Biotinylated probes in the electrophoretic mobility shift assay to examine specific dsDNA, ssDNA or RNA-protein interactions.
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Antigens, Viral↗
Biomedical subjects
S A Schwartz
Publications and source records attributed to S A Schwartz.
Synergistic effect of cortisol and HIV-1 envelope peptide on the NK activities of normal lymphocytes.
In order to examine the potential role of stress hormones and circulating HIV-1-derived products in the progression of HIV infections, we developed an in vitro model system that investigates the effects of cortisol and HIV soluble gene products on the natural killer cell activity of normal lymphocytes. The system employs a 4-h 51Cr release assay and K562- and LAV-infected 8E5/LAV target cells. Direct addition of cortisol at 0.05, 0.1, and 0.2 microgram/ml or the HIV recombinant peptide, env-gag, at 1, 10, and 50 ng/ml separately to the mixture of effector and prelabeled target cells did not produce any significant immunoregulatory effects on NK cell activity against either target. However, cortisol or env-gag at concentrations that did not produce any inhibitory effect on NK activity when used separately, manifested significant inhibitory effects when added in combination. Suppression was evident at concentrations as low as 1 ng/ml of env-gag and 0.05 microgram/ml of cortisol and was observed at different effector:target cell ratios. Suppression was not caused by nonspecific toxicity of cortisol or HIV peptides when added in combination to the effector cells nor was due to decreased susceptibility of targets to lysis by effector cells. A non-HIV viral antigen (Rubeola virus) and another HIV-1 envelope-derived sequence (env 578-608 aa) were used as controls separately or in combination with cortisol and did not produce significant inhibition thus demonstrating the specificity of env-gag-induced inhibition. The synergistic inhibitory effect of cortisol- and HIV-derived soluble products in patients with HIV infections are consistent with a model that proposes that stress and circulating HIV-1-derived products may be involved in the progression of HIV infections.
Adult↗
Substance P induces tumor necrosis factor in an ex vivo model system.
Many studies have shown that tumor necrosis factor (TNF) is a potent soluble mediator of immunoregulation and inflammation. Neuropeptide substance P (SP) has been known to exert significant influence on production of certain inflammatory cytokine by immune cells. Immunopathogenic mechanism underlying the effect of neuropeptide substance P (SP) and the specific amino acid sequence of SP that induces TNF has not been clearly studied. Employing ex vivo and in vitro model systems, we investigated the direct effect of different sequences of SP on TNF secretion by whole blood and separated total mononuclear cells. Aliquots of blood samples (1 ml) or Ficoll-Hypaque-separated total mononuclear cells (1 x 10(6)/ml) were cultured with different concentrations of SP and its sequences (SP 1-4, SP 4-11) or vasoactive intestinal peptide (VIP) for 24 hr at 37 degrees C. Plasma samples and culture supernatants were assayed for TNF levels in a bioassay using a TNF-sensitive WEHI 164 subclone 13 cell line. Plasma from blood samples or lymphocytes treated with whole SP and SP 4-11 at 10(-7), 10(-8), and 10(-9) M concentrations induced significant production of TNF compared to negligible levels of TNF produced by SP 1-4-treated and untreated cultures. VIP at all concentrations tested did not induce TNF production and was similar to untreated control cultures. Separated mononuclear cells also produced significant levels of TNF in response to SP and SP 4-11. Anti-TNF-alpha antibodies neutralized the TNF induced by SP 4-11 in plasma. These studies suggest that an ex vivo system using whole blood may be an ideal model to study the effects of SP on TNF production. These studies also demonstrated that the TNF inducing activity of SP residues in the region containing amino acids 4 to 11.
Adult↗
MEDLINE training for medical students integrated into the clinical curriculum.
This study was initiated in response to the availabilty of unlimited access to MEDLINE via the PaperChase interface at the host institution. The goal of the study was to analyse the usage of MEDLINE by medical students during their third-year clinical clerkship in paediatrics. This was achieved by first giving them a formal demonstration of MEDLINE and then longitudinally administering a structured questionnaire at several points during their paediatric clerkship. Since medical students were required to write a thesis for this clerkship, which included an analysis of the primary literature, there was an identified need for using the system. This study analyses the students' perceptions and searching activities after formal training and upon having unlimited access to MEDLINE.
Clinical Clerkship↗
Differential effects of human immunodeficiency virus type 1 envelope protein gp120 on interferon production by mononuclear cells from adults and neonates.
