Precursors of Langerhans cells

LC are dendritic cells localized in the supra-basal layer of the epidermis and in mucous epithelia. Their density ranges from 200 to 900 cells/mm². Their first function is to take an antigen, process it and present the processed antigen to the lymphocytes ([1] Misery L. La cellule de Langerhans. Editions Techniques, Encycl. Méd. Chir. Dermatologie 1994;12-220-B-10). They are involved in numerous diseases. The origin of these cells has been debated but a consensus has now been reached. Langerhans cells (LC) were first described in 1868 by Paul Langerhans ([2] Über die Nerven der menschlichen Haut. Virch Arch A (Pathol Anat) 1868;44:325–337). He thought that it was a nerve cell. LC were first considered to be a component of the nervous system because their dendritic processes are similar so nerve fibers and because of their staining by gold chloride. Other authors have discussed a possible relationship with melanocytes. LC were regarded either as melanocytes, the progeny of melanocytes after division, or as melanocytes in an arrested stage of development ([3] Masson P. My conception of cellular naevi. Cancer 1951;4:9–15; [4] Fan J, Schoenfeld RJ, Hunter J. A study of the epidermal clear cells with special reference to their relationship to the cells of Langerhans. J Invest Dermatol 1959;32:445–450; [5] Zelickson AS. Granule formation in the Langerhans cell. J Invest Dermatol 1966;47:498–502). S100 protein is expressed on melanocytes, on nerve cells and on LC ([6] Cocchia D, Michetti F, Donato R. Immunochemical and immunocytochemical localization of S100 antigen in normal human skin. Nature 1981;294:85–87), but this does not imply that there is a common lineage. Subsequent research showed that this cell is in fact an immune cell. Electron microscopy has given us a new and very important insight into the nature of LC. Thus, there is no tonofilament, no desmosome and no melanosome ([7] Birbeck MS, Breathnach AS, Everall JD. An electron microscopy study of basal melanocyte and high level clear cell (Langerhans cell) in vitiligo. J Invest Dermatol 1961;37:51–63). The most important ultrastructural feature is the presence of Birbeck granules. Many experiments have pointed to a hone-marrow origin of LC and their probable relationship with the phagocytic mononuclear cell system.     

An emancipatory study of contemporary nursing practice

Changes in health care facilities have created the necessity for individual nurses to change, eg, change jobs, pursue additional education, become independent entrepreneurs. There is a shortage of nurses that places stress on those who remain to care for an increasing number of persons with too few resources. The purposes of this study were to explore nurses' perceptions of the circumstances of their work lives and to describe the processes by which they can create change in these circumstances. The methodology was an emancipatory design combining tenets of critical inquiry and feminist research. The method used was a dialectical process of reflection and action (praxis). Three diverse groups of nurses met weekly over 6-10 weeks. Using the group process method, each group reflected on, discussed, and analyzed the phenomenon of practicing nursing today. The outcome of an emancipatory study is reflected in the power of the process. The group interaction increased awareness, promoted reflection on the status quo, and energized the groups to derive possible solutions to changing that status quo. It is not the solutions themselves that are as relevant as is the obvious cogency of the process to achieve individual and group emancipation. Six codifications reflected the themes that emerged and 5 processes for exploring untested feasibilities for change were identified. The participants perceived themselves more as subjects in their history than objects to be manipulated, capable of transforming a rather dismal situation of nursing practice into one that was critical, creative, and freer from constraints. The implication of this study is that nurses are encouraged to adopt and adapt this process of group interaction because of its demonstrated credibility to empower and validate the role that nurses have to derive and implement solutions to change their unsatisfactory status quo.     

Respiratory frequencies of sleeping infants during the first months of life: Correlations between values in different sleep states

This study was carried out on 57 normal infants: 22 full-term newborns, examined in the hospital laboratory, and 35 2–18-wk-old infants, examined in two resident nurseries. Polygraphic records, including 1–3 complete sleep cycles, were performed during the morning. The tracings were analyzed by 20-sec epochs.Three to 10% of active sleep states (AS) and 0.8-4% of quiet sleep states (QS) included ?3 sec respiratory pauses. There were minimal, non-significant differences between respiratory frequencies (RF) in total and in no-pause tracings.Our results confirmed that RF was higher in AS in all ages, when compared with QS (P < 0.02). During the transition (TS) from one to another well-defined sleep state, the respiratory rate showed an intermediate level (AS > TS > QS): the transition from AS to QS showed progressive slowing of RF, while the transition from QS to AS occurred abruptly, with sudden acceleration of RF. There was a significant slowing of RF during the course of QS, while the RF in AS was more variable without significant differences between the beginning, the middle and the end of AS state. In this material, RF was higher in 2–5-wk and 6–10-wk age groups, compared to newborns and to 11-18-wk-old infants. At all ages, there was a high degree of correlation (P < 0.01) between RF found in different sleep states for given individuals: some infants breathed more rapidly and others more slowly in all sleep states.A review of the literature showed that the differences between normal RF     

Bowel obstruction in patients with metastatic cancer: does intervention influence outcome?

Background: Both surgical and nonsurgical options are available to treat bowel obstruction in patients with metastatic cancer. The goal is straightforward: to restore bowel patency and palliate the symptoms of obstruction. Yet the most appropriate management is often a challenging decision. Aim of the Study: We sought to review our experience in managing patients with metastatic cancer and bowel obstruction. Methods: A retrospective review was performed to identify all patients admitted at University of Wisconsin Hospital between 1993 and 2000 with the diagnoses of both bowel obstruction and metastatic cancer. Demographic data, type of management, postoperative complications, and outcome were analyzed. Results: A total of 114 patients with primarily colorectal or gynecologic malignancies were identified. Patients’ first bowel obstructions were managed in one of two ways: (1) definitive surgical intervention (n=47), or (2) conservative management (n=67). The median overall survival was 3 mo for the entire study group. There was no significant difference in overall or obstruction-free survival based on management, presence of recurrent bowel obstruction, or type of primary cancer. The only factor that was significant in predicting poor overall survival included a disease-free interval of less than 1 yr (time of diagnosis of primary cancer to time of bowel obstruction, p=0.002). Conclusions: Bowel obstruction in patients with metastatic cancer is a terminal event, with a 3-mo median survival. Because there is no difference in overall or obstruction-free survival based on management, the treatment for palliation of bowel obstruction in patients with metastatic cancer should be individualized.     

Hormonal and sensory inputs regulate distinct neuroblast cell cycle properties in adult cricket brain

From invertebrates to humans, it has been demonstrated that new neurons are added to specific brain structures throughout adult life. In the house cricket, adult neurogenesis occurs in the mushroom bodies, the main sensory integrative center of the brain, often considered an analogue of vertebrate hippocampus. We have previously shown that this neurogenesis can be modulated by hormones through the polyamine pathway and by environmental conditions through sensory inputs and the nitric oxide pathway. Environment-induced neurogenesis is independent of juvenile hormone levels, so we addressed the roles of sensory inputs and hormones in the control of neuroblast proliferation. Here, by using double labelling of cells specifically in S phase (5-bromo-2'-deoxyuridine) together with labelling of mitotically active cells in any phase (proliferating cell nuclear antigen), we show that juvenile hormone acts on progenitor cell proliferation by inducing quiescent neuroblasts to enter the cell cycle, whereas sensory inputs act by shortening the cell cycle. Thus, in the adult house cricket, regulation of neuroblast proliferation by hormonal and environmental cues occurs through two independent modes of action.