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Biomedical subjects

D E Lewis

Publications and source records attributed to D E Lewis.

At least 73 records · Page 4Linked to original sources
PubMed1995

HIV-1 and HHV-6 antigens and transcripts in retinas of patients with AIDS in the absence of human cytomegalovirus.

PURPOSE: The purpose of this study was to define the agents involved in the development of acquired immune deficiency syndrome (AIDS)-associated retinitis. To achieve this goal, the authors determined the frequency and proximity of the simultaneous presence of human immunodeficiency virus (HIV)-1, human herpesvirus (HHV)-6, and human cytomegalovirus (HCMV) in retinas of patients with AIDS with and without AIDS-associated retinitis. METHODS: Retinal sections from 50 globes from patients with AIDS were analyzed for the presence of viral antigens and transcripts. Group 1 contained 13 globes from patients with HCMV infection. Group 2 contained 20 globes from patients with retinal lesions of uncertain etiology in which HCMV antigen and transcripts were not detected. Group 3 contained 17 globes from patients with no retinal lesions. RESULTS: Retinal sections from all 13 globes (group 1) were positive for HCMV antigens and HIV-1 antigens and transcripts. Six of the 13 retinas were also positive for HHV-6 antigens and transcripts. Sections from 13 of the 20 globes (group 2) were positive for HIV-1 antigens and transcripts, and 5 of these 13 were also positive for HHV-6 antigens and transcripts. Multiple areas in sections from two of the HIV-1-positive retinas showed coinfection with HHV-6. All 17 globes (group 3) were positive for HIV-1 antigens and transcripts. Ten of these 17 retinas were also positive for HHV-6 antigens. Human cytomegalovirus antigens were not detectable in retinas from groups 2 and 3. No viral antigens or transcripts were detectable in retinal sections from 10 HIV-1 negative donors. CONCLUSION: The coexistence of HIV-1 and HHV-6 activity in more than 50% of retinas without HCMV infection suggests that HIV-1 and HHV-6 alone or in combination may predispose retinal tissue to other opportunistic agents such as HCMV during the development of AIDS-associated retinitis.

AIDS-Related Opportunistic Infections↗
PubMed1994

Anergy and apoptosis in CD8+ T cells from HIV-infected persons.

CD8+T cells from HIV-infected persons increase early in infection, display increased levels of activation Ags, and abnormal MHC-restricted, HIV-specific and nonspecific cytotoxicity abilities. Paradoxically, these cells are also unresponsive to T cell signaling in vitro and have decreased in vitro cloning potential. HIV-specific CTL precursors also are lost late in infection. A quantitative Southern blotting technique showed that CD8+ T cells from asymptomatic, HIV-infected persons have increased DNA fragmentation after overnight incubation. DNA fragmentation was reduced by an endonuclease inhibitor but not by cycloheximide, suggesting that a pre-apoptotic state exists in vivo. Partial inhibition of DNA fragmentation also could be induced by IL-2 addition. No consistent difference in fragmentation was observed among CD8+ subpopulations from HIV-infected individuals, although only CD8+ T cells that did not express activation Ags (DR-, CD28+, CD57- phenotype) showed reduced fragmentation when incubated in IL-2. A dramatic increase in CD8+, CD28- cells was observed in asymptomatic HIV-infected people. A subset of CD8+, CD28- cells in both controls and HIV-infected people do not proliferate to T cell signals, and these cells from controls demonstrate increased DNA fragmentation in vitro after 3 days of incubation, regardless of stimulation conditions. This suggests that the cells are end-stage cells. Taken together, the data suggest an increase in anergic or apoptotic CD8+ T cells in HIV-infected persons. Eventual depletion of HIV-specific CD8+ T cells may occur through a process of proliferation, anergy induction, and apoptosis.

Antigens, CD↗
PubMed1994

Inhibition of retrovirus-induced syncytium formation by photoproducts of a brominated 1,8-naphthalimide compound.

