Nursing in foreign countries as described in the professional journals of national nurses' associations

This paper discusses the extent of the coverage accorded by national nurses' association journals to the important subject of nursing in other countries. With one exception, the journals sampled showed that dissemination of such information is diminishing. What are the reasons for this?     

Glycine site of the excitatory amino acid N-methyl-D-aspartate receptor in neonatal and adult brain.

The N-methyl-D-aspartate (NMDA) receptor complex in brain is a glutamate receptor subtype with several recognition sites including a glycine site that is able to modulate and activate allosterically the receptor. This receptor may be important in the regulation of developmental synaptic plasticity. The release of glutamate and consequent overstimulation of NMDA receptors that follows hypoxia-ischaemia leads to brain damage. Brain tissue obtained at necropsy was studied in a total of 16 term infants aged less than 1 week to 22 weeks and in four adults aged from 66 to 84 years. Glycine sites were determined in brain sections by the binding of the selective ligand [3H]5,7-dichloro-kynurenic acid and measured by autoradiography. In infant brains the amount of binding to the glycine site was higher in temporal cortex and hippocampus than in basal ganglia and was also higher than in comparable areas of adult brain. The amount of glycine site binding in infant cortex increased with postnatal age. The data suggest that infant brain acquires a relatively high density of NMDA receptors in temporal lobe due to postnatal proliferation of glutamatergic synapses. These findings have therapeutic implications as drugs that reduce NMDA receptor function by blocking the glycine modulatory site would be pertinent to preventing brain damage after hypoxia-ischaemia.     

Fates of visual cortical neurons in the ferret after isochronic and heterochronic transplantation

In the mammalian cerebral cortex, neurons in a given layer are generated at about the same time in development. These cells also tend to share similar sets of morphological and physiological properties and have projection patterns characteristic of that layer. This correspondence between the birthday and eventual fate of a cortical neuron suggests the possibility that the commitment of a cell to a particular laminar position and set of connections may occur very early on in cortical development. The experiments described here constitute an attempt to manipulate the fates of newly generated cortical neurons upon transplantation. The first set of experiments addressed the normal development of neurons in the primary visual cortex (area 17) of the ferret. Injections of 3H-thymidine into newborn ferrets showed that neurons generated after birth are destined to sit in layer 2/3 of the cortex, whereas neurons born on embryonic day (E) 32 populate primarily layers 5 and 6. Many layer 2/3 neurons in adult ferrets could be retrogradely labeled with HRP from visual cortical areas 18 and 19, while about half of the neurons in layer 6 were found to project to the lateral geniculate nucleus (LGN). In the second set of experiments, presumptive layer 2/3 cells were labeled in vivo by injecting ferrets with 3H-thymidine on P1 and P2. Before the cells had a chance to migrate, they were removed from the donor brain, incubated in a fluorescent dye (DAPI or fast blue), and dissociated into a single-cell suspension. The labeled cells were then transplanted into the proliferative zone of a littermate host ferret ("isochronic" transplants). Over the next few weeks, many of these dye-labeled cells underwent changes in their position and morphology that were consistent with a radially directed migration and subsequent differentiation into cortical neurons. The final positions of isochronically transplanted neurons in the host brain were mapped out by using the 3H-thymidine marker after long survival periods. About 97% of radioactively labeled cells had migrated out into the visual cortex, where they attained a compact laminar distribution: 99% were found in layer 2/3, their normal destination. The labeled cells had normal, mostly pyramidal neuronal morphologies and appeared to be well integrated with host neurons when viewed in Nissl-stained sections. Ten isochronically transplanted neurons were successfully labeled after HRP injection into 2 normal target regions, areas 18 and 19.(ABSTRACT TRUNCATED AT 400 WORDS)     

Pathological, immunocytochemical and microbiological findings in calf pneumonias associated with Haemophilus somnus infection

Pathological, immunocytochemical and microbiological findings in 32 cases of calf pneumonia associated with Haemophilus somnus infection are described. The majority of cases were "found dead" or died after a sudden onset pneumonia of less than 24 h duration. Lesions of exudative bronchopneumonia were present and the cases could be divided into two main groups on the basis of histopathological and immunocytochemical features. In group A, cases were dominated by necrotizing bronchiolitis, degeneration and necrosis of airway and alveolar exudates, severe alveolitis with accumulations of degenerate basophilic cells, interstitial inflammatory changes and the widespread distribution of H. somnus antigen in airways and alveoli. In Group B, necrotizing and degenerative changes were much less extensive and less severe and the overall appearance was of suppurative bronchopneumonia with H. somnus antigen much less widespread within the lungs. Alveolar oedema, hyaline membrane formation and alveolar epithelial hyperplasia were present in caudodorsal lung areas of several calves. No major differences were seen between the histopathology of lungs where H. somnus was the sole isolate and that of lungs where H. somnus was isolated along with other bacterial pathogens.     

