耐力训练过程中大鼠体内糖储备及胰岛激素变化与黄芪、生脉穴位注射的干预效应

目的:穴位注射疗法在临床应用较多,但在运动医学领域研究不多。观察穴位注射黄芪、生脉对耐力训练大鼠糖储备和运动能力的影响。方法:实验于2004-07在陕西师范大学完成。①实验分组:健康雄性SD大鼠32只,体质量180～220g,随机抽签法分为安静对照组、训练对照组、生理盐水组、药物注射组,每组8只。②实验方法:建立穴位注射黄芪、生脉大鼠的耐力跑台训练实验模型,安静对照组安静笼饲养。训练对照组、生理盐水组、药物注射组先于动物跑台上进行5周适应性训练,之后跑速每周递增,5d/周,共5周;然后进行2周的大强度耐力训练,30min/d,7d/周,共2周。训练对照组、生理盐水组、药物注射组第8周第1天以速度为35m/min运动至力竭。③实验评估:7周后取材测定肝糖原、肌糖原、血清胰岛素、胰高血糖素的变化。实验中对动物处置符合动物伦理学标准。结果:纳入大鼠32只,均进入结果分析。①通过大强度耐力训练,药物注射组与其他3组相比,肝糖原含量均升高(P<0.05);训练对照组肌糖原比安静对照组降低(P<0.05),生理盐水组与训练对照组相比则显著性升高(P<0.01)。②训练对照组胰岛素比安静对照组明显降低(P<0.01);生理盐水组及药物注射组都能抑制这种降低的趋势(P<0.01);药物注射组胰高血糖素较安静对照组、训练对照组要高,且有显著性差异(P<0.01)。结论:穴位注射黄芪、生脉使大强度耐力训练大鼠体内糖储备显著增加,同时可以提高胰岛激素水平,从而提高了大鼠的运动能力。     

Blood usage in lung transplantation

BACKGROUND: Few published data are available regarding perioperative blood usage in lung transplantation. STUDY DESIGN AND METHODS: The medical records of all patients undergoing lung transplantation at a university medical center in 1994 and 1995 were reviewed. RESULTS: Ninety patients underwent lung transplantation during this period. Six patients were excluded: two received a living related-donor lung, three underwent retransplantation and one underwent concomitant repair of a tetralogy of Fallot. Of the 84 evaluable patients, 59 underwent single lung transplantation and 25 double lung transplantation. Double-lung recipients used more red cells (6.4 vs. 1.7 units, p = 0.0002) and were more likely to receive red cells, platelets, plasma, or any component (92 vs. 32%, p< or =0.0001) than were single-lung recipients. Double- lung recipients were more likely to require cardiopulmonary bypass (40 vs. 12%, p = 0.003), and cardiopulmonary bypass was associated with greater transfusion requirements (p< or =0.0001). However, among patients requiring cardiopulmonary bypass, blood use did not differ between those undergoing double lung transplantation and those undergoing single lung transplantation. In the subset of patients not requiring cardiopulmonary bypass, double-lung recipients received more red cells (4.5 vs. 0.7 units, p< or =0.0001) and more plasma (2.0 vs. 0.2 units, p = 0.006). CONCLUSION: Double-lung recipients require more perioperative transfusions than single-lung recipients. The greater transfusion requirement is due to the more frequent need for cardiopulmonary bypass as well as the greater complexity of the procedure. These data are useful for developing surgical blood ordering guidelines for lung transplantation.     

