ISCEV standard for clinical pattern electroretinography (2024 update)

The pattern electroretinogram (PERG) is a localized retinal response evoked by a contrast-reversing pattern, usually a black and white checkerboard, which provides information about macular and retinal ganglion cell function. This document, from the International Society for Clinical Electrophysiology of Vision (ISCEV; www.iscev.org ) presents an updated and revised Standard for clinical PERG testing. This replaces the 2013 and all earlier versions. Minimum protocols for basic PERG stimuli, recording methods and reporting are specified, to promote consistency of methods for diagnosis and monitoring purposes, while responding to evolving clinical practices and technology. The main changes in the updated ISCEV Standard for clinical PERG include expanded guidance about large stimulus fields, stimulus parameters for simultaneous PERG and pattern visual evoked potential recording, baseline drift correction, and use of consistent ambient room lighting. These changes aim to provide a clinically relevant document about current practice which will facilitate good quality recordings and inter-laboratory comparisons.

ISCEV and IPS guideline for the full-field stimulus test (FST)

The full-field stimulus test (FST) is a psychophysical technique designed for the measurement of visual function in low vision. The method involves the use of a ganzfeld stimulator, as used in routine full-field electroretinography, to deliver full-field flashes of light. This guideline was developed jointly by the International Society for Clinical Electrophysiology of Vision (ISCEV) and Imaging and Perimetry Society (IPS) in order to provide technical information, promote consistency of testing and reporting, and encourage convergence of methods for FST. It is intended to aid practitioners and guide the formulation of FST protocols, with a view to future standardisation.

7 Scoping review of homonymous hemianopia in childhood

Cerebral visual impairment (CVI) encompasses a heterogeneous group of disorders and a spectrum of types of visual impairments. Research is needed to characterise the different forms of CVI and identify the specific needs of these groups to inform individualised patient care. Homonymous hemianopia (HH) is a definable visual field defect that affect some children with CVI. As part of a new research programme, we conducted a scoping review of the literature on HH in children and young people to map current knowledge and identify evidence gaps.We used the PRISMA extension for Scoping Reviews methodology. Multiple online databases were searched using terms associated with 'homonymous hemianopia' and 'children'. This yielded 1588 papers which were screened by two reviewers. Of these 1001 were excluded at abstract screen and a further 415 excluded after full text review, with full text unavailable for 15. Data were extracted and charted from 157 studies and additional grey literature.Interim analysis shows reported studies are predominantly from high income countries with a paucity of higher-level evidence, and a preponderance of case reports. Most papers reported causative pathology and diagnosis of HH. There was minimal attention to or evidence relating to intervention. Child-specific grey literature on HH was limited.This review collates the current evidence-base for HH in children. It demonstrates the important evidence-gap relating to intervention in these cases that would help inform more individualised care. Similar scoping reviews may be prove useful in assessing the evidence relating to other definable groups within the CVI umbrella.

Visual outcomes and predictors in optic pathway glioma: a single centre study

BACKGROUND/AIMS

Optic pathway gliomas (OPGs) may cause progressive visual loss despite chemotherapy. Newer, less toxic treatments might be given earlier, depending on visual prognosis. We aimed to investigate the prognostic value of visual evoked potentials (VEP) and optical coherence tomography (OCT).

METHODS

A retrospective study of OPG patients (treated 2003-2017) was conducted. Primary outcome was PEDIG category visual acuity in better and worse eyes (good < = 0.2, moderate 0.3-0.6 and poor > = 0.7 logMAR). Binary logistic regression analysis was used to identify predictors of these outcomes.

RESULTS

60 patients (32 Neurofibromatosis type 1 [NF1] and 28 sporadic) had median presentation age 49 months (range 17-183) (NF1) and 27 months (range 4-92) (sporadic). Median follow up was 82 months (range 12-189 months). At follow up 24/32 (75%) of NF1 children and 14/28 (50%) of sporadic children had good better eye visual acuity and 11/32 (34%) of NF1 children and 15/28 (54%) of sporadics had poor worse eye acuity. Mean peripapillary retinal nerve fibre layer (RNFL) thickness predicted good better eye final acuity (OR 0.799, 95%CI 0.646-0.987, p = 0.038). Presenting with visual symptoms (OR 0.22 95% CI 0.001-0.508, p = 0.017) and poorer VEP scores (OR 2.35 95% CI 1.1-5.03, p = 0.027) predicted poor worse eye final acuity. 16 children had homonymous hemianopias at follow up, predicted by poor presenting binocular VEP score (OR 1.449 95%CI 1.052-1.995, p = 0.02).

CONCLUSIONS

We found that both RNFL thickness on OCT and VEP were useful in predicting future visual acuity and vision and potentially in planning treatment. We had a high prevalence of homonymous hemianopia.

What is in? What is out? Updating the British Society for Cutaneous Allergy facial series

BACKGROUND

Allergic contact dermatitis (ACD) to cosmetics is widely reported. To ensure we are accurately diagnosing ACD, patch test series should be continually reviewed to identify relevant and emerging allergens and highlight those that are outdated. The current British Society for Cutaneous Allergy (BSCA) facial series recommends 26 allergens and was last modified in 2012.

OBJECTIVES

To review and update the BSCA facial series.

METHODS

We retrospectively reviewed the results from 12 UK and Ireland patch test centres' facial series from January 2016 to December 2017. We recorded the number of allergens tested in each centre and the detection rate for each allergen. Using a 0·3% positive rate as the inclusion threshold, we established which allergens in the BSCA facial series had positive patch test rates < 0·3% and > 0·3%. Allergens not in the BSCA facial series that had a positive patch test rate > 0·3% were identified.

RESULTS

Overall, 4224 patients were patch tested to the facial series. The number of allergens included in individual centres' facial series ranged from 24 to 66, with a total of 103 allergens tested across all centres. Twelve of the 26 allergens in the BSCA facial series had a positive patch test rate < 0·3% and 14 had a rate > 0·3%. Twenty-five allergens not recommended in the BSCA facial series had a positive patch test rate > 0·3%.

CONCLUSIONS

This audit has highlighted the significant variation in practice that exists among patch test centres, despite a recommended facial series. The BSCA facial series has been updated and now contains 24 allergens. Fifteen allergens remain, 11 allergens have been dropped and nine new allergens have been added.

G1T48, an oral selective estrogen receptor degrader, and the CDK4/6 inhibitor lerociclib inhibit tumor growth in animal models of endocrine-resistant breast cancer

Purpose

The combination of targeting the CDK4/6 and estrogen receptor (ER) signaling pathways with palbociclib and fulvestrant is a proven therapeutic strategy for the treatment of ER-positive breast cancer. However, the poor physicochemical properties of fulvestrant require monthly intramuscular injections to patients, which limit the pharmacokinetic and pharmacodynamic activity of the compound. Therefore, an orally available compound that more rapidly reaches steady state may lead to a better clinical response in patients. Here, we report the identification of G1T48, a novel orally bioavailable, non-steroidal small molecule antagonist of ER.

