[Comparison of ultrasound and nerve stimulation techniques for brachial plexus block for regional hemodynamic changes of upper extremity].

OBJECTIVE: To compare ultrasound guidance versus nerve stimulator guidance supraclavicular brachial plexus block for regional hemodynamic changes of upper extremity. METHODS: Sixty ASA I-II patients scheduled for upper extremity operation were randomly assigned to receive a supraclavicular brachial plexus block guided by either ultrasound (U group, n = 30) or nerve stimulation (N group, n = 30).20 ml mixture of equal volumes of 2% lidocaine and 0.75% ropivacaine was injected in both groups. Regional hemodynamic parameters were measured in the ipsilateral ulnar artery and radial artery, using pulsed-wave Doppler ultrasound, before and 30 minutes after the block. Regional hemodynamic parameters included peak systolic velocity (PSV), end-diastolic velocity (EDV), time averaged maximum velocity (TAMAX), resistance index (RI), pulsatility index (PI), cross-sectional area (Area) and Blood flow (Q). The intensity of sensory block was measured at 30 minutes after the block. RESULTS: There was no significant difference in the hemodynamic parameters of ulnar artery and radial artery before the block between two groups. Compared with N group, EDV, TAMAX and Q of ulnar artery were higher in U group (1.88-fold, 1.71-fold and 1.84-fold)(P < 0.01 or P < 0.05), PI and RI of ulnar artery were lower in U group (P < 0.01) at 30 minutes after the block, EDV of radial artery was higher in U group (1.47-fold) (P < 0.01), PI and RI of radial artery were lower in U group (P < 0.05) at 30 minutes after the block. Comparing the hemodynamic parameters of ulnar artery and radial artery with complete block between two groups at 30 minutes after the block, EDV, TAMAX and Q of ulnar artery in U group were higher than that in N group (1.68-fold, 1.55-fold and 1.62-fold) (P < 0.01 or P < 0.05), PI of ulnar artery in U group was lower than that in N group (P < 0.01), EDV and TAMAX of radial artery in U group was higher than that in N group (1.54-fold and 1.26-fold) (P < 0.01 or P < 0.05), PI and RI of radial artery in U group was lower than that in N group (P < 0.05). The rate of complete block in U group was higher than that in N group (28/30 vs 22/30, P < 0.05). CONCLUSION: Ultrasound-guided supraclavicular brachial plexus block enhance the degree of sympathetic block of upper extremity, especially of ulnar artery and increase the blood flow of ulnar artery compared with nerve stimulator.

Spontaneous interspecific hybridization and patterns of pollen dispersal in ex situ populations of a tree species (Sinojackia xylocarpa) that is extinct in the wild.

For endangered plants interspecific hybridization occurring in ex situ collections may lead to failure of reintroduction actions. We used Sinojackia xylocarpa, a well documented Chinese endemic species that is extinct in the wild, as a model case to address this concern. We used paternity analyses to assess the spontaneous hybridization and patterns of pollen flow between S. xylocarpa and its congener species, S. rehderiana, in conserved populations in Wuhan Botanic Garden. Interspecific hybridization events were detected in seven out of eight maternal trees of S. xylocarpa, and an average of 32.7% seeds collected from maternal trees of S. xylocarpa were hybrids. The paternity of 93 out of 249 seedlings from S. xylocarpa assigned to S. rehderiana provided convincing evidence that spontaneous interspecific hybridization occurred extensively in the living garden collection we studied. Different patterns of pollen dispersal (predominantly short-distance vs. long-distance pollination) were observed between intra- and interspecific hybridization events in the garden. Pollen dispersal within the ex situ populations was not restricted by distance, as evidenced by a lack of significant correlations between the average effective pollen dispersal distance (delta) and the geographic distances (d1 and d2) between maternal and paternal trees. The interspecific pollen-dispersal distance ranged from 10 to 620.1 m (mean 294.4 m). Such extensive hybridization in ex situ collections could jeopardize the genetic integrity of endangered species and irrevocably contaminate the gene pool if such hybrids are used for reintroduction and restoration. We recommend strongly that measures be taken to minimize the genetic risks of this kind of hybridization, including establishing buffer zones in ex situ collections, manipulating flowering phenology, testing seed lots before use in reintroduction programs, and controlling pollination for seed purity.

[Genetic risks in plant ex situ conservation].

Conserving genetic diversity of rare and endangered species and their evolutionary potential is one of the long-term goals of ex-situ conservation. Some potential genetic risks in ex-situ conservation in botanical gardens are presented. The preserved species may lack genetic representativity because of poor sampling. Inappropriate plantations, inadequate records and unclear kinships jeopardize endangered species to genetic confusion, inbreeding depression or outbreeding depression. Artificial selection and habitat conversion also potentially result endangered plants in adapting to ex-situ conservation, which had been usually overlooked. All the genetic risks can decrease the success of reintroduction and recovery. Therefore, appropriate genetic management should be carried out in botanical gardens to decrease or avoid genetic risks in ex-situ conservation.