Name of the game?
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Ethics, Professional↗
Biomedical subjects
C H Fox
Publications and source records attributed to C H Fox.
cDNA cloning of the B cell membrane protein CD22: a mediator of B-B cell interactions.
We have cloned a full-length cDNA for the B cell membrane protein CD22, which is referred to as B lymphocyte cell adhesion molecule (BL-CAM). Using subtractive hybridization techniques, several B lymphocyte-specific cDNAs were isolated. Northern blot analysis with one of the clones, clone 66, revealed expression in normal activated B cells and a variety of B cell lines, but not in normal activated T cells, T cell lines, Hela cells, or several tissues, including brain and placenta. One major transcript of approximately 3.3 kb was found in B cells although several smaller transcripts were also present in low amounts (approximately 2.6, 2.3, and 1.6 kb). Sequence analysis of a full-length cDNA clone revealed an open reading frame of 2,541 bases coding for a predicted protein of 847 amino acids with a molecular mass of 95 kD. The BL-CAM cDNA is nearly identical to a recently isolated cDNA clone for CD22, with the exception of an additional 531 bases in the coding region of BL-CAM. BL-CAM has a predicted transmembrane spanning region and a 140-amino acid intracytoplasmic domain. Search of the National Biological Research Foundation protein database revealed that this protein is a member of the immunoglobulin super family and that it had significant homology with three homotypic cell adhesion proteins: carcinoembryonic antigen (29% identity over 460 amino acids), myelin-associated glycoprotein (27% identity over 425 amino acids), and neural cell adhesion molecule (21.5% over 274 amino acids). Northern blot analysis revealed low-level BL-CAM mRNA expression in unactivated tonsillar B cells, which was rapidly increased after B cell activation with Staphylococcus aureus Cowan strain 1 and phorbol myristate acetate, but not by various cytokines, including interleukin 4 (IL-4), IL-6, and gamma interferon. In situ hybridization with an antisense BL-CAM RNA probe revealed expression in B cell-rich areas in tonsil and lymph node, although the most striking hybridization was in the germinal centers. COS cells transfected with a BL-CAM expression vector were immunofluorescently stained positively with two different CD22 antibodies, each of which recognizes a different epitope. Additionally, both normal tonsil B cells and a B cell line were found to adhere to COS transfected with BL-CAM in the sense but not the antisense direction.(ABSTRACT TRUNCATED AT 400 WORDS)
Adolescent↗
Influence of surface characteristics on bone integration of titanium implants. A histomorphometric study in miniature pigs.
The purpose of the present study was to evaluate the influence of different surface characteristics on bone integration of titanium implants. Hollow-cylinder implants with six different surfaces were placed in the metaphyses of the tibia and femur in six miniature pigs. After 3 and 6 weeks, the implants with surrounding bone were removed and analyzed in undecalcified transverse sections. The histologic examination revealed direct bone-implant contact for all implants. However, the morphometric analyses demonstrated significant differences in the percentage of bone-implant contact, when measured in cancellous bone. Electropolished as well as the sandblasted and acid pickled (medium grit; HF/HNO3) implant surfaces had the lowest percentage of bone contact with mean values ranging between 20 and 25%. Sandblasted implants with a large grit and titanium plasma-sprayed implants demonstrated 30-40% mean bone contact. The highest extent of bone-implant interface was observed in sandblasted and acid attacked surfaces (large grit; HCl/H2SO4) with mean values of 50-60%, and hydroxylapatite (HA)-coated implants with 60-70%. However, the HA coating consistently revealed signs of resorption. It can be concluded that the extent of bone-implant interface is positively correlated with an increasing roughness of the implant surface.
Animals↗
Human intestine matures as nude mouse xenograft.
This report describes a novel system for the study of the development and function of human intestine. Human fetal bowel transplanted into a subcutaneous tunnel on the back of athymic nude (nu/nu) mice develops a new microcirculation within 4 weeks. Tissues undergo morphological development, become similar to adult human bowel tissue, and may survive for 6 months after transplantation. Monoclonal antibody immunoperoxidase staining shows that the epithelial and some endothelial elements are of human phenotype, but the circulating blood cells and migrating mucosal lymphocytes are of mouse origin.
