青岛地区哺乳动物隐孢子虫感染调查

目的 了解青岛地区哺乳动物隐孢子虫感染状况及最佳检测方法.方法 收集青岛地区某些县(市)的猪、狗、猫及青岛大学医学院寄生虫学教研室实验用小鼠、大鼠、兔粪便388份,分别应用改良抗酸染色、金胺-酚染色、金胺-酚串联改良抗酸染色法检测隐孢子虫,并在生理盐水、饱和盐水及碘液中对隐孢子虫卵囊进行形态学观察.用腹泻儿童粪便中分离隐孢子虫卵囊感染2只幼犬,对其进行病原学和病理学观察.结果 哺乳动物隐孢子虫检出率为15.98%(62/388),其中家养动物猪、狗和猫隐孢子虫检出率分别为4.71%(8/170)、22.22%(10/45)和0(0/15),实验动物小鼠、大鼠和兔隐孢子虫检出率分别为31.03%(9/29)、40.00%(24/60)和15.94%(11/69).实验动物隐孢子虫检出率(27.85%)明显高于家养动物(7.86%)(χ2=27.965,P<0.01).人隐孢子虫卵囊感染幼犬后产生明显腹泻症状,粪便中查到隐孢子虫卵囊,大小形态与人株相似,肠壁病变明显.结论 在青岛地区哺乳动物中查出隐孢子虫感染,金胺-酚串联改良抗酸染色法效果最好.对甲醛液保存时间较长的粪便标本,金胺-酚染色法染色后,用体积分数0.03盐酸-乙醇脱色5 min,再用改良抗酸法染色,可提高卵囊检出率.隐孢子虫人株对狗无宿主特异性,并且具有明显致病性.     

Friction and lubrication of pleural tissues

The frictional behaviour of rabbit's visceral pleura sliding against parietal pleura was assessed in vitro while oscillating at physiological velocities and amplitudes under physiological normal forces. For sliding velocities up to 3 cm s(-1) and normal compressive loads up to 12 cm H2O, the average value of the coefficient of kinetic friction (mu) was constant at 0.019 +/- 0.002 (S.E.) with pleural liquid as lubricant. With Ringer-bicarbonate solution, mu was still constant, but significantly increased (Deltamu = 0.008 +/- 0.001; P < 0.001). Under these conditions, no damage of the sliding pleural surfaces was found on light and electron microscopy. Additional measurements, performed also on peritoneum, showed that changes in nominal contact area or strain of the mesothelia, temperature in the range 19-39 degrees C, and prolonged sliding did not affect mu. Gentle application of filter paper increased mu approximately 10-fold and irreversibly, suggesting alteration of the mesothelia. With packed the red blood cells (RBC) between the sliding mesothelia, mu increased appreciably but reversibly on removal of RBC suspension, whilst no ruptures of RBC occurred. In conclusion, the results indicate a low value of sliding friction in pleural tissues, partly related to the characteristics of the pleural liquid, and show that friction is independent of velocity, normal load, and nominal contact area, consistent with boundary lubrication.     

Dopamine1 receptor agonists reverse opioid respiratory network depression, increase CO2 reactivity

In adult pentobarbital-anesthetized and unanesthetized decerebrate cats, the D(1)R agonists (6-chloro-APB, SKF-38393, dihydrexidine) given intravenously restored phrenic nerve and vagus nerve respiratory discharges and firing of bulbar post-inspiratory neurons after the discharges were abolished by the micro-opioid receptor agonist fentanyl given intravenously. Reversal of opioid-mediated discharge depression was prevented by the D(1)R antagonist SCH23390. Iontophoresis of the micro-opioid receptor agonist DAMGO depressed firing of medullary bulbospinal inspiratory neurons. Co-iontophoresis of SKF-38393 did not restore firing and had no effect on bulbospinal inspiratory neuron discharges when applied alone. The D(1)R agonists given intravenously prolonged and intensified phrenic nerve and bulbospinal inspiratory neuron discharges. They also increased reactivity to CO(2) by lowering the phrenic nerve apnea threshold and shifting the phrenic nerve-CO(2) response curve to lower et(CO(2)) levels. Intravenous fentanyl on the other hand decreased CO(2) reactivity by shifting the phrenic nerve apnea threshold and the response curve to higher et(CO(2)) levels. Fentanyl effects on reactivity were partially reversed by D(1)R agonists.     

