Search PubMed⌕ Search

Biomedical subjects

R L Boyd

Publications and source records attributed to R L Boyd.

At least 109 records · Page 6Linked to original sources
PubMed1990

Lymphokine-activated killer cytotoxicity against leukaemic blast cells.

While the sensitivity of cell lines and solid tumours to lymphokine-activated killer (LAK) cell cytotoxicity is extensively reported, the ability of these generated cytotoxic cells to lyse leukaemic blast cells is controversial. This study reports the successful generation of LAK cells with specificity for leukaemic blast cells. Control donors, patients in remission and patients with active leukaemia were capable of lysing allogeneic leukaemic blast cells. One patient was also capable of lysing autologous leukaemic blast cells. Successful LAK generation was achieved by the use of high dose recombinant interleukin-2 (rIL-2) while combinations of lymphokines did not improve LAK specificity or efficacy. These findings suggest that LAK immunotherapy may be considered for the treatment of patients with acute leukaemia.

Adolescent↗
PubMed1990

The ontogeny of chicken bursal stromal cells defined by monoclonal antibodies.

Molecules expressed on lymphoid stromal cells influence the differentiation of lymphocytes. We have examined the expression of stromal markers, identified by monoclonal antibodies, in the chicken bursa of Fabricius during ontogenic development. These results are also consistent with the hypothesis that medullary secretory cells are of mesenchymal origin, whereas the basement membrane-associated and some medullary epithelium are derived from the endoderm. Our results have demonstrated the complexity of bursal stromal development with determinants expressed on the adult medullary stellate cells (e.g., MUI-57 and 62) and cortical macrophages (e.g., MUI-66 and 72) detected on the early embryonic tunica propria (e.g., MUI-57, 66 and 72) or surface epithelium (e.g., MUI-62 and 66). In addition, we provide preliminary evidence regarding potential functions of these molecules in stem cell colonization (MUI-52), early B-cell differentiation (e.g., MUI-72), late bursal B-cell development (MUI-69 and 71) and the follicle-associated epithelium transport mechanism (MUI-61 and 73).

Animals↗
PubMed1990

Phenotypic characterization of chicken bursal stromal elements.

Many, if not all, of the different phases of intrabursal B-cell maturation are controlled by the stromal components. We have used an extensive panel of mAb to provide a detailed phenotypic profile of these cells. Antigenic specificities were defined for the entire surface epithelium, interfollicular surface epithelium, follicle-associated epithelium, basement membrane, basement membrane-associated epithelium. Several mAb were specific for the medulla, including those reactive with the stellate network of epithelial cells, isolated macrophages, and granular, apparently secreted antigens. One of these, MUI-92, appears to be bursa-specific. Two mAb reacted strongly with stellate cortical macrophages, one of which weakly stained similar cells in the medulla. MHC-class II antigens were expressed on endothelium of the corticomedullary junction, macrophagelike cells in the cortex, and medulla and B lymphocytes predominantly in the cortex. Collectively, these mAb have demonstrated the antigenically distinct nature of discrete regions in the bursa, but also the continuity of the surface epithelium with the corticomedullary junction and medulla. They represent excellent reagents for defining the stromal cell contribution of B-cell development.

Animals↗
PubMed1990

The phenotypic heterogeneity of mouse thymic stromal cells.

Sixteen monoclonal antibodies (mAb) were produced against mouse thymic stromal elements. These mAb fell into two groups of reactivity: (i) thymic epithelial markers (screened and presented according to the guidelines proposed in the 1989 Rolduc Thymic Epithelial Workshop); and (ii) non-epithelial thymic markers. Specificities of these mAb included extensive subpopulations of both epithelial and non-epithelial thymic stromal cells, as well as isolated stromal cells, demonstrating some of the complex microspecificities in existence within the thymic microenvironment. Furthermore, six of these mAb demonstrated shared antigenicity between thymocytes and thymic stromal cells, revealing greater similarities than previously recognized between these two components. Three mAb detected antigens illustrating three consecutive layers of the blood-thymus barrier: the vascular endothelium; connective tissue of the capsule and perivascular spaces; and the connective tissue associated with the basal laminae lining these regions. This study illustrates unequivocably that there are indeed complex and varied microenvironments existing within the thymus, and emphasizes the need for reclassification of these cells.

