Media literacy perspectives

Media literacy education involves cognitive processes used in critical thinking. Media workshops and curricula emphasize moral values (the defensive, inoculation approach), discriminating responsiveness (the critical viewer), antimedia resistance, and consumer revolution. Inductive media literacy programs promote independent critical thinking. Media content is a limited predictor of potential effects of media exposure. Meaning is situated in what audiences bring to their media experience (selective perception), the context in which they use media (accommodation), and how and why they use the medium (use and gratifications). To succeed, a curricular program of media literacy requires collaboration among teachers, administrators, specialists, and parents.     

Assessment of pituitary function after transsphenoidal hypophysectomy in beagle dogs

Pituitary function was assessed in healthy adult beagle dogs before and after hypophysectomy. Anterior pituitary function was tested by use of the combined anterior pituitary (CAP) function test, which consisted of sequential 30-sec intravenous injections of four hypothalamic releasing hormones, in the following order and doses: 1 microgram of corticotropin-releasing hormone (CRH)/kg, 1 microgram of growth hormone-releasing hormone (GHRH)/kg, 10 micrograms of gonadotropin-releasing hormone (GnRH)/kg, and 10 micrograms of thyrotropin-releasing hormone (TRH)/kg. Plasma samples were assayed for adrenocorticotropin (ACTH), cortisol, GH, luteinizing hormone (LH), and prolactin (PRL) at multiple times for 120 min after injection. Pars intermedia function was assessed by the alpha-melanotropin (alpha-MSH) response to the intravenous injection of the dopamine antagonist haloperidol in a dosage of 0.2 mg/kg. Posterior pituitary function was assessed by the plasma vasopressin (AVP) response to the intravenous infusion of 20% saline. Basal plasma ACTH, cortisol, thyroxine, LH. PRL, and AVP concentrations were significantly lower at 10 wk after hypophysectomy than before hypophysectomy. In the CAP test and the haloperidol test, the peaks for the plasma concentrations of ACTH, cortisol, GH, LH, PRL, and alpha-MSH occurred within 45 min after injection. At 2 and 10 wk after hypophysectomy, there were no responses of plasma GH, LH, PRL, and alpha-MSH to stimulation. In four of eight hypophysectomized dogs, there were also no plasma ACTH and cortisol responses, whereas in the other four dogs, plasma ACTH and cortisol responses were significantly attenuated. The basal plasma ACTH and cortisol concentrations were significantly lower in the corticotropic nonresponders than in the responders. Plasma AVP responses were completely abolished by hypophysectomy, although water intake by the dogs was normal. Histopathological examinations at 10 wk after hypophysectomy revealed that adrenocortical atrophy was much more pronounced in the corticotropic nonresponders than in the responders. No residual pituitary tissue was found along the ventral hypothalamic diencephalon. However, in all hypophysectomized dogs that were investigated, islets of pituitary cells were found embedded in fibrous tissue in the sella turcica. A significant positive correlation was found between the number of ACTH-immunopositive cells and the ACTH increment in the CAP test at 10 wk after hypophysectomy. It is concluded that 1) stimulation of the anterior pituitary with multiple hypophysiotropic hormones, stimulation of the pars intermedia with a dopamine antagonist, and stimulation of the neurohypophysis with hypertonic saline do not cause side effects that would prohibit routine use, 2) in the routine stimulation of the anterior pituitary and the pars intermedia, blood sampling can be confined to the first 45 min, 3) the ACTH and cortisol responses to hypophysiotropic stimulation are the most sensitive indicators for residual pituitary function after hypophysectomy, 4) small islets of pituitary cells in the sella turcica, containing corticotropic cells, are the most likely source of the attenuated corticotropic response that may occur after hypophysectomy, and 5) residual AVP release from the hypothalamus after hypophysectomy is sufficient to prevent diabetes insipidus, despite the fact that the AVP response to hypertonic saline infusion is completely abolished.     