A major disadvantage of conventional phototherapy is the requirement for the in situ delivery of stimulating photoenergy subsequent to the binding of photochemicals to target malignant cells, or virus-infected cells, or viruses. This drawback has resulted in considerable limitation in the use of photochemicals in photomedicine. To circumvent this problem, we have investigated the antiviral efficacy of a brominated 1,8-naphthalimide photocompound, termed LY66Br [3-bromo-4-(hexylamino)-N-hexyl-1,8-naphthalimide], which upon exposure to visible light at 420 nm generates independently of oxygen one or more stable antiviral molecular photoproducts (e.g., is 'preactivated'). Human cell lines infected with the human immunodeficiency virus type 1 (HIV-1), or with the human T-lymphotropic virus type-1 (HTLV-I) exposed to photochemical products of LY66Br (P-LY66Br) completely lost their ability to form syncytia in vitro. Photoproducts of P-LY66Br retain full antiviral activity for at least 3 and 6 weeks when stored at room temperature and at -80 degrees C, respectively. Concentrations of P-LY66Br, effective in inhibiting syncytium formation mediated by HIV-1 and HTLV-I, were nontoxic to normal red cell components of whole blood (red blood cell 2,3-diphosphoglyceric acid, adenosine triphosphate, osmotic fragility or blood type antigens). Additionally, no evidence of acute toxicity was demonstrated in mice following an intravenous bolus inoculation to achieve plasma concentration of 600 microM of P-LY66Br. These findings represent the first demonstration of inhibition of retrovirus-induced syncytium formation by a photochemical product, and justify further investigation of the preactivation process of photochemicals in the treatment of systemic viral infections such as the acquired immunodeficiency syndrome (AIDS), in cancer therapy, and in sterilization of banked blood products.

1-Naphthylamine↗
PubMed1994

Preferred hearing-aid frequency responses in simulated listening environments.

This study was designed to determine if an adaptive strategy could be used to select frequency/gain characteristics that would be considered appropriate across a variety of listening environments. In Experiment I, the test-retest reliability of the paired comparison procedure used in Experiment II was assessed in quiet for nine subjects and in speech noise for six subjects. For both conditions, results revealed mean standard deviations of < 3 dB from 200 through 4000 Hz. In Experiment II, four subjects selected frequency/gain characteristics for five different listening environments (quiet, speech noise, quiet conference room, reverberant lecture hall, and reverberant lecture hall in noise). In general, subjects did not tend to select different frequency/gain characteristics across the five simulated environments used in this study. When differences in frequency responses were observed, they tended to be alterations in overall gain rather than changes in relative frequency response. Findings support additional evaluation in more diverse listening environments, possibly with systems that incorporate nonlinear signal processing.

Acoustic Stimulation↗
PubMed1994

A sensitive reporter cell line for HIV-1 tat activity, HIV-1 inhibitors, and T cell activation effects.

The production and characterization of a cell line for quantitative HIV-1 Tat function and T cell activation assays is described. 1G5 is a clonal cell line derived from Jurkat T cells stably transfected with a luciferase gene driven by an HIV-1 long terminal repeat (HIV-LTR). The 1G5 clone was selected for low basal luciferase activity, susceptibility to HIV infection, and high responsiveness to Tat and T cell activation signals. A 10 to 1000-fold increase in luciferase activity after transfection or infection with tat-expressing vectors or HIV was observed. Equivalent levels of expression were detected after stimulation with T cell mitogens. The characteristics of 1G5 make it a valuable reagent for studies of HIV infection, HIV regulatory agents, and other T cell or HIV-activating factors, and for screening potential anti-HIV therapeutic agents.

Amino Acid Sequence↗
PubMed1994

Three-dimensional laser-scanning confocal microscopy of in situ hybridization in the skin.

