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Biomedical subjects

A Field

Publications and source records attributed to A Field.

9 recordsLinked to original sources
PubMed1992

Unique region of the minor capsid protein of human parvovirus B19 is exposed on the virion surface.

Capsids of the B19 parvovirus are composed of major (VP2; 58 kD) and minor (VP1; 83 kD) structural proteins. These proteins are identical except for a unique 226 amino acid region at the amino terminus of VP1. Previous immunization studies with recombinant empty capsids have demonstrated that the presence of VP1 was required to elicit virus-neutralizing antibody activity. However, to date, neutralizing epitopes have been identified only on VP2. Crystallographic studies of a related parvovirus (canine parvovirus) suggested the unique amino-terminal portion of VP1 assumed an internal position within the viral capsid. To determine the position of VP1 in both empty capsids and virions, we expressed a fusion protein containing the unique region of VP1. Antisera raised to this protein recognized recombinant empty capsids containing VP1 and VP2, but not those containing VP2 alone, in an enzyme-linked immunosorbent assay. The antisera immunoprecipitated both recombinant empty capsids and human plasma-derived virions, and agglutinated the latter as shown by immune electron microscopy. The sera contained potent neutralizing activity for virus infectivity in vitro. These data indicate that a portion of the amino terminus of VP1 is located on the virion surface, and that this region contains intrinsic neutralizing determinants. The external location of the VP1-specific tail may provide a site for engineered heterologous epitope presentation in novel recombinant vaccines.

Animals↗
PubMed1992

Endometrial resection. A modern treatment of menorrhagia.

In general menorrhagia is poorly understood and tends to be unsatisfactorily treated. The word menorrhagia is derived from the Greek men month and rhegynai, to burst forth. Patients complain of increased menstrual loss, requiring more sanitary protection, or of the passage of clots. Most patients with menorrhagia have no significant uterine abnormality and the woman's interpretation of her blood loss is insufficient and unreliable. Menorrhagia must be defined in terms of measured menstrual blood loss. Many medications effectively diminish blood loss, but the symptoms usually return after the therapy has been stopped. Long term treatment is also restricted due to the potential side effects associated with some drugs.

Catheter Ablation↗
PubMed1991

Self-assembled B19 parvovirus capsids, produced in a baculovirus system, are antigenically and immunogenically similar to native virions.

B19 parvovirus is pathogenic in humans, causing fifth disease, transient aplastic crisis, some cases of hydrops fetalis, and acquired pure red cell aplasia. Efforts to develop serologic assays and vaccine development have been hampered by the virus's extreme tropism for human bone marrow and the absence of a convenient culture system. We constructed recombinants containing either the major (VP2) or minor (VP1) structural proteins of B19 in a baculovirus-based plasmid, from which the polyhedrin gene had been deleted; these recombinant plasmids were used to generate recombinant infectious baculovirus. Subsequent infection of insect cells in vitro resulted in high-level expression of either B19VP1 or VP2. Parvovirus capsids were obtained by self-assembly in cell cultures coinfected with either VP1- and VP2-containing baculoviruses or, surprisingly, VP2-containing baculoviruses alone. Empty B19 capsids composed of VP1 and VP2 could replace serum virus as a source of antigen in a conventional immunoassay for detection of either IgG or IgM antiparvovirus antibodies in human serum. Immunization of rabbits with capsids composed of VP1 and VP2 resulted in production of antisera that recognized serum parvovirus on immunoblot and neutralized parvovirus infectivity for human erythroid progenitor cells. Baculovirus-derived parvovirus antigen can substitute for scarce viral antigen in immunoassays and should be suitable as a human vaccine.

Amino Acid Sequence↗
PubMed1990

Topographic components analysis of evoked potentials: estimation of model parameters and evaluation of parameter uniqueness.

The purpose of this paper is to evaluate the practicability of the 'topographic components model' proposed by Möcks for the spatio-temporal characterization of multi-channel evoked potentials (EP), and to present a complete and detailed algorithm for this method of analysis. Details of the algorithm are discussed along with various computational issues, especially with regard to contrasts with traditional principal components analysis. The algorithm is applied to multi-channel pattern-shift visual EP data obtained from normal subjects, and the model is demonstrated to provide data reduction of 71% with a relative mean-squared error (MSE) of 2%. Obvious features of the data are seen to be reflected in the estimated model parameters, lending support to the appropriateness of the model. The results also demonstrate that although the model parameters are uniquely identifiable in theory, care must be taken when fitting the model to insure that the MSE is not so insensitive to perturbations in the model parameters that they are rendered 'non-unique' for all practical purposes. The proper selection of model order is shown to play a critical role in avoiding this problem. Finally, a theoretical analysis is presented which evaluates the relationship between parameter 'uniqueness', model order, and the non-orthogonality of the model components.

Algorithms↗
PubMed1989

Hereditary white sponge naevus.

The authors report two cases of white sponge naevus in the same family, where the condition had clearly been inherited by the daughter from her mother. The positive family history aided correct diagnosis of this entirely benign lesion.

Adult↗
PubMed1979

Orthoses to fit shoes.

Orthoses which fit inside shoes have, in many cases in the past, been fashioned to the shape of the patient's foot. It is suggested that improved stability and comfort is achieved if, instead, the outside shape of the foot-piece of the orthosis is fashioned to the inside shape of the footwear. A method for achieving this is described.

Artificial Limbs↗
PubMed1970

Mosaic mutants: absence in a eucaryotic organism.

Exposure of procaryotic and eucaryotic cells to mutagenic agents generally gives both complete mutants and mosaic mutants. Irradiation of the eucaryotic multicellular alga Ulva mutabilis with ultraviolet light has given exclusively complete mutants.

DNA Replication↗