Methods

The pharmacological effects and the antineoplastic mechanism of action of G1T48 on tumors was evaluated using human breast cancer cells (in vitro) and xenograft efficacy models (in vivo).

Results

G1T48 is a potent and efficacious inhibitor of estrogen-mediated transcription and proliferation in ER-positive breast cancer cells, similar to the pure antiestrogen fulvestrant. In addition, G1T48 can effectively suppress ER activity in multiple models of endocrine therapy resistance including those harboring ER mutations and growth factor activation. In vivo, G1T48 has robust antitumor activity in a model of estrogen-dependent breast cancer (MCF7) and significantly inhibited the growth of tamoxifen-resistant (TamR), long-term estrogen-deprived (LTED) and patient-derived xenograft tumors with an increased response being observed with the combination of G1T48 and the CDK4/6 inhibitor lerociclib.

Conclusions

These data show that G1T48 has the potential to be an efficacious oral antineoplastic agent in ER-positive breast cancer.

Electronic supplementary material

The online version of this article (10.1007/s10549-020-05575-9) contains supplementary material, which is available to authorized users.

Implementing a fracture liaison service open model of care utilizing a cloud-based tool

PURPOSE

Although half of women and one-quarter of men aged 50 and older will sustain an acute low-trauma fracture, less than a quarter receive appropriate secondary fracture prevention. The goal of this quality improvement demonstration project was to implement a Fracture Liaison Service (FLS) focused on secondary prevention of an osteoporotic fracture in three open health care systems aided by a cloud-based tool.

METHODS

The pre-post study design examined the proportion of men and women over age 50 who received appropriate assessment (bone mineral density, vitamin D levels) and treatment (calcium/vitamin D, pharmacologic therapy) in the six months following a recently diagnosed fracture. The pre-study (Pre FLS) included a retrospective chart review for baseline data (N = 344 patients) within each health care system. In the post-evaluation (Post FLS, N = 148 patients), the FLS coordinator from each health care system examined these parameters following enrollment and for 6 months following the recently diagnosed fracture. Data were managed in the cloud-based FLS application tool.

RESULTS

Ninety-three participants completed the program. The FLS program increased the percentage of patients receiving bone mineral density testing from 21% at baseline to 93% (p < 0.001) Post FLS implementation. Assessments of vitamin D levels increased from 25 to 84% (p < 0.001). Patients prescribed calcium/vitamin D increased from 36% at baseline to 93% (p < 0.001) and those prescribed pharmacologic treatment for osteoporosis increased on average from 20 to 54% (p < 0.001) Post FLS.

CONCLUSIONS

We conclude that the FLS model of care in an open health care system, assisted by a cloud-based tool, significantly improved assessment and/or treatment of patients with a recently diagnosed osteoporotic fracture. Future studies are necessary to determine if this model of care is scalable and if such programs result in prevention of fractures. Mini-Abstract: The goal was to implement a Fracture Liaison Service (FLS) focused on secondary prevention of an osteoporotic fracture in open health care systems aided by a cloud-based tool. This model significantly improved assessment and/or treatment of patients with a recently diagnosed fracture.

Development of a cloud-based application for the Fracture Liaison Service model of care

The aims of this study are to develop a cloud-based application of the Fracture Liaison Service for practitioners to coordinate the care of osteoporotic patients after suffering primary fractures and provide a performance feedback portal for practitioners to determine quality of care. The application provides continuity of care, improved patient outcomes, and reduced medical costs.

INTRODUCTION

The purpose of this study is to describe the content development and functionality of a cloud-based application to broadly deploy the Fracture Liaison Service (FLS) to coordinate post-fracture care for osteoporotic patients.

METHODS

The Bone Health Collaborative developed the FLS application in 2013 to support practitioners' access to information and management of patients and provide a feedback portal for practitioners to track their performance in providing quality care. A five-step protocol (identify, inform, initiate, investigate, and iterate) organized osteoporotic post-fracture care-related tasks and timelines for the application. A range of descriptive data about the patient, their medical condition, therapies and care, and current providers can be collected. Seven quality of care measures from the National Quality Forum, The Joint Commission, and the Centers for Medicare and Medicaid Services can be tracked through the application.

RESULTS

There are five functional areas including home, tasks, measures, improvement, and data. The home, tasks, and data pages are used to enter patient information and coordinate care using the five-step protocol. Measures and improvement pages are used to enter quality measures and provide practitioners with continuous performance feedback. The application resides within a portal, running on a multitenant, private cloud-based Avedis enterprise registry platform. All data are encrypted in transit and users access the application using a password from any common web browser.

CONCLUSION

The application could spread the FLS model of care across the US health care system, provide continuity of care, effectively manage osteoporotic patients, improve outcomes, and reduce medical costs.

Congenital high myopia and central macular atrophy: a report of 3 families

AIMS

To report the clinical phenotype in a series of four children from three families with the rare association of high myopia, central macular atrophy, and normal full-field electroretinography (ERG).

METHODS

Four male patients were ascertained with reduced vision, nystagmus, and atrophy of the macula from early childhood. Patients underwent full ophthalmic examination, electrophysiological testing, and retinal imaging.

RESULTS

Minimum duration of follow-up was 8 years. At last review, visual acuity ranged from 0.22 to 1.20 logMAR (6/9.5-6/95 Snellen) at a mean age of 10.5 years (median 9.5 years, range 9-14 years). Refractive error ranged from a spherical equivalent of -7.40 D to -24.00 D. Three had convergent squint. Fundus examination and imaging demonstrated bilateral macular atrophy in all patients that varied from mild atrophy of the retinal pigment epithelium (RPE) to well-demarcated, punched-out atrophic lesions of retina, RPE, and choroid. Flash ERG was normal under photopic and scotopic conditions in all patients. Pattern ERG, performed in three patients, was consistent with mild to severe macular dysfunction. Progression of the area of atrophy was evident in one patient and of the myopia in two patients but all patients had stable visual acuity.

CONCLUSIONS

Patients with congenital high myopia and macular atrophy present in infancy with reduced visual acuity and nystagmus. The macular atrophic lesions vary in size and severity but electrophysiological testing is consistent with dysfunction confined to the macula. There was no deterioration in visual acuity over 8-10 years of monitoring.

Multi-centre variability of ISCEV standard ERGs in two normal adults

BACKGROUND

The reproducibility of an individual's full-field ERG between centres has not previously been investigated.

METHODS

ERGs were recorded using both silver thread and skin electrodes from the same two normal adult subjects at 15 UK centres using routine, local protocols and a highly standardised, 'ISCEV-specified' protocol matching the values specified in the ISCEV standard; where the ISCEV standard allows options, a single value was chosen.

