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Biomedical subjects

E Ray

Publications and source records attributed to E Ray.

18 recordsLinked to original sources
PubMed2004

Monitoring Ceratomyxa shasta infection during a hatchery rearing cycle: comparison of molecular, serological and histological methods.

The prevalence of Ceratomyxa shasta infection in production stocks of steelhead Oncorhynchus mykiss and cutthroat trout O. clarki was monitored using a parasite-specific polymerase chain reaction (PCR) assay. For all 4 stocks of fish followed through their 1 yr rearing cycle, C. shasta infection was detected despite their genetic resistance to the disease and the treatment of the incoming water with ozone. Infection was confirmed using serological methods and standard histological procedures, except when prevalence was low (<10%). This suggests that at the lowest infection levels PCR is more sensitive than other methodologies, and can be used as an early indicator of infection. Results of the PCR assay continued to correlate with histological and serological detection as the numbers of parasites and the lesion severity increased over the rearing cycle. For both steelhead and cutthroat trout, early infections were characterized by large numbers of parasites on the epithelial surface, but with little associated inflammation. At release as yearlings, the infection prevalence in all stocks was greater than 90 % and the inflammatory response in many fish was extensive, with tissue necrosis and mucosal damage. Although C. shasta infections no longer result in high mortality at this facility, results of this study indicate that the parasite remains a contributor to low condition indices in these fish, despite their genetic resistance and ozone disinfection of the water supply.

Animals↗
PubMed2001

A second iron-regulatory system in yeast independent of Aft1p.

Iron homeostasis in the yeast Saccharomyces cerevisiae is regulated at the transcriptional level by Aft1p, which activates the expression of its target genes in response to low-iron conditions. The yeast genome contains a paralog of AFT1, which has been designated AFT2. To establish whether AFT1 and AFT2 have overlapping functions, a mutant containing a double aft1Deltaaft2Delta deletion was generated. Growth assays established that the single aft2Delta strain exhibited no iron-dependent phenotype. However, the double-mutant aft1Deltaaft2Delta strain was more sensitive to low-iron growth conditions than the single-mutant aft1Delta strain. A mutant allele of AFT2 (AFT2-1(up)), or overexpression of the wild-type AFT2 gene, led to partial complementation of the respiratory-deficient phenotype of the aft1Delta strain. The AFT2-1(up) allele also increased the uptake of (59)Fe in an aft1Delta strain. DNA microarrays were used to identify genes regulated by AFT2. Some of the AFT2-regulated genes are known to be regulated by Aft1p; however, AFT2-1(up)-dependent activation was independent of Aft1p. The kinetics of induction of two genes activated by the AFT2-1(up) allele are consistent with Aft2p acting as a direct transcriptional factor. Truncated forms of Aft1p and Aft2p bound to a DNA duplex containing the Aft1p binding site in vitro. The wild-type allele of AFT2 activated transcription in response to growth under low-iron conditions. Together, these data suggest that yeast has a second regulatory pathway for the iron regulon, with AFT1 and AFT2 playing partially redundant roles.

Alleles↗
PubMed2001

Haa1, a protein homologous to the copper-regulated transcription factor Ace1, is a novel transcriptional activator.

The Saccharomyces cerevisiae genome contains a predicted gene, YPR008w, homologous to the gene encoding the copper-activated transcription factor Ace1. The product of the YPR008w gene, designated Haa1, regulates the transcription of a set of yeast genes, many of which encode membrane proteins. Two main target genes of Haa1 are the multidrug resistance gene YGR138c and the YRO2 homolog to the plasma membrane Hsp30. Haa1 is localized to the nucleus. Haa1-induced expression of YGR138c and YRO2 appears to be direct. Induction of HAA1 using a GAL1/HAA1 fusion gene resulted in rapid galactose-induced expression of both HAA1 and target genes. Although Haa1 has a sequence very similar to the Cu-activated DNA binding domain of Ace1, expression of Haa1 target genes was found to be independent of the copper status of cells. Haa1 does not exhibit metalloregulation in cells incubated with a range of transition metal salts. Haa1 does not exhibit any cross-talk with Ace1. Overexpression of Haa1 does not compensate for cells lacking a functional Ace1. The lack of metalloregulation of Haa1 despite the strong sequence similarity to the copper regulatory domain of Ace1 is discussed.

