Community action and reflective practice in health promotion research

While health promotion practitioners are engaging increasingly in research, there has been little examination of the practical dilemmas they may face in negotiating and collaborating with academics and community members in action research projects. This paper analyses how the practice of health promotion can interact with action research, and considers issues that arise for organizationally based health promotion practitioners and professional researchers. The first section charts types of action research along three dimensions (power, goals/values, resources). The second section examines some of the issues and practical dilemmas which arise in negotiating and researching collaborative projects in community health promotion. The discussion includes the differing perspectives of: practitioners (managerial and frontline), community members and academic researchers. The final section outlines a hybrid model of action research, developed in our work with community members, organizationally based health promoters and academy-based researchers. It combines the reflective practice of practice-based action research with the community participation and control of participatory research. The model is called community reflective action research.     

CO2 transport in agnathan blood: evidence of erythrocyte Cl-/HCO3- exchange limitations

CO2 transport properties of blood were examined in the lamprey Petromyzon marinus and the hagfish Myxine glutinosa. In order to evaluate possible chloride/bicarbonate exchange limitations, experiments were conducted under control conditions and in the presence of an ionophore to permit equilibrium distribution of chloride, bicarbonate, and protons across the erythrocyte membrane. The ionophore, tri-n-propyl tin chloride, markedly altered the CO2 transport properties and apparent nonbicarbonate buffering characteristics of the blood of Petromyzon marinus. In addition, the distributions of protons, bicarbonate and chloride ions across the erythrocyte membrane were very different from each other under control conditions, but became very similar in the presence of the anionic ionophore. The CO2 transport properties of the blood of Myxine glutinosa were not significantly different in the presence of the ionophore. Small but significant changes were observed, however, in erythrocyte pH, chloride concentration and water content in the presence of tri-n-propyl tin chloride. These results demonstrate that chloride/bicarbonate exchange limitations and possibly active transport of protons contribute to the unique CO2 transport properties in the blood of the lamprey, Petromyzon marinus. In the hagfish, Myxine glutinosa, the importance of anion exchange limitations or active proton transport with regard to the CO2 carrying properties of the blood are clearly much less than in the lamprey under the in vitro conditions of this study.     

Exclusive involvement of folliculosebaceous units by herpes: a reflection of early herpes zoster

The histopathological changes of herpes simplex, herpes zoster, and varicella are considered to be indistinguishable from one another. Evaluation of the clinical setting, with adjunctive studies if necessary, generally clarifies the specific diagnosis. Vesicular lesions in all three conditions can involve epidermal and adnexal epithelium with characteristic cytopathic features. We describe three patients with non-vesicular eruptions on the head and neck whose biopsies revealed exclusive folliculosebaceous involvement by herpes. All three patients developed typical herpes zoster within days of the biopsy. There is compelling scientific evidence in the literature indicating that, in herpes zoster, the virus is transported from dorsal root or trigeminal ganglia via myelinated nerves to the skin. These terminate at the isthmus of hair follicles and primary infection of follicular and sebaceous epithelium occurs. Spread of infection to the epidermis follows. In contrast, data pertaining to recurrent herpes simplex indicates that axonal transport of the virus from sensory ganglia to the skin is directed primarily to the epidermis, via terminal non-myelinated nerve twigs. The clinical evolution of our three cases and scientific data in the literature indicate that exclusive folliculosebaceous involvement by herpes, in the setting of a non-vesicular eruption, represents early herpes zoster.     

Mechanisms of metabolic defense against hypoxia in hibernating frogs.

The cold submerged frog (Rana temporaria) serves as a useful model for many hibernating ectotherms that take refuge in hypoxic ponds and lakes until more favourable conditions of climate and food availability return. In all such animals, entry into a hypometabolic state effectively extends their survival time by lessening the impact of ATP demands on endogenous substrates. At the cellular level, metabolic depression may be brought about by decreasing energy-consuming processes and/or by increasing the efficiency of energy-producing pathways. Since the mitochondrion is the major contributor to the total energy production during aerobic metabolism and frog survival during winter depends on entry into a hypometabolic state, this review focuses on the respiratory properties of mitochondria that serve to increase the efficiency of energy production in hibernation. Energy conservation during overwintering also occurs through decreases in the ATP demand of the energy-consuming processes. For example, hibernating frogs decrease their ATP demands for Na(+)/K(+)-ATPase activity as part of a coordinated process of energy conservation wherein O(2)-limitation initiates a generalised suppression of ion channel densities and/or channel leak activities. The net result is that cell membrane permeabilities are reduced, thereby lowering the energetic costs of maintaining transmembrane ion gradients.     