RESULTS

Inter-ocular differences were small, and amplitudes were smaller for skin than silver thread electrodes. No centre produced outlying data points, and ERGs across all 15 centres were remarkably similar. Amplitude variability was less for local protocols (using LED flashes) than for the ISCEV-specified protocol using xenon flashes (22 vs. 24 %, p = 0.01), but peak time variability was less for the ISCEV-specified protocol (6.1 vs. 7.4 %, p = 0.001). Only the DA 0.01 ERG correlated with photometric variability. The bifidity of the DA 3 a-wave doubled its peak time variability compared with the DA 10 a-wave.

CONCLUSIONS

Inter-centre amplitude variability was typically within clinically significant thresholds, suggesting that inter-centre variability with suitable standardisation may not add more to total variability than inter-subject variability. Variability improvements gained by the tighter specifications of the ISCEV-specified protocol were possibly more than lost due to imprecisions of xenon flashtubes. Peak time variability was far lower than amplitude variability, corresponding with acceptable variability of biochemical assays. These results represent a vindication of the existence of an ERG standard and suggest that further standardisation would lend itself to greater reproducibility of ERGs worldwide.

Semiconductor optical amplifiers grown on a metamorphic substrate for long wavelength applications

A semiconductor optical amplifier is grown on an InAsP metamorphic substrate to extend the long wavelength accessibility of the amplifier. The amplifier is shown to produce gain at wavelength exceeding 1640 nm while containing large tensile strain in the quantum wells. Also a laser diode is fabricated from the same device structure.

Electrical characteristics of core-shell p-n GaAs nanowire structures with Te as the n-dopant

GaAs nanowire (NW)-based p-n photovoltaic devices, with two distinct p and n spatial distributions and where Te was the n-dopant, have been studied by impedance spectroscopy in the 10(3)-10(7) Hz frequency range and the - 1.5-1.5 V bias range. For a large n-core/p-shell overlap region within NWs in a coaxial geometry, the p-n junction properties (DC rectification and p-n depletion capacitance) are found to prevail. The impedance data at low bias for both NW devices show large frequency dispersions with relaxation frequencies that are compatible with carrier re-emission times from traps due to GaAs surface states. An increasing conductance with increasing frequency for low bias is observed, suggesting hopping transport through localized states. For large bias the conductance increases exponentially with bias and is frequency independent, indicating conduction through extended states in this regime.

Variation in caregiver perceptions of teamwork climate in labor and delivery units

OBJECTIVE

To test the psychometric soundness of a teamwork climate survey in labor and delivery, examine differences in perceptions of teamwork, and provide benchmarking data.

DESIGN

Cross-sectional survey of labor and delivery caregivers in 44 hospitals in diverse regions of the US, using the Safety Attitudes Questionnaire teamwork climate scale.

RESULTS

The response rate was 72% (3382 of 4700). The teamwork climate scale had good internal reliability (overall alpha = 0.78). Teamwork climate scale factor structure was confirmed using multilevel confirmatory factor analyses (CFI = 0.95, TLI = 0.92, RMSEA = 0.12, SRMR(within) = 0.04, SRMR(between) = 0.09). Aggregation of individual-level responses to the L&D unit-level was supported by ICC (1) = 0.06 (P < 0.001), ICC (2) = 0.83 and mean r (wg(j)) = 0.83. ANOVA demonstrated differences between caregivers F (7, 3013) = 10.30, P < 0.001 and labor and delivery units, F (43, 1022) = 3.49, P < 0.001. Convergent validity of the scale scores was measured by correlations with external teamwork-related items: collaborative decision making (r = 0.780, P < 0.001), use of briefings (r = 0.496, P < 0.001) and perceived adequacy of staffing levels (r = 0.593, P < 0.001).

CONCLUSION

We demonstrate a psychometrically sound teamwork climate scale, correlate it to external teamwork-related items, and provide labor and delivery teamwork benchmarks. Further teamwork climate research should explore the links to clinical and operational outcomes.

The achiasmia spectrum: congenitally reduced chiasmal decussation

AIM

To describe the clinical spectrum of achiasmia, a congenital disorder of reduced relative decussation at the optic chiasm.

METHODS

A retrospective case note and patient review of nine children (four boys). Achiasmia was defined by the combination of a characteristic asymmetry of the monocular visual evoked potential (VEP) response to flash and neuroimaging showing reduced chiasmal size.

RESULTS

Three of the children had an associated skull base encephalocele with agenesis of the corpus callosum. In two patients achiasmia was associated with septo-optic dysplasia. Three patients had no neuroimaging abnormalities other than reduced chiasmal size and have no known pituitary dysfunction. One child had multiple physical deformities but the only brain imaging abnormality was reduced chiasmal size.

CONCLUSIONS

Some children with disorders of midline central nervous system development, including septo-optic dysplasia and skull base encephaloceles, have congenitally reduced chiasmal decussation. Reduced relative decussation may co-exist with overall chiasmal hypoplasia. Children with an apparently isolated chiasmal decussation deficit may have other subtle neurological findings, but our clinical impression is that most of these children function well.

Cataract in long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency (LCHADD)

Long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency (LCHADD) is a rare metabolic disorder that can lead to acute encephalopathy, liver disease, cardiomyopathy, rhabdomyolysis, and long-term complications involving the eye and peripheral nerves. LCHADD is a peroxisome biogenesis disorder (PBD). Except for the series presented by Tyni and colleagues (Ophthalmology 1998;105:810-824), which described visually insignificant lens opacities in association with LCHADD, previous ophthalmic papers have only reported retinal complications. We report on one case with progressive asymmetrical cataract. The more mildly affected eye had a similar morphology to that previously reported and the more severely affected eye had an unusual morphology we believe is unique to LCHADD. We discuss the range of ophthalmic presentations in our cases and in the literature. The variability of the severity of ocular complications, even between eyes in one individual, makes it difficult to test the effectiveness of therapeutic options upon the ophthalmic complications.

High-resolution NMR structure of the chemically-synthesized melanocortin receptor binding domain AGRP(87-132) of the agouti-related protein

The agouti-related protein (AGRP) is an endogenous antagonist of the melanocortin receptors MC3R and MC4R found in the hypothalamus and exhibits potent orexigenic (appetite-stimulating) activity. The cysteine-rich C-terminal domain of this protein, corresponding to AGRP(87-132), contains five disulfide bonds and exhibits receptor binding affinity and antagonism equivalent to that of the full-length protein. The three-dimensional structure of this domain has been determined by 1H NMR at 800 MHz. The first 34 residues of AGRP(87-132) are well-ordered and contain a three-stranded antiparallel beta sheet, where the last two strands form a beta hairpin. The relative spatial positioning of the disulfide cross-links demonstrates that the ordered region of AGRP(87-132) adopts the inhibitor cystine knot (ICK) fold previously identified for numerous invertebrate toxins. Interestingly, this may be the first example of a mammalian protein assigned to the ICK superfamily. The hairpin's turn region presents a triplet of residues (Arg-Phe-Phe) known to be essential for melanocortin receptor binding. The structure also suggests that AGRP possesses an additional melanocortin-receptor contact region within a loop formed by the first 16 residues of its C-terminal domain. This specific region shows little sequence homology to the corresponding region of the agouti protein, which is an MC1R antagonist involved in pigmentation. Consideration of these sequence differences, along with recent experiments on mutant and chimeric melanocortin receptors, allows us to postulate that this loop in the first 16 residues of its C-terminal domain confers AGRP's distinct selectivity for MC3R and MC4R.

