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Biomedical subjects

J Samuel

Publications and source records attributed to J Samuel.

106 records · Page 6Linked to original sources
PubMedDate not supplied

Liposomal formulations of synthetic MUC1 peptides: effects of encapsulation versus surface display of peptides on immune responses.

Synthetic human MUC1 peptides are important candidates for therapeutic cancer vaccines. To explore whether a human MUC1 peptide BP25 (STAPPAHGVTSAPDTRPAPGSTAPP) can be rendered immunogenic by incorporation in liposomes, the effects of physical association of the peptide with liposomes on immune responses were investigated. Lipid conjugated and nonconjugated MUC1 peptides were incorporated in liposomes with a composition of distearoylphosphatidylcholine/cholesterol/dimyristoylphosphatidylglyc erol (3:1:0.25, molar ratio) containing monophosphoryl lipid A (1% w/w of the total lipids). Liposomes were characterized for peptide retention by HPLC and for surface peptide display of MUC1 epitopes by flow cytometry. C57BL/6 mice were immunized with lipopeptide alone, peptide mixed with peptide-free liposomes, and peptide associated with liposomes in entrapped or surface-exposed forms. T cell proliferative responses, cytokine patterns, and antibody isotypes were studied. Results showed that immune responses were profoundly influenced by the liposome formulations. Physically associated, either encapsulated or surface-exposed, peptide liposomes elicited strong antigen-specific T cell responses, but not lipopeptide alone or peptide mixed with peptide-free liposomes. Analysis of the cytokines secreted by the proliferating T cells showed a high level of IFN-gamma and undetectable levels of IL-4, indicating a T helper type 1 response. Thus, physical association of the peptide with liposomes was required for T cell proliferative responses, but the mode of association was not critical. On the other hand, the nature of the association significantly affected humoral immune responses. Only the surface-exposed peptide liposomes induced MUC1-specific antibodies. A domination of anti-MUC1 IgG2b over IgG1 (94 versus 6%) was observed. Our results support the hypothesis that different immune pathways are stimulated by different liposome formulations. This study demonstrated that a liposome delivery system could be tailored to induce either a preferential cellular or humoral immune response.

Amino Acid Sequence↗
PubMedDate not supplied

Tuberculous mastoiditis.

Twenty-three cases of tuberculous mastoiditis are presented, nine of which were complicated by facial palsy. Six presented with acute mastoiditis, and two had meningitis. Surgery was required in 16 patients; in four cases the diagnosis was made by culture and in another four by biopsy of the granulations or polyp of the external canal. The response to antituberculous treatment was satisfactory in 22 cases. One patient, whose case was complicated by meningitis, died.

Adolescent↗
PubMedDate not supplied

Amyloidosis of Waldeyer's ring. A clinical and ultrastructural report.

Amyloidosis of the tonsil is a rare condition and amyloidosis of Waldeyer's ring has not been previously reported. The present study describes a case of amyloidosis of the tonsil, nasopharynx and base of tongue in a 35-year-old patient in otherwise good health and without clinical symptoms. The possibility of systemic amyloidosis was excluded by clinical examination and biopsy of rectal and buccal mucosae. Electron microscopy showed the presence of typical amyloid fibrils. Large masses of the fibrils were closely surrounded by cells which appeared to be phagocytic. The ultrastructure of these cells is described. This case is considered to be a unique type of organlimited amyloidosis of Waldeyer's ring.

Adult↗
PubMedDate not supplied

Kawasaki disease.

Kawasaki disease is an acute vasculitis of small- and medium-sized blood vessels which was first described by Dr Tomisaku Kawasaki in 1967. Involvement of the coronary arteries is common and may be life threatening or cause long-term cardiovascular complications.

Antibody Formation↗