While considerable progress in examining the course of human immunodeficiency virus (HIV) infection in adults has been made, a better understanding of the natural history of perinatal HIV infection remains to be obtained. Dysregulation of the production and functions of various cytokines, especially the interferons (IFNs), during HIV infections has been reported. Using an in vitro model system, we examined the effects of the HIV type 1 envelope protein, gp120 (10, 50, and 100 ng/ml), on gamma IFN (IFN-gamma) and IFN-alpha production by lymphocytes from neonates and adults and also examined the potential regulatory effects of gp120 on phorbol 12-myristate acetate (PMA)- and Sendai virus-induced IFN-gamma and IFN-alpha production by lymphocytes. PMA at a concentration of 50 ng/ml plus 50 ng of calcium ionophore A23187 per ml was used to induce IFN-gamma, while 150 hemagglutinating units of Sendai virus was used to induce IFN-alpha production. The antiviral activity of both IFN-alpha and IFN-gamma in leukocyte culture supernatants was assayed on BG-9 cells by a dye uptake technique using vesicular stomatitis virus as a challenge virus. Placental cord blood leukocyte (CBL) samples from healthy, term infants and adult peripheral blood leukocytes (APBL) produced no IFN in response to gp120. However, CBL produced significantly decreased levels of IFN-gamma compared with APBL in response to PMA plus ionophore. gp120 significantly suppressed both Sendai virus-induced IFN-alpha and PMA-induced IFN-gamma production by both CBL and APBL in a dose-dependent manner. However, gp120-induced suppression of IFN-alpha and IFN-gamma was significantly greater with CBL than with APBL. Treatment of CBL and APBL with gp120 did not induce any phenotypic alteration of the CD45 RO+ subset. Increased suppression of IFN-alpha and IFN-gamma production by gp120 in neonates may partially explain their apparent increased susceptibility to the clinical progression of HIV infections compared with that of adults.
Adult↗
Selective inhibition by alcohol and cortisol of natural killer cell activity of lymphocytes from cord blood.
1. The immunosuppressive effects of drugs such as alcohol or hormones such as cortisol may be age-related. To test this hypothesis, the authors investigated the in vitro effects of ethanol (EtOH) and cortisol on Natural Killer (NK) cell activity of lymphocytes from normal cord blood in comparison with that of lymphocytes from normal adult peripheral blood. 2. K562, an erythroleukemia cell line, was used as a target in a 4 hr 51Cr release assay. 3. Ethanol at 0.3% (V/V) and cortisol at 0.05, 0.1 and 0.2 microgram/ml concentrations, added directly to a mixture of effector and target cells significantly suppressed the NK activity of cord blood lymphocytes in a dose dependent fashion, whereas similar concentrations of either EtOH or cortisol did not manifest significant immunoregulatory effects on NK cell activity of normal adult lymphocytes. 4. Pre-treatment of the target with either EtOH or cortisol for 4 hours did not affect cytotoxicity. Inhibition of cytotoxicity was also not due to direct toxicity of effector cells because lymphocytes treated with either EtOH or cortisol showed normal 51Cr release and their viability was comparable to that of untreated control cells. 5. This suggests a selective inhibitory effect of EtOH and cortisol on NK activity of neonatal lymphocytes that may be of clinical significance.
Adult↗
MEDLINE training for medical students in the clinical curriculum.
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Clinical Clerkship↗
Recovery of infectious HIV-1 from whole saliva.
Whole saliva and serum samples were collected from 75 HIV-infected homosexual or bisexual men. Thirty-eight percent of cultured sera were positive for cell-free, infectious virus while only 1 percent of the 218 cultured whole salivas contained cell-free, infectious virus. These data support previous studies suggesting unlikely potential transmissibility of HIV infection by saliva.
Adult↗
Modulation of a human immunosuppressive lymphokine by monosaccharides.
Soluble suppressor factor (SSF) is a recently purified human lymphokine produced by peripheral blood lymphocytes (PBL) in serum-free medium as a likely consequence of an autologous mixed lymphocyte reaction. Immunoregulatory actions of SSF include suppression of: polyclonal B cell activation, proliferative responses of normal PBL, and natural killer (NK) and antibody-dependent cellular cytotoxicity. We examined the ability of the monosaccharides fucose (Fuc), galactose (Gal), glucose (Glc), and mannose (Man) to reverse SSF-mediated suppression of NK activity. Fuc and Gal can partially or completely reverse SSF-mediated suppression at four effector:target cell ratios. Man and Glc were unable to significantly reverse SSF-mediated suppression. Fuc or Gal was added to PBL at various times after addition of SSF. SSF-mediated suppression of NK cytotoxicity becomes irreversible with respect to these monosaccharides during the first 24 hr of PBL exposure to SSF. To explore the mechanism behind this block of SSF-mediated suppression. Fuc or Gal (50 mM) was cultured with PBL for 24 hr before addition of SSF, or with SSF for 24 hr before addition to PBL. Our experiments indicate that SSF is directly interacting with these monosaccharides, and may function by recognizing specific sugar moieties on the surface of effector cells.
