Intermittent mydriasis associated with carotid vascular occlusion

PurposeTo describe two cases of stereotyped, intermittent, neurologically isolated, unilateral mydriasis in patients with a history of acquired internal carotid artery (ICA) occlusive disease on the ipsilateral side.PatientsTwo patients with intermittent mydriasis.MethodsCase Series.ResultsCase one: A 78-year-old man experienced 10 episodes of intermittent, unilateral, and painless mydriasis in the left eye and had 100% occlusion of the left ICA artery due to atherosclerotic disease. Case two: A 26-year-old woman with history of migraine developed new painless, intermittent episodes of unilateral mydriasis after sustaining chest trauma and was diagnosed with subsequent dissection and 65% occlusion of the ipsilateral ICA. Neither patient developed permanent anisocoria.ConclusionBenign episodic unilateral mydriasis (BEUM) typically presents in young women with a history of migraine. To our knowledge, these are the first cases of episodic, unilateral, neurologically isolated mydriasis associated with occlusive disease of the ICA in the English language ophthalmic literature. We hypothesize that transient dysfunction of the autonomic nervous system related to the ICA disease may account for the intermittent mydriatic episodes in these patients and we recommend consideration for imaging of the ICA in patients with atypical features for BEUM (for example, old age or males, non-isolated mydriasis, or recent trauma).

Neuro-ophthalmologic Aspects of Ameloblastoma

Ameloblastomas are histologically benign tumors derived from the odontogenic apparatus. Although these tumors are locally invasive, they rarely invade the paranasal sinuses, orbits, or intracranial cavity, and, thus, they rarely produce ophthalmologic signs and symptoms. In this report, we describe the neuro-ophthalmologic features of three patients with chronically aggressive ameloblastoma. Two of the patients developed a progressive and recurrent orbital apex and cavernous sinus syndromes. One of these patients is, to our knowledge, the first patient described with orbital and cavernous simus involvement by an ameloblastoma initially arising in the mandible. The other is only the second case described with bilateral orbital involvement. The third patient in this series developed a trigeminal sensory neuropathy as the only sign of the tumor. Although ameloblastomas are benign, slowly growing tumors, they may, often over a long period of time, cause significant neuro-ophthalmologic and orbital manifestutions that can only be partially ameliorated by surgery.

Abstract P4-05-05: Stromal Response to 14-Day Preoperative Therapy in Postmenopausal Oestrogen Receptor Positive Breast Cancer

Background: Stromal-epithelial interaction is a key factor in tumour progression. Cancer-associated fibroblasts (CAFs) and macrophage infiltration have been associated with early relapse in breast cancer. Bisphosphonates are effective inhibitors of osteoclast activation in metastatic breast cancer but also have a general inhibitory effect on breast cancer progression. In order to monitor a potential tumour stromal response in breast cancer during treatment with an aromatase inhibitor and a bisphosphonate we analysed pre-and post-treatment samples from a neoadjuvant window study and focused on the presence of macrophages and CAFs.

Materials and methods: Tissue microarrays (TMAs) from surgical samples and pre-operative core biopsies were immunohistochemically stained for aSMA (CAF marker), CD68 (macrophages) and epithelial proliferation (Ki67). In order to validate if the presence of macrophages and aSMA could be monitored by the TMA approach, we initially analysed a screening cohort of 144 breast cancer samples. We then studied pre-and post-treatment samples from 110 postmenopausal ER-positive invasive breast cancer patients randomised to receive 14 days of preoperative treatment (placebo, Letrozole, or Letrozole plus Zoledronate). Results: In the screening cohort, we observed significant links between aSMA positive fibroblasts and disease recurrence as well as between CD68 positive macrophages and tumour size, grade, lymph node positivity and recurrence. This validated the use of TMAs for stromal analyses and furthersupported a link with key tumour biological events. In both treatment arms, there was a significant drop in absolute Ki67 value compared to placebo (-9.3% Letrozole and -13.1% combination reduction versus 1% increase, P<0.001). Post-treatment CD68 (median 35, range 3 to 117) was significantly linked to a Ki67 drop (p=0.045). Interestingly, this effect was mainly observed in the combination treatment group (p=0.002). aSMA expression was unaffected during treatment in 52%, increased in 35% and decreased in 13% of cases. Patients with aSMA reduction post treatment had a larger Ki67 fall compared to patients with increase or no change in aSMA (p=0.007).

