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Biomedical subjects

G Freeman

Publications and source records attributed to G Freeman.

At least 19 recordsLinked to original sources
PubMed1992

Ineffectiveness of AIDS education and HIV antibody testing in reducing high-risk behaviors among injection drug users.

The effectiveness of education in reducing high-risk human immunodeficiency virus (HIV) transmission behaviors was examined in 313 injection drug users. Involvement in high-risk behaviors was assessed via structured interview at study entry and 4 months following the intervention. Subjects were randomly assigned to (1) AIDS education, (2) AIDS education with optional HIV antibody testing, or (3) a wait list. The sample as a whole decreased its involvement in high-risk behaviors, but there were no significant differences as a function of experimental group assignment.

AIDS Serodiagnosis↗
PubMed1991

All advanced stage non-Hodgkin's lymphomas with a polymerase chain reaction amplifiable breakpoint of bcl-2 have residual cells containing the bcl-2 rearrangement at evaluation and after treatment.

Polymerase chain reaction (PCR) of bcl-2 provides an extremely sensitive method to detect minimal disease in approximately 50% of patients with non-Hodgkin's lymphomas (NHL). In an attempt to determine the clinical usefulness of this technique, we examined the bone marrow (BM) of 152 patients with advanced-stage NHL at the time of evaluation and after induction or salvage chemotherapy before autologous BM transplantation. The BM proved to be an accessible and reproducible tissue source to determine PCR positivity because all of the 102 patients examined had the same PCR-amplifiable breakpoint in their BM and lymph node. At the time of evaluation, PCR analysis in advanced-stage NHL patients added little additional information to morphologic analysis because each technique identified BM infiltration in approximately 70% of patients. PCR was significantly more useful in determining BM infiltration after induction or salvage therapy. At that time, approximately 50% of patients had morphologically normal BM, whereas PCR analysis remained positive in 100% of those with an amplifiable breakpoint. These observations were confirmed in a clinical trial attempting to induce remission in previously untreated low-grade advanced-stage NHL patients. In this series, PCR was positive in all patients after treatment although the BM was histologically uninvolved in 50% of cases, showing that conventional therapy did not eradicate bcl-2-positive cells.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1991

Follicular dendritic cells contain a unique gene repertoire demonstrated by single-cell polymerase chain reaction.

Follicular dendritic cells (FDCs) form a dense network between B cells within the germinal center and are thought to be an important component of this B-cell microenvironment. Previous immunophenotypic studies have been inconclusive in determining the cellular origin of FDCs. Gene coexpression within individual and highly enriched FDCs was determined using polymerase chain reaction. FDCs contain a very restricted mRNA pattern with high levels of message for the C3d receptor (CR2, Epstein Barr-virus/EBV receptor, CD21) and lack of mRNA for CD20, CD45, CD4, fibronectin, and platelet-derived growth factor receptor alpha and beta. These observations are consistent with the hypothesis that FDCs may not be of classical hematopoietic or fibroblastic origin. The absence of interferon-gamma, tumor necrosis factor-alpha, interleukin-3, and interleukin-6 mRNA provides preliminary evidence that these cells might produce only a very restricted set of cytokines limited to the germinal center.

Antigens, CD↗
PubMed1991

The bases for and timing of regional specification during larval development in Phoronis.

A fate map has been constructed for Phoronis vancouverensis. The animal pole of the egg gives rise to the apical plate in the hood of the actinotroch larva. The vegetal pole of the egg marks the site of gastrulation. During the initiation of gastrulation the cells of the animal pole of the embryo are directly opposite those at the vegetal pole of the embryo. The plane of the first cleavage always goes through the animal-vegetal pole of the egg. In about 70% of the cases the plane of the first cleavage is perpendicular to the future anterior-posterior axis of the actinotroch larva; in the remaining cases the plane of the first cleavage is either oblique with reference to, or occurs along, the future anterior-posterior axis of the larva. Following gastrulation catecholamine-containing cells first make their appearance in the apical plate and gut cells first produce esterase. The timing of regional specification in these embryos has been examined by isolating animal or vegetal, anterior or posterior, or lateral regions at different time periods between the initiation of cleavage and gastrulation and examining their ability to differentiate. Animal halves isolated from early cleavage through late blastula stages do not gastrulate and do not form catecholamine-containing cells. When animal halves are isolated with endoderm during gastrulation, they differentiate catecholamine-containing cells. Vegetal halves isolated at the 8- to 16-cell stage gastrulate and form normal actinotroch larvae with esterase-positive gut and catecholamine-containing apical plate cells. When this same region is isolated at blastula stages it does not gastrulate and does not differentiate these cell types. Vegetal halves isolated during gastrulation subsequently form esterase-positive gut cells, but they do not form catecholamine-containing apical plate cells. When presumptive anterior, posterior, or lateral halves are isolated from early cleavage through blastula stages, each half forms a normal actinotroch larva. Lateral halves isolated during gastrulation also form normal larvae. Anterior halves isolated during late gastrulation differentiate only the anterior end of the actinotroch larva. These isolates have a hood with catecholamine-containing apical plate cells and the first part of an esterase-positive gut but lack the anlagen of the intestine and protonephridia. Posterior halves isolated during late gastrulation differentiate only the posterior end of the actinotroch which lacks a hood with catecholamine-containing cells but has an esterase-positive gut, protonephridia, and the anlagen of the intestine.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1991