5-Aminosalicylic acid (mesalazine) use in Crohn's disease: a survey of the opinions and practice of Australian gastroenterologists

BACKGROUND: The use of 5-aminosalicylate (5-ASA) drugs in Crohn's disease (CD) is controversial, with their continuing apparent widespread use despite high-level evidence indicating marginal benefit at best and international guidelines recommending limited indications. METHODS: In order to understand how clinicians translate the evidence base into clinical practice, we surveyed a cross-section of Australian gastroenterologists to determine opinions and prescribing patterns of 5-ASA drugs in CD. RESULTS: In all, 42% of 285 gastroenterologists who were sent a questionnaire by e-mail responded. Five (4%) never use 5-ASA drugs in CD. The drugs are most commonly prescribed for patients with colonic (96%) or ileocolonic (92%) disease location, inflammatory disease behavior (80%), and mild disease activity (97%). The majority (64%) use a dose of 1-3 g/day, but only 6% use over 4.5 g/day. Less than one-half use 5-ASA drugs as maintenance following surgical resection, but most use it for inducing remission alone (70%) or in combination with other drugs (90%), and continue its use for maintenance. Side effects are thought to be infrequent (62%) or rare (20%) and few common side effects are believed to be serious. Respondents estimated that over 90% of patients were nonadherent to prescribed 5-ASA regimens at least 50% of the time. While 84% believed that 5-ASA drugs were effective in CD, only 58% believed that they were cost-effective. CONCLUSIONS: In Australia 5-ASA drugs are extensively prescribed for CD at relatively low doses without expectation of patient adherence. Current evidence and guidelines has had little apparent impact on clinical practice. The cost implications are considerable.     

Flavocoxid,a dual inhibitor of cyclooxygenase and 5-lipoxygenase,blunts pro-inflammatory phenotype activation in endotoxin-stimulated macrophages

Background and purpose:

The flavonoids, baicalin and catechin, from Scutellaria baicalensis and Acacia catechu, respectively, have been used for various clinical applications. Flavocoxid is a mixed extract containing baicalin and catechin, and acts as a dual inhibitor of cyclooxygenase (COX) and 5-lipoxygenase (LOX) enzymes. The anti-inflammatory activity, measured by protein and gene expression of inflammatory markers, of flavocoxid in rat peritoneal macrophages stimulated with Salmonella enteritidis lipopolysaccharide (LPS) was investigated.

Experimental approach:

LPS-stimulated (1 µg·mL⁻¹) peritoneal rat macrophages were co-incubated with different concentrations of flavocoxid (32–128 µg·mL⁻¹) or RPMI medium for different incubation times. Inducible COX-2, 5-LOX, inducible nitric oxide synthase (iNOS) and inhibitory protein κB-α (IκB-α) levels were evaluated by Western blot analysis. Nuclear factor κB (NF-κB) binding activity was investigated by electrophoretic mobility shift assay. Tumour necrosis factor-α (TNF-α) gene and protein expression were measured by real-time polymerase chain reaction and enzyme-linked immunosorbent assay respectively. Finally, malondialdehyde (MDA) and nitrite levels in macrophage supernatants were evaluated.

Key results:

LPS stimulation induced a pro-inflammatory phenotype in rat peritoneal macrophages. Flavocoxid (128 µg·mL⁻¹) significantly inhibited COX-2 (LPS = 18 ± 2.1; flavocoxid = 3.8 ± 0.9 integrated intensity), 5-LOX (LPS = 20 ± 3.8; flavocoxid = 3.1 ± 0.8 integrated intensity) and iNOS expression (LPS = 15 ± 1.1; flavocoxid = 4.1 ± 0.4 integrated intensity), but did not modify COX-1 expression. PGE₂ and LTB₄ levels in culture supernatants were consequently decreased. Flavocoxid also prevented the loss of IκB-α protein (LPS = 1.9 ± 0.2; flavocoxid = 7.2 ± 1.6 integrated intensity), blunted increased NF-κB binding activity (LPS = 9.2 ± 2; flavocoxid = 2.4 ± 0.7 integrated intensity) and the enhanced TNF-α mRNA levels (LPS = 8 ± 0.9; flavocoxid = 1.9 ± 0.8 n-fold/β-actin) induced by LPS. Finally, flavocoxid decreased MDA, TNF and nitrite levels from LPS-stimulated macrophages.