In situ hybridization is an important tool in molecular and developmental biology to detect specific nucleic acid sequences (either mRNA or DNA) within cells. This technique is especially applicable to tissue sections since it provides information about the spatial distribution of DNA or mRNA sequences. However, previous studies utilizing in situ hybridization in the skin were hampered by a high degree of nonspecific background, which has made interpretation of the results difficult. In this paper, we demonstrate how refinements in in situ hybridization techniques, combined with laser-scanning confocal microscopy, significantly reduce nonspecific background and produce improved resolution of in situ hybridization in skin specimens. The sensitive detection method of laser-scanning confocal microscopy allows three-dimensional localization of S35 radioactive-labeled riboprobes within the emulsion of specimens, which is not possible with conventional bright or dark field light microscopy.

Dendritic Cells↗
PubMed1994

A comparative study of human immunodeficiency virus culture, polymerase chain reaction and anti-human immunodeficiency virus immunoglobulin A antibody detection in the diagnosis during early infancy of vertically acquired human immunodeficiency virus infection.

The infection status of 91 infants born to mothers with human immunodeficiency virus (HIV) infection was determined. Twenty-eight (31%) infants had confirmed HIV infection and 63 (69%) had seroreverted to HIV and lack evidence of infection. During the first 6 months of life HIV culture had a sensitivity and specificity for diagnosis of HIV infection of 80 and 100%, respectively. False negative HIV cultures were observed in only 7 of 35 specimens, 6 from among the 12 infected infants tested at birth. The sensitivity and specificity of polymerase chain reaction (PCR) detection of HIV were 95 and 93% respectively. A single false negative PCR test result was observed among the 19 tests performed on specimens from HIV-infected infants. False positive PCR test results were observed occasionally throughout the first 6 months of life. Detection of HIV-specific IgA antibody lacked diagnostic sensitivity; positive test results were observed in only 53% of specimens obtained from infected infants. Culture and PCR detection offer excellent sensitivity and specificity for diagnosis of HIV infection during the first 6 months of life; however, false-negative HIV cultures sometimes are observed, particularly during the newborn period, and either false negative or false positive PCR test results may be noted occasionally. For purposes of clinical decision-making, any positive test result should be confirmed with a second HIV culture or PCR test performed on a separate blood specimen.

False Negative Reactions↗
PubMed1994

Cocaethylene in meconium specimens.

Cocaethylene, a metabolite of cocaine and ethanol, exhibits cardiac and neurobehavioral effects. In order to determine the prevalence of this compound in meconium specimens, samples which gave a positive result for benzoylecgonine using fluorescence polarization immunoassay were analyzed by gas chromatography/mass spectrometry for cocaine, cocaethylene and benzoylecgonine. Deuterated cocaine, cocaethylene and benzoylecgonine were used as internal standards. Gas chromatography/mass spectrometry cutoff concentrations of 5.0 ng/g were utilized for all analytes. Of the 361 specimens which consecutively confirmed positive for cocaine or benzoylecgonine, 114 (31.6%) tested positive for cocaethylene. Further, cocaethylene accumulates in greater concentrations in meconium than urine, and is a useful analyte for identifying fetal alcohol exposure.

Cocaine↗
PubMed1993

Cocrystals of Escherichia coli trp repressor bound to an alternative operator DNA sequence.

Cocrystals of a 2:1 complex of trp repressor dimers with a DNA duplex containing a single, central operator half-site sequence are described. Crystals with different morphologies grew under diverse crystallization conditions within days to weeks by hanging-drop vapor-diffusion. Twinned rods split along their longitudinal cleft produce single crystals with space group C2 and unit cell dimensions a = 112.34 A, b = 90.16 A, c = 58.65 A and beta = 113.92 degrees. The crystals diffract to 2.4 A and are thus suitable for structural analysis by X-ray diffraction. Several heavy-atom derivative cocrystals have been obtained with iodouridine-substituted DNAs.

Bacterial Proteins↗
PubMed1993

Ca(2+)-dependent and thapsigargin-inhibited phosphorylation of Na+,K(+)-ATPase catalytic domain following chimeric recombination with Ca(2+)-ATPase.