Conclusion: Short term treatment response in the epithelial component of cancers was paralleled by specific responses in the tumour stromal component. These novel findings suggest that bisphosphonates and aromatase inhibitors have major effects on tumour stroma in vivo which might augment their inhibitory effect on tumour progression.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P4-05-05.

Psychological Androgyny and Social Desirability

The concept of psychological androgyny, because of its implications for sex roles, social change, and human development, is presently of special theoretical interest. Psychologically androgynous persons, as identified by the Bern Sex Role Inventory (BSRI), score higher on both its femininity and masculinity scales. Given the psychometric properties of the BSRI, it can be hypothesized that androgynous persons will have higher social desirability scores. Yet, the "masculine male" and the "feminine female" may be the most socially desirable, in that they conform to normative expectations. Consequently it can also be hypothesized that individuals who are either masculine-typed males or feminine-typed females on the BSRI will have the higher social desirability scores. Neither prediction was found to be entirely accurate; instead, androgynous and feminine-typed individuals were found to have higher social desirability scores. Moreover, the data reveal that the BSRI femininity scale has social desirability characteristics which are sex-specific.

Long-term follow-up of idiopathic intracranial hypertension: the Iowa experience

OBJECTIVE

To evaluate recurrent or delayed worsening of papilledema and visual function in patients with idiopathic intracranial hypertension (IIH) followed for more than 10 years.

METHODS

This is an Institutional Review Board approved retrospective chart review of 410 patients with the diagnosis of IIH evaluated at the University of Iowa Hospitals and Clinics from January 1984 to January 1996. Of the 410 patients, 20 patients with IIH who were followed over 10 years at the neuro-ophthalmology clinic met the inclusion criteria. Three neuro-ophthalmologists independently evaluated and graded the visual field examinations and optic disc stereo-photographs for each follow-up visit (median = 15).

RESULTS

Of the 20 patients, 11 demonstrated a stable course of disease without worsening in papilledema or visual field, and 9 patients worsened after a stable course. Of these 9 patients, 6 patients experienced delayed worsening (range: 28 to 135 months from presentation) and 3 patients had recurrence after resolution of papilledema 12 to 78 months from initial resolution of the IIH.

CONCLUSION

Idiopathic intracranial hypertension is a chronic condition that may worsen after a period of stability, warranting long-term follow-up.

MRI findings in Susac's syndrome

BACKGROUND

Susac syndrome (SS) is a self-limited syndrome, presumably autoimmune, consisting of a clinical triad of encephalopathy, branch retinal artery occlusions, and hearing loss. All three elements of the triad may not be present or recognized, and MR imaging is often necessary to establish the diagnosis.

OBJECTIVE

To determine the spectrum of abnormalities on MRI in SS.

METHODS

The authors reviewed the MR images of 27 previously unreported patients with the clinical SS triad, and 51 patients from published articles in which the MR images were depicted or reported.

RESULTS

All 27 patients had multifocal supratentorial white matter lesions including the corpus callosum. The deep gray nuclei (basal ganglia and thalamus) were involved in 19 (70%). Nineteen (70%) also had parenchymal enhancement and 9 (33%) had leptomeningeal enhancement. Of the 51 cases from the literature, at least 32 had callosal lesions. The authors could not determine the presence of callosal lesions in 18 of these patients, and only one was reported to have a normal MRI at the onset of encephalopathy.

CONCLUSIONS

The MR scans in SS show a rather distinctive pattern of supratentorial white matter lesions that always involve the corpus callosum. There is often deep gray matter, posterior fossa involvement, and frequent parenchymal with occasional leptomeningeal enhancement. The central callosal lesions differ from those in demyelinating disease, and should support the diagnosis of SS in patients with at least two of the three features of the clinical triad.

Accuracy of clinical detection of INO in MS: Corroboration with quantitative infrared oculography

The authors compared the accuracy of clinical detection (by 279 physician observers) of internuclear ophthalmoparesis (INO) with that of quantitative infrared oculography. For the patients with mild adduction slowing, INO was not identified by 71%. Intermediate dysconjugacy was not detected by 25% of the evaluators. In the most severe cases, INO was not identified by only 6%. Oculographic techniques significantly enhance the precision of INO detection compared to the clinical exam.

