Features of the antiviral effect of carbocyclic compounds depending on their concentration

As there are no studies done on the prevalence of intestinal parasites in Lebanon since 1967, this study was undertaken to reveal the current patterns of intestinal parasitic infestations in Lebanese patients from two geographic regions: Beirut and Tripoli. Analysis was based on 33,253 stool specimens examined at the American University of Beirut Medical Center (AUH) and 11,611 specimens examined at the Islamic Hospital (IH) in Tripoli over five and three years, respectively. The prevalence of intestinal parasites at AUH and IH were 8.47% and 45.35%, respectively (overall 18%). The prevalence in males vs females was almost the same; being 8.23% vs 8.74%, and 44.67% vs 45.88%, at AUH and IH, respectively. Multiple infections were noted in 8.8% and 3.5% of stool specimens at AUH and IH, respectively. Although 18 different types of parasites were encountered, the most common pathogenic parasites found at AUH vs IH were: Giardia lamblia (20.7% vs 10.5% of parasites found), Entamoeba histolytica (19.41% vs 1.25%), Taenia spp. (6.03% vs 4.08%) and Ascaris lumbricoides (2.09% vs 46.97%). The overall yearly or monthly prevalence of parasites recovered from both hospitals did not show clear seasonal patterns. Compared to developed countries, Lebanon still suffers from a high prevalence and a wide spectrum of intestinal parasites.     

Chronic expectoration and risk of death in chronic obstructive lung disease

We wished to determine whether excess COPD-related mortality in subjects with chronic mucus hypersecretion (CMH) could be explained by proneness to pulmonary infection. Methods: 14,223 subjects of both sexes were followed for 10-12 years. Deaths with COPD as underlying or contributory cause (n = 214) were included and if death occurred in hospital, hospital records were obtained when possible (n = 101). From information regarding increased or purulent mucus, fever, leucocytosis and chest X-ray during hospital admission, death was classified as caused by pulmonary infection (n = 38), not caused by pulmonary infection (n = 51), or unclassifiable (n = 12). Results: Of subjects reporting CMH, 54% died from pulmonary infection, whereas that was only the case for 28% of subjects without CMH (p < 0.01). Cox regression-analysis showed a strong inverse relationship between ventilatory function and COPD-related mortality. CMH was an independent predictor of death with pulmonary infection implicated (RR:3.5) but not of death without pulmonary infection (RR:0.9). Conclusion: COPD-patients with CMH are more likely to die from pulmonary infection than COPD-patients without CMH.     

Early monaural occlusion alters the neural map of interaural level differences in the inferior colliculus of the barn owl

Monaural occlusion during early life causes adaptive changes in the tuning of units in the owl's optic tectum to interaural level differences (ILD) that tend to align the auditory with the visual map of space. We investigated whether these changes could be due to experience-dependent plasticity occurring in the auditory pathway prior to the optic tectum. Units were recorded in the external nucleus of the inferior colliculus (ICx), which is a major source of auditory input to the optic tectum. The tuning of ICx units to ILD was measured in normal barn owls and in barn owls raised with one ear occluded. ILD tuning at each recording site was measured with dichotic noise bursts, presented at a constant average binaural level, 20 dB above threshold. The best ILD at each site was defined as the midpoint of the range of ILD values which elicited more than 50% of the maximum response. A physiological map of ILD was found in the ICx of normal owls: best ILDs changed systematically from right-ear-greater to left-ear-greater as the electrode progressed from dorsal to ventral. Best ILDs ranged from 13 dB right-ear-greater to 15 dB left-ear-greater and progressed at an average rate of 12 dB/mm. The representations of ILD were similar on both sides of the brain. In the ICx of owls raised with one ear occluded, the map of ILD was shifted in the adaptive direction: ILD tuning was shifted towards values favoring the non-occluded ear (the direction that would restore a normal space map). The average magnitude of the shift was on the order of 8-10 dB in each of 4 owls. In one owl, the mean shift in ILD tuning was almost identical on both sides of the brain. In another owl, the mean shift was much larger on the side ipsilateral to the occlusion than on the contralateral side. In both cases, the mean shifts measured in each ICx were comparable to the mean shifts measured in the optic tectum on the same sides of the brain. Thus, the adjustments in ILD tuning that have been observed in the optic tectum in response to monaural occlusion are almost entirely due to adaptive mechanisms that operate at or before the level of the ICx.     