CCR2 and CCR5 receptor-binding properties of herpesvirus-8 vMIP-II based on sequence analysis and its solution structure

Human herpesvirus-8 (HHV-8) is the infectious agent responsible for Kaposi's sarcoma and encodes a protein, macrophage inflammatory protein-II (vMIP-II), which shows sequence similarity to the human CC chemokines. vMIP-II has broad receptor specificity that crosses chemokine receptor subfamilies, and inhibits HIV-1 viral entry mediated by numerous chemokine receptors. In this study, the solution structure of chemically synthesized vMIP-II was determined by nuclear magnetic resonance. The protein is a monomer and possesses the chemokine fold consisting of a flexible N-terminus, three antiparallel beta strands, and a C-terminal alpha helix. Except for the N-terminal residues (residues 1-13) and the last two C-terminal residues (residues 73-74), the structure of vMIP-II is well-defined, exhibiting average rmsd of 0.35 and 0.90 A for the backbone heavy atoms and all heavy atoms of residues 14-72, respectively. Taking into account the sequence differences between the various CC chemokines and comparing their three-dimensional structures allows us to implicate residues that influence the quaternary structure and receptor binding and activation of these proteins in solution. The analysis of the sequence and three-dimensional structure of vMIP-II indicates the presence of epitopes involved in binding two receptors CCR2 and CCR5. We propose that vMIP-II was initially specific for CCR5 and acquired receptor-binding properties to CCR2 and other chemokine receptors.

Cellular characterization of leukotoxin diol-induced mitochondrial dysfunction

Leukotoxin, a cytochrome P450-derived epoxide of linoleic acid, has been implicated as a causative factor in acute respiratory distress syndrome. Conversion of this fatty acid epoxide to leukotoxin diol by epoxide hydrolase has been hypothesized as the critical activation step in leukotoxin-induced cellular toxicity. In both human and insect cells, we observed that leukotoxin diol causes acute cellular toxicity and that cyclosporin A, an inhibitor of the mitochondrial permeability transition, ameliorates leukotoxin diol-associated toxicity. To evaluate mitochondria as a target of leukotoxin diol, multiple aspects of mitochondrial integrity were evaluated in both cell- and organelle-based assays. Leukotoxin diol specifically activated the mitochondrial permeability transition, resulting in release of cytochrome c and subsequent cell death. Pretreatment with cyclosporin A inhibited these effects and, furthermore, limited in vivo toxicity. While the mechanisms underlying leukotoxin-mediated toxicity remain to be fully elucidated, the observation that leukotoxin diol disrupts mitochondrial function specifically through activation of the mitochondrial permeability transition suggests at least one mechanism through which leukotoxin diol may exert its activity in physiological contexts.

The HPV E7 oncoprotein inhibits tumor necrosis factor alpha-mediated apoptosis in normal human fibroblasts

Tumor necrosis factor-alpha (TNF) is a cytokine that induces programmed cell death, apoptosis, in a number of cell types and is employed by cytotoxic T cells to eliminate virus infected cells. Consequently, many viruses have acquired mechanisms to undermine these host cell defense mechanisms and cause resistance to TNF-mediated apoptosis. Here we show that normal human diploid fibroblasts that express the human papillomavirus type 16 E7 oncoprotein have a decreased propensity to undergo apoptosis in response to TNF treatment. The ability of E7 to undermine TNF-mediated apoptosis correlates with cellular transformation. While E7 does not generally subvert signaling by tumor necrosis factor receptor 1, pro-caspase 8 activation is decreased in E7-expressing cells. E7 also provides some protection from apoptosis caused by stimulation of the TNF receptor 1-related cytokine receptor Fas, where induction of apoptosis occurs much slower in this cell type. Hence, E7-expressing normal human fibroblasts exhibit a specific defect that obstructs cytokine-mediated activation of pro-caspase 8 and apoptosis.

Mutations in the gene encoding lecithin retinol acyltransferase are associated with early-onset severe retinal dystrophy

The chromophore of the visual pigments, 11-cis retinal, is derived from vitamin A (all-trans retinol) through a series of reactions that take place in retinal pigment epithelium (RPE); (ref. 1). The first of these reactions is catalyzed by lecithin retinol acyltransferase (LRAT); (ref. 2). We screened 267 retinal dystrophy patients for mutations in LRAT and identified disease-associated mutations (S175R and 396delAA) in three individuals with severe, early-onset disease. We showed that the S175R mutant has no acyltransferase activity in transfected COS-7 cells. Our findings highlight the importance of genetic defects in vitamin A metabolism as causes of retinal dystrophies and extend prospects for retinoid replacement therapy in this group of diseases.

Pathways of epoxyeicosatrienoic acid metabolism in endothelial cells. Implications for the vascular effects of soluble epoxide hydrolase inhibition

Epoxyeicosatrienoic acids (EETs) are products of cytochrome P-450 epoxygenase that possess important vasodilating and anti-inflammatory properties. EETs are converted to the corresponding dihydroxyeicosatrienoic acid (DHET) by soluble epoxide hydrolase (sEH) in mammalian tissues, and inhibition of sEH has been proposed as a novel approach for the treatment of hypertension. We observed that sEH is present in porcine coronary endothelial cells (PCEC), and we found that low concentrations of N,N'-dicyclohexylurea (DCU), a selective sEH inhibitor, have profound effects on EET metabolism in PCEC cultures. Treatment with 3 microM DCU reduced cellular conversion of 14,15-EET to 14,15-DHET by 3-fold after 4 h of incubation, with a concomitant increase in the formation of the novel beta-oxidation products 10,11-epoxy-16:2 and 8,9-epoxy-14:1. DCU also markedly enhanced the incorporation of 14,15-EET and its metabolites into PCEC lipids. The most abundant product in DCU-treated cells was 16,17-epoxy-22:3, the elongation product of 14,15-EET. Another novel metabolite, 14,15-epoxy-20:2, was present in DCU-treated cells. DCU also caused a 4-fold increase in release of 14,15-EET when the cells were stimulated with a calcium ionophore. Furthermore, DCU decreased the conversion of [3H]11,12-EET to 11,12-DHET, increased 11,12-EET retention in PCEC lipids, and produced an accumulation of the partial beta-oxidation product 7,8-epoxy-16:2 in the medium. These findings suggest that in addition to being metabolized by sEH, EETs are substrates for beta-oxidation and chain elongation in endothelial cells and that there is considerable interaction among the three pathways. The modulation of EET metabolism by DCU provides novel insight into the mechanisms by which pharmacological or molecular inhibition of sEH effectively treats hypertension.

