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Biomedical subjects

A North

Publications and source records attributed to A North.

At least 19 recordsLinked to original sources
PubMed2005

Arm and ankle blood pressure during caesarean section.

BACKGROUND: We have previously reported that measurement of non-invasive blood pressure during caesarean section under spinal anaesthesia fails in over 50% of cases. We felt that errors would be less likely if blood pressure could be measured at the ankle as it is immobile during caesarean section. The purpose of our study was to determine whether blood pressure measurement at the ankle was equivalent to the arm. METHOD: Following ethical approval, informed consent was obtained from 30 women scheduled for elective caesarean section. Two non-invasive blood pressure cuffs, one on the upper arm and one on the ankle, were used to measure blood pressures at three timed intervals: before spinal insertion, before surgery and after delivery of the neonate. RESULTS: Using the method of Bland and Altman we found that there was only marginal agreement between the two methods. On eight out of 15 occasions where there was a greater than 20% fall in arm systolic blood pressure, this was not detected at the ankle. CONCLUSION: We cannot recommend the use of the ankle to measure blood pressure during caesarean section.

Anesthesia, Obstetrical↗
PubMed2003

Comparison of antibody functionality using different immobilization methods.

This study investigates the influence of antibody immobilization methods on antigen capture. Adsorption and two surface chemistries, an aminosilane chemistry and a common heterobifunctional crosslinker (N-gamma-maleimidobutyryloxy-succinimide ester, GMBS), were compared and evaluated for their ability to immobilize antibodies and capture antigen. The role of protein A as an orienting protein scaffold component in each of these techniques was also evaluated. Through experimentation it was determined that the GMBS technique immobilized the highest amount of antibody and minimized nonspecific binding. For all techniques, the most functional antibodies were found to be those immobilized with protein A. Interestingly, the aminosilane technique demonstrated the highest antigen capture with antibody alone but also exhibited the highest level of nonspecific binding.

Algorithms↗
PubMed2002

Encapsulation of recombinant adenovirus into alginate microspheres circumvents vector-specific immune response.

Pre-existing immunity against adenoviruses may compromise the efficacy of adenoviral vectors for vaccination and gene therapy. The purpose of this study was to determine whether encapsulation of adenovirus recombinants into biodegradable alginate microparticles could circumvent the vector-specific immune response. Mice were immunized either intranasally (i.n.) or intraperitoneally (i.p.) with human adenovirus type 5 (HAd5), resulting in the development of virus-specific antibodies. Immunized and nai;ve mice were inoculated with AdCA36lacZ (an E1-deleted HAd5 recombinant containing the bacterial beta-galactosidase (LacZ) gene), encapsulated (E) into alginate microparticles, or nonencapsulated (NE) ie, as a virus suspension. LacZ expression in animals immunized once (1x) or twice (2x) with HAd5 and subsequently inoculated with NE-AdCA36lacZ (NE-Z) was significantly (P<0.001) reduced compared to those levels observed in NE-Z inoculated nai;ve mice, suggesting that the immune response against the vector adversely affected transgene expression. In contrast, there was only slight reduction (P>0.05) in LacZ expression in mice immunized 1x or 2x with HAd5 that were subsequently inoculated with E-AdCA36lacZ (E-Z) compared to those levels obtained in E-Z inoculated nai;ve animals. Similar results were obtained with i.n. or i.p. inoculated animals. These results indicate that microencapsulation of recombinant adenovirus effectively circumvented the vector-specific immune response.

Adenoviridae↗
PubMed2001

Mice lacking desmocollin 1 show epidermal fragility accompanied by barrier defects and abnormal differentiation.

