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Biomedical subjects

L S Young

Publications and source records attributed to L S Young.

At least 19 recordsLinked to original sources
PubMed1992

Tumor necrosis factor alpha stimulates mycobactericidal/mycobacteriostatic activity in human macrophages by a protein kinase C-independent pathway.

Tumor necrosis factor (TNF) is a 17-kDa protein produced by endotoxin-stimulated macrophages. We have demonstrated that recombinant human TNF activates human macrophages to kill intracellular bacteria of the Mycobacterium avium complex (MAC) in a dose-related manner. TNF also primed macrophages to produce superoxide anion (O2-) following treatment with phorbol esther PMA (0.1 micrograms/ml). To investigate the intracellular pathway involved in the TNF-mediated activation of mycobacteriostatic/mycobactericidal activity in macrophages, we used two different protein kinase C (PKC) inhibitors: H7 (10(-5)-10(7) M) and staurosporine (10(-7)-10(-9) M). Mellitin (1 and 100 mM) was used as a calmodulin inhibitor. Human peripheral blood-derived macrophages cultured for 7 days were treated with H7, mellitin, or staurosporine for 1 hr prior to incubation with TNF (10(3) U/ml). Twenty-four hours after treatment with TNF the O2- release was measured spectrophotometrically following exposure to PMA. Macrophages were infected with MAC and the viable intracellular bacilli were quantitated following 4 days of treatment with TNF. All PKC inhibitors suppressed O2- production after incubation with PMA. However, treatment with either PKC or calmodulin inhibitors did not influence the intracellular killing of M. avium by TNF-stimulated macrophages. Exposure of the macrophages to cGMP inhibitor but not to cAMP inhibitor significantly impaired the response to the stimulation with TNF. In contrast, incubation of macrophages with protein kinase A (PKA) had no effect on TNF-mediated mycobacteriostatic/mycobactericidal activity. These results suggest that the TNF-mediated mycobactericidal activity in cultured macrophages probably occurs by a PKC-independent mechanism.

Calmodulin↗
PubMed1992

Distribution and phenotype of Epstein-Barr virus-harboring cells in Hodgkin's disease.

Distribution and phenotype of Epstein-Barr virus (EBV)-harboring cells were determined in Hodgkin's disease (HD) biopsies by in situ hybridization with [35S]-labeled RNA probes specific for the small EBV-encoded nuclear RNAs, EBER1 and EBER2, in some instances preceded by immunohistology for CD20, CD30, CD45RO, and CD68 antigens, the T-cell receptor beta-chain, and latent membrane antigen (LMP) of EBV. Twenty-three of 46 HD cases displayed EBER transcripts in all Hodgkin and Reed-Sternberg (H-RS) cells, and 18 of these cases showed LMP expression exclusively in neoplastic cells. EBER+ small reactive cells were present in 39 cases in low numbers, and in three cases in abundance. Thus, presence of H-RS cells with or without LMP expression was not accompanied by an unrestricted proliferation of reactive EBER+/LMP- lymphoid cells in the majority of HD patients. Simultaneous in situ hybridization with [35S]-labeled immunoglobulin light chain (IgLC) gene probes and nonisotopically labeled EBER probe showed a phenotype of mature B lymphocytes and a polyclonal composition for a large proportion of the EBER+ small cells. However, in contrast to noninfected cells, CD20 expression was not detectable in many of these cells, which may indicate downregulation of certain differentiation antigens in latently EBV-infected small lymphoid cells in vivo.

Antigens, CD↗
PubMed1992

Clinical and metabolic efficacy of glutamine-supplemented parenteral nutrition after bone marrow transplantation. A randomized, double-blind, controlled study.

