C G Summers.

At least 37 records · Page 2Linked to original sources
PubMed1994

Ophthalmic features of minimal pigment oculocutaneous albinism.

PURPOSE: The purpose of this study is to describe the heterogeneous phenotype of individuals with an unusual type of albinism--minimal pigment oculocutaneous albinism. METHODS: Nine patients with minimal pigment oculocutaneous albinism were identified and followed for up to 11 years. The criteria were the presence of oculocutaneous albinism in association with low hairbulb tyrosinase activity in the patient and disparate activity in the parents with one parent having normal activity and the other having low tyrosinase activity. Changes in skin, hair, and ocular pigment were followed as the patients matured. As a measure of ocular pigment, iris transillumination and macular transparency were graded according to a previously published scheme. RESULTS: Patients were born with white scalp hair and skin, and nystagmus developed. Visual acuity was reduced to 20/50 to 20/200 for the group, but in one patient vision improved with maturity. Irides were blue. In seven patients, iris pigment developed, which was detected by transillumination with slit-lamp biomicroscopy, including the one patient with improved visual acuity. All patients had foveal hypoplasia, and melanin pigment in the fundi could not be detected by clinical examination. Visual acuity in the group did not correlate directly with the presence or development of iris transillumination or macular transparency. The pedigrees were consistent with an autosomal recessive inheritance pattern. CONCLUSION: This unique type of oculocutaneous albinism has heterogeneous clinical features. Minimal pigment oculocutaneous albinism appears to represent a new type of tyrosinase-related oculocutaneous albinism (OCA1MP).

Adolescent↗
PubMed1994

Dense peripheral corneal clouding in Scheie syndrome.

A 28-year-old woman with Scheie syndrome (MPS I-S) presented with the unusual feature of extremely dense peripheral corneal clouding, allowing maintenance of good central visual acuity. Characteristic systemic features, an abnormal electroretinogram result, and absent alpha-L-iduronidase activity confirmed the diagnosis despite the unusual corneal pattern of clouding.

Adult↗
PubMed1994

Effect of acute-phase retinopathy of prematurity on grating acuity development in the very low birth weight infant. The Cryotherapy for Retinopathy of Prematurity Cooperative Group.

PURPOSE: To examine the development of grating acuity in four groups of eyes in the Multicenter Study of Cryotherapy for Retinopathy of Prematurity (CRYO-ROP): eyes with no ROP; eyes with less-than-prethreshold ROP; eyes with prethreshold ROP; and eyes with threshold ROP that were randomized to serve as controls (not treated with cryotherapy). METHODS: Subjects were 1398 children with birth weights < 1251 g whose acute-phase ROP was documented as part of the CRYO-ROP study. Monocular grating acuity was measured using the Teller acuity card procedure when children reached 1, 2, 3 1/2, and 4 1/2 years of age. RESULTS: Eyes in the no-ROP and less-than-prethreshold groups showed nearly identical acuity development. Eyes with prethreshold ROP showed mean acuity similar to the no-ROP group at 1 and 2 years, but slightly below the no-ROP group at 3 1/2 and 4 1/2 years. Only 50% of eyes in the threshold untreated ROP group had measurable acuity. These eyes showed mean acuity scores that were approximately 1 octave below those of the no-ROP group at all four test ages. When data from eyes with ROP residua or other ocular abnormalities, and data from eyes of children who were unable to pass the study developmental screening items, were excluded, acuity development was similar among groups. CONCLUSIONS: Mild (less-than-prethreshold) ROP has no effect on the development of grating acuity in children between 1 and 4 1/2 years of age. Moderate (prethreshold) ROP is associated with reduced acuity at 3 1/2 and 4 1/2 years. In general, severe (threshold untreated) ROP results in moderate to severe reductions in acuity at all ages between 1 and 4 1/2 years. However, a small number of children with severe ROP show normal acuity development.

Acute Disease↗
PubMed1994

Albinism and the associated ocular defects.

Several types of hypopigmentation in humans are called albinism. The phenotype for different types of albinism varies according to the amount of pigment in the hale, skin and iris, the reduction in visual acuity and the degree of nystagmus and strabismus. Cutaneous and ocular melanin pigment can range from complete absence throughout the lifetime of the individual to the development of nearly normal levels, including the ability to tan. Visual acuity ranges from 20/40 to 20/400, and visual development in an affected infant is slower than normal. Foveal hypoplasia and altered routing of the optic nerves are found in all types of albinism and are the most constant feature of this condition. The demonstration of optic track misrouting by visual evoked potential studies provides the critical diagnostic procedure for questionable cases of albinism, and this is the single definitive diagnostic test to confirm a diagnosis of albinism.

