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Biomedical subjects

D Wong

Publications and source records attributed to D Wong.

At least 73 records · Page 4Linked to original sources
PubMed2001

The Goodpasture antigen is expressed in the human thymus.

BACKGROUND: Autoimmunity to kidney antigens causes membranous nephropathy and Goodpasture's disease and very likely is pivotal in many other glomerular diseases. We investigated the potential for central tolerance to the best-characterized kidney autoantigen, the NC1 domain of the alpha3 chain of type IV collagen [alpha3(IV)NC1], which is the target of autoimmune attack in Goodpasture's disease. METHODS: Indirect immunofluorescence on human thymus and polymerase chain reaction (PCR) and Southern blot analysis of cDNA reverse transcribed from RNA extracted from human thymus and kidney. RESULTS: Indirect immunofluorescence on human thymus demonstrated the presence of alpha3(IV)NC1 in all six thymus samples examined. The homologous collagen IV chain, alpha5(IV)NC1, also was detected with a similar intra-thymic distribution. Strikingly, thymic alpha3 and alpha5 localized around and within Hassall's corpuscles in the thymic medulla, which are structures implicated in T cell apoptosis and possibly negative selection. In contrast, alpha1(IV)NC1 localized to the basement membranes of interlobular septa and blood vessels, as is typical of collagen IV chains situated outside the thymus. Reverse transcription-polymerase chain reaction (RT-PCR) confirmed the presence of mRNA encoding alpha3(IV)NC1 and alpha5(IV)NC1 in thymic tissue establishing that the antigens were likely to have been synthesized locally. CONCLUSIONS: The results demonstrate that alpha3(IV)NC1 is expressed in the human thymus, and therefore should be available for induction of alpha3(IV)NC1-specific tolerance. This observation has the important implication that patients' alpha3(IV)NC1-specific, autoreactive T cells are more likely to recognize cryptic epitopes that are not adequately presented by thymic antigen-presenting cells (APC) than the major antigen-derived epitopes generally identified by conventional approaches.

Adolescent↗
PubMed2001

Residential proximity to industrial sources of air pollution: interrelationships among race, poverty, and age.

This study builds on earlier work investigating statistical relationships between sociodemographic characteristics of populations and their residential proximity to industrial sources of air pollution. The analysis uses demographic data from the 1990 U.S. Census and industrial site data from the U.S. Environmental Protection Agency (EPA)'s 1990 Toxics Release Inventory (TRI). The focus is on examining interactions among race (African Americans and Whites), poverty (above and below household poverty threshold), and age (children from birth to 5 years of age and elderly people 65 years old or older). Results from three different study areas (Kanawha Valley in West Virginia, the Baton Rouge-New Orleans Corridor in Louisiana, and the greater Baltimore metropolitan area in Maryland) suggest there are important interactions among race, poverty, and age that are likely to have consequential ramifications for efforts aimed at investigating issues related to environmental justice. Our results indicate that a substantial proportion of all demographic groups studied live within a mile of the nearest facility, with values ranging from 22% of Whites above poverty in the Baton Rouge-New Orleans Corridor to 60% of African Americans below poverty in Baltimore. Likewise, a substantial proportion of all demographic groups also live within 2 miles of four or more industrial facilities, with values ranging from 16% for Whites above poverty in the Corridor to 70% for African Americans below poverty in Baltimore. In all three study areas, African Americans were more likely than Whites to (1) live in households with incomes below the household poverty line, (2) have children 5 years of age or younger, (3) live closer to the nearest industrial emissions source, and (4) live within 2 miles of multiple industrial emission sources. Findings indicate that, compared with White children, a substantially higher proportion of African-American children 5 years of age or younger lived in poor households that were located in relatively close proximity to one or more industrial sources of air pollution.

Adolescent↗
PubMed2001

Clinicopathological correlation of epiretinal membranes and posterior lens opacification following perfluorohexyloctane tamponade.

BACKGROUND/AIMS: Epiretinal and retrolental proliferation may occur during prolonged use of the novel tamponade agent perfluorohexyloctane (F(6)H(8)). This study aims to determine whether there is any histological evidence that F(6)H(8) has a role in the formation of these membranes. METHODS: Eight epiretinal membranes and three opaque posterior lens capsules were excised from patients in whom F(6)H(8) had been used as a long term retinal tamponade agent. The membranes and capsules were examined employing light microscopic methods, including immunohistochemistry. RESULTS: The epiretinal membranes showed histological features typical of proliferative vitreoretinopathy (PVR) epiretinal membranes, but they also exhibited a dense macrophagic infiltration. In addition, three of the membranes contained multinucleated cells. Macrophages represented up to 30% of the cells present and appeared to contain large intracytoplasmic vacuoles. Similar cells were seen on the back of the posterior lens capsule in one specimen and all three capsules had posterior migration of lens epithelium. CONCLUSION: The pathological findings are not simply those of PVR. The macrophage infiltration suggests that there may be a biological reaction to F(6)H(8) which could reflect its surmised propensity to emulsify. Further investigations concerning the cellular response to this promising tamponade agent are warranted.