Animals↗
PubMed1990

Cyclophosphamide- and testosterone-induced alteration in chicken bursal stroma identified by monoclonal antibodies.

Both cyclophosphamide (Cy) and testosterone propionate (TP) treatments ablate B cells in chickens. Essential bursal microenvironmental elements, however, are altered or lost following TP treatment, while bursae from Cy-injected birds can be reconstituted with donor precursors. These two models can thus be utilized to distinguish which bursal stromal molecules are functionally most important in the specific microenvironment of this organ. Monoclonal antibodies (mAb) reactive with non-lymphoid components of the chicken bursa of Fabricius have been used to examine bursal sections from birds treated with Cy or TP. Molecules have been identified on the epithelial buds and follicle-associated epithelium (FAE) that are enhanced following Cy treatment (MUI-52 and 58) and are absent in TP-treated birds. The expression of these molecules may correspond to the ability of Cy-treated but not TP-treated bursae to attract lymphoid precursors. Molecules have also been identified on cells in the subepithelial mesenchymal layer (MUI-63, 65 and 75). These cells interact with the surface epithelium (sEp) prior to epithelial bud formation, an interaction which appears to be TP sensitive. Additionally, two potentially important molecules have been identified in the bursal medulla (MUI-54 and 72) which may have an interactive role with developing B lymphocytes.

Animals↗
PubMed1989

The myelopoietic inducing potential of mouse thymic stromal cells.

The thymus has generally been considered as being solely involved in T cell maturation. In this study we have demonstrated that mouse thymic stroma can also support myelopoiesis. Bone marrow from mice treated with 5-fluorouracil was depleted of cells expressing Mac-1, CD4, and CD8 and incubated on lymphocyte-free monolayer cultures of adherent thymic stromal cells. After 7 days there was a marked increase in nonadherent cells, the majority of which were Mac-1+, FcR+, and HSA+. These proliferating bone marrow cells also expressed markers (MTS 17 and MTS 37) found on thymic stromal cells. Such cells were not found in thymic cultures alone, in bone marrow cultured alone, or on control adherent cell monolayers. Supernatants from the cultured thymic stroma, however, were able to induce these cell types in the bone marrow precursor population. Incubation of normal thymocytes with a monolayer of these in vitro cultivated Mac-1+, MTS 17+, MTS 37+ myeloid cells leads to selective phagocytosis of CD4+ CD8+ cells. Hence, this study demonstrates that the thymic adherent cells can induce myelopoiesis in bone marrow-derived precursor cells and provide a form of self-renewal for at least one population of thymic stromal cells. Furthermore, these induced cells are capable of selective phagocytosis of CD4+ CD8+ thymocytes and may provide one mechanism for the selective removal of such cells from the thymus.

Animals↗
PubMed1989

Effect of rotary electric toothbrush versus manual toothbrush on periodontal status during orthodontic treatment.

Adolescents with fixed orthodontic appliances frequently have increased levels of plaque accumulation and gingivitis. The purpose of this study was to determine whether a rotary electric toothbrush would be more effective than conventional toothbrushing in maintaining periodontal health in these patients. Forty adolescent patients were divided into equal groups matched for sex and age. Before and during placement of orthodontic appliances, one group was instructed in use of the rotary electric toothbrush and the other in the use of a conventional toothbrush; these instructions were reinforced at monthly visits thereafter. Baseline clinical assessments of Plaque Index, Gingival Index, and bleeding tendency were made on six standard teeth before appliances were placed. assessments were repeated at 1, 3, 6, 9, 12, and 18 months after appliances were placed. Intragroup and intergroup differences were tested by a two-way analysis of variance. At baseline there were no significant differences between the two groups for any study variable. During the 18-month study period, however, plaque accumulation and gingivitis increased significantly over baseline levels in the control group (p less than 0.01) but remained stable in the group using the rotary electric toothbrush. In addition, the control group showed significantly greater plaque (p less than 0.01), gingival inflammation (p less than 0.001), and gingival bleeding on probing (p less than 0.001) than did the treatment group from the 1- to 18-month examinations. These data suggest that the rotary electric toothbrush is more effective than conventional toothbrushes for removing plaque and controlling gingivitis in adolescents during orthodontic treatment with fixed appliances.

