Localisation of 11ß-Hydroxysteroid Dehydrogenase Type 2 in Mineralocorticoid Receptor Expressing Magnocellular Neurosecretory Neurones of the Rat Supraoptic and Paraventricular Nuclei.

An accumulating body of evidence suggests that the activity of the mineralocorticoid, aldosterone, in the brain via the mineralocorticoid receptor (MR) plays an important role in the regulation of blood pressure. MR was recently found in vasopressin and oxytocin synthesising magnocellular neurosecretory cells (MNCs) in both the paraventricular (PVN) and supraoptic (SON) nuclei in the hypothalamus. Considering the physiological effects of these hormones, MR in these neurones may be an important site mediating the action of aldosterone in blood pressure regulation within the brain. However, aldosterone activation of MR in the hypothalamus remains controversial as a result of the high binding affinity of glucocorticoids to MR at substantially higher concentrations compared to aldosterone. In aldosterone-sensitive epithelia, the enzyme 11ß-hydroxysteroid dehydrogenase type 2 (11ß-HSD2) prevents glucocorticoids from binding to MR by converting glucocorticoids into inactive metabolites. The present study aimed to determine whether 11ß-HSD2, which increases aldosterone selectivity, is expressed in MNCs. Specific 11ß-HSD2 immunoreactivity was found in the cytoplasm of the MNCs in both the SON and PVN. In addition, double-fluorescence confocal microscopy demonstrated that MR-immunoreactivity and 11ß-HSD2-in situ hybridised products are colocalised in MNCs. Lastly, single-cell reverse transcriptase-polymerase chain reaction detected MR and 11ß-HSD2 mRNAs from cDNA libraries derived from single identified MNCs. These findings strongly suggest that MNCs in the SON and PVN are aldosterone-sensitive neurones.

Abundance, age structure, and voltinism of light brown apple moth populations in California.

The light brown apple moth, Epiphyas postvittana (Walker), is native to Australia and first was detected in California in 2006. In this study, we regularly sampled populations on Leptospermum laevigatum (Gaertn.) F.Muell. at two sites in San Francisco and on Arctostaphylos densiflora M.S. Baker at two sites in Santa Cruz over a 2-yr period to monitor the abundance, age structure, and voltinism of this potential pest in relation to degree-days. Our results showed that larval abundance declined at two sites, cycled with peaks in midsummer at one site, and remained steady at one site. Generations overlapped at all four sites with the full range of larval instars being present for most of the year, although populations during the winter were predominantly mid to late instars. Accumulated degree-days predict an average of 3.27 and 4.58 generations per year in San Francisco and Santa Cruz, respectively, which matched our observed peaks of late-instar larvae in the field remarkably well. This new information on light brown apple moth phenology in coastal California will be invaluable for the development of effective monitoring and management strategies for this new invader in the studied region.

Molecular markers reveal strong geographic, but not host associated, genetic differentiation in Aphidius transcaspicus, a parasitoid of the aphid genus Hyalopterus.

Host plant associated genetic differentiation is a common phenomenon in phytophagous insects, but the degree to which such associations sequentially drive diversification at higher trophic levels is not as well understood. A recent study examining neutral molecular markers in Hyalopterus aphids revealed that genetic structure in this genus is strongly determined by primary host plant use (Prunus spp.). In this paper, we take a similar approach to determine whether this host plant specificity has affected genetic structure in the parasitoid Aphidius transcaspicus, an important natural enemy of Hyalopterus spp. in the Mediterranean. Mitochondrial DNA (428 bp) and seven microsatellite loci were examined in parasitoids collected from aphid populations on almond, apricot, peach and plum trees from Spain and Greece. In contrast to the previous findings for Hyalopterus from the same regions, here we find no evidence for host associated diversification in A. transcaspicus at the species level or below, though geographic structure between regional populations is exceptionally high. These findings have several implications for our understanding of the ecology and evolution of A. transcaspicus as well as for its use as a biological control agent for Hyalopterus, suggesting that a consideration of host plant specificity may be less critical than factors such as climatic suitability or geographic origins of invasive populations.

Heel-shoe interactions and the durability of EVA foam running-shoe midsoles.

A finite element analysis (FEA) was made of the stress distribution in the heelpad and a running shoe midsole, using heelpad properties deduced from published force-deflection data, and measured foam properties. The heelpad has a lower initial shear modulus than the foam (100 vs. 1050 kPa), but a higher bulk modulus. The heelpad is more non-linear, with a higher Ogden strain energy function exponent than the foam (30 vs. 4). Measurements of plantar pressure distribution in running shoes confirmed the FEA. The peak plantar pressure increased on average by 100% after 500 km run. Scanning electron microscopy shows that structural damage (wrinkling of faces and some holes) occurred in the foam after 750 km run. Fatigue of the foam reduces heelstrike cushioning, and is a possible cause of running injuries.

Host-limited dynamics of autoparasitoids.

