Edge-on adsorption of multi-chain functional alkanes stabilizes noncovalent monolayers on MoS2

Diyne phospholipids adsorb edge-on on MoS₂, producing stable monolayers with large, ordered domains, despite low alkane adsorption enthalpies on MoS₂.

High sensitivity cardiac troponin T in patients with immunoglobulin light chain amyloidosis

OBJECTIVES

To define whether the high sensitivity cardiac troponin T (hs-cTnT) assay in patients with immunoglobulin light chain amyloidosis (AL) improves risk prediction.

BACKGROUND

Cardiac involvement is the major cause of death in patients with AL amyloidosis. Risk stratification is facilitated by cardiac biomarkers such as cardiac troponin T (cTnT) and N-terminal pro B-type natriuretic peptide (NT-proBNP).

METHODS

Stored serum from patients with newly diagnosed AL was used to measure hs-cTnT, cTnT, and NT-proBNP. Survival modelling was performed.

RESULTS

The direct numeric result from hs-cTnT measurement cannot merely be substituted for a cTnT measurement in the Mayo AL staging system. The performance of the receiver operator curve derived an hs-cTnT cut-point of 54 ng/L which improves on the value of 35 ng/L validated with the prior iteration of the assay. An alternate staging option using hs-cTnT alone-using the two thresholds 14 ng/L and 54 ng/L-performs as well as either the original Mayo AL staging system or other systems incorporating hs-cTnT. On multivariate analysis, an hs-cTnT alone staging system was independent of period of diagnosis, type of therapy, and NT-proBNP value, the last of which dropped out of the model. Alternate models were explored, but none performed better than the original system or the new hs-cTnT system. Thus, hs-cTnT can be used alone for the staging of disease prognosis.

CONCLUSIONS

A survival model based on hs-cTnT improves the prognostic staging of patients with AL amyloidosis, relegating NT-proBNP to a measure of cardiac response.

Phenotypic heterogeneity associated with a novel mutation (Gly112Glu) in the Norrie disease protein

PURPOSE

To determine the molecular pathology and clinical severity of two pedigrees with a history of early retinal detachment and peripheral retinal vascular abnormalities.

DESIGN

Longitudinal cohort study.

METHODS

A longitudinal clinical study and DNA analysis was performed on 49 family members of two pedigrees.

RESULTS

Nine individuals were found to be hemizygous for a mutation at codon 112 (Gly112Glu) of the Norrie disease protein (NDP) in one pedigree. Significant phenotypic heterogeneity was found. The proband presented with a unilateral subtotal retinal detachment at the age of 3 years, and subsequently developed a slowly progressive tractional retinal detachment involving the macula in the contralateral eye at the age of 4 years. One individual had only mild peripheral retinal pigmentary changes with normal vision at the age of 79 years. The remaining seven individuals had varying degrees of peripheral retinal vascular abnormalities and anterior segment findings. Seven affected members of a second pedigree affected by a previously reported mutation, Arg74Cys, also demonstrated wide ocular phenotypic variation.

CONCLUSION

A novel mutation (Gly112Glu), which represents the most carboxy located, NDP mutation reported, results in significant phenotypic heterogeneity. These data support the contention that the spectrum of ocular disease severity associated with these NDP mutations is broad. Use of terms that characterize this entity by phenotypic appearance, such as familial exudative vitreoretinopathy, do not adequately communicate the potential spectrum of severity of this disorder to affected or carrier family members.

Vitreous and retinal amino acid concentrations in experimental central retinal artery occlusion in the primate

PURPOSE

Vitreous and retinal amino-acid concentrations were evaluated in a primate model of central retinal artery occlusion (CRAO) to study the role of glutamate excitotoxicity in acute retinal ischaemia.

METHODS

Unilateral, acute CRAO was produced by temporary clamping of the central retinal artery for 190 min in four elderly rhesus monkeys. Fundus photography, fluorescein angiography, and electroretinogram were performed before and during CRAO, and after unclamping the artery. Vitreous samples were obtained before and after CRAO in both eyes, and analysed for 13 amino-acid concentrations using high-pressure liquid chromatography. The animals were killed 350 min after retinal reperfusion, and the retinal tissue was submitted for amino-acid analysis.

RESULTS

In all four eyes, the macula showed the 'cherry red spot'. The CRAO was confirmed by fluorescein angiography and decreased b-wave on electroretinogram. Retinal histology confirmed ischaemic changes in the inner retina. Changes in all 13 vitreous amino-acid concentrations after CRAO (including glutamate) were not significantly different between study and control eyes (P = 0.09 to 0.82). All retinal amino-acid concentrations (including glutamate) were not significantly different between two eyes (P = 0.07-0.93).

CONCLUSIONS

In the primate model of acute inner retinal ischaemia induced by transient CRAO, we were unable to detect significantly elevated concentrations of vitreous and retinal glutamate. Our primate model has the advantage of closely modelling the CRAO in humans. Further basic and clinical studies are needed to elucidate the role of glutamate excitotoxicity in retinal ischaemia.

Optic disc, foveal, and extrafoveal damage due to surgical separation of the vitreous

OBJECTIVE

To evaluate the morphologic outcomes resulting from surgical vitreoretinal separation in young adult primates.

MATERIALS AND METHODS

Vitrectomy and mechanical separation of the vitreous from the internal limiting lamina (ILL) of the posterior retina and surface of the optic disc were performed on 25 young adult cynomolgus monkey eyes in vivo. Lectin histochemical studies were used to evaluate the vitreoretinal interface. Morphologic outcomes were tabulated.

RESULTS

In 11 of 25 eye regions, residual vitreous remained attached to the ILL in some of the regions. Localized ILL breaks or separation of the ILL from the neural retina was noted in 9 eyes. Retinal tissue loss, including avulsion of the ganglion cell, inner plexiform, or inner nuclear layers, was observed in 7 eyes. Avulsion of axon bundles in the optic disc was noted in 9 eyes. Significantly, partial- or full-thickness foveal tears were noted in 11 eyes. Based on the surgeons' intraoperative observations, small superficial optic disc or retinal hemorrhages were observed in 3 of 25 eyes. None of the eyes on which a vitrectomy alone was performed showed ILL damage, or retinal or optic disc tissue loss.

CONCLUSION

Damage may occur to the optic disc, fovea, and extrafoveal retina as a result of surgical separation of the vitreous from the retina in young adult primates.

CLINICAL RELEVANCE

These data support the contention that surgically induced damage at the level of the vitreoretinal interface may help explain the visual field defects noted after surgery to close full-thickness macular holes. These data also support the need for developing additional modalities to assist in vitreous separation, thereby reducing the risk of traumatic complications associated with purely mechanical procedures.