Albinism, Ocular↗
PubMed1993

Long-term outcome of Hurler syndrome following bone marrow transplantation.

Previous reports suggested a therapeutic response of lysosomal storage diseases such as Hurler syndrome following bone marrow transplantation. However, a clearer understanding of outcome has awaited long-term follow-up. We evaluated prospectively 11 consecutive patients with Hurler syndrome receiving marrow from an HLA-identical sib donor between September 1983-October 1988. Follow-up evaluations included assessment of donor engraftment by restriction fragment polymorphism analysis, determination of leukocyte alpha-L-iduronidase level, measurement of lumbar cerebrospinal fluid (CSF) pressure, computerized tomography (CT) of the brain, and psychometric testing. In this series there was a survival rate of 9/11 (82%) with all survivors showing complete (7 patients) or partial (2 patients) donor engraftment. Prospective longitudinal evaluation of the 9 surviving children, now 3.8-8.9 years posttransplantation (median 5.5) demonstrated persistence of previously deficient leukocyte alpha-L-iduronidase at levels reflecting the donor genotype and degree of donor engraftment. Urinary glycosaminoglycan excretion declined to near-normal within 5 months of donor engraftment. Prior to treatment, 7 of 8 children studied were found to have occult intracranial hypertension (lumbar CSF pressure > 20 cm CSF); however, all surviving children attained normal or near-normal pressure within 18 months of donor engraftment. Longterm follow-up CT imaging of the brain did not show progressive volume loss (cerebral atrophy) after donor engraftment. Of 9 survivors, 4 children having a developmental quotient (DQ, Mental Development Index on Bayley Scales of Infant Development) above 80 prior to transplantation subsequently maintained IQ scores above this level. However, 5 patients with lower pretransplant DQ scores now have significant cognitive deficits and attention deficit hyperactivity disorder. Progressive brain damage resulting from communicating hydrocephalus may be prevented by successful engraftment. Early transplantation of children with Hurler syndrome who have normal intelligence is likely to have the clearest benefit because long-term intellectual outcome will be limited by brain damage which has occurred prior to treatment.

Bone Marrow Transplantation↗
PubMed1993

Surfactant prophylaxis and retinopathy of prematurity.

OBJECTIVE: The use of exogenous surfactant has led to a decrease in mortality of low-birth-weight infants. In some instances, use of this drug has also led to a reduction in neonatal morbidity, such as respiratory distress syndrome. This study was undertaken to determine whether prophylactic surfactant therapy has an effect on the incidence and severity of retinopathy of prematurity. DESIGN: The authors reviewed the findings of sequential prospective ophthalmologic examinations performed in two neonatal intensive care units that participated in randomized trials of prophylactic exogenous mammalian surfactant. PATIENTS: There were 43 patients in the control group (no prophylactic surfactant) and 43 patients in the prophylactic surfactant group. These groups did not differ on the basis of birth weight, gestational age, race, or gender. RESULTS: The incidence and severity of retinopathy of prematurity did not vary between the control and surfactant-treated infants. Only birth weight appeared to be significantly related to the incidence and severity of retinopathy of prematurity. CONCLUSIONS: These results suggest that the widespread use of prophylactic surfactant therapy will not change the incidence of retinopathy of prematurity in extremely low-birth-weight infants. However, the absolute number of affected patients will likely increase because of the decrease in mortality of extremely low-birth-weight patients, the patients most at risk for retinopathy of prematurity.

Female↗
PubMed1993

Calcification of scleral-wrapped orbital implant in patients with retinoblastoma.

Calcification detected by CT is a valuable technique to confirm a clinical impression of retinoblastoma. However, when calcification is detected following enucleation with placement of a scleral-wrapped orbital implant, the presence of calcium may be dystrophic, instead of indicating recurrent tumor growth. Cautious follow-up is warranted, and this report suggests that such calcification, probably associated with the scleral wrapping, can remain stable over many years.

Calcinosis↗
PubMed1993

Children with mucopolysaccharidosis: perioperative care, morbidity, mortality, and new findings.

