Biomedical subjects

A Levine

Publications and source records attributed to A Levine.

At least 19 recordsLinked to original sources

PubMed2001

Determinants of HIV-1 shedding in the genital tract of women.

BACKGROUND: Plasma HIV-1 RNA concentration has been the best predictor for risk of heterosexual and perinatal transmission. However, direct contact with HIV-1 present locally in the genital tract might be necessary for transmission. We aimed to assess the relation between HIV-1 shedding (RNA or culturable virus) in female genital secretions and other factors that might affect HIV-1 shedding. METHODS: This was a cross-sectional study within the Women's Interagency HIV Study (WIHS), a prospective longitudinal cohort study of HIV-infected women. We enrolled 311 HIV positive women from Jan 30, 1997 to July 1, 1998. We did clinical assessments, cultured HIV-1, and measured RNA in peripheral blood mononuclear cells (PBMC) and genital secretions. We compared the results with univariate and multivariate analyses. Presence of HIV-1 RNA or culturable virus in genital secretions was defined as HIV-1 shedding. FINDINGS: HIV-1 RNA was present in genital secretions of 57% (152/268) of women whereas infectious virus was detected only in 6% (17/271). Genital tract HIV-1 shedding was found in 80% (130/163) of women with detectable plasma RNA and 78% (116/148) of women with positive PBMC cultures. 33% (27/83) of women with less than 500 copies/mL plasma RNA and 39% (35/90) of those with negative PBMC cultures also had genital tract shedding. INTERPRETATION: Plasma RNA concentration, both qualitatively and quantitatively, was the most important factor in predicting genital HIV-1 shedding, even among women receiving potent antiretroviral therapy. However, HIV-1 shedding did occur in women with less than 500 copies/mL plasma HIV-1 RNA. This finding suggests that a separate reservoir of HIV-1 replication may exist in some women.

Adult↗

PubMed2001

A computational scan for U12-dependent introns in the human genome sequence.

U12-dependent introns are found in small numbers in most eukaryotic genomes, but their scarcity makes accurate characterisation of their properties challenging. A computational search for U12-dependent introns was performed using the draft version of the human genome sequence. Human expressed sequences confirmed 404 U12-dependent introns within the human genome, a 6-fold increase over the total number of non-redundant U12-dependent introns previously identified in all genomes. Although most of these introns had AT-AC or GT-AG terminal dinucleotides, small numbers of introns with a surprising diversity of termini were found, suggesting that many of the non-canonical introns found in the human genome may be variants of U12-dependent introns and, thus, spliced by the minor spliceosome. Comparisons with U2-dependent introns revealed that the U12-dependent intron set lacks the 'short intron' peak characteristic of U2-dependent introns. Analysis of this U12-dependent intron set confirmed reports of a biased distribution of U12-dependent introns in the genome and allowed the identification of several alternative splicing events as well as a surprising number of apparent splicing errors. This new larger reference set of U12-dependent introns will serve as a resource for future studies of both the properties and evolution of the U12 spliceosome.

Alternative Splicing↗

PubMed2001

Vesicle-associated membrane protein of Arabidopsis suppresses Bax-induced apoptosis in yeast downstream of oxidative burst.

Programmed cell death (PCD) in many systems is controlled by relative amounts of the apoptosis-regulating proteins Bax and Bcl-2 through homo- or heterodimerization. Here we show that Bax-induced PCD of yeast was suppressed by transformation with a vesicle-associated membrane protein from Arabidopsis (AtVAMP), which was isolated by screening a cDNA expression library against sugar-induced cell death in yeast. AtVAMP expression blocked Bax-induced PCD downstream of oxidative burst. AtVAMP also prevented H(2)O(2)-induced apoptosis in yeast and in Arabidopsis cells. Reduced oxidation of lipids and plasma membrane proteins was detected in the AtVAMP-transformed yeast, suggesting improved membrane repair. Inhibition of intracellular vesicle trafficking by brefeldin A induced apoptosis from a sublethal concentration of H(2)O(2). No protection occurred by overexpression of the yeast homolog SCN2. However, efficient suppression of yeast PCD occurred by expression of a chimeric gene, composed of the conserved domains from yeast, fused to the variable N-terminal domain from Arabidopsis, resulting in exchange of the proline-rich N-terminal domain of SCN2 with a proline-poor Arabidopsis sequence. Our results suggest that intracellular vesicle traffic can regulate execution of apoptosis by affecting the rate of membrane recycling and that the proline-rich N-terminal domain of VAMP inhibited this process.

