Mechanism of occupational asthma due to Western red cedar (Thuja plicata)

1994 ◽  
Vol 25 (1) ◽  
pp. 13-18 ◽  
Author(s):  
Moira Chan-Yeung
2017 ◽  
Vol 11 (1) ◽  
pp. 79-81
Author(s):  
Kole F. Adelalu ◽  
Xiao-Jian Qu ◽  
Yan-Xia Sun ◽  
Tao Deng ◽  
Hang Sun ◽  
...  

IAWA Journal ◽  
2002 ◽  
Vol 23 (2) ◽  
pp. 201-211 ◽  
Author(s):  
Simon Ellis ◽  
Paul Steiner

Five wood species, Oregon ash (Fraxinus latifolia Benth.), Balau (Shorea spp.), Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), Western red cedar (Thuja plicata Donn ex D. Don), and Trembling aspen (Populus tremuloides Michx.) were loaded in compression longitudinally, radially and tangentially. The wood cubes were conditioned to one of four moisture contents prior to loading. Small cubes were loaded until no void space remained after which samples were released and soaked in water. Stress /strain curves were recorded over the whole range of strain and cube thicknesses were recorded at the end of the compression, after release from the testing apparatus, and after soaking in water. Denser woods resulted in a greater Young’s modulus, higher levels of stress and shorter time to densification than did less dense woods. Higher initial moisture contents apparently increased the plasticity of the wood leading to a lower Young’s modulus and lower levels of stress during compression, greater springback after release of stress and greater recovery after swelling in water. Differences observed in the radial and tangential behaviours were believed to be due to the supporting action of the rays when the wood was compressed in the radial direction in balau and trembling aspen and to the relative difference between the lower density earlywood and higher density latewood regions in ash, Douglas-fir and western red cedar.


Botany ◽  
2020 ◽  
Vol 98 (7) ◽  
pp. 353-359
Author(s):  
Kermit Ritland ◽  
Allyson Miscampbell ◽  
Annette Van Niejenhuis ◽  
Patti Brown ◽  
John Russell

We used microsatellite genetic markers to evaluate the mating system of western red cedar (Thuja plicata Donn ex D. Don) under various seed orchard pollen management schemes. We primarily examined whether supplemental mass pollination (SMP) can reduce the observed selfing rates. Pollen blowing and “hooding” were also examined in smaller tests. Only SMP was consistently effective in reducing the selfing rate, from 30% to 20%. The correlation of paternity was quite high (60%–90%) in two of three orchards, and in these two orchards the application of SMP reduced this correlation by about 10% as well. The correlation of paternity is the fraction of full-sibling vs. half-sibling progeny, and unbiased estimates can be obtained with few loci, even single loci, in contrast to other types of paternity analysis. We also find the microsatellite amplicon sizes should be pooled into “bins” of 2–4 nucleotides, owing to unintended errors of assay; otherwise the estimates are biased. This new feature of mating system estimation was incorporated into the computer program MLTR.


1992 ◽  
Vol 7 (2) ◽  
pp. 48-50 ◽  
Author(s):  
Nicholas J. Smith ◽  
Alan McLeod

Abstract Edible biomass estimating regression equations were developed for red huckleberry (Vaccinium parvifolium), understory western red-cedar (Thuja plicata) and deer fern (Blechnum spicant) growing in potential second-growth Columbian black-tailed deer (Odocoileus hemionus columbianus) winter range on Vancouver Island, B.C. Vertical edible biomass height profile equations were also developed for red huckleberry and western red-cedar. These models may be used to objectively and conveniently help assess the amount of forage available to deer during severe winters. West. J. Appl. For. 7(2):48-50.


1981 ◽  
Vol 1 (1) ◽  
pp. 41-51 ◽  
Author(s):  
A.D. Blainey ◽  
V.A.L. Graham ◽  
M.J. Phillips ◽  
R.J. Davies

1 Asthma due to western red cedar (Thuja plicata) is well recognized, but has not been described frequently in the UK. Two patients who developed asthma and rhinitis due to occupational contact with western red cedar were studied. Both patients developed late asthmatic responses following bronchial challenge with western red cedar. 2 The challenge technique and the results of comparison between different wood dusts and dust extract are described. 3 The technique of anterior rhinometry was used to follow the nasal response to challenge in one patient, and demonstrated a late nasal reaction which followed a similar time course to the bronchial response.


1958 ◽  
Vol 36 (12) ◽  
pp. 1612-1615 ◽  
Author(s):  
J. A. F. Gardner ◽  
G. M. Barton

The steam-volatile oil of western red cedar contains traces of a fifth tropolone, β-dolabrin (4-isopropenyltropolone), in addition to α-, β-, and γ-thujaplicin and 7-hydroxy-4-isopropyltropolone. The presence of β-dolabrin, previously obtained from Japanese "Hiba" wood by Nozoe, was detected by paper chromatography and proved by isolation of a sample from the steam-volatile oil by a combination of sodium salt precipitation, fractional crystallization, and preparative paper chromatography. The approximate composition of the steam-volatile oil from butt heartwood is given.


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