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D E Lewis

Publications and source records attributed to D E Lewis.

At least 37 records · Page 2Linked to original sources
PubMed1999

Costimulatory pathways mediate monocyte-dependent lymphocyte apoptosis in HIV.

Examination of annexin V binding, an indicator of early apoptosis, on lymphocytes from HIV+ people immediately after isolation showed that both CD4(+) and CD8(+) T cells were apoptotic, whereas B cell apoptosis was induced mainly after incubation. CD8(+) T cell apoptosis correlated with fewer CD4(+) T cells, but not the level of viremia. To determine potential mechanisms for apoptosis, we examined FasL expression, which was dramatically elevated on CD14(+) monocytes; however, antibody to FasL did not reproducibly inhibit apoptosis. Rather, CD8(+) T cell apoptosis was caused by antigen-presenting cells because removal of monocytes or addition of antibodies to CD80 and CD86 reduced apoptosis. B cell apoptosis also involved costimulatory signals delivered by T cells but not monocytes. A unique CD8(bright)CD28(dim) T cell population died after costimulation by monocytes. Because this population was increased in patients with undetectable viremia, abnormal antigen-presenting cells may contribute to continued CD8(+) T cell exhaustion by inducing apoptosis.

Annexin A5↗
PubMed1999

Alterations in HIV expression in AIDS patients with psoriasis or pruritus treated with phototherapy.

BACKGROUND: Ultraviolet light (UVL) upregulates HIV transcription in vitro and in transgenic mice. AIDS-associated psoriasis and pruritus respond to phototherapy. OBJECTIVE: Our goal was to determine the effect of phototherapy on viral load and immunologic parameters in HIV-positive patients. METHODS: T cell subsets, p24, plasma cytokines, serum or plasma HIV-RNA, dosage, and antivirals were assessed in HIV-positive patients and negative controls receiving 6 weeks of phototherapy with UVB and in untreated controls. RESULTS: Phototherapy improved skin conditions without significantly affecting T cell numbers. Plasma p24 increased 2-fold (P = .055) and HIV-RNA levels 4-fold (P = .022) 6 weeks from baseline in patients who entered the trial before March 1995. Later patients who were mostly receiving combination antiviral therapy showed a 4-fold reduction in serum HIV-RNA (P = .012) at 2 weeks. The effect of UVB on viral load at 6 weeks was dependent on the baseline level (P = .006). IL-10 increased and was inversely related to HIV-RNA levels (P = .0267). CONCLUSION: Phototherapy is associated with HIV load alterations, depending on patients' initial HIV-RNA, antiviral therapy, skin type, and UVL dosage.

Acquired Immunodeficiency Syndrome↗
PubMed1999

Role of HU and DNA supercoiling in transcription repression: specialized nucleoprotein repression complex at gal promoters in Escherichia coli.

Efficient repression of the two promoters P1 and P2 of the gal operon requires the formation of a DNA loop encompassing the promoters. In vitro, DNA looping-mediated repression involves binding of the Gal repressor (GalR) to two gal operators (OE and OI) and binding of the histone-like protein HU to a specific locus (hbs) about the midpoint between OE and OI, and supercoiled DNA. Without DNA looping, GalR binding to OE partially represses P1 and stimulates P2. We investigated the requirement for DNA supercoiling and HU in repression of the gal promoters in vivo in strains containing a fusion of a reporter gene, gusA or lacZ, to each promoter individually. While the P1 promoter was found to be repressible in the absence of DNA supercoiling and HU, the repression of P2 was entirely dependent upon DNA supercoiling in vivo. The P2 promoter was fully derepressed when supercoiling was inhibited by the addition of coumermycin in cells. P2, but not P1, was also totally derepressed by the absence of HU or the OI operator. From these results, we propose that the repression of the gal promoters in vivo is mediated by the formation of a higher order DNA-multiprotein complex containing GalR, HU and supercoiled DNA. In the absence of this complex, P1 but not P2 is still repressed by GalR binding to OE. The specific nucleoprotein complexes involving histone-like proteins, which repress promoter activity while remaining sensitive to inducing signals, as discussed, may occur more generally in bacterial nucleoids.

Aminocoumarins↗
PubMed1999

Recognition performance for four combinations of FM system and hearing aid microphone signals in adverse listening conditions.