The effect of vasodilators on aspirin-induced antagonism of t-PA thrombolysis

Although i.v. t-PA has proven successful in reducing neurologic deficits in acute ischemic stroke, the disadvantages of a narrow therapeutic time window and the failure of thrombolysis in more than 50% of patients treated have necessitated an examination of adjuvant therapies to improve the rate of thrombolysis. Experimentally, the combination of aspirin therapy with t-PA has resulted in a paradoxical antagonism of thrombolysis. Reversal of this antagonism with nitric oxide (NO) donors suggested that aspirin may inhibit/ antagonize NO-related mechanisms. Using this rabbit model of thromboembolic stroke, this hypothesis is now expanded to compare two clinically relevant anti-hypertensive agents, atenolol (NO-dependent) and hydralazine (NO-independent), for their ability to improve t-PA-mediated clot lysis following aspirin pre-treatment. Thirty rabbits (10 per group) were pre-treated with aspirin (20mg kg(-1), i.v.) and then randomized to receive either vehicle, atenolol (20 microg kg(-1) h(-1), i.v.) or hydralazine (10 microg kg(-1) min(-1), i.v.) beginning 30 min following autologous clot embolization. All rabbits then received t-PA (6.3 mg kg(-1), i.v.) beginning 1 h after embolization, with completion of the protocol 4 h after embolization. Aspirin therapy reduced regional cerebral blood flow (rCBF) from 82.8m +/- 4.7 to 62.5 +/- 6.6 (n = 30; p = 0.0005). In the aspirin control group only 30% (3 of 10) rabbits demonstrated complete clot lysis, whereas the combined atenolol (60%) and hydralazine (70%) groups experienced a clot lysis rate of 65% (13 of 20 rabbits), similar to clot lysis rates previously observed with t-PA alone. In a separate series of experiments, all agents able to reverse aspirin antagonism of thrombolysis demonstrated an improvement in rCBF, suggesting a common mechanism for this diverse group of agents in reversing aspirin's antagonism of thrombolysis.

Rapid (0.5 degrees C/min) minimally invasive induction of hypothermia using cold perfluorochemical lung lavage in dogs

OBJECTIVE

Demonstrate minimally invasive rapid body core and brain cooling in a large animal model.

DESIGN

Prospective controlled animal trial.

SETTING

Private research laboratory.

SUBJECTS

Adult dogs, anesthetized, mechanically ventilated.

INTERVENTIONS

Cyclic lung lavage with FC-75 perfluorochemical (PFC) was administered through a dual-lumen endotracheal system in the new technique of 'gas/liquid ventilation' (GLV). In Trial-I, lavage volume (V-lav) was 19 ml/kg, infused and withdrawn over a cycle period (tc) of 37 s. (effective lavage rate V'-lav=31 ml/kg/min.) Five dogs received cold (approximately 4 degrees C) PFC; two controls received isothermic PFC. In Trial-II, five dogs received GLV at V-lav=8.8 ml/kg, tc=16 s, V'-lav=36 ml/kg/min.

MEASUREMENTS AND MAIN RESULTS

Trial-I tympanic temperature change was -3.7+/-0.6 degrees C (SD) at 7.5 min, reaching -7.3+/-0.6 degrees C at 18 min. Heat transfer efficiency was 60%. In Trial-II, efficiency fell to 40%, but heat-exchange dead space (VDtherm) remained constant. Lung/blood thermal equilibration half-time was <8 s. Isothermic GLV caused hypercapnia unless gas ventilation was increased. At necropsy after euthanasia (24 h), modest lung injury was seen.

CONCLUSIONS

GLV cooling times are comparable to those for cardiopulmonary bypass. Heat and CO(2) removal can be independently controlled by changing the mix of lavage and gas ventilation. Due to VDtherm of approximately 6 ml/kg in dogs, efficient V-lav is >18 ml/kg. GLV cooling power appears more limited by PFC flows than lavage residence times. Concurrent gas ventilation may mitigate heat-diffusion limitations in liquid breathing, perhaps via bubble-induced turbulence.

16(R)-hydroxyeicosatetraenoic acid, a novel cytochrome P450 product of arachidonic acid, suppresses activation of human polymorphonuclear leukocyte and reduces intracranial pressure in a rabbit model of thromboembolic stroke

OBJECTIVE

Activated polymorphonuclear leukocytes (PMNs) have been suggested to contribute to the development of increased intracranial pressure (ICP). We recently demonstrated that human PMNs produce a novel cytochrome P450-derived arachidonic acid metabolite, 1 6(R)-hydroxyeicosatetraenoic acid [16(R)-HETE], that modulates their function. It was thus of interest to examine this novel mediator in an acute stroke model.

METHODS

16-HETE was assessed initially in a variety of human PMN and platelet in vitro assays and subsequently in an established rabbit model of thromboembolic stroke. A total of 50 rabbits completed a randomized, blinded, four-arm study, receiving 16(R)-HETE, tissue plasminogen activator, both, or neither. Experiments were completed 7 hours after autologous clot embolization. The primary end point for efficacy was the suppression of increased ICP.

RESULTS

In in vitro assays, 16(R)-HETE selectively inhibited human PMN adhesion and aggregation and leukotriene B4 synthesis. In the thromboembolic stroke model, animals that received 16(R)-HETE demonstrated significant suppression of increased ICP (7.7 +/- 1.2 to 13.1 +/- 2.7 mm Hg, baseline versus final 7-h time point, mean +/- standard error), compared with either the vehicle-treated group (7.7 +/- 0.9 to 15.8 +/- 2.6 mm Hg) or the tissue plasminogen activator-treated group (7.6 +/- 0.6 to 13.7 +/- 2.1 mm Hg). The group that received the combination of 16(R)-HETE plus tissue plasminogen activator demonstrated no significant change in ICP for the duration of the protocol (8.6 +/- 0.6 to 11.1 +/- 1.2 mm Hg).

CONCLUSION

16(R)-HETE suppresses the development of increased ICP in a rabbit model of thromboembolic stroke and may serve as a novel therapeutic strategy in ischemic and inflammatory pathophysiological states.

Estimate and measure of the region of view and myopia resulting from vitreous gas

PURPOSE

After vitreous gas injection, patients notice better acuity in downward gaze than in horizontal gaze. The authors evaluated the refractive error and the size of the region within which vision improves.

METHODS

For the vitreous fluid-gas interface, the authors calculated the angle of total internal reflection and the expected myopic shift and then measured them in nine consecutive patients. The volume of gas, declination angle at which perception of small targets occurred, and preoperative and postoperative refractive error in downward gaze were measured.

RESULTS

Total internal reflection occurs at 41.5 degrees declination. Patients perceived a region of improved acuity below 41 degrees (+/-5 degrees) declination. The difference between the calculated and clinically measured gas-induced myopia was less than 25% for five of nine patients. The largest measured induced myopia was -23.9 diopters (60% gas volume). In eight eyes, patients read 5-point type or smaller.

CONCLUSIONS

Patients accurately perceive that their acuity improves in downward gaze; the boundary of this region corresponds with the angle of total internal reflection. Calculations predict that vitreous gas produces a myopic shift and aberration. These data support the notion that ocular positioning by patients with vitreous gas can be enhanced by instructing them to regard near targets in downward gaze.