Artemisinins target the SERCA of Plasmodium falciparum

Artemisinins are extracted from sweet wormwood (Artemisia annua) and are the most potent antimalarials available, rapidly killing all asexual stages of Plasmodium falciparum. Artemisinins are sesquiterpene lactones widely used to treat multidrug-resistant malaria, a disease that annually claims 1 million lives. Despite extensive clinical and laboratory experience their molecular target is not yet identified. Activated artemisinins form adducts with a variety of biological macromolecules, including haem, translationally controlled tumour protein (TCTP) and other higher-molecular-weight proteins. Here we show that artemisinins, but not quinine or chloroquine, inhibit the SERCA orthologue (PfATP6) of Plasmodium falciparum in Xenopus oocytes with similar potency to thapsigargin (another sesquiterpene lactone and highly specific SERCA inhibitor). As predicted, thapsigargin also antagonizes the parasiticidal activity of artemisinin. Desoxyartemisinin lacks an endoperoxide bridge and is ineffective both as an inhibitor of PfATP6 and as an antimalarial. Chelation of iron by desferrioxamine abrogates the antiparasitic activity of artemisinins and correspondingly attenuates inhibition of PfATP6. Imaging of parasites with BODIPY-thapsigargin labels the cytosolic compartment and is competed by artemisinin. Fluorescent artemisinin labels parasites similarly and irreversibly in an Fe2+-dependent manner. These data provide compelling evidence that artemisinins act by inhibiting PfATP6 outside the food vacuole after activation by iron.

The potassium channel KcsA and its interaction with the lipid bilayer

The crystal structure of the K+ channel KcsA explains many features of ion channel function. The selectivity filter corresponds to a narrow region about 12 Along and 3 A wide, lined by carbonyl groups of the peptide backbone, through which a K+ ion can only move ina dehydrated form. The selectivity filter opens into a central, water-filled cavity leading to a gating site on the intracellular side of the channel. The channel is tetrameric, each monomer containing two transmembrane a helices, M1 and M2. Helix M1 faces the lipid bi-layer and helix M2 faces the central channel pore; the M2 helices participate in subunit-subunit interactions. Helices M1 and M2 in each subunit pack as a pair of antiparallel coils with a heptad repeat, but the M2 helices of neighbouring subunits show fewer interactions, crossing at an angle of about -40 degrees. Trp residues at the ends of the transmembrane a helices form clear girdles on the two faces of the membrane, which, together with girdles of charged residues, define a hydrophobic thickness of about 37 A for the channel. Binding constants for phosphatidylcholines to KcsA vary with fatty acyl chain length, the optimum chain length being C22. A phosphatidylcholine with this chain length gives a bilayer of thickness about 34 A in the liquid crystalline phase, matching the hydrophobic thickness of the protein. However, a typical biological membrane has a hydrophobic thickness of about 27 A. Thus either the transmembrane a helices of KcsA are more tilted in the native membrane than they are in the crystal structure, or the channel is under stress in the native membrane. The efficiency of hydrophobic matching between KcsA and the surrounding lipid bilayer is high over the chain length range C10-C24. The channel requires the presence of some anionic lipids for function, and fluorescence quenching studies show the presence of two classes of lipid binding site on KcsA; at one class of site (nonannular sites) anionic phospholipids bind more strongly than phosphatidylcholine, whereas at the other class of site (annular sites) phosphatidylcholines and anionic phospholipids bind with equal affinity.

Mechanism of binding of warfarin enantiomers to recombinant domains of human albumin

Domain fragments of human serum albumin corresponding to domains 1 and 2 (D12) and domains 2 and 3 (D23) were expressed in yeast. The kinetics of warfarin binding to these fragments were investigated using stopped-flow fluorescence spectroscopy. Binding can be characterized by a two-step process, a rapid diffusion-controlled step and a slower rate-limiting step in which a stable drug-protein complex is formed. The equilibrium constant for step 1 is greater for both D12 and D23 than for albumin, probably as a result of reduced steric hindrance offered by the domain fragments. Binding step 2, thought to be the result of a conformational change as warfarin is accommodated by the protein, is faster for D12 and D23. Albumin and the domain fragments show an increased preference for the R enantiomer, but the preference is particularly enhanced for domain fragment D12. These preferences can largely be explained by the domains having different rates for step 2 of the binding process.

