Utku Goreke, Erdem Kucukal, Fang Wang, Ran An, Nicole Arnold, Erina Quinn, Charlotte Yuan, Allison Bode, Ailis Hill, Yuncheng Man, Bryan C. Hambley, Robert Schilz, Mahazarin Ginwalla, Jane Little, Umut A Gurkan; Membrane bending and sphingomyelinase associated sulfatide dependent hypoxic adhesion of sickle mature erythrocytes. Blood Adv 2023; bloodadvances.2022008392. doi:
Abnormal erythrocyte adhesion due to polymerization of sickle hemoglobin is central to the pathophysiology of sickle cell disease (SCD). Mature erythrocytes constitute >80% of all erythrocytes in SCD, and the relative contributions made by erythrocytes to acute and chronic vasculopathy in SCD are not well understood. Here, we show that the bending stress exerted on the erythrocyte plasma membrane by the sickle hemoglobin polymerization under hypoxia enhances sulfatide-mediated abnormal mature erythrocyte adhesion. We hypothesized that sphingomyelinase activity that is upregulated by accumulated bending energy leads to elevated membrane sulfatide availability and thus hypoxic mature erythrocyte adhesion. We found that mature erythrocyte adhesion to laminin in controlled microfluidic experiments is significantly greater under hypoxia than under normoxia (1856±481 vs. 78±23, mean±SEM), while sickle reticulocyte (early erythrocyte) adhesion, high to begin with, does not change (1281 ±299 vs. 1258±328, mean±SEM). We show that greater mean accumulated bending energy of adhered mature erythrocytes is associated with higher acid SMase activity and increased mature erythrocyte adhesion (p=0.022, for the acid SMase activity and p=0.002 for the increase in mature erythrocyte adhesion with hypoxia, N=5). In addition, hypoxia results in sulfatide exposure on the erythrocyte membrane, and sphingomyelinase increases while anti-sulfatide inhibits the enhanced adhesion of erythrocytes. These results suggest that lipid components of the plasma membrane contribute to the complications in SCD. Therefore, sulfatide and the components of its upregulation pathway, particularly sphingomyelinase should be further explored as potential therapeutic targets to inhibit sickle erythrocyte adhesion.
Five 40-year-old Pinus taeda trees growing in Tochigi, Japan, were used to evaluate juvenile wood (JW) and mature wood (MW) properties and the bending properties of lumber. The boundary between JW and MW existed from the 14th to the 19th ring from pith in the sample trees. There were obvious differences in wood properties between the JW and MW: the MW had higher values in the latewood percentage and basic density and lower values in the microfibril angle. The microfibril angle and the air-dry density were closely related to the bending properties of the JW lumber and the MW lumber, respectively.
In softwoods, it is known that there is a problem with using the juvenile wood as structural lumber and pulp because it has a lower density, shorter cell length, larger microfibril angle (MFA) of the S2 layer, and poor mechanical properties compared with mature wood (Shiokura 1982, Bendtsen and Senft 1986, Clark and Saucier 1989, Zobel and van Buijtenen 1989). It has been shown that the effects of the wood properties, such as the MFA and wood density, on the strength properties differ between juvenile and mature wood. For example, in Japanese cedar (Cryptomeria japonica), Ishiguri et al. (2009) pointed out that the MFA influenced mainly the bending properties of juvenile wood, whereas the air-dry density (AD) influenced mainly the bending properties of mature wood. Matsumura et al. (2012) examined the influence of the lumber positions (center [near the pith], inner, and outer [near the bark]) in large-diameter Japanese cedar logs on variations in the dynamic modulus of elasticity (DMOE) of the lumber. The results showed that the mean values of the DMOE of the lumber obtained from the center, inner, and outer positions were 4.64, 5.44, and 6.48 GPa, respectively. These differences in the DMOE of the lumber are closely related to the existence of juvenile wood. Therefore, it is important to clarify the differences in the wood and the mechanical properties between juvenile and mature wood.
In the present study, the wood properties and bending properties of lumber were investigated in 40-year-old P. taeda trees planted in Tochigi, Japan. The results obtained were used to clarify the differences in the wood properties and bending properties between juvenile wood and mature wood.
