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Biomedical subjects

D R Howard

Publications and source records attributed to D R Howard.

At least 37 records · Page 2Linked to original sources
PubMed1990

Intramuscular vaccination of skunks and raccoons against rabies.

Live-captured striped skunks (Mephitis mephitis) and raccoons (Procyon lotor) were immunized with inactivated rabies vaccine by intramuscular injection and released at the point of capture during a rabies control program in Metropolitan Toronto (Ontario, Canada). Serum samples collected prior to and following vaccination revealed that 100% of the skunks and 98% of the raccoons seroconverted. Rabies antibody was still detectable 314 to 757 days postvaccination. Five of six skunks vaccinated in the laboratory survived challenge with rabies virus 90 days postvaccination. To our knowledge, this is the first documentation of the successful seroconversion of skunks and raccoons vaccinated against rabies in the field.

Animals↗
PubMed1990

Angiomyolipoma of kidney with lymph node involvement. DNA flow cytometric analysis.

We performed DNA flow-cytometric analysis in three cases of angiomyolipoma of the kidney with lymph node involvement. The primary tumors of the kidneys and tumors in the lymph nodes of all patients contained diploid DNA. All three patients have been monitored for longer than 1 year and have no evidence of recurrence or metastasis. The lack of aneuploidy in both the kidney and the lymph nodes in our patients, although not excluding malignant neoplasia, supports the benign and multifocal nature of this lesion. Larger studies with long-term follow-up are reported to confirm this conclusion.

DNA, Neoplasm↗
PubMed1987

The GDP-fucose:N-acetylglucosaminide 3-alpha-L-fucosyltransferases of LEC11 and LEC12 Chinese hamster ovary mutants exhibit novel specificities for glycolipid substrates.

Previous studies have shown that the GDP-fucose:N-acetylglucosaminide 3-alpha-L-fucosyltransferase (alpha (1,3) fucosyltransferase (Fuc-T)) activities expressed by the Chinese hamster ovary cell mutants LEC11 (Fuc-TI) and LEC12 (Fuc-TII) are different enzymes and indicated that Fuc-TI might act on sialylated lactosamine sequences (Campbell, C., and Stanley, P. (1984) J. Biol. Chem. 259, 11208-11214). In this paper we show that CSLEX-1, a monoclonal antibody specific for NeuNac alpha (2,3)Gal beta (1,4)(Fuc alpha (1,3))GlcNAc beta 1 sequences, bound to LEC11 cells but not to LEC12 cells. Direct evidence that Fuc-TI could act on sialylated substrates was sought with a series of glycolipid acceptors. Optimal assay conditions in crude cell extracts were determined with nLc4, a glycolipid which accepted fucose with both Fuc-TI and Fuc-TII to generate the Lex antigenic determinant. The two enzymes differed in their detergent sensitivities, pH optima, Mn2+ requirements, and apparent Km values for nLc4. When sialylated glycolipids were examined as substrates, Fuc-TI added fucose to IV3NeuNAcnLc4 but not to IV6NeuNAcnLc4, whereas Fuc-TII was unable to utilize either glycolipid as a substrate. Further studies showed that Fuc-TI and Fuc-TII possess novel specificities for glycolipids containing two lactosamine sequences as potential fucose acceptors. Fuc-TI exhibited good activities with VI3NeuNAcnLc6 and VI6NeuNAcnLc6 whereas Fuc-TII had very low activity with both substrates. Glycosidase digestions of the labeled products showed that Fuc-TI added fucose primarily to the internal N-acetylglucosamine of both glycolipids. The same preference for the internal N-acetylglucosamine was shown by Fuc-TI when nLc6 was the acceptor. In contrast, Fuc-TII preferred to transfer fucose to the external acceptor site of nLc6, consistent with the low activities of Fuc-TII with sialylated nLc6 derivatives. Thus the two enzymes preferentially add fucose to different N-acetylglucosamines in the same substrate, nLc6. This indicates that the biosynthetic pathway for fucosylation of polylactosamine sequences in glycolipids and glycoproteins will vary depending upon the particular alpha (1,3)fucosyltransferase present.

Animals↗
PubMed1987

Comparative prevalence of rabies antibodies among household and unclaimed/stray dogs as determined by the immune adherence haemagglutination assay.

The immune adherence haemagglutination assay (IAHA), widely used for human viral disease diagnosis, has been adapted for detection of rabies virus antibodies in dog sera. Rabies virus antibody titres obtained by the IAHA correlated well with those obtained by the currently accepted test for rabies antibody determination, the rapid-fluorescent-focus-inhibition test (RFFIT). Although it is not known if the antibodies detected in IAHA test represent neutralizing antibodies against rabies, IAHA has several advantages over the RFFIT: the IAHA is rapid, requiring about seven hours for results to be available; it is relatively inexpensive and easy to perform; uses reagents commonly available in any routine virology laboratory; and uses inactivated rabies virus, thus eliminating hazards associated with the use of live virus in RFFIT. Using this test we found that rabies antibody titres were significantly higher, and at the same time more prevalent, among household dogs than among the unclaimed/stray dogs. The results re-emphasize the increased hazard associated with unclaimed/stray dogs and the need for vaccination of all dogs.