OBJECTIVE: To determine whether glutamine-supplemented parenteral nutrition improves nitrogen retention and reduces hospital morbidity compared with standard parenteral nutrition after bone marrow transplantation. DESIGN: Double-blind, randomized, controlled clinical trial. SETTING: University teaching hospital. PATIENTS: Forty-five adults receiving allogeneic bone marrow transplants for hematologic malignancies. INTERVENTION: Parenteral nutrition was initiated the day after bone marrow transplantation (day 1). The experimental solution was supplemented with L-glutamine (0.57 g/kg body weight per day) and provided estimated requirements for energy and protein. The control solution was a standard, glutamine-free, isonitrogenous, isocaloric formula. MEASUREMENTS: Nitrogen balance was determined between days 4 and 11 in the initial 23 patients. The incidence of clinical infection and microbial colonization, time until bone marrow engraftment, indices of clinical care, and other data related to hospital morbidity were recorded for all patients. RESULTS: The glutamine-supplemented patients (n = 24) were clinically similar to the controls (n = 21) at entry. Nutrient intake was similar in both groups; however, nitrogen balance was improved in the glutamine-supplemented patients relative to the controls (-1.4 +/- 0.5 g/d compared with -4.2 +/- 1.2; P = 0.002). Fewer experimental patients developed clinical infection (three compared with nine in the control group; P = 0.041), and the incidence of microbial colonization was also significantly reduced. Hospital stay was shortened in patients receiving glutamine supplementation (29 +/- 1 d compared with 36 +/- 2 d; P = 0.017). CONCLUSION: Patients receiving glutamine-supplemented parenteral nutrition after bone marrow transplantation had improved nitrogen balance, a diminished incidence of clinical infection, lower rates of microbial colonization, and shortened hospital stay compared with patients receiving standard parenteral nutrition. These effects occurred despite no differences between groups in the incidence of fever, antibiotic requirements, or time to neutrophil engraftment.

Adult↗
PubMed1992

Patterns of Epstein-Barr virus infection in non-neoplastic lymphoid tissue.

Taking advantage of the abundant expression of the small Epstein-Barr virus (EBV)-encoded RNAs (EBERs) in latently infected cells, we have analyzed 72 normal and hyperplastic lymph nodes and three tonsils of acute infectious mononucleosis (IM) for the presence and distribution of EBV+ cells using EBER-specific in situ hybridization, in some cases combined with immunohistologic demonstration of cell type-characteristic antigens. In IM, large numbers of EBV+ lymphoid B blasts were detectable in extrafollicular areas, whereas germinal centers were generally free of EBV+ cells. In reactive lymph nodes, the frequency of EBV+ cells varied with the degree of lymphoid hyperplasia and underlying immune status. The lowest numbers of EBV+ cells were detected in nonactivated lymph nodes and highest in human immunodeficiency virus-associated lymphadenopathy. If present in these lymph nodes, EBV+ cells were almost exclusively localized to extrafollicular areas, as also observed in IM. However, in contrast to IM, these cells were mainly small lymphocytes. Furthermore, in some instances, occasional scattered EBV+ cells were seen within germinal centers, and in two cases diffuse expansions of EBV+ cells occurred within a single germinal center each, indicating that under certain circumstances EBV+ B lymphocytes may participate in physiologic germinal center reactions. These findings reflect the interference of EBV with physiologic lymphoid differentiation pathways and provide a link to EBV-associated malignant lymphomas with a postulated origin from germinal center cells.

B-Lymphocytes↗
PubMed1992

Elevated expression of ICAM1 (CD54) and minimal expression of LFA3 (CD58) in Epstein-Barr-virus-positive nasopharyngeal carcinoma cells.

Undifferentiated nasopharyngeal carcinoma (NPC) is a remarkable entity among human tumors because of its constant association with the Epstein-Barr virus (EBV). Malignant epithelial cells harbor the EBV genome and often express at least 2 species of latent EBV protein (EBNA1 and LMP1). Despite the massive presence of tumor-infiltrating lymphocytes, NPC cells obviously escape immune surveillance directed to EBV antigens. Previous investigations carried out on EBV-positive Burkitt lymphoma (BL) cells have shown that this fact may be partially accounted for by a lack of expression of ICAM1 (CD54) and LFA3 (CD58). ICAM1 and LFA3 have therefore been investigated in fresh NPC biopsies and transplanted NPCs. With only 1 exception out of 9 cases, NPC cells appear to express high levels of ICAM1 and low levels of LFA3. This is a complete inversion of the pattern observed in normal epithelial cells in vivo. Additional investigations will be required to determine to what extent these characteristics affect T-cell interactions with NPC cells, specially in the process of EBV-antigen recognition.

Animals↗
PubMed1992

Epstein-Barr virus infection and replication in a human epithelial cell system.