Conclusion and implications:

Flavocoxid might be useful as a potential anti-inflammatory agent, acting at the level of gene and protein expression.     

Role of Endothelium/Nitric Oxide and Cyclic AMP in Isoproterenol Potentiation of 17ß-Estradiol-Mediated Vasorelaxation

Background: Calcitonin gene-related peptide (CGRP) is known to have an extremely potent and prolonged vasodilator effect on the coronary arteries. Studies have shown that CGRP increased coronary blood flow and alleviated reperfusion injury in vitro. It is still unknown, however, whether exogenous CGRP has a protective effect on the reperfusion heart associated with cardiopulmonary bypass (CPB). Methods: An in vivo porcine model of CPB was established. Twenty pigs, 10 controls and 10 CGRP used animals (CGRP group), were performed a median sternotomy followed by a standard CPB. All the hearts were arrested for 45 minutes. In the CGRP group, 1mg/kg CGRP was added into the cardioplegia, and another 1mg/kg was reperfused just before the aortic cross-clamp was removed. In both groups, myocardial microvascular perfusion, coronary arterial microvessel diameter and microvessel blood flow were detected by a laser doppler flowmeter and a contact microscope with TV monitor on five consecutive time perioperatively. Result: Myocardial microvascular perfusion was significantly higher and coronary arterial microvessel diameter was larger in the CGRP group on every point of time of reperfusion compared to those in the control group. In the CGRP group, microvessel blood flow also improved significantly than that in the control group during reperfusion. Conclusion: CGRP improves myocardial microcirculation during cardiac ischemia-reperfusion associated with CPB and could become a new, potent myocardial protector.     

Ultra-protective tidal volume: how low should we go?

