Host-Pathogen Interactions : XXXII. A Fungal Glucan Preparation Protects Nicotianae against Infection by Viruses

A glucan preparation obtained from the mycelial walls of the fungus Phytophthora megasperma f.sp. glycinea and known as an elicitor of phytoalexins in soybean was shown to be a very efficient inducer of resistance against viruses in tobacco. The glucan preparation protected against mechanically transmitted viral infections on the upper and lower leaf surfaces. Whether the glucan preparation was applied by injection, inoculation, or spraying, it protected the plants if applied before, at the same time as, or not later than 8 hours after virus inoculation. At concentrations ranging from 0.1 to 10 micrograms per milliliter, the glucan preparation induced protection ranging from 50 to 100% against both symptom production (necrotic local lesions, necrotic rings, or systemic mosaic) and virus accumulation in all Nicotiana-virus combinations examined. However, no significant protection against some of the same viruses was observed in bean or turnip. The host plants successfully protected included N. tabacum (9 different cultivars), N. sylvestris, N. glutinosa, and N. clevelandii. The viruses belonged to several taxonomic groups including tobacco mosaic virus, alfalfa mosaic virus, and tomato black ring virus. The glucan preparation did not act directly on the virus and did not interfere with virus disassembly; rather, it appeared to induce changes in the host plant that prevented infections from being initiated or recently established infections from enlarging. The induced resistance does not depend on induction of pathogenesis-related proteins, the phenylpropanoid pathway, lignin-like substances, or callose-like materials. We believe the induced resistance results from a mechanism that has yet to be described.

Electrodermally differentiated subgroups of anxiety patients and controls. II: Relationships with auditory, somatosensory and pain thresholds, agoraphobic fear, depression and cerebral laterality

Patients diagnosed (DSM III) with anxiety disorders (agoraphobia, panic syndrome, generalised anxiety syndrome) were classified along with controls as electrodermally stabile or labile on the basis of non-specific electrodermal activity and rate of habituation to tones. While patients showed more evidence of psychopathology than controls on scales of anxiety, neuroticism, depression and agoraphobic fear, patient labiles scored higher than stabiles on agoraphobic fear and were differentiated by higher scores of Beck depression. They were also more sensitive to pain, whereas patient stabiles were less sensitive at absolute somatosensory threshold. Amongst controls agoraphobic fear was associated with lability and stabiles scored higher on autonomy in locus of control. Lateral asymmetries in auditory thresholds were consistent with reciprocal hemispheric influences on electrodermal reactivity and habituation, modifiable by anxiety. Interrelationships between fear, depression, sensitivity to somatosensory stimulation, pain, and superior vigilance performance in patient labiles were consistent with elevated right hemisphere function.

Influence of parenteral fat administration on the pulmonary vascular system in man

In 16 patients with multiple injuries the effect of parenteral administration of a fat emulsion on the pulmonary vascular system has been studied. Using the Hewlett Packard 5600 A Intensive Care System, which allows vital parameters to be sampled at a rate of two values per min, pulmonary artery pressure (PAP) was monitored before, during, and after the administration of Lipofundin S 20% (0.24 g/kg/h). In addition right ventricular stroke work index (RVSWI), alveolar-arterial oxygen difference (A-aDO2) and pulmonary shunt (Qs/Qt) were calculated. The results indicate that there are no changes of the PAP, the RVSWI, and the A-aDO2 during the period of observation.

Plant disease and the regulation of enzymes involved in lignification : Effects of osmotic pressure on phenylpropanoid enzymes and on the hypersensitive response of tobacco to tobacco mosaic virus

Tobacco varieties carrying the N gene from Nicotiana glutinosa respond to infection by Tobacco Mosaic Virus (TMV) by forming necrotic local lesions (hypersensitive reaction), thereby localizing the infection. In this study, infected mesophyll leaf tissue of N. tabacum Samsun NN was treated with the non-permeating, non-metabolizable carbohydrate mannitol. The local lesions developed under iso-osmotic conditions (0.28 M mannitol), though with a slight delay and with a reduced rate of growth, as compared to those on attached leaves. At increasing plasmolysing concentrations of mannitol, necrotization was progressively inhibited, but not completely suppressed. The leaf tissue produced tiny translucent zones, with a delay that increased between the virus inoculation and application of the plasmolytica. Activities of phenylalanine ammonia-lyase (PAL, EC 4.3.1.5) and O-methyltransferase (OMT, EC 2.1.1.6) are strongly stimulated in hypersensitively reacting tobacco and were used as biochemical markers in the present study. This study was done to determine whether the inhibitory effect of plasmolysis on the elicitation of the hypersensitive response is due to a decrease in virus spread, resulting from the rupture of plasmodesmata or, at least in part, to metabolic alterations of the host cell exposed to osmotic stress. Since necrotization is normally preceded by intense virus multiplication, the inhibitory effects found for early applications (i.e., before local lesion appearance) of plasmolytica could easily be related to an inhibition of virus spread which also occurred in similarly treated leaf tissue of the systemically reacting variety Samsun. The most meaningful data were obtained from mannitol treatments performed on leaf tissue already carrying local lesions, i.e., in which the elicitor(s) and/or the factor(s) of necrotization were already operating. Under iso-osmotic conditions, we found the stimulated PAL and OMT activities characteristic of the hypersensitive response. At plasmolysing concentrations of mannitol, we observed the counteracting effects of two different mechanisms controlling the phenylpropanoid enzymes. Floating the leaf material on the liquid medium induced an ageing-like effect with a continuous increase in enzyme activities that was independent on osmotic pressure and sensitive to cycloheximide. At the same time, the stimulated enzyme activities related to hypersensitivity decreased at a rate related to osmotic pressure. Since PAL and OMT of tobacco leaves are long-lived enzymes, it is likely that the increased de novo synthesis of the enzymes was suppressed by plasmolysis while their degradation and/or inactivation was maintained or even increased. From these results it is concluded that the apparent inhibition of the hypersensitive response by plasmolysis is due to both a decrease in virus spead (artificially caused by the rupture of connections between cells) and to drastic metabolic alterations of the host cell exposed to high osmotic pressure.

[Cinnamic acid 4-hydroxylase and 0-methyltransferase activities in leaves of hypersensitive tobacco plants infected by tobacco mosaic virus]

Tobacco leaves of Nicotiana tabacum L., variety Samsun NN, show a low cinnamic acid-4-hydroxylase activity and a rather high O-methyltransferase activity. Caffeic acid, the substrate of the latter enzyme, is methylated specifically in the meta position. In TMV-infected leaves a strong increase in the activities of phenylalanine ammonia-lyase and of these two enzymes occurs at the time of appearance and development of the necrotic reaction.

Arguments against long-term conservative treatment of oesophageal strictures due to corrosive burns

Thirty-two patients are presented with late complications after a corrosive burn of the oesophagus. From this group of 32 cases 11 had fistulae and mediastinal abscesses after perforation of the gullet; 11 patients developed a tight peptic stricture in the narrowed oesophagus due to traction-type hiatal hernia as a result of the longitudinal contraction of the fibrotic oesophagus; cancer developed in the corrosive stricture in 10 patients, inoperable in five.

Arguments against long-term conservative treatment of narrowed and fibrotic oesophageal strictures are presented. Early operation gives final relief from dysphagia and prevents late complications. The risk of intrathoracic oesophageal replacement with a segment of bowel/colon or jejunum in uncomplicated cases is 2·4% in our series of 42 cases.