Epstein-Barr virus, a human herpesvirus with oncogenic potential, infects two target tissues in vivo: B lymphocytes, where the infection is largely non-productive, and stratified squamous epithelium in which virus replication occurs. The interaction with B cells, initiated through virus binding to the B-cell surface molecule CR2 (ref. 4), has been studied in vitro and the virus 'latent' genes associated with B-cell growth transformation defined. By comparison, viral infection of epithelium remains poorly understood, reflecting the lack of an appropriate cell-culture model. Here we describe the development of such a model using as targets CR2-expressing transfected cells of two independent human epithelial lines. A high proportion of these cells bind virus and become actively infected, expressing the small EBER RNAs (small non-polyadenylated virus-coded RNAs) and the Epstein-Barr nuclear antigen 1 but not other latent proteins; thereafter, under conditions favouring epithelial differentiation, up to 30% of the cells can be induced to enter virus productive cycle with some progressing to full virus replication. We find significant differences between laboratory virus strains in their ability to infect epithelium that do not correlate with their B-cell growth-transforming activity.

Antigens, Differentiation, B-Lymphocyte↗
PubMed1992

Immunohistochemical demonstration of the Epstein-Barr virus-encoded latent membrane protein in paraffin sections of Hodgkin's disease.

Paraffin sections from 46 cases of Hodgkin's disease were examined for the presence of the Epstein-Barr virus (EBV)-encoded latent membrane protein (LMP) using a sensitive (double layer alkaline phosphatase-anti-alkaline phosphatase) immunohistochemical method. LMP was detected in 22 cases, the majority of positive cases being of nodular sclerosis (12/24), mixed cellularity (6/7), and lymphocyte depletion (3/3) subtypes. Only one of 12 cases of lymphocyte predominant disease was positive. In all cases, reactivity was confined to Hodgkin's and Reed-Sternberg cells. These results provide further evidence for an association between EBV and Hodgkin's disease and indicate that LMP may be readily detected in archival material.

Herpesvirus 4, Human↗
PubMed1992

Three transcriptionally distinct forms of Epstein-Barr virus latency in somatic cell hybrids: cell phenotype dependence of virus promoter usage.

Phenotypically distinct human B cell lines display two transcriptionally distinct forms of Epstein-Barr virus (EBV) latency. Latency I (Lat I) in group I Burkitt's lymphoma (BL) cell lines is characterized by selective expression of the virus-coded nuclear antigen EBNA 1 from a uniquely spliced mRNA driven by the Fp promoter. Latency III (Lat III) in group III BL and EBV-transformed lymphoblastoid cell lines (LCLs) is characterized by expression of EBNAs 1, 2, 3a, 3b, 3c, and -LP from mRNAs driven by the Cp or Wp promoter and of the latent membrane proteins (LMPs 1, 2A, and 2B) from mRNAs driven by the LMP promoters. Here we have altered the group I BL and LCL phenotypes by cell hybridization and screened for attendant changes in EBV latency by PCR analysis of viral mRNAs and immunoblotting of viral proteins. Fusion of group I BL cells with LCLs activated the BL virus genome from a Lat I to Lat III pattern of gene expression. Fusion of LCLs with nonlymphoid lines repressed virus gene expression from Lat III either to Lat I or to another form of latency (Lat II) hitherto not seen in vitro and characterized by selective expression of the Fp-driven EBNA 1 mRNA and of the LMP 1, 2A, and 2B transcripts. There are therefore three forms of EBV latency which can be interconverted by altering cellular phenotype and thereby virus promoter usage.

Antigens, Viral↗
PubMed1992

Evaluation of new anti-infective drugs for the treatment of febrile episodes in neutropenic patients. Infectious Diseases Society of America and the Food and Drug Administration.

The use of empirical antimicrobial therapy has significantly reduced the morbidity and mortality associated with untreated infections in febrile neutropenic patients. This guideline describes clinical trials of the safety and efficacy of new antimicrobial drugs in this population of patients. Fever and neutropenia should be precisely defined in each protocol. Patients should be randomized to treatment with a new or active-control drug regimen, stratified on the basis of type of cancer and age, and treated until resolution--as defined in the protocol--is attained. Outcome should be assessed both for cases with a defined microbial etiology and for those without. Final microbiological outcome is important for cases with identified pathogens, but clinical outcome is paramount.

Anti-Infective Agents↗
PubMed1992

An animal model of Mycobacterium avium complex disseminated infection after colonization of the intestinal tract.

