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Biomedical subjects

A Ray

Publications and source records attributed to A Ray.

At least 19 recordsLinked to original sources
PubMed2000

Melanocortin-1-receptor gene and sun sensitivity in individuals without red hair.

Susceptibility to sunburn, photoageing, and skin cancer is inversely related to an individual's ability to tan after sun exposure. We examined variants in the melanocortin-1-receptor (MC1R) gene in individuals from Ireland and the UK. We found evidence of an association between the degree of tanning after repeated sun exposure, and the number of variant alleles present. Heterozygotes were intermediate between wild-type individuals and those with two variant alleles. We suggest that MC1R gene status therefore determines sun sensitivity in people without red hair.

Adult↗
PubMed2000

Dominance of IL-12 over IL-4 in gamma delta T cell differentiation leads to default production of IFN-gamma: failure to down-regulate IL-12 receptor beta 2-chain expression.

Gamma delta T cells secrete Th1- and Th2-like cytokines that help mediate innate and acquired immunity. We have addressed the mechanism whereby murine gamma delta T cells acquire the capacity to differentially produce such cytokines. Splenic gamma delta T cells could be polarized into IFN-gamma- or IL-4-secreting cells in vitro; however, in contrast to CD4+ alpha beta T cells, gamma delta T cells predominantly produced IFN-gamma, even in the presence of IL-4, a finding independent of genetic background. Like CD4+ Th1 cells, IFN-gamma-producing cells expressed the IL-12 receptor beta 2-chain after activation in the presence of IL-12; however, unlike Th2 cells, IL-4-primed gamma delta T cells also expressed this receptor, even in the absence of IFN-gamma and despite the presence of the transcription factor GATA-3. IL-12 also induced IL-4-primed gamma delta T cells to proliferate and to translocate Stat3/Stat4, indicating signaling through the IL-12 receptor. These molecular events can account for the predominant production of IFN-gamma by gamma delta T cells in the presence of IL-12, despite the availability of IL-4. Early and predominant production of IFN-gamma by gamma delta T cells likely is critical for the roles that these cells play in protection against intracellular pathogens and in tumor immunity.

Animals↗
PubMed2000

Characterization of the extracellular polysaccharide produced by a marine cyanobacterium, Cyanothece sp. ATCC 51142, and its exploitation toward metal removal from solutions.

Cyanobacterium, Cyanothece sp. ATCC 51142 produces an exopolysaccharide at a high level. Physical analysis of the exopolysaccharide (EPS), such as nuclear magnetic resonance, infrared spectrum, were done to determine its possible structure. Thermal gravimetric analysis, differential scanning calorimeter, and differential thermal analysis of the polymer were done to find out the thermal behavior. Calcium content within the sample was found out. Some of the physicochemical properties, such as relative viscosity, specific viscosity, and intrinsic viscosity of the EPS were studied under different conditions. The phenomenon of gel formation by the EPS was investigated for its potential application in metal removal from solutions.

Calcium↗
PubMed2000

Upregulation of the transcription factor GATA-3 in upper airway mucosa after in vivo and in vitro allergen challenge.

BACKGROUND: Allergic rhinitis is a complex upper airways disorder characterized by the infiltration of eosinophils and T(H2)-type T lymphocytes. GATA-3 is a novel transcription factor recently shown to regulate IL-5 and, possibly, IL-4 gene expression. We previously reported that GATA-3 is increased within the bronchial mucosa of allergic asthmatic subjects compared with control subjects. OBJECTIVE: In the present study we set out to determine whether there is also an increased number of cells expressing GATA-3 messenger (m)RNA within the nasal mucosa of patients with allergic rhinitis. METHODS: Inferior turbinate biopsy specimens were obtained from patients with allergic rhinitis and nonatopic control subjects before and after local allergen provocation in vivo. To assess the contribution of resident cells expressing GATA-3 mRNA, we also performed isolated explant studies in which nasal mucosal tissue from subjects with allergic rhinitis and nonatopic control subjects was cultured in allergen-treated medium. The presence of mRNA coding for GATA-3, IL-5, IL-4, IL-13, and GM-CSF was assessed by using in situ hybridization. RESULTS: The number of GATA-3 mRNA(+) cells was increased after local allergen provocation in vivo (increase in GATA-3 mRNA(+) cells [mean +/- SEM]: subjects with allergic rhinitis, 11.3 +/- 8.7; control subjects, 1.2 +/- 4.1; P <.05) and in explanted nasal mucosa in vitro (subjects with allergic rhinitis, 10. 2 +/- 3.8; control subjects, 2.7 +/- 4.4; P <.05). The gene expression of GATA-3 was significantly correlated to the numbers of IL-5 (r = 0.87) and GM-CSF (r = 0.79) mRNA(+) cells but not with IL-4 or IL-13 mRNA(+) cells. CONCLUSION: In summary, the expression of the transcription factor GATA-3 was increased after allergen challenge, and this was evident in the absence of de novo inflammatory cell recruitment. GATA-3 may be a potential target in the treatment of allergic diseases, such as rhinitis.