Animals↗
PubMed1986

Lymphocyte function-associated antigen (LFA-1) is involved in B cell activation.

Human LFA-1 is a widely expressed leukocyte antigen present on cells of myeloid and lymphoid lineage. Monoclonal antibodies to LFA-1 have been shown to inhibit in vitro T cell immune functions. However, a role for LFA-1 in B cell activation has not been documented. To investigate this possibility, we examined the distribution of LFA-1 on normal, neoplastic, and EBV-transformed B cells as well as the ability of a monoclonal anti-LFA-1 antibody (NB-107) to inhibit B cell mitogenesis. NB-107 immunoprecipitates a noncovalently linked heterodimer of approximately 170,000 and 95,000 daltons. Sequential immunoprecipitation and cross-blocking studies showed that NB-107 identified a distinct epitope on the LFA-1 molecule. NB-107-defined LFA-1 was present on peripheral blood mononuclear cells (PBMC) from all normal individuals (N = 27) and on EBV-transformed cell lines (N = 9), but was absent from four of seven neoplastic B lymphoma lines. NB-107 was observed to profoundly inhibit the response of PBMC to the B cell mitogens anti-IgM (mean 71% inhibition) and lipopolysaccharide (mean 80% inhibition). In order to investigate the mechanism of inhibition, B cells were sequentially purified from PBMC by using a combination of E rosette depletion of T cells, monocyte removal by glass adherence, and finally cell sorting. These extensively enriched populations of B cells, although still responding to anti-mu, showed no evidence of inhibition by NB-107. Growth of EBV-transformed cell lines, cultured in the presence of NB-107, also was not inhibited by this antibody. When tested in assays for T cell function, NB-107 was shown to inhibit the mixed lymphocyte response, but had no effect on phytohemagglutinin stimulation of PBMC nor on the clonal growth and differentiation of granulopoietic, erythropoietic, and pluripotent progenitor cells. We conclude that anti-LFA-1 monoclonal antibody inhibits B cell mitogens via indirect effects on monocytes and/or T cells, rather than by a direct antiproliferative effect on B cells.

Animals↗
PubMed1986

High-frequency transfection of CHO cells using polybrene.

High-frequency transfection of CHO cells has been achieved for several plasmids, a cosmid library, and genomic DNA using Polybrene and dimethyl sulfoxide. All plasmid transfectants examined were stable and exhibited plasmid sequences in genomic DNA. The method is simple, reproducible, and succeeded with several independent CHO clones in the presence or the absence of carrier DNA, even at very low concentrations of plasmid DNA.

Animals↗
PubMed1986

Monoclonal antibodies to HLA-DP, DQ, and DR determinants: functional effects on the activation and proliferation of normal and EBV-transformed B cells.

To investigate the function of HLA class II molecules in B-cell activation, we generated three new anti-HLA class II monoclonal antibodies with differing specificities for DP, DQ, and DR determinants. These were tested for their ability to inhibit various B- and T-lymphocyte responses. Each of these antibodies (NB-29, DH-84, and DH-224) immunoprecipitates a heterodimer of approximately 35,000 and 28,000 mol wt from 125I-surface-labeled B-lymphoma cells, as shown by SDS-PAGE. NB-29 (IgG1) detects a polymorphic DQ determinant, while DH-224 (IgG1) is reactive with monomorphic DR determinants, and DH-84 (IgG2a) has specificity for DP, DQ, and DR. Both DH-224 and DH-84, but not NB-29, were found to inhibit significantly the stimulation of peripheral blood mononuclear cells (PBMC) by anti-mu (70%-90% inhibition) and by lipopolysaccharide (80%-90% inhibition), as measured by incorporation of tritiated thymidine. When added to highly purified populations of peripheral blood B cells, none of these anti-class II monoclonal antibodies inhibited anti-mu-induced stimulation. This suggests that the inhibitory effect that DH-224 and DH-84 have on the stimulation of unfractionated PBMC may be due to their ability to interfere with the action of accessory cells. Epstein-Barr-virus (EBV)-transformed B-cell lines, in contrast, showed substantial inhibition of growth when cultured in the presence of any of the three antibodies. With respect to T cells, DH-84 and DH-224 strongly inhibited the mixed lymphocyte response; NB-29 did not. None of these antibodies inhibited stimulation of PBMC by phytohemagglutinin (PHA). These findings suggest that DQ and DR HLA class II molecules have differing roles in B-cell activation and document a direct antiproliferative effect of anti-HLA class II monoclonal antibodies on the growth of EBV-transformed cell lines.

