Morphological changes in the junctional complex of cells in the arachnoid layer of the rat after cold injury

Summary The junctional complexes of cells in the outer arachnoid layer overlying the cerebral cortex of 2-week-old rats were examined with freeze-fracture electron microscopy up to 60 min after transcranial cold injury to the dorsal surface of the brain. Within 30 min after injury, areas of gap and tight junctions with morphological features characteristic of junction formation and/or junction disruption were found scattered among normal junctional complexes in some arachnoid cells. Within 60 min after injury, tight junctions with features typical of less leaky zonulae occludentes were present in all arachnoid cells examined. These morphological features include increases in the number of tight junctional strands and the number of strand-to-strand anatomoses. Gap junctions were interspersed among the tight junctional strands, and many were completely encircled by the strands. The increase in the number and complexity of the tight junctional strands in response to brain injury may be the morphological basis for the maintenance of the cerebrospinal fluid-blood dural barrier.This study was supported by the National Institute of Neurological and Communicative Disorders and Stroke Grant NS20590. The opinions or assertions contained herein are the private ones of the authors and are not to be construed as official or reflecting the views of the DoD or the USUHS. The experiments reported herein were conducted according to the principles set forth in the Guide for Care and Use of Laboratory Animals, Institute of Laboratory Animal Resources, National Research Council, DHEW Pub. No. (NIH) 78-23     

Chronic Obstructive Pulmonary Emphysema—Is Exercise Beneficial?

Following a six-week program of training in a series of exercises, a significant number of patients with chronic obstructive pulmonary emphysema showed decided improvement in functional activity. Subjective improvement also was noted and kept the patient motivation high.Preliminary observations indicated that the improvement could be maintained long after the end of the training period.     

Distribution,causal agents,and infection dynamic of emerging ink disease of sweet chestnut in Southern Switzerland

Emerging diseases caused by both native and exotic pathogens represent a main threat to forest ecosystems worldwide. The two invasive soilborne pathogens Phytophthora cinnamomi and Phytophthora × cambivora are the causal agents of ink disease, which has been threatening Castanea sativa in Europe for several centuries and seems to be re-emerging in recent years. Here, we investigated the distribution, causal agents, and infection dynamics of ink disease in southern Switzerland. A total of 25 outbreaks were identified, 19 with only P. cinnamomi, 5 with only P. × cambivora, and 1 with both species. Dendrochronological analyses showed that the disease emerged in the last 20–30 years. Infected trees either died rapidly within 5–15 years post-infection or showed a prolonged state of general decline until death. Based on a generalized linear model, the local risk of occurrence of ink disease was increased by an S-SE aspect of the chestnut stand, the presence of a pure chestnut stand, management activities, the proximity of roads and buildings, and increasing annual mean temperature and precipitation. The genetic structure of the local P. cinnamomi population suggests independent introductions and local spread of the pathogen.     

Host discrimination byChelonus insularis [Hym.: Braconidae], telenomus heliothidis [Hym.: Scelionidae], andTrichogramma pretiosum [Hym.: Trichogrammatidae]

The ability of female parasitoids (Chelonus insularis Cresson,Telenomus heliothidis Ashmead, andTrichogramma pretiosum Riley) to distinguish between parasitized and unparasitized tobacco budworm,Heliothis virescens (F.), eggs was determined in laboratory studies. All 3 species were relatively efficient at detecting eggs that were previously parasitized by conspecific females.T. heliothidis andT. pretiosum were able to discriminate on the basis of external examination of host eggs, whereasC. insularis appeared to examine hosts internally as well as externally. In interspecific tests, no species readily rejected eggs parasitized by the other 2 species.     

Failure of intracerebral BCG cell wall preparation to prevent glioma induction by avian sarcoma virus in rats

Summary Five-day-old Fischer 344 rats were inoculated intracerebrally with BCG cell walls attached to oil (BCG-CW) or with oil emulsion alone. Doses of BCG-CW of 40 g in 0.01 ml, 200 g in 0.05 ml, and 400 g in 0.1 ml were used, with similar volumes of oil emulsion for comparison. Twentyfive days later hydrocephalus, intracerebral granulomas, and arachnoid granulomas were found at autopsy. The frequency and severity of these abnormalities were related to the presence of BCG-CW in the inoculum and the dose administered. There were minimal abnormalities with 40 g BCG-CW.Two microliters of Avian sarcoma virus (ASV) suspension was inoculated intracerebrally into 5-day-old rats to induce intracerebral gliomas. One hour later 40 g BCG-CW in 0.01 ml, 80 g BCG-CW in 0.02 ml, or similar volumes of oil emulsion alone were inoculated intracerebrally in the region of the virus injection site. BCG-CW or oil emulsion alone failed to prevent induction and growth of the ASV-induced brain tumors. Survival curves of the BCG-CW inoculated animals were similar to that obtained for control animals injected with ASV and otherwise untreated. The oil emulsion decreased survival times compared with control animals.     

Effects of Cortisol and Dexamethasone on Insulin Signalling Pathways in Skeletal Muscle of the Ovine Fetus during Late Gestation

Before birth, glucocorticoids retard growth, although the extent to which this is mediated by changes in insulin signalling pathways in the skeletal muscle of the fetus is unknown. The current study determined the effects of endogenous and synthetic glucocorticoid exposure on insulin signalling proteins in skeletal muscle of fetal sheep during late gestation. Experimental manipulation of fetal plasma glucocorticoid concentration was achieved by fetal cortisol infusion and maternal dexamethasone treatment. Cortisol infusion significantly increased muscle protein levels of Akt2 and phosphorylated Akt at Ser473, and decreased protein levels of phosphorylated forms of mTOR at Ser2448 and S6K at Thr389. Muscle GLUT4 protein expression was significantly higher in fetuses whose mothers were treated with dexamethasone compared to those treated with saline. There were no significant effects of glucocorticoid exposure on muscle protein abundance of IR-β, IGF-1R, PKCζ, Akt1, calpastatin or muscle glycogen content. The present study demonstrated that components of the insulin signalling pathway in skeletal muscle of the ovine fetus are influenced differentially by naturally occurring and synthetic glucocorticoids. These findings may provide a mechanism by which elevated concentrations of endogenous glucocorticoids retard fetal growth.