Human immunodeficiency virus type 1 entry inhibitors PRO 542 and T-20 are potently synergistic in blocking virus-cell and cell-cell fusion

Human immunodeficiency virus type 1 (HIV-1) entry proceeds via a cascade of events that afford promising targets for therapy. PRO 542 neutralizes HIV-1 by blocking its attachment to CD4 cells, and T-20 blocks gp41-mediated fusion. Both drugs have shown promise in phase 1/2 clinical trials. Here, the drugs were tested individually and in combination in preclinical models of HIV-1 infection, and inhibition data were analyzed for cooperativity by using the combination index method. Synergistic inhibition of virus-cell and cell-cell fusion was observed for phenotypically diverse viruses for a broad range of drug concentrations, often resulting in > or = 10-fold dose reductions in vitro. Additional mechanism-of-action studies probed the molecular basis of the synergies. The markedly enhanced activity observed for the PRO 542:T-20 combination indicates that the multistep nature of HIV-1 entry leaves the virus particularly vulnerable to combinations of entry inhibitors. These findings provide a strong rationale for evaluating combinations of these promising agents for therapy in vivo.

Inhibition of the visual cycle in vivo by 13-cis retinoic acid protects from light damage and provides a mechanism for night blindness in isotretinoin therapy

Isotretinoin (13-cis retinoic acid) is frequently prescribed for severe acne [Peck, G. L., Olsen, T. G., Yoder, F. W., Strauss, J. S., Downing, D. T., Pandya, M., Butkus, D. & Arnaud-Battandier, J. (1979) N. Engl. J. Med. 300, 329-333] but can impair night vision [Fraunfelder, F. T., LaBraico, J. M. & Meyer, S. M. (1985) Am. J. Ophthalmol. 100, 534-537] shortly after the beginning of therapy [Shulman, S. R. (1989) Am. J. Public Health 79, 1565-1568]. As rod photoreceptors are responsible for night vision, we administered isotretinoin to rats to learn whether night blindness resulted from rod cell death or from rod functional impairment. High-dose isotretinoin was given daily for 2 months and produced systemic toxicity, but this caused no histological loss of rod photoreceptors, and rod-driven electroretinogram amplitudes were normal after prolonged dark adaptation. Additional studies showed, however, that even a single dose of isotretinoin slowed the recovery of rod signaling after exposure to an intense bleaching light, and that rhodopsin regeneration was markedly slowed. When only a single dose was given, rod function recovered to normal within several days. Rods and cones both showed slow recovery from bleach after isotretinoin in rats and in mice. HPLC analysis of ocular retinoids after isotretinoin and an intense bleach showed decreased levels of rhodopsin chromophore, 11-cis retinal, and the accumulation of the biosynthetic intermediates, 11-cis and all-trans retinyl esters. Isotretinoin was also found to protect rat photoreceptors from light-induced damage, suggesting that strategies of altering retinoid cycling may have therapeutic implications for some forms of retinal and macular degeneration.

Nicardipine versus nitroprusside for breakthrough hypertension following carotid endarterectomy

STUDY OBJECTIVE

To evaluate the effectiveness of nicardipine and nitroprusside for breakthrough hypertension following carotid endarterectomy.

DESIGN

Prospective, randomized, double-blind, controlled effectiveness trial.

SETTING

University-based surgical intensive care unit.

PATIENTS

60 ASA physical status I, II, III, and IV patients experiencing breakthrough hypertension at the time of admission to the intensive care unit (ICU).

INTERVENTIONS

Patients received either nicardipine (n = 29) and placebo or nitroprusside (n = 31) and placebo for up to 6 hours postoperatively. Loading doses of nicardipine were provided, but placebo was used as a load for patients randomized to nitroprusside.

MEASUREMENTS AND MAIN RESULTS

Rapidity and variability of blood pressure (BP) control were assessed. During the first 10 minutes, 83% of nicardipine patients compared to 23% of nitroprusside-treated patients, achieved BP control (p < 0.01). Following initial control, 12 nicardipine- and 24 nitroprusside-treated patients required additional titration of their infusions to maintain blood pressure within the targeted range (p < 0.05). No patient suffered a stroke, myocardial infarction, or was returned to the operating room (OR) for bleeding.

CONCLUSIONS

Nicardipine administration produced more rapid BP control, most likely related to the administration of a loading dose. In addition to more rapid control, nicardipine-treated patients had less variability in BP and required significantly fewer additional interventions. Although no patient suffered a major event during this study, this study was not powered sufficiently to assess safety.

Genetics and phenotypes of RPE65 mutations in inherited retinal degeneration

PURPOSE

To characterize the spectrum of RPE65 mutations present in 453 patients with retinal dystrophy with an interest in understanding the range of functional deficits attributable to sequence variants in this gene.

METHODS

The 14 exons of RPE65 were amplified by polymerase chain reaction (PCR) from patients' DNA and analyzed for sequence changes by single-strand conformation polymorphism (SSCP) and direct sequencing. Haplotype analysis was performed using RPE65 intragenic polymorphisms. Patients were examined clinically and with visual function tests.

RESULTS

Twenty-one different disease-associated DNA sequence changes predicting missense or nonsense point mutations, insertions, deletions, and splice site defects in RPE65 were identified in 20 patients in homozygous or compound heterozygous form. In one patient, paternal uniparental isodisomy (UPD) of chromosome 1 resulted in homozygosity for a probable functional null allele. Eight of the disease-associated mutations (Y79H, E95Q, E102X, D167Y, 669delCA, IVS7+4a-->g, G436V, and G528V) and one mutation likely to be associated with disease (IVS6+5g-->a) have not been reported previously. The most commonly occurring sequence variant identified in the patients studied was the IVS1+5g-->a mutation, accounting for 9 of 40 (22.5%) total disease alleles. This splice site mutation, as well as R91W, the most common missense mutation, exists on at least two different genetic backgrounds. The phenotype resulting from RPE65 mutations appears to be relatively uniform and independent of mutation class, suggesting that most missense mutations (15 of 40 disease alleles [37.5%]) result in loss of function. At young ages, this group of patients has somewhat better subjective visual capacity than is typically associated with Leber congenital amaurosis (LCA) type I, with a number of patients retaining some useful visual function beyond the second decade of life.