Adult↗
PubMed2000

Host gene regulation during coxsackievirus B3 infection in mice: assessment by microarrays.

Host genetic responses that characterize enteroviral myocarditis have not yet been determined. The injurious and inflammatory process in heart muscle may reflect host responses of benefit to the virus and ultimately result in congestive heart failure and dilated cardiomyopathy. On the other hand, host responses within the myocardium may secure the host against acute or protracted damage. To investigate the nature of modified gene expression in comparison with normal tissue, mRNA species were assessed in myocardium using cDNA microarray technology at days 3, 9, and 30 after infection. Of 7000 clones initially screened, 169 known genes had a level of expression significantly different at 1 or more postinfection time points as compared with baseline. The known regulated genes were sorted according to their functional groups and normalized expression patterns and, subsequently, interpreted in the context of viremic, inflammatory, and healing phases of the myocarditic process.

Animals↗
PubMed2000

Cross-correlation for flow cytometric histogram background subtractions.

Background subtraction is a widely encountered problem in flow cytometry applications for which the currently available analysis techniques are unsatisfactory. The 99% division line method, also referred to as the threshold or marker method, is widely used because it is computationally simple but it has poor accuracy and tends to underestimate the percentage of positive cells when there is overlap between histograms. Model-based approaches are preferred when there are overlapping peaks, but these methods require curve fitting and strong assumptions regarding the shape of the underlying distributions. This report assesses a mathematically rigorous, computationally facile, non-parametric technique called cross correlation for the background subtraction problem. A metric, positivity, derived from cross correlation is shown to overcome the disadvantages of both the 99% division line and model-based methods without compromise.

Flow Cytometry↗
PubMed2000

Hypothalamic-pituitary-adrenal dysfunction in Apoe(-/-) mice: possible role in behavioral and metabolic alterations.

Several neurological diseases are frequently accompanied by dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis. The HPA axis regulates the secretion of glucocorticoids (GCs), which play important roles in diverse brain functions, including cognition, emotion, and feeding. Under physiological conditions, GCs are adaptive and beneficial; however, prolonged elevations in GC levels may contribute to neurodegeneration and brain dysfunction. In the current study, we demonstrate that apolipoprotein E (apoE) deficiency results in age-dependent dysregulation of the HPA axis through a mechanism affecting primarily the adrenal gland. Apoe(-/-) mice, which develop neurodegenerative alterations as they age, had an age-dependent increase in basal adrenal corticosterone content and abnormally increased plasma corticosterone levels after restraint stress, whereas their plasma and pituitary adrenocorticotropin levels were either unchanged or lower than those in controls. HPA axis dysregulation was associated with behavioral and metabolic alterations. When anxiety levels were assessed in the elevated plus maze, Apoe(-/-) mice showed more anxiety than wild-type controls. Apoe(-/-) mice also showed reduced activity in the open field. Finally, Apoe(-/-) mice showed age-dependent increases in food and water intake, stomach and body weights, and decreases in brown and white adipose tissues. These results support a key role for apoE in the tonic inhibition of steroidogenesis and HPA axis activity and have important implications for the behavioral analysis of Apoe(-/-) mice.

Adrenal Glands↗
PubMed2000

Immunophenotypic shift in a case of mycosis fungoides with vitreous invasion.

The case of an 82-year-old man who developed intraocular extension from mycosis fungoides, a cutaneous T-cell lymphoma, is presented. The patient died soon after intraocular involvement occurred. Immunohistochemistry of a skin biopsy, taken early in the course of the disease, disclosed a predominance of T cells with a helper/inducer phenotype (CD4(+)). However, an intraocular infiltrate obtained 7 years later contained mostly T cells with a suppressor/cytotoxic phenotype (CD8(+)). The occurrence of ocular invasion, the change in immunophenotype, and the predominant proliferation of CD8(+) lymphocytes may have been related to the poor outcome in this patient.

Aged↗
PubMed2000

A rapid spectrofluorimetric technique for determining drug-serum protein binding suitable for high-throughput screening.