The desmosomal cadherin desmocollin (Dsc)1 is expressed in upper epidermis where strong adhesion is required. To investigate its role in vivo, we have genetically engineered mice with a targeted disruption in the Dsc1 gene. Soon after birth, null mice exhibit flaky skin and a striking punctate epidermal barrier defect. The epidermis is fragile, and acantholysis in the granular layer generates localized lesions, compromising skin barrier function. Neutrophils accumulate in the lesions and further degrade the tissue, causing sloughing (flaking) of lesional epidermis, but rapid wound healing prevents the formation of overt lesions. Null epidermis is hyperproliferative and overexpresses keratins 6 and 16, indicating abnormal differentiation. From 6 wk, null mice develop ulcerating lesions resembling chronic dermatitis. We speculate that ulceration occurs after acantholysis in the fragile epidermis because environmental insults are more stringent and wound healing is less rapid than in neonatal mice. This dermatitis is accompanied by localized hair loss associated with formation of utriculi and dermal cysts, denoting hair follicle degeneration. Possible resemblance of the lesions to human blistering diseases is discussed. These results show that Dsc1 is required for strong adhesion and barrier maintenance in epidermis and contributes to epidermal differentiation.

Aging↗
PubMed2001

Is visual search really like foraging?

The visual-search paradigm provides a controlled and easy to implement experimental situation in which to study the search process. However, little work has been carried out in humans to investigate the extent to which traditional visual-search tasks are similar to more general search or foraging. Here we report results from a task in which search involves walking around a room and leaning down to inspect individual locations. Consistent with more traditional search tasks, search time increases linearly with display size, and the target-present to target-absent search slope is 1:2. However, although rechecking of locations did occur, compared to more traditional search it was relatively rare, suggesting an increased role for memory.

Adult↗
PubMed2000

Immunization with DNA, adenovirus or both in biodegradable alginate microspheres: effect of route of inoculation on immune response.

To determine the potential for biodegradable alginate microspheres to be used as a delivery vehicle for DNA based vaccines, we constructed a plasmid, pMNe-gal-SV40, containing the bacterial beta-galactosidase (LacZ) gene under the control of the murine cytomegalovirus (MCMV) immediate-early promoter and the simian virus 40 (SV40) polyadenylation signal. The effect of the route of administration and co-administration of adenovirus on systemic and mucosal immune responses were investigated. Mice were inoculated orally, intranasally (i.n.), intramuscularly (i.m.), subcutaneously (s.c.) or intraperitoneally (i.p.) on days 0, 14 and 28 with microspheres containing plasmid DNA, bovine adenovirus type 3 (BAd3) or plasmid DNA + BAd3. Systemic routes of immunization (i.m., s.c. and i.p.) resulted in higher LacZ- or BAd3-specific IgG ELISA titers compared to those obtained by mucosal routes of inoculation (oral and i.n.). Mucosal immunization led to slightly higher titers of LacZ- or BAd3-specific IgA at mucosal sites compared to those obtained by the various systemic routes. All the routes of immunization induced LacZ-specific lymphoproliferation. Co-administration of BAd3 enhanced the LacZ-specific IgG response irrespective of the route of administration.

3T3 Cells↗
PubMed1999

Biodegradable alginate microspheres as a delivery system for naked DNA.

Sodium alginate is a naturally occurring polysaccharide that can easily be polymerized into a solid matrix to form microspheres. These biodegradable microspheres were used to encapsulate plasmid DNA containing the bacterial beta-galactosidase (LacZ) gene under the control of either the cytomegalovirus (CMV) immediate-early promoter or the Rous sarcoma virus (RSV) early promoter. Mice inoculated orally with microspheres containing plasmid DNA expressed LacZ in the intestine, spleen and liver. Inoculation of mice with microspheres containing both the plasmid DNA and bovine adenovirus type 3 (BAd3) resulted in a significant increase in LacZ expression compared to those inoculated with microspheres containing only the plasmid DNA. Our results suggest that adenoviruses are capable of augumenting transgene expression by plasmid DNA both in vitro and in vivo.

3T3 Cells↗
PubMed1998

Desmosomal adhesion inhibits invasive behavior.