Autoparasitoids, an important class of intraguild predators used in classical biological control, have a unique biology. Females develop as primary endoparasitoids of scale insects and whiteflies. Males develop at the expense of conspecific or heterospecific parasitoid prepupae. To evaluate the effect of autoparasitism on host suppression, system stability, and parasitoid coexistence, stage-structured differential equation models are developed and analysed. For a host-parasitoid system, autoparasitism stabilizes host-parasitoid oscillations generated by developmental delays of the parasitoid. In host-autoparasitoid-primary parasitoid systems, a distinction between obligate (i.e. parasitoid only attacks conspecifics for the production of males) and facultative (i.e. parasitoid attacks conspecifics and heterospecifics for the production of males) autoparasitism is drawn. Coexistence between an obligate autoparasitoid and primary parasitoid occurs if and only if the autoparasitoid can invade at lower host densities than the primary parasitoid, and the primary parasitoid can suppress the host to a lower equilibrium density than the autoparasitoid. When coexistence occurs, the primary parasitoid determines the host equilibrium abundance. Interactions between facultative autoparasitoids and primary parasitoids can lead to a priority effect, and, less likely, to coexistence. When coexistence occurs, the invasion of the facultative autoparasitoid into the host-primary parasitoid system raises the equilibrium density of the host. In either coexistence scenario, the invasion of an autoparasitoid can stabilize an unstable host-primary parasitoid system. The analysis concludes by showing that the introduction of an autoparasitoid to a host-primary parasitoid system can improve host suppression in the short-term despite possible long-term disruption.

Quantitative evaluation of hypothermia, hyperthermia, and hemodilution on coagulation.

The purpose of this study was to investigate the effects of temperature change on the coagulation time of blood at two different hematocrit levels by using various coagulation-monitoring devices. The devices used in this study were the Bayer Rapid Point Coag Analyzers, Hemochron Jr. Signature, Hemochron Response, Medtronic ACT II, and Haemoscope Thrombelastograph. One unit of human bank blood was used in this study. The hematocrit level was adjusted to 40% and 20%. A control bath and experimental bath were set up. Control blood was maintained at 37 degrees C and tested every 45 +/- 15 min throughout the experimental period of 6 h to demonstrate the stability of the model. The experimental blood was tested at temperature points of 37, 32, 27, 32, 37, 42, and 37 degrees C. Activated clotting time (ACT) tended to increase when the temperature was initially decreased from 37 to 27 degrees C, which reached a statistically significant level when measured by the Hemochron Response at both the 20% (147 +/- 10.7 to 159.3 +/- 11.0, p < .0332) and 40% hematocrit level (130 +/- 14.9 to 152.1 +/- 19.7, p < .0148). ACT was decreased significantly (p < .05) when the temperature was increased to 42 degrees C as measured by all machines except the Hemochron Jr. Signature at the 20% hematocrit level. ACT was significantly higher (p < .05) at a 20% hematocrit level as compared to that at a 40% hematocrit level on all devices for the majority of temperature points. These data suggested that hypothermia only increased ACT when measured by a macrosample device requiring a milliliter sample (Hemochron Response). However, hemodilution induced anticoagulatory effects and hyperthermia caused an acceleration in coagulation by all devices utilized in this study.

Effects of ultrafiltration on enoxaparin: an in vitro analysis.

The use of low molecular weight heparins (LMWH) as an anticoagulant in the heparin-resistant patient poses challenges during cardiopulmonary bypass (CPB). The ultrafiltrability of LMWH has not been previously examined. The purpose of this study was to determine the effects of continuous ultrafiltration on the concentraton of a LMWH, enoxaparin. An in vitro analysis was performed using fresh whole human blood and an extracorporeal circuit containing four parallel ultrafiltrators and a cardiotomy reservoir with an integrated heat exchanger. Constant conditions included temperature (37 degrees C), flow (0.20 L-min(-1)) transmembrane pressure (200 mmHg), and hematocrit (25 +/- 2%). Samples were collected at the inlet, outlet, and ultrafiltrate line at one and three min for one control trial and again for each of the four hemoconcentrators following the bolus of enoxaparin. Coagulation measurements included a viscoelastic monitor (TEG), activated clotting time (ACT), activated partial thromboplastin time (aPTT), and quantitative analysis utilizing a membrane-based electrode for potentiometric measurement of polyanionic concentrations of enoxaparin. Enoxaparin concentration, from inlet to outlet, increased from 2.95 +/- 0.64 to 5.89 +/- 0.95 (p < .001) at 1 min and 4.24 +/- 0.49 to 7.89 +/- 0.606 (p < .001) at 3 min. Kinetic clot activity, as assessed by the TEG index, decreased from -3.8 +/- 2.5 vs. -10.5 +/- 6.0; (p < .01) pre- to postultrafiltrator samples after 3 min. ACT and aPTT results demonstrated no significant change. In conclusion, this study demonstrates enoxaparin is concentrated with the use of continuous ultrafiltration. Functional coagulation studies also indicate a concentrating effect, primarily via the TEG.

