Parasympathetic innervation of canine tracheal smooth muscle

To investigate whether efferent parasympathetic fibers to the trachealsmooth muscle course through the pararecurrent nerve rather than therecurrent or the superior laryngeal nerve, we stimulated all threenerves in anesthetized dogs. We also recorded the pararecurrentnerve activity response to bronchoconstrictor stimuli and compared itwith pressure changes inside a saline-filled cuff of an endotrachealtube. Electrical stimulation (30 s, 100 Hz, 0.1 ms, 10 mA) increasedtracheal cuff pressure by 21.0 ± 3.2 and 1.3 ± 0.7 cmH₂O for the pararecurrent and the recurrent laryngealnerve, respectively. Stimulation of the superior laryngeal nerveincreased tracheal cuff pressure before, but not after, sectioning ofthe ramus anastomoticus, which connects it to the pararecurrent nerve.Intravenous administration of sodium cyanide increased pararecurrentnerve activity by 208 ± 51% and tracheal cuff pressure by14.4 ± 3.5 cmH₂O. Elevation of end-tidalPCO₂ to 50 Torr increased pararecurrent nerveactivity by 49 ± 19% and tracheal cuff pressure by 8.4 ± 3.6 cmH₂O. Further elevation to 60 Torr increasedpararecurrent nerve activity by 101 ± 33% and tracheal cuffpressure by 11.3 ± 2.9 cmH₂O. These results lead usto the conclusion that parasympathetic efferent fibers reach the smoothmuscle of the canine trachea via the pararecurrent nerve.

     

Detection of nanometer-sized particles in living cells using modern fluorescence fluctuation methods

Nanosized materials are increasingly used in medicine and biotechnology but originate also from various aerosol sources. A detailed understanding of their interaction with cells is a prerequisite for specific applications and appraisal of hazardous effects. Fluorescence fluctuation methods are applied to follow the time-course of the translocation and distribution of fluorescent 20 nm polystyrene nanoparticles with negative surface charges in HeLa cells under almost physiological conditions. The experimental results demonstrate that singular particles enter the cell without significant contribution by endocytotic mechanisms and are distributed within the cytoplasm. Subsequently aggregation is observed, which can be blocked by cytotoxins, like Genistein and Cytochalasin B, interfering with cellular uptake processes. The observed non-active uptake is due to non-specific interactions with the cell surface and could be responsible for distribution of nanometer-sized materials in tissue.     

The temperature dependence of water and counter ion order in soap-water mesophases. A deuterium and sodium NMR study

Deuterium magnetic resonance (DMR) spectra of the water and hydrocarbon chains in potassium and sodium palmitates and sodium magnetic resonance spectra of sodium in sodium palmitate demonstrate correlations between water, hydrocarbon chain and counter ion order. In the lamellar phase of potassium palmitate the order parameters inferred from DMR splittings of D₂O and the first few methylene chain segments initially increase and then decrease with increasing temperature. This is explained in terms of a model where the lipid-water structure at low temperatures imposes a direction for which all the order parameters are smaller than for the higher temperature structure for purely geometric reasons. As temperature increases the structuring effect of water decreases and there is an “apparent” increase in order until at even higher temperatures there is an intrinsic decrease in order parameter. In addition, for potassium palmitate the DMR splittings of D₂O and the first few methylene segments indicate a “phase transition” within the liquid crystalline phase.     

Exercise-induced intrapulmonary shunting of venous gas emboli does not occur after open-sea diving.