CONCLUSIONS

RPE65 mutations account for a significant percentage (11.4%) of disease alleles in patients with early-onset retinal degeneration. The identification and characterization of patients with RPE65 mutations is likely to represent an important resource for future trials of rational therapies for retinal degeneration.

PDZK1 and GREB1 are estrogen-regulated genes expressed in hormone-responsive breast cancer

The function of estrogen in breast cancer proliferation and progression is likely to be due to the expression of a repertoire of genes regulated by estrogen receptor (ER). Using suppression subtractive hybridization, we have isolated a set of 14 estrogen-responsive genes that was differentially expressed in MCF7 cells stimulated by beta-estradiol as compared with unstimulated cells. Tamoxifen repressed the expression of all 14 estrogen-responsive genes. Thirteen of the genes were induced within 6 h of estrogen treatment, indicating that these were early response genes in the ER-regulated pathway. PDZK1 and a new gene, GREB1, demonstrated a significant correlation with ER phenotype in a panel of breast cancer cell lines. Treatment with cycloheximide indicated that ER directly controls GREB1 expression. Three cDNAs (GREB1a, GREB1b, and GREB1c) were isolated by screening a MCF7 cDNA library. These three cDNAs of GREB1 shared extensive sequences through the open reading frame but had divergent 5' untranslated regions, indicating the possibility of multiple promoters regulated by beta-estradiol. Studies in primary breast cancers showed that PDZK1 and GREB1 were overexpressed in ER-positive breast cancers as compared with ER-negative breast cancers by 19-fold and 3.5-fold, respectively. GREB1 was also induced by beta-estradiol in the ER-positive endometrial cell line ECC-1. The pattern of expression suggests a critical role for these two genes in the response of tissues and tumors to beta-estradiol.

Mutations in MERTK, the human orthologue of the RCS rat retinal dystrophy gene, cause retinitis pigmentosa

Mutation of a receptor tyrosine kinase gene, Mertk, in the Royal College of Surgeons (RCS) rat results in defective phagocytosis of photoreceptor outer segments by the retinal pigment epithelium (RPE) and retinal degeneration. We screened the human orthologue, MERTK, located at 2q14.1 (ref. 10), in 328 DNA samples from individuals with various retinal dystrophies and found three mutations in three individuals with retinitis pigmentosa (RP). Our findings are the first conclusive evidence implicating the RPE phagocytosis pathway in human retinal disease.

Comparison of the structure of vMIP-II with eotaxin-1, RANTES, and MCP-3 suggests a unique mechanism for CCR3 activation

Herpesvirus-8 macrophage inflammatory protein-II (vMIP-II) binds a uniquely wide spectrum of chemokine receptors. We report the X-ray structure of vMIP-II determined to 2.1 A resolution. Like RANTES, vMIP-II crystallizes as a dimer and displays the conventional chemokine tertiary fold. We have compared the surface topology and electrostatic potential of vMIP-II to those of eotaxin-1, RANTES, and MCP-3, three CCR3 physiological agonists with known three-dimensional structures. Surface epitopes identified on RANTES to be involved in binding to CCR3 are mimicked on the eotaxin-1 and MCP-3 surface. However, the surface topology of vMIP-II in these regions is markedly different. The results presented here indicate that the structural basis for interaction with the chemokine receptor CCR3 by vMIP-II is different from that for the physiological agonists eotaxin-1, RANTES, and MCP-3. These differences on vMIP-II may be a consequence of its broad-range receptor recognition capabilities.

Presentation of chemokine SDF-1 alpha by fibronectin mediates directed migration of T cells

The role of chemokine-matrix interactions in integrin-dependent T-cell migration was examined to address the critical question of how chemokines provide directional information. The chemokine SDF-1 alpha binds fibronectin (Fn) with a low nanomolar K(d) (equilibrium dissociation constant). SDF-1 alpha presented by Fn induced directed migration. Spatial concentration gradients of chemokine were not required to maintain directed migration. Fn-presented chemokine induced the polarization of cells, including the redistribution of the SDF-1 alpha receptor, to the basal surface and leading edge of the cell. A new model for directed migration is proposed in which the co-presentation of an adhesive matrix and chemokine provides the necessary positional information independent of a soluble spatial gradient. (Blood. 2000;96:2682-2690)

Predictors of pain control in patients undergoing flexible bronchoscopy

The purpose of this study was to assess the extent to which patients undergoing flexible bronchoscopy (FOB) experience pain and to identify patient factors and process of care factors that are associated with pain. We conducted a prospective cohort study on 481 patients undergoing FOB. Overall control of pain during FOB was the primary outcome. The mean age of the patients was 48 yr, 50% were male, and 32% required supplemental oxygen prior to FOB. Pain control was excellent in 36% of patients, but 10% considered it to be fair or poor. Patient factors associated with excellent pain control were excellent health (versus poor health, OR = 6.25 [95% CI, 2.28-16.67]), more education (college education versus high school education, OR = 1.72 [95% CI, 1.05-2.86]), and not having asthma (OR = 2.86 [95% CI, 1.09-7.14]). Process of care factors associated with excellent pain control were not being bothered by scope insertion (versus bothered, OR = 3.65 [95% CI, 1.99-6.98]), no memory of FOB (versus some memory, OR = 2.33 [95% CI, 1.24-4.44]), and higher ratings of information about the procedure (per 1-point increase on a 12-point scale, OR = 1.57 [95% CI, 1.41-1.78]). This is the first large-scale, prospective study to evaluate patient and process of care factors that influence pain control during FOB. It demonstrated that there are patient characteristics and process of care factors that need to be considered when evaluating pain during bronchoscopy. Improved preparation of patients with lower education, inferior health status, and asthma may lead to decreased pain during FOB. Bronchoscopists may be able to reduce pain during FOB by identifying methods to decrease pain on scope insertion, by improving the information provided to patients, and by achieving greater levels of amnesia during FOB.

Sexually transmitted diseases in a family planning and an antenatal clinic in Peru: limitations of current practices and analysis of the use of potential markers, pH testing, and Whiff testing

BACKGROUND

Little data exist on sexually transmitted diseases (STDs), including HIV, in family planning and antenatal clinics in Peru.

GOAL

To evaluate (1) the prevalence of infection, (2) associated factors, (3) current clinical practices, and (4) the sensitivity of whiff and pH testing for STDs.

STUDY DESIGN

A study of 363 women from an antenatal (n = 259) and a family planning (n = 104) clinic in central Lima, Peru that included oral histories and physical examinations. Samples were collected for laboratory diagnosis of common STDs, including HIV.

RESULTS

Overall, 10.8% of antenatal clinic patients and 15.4% of family planning clinic patients had an STD, but no HIV infection was found. The diagnostic sensitivity of health providers was low, especially for cervical infections (sensitivity, 0%). In addition, few factors were associated with cervical infections or trichomoniasis. In the family planning clinic, pH testing was 100% sensitive for trichomoniasis and bacterial vaginosis. In both clinics, whiff testing was 84% sensitive and 47% specific for trichomoniasis and 88% sensitive and 53% specific for bacterial vaginosis.