Child↗
PubMed1989

Periodontal implications of orthodontic treatment in adults with reduced or normal periodontal tissues versus those of adolescents.

This longitudinal study monitored periodontal status in 20 adults and 20 adolescents undergoing fixed orthodontic treatment. Ten adults had generalized periodontitis and received periodontal treatment, including periodontal surgery, before orthodontic treatment. They also received periodontal maintenance at 3-month intervals during orthodontic treatment. The other 10 adults had normal periodontal tissues. Neither these latter adults nor the adolescents received periodontal maintenance during orthodontic treatment. Periodontal status was determined (1) at six standard sites before fixed appliances were placed (baseline), (2) at 1, 3, 6, 9, 12, and 18 months after appliances had been placed, and (3) 1, 3, 6, and 12 months after appliances had been removed. At each of these visits, these sites were assessed for plaque index, gingival index, bleeding tendency, and pocket depth. Loss of attachment between baseline and 3 months after appliances were removed and tooth loss were also determined. Complete data were obtained for 15 adolescents and 14 adults. During orthodontic treatment the adolescent group showed significantly more (p less than 0.05) periodontal inflammation and supragingival plaque than the adults; after appliances were removed, this pattern was no longer statistically significant. For loss of attachment, there were no significant differences among adolescents, adults with normal periodontal tissues, or adults with reduced but healthy periodontal tissues who had undergone treatment for periodontal disease. For tooth loss, three nonstudy site teeth with pockets deeper than 6 mm and/or furcation involvements were lost because of periodontal abscesses in the adult group treated for periodontal disease.

Adolescent↗
PubMed1989

Childlessness and social mobility during the baby boom.

America's post-war baby boom was an era of high fertility and widespread pronatalism. Supposedly, few couples during this time were childless by choice. However, by using a special census sample, this study shows that voluntary childlessness was relatively common in certain upwardly mobile segments of the population during the baby boom. In particular, the results support the classic Dumont-Banks model of status enhancement and fertility, which states that couples with the greatest disadvantages must make the greatest sacrifices of child-centered behavior. The theoretical implications of the findings are discussed and suggestions for future research proposed.

Americas↗
PubMed1989

Diminished insulin-like growth factor-1 levels after chronic ethanol: relationship to pulsatile growth hormone release.

Previous studies have clearly demonstrated a reduction in plasma levels of IGF-1 in rats chronically fed an ethanol diet. The purpose of this study was to determine whether the reduction in IGF-1 was associated with alterations in growth hormone secretory dynamics. Male Sprague-Dawley rats were fed either a liquid diet containing 5% ethanol or an identical volume of diet made isocaloric with maltose-dextrin (pair-fed controls). After 4 months of continuous feeding, another group of animals of the same age was introduced into the colony and fed the maltose-dextrin diet ad libitum. All animals were atrial cannulated 4.5 months after the initiation of the experiment and serial samples of blood removed at 20-min intervals for periods up to 6 hr. Plasma was separated and growth hormone and IGF-1 concentrations determined by radioimmunoassay. Growth hormone secretory dynamics were analyzed by Cluster Analysis. Our results demonstrated that (a) chronic ethanol administration decreases plasma IGF-1 concentrations compared to either ad libitum or pair-fed control animals, (b) a reduction in dietary intake of approximately 33% reduces both the number of detectable growth hormone pulses and nadir concentrations of this hormone but has no effect on peak height, peak width, or area under the peak, and (c) ethanol feeding increases the amplitude of growth hormone pulses compared to pair-fed rats. We conclude that the decrease in plasma IGF-1 levels in ethanol as compared to pair-fed control animals is not caused by a further reduction in growth hormone secretory dynamics.(ABSTRACT TRUNCATED AT 250 WORDS)

Alcohol Drinking↗
PubMed1989

Effects on gingivitis of daily rinsing with 1.5% H2O2.