Lipid-protein interactions in biological membranes: a structural perspective

Lipid molecules bound to membrane proteins are resolved in some high-resolution structures of membrane proteins. An analysis of these structures provides a framework within which to analyse the nature of lipid-protein interactions within membranes. Membrane proteins are surrounded by a shell or annulus of lipid molecules, equivalent to the solvent layer surrounding a water-soluble protein. The lipid bilayer extends right up to the membrane protein, with a uniform thickness around the protein. The surface of a membrane protein contains many shallow grooves and protrusions to which the fatty acyl chains of the surrounding lipids conform to provide tight packing into the membrane. An individual lipid molecule will remain in the annular shell around a protein for only a short period of time. Binding to the annular shell shows relatively little structural specificity. As well as the annular lipid, there is evidence for other lipid molecules bound between the transmembrane alpha-helices of the protein; these lipids are referred to as non-annular lipids. The average thickness of the hydrophobic domain of a membrane protein is about 29 A, with a few proteins having significantly smaller or greater thicknesses than the average. Hydrophobic mismatch between a membrane protein and the surrounding lipid bilayer generally leads to only small changes in membrane thickness. Possible adaptations in the protein to minimise mismatch include tilting of the helices and rotation of side chains at the ends of the helices. Packing of transmembrane alpha-helices is dependent on the chain length of the surrounding phospholipids. The function of membrane proteins is dependent on the thickness of the surrounding lipid bilayer, sometimes on the presence of specific, usually anionic, phospholipids, and sometimes on the phase of the phospholipid.

Ca2+ -ATPase structure in the E1 and E2 conformations: mechanism, helix-helix and helix-lipid interactions

The determination of the crystal structure of the Ca(2+)-ATPase of sarcoplasmic reticulum (SR) in its Ca(2+)-bound [Nature 405 (2000) 647] and Ca(2+)-free forms [Nature 418 (2002) 605] gives the opportunity for an analysis of conformational changes on the Ca(2+)-ATPase and of helix-helix and helix-lipid interactions in the transmembrane (TM) region of the ATPase. The locations of the ends of the TM alpha-helices on the cytoplasmic side of the membrane are reasonably well defined by the location of Trp residues and by the location of Lys-262 that snorkels up to the surface. The locations of the lumenal ends of the helices are less clear. The position of Lys-972 on the lumenal side of helix M9 suggests that the hydrophobic thickness of the protein is only about 21 A, rather than the normal 30 A. The experimentally determined TM alpha-helices do not agree well with those predicted theoretically. Charged headgroups are required for strong interaction of lipids with the ATPase, consistent with the large number of charged residues located close to the lipid-water interface. Helix packing appears to be rather irregular. Packing of helices M8 and M10 is of the 3-4 ridges-into-grooves or knobs-into-holes types. Packing of helices M5 and M7 involves two Gly residues in M7 and one Gly residue in M5. Packing of the other helices generally involves just one or two residues on each helix at the crossing point. The irregular packing of the TM alpha-helices in the Ca(2+)-ATPase, combined with the diffuse structure of the ATPase on the lumenal side of the membrane, is suggested to lead to a relative low activation energy for changing the packing of the TM alpha-helices, with changes in TM alpha-helical packing being important in the process of transfer of Ca(2+) ions across the membrane. The inhibitor thapsigargin binds in a cleft between TM alpha-helices M3, M5 and M7. It is suggested that this and other similar clefts provide binding sites for a variety of hydrophobic molecules affecting the activity of the Ca(2+)-ATPase.

The management of the red eye for the generalist

Patients often present to primary care physicians with acute or chronic red eyes. Benign conditions may be evaluated and treated by primary care practitioners. Red eyes due to serious conditions may be vision threatening and require early detection and referral.