Drusen associated with aging and age-related macular degeneration contain proteins common to extracellular deposits associated with atherosclerosis, elastosis, amyloidosis, and dense deposit disease

Age-related macular degeneration (AMD), a blinding disorder that compromises central vision, is characterized by the accumulation of extracellular deposits, termed drusen, between the retinal pigmented epithelium and the choroid. Recent studies in this laboratory revealed that vitronectin is a major component of drusen. Because vitronectin is also a constituent of abnormal deposits associated with a variety of diseases, drusen from human donor eyes were examined for compositional similarities with other extracellular disease deposits. Thirty-four antibodies to 29 different proteins or protein complexes were tested for immunoreactivity with hard and soft drusen phenotypes. These analyses provide a partial profile of the molecular composition of drusen. Serum amyloid P component, apolipoprotein E, immunoglobulin light chains, Factor X, and complement proteins (C5 and C5b-9 complex) were identified in all drusen phenotypes. Transcripts encoding some of these molecules were also found to be synthesized by the retina, retinal pigmented epithelium, and/or choroid. The compositional similarity between drusen and other disease deposits may be significant in view of the recently established correlation between AMD and atherosclerosis. This study suggests that similar pathways may be involved in the etiologies of AMD and other age-related diseases.

Location, substructure, and composition of basal laminar drusen compared with drusen associated with aging and age-related macular degeneration

PURPOSE

To determine whether basal laminar drusen differ in their location, ultrastructure, or composition from drusen associated with aging and age-related macular degeneration.

METHODS

A paraffin-embedded block from an eye of a patient with basal laminar drusen was obtained. Sections were examined immunohistochemically using a battery of antibodies and lectins directed against drusen-associated proteins and glycoconjugates, respectively. Thin sections were examined by electron microscopy and compared with eyes with age-related macular degeneration.

RESULTS

Drusen in the eye with basal laminar drusen are located between the basal lamina of the retinal pigment epithelium and the inner collagenous layer of Bruch membrane, just as they are in age-related macular degeneration. Two distinct ultrastructural phenotypes are observed in the eye with basal laminar drusen; their substructure is indistinguishable from drusen phenotypes in age-related macular degeneration. Both basal laminar drusen and drusen associated with age-related macular degeneration are bound by the lectins Ricinis communis agglutinin and Arachis hypogea agglutinin (after neuraminidase digestion) and by antivitronectin, anti-HLA-DR, anti-serum amyloid P, and anti-C5 antibodies, but not by antibodies directed against basement membrane-associated heparan sulfate proteoglycan, laminin, fibrinogen, or collagen type IV.

CONCLUSIONS

These data support the notion that cuticular or basal laminar drusen are similar to, and perhaps indistinguishable from, drusen associated with age-related macular degeneration and are not nodular or diffuse thickenings of Bruch membrane, as previously suggested. Thus, we suggest basal laminar drusen is a misnomer. This clinical phenotype should be identified as "early adult onset, grouped drusen" or by the eponym "Gass syndrome." Features of basal laminar drusen, such as uniform drusen size, clustered distribution, and angiographic features, do not appear to be related to differences in drusen location, composition, or substructure.

Effects of solute methoxylation on glass-forming ability and stability of vitrification solutions

The effects of replacing hydroxyl groups with methoxyl (OCH(3)) groups in the polyols ethylene glycol (EG), propylene glycol (PG), glycerol, and threitol were studied by differential scanning calorimetry (DSC) during cooling of aqueous solutions to -150 degrees C and subsequent rewarming. For 35% (w/w) PG, 40% EG, and 45% glycerol, a single substitution of a terminal hydroxyl group with a methoxyl group reduced the critical cooling rate necessary to avoid ice on cooling (vitrify) from approximately 500 to 50 degrees C/min. This reduction was approximately equivalent to increasing the parent polyol concentration by 5% (w/w). The critical warming rate calculated to avoid formation of ice on rewarming (devitrification) was also reduced by methoxyl substitution, typically by a factor of 10(4) for dilute solutions. Double methoxylation (replacement of both terminal hydroxyls) tended to result in hydrate formation, making these compounds less interesting. An exception was threitol, for which substituting both terminal hydroxyls by methoxyls reduced the critical rewarming rate of a 50% solution by a factor of 10(7) without any hydrate formation. These glass-forming and stability properties of methoxylated compounds, combined with their low viscosity, enhanced permeability, and high glass transition temperatures, make them interesting candidate cryoprotective agents for cryopreservation by vitrification or freezing. Copyright 1999 Academic Press.

Vitronectin is a constituent of ocular drusen and the vitronectin gene is expressed in human retinal pigmented epithelial cells

Age-related macular degeneration (AMD) leads to dysfunction and degeneration of retinal photoreceptor cells. This disease is characterized, in part, by the development of extracellular deposits called drusen. The presence of drusen is correlated with the development of AMD, although little is known about drusen composition or biogenesis. Drusen form within Bruch's membrane, a stratified extracellular matrix situated between the retinal pigmented epithelium and choriocapillaris. Because of this association, we sought to determine whether drusen contain known extracellular matrix constituents. Antibodies directed against a battery of extracellular matrix molecules were screened on drusen-containing sections from human donor eyes, including donors with clinically documented AMD. Antibodies directed against vitronectin, a plasma protein and extracellular matrix component, exhibit intense and consistent reactivity with drusen; antibodies to the conformationally distinct, heparin binding form of human vitronectin are similarly immunoreactive. No differences in vitronectin immunoreactivity between hard and soft drusen, or between macular and extramacular regions, have been observed. RT-PCR analyses revealed that vitronectin mRNA is expressed in the retinal pigmented epithelium (RPE)-choroidal complex and cultured RPE cells. These data document that vitronectin is a major constituent of human ocular drusen and that vitronectin mRNA is synthesized locally. Based on these data, we propose that vitronectin may participate in the pathogenesis of AMD.

Humanized anti-L-selectin monoclonal antibody DREG200 therapy in acute thromboembolic stroke

Strategies directed against activated neutrophils have reduced ischemia-induced brain injury. However, therapies targeted specially against the neutrophil adhesion protein L-selectin have not yet been examined in stroke. This study therefore examined the effects of a monoclonal antibody directed against L-selectin in a rabbit model of thromboembolic stroke with (n = 16) or without (n = 10) concomitant t-PA therapy. Rabbits received either the humanized monoclonal antibody DREG200 directed against the L-selectin receptor or humanized control monoclonal antibody HuDREG55 which does not bind to rabbit L-selectin in addition to t-PA therapy (n = 8, each group). HuDREG200 (2 mg kg-1 i.v.) was given as a bolus 3 h following clot embolization, followed immediately by a 2 h intravenous infusion of t-PA (6.3 mg kg-1. Without t-PA therapy rabbits received HuDREG200 (2 mgkg-1, i.v.; n = 5) or HuDREG55 (n = 5) 1 h following clot embolization. The group receiving HuDREG200 in addition to t-PA demonstrated a moderate improvement in brain infarct size (8.4 +/- 2.4 vs. 13.5 +/- 3.5, %hemisphere, mean +/- sem), ICP (final reading 10.0 +/- 1.6 vs. 12.4 +/- 3.0 torr) and restoration in regional cerebral blood flow (30.2 +/- 7.8 vs. 21.6 +/- 10.9 cc 100 g-1 min-1) when compared to t-PA therapy alone although statistical significance was not achieved. No efficacy was demonstrated in the group receiving HUDREG200 without concomitant t-PA therapy. The results suggest the addition of a humanized anti-L-selectin monoclonal antibody HuDREG200 in combination with t-PA may further improve outcome in acute thromboembolic stroke, although future studies are necessary to support these findings.

