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Biomedical subjects

W Dobrowolski

Publications and source records attributed to W Dobrowolski.

At least 19 recordsLinked to original sources
PubMed2005

California black oak response to nitrogen amendment at a high O3, nitrogen-saturated site.

In a nitrogen (N) saturated forest downwind from Los Angeles, California, the cumulative response to long-term background-N and N-amendment on black oak (Quercus kelloggii) was described in a below-average and average precipitation year. Monthly measurements of leaf and branch growth, gas exchange, and canopy health attributes were conducted. The effects of both pollutant exposure and drought stress were complex due to whole tree and leaf level responses, and shade versus full sun leaf responses. N-amended trees had lower late summer carbon (C) gain and greater foliar chlorosis in the drought year. Leaf water use efficiency was lower in N-amended trees in midsummer of the average precipitation year, and there was evidence of poor stomatal control in full sun. In shade, N-amendment enhanced stomatal control. Small differences in instantaneous C uptake in full sun, lower foliar respiration, and greater C gain in low light contributed to the greater aboveground growth observed.

Acclimatization↗
PubMed2004

Stomata open at night in pole-sized and mature ponderosa pine: implications for O3 exposure metrics.

Ponderosa pine (Pinus ponderosa Dougl. ex Laws.) is widely distributed in the western USA. We report the lack of stomatal closure at night in early summer for ponderosa pine at two of three sites investigated. Trees at a third site with lower nitrogen dioxide and nitric acid exposure, but greater drought stress, had slightly open stomata at night in early summer but closed stomata at night for the rest of the summer. The three sites had similar background ozone exposure during the summer of measurement (2001). Nighttime stomatal conductance (gs) ranged from one tenth to one fifth that of maximum daytime values. In general, pole-sized trees (< 40 years old) had greater nighttime gs than mature trees (> 250 years old). In late summer, nighttime gs was low (< 3.0 mmol H2O m(-2) s(-1)) for both tree size classes at all sites. Measurable nighttime gs has also been reported in other conifers, but the values we observed were higher. In June, nighttime ozone (O3) uptake accounted for 9, 5 and 3% of the total daily O3 uptake of pole-sized trees from west to east across the San Bernardino Mountains. In late summer, O3 uptake at night was < 2% of diel uptake at all sites. Nocturnal O3 uptake may contribute to greater oxidant injury development, especially in pole-sized trees in early summer.

Ozone↗
PubMed1986

[Causes of lamb losses with special reference to listeriosis on a large-scale farm].

Epizootiological studies on lamb losses on a large scale farm (4.5 thousand mothers) were carried out. The results of the studies denied the direct effect of maize silage on the genesis of enzootia of listeriosis. The earlier reports were confirmed, i.e. that the direct cause of enzootia of listeriosis is the weakening of an animal organism due to other microbiological, zoohigienical, nutritional factors (e.g. not proper content of mineral compounds). Maize silage has a destructive effect on the health of lambs as well as other fodders with unsuitable biochemical composition. The results of the studies were prepared in Basic language using Hellwig's method "Determination of the maximum capacity of data carrier", to enable the automation of statistical data. Verification of the above mentioned method was done on the basis of the results of the studies performed on a sheep farm. Essential influence of the content of magnesium and iron as well as statistically known interdependencies between the indices studied were revealed and confirmed. "Listing" of the programme; data and result printout, to be used widely, was enclosed.

Animal Feed↗
PubMed1975

Plasma levels of LH and prolactin in cows following enucleation of the persistent corpus luteum.

LH and prolactin were measured in plasma of 5 cows before and after enucleation of the persistent corpus luteum. Two cows returned to normal oestrous cycles following enucleation and did not differ from normal, cycling cows, with respect to hormone levels. Three other ones developed follicular cysts following enucleation and had decreased levels of LH and prolaction as compared with cycling cows. On the day of enucleation the fluctuations in LH-levels were higher than either before or after enucleation.

Animals↗