Allergens↗
PubMed2000

Enterogenous cyst of the posterior fossa.

We report the case of a 13-year-old boy who presented with deafness due to a posterior fossa cystic lesion which was surgically excised. Histological examination showed it to be an enterogenous cyst. These extremely rare lesions seldom occur within the neural axis.

Adolescent↗
PubMed2000

Peptide nucleic acid (PNA): its medical and biotechnical applications and promise for the future.

Synthetic molecules that can bind with high sequence specificity to a chosen target in a gene sequence are of major interest in medicinal and biotechnological contexts. They show promise for the development of gene therapeutic agents, diagnostic devices for genetic analysis, and as molecular tools for nucleic acid manipulations. Peptide nucleic acid (PNA) is a nucleic acid analog in which the sugar phosphate backbone of natural nucleic acid has been replaced by a synthetic peptide backbone usually formed from N-(2-amino-ethyl)-glycine units, resulting in an achiral and uncharged mimic. It is chemically stable and resistant to hydrolytic (enzymatic) cleavage and thus not expected to be degraded inside a living cell. PNA is capable of sequence-specific recognition of DNA and RNA obeying the Watson-Crick hydrogen bonding scheme, and the hybrid complexes exhibit extraordinary thermal stability and unique ionic strength effects. It may also recognize duplex homopurine sequences of DNA to which it binds by strand invasion, forming a stable PNA-DNA-PNA triplex with a looped-out DNA strand. Since its discovery, PNA has attracted major attention at the interface of chemistry and biology because of its interesting chemical, physical, and biological properties and its potential to act as an active component for diagnostic as well as pharmaceutical applications. In vitro studies indicate that PNA could inhibit both transcription and translation of genes to which it has been targeted, which holds promise for its use for antigene and antisense therapy. However, as with other high molecular mass drugs, the delivery of PNA, involving passage through the cell membrane, appears to be a general problem.

Animals↗
PubMed1999

Varying the number of telomere-bound proteins does not alter telomere length in tel1Delta cells.

Yeast telomere DNA consists of a continuous, approximately 330-bp tract of the heterogeneous repeat TG(1-3) with irregularly spaced, high affinity sites for the protein Rap1p. Yeast monitor, or count, the number of telomeric Rap1p C termini in a negative feedback mechanism to modulate the length of the terminal TG(1-3) repeats, and synthetic telomeres that tether Rap1p molecules adjacent to the TG(1-3) tract cause wild-type cells to maintain a shorter TG(1-3) tract. To identify trans-acting proteins required to count Rap1p molecules, these same synthetic telomeres were placed in two short telomere mutants: yku70Delta (which lack the yeast Ku70 protein) and tel1Delta (which lack the yeast ortholog of ATM). Although both mutants maintain telomeres with approximately 100 bp of TG(1-3), only yku70Delta cells maintained shorter TG(1-3) repeats in response to internal Rap1p molecules. This distinct response to internal Rap1p molecules was not caused by a variation in Rap1p site density in the TG(1-3) repeats as sequencing of tel1Delta and yku70Delta telomeres showed that both strains have only five to six Rap1p sites per 100-bp telomere. In addition, the tel1Delta short telomere phenotype was epistatic to the unregulated telomere length caused by deletion of the Rap1p C-terminal domain. Thus, the length of the TG(1-3) repeats in tel1Delta cells was independent of the number of the Rap1p C termini at the telomere. These data indicate that tel1Delta cells use an alternative mechanism to regulate telomere length that is distinct from monitoring the number of telomere binding proteins.

