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Biomedical subjects

M T Miller

Publications and source records attributed to M T Miller.

At least 37 records · Page 2Linked to original sources
PubMed1995

Progressive hemifacial atrophy. A natural history study.

PURPOSE: To describe two very different natural history courses in 2 patients with hemifacial atrophy. Progressive hemifacial atrophy (Parry-Romberg syndrome, Romberg syndrome, PHA) is characterized by slowly progressive atrophy, frequently involving only one side of the face, primarily affecting the subcutaneous tissue and fat. The onset usually occurs during the first 2 decades of life. The cause and pathophysiology are unknown. Ophthalmic involvement is common, with progressive enophthalmos a frequent finding. Pupillary disturbances, heterochromia, uveitis, pigmentary disturbances of the ocular fundus, and restrictive strabismus have also been reported. Neurologic findings may be present, but the natural history and progression of ocular findings are often not described in the literature. METHODS: We studied the records and present findings of 2 patients with progressive hemifacial atrophy who were observed in our institution over a 10-year period. RESULTS: Both patients showed progression of ophthalmic findings, primarily on the affected side. One patient has had chronic uveitis with secondary cataract and glaucoma, in addition to retinal pigmentary changes. She also had a third-nerve paresis of the contralateral eye and mild seizure activity. The other patient had mild uveitis, some progression of unilateral retinal pigmentary changes, and a significant increase in hyperopia in the affected eye, in addition to hypotony at age 19 without a clear cause, but with secondary retinal and refractive changes. CONCLUSION: Ocular manifestations of progressive hemifacial atrophy are varied, but can progress from mild visual impairment to blindness.

Adult↗
PubMed1994

Microcephaly, lymphedema, and chorioretinal dysplasia: report of two additional cases.

In recent years, several patients with microcephaly, lymphedema and chorioretinal dysplasia have been described. We have studied two additional patients with similar findings. The question of whether microcephaly with lymphedema and microcephaly with chorioretinal dysplasia and lymphedema are distinct entities remains unanswered. Identification of other patients in the future may provide additional information.

Abnormalities, Multiple↗
PubMed1993

A cellular model of oxidant-mediated neuronal injury.

Oxidants derived from the partial reduction of oxygen are thought to play a significant role in neuronal injury. We present here a cellular model of neuronal injury mediated by hydrogen peroxide (H2O2) using the PC 12 rat pheochromocytoma cell line. The organization of microtubules and microfilaments within neurites of PC 12 cells differentiated by exposure to nerve growth factor was examined after H2O2 injury using fluorescence microscopy. Concentrations of H2O2 as low as 100 microM produced an initial periodic pattern of microtubule depolymerization over 3-4 h which later progressed to complete depolymerization. Neuritic microspikes containing actin filaments were relatively more resistant to injury by H2O2 than microtubules. Blebbing of PC 12 cell bodies and neurites also was seen after H2O2 injury and the blebs appeared to contain microtubules. The destructive changes affecting neuritic structure preceded but were not essential for PC 12 cell lysis. Exposure of the cells to the Ca2+ ionophore, ionomycin (25 microM) also produced the same pattern of microtubule depolymerization in PC 12 neurites as was seen after H2O2 injury suggesting that H2O2 may mediate its destructive effect on the neurites via elevation of intracellular Ca2+.

Actin Cytoskeleton↗
PubMed1993

Thalidomide embryopathy: revisited 27 years later.

A prospective ophthalmological study was done in 86 out of a total of 100 Swedes with established thalidomide embryopathy. Forty-six (54%) of all examined individuals had eye findings, which made the eye the second most commonly affected organ in thalidomide embryopathy only surpassed by upper limbs (81%). Forty-three patients (50%) had ocular motility defects, mostly incomitant strabismus. Facial palsy and abnormal lacrimation each occurred in 17 (20%) individuals. One patient had coloboma of the uvea and optic disc and another two had coloboma of the optic disc. Infrequent anomalies were microphthalmos, congenital glaucoma, lipodermoid, and large refractive errors. The observed ocular motility defects, facial palsy and abnormal lacrimation occurred with early induced defects in thalidomide embryopathy, but not with isolated late occurring anomalies. This suggests that thalidomide exerts its effects on the development of these structures early in the teratogenic period, probably mainly during the fourth week of development.

Abnormalities, Drug-Induced↗
PubMed1993

ATP depletion induces an increase in the assembly of a labile pool of polymerized actin in endothelial cells.