Defective learning in mutants of the Drosophila gene for a regulatory subunit of cAMP-dependent protein kinase

Disruptions of a Drosophila gene encoding a regulatory subunit of cAMP-dependent protein kinase homologous to mammalian RIbeta (dPKA-RI) were targeted to the first (noncoding) exon of dPKA-RI via site-selected P element mutagenesis. Flies homozygous for either of two mutant alleles showed specific defects in olfactory learning but not in subsequent memory decay. In contrast, olfactory acuity and shock reactivity, component behaviors required for normal odor avoidance learning, were normal in these mutants. Northern and Western blot analyses of mRNA and protein extracted from adult heads have revealed a complex lesion of the PKA-RI locus, including expression of a novel product and over- or underexpression of wild-type products in mutants. Western blot analysis revealed reductions in RI protein in mutants. PKA activity in the absence of exogenous cAMP also was significantly higher than normal in homogenates from mutant adult heads. These two mutant alleles failed to complement each other for each of these phenotypic defects, eliminating second-site mutations as a possible explanation. These results establish a role for an RI regulatory subunit of PKA in Pavlovian olfactory conditioning.

Nitric oxide reverses aspirin antagonism of t-PA thrombolysis in a rabbit model of thromboembolic stroke

Randomized trials of thrombolytic therapy in stroke have reported an improvement in neurologic outcome; however, the addition of aspirin has resulted in a significant increase in mortality and antagonism of clot lysis in clinical and animal studies, respectively. This finding is in contradistinction to the known synergy in mortality reduction for aspirin and thrombolytics in myocardial infarction. It is hypothesized that aspirin antagonism of clot lysis is related to inhibition of nitric oxide (NO) and may be reversed by providing a source of NO. Twenty rabbits were treated with aspirin (20 mg/kg, i.v.) prior to internal carotid clot embolization. One-half hour following embolization, rabbits were randomized to receive vehicle (n = 5), the NO precursor L-arginine (300 mg/kg, i.v. bolus at 0.5 and 2.5 h postembolus; n = 5), or a nitric oxide donor (nitroprusside, 1 mg/kg/h, i.a., or nitroglycerin, 10 microg/kg/min, i.v., n = 5 each agent). Tissue plasminogen activator (t-PA) (6.3 mg/kg) was administered from 1 to 3 h after embolization. Lysis of the tin-tagged clot was followed with serial X rays and gross examination. No rabbit in the control group experienced complete clot lysis. However, 2 of 5 rabbits in the L-arginine group and 6 of 10 rabbits in the nitric oxide donor (nitroprusside and nitroglycerin) groups noted complete clot lysis (P < 0.05, Fisher exact test). Thus, administration of an NO donor (nitroglycerin or nitroprusside) and, to a lesser extent L-arginine, reversed aspirin's antagonism of t-PA thrombolysis. This study may help explain the discrepant results seen with aspirin and thrombolytics.

Insoluble interphotoreceptor matrix in human vitreous after rhegmatogenous retinal detachment

PURPOSE

To determine whether insoluble interphotoreceptor matrix is present in the vitreous of human eyes after rhegmatogenous retinal detachment.

METHODS

Vitreous aspirates were collected from 12 eyes of 12 patients during retinal reattachment surgery or membrane peeling for rhegmatogenous retinal detachment-related macular epiretinal membranes between 1 day and 5 months after patients' initial rhegmatogenous retinal detachment symptoms. The aspirates were pelleted by centrifugation, embedded in acrylamide, sectioned, and incubated with fluorescein isothiocyanate-conjugated peanut agglutinin and an interphotoreceptor matrix-specific polyclonal antibody, designated 1-89B.

RESULTS

Before surgery, 11 of 12 eyes exhibited pigment in the anterior vitreous (Shafer's sign). Morphologic and histochemical characteristic profiles of insoluble interphotoreceptor matrix domains, bound by fluorescein isothiocyanate-conjugated peanut agglutinin or polyclonal antibody 1-89B, or both, were identified in vitreous aspirates from 11 of 12 patients.

CONCLUSIONS

The results of this study provide evidence that insoluble interphotoreceptor matrix constituents gain access to the vitreous after rhegmatogenous retinal detachment. Furthermore, insoluble interphotoreceptor matrix may remain in the vitreous for several months without being degraded.

Activation of complement by tissue plasminogen activator, but not acute cerebral ischemia, in a rabbit model of thromboembolic stroke

Although complement activation is associated with tissue injury during inflammatory and ischemic states, complement activation in states of acute cerebral ischemia before and after administration of tissue plasminogen activator (TPA) has not yet been examined and is the focus of this investigation. Twenty-four New Zealand White rabbits weighing 3 to 3.5 kg were used for this study. Of these, 20 were subjected to intracranial autologous clot embolization via the internal carotid artery. Three hours postembolization, rabbits received an intravenous infusion of TPA (6.3 mg/kg, 20% bolus with the remainder infused over a 2-hour interval; 12 animals) or vehicle (eight animals). All animals were observed for a total of 7 or 8 hours postembolization. These two groups were compared to a cohort undergoing sham operation with subsequent TPA infusion (four animals). Plasma samples to quantify complement component C5 hemolytic activity (C5H5O) were obtained at the following time points: 30 minutes before and after clot embolization; 1 hour before and 1 hour after the initiation of therapy with TPA or vehicle and at the completion of the protocol; 7 to 8 hours after clot embolization. The C5 activation was not detected as the result of acute cerebral ischemia. However, animals receiving TPA with or without concomitant clot embolization exhibited C5 activation as assessed by a reduction in C5 hemolytic function, both 1 hour after initiation of TPA infusion (78.7 +/- 10.3% and 77.5 +/- 9.9% of baseline value, respectively; mean +/- standard error of the mean [SEM]) and at the end of the protocol, 2 hours after the completion of the TPA infusion (72.5 +/- 8.8% and 53.3 +/- 8.1%, respectively; mean +/- SEM, p < 0.05, each group). This study supports the conclusion that TPA, but not acute cerebral ischemia, may activate the complement cascade in this rabbit model of thromboembolic stroke.

The Dichaete gene of Drosophila melanogaster encodes a SOX-domain protein required for embryonic segmentation

We have cloned and characterised a member of the High Mobility Group superfamily of genes from Drosophila, Sox70D, which is closely related to the mammalian testis determining gene SRY. Sox70D corresponds to the dominant wing mutation Dichaete. Homozygous deletions of the Sox70D gene and recessive lethal Dichaete alleles have a variable embryonic segmentation phenotype. Dichaete is expressed in early embryos in a dynamic pattern reminiscent of gap and pair-rule genes and is required for the appropriate expression of the primary pair-rule genes even skipped, hairy and runt. The molecular nature of Dichaete and its expression pattern during early embryogenesis suggest that the gene plays a key role in early development; the variability in both the segmentation phenotype and the effects on pair-rule gene expression suggests that this role is to support the transcriptional regulation of key developmental genes rather than directly regulate any one of them.