Curcumin, a molecule that inhibits the Ca2+-ATPase of sarcoplasmic reticulum but increases the rate of accumulation of Ca2+

Curcumin, an important inhibitor of carcinogenesis, is an inhibitor of the ATPase activity of the Ca(2+)-ATPase of skeletal muscle sarcoplasmic reticulum (SR). Inhibition by curcumin is structurally specific, requiring the presence of a pair of -OH groups at the 4-position of the rings. Inhibition is not competitive with ATP. Unexpectedly, addition of curcumin to SR vesicles leads to an increase in the rate of accumulation of Ca(2+), unlike other inhibitors of the Ca(2+)-ATPase that result in a reduced rate of accumulation. An increase in the rate of accumulation of Ca(2+) is seen in the presence of phosphate ion, which lowers the concentration of free Ca(2+) within the lumen of the SR, showing that the effect is not passive leak across the SR membrane. Rather, simulations suggest that the effect is to reduce the rate of slippage on the ATPase, a process in which a Ca(2+)-bound, phosphorylated intermediate releases its bound Ca(2+) on the cytoplasmic rather than on the lumenal side of the membrane. The structural specificity of the effects of curcumin on ATPase activity and on Ca(2+) accumulation is the same, and the apparent dissociation constants for the two effects are similar, suggesting that the two effects of curcumin could follow from binding to a single site on the ATPase.

Effects of phospholipid headgroup and phase on the activity of diacylglycerol kinase of Escherichia coli

Diacylglycerol kinase (DGK) of Escherichia coli has been reconstituted into a variety of phospholipid bilayers and its activity determined as a function of lipid headgroup structure and phase preference. The anionic phospholipids dioleoylphosphatidic acid, dioleoylphosphatidylserine, and cardiolipin were all found to support activities lower than that supported by dioleoylphosphatidylcholine. In mixtures of dioleoylphosphatidylcholine and 20 mol % anionic phospholipids, the presence of anionic phospholipids all resulted in lower activities than in dioleoylphosphatidylcholine, except for dioleoylphosphatidylglycerol whose presence had little effect on activity. In some cases, the low activity in the presence of anionic phospholipid followed from a decrease in v(max); in some cases, it followed from an increase in the K(m) for diacylglycerol, and in the case of dioleoylphosphatidic acid, it followed from both. Activities in mixtures containing 80 mol % dioleoylphosphatidylethanolamine were lower than in dioleoylphosphatidylcholine at temperatures where both lipids adopted a bilayer phase; at higher temperatures where dioleoylphosphatidylethanolamine preferred a hexagonal H(II) phase, the differences in activity were greater. These experiments suggest that the presence of lipids preferring a hexagonal H(II) phase leads to low activities. Activities of DGK are low in a gel phase lipid.

Self-association of model transmembrane alpha-helices is modulated by lipid structure

We have developed a fluorescence quenching method using peptides containing 3,5-dibromotryrosine to measure oligomerization of model transmembrane alpha-helices in lipid bilayers. Peptides of the type Ac-LysLysGlyLeu(m)XLeu(n)LysLysAla-amide where X is tryptophan or 3,5-dibromotyrosine were found to form heterodimers in bilayers of phosphatidylcholine in the liquid-crystalline phase. The free energy of dimer formation changed little with increasing number of Leu residues from 16 to 22 but increased with increasing phospholipid fatty acyl chain length, with a slope of about 0.5 kJ mol(-1) per fatty acyl chain carbon. Peptides were excluded from lipid in the gel phase, resulting in increased levels of oligomerization. Addition of cholesterol to form the liquid-ordered state led to increased dimerization but without phase separation. The presence of phosphatidylethanolamine had little effect on dimerization.

Improvement in papilledema and visual loss after endovascular stent placement in dural sinus thrombosis

OBJECTIVE

To report two cases of cerebral venous sinus thrombosis with papilledema and visual loss that improved after endovascular stent placement.

MATERIALS AND METHODS

Retrospective case series from a tertiary ophthalmic center.

RESULTS

Two cases of venous sinus occlusion treated with angioplasty and stenting are described. Both cases experienced improvement in optic disc edema and visual function following the procedures.

CONCLUSION

Endovascular stent placement may relieve increased intracranial pressure and papilledema caused by cerebral sinus thrombosis and may prevent further visual loss.

Recurrent idiopathic familial facial nerve palsy and ophthalmoplegia

INTRODUCTION

Idiopathic facial nerve palsy is a common neurologic condition but episodes of ophthalmoplegia in these patients are uncommon.

MATERIALS AND METHODS

Retrospective case series.

RESULTS

Three patients with facial nerve palsy with unusual features, including ophthalmoplegia, are described.

CONCLUSION

Recurrent episodes, familial tendency, and associated ophthalmoplegia are uncommon in patients with idiopathic facial nerve palsy.