Apoptosis↗

PubMed2001

Chemotherapy for human immunodeficiency virus-associated non-Hodgkin's lymphoma in combination with highly active antiretroviral therapy.

PURPOSE: This study investigated the efficacy, toxicity, and pharmacokinetic interactions resulting from simultaneous combination chemotherapy and highly active antiretroviral therapy (HAART) for patients with human immunodeficiency virus (HIV)-associated non-Hodgkin's lymphoma (NHL). In addition, the effects on viral load, CD4 counts, and opportunistic infections were examined with the use of combination chemotherapy combined with HAART. PATIENTS AND METHODS: Sixty-five patients with previously untreated and measurable disease at any stage of HIV-associated NHL of intermediate or high grade were entered onto this study at 17 different centers. The first 40 patients entered onto the study received reduced doses of cyclophosphamide and doxorubicin, combined with vincristine and prednisone (modified CHOP [mCHOP]), whereas the subsequent 25 patients entered onto the study received full doses of CHOP combined with granulocyte colony-stimulating factor (G-CSF). All patients also received stavudine, lamivudine, and indinavir. RESULTS: The complete response rates were 30% and 48% among patients who received mCHOP and full-dose CHOP combined with HAART, respectively. Grade 3 or 4 neutropenia occurred in 25% of patients receiving mCHOP and 12% of those receiving full-dose CHOP combined with G-CSF (25% v 12%). There were similar numbers of patients with grade 3 or 4 hyperbilirubinemia (12% and 17%), constipation and abdominal pain (18% and 17%), and transaminase elevation (48% and 52%) on the modified and full-dose arms of the study, respectively. Doxorubicin clearance and indinavir concentration curves were similar among patients on this study and historical controls, whereas cyclophosphamide clearance was 1.5-fold reduced as compared with control values. Human immunodeficiency virus (HIV) load declined from a median baseline value of 29,000 copies/mL to a median minimum value on therapy of 500 copies/mL. CONCLUSION: Either modified-dose or full-dose CHOP chemotherapy for HIV-NHL, delivered with HAART, is effective and tolerable.

Adult↗

PubMed2001

Induction of cell death in arabidopsis by superoxide in combination with salicylic acid or with protein synthesis inhibitors.

Induction of programmed cell death (PCD) by oxidative stress is a widespread phenomenon in all living organisms. The degree of cell death depends on the concentration of oxidants and on environmental and physiological conditions. In plants, generation of reactive oxygen intermediates (ROI) occurs during many biotic and abiotic stresses. Recently, a number of spontaneous cell death mutants have been isolated in Arabidopsis. In one of the mutants (lsd1) induction of PCD has been attributed to superoxide (O(2)(*)(-)). Here we show that while in wild type plants generation of superoxide is symptomless, combination of O(2)(*)(-) with salicylic acid or with inhibitors of protein synthesis induced PCD. Cell death induced by these treatments was suppressed by protease inhibitors, indicating an active response. PCD induced by both treatments was preceded by nuclear condensation, which is a hallmark of apoptosis in plants and animals. These results may explain increased sensitivity to oxidative stress under certain physiological conditions, associated with high levels of salicylic acid or decrease in protein synthesis.

Apoptosis↗

PubMed2001

Accuracy of diagnoses of HIV-related oral lesions by medical clinicians. Findings from the Women's Interagency HIV Study.

