This study elucidated O 2 dynamics in shoots and roots of submerged Halosarcia pergranulata (Salicornioideae), a perennial halophytic stem succulent that grows on floodprone mudflats of salt lakes. Oxygen within shoots and roots was measured using microelectrodes, for plants when waterlogged or completely submerged, with shoots in light or in darkness, in a controlled environment. Net photosynthesis ( P N ) when underwater, at a range of dissolved CO 2 concentrations, was measured by monitoring O 2 production rates by excised stems. The bulky nature and apparently low volume of gas-filled spaces of the succulent stems resulted in relatively high radial resistance to gas diffusion. At ambient CO 2 , quasi-steady state rates of P N by excised succulent stems were estimated to be close to zero; nevertheless, in intact plants, underwater photosynthesis provided O 2 to tissues and led to radial O 2 loss (ROL) from the roots, at least during the first several hours (the time period measured) after submergence or when light periods followed darkness. The influence of light on tissue O 2 dynamics was confirmed in an experiment on a submerged plant in a salt lake in south-western Australia. In the late afternoon, partial pressure of O 2 (pO 2 ) in the succulent stem was 23.2 kPa (i.e. ~ 10% above that in the air), while in the roots, it was 6.2-9.8 kPa. Upon sunset, the pO 2 in the succulent stems declined within 1 h to below detection, but then showed some fluctuations with the pO 2 increasing to at most 2.5 kPa during the night. At night, pO 2 in the roots remained higher than in the succulent stems, especially for a root with the basal portion in the floodwater. At sunrise, the pO 2 increased in the succulent stems within minutes. In the roots, changes in the pO 2 lagged behind those in the succulent stems. In summary, photosynthesis in stems of submerged plants increased the pO 2 in the shoots and roots so that tissues experience diurnal changes in the pO 2 , but O 2 from the H 2 O column also entered submerged plants.

Inheritance and allergen exposure are key factors in the development and the course of atopic allergy, expressed as conjunctivitis, rhinitis, asthma or dermatitis. This study concerns the clinical significance of mite and mite-allergen avoidance measures based on intensive cleaning with acaricide (solidified benzylbenzoate) added (10 dwellings), and without biocidal activity (10 other homes) as a control in a double-blind trial with matched pairs. Twenty subjects with persisting rhinitic complaints were selected. They lived in 20 different dwellings and were all sensitized to pyroglyphid mites; 12 of them were also sensitized to stored product mites (Acari). Daily symptoms and medication score, guanine and dust exposure, total and mite-specific IgE in serum, eosinophilia in the blood and in the nasal smear, intracutaneous tests with house dust mite and storage mite extracts were compared in both pairs and groups. Acarological data, physiochemical aspects and exposure assessment are discussed in detail elsewhere. Symptom scores dropped significantly, as did the total IgE and exposure to dust and mite products in the acaricidal cleaner treatment group. After 1 year, the daily symptoms median was 47% (P = 0.025), total IgE was 38% (P = 0.0049), and exposure to dust and mite products (guanine exposure) was 53% (P = 0.0449) better or lower than in the controls. Intensive cleaning, without acaricidal treatment performed twice a year, resulted in clinical improvement in four out of 10 subjects, of whom none became free of complaints. In the Acarosan treatment group (cleaning + benzylbenzoate) eight out of 10 subjects improved, in three cases subjective symptoms disappeared.(ABSTRACT TRUNCATED AT 250 WORDS)

Individualisation of pacing configuration for biventricular pacing leads to further haemodynamic improvement in patients with heart failure and reduces the number of patients not responding to this therapy.

collateral flow from the basilar to the carotid territory is often hampered by non-functioning posterior communicating arteries. A non-functioning anterior communicating artery is rare. A complete collateral circulation provides better perfusion of the MCA during carotid occlusion as compared with collateral supply through only the anterior or the posterior communicating artery in the case of an incomplete circle of Willis.