Effects of bilayer thickness on the activity of diacylglycerol kinase of Escherichia coli

We have developed a procedure for the reconstitution of Escherichia coli diacylglycerol kinase (DGK) into phospholipid bilayers containing diacylglycerol substrate. When DGK is reconstituted into a series of phosphatidylcholines containing monounsaturated fatty acyl chains, activity against dihexanoylglycerol (DHG) as a substrate was found to be markedly dependent on the fatty acyl chain length with the highest activity in dioleoylphosphatidylcholine [di(C18:1)PC] and a lower activity in bilayers with shorter or longer fatty acyl chains. Low activities in the short chain phospholipid dimyristoleoylphosphatidylcholine [di(C14:1)PC] followed from an increase in the K(m) value for DHG and ATP, with no effect on v(max). In contrast, in the long chain lipid dierucoylphosphatidylcholine [di(C24:1)PC], the low activity followed from a decrease in v(max) with no effect on K(m). In mixtures of two phosphatidylcholines with different chain lengths, the activity corresponded to that expected for the average chain length of the mixture. Cholesterol increased the activity in di(C14:1)PC but slightly decreased it in di(C18:1)PC or di(C24:1)PC, effects that could follow from changes in bilayer thickness caused by cholesterol.

Orbital presentations of giant cell arteritis

BACKGROUND

giant cell arteritis (GCA) is a systemic vasculitis that may affect the optic nerve and cause blindness (e.g. ischemic optic neuropathy). Orbital inflammatory disease, however, is an uncommon presentation of GCA.

PURPOSE

to alert clinicians to the orbital presentations of GCA.

PATIENTS AND METHODS

a retrospective case series from tertiary care academic ophthalmic referral centers of four patients with orbital manifestations of giant cell arteritis.

RESULTS

presentation of cases and review of the literature. In three cases, a temporal artery biopsy was diagnostic of GCA, but in one case, an orbital biopsy was needed to confirm the diagnosis.

CONCLUSION

GCA can have orbital manifestations and clinicians should be aware of this unusual presentation of GCA in cases of presumed orbital inflammatory pseudotumor in the elderly.

What the structure of a calcium pump tells us about its mechanism

The report of the crystal structure of the Ca(2+)-ATPase of skeletal muscle sarcoplasmic reticulum in its Ca(2+)-bound form [Toyoshima, Nakasako and Ogawa (2000) Nature (London) 405, 647-655] provides an opportunity to interpret much kinetic and mutagenic data on the ATPase in structural terms. There are no large channels leading from the cytoplasmic surface to the pair of high-affinity Ca(2+) binding sites within the transmembrane region. One possible access pathway involves the charged residues in transmembrane alpha-helix M1, with a Ca(2+) ion passing through the first site to reach the second site. The Ca(2+)-ATPase also contains a pair of binding sites for Ca(2+) that are exposed to the lumen. In the four-site model for transport, phosphorylation of the ATPase leads to transfer of the two bound Ca(2+) ions from the cytoplasmic to the lumenal pair of sites. In the alternating four-site model for transport, phosphorylation leads to release of the bound Ca(2+) ions directly from the cytoplasmic pair of sites, linked to closure of the pair of lumenal binding sites. The lumenal pair of sites could involve a cluster of conserved acidic residues in the loop between M1 and M2. Since there is no obvious pathway from the high-affinity sites to the lumenal surface of the membrane, transport of Ca(2+) ions must involve a significant change in the packing of the transmembrane alpha-helices. The link between the phosphorylation domain and the pair of high-affinity Ca(2+) binding sites is probably provided by two small helices, P1 and P2, in the phosphorylation domain, which contact the loop between transmembrane alpha-helices M6 and M7.

Primary central nervous system lymphoma involving the optic chiasm in AIDS

OBJECTIVE

To report visual loss resulting from chiasmal involvement by primary central nervous system lymphoma (PCNSL).

MATERIALS AND METHODS

Case report.

RESULTS

A patient with the acquired immune deficiency syndrome (AIDS) presented with visual loss resulting from PCNSL involving the optic chiasm. The clinical findings, neuroimaging, pathology, and treatment of this patient are described.

CONCLUSIONS

Although rare, clinicians should consider PCNSL in the differential of a hypothalamic/chiasmal mass, especially in a patient with AIDS.