Paradoxical arterializations of venous gas emboli can lead to neurological damage after diving with compressed air. Recently, significant exercise-induced intrapulmonary anatomical shunts have been reported in healthy humans that result in widening of alveolar-to-arterial oxygen gradient. The aim of this study was to examine whether intrapulmonary shunts can be found following strenuous exercise after diving and, if so, whether exercise should be avoided during that period. Eleven healthy, military male divers performed an open-sea dive to 30 m breathing air, remaining at pressure for 30 min. During the bottom phase of the dive, subjects performed mild exercise at approximately 30% of their maximal oxygen uptake. The ascent rate was 9 m/min. Each diver performed graded upright cycle ergometry up to 80% of the maximal oxygen uptake 40 min after the dive. Monitoring of venous gas emboli was performed in both the right and left heart with an ultrasonic scanner every 20 min for 60 min after reaching the surface pressure during supine rest and following two coughs. The diving profile used in this study produced significant amounts of venous bubbles. No evidence of intrapulmonary shunting was found in any subject during either supine resting posture or any exercise grade. Also, short strenuous exercise after the dive did not result in delayed-onset decompression sickness in any subject, but studies with a greater number of participants are needed to confirm whether divers should be allowed to exercise after diving.     

Deuterium magnetic resonance of selectively deuterated cholesteryl esters in dipalmitoyl phosphatidylcholine dispersions

Dispersions (50 wt% water) containing 95 mol% dipalmitoyl phosphatidylcholine/5 mol% deuterated cholesteryl palmitate (or stearate) were studied using ²H-NMR. Incorporation of ester into the phospholipid bilayer was found to be 0.5 mol% at 50°C. From the profile of ²H quadrupolar splitting vs. chain position, support for an average conformation resembling a ‘horseshoe’ within the bilayer is obtained. Quadrupolar relaxation times $\text{T}{}_{2e}$ of approx. 250 μs and approx. 850 μs are measured for cholesteryl palmitate-2,2-d₂ and cholesteryl palmitate-16,16,16-d₃, respectively, which are less than one-half those obtained for the corresponding positions in dipalmitoyl-d₆₂ phosphatidylcholine. This is ascribed to a slower rate of motion of the ester chain and/or an extra, slow motion of the molecule.     

Investigation on the optimal term of one-fold insecticide application for decreasing onion thrips ( Thrips tabaci Lindeman, Thysanoptera, Thripidae) damage on early white cabbage

An impact of the term of one-fold insecticide application to reduce the damage of the onion thrips in early white cabbage was established. During the growing season plants were treated with insecticide (abamectin) in three different terms (treatment 1: 9 June, treatment 2: 16 June, treatment 3: 23 June, and treatment 4: untreated). On the exterior leaves of cabbage heads, treated with the insecticide, statistically significantly lower mean index of damage was determined as compared to the untreated plants. No significant differences were found between three different terms of application. The majority of the economically important damages in all of the treatments was found between the 3rd and 6th exterior leaf in the head. The highest mean weight of heads (1517.3 g) and mean net weight of heads I = mean weight of heads - weight of damaged and removed leavesl (1166.3 g) were established in plants which were treated the last. These parameters were the lowest in untreated plants (1083.3 g / 805.6 g). The yield loss due to damaged leaves removal amounted from 22.9% (treatment 2) to 25.6% (treatment 4). Based on the results obtained in this research we concluded that yield loss due to onion thrips attack in plants with one-fold insecticide application is not substantially lower as in untreated plants (though statistically significant differences between them were established), because insecticide cannot reach the interior leaves in the head. Substantial differences in the total and net weight of heads between the treatments and especially between the treated and untreated plants are explained by the fact that feeding of numerous thrips populations in the heads and on the exterior cabbage leaves negatively affects plant physiology and yield. The highest average yield in plants which were treated the last indicates a possibility that insecticide also inhibits plant growth and development to a certain extent.     

Deuterium magnetic resonance study of cholesteryl esters in membranes

The ternary systems EYL:H2O (50:50 wt %) containing 1 and 5 mol % cholesteryl palmitate-d31 or 1 and 5 mol % cholesteryl palmitate-16,16,16,16-d3 have been studied. Cholesteryl palmitate-d31 gave a unique deuterium magnetic resonance spectrum corresponding to a homogeneous (delta vQ = 3 and 12 kHz) and a solid phase (deltaVQ = 38 and 118 kHz). From the characteristic spectra and spin-lattice relaxation times, a procedure for calculating the amount of each phase present in the ternary mixture is given resulting in a maximum value of homogeneously dissolved cholesteryl palmitate of 0.2 +/- 0.1 mol % and a solid fraction above 0.2 mol %. The most probable order parameter for the (-CD2)n portion of the homogeneous fraction of cholesteryl palmitate-d31 was determined from the quadrupolar splittings to be S = 0.1 which is less than one-half that of the order parameter found for the lecithin chains. Possible explanations for the diminution of the order parameter for cholesteryl ester in bilayers are discussed.     