Animals↗
Lymphoid germinal centers are reservoirs of human immunodeficiency virus type 1 RNA.
When radiolabeled RNA was used for in situ hybridization, human immunodeficiency virus type 1 (HIV-1) RNA was found in high concentrations in germinal centers of lymphoid tissues from patients with HIV-1 infection. Most of the signal from hybridized probe was independent of specific cells, being found in the extracellular space of germinal centers in all lymphoid tissues examined from adult patients with Centers for Disease Control (CDC) class II and III disease or pediatric patients with CDC class P-2A disease. Lymphoid tissues from adult patients with CDC class IV infections or pediatric patients with CDC class P-2D disease (including autopsy material) lacked intact germinal centers, and HIV-1 RNA was then found only in rare, isolated cells, with some tissues having no detectable HIV-1 RNA. Thus, in the early stages of HIV infection, germinal centers serve as important reservoirs of free virus in the interstitial spaces, and this reservoir disappears as the germinal centers involute with advancing disease.
Adenoids↗
Examining cells for infectious agents: a novel approach.
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Cells, Cultured↗
Effects of the platelet-derived growth factor/insulin-like growth factor-I combination on bone regeneration around titanium dental implants. Results of a pilot study in beagle dogs.
The purpose of this study was to evaluate the early wound healing events of bone around press-fit titanium implants inserted with and without the concurrent application of a combination of platelet-derived growth factor (PDGF) and insulin-like growth factor (IGF-I). Nine months prior to implant placement all mandibular premolar teeth were extracted in 8 beagle dogs. Subsequently, 40 specially manufactured titanium implants with 2 transverse holes in the apical section were press fit into precise recipient sites in the dogs' mandibles. The dogs were sacrificed at 7 and 21 days following implant placement yielding 12 PDGF-B/IGF-I treated and 8 control (placebo gel or non-treated) implants for each observation period. Coded undecalcified sections were analyzed for: 1) percentage of implant surface in contact with new bone; 2) percentage of peri-implant space filled with new bone; and 3) percentage of implant hole filled with new bone. An analysis of variance was used to determine significant differences among the treatment groups. At 7 days, the percentage of bone fill in the peri-implant spaces and the percentage of implant surface in contact with new bone were both significantly increased in PDGF-B/IGF-I treated sites (P less than 0.01 for both groups). There was less than 1.5% fill of the implant holes in both treated and control sites (no significant differences). At 21 days the percentage of bone fill in the peri-implant spaces was significantly increased in the PDGF-B/IGF-I treated sites (P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)
Analysis of Variance↗
Determining the value of a periodontal diagnostic test.
The purpose of this analysis is to present a method to determine the value of diagnostic tests for evidence of bacterial activity related to periodontal disease. Five population studies are discussed: 1) screening the general population; 2) screening the patients of a general practice; 3) diagnosing initial patients referred to a periodontist; 4) monitoring periodontal maintenance patients; and 5) monitoring postsurgical refractory patients. A decision tree is constructed in which the primary decision branches are test and no test. Chance branches after the test branch were test positive and test negative. The treatment alternatives in the treatment branches were prophylaxis and oral hygiene, scaling and root planing, and advanced periodontal therapy (including surgical intervention and/or antibiotics or chemotherapies). Probabilities for the prevalence of disease in each population were obtained from epidemiological surveys. Disease activity and outcome states were estimated from clinical studies of periodontal treatment. For initial periodontal patients, using a sensitivity of .87 and a specificity of .84 the value of the test branch is .851 versus .566 for the no test branch. Assumptions on the diagnostic test's sensitivity and specificity and the utility of outcomes were tested with the decision analysis techniques of sensitivity and 2-way threshold analyses. These analyses show that using a test had a greater value than no test for older patients in the general practitioner's office, and for the 3 types of periodontal treatment patients. In contrast, using the test had a lower value than not using the test in younger dental patients in the general practitioner's office and for screening the general population. The diagnostic and treatment schemes proposed here are amendable to rigorous testing to evaluate their reliability and usefulness.