OBJECTIVE: Children with moderate to severe hearing loss routinely use personal frequency modulated (FM) systems in the classroom to improve the signal to noise ratio of teacher-directed speech with notable success. Attention is now being given to the ability of these children to hear other students via the hearing aid (HA) microphone while using an FM system. As a result, a variety of FM system and HA microphone combinations have been recommended for classroom use. To date, there are no studies regarding the efficacy of these FM/HA combinations. The purpose of this study was to evaluate recognition performance using four FM/HA combinations and to characterize that performance for stimuli received primarily through FM system and HA microphone transmission. DESIGN: Recognition performance for FM system and HA microphone signals was evaluated for two symmetrical and two asymmetrical FM/HA combinations using two commercially available FM systems (one conventional and one FM-precedence circuit). Eleven children (ages 9 to 12) with moderate to severe sensorineural hearing loss and eight children (ages 10 to 11) with normal hearing served as subjects. The two symmetrical FM/HA combinations included: 1) binaural FM system and HA microphone input using the conventional FM system, and 2) binaural FM and HA input using the FM-precedence circuit. The conventional FM system was used for the two asymmetrical combinations and included: 1) binaural FM input and monaural HA input, and 2) FM input to one ear and HA input to the other. Stimuli were 33 consonants presented in the form of nonsense syllables. The stimuli were presented through three loudspeakers representing a teacher and two fellow students in a classroom environment. Speech shaped noise was presented through two additional loudspeakers. RESULTS: In general, no statistically significant differences in recognition performance were found between any of the FM/HA combinations. Mean recognition scores for HA microphone transmission (55%) were significantly poorer than those for FM system transmission (75%). As expected, initial consonants were more easily recognized than final consonants via FM system and HA microphone transmission. However, voiceless consonants were more easily recognized than voiced consonants via HA microphone transmission, which was not predicted on the basis of previous research. CONCLUSIONS: These results suggest that a certain amount of flexibility is present when choosing an FM/HA combination. However, recognition performance via the HA microphones was consistently poorer than performance via FM transmission. Because relevant material also originates from fellow students (e.g., answering teacher-directed questions), input via the HAs is often as important as information originating from the teacher. The results suggest that attempts to improve performance for signals transmitted through the HA microphones in a classroom setting would benefit children with hearing loss.

Child↗
PubMed1999

Subjective effects of peak clipping and compression limiting in normal and hearing-impaired children and adults.

Despite many advances in hearing-aid signal processing, compression limiting and peak clipping are still used. To date, perceptual studies have been conducted only with adults. The current study was designed to investigate the clarity of peak-clipped and compressed speech for both adults and children. Subjects were 30 normal-hearing and 30 hearing-impaired individuals in three age ranges (7-9, 10-12, and 16-50 years). Stimuli were processed at 60, 70, 75, and 80 dB SPL using peak clipping and at 80 dB SPL using compression limiting. Paired-comparison measures were used to assess the clarity of sentences, and a signal-to-distortion ratio (SDR) based on a measure of coherence between input and output was computed for each condition. For the peak-clipping conditions, there was a decrease in perceived clarity as the input increased from 60 to 80 dB SPL. This perceptual continuum was most apparent for the normal-hearing adults. The normal-hearing 10-12 year olds and the hearing-impaired adults showed a similar, but less pronounced, pattern. In contrast, the remaining three subject groups showed minimal differences in perceived clarity across conditions. Surprisingly, only the two oldest normal-hearing groups showed a clear preference for compression limiting over peak clipping at the highest input level, and only their results were consistent with the pattern of coherence across stimuli. Judgments of clarity by the normal-hearing subjects correlated best with the SDR in the 500-2000-Hz range, while clarity judgments of the hearing-impaired subjects correlated best with the SDR below 1000 Hz.

Adolescent↗
PubMed1998

Isolation of yeast mutants defective for localization of vacuolar vital dyes.

An application of flow cytometric sorting is used for isolation of Saccharomyces cerevisiae mutants that mislocalize vacuolar vital dyes. This screen is based on the ability of a lipophilic styryl compound, N-(3-triethylammoniumpropyl)-4-(6-(4-(diethylamino)phenyl)hexatrie nyl )pyridinium dibromide (FM4-64), to label endocytic intermediates from the plasma membrane to the vacuole membrane at 15 degreesC. Cells stained at 15 degreesC for both FM4-64 and carboxydichlorofluorescein diacetate (a vacuolar luminal vital stain), had a pronounced shift in red/green fluorescence from cells stained at 30 degrees or 38 degreesC. Flow cytometric selection based on this characteristic shift allowed the isolation of 16 mutants. These comprised 12 complementation groups, which we have designated SVL for styryl dye vacuolar localization. These groups were put into three classes. Class I mutants contain very large vacuoles; class II mutants have very fragmented vacuoles; and class III mutants show the strongest svl phenotype with punctate/diffuse FM4-64 staining. Limited genetic overlap was observed with previously isolated mutants, namely svl2/vps41, svl6/vps16, and svl7/fab1. The remaining svl mutants appear to represent novel genes, two of which showed temperature-sensitive vacuole staining morphology. Another mutant, svl8, displayed defects in uptake and sorting of phosphatidylcholine and phosphatidylethanolamine. Our flow cytometric strategy may be useful for isolation of other mutants where mislocalization of fluorescent compounds can be detected.