Alpha-Adrenergic receptor responsiveness is preserved during prolonged exercise

Our laboratory has previously reported a decline in sympathetic nervous system restraint of skeletal muscle blood flow during prolonged mild-intensity exercise. This decline may be explained by a decrease in alpha(1)- and alpha(2)-adrenergic receptor responsiveness over time. Thus the purpose of the present study was to investigate the effect of exercise duration on alpha(1)- and alpha(2)-adrenergic receptor responsiveness during prolonged constant-load exercise. Mongrel dogs (n = 6) were instrumented chronically with transit-time flow probes on the external iliac arteries and an indwelling catheter in a branch of the femoral artery. On separate days, flow-adjusted doses of selective alpha(1)- (phenylephrine) alpha(2)-adrenergic-receptor (clonidine) agonists, and tyramine (to evoke endogenous norepinephrine release) were infused following 5, 30 and 50 min of mild-intensity treadmill exercise (3 miles/h), with hindlimb blood flow (HBF) and mean arterial pressure (MAP) monitored continuously. Vascular conductance (VC) was calculated as HBF/MAP. While the dogs ran on the treadmill at 3 miles/h, infusion of phenylephrine resulted in similar decreases in VC after 5 [73% (SD 10)], 30 [76% (SD 9)], and 50 [73% (SD 10)] min of exercise. Infusion of the alpha(2)-agonist clonidine also produced similar decreases in VC after 5 [58% (SD 10)], 30 [58% (SD 11)], and 50 [53% (SD 12)] min of exercise. Infusion of tyramine resulted in similar decreases in VC after 5 [55% (SD 15)], 30 [51% (SD 10)], and 50 [50% (SD 7)] min of exercise. These results demonstrate that alpha(1)- and alpha(2)-adrenergic receptor responsiveness to infusion of selective alpha(1)- and alpha(2)-adrenergic-receptor agonists and endogenous norepinephrine release (tyramine) does not decline during prolonged mild-intensity exercise. Thus a decrease in alpha-adrenergic receptor responsiveness over time does not appear to be responsible for the decrease in sympathetic restraint of muscle blood flow during prolonged exercise.     

Expression of endothelial selectin ligands on human leukocytes following dive

The fact that impaired endothelial-dependent vasodilatation after scuba diving often occurs without visible changes in the endothelial layer implies its biochemical origin. Since Lewis x (CD15) and sialyl-Lewis x (CD15s) are granulocyte and monocyte carbohydrate antigens recognized as ligands by endothelial selectins, we assumed that they could be sensitive markers for impaired vasodilatation following diving. Using flow cytometry, we determined the CD15 and CD15s peripheral blood mononuclear cells of eight divers, 30 mins before and 50 mins after a single dive to 54 m for 20 mins bottom time. The number of gas bubbles in the right heart was monitored by ultrasound. Gas bubbles were seen in all eight divers, with the average number of bubbles/cm(2) 1.9 +/- 1.9. The proportion of CD15 + monocytes increased 2-fold after the dive as well as the subpopulation of monocytes highly expressing CD15s. The absolute number of monocytes was slightly, but not significantly, increased after the dive, whereas the absolute number of granulocytes was markedly elevated (up to 61%). There were no significant correlations between bubble formation and CD15 + monocyte expression (r = - 0.56; P = 0.17), as well as with monocytes highly expressing CD15s (r = 0.43; P = 0.29). This study suggests that biochemical changes induced by scuba diving primarily activate existing monocytes rather than increase the number of monocytes at a time of acute arterial endothelial dysfunction.