Binding Sites↗
PubMed1999

Persistent expression of serum amyloid A during experimentally induced chronic inflammatory condition in rabbit involves differential activation of SAF, NF-kappa B, and C/EBP transcription factors.

The serum amyloid A (SAA) protein has been implicated in the pathogenesis of several chronic inflammatory diseases. Its induction mechanism in response to a chronic inflammatory condition was investigated in rabbits following multiple s.c. injections of AgNO3 over a period of 35 days. During unremitting exposure to inflammatory stimulus, a persistently higher than normal level of SAA2 expression was seen in multiple tissues. Induction of SAA was correlated with higher levels of several transcription factor activities. Increased SAA-activating factor (SAF) activity was detected in the liver, lung, and brain tissues under both acute and chronic inflammatory conditions. In the heart, kidney, and skeletal muscle tissues, this activity remained virtually constant. In contrast, CCAAT enhancer binding protein (C/EBP) DNA-binding activity was transiently induced in selective tissues. Higher than normal NF-kappa B DNA-binding activity was detected in the lung and to a lesser extent in the liver and kidney tissues under both acute and chronic conditions. This result suggested that C/EBP, SAF, and NF-kappa B are required for transient acute phase induction of SAA whereas SAF and NF-kappa B activities are necessary for persistent SAA expression during chronic inflammatory conditions.

Acute Disease↗
PubMed1999

Spectroscopic studies on the interaction of aristololactam-beta-D-glucoside with DNA and RNA double and triple helices: A comparative study.

The interaction of aristololactam-beta-D-glucoside (ADG), a DNA intercalating alkaloid, with the DNA triplexes, poly(dT). poly(dA)xpoly(dT) and poly(dC).poly(dG)xpoly(dC+), and the RNA triplex poly(rU).poly(rA)xpoly(rU) was investigated by circular dichroic, UV melting profile, spectrophotometric, and spectrofluorimetric techniques. Comparative interaction with the corresponding Watson-Crick duplexes has also been examined under identical experimental conditions. Triplex formation has been confirmed from biphasic thermal melting profiles and analysis of temperature-dependent circular dichroic measurements. The binding of ADG to triplexes and duplexes is characterized by the typical hypochromic and bathochromic effects in the absorption spectrum, quenching of steady-state fluorescence intensity, a decrease in fluorescence quantum yield, an increase or decrease of thermal melting temperatures, and perturbation in the circular dichroic spectrum. Scatchard analysis indicates that ADG binds both to the triplexes and the duplexes in a noncooperative manner. Binding parameters obtained from spectrophotometric measurements are best fit by the neighbor exclusion model. The binding affinity of ADG to the DNA triplexes is substantially stronger than to the RNA triplex. Thermal melting study further indicates that ADG stabilizes the Hoogsteen base-paired third strand of the DNA triplexes whereas it destabilizes the same strand of RNA triplex but stabilizes its Watson-Crick strands. Comparative data reveal that ADG exhibits a stronger binding to the triple helical structures than to the respective double helical structures.

Alkaloids↗
PubMed1999

Activation of Sp1 and its functional co-operation with serum amyloid A-activating sequence binding factor in synoviocyte cells trigger synergistic action of interleukin-1 and interleukin-6 in serum amyloid A gene expression.

The serum amyloid A (SAA) protein has been implicated in the progression and pathogenesis of rheumatoid arthritis through induction of collagenase activity in synovial fibroblast cells that line the joint tissues. We demonstrate that SAA is synergistically induced in synovial cells by interleukin (IL)-1 and IL-6 that are present at significantly high level in the synovial fluid of arthritis patients. These cytokines induced phenotypic changes in synovial cells, promoting protrusion and increased cellular contact. Induction of SAA under this condition is mediated by promoter elements located between -254 and -226, which contains binding sites for transcription factors Sp1 and SAA activating sequence binding factor (SAF). Mutation of these sequences abolishes SAA promoter response to IL-1 and IL-6. The role of Sp1 in SAA induction was demonstrated by increased DNA binding activity, phosphorylation, and increased protein content of Sp1 during cytokine treatment. Sp1 interacts with the SAA promoter in association with SAF as an SAF. Sp1 heteromeric complex. Furthermore, using a phosphatase inhibitor, we demonstrated increased transactivation potential of both Sp1 and SAF as a consequence of a phosphorylation event. These results provide first evidence for cytokine-mediated activation of Sp1 in synovial fibroblast cells and its participation in regulating SAA expression by acting in conjunction with SAF.