The perioperative care, morbidity, and mortality in 30 patients with mucopolysaccharidosis (MPS) are presented. They underwent a detailed preoperative assessment and were anesthetized 141 times. An intravenous induction technique was used in most patients. It was easier to see the vocal cords, during laryngoscopy, in children with Hurler syndrome (HS) when they were younger (23 v 41 months, P < or = .01) and smaller (12 v 15 kg, P < or = .05). Preoperative obstructive breathing was associated with a significantly higher incidence of postextubation obstruction (P < or = .05). A total of 28 children underwent bone marrow transplantation (BMT); this reversed upper airway obstruction and also reversed intracranial hypertension. In children with HS, the incidence of odontoid dysplasia was 94%; 38% demonstrated anterior C1-C2 subluxation. Head and neck manipulation was limited in children with cervical spine defects. None of the 30 patients experienced spinal cord morbidity. One child suffered an intraoperative stroke; another, pulmonary edema. Severe and extensive coronary obstruction was responsible for 2 intraoperative deaths. Coronary angiography underestimated coronary artery disease.

Adolescent↗
PubMed1991

Variable expression of vision in sibs with albinism.

Oculocutaneous albinism is defined by the presence of cutaneous and ocular hypopigmentation, the latter associated with nystagmus, iris transillumination, reduced retinal pigment, foveal hypoplasia, and misrouting of the optic fibers at the chiasm. The visual acuity is variable but almost always reduced. We report on two brothers with oculocutaneous albinism and markedly different visual acuity. One brother has a visual acuity of 20/100, while the second has similar cutaneous pigmentation and visual acuity of 20/20 and had not previously been recognized as having oculocutaneous albinism. Both brothers have foveal hypoplasia and misrouting of the optic fibers at the chiasm. Biochemical analysis suggests that this is a tyrosinase-related type of oculocutaneous albinism. This study demonstrates that careful observation of foveal development in relatives with normal vision is necessary to detect all individuals with albinism in a family. A suspected diagnosis of albinism may be confirmed when the visual-evoked potentials show excessive decussation of the optic fibers at the chiasm.

Adolescent↗
PubMed1991

Temperature-sensitive tyrosinase associated with peripheral pigmentation in oculocutaneous albinism.

Several types of autosomal recessive oculocutaneous albinism (OCA) are associated with abnormal tyrosinase function and a generalized reduction in or absence of cutaneous and eye melanin. Each is thought to result from a different mutant allele at the tyrosinase locus, with the mutation producing an enzyme with little or no activity in all involved tissues. In this paper, we report a new type of OCA that results from a tyrosinase allele producing a temperature-sensitive enzyme. The proband had white hair in the warmer areas (scalp and axilla) and progressively darker hair in the cooler areas (extremities) of her body. Melanocyte and melanosome architecture were normal. Quantitative hairbulb tyrosinase (dopa oxidase) assay demonstrated a loss of activity above 35-37 degrees C. Plasma pheomelanin and urine eumelanin intermediates were reduced and correlated with hair melanin content. This is the first temperature-sensitive tyrosinase mutation to be reported in humans and is analogous to the Siamese mutation in the cat and the Himalayan mutation in the mouse.

Albinism, Oculocutaneous↗
PubMed1991

Three different frameshift mutations of the tyrosinase gene in type IA oculocutaneous albinism.

Mutations in the gene for the pigment-producing enzyme tyrosinase are responsible for type IA (tyrosinase-negative) oculocutaneous albinism (OCA). Most reported mutations have been single base substitutions. We now report three different frameshift mutations in three unrelated individuals with type IA OCA. The first individual has a single base deletion within a series of five guanidines, resulting in a premature stop codon in exon I on one allele and a missense mutation at codon 382 in exon III on the homologous allele. The second individual is a genetic compound of two separate frameshift mutations, including both the same exon I single base deletion found in the first individual and a deletion of a thymidine-guanidine pair, within the sequence GTGTG, forming a termination codon (TAG) in exon I on the homologous allele. The third individual has a single base insertion in exon I on one allele and a missense mutation at codon 373 in exon III on the homologous allele. The two missense mutations occur within the copper Bbinding region and may interfere with either copper binding to the enzyme or oxygen binding to the copper. These five different mutations disrupt tyrosinase function and are associated with a total lack of melanin biosynthesis.

Albinism, Oculocutaneous↗
PubMed1990

Visual anomalies associated with albinism.