Amino Acid Sequence↗
PubMed2000

Frequency of cytochrome P450 3A4 variant genotype in transplant population and lack of association with cyclosporin clearance.

OBJECTIVE: Cytochrome P450 3A4 (CYP3A4) plays a vital role in the oxidative metabolism of many xenobiotics. Some recent reports have provided circumstantial evidence in support of an association between a genetic polymorphism (A-->G) in the 5'-flanking region (-290) of CYP3A4 and altered enzyme activity. We sought to determine whether genotyping patients for CYP3A4-G could assist with the dose optimisation of drugs metabolised by this system. METHODS: Normal subjects and renal-transplant patients receiving cyclosporin for immune modulation were genotyped for the CYP3A4-G variant. A surrogate for cyclosporin clearance was estimated from the ratio of the cyclosporin dose, normalised for body weight and the corresponding trough concentration. The association between genotype and clearance was examined in patients who received twice-daily doses of cyclosporin and who were not on concurrent medication known to modify CYP3A4 function. RESULTS: The allelic frequencies of the CYP3A4-G variant were estimated to be 2.6% and 3% in transplant patients and normal subjects, respectively. The median cyclosporin pseudo-clearance of transplant patients with wild-type CYP3A4 was 0.90 l/h/kg (range: 0.35-3.8 l/h/kg; n = 86), whereas the corresponding value for the five patients heterozygotic for the CYP3A4-G variant was 0.71 l/h/kg (range 0.35-0.91 l/h/kg). The distribution of the pseudo-clearance according to genotype was not found to be significant according to a Fisher's exact test (P = 0.15). CONCLUSION: Genotyping for the CYP3A4-G polymorphism is unlikely to assist cyclosporin dose selection in transplant patients.

Adolescent↗
PubMed1997

Receptor-mediated endocytosis of IL-8: a fluorescent microscopic evidence and implication of the process in ligand-induced biological response in human neutrophils.

Interleukin 8 (IL-8), a neurophil-activating and chemotactic cytokine, is known to play a key role in the pathogenesis of a large number of neutrophil-driven inflammatory diseases. Although the cytokine is rapidly internalized at 37 degrees C with its receptors, there was no direct evidence for the ligand-induced endocytosis of the receptor or that of the interaction of receptor ligand complex at 37 degrees C. As a result, our understanding about the regulation of Il-8 induced biological response is very limited. In the present study, using FITC-IL-8 conjugate as a probe, we have demonstrated the time- and temperature-dependent endocytosis of IL-8 under fluorescent microscope. We have also shown that the bright fluorescent light on the surface of neutrophils gradually disappears and it becomes almost dark after 120 min of incubation. Monodansyl cadaverine (MDC, 900 microM), however, was found to retain the fluorescent light of FITC coupled with Il-8 on the cells. MDC and ouabain (2.5 mM) can inhibit the ligand induced endocytosis by 76% and 96%, respectively, compared to control. With respect to control, IL-8 induced biological responses e.g. IL-8 directed migration, intracellular Ca2+ release and superoxide release are significantly reduced by 77%, 94% and 76%, respectively, in presence of MDC. The study presents a direct visual evidence of the time and temperature-dependent receptor-mediated endocytosis of IL-8 which is inhibited by MDC and ouabain. This information is useful for understanding the ligand receptor interaction at 37 degrees C and may be useful for developing anti-inflammatory agents against IL-8.

Anions↗
PubMed1997

SET1, a yeast member of the trithorax family, functions in transcriptional silencing and diverse cellular processes.

The trithorax gene family contains members implicated in the control of transcription, development, chromosome structure, and human leukemia. A feature shared by some family members, and by other proteins that function in chromatin-mediated transcriptional regulation, is the presence of a 130- to 140-amino acid motif dubbed the SET or Tromo domain. Here we present analysis of SET1, a yeast member of the trithorax gene family that was identified by sequence inspection to encode a 1080-amino acid protein with a C-terminal SET domain. In addition to its SET domain, which is 40-50% identical to those previously characterized, SET1 also shares dispersed but significant similarity to Drosophila and human trithorax homologues. To understand SET1 function(s), we created a null mutant. Mutant strains, although viable, are defective in transcriptional silencing of the silent mating-type loci and telomeres. The telomeric silencing defect is rescued not only by full-length episomal SET1 but also by the conserved SET domain of SET1. set1 mutant strains display other phenotypes including morphological abnormalities, stationary phase defects, and growth and sporulation defects. Candidate genes that may interact with SET1 include those with functions in transcription, growth, and cell cycle control. These data suggest that yeast SET1, like its SET domain counterparts in other organisms, functions in diverse biological processes including transcription and chromatin structure.