Unevenness of ventilation assessed by the expired CO(2) gas volume versus V(T) curve in asthmatic patients

Recently, we have shown that the expired CO2 gas volume versus tidal volume (VCO2-VT) curve is a useful tool for assessing unevenness of ventilation because it allows the separation of tidal volume into three functional compartments: (a) the CO2-free expired air (V0), (b) the transitional volume (Vtr), (c) the alveolar volume (VA) and the measurement of alveolar FCO2 during resting breathing in normal subjects and patients with COPD. In this paper, we have investigated whether changes pertaining to unevenness of ventilation taking place immediately after the administration of methacholine can be assessed using the VCO2-VT curve in asthmatic patients. The VCO2-VT curve was obtained during tidal breathing from 16 stable asthmatic patients who underwent a methacholine challenge test. It has been found that the Vtr, and hence Bohr's dead space (VD,Bohr = V0 + Vtr), over tidal volume ratios were significantly increased immediately after the methacholine administration, whilst the V0 over tidal volume ratio was not affected. The change of the above ratios was not related to the percentage decrease of FEV1.0 following methacholine administration.     

Tongue mechanical characteristics and genioglossus muscle EMG in obstructive sleep apnoea patients

The increased genioglossus muscle (GGm) activity seen in obstructive sleep apnoea syndrome (OSAS) may lead to increased fatigability or longer recovery time of the tongue. Maximal force, endurance, and recovery times of the tongue, electromyogram (EMG) absolute value, and EMG spectral analysis of the GGm obtained during submaximal contractions were compared in eight individuals without chronic snoring and eight OSAS patients. Endurance time values were not significantly different between the two groups (P = 0.40). Time to recovery of initial maximal force was significantly greater in the OSAS group (P = 0.01). Final EMG median frequency was significantly higher (P = 0.01) and the final low-frequency EMG component smaller in the OSAS patients (P = 0.02). Patients did not have changes in endurance time or fatigability but had longer recovery times and changes in spectral analysis variations. This functional investigation may be helpful in determining the presence of OSAS and the potential contribution of the tongue to pharyngeal obstruction.     

Oxygen uptake kinetics during high-intensity arm and leg exercise

The purpose of the present study was to examine the oxygen uptake kinetics during heavy arm exercise using appropriate modelling techniques, and to compare the responses to those observed during heavy leg exercise at the same relative intensity. We hypothesised that any differences in the response might be related to differences in muscle fibre composition that are known to exist between the upper and lower body musculature. To test this, ten subjects completed several bouts of constant-load cycling and arm cranking exercise at 90% of the mode specific V(O(2)) peak. There was no difference in plasma [lactate] at the end of arm and leg exercise. The time constant of the fast component response was significantly longer in arm exercise compared to leg exercise (mean+/-S.D., 48+/-12 vs. 21+/-5 sec; P < 0.01), while the fast component gain was significantly greater in arm exercise (12.1+/-1.0 vs. 9.2+/-0.5 ml min(-1) W(-1); P < 0.01). The V(O(2)) slow component emerged later in arm exercise (126+/-27 vs. 95+/-20 sec; P < 0.01) and, in relative terms, increased more per unit time (5.5 vs. 4.4% min(-1); P < 0.01). These differences between arm crank and leg cycle exercise are consistent with a greater and/or earlier recruitment of type II muscle fibres during arm crank exercise.     

Acute ventilatory and circulatory reactions evoked by nicotine: are they excitatory or depressant?