PURPOSE: To develop and validate a rapid method for determining the dissociation constants with which pharmaceutical candidates and drugs bind to serum albumin and to alpha1-acid glycoprotein with the goal of deducing the extent of binding. METHODS: The quenching of the intrinsic tryptophan fluorescence of serum albumin and alpha1-acid glycoprotein was monitored by spectrofluorimetry and the data were used to calculate the apparent dissociation constant. Sodium warfarin was used to probe the warfarin-binding site of serum albumin and diazepam was used to probe the benzodiazepine binding site. Additionally, the binding of sodium salicylate, phenylbutazone, sulfinpyrazone, iophenoxic acid, theophylline, chloramphenicol, acetaminophen, lithium chloride and ampicillin were also investigated. Chlorpromazine hydrochloride and imipramine hydrochloride were used as probes for alpha1-acid glycoprotein. The assays were also extended to the multiwell format. The quenching curves were fitted to the quadratic binding equation to determine the dissociation constants. RESULTS: Intrinsic fluorescence measurements are an excellent predictor of the drug binding to human serum albumin and to alpha1-acid glycoprotein. These measurements detect binding to the warfarin and benzodiazepine binding sites of human serum albumin. The dissociation constants estimated using the method compare favorably to the dissociation constants previously reported by Epps et al. using extrinsic fluorescence methodology, and the results correlate well with equilibrium dialysis using drug displacement endpoints. CONCLUSIONS: These measurements can be carried out with small samples and do not require separation of the bound and unbound species. Additionally, the proposed methods eliminate membrane separations, are not compound specific and do not require analytical chromatography or mass spectrometry for quantitation. Spectrofluorimetry may prove to be a useful method for rapidly determining the protein binding of combinatorial libraries.

Anticoagulants↗
PubMed2000

Challenges in ophthalmic pathology: the vitreoretinal membrane biopsy.

The introduction of vitreoretinal microsurgery has produced a new type of biopsy; that of the vitreoretinal membrane. This review investigates methods by which these scar-like tissues are handled in the laboratory and explores the implications of the results of such evaluations. The study of vitreoretinal membrane biopsies has provided much information concerning the pathobiology of the various conditions which may give rise to the tissue as well as insights into how membranes themselves develop. Moreover, the application of new laboratory techniques is expected to enhance our understanding of the formation of vitreoretinal membranes, and lead to further advances in their surgical and medical management.

Biopsy↗
PubMed2000

The amino terminus of bacteriophage lambda integrase is involved in protein-protein interactions during recombination.

Bacteriophage lambda integrase (Int) catalyzes at least four site-specific recombination pathways between pairs of attachment (att) sites. Protein-protein contacts between monomers of Int are presumed to be important for these site-specific recombination events for several reasons: Int binds to the att sites cooperatively, catalytic Int mutants can complement each other for strand cleavage, and crystal structures for two other recombinases in the Int family (Cre from phage P1 and Int from Haemophilus influenzae phage HP1) show extensive protein-protein contacts between monomers. We have begun to investigate interactions between Int monomers by three approaches. First, using a genetic assay, we show that regions of protein-protein interactions occur throughout Int, including in the amino-terminal domain. This domain was previously thought to be important only for high-affinity protein-DNA interactions. Second, we have found that an amino-terminal His tag reduces cooperative binding to DNA. This disruption in cooperativity decreases the stable interaction of Int with core sites, where catalysis occurs. Third, using protein-protein cross-linking to investigate the multimerization of Int during recombination, we show that Int predominantly forms dimers, trimers, and tetramers. Moreover, we show that the cysteine at position 25 is present at or near the interface between monomers that is involved in the formation of dimers and tetramers. Our evidence indicates that the amino-terminal domain of Int is involved in protein-protein interactions that are likely to be important for recombination.

Attachment Sites, Microbiological↗
PubMed2000

Foveal relocation by redistribution of the neurosensory retina.

AIM: To describe a new surgical technique for foveal relocation, and to report the outcome in nine patients treated with this procedure. METHODS: Nine consecutive patients with subfoveal choroidal neovascular membranes (CNVMs) secondary to age related macular degeneration underwent foveal relocation surgery by redistribution of the neurosensory retina (RNR). The technique involved induction of a retinal detachment via a single retinotomy, relocation of the fovea by "sweeping" the retinal tissue with a retinal brush, and stabilisation of the retina in its new location using perfluorocarbon liquid peroperatively and silicone oil postoperatively. RESULTS: In eight of nine eyes successful relocation of the fovea was achieved; in one eye the CNVM remained in a subfoveal location postoperatively. Visual acuity improved in two eyes, remained unchanged in three, and decreased in four eyes after a median follow up of 4 months (range 2.5-6 months). Complications included rupture of a foveal cyst with the development of a macular hole in one eye and epimacular membrane formation in another eye. In two eyes, macular retinal vessel closure occurred at the time of laser photocoagulation; one of these eyes later developed cystoid macular oedema and the other an epiretinal membrane. Recurrence of the CNVM was observed in one eye, but was controlled with further laser treatment. CONCLUSIONS: Foveal relocation by RNR appears to be feasible, obviating the need for extensive retinotomies or scleral shortening.

Aged↗