Applying tidal volumes of less than 6 mL/kg might improve lung protection in patients with acute respiratory distress syndrome. In a recent article, Retamal and colleagues showed that such a reduction is feasible with conventional mechanical ventilation and leads to less tidal recruitment and overdistension without causing carbon dioxide retention or auto-positive end-expiratory pressure. However, whether the compensatory increase in the respiratory rate blunts the lung protection remains unestablished.Further reducing tidal volumes beyond the standard 6 mL/kg is an appealing goal in patients with acute respiratory distress syndrome (ARDS) [1]. Such reduction could decrease the tidal stretch imposed on the lung, potentially attenuating further the ventilator-induced lung injury [2]. In fact, tidal volumes of less than 6.5 mL/kg and as low as 4 mL/kg were recently associated with increased survival in patients with ARDS [3]. One of the main obstacles to such a strategy is the potential for carbon dioxide (CO₂) retention and severe acidosis. To avoid this, specialized techniques, such as high-frequency oscillatory ventilation and extracorporeal CO₂ removal, have been previously tested with mixed results [4-6].In the previous issue of Critical Care, Retamal and colleagues proposed that lower tidal volumes could be used with conventional positive-pressure ventilation without leading to CO₂ retention [1]. A reduction in tidal volume from 6 to 4 mL/kg was feasible with a decrease in the instrumental dead space and an increase in the respiratory rate. In patients with ARDS, the dead space is a marker of disease severity [7]. Consequently, very low tidal volumes can be difficult to use in practice, especially in very sick patients, because the necessary increase in respiratory rate might cause significant auto-positive end-expiratory pressure (auto-PEEP). Luckily, patients with severe ARDS also tend to have low lung compliance [8], making their lungs inflate and deflate fast. Therefore, this restrictive ventilatory pattern allows the safe use of high respiratory rates without leading to significant auto-PEEP.Retamal and colleagues [1] should be congratulated for their careful design of the ventilator protocol in the 4 mL/kg phase, which allowed an effective CO₂ elimination. The bottom line is that if one decides to use very low tidal volumes with high respiratory rates, attention to the details is invaluable. First, the removal of any dispensable dead space, including substituting an external heated humidifier by the heat-moisture exchanger, is imperative. Second, the use of volume-controlled ventilation helps to keep short inspiratory times. Peak airway pressures may increase, but the preserved expiratory time guarantees low auto-PEEP and, consequently, low plateau pressures. For safety, plateau pressures and auto-PEEP should be measured periodically. Third, in selected cases with high recruitability, the alveolar dead space can be minimized through recruitment maneuvers and higher PEEP values. Finally, the use of a short end-inspiratory pause is encouraged to improve the CO₂ elimination [9]. These measures will improve the safety and optimize the CO₂ elimination of a strategy with very low tidal volumes, even with higher-than-normal respiratory rates.However, even successfully avoiding CO₂ retention, this strategy has yet to be proven effective in terms of further lung protection. We believe that two aspects should be taken into consideration. The first is whether the strategy attenuated the mechanisms of lung injury. The authors performed computed tomography scans in all patients at tidal volumes of both 4 and 6 mL/kg and showed that the amount of cyclic recruitment-derecruitment and hyperinflation decreased after reducing the tidal volume. Although the absolute reduction was small (less than 1% of the lung weight), this finding is suggestive of decreased injury per breath. The second aspect is that an increased respiratory rate can be injurious per se [10]. It would be important to know whether the compensatory increase of the respiratory rate blunted the protective effect per breath of the tidal volume reduction.This tradeoff was emphasized recently in a model of the energy delivered by the ventilator as a surrogate for the potential lung damage [11]. Decreases in tidal volume require disproportionate increases in respiratory rate to maintain alveolar ventilation, and so more energy can be delivered to the lungs even at reduced stress and strain per breath. Though purely theoretical, this hypothesis helps reconcile our expectation of a further protective effect of very low tidal volumes with the recent findings of harmful or null effect of oscillatory high-frequency ventilation [5,6]. In these trials, it is possible that the reduction in lung injury per breath was offset by the very high respiratory rates applied.Finally, Retamal and colleagues [1] followed their patients for 5 to 30 minutes only. Since lower tidal volumes tend to promote atelectasis, especially under insufficient PEEP [12], a longer observation time perhaps would have shown an increase in atelectasis and driving pressures, opposing the benefits initially achieved.In conclusion, we are convinced that a strategy with very low tidal volumes (4 mL/kg) is feasible with conventional positive-pressure ventilation. This strategy could be used in patients with high plateau pressures or high driving pressures with standard 6 mL/kg tidal volumes, but we need more data in terms of lung protection before we can recommend this strategy to every patient with ARDS.     

Neonatal treatment with 192 IgG-saporin produces long-term forebrain cholinergic deficits and reduces dendritic branching and spine density of neocortical pyramidal neurons

The role of basal forebrain-derived cholinergic afferents in the development of neocortex was studied in postnatal rats. Newborn rat pups received intraventricular injections of 192 IgG-saporin. Following survival periods ranging from 2 days to 6 months, the brains were processed to document the cholinergic lesion and to examine morphological consequences. Immunocytochemistry for choline acetyltransferase (ChAT) and in situ hybridization for ChAT mRNA demonstrate a loss of approximately 75% of the cholinergic neurons in the medial septum and nucleus of the diagonal band of Broca in the basal forebrain. In situ hybridization for glutamic acid decarboxylase mRNA reveals no loss of basal forebrain GABAergic neurons. Acetylcholinesterase histochemistry demonstrates a marked reduction of the cholinergic axons in neocortex. Cholinergic axons are reduced throughout the cortical layers; this reduction is more marked in medial than in lateral cortical areas. The thickness of neocortex is reduced by approximately 10%. Retrograde labeling of layer V cortico-collicular pyramidal cells reveals a reduction in cell body size and also a reduction in numbers of branches of apical dendrites. Spine densities on apical dendrites are reduced by approximately 20-25% in 192 IgG- saporin-treated cases; no change was detected in number of spines on basal dendrites. These results indicate a developmental or maintenance role for cholinergic afferents to cerebral cortical neurons.