Animals↗
PubMed1985

Tn, a carcinoma-associated antigen, reacts with anti-Tn of normal human sera.

Tn antigen is the immediate precursor of the carcinoma (CA)-associated T antigen; both are masked in non-CA tissues. Tn antigen was detected by absorption of human anti-Tn antibody in 46 of 50 primary breast CAs and in all 6 metastases originating from Tn-positive primary CAs. Thirteen of 25 (52%) anaplastic CAs, but only 2 of 15 (13%) well differentiated CAs had more Tn than T; 1 anaplastic CA had neither antigen. Eighteen of 20 benign breast lesions had no Tn; the 2 positive lesions were premalignant. All 19 breast CAs, studied immunohistochemically, reacted strongly with human polyclonal anti-Tn; benign or normal glandular tissues had minimal or no reactivity. Among live cancer cell lines, the most malignant sublines had more Tn than T on their cell surfaces. Preliminary studies with rodent monoclonal anti-Tn and anti-T antibodies gave immunohistochemical reactivity patterns similar to those of the polyclonal antibodies, but the former were less sensitive in absorption tests. Tn is a CA marker that promises to be useful in tumor detection.

Animals↗
PubMed1985

Two monoclonal antibodies defining unique antigenic determinants on human B-lymphoma cells.

The non-Hodgkin's lymphomas are a clinically, morphologically, and immunologically heterogeneous group of diseases. Why lymphoma cells are unresponsive to normal regulatory growth controls and how they differ from normal lymphocytes are not well understood. In order to address these questions we have raised monoclonal antibodies to neoplastic B-cells. Two of these, LM-26 and LM-155, show a high degree of specificity for B-cell lymphomas. When tested by fluorescence activated cell sorter analysis, LM-26 reacted with 80% (18 of 23) of B-cell lymphomas freshly explanted from patients and LM-155 reacted with 20% (5 of 23). The antigenic determinant detected by LM-26 was also found to be present on four of seven neoplastic large cell B-lymphoma lines. LM-155 detected a determinant present on all seven of these lines. For neither monoclonal antibody was there any association between antibody reactivity and the morphological subtype of lymphoma examined or the type of cell surface immunoglobulin expressed. LM-155 reacted with one case of B-cell acute lymphoblastic leukemia. Neither antibody reacted with normal B-cell blasts, normal peripheral blood mononuclear or marrow cells, T-cell leukemias or lymphomas, or chronic lymphocytic leukemia cells. Lymphocytes from reactive lymphoid hyperplasias involving lymph nodes, spleen, peripheral blood, and lung were also negative for LM-26 and LM-155 binding or showed only a small percentage of cells positive (4-8%). Both monoclonals were unreactive with non-B-lymphoid neoplastic cell lines, nine of ten Epstein-Barr virus transformed B-cell lines, and cells freshly explanted from patients with cancers of diverse cellular origins. Fluorescence activated cell sorter analysis of the expression of the antigens defined by LM-26 and LM-155 on lymphoma cells and normal B-cell blasts suggests that they are not normal differentiation antigens associated with lymphocyte activation or proliferation. The highly restricted expression of detectable levels of antigens reactive with monoclonal antibodies LM-26 and LM-155 on non-Hodgkin's lymphoma cells suggests a possible relation to their neoplastic properties. From a practical viewpoint these monoclonals may prove useful in the diagnosis, classification, detection of residual disease, and treatment of the non-Hodgkin's lymphomas.

Antibodies, Monoclonal↗
PubMed1984

Differentiation of chronic lymphocytic leukemia from reactive lymphocytosis by the mouse red cell rosette assay.

The differential diagnosis of chronic lymphocytic leukemia (CLL) from other neoplastic and nonneoplastic lymphocytoses may be difficult, even when optimal clinical and laboratory data are available. The mouse red cell (M) rosette assay has been valuable in distinguishing normal and lymphomatous lymphocytes from those of CLL. Not yet tested is the ability of this test to separate reactive (benign) lymphocytes from morphologically similar but neoplastic cells of CLL. In the present study, lymphocytes of 58 subjects with CLL, reactive lymphocytosis, and healthy controls were evaluated for M rosette formation, in addition to the usual B and T cell markers. Lymphocytes from patients with CLL showed a marked increase in the ability to form M rosettes in comparison to those from normal controls and patients with reactive lymphocytosis. The formation of M rosettes was a more reliable marker for CLL than surface membrane immunoglobulin.

Adult↗
PubMed1983

T-antigen does not induce cell mediated immunity in patients with breast cancer.