Adult↗
In praise of remarkable men, microscopes, and chicken salad.
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Demography↗
Cloning of a human homeobox gene that resembles a diverged Drosophila homeobox gene and is expressed in activated lymphocytes.
A new homeobox gene, HB24, has been isolated from a human B-lymphocyte cDNA library. Northern blot analysis of polyadenylated RNA purified from activated human B cells revealed a single mRNA transcript of approximately 2.3 kb. Two cDNA clones were sequenced and provided 2,250 nucleotides (nt) of DNA sequence information. There is a single methionine codon-initiated open reading frame of 1,458 nt in frame with a homeobox and a CAX repeat, and the open reading frame is predicted to encode a protein of 51,659 daltons. When the homeodomain from HB24 was compared to known mammalian and Drosophila homeodomains it was found to be only moderately conserved, but when it was compared to a highly diverged Drosophila homeodomain, H2.0, it was found to be 80% identical. The HB24 mRNA was absent or present at low levels in normal B and T lymphocytes; however, with the appropriate activation signal HB24 mRNA was induced within several hours even in the presence of cycloheximide. Characterization of HB24 expression in lymphoid and select developing tissues was performed by in situ hybridization. Positive hybridization was found in thymus, tonsil, bone marrow, developing vessels, and in fetal brain. HB24 is likely to have an important role in lymphocytes as well as in certain developing tissues.
Amino Acid Sequence↗
Endothelins, peptides with potent vasoactive properties, are produced by human macrophages.
Endothelins are peptides, originally isolated from endothelial cells, with potent vasoactive and mitogenic properties. In this study, we demonstrate that human macrophages synthesize and secrete endothelins. Cultured human macrophages were found by immunocytochemistry to stain positively for endothelin 1 and endothelin 3. Their capability to produce and release these peptides was confirmed by a combination of reverse-phase high-performance liquid chromatography and radioimmunoassays, specific for endothelin 1 and 3, respectively. Immunoreactive peptides were identified both in cellular extracts and in macrophage-conditioned medium. The secretion of endothelin 1, but not of endothelin 3, from macrophages could be stimulated 6-10-fold by lipopolysaccharide or phorbol myristate acetate (PMA). Northern blot analysis of total macrophage RNA using an endothelin 1 cDNA probe revealed induction of endothelin mRNA in PMA-treated macrophages. Furthermore, immunoreactive endothelin 1 and 3 were found in U937 cells, a human promonocytic line, and in freshly isolated human monocytes. In contrast, no immunoreactive endothelin was detected in cell extracts from human neutrophils and lymphocytes. The expression of endothelins in tissue macrophages was demonstrated in paraffin sections of human lung using immunohistochemistry. In conclusion, the finding that human macrophages produce endothelins suggests an important role for these peptides in the microenvironment of tissue macrophages. Macrophage-derived endothelins may have an essential function in blood vessel physiology, and aberrant production may contribute to vessel pathology.
Cells, Cultured↗
Identification of human immunodeficiency virus-1 RNA and DNA in the heart of a child with cardiovascular abnormalities and congenital acquired immune deficiency syndrome.
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Acquired Immunodeficiency Syndrome↗
The reservoir for HIV-1 in human peripheral blood is a T cell that maintains expression of CD4.
Human immunodeficiency virus type 1 (HIV-1) selectively infects cells expressing the CD4 molecule, resulting in substantial quantitative and qualitative defects in CD4+ T lymphocyte function in patients with acquired immunodeficiency syndrome (AIDS). However, only a very small number of cells in the peripheral blood of HIV-1-infected individuals are expressing virus at any given time. Previous studies have demonstrated that in vitro infection of CD4+ T cells with HIV-1 results in downregulation of CD4 expression such that CD4 protein is no longer detectable on the surface of the infected cells. In the present study, highly purified subpopulations of peripheral blood mononuclear cells (PBMCs) from AIDS patients were obtained and purified by fluorescence-automated cell sorting. They were examined with the methodologies of virus isolation by limiting dilution analysis, in situ hybridization, immunofluorescence, and gene amplification. Within PBMCs, HIV-1 was expressed in vivo predominantly in the T cell subpopulation which, in contrast to the in vitro observations, continued to express CD4. The precursor frequency of these HIV-1-expressing cells was about 1/1000 CD4+ T cells. The CD4+ T cell population contained HIV-1 DNA in all HIV-1-infected individuals studied and the frequency in AIDS patients was at least 1/100 cells. This high level of infection may be the primary cause for the progressive decline in number and function of CD4+ T cells in patients with AIDS.
