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Biomedical subjects

S C Pollock

Publications and source records attributed to S C Pollock.

16 recordsLinked to original sources
PubMed1996

Periodic vestibulocerebellar ataxia, an autosomal dominant ataxia with defective smooth pursuit, is genetically distinct from other autosomal dominant ataxias.

BACKGROUND: Periodic vestibulocerebellar ataxia is an autosomal dominant disorder characterized by defective smooth pursuit, gaze-evoked nystagmus, ataxia, and vertigo. The age of onset ranges from the third to the sixth decade. To date, all patients have originated from North Carolina, suggesting a single common founder. OBJECTIVE: To clarify the classification of periodic vestibulocerebellar ataxia by determining whether it is allelic to other autosomal dominant cerebellar ataxias for which genes have been either localized or identified. METHODS: Blood was collected and DNA isolated from 66 subjects (19 affected individuals) in two multigenerational families. The microsatellite markers used in the analysis either flanked or were tightly linked to the disease gene regions. Two-point and multipoint linkage analyses were performed to define the limits of exclusion. RESULTS: Periodic vestibulocerebellar ataxia was excluded from loci linked to spinocerebellar ataxia type 1 (chromosome 6p), type 2 (chromosome 12q) type 3/Machado/Joseph disease (chromosome 14q), type 4 (chromosome 16q), and type 5 (11cent) as well as to episodic ataxia with myokymia (chromosome 12p), episodic ataxia with nystagmus (chromosome 19p), acetazolamide-responsive hereditary paroxysmal cerebellar ataxia (chromosome 19p), and dentatorubral-pallidoluysian atrophy/Haw River syndrome (chromosome 12p). CONCLUSION: Periodic vestibulocerebellar ataxia is genetically distinct from those autosomal dominant ataxias for which chromosomal localization has been established.

Alleles↗
PubMed1996

Ocular motility in North Carolina autosomal dominant ataxia.

The term "vestibulocerebellar ataxia" has been applied to a rare, autosomal dominant, late-onset disease with unusual ocular motility findings. We examined the ocular motility of 18 family members from two different kindreds and found 11 affected individuals. Both families in the present study, one of which was originally described by Farmer and Mustian, as well as the family reported by Farris et al., originated from Johnston County, North Carolina. We suspect that all three of these families have a common ancestral origin. The age of onset of the disorder was 31-60 years in the individuals examined. Ataxia, vertigo, diplopia, oscillopsia, and tinnitus were common complaints. Although a variety of eye movement abnormalities have previously been described in this disease, the most prominent and consistent findings in our patients were (a) abnormal smooth pursuits, (b) inability to suppress the vestibuloocular reflex (VOR), and (c) gaze-evoked nystagmus. These findings suggest that the cerebellar flocculus may be the primary site of pathology.

Adult↗
PubMed1995

Clinical features and pathogenesis of Alport retinopathy.

BACKGROUND: Alport syndrome refers to the clinical triad of hereditary nephritis, sensorineural deafness, and ocular abnormalities. Ultrastructural findings in the lens capsule and in the renal glomeruli have provided evidence that abnormal basement membranes are elaborated in affected tissues of patients with this disorder. Recently, the results of several linkage studies have allowed the genetic defect in Alport syndrome to be mapped to a locus that codes for a subtype of type IV collagen (alpha 5) known to be present in glomerular basement membranes. In spite of these advances, the nature of the retinal flecks in Alport syndrome and the visual consequences of the flecks remain controversial. METHODS: Detailed psychophysical and electrophysiologic testing was performed in a young man with Alport syndrome. The concurrence of an unusually extensive fleck retinopathy and unilateral pseudophakia afforded a unique opportunity to assess the effect of the flecks on retinal function. RESULTS: No sensory deficits were present in the eye with clear media. CONCLUSION: Macular flecks in Alport syndrome are not associated with demonstrable retinal dysfunction. The authors address questions about the nature and pathogenesis of the flecks in light of new clinical and genetic information.

Adult↗
PubMed1994

Chronic recurrent multiple evanescent white dot syndrome.

PURPOSE: Multiple evanescent white dot syndrome (MEWDS) is usually unilateral, self-limited, and monophasic. The purpose of this study was to demonstrate that a chronic recurring form of the disease exists. METHODS: Three patients with otherwise typical MEWDS were observed for 4 to 5 years. Their ocular histories and physical findings were recorded. RESULTS: Multiple recurrences (5-7) involving both eyes were noted in each of the three patients. Classic clinical findings were seen, including granularity to the macula, white dots, and optic disc changes. Despite these recurrences, the patients still retained visual acuity of 20/20 in each eye. CONCLUSION: A chronic recurrent form of MEWDS exists. The cause of MEWDS remains unknown, and it is unclear why these patients demonstrated this atypical clinical course.

Adult↗
PubMed1993

Altered gene expression after optic nerve transection: reduced neurofilament expression as a general response to axonal injury.