Needle-use practices among intravenous drug users in an area where needle purchase is legal.

Needle-use practices of intravenous drug users (IVDUs) were examined in a region (Seattle, King Country, Washington State, USA) where needle purchase is legal. IVDUs in treatment (n = 313) were administered extensive structured interviews concerning drug and injection equipment-use practices. Of the 80.2% reporting intravenous drug use in the previous year, 78.3% reported sharing needles. Of the 47.7% reporting intravenous use in the previous 30 days, only 40.5% shared needles, with 59.3% sharing with only one other person. Most needle-sharing partners were very well known (63%) or well known (17%) to the subjects. The most frequent method for obtaining needles was 'buying in a drug store', ranked first by 65% of the sample. Subjects whose primary source was 'buying in a drug store' shared equipment less frequently during drug-use events in the previous year (mean: 16.2%) than those with other primary sources (mean: 28.5%). Compared with findings from other regions where needle purchase and possession are illegal without a prescription, fewer subjects in the current investigation shared needles, and those who did shared with a smaller number of people. The apparent association between legalized injection equipment and reduced sharing of equipment among IVDUs should be further examined in longitudinal studies of needle-sharing before and after legalization is instituted.

Adult↗
PubMed1991

Sexual behaviors of intravenous drug users in treatment.

Sexual behaviors of a group of 313 intravenous drug users (IVDUs) (225 men, 88 women) were assessed by a structured interview at the start of an AIDS prevention project. Although the majority were celibate or monogamous during the prior year (men 52.5%, women 64.3%), many IVDUs had multiple sexual partners in that time, including 19.6% of men and 7.2% of women reporting five or more. Married male and female IVDUs were more likely to have multiple sexual partners than married people in general population samples. Only 38.5% of male and 35.4% of female IVDUs ever used condoms during the previous 5 years. Percentage of sexual encounters in which condoms were used correlated significantly with the number of partners for women (r = 0.37, p less than 0.01), but not for men (r = 0.03, ns). Use of intravenous drugs in the prior year, sharing of needles, use of stimulants, exchange of sex for money or drugs, and combining sexual events with drug use were all associated with greater numbers of sexual partners. A subset of male IVDUs engages in the dual-risk behaviors of needle sharing and unprotected intercourse with multiple partners. This group could act as a highly efficient vector for human immunodeficiency virus transmission and should become a focus of intensive preventive intervention.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Acute effects of aspartame on concentrations of brain amines and their metabolites in selected brain regions of Fischer 344 and Sprague-Dawley rats.

This study is the first in a series to define a rodent model to document the effects of amino acid-modulating compounds on central neurotransmitter function. A time-response curve for a single dose of orally intubated aspartame was determined in male Fischer 344 and Sprague-Dawley rats. Regional brain concentrations of norepinephrine (NE), dopamine (DA), serotonin (5-HT) and their metabolites were analyzed in the hypothalamus, cerebellum, pons/medulla, hippocampus, striatum, cortex, and midbrain/thalamus at 30, 60, 120, or 240 min after oral aspartame (1000 mg/kg) administration. Without consideration for time and group variables, levels of most compounds were higher in the brain regions of Fischer than Sprague-Dawley rats. Aspartame in Fischer 344 or Sprague-Dawley rats had no significant effect on levels of the catecholamines or indoleamines at any of the time points monitored following its acute administration. From the results of this study, large oral loads of aspartame do not appear to lead to regional alterations in brain biogenic amine levels.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1990

mAb 104, a new monoclonal antibody, recognizes the B7 antigen that is expressed on activated B cells and HTLV-1-transformed T cells.

