Biomedical subjects

C Bono

Publications and source records attributed to C Bono.

12 recordsLinked to original sources

PubMed1999

Occipital screw pullout strength. A biomechanical investigation of occipital morphology.

STUDY DESIGN: A three-group design with consistent pullout strength measures. OBJECTIVES: To determine pullout strength of three fixation types (unicortical screws, bicortical screws, wires) and to investigate their correlation with respect to occipital morphology. SUMMARY OF BACKGROUND DATA: A secured, multidirectional occipitocervical fusion requires internal fixation. Devices secured at occipital protuberance were suggested to offer the greatest pullout strength because of this region's thickness. METHODS: Twelve fresh human cadaveric occiputs were sketched with a grid delineating 21 fixation sites. Each site was drilled and hand-tapped. Four specimens were instrumented with unicortical screws on one side of the midline and bicortical screws on the other. Another four were instrumented with bicortical screws and wires, and the remaining four were instrumented with unicortical screws and wires. Two points on each specimen were secured with identical fixation to examine side-to-side symmetry. An MTS materials testing apparatus (MTS Systems Corporation, Eden Prairie, MN) was used to displace the fixators. Pullout strengths at different anatomic locations were recorded. RESULTS: The greatest pullout strength was at the occipital protuberance for all fixation types. The bicortical pullout strength was 50% greater than unicortical. The wire pullout strength was not significantly different from that of the unicortical screw (P > 0.05). Seventy-eight percent of wires broke at 1100 N. Unicortical pullout strength at occipital protuberance was comparable with that of the bicortical screw at other locations. CONCLUSIONS: Unicortical screw fixation at occipital protuberance offers acceptable pullout strength without the potential complications of bicortical screws or wire fixation.

Biomechanical Phenomena↗

PubMed1997

Anatomy of the posterior interosseous nerve in relation to fixation of the radial head.

The relationship of the posterior interosseous nerve to the radial neck as it relates to internal fixation of radial head fractures was studied in 50 fresh anatomic specimen arms. After a standard posterolateral approach, blind subperiosteal dissection was performed distally until a 4-cm minifragment plate could be placed on the shaft of the radius. Dissection of the radial nerve was performed under loupe magnification. In only one (2%) arm did the posterior interosseous nerve lie directly on the radius. The average distance from the posterior interosseous nerve to the plate was 5 +/- 1.2 mm. The nerve was not damaged by placement of the plate in any case. In two (4%) cases the nerve play on top of the distal portion of the plate within the supinator with the forearm in neutral rotation. The average distance from the radial head to the origin of the posterior interosseous nerve was 1.2 +/- 1.9 mm, with the takeoff being proximal to the radial head in 31 cases. The muscular branch to the extensor carpi radialis longus was located 7.1 +/- 1.8 mm from the radial head. These findings suggest that pronation of the forearm with blind subperiosteal dissection for plate placement does not place the posterior interosseous nerve at significant risk for structural injury. However, as with any approach done in the region of the nerve, caution should be used to avoid tension on the nerve that could lead to physiologic injury.

Bone Plates↗

PubMed1994

Peptide binding to surface class II molecules is the major pathway of formation of immunogenic class II-peptide complexes for viable antigen presenting cells.