Either excitatory or inhibitory cardio-respiratory responses induced by nicotine have been reported. We evaluated the joint and separate contributions of peripheral arterial chemoreceptors and pulmonary vagal afferences to nicotine-induced cardio-respiratory responses in 11 pentobarbitone-anaesthetized cats. Nicotine, given i.v. in doses of from 1 to 200 microg/kg, evoked dose-dependent transient increases in tidal volume (VT) and arterial blood pressure (BP), but the highest doses evoked brief apnoea, immediately followed by intense hyperventilation, as well as discrete early hypotension followed by late hypertension. Bilateral section of the aortic and carotid nerves abolished all hyperventilatory responses to nicotine, giving way to apnoea followed by few cycles of reduced VT and profound hypotension followed by slight hypertension in response to intermediate doses (50-100 microg/kg). Subsequent bilateral vagotomy (BV) suppressed apnoeic and hypotensive responses. In other cats initially subjected to BV, only increases in VT and BP were observed in response to nicotine, effects which were no longer observed after additional carotid and aortic deafferentation. These data suggest that excitatory effects of nicotine on respiration and BP are reflexes evoked by stimulation of peripheral arterial chemoreceptors, while inhibitory effects are also reflex responses but evoked from stimulation of pulmonary vagal afferences.     

Numerical simulation of respiratory flow patterns within human lung

A computational fluid dynamics (CFD) modelling approach is used to study the unsteady respiratory airflow dynamics within a human lung. The three-dimensional asymmetric bifurcation model of the central airway based on the morphological data given by Horsfield et al. (J. Appl. Physiol. 67 (1971) 207) was used in the present study to simulate the oscillatory respiratory. The single bifurcation was found to be sufficient to give a number of results which both qualitatively and quantitatively agreed well with other published experimental and CFD results. Numerical simulation were made for two breathing conditions: (a) resting or normal breathing condition and (b) maximal exercise condition. The respiratory flow results for the both conditions are found strongly dependent on the convective effect and the viscous effect with some contribution of the unsteadiness effect. The secondary motions were stronger for the normal breathing condition as compared with the maximal exercise condition. The difference between the two cases is the flow separation regions found close to the carinal ridge for maximal exercise condition. For normal breathing condition no separation regions was observed in this region.     

Measurement of dyspnea: word labeled visual analog scale vs. verbal ordinal scale

We previously used a verbal ordinal rating scale to measure dyspnea. That scale was easy for subjects to use and the words provided consistency in ratings. We have recently developed a word labeled visual analog scale (LVAS) with labels placed by the subjects, retaining the advantages of a verbal scale while offering a continuous scale that generates parametric data. In a retrospective meta-analysis of data from 43 subjects, individuals differed little in their placement of words on the 100 mm LVAS (mean+/-S.D. for slight=20+/-2.5 mm, moderate=50+/-5 mm and severe=80+/-6 mm) and ratings were distributed uniformly along the scale. A significant stimulus-response correlation was obtained for both the LVAS (r(2)=0.98) and for the verbal ordinal scale (Spearman r=0.94). The resolution of the two scales differed only slightly. With meaningful verbal anchors, well-defined end-points, and clear instructions about the specific sensation to be rated, both scales provide valid measures of dyspnea.     

5-HT at hypoglossal motor nucleus and respiratory control of genioglossus muscle in anesthetized rats

Serotonin (5-HT) from medullary raphe neurons excites hypoglossal motoneurons innervating genioglossus (GG) muscle. Since some raphe neurons also show increased activity in hypercapnia, we tested the hypothesis that serotonergic mechanisms at the hypoglossal motor nucleus (HMN) modulate GG activity and responses to CO2. Seventeen urethane-anesthetized, tracheotomized and vagotomized rats were studied. Microdialysis probes were used to deliver mianserin (5-HT receptor antagonist, 0 and 0.1 mM) or 5-HT (eight doses, 0-50 mM) to the HMN during room air or CO2-stimulated breathing. Mianserin decreased respiratory-related GG activity during room air and CO2-stimulated breathing (P<0.001), and also suppressed GG responses to CO2 (P=0.05). In contrast, GG activity was increased by 5-HT at the HMN, and was further increased in hypercapnia (P<0.02). However, 5-HT increased respiratory-related GG activity at levels lower (1 mM) than those eliciting tonic GG activity (10-30 mM 5-HT). The results show that 5-HT at the HMN contributes to the respiratory control of GG muscle.