The purpose of this study was to compare 2 groups of adolescents undergoing orthodontic treatment with fixed appliances to determine whether once daily use of a mouthrinse containing 1.5% H2O2 along with toothbrushing would be better than toothbrushing alone in maintaining their periodontal health. The 2 groups of subjects were selected non-randomly but were matched for age and sex. The control group (N = 34) used toothbrushing and a mint-flavored 0.05% NaF mouthrinse once daily, while the treatment group (N = 25) used toothbrushing and a once daily rinse with a preparation containing 0.05% NaF and 1.5% H2O2 (Orthoflur). 2 calibrated clinical examiners made single-blind clinical assessments of the plaque index, gingival index, and bleeding tendency in 6 standard sites per subject. They also noted any generalized mucosal irritations or staining of the teeth or tongue. Assessments were made before appliances were placed (baseline) and 1, 3, 6, 9, 12 and 18 months after appliances were placed. Results indicated that although there were no significant differences at baseline, the Orthoflur group had significantly fewer study sites with gingival indes or bleeding tendency scores greater than 1 than the control group from the 1-month through the 18-month examinations (P less than 0.01), and significantly fewer sites with plaque index greater than 1 and bleeding tendency scores of 2 or more from the 3-month through the 18-month examinations (P less than 0.02 and 0.01, respectively). No generalized mucosal irritations or clinically significant staining of the tongue or teeth were noted in either group during the study.

Adolescent↗
PubMed1989

Effect on periodontal status of rotary electric toothbrushes vs. manual toothbrushes during periodontal maintenance. I. Clinical results.

The purpose of this study was to compare the Rotadent rotary electric toothbrush with conventional toothbrushing for its effectiveness in controlling supragingival plaque and gingival inflammation in periodontal maintenance patients. Forty subjects who had received periodontal treatment, including periodontal surgery, for moderate to advanced periodontitis and were on a 3-month periodontal maintenance were divided into two equal groups matched for age and sex. One group used conventional toothbrushing, dental floss, and toothpicks and the other used only the rotary electric toothbrush for a 12-month study period. Single-blind clinical assessments (Plaque Index, Gingival Index, bleeding tendency, pocket depth, and loss of attachment) were made at baseline and at 3, 6, 9, and 12 months after baseline. Subgingival debridement was performed 1 week after the baseline assessment and the 6- and 12-month examinations. Plaque removal was reinforced at 3-month intervals. Both groups had significantly improved scores (P less than 0.01) for Gingival Index and bleeding tendency during the 12-month period, but no differences were found between the groups at any examination. These results indicate that the rotary electric toothbrush is as effective for plaque removal and control of gingival inflammation as a combination of conventional toothbrushing, flossing, and toothpicks for patients in periodontal maintenance.

Adult↗
PubMed1989

Effect of periodontal status of rotary electric toothbrushes vs. manual toothbrushes during periodontal maintenance. II. Microbiological results.

We compared the use of a rotary electric toothbrush with conventional toothbrushing for their effectiveness in modulating the subgingival microbiota. Forty subjects who had received periodontal treatment for moderate to advanced periodontitis and were on 3-month periodontal maintenance were divided into two equal groups matched for age and sex. One group used only the rotary tooth cleaner and the other group used conventional toothbrushing, dental floss, and toothpicks for 12 months. Subgingival plaque samples (two sites per patient) were taken from 10 subjects per group at baseline, 6 months, and 12 months and analyzed for percentage of obligate anaerobes and colony-forming units of black-pigmented Bacteroides, Fusobacterium, Actinomyces, Streptococcus, and Veillonella spp. The percentage of spirochetes and motile rods was determined by darkfield microscopy. Results showed that levels of obligate anaerobes, Fusobacterium, and Actinomyces and percentage of spirochetes and motile rods decreased significantly (P less than 0.05), while levels of Streptococcus spp. increased (P less than 0.05) for both groups. However, there was no significant difference between the two groups, indicating that the rotary tooth cleaner and conventional toothbrushing are equally effective in controlling gingivitis and fostering a less pathogenic microflora.