Although studies on fixed APCs have demonstrated that peptide can bind to cell surface class II molecules, the mechanisms by which peptide-class II complexes are formed in viable cells is largely unexplored. To explore the possibility that peptide loading of class II molecules was occurring after endocytosis of peptides as well as by surface binding, we utilized an immunogenic hemagglutinin peptide (HAP 128-145) from the influenza strain A/Japan/57, and studied the appearance of surface complexes of HAP 128-145 bound to HLA-DRw11 molecules on human B-lymphoblastoid cells (BLCLs). Detection of the bound peptide was made possible by a rabbit anti-serum (alpha HAP) raised against HAP 128-145, which recognizes both the free peptide as well as peptide bound to DRw11 on living APCs. Pretreatment of the BLCLs with a variety of inhibitors of protein synthesis and intracellular trafficking failed to decrease the levels of HAP 128-145/DRw11 surface complexes. However, significant inhibition in the appearance of these complexes was caused by a decrease in the temperature at which the cells were incubated with peptide. Temperature-specific inhibition was also observed for fixed DRw11-positive APCs and purified DRw11 molecules indicating that the effect of temperature was directly on the class II molecules. We conclude that surface binding of peptide by class II molecules on human B cells is a major pathway of formation of immunogenic class II-peptide complexes for at least some soluble antigenic peptides, and that endocytosis of soluble peptides with subsequent binding of peptide by intracellular class II molecules plays little if any role in the formation of such complexes. Moreover, class II molecules have evolved to stably bind peptide optimally at physiologic temperatures, independent of cell metabolism.

Amino Acid Sequence↗

PubMed1992

Nerve growth factor modulates the expression of muscarinic cholinergic receptor messenger RNA in telencephalic neuronal cultures from newborn rat brain.

The effect of nerve growth factor (NGF) on muscarinic receptor subtypes was investigated in a primary culture of telencephalic neurons prepared from neonatal rats. The treatment with 100 ng/ml of NGF significantly enhanced choline acetyltransferase (ChAT) activity and intracellular acetylcholine (ACh) content during cultivation. The same treatment induced an early transient increase of the number of muscarinic cholinergic receptors (mAChR), as measured by [3H]quinuclidinyl benzilate binding to cell homogenate, that was followed by a dramatic decrease of the receptor density from the 9th day of culture. Atropine completely prevented the decrease of the maximal number of muscarinic recognition sites induced by NGF. Prolonged exposure of telencephalic neurons to NGF also induced a significant reduction of the relative content of the messenger RNA (mRNA) encoding m1 and m3 receptors, while the m4 transcript was increased by the treatment. We suggest that the prolonged stimulation of cholinergic neurons by NGF induces a downregulation of m1 and m3 mAChR and their mRNAs on the postsynaptic site, while it increases the synthesis of the functionally distinct m4 receptor subtype, which might be presynaptically localized on cholinergic neurons. The transient increase of the receptor number that occurs at the first days of culture was not paralleled by changes in the relative content of mAChR mRNAs and might be associated with the trophic activity of NGF on cholinergic synapses during early development.

Animals↗

PubMed1991

Recognition of the influenza hemagglutinin by class II MHC-restricted T lymphocytes and antibodies. I. Site definition and implications for antigen presentation and T lymphocyte recognition.

We have identified the site encompassing residues 126-145 on the A/Japan/57 influenza hemagglutinin molecule that is recognized in association with HLA-DRw11 by a clonal population of human, influenza specific, CD4+ cytolytic T lymphocytes. The critical core sequence of the T cell determinant spans hemagglutinin residues 129-140 and overlaps a putative antibody binding site. Hemagglutinins of influenza field strains that are not recognized by the T cell clones contain sequence alterations within the 129-140 target site of the CD4+ T cells. Functional analyses, with synthetic peptides, of the contribution of each of the residues within the sequence toward the capacity of the antigenic fragment to associate with both the restriction element and the TCR revealed a continuous linear array of residues necessary for MHC binding and/or Ag receptor engagement. At least one residue, the lysine at position 134, was shown to be critical for both DRw11 association and TCR recognition. The significance of these findings for recognition of glycoproteins by human CD4+ T cells is discussed.

Amino Acid Sequence↗

PubMed1991

Invariant chain influences post-translational processing of HLA-DR molecules.

