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Biomedical subjects

A M Herrera

Publications and source records attributed to A M Herrera.

11 recordsLinked to original sources
PubMed2003

Ultrastructure of airway smooth muscle.

There is an abundance of ultrastructural data in the literature on vascular, visceral, and other smooth muscles; such data on airway smooth muscle, however, are conspicuously missing. Here we present a series of electron micrographs depicting contractile and cytoskeletal elements as well as organelles in porcine trachealis. Myosin thick filaments are present in the relaxed muscle; thick filament density increases substantially when the muscle is activated. Actin thin filaments are present in large excess over the thick filaments; the thin/thick filament ratio is about 31/1 in the relaxed state; this ratio is reduced to about 22/1 when the muscle is activated. The sarcoplasmic reticulum is often found associated with caveolae and mitochondria. Cells within a bundle are well connected by intermediate and gap junctions. The results demonstrate that quantitative morphological analysis of ultrastructure of airway smooth muscle fixed under different functional states is possible and will be essential in elucidating the structural basis of adaptation and contraction of the muscle.

Actins↗
PubMed2001

Plasmid DNA-recombinant Opc protein complexes for nasal DNA immunization.

The nasal mucosa may provide a simple, non-invasive route to deliver DNA encoding genes that stimulate a specific immune response. Based on this, a new approach using pCMVbeta-gal plasmid DNA complexed to the Opc meningococcal outer membrane protein was assayed for. Optimal conditions of interaction were established between recombinant Opc protein and pCMVbeta-gal plasmid DNA. Complexes were fully characterized by electrophoresis analysis, DNAse resistance assay and transmission electron microscopy. DNA-protein complexes were also evaluated in in vitro transfection experiments. After the characterisation of complexes, Balb/c mice were intranasal (i.n.) and intramuscularly (i.m.) immunized. The humoral immune response against beta-galactosidase was measured by ELISA. The proliferative response in the spleen lymph nodes was also measured. Complexes administered by i.n. route induced both systemic and mucosal antibody responses. This behavior was not observed with the naked DNA. Finally, a lymphoproliferative response specific to beta-galactosidase induced by DNA-protein complexes was also detected.

Administration, Intranasal↗
PubMed2001

Multivalent DNA-based immunization against hepatitis B virus with plasmids encoding surface and core antigens.

The immune response against hepatitis B surface and core antigens was evaluated by either coinoculation or independent intramuscular administration of pAEC compact DNA immunization vectors carrying their genes. The pAEC vectors bear just the essential elements for mammalian expression and bacterial amplification. Balb/c mice were immunized with 100 microg of each construct, either alone or in combination. In spite of lacking known immunostimulatory sequences (e.g., AACGTT), significant cellular (proliferative) and humoral immune responses were raised against both antigens. Coadministration of both plasmids maintained the immune response against the two antigens, without interference between them. Modulation of the antigen expression and further immune response, by using the Kozak's translation initiation sequence, was also analyzed. No differences due to its presence or absence were observed.

Animals↗
PubMed2000

A family of compact plasmid vectors for DNA immunization in humans.

DNA immunization technology is based on the availability of adequate vectors for cloning and expression of heterologous immunoactive proteins in mammalian cells. We have developed a family of DNA plasmid vectors suitable to manipulate antigen expression and location. Their in vitro and in vivo functionality and application are also reported. The developed immune response, the aspects considered for vector design, and the possible independent manipulation of both blocks for the generation of bicistronic constructs, make of the pAEC family of plasmid vectors a source for DNA vaccine candidate's development for further evaluation in human clinical trials, and for potential use in the gene therapy approach.

Animals↗
PubMed2000

Efficiency of erythropoietin's signal peptide for HIV(MN)-1 gp 120 expression.

The HIV-1 gp120 gene with natural signal sequence expressed in eukaryotic expression systems showed extremely low levels of synthesis and secretion. Several expression systems have been used to improve the secretion levels of gp 120. In mammalian cells, the efficient expression of gp120 fused to t-PA signal peptide has been previously reported. Here, the effects of t-PA and EPO signal peptides were compared as secretion sequences for expression of gp120 in COS-7 cells. The EPO's signal peptide is used for the first time as leader sequence for secretion of foreign proteins. Our results indicated that higher amounts of secreted gp 120 were obtained when vectors containing EPO signal peptide were used.