Amino Acid Sequence↗
PubMed1996

Linker histones inhibit T4 and Escherichia coli DNA ligases.

Based on some preliminary observations that linker histones strongly inhibit the activity of prokaryotic DNA ligases, we studied the effect of these histones on the ligation of short restriction DNA fragments by either T4 or E. coli DNA ligases. The inhibitory effect was strong, but it appeared only after two molecules of H1 bound to a approximately 200 bp-long DNA fragment. A similar pattern of inhibition (but at much higher concentration) was observed with the isolated globular domain of histone H5. That the inhibition was specific to the linker histones became clear when other basic proteins, such as the core histone octamer or cytochrome C, were tested. They did not inhibit the ligases but rather significantly stimulated them. The other major linker DNA-binding protein in chromatin, the non-histone protein HMG1, showed no significant effect on the ligase activity.

Animals↗
PubMed1996

Dansyl cadaverine regulates ligand induced endocytosis of interleukin-8 receptor in human polymorphonuclear neutrophils.

Interleukin-8 (IL-8), a neutrophil chemotactic agent, acts as a key mediator in a large number of acute and chronic inflammatory diseases. At 37 degrees C, the receptor for IL-8 is rapidly internalized with its ligand. But no specific inhibitor of this ligand induced internalization of the receptor has been reported so far. We have found that monodansyl cadaverine (MDC) inhibited about 70% of IL-8 induced endocytosis and caused 70% and 66% inhibition of IL-8 mediated chemotaxis and respiratory burst response, respectively, in neutrophils. The uninternalized receptor was detected by anti IL-8R antibody in MDC treated cells. The endocytosis of IL-8R was strongly inhibited under Ca2+ depleted conditions which was restored on addition of 1 mM CaCl2 indicating the critical involvement of a Ca2+ ion in the process. Absence of receptor internalisation makes the MDC treated neutrophils suitable for studying the interaction of IL-8R with potential therapeutic agents e.g. for in vitro screening of anti-inflammatory agents.

Antigens, CD↗
PubMed1994

Diffusion and relaxation mapping of cartilage-bone plugs and excised disks using microscopic magnetic resonance imaging.

Spatially resolved maps of proton self-diffusion coefficients (D) and relaxation times (T1 and T2) were obtained on cartilage-bone plug samples and on excised disks of canine cartilage at a transverse resolution of 30 microns, using microscopic magnetic resonance imaging (micro-MRI). Results are compared for excised disks of cartilage and intact cartilage-bone plugs. Correlations between the absolute water concentration, the self-diffusion coefficient and the T1 relaxation are reported. The diffusion coefficient is not a linear function of water concentration. The thickness of the disks is 600 microns, compared with the ca. 900 microns observed for the cartilage-bone plugs, presumably due to the absence of the interfacial or tidemark layer of interdigitated cartilage and bone in the former samples. Our results suggest that excised disks of cartilage are excellent models for the articular surface and the first 500 or so microns of tissue. The molecular parameters of spin-spin and spin-lattice relaxation times, as well as the water self-diffusion coefficient, are virtually identical in the two types of samples. However, the cartilage-bone plugs have the additional feature of permitting the study of the tidemark region, a region that likely plays a major role in the transmission of mechanical force.

Animals↗
PubMed1994

[African histoplasmosis: clinical and therapeutic aspects, relation to AIDS. Apropos of 4 cases, including a case with HIV-1-HTLV-1 co-infection].

The authors report 4 cases of African histoplasmosis in Zaïrans. The diagnostic was based ou cutaneous (4 patients), bones (3), lymph-nodes (2), and bowel-localizations (1) and was confirmed by the presence of Histoplasma duboisiis yeasts in cutaneous biopsy (4 patients), in pus of abscess or cutaneous lesions (3) and in stools (1). Two HIV seronegatives patients had a good outcome with amphotericin B. One patient died without any treatment. One HIV-1 and HTLV-1 seropositive patient had successful short-term outcome with ketoconazole. Seven others cases of association between African histoplasmosis and AIDS are noted in the literature. They suggest the opportunistic nature of this deep mycosis.