Orbital solitary fibrous tumor: radiographic and histopathologic correlations

OBJECTIVE

To correlate the clinicopathologic and radiographic features characteristic of orbital solitary fibrous tumor (SFT).

METHODS

The diagnostic features and clinical outcome of seven adults with orbital SFT are retrospectively outlined. Orbital imaging was performed by ultrasonography, computed tomography, or magnetic resonance imaging. Some cases were imaged by multiple modalities. Histopathologic examination of each tumor specimen included standard light and immunohistochemical stains.

RESULTS

Heterogeneous internal composition was better appreciated on magnetic resonance imaging than on computed tomography. All cases undergoing magnetic resonance imaging showed T1 isointensity and T2 hypointensity relative to gray matter. Strong, generalized immunohistochemical reactivity to vimentin and CD34 validated the diagnosis of SFT and differentiated the specimens from other spindle cell neoplasms. After complete tumor resection, our patients remain tumor free with postoperative intervals of 15 to 45 months.

CONCLUSIONS

Solitary fibrous tumor has now been reported in 26 orbits. No physical finding is pathognomonic, but several imaging traits are highly characteristic. Intralesional image heterogeneity and a predominantly low T2 signal intensity are distinctive of SFT. Complete tumor resection and immunohistologic specimen evaluation are emphasized. Clinicians should consider the diagnosis of SFT when confronted with an adult patient having an orbital soft tissue mass demonstrating the distinctive magnetic resonance imaging findings.

Acute multifocal placoid pigment epitheliopathy and central nervous system involvement: nine new cases and a review of the literature

OBJECTIVE

The authors describe nine new cases of acute multifocal placoid pigment epitheliopathy (AMPPE) with associated central nervous system (CNS) involvement and permanent visual sequelae. The study includes a review of the literature and discussion of evaluation, management, and treatment options.

DESIGN

Retrospective, noncomparative case series.

PARTICIPANTS

Nine patients were identified with AMPPE and CNS involvement in addition to 22 patients reviewed in the literature.

MAIN OUTCOME MEASURES

A review of nine patients with AMPPE and CNS involvement was performed. Charts were reviewed for age, gender, preceding viral prodromes, visual acuity, ophthalmologic examination findings, CNS findings, and treatment.

RESULTS

Thirty-one patients (nine new patients) were diagnosed with AMPPE and various degrees of CNS involvement. Ages ranged from 8 to 54 years, with an average of 27 years. Twenty-one males (68%) and 10 females (32%) were identified. Eleven patients (35%) had antecedent viral illnesses. Visual acuity was variable and ranged from 20/20 to count fingers. The spectrum of CNS findings ranged from headaches to sagittal sinus thrombosis.

CONCLUSIONS

Acute multifocal placoid pigment epitheliopathy can be associated with CNS abnormalities and permanent visual deficits. Neuroimaging, lumbar puncture, and cerebral angiography analysis provide useful diagnostic tools when CNS involvement is suspected. Intravenous corticosteroids and collaboration with neurovascular colleagues should be considered in these situations. In cases complicated by CNS arteritis, immunosuppressive agents can be a beneficial adjunct to corticosteroids.

Myasthenia gravis with ocular involvement in older patients

BACKGROUND

There has been little previous study reporting the eye findings and presentation of elderly patients with myasthenia gravis. The purpose of this study was to review the findings and course of myasthenia gravis after the sixth decade of life.

METHODS

Retrospective observational case series. The authors reviewed the clinical records of 27 patients with onset of myasthenia gravis at age 60 years or more who were seen at a tertiary care academic ophthalmology centre in Houston between January 1992 and March 1999. The diagnosis of myasthenia gravis was based on conventional clinical and laboratory criteria.

RESULTS

Twenty patients (74%) were men. Of the 16 patients who underwent testing for anti-acetylcholine receptor antibodies, 11 (69%) were seropositive. Concurrent thyroid disease was found in seven patients (26%), including five (71%) of the seven women. No patient had thymoma. Sixteen patients (59%) manifested generalized symptoms during follow-up; 12 did so within 1 year of disease onset. Patients responded well to both anticholinesterase and corticosteroid therapy. At the most recent follow-up visit 18 patients (67%) were clinically improved, and no patient was clinically worse.

