Flowmetric comparison of respiratory inductance plethysmography and pneumotachography in horses

Respiratory inductance plethysmographic (RIP) and pneumotachographic (Pn) flows were compared dynamically in horses with bronchoconstriction. On a breath-by-breath basis, RIP was normalized to inspiratory volume from Pn, and peak [peak of subtracted final exhalation waveform (SFE(max))] and selected area [integral of subtracted final waveform during first 25% of exhaled volume (SFE(int))] differences between RIP and Pn flows during early expiration were measured in three settings: 1) healthy horses (n = 8) undergoing histamine bronchoprovocation; 2) horses with naturally occurring lower airway obstruction (AO) (n = 7); and 3) healthy horses (n = 6) given lobeline. HCl to induce hyperpnea. In setting 1, histamine challenge induced a dose-dependent increase in SFE(max) and SFE(int) differences. A test index of airway reactivity (interpolated histamine dose that increased SFE(max) by 35%) closely correlated (r(s) = 0.93, P = 0.001) with a conventional index (histamine dose that induced a 35% decrease in dynamic compliance). In setting 2, in horses with AO, SFE(max) and SFE(int) were markedly elevated, and their absolute values correlated significantly (P < 0.005) with pulmonary resistance and the maximum change in transpulmonary pressure. The effects of bronchodilator treatment on the SFE(max) and SFE(int) were also highly significant (P < 0.0001). In setting 3, hyperpnea, but not tachypnea, caused significant (P < 0.01) increases in SFE(max) but not in SFE(int). In conclusion, dynamic comparisons between RIP and Pn provide a defensible method for quantifying AO during tidal breathing, without the need for invasive instrumentation.

Carotid chemoreceptor reflex effects on coronary flow and heart rate

The innervated Langendorff's dog heart preparation in ventricular fibrillation with completely separated cross circulations to the head and heart was used for clarifying the mechanism of the carotid chemoreceptor reflex induced by nicotine, lobeline, 5-hydroxytryptamine, and acetylcholine. The effects of carotid chemoreflex were studied on the atrial rhythm and the coronary blood flow at constant pressure. A prompt decrease in atrial rate followed by a delayed acceleration was observed. Coronary dilation followed by constriction was observed concomitantly. In the atropinized heart evidences of a sympathetic component in the chemoreceptor reflex became evident. The sympathetic activity disappeared upon cooling of the head perfusion to 31 C, while the vagal action persisted. Warming to 40 C made the sympathetic effect more prominent. The reciprocal relation between the atrial rate and the coronary vascular tone may indicate a vagal coronary dilator and a sympathetic coronary constrictor effect in the dog.

ACTION OF LOBELINE ON PULMONARY ARTERY MECHANORECEPTORS OF THE CAT

1. The effects of lobeline (15 to 45 µg/kg) and of local changes of pulmonary artery pressure on the afferent activity of single neurone preparations of pulmonary artery mechanoreceptors have been studied in the intact cat. Pulmonary artery pressure was monitored via a double lumen balloon catheter passed into the pulmonary artery.

2. Pulmonary artery mechanoreceptors were distinguished from systemic mechanoreceptors by applying two simple tests to all mechanoreceptors found by random selection of single fibers from the right cervical vagus. The afferent activity of pulmonary mechanoreceptors closely followed induced changes of pulmonary artery pressure, whereas other arterial mechanoreceptors did not. Pulmonary artery pressure was increased by the rapid injection of 2 ml dextran into the right atrium and was reduced by inflation of the intravascular balloon.

3. In the absence of a rise in pulmonary artery pressure, lobeline increased the afferent activity in two phases. The early response, which was seen in 17 of the 18 fibers studied, occurred within one to two seconds after injection and was characteristically a variable and moderate response. This effect is caused probably by the diffusion of lobeline to sensory endings within the pulmonary artery wall. The delayed response occurred about eight to ten seconds later. The activity of afferent fibers was intensified conspicuously and frequencies up to 300/sec were recorded. It is probable that this is due to the action of lobeline carried by the vasa vasorum to the intramural receptors.

4. By combining the results following balloon inflation and dextran injection, the relationship between impulses per heart beat and mean pulmonary artery pressure was established for a number of pulmonary artery mechanoreceptors in the intact animal.

5. Pulmonary artery mechanoreceptors were insensitive to doses of veratridine and relatively insensitive to doses of phenyldiguanide which, in the intact cat, produce equivalent reflexogenic responses as lobeline (45 µg/kg).

6. Other intrathoracic sensory endings studied, including atrial and ventricular stretch receptors, Hering-Breuer receptors, and systemic mechanoreceptors, were completely insensitive to the doses of lobeline used in these experiments.

7. These results support earlier experiments which suggested that when lobeline is injected, its reflex effect from the pulmonary vascular bed, namely depression of ventilation, is due to its action on a pressure- or stretch-sensitive area in the region of the bifurcation of the pulmonary artery.

Parental attitudes towards the uptake of smoking by children

ISSUE ADDRESSED

Factors related to parental smoking and parenting practice have a big effect on adolescent smoking. More in-depth information about these relationships can be used to inform interventions. This study investigated Maori, Pacific Islander, New Zealand European and Asian parent attitudes and practices in relation to smoking uptake in children.