OBJECTIVE: To determine if medical clinicians are as accurate as dental clinicians in recognizing diagnostic characteristics of HIV-related oral lesions. METHODS: In 355 HIV-infected participants at five Women's Interagency HIV Study sites, we paired oral examinations conducted within 7 days of each other by dental and medical clinicians. We used the former as a gold standard against which to evaluate the accuracy of the latter. We assessed the accuracy of the medical clinicians' findings based both on their observations of abnormalities and on their descriptions of these abnormalities. RESULTS: Dental clinicians diagnosed some oral abnormality in 38% of participants. When "abnormality" was used as the medical clinicians' outcome, sensitivities were 75% for pseudomembranous candidiasis and 58% for erythematous candidiasis, but only 40% for hairy leukoplakia. When a precise description of the abnormality was used as their outcome, sensitivities were 19%, 12% and 20%, respectively. CONCLUSIONS: Medical clinicians recognize that HIV-related oral abnormalities are present in 40-75% of cases, but less often describe them accurately. Low sensitivity implies that the true associations of specific oral lesions with other HIV phenomena, such as time until AIDS, must be stronger than the literature suggests.

AIDS-Related Opportunistic Infections↗

PubMed2001

Maximal aryl hydrocarbon receptor activity depends on an interaction with the retinoblastoma protein.

The aryl hydrocarbon receptor (AhR) belongs to the basic helix-loop-helix/periodicity/AhR nuclear translocator/simple-minded (Per-Arnt-Sim) family of transcription factors that regulate critical functions during development and tissue homeostasis. Within this family, the AhR is the only member conditionally activated in response to ligand binding, typified by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). We recently demonstrated that the AhR interacts with the retinoblastoma protein (pRb). This report presents evidence that a LXCXE motif in the AhR protein confers pRb binding, which is necessary for maximal TCDD induced G(1) arrest in rat 5L hepatoma cells. The data support a mechanism whereby pRb seems to regulate G(1) cell cycle progression distinct from the direct repression of E2F-mediated transcription. Furthermore, the results indicate that the AhR-pRb interaction regulates TCDD induction of CYP1A1, suggesting that pRb may be a general AhR coactivator.

Amino Acid Motifs↗

PubMed2001

Benign intracranial hypertension associated with budesonide treatment in children with Crohn's disease.

Oral budesonide in adult studies is a potent corticosteroid with decreased systemic bioavailability and an improved adverse effect profile in comparison with prednisone. It has recently been introduced for the treatment of inflammatory bowel disease in Europe, Canada, and Israel. Benign intracranial hypertension has rarely been associated with corticosteroid therapy but has not been reported in association with budesonide therapy. Three adolescents with Crohn's disease and poor nutritional status developed benign intracranial hypertension while receiving oral budesonide. All three patients had previously received multiple courses of prednisone during the course of their disease, without developing intracranial hypertension. Benign intracranial hypertension resolved after medication withdrawal and did not recur with subsequent use of prednisone. Evaluation for benign intracranial hypertension should be considered in patients with inflammatory bowel disease who develop headache while receiving oral budesonide. This side effect may be associated with poor nutritional status.

Adolescent↗

PubMed2001

Carnitine-deficient myopathy as a presentation of tyrosinemia type I.

Carnitine deficiency secondary to renal Fanconi's tubulopathy has been described in only a few inborn errors of metabolism: cystinosis, galactosemia, and Fanconi-Bieckel syndrome. We report a 27-month-old infant who presented with a sudden change in gait owing to proximal muscle weakness. The laboratory evaluation showed carnitine deficiency associated with Fanconi's tubulopathy. Eventually, tyrosinemia type I was diagnosed. Carnitine deficiency can contribute to the clinical picture of hepatorenal tyrosinemia and should therefore be evaluated and treated.

Carnitine↗

PubMed2001

Molecular regulation of genes encoding xenobiotic-metabolizing enzymes: mechanisms involving endogenous factors.