Animals↗
PubMed1999

Gene expression of the GATA-3 transcription factor is increased in atopic asthma.

BACKGROUND: High expression of IL-5 by T cells in the airways of asthmatic individuals is believed to play a fundamental role in the eosinophilia associated with this disease. Recently, the transcription factor GATA-3 was shown to be critical for IL-5 gene expression in TH2 cells in vitro. OBJECTIVE: Our aim was to examine the expression of GATA-3 mRNA and its colocalization within the airways of asthmatic and nonasthmatic individuals. METHODS: We investigated the association between GATA-3 gene expression, airway inflammatory cells, and IL-5 gene expression in bronchoalveolar lavage fluid and bronchial biopsy specimens from atopic asthmatic subjects (n = 10) and normal control subjects (n = 10). RESULTS: We report that GATA-3 mRNA expression is significantly increased in the airways of asthmatic subjects compared with those of normal control subjects (P <.001). Numbers of cells expressing GATA-3 transcripts correlated significantly with reduced airway caliber (P <.05) and airways hyperresponsiveness (P <.05) in asthmatic subjects. Colocalization studies showed that the majority (approximately 60% to 90%) of GATA-3 mRNA+ cells in asthmatic airways were CD3(+) T cells, with smaller contributions from major basic protein+ eosinophils and tryptase+ mast cells. The density of GATA-3 mRNA+ cells correlated significantly with the numbers of cells expressing IL-5 mRNA (P <.001, r = 0.879 for bronchoalveolar lavage fluid; P <. 05, r = 0.721 for biopsy specimens). Furthermore, double in situ hybridization demonstrated that approximately 76% of GATA-3 mRNA+ cells coexpressed IL-5 mRNA and that 91% of IL-5 mRNA+ cells coexpressed GATA-3 mRNA. CONCLUSION: The results of this study provide the first evidence of increased GATA-3 gene expression in association with IL-5 mRNA+ cells in asthmatic airways. These findings support a causal association between augmented GATA-3 expression and dysregulated IL-5 expression in atopic asthma.

Adult↗
PubMed1999

Inhibition of allergic inflammation in a murine model of asthma by expression of a dominant-negative mutant of GATA-3.

The cytokines IL-4, IL-5, and IL-13, secreted by Th2 cells, have distinct functions in the pathogenesis of asthma. We have previously shown that the transcription factor GATA-3 is expressed in Th2 but not Th1 cells. However, it was unclear whether GATA-3 controls the expression of all Th2 cytokines. Expression of a dominant-negative mutant of GATA-3 in mice in a T cell-specific fashion led to a reduction in the levels of all the Th2 cytokines IL-4, IL-5, and IL-13. Airway eosinophilia, mucus production, and IgE synthesis, all key features of asthma, were severely attenuated in the transgenic mice. Thus, targeting GATA-3 activity alone is sufficient to blunt Th2 responses in vivo, thereby establishing GATA-3 as a potential therapeutic target in the treatment of asthma and allergic diseases.

Aerosols↗
PubMed1999

Mechanism of minimally modified LDL-mediated induction of serum amyloid A gene in monocyte/macrophage cells.

Minimally modified low-density lipoprotein (MM-LDL) is regarded as a major risk factor for the development of atherosclerosis. In this report, we show that this lipoprotein complex can induce expression of an inflammatory protein, serum amyloid A (SAA), in monocyte/macrophage cells, a key cell type implicated in the pathogenesis of atherosclerosis. By promoter function analysis and site-directed mutagenesis, we have located promoter regions responsive to MM-LDL action. Using electrophoretic mobility shift, antibody ablation/supershift, and Western blot assays, we showed that induction of SAA by MM-LDL is mediated via activation of SAS binding factor (SAF) and C/EBP transcription factors. We further show that tamoxifen, a downregulator of CD36, one of the major scavenger receptors which binds MM-LDL, can inhibit MM-LDL-mediated SAA induction in THP-1 cells. This finding suggests that CD36 participates in the manifestation of the inflammatory effects of MM-LDL. Our experiments provide the first evidence for transcription factor activation by MM-LDL.