METHODS

Parents of children aged 8-15 years, recruited through the researchers' community networks and the media, participated in focus groups or interviews run by ethnically matched facilitators. Areas addressed included parents' beliefs about children smoking, their actions, and their suggestions for tobacco control activities. The data were analysed thematically.

RESULTS

Parents believed that parental smoking, peer pressure and smoking role models in the media influenced smoking uptake in children. They said they would be disappointed if their children started smoking, but their confidence in influencing them varied. Many talked to their children about the health consequences of smoking, including their own negative perceptions of smoking and smokers. Most had smoke-free homes. The parents who smoked tried to avoid smoking around children. There was a good deal of commonality across the different ethnic groups. Important differences related to the provision of interventions.

CONCLUSIONS

Parents believed in the value of a smoke-free lifestyle and wanted to protect their children from smoking. Important strategies to prevent smoking in children may include supporting parents to quit, informing them that discouraging children of any age from smoking can be effective, and providing culturally appropriate education and resources to facilitate parent/child communication about smoking.

Identity of pulmonary artery pressure and lobeline-induced ventilatory reflex

Reflex ventilatory changes following pulmonary artery pressure reduction have been compared in the α-chloralose-anesthetized intact cat to those following the intravenous injection of lobeline, phenyldiguanide, and veratridine. These drugs stimulate different groups of sensory neurons in the pulmonary vascular bed. The reflex changes initiated by pulmonary artery pressure reduction and by small doses of lobeline are predominantly ventilatory, whereas those consequent on phenyldiguanide and veratridine are not. Using specific reflex blocking procedures, it was shown that although definite and consistent separation of the responses to the three drugs could be obtained, the responses to pulmonary artery pressure reduction and lobeline could not be differentiated. It is concluded that pulmonary artery pressure fall and lobeline probably act on the same reflex, which, since it is known that the reflexogenic lobeline-sensitive zone lies in the extrapleural pulmonary arteries, must be a ventilation-regulating reflex originating from a pressure-sensitive zone in the region of the pulmonary artery bifurcation.

Infiltration properties of n-alkanes in mesoporous biochar: The capacity of smokeless support for stability and energy storage

Biochar, also named biocarbon, is a solid particulate material produced from the thermal decomposition of biomass at moderate temperatures. It has progressively become the topic of scientific interest in energy storage and conversion applications due to its affordability, environment friendliness, and structural tunability. In this study, biochar (obtained 600 °C pyrolysis) was introduced as phase change materials (PCMs) support. Three different n-alkanes (such as dodecane, tetradecane, and octadecane) are used as PCMs. The PCMs were infiltrated in the biochar network via the vacuum impregnation method. Among the biochar/n-alkane composites, one from octadecane exhibited a high latent heat storage capacity of 91.5 kJ/kg, 15.7 % and 25.9 % higher than that of dodecane and tetradecane-based composites, respectively. The molecular length of the PCMs and intermolecular interaction between the functional groups play an imperative role. The infiltration ratio of PCM in the biochar reached 50.1 % with improved thermal stability and chemical compatibility. This is attributed to the favorable morphological and structural properties (e.g., large BET surface area and mesopore structure) of the biochar that resides the n-alkanes found in the nanosized chain length. Hence, this report will lay a foundation for the application of biochars in thermal energy management systems.

Smoke or smokeless moxibustion treatment for breech presentation: A three-arm pilot trial

AIMS

We conducted a pilot trial to compare the effects of smoke and smokeless moxibustion with a control as a possible supplement to external cephalic version (ECV) for converting breech to cephalic presentation and increasing adherence to cephalic position, and to assess their effects on the well-being of the mother and child.

METHODS

We used a quasi-experimental design with 3 arms: a smoke moxibustion (SM) (n = 20) and smokeless moxibustion (SLM) (n = 20) groups (20-min acupoint BL67 stimulation once or twice daily for 10-14 days), and a control group (n = 20). The participants had singleton breech presentations between 33 and 35 gestation weeks. The primary outcome was cephalic presentation at the conclusion of intervention. The secondary outcomes were cephalic presentation at birth and effects on mother and child well-being.

RESULTS

At the conclusion of intervention, cephalic presentation was higher in the SLM (60.0%) than the control groups (25.0%), Relative Risk 2.40, 95% Confidence Interval [1.04-5.56]; there was no significant difference for SM. At birth, there were no significant differences in cephalic presentation or well-being.

CONCLUSION

SLM treatment showed an increasing trend towards cephalic presentation at the conclusion of intervention. Although significant differences were not observed at birth possibly due to the small samples and non-randomization, moxibustion was safe, and not associated with perinatal morbidity and mortality. A randomized controlled trial with a larger sample is warranted to ascertain SLM treatment as a possible ECV supplement for converting and increasing adherence to cephalic position.

Crystals in the leaf of Lobelia inflata Linn

The leaves of Lobelia inflata Linn. have been said either to contain crystals of calcium oxalate or to have no crystals of any kind. Other descriptions note the presence of droplets of oil in the mesophyll. This anomalous situation needs clarifying. It is shown that the crystals are fat.