Assessment of pharyngeal airway stability in normal and micrognathic infants

A current hypothesis for obstructive sleep apnea states that 1) negative airway pressure during inspiration can collapse the pharyngeal airway, and 2) neural control of pharyngeal airway-dilating muscles is important in preventing this collapse. To test this hypothesis we performed nasal mask occlusions to increase negative pharyngeal airway pressures during inspiration in eight normal and five micrognathic infants. Both groups developed midinspiratory pharyngeal obstruction, but obstruction was more frequent in micrognathic infants and varied in some infants with sleep state. The airway usually reopened with the subsequent expiration. The occasional failure to reopen was presumably due to pharyngeal wall adhesion. If airway obstruction occurred in sequential breaths during multiple-breath nasal mask occlusions in normal infants, there was a breath-by-breath change in the airway pressure associated with airway closure (airway closing pressure); the airway closing pressure became progressively more negative. Micrognathic infants showed less ability to improve the airway closing pressure, but this ability increased with age. These findings suggest that nasal mask occlusion can test the competence of the neuromuscular mechanisms that maintain pharyngeal airway patency in infants. Micrognathic infants had spontaneous midinspiratory pharyngeal airway obstructions during snoring. Their episodes of obstructive apnea began with midinspiratory pharyngeal obstruction similar to that seen during snoring and nasal mask occlusions. These findings imply a similar pathophysiology for snoring, spontaneous airway obstruction, and obstruction during snoring.     

Circadian Rhythms in Competitive Sabre Fencers: Internal Desynchronization and Performance

During a 7-10 day span, circadian rhythms of sleep-wake, self-rated fatigue and mood, oral temperature, eye-hand skill and right and left hand grip strength were investigated in eight subjects: five males (21-28 years of age), members of the French sabre fencing team selected for the 1984 Olympic Games in Los Angeles, and three females (19-26 years of age) practicing fleuret (foil) fencing as a sports activity. On the average six measurements/day/variable/subject were performed. The single cosinor method showed that a circadian rhythm was detectable for only 26 out of the 56 time series (46.4%). Power spectrum analysis gave almost the same figure (19 out of 48: 39.5%) with regard to rhythms with τ=24hr indicating that with one exception (subject JFL) rhythms were internally desynchronized including differences τ between right and left hand grip strength rhythms for three subjects. Results suggest: (a) a physiologic synchronization of circadian rhythms may be a predictor of good performance; (b) however, internal desynchronization as shown previously may be a trivial phenomenon and thus does not imply in itself alterations of either health or performance; (c) chronobiologic methods should be recommended for a better understanding of changes in performance by those participating in competitive and other sports.     

Temporal Patterns of Reported Single-Vehicle Car and Truck Accidents in Texas, U.S.A. During 1980-1983

Reported single car and truck accidents due specifically to driver 'fatigue' for the 4-year span of 1980-1983 were analyzed for 24-hr, 7-d and 1-yr patterns. Three types of data were examined: (1) accidents in rural Texas, (2) accidents only in San Antonio, the fourth largest city in Texas and (3) accident ratio (number of accidents per time interval divided by traffic volume for the interval) in this city.

A statistically significant seasonal variation of relatively low amplitude with peaks in May and July was detected only for accidents in rural areas. High-amplitude periodicities of 7 d were evident in all the data sets, with a peak on the weekend. A very prominent 24-hr pattern was detected as well, with the acrophase determined by single cosinor around 0300. A slight secondary peak in accidents, around 1500, was evident in the data from the rural areas. This secondary peak represented a 12-hr rhythm in addition to the 24-hr. Overall, features of the temporal patterns in accidents over 24 hr and over the year in urban and rural areas differed only slightly. Accident ratios yielded results similar to accident frequencies. However, with regard to the rural data, the shape of the 24-hr temporal pattern varied with driver age; older drivers exhibited a flatter curve with a more pronounced afternoon rather than early morning (around 0300) peak.     

Comparison of the antiemetics metoclopramide and promethazine in labour.

A double blind trial was conducted in 477 mothers in labour to compare the antiemetics metoclopramide 10 mg and promethazine 25 mg and placebo when added to the first dose of pethidine. Metoclopramide and promethazine were equally effective, and both better than placebo, in reducing the incidence of nausea and vomiting after the administration of pethidine. Seventy seven per cent of mothers were drowsy, and 8% slept in the hour after the pethidine injection, with no difference between the groups. The sedative effect was more persistent in the promethazine group, 66% of whom were still drowsy after delivery. One third of the mothers in each group needed further analgesia, with 77% of these ultimately requesting an epidural. The reduction in pain half an hour and one hour after pethidine, assessed by a visual analogue scale, were, respectively, 22% and 22% for placebo; 26% and 23% for metoclopramide; 13% and 9% for promethazine. Analgesia after metoclopramide was significantly better than that after promethazine in terms of pain score, duration of first injection, and need for Entonox. Metoclopramide is therefore to be preferred to promethazine as an antiemetic in labour.     

Migration of peripheral T and B cells into the thymus of aging (NZB × SJL)F1 female mice

Aging NZB × SJL (NS) female mice provide a unique model of thymopathology characterized by the intrathymic accumulation of large numbers of mature T and B cells. The purpose of the present work was to examine the possibility that this phenomenon results from the invasion of the thymus by cells from the periphery. Lymphoid cells labeled with chromium-51 or indium-111 were injected into syngeneic recipients to study their patterns of in vivo migration. Lymph node (LN) or spleen cells were found to localize significantly (1–2% of injected radioactivity) into the thymus of 12-month-old NS females but not into that of young recipients or of old NS males. However, intrathymic localization of injected LN cells was observed in castrated NS males which exhibit the same thymopathology as NS females. Both radiolabeled T and B cells were found to enter the thymus of aged NS females but the latter cells about three times less efficiently than the former. Moreover, while thymocytes from young NS females were unable to recirculate to LN, those of old NS females showed increased LN-seeking capacity and part (1%) of them did migrate back into the thymus of old but not young NS females. In additional cell transfer experiments, the intrathymic migration of B cells into old NS females was further documented by using the antibody response to sheep erythrocytes as a tracer. Taken together, these observations indicate that the thymus of aging NS female mice is permeable to recirculating lymphocytes, suggesting that at least part of the mature T and B cells detected in this thymus, are migrants from the periphery.     