CONCLUSION

The burden of STDs was high and the sensitivity of current diagnostic practices was low. These results point to the need for simple diagnostic tools. Whiff and pH testing was found potentially useful for the diagnosis of vaginal infections. These simple tests should be implemented as screening tools.

Entry of R5X4 and X4 human immunodeficiency virus type 1 strains is mediated by negatively charged and tyrosine residues in the amino-terminal domain and the second extracellular loop of CXCR4

CXCR4 mediates the fusion and entry of X4 and R5X4 strains of human immunodeficiency virus type 1 (HIV-1). The residues involved in CXCR4 coreceptor function have not all yet been identified, but tyrosine and negatively charged residues in the amino-terminal domain of CCR5 were shown to be indispensable for gp120 binding and entry of R5 and R5X4 strains. We therefore evaluated the role of such residues in CXCR4 coreceptor function by replacing tyrosines (Y), aspartic acids (D), and glutamic acids (E) with alanines (A) and testing the ability of these mutants to mediate the entry of X4 and R5X4 HIV-1 isolates. Our results show that viral entry depends on YDE-rich clusters in both the amino-terminus and the second extracellular loop of CXCR4. Different viral isolates vary in their dependence on residues in one or the other domain. The determinants of CXCR4 coreceptor function are, therefore, more diffuse and isolate-dependent than those of CCR5.

Sequencing of peach latent mosaic viroid variants from nine North American peach cultivars shows that this RNA folds into a complex secondary structure

We sequenced 34 new peach latent mosaic viroid (PLMVd) variants isolated from nine different peach cultivars. This study provides the widest view of PLMVd diversity reported to date and includes the original characterization of North American variants, which cannot be differentiated from European sequences. PLMVd appears as a species in which each isolate is a complex mixture of RNAs. Analysis of base-pair covariations supports the hypothesis that PLMVd folds into a complex branched structure with the potential of including three new pseudoknots. The resulting "globular-like" structure is in contrast to the rod-like one adopted by most other viroids.

Specific interaction of CCR5 amino-terminal domain peptides containing sulfotyrosines with HIV-1 envelope glycoprotein gp120

The HIV-1 envelope glycoprotein gp120 interacts consecutively with CD4 and the CCR5 coreceptor to mediate the entry of certain HIV-1 strains into target cells. Acidic residues and sulfotyrosines in the amino-terminal domain (Nt) of CCR5 are crucial for viral fusion and entry. We tested the binding of a panel of CCR5 Nt peptides to different soluble gp120/CD4 complexes and anti-CCR5 mAbs. The tyrosine residues in the peptides were sulfated, phosphorylated, or unmodified. None of the gp120/CD4 complexes associated with peptides containing unmodified or phosphorylated tyrosines. The gp120/CD4 complexes containing envelope glycoproteins from isolates that use CCR5 as a coreceptor associated with Nt peptides containing sulfotyrosines but not with peptides containing sulfotyrosines in scrambled Nt sequences. Finally, only peptides containing sulfotyrosines inhibited the entry of an R5 isolate. Our data show that proper posttranslational modification of the CCR5 Nt is required for gp120 binding and viral entry. More importantly, the Nt domain determines the specificity of the interaction between CCR5 and gp120s from isolates that use this coreceptor.

A binding pocket for a small molecule inhibitor of HIV-1 entry within the transmembrane helices of CCR5

HIV-1 entry into CD4(+) cells requires the sequential interactions of the viral envelope glycoproteins with CD4 and a coreceptor such as the chemokine receptors CCR5 and CXCR4. A plausible approach to blocking this process is to use small molecule antagonists of coreceptor function. One such inhibitor has been described for CCR5: the TAK-779 molecule. To facilitate the further development of entry inhibitors as antiviral drugs, we have explored how TAK-779 acts to prevent HIV-1 infection, and we have mapped its site of interaction with CCR5. We find that TAK-779 inhibits HIV-1 replication at the membrane fusion stage by blocking the interaction of the viral surface glycoprotein gp120 with CCR5. We could identify no amino acid substitutions within the extracellular domain of CCR5 that affected the antiviral action of TAK-779. However, alanine scanning mutagenesis of the transmembrane domains revealed that the binding site for TAK-779 on CCR5 is located near the extracellular surface of the receptor, within a cavity formed between transmembrane helices 1, 2, 3, and 7.

Setting-based practice variation in the management of simple febrile seizure

OBJECTIVE

To identify provider-based differences in the ED assessment and management of children presenting with uncomplicated, first-time febrile seizures.

METHODS

Multicenter, retrospective cohort study of seven EDs in-the Chicago area: two tertiary academic pediatric EDs (PEDs) and five community-based general EDs (GEDs). The visits of all patients with a discharge diagnosis including the term "seizure" were identified from a 30-month period. Records of patients who met criteria for simple, first-time febrile seizure were reviewed (age 6-60 months; temperature > or =38.0 degrees C; single, generalized, tonic-clonic seizure <20 minutes; "alert" or "arousable" on presentation; absence of known neurologic disease).

RESULTS

Four hundred fifty-five records were included: 330 and 125 patients presenting to GEDs and PEDs, respectively. The two groups did not differ in mean age, vital signs, reported duration of seizure, or prior antibiotic use. Lumbar puncture (LP) was performed more often in the GED group (33% vs 22%). No patients were found to have bacterial meningitis. The patients in the GED group were more likely to receive parenteral antibiotics in the ED (56% vs 22%) and to be admitted or transferred (18% vs 4%). In a logistic regression model incorporating age, temperature, seizure duration, seizure in the ED, prior antibiotic use, primary care, and insurance status, the GED patients remained more likely to have an LP (OR 1.5), receive parenteral antibiotics (OR 2.5), and be admitted or transferred (OR 2.5).

CONCLUSIONS

There were significant setting-based differences in the evaluation and management of children with simple febrile seizures presenting to GEDs and PEDs.

The chemokine receptor antagonist AOP-RANTES reduces monocyte infiltration in experimental glomerulonephritis

The chemokine receptor antagonist AOP-RANTES reduces monocyte infiltration in experimental glomerulonephritis.

BACKGROUND

This study was designed to evaluate the role of the novel chemokine receptor antagonist amino-oxypentane RANTES (AOP-RANTES), which blocks the binding of macrophage inflammatory protein-1alpha (MIP-1alpha), MIP-1beta, and RANTES to the chemokine receptor-5 (CCR-5) on the infiltration of monocytes in experimental glomerulonephritis.