Previous studies have shown that axonal injury (axotomy) in neurons of the mammalian peripheral nervous system (PNS) results in a recapitulation of the developmental program for cytoskeletal gene expression; these changes include the increased expression of a developmentally regulated isotype of beta-tubulin (class II) and reduced neurofilament (NF) expression. In the present study we examined the abundance of mRNAs encoding the low-molecular-weight NF protein (NF-L) and class II beta-tubulin in RNA purified from the retinae of newborn rats, from the retinae of adult rats at 2, 7, and 14 days after intracranial transection of the ipsilateral optic nerve, and from contralateral control retinae. In order to facilitate comparison with representative PNS neurons, parallel analyses were carried out in axotomized dorsal root ganglion (DRG) sensory neurons. Since NF-L and class II beta-tubulin are neuron-specific proteins, axotomy-induced alterations in the levels of retinal mRNAs encoding these proteins largely reflect corresponding changes in expression by retinal ganglion cell neurons. Comparison of retinal RNA from newborn and adult (70-day-old) animals demonstrated a postnatal increase in NF-L and a decline in class II beta-tubulin mRNAs comparable to those previously described in DRG neurons. Reductions in NF-L mRNA levels were noted in retina at 2, 7, and 14 days after axotomy and in DRG neurons at 7 and 14 days after axotomy. The abundance of class II beta-tubulin mRNAs increased after axotomy in DRG neurons, but not in retina.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Recovery of vision in a 47-year-old man with fulminant giant cell arteritis.

Giant cell arteritis is a systemic necrotizing vasculitis that often causes profound and irreversible visual loss in elderly individuals. We describe a 47-year-old man with fulminant giant cell arteritis whose clinical picture included severe visual loss and several unusual or previously unreported findings. Aggressive treatment with intravenous corticosteroids resulted in a dramatic improvement in the patient's vision. Although no firm conclusions can be drawn from the outcome in a single case, we believe that, in some patients with arteritic ischemic optic neuropathy, aggressive treatment with intravenous corticosteroids may be associated with a better visual prognosis than treatment by the oral route.

Giant Cell Arteritis↗
PubMed1990

Optic nerve hypoplasia. Identification by magnetic resonance imaging.

High-resolution magnetic resonance images of the intracranial optic nerves and chiasm were obtained in 15 patients with severe optic nerve hypoplasia. These were compared, in a double-blind manner, with similar images from 30 age-matched controls. On both coronal and sagittal images, hypoplastic optic nerves were thin and demonstrated signal attenuation when compared with normal optic nerves. All patients with severe bilateral optic nerve hypoplasia also had diffuse chiasmal hypoplasia, which was seen best on coronal images. Patients with unilateral or asymmetrical optic nerve hypoplasia had variable chiasmal abnormalities. The degree to which the magnetic resonance diagnosis of optic nerve hypoplasia matched the clinical diagnosis was highly significant (P less than .001, Fisher's Exact Test) for both coronal and sagittal views of the intracranial optic nerves. Oblique axial and coronal views of the orbital optic nerves did not reliably distinguish optic nerve hypoplasia from normal optic nerves. High-resolution magnetic resonance imaging is a useful diagnostic modality to identify small optic nerves neuroradiologically.

Adolescent↗
PubMed1988

Sporothrix schenckii endophthalmitis in a patient with human immunodeficiency virus infection.

A 30-year-old homosexual man with a positive serologic test for human immunodeficiency virus and a history of successfully treated disseminated cutaneous sporotrichosis developed a granulomatous uveitis that worsened with topical and subconjunctival steroid therapy. Culture of the aqueous aspirate yielded Sporothrix schenckii. The patient was treated with intravenous amphotericin B and intravitreal amphotericin B, kanamycin sulfate, and amikacin sulfate. Subsequent aqueous and vitreous cultures were negative, but the intraocular inflammatory process progressed and ultimately led to enucleation of the eye. Histopathologic examination revealed granulomatous inflammation of the anterior uvea and scattered S schenckii in the anterior and posterior chambers. Electron microscopy demonstrated that most of the organisms had disorganized protoplasm. Although treatment failed to ameliorate the progressive intraocular inflammatory process, the negative cultures and the electron microscopic observations suggest that the treatment was reasonably effective in killing S schenckii within the eye. To our knowledge, this is the first case report of S schenckii endophthalmitis in a patient with human immunodeficiency virus infection.

Acquired Immunodeficiency Syndrome↗
PubMedDate not supplied

Neural misdirection in congenital ocular fibrosis syndrome: implications and pathogenesis.

A child with congenital ocular fibrosis syndrome and oculocutaneous albinism displayed two distinct neural misdirection syndromes: synergistic divergence and Marcus Gunn jaw winking. This and other reported cases of misdirected innervation in patients with congenital fibrosis syndrome suggest that normal neuronal connections fail to become established early in development and that lack of innervation may underlie the pathologic features of the disorder. The prevailing concept of congenital fibrosis syndrome as a primary myopathy should be reconsidered.

Albinism↗