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Biomedical subjects

B Santamaria

Publications and source records attributed to B Santamaria.

5 recordsLinked to original sources
PubMed2000

Late apoptotic effects of taxanes on K562 erythroleukemia cells: apoptosis is delayed upstream of caspase-3 activation.

The efficacy of taxanes on human leukemia cells is the object of intensive in vitro investigation concerning the influence of cell-type-specific characteristics on cytotoxic response to drugs. The present study dissects the response to taxanes of HL60 acute myelomonocytic leukemia and of K562 chronic myelogenous leukemia, in parallel over a 72-hr time-span. The kinetics of cytotoxicity following pulsed and continuous exposure to either taxol or taxotere showed a delayed response of K562 cells independently of dose and type of exposure. In K562 cells, apoptosis became evident at 48 hr and prominent at 72 hr of treatment. These events were mirrored by delayed kinetics of caspase-3 activation. Comparable microtubule targeting was demonstrated in HL60 and in K562 cell lines, as bcl-2 and raf-1 were phosphorylated following treatment with taxanes. These observations indicate that early activation processes were responsible for apoptosis, but that the delay was determined by other factors. In addition, cell-free-system experiments excluded the presence of excess nuclear and/or cytoplasmic inhibitory factors and demonstrated that K562 cells possess a fully competent caspase system which can be readily activated. Processing of caspase-3 pro-enzyme was in fact increased by addition of cytochrome c. These results extend to taxol and taxotere the notion that drug-induced apoptosis is delayed upstream of caspase-3 activation in K562 cells, that such kinetics is independent of drug concentration and exposure time, and that it is linked to intrinsic cellular characteristics mapping between bcl-2 phosphorylation and cytochrome c release.

Apoptosis↗
PubMed2000

Cell activation via CD44 occurs in advanced stages of squamous cell carcinogenesis.

Squamous cell carcinoma (SCC) derives from dysplastic or metaplastic stratified epithelia. The process of squamous cell carcinogenesis has been investigated for the potential role of the adhesion molecule CD44, whose standard form (CD44s) and isoforms generated by alternative splicing of variant exons are known to display altered expression during tumorigenesis in other systems. We have utilized an in vitro correlate of squamous cell carcinogenesis, in which progression stages from normal squamous epithelium to dysplastic lesions and to SCC are represented by primary cultures of normal keratinocytes, by human papilloma virus-immortalized keratinocytes (UP) and by HPVimmortalized/v-Ha-ras transfected tumorigenic keratinocytes (UPR). We investigated expression of CD44 and of variant isoforms, from mRNA to intracellular and surface protein levels, and found no relationship between expression of CD44 and stages of squamous cell carcinogenesis. However, when the function of CD44 was analyzed as Ca(2+) mobilization ability upon monoclonal antibody binding and crosslinking, signal transduction via CD44 was found only for the neoplastic stage (UPR cells). Ca(2+) mobilization was completely independent of density of surface CD44. We have performed similar analyses in an in vitro model of SCC in which four squamous tumor cell lines and UPR cells were sorted according to increasing resistance to external cytotoxic stimuli, i.e. starving conditions, treatment with the retinoid N-(4-hydroxyphenyl)retinamide and cytolytic activity of effector lymphokine-activated killer cells. No relationship between expression of CD44 and level of cell resistance against external cell death-inducing stimuli was found, while CD44-mediated Ca(2+) mobilization ability was restricted to the highly resistant tumor cell lines. Our results indicate that the role(s) of CD44 in squamous cell proliferative disorders can be evinced from the functional features of the molecule, rather than from its phenotypic repertoire.

Apoptosis↗
PubMed1996

Diagnosis and management of asthma: occupational health nurses' awareness and use of national consensus practice guidelines.

A regional sample of members of the American Association of Occupational Health Nurses (AAOHN) from Maryland, Delaware, Virginia, and the District of Columbia was surveyed prior to the publication of the Expert Panel Report on Guidelines for the Diagnosis and Management of Asthma (time 1). The guidelines were disseminated directly to AAOHN members through an article in AAOHN Journal and an annual convention plenary session presentation at which copies of the Report were distributed. They were disseminated indirectly through medical journals and government documents. A follow up survey of AAOHN members' familiarity with and use of the Expert Panel Report was conducted 1 year later (time 2). Of the total eligible sample of 570 persons, 325 (57.0%) responded at time 1. Of these, 232 (71.4%) responded at time 2. One year after publication, 31 (13.4%) of the nurses participating in the time 2 survey were aware of the Report, 16 (6.9%) reported having an available copy of the Report, 31 (13.4%) were familiar with the recommendations in the Report, 17 (7.3%) referred to the guidelines and 34 (14.7%) based care on the guidelines. Multiple direct dissemination strategies of consensus guidelines to improve practice will be necessary if nurses' awareness and use are to be enhanced.

Asthma↗
PubMed1993

An update on the diagnosis and management of pediatric asthma. Based on the National Heart, Lung and Blood Institute expert panel report.

Asthma morbidity and mortality are increasing despite the availability of antiasthma medicines and a broader understanding of the pathology of the disease. In an attempt to enhance the understanding of asthma and to aid in appropriate asthma management, the National Heart, Lung and Blood Institute assembled an expert panel, which developed a report titled "Guidelines for the Diagnosis and Management of Asthma." These guidelines are designed to facilitate patient and health-care-provider education, and diagnosis and management of asthma. Proper diagnosis of the disease is a frequent problem in children and adults. For proper diagnosis of asthma, a complete patient history, physical examination and specific laboratory tests are required. Health care providers who educate patients and their families about common symptom triggers, encourage avoidance techniques and who incorporate state-of-the-art treatment for acute and chronic asthma management may reduce the recent increases in asthma morbidity and mortality while maintaining normal growth and development of the child.

Academies and Institutes↗