The effect of volume replacement on serum protein concentration during cardiopulmonary bypass.

Although controversy exists concerning the optimal total protein and colloid osmotic pressure that should be maintained during cardiopulmonary bypass (CPB), the primary volume expanders remain albumin and 6% hetastarch. The purpose of this study was to quantify the effect of adding boluses of volume replacement agents under various conditions to total serum protein values during CPB. A standard CPB circuit was utilized in eight 45-kg swine that had a priming volume (physiologic saline solution) of 2309 +/- 245 mL. Volumetric alterations occurred throughout the CPB period by the addition of combinations of physiologic saline solution, 6% hetastarch or 5% swine albumin. Pre- and postadministration samples were assayed for total serum protein, total protein, and albumin throughout the CPB period and at pre- and postvolume administration times. There was a significant decline in total serum protein with the initiation of CPB (6.14 +/- 0.49 g/dL vs. 3.40 +/- 0.43 g/dL, p < .0001). Addition of 12.5 g of swine albumin (N = 5) to two different swine increased total serum protein significantly when compared to adding 500 mL of 6% hetastarch (N = 6) (swine albumin 12.4 +/- 6.3% vs. hetastarch 3.3 +/- 2.1%, p < .005). A reduction in total serum protein occurred after hemodilution with varying amount of physiologic saline solution: 250-450 mL (7.4 +/- 4.5%), 451-650 mL (9.6 +/- 5.6%), and 651-1050 mL (19.4 +/- 4.0%). In summary, knowledge of total serum protein concentration and estimated circulating blood volume can be used to guide albumin and hetastarch administration following hemodilution.

Protection of the side of the head.

The side of the head is a frequent impact site for pedal cyclists, motorcyclists, and industrial workers. It is vulnerable to impact, yet many helmet standards do not have impact tests at the side of the helmet. Laboratory impact tests should reproduce the phenomena in real impacts, but usually they do not allow the headform to rotate, or ignore the effect of the neck on the motion of the head. The authors designed a linkage, simulating the flexibility of the neck, for use with anthropomorphic dummies in helmet testing. Impacts at the side of the helmet, normal to the helmet surface, were made with flat and hemispherical strikers. Head rotation during impacts caused the impact site to move, in some cases to below the level protected by the helmet. The peak angular head acceleration correlated with the peak linear accelerations. Neck flexibility means that helmets can protect the head from higher kinetic energy impacts than those specified in standards using immovable headforms or impact anvils. The load spreading efficiency of polypropylene foam, used in soft shell bicycle helmets, is better than that of polystyrene foam. The authors conclude that the side of the head can be protected by a suitable helmet design.

The biomechanics of hip protectors.

The mode of action of one design of hip protector was investigated. A dummy femur surrounded by a flesh substitute was impacted from a range of heights while the forces on the trochanter and the surrounding flesh were measured. The protector doubled the estimated fall distance for fracture of the trochanter. The protection mechanisms are load transfer to the muscles of the thigh and energy absorption in the protector. Hip protectors could absorb more energy safely if they were thicker, or if the shell design was modified.

The effectiveness of foams in bicycle and motorcycle helmets.

The optimisation of the foam used for shock absorption in bicycle and motorcycle helmets is considered. It is shown that for the former, the ideal foam yield stress for impact with a rigid protruding object is higher than that for impact with a deformable flat object. Therefore, the design must be a compromise. For motorcycle helmets the shell stiffness is higher and the force to cause shell buckling plays a significant part in the response. Lower density foams can be used only if the impact test standards are rewritten with less emphasis on impacts with convex and pointed objects.

Protective capability of bicycle helmets.

Cycle helmets that meet UK and US standards have been tested. The mechanisms of energy absorption for frontal and side impacts have been analysed. A good helmet should protect the wearer for impacts up to 15 mph into a rigid flat surface.

Performance of horse-riding helmets in frontal and side impacts.

Cases of head injury are reviewed in which riders wearing jockey skull caps have suffered impacts to the front, back or side of their helmets. The design and constructional materials of such helmets are assessed. Impact tests that simulate the accidents confirm the low energy absorption potential of some helmets for lateral impacts. Most pedal or motorcycle helmet designs afford better lateral impact protection.

The estimation of mean duration from stage frequency data.

A simple method of estimating duration from stage frequency data is derived. A simulation model of the passage of individuals through a particular stage in the life-cycle is presented, together with results from the model on the influence of recruitment, development and mortality on the parameters used in the estimation of stage duration. The application of the method to field data is described and a test example, using simulated data, is given.

The estimation of recruitment from stage frequency data.

A general relationship is derived for the area of the sample curve for a given stage in the life-cycle, in terms of the mean survival rate and duration and the number entering the stage. The influence of recruitment, development and mortality patterns on the area of the sample curve is investigated. The results indicate a simple method of analysing stage frequency data to produce a best estimate of the number entering each stage. A test example, using simulated data, is provided with a discussion of the method in relation to other techniques based on the area of the sample curve.