Does an oral appliance reduce palatal flutter and tongue base snoring?

OBJECTIVES: Oral appliances are designed to treat snoring and sleep apnea by advancing the mandible and tongue. We test the hypothesis that an oral appliance affects palatal snoring as well as tongue base obstruction. METHODS: Prospective observational cohort study. Sixty patients with a chief complaint of snoring with or without apnea were enrolled. Each patient underwent a home sleep test followed by 3 weeks sleeping with an oral appliance. Each patient then underwent a repeat home sleep test while using the device. RESULTS: There was a statistically significant improvement in the snores per hour (P = 0.0005), the maximum snoring loudness (P = 0.0001), average snoring loudness (P = 0.00001), and the percentage of palatal snoring (P = 0.0007). There was also a significant decrease in oxygen desaturation events (P = 0.003). CONCLUSIONS: This study suggests oral appliances may be effective treatment for both palatal and tongue base snoring.     

Herpetic croup: two case reports and a review of the literature

Croup is an acute infectious illness usually occurring in children; it is characterized by brassy cough and stridor. The main pathogens include mainly parainfluenza and influenza viruses. Recently there have been reports of prolonged croup caused by the herpes simplex viruses. We report two cases of prolonged croup due to herpes simplex types 1 and 2. We also review and summarize the reported pediatric cases of herpetic croup.     

Phosphodiesterase isozyme inhibition, activation of the cAMP system, and positive inotropy mediated by milrinone in isolated guinea pig cardiac muscle

The purpose of the present study was to examine the interrelationships among phosphodiesterase (PDE) isozyme inhibition, cAMP formation, activation of cAMP-dependent protein kinase (cAPK), and positive inotropy in isolated guinea pig cardiac muscle mediated by the cardiotonic/vasodilator agent, milrinone. Milrinone was a potent and selective inhibitor of the "low Km" cAMP PDE isozyme (peak III) isolated by diethylaminoethyl ether cellulose chromatography, with IC50 values of 0.7 microM for peak III PDE and 100 microM for peak I PDE. In isolated papillary muscles frozen at peak inotropic responses, positive and significant correlations were evident between isometric force development as a function of cAMP content (r = 0.72, p less than 0.05) or cAPK activity ratio, an index of activation of cAPK (r = 0.79, p less than 0.001), for concentrations of milrinone from 0.1-1000 microM. Similar correlations were evident in muscles frozen at peak inotropic responses for the beta-adrenoreceptor agonist isoproterenol (r = 0.96, p less than 0.001; r = 0.98, p less than 0.001, respectively), but not for ouabain or Bay K-8644. The temporal sequence of these events was also quantitated for concentrations of milrinone (100 microM) and isoproterenol (3 nM) that produced approximately a 100% increase in isometric force. Whereas early time interval of force development (30 s, 1 min, isoproterenol; 30 s milrinone) were not accompanied by significant increases in either cAMP content or cAPK activity ratio, peak increases in force development for both isoproterenol (2 min) and milrinone (1 min) were related to peak increases in cAPK activity ratios. In summary, these results show that significant increases in cAMP content or cAPK activation are correlated with positive inotropy in isolated guinea pig papillary muscles with milrinone. These correlations occur at concentrations of milrinone that inhibit cardiac PDE isozymes and are similar to the known cAMP-dependent cardiostimulant isoproterenol. These data support the hypothesis that selective PDE isozyme inhibition is a mechanism by which milrinone effects positive inotropy.     

Band-pass response properties of rat SI neurons

Rats typically employ 4- to 12-Hz "whisking" movements of their vibrissae during tactile exploration. The intentional sampling of signals in this frequency range suggests that neural processing of tactile information may be differentially engaged in this bandwidth. We examined action potential responses in rat primary somatosensory cortex (SI) to a range of frequencies of vibrissa motion. Single vibrissae were mechanically deflected with 5-s pulse trains at rates /=3 Hz. In contrast with this low-pass feature of the response, several other characteristics of the response revealed bandpass response properties. While average evoked response amplitudes measured 0-35 ms after stimulus onset typically decreased with increasing frequency, the later components of the response (>15 ms post stimulus) were augmented at frequencies between 3 and 10 Hz. Further, during the steady state, both rate and temporal measures of neural activity, measured as total spike rate or vector strength (a measure of temporal fidelity of spike timing across cycles), showed peak signal values at 5-10 Hz. A minimal biophysical network model of SI layer IV, consisting of an excitatory and inhibitory neuron and thalamocortical input, captured the spike rate and vector strength band-pass characteristics. Further analyses in which specific elements were selectively removed from the model suggest that slow inhibitory influences give rise to the band-pass peak in temporal precision, while thalamocortical adaptation can account for the band-pass peak in spike rate. The presence of these band-pass characteristics may be a general property of thalamocortical circuits that lead rodents to target this frequency range with their whisking behavior.     