Acquired Immunodeficiency Syndrome↗
Kaposi's sarcoma of the parotid gland in acquired immunodeficiency syndrome.
A patient with acquired immunodeficiency syndrome complained of a dry mouth and bilateral swelling of the parotid glands. Kaposi's sarcoma (KS) was found within the tissue of the parotid gland. Although KS is a common manifestation of acquired immunodeficiency syndrome, the presence of KS in the salivary glands is very rare. The human immunodeficiency virus I (HIV-I) genome was not identified in parotid glandular cells or in KS cells in this case, although the virus was detected in infiltrating lymphocytes and in tissue macrophages.
Acquired Immunodeficiency Syndrome↗
Detection of HIV-1 RNA in the lamina propria of patients with AIDS and gastrointestinal disease.
Thirty formaldehyde-fixed, paraffin-embedded endoscopic biopsy specimens from the colon and rectum of 25 patients with acquired immunodeficiency syndrome were examined using a [35S]HIV-RNA in situ hybridization procedure. Nine of the specimens contained cells that bound significant amounts of probe. Cells were considered positive if more than 50 grains of silver (over background) per 200 micron 2 were seen over cells that did not stain with eosin. Most of the positive cells resembled macrophages, although cells with condensed nuclei resembling lymphocytes were found. No epithelial cells expressing viral RNA were detected. Formaldehyde-fixed eosinophils gave spurious signals that could be reduced with sulfhydryl modifying agents. HIV-1 may be disseminated in the lamina propria of the gut at low concentrations in some patients but may not be detectable in others. The lower gut lining may be both a portal of initial infection with HIV and a target of disseminated HIV infection.
Acquired Immunodeficiency Syndrome↗
Bilateral parotid enlargement in HIV-seropositive patients.
Bilateral enlargement of the parotid glands has been noted in five patients who are seropositive for antibody to the human immunodeficiency virus. A characteristic cystic appearance has been noted in these lesions on clinical and radiographic examination. A benign lymphoepithelial infiltrate with cystic degeneration is found in parotid specimens from these patients. The presence of human immunodeficiency virus ribonucleic acid in inflammatory cells infiltrating the parotid specimen was confirmed by an in situ hybridization technique. The clinical manifestations of sicca syndrome were not present nor were opportunistic infections diagnostic for the acquired immunodeficiency syndrome.
Adult↗
Vitamin B12 malabsorption in patients with acquired immunodeficiency syndrome.
We have examined 11 patients with the acquired immunodeficiency syndrome (AIDS) for evidence of subclinical vitamin B12 malabsorption. Three subjects (27%) had low levels of vitamin B12. Eight subjects (73%), including these 3 subjects plus 5 others with normal vitamin B12 levels, had abnormal Schilling test results. In addition, 15% of an unselected population of 121 patients with AIDS and 7% of 27 patients without AIDS who were seropositive for human immunodeficiency virus type 1 (HIV-1) had low serum vitamin B12 levels. Stool cultures from the 8 subjects with abnormal Schilling test results revealed no pathogens. Intestinal involvement by Kaposi's sarcoma was found in only 1 patient. Biopsy specimens from 5 of 6 patients with vitamin B12 malabsorption, however, contained mononuclear cells harboring HIV-1, as indicated by in situ hybridization studies. Our observations suggest that vitamin B12 malabsorption is common in patients with AIDS and may be a very early manifestation of infection with HIV-1.
Acquired Immunodeficiency Syndrome↗