Recent studies of human disease and transgenic animal experiments have clearly demonstrated the importance of desmosomes in normal tissue architecture. Furthermore, desmosomal components are down-regulated in certain types of carcinomas, suggesting a possible role for desmosomes in suppression of invasion and metastasis. However, there is no functional evidence to support such a hypothesis. To obtain such evidence, we needed to generate desmosomal adhesion in an invasive cell line. We show that expression of multiple desmosomal components (the desmosomal cadherins, desmocollin and desmoglein, and the armadillo protein, plakoglobin) in nonadhesive L929 fibroblasts generates adhesion in aggregation assays. This adhesion is specifically blocked by short peptides corresponding to the putative cell adhesion recognition sites of desmocollin and desmoglein. This result provides an experimental demonstration of the functional importance of the cell adhesion recognition sites of desmocollin and desmoglein and indicates that both desmosomal cadherins are specifically involved in this adhesion. Moreover, whereas parental L929 cells are strongly invasive into collagen gels, we show that invasion is substantially inhibited in cells transfected with desmosomal components. Invasion is restored by treating the transfected cells with anti-adhesion peptides, indicating that desmosomal adhesion specifically blocks invasion in culture. Our results support the suggestion that desmosomes have a role in suppression of tumor spreading.

Cadherins↗
PubMed1997

Inhibition of neutrophil serine proteinases by suramin.

Suramin, a hexasulfonated naphtylurea recently used as an anti-tumor drug, is a potent inhibitor of human neutrophil elastase, cathepsin G, and proteinase 3. The complexes it forms with these enzymes are partially active on synthetic substrates, but full inhibition takes place when elastase activity is measured with fibrous elastin or when cathepsin G activity is measured using platelet aggregation. One molecule of elastase binds four molecules of suramin with a Ki of 2 x 10(-7) M as determined by enzyme inhibition or intrinsic fluorescence enhancement of suramin. The binding curves show no sign of cooperativity or anticooperativity. The Ki for the complexes with cathepsin G and proteinase 3 are 8 x 10(-8) and 5 x 10(-7) M, respectively. Ionic strength increases the Ki of the elastase-suramin complex in a way that suggests that four of the six sulfonate groups of suramin form ionic interactions with basic residues of the enzyme and that at saturation almost all arginines of elastase form salt bridges with suramin. The neutrophil proteinase-inhibitory activity of suramin might be used to prevent tissue destruction and thrombus formation in diseases where massive infiltration and activation of neutrophils take place.

Cathepsin G↗
PubMed1996

Desmosomes: differentiation, development, dynamics and disease.

Recent evidence on the distribution of desmosomal glycoprotein isoforms that shows their combined expression in individual desmosomes has strengthened the belief that the latter are involved in epithelial differentiation and morphogenesis. It has been shown that cellular interactions and protein kinase C can modulate the adhesive properties of desmosomes in epithelial cell sheets. Genetic studies indicate the involvement of desmosomal components in cancer and epidermal diseases.

Animals↗
PubMed1996

Purification, characterization, assembly and crystallization of assembled alfalfa mosaic virus coat protein expressed in Escherichia coli.

The coast protein of alfalfa mosaic virus (AMV) was cloned and expressed in Escherichia coli as a fusion protein containing a 37 amino acid extension with a (His)6 region for affinity purification. About half of the expressed recombinant coat protein (rCP) was soluble upon extraction and half was insoluble in inclusion bodies. Western blot analysis confirmed the identity of the rCP and protoplast infectivity assays indicated that the rCP was biologically active in an early event of AMV infection, called genome activation. The rCP assembled into T = 1 empty icosahedral particles, as described previously for native coat protein. Empty particles formed hexagonal crystals that diffracted X-rays to 5.5 A resolution. The crystals of trypsin-treated particles of rCP appear to be isomorphous with crystals of trypsin-treated particles of native coat protein, Spherical particles containing RNA assembled when the rCP was combined with in vitro transcripts of AMV RNA4, the smallest naturally encapsidated AMV RNA. Bacilliform particles that resembled native virions assembled when the rCP was combined with transcripts of RNA1, the largest genomic RNA.

Alfalfa mosaic virus↗
PubMedDate not supplied

Product report. Creams.

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Dermatologic Agents↗