Blotting, Northern↗
PubMed1999

The yeast telomere length counting machinery is sensitive to sequences at the telomere-nontelomere junction.

Saccharomyces cerevisiae telomeres consist of a continuous 325 +/- 75-bp tract of the heterogeneous repeat TG1-3 which contains irregularly spaced, high-affinity sites for the protein Rap1p. Yeast cells monitor or count the number of telomeric Rap1p molecules in a negative feedback mechanism which modulates telomere length. To investigate the mechanism by which Rap1p molecules are counted, the continuous telomeric TG1-3 sequences were divided into internal TG1-3 sequences and a terminal tract separated by nontelomeric spacers of different lengths. While all of the internal sequences were counted as part of the terminal tract across a 38-bp spacer, a 138-bp disruption completely prevented the internal TG1-3 sequences from being considered part of the telomere and defined the terminal tract as a discrete entity separate from the subtelomeric sequences. We also used regularly spaced arrays of six Rap1p sites internal to the terminal TG1-3 repeats to show that each Rap1p molecule was counted as about 19 bp of TG1-3 in vivo and that cells could count Rap1p molecules with different spacings between tandem sites. As previous in vitro experiments had shown that telomeric Rap1p sites occur about once every 18 bp, all Rap1p molecules at the junction of telomeric and nontelomeric chromatin (the telomere-nontelomere junction) must participate in telomere length measurement. The conserved arrangement of these six Rap1p molecules at the telomere-nontelomere junction in independent transformants also caused the elongated TG1-3 tracts to be maintained at nearly identical lengths, showing that sequences at the telomere-nontelomere junction had an effect on length regulation. These results can be explained by a model in which telomeres beyond a threshold length form a folded structure that links the chromosome terminus to the telomere-nontelomere junction and prevents telomere elongation.

Base Sequence↗
PubMed1999

HSV-1 migration in latently infected and naive rabbits after penetrating keratoplasty.

PURPOSE: To investigate the migration of herpes simplex virus type 1 (HSV-1) between latently infected and naive corneal tissues and trigeminal ganglion (TG) in rabbits after penetrating keratoplasty (PKP) and transcorneal epinephrine iontophoresis. METHODS: Two mutants, genetically constructed from HSV-1 strain 17syn+, were used to inoculate rabbit corneas: 17deltaPst, a latency associated transcript (LAT) negative, low-reactivating virus and 17Pr, a high-reactivating, LAT-positive rescuant of 17deltaPst. Latently infected rabbits were given corneal allografts from naive rabbits, and naive rabbits received grafts from latently infected rabbits. Ninety days after PKP, groups of the transplanted rabbits were induced to reactivate by transcorneal epinephrine iontophoresis, but others were not induced. Viral shedding was monitored by tear film cultures. Rabbits were killed 5 days after iontophoresis. Transplanted grafts, recipient corneal rims, and corresponding TG were obtained. Nucleic acids were extracted and amplified for detection of HSV-1 DNA and viral gene transcription. RESULTS: In naive rabbits receiving grafts transplanted from rabbits latently infected with 17Pr (LAT+), 3 of 6 corneal rims contained HSV DNA after induction. In contrast, none of the 5 corneal rims from naive rabbits receiving grafts from rabbits latent with 17deltaPst (LAT-) contained viral DNA. Viral DNA and gene transcripts were detected in 2 of 6 TG from naive rabbits that received grafts from 17Pr (LAT+) latently infected rabbits. In recipient corneal rims and TG of latently infected rabbits receiving grafts from naive rabbits, viral DNA concentration was significantly greater with induced reactivation, compared with the results in noninduced rabbits. The amount of viral DNA in naive grafts transplanted into 17Pr (LAT+) latently infected rabbits was significantly higher with induction than without induction (P = 0.018). More viral DNA and viral gene transcripts were found in tissues from rabbits latently infected with 17Pr (LAT+) than in rabbits latently infected with 17deltaPst (LAT-). CONCLUSIONS: Corneas from latently infected rabbits contain HSV-1 DNA that can replicate after induced reactivation. Viral migration can occur in both anterograde and retrograde directions between the transplanted graft and the recipient corneal rim and TG. The LAT negative HSV-1 construct 17deltaPst has a significantly reduced ability to replicate and migrate.

Animals↗