All mammals with hypopigmentation of the retinal pigment epithelium have abnormal visual systems. Albino mammals have been found to have: (1) reduced numbers of uncrossed optic fibers projecting to all visual centers, (2) disorganization of the pattern (lamination) of the dorsal lateral geniculate nuclei, and (3) disorganization of projections from the dorsal lateral geniculate nuclei to the visual cortex. The disorganization of central visual centers has catastrophic effects on stereovision and optokinetic nystagmus. Variable expression in oculocutaneous albinism suggests that affected individuals cannot always be identified by hypopigmentation, reduced visual acuity and nystagmus. Careful observation of foveal development in individuals even with normal vision is necessary to detect all persons with albinism. The scalp-recorded visually evoked potential designed to detect optic misrouting is the most reliable concomitant for determining albinism.

Albinism↗
PubMed1990

Albinism and Hermansky-Pudlak syndrome in Puerto Rico.

Five types of oculocutaneous albinism and two types of ocular albinism were found among 349 Puerto Rican albinos. The most prevalent type of albinism was the Hermansky-Pudlak syndrome (HPS). HPS was observed in five of every six albinos in Puerto Rico. The prevalence of HPS was highest in the northwestern quarter of the island, affecting approximately one in 1,800 persons, and approximately one in 22 are carriers of the gene. HPS is an autosomal recessively inherited triad of a tyrosinase-positive type of albinism, a hemorrhagic diathesis due to storage pool deficient platelets and accumulation of ceroid in tissues. The pigmentary phenotype of HPS albinos resembled that of any other type of oculocutaneous or ocular albinism. The most reliable method of diagnosing HPS is by a deficiency of platelet dense bodies observed by electron microscopy. The accumulation of ceroid in the tissues is associated with fibrotic restrictive lung disease and granulomatous enteropathic disease. The enteropathic disorder resembles Crohn's disease and with few exceptions, had its onset after 13 years of age. The major causes of death were fibrotic restrictive pulmonary disease, hemorrhagic episodes and sequelae of granulomatous enteropathic disease. Menometrorrhagia was common in women with HPS. No immune deficiency was found in HPS patients. The majority of patients with HPS had visual acuities of 20/200 or worse and consequently were legally blind. Albinos of all types, including HPS, lacked binocular vision due to nearly complete crossing of the optic tracts.

Albinism, Ocular↗
PubMed1989

Ocular changes in the mucopolysaccharidoses after bone marrow transplantation. A preliminary report.

Metabolic correction and physiologic response were evaluated after bone marrow transplantation in mucopolysaccharidosis. Eleven patients were prospectively evaluated to determine the effect of bone marrow transplantation on the progressive ocular manifestations of these disorders. Follow-up of 0.6 to 2.8 years after successful donor stem cell engraftment showed that some patients had slow clearing of the corneal clouding, reduction of intracytoplasmic inclusions in the conjunctiva, resolution of optic nerve edema, and stabilized or improved retinal function as determined by electroretinography. These preliminary results suggest that early bone marrow transplantation may alter some of the progressive ophthalmic characteristics of the mucopolysaccharidoses. Long-term follow-up is necessary to determine if these early alterations in the ocular features are predictive of a prolonged functional improvement in the visual status.

Bone Marrow Transplantation↗
PubMed1988

Hermansky-Pudlak syndrome. Ophthalmic findings.

Prospective ophthalmic evaluation was performed in 20 individuals with Hermansky-Pudlak syndrome, a type of oculocutaneous albinism with an associated deficiency of dense bodies in platelets. The extent of visual impairment and the possible relationship to the degree of hypopigmentation were studied. All patients showed nystagmus, visual acuity ranged from 20/60 to 20/400, and correction of refractive error provided a mild improvement in vision. Iris pigmentation varied in amount and did not correlate with the visual acuity measurement. Foveal hypoplasia was found in all patients, but variability in macular transparency and vascular architecture was noted. Visual-evoked potentials performed in 11 patients demonstrated excessive decussation of optic fibers. Recognition of this form of oculocutaneous albinism is important because of the associated pulmonary, gastrointestinal, renal, and cardiac manifestations of Hermansky-Pudlak syndrome.

Adolescent↗
PubMed1988

Clinical significance of hematic cyst of the orbit.

Hematic cyst is a rarely encountered orbital lesion consisting of encapsulated blood or blood breakdown products. The abnormality may be recognized by identifying the cystic structure by B-scan ultrasonography or computed tomography. Cysts located peripherally in the orbit tend to have histologic features suggesting hematoma formation. More centrally located orbital cysts are sometimes associated with vascular abnormalities. In other cases, the etiology is obscure, as in the case presented here. The visual prognosis is usually good, and associated systemic abnormalities are lacking.

Adult↗