INTERPRETATION

Myasthenia gravis in this study was characterized by a male predominance, high rate of concurrent thyroid disease, high rate of progression to mild generalized symptoms, absence of thymoma, good response to medical therapy and minimal life-threatening complications. Clinicians should consider the diagnosis of myasthenia gravis in an older patient presenting with diplopia or ptosis.

Myelin: Delivery by raft

Recent results suggest that membrane proteins are delivered to the myelin sheath of an oligodendrocyte on rafts with a distinctive lipid composition. The major intrinsic membrane protein of myelin, proteolipid protein, interacts with rafts in oligodendrocytes but not with the different rafts found in other cell types.

Optic neuropathy associated with laser in situ keratomileusis

PURPOSE

To report 4 cases of optic neuropathy following laser in situ keratomileusis (LASIK).

SETTING

Tertiary Care ophthalmic practices.

METHODS

In this retrospective observational case series, 4 patients who developed acute visual loss following LASIK are reported. All had clinical evidence of optic neuropathy. Two had optic disc edema and 2 had normal appearing optic discs initially. None of the patients experienced significant visual recovery, and all developed optic atrophy in the affected eye.

RESULTS

All patients had evaluations for alternative etiologies of their optic neuropathy, with negative results. All patients were therefore presumed to have experienced an ischemic optic neuropathy following LASIK.

CONCLUSIONS

Patients who have LASIK may experience an acute anterior or retrobulbar optic neuropathy. The etiology is unknown but may be related to the marked increase in intraocular pressure that occurs during a portion of the procedure.

Neuroimaging contrast agents in ophthalmology

Magnetic resonance (MR) imaging and computed tomography (CT) are routinely performed with the use of contrast materials in the diagnosis of neuro-ophthalmologic disease. Iodinated agents are commonly used in CT scanning and femoral contrast arteriography, and gadolinium is used in MR imaging. While contrast materials contribute greatly to diagnostic accuracy, they may also be responsible for adverse effects, ranging in severity from mild discomfort to death. The most frequent and severe side effects are associated with ionic iodinated contrast agents, while the rate of adverse reactions is less with use of nonionic iodinated contrast agents. Side effects and adverse reactions to gadolinium are uncommon, but they do occur. In neuro-ophthalmologic diagnosis, MR imaging is generally preferred over CT scanning, partly because of its greater ability to delineate soft tissue intracranial structures, but also because of the relative safety of gadolinium as a contrast agent. Properties of contrast agents are discussed in the context of specific imaging techniques and tissues investigated. Types and severity of adverse effects as well as risk factors for incurring such effects are summarized.

Selectivity in lipid binding to the bacterial outer membrane protein OmpF

The outer membrane porin OmpF from Escherichia coli has been reconstituted into lipid bilayers of defined composition, and fluorescence spectroscopy is used to characterize its interaction with the surrounding lipid. OmpF is a trimer within the membrane. It contains two Trp residues per monomer, Trp(214) at the lipid-protein interface and Trp(61) at the trimer interface. The fluorescence of Trp-214 in the mutant W61F is quenched by dibromostearoylphosphatidylcholine (di(Br(2)C18:0)PC), whereas the fluorescence of Trp(61) in the mutant W214F is not quenched by di(Br(2)C18:0)PC when fluorescence is excited directly through the Trp rather than through the Tyr residues. Measurements of relative fluorescence quenching for OmpF reconstituted into mixtures of lipid X and di(Br(2)C18:0)PC have been analyzed to give the binding constant of lipid X for OmpF, relative to that for dioleoylphosphatidylcholine (di(C18:1)PC). The phosphatidylcholine showing the strongest binding to OmpF is dimyristoyloleoylphosphatidylcholine (di(C14:1)PC) with binding constants decreasing with either increasing or decreasing fatty acyl chain length. Comparison with various theories for hydrophobic matching between lipids and proteins suggests that in the chain length range from C14 to C20, hydrophobic matching is achieved largely by distortion of the lipid bilayer around the OmpF, whereas for chains longer than C20, distortion of both the lipid bilayer and of the protein is required to achieve hydrophobic matching. Phosphatidylcholine and phosphatidylethanolamine bind with equal affinity to OmpF, but the affinity for phosphatidylglycerol is about half that for phosphatidylcholine.