Biomedical subjects

F J Martin

Publications and source records attributed to F J Martin.

43 records · Page 3Linked to original sources

PubMed1976

Lipid vesicle-cell interactions. II. Induction of cell fusion.

The ability of lipid vesicles of simple composition (lecithin, lysolecithin, and stearylamine) to induce cells of various types to fuse has been investigated. One in every three or four cells in monolayer cultures can be induced to fuse with a vesicle dose of about 100 per cell. At such dosages and for exposures of 15 min to 1 h, vesicles have essentially no effect on cell viability. Under anaerobic conditions, these cells lyse rather than fuse. Avian erythrocytes are readily fused with lipid vesicles in the presence of dextran. Fusion indices increase linearly with the zeta potential of the vesicles (increasing stearylamine content), indicating that contact between vesicle and cell membrane is required. Fusion indices increase sublinearly with increasing lysolecithin content. Divalent cations increase fusion indices at high vesicle doses. The data presented are consistent with the hypothesis that cell fusion occurs via simultaneous fusion of a vesicle with two adhering cell membranes.

Animals↗

PubMed1976

Lipid vesicle-cell interactions. III. Introduction of a new antigenic determinant into erythrocyte membranes.

The introduction of a new antigenic determinant, 2,4-dinitrophenyl-aminocaproyl-phosphatidylethanolamine (DNP-Cap-PE), into the surface membranes of intact human erythrocytes is described. Fresh cells were incubated in the presence of liposomes composed of 10% DNP-Cap-PE, 5% stearylamine, 20% lysolecithin, and 65% lecithin. Such liposome-treated erythrocytes are shown to be susceptible to immune lysis by anti-DNP serum in the presence of complement. Uptake of DNP-Cap-PE by erythrocyte membranes is also demonstrated by immunofluorescence using indirect staining with rabbit anti-DNP serum followed by fluroescein-conjugated goat anti-rabbit IgG and by electron microscopy using ferritin-conjugated antibody. Antigen uptake did not occur at low temperatures or from vesicles lacking lysolecithin and stearylamine. Fluorescence microscopy shows that the antigen-antibody complexes are free to diffuse over the cell surface, eventually coalescing into a single area on the cell membrane. Electron microscopy suggests that a substantial proportion of the lipid antigen is incorporated by fusion of vesicles with the cell membrane. There are indications that vesicle treatment causes a small proportion of cells to invaginate.

Agglutination↗

PubMed1975

Epidermal neoplasms with epidermolysis bullosa dystrophica with the first report of carcinoma with the acquired type.

Carcinoma, usually always squamous cell carcinoma, is one of the most serious complications in epidermolysis bullosa dystrophica. It can occur on the skin, mucous membranes, the esophagus and possibly the upper part of the bronchial tree. We are reporting on four new patients; one, the youngest to be so reported, one with a definite autosomal dominant inheritance and one with a chronic acquired dystrophica epidermolysis bullosa. Most cases have an autosomal recessive inheritance, but the disorder is probably more hetereogeneous in its inheritance than has been reported. Studies of the collagen indicate a disturbance, but present studies indicate the defect to be more a cellular defect in the fibroblast yet undetermined. The carcinomas, usually multiple, appear to arise on scarred tissue and to metastasize rapidly with death.

Adolescent↗

PubMedDate not supplied

The development and application of protein-liposome conjugation techniques.

Numerous techniques have been developed over the past 10 years for the conjugation of proteins to liposomes. Early procedures involved coupling with reagents such as glutaraldehyde or EDCI. Subsequently, more sophisticated approaches involving selective bifunctional coupling agents have been developed. These later procedures are also much more efficient for coupling in aqueous media. The techniques of coupling have become more rigorous because investigators have recognized the inherent problems of producing, purifying and characterizing protein conjugated liposomes. Protein-liposome coupling techniques were developed mainly for targeted drug delivery. The attachment of specific antibodies to the surface of the liposomes makes them able to bind to cells and to subsequently be internalised by the cells. Protein conjugated liposomes have also been used for various immunochemical and diagnostic purposes. These include the binding of labelled liposomes to cells and the agglutination of cells or latex particles by protein conjugated liposomes.

Agglutination↗

PubMedDate not supplied

Metacarpal cortical thickness by computed radiography in osteoporosis.

Computed radiography was used to make radiogrammetric measurements of the second metacarpal in 240 women, 180 considered normal and 60 osteoporotic. These measurements had a coefficient of variation for the external diameter of 0.74% in normal women and 0.75% in osteoporotic women, and for the internal diameter of 2.4% and 2.03%, respectively. The group of women with osteoporosis was divided according to external diameter and internal diameter into a group with osteoporosis due to increased bone resorption (61.1%, normal external diameter and increased internal diameter), and osteoporosis due to deficient bone formation (26.1%, decreased external diameter and normal internal diameter). In the remaining subjects (12.8%), osteoporosis was attributed to both mechanisms. There was a significant linear regression between internal diameter and tartrate-resistant acid phosphatase concentration (p < 0.0001) in the group of increased bone resorption, which was absent (p = ns) in the group with deficient bone mass formation. No changes were observed in the size of the two groups. The low coefficient of variation of radiogrammetric measurements with computed radiography validate it as an accurate technique for bone mass studies. Moreover, it has the additional advantage of permitting determination of the proportion of women with osteoporosis due to increased bone resorption and/or deficient bone mass formation.

Acid Phosphatase↗

PubMedDate not supplied

Epilogue. Establishment of the Center for Chronic Disease Prevention and Health Promotion.

The establishment of the Center for Chronic Disease Prevention and Health Promotion (CCDPHP) at the Centers for Disease Control (CDC) following the Conferences on the State of the Art in Quality Control Measures for Diagnostic Cytology Laboratories is briefly discussed. The CCDPHP is expected to play a major role in the CDC's cancer control program, including participation in establishing effective screening programs and assuring the quality of such methodologies as the Papanicolaou test and mammography.

Centers for Disease Control and Prevention, U.S.↗

PubMedDate not supplied

Measuring screening skills in gynecologic cytology. Results of voluntary self-assessment.

When the Clinical Laboratory Improvement Act (CLIA) was passed in 1967, the Centers for Disease Control (CDC) became interested in evaluating screening performance in cytodiagnosis. Finding no validated performance measurement methods that could be used on a national scale, the CDC initiated a program of sequential investigations to develop information that would describe the state of the art in microscopic performance in gynecologic cytopathology. The first of these experiments developed a method, the Self-Assessment Workshop, to measure performance at the microscope by using sets of glass slides. This paper describes the method, its validation process and participant performance over a 15-year period. Study results indicated that cytotechnologists and pathologists tended to correctly identify specimens (slides) in the negative and benign reaction categories in up to 95% of responses, but on slides of dysplasia they made 12% of their calls too low. Carcinomas in situ and invasive squamous cancers were undercalled in only about 5% of responses, but endometrial adenocarcinomas and other rare malignancies were undercalled in as much as 20%. The self-assessment technique is a practical, useful tool for identifying cytology personnel with serious deficiencies in cell location/identification skills and is well accepted by cytotechnologists and pathologists. However its limitations should be kept in mind: screening results from this simulated test should not be extrapolated to routine work performance; the screening time limit of five minutes per slide may adversely affect performance; and, finally, these results may reflect state-of-the-art performance only in voluntary, not mandatory, settings.

Adult↗