HLA class II MHC molecule alpha- and beta-chains are normally synthesized in the presence of a third molecule, the invariant chain (Ii). Although Ii is not required for surface expression of HLA class II molecules, the influence of Ii on post-translational processing and maturation HLA class II molecules has not been thoroughly studied. In the present study, BALB/c 3T3 cells were transfected with HLA-DR alpha- and beta-chains with or without co-transfection with human Ii. Although Ii had no effect on the surface expression of DR, Ii did have a profound effect on the post-translational processing of both the alpha- and beta-chains. In the absence of Ii, the major species of alpha- and beta-chains were of lower m.w. than when expressed in the presence of Ii. The differences in m.w. were shown to be caused by differences in glycosylation with the majority of alpha- and beta-chains remaining unprocessed and endo H sensitive in the absence of Ii. The small proportion of alpha-chains that were processed in the absence of Ii showed an altered m.w. and altered sensitivity to treatment with endo H relative to alpha-chains processed in the presence of Ii. Pulse/chase studies demonstrated that although the majority of the alpha- and beta-chains remained unprocessed in the absence of Ii, the small amount that was processed was done so at a rate similar to that observed for alpha- and beta-chains processed in the presence of Ii. These studies demonstrate that Ii influences the post-translational processing of human class II molecules by affecting the proportion of alpha- and beta-chains that are processed and by determining the degree of processing of oligosaccharides on mature alpha-chains.

Animals↗

PubMed1991

Antibody recognition of an immunogenic influenza hemagglutinin-human leukocyte antigen class II complex.

The A/Japan/57 influenza hemagglutin (HA) peptide HA 128-145, when bound by human histocompatibility leukocyte antigen-DRw11 cells, is recognized by the human CD4+ T cell clone V1. A rabbit antiserum has been raised against HA 128-145 which recognizes not only the free peptide, but also the HA 128-145/DRw11 complex on a solid matrix, in solution, or on the surface of viable cells. The detection of these complexes on viable cells was shown to be class II specific, DRw11 restricted, and commensurate with the level of DRw11 expression. The identity of DRw11 as the cell surface molecule binding HA 128-145 was confirmed by immunoprecipitation, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and tryptic peptide mapping. Using this antiserum HA 128-145/DRw11 complexes could be detected on the cell surface as soon as 30 min after the peptide was added, and increased up to 24 h. Dissociation kinetics showed these complexes were long-lived, with a half-life of approximately 14 h. This anti-HA peptide antiserum represents the first direct means of studying antigenic peptide-human leukocyte antigen class II complexes on the surface of living cells without the addition of a non-amino acid moiety to the peptide. The properties of this antiserum thus provide the potential to study naturally processed antigenic peptides as well as the mechanism of processing itself in a physiologically relevant system.

Amino Acid Sequence↗

PubMed1987

The HLA-class II-associated chondroitin sulfate proteoglycan expressed by class II positive T and monocyte-like cell lines is larger than that expressed by EBV-transformed B-lymphoblastoid cell lines.

The human class II-associated chondroitin sulfate proteoglycan (CSPG) was originally detected as an approximately 40-70 kd species from normal human tonsil cells and Epstein-Barr virus (EBV) transformed B-lymphoblastoid cell lines. The identification of the invariant chain as the core protein of the CSPG allowed us to directly assay for the CSPG on both class II positive and negative immunocompetent cells of other lineages. Our results indicate that the CSPG is present on the class II-positive monocyte-like cell line U937 and T-cell line HUT-102, but not on the class-II negative T-cell line CCRF/CEM. No class II positive cells were found that did not also express the CSPG. The expression of the CSPG on U937 cells is increased after stimulation with gamma-interferon and PMA, paralleling the previously described increase in class II and invariant chain expression. In addition, the CSPGs from U937, HUT-102, and Raji, all cell lines derived from human malignancies, migrate as an approximately 55-90 kd species, larger than the CSPG previously characterized. However, the core proteins of the CSPG from all cells studied appear as two bands of 38 and 28 kd, indicating the size difference in the CSPG is attributable to differences in the glycosaminoglycan chains.

B-Lymphocytes↗

PubMed1986

The human invariant chain is the core protein of the human class II-associated proteoglycan.