The Drosophila Eip78C gene is not vital but has a role in regulating chromosome puffs

We have generated a number of chromosomal aberrations that disrupt the early-late ecdysone-induced 78C puff gene (Eip78C, ecdysone-induced protein, FlyBase name for the E78 gene of Stone and Thummel 1993), which encodes the two members of the nuclear hormone receptor superfamily Eip78C-A and Eip78C-B. The aberrations include deletions of the ligand-binding/dimerization domain of both, inversions that split Eip78C-A but retain residual Eip78C-B expression, and a small deletion specific for Eip78C-B. We find that wild-type Eip78C functions are completely dispensable for normal development under laboratory conditions. However, we show that Eip78C-B is required for the maximal puffing activity of a subset of late puffs (63E and 82F) since these puffs are reduced in size in Eip78C-B mutant backgrounds. Paradoxically the same late puffs are reduced, as well as at least one other, when the Eip78C-B cDNA is overexpressed from a heat shock promoter. These data indicate either that Eip78C function is redundant or that it plays a subtle modulating role in the regulation of chromosome puffing.

The effect of oral antiplatelet agents on tissue plasminogen activator-mediated thrombolysis in a rabbit model of thromboembolic stroke

OBJECTIVE

The success of thrombolytic therapy in acute stroke relies on timely reperfusion. The current study examines the efficacy of antiplatelet agents as adjuvants for thrombolytic therapy.

METHODS

Using an established rabbit model of clot embolization and a randomized blinded design, rabbits (n = 8 in each group) were orally pretreated daily for 5 days with adjuvant aspirin (1 mg/kg of body weight or 20 mg/kg), ticlopidine (100 mg/kg), or vehicle (sodium carbonate). On the 6th day, tissue plasminogen activator (6.3 mg/kg administered intravenously over 2 h), was initiated 1 hour after embolization.

RESULTS

In all groups, cerebral blood flow (CBF) was reduced to < 10 ml/100 g/min immediately after clot embolization. After the initiation of tissue plasminogen activator (t-PA), there was significant restoration of CBF in the control (t-PA only) and ticlopidine groups (P < 0.05) only. Restoration of CBF generally correlated with brain infarct size (percent hemisphere, mean +/- standard error of the mean), which was 18.0 +/- 7.0 in the t-PA only group versus 11.0 +/- 3.3, 26.5 +/- 5.8, and 21.5 +/- 3.4 in the ticlopidine, low-dose aspirin, and high-dose aspirin groups, respectively (ticlopidine versus aspirin, P < 0.05). Clot lysis was identical in the control and ticlopidine groups, with 6 of 8 animals demonstrating complete clot lysis. Aspirin antagonized clot lysis in a dose-related manner, with low-and high-dose aspirin groups noting clot lysis in four of eight and two of eight animals, respectively.

CONCLUSIONS

Pretreatment with ticlopidine significantly reduced brain infarct size when compared with aspirin treatment (P < 0.05). Moreover, whereas ticlopidine treatment did not affect clot lysis or CBF relative to t-PA alone, aspirin therapy resulted in antagonism of clot lysis and was associated with a more modest restoration of blood flow. This study provides a background for a more comprehensive understanding of the balance of thrombogenicity and thrombolysis and may assist in the development of novel therapies to expedite cerebrovascular patency and reduce ischemic and reperfusion-mediated neuronal injury.

A Drosophila melanogaster chromosome 2L repeat is expressed in the male germ line

We describe the initial characterisation of a Drosophila melanogaster locus, Mst40 (Male-specific transcript), that was cloned on the basis of its male-specific transcription during the third larval instar. Corresponding low molecular weight poly(A)+ mRNAs are abundant in primary spermatocytes, but in no other larval or adult tissue. During early embryogenesis Mst40 expression is complex; initially transcription is detected during early cleavage stages. This early expression appears as two discrete dots of hybridisation associated with each nucleus. Subsequently, the transcripts are abundant in the cytoplasm of the newly formed pole cells. In the genome Mst40 sequences are located in region 40, at the base of chromosome 2L, close to, or within, the beta-heterochromatin. The Mst40 sequences are organised as a tandemly arrayed 1.4 kb repeat unit. The repeat is conserved in all D. melanogaster strains examined but absent from other Drosophila species studied. The locus does not correspond to any known complementation groups in the region and has yet to be assigned a function.

Point mutation in a leucine-rich repeat of platelet glycoprotein Ib alpha resulting in the Bernard-Soulier syndrome

Leucine-rich repeats are a conserved structural motif, of yet undefined significance, found in a group of proteins from different species. Among these are the four components of the human platelet glycoprotein Ib-IX-V complex, a membrane receptor that performs an essential role in the thrombogenic function of platelets by interacting with the adhesive protein, von Willebrand factor. We have found that a single amino acid substitution (Ala156-->Val) within one of the six leucine-rich repeats in the alpha-subunit of glycoprotein Ib results in a variant form of the congenital bleeding disorder, Bernard-Soulier syndrome, characterized by giant dysfunctional platelets. Genetic studies of the propositus and his family members were complemented by immunological and functional analysis of expressed recombinant GP Ib alpha fragments to demonstrate that the observed mutation is the cause of defective von Willebrand factor binding. These studies define the molecular basis of the Bernard-Soulier syndrome within this family and demonstrate that structural integrity of a leucine-rich repeat is necessary for normal function of the glycoprotein Ib-IX-V receptor complex and, possibly, for normal platelet morphology.

Expression of the phenotypic abnormality of platelet-type von Willebrand disease in a recombinant glycoprotein Ib alpha fragment

The platelet GP Ib-IX receptor supports platelet adhesion and activation by binding to vWf in the exposed subendothelial matrix. An abnormal GP Ib-IX complex exists in platelet-type or pseudo-von Willebrand disease and has a characteristic increased affinity for soluble vWf resulting in impaired hemostatic function due to the removal of larger vWf multimers from the circulation. Genetic studies within an afflicted family have demonstrated that the disease is linked to a Gly233-->Val amino acid substitution within the alpha-subunit of the oligomeric GP Ib-IX complex (Miller, J.L., D. Cunningham, V.A. Lyle, and C. L. Finch. 1991. Proc. Natl. Acad. Sci. USA. 88:4761-4765). To evaluate the functional consequences of this mutation, we constructed a recombinant analogue of the alpha-subunit of GP Ib containing Val233. Experiments comparing molecules with either Gly233 or Val233 revealed that the Val substitution generates a molecule with increased affinity for vWf. The recombinant fragment reproduces the functional abnormality of the GP Ib-IX complex in platelet-type von Willebrand disease, thus establishing the molecular basis of the bleeding disorder within this family. Moreover, it becomes apparent that structural elements responsible for the regulation of hemostasis through modulation of vWf affinity for platelets reside within the alpha-subunit of the GP Ib-IX complex.