METHODS

Rats were treated twice daily with 12.5 microg AOP-RANTES following an induction of anti-rat-thymocyte antibody-mediated glomerulonephritis. The white blood cell count, glomerular monocyte infiltration, chemokine expression, and collagen type IV deposition were assessed.

RESULTS

The induction of glomerulonephritis increased glomerular monocyte/macrophage (M/M) infiltration at 24 hours and at 5 days was still higher than in controls. AOP-RANTES prevented glomerular M/M infiltration at 24 hours and at 5 days. This was paralleled by reduced glomerular collagen type IV deposition as a fibrotic marker in nephritic animals.

CONCLUSION

These data show that the CCR-5 chemokine receptor antagonist AOP-RANTES ameliorates M/M infiltration and improves glomerular pathology in experimental glomerulonephritis. The use of chemokine receptor antagonists may offer a new therapeutic option in inflammatory renal injuries.

Visual-evoked potential evidence of chiasmal hypoplasia

PURPOSE

To show that chiasmal hypoplasia or aplasia need not be an isolated developmental anomaly and to examine the spectrum of associated clinical findings to explore the possibility that these patients may represent a phenotypic manifestation of a developmental gene anomaly.

DESIGN

An observational case series.

PARTICIPANTS

Five infants, between several weeks and 7 months of age, in whom the electrophysiologic characteristic of chiasmal hypoplasia had been noted were included.

METHODS

Flash electroretinography and flash and pattern visual-evoked potentials (VEPs) were elicited from all patients. Clinical ophthalmologic examinations, including funduscopy, were performed, and all patients had magnetic resonance imaging (MRI) brain scans.

MAIN OUTCOME MEASURES

The occipital distribution of monocular VEP response peaks was studied. The symmetry of lateral channel responses was compared for monocular stimulation.

RESULTS

All five patients had a crossed asymmetry in the monocular VEP occipital distribution, which is consistent with a paucity of fibers crossing at the chiasm. The MRI findings supported this electrophysiologic observation, illustrating degrees of chiasmal hypoplasia and variable coincidence of other midline abnormalities of the brain. Optic disc appearances varied from normal to hypoplastic and colobomatous.

CONCLUSIONS

The ophthalmologic and MRI findings of five patients who showed a crossed asymmetry in monocular flash VEPs are consistent with a paucity of axons crossing at the chiasm. The similarities between achiasmia in humans and mice due to a Pax2 gene anomaly are discussed.

Expression of functional CXCR4 chemokine receptors on human colonic epithelial cells

In addition to their role as regulators of leukocyte migration and activation, chemokines and their receptors also function in angiogenesis, growth regulation, and HIV-1 pathogenesis--effects that involve the action of chemokines on nonhematopoietic cells. To determine whether chemokine receptors are expressed in human colonic epithelium, HT-29 cells were examined by RT-PCR for the expression of the chemokine receptors for lymphotactin, fractalkine, CCR1-10, and CXCR1-5. The only receptor consistently detected was CXCR4 (fusin/LESTR), although HT-29 cells did not express mRNA for its ligand, stromal cell-derived factor (SDF-1alpha). Flow cytometric analysis with anti-CXCR4 antibody indicated that the CXCR4 protein was expressed on the surface of roughly half of HT-29 cells. CXCR4 was also expressed in colonic epithelial cells in vivo as shown by immunohistochemistry on biopsies from normal and inflamed human colonic mucosa. The mRNA for SDF-1alpha and other CC and CXC chemokines was present in normal colonic biopsies. The CXCR4 receptor in HT-29 cells was functionally coupled, as demonstrated by the elevation in [Ca2+]i, which occurred in response to 25 nM SDF-1alpha and by the SDF-1alpha-induced upregulation of ICAM-1 mRNA. Sodium butyrate downregulated CXCR4 expression and induced differentiation of HT-29 cells, suggesting a role for CXCR4 in maintenance and renewal of the colonic epithelium. This receptor, which also serves as a coreceptor for HIV, may mediate viral infection of colonic epithelial cells.

Genetic control of recombination partner preference in yeast meiosis. Isolation and characterization of mutants elevated for meiotic unequal sister-chromatid recombination

Meiotic exchange occurs preferentially between homologous chromatids, in contrast to mitotic recombination, which occurs primarily between sister chromatids. To identify functions that direct meiotic recombination events to homologues, we screened for mutants exhibiting an increase in meiotic unequal sister-chromatid recombination (SCR). The msc (meiotic sister-chromatid recombination) mutants were quantified in spo13 meiosis with respect to meiotic unequal SCR frequency, disome segregation pattern, sporulation frequency, and spore viability. Analysis of the msc mutants according to these criteria defines three classes. Mutants with a class I phenotype identified new alleles of the meiosis-specific genes RED1 and MEK1, the DNA damage checkpoint genes RAD24 and MEC3, and a previously unknown gene, MSC6. The genes RED1, MEK1, RAD24, RAD17, and MEC1 are required for meiotic prophase arrest induced by a dmc1 mutation, which defines a meiotic recombination checkpoint. Meiotic unequal SCR was also elevated in a rad17 mutant. Our observation that meiotic unequal SCR is elevated in meiotic recombination checkpoint mutants suggests that, in addition to their proposed monitoring function, these checkpoint genes function to direct meiotic recombination events to homologues. The mutants in class II, including a dmc1 mutant, confer a dominant meiotic lethal phenotype in diploid SPO13 meiosis in our strain background, and they identify alleles of UBR1, INP52, BUD3, PET122, ELA1, and MSC1-MSC3. These results suggest that DMC1 functions to bias the repair of meiosis-specific double-strand breaks to homologues. We hypothesize that the genes identified by the class II mutants function in or are regulators of the DMC1-promoted interhomologue recombination pathway. Class III mutants may be elevated for rates of both SCR and homologue exchange.

Electron Microscopic Detection of Novel, Coiled Viruslike Particles Associated with Graft-Inoculation of Prunus Species

Coiled, viruslike particles (spirions) were detected by electron microscopic examination of crude extracts from flowers, leaves, and/or roots of infected Prunus avium, P. mume, and P. serrulata. The particles were observed in ultrathin sections of lower epidermis, palisade, and spongy mesophyll cells of leaves of P. avium and P. mume. Spring (March and April) appears to be optimal for detection of the particles in both screenhouse and field-grown plants. The particles were successfully graft-transmitted to P. armeniaca (cvs. Luizet and Tilton), P. avium (cvs. Bing, F12/1, Mazzard, and Sam), P. mahaleb, and P. persica (cv. Elberta). Individual spirions measured 132 × 34 nm. The particles appear to be coiled forms of a filamentous virus. Filaments extending from some coiled particles were approximately 13 nm wide, with striations at a pitch of 3.24 nm. No disease symptoms or cytopathological abnormalities were associated with the presence of the particles in the Prunus species studied. The particles were not detected in virus-free control plants.