The human class II-associated chondroitin sulfate proteoglycan (CSPG) was analyzed biochemically and immunologically to determine a possible relationship with the human invariant chain (gamma 1) and its related components. The CSPG was purified by a three-step procedure involving associative ion-exchange chromatography, immunoprecipitation, and dissociative ion-exchange chromatography. Treatment of the CSPG with chondroitinase revealed core proteins of Mr approximately 46,000, 38,000, and 28,000, with the 38,000 species most highly represented. Tryptic peptide analysis revealed identity of the peptides of the 38,000 Mr core protein and gamma 1, and of the 28,000 Mr species and p25. The CSPG and its core proteins were shown to react directly with the mouse anti-human invariant chain monoclonal antibody VIC-Y1 and a rabbit antiserum produced against a synthetic peptide corresponding to the C-terminal end of invariant chain. These results demonstrate that the invariant chain is the core protein of the class II-associated CSPG. In addition, virtually all the CSPG was shown to be present on the cell surface.

Antigens, Differentiation, B-Lymphocyte↗

PubMed1986

A new polymorphic determinant on HLA-DQ molecules.

In man, the immune response genes are located within the HLA-D/DR region, and the gene products, the Ia antigens, are expressed on B lymphocytes, monocytes, and a percentage of null cells and activated T lymphocytes. We recently identified a human Ia antigen, K19, which appeared to be limited in its expression to B lymphocytes, and to be preferentially expressed on the more mature cells within this population. This work was facilitated by a monoclonal antibody. HK-19, which recognized a monomorphic determinant of this Ia molecule. We now report the characterization of a second monoclonal antibody, HK-13, which recognized the same molecule as HK-19, but only on cells from some individuals. The greater affinity of HK-13 allowed more complete characterization of the K19/K13 molecule. This characterization included cytofluorography, two-dimensional gel electrophoresis, tryptic peptide mapping, and partial N-terminal amino acid sequencing, and indicated that K19 and K13 were epitopes on HLA-DQ (DC) molecules. The pattern of reactivity of HK-13 on a panel of typing cells did not correlate with any of the known HLA-DQ polymorphic determinants. Thus, HK-13 is a new polymorphic determinant of the HLA-DQ series.

Amino Acid Sequence↗

PubMed1985

The molecules recognized by anti-MT2 alloantisera and anti-MT2-like (DRw52) monoclonal antibodies are different.

The human class II alloantigens include the HLA-DR, DQ, and MT determinants. Previous reports in the literature suggest that while the DQ determinants appear to be on a molecule separate from DR, the MT determinants are variably present on DR or DQ molecules. We have previously reported, using the homozygous DR5 cell line Swei, that the MT4 determinant defined by the allosera, MGH88B, was only on the DQw3 molecule, while MT2, defined by the functionally monospecific anti-MT2 alloantiserum MGH87B, was present on both the DR5 and DQw3 molecules. We now report using the monoclonal antibody ILR2 directed against an MT2-like determinant DRw52, that DRw52 is present on the DR molecules only. The MT2 determinant(s) recognized by the functionally monospecific alloantisera MGH87B appear to include the DRw52 determinant(s) recognized by the monoclonal antibody ILR2.

Animals↗

PubMed1979

In vivo activation of murine peritoneal macrophages by Nocardia water soluble mitogen (NWSM).

In vitro NWSM has been shown to be a B cell mitogen and a polyclonal activator. Although NWSM has been also shown to be adjuvant active in vivo, motogenicity and polyclonal activation are not observed when this fraction has been administered to mice. In contrast, the experiments reported here demonstrate that after in vivo administration several effects of NWSM on mouse peritoneal macrophages can be observed: NWSM was able to induce an important increase in the ability of peritoneal macrophages to inhibit in vitro growth of tumor cells, to increase their phagocytic activity and to enhance their ability to induce an immune response, following the incubation with an antigen NWSM was able to stimulate phagocytic activity of macrophages of C3H/He Orl. mice (LPS-resistant strain). Those findings suggest that the adjuvant activity of NWSM in vivo can be related to its capacity to activate macrophages.

Adjuvants, Immunologic↗