Depletion of cellular ATP is associated with profound effects on the cytoskeleton, particularly disruption of microfilaments. We examined this process in bovine pulmonary artery endothelial cells by inducing differential reductions of cellular ATP using mitochondrial inhibition and variable amounts of glucose. Reduction of cellular ATP to levels < 40% of control produced discrete stages in the visible disruption of microfilaments. Using the deoxyribonuclease I assay, a reversible 11% decrease in monomeric (G) actin occurred in conjunction with microfilament disruption. Polyacrylamide gel electrophoretic (PAGE) analysis of the detergent-insoluble cytoskeleton did not reveal any differences in actin content between normal or ATP-depleted cells. Image analysis of adherent endothelial cells that had been fixed and stained with N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)-phallacidin revealed that an increase of F-actin of approximately 20% occurred in cells depleted of ATP. If the cells were lysed with detergent before fixation, the increase in F-actin was lost. PAGE analysis and electron microscopy of detergent-soluble material from the cells obtained by ultracentrifugation directly demonstrated the presence of a labile pool of F-actin within the cells, which increased with ATP loss. These observations suggest that ATP may play an important role in the organization and remodeling of microfilaments within cells.

Actin Cytoskeleton↗
PubMed1992

Refractive evaluation in thalidomide embryopathy.

To evaluate the ocular findings associated with thalidomide embryopathy, we examined 86 of 100 Swedes who had a proven correlation between birth defects and the mother's intake of thalidomide during pregnancy. Cycloplegic refraction, keratometry, and axial length measurements were performed. The subjects were divided into four groups according to their physical malformations, giving a time frame for when in gestation the insult occurred (the sensitive phase for thalidomide is 20-36 days after conception). The results indicate a trend toward shorter and longer axial lengths, high refractive errors, and corneal astigmatism in thalidomide embryopathy compared to controls, and in addition there was a tendency for those anomalies to occur in the group with the earliest thalidomide-induced defects. It is suggested that thalidomide disturbs the growth and shape of the eye and that this effect is exerted early in its teratogenic period.

Abnormalities, Drug-Induced↗
PubMed1992

Ocular teratology. Observations, speculations, questions, principles reaffirmed.

Teratology is most simply defined as "the study of environmental agents which disturb development". A more comprehensive definition is "the study of causes, mechanisms, and manifestations of developmental deviation, structural or functional." Teratology has several important purposes. Obviously, the most important is to protect future generations by identifying environmental agents that cause malformations. In this sphere, ophthalmologists are generally not the primary detectors. One notable exception is when Gregg, in 1941, recognised that an increase in congenital cataracts was due to a viral agent and brought rubella embryopathy to the attention of the medical community. Another pertinent reason for teratology is that it gives us insights into normal development. As Harvey said with such flair, "nature is nowhere accustomed more openly to display her secret mysteries than in cases where she shows tracings of her workings apart from the beaten path".

Ethanol↗
PubMed1992

The study of malformations "by the company they keep".

Our study of individuals with thalidomide embryopathy reaffirms many of the principles of clinical teratology concerning sensitivity of developing structures and specificity of action. It also highlights important features of ocular teratology that differ from those of other organ systems. Because malformations of the eye and associated structures do not significantly threaten the survival of the embryo, fetus, or neonate, any variation in prevalence in older individuals is not due to the nature of the ocular malformation but may be significantly modified by "the company they keep," the systemic malformations occurring at the same time as the original insult, whether it be an environmental, a genetic, or a local disturbance. Additionally, the presence of clusters of malformations caused by a teratogen at a specific time supports the concept of a common pathogenic mechanism and provides suggested avenues for further research into the cause of these malformations.

Abnormalities, Drug-Induced↗
PubMed1989

Magnetic resonance imaging of pituitary stalk hypoplasia. A discrete midline anomaly associated with endocrine abnormalities in septo-optic dysplasia.

Septo-optic dysplasia describes optic nerve hypoplasia in association with endocrine disturbances and/or midline brain malformations. Magnetic resonance imaging of the brain was used to study two patients with optic nerve hypoplasia, endocrine abnormalities, and normal midline brain anatomy on prior computed tomographic scan. The magnetic resonance imaging scans showed normal midline brain anatomy except for failure to visualize the pituitary stalk, a structure that magnetic resonance imaging has shown to be 100% sensitive in imaging in our normal controls. We propose that our two patients have endocrine abnormalities due to the discrete anomaly of pituitary stalk hypoplasia.

Child, Preschool↗
PubMed1988

Simulated superior oblique tendon sheath syndrome.

Three patients with simulated Brown's superior oblique tendon sheath syndrome are presented. With the use of computed tomographic (CT) findings, the site of the pathology could be demonstrated. In all three patients, there were definite abnormal findings in the anterior sheath of the reflected tendon of the superior oblique. The abnormal findings in one case were confirmed at the time of surgery. Therapy in two of the cases was determined by the abnormal findings on the CT scan.

Adolescent↗
PubMed1987

Amniotic bands as a cause of ocular anomalies.

We examined nine patients with amniotic band syndrome who had systemic and ocular pathologic deformities. The most common ocular malformations were congenital corneal leukomas or acquired corneal opacities secondary to exposure and eyelid colobomas. The eyelid defects appeared to be extensions of facial clefts in these patients and were often located adjacent to the corneal opacities. Other anomalies included microphthalmos, strabismus, and hypertelorism. One patient had the typical peripheral and facial stigmata of the amniotic band syndrome in association with a coloboma of the left iris and retina.

Abnormalities, Multiple↗