A total of 80 subjects with benign and malignant breast disease and healthy controls were studied for reactivity to T-antigen, MN-antigens and phytohemagglutinin (PHA) using the lymphocyte blastogenesis assay. No differences were detected between controls and patients with benign or malignant breast disease in reactivity to T- and MN-antigens. Moreover, there was no differential response to T- and MN-antigens among patients with breast cancer. PHA reactivity, although similar between groups as a whole, was diminished in patients with advanced carcinoma. These findings indicate that T-antigen fails to induce cell mediated immunity in patients with breast cancer.

Adult↗
PubMed1982

Structural studies of the endoglycosidase H-resistant oligosaccharides present on human beta-glucuronidase.

Human beta-glucuronidase bears 3-4 oligosaccharide moieties/subunit of Mr = 75,000. We have previously characterized the endoglycosidase H-releasable oligosaccharides of this enzyme including those which are phosphorylated and involved in targeting to lysosomes. In this study, we report the characterization of the endoglycosidase H-resistant oligosaccharides which were released from beta-glucuronidase with anhydrous hydrazine. Approximately 65% of the hydrazine-released oligosaccharides are of the high mannose type, with the predominant species containing 9 mannose residues. The remaining oligosaccharides appear to originate from incomplete complex oligosaccharides. Their basic structures are Man alpha 1,6Man beta 1,4Glc-NAc beta 1,4GlcNAcol, and Man alpha 1,3[Man alpha 1,6]Man beta 1,4Glc-NAc beta 1,4GlcNAcol with roughly half of each species containing an additional fucose linked alpha 1,6 to the N-acetylglucosaminitol (GlcNAcol) residue. The small amount of complex oligosaccharide present bearing 1 sialic acid was heterogeneous in nature with incompletion of the nonsialylated branch. In addition, there was a minor specie of high mannose-type oligosaccharide bearing 5 mannose residues with an alpha 1,6-linked fucose on the GlcNAcol. This structure was not expected since high mannose-type oligosaccharides have been reported to not be substrates for the alpha 1,6-fucosyl transferase.

Carbohydrate Conformation↗
PubMed1982

Vitamin E does not modify HDL-cholesterol.

Vitamin E has been reported to increase serum high-density lipoprotein (HDL) cholesterol. Given the known inverse relationship between HDL-cholesterol and risk of developing coronary artery disease, these preliminary results require verification or refutation. In the present study, 39 volunteers were given 600 U of vitamin E daily for 30 days. Serum vitamin E, cholesterol, HDL-cholesterol, and triglycerides were measured at appropriate intervals. No significant change in serum HDL-cholesterol with vitamin E therapy could be documented.

Adult↗
PubMed1982

Peanut agglutinin: a new marker for tissue histiocytes.

The histiocyte (macrophage) is a unique cellular constituent of the immune system which is involved in immune and non-immune cellular reactions, as well as in the genesis of a variety of benign and malignant neoplasms. The ability to distinguish histiocytes from similar appearing cells morphologically, is often difficult, yet may be of considerable practical and theoretical importance. The present study describes a new marker for histiocytes, applicable to routinely processed tissues. An immunoperoxidase procedure to detect binding of peanut agglutinin (PNA) was applied to 58 specimens consisting of lymph nodes, extranodal lymphoid tissues, neoplasms and reactive histiocytic lesions. Results were compared with a currently accepted histiocytic marker--cytoplasmic muramidase. Of the 58 tissues, 51 showed PNA binding to morphologically recognizable histiocytes, whereas muramidase was detected in only 44. PNA binding- appeared at least as sensitive and specific as muramidase, as a marker for histiocytes, and offers the advantage that it does not bind to cells of the granulocytic series.

Cytoplasm↗
PubMed1981

Carcinoma-associated cytostructural antigenic alterations: detection by lectin binding.

Tumor cell membrane glycoproteins may be involved in the induction of tumor immunity or in the escape of tumors from immunologic defense mechanisms. Previous investigations have suggested a role for blood group antigens and their precursors, in the generation of the immune response to neoplasia. In this study, 44 benign and malignant breast lesions were examined for the presence of a carbohydrate precursor antigen (T-antigen) of the human blood group system MN. T-antigen was demonstrated using an immunohistochemical technique to detect tissue binding of a plant lectin (PNA) with specificity for T-antigen. Of the 22 benign breast lesions examined, 19 showed T-antigen present along the luminal cytoplasmic membrane and occasionally on intraluminal secretions. T-antigen, as demonstrated by lectin binding, was confined to this region in all benign lesions except one, which also showed cytoplasmic positivity. Malignant breast lesions showed a pattern of T-antigen expression markedly different from that of benign breast tissues. Of 22 breast carcinomas, 17 showed diffuse cytoplasmic T-antigen. Five carcinomas showed no evidence of T-antigen by this technique. These malignancies tended to be the most poorly differentiated when judged by histologic criteria. A possible role for T-antigen in the modulation of the immune response to breast carcinoma is suggested.

Antigens, Neoplasm↗