Two chimeric proteins comprising the Na,K-ATPase catalytic domain (large cytosolic loop) and the two flanking regions of the Ca-ATPase were obtained by transient or stable expression in mammalian cells transfected with recombinant DNA. In the first chimera (CpNC), a large portion (containing the nucleotide-binding site) of the cytosolic loop between putative membrane spans M4 and M5 of the sarcoendoplasmic reticulum Ca2+ (SERCA) 1 (fast muscle) ATPase was replaced by the corresponding portion of the Na,K-ATPase alpha 1 subunit. In the second chimera (CNpC), an even larger portion (containing the nucleotide-binding site and the phosphorylation site) of the analogous cytosolic loop of the SERCA2 (cardiac muscle) ATPase was replaced by the corresponding portion of the Na,K-ATPase alpha 1 subunit. Steady state Ca2+ transport and coupled ATP hydrolysis by the chimeric proteins were negligible as compared to those obtained with SERCA enzymes. Nevertheless, the chimeric proteins were able to utilize ATP to form phosphoenzyme levels equal to those formed by SERCA ATPases. Chimeric and SERCA enzymes exhibited an identical Ca2+ requirement for ATP utilization and sensitivity to thapsigargin (TG) which is a specific inhibitor of SERCA ATPase and not of Na,K-ATPase. Furthermore, both SERCA and chimeric enzymes could be phosphorylated with P(i), and this reaction required removal of Ca2+. In comparative experiments, the functional pattern of seemingly unaffected phosphoenzyme formation and inhibited Ca2+ transport was produced in the SERCA ATPase even by single mutation of Pro337 to Ala, evidently due to defective protein conformation. Retention of Ca2+ and TG sensitivity by the chimeric proteins demonstrates that the Ca(2+)- and TG-binding domains do not reside within the cytosolic loop replaced by chimeric substitution and strongly support previous studies suggesting that binding of calcium required for enzyme activation occurs within the membrane-bound region of the SERCA ATPases (Clarke et al., 1989a; Sumbilla et al., 1991).

Amino Acid Sequence↗
PubMed1993

Analysis of trp repressor-DNA interactions using gel electrophoresis.

Quantitative analysis of the DNA-binding equilibria of E. coli trp repressor by gel electrophoresis led to reevaluation of our understanding of this complex system. In this review, the data leading to controversy about the trp system are discussed, and our current understanding is presented.

Bacterial Proteins↗
PubMed1993

Real ear to 6-cm3 coupler differences in young children.

Real-ear sound pressure levels under supra-aural earphones were measured for a group of young children (9 months to 7 years) and adults. Pure-tone signals were presented at nine test frequencies from 250 to 6000 Hz, and real ear to 6-cm3 coupler differences were computed for each frequency. Results suggest that, by 2 years of age, average real ear to 6-cm3 coupler differences are similar for adults and children. The intersubject variability for all groups supports the need for real-ear threshold measures on an individual basis in cases where the ability to amplify the speech spectrum to a level that is audible across the frequency range is in question.

Acoustics↗
PubMed1993

Neutralization of HIV-1 and inhibition of HIV-1-induced syncytia by 1,8-naphthalimide photoactive compound.

The antiviral property of a newly designed class of 1,8-naphthalimide photochemical compounds was investigated. One such photoactive compound, 1,14-bis-(N-hexyl-3'-bromo-1,8'-naphthalimide-4'-yl)-1,4,11,14- tetraazatetradecane-5,10-dione (diED66Br), when activated to an excited state by visible light (420 nm), effectively neutralized the in vitro infectivity of human immunodeficiency virus (HIV-1). Light-activated diED66Br also inhibited syncytium formation induced by cells infected with HIV-1. Nonactivated diED66Br was completely ineffective. The neutralizing and syncytium-inhibiting doses of activated diED66Br had no effect on normal human peripheral blood mononuclear cells. Radioimmunoprecipitation analysis indicated that diED66Br neutralizing activity resulted primarily from its ability to inhibit the binding of HIV-1 envelope glycoprotein gp120 to the CD4 cellular receptors. Although the exact molecular mechanism of viral neutralization by diED66Br has not been elucidated, its ability to neutralize HIV-1 infectivity and to inhibit syncytium formation supports further investigations of this photochemical as a potential therapeutic treatment of HIV-1 infection.