Influence of environmental temperature on exercise-induced inspiratory muscle fatigue

Exercise in the heat has detrimental effects on circulation that might negatively influence endurance performance. If blood is diverted away from the inspiratory muscles to the skin during exercise in the heat, exercise-induced inspiratory muscle fatigue might be exacerbated. Thus, we hypothesised that prolonged heavy endurance exercise in the heat would impair exercise performance and exacerbate inspiratory muscle fatigue compared to exercise in a thermo-neutral environment. Using a crossover design, seven male endurance trained subjects [mean (SEM) maximum oxygen uptake = 62.2 (1.5) ml·kg^–1·min^–1] were assigned at random to either a group that exercised in the heat at an ambient temperature of 35°C (H) or a group that exercised in the cool at 15°C (C). Maximum inspiratory mouth pressure at zero flow (P ₀), pressure normalised maximum relaxation rate (MRR/P ₀), time constant for the pressure decay (), and maximum inspiratory flow at 30% P ₀ ( ₃₀) were assessed immediately before and reassessed within 2, 30, and 60 min of completing a pre-loaded time trial [40 min at 65% peak power, plus ~30 min time trial] on a cycle ergometer . Group H completed the time trial 432 (135) s slower than group C [2,285 (180) vs 1,852 (122) s, respectively; =24 (8)%, P=0.0094]. Repeat measurements within 2 min post-exercise revealed significant declines in P ₀, MRR/P ₀, , and ₃₀ from baseline values, but no between-group differences were observed. In conclusion, heavy sustained exercise in the heat impaired subsequent time-trial performance but did not exacerbate inspiratory muscle fatigue in endurance-trained subjects.     

CD40 ligand-independent B cell activation revealed by CD40 ligand-deficient T cell clones: evidence for distinct activation requirements for antibody formation and B cell proliferation

We report the capacity of CD40 ligand (CD40L)-negative T cell clones to activate human B cells. CD40L-negative T cells induce a level of B cell proliferation 10–20% of that seen with normal T cells. The signal provided by the negative clones is synergistic with that derived from a CD40L transfectant, and restores B cell proliferation to normal levels, showing that CD40L-negative T cell clones are not inherently inhibitory for B cells. Although their capacity to induce proliferation was much reduced, CD40L-negative T cell clones were still strong inducers of B cell differentiation to plasma cells. This differentiation to plasma cells was inhibited by a CD40L transfectant. The data are discussed with regard to the normal in vivo mechanism for maintaining B cell memory and memory antibody responses to T-dependent antigens.     

Increased susceptibility to bacterial infection as a sequela of exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin.

The effects of subclinical levels of 2,3,7,8-tetrachloridibenzo-p-dioxin (TCDD) on the response of mice to infection with either Salmonella bern or Herpesvirus suis, also known as pseudorabies virus, are reported. TCDD is a contaminant of certain commercially useful chemicals, such as chlorinated phenols or herbicides. It has been shown to cause thymic atrophy and to suppress cell-mediated immunity in laboratory animals. Sublethal levels of TCDD were used: 0.5, 1,5, 10, or 20 mug/kg, given through a gastric tube once weekly for 4 weeks. A significant decrease in weight gain compared with control mice occurred at the 20-mug dosage. Dose schedules of 1 mug or more, followed by salmonella infection, resulted in significant increases in mortality and decreases in the time from infection to dealth. However, TCDD had no significant effect on mortality in the pseudorabies-infected mice. The most important finding in this study is that extremely low levels of TCDD, which do not produce clinical or pathological change, still have the capacity to affect host defense.     

Architecture of secondary lymphoid tissue in sheep experimentally challenged with scrapie

Scrapie is a transmissible spongiform encephalopathy in which there is an accumulation of the abnormal form of the prion protein, PrPsc, in the lymphoreticular system and nervous system. There is a particular accumulation of PrPsc on follicular dendritic cells within the germinal centre of B-cell follicles. Because accumulation of PrPsc in the nervous system leads to neuronal cell loss we have examined PrPsc accumulation in the prescapular and mesenteric lymph nodes in relation to lymph node architecture of scrapie-challenged sheep. We demonstrate that an accumulation of PrPsc in the lymph node fails to result in gross defects in the microanatomy and phenotype of T- and B-cell areas in the lymph nodes.     

IL-2-like activity in lymph fluid following in vivo antigen challenge.

The majority of studies that characterize lymphokines utilize in vitro activation of lymphocytes. In an attempt to identify and characterize lymphokines released from tissue sites, we have cannulated sheep lymphatic vessels and collected lymph that drains a site of in vivo antigen challenge. Lymph draining directly from a site of intradermal antigen challenge (afferent lymph) and lymph draining an antigen-stimulated lymph node (efferent lymph) were assayed for lymphokine activity by the ability of cell-free lymph fluid to stimulate the proliferation of sheep Con A-blasts. Afferent and efferent lymph, both collected at 24 and 48 hr following in vivo antigen challenge, with either ovalbumin or PPD in primed animals, stimulates the proliferation of sheep Con A-blast cells. This in vivo-derived lymphokine activity and in vitro-generated sheep Con A supernatant has an active component with properties similar to interleukin-2 (IL-2) that has been described in several other species. The IL-2-like material is precipitated by 40-80% ammonium sulphate saturation, has a molecular weight (MW) of 20,000 MW as judged by gel filtration chromatography, and is eluted from an anion-exchange HPLC column with 125 mM NaCl. HPLC ion-exchange fractionation of the 20,000 MW material from lymph fluid shows differences between afferent and efferent lymph material. The fractionation of afferent material is similar to that of in vitro generated Con A supernatant material with a single peak of activity eluted by 125 mM NaCl. In contrast, the 20,000 MW material from efferent lymph elutes with peaks of activity at 125 and 300 mM NaCl.