A new monoclonal antibody (mAb) of the IgG1 subclass, mAb 104, has been obtained after immunization of mice with the Burkitt lymphoma cell line Jijoye. It only weakly binds to a small proportion of non-activated normal B cells and binds to a larger proportion of in vitro-activated normal B cells. All tested Epstein-Barr virus (EBV)-transformed B-cell lines, Burkitt lymphoma cell lines and freshly isolated follicular B-lymphoma cell preparations strongly bound mAb 104. mAb 104 did not bind to peripheral monocytes or tested myelomonocytic cell lines, or to resting and activated normal T cells, T-cell lines and T-cell clones. However, the recognized antigen is expressed on HTLV-1-infected T-cell lines and HTLV-1-transformed T-cell clones. mAb 104 immunoprecipitates, from Jijoyce cell lysates, a single polypeptide with an apparent MW of 45,000-60,000 and an isoelectric point of 5.6. Competition studies with the anti-B7 antibody (Freedman et al., 1987) demonstrated that mAb 104 and the anti-B7 block each others' binding. Furthermore, mAb 104 binds to transfected COS cells (Freedman et al., 1989) expressing the B7 antigen. Thus mAb 104 and and anti-B7 define the same antigen. The restricted distribution of the 104/B7 antigen to activated B cells and HTLV-1-transformed T cells may make it a useful marker for the study of pathological states linked to lymphocyte activation and for the functional study of B-cell subpopulations.

Antibodies, Monoclonal↗
PubMed1989

Definition of T-cell specific DNA-binding factors that interact with a 3'-silencer in the CD4+ T-cell gene Rpt-1.

Analysis of the region 3' to the CD4+ T-cell gene Rpt-1 (encoding regulatory protein T-lymphocyte 1) led to the definition of a silencer element that inhibits heterologous gene expression in certain CD4+ T-cell lines but not in B-cell or non-lymphoid cell lines. Functional silencer activity in vivo was associated with the presence of a specific silencer-DNA-protein complex in electrophoretic mobility shift assays with T-cell extracts. Formation of this complex was selectively inhibited by the region in HIV-1 containing a silencer element. We discuss the possibility that DNA-binding factors may coregulate HIV-1 and Rpt-1 gene expression through a common transcriptional silencer element.

Amino Acid Sequence↗
PubMed1989

Activation primes human B lymphocytes to respond to heat shock.

Crosslinkage of the B cell antigen receptor by anti-mu beads or SAC results in the selective induction of hsp70. We have observed that activated cells, having enhanced expression of hsp70, survive lethal stimuli much better than their unactivated counterparts. These results are in accordance with the proposal that hsp70 is essential for cells to survive lethal environmental stresses. Moreover, the activation event itself primes B cells thereby enabling them to increase the expression of both hsp70 mRNA and protein. This is the first demonstration that triggering of B cells via crosslinkage of sIg is accompanied by the induction of thermotolerance without the need for a prior sublethal heat treatment.

B-Lymphocytes↗
PubMed1989

Isolated human follicular dendritic cells display a unique antigenic phenotype.

In the present study, follicular dendritic cells (FDCs) were purified to homogeneity in order to define the lineage and function of these cells. FDCs were identified by their characteristic morphology and by their expression of receptors for the third complement component, the myeloid-restricted antigen CD14, and the FDC antigen DRC-1. Unclustered FDCs displayed a unique antigenic phenotype since they expressed several B- and myeloid lineage-restricted antigens, but lacked T and NK cell antigens as well as the leukocyte common antigen. FDCs expressed adhesion molecules, including most of the VLA proteins, intercellular adhesion molecule 1 (ICAM-1), and CD11b. FDCs could be isolated to homogeneity by their intense staining with anti-CD14 using flow cytometric cell sorting. These highly purified FDCs expressed CD14 and CD21 but lacked CD20. This antigen pattern and characteristic morphology confirmed that these cells were, in fact, homogeneous FDC preparations. Analysis of polymerase chain reaction-amplified cDNA from highly purified FDCs showed no transcripts for IL-6. The isolation of homogeneous FDC populations will be important for the analysis of the functional role of FDCs within the lymphoid follicle.

Antigens, Differentiation↗
PubMed1989

GPs' differing responses to out-of-hours calls.

After noticing trainer-trainee differences in the proportion of patients visited, a three-month audit of all out-of-hours requests and calls was performed. A wide variation of response was found among doctors on the rota. Those more likely to visit were also more likely to prescribe. A large proportion of the user population was either very young or very old and had an annual consultation rate nearly three times the mean for the practice as a whole.

Adult↗
PubMed1989

Expression and regulation of CD5 on in vitro activated human B cells.