1-Naphthylamine↗
PubMed1993

Crossover of human immunodeficiency virus-infected patients from aerosolized pentamidine to trimethoprim-sulfamethoxazole: lack of hematologic toxicity and relationship of side effects to CD4+ lymphocyte count.

Trimethoprim-sulfamethoxazole (TMP/SMZ) was given in a crossover study to 130 human immunodeficiency virus-infected patients who had been receiving aerosolized pentamidine; 86 (66%) successfully crossed over to TMP/SMZ without hypersensitivity reactions or hematologic toxicity. No significant changes occurred in mean hemoglobin concentration, leukocyte count, or platelet count between study enrollment and 12-month follow-up. Predominant side-effects, in 41 patients (33.8%), were fever and maculopapular rashes, which resolved promptly with discontinuation of TMP/SMZ. The mean time to first side effect was 12.3 days, and 86% of side effects developed within 30 days. Three patients experienced toxicity serious enough to warrant hospitalization. Of patients with < or = 200 CD4+ lymphocytes/mm3, 57% developed rashes after the cross-over compared with only 27% of patients with higher CD4+ cell counts. Many patients currently receiving aerosolized pentamidine can be safely crossed over without hematologic toxicity or hypersensitivity reactions.

Adult↗
PubMed1993

Rapid characterization of HIV-1 sequence diversity using denaturing gradient gel electrophoresis and direct automated DNA sequencing of PCR products.

A direct method for visualization and isolation of sequence variants of human immunodeficiency virus type 1 (HIV-1) utilizing denaturing gradient gel electrophoresis (DGGE) combined with automated direct DNA sequencing was developed. Two fragments from the env gene and one from the nef gene of HIV-1, which together constitute approximately 1.0 kb of sequence, were amplified by PCR and analyzed. HIV-1 variants from each region were resolved and excised from the gel; this was followed by direct sequencing of different viral variants. In 9 infected patients, a limited number of dominant sequence variants could be seen in the three regions, together with a faint background of minor variants. The use of DGGE makes it possible to obtain a direct estimate of overall HIV-1 sequence diversity within patient samples without an intermediate DNA cloning step.

Base Sequence↗
PubMed1993

Intense exercise and food restriction cause similar hypothalamic neuropeptide Y increases in rats.

Neuropeptide Y (NPY) is a potent central appetite stimulant whose concentrations rise markedly in hypothalamic appetite-regulating regions in food-deprived rats. To determine whether increased energy expenditure also affects hypothalamic NPY, we studied the effects of intense physical exercise in rats (n = 10) running voluntarily on a large-diameter exercise wheel. Running was initiated by restricting food intake but stabilized at an average of 8 km/day when food intake was matched to that in 11 nonexercised, freely fed controls [23.9 +/- 1.9 (SE) g/day vs. 24.7 +/- 1.3 g/day; P > 0.5]. Running expended approximately 40% of daily energy intake, and weight gain was significantly inhibited. A separate group (n = 10) of nonexercised rats was food restricted (approximately 15 g/day) to match the weights of the exercised rats. The rats were killed after 40 days, when both experimental groups weighed 30% less than controls (P < 0.01). Hypothalamic NPY concentrations showed significant (P < 0.01) increases of 30-70% in specific regions (arcuate and dorsomedial nuclei and medial preoptic and lateral hypothalamic areas) in both the running and food-restricted groups, compared with controls. There were no significant differences between the two experimental groups in NPY concentrations in any hypothalamic region. These findings suggest that negative energy balance, whether caused by reduced energy intake or increased expenditure, increases hypothalamic NPYergic activity. As NPY acts on the hypothalamus to increase body weight, these data support the postulated homeostatic role of NPY in maintaining nutritional state.

Animals↗