Drosophila melanogaster male germ line-specific transcripts with autosomal and Y-linked genes

We have identified of set of related transcripts expressed in the germ line of male Drosophila melanogaster. Surprisingly, while one of the corresponding genes is autosomal the remainder are located on the Y chromosome. The autosomal locus, at 77F on chromosome arm 3L, corresponds to the previously described transcription unit 18c, located in the first intron of the gene for an RI subunit of cAMP-dependent protein kinase. The Y chromosome copies have been mapped to region h18-h19 on the cytogenetic map of the Y outside of any of the regions required for male fertility. In contrast to D. melanogaster, where Y-linked copies were found in nine different wild-type strains, no Y-linked copies were found in sibling species. Several apparently Y-derived cDNA clones and one Y-linked genomic clone have been sequenced. The Y-derived genomic DNA shares the same intron/exon structure as the autosomal copy as well as related flanking sequences suggesting that it transposed to the Y from the autosomal locus. However, this particular Y-linked copy cannot encode a functional polypeptide due to a stop codon at amino acid position 72. Divergence among five different cDNA clones ranges from 1.5 to 6% and includes a large number of third position substitutions. We have not yet obtained a full-length cDNA from a Y-linked gene and therefore cannot conclude that the D. melanogaster Y chromosome contains functional protein-coding genes. The autosomal gene encodes a predicted polypeptide with 45% similarity to histones of the H5 class and more limited similarity to cysteine-rich protamines. This protein may be a distant relative of the histone H1 family perhaps involved in sperm chromatin condensation.

Expression of human platelet glycoprotein Ib alpha in transgenic mice

Platelets are cytoplasmic fragments of megakaryocytes and, therefore, their membrane proteins cannot be manipulated by expression methods in culture. To overcome this limitation, we have expressed human glycoprotein (GP) Ib alpha in transgenic mouse megakaryocytes and found that it was present on the surface of platelets associated with the mouse GP Ib beta subunit. This finding demonstrates that assembly of the heterooligomeric GP Ib complex occurs through mechanisms conserved across species. In contrast, the receptor function of GP Ib exhibited restricted species specificity, since only the chimeric complex containing human GP Ib alpha bound human von Willebrand factor and supported platelet aggregation mediated by ristocetin. These studies demonstrate the transgenic engineering of a platelet adhesion receptor under control of the human GP Ib alpha promoter and illustrate a new approach to manipulate platelet receptors and study structure-function relationships in hemostasis and thrombosis.

The effects of feed restriction on reproductive function in Swiss CD-1 mice

Many test compounds used in toxicity studies produce a "systemic" toxicity manifested as reduced body weight gain. While it is known that reduced weight gain during juvenile growth reduces or delays reproductive competence, the effects of adult-onset feed restriction (FR) and inhibited weight gain on the reproductive system of mice are poorly known. To gain some information on the effects of graded body weight reduction, or reduced body weight gain, on commonly used reproductive endpoints, the studies reported below were conducted at two laboratories, using adult mice that were maintained at 90, 80, and 70% of concurrent control body weight (CBW) for up to 21 weeks. Estrous cyclicity and fertility in the females were significantly affected. While male fertility was variably affected, there was a significant decrease in the number of epididymal sperm and in the number of testicular spermatids in the 70% CBW groups. Testis weight was conserved in both studies; relative testis weight increased in all FR groups. These data can improve the interpretation of future studies by helping to separate chemically induced changes from those produced by reduced body weight gain.

Chondroitin sulfate-induced generation of epiretinal membranes

Previous investigations have examined the role of serum and retinal pigment epithelium-derived factors in the elaboration of epiretinal membranes. Alternatively, the contribution of the insoluble interphotoreceptor matrix, known to contain chondroitin-sulfate-containing proteoglycans, in the generation of epiretinal membranes, has not been evaluated, to our knowledge. To investigate the potential role of chondroitin sulfates in eliciting epiretinal membranes, chondroitin sulfate glycosaminoglycans were injected into the vitreous cavity of rabbits. Examination demonstrated epiretinal membranes in 86% of eyes receiving chondroitin-6-sulfate. Temporal development of chondroitin sulfate glycosaminoglycan-induced epiretinal membranes was categorized into three distinct stages: a preretinal cell stage 1 to 3 weeks following injection, a glial "tuft" stage at 3 to 6 weeks, and a "mature" complex membrane stage at 6 weeks or later. Our results suggest that intravitreal administration of chondroitin sulfate glycosaminoglycan, components of insoluble interphotoreceptor matrix proteoglycans, may elicit the generation of epiretinal membranes, even in the absence of retinal disruption.

Genetic and structural characterization of an amino acid dimorphism in glycoprotein Ib alpha involved in platelet transfusion refractoriness

The platelet-specific alloantigen, Siba, located within the alpha-subunit of the glycoprotein (GP) Ib-IX membrane receptor, has been found to be involved in the pathogenesis of platelet transfusion refractoriness. We have identified the existence of a naturally occurring threonine/methionine dimorphism at position 145 of the GPIb alpha sequence, and determined that the Siba antigen corresponds to the molecule containing methionine145. The diallelic codons can be detected by restriction enzyme analysis of amplified genomic DNA fragments from the GPIb alpha gene. Evaluation of 61 healthy blood donors showed that the allele frequencies are 89% and 11% for the threonine145 and methionine145 codons, respectively. A positive correlation exists between platelet reactivity with the anti-Siba antibody and the presence of a methionine145-encoding allele. Moreover, recombinant expression of two soluble GPIb alpha fragments differing only at residue 145, provided definitive evidence that the human anti-Siba antibody reacts only with the molecule containing methionine145. These results explain the structural basis of the Siba human alloantigen system and define screening methodologies useful in transfusion medicine to match donor and recipient platelets accordingly.

Methods for assessing rat sperm motility

Computer-assisted sperm analysis (CASA) systems are becoming more widely used. With this spread of technology come more data from toxicology studies, designed to determine if treatment with putative toxicants affects sperm motion parameters. While these CASA methods provide us with more ways to evaluate toxicity and thus perhaps increase our chances of successfully protecting human health, there is also a greater likelihood that different laboratories will use different methods of collecting data on sperm motility. Different systems used with different methods in different laboratories will inevitably generate data that are difficult to compare. In a prospective attempt to address this issue of comparability and limit the problems, a group of individuals using CASA systems to analyze rat sperm motility convened to discuss methodologic issues, share data, and try to reach a consensus about methods for performing these studies. This article shares those meetings and data in the hope that common methods will enhance interlaboratory comparisons.

Hemorrhagic detachment of the internal limiting membrane after penetrating ocular injury

During surgery to remove an intraocular gunshot pellet, a loculated "preretinal" hemorrhage was identified. This provided an opportunity to evaluate the structural identity of the inner wall, presumably representing detached posterior vitreous. The preretinal membrane was excised and evaluated using lectin histochemical analysis. All lectins tested bound to the excised tissue, supporting the conclusion that the membrane was a hemorrhagic internal limiting membrane detachment resulting from direct penetrating ocular injury. During intraoperative biomicroscopic examination, this detachment was indistinguishable from a subhyaloid hemorrhage. Because there are no natural history studies on internal limiting membrane loss and damage to retinal visual function, caution is urged in the surgical management of these lesions.