AIDS-Related Opportunistic Infections↗
PubMed1993

Acquired equivalence between cues trained with a common antecedent.

In Experiment 1, rats experienced 2 stimuli (A and N) each preceded by the same event (food) or by different events (food preceded 1 but not the other). N was then paired with shock, and the generalization of conditioned suppression to A was assessed. Generalization was more marked when A and N had been experienced along with a common antecedent. In Experiment 2, 3 stimuli (A, B, and N) were presented in initial training. For 1 group, A and N were preceded by food and B was not; for a 2nd group A alone was preceded by food. In each group, suppression generalized more readily from N to the stimulus that had received the same initial training as had been given to N. Experiment 3 found that generalization was not enhanced between stimuli when 1 had preceded food in initial training and 1 had followed it. These results demonstrate that stimuli that have shared a common antecedent will come to be treated as equivalent.

Animals↗
PubMed1987

Diagnostic criteria and efficient use of outpatient cultures.

The authors conducted an eight-year longitudinal study to evaluate the effect of diagnostic criteria on efficient use of outpatient cultures. Efficiency was determined by monitoring alterations in culture use, yield (percent positive), and charges for four common ambulatory diseases: Group A streptoccocal pharyngitis; gonococcal urethritis and cervicitis; bacterial cystourethritis; and acute enterocolitis.The study demonstrated that the use of diagnostic criteria resulted in more efficient use of laboratory tests as reflected in the immediate and sustained decrease in culture use and associated charges, an increase in yield (percent positive), and a corresponding decrease in charge per test.

Ambulatory Care Facilities↗
PubMed1980

Influence of lecithin:cholesterol acyltransferase on cholesterol metabolism in hepatoma cells and hepatocytes.

Cholesterol content and synthesis were measured in rabbit hepatocytes and rat hepatoma cells (Fu5AH) incubated in rabbit serum at concentrations ranging from 2.5% to 50%. Values were compared to controls grown in delipidized serum protein. Cellular cholesterol content varied inversely with the serum concentration, whereas cholesterol synthesis was elevated as serum concentration in the incubation medium was raised. The reduction in cellular cholesterol content and the elevation in synthesis observed with the cells incubated in high concentrations of fresh serum could be correlated with the extent of serum lipoprotein modification by lecithin:cholesterol acyltransferase. Unmodified serum in which LCAT had been inactivated depressed cholesterol synthesis and increased cellular cholesterol content at all concentrations. The presence of active LCAT was not required for the cellular responses, since serum which had been modified before LCAT inactivation also stimulated cholesterol synthesis and decreased content. Qualitatively similar results were obtained with human, rat and rabbit sera. Fractionation of serum demonstrated that the stimulatory activity of LCAT-modified serum was associated primarily with the high-density lipoprotein fraction. Comparative cholesterol flux studies using prelabeled hepatoma cells exposed to either normal or modified high-density lipoproteins demonstrated that cellular cholesterol efflux was somewhat depressed in the presence of the modified lipoprotein whereas cholesterol influx was markedly reduced. These data indicate that LCAT modification of serum lipoproteins alters the relative rates of cholesterol flux with the major effect being on cholesterol uptake. This results in a net loss of cholesterol from the cells accompanied by a stimulation of cholesterol synthesis.

Acetates↗
PubMedDate not supplied

Fluorescence diagnosis of bladder cancer.

Standard management of newly presenting superficial bladder tumours is to remove the tumour endoscopically and to administer a single dose of a chemotherapeutic agent into the bladder postoperatively. However, between 20-40% of patients will develop a tumour in the bladder again within 12 months (Herr, 1997). There is controversy about whether these tumours are genuine recurrences or previously undetected tumours. Photodynamic diagnosis is currently the subject of clinical trials for detection and surveillance of bladder cancer. A solution is administered into the bladder preoperatively which is absorbed by the cancer cells. These areas within the bladder then fluoresce under blue light, aiding the surgeon to detect tumours that may not have been visible to the naked eye. The authors present a review of this developing technique and their early experiences of photodynamic diagnosis in clinical trials which appear to be clinically relevant in decreasing recurrent bladder tumours.

Aminolevulinic Acid↗