125I] 3-quinuclidinyl 4-iodobenzilate: a high affinity, high specific activity radioligand for the M1 and M2-acetylcholine receptors

We have prepared a radioiodinated ligand which binds with high affinity to the muscarinic acetylcholine receptor (m-AChR). A derivative of 3-quinuclidinyl benzilate, [125I] labeled (R) 1-aza-bicyclo(2.2.2)oct-3-yl (R,S)-alpha-hydroxy-alpha-(4-[125I]iodophenyl)phenyl acetate (4- IQNB ) exhibits an affinity for the m-AChR from corpus striatum higher than that of (R) [3H] QNB. Additionally, [125I] 4- IQNB exhibits receptor selectivity for the M1 receptor since the affinity for the receptor from dog and rat heart is lower than that using dog or rat corpus striatum.     

Plant biomass and nutrient levels of a tropical macrophyte (Cyperus papyrus L.) receiving domestic wastewater

The aboveground biomass and nutrient content ofCyperus papyrus were determined in a small tropical swamp receiving domestic wastewater. It was found that the biomass (4,955 g.m^–2 dry weight) was the highest ever reported for papyrus. The levels of both nitrogen and phosphorus in the plant organs were very high. The nitrogen concentrations of the various plant organs were 4.8% roots, 8.4% rhizomes, 4.5% scales, 4.8% culms, and 6.2% umbels on dry weight basis. As to phosphorus the concentrations were 0.09% roots, 0.11% rhizomes, 0.09% scales, 0.10% culms, and 0.13% umbels. The high biomass and nutrient contents of the plants may have been caused by the high nutrient levels in the surrounding water. Comparison of the nitrogen to phosphorus ratios in the plants to those in the surrounding water showed that the plants stored very high amounts of nitrogen.     

Acute effect of cigarette smoke on laryngeal receptors

Upper airway exposure to cigarette smoke elicits reflex changes in breathing pattern. To examine whether laryngeal afferents are affected by cigarette smoke, neural activity was recorded from the peripheral cut end of superior laryngeal nerve in anesthetized dogs. A box-balloon system, connected to the breathing circuit, allowed smoke to be inhaled spontaneously through the isolated upper airway while preserving its normal respiratory flow and pressure. Our results showed the following. Inhalation of cigarette smoke (25-50% concentration, 300-400 ml) caused a marked increase in activity of laryngeal irritant receptors which were either silent or randomly discharging during control breathing [their activity increased from a control value of 1.67 +/- 0.50 (mean +/- SE; n = 21) to a peak of 5.03 +/- 0.85 impulses/s in 11-15 s]. The activity of laryngeal cold receptors was reduced to 77.3 and 63.8% of control (n = 9) during the two breaths of smoke inhalation, respectively. After returning toward the base-line activity, a more pronounced inhibition (26.3% of control) occurred at three to nine breaths after the smoke inhalation. A small but significant decrease (88.5% of control) in the inspiratory discharge of laryngeal mechanoreceptors was observed during the first test breath. These effects were independent of the CO2 content of the smoke. Furthermore, there was no difference between the responses of these laryngeal afferents to high- and low-nicotine cigarette smoke.     

Binding properties and biological potencies of insulin-like growth factors in L6 myoblasts.

Protein synthesis in rat L6 myoblasts is stimulated and protein breakdown inhibited in a co-ordinate manner by insulin-like growth factors (IGF) or insulin. For both processes, bovine IGF-1 was somewhat more potent than human IGF-1, which was effective at a tenth the concentration of insulin, rat IGF-2 or human IGF-2. A similar order of potency is noted when DNA synthesis or protein accumulation is monitored over a 24 h period, but between 20- and 50-fold higher concentrations of each growth factor are required than those needed to produce effects in the 4 h protein-synthesis or -breakdown measurements. Binding experiments with labelled human or bovine IGF-1 as ligand demonstrated competition at concentrations of IGF-2, especially human IGF-2, lower than that of either IGF-1 preparation. This pattern was much more pronounced when the radioligand was either human IGF-2 or rat IGF-2. Insulin competed 10-15% for the binding of labelled IGF-1, but not at all with labelled IGF-2. Ligand-receptor cross-linking experiments showed that labelled bovine IGF-1 bound approximately equally to the type 1 IGF receptor (Mr 130000 after reduction) and to the type 2 IGF receptor (Mr 270000 after reduction), and that unlabelled IGF-1 competed equally with radioligand binding to both receptors. On the other hand, rat IGF-2 competed more effectively for binding to the type-2 receptor, and insulin competed only for binding to the type-1 receptor. Further cross-linking experiments with rat IGF-2 as radioligand demonstrated binding only to the type-2 receptor and to proteins with Mr values after reduction of 230000 and 200000. This binding was prevented by high rat IGF-2 concentrations, less effectively by bovine IGF-1 and not at all by insulin. The apparently conflicting biological potencies and receptor binding of the different growth factors can be explained if all the biological actions are mediated via the type-1 IGF receptor, rather than through the abundant type-2 receptor.