Mycobacterium avium complex infections occur in 30%-80% of patients with AIDS. Recent evidence supports the gastrointestinal tract as the source of M. avium. Although a reproducible animal model exists, a model more closely resembling the infection in AIDS patients is needed to answer pertinent questions regarding response to therapy and prophylaxis. Beige mice were infected orally (1 x 10(8) or 1 x 10(4) cfu, five doses), and consistent, reproducible disseminated infections after 4 and 8 weeks, respectively, were obtained. Bacteremia was observed in none to 70% of the animals depending on the strain used, and mortality ranged from none to 33%, also depending on the strain used. Concomitant ingestion of ethanol (4% of daily dietary calories) was associated with a significant increase in the number of viable bacteria recovered from liver, spleen, and appendix compared with animals not receiving ethanol. The orally infected animal model closely resembles M. avium infection in humans and may be important in investigating prophylaxis and therapy of this infection.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Postantibiotic effect of amikacin and rifapentine against Mycobacterium avium complex.

Postantibiotic effect (PAE) has received little attention in the therapy of chronic intracellular infections, such as those caused by mycobacteria. Amikacin is active therapeutically against Mycobacterium avium complex, even though serum levels exceed the MIC for only a few hours. To determine the PAE of amikacin and rifapentine for M. avium, bacteria were exposed to concentrations of 1x, 4x, and 10x the MIC of each drug for up to 120 min. Regrowth of M. avium was compared with similarly diluted untreated cultures. No PAE was observed on an inoculum of 10(4) bacteria when rifapentine was used at 5x MIC, although a slight inhibition of growth was obtained at 10x MIC for 2 h. For amikacin, PAE was observed up to 48 h at concentrations of 4x and 8x MIC and exposure times of 30-120 min. A PAE of 22 h was seen with 10(7) cfu of M. avium during incubation for 30 min with amikacin at 4x MIC. These results show that amikacin, unlike rifapentine, has a long PAE against M. avium.

Amikacin↗
PubMed1992

Interleukin-6 antagonizes tumor necrosis factor-mediated mycobacteriostatic and mycobactericidal activities in macrophages.

Interleukin-6 (IL-6) is a cytokine produced by a number of cells, including macrophages, and is directly involved in the inflammatory response. The production of IL-6 can be stimulated by monokines such as IL-1 and tumor necrosis factor (TNF). Mycobacterium avium complex organisms frequently cause disseminated disease in patients with AIDS. M. avium is an intracellular bacterium that that mainly infects macrophages. Treatment of M. avium-infected macrophage monolayers with recombinant IL-6 decreased the ability of TNF to activate cultured macrophages to inhibit growth of or kill intracellular M. avium (68% +/- 14% decrease in intracellular killing compared with that in monolayers not treated with IL-6). To further evaluate whether this effect was dependent on the down regulation of membrane receptors to TNF, we examined 125I-TNF binding to macrophages previously exposed to IL-6: the expression of TNF receptors was decreased by 78% +/- 9%. The effect of IL-6 on TNF receptors was observed after 4 h and was reversible. Infection of macrophages with different M. avium serovars was associated with release of IL-6, and IL-6 production peaked at 48 h after infection in concentrations ranging from 328 +/- 87 ng/10(5) cells to 907 +/- 224 ng/10(5) cells. IL-6 did not have any influence on the rate of growth of the tested strains of M. avium within or outside macrophages. These results suggest that release of IL-6 by M. avium-infected macrophages may influence the host's immune response and the outcome of the disease.

Humans↗
PubMed1992

Epstein-Barr virus latent gene transcription in nasopharyngeal carcinoma cells: coexpression of EBNA1, LMP1, and LMP2 transcripts.