It is widely recognized that xenobiotic-metabolizing enzymes play a fundamental role in the basic processes of carcinogenesis and toxicity on one hand, and chemoprevention and drug efficacy on the other. Realization that different factors can profoundly affect the expression of these enzymes at the genome level has resulted in an enhanced appreciation of the importance these genes play in our modern industrialized age. There continues to be rapid proliferation of studies addressing the molecular regulation of these genes. The discovery of common signal transduction pathways and transcription factors that dictate tissue and developmental-specific expression, as well as variation in expression within a given tissue, suggest that there may be significant interaction among these various regulatory systems. This report is a summary of a symposium that was part of the Structure, Function and Regulation of Cytochromes P450 and Xenobiotic Metabolizing Enzymes satellite meeting of the 2000 joint meeting of the American Society for Biochemistry and Molecular Biology, the American Society for Pharmacology and Experimental Therapeutics, the French Pharmacological Society, and the Pharmacological Society of Canada held in Boston, Massachusetts. This symposium brought together several speakers who addressed specific receptor-mediated signal transduction pathways involved in the regulation of xenobiotic-metabolizing enzymes, as well as other molecular mechanisms whereby endogenous factors are involved in controlling tissue- and developmental-specific expression.

Enzymes↗

PubMed2000

Association of race and gender with HIV-1 RNA levels and immunologic progression.

CONTEXT: HIV-1 RNA and lymphocyte subset levels are the principal indications for antiretroviral treatment. Past reports have differed with regard to the effect of gender and race on these measures and in measures of disease progression. OBJECTIVE: To assess racial and gender differences in HIV-1 RNA levels and CD4+ lymphocyte decline. DESIGN: A longitudinal study based in the two largest HIV natural history cohort studies conducted in 7 metropolitan areas of the United States. RESULTS: In all, 1256 adult women and 1603 adult men for whom multiple data points were available prior to initiation of antiretroviral therapy were included. Women were more likely to be nonwhite, to have a history of injection drug use, and to have HIV-associated symptoms. After adjustment for differences in measurement method, baseline CD4+ cell count, age, and clinical symptoms, HIV-1 RNA levels were 32% to 50% lower in women than in men at CD4+ counts >200 cells/mm3 (p <.001) but not at CD4+ cell counts <200 cells/mm3. HIV-1 RNA levels were also 41% lower in nonwhites than in whites (p <.001) and 21% lower in persons reporting a prior history of injection drug use (p <.001). Women had more rapid declines in CD4+ cell counts over time than men (difference in slope of 46 cells/year) and nonwhite individuals had slower decline in CD4 cell counts than whites (difference of 39 cells/year). CONCLUSIONS: Both race and gender influence the values of HIV-1 RNA and the rate of HIV-1 disease progression as indicated by decline in CD4 cell counts over time. These effects could provide clues regarding the factors that influence HIV-disease progression and may indicate that guidelines for therapy should be adjusted for demographic characteristics.

Acquired Immunodeficiency Syndrome↗

PubMed2000

The hypersensitive response facilitates plant infection by the necrotrophic pathogen Botrytis cinerea.

BACKGROUND: Plants have evolved efficient mechanisms to combat pathogen attack. One of the earliest responses to attempted pathogen attack is the generation of oxidative burst that can trigger hypersensitive cell death. This is called the hypersensitive response (HR) and is considered to be a major element of plant disease resistance. The HR is thought to deprive the pathogens of a supply of food and confine them to initial infection site. Necrotrophic pathogens, such as the fungi Botrytis cinerea and Sclerotinia sclerotiorum, however, can utilize dead tissue. RESULTS: Inoculation of B. cinerea induced an oxidative burst and hypersensitive cell death in Arabidopsis. The degree of B. cinerea and S. sclerotiorum pathogenicity was directly dependent on the level of generation and accumulation of superoxide or hydrogen peroxide. Plant cells exhibited markers of HR death, such as nuclear condensation and induction of the HR-specific gene HSR203J. Growth of B. cinerea was suppressed in the HR-deficient mutant dnd1, and enhanced by HR caused by simultaneous infection with an avirulent strain of the bacterium Pseudomonas syringae. HR had an opposite (inhibitory) effect on a virulent (biotrophic) strain of P. syringae. Moreover, H(2)O(2) levels during HR correlated positively with B. cinerea growth but negatively with growth of virulent P. syringae. CONCLUSIONS: We show that, although hypersensitive cell death is efficient against biotrophic pathogens, it does not protect plants against infection by the necrotrophic pathogens B. cinerea and S. sclerotiorum. By contrast, B. cinerea triggers HR, which facilitates its colonization of plants. Hence, these fungi can exploit a host defense mechanism for their pathogenicity.