Chromatography, Affinity↗
Relapse in sexual behavior among homosexual men: a 2-year follow-up from the Chicago MACS/CCS.
Serial biannual cross-sectional assessments of HIV sexual risk indicated a consistent increase in safer sexual practices among homosexual men participating in the Chicago-Multicenter AIDS Cohort Study (MACS)/Coping and Change Study (CCS) in 1986-1988. Safer sexual practices were achieved by avoidance of anal sex and less often by consistent use of condoms. Longitudinal patterns of variability in individual behavior were also assessed. After 1 year of follow-up, 53% of the participants maintained safer practices in receptive anal sex, 6% maintained unsafe practices, while 31% relapsed at least once. After 2 years, 45% maintained safer practices, 3% maintained unsafe practices and 47% relapsed at least once. Similar trends were observed in insertive anal sex.
Chicago↗
Intravenous immunoglobulin (IVIG) for the therapy of autoimmune disorders.
The weight of evidence from numerous clinical studies supports the use of IVIG, particularly at higher doses, in the treatment of a wide range of autoimmune disorders. Extensive experience has documented the safety of IVIG therapy but its present relatively high cost necessitates firmly establishing its efficacy. There is an acute need to define those disease states where IVIG is indicated and effective. Large-scale, possibly multicentered, clinical trials employing rigorous controls will resolve these questions. Concurrent fundamental immunologic studies will elucidate the mechanisms underlying the clinical effects. We are experiencing an exciting new era of effective immunotherapies and intravenous gamma-globulin preparations have already secured an important place in the therapeutic armamentarium. While one must guard against unsubstantiated applications, critical exploration of new uses for this unique product is warranted.
Autoimmune Diseases↗
Effects of alcohol and nicotine on cytotoxic functions of human lymphocytes.
The in vitro effects of the recreational drugs, ethanol (EtOH) and nicotine, on natural killer (NK) antibody-dependent cellular cytotoxic (ADCC) and lymphokine-activated killer (LAK) cell activities on normal lymphocytes were investigated. Lymphocytes precultured with EtOH at concentrations of 0.4 and 0.6% (v/v) produced significant suppression of NK and ADCC activities. In target-binding assays, EtOH decreased the target-binding capacity of effector cells. EtOH also inhibited the activities of Percoll-separated, NK-enriched large granular lymphocytes. EtOH-induced inhibition of NK activity could be reversed by incubating lymphocytes for 1 hr with interferon. The generation and lytic capacity of LAK cells was also significantly depressed by EtOH when added at the initiation of culture. Nicotine at concentrations of 5 and 10 micrograms/ml, when added directly to mixtures of effector and target cells, produced significant inhibition of NK activity. Nicotine (2 micrograms/ml) and EtOH (0.01, 0.1, and 0.2%) at noninhibitory concentrations when added separately, showed significant suppression of NK activity when used in combination. Pretreatment of target cells with either EtOH or nicotine for 4 hr did not affect cytotoxic activity. Inhibition of cytotoxicity was also not due to direct toxicity of effector cells because lymphocytes treated with either EtOH or nicotine showed normal 51Cr release and their viability was comparable to that of untreated control cells. These studies demonstrate that EtOH and nicotine have significant immunomodulatory effects on the cytotoxic activities of human lymphocytes which may be of clinical relevance.
Antibody-Dependent Cell Cytotoxicity↗
Immunoregulatory effects of alcohol on lymphocyte responses to human immunodeficiency virus proteins.
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Alcoholism↗
Flow cytometric analysis of lymphocyte subpopulations in infants with congenital heart disease.
Premortem diagnosis of the DiGeorge syndrome and its partial variants relies on the demonstration of a primary defect in cell-mediated immunity, generally in the setting of an infant with congenital heart disease, hypocalcemia, absence of a thymic shadow, and typical dysmorphic features. Although T-cell enumeration is considered a vital part of the diagnostic evaluation, no studies to date have addressed the issue of appropriate reference data in infants with congenital heart disease. We therefore undertook a prospective descriptive study of lymphocyte phenotype analysis in 27 nontransfused infants undergoing diagnostic cardiac catheterization. Striking differences were seen between patients and adult controls in means percentages and numbers of most lymphocyte subsets analyzed. Few differences were found in comparing the patient data to values for age-matched control infants without heart disease. The data are discussed with reference to published values for patients with partial DiGeorge syndrome. It is concluded that lymphocyte phenotype analysis in the diagnostic evaluation of patients with suspected DiGeorge syndrome must utilize appropriate reference values.