Biological Transport, Active↗
PubMed1998

Prenatal diagnosis with use of fetal cells isolated from maternal blood: five-color fluorescent in situ hybridization analysis on flow-sorted cells for chromosomes X, Y, 13, 18, and 21.

OBJECTIVE: Currently, prenatal diagnosis of chromosome abnormalities requires invasive techniques such as amniocentesis and chorionic villus sampling that carry small but finite risks of fetal loss. A noninvasive approach is to isolate fetal cells from maternal blood by flow sorting followed by genetic interphase analysis with fluorescence in situ hybridization. Because the ratio of fetal to maternal cells is relatively low after flow sorting and to detect 90% to 95% of fetal aneuploidies associated with serious birth defects, a 5-color fluorescent in situ hybridization strategy is necessary for simultaneous detection of chromosomes X, Y, 13, 18, and 21 in all flow-sorted nuclei recovered from a specimen. STUDY DESIGN: Fetal nucleated red blood cells were isolated from maternal blood in 40 cases (10.4 to 27.0 weeks' gestation) by flow cytometry on the basis of positive selection of CD71+ (transferrin receptor), CD45-, and LDS751 staining. Each case was evaluated for 5-color fluorescent in situ hybridization efficiency by determining the percentage of flow-sorted nuclei containing 8 hybridization signals for chromosomes X, Y, 13, 18, and 21. RESULTS: A total of 42,312 flow-sorted nuclei from maternal blood samples were analyzed. In 5 of 16 (31%) cases with a male fetus, 0.16% of nuclei scored were identified as fetal by the presence of 1 signal each for chromosomes X and Y. Fetal trisomy 21 nuclei were accurately detected in 2 cases with a female fetus, each of which was subsequently confirmed. CONCLUSIONS: Five-color interphase fluorescent in situ hybridization analysis can be used to effectively analyze rare fetal aneuploid nuclei in enriched flow-sorted cells isolated from maternal blood.

Chromosome Aberrations↗
PubMed1998

Trial of labour versus elective repeat caesarean section: a cost-effectiveness analysis.

For subsequent births, women who have experienced previous caesarean section face a choice between elective caesarean section and trial of labour. The study reported in this paper utilises Australian hospital data to compare birth outcome and health system costs of these two options. Although trial of labour is more expensive if the result is an emergency caesarean section, high rates of successful vaginal delivery mean that, overall, trial of labour is found to be 30 per cent less expensive than elective caesarean section. It is estimated that trial of labour remains the most cost-effective option as long as less than 68 per cent of women require emergency caesarean section. This study highlights the potential importance of more accurate information about a broader range of costs and outcomes in order for stronger conclusions to be drawn.

Australia↗
PubMed1998

Presence of HLA-C-restricted cytotoxic T-lymphocyte responses in long-term nonprogressors infected with human immunodeficiency virus.

Approximately 5% of people with human immunodeficiency virus type 1 (HIV-1) infection remain free of disease for 10 or more years. These long-term nonprogressors (LTNPs) exhibit lower viral loads and stable CD4+ lymphocyte counts. The immunologic basis for this disease-free condition is not known. Because cytotoxic T lymphocytes (CTLs) constitute a major immune defense mechanism for sustained recovery from viral infections, we analyzed HIV-specific CTL responses in three asymptomatic LTNPs. We observed the presence of HIV-1 envelope-specific CTL responses mediated by HLA class I C-restricted CD8+ cells in these individuals. Using autologous target cells and a panel of HLA-matching and -mismatching B-cell lines as targets, we determined that HLA-Cw7 is the restricting element for the observed CTL activity. Additionally, we identified three peptides, one previously not reported, from conserved regions in the envelope protein as CTL epitopes. We previously reported these peptides to be efficient in inducing HIV-specific cellular immune responses in murine and nonhuman primate models. Our results support the role of the HLA-C locus in generating CTL responses and constitute the first report of an HLA-Cw7-restricted HIV-1 envelope-specific CTL response in HIV+ LTNPs, which may be important in the control of HIV replication in vivo.

Amino Acid Sequence↗
PubMed1998

Distinct serum cytokines in AIDS-related skin diseases.