Behavioural strategies used by the hookworms Necator americanus and Ancylostoma duodenale to find, recognize and invade the human host

The infective third-stage larvae of the hookworms Necator americanus and Ancylostoma duodenale infect their human hosts by active skin invasion, but A. duodenale is in addition capable of oral infection. The behaviour of the larvae when crawling on surfaces has already been described. Here we analyse in various in vitro systems the other behavioural invasion phases: activation, penetration, and orientation within the host. The larvae normally remained in a motionless, energy-saving, resting posture. An activation to sinusoidal locomotion was stimulated in both species by similar cues such as touch, vibration, water currents, heat, light, and chemicals. Human breath in addition stimulated searching and waving (nictating) behaviour, which facilitates a change-over to the host. Activating cues in air streams were warmth and moisture; CO₂ activated only in combination with warmth and/or moisture. Penetration behaviour in both species was stimulated by warmth and skin extracts. The stimulating components of skin extracts were fatty acids, but their stimulating characteristics differed from those inducing schistosome cercarial skin penetration. After penetration into agar substrates, both species showed thermo-orientation, but only A. duodenale followed gradients of serum. The directing serum cues were not amino acids and glucose (the supposed cues for schistosome blood vessel localization), but Ringers solution attracted the larvae. The host-finding and host-invasion behaviour of both hookworm species is well adapted to the invasion of the human skin, and there seems to be no particular adaptation of A. duodenale behaviour to the oral infection mode. Hookworm host-finding behaviour is not as complex as that of schistosome cercariae but seems well adapted to the ecological conditions in the transmission sites.     

The composition of foetal and maternal blood during parturition in the ewe

1. Changes in the composition of foetal and maternal blood have been followed during the last 5-10 days of gestation and throughout parturition in the conscious sheep.2. Catheters were placed in the foetal inferior vena cava through a tarsal vein and in a maternal uterine vein in ten ewes under sodium pentobarbitone anaesthesia. In four of the foetuses blood pressure and heart rates were recorded before and during parturition from an arterial catheter.3. Foetal blood gas tensions, pH and PCV remained stable during the latter part of gestation and throughout labour until 15 min before delivery, when P(O) (2) and pH fell while PCV and P(CO) (2) rose in about 50% of the foetuses examined.4. Metabolite levels were also relatively stable at the end of gestation. Plasma glucose in both maternal and foetal blood rose during the hour before birth, while foetal plasma lactate was elevated as early as 4 hr before birth and was unrelated to any maternal changes. Foetal fructose levels were maintained until after delivery.5. Rises in foetal blood pressure before birth were associated with uterine contractions. Foetal heart rate changes during labour varied in different individuals. The heart rate either fell gradually before birth or there was little change until a sudden drop at delivery.6. The most striking changes in the lamb occurred at, or a few minutes after, birth; pH and P(O) (2) fell, P(CO) (2) and PCV rose, and bradycardia at delivery was succeeded by prolonged tachycardia. There were marked increases in plasma glucose and lactic acid at this time.7. P(O) (2) rose rapidly once respiration was established, while pH and P(CO) (2) levels were restored within (1/2)-1 hr. Plasma FFA levels rose rapidly in the lambs 10-30 min after birth and remained high, while plasma glucose, lactate and fructose concentrations declined slowly in the 1-2 hr after birth, although suckling raised the plasma glucose levels. Considerable individual variation in the metabolite levels was found in both ewes and lambs.8. In the majority of ewes delivery was associated with an abrupt maternal hyperglycaemia, with a much smaller rise in lactate and virtually no change in maternal blood gases or pH.9. These findings are discussed in relation to existing information on new-born lambs and the human infant during birth.     

Improving delivery of hydrophobic drugs from hydrogels through cyclodextrins

A simple and effective technique of improving delivery of hydrophobic drugs from swellable systems is presented. Conventional methods of drug loading in hydrogel systems are limited by the characteristics of the pharmacological agent. The approach we present uses complexants to modulate drug release. Crosslinked poly(ethylene glycol) (PEG) hydrogels were synthesized, characterized, and used for vascular applications. The release of cyclosporine (CyA) from PEG hydrogels is significantly altered by the sterilization techniques. It was hypothesized that the release of CyA from PEG hydrogels can be modulated by using complexants. A cyclodextrin-CyA complex solution was prepared and used for drug loading. The sterilized PEG hydrogels that were loaded using the cyclodextrin-CyA complex solution had favorable release characteristics compared with the release from PEG hydrogels that were loaded using the conventional technique. Hence, drug release from swellable systems can be tailored by the application of this strategy.