Veterinary physiology and community development: are they compatible in a new South Africa?

One of the most complex and troubling issues facing society and health care professionals is physician-assisted suicide (PAS). The convergence of significant trends in legislation, judicial decisions, research, and public sentiment has highlighted its importance. A broad spectrum of societal opinion and philosophical, religious, legal, and professional debate surrounds PAS.     

Apoptosis of late-stage erythroblasts in megaloblastic anemia: association with DNA damage and macrocyte production

An in vitro model of folate-deficient erythropoiesis has been developed using proerythroblasts isolated from the spleens of Friend virus-infected mice fed an amino acid-based, folate-free diet. Control proerythroblasts were obtained from Friend virus-infected mice fed the same diet plus 2 mg folic acid/kg diet. Our previous studies showed that, after 20 to 32 hours of culture in folate-deficient medium with 4 U/mL of erythropoietin, the folate-deficient proerythroblasts underwent apoptosis, whereas control erythroblasts survived and differentiated into reticulocytes over a period of 48 hours. The addition of folic acid or thymidine to the folate-deficient medium prevented the apoptosis of the folate-deficient erythroblasts, thereby implicating decreased thymidylate synthesis as the main cause of apoptosis in the folate-deficient erythroblasts. In the study reported here, we examined intracellular folate levels, uracil misincorporation into DNA, p53 and p21 proteins, and reticulocyte formation in erythroblasts cultured in folate-deficient or control medium. In all experiments, the folate-deficient erythroblasts cultured in folate-deficient medium gave results that varied significantly from folate-deficient erythroblasts cultured in control medium or control erythroblasts cultured in either folate-deficient or control media. Folate-deficient erythroblasts cultured in folate-deficient medium had marked decreases in all coenzyme forms of folate that persisted throughout culture, increased uracil misincorporation into DNA, persistent accumulations of p53 and p21, and decreased reticulocyte production but increased size of individual reticulocytes. A model of folate-deficient erythropoiesis based on apoptosis of late stage erythroblasts is presented. This model provides explanations for the clinical findings in megaloblastic anemia.     

Introduction to the AFDC program. Aid to Families with Dependent Children

The NADYA Group, integrated in the Spanish Society of Parenteral and Enteral Nutrition (SENPE), and made up of professionals dedicated to Artificial Nutrition, and specifically, to Artificial Nutrition in the home, annually undertakes the task of collecting data on diagnosis, type of support, follow up characteristics, complications, and quality of life, of patients included in programs of at home artificial nutrition in Spain. In the Annual Register corresponding to 1994, 17 hospitality groups have participated, providing 369 patients with Home Enteral Nutrition, and 30 with Home Parenteral Nutrition. Home Enteral Nutrition is mainly applied in patients with neoplasias (36%) or neurological alterations (35%). The most commonly used access route in the nasogastric tube, although there is an observed increase in the application of Percutaneous Gastrostomies (21%) in relation to previous data of the Spanish population. There is an observed complications index of 0.07 episodes/patient-year, a mortality of 30% (neoplasias) and 20% (neurological alterations), and low rehabilitation indexes in this group. In Home Parenteral Nutrition, post-radiation enteritis, neoplasias, and mesenteric ischemia, are the main diagnostic groups. The majority of the patients have a tunneled tube (63%), with 37% using an implanted tube. With an index of hospitalizations of 0.83 hospitalizations/ patient-year, catheter septicemia justifies the majority of the re-hospitalizations derived from nutritional treatment (0.56 hospitalizations/patient-year), note the mortality of 37%. There are complete rehabilitations, continuing the previously normal activity in 80% of the cases.     

Assessing the contribution of free hydroxyl radical in organic matter-sensitized photohydroxylation reactions

Photochemical formation of reactive oxygen species from dissolved organic matter (DOM) is incompletely understood, especially in the case of hydroxyl radical (?OH) production. Many studies have used various probes to detect photochemically produced ?OH from DOM, but the fundamental reactions of these probes are not necessarily specific for free ?OH and may also detect lower-energy hydroxylation agents. In this study, two tests were applied that have previously been used as a diagnostic for the presence of free ?OH: methane quenching of ?OH and hydroxybenzoic acid (hBZA) product yields. Upon application of these two tests to a set of five DOM isolates, it was found that methane quenching and the hBZA ratio results were not necessarily consistent. Overall, the results provide compelling evidence that all isolates studied photochemically produce free ?OH. The hydroxylating acitivity of Elliot Soil Humic Acid and Pony Lake Fulvic Acid, however, also had a significant contribution from a photochemically generated hydroxylating agent that is lower in energy than free ?OH. Catalase quenching experiments were conducted to assess whether hydrogen peroxide was the immediate precursor to hydroxyl in these systems. In all cases, catalase addition slowed photohydroxylation of terephthalate, but the contribution of hydrogen peroxide photolysis was determined to be less than 50%.     

Exposure to nitrogen dioxide (NO2) and respiratory disease risk

Epidemiological evidence suggests that exposure to nitrogen dioxide (NO2) through the use of unvented gas cookers in homes is associated with respiratory symptoms. Toxicological evidence, mainly in animal models, suggests that NO2 may increase the susceptibility to infection by viruses and bacteria. This review examines the evidence and proposes mechanisms whereby such exposure may occur, in particular how NO2 may aggravate respiratory symptoms in the presence of coexistent infection.     

Activation of the genetically defined m1 muscarinic receptor potentiates N-methyl-D-aspartate (NMDA) receptor currents in hippocampal pyramidal cells

Evidence suggests that cholinergic input to the hippocampus plays an important role in learning and memory and that degeneration of cholinergic terminals in the hippocampus may contribute to the memory loss associated with Alzheimer's disease. One of the more prominent effects of cholinergic agonists on hippocampal physiology is the potentiation of N-methyl-D-aspartate (NMDA)-receptor currents by muscarinic agonists. Here, we employ traditional pharmacological reagents as well as m1-toxin, an m1 antagonist with unprecedented selectivity, to demonstrate that this potentiation of NMDA-receptor currents in hippocampal CA1 pyramidal cells is mediated by the genetically defined m1 muscarinic receptor. Furthermore, we demonstrate the colocalization of the m1 muscarinic receptor and the NR1a NMDA receptor subunit at the electron microscopic level, indicating a spatial relationship that would allow for physiological interactions between these two receptors. This work demonstrates that the m1-muscarinic receptor gene product modulates excitatory synaptic transmission, and it has important implications in the study of learning and memory as well as the design of drugs to treat neurodegenerative diseases such as Alzheimer's.