To determine whether common skin diseases associated with human immunodeficiency virus (HIV) were distinguishable based on the pattern of serum cytokine expression, we studied patients with psoriasis, pruritus, and Kaposi's sarcoma (KS) for levels of tumor necrosis factor (TNF)-alpha, interferon-gamma (IFN-y), interleukin (IL)-10, and IL-4. Thirty-two HIV-positive (HIV+) patients including 8 with KS, 11 with psoriasis, and 13 with pruritus along with 16 HIV-negative subjects with psoriasis were studied. IFN-gamma levels were highest in sera of HIV+ patients with psoriasis (p = 0.040). By contrast, TNF-alpha and IL-10 levels were highest in sera of HIV+ patients with pruritus (p = 0.012). Detectable levels of all cytokines in these patients were remarkably higher than for healthy adults. These results suggest that common skin diseases associated with HIV infection and AIDS can be distinguished by the production of unique cytokines.

Acquired Immunodeficiency Syndrome↗
PubMed1998

Transcription regulation by repressosome and by RNA polymerase contact.

The original model of repression of transcription initiation is steric interference of RNA polymerase binding to a promoter by its repressor protein bound to a DNA site that overlaps the promoter. From the results described here, we propose two other mechanisms of repressor action, both of which involve formation of higher-order DNA-multiprotein complexes. These models also explain the problem of RNA polymerase gaining access to a promoter in the condensed nucleoid in response to an inducing signal to initiate transcription.

Amino Acid Sequence↗
PubMed1998

Optimized fixation and storage conditions for FISH analysis of single-cell suspensions.

In our protocol to isolate and identify fetal cells in maternal peripheral blood, antibody (Ab)-stained cells are preserved with paraformaldehyde (PF) before batch flow cytometric sorting. However, PF fixation compromises the quality of subsequent interphase fluorescence in situ hybridization (FISH). We therefore examined the effect of PF concentrations and storage time in phosphate-buffered saline (PBS) on the quality of FISH signals. Cells were analyzed for changes in light scatter, morphology, and accessibility of target cell DNA. Fixation in 3% PF for 1 hr was ideal for both flow cytometry and subsequent FISH detection. However, beyond 10 days of storage, FISH quality deteriorated. (J Histochem Cytochem 46:971-973, 1998)

Buffers↗
PubMed1998

Smoking policy in long-term care: a survey of administrators in San Francisco.

Despite the fact that smoking is a ubiquitous yet potentially hazardous behavior in long-term care settings, little previous investigation has been made into the construction or implementation of policy to manage smoking by elderly residents. This survey of administrators in long-term care facilities in San Francisco city and county reveals that fire and safety issues were the prime forces motivating smoking policy, which operated through control of behavior rather than by other available means, such as the use of fire retardant aprons. Although all facilities permitted smoking, a hierarchy of limit setting strategies was adopted, strategies which successively and evermore intrusively overrode the resident's autonomy and turned smoking policy from beneficent philosophy into a coercive moral statement. Arranged in order of frequency of occurrence and increasing degree of restriction, these strategies were: (a) designating appropriate locations; (b) controlling smoking opportunities and materials; (c) requiring staff supervision or help; (d) limiting the availability of staff help; and (e) writing Doctor's orders. By acknowledging the tensions between ambivalent goals inherent in smoking in long-term care, administrators could devise policies and procedures that are both supportive of collective rights and less corrosive of individual ones.

Aged↗
PubMed1997

TAK, an HIV Tat-associated kinase, is a member of the cyclin-dependent family of protein kinases and is induced by activation of peripheral blood lymphocytes and differentiation of promonocytic cell lines.

We have previously identified a cellular protein kinase activity termed TAK that specifically associates with the HIV types 1 and 2 Tat proteins. TAK hyperphosphorylates the carboxyl-terminal domain of the large subunit of RNA polymerase II in vitro in a manner believed to activate transcription [Herrmann, C. H. & Rice, A. P. (1995) J. Virol. 69, 1612-1620]. We show here that the catalytic subunit of TAK is a known human kinase previously named PITALRE, which is a member of the cyclin-dependent family of proteins. We also show that TAK activity is elevated upon activation of peripheral blood mononuclear cells and peripheral blood lymphocytes and upon differentiation of U1 and U937 promonocytic cell lines to macrophages. Therefore, in HIV-infected individuals TAK may be induced in T cells following activation and in macrophages following differentiation, thus contributing to high levels of viral transcription and the escape from latency of transcriptionally silent proviruses.

Cell Differentiation↗
PubMed1997

Protection of primary human T cells from HIV infection by Trev: a transdominant fusion gene.