Adult↗
PubMed1989

Modulation of T-cell differentiation in murine fetal thymus organ cultures.

The effects of IL-1, IL-2, and a panel of monoclonal antibodies to thymic stroma and/or thymocytes, on T-cell differentiation in murine fetal thymus organ cultures were followed. Day-14 fetal thymic lobes were cultured for up to 12 days in the presence of IL-1 and/or IL-2 at concentrations of 100 U/ml. Development of all the major subpopulations defined by CD4 and CD8 expression was inhibited by IL-2, however the degree of inhibition was greatest for CD4+CD8- and CD4+CD8+ subsets. IL-1 alone caused only minor shifts in the subpopulations, but when added together with IL-2 the inhibitory effects of IL-2 were markedly enhanced. Analyses of subsets of CD4-CD8- cells demonstrated that the inhibition was most dramatic at the IL-2R positive and subsequent stages of CD4-CD8- differentiation. Interestingly, the putative precursors of IL-2R+CD4-CD8- increased in the presence of IL-2. In preliminary studies the organ culture system was used to examine the effects of a panel of antibodies to thymocytes and/or thymic stromal cells. Out of 14 antibodies tested, MTS 35 and MTS 37 have caused relative increases in the CD8 and CD4 single-positives, respectively. Both antibodies also induced increases in the percentages of CD4-CD8- cells and decreases in the percentages of CD4+CD8+ cells.

Animals↗
PubMed1989

Thymic epithelial antibodies: immunohistological analysis and introduction of nomenclature.

During the Workshop "The Thymus. Histophysiology and Dynamics in the Immune System', Rolduc, april 1989, a special workshop was hold to characterize monoclonal antibodies (mAb) to thymic epithelial cells (TEC) in thymus of man, mice, and rat. Twenty-five TEC-specific mAb's were evaluated for their immunohistological staining patterns on reference thymus, thymuses during ontogeny, various other organs (all tissues obtained from the species against the mAb was raised) and thymuses of other species. In this report only immunohistological results of reference thymuses and thymuses of other species are described. Based on the staining patterns on reference thymuses, mAb could be subdivided in 5 main groups. It is proposed to use these clusters of thymic epithelial staining patterns (CTES) to designate individual mAb, awaiting the possible incorporation in existing CD nomenclature for leucocyte differentiation antigens. The present immunohistological approach will be extended by additional analysis for which a protocol was designed. The ultimate goal of this TEC-mAb workshop is to get well-characterized reagents in the analysis of TEC-associated molecules with putative function in intrathymic T-cell processing.

Animals↗
PubMed1989

Antigens shared by thymic stromal cells and T lymphocytes are abnormally expressed in AKR thymuses.

Accumulating evidence has shown that thymic stromal-lymphoid interactions play a major role in the development of AKR thymic leukemia. A normal thymic stromal cell (TSC) line B6TE-A, which has been shown to support the in vitro growth of AKR leukemic T cells by forming multicellular complexes with them, was used to raise monoclonal antibodies. Three of these mAb, MTS 31, 32 and 38, in addition to 2 other MTS mAb, are abnormally expressed in the preleukemic and/or leukemic stages in AKR mice. These 5 MTS mAb, which detect antigens on both subpopulations of TSC and T cells, show some reduced cortical reactivity from the pre-leukemic period (MTS 32 and 35) to markedly depressed reactivity in the leukemic period (MTS 31, 32, 33, 35 and 38). While it appears that the major reduction is due to the loss of antigens from the cortical thymocytes, there is some indication that the stromal elements may be affected also. In addition, MTS 29, which was also produced in this study, while only reacting with rare thymic medullary cells in situ was densely distributed on cultured stromal cells from both normal and leukemic thymuses. In this report, the value of these MTS mAb for documenting various stages of AKR leukemogenesis has been clearly demonstrated: their possible modulatory effects on in vitro T cell leukemia growth is currently being investigated.

Animals↗