Arabidopsis↗

PubMed2000

Faecal occult blood in children with coeliac disease.

UNLABELLED: It has recently been suggested that in adults with coeliac disease, faecal blood loss may play a role in the development of iron deficiency. A group of 45 children diagnosed with coeliac disease during 1996 and 1997 were therefore prospectively evaluated for the presence of gluten in their diet, iron deficiency anaemia, and faecal occult blood. Sixty children admitted for elective surgery or asthma served as controls. Faecal occult blood was found in four iron deficient children on normal diet, of whom three were newly diagnosed. Occult blood loss disappeared in three of the four children when gluten was removed from their diet. Faecal occult blood was found in 26.7% of children on gluten-containing diet, but not in children on gluten-free diet (P = 0.01), or in control children (P = 0.001). CONCLUSION: Our data suggest that the incidence of occult blood loss in coeliac disease occurs mainly in newly diagnosed cases and responds to a gluten-free diet. Occult blood testing may not be warranted in the absence of iron deficiency anaemia nor in children with iron deficiency anaemia who are on a gluten-free diet.

Adolescent↗

PubMed2000

The transcriptome of Arabidopsis thaliana during systemic acquired resistance.

Infected plants undergo transcriptional reprogramming during initiation of both local defence and systemic acquired resistance (SAR). We monitored gene-expression changes in Arabidopsis thaliana under 14 different SAR-inducing or SAR-repressing conditions using a DNA microarray representing approximately 25-30% of all A. thaliana genes. We derived groups of genes with common regulation patterns, or regulons. The regulon containing PR-1, a reliable marker gene for SAR in A. thaliana, contains known PR genes and novel genes likely to function during SAR and disease resistance. We identified a common promoter element in genes of this regulon that binds members of a plant-specific transcription factor family. Our results extend expression profiling to definition of regulatory networks and gene discovery in plants.

Arabidopsis↗

PubMed2000

Chronic urticaria in children: expanding the "autoimmune kaleidoscope".

Most cases of chronic urticaria (CU) are considered idiopathic. It has recently been accepted that autoimmunity plays a critical role in the pathogenesis of CU in some of these patients. Although urticaria is common in the pediatric population, the knowledge regarding CU-associated autoimmunity is very limited. We describe the association of CU with a wide spectrum of clinical and laboratory autoimmune disorders in 2 children and emphasize the concept that CU is another manifestation of the "autoimmune kaleidoscope."

Adolescent↗

PubMed2000

Comparison of assays for anti-endomysial and anti-transglutaminase antibodies for diagnosis of pediatric celiac disease.

BACKGROUND: Anti-endomysial antibodies are sensitive and specific markers for celiac disease. This antibody has recently been identified as an antibody to tissue transglutaminase, an enzyme that cross-links and stabilizes extracellular matrix proteins. OBJECTIVES: To evaluate the clinical usefulness of an enzyme-linked immunoassay for anti-transglutaminase antibodies, and to compare the results with those of AEA, the current gold standard serological test for celiac disease. METHODS: Serum samples were collected from 33 patients with biopsy-proven celiac disease and AEA tests were performed. Control samples for anti-transglutaminase were obtained from 155 patients. An ELISA test for immunoglobulin A anti-transglutaminase utilizing guinea pig liver transglutaminase was developed and performed on all sera. Cutoff values for the test were performed using logistic regression and receiver operating curves analysis. RESULTS: An optical density cutoff value of 0.34 was established for the assay. The mean value was 0.18 +/- 0.19 optical density for controls, and 1.65 +/- 1.14 for patients with celiac disease (P < 0.001). Sensitivity and specificity of the assay were both 90%, while AEA had a sensitivity and specificity of 100% and 94%, respectively. CONCLUSIONS: A tissue transglutaminase-based ELISA test is both sensitive and specific for detection of celiac disease.