Hydrogen embrittlement and fracture toughness of a titanium alloy with surface modification by hard coatings

The effect of hydrogen embrittlement on the fracture toughness of a titanium alloy with different surface modifications was investigated. Disk- shaped compact- tension specimens were first coated with different .hard films and then hydrogen charged by an electrochemical method. Glow discharge optical spectrometry (GDOS), scanning electron microscopy (SEM), and x- ray diffractometry (XRD) were applied to analyze the surface characteristics. The results revealed that fracture toughness of the as- received titanium alloy decreased with the increase of hydrogen charging time. Fracture toughness of the alloy after plasma nitriding or ion implantation, which produced a TiN _x layer, decreased as well, but to a lesser extent after cathodic charging. The best result obtained was for the alloy coated with a CrN film where fracture toughness was sustained even after hydrogen charging for 144 h. Obviously, the CrN film acted as a better barrier to retard hydrogen permeation, but it was at the sacrifice of the CrN film itself.     

An experimental study of the rate and dynamics of the progression of different foods through the digestive tract of the greater gerbil

The rate and dynamics of food movement over the digestive tract was studied with the use of solid markers and small fragments of colored plastic film, in five experimental groups of great gerbils kept on different diets (various combinations of concentrated and cellulose food). The concentrated food moves relatively uniformly over the digestive tract and is fully evacuated within 24-25 h. Addition of various plant objects rich in cellulose to the grain food and feeding of the gerbil on the cellulose food alone lengthened the period of food evacuation up to 50 h. This is due to food differentiation into rapidly and slowly moving portions (the latter are delayed in the prostomach and caecum).     

Cardiovascular stimulation induced by rapid increases in desflurane concentration in humans results from activation of tracheopulmonary and systemic receptors

BACKGROUND: It was hypothesized that stimulation of rapidly adapting airway receptors produces the transient (2-4 min) circulatory responses to rapid increases in desflurane concentrations greater than 6%. Accordingly, it was reasoned that increasing the concentration of desflurane in one lung, without altering the concentration of desflurane in systemic blood, should cause cardiovascular stimulation, whereas once the airway receptors had adapted to the stimulation, an initial increase in the systemic concentration of desflurane should have little effect. METHODS: After placement of a double-lumen endotracheal tube in four volunteers and establishment of a steady-state level of 4% desflurane in both lungs, the desflurane concentration was rapidly increased from 4% to 8% in one lung while decreasing it in the other, thereby obviating any increase in the systemic desflurane blood concentration (confirmed by analysis). After returning the desflurane end-tidal concentration to 4% in both lungs, this process was repeated for the contralateral lung thereby having exposed both lungs to 8% desflurane without increasing the systemic desflurane concentration. After returning desflurane concentration to 4%, it was increased in both lungs simultaneously to 8% and consequently in blood to 8% of an atm. RESULTS: Rapid increases in desflurane concentrations in either lung, but not blood, significantly increased heart rate (17 +/- 5 beats/min, mean +/- SE, P < 0.05) and mean arterial blood pressure (15 +/- 5 mmHg, P < 0.05), but a greater increase in heart rate (43 +/- 5 beats/min, P < 0.05) and mean arterial blood pressure (46 +/- 11 mmHg, P < 0.05) occurred when both lungs were exposed simultaneously to rapidly increased desflurane concentration for the second time within 90 min. This result did not differ from the increase occurring on another day when both lungs and blood were exposed for the first time that day to 8% desflurane (heart rate 40 +/- 7 beats/min, P = 0.8; mean arterial blood pressure 40 +/- 3 mmHg, P = 0.5). CONCLUSIONS: It was concluded that at least two sites respond to a rapid increase in desflurane concentrations greater than 6%: one site in the airways and/or lungs, and at least one other in a highly perfused tissue(s). The systemic site contributes more importantly.