Gene therapy is one of several approaches that are being tested in the search for an effective anti-human immunodeficiency virus (HIV) treatment. In this strategy, a "protective" gene would be introduced into target cells, rendering them relatively resistance to the virus-induced cytopathicity. Tat and Rev are viral proteins essential for HIV gene expression. Tat increases viral gene transcription and Rev is responsible for the nuclear export of mRNA encoding structural viral proteins. A fusion protein (Trev) was constructed, joining Tat and Rev transdominant mutant gene sequences. Previously, we showed that Trev inhibits both Tat and Rev activities in Jurkat T cells. To determine whether Trev could inhibit HIV replication in primary cells, we transferred the trev gene to peripheral blood lymphocytes and challenged them with different HIV strains. Levels of HIV p24 antigen (Ag) were reduced 4- to 15-fold in cultures of Trev-CD4+ T cells infected with two HIV primary clinical isolates and were not detectable in cultures infected with HIV strains NL4-3 and SF2. In contrast, cultures of nontransduced CD4+ T cells infected with the same viruses had levels of HIV p24 Ag up to 10 ng/ml. Trev-transduced CD4+ T cells demonstrated increased survival following HIV challenge for the length of the experiments (30 days). We did not observe rapid emergence of Trev-resistant HIV in our cultures. Following HIV challenge, cell-associated Trev protein was increased, supporting the hypothesis that cells surviving Trev expression provided a cell survival advantage. This work showed that Trev was able to inhibit HIV replication in primary CD4+ T cells, and, therefore the trev gene could be a candidate for gene therapy against HIV.

CD4-Positive T-Lymphocytes↗
PubMed1997

Regulation of CD28 costimulation in human CD8+ T cells.

Optimal stimulation and prevention of anergy in T cells requires signaling through the CD28 molecule. During HIV disease progression, CD28 expression is lost, particularly on CD8+ T cells. Because alterations in cytokine production patterns occur during HIV infection, we determined whether CD8+ T cell phenotype or function was affected by cytokine environment. Treatment of CD8+ T cells with IL-4 decreased levels of both CD28 surface expression and message and increased CD8 expression. Furthermore, CD8+ T cells that had down-regulated CD28 had reduced proliferative capacity. The inhibitory effects of CD28 reduction could be compensated either by increased anti-CD3 or by exogenous IL-2, suggesting that the strength of T cell signaling necessary for the production of IL-2 and subsequent proliferation is negatively regulated by IL-4. CD8+ subpopulations with differential CD28 expression produced different patterns of cytokines, particularly IL-2 and IFN-gamma. Furthermore, CD8+ T cells that had reduced CD28 levels but made their own IL-2 were able to proliferate in response to TCR stimulation. These results suggest that loss of CD28 expression and CD8 T cell function can be regulated by the cytokine environment, which may be altered during HIV disease progression. Whether the dysfunction of CD8+ T cells in HIV infection occurs by such a mechanism is the subject of future investigation.

Antibodies, Monoclonal↗
PubMed1997

Role of placental cytokines and inflammation in vertical transmission of HIV infection.

In light of new evidence suggesting that maternal human immunodeficiency virus (HIV) infection produces at least a three-fold increase in the number of early spontaneous abortions, it is important to search for factors that may predispose to fetal wastage. Immunological factors are thought to play an important role in permitting the HLA-disparate fetus to continue to term, despite powerful maternal immune forces capable of rejection. In the context of a heightened incidence of spontaneous abortion in HIV infection, evidence is now accumulating that implicates an imbalance in immune factors in contributing to this fetal loss. Soluble immune factors, such as cytokines, have been suggested as contributing agents to recurrent spontaneous abortions. Inflammatory cytokines-interleukin 1beta, interleukin 6 and tumor necrosis factor alpha-have been measured in isolated placental trophoblastic cells in HIV-infected and non-infected pregnant women in an attempt to explore this hypothesis. These inflammatory cytokines and their messenger RNAs were significantly elevated before and after stimulation in HIV-infected women, supporting the belief that HIV-infected women present their fetuses a milieu of imbalanced immune factors capable of contributing to immunological rejection. In addition, these elevated inflammatory cytokine levels may contribute to HIV disease progression in fetuses by virtue of activation of HIV gene transcription factors similar to what has been demonstrated in in vitro systems. We therefore propose that HIV infection in pregnant women produces an altered state of certain soluble immune factors, which in concert with other immune factor abnormalities, such as loss of immune selection in the fetal thymus, predisposes the fetus to advanced HIV infection and possible spontaneous abortion.

Abortion, Spontaneous↗