Antigens, Differentiation↗
Use of intravenous immune globulin in the treatment of seizure disorders.
Recurrent seizures are a significant cause of childhood morbidity. Often the underlying pathogenesis is unknown. Studies from several laboratories have suggested a relationship between perturbations of humoral immunity and clinical epilepsy. Brain-specific antigens have been observed in the systemic circulation after brain injury. This can be followed by the appearance of antibodies to neuronal tissues in both serum and cerebrospinal fluid. Moreover, there appears to be disproportionate representation of persons with coexisting humoral immune deficiencies among patients with chronic epilepsy. Interestingly, a potent immunosuppressant, adrenocorticotropic hormone, has long been the principal treatment for infantile spasms. Given this body of information associating humoral immunity with recurrent seizures, several investigators have recently attempted to treat intractable childhood epilepsy with high-dose intravenous immune globulin. Although the number of patients treated is small and it is not possible to make comparisons between individual studies, nevertheless the results have been encouraging. Five patients with intractable seizures who failed to respond to conventional therapy were treated with an outpatient regimen of intravenous immune globulin (1 gm/kg/day) for 2 days. Two patients showed significant clinical improvement while a third had an equivocal response. Immunologic analysis of these patients before therapy revealed a surprisingly high incidence of immune abnormalities. We conclude that intravenous immune globulin may be useful in the treatment of selected patients with chronic epilepsy unresponsive to anticonvulsants.
Adolescent↗
Apical closure in the presence of pulpal necrosis: report of two cases.
This article reports apical closure in two cases in which necrotic pulps were present and no endodontic treatment was performed prior to closure. Possible mechanisms for the occurrence are suggested.
Adolescent↗
Recombinant interleukin 2 therapy in severe combined immunodeficiency disease.
Severe combined immunodeficiency disease (SCID) is a congenital disorder of severe B- and T-lymphocyte dysfunction in which several pathogenic mechanisms have been identified. The present study describes a female child with SCID who had a primary defect in the ability of T cells to secrete interleukin 2 (IL-2). B- and T-cell numbers were normal, but their functions were severely deficient. Mitogen and antigen-driven lymphoproliferative responses were diminished but were correctable in vitro with recombinant IL-2 (rIL-2). The patient's phytohemagglutinin-stimulated lymphocytes expressed IL-2 receptors normally. Despite the presence of the gene for IL-2, the patient's cells were grossly deficient in messenger RNA for IL-2 and endogenous IL-2 production. Pokeweed mitogen-driven B-cell differentiation was decreased and was not corrected by the addition of normal T cells to the B cells. Two attempts at immune reconstitution by haploidentical bone marrow transplantation failed. Therapy with rIL-2 (30,000 units/kg, given daily i.v.) resulted in marked clinical improvement as well in improved T-cell functions. The child, now 3 yr old, has been on rIL-2 therapy for 2 yr and receives rIL-2 (30,000 units/kg) three times weekly at home. This case study points to a new direction in the treatment of such disorders with rIL-2.
B-Lymphocytes↗
Ineffectiveness of postexposure prophylaxis of rhinovirus infection with low-dose intranasal alpha 2b interferon in families.
Past studies conducted in Australian and American families have demonstrated that alpha 2b interferon (IFN) is effective in preventing rhinovirus-associated illnesses in exposed family members. IFN had been used by intranasal application for 7 days after exposure (5 x 10(6) IU/day). We used the same approach but with only 5 days of spraying (5 x 10(6) IU on day 1 and 2.5 x 10(6) IU on each subsequent day). This amount has been effective in studies involving seasonal prophylaxis. During the study period, a total of 178 rhinoviruses were isolated from the 199 enrolled families in Tecumseh, Mich. There were 434 courses of IFN use and 434 courses of placebo use. Although rhinoviruses were less frequently isolated from those using IFN than those using the placebo, no differences favoring IFN treatment could be found in any of the symptomatic episodes. In fact, more episodes were observed in IFN recipients than in placebo recipients, although the differences were not statistically significant. Additionally, there was no evidence of modification of the severity of episodes of illness. It was concluded that prevention of rhinovirus illness episodes postexposure required a dosage of at least 5 x 10(6) IU of IFN-alpha 2b.
Administration, Intranasal↗