Amino Acid Sequence↗
PubMed1998

Misrepresentation of research citations among medical school faculty applicants.

PURPOSE: A descriptive study of bibliographic misrepresentations by applicants to medical school faculty positions. METHOD: The authors reviewed 250 1995 faculty applicant bibliographies from eight medical institutions, representing six medical specialities. Using computerized library database searches or direct retrieval, they evaluated the legitimacy of each journal, abstract, and book citation. The authors classified and tabulated the following discrepancies as misrepresentations: (1) citing a nonexistent article in an existent source, (2) claiming authorship on an article that did not list the applicant as an author, and (3) altering authorship order to enhance the applicant's position. RESULTS: The authors found 56 misrepresented citations among 2,149 verified articles (2.6%). These misrepresentations were distributed among 39 applicants (15.6%; 95% CI, 11.5% to 20.9%); 11 of whom (4.4%) had multiple discrepancies. Sixty-eight percent of all misrepresentations were due to discrepancies in authorship order, while journal citations constituted the most frequent source of misrepresentation (77%). CONCLUSIONS: Misrepresentation of bibliographic citations does exist among medical school faculty applicants. One possible solution to this problem would be to require applicants to document their bibliographic citations.

Authorship↗
PubMed1990

Microdialysis sampling for determination of plasma protein binding of drugs.

The use of microdialysis sampling to study the binding of drugs to plasma proteins was evaluated. Microdialysis sampling is accomplished by placing a short length of dialysis fiber in the sample and perfusing the fiber with a vehicle. Small molecules in the sample, such as drugs, diffuse into the fiber and are transported to collection vials for analysis. Larger molecules, such as proteins and protein-bound drugs are excluded by the dialysis membrane. Microdialysis was found to give values for in vitro protein binding in plasma equivalent to those determined by ultrafiltration. Microdialysis offers advantages in terms of maintaining equilibria and experimental versatility. Microdialysis sampling also provides potential use for in vivo determinations of protein binding.

Blood Proteins↗
PubMed1990

Sinusitis. Its association with asthma.

Sinusitis may present as an indolent infection, without the classic symptoms and signs commonly expected, and will probably be missed in children who have only cough and persistent rhinorrhea unless this diagnosis is kept in mind. Plain radiography is the most commonly used diagnostic procedure for sinusitis, but computed tomography may be more sensitive. The contribution of sinusitis to the induction and exacerbation of asthma is still unresolved. The existence of a nasobronchial reflex is not clearly supported by available data, although it is a likely explanation for the observed relationship between the two processes. However, sinusitis appears to be an important underlying trigger for some cases of asthma and, therefore, should be suspected any time that acute or chronic asthma is difficult to control.

Adult↗
PubMed1989

Immunoglobulin composition of three commercially available intravenous immunoglobulin preparations.

To evaluate whether significant differences in immunoglobulin composition exist among the three commercially available intravenous immunoglobulin (IVIG) preparations, we compared three of these products in terms of their quantitative immunoglobulin concentration, IgG subclass concentration, and the presence of IgG aggregates. Three different lots were tested for each of the IVIG formulations, and the IgG subclass assays were performed by three different laboratories. Differences were found among the three formulations in subclass concentration and aggregate content. Sandoglobulin (Sandoz Pharmaceuticals, East Hanover, N.J.) contained a significantly higher amount of IgG2 (p less than 0.002) compared to the other formulations. All the formulations tested were found to be deficient in IgG4 relative to the World Health Organization standards, with Gammagard (Hyland Therapeutics, Glendale, Calif.) demonstrating only negligible amounts. Immunoglobulin aggregate content was different among manufacturers with Gamimmune N (Cutter Biological, Berkeley, Calif.) containing the highest amount of monomer IgG (99.8%). Significant differences were found in the subclass results obtained by the ICN ImmunoBiologicals assay (Lisle, Ill.), compared to the two reference laboratories. This difference among the subclass assays raises the question as to the use of these assays in the evaluation of patients with suspected subclass deficiencies. The differences in subclass concentration and aggregate content in IVIG preparations were great, and future clinical trials with these formulations would be indicated to determine the clinical significance of these findings.

Chromatography, High Pressure Liquid↗