Distribution of glycoconjugates in the human retinal internal limiting membrane

The internal limiting membrane (ILM), or basal lamina, of the neural retina is located between the end feet of retinal Müller cells and the vitreous cortex. Recent studies of ILM substructure and histochemistry suggest that the ILM lamina rara externa, a region of the ILM likely to mediate vitreoretinal adhesion, is rich in noncollagen glycoconjugates. To characterize the spatial distribution and temporal expression of ILM glycoconjugates further, fetal and adult human retinas were examined using lectin histochemistry. Eyes from early fetal (13-15 weeks of gestation), midfetal (17-20 weeks of gestation), late fetal (23-26 weeks of gestation), full-term (38-41 weeks of gestation), early adult (17-20 yr of age), and late adult (57-84 yr of age) stages were examined. Although a number of significant observations pertaining to the distribution and temporal expression of ILM-associated glycoconjugates are described, two may have a significant relationship to vitreoretinal adhesion. In contrast to laminin and fibronectin, which are detectable throughout the retinal ILM at both young and older adulthood, erythrina cristagalii (ECA), a lectin with high binding affinity for galactose beta (1,3) N-acetyl-glucosamine, binds strongly to the ILM of young eyes but does not bind to the ILM of eyes from older donors. In addition, dolichos bifloris (DBA), a lectin with high binding affinity for N-acetylgalactosamine, does not bind to the ILM at early fetal stages, but binds at the midfetal stage, a time which corresponds with the onset of tertiary vitreous elaboration. More significantly, the DBA-binding glycoconjugate is neural retina ILM specific; it is not present in the basal lamina of the ciliary epithelium. Based on the known oligosaccharide composition of nonocular forms of human laminin, fibronectin, and collagen type I, and on the distribution of these molecules in the basal laminas of both the retina and ciliary epithelium, the authors conclude that the molecule bound by DBA has not been identified previously as a component of the ILM. Further characterization of ILM-associated molecules will be important to understand vitreoretinal adhesion and clinical disorders where adhesion is anomalous.

Autosomal dominant neovascular inflammatory vitreoretinopathy

Twenty-eight of 61 members of a six-generation family are affected by an autosomal dominant eye disease which has not been described previously. Affected patients are asymptomatic in early adulthood, but have vitreous cells and the selective loss of the b-wave on the electroretinogram. Later, peripheral retinal scarring and pigmentation, peripheral arteriolar closure, and neovascularization of the peripheral retina at the ora serrata or occasionally neovascularization of the optic disc develop. Cystoid macular edema, vitreous hemorrhage, tractional retinal detachment, and neovascular glaucoma can cause profound visual loss. Vitrectomy reduces traction on the retina and allows for retinal reattachment. The role of argon laser photocoagulation or cryopexy in reducing the neovascular complications remains uncertain.

Direct and feeder vessel photocoagulation of retinal angiomas with dye yellow laser

Dye yellow laser photocoagulation (577 nm) was used to treat 14 retinal angiomas in nine patients. Eight patients had von Hippel-Lindau disease. Treatment was applied either directly to the tumor surface or to the feeding artery. Seven of eight angiomas that were treated directly and five of six that had feeder vessel treatment only were ablated successfully using dye yellow laser alone (mean follow-up, 11.1 months). An average of 2.2 treatments for feeder vessel and 1.1 treatments for direct ablation was required. Neither treatment caused decreased vision or severe complications. Dye yellow laser photocoagulation allows for effective treatment of retinal angiomas even when applied to the feeder vessel alone.

Nonsense mutation in the glycoprotein Ib alpha coding sequence associated with Bernard-Soulier syndrome

Three distinct gene products, the alpha and beta chains of glycoprotein (GP) Ib and GP IX, constitute the platelet membrane GP Ib-IX complex, a receptor for von Willebrand factor and thrombin involved in platelet adhesion and aggregation. Defective function of the GP Ib-IX complex is the hallmark of a rare congenital bleeding disorder of still undefined pathogenesis, the Bernard-Soulier syndrome. We have analyzed the molecular basis of this disease in one patient in whom immunoblotting of solubilized platelets demonstrated absence of normal GP Ib alpha but presence of a smaller immunoreactive species. The truncated polypeptide was also present, along with normal protein, in platelets from the patient's mother and two of his four children. Genetic characterization identified a nucleotide transition changing the Trp-343 codon (TGG) to a nonsense codon (TGA). Such a mutation explains the origin of the smaller GP Ib alpha, which by lacking half of the sequence on the carboxyl-terminal side, including the trans-membrane domain, cannot be properly inserted in the platelet membrane. Both normal and mutant codons were found in the patient, suggesting that he is a compound heterozygote with a still unidentified defect in the other GP Ib alpha allele. Nonsense mutation and truncated GP Ib alpha polypeptide were found to cosegregate in four individuals through three generations and were associated with either Bernard-Soulier syndrome or carrier state phenotype. The molecular abnormality demonstrated in this family provides evidence that defective synthesis of GP Ib alpha alters the membrane expression of the GP Ib-IX complex and may be responsible for Bernard-Soulier syndrome.

Vitrectomy for complicated retinal detachments secondary to branch retinal vein occlusions

Combined rhegmatogenous and traction retinal detachments associated with branch vein occlusions occurred in five eyes of five patients between Jan. 1, 1986 and Dec. 31, 1987. Four patients underwent surgery with pars plana vitrectomy and intravitreal gas, with or without scleral buckling. One patient refused treatment. All operated on eyes had attached retinas at a mean follow-up of seven months. Because posterior traction plays an important role in these unusual detachments, consideration should be given to pars plana vitrectomy and air-fluid exchange rather than scleral buckling alone.

Reproductive toxicity of three phthalic acid esters in a continuous breeding protocol

A continuous breeding protocol was utilized to examine the reproductive toxicity of three phthalate esters. CD-1 mice were given diets with either di-n-propyl phthalate (DPrP: 0.0, 1.25, 2.5, or 5.0%), di-n-pentyl phthalate (DPP: 0.0, 0.5, 1.25, or 2.5%), or di-n-octyl phthalate (DOP: 0.0, 1.25, 2.5, or 5.0%). Both male and female mice (20 pairs per treatment group, 40 pairs of control animals) were dosed for 7 days prior to and during a 98-day cohabitation period. Reproductive function was evaluated during the cohabitation period by measuring number of litters per pair, live pups per litter, and pup weight. There was no apparent effect on reproductive function in the animals exposed to DOP at dose levels sufficient to cause a significant increase in liver weight. Both DPP and DPrP were toxic to the reproductive system as evidenced by a complete inhibition of fertility at 1.25 and 2.5% DPP or 5.0% DPrP, and reduced fertility (litters/pair and live pups/litter, 0.5% DPP; live pups/litter, 2.5% DPrP). Toxicity of DPP had a strong male component and female component, whereas DPrP was more toxic to the female than the male reproductive system. DPP and DPrP treatment was associated with decreased body weight, increased liver weight, decreased testis and epididymis weights, decreased epididymal sperm concentration, and elevated seminiferous tubule atrophy. A comparison of seven phthalate esters tested using this continuous breeding protocol indicates the relative order of reproductive toxicity as diethylhexyl, dihexyl, dipentyl, dibutyl, dipropyl; diethyl and dioctyl are nontoxic.