Chimerism analysis in long-term survivor patients after bone marrow transplantation for severe aplastic anemia

BACKGROUND AND OBJECTIVE: Allogeneic bone marrow transplantation (BMT) is the most common treatment for young patients with severe aplastic anemia (SAA). Late graft failure represents one of the possible unfavorable outcomes in this setting. Mixed chimerism might represent a risk factor for late graft failure. We examined this relationship by studying chimerism in long-term survivor SAA patients after allogeneic BMT. METHODS: We analyzed long-term hematopoietic chimerism in 15 patients who received BMTs for SAA: 9 with an irradiation-based conditioning regimen and 6 with ATG. We used a PCR method targeting VNTR loci. Sensitivity of the technique ranged between 0.5 and 1.5%. RESULTS: All patients conditioned with radiation-based schemes showed complete donor chimerism. Conversely, out of six patients who received cyclophosphamide and ATG as a conditioning regimen, only one of them had late graft failure (day +168). In this patient, durable mixed chimera status was first detected two months after BMT. INTERPRETATION AND CONCLUSIONS: Our results suggest that in long-term survivors of SAA after BMT there is almost always complete donor chimerism in both irradiated and ATG-conditioned recipients. Mixed chimerism might predict graft failure in these patients.     

Theoretical analysis of a morphine withdrawal phenotype in a cultured cell line

We have previously described a delta-opioid receptor-expressing cultured cell line that proliferates in a defined medium and responds to chronic morphine treatment with an inhibition of its rate of proliferation. To help provide an explanation for this behavior, we have used computer simulation of cell cycle kinetics to analyze the observed rates of proliferation of these cells in the presence and absence of morphine, and after withdrawal of morphine treatment. We questioned whether the difference in cell kinetics observed for the cell populations under the different treatments could be due to changes in the length of the cell cycle, withdrawal of cells from the cycle into a quiescent state, or differences in cell renewal. This was investigated by comparing observed cell numbers as a function of time with the results of different computer simulations using different values for these parameters. We found that we can provide a satisfactory explanation of the experimental observations on the basis of changes in a small set of parameters: Untreated cells experience a slowdown of cell proliferation at about the culture density where multiple cell-cell contacts are made and, beginning then, a large fraction are shunted from G1 into a quiescent state. Chronic morphine treatment inhibits proliferation by slowing passage through G1, but the cells remain as sensitive to cell-cell contacts as the untreated cells. After drug withdrawal following a 6 day treatment with morphine, the cells exhibit a large temporary increase in their rate of proliferation compared with control or chronically treated cells but about 48 hours after withdrawal, when cell-cell contacts just begin to be made, the cells return to almost their pre-treatment total cell cycle time and, as before, a large fraction are shunted into a quiescent state. Taken in conjunction with previously published results, the present ones indicate a possible interaction between morphine-induced and insulin-induced nuclear signaling pathways to the nucleus.     

Influence of an oligodendroglial component on the survival of patients with anaplastic astrocytomas: a report of Radiation Therapy Oncology Group 83-02

PURPOSE: Seven percent of patients with high grade gliomas enrolled in RTOG 83-02 had mixed astrocytoma/oligodenroglial elements on central pathology review. It has often been assumed that the most aggressive histologic component of a tumor determines biologic behavior; however in this trial, the survival of patients who had mixed glioblastomas/oligodenrogliomas was significantly longer than that of patients with pure glioblastomas (GBM). We therefore evaluated the effect of an oligodendroglial component on the survival of patients who had anaplastic astrocytomas (AAF) treated in the same trial. METHODS AND MATERIALS: One hundred nine patients who had AAF and 24 patients with mixed AAF/oligodendrogliomas (AAF/OL) were enrolled in a Phase I/II trial of randomized dose-escalation hyperfractioned radiotherapy plus BCNU. AAF/OL patients were older and more likely to have had more aggressive surgery than AAF patients. Other pretreatment characteristics were balanced between groups, as was assigned treatment. RESULTS: The median survival time for AAF was 3.0 years versus 7.3 years for AAF/OL (p = 0.019). In a multivariate analysis, adjusting for extent of surgical resection and age, an oligodendroglial component was an independent prognostic factor for survival. CONCLUSION: The results support the concept that AAFs with an oligodendroglial component have a better prognosis than pure AAF tumors, similar to the effect seen among patients with glioblastoma multiforme tumors. This better survival outcome should be taken into consideration in the design and stratification of future trials. Additionally, in contrast to patients with GBMs, patients who have AAF/OL have the potential for prolonged survival; therefore, late sequelae of treatment (both radiation and chemotherapy) must be weighed more heavily in the benefits to risks analysis.     