Gas exchange and acid-base regulation in the blood and extraembryonic fluids of the developing chicken embryo.

Measurements of pH, PCO2, PO2 and total CO2 were recorded simultaneously in samples of chorioallantoic fluid, amnionic fluid and blood of the chorioallantoic artery from chicken embryos on days 8, 10, 12, 14, 16, 17 and 18 of incubation. During the incubation period studied, PCO2 levels similarly increased in the blood and extraembryonic fluids. The pH of the blood and amnionic fluid remained approximately constant while the chorioallantoic fluid became progressively acidic. Increases of amnionic fluid and blood HCO-3 indicated that respiartory compensation processes regulate pH. In addition, the disappearance of chorioallantoic fluid HCO-3 suggested that reabsorptive processes may conserve these ions and contribute them to the amnionic fluid by either a direct transfer through the amnioallantoic membrane or by way of the chorioallantoic vascular system.     

An efficient helper-virus-free method for rescue of recombinant paramyxoviruses and rhadoviruses from a cell line suitable for vaccine development

Recovery of recombinant, negative-strand, nonsegmented RNA viruses from a genomic cDNA clone requires a rescue system that promotes de novo assembly of a functional ribonucleoprotein (RNP) complex in the cell cytoplasm. This is accomplished typically by cotransfecting permissive cells with multiple plasmids that encode the positive-sense genomic RNA, the nucleocapsid protein (N or NP), and the two subunits of the viral RNA-dependent RNA polymerase (L and P). The transfected plasmids are transcribed in the cell cytoplasm by phage T7 RNA polymerase (T7 RNAP), which usually is supplied by infection with a recombinant vaccinia virus or through use of a stable cell line that expresses the polymerase. Although both methods of providing T7 RNAP are effective neither is ideal for viral vaccine development for a number of reasons. Therefore, it was necessary to modify existing technology to make it possible to routinely rescue a variety of recombinant viruses when T7 RNAP was provided by a cotransfected expression plasmid. Development of a broadly applicable procedure required optimization of the helper-virus-free methodology, which resulted in several modifications that improved rescue efficiency such as inclusion of plasmids encoding viral glycoproteins and matrix protein, heat shock treatment, and use of electroporation. The combined effect of these enhancements produced several important benefits including: (1) a helper-virus-free methodology capable of rescuing a diverse variety of paramyxoviruses and recombinant vesicular stomatitis virus (rVSV); (2) methodology that functioned effectively when using Vero cells, a suitable substrate for vaccine production; and (3) a method that enabled rescue of highly attenuated recombinant viruses, which had proven refractory to rescue using published procedures.     

Merkel cell carcinoma: squamous and atypical fibroxanthoma-like differentiation in successive local tumor recurrences

Merkel cell carcinoma (MCC) is a rare, frequently lethal, primary neuroendocrine carcinoma of the skin. Histopathologically, it appears as a dermal nodule of small, undifferentiated malignant cells. Historically, MCC was considered to be an eccrine carcinoma. Recognition of its neuroendocrine features later led to the hypothesis that it arose from Merkel cells in the skin, although recent evidence revisits the question of an epithelial origin. We present a case of MCC arising on the temple of a 78-year-old male, in association with an actinic keratosis. Three years later, a local tumor recurrence showed a mixed malignancy comprising small cell neuroendocrine and large cell squamoid components. A further recurrence at the site two years later, after local radiotherapy, revealed a bizarre pleomorphic large cell morphology with retention of immunohistochemical features of a neuroendocrine carcinoma. Evolution to a bizarre pleomorphic large cell neoplasm has been recorded in malignant tumors treated by radiotherapy, but is unique for MCC. The association of this MCC with an actinic keratosis and the development of squamoid differentiation in a local recurrence support the link between MCC and epithelial neoplasia. In addition, its evolution to an atypical fibroxanthoma-like morphology is of interest, because some view atypical fibroxanthomas as bizarre variants of squamous cell carcinoma.