A method for improved biometry of the anterior chamber with a Scheimpflug technique

A new method is described for obtaining cross-sectional images of the anterior chamber. Photographs are obtained with a Scheimpflug slit-lamp camera. After cornea, iris, and lens surfaces are digitized, mathematical corrections are made for the camera distortion and for the refractive effects of the cornea. The reproducibility and accuracy of the method were tested and found to be adequate for clinical study of human eyes in physiologic or diseased states.

Predictors of scleral rupture and the role of vitrectomy in severe blunt ocular trauma

We reviewed retrospectively 40 eyes that had received blunt trauma and had been explored for scleral rupture. Twenty-nine eyes had scleral rupture. Of these 29, ten had ruptures seen preoperatively. Nineteen had occult ruptures. The preoperative findings predictive of scleral rupture were a visual acuity of light perception or no light perception, an intraocular pressure of less than 10 mm Hg, hyphema, and chemosis. Of the 29 ruptures, 27 involved the superior hemisphere and 25 involved the anterior hemisphere of the globe. Ten of 29 eyes (34%) with scleral rupture and eight of 11 eyes (73%) without rupture achieved a final visual acuity of 5/200 or better over an average follow-up period of 6.7 months. Factors prognostic of ambulatory vision for eyes with ruptured and intact globes included an initial visual acuity of 5/200 or better, absence of scleral rupture, and a rupture length of less than 11 mm in eyes with ruptures. The vitrectomized eyes also had a better result, suggesting that early pars plana vitrectomy is of benefit in selected rupture cases.

Inhibition of platelet function with synthetic peptides designed to be high-affinity antagonists of fibrinogen binding to platelets

We have constructed synthetic peptides modeled on the sequences of (i) Arg-Gly-Asp, present in fibrinogen, fibronectin, and von Willebrand factor, and of (ii) the fibrinogen gamma chain (gamma 400-411) His-His-Leu-Gly-Gly-Ala-Lys-Gln-Ala-Gly-Asp-Val. The concentration of each peptide that inhibits 50% of 125I-labeled fibrinogen binding to thrombin-stimulated platelets (IC50) was then determined. The IC50 for (gamma 400-411) was 48-180 microM at a fibrinogen concentration of 60 micrograms/ml. A substitution of arginine for alanine at position 9 decreased the IC50 to 14.5 microM. Arginine substitutions for all other residues on the amino-terminal side of the peptide Arg9-Gly-Asp-Val resulted in an IC50 of 0.4-0.8 microM, and the IC50 of the peptide Arg13-Gly-Asp-Val was 0.2-0.3 microM. This contrasts with an IC50 of 200 microM for Arg5-Gly-Asp-Val-Arg4 and an IC50 greater than 1 mM for the peptide Arg12. The inhibitory effect resulted primarily in a decreased affinity of fibrinogen binding to platelets, although the number of available binding sites had also decreased. Binding was completely inhibited. At concentrations between 10 and 18 microM, Arg9-Gly-Asp-Val blocked all ADP-induced aggregation in citrated platelet-rich plasma. The peptide Tyr-His-His-Lys-Arg-Lys-Arg-Lys-Gln-Arg-Gly-Asp-Val was labeled with 125I to quantitate its binding to thrombin-stimulated platelets; at saturation, 59,990 molecules were bound per cell (Kd = 3.8 X 10(-7) M). These modified synthetic peptides bind to platelets with the same affinity as does intact fibrinogen and inhibit platelet function. The increased affinity of these modified peptides is greater than 20-fold that of peptides comprised of only native sequences and is a prerequisite for the potential antithrombotic use of these agents.

Risk factors in age-related maculopathy complicated by choroidal neovascularization

We evaluated previously reported and hypothesized risk factors for the development of age-related maculopathy (ARM) in a case-control study. We compared 26 patients with documented disciform scarring or choroidal neovascularization with 23 age- and sex-matched controls. Systolic and diastolic blood pressure, smoking history, glucose, lipoprotein profiles, and serum levels of vitamins A, C, and E did not differ significantly between the two groups. Statistically significant associations (P less than 0.05) identified by univariate analysis include degree of dermal elastotic degeneration in sun-exposed and sun-protected skin, white blood count, increasing age and small posterior lenticular opacities. Using an interactive multivariate model, only extent of elastosis in sun protected dermis, age and white blood count were predictive (Mult R = 0.652, P less than .001). Our data support the concept of a multifactorial etiology of ARM but suggest that generalized increased susceptibility of elastic fibers to photic or other degenerative stimuli is a new and important risk factor for choroidal neovascularization.

von Willebrand factor. A reduced and alkylated 52/48-kDa fragment beginning at amino acid residue 449 contains the domain interacting with platelet glycoprotein Ib

We have purified a reduced and alkylated tryptic fragment of von Willebrand factor (vWF) which migrated in sodium dodecyl sulfate-polyacrylamide gel electrophoresis as a 52/48-kDa doublet, but behaved as a single 46-kDa species after partial deglycosylation. After extensive treatment with denaturants, the 52/48-kDa polypeptide retained its ability to inhibit ristocetin-induced platelet aggregation in the presence of native vWF, as well as aggregation induced by desialylated vWF alone. Therefore, the 52/48-kDa polypeptide interacts with the platelet glycoprotein Ib receptor even in the absence of ristocetin. Both the 52/48- and the 46-kDa species inhibited ristocetin-induced binding of the intact molecule to platelets, but did not affect thrombin-induced binding. Determination of the NH2-terminal sequence of both members of the doublet gave identical results: VTLNPSDPEHCQ. This provided additional evidence that differences between the doublet constituents were only of carbohydrate composition and established the position of this peptide within the vWF polypeptide chain of approximately 2050 amino acid residues as beginning with the residue tentatively designated 449. These studies suggest that native conformation is not necessary for binding of vWF to platelets at the glycoprotein Ib receptor and that a linear amino acid sequence following residue 449 defines a domain responsible for this interaction.

Cell sorting using a universally applicable affinity chromatography matrix: solid-phase anti-fluorescein isothiocyanate antibody

Procedures are described for fractionating cells utilizing a universally applicable cellular affinity chromatography matrix. The affinity matrix consists of immunoabsorption purified goat anti-fluorescein isothiocyanate antibody coupled to large derivatized polyacrylamide beads. This matrix may, in principle, be used to isolate any cell subpopulation provided it has a fluorescein-labeled ligand on its surface. In this report the matrix was used to isolate viable purified fractions of mouse surface Ig-positive cells, Lyt1 cells, and mouse lymphocytes that bind the lectin soybean agglutinin. A preliminary experiment using the anti-FITC beads suggested that this technique can provide a fraction of cells enriched in antigen binding cells. Cell populations isolated by this technique retain their ability to respond to in vitro mitogen stimulation, as well as their ability to be maintained in cell culture following fractionation. Additional experiments using a column consisting of goat anti-rabbit Ig antibody coupled to the same support material are also reported.