Analysis of Variance↗

PubMed1999

Programmed cell death of the dinoflagellate Peridinium gatunense is mediated by CO(2) limitation and oxidative stress.

The phytoplankton assemblage in Lake Kinneret is dominated in spring by a bloom of the dinoflagellate Peridinium gatunense, which terminates sharply in summer [1]. The pH in Peridinium patches rises during the bloom to values higher than pH9 [2] and results in CO(2) limitation. Here we show that depletion of dissolved CO(2) (CO(2(dis))) stimulated formation of reactive oxygen species (ROS) and induced cell death in both natural and cultured Peridinium populations. In contrast, addition of CO(2) prevented ROS formation. Catalase inhibited cell death in culture, implicating hydrogen peroxide (H(2)O(2)) as the active ROS. Cell death was also blocked by a cysteine protease inhibitor, E-64, a treatment which stimulated cyst formation. Intracellular ROS accumulation induced protoplast shrinkage and DNA fragmentation prior to cell death. We propose that CO(2) limitation resulted in the generation of ROS to a level that induced programmed cell death, which resembles apoptosis in animal and plant cells. Our results also indicate that cysteine protease(s) are involved in processes that determine whether a cell is destined to die or to form a cyst.

Animals↗

PubMed1999

Cervicovaginal human papillomavirus infection in human immunodeficiency virus-1 (HIV)-positive and high-risk HIV-negative women.

BACKGROUND: Human papillomavirus (HPV) infection is associated with precancerous cervical squamous intraepithelial lesions commonly seen among women infected with human immunodeficiency virus-1 (HIV). We characterized HPV infection in a large cohort of HIV-positive and HIV-negative women participating in the Women's Interagency HIV Study to determine the prevalence of and risk factors for cervicovaginal HPV infection in HIV-positive women. METHODS: HIV-positive (n = 1778) and HIV-negative (n = 500) women were tested at enrollment for the presence of HPV DNA in a cervicovaginal lavage specimen. Blood samples were tested for HIV antibody status, level of CD4-positive T cells, and HIV RNA load (copies/mL). An interview detailing risk factors was conducted. Univariate and multivariate analyses were performed. RESULTS: Compared with HIV-negative women, HIV-positive women with a CD4+ cell count of less than 200/mm3 were at the highest risk of HPV infection, regardless of HIV RNA load (odds ratio [OR] = 10.13; 95% confidence interval [CI] = 7.32-14.04), followed by women with a CD4+ count greater than 200/mm3 and an HIV RNA load greater than 20,000 copies/mL (OR = 5.78; 95% CI = 4.17-8.08) and women with a CD4+ count greater than 200/mm3 and an HIV RNA load less than 20,000 copies/mL (OR = 3.12; 95% CI = 2.36-4.12), after adjustment for other factors. Other risk factors among HIV-positive women included racial/ethnic background (African-American versus Caucasian, OR = 1.64; 95% CI = 1.19-2.28), current smoking (yes versus no; OR = 1.55; 95% CI = 1.20-1.99), and younger age (age < 30 years versus > or = 40 years; OR = 1.75; 95% CI = 1.23-2.49). CONCLUSIONS: Although the strongest risk factors of HPV infection among HIV-positive women were indicators of more advanced HIV-related disease, other factors commonly found in studies of HIV-negative women, including racial/ethnic background, current smoking, and age, were important in HIV-positive women as well.

AIDS-Related Opportunistic Infections↗