The T cell-associated antigen CD5 has been shown to play an important role in the regulation of T cell activation. Monoclonal antibodies directed against CD5 upregulate helper function, and induce interleukin 2 (IL2) production by mature T cells as well as thymocytes. CD5 is also expressed on subsets of B cells associated with autoantibody production, and CD5+ B cells are present in increased numbers in patients with rheumatoid arthritis and systemic lupus erythematosis. More recently CD5 has been found to be present on human B lymphocytes following in vitro activation with phorbol myristate acetate. To date a similar functional role for CD5 has not to date been demonstrated for B cells. In this study we have shown that structurally similar CD5 molecules are present on activated B cells and T cells. In addition, CD5 on both stimulated B cells and T cells is phosphorylated, which may be important in the function of CD5 following activation. CD5 protein or mRNA was not detected on unstimulated splenic B cells depleted of any CD5+ cells. To investigate the control of CD5 expression, we examined a series of cytokines either alone or in combination for their effect on the induction of CD5. CD5 expression was specifically inhibited by IL4 but not by the other cytokines tested. This inhibition was very specific as IL4 did not inhibit the expression of other B cell activation antigens including CD25, B5, T9 and CD23 as well as the pan-B cell antigen CD20. The addition of other cytokines did not increase or reverse the inhibition of CD5 expression by IL4. This inhibition was demonstrated by immunofluorescence and flow cytometric analysis. Immunoprecipitation studies of 125I-labeled activated B cells demonstrated that there was a decrease in cell surface CD5 protein, and not simply inhibition of expression of a particular epitope. Northern blot analysis demonstrated that the expression of CD5 mRNA was markedly inhibited in the presence of IL4, whereas the induction of the protooncogene c-myb was unaffected. This suggests that IL4 inhibits CD5 protein expression on activated B cells by reducing the amount of CD5 mRNA transcription or increasing the degradation of CD5 mRNA. The role of the T cell-derived lymphokine IL4 in regulating CD5 expression may be important in the disease states characterized by increased numbers of CD5+ B cells.

Antigens, Differentiation↗
PubMed1989

Cytosolic-free calcium and neurotransmitter release with decreased availability of glucose or oxygen.

Exposing brain slices to reduced oxygen tensions or impairing their ability to utilize oxygen with KCN decreases acetylcholine (ACh) but increases dopamine (DA) and glutamate in the medium at the end of a release incubation. To determine if these changes are due to alterations in the presynaptic terminals, release from isolated nerve endings (i.e. synaptosomes) was determined during histotoxic hypoxia (KCN). KCN reduced potassium-stimulated synaptosomal ACh release and increased dopamine and glutamate release. Since several lines of evidence suggest that altered calcium homeostasis underlies these changes in release, the effects of reducing medium calcium concentrations from 2.3 to 0.1-mM were determined. In low calcium medium, KCN still increased dopamine and glutamate release, but had no effect on ACh release. Hypoxia increased cytosolic-free calcium in both the normal and low calcium medium, although the elevation was less in the low calcium medium. Thus, the effects of histotoxic hypoxia on cytosolic free calcium concentration paralleled those on glutamate and dopamine release. Reducing the glucose concentration of the medium also increased cytosolic-free calcium. The data are consistent with the hypothesis that hypoxia and hypoglycemia increase cytosolic-free calcium, which stimulates the release of dopamine and glutamate, whose excessive release may lead to subsequent cellular damage postsynaptically.

Animals↗
PubMed1989

Studies of in vitro activated CD5+ B cells.

Human B lymphocytes undergo distinct phenotypic changes following activation with antigen and polyclonal mitogens. Increasing interest has focused on the unique subpopulation of B cells that expresses the CD5 antigen. In this study, we examined the signals that induce the expression of CD5 on normal splenic B cells. Only 12-O-tetradecanoylphorbol-13-acetate (TPA) induced CD5 expression on highly purified splenic B cells, whereas anti-immunoglobulin (anti-Ig), Epstein-Barr virus, anti-CD20, recombinant interleukin-1 (rIL-1), rIL-2, rIL-4, recombinant interferon-gamma (rINF-gamma), and B-cell growth factor all failed to induce CD5 expression. The expression of CD5 was detected on the cell surface by 48 hours and decreased by 96 hours. Dual-fluorochrome analysis demonstrated that the CD5+ B cells coexpressed the B-cell activation antigens B5, IL-2 receptor, and CD23, thereby providing phenotypic evidence that this B-cell subpopulation is activated. In vitro studies of dual-fluorochrome-sorted, TPA-stimulated splenic B cells demonstrated significantly greater tritiated thymidine incorporation and Ig secretion by the CD20+ CD5- cells than by the CD20+ CD5+ subset. These phenotypic and functional studies are consistent with the notion that TPA-induced CD5+ B cells are a subset of in vitro activated B lymphocytes.

Antigens, CD20↗