Orbital venous anomalies. A long-standing dilemma

Chronic pancreas transplant rejection with enteric exocrine drainage can lead to significant long-term complications. We report a case of a 47-year-old male insulin-dependent diabetic who survived the complications of peripancreatic abscess, enterocutaneous fistula, and arterioenteric fistula related to pancreas transplantation. To avoid these long-term complications, we now recommend elective removal of nonfunctioning, enterically drained pancreas allografts.     

Cerebrospinal fluid levels of alpha-tocopherol (vitamin E) in Parkinson's disease

We compared CSF and serum levels, and the CSF/serum ratio of alpha-tocopherol (vitamin E), measured by HPLC, in 34 patients with Parkinson's disease (PD) and 47 controls. CSF and serum vitamin E levels were correlate. The mean CSF and serum vitamin E levels, and the CSF/serum ratio of PD patients did not differ significantly between the groups. There was no influence of antiparkinsonian therapy on CSF vitamin E levels. CSF vitamin E levels did not correlate with age, age at onset, duration of the disease, scores of the Unified Parkinson Disease Rating Scale of the Hoehn and Yahr staging in the PD group. These results suggest that CSF vitamin E concentrations are unrelated with the risk for PD.     

Endocytosis and recycling of G protein-coupled receptors

Agonist stimulation of G protein-coupled receptors causes a dramatic reorganization of their intracellular distribution. Activation of receptors triggers receptor endocytosis and, since receptors recycle back to the surface continuously, a new steady state is reached where a significant proportion of receptors is located internally. Although this movement of receptors is remarkable, its role has been enigmatic. Recent developments have provided insight into the compartments through which the receptors move, the nature of the signals that trigger receptor translocation, and the significance of receptor cycling for cell function. In this article, Jennifer Koenig and Michael Edwardson review recent progress in this field and place receptor cycling into a mathematical framework that reveals the extent and rate of intracellular receptor movement.     

Reactive oxygen species and the neurodegenerative disorders

Starting at infancy and continuing throughout adult life, huddling is a major component of the behavioral repertoire of Norway rats (Rattus norvegicus). Huddling behavior maintains the cohesion of litters throughout early life, and in adulthood, it remains a consistent feature of social behavior of R. norvegicus. During infancy, rats have severely limited sensorimotor capabilities, and yet they are capable of aggregating and display a form of group regulatory behavior that conserves metabolic effort and augments body temperature regulation. The functions of huddling are generally understood as group adaptations, which are beyond the capabilities of the individual infant rat. We show, however, that huddling as aggregative or cohesive behavior can emerge as a self-organizing process from autonomous individuals following simple sensorimotor rules. In our model, two sets of sensorimotor parameters characterize the topotaxic responses and the dynamics of contact in 7-day-old rats. The first set of parameters are conditional probabilities of activity and inactivity given prior activity or inactivity and the second set are preferences for objects in the infant rat's environment. We found that the behavior of the model and of actual rat pups compare very favorably, demonstrating that the aggregative feature of huddling can emerge from the local sensorimotor interactions of individuals, and that complex group regulatory behaviors in infant rats may also emerge from self-organizing processes. We discuss the model and the underlying approach as a paradigm for investigating the dynamics of social interactions, group behavior, and developmental change.