Epstein-Barr virus (EBV) genome-positive nasopharyngeal carcinomas (NPCs) regularly express the virus-coded nuclear antigen EBNA1, but not other EBNAs, and a subset of tumors also appear to be latent membrane protein LMP1 positive; the status of NPCs with respect to a second virus-coded latent membrane protein LMP2 is unknown. In the present work the EBV-NPC cell interaction has been analyzed at the RNA level with reverse transcription and polymerase chain reaction-based amplification to detect specific latent viral mRNAs. All four transplantable NPC cell lines studied and 17 of 18 fresh snap-frozen NPC biopsy specimens expressed an EBNA1 mRNA with a BamHI Q/U/K splice structure exactly like that recently identified in group I Burkitt's lymphoma (BL) cell lines and shown to be driven from a novel viral promoter, Fp. The BamHI Y3/U/K-spliced EBNA1 mRNA characteristic of virus-transformed B-lymphoblastoid cell lines (LCLs) was never found in NPCs. These same NPC biopsy specimens were then analyzed for evidence of the various LMP transcripts which are constitutively expressed in LCLs but down-regulated in BL cells. While only 3 of 18 tumors gave a clear LMP1 mRNA-specific signal after first-round amplification with either of two sets of polymerase chain reaction primers, the majority proved to be LMP1 mRNA positive after second-round amplification with nested primers. A rather similar pattern of results was obtained with respect to LMP2B mRNA expression, such transcripts being detectable only in a subset of tumors, and then at apparently low levels. In contrast, clear evidence of LMP2A mRNA expression was obtained in 17 of 17 fresh biopsies. The predominant form of EBV infection in NPCs, with coexpression of EBNA1 and LMP mRNAs, is therefore quite distinct from that seen in BL cells (in which EBNA1 is the only expressed mRNA) and in LCL cells (in which all six EBNA and three LMP transcripts are present). This third form of EBV latency may not be restricted to NPC but may have more general relevance in the context of EBV infection in vivo.

Antigens, Viral↗
PubMed1992

Recombinant human growth hormone enhances the metabolic efficacy of parenteral nutrition: a double-blind, randomized controlled study.

This multicenter, randomized, double-blind study was performed to investigate whether recombinant GH improves the efficacy of total parenteral nutrition (TPN). Fifteen stable patients requiring parenteral feeding due to gastrointestinal/pancreatic disease were studied. Constant maintenance TPN providing approximately 30 kcal/kg day and approximately 1.6 g protein/kg.day was administered during an initial 7-day baseline period. After randomization, daily sc injections of saline (control, n = 9) or GH (10 mg/day, n = 6) were administered a 14-day treatment period as nutrient intake remained constant. Elemental balances for nitrogen (N), potassium (K), phosphorus (P), and sodium (Na) were determined daily and serial blood indices, vital signs, and other clinical parameters were monitored. Nutrient balances approached equilibrium during the baseline week in both groups. With GH administration, a significant increase in N, K, and P balance occurred; in contrast, nutrient balances did not change significantly from baseline values in control patients. The cumulative change (delta) in nutrient balances from the baseline week was also significantly greater in the GH-treated patients (delta N: control+2 +/- 7 g vs. GH+36 +/- 6. g, P less than 0.005; delta K:+57 +/- 45 mmol vs.+199 +/- 19 mmol, P less than 0.03; delta P: -27 +/- 30 mmol vs. +91 +/- 69 mmol, P less than 0.02). Plasma insulin-like growth factor-I concentrations rose 5-fold and serum cholesterol rose slightly with GH; no other significant change in group mean blood values occurred. One patient receiving GH and chronic prednisone therapy developed moderate hyperglycemia and mild peripheral edema; no other deleterious effects attributable to GH were observed. GH was well tolerated and significantly enhanced nutrient retention compared to standard parenteral feeding alone. GH improves the efficacy of parenteral nutrient utilization in patients requiring TPN.

Adolescent↗
PubMed1992

Expression of Epstein-Barr virus genes and of lymphocyte activation molecules in undifferentiated nasopharyngeal carcinomas.

Previous studies investigating the role of Epstein-Barr virus (EBV) in undifferentiated nasopharyngeal carcinoma (NPC) have been performed on extracts from biopsies. The authors analyzed expression and localization of viral gene products in 18 undifferentiated NPCs at the cellular level using immunohistology and in situ hybridization. All cases were EBV-positive. The small nuclear EBV-encoded RNAs, EBERs, were regularly expressed whereas the latent membrane protein, LMP1, and EBV was detectable only in four cases (22%) and the nuclear antigen 2 was not detectable. The BZLF-1 protein of EBV which disrupts viral latency, was not detectable, confirming that the virus is latent in the tumor cells. Although the expression of the CD23 antigen in transplantable NPCs has been reported, our study demonstrates that expression of this antigen in human undifferentiated NPCs is rare. In contrast, almost all cases expressed the CDw70 antigen. Since in normal tissues this antigen is present only in activated lymphoid blasts, this finding may be relevant for the differential diagnosis of undifferentiated NPCs.

Antibodies, Monoclonal↗