The boundary between the juvenile and mature wood was determined according to the method described by Shiokura (1982), in which a logarithmical formula was obtained as a function of the annual ring number from the pith. The ring number in which the increased ratio of the TL becomes less than 1 percent was regarded as the boundary between juvenile and mature wood (Shiokura 1982). Based on these results, the boundary between juvenile and mature wood in five sample trees existed from the 14th to the 19th annual ring from the pith (Fig. 2).
Radial variations in mean values of five sample trees in latewood tracheid length (TL), annual ring width (ARW), and increase ratio (IR) of TL. Circles, triangles, and squares indicate TL, ARW, and IR of TL, respectively. IR of TL was determined according to the method described by Shiokura (1982). Gray color area is transition zone (TZ) from juvenile wood (JW) to mature wood (MW) determined by IR of TL. Dotted line indicates threshold value of annual ring width to classify the JW and MW in lumber.
When the boundary between juvenile wood and mature wood was regarded as the 14th annual ring from pith, significant differences at the 1 percent level were recognized in all of the wood properties investigated in the present study between juvenile and mature wood (Table 2). The LWP in the juvenile wood was almost half of that in the mature wood, while the MFA in the juvenile wood was 1.5 times higher than that in the mature wood. In general, the juvenile wood showed a lower density, shorter TL, larger MFA, and inferior mechanical properties (Zobel and van Buijtenen 1989). These trends were also true for the P. taeda examined in the present study.
In the present study, the boundary between juvenile and mature wood was the 14th to 19th annual ring from the pith. The mean values of the ARW in the 13th ring and after the 14th annual ring from the pith were 5.2 and about 4.0 mm, respectively; thus, the lumber was classified into juvenile and mature wood by using an ARW of 5.0 mm as the threshold value (Fig. 2). The results of this study show significant differences between the juvenile and mature woods in the bending properties of the lumber (Table 3): the mature wood showed higher values in its bending properties than those in the juvenile wood. Our results were similar to those reported for P. taeda by several previous researchers (Pearson and Gilmore 1980, Kretschmann and Bendtsen 1992).
Table 4 shows the correlation coefficients between the wood properties and the bending properties of the lumber. In all of the lumber (n = 82), there were significant correlations (1% level) between the ARW or AD and the bending properties of the lumber (Table 4). However, significant correlations between the ARW and bending properties were found in the juvenile wood, not in the mature wood. In contrast, significant correlations between the AD and DMOE or MOE were recognized in the mature wood but not in the juvenile wood. However, there were significant correlations between the AD and MOR in both the juvenile and the mature wood. In general, the MFA was strongly related to the MOE: the higher the MFA, the lower the MOE (Hirakawa and Fujisawa 1995, Lachenbruch et al. 2010). In the present study, the MFA in the juvenile wood was greater than that in the mature wood (Table 2). One could consider, therefore, that the ARW was not directly related to the bending properties of the lumber but that the MOE may correlate with the MFA. Hirakawa and Fujisawa (1995) reported that the MFA in the juvenile wood of the Japanese cedar varied greatly compared with that of the mature wood. They also reported that, because of the large variation in the MFA, no significant correlation between the density and MOE was found in the juvenile wood. In the mature wood, on the other hand, the MFA did not vary as much compared with the juvenile wood (Table 2). Thus, the smaller variation in the MFA, with a smaller deviation, might lead to a significant correlation between the AD and MOE in the mature wood. Based on these results, it can be concluded that, in P. taeda, the MFA and AD can predict the bending properties of lumber produced from juvenile wood and mature wood, respectively.
The boundary between juvenile and mature wood in five sample trees grown in Tochigi, Japan, existed from the 14th to the 19th annual ring from the pith via the radial variations of the TL, which was similar to those reported by several researchers.
The effects of the wood properties on the bending properties of the lumber differed between the juvenile and mature wood. The MFA and AD affected the bending properties of the lumber in the juvenile and mature wood, respectively.
Tufted perennial 30-60 cm. Spreads by surface rooting stolons. Distinguished from Common couch by longer ligule, lack of auricles and fine leaves. Flower head is a narrow pyramid of cylindrical shape, spreading when in flower but closed up when mature. Spikelets are small, narrow, single flowered and awnless. 781b155fdc