[Effect of preoperative anterior bony impingement on lateral collateral ankle ligament reconstruction]

Objective: To explore whether the combination of anterior bony impingement before surgery will affect the efficacy of the lateral collateral ankle ligament reconstruction surgery in patients with chronic ankle instability (CAI). Methods: A prospective cohort study. Patients with CAI who underwent lateral collateral ankle ligament reconstruction from January 2014 to October 2017 in the Department of Sports Medicine, Huashan Hospital, Fudan University were enrolled in this study. The patients were divided into no bony impingement group (NI group) and bony impingement group (BI group) according to the presence of bone impingement in front of the ankle during the operation. Preoperative American Orthopedic Foot and Ankle Society (AOFAS) score, Karlsson ankle functional socre (KAFS), Tegner score, visual analogue scale (VAS) of pain were extracted and were reevaluated at least 2 years after surgery as well as imaging evaluation of ankle. Results: A total of 59 patients were enrolled in this study. There were 29 patients in the NI group, 23 males and 6 females with a mean age of (28.4±7.1) years. And there were 30 cases in the BI group, 28 males and 2 females with a mean age of (31.9±8.6) years. The AOFAS, KAFS and Tegner scores in NI group increased from 65.8±10.6, 65.9±10.1 and 3.0 (3.0, 4.0) before the operation to 97.5±4.3, 97.8±4.7 and 6.0(5.0,6.0) after the operation, respectively; and the VAS decreased from 3.0(3.0, 4.0) to 0(0, 0); there were significant differences in those indexes before and after the operation (all P<0.05). The scores of AOFAS, KAFS and Tegner in BI group increased from 65.2±11.0, 64.2±10.0 and 3.0(3.0, 4.0) before the operation to 97.1±4.3, 97.3±4.3 and 5.0(4.0, 6.0) post the operation, respectively; and the VAS scores decreased from 3.0(3.0, 5.0) to 0(0, 1.0); there were significant differences in up-mentioned indexes before and after the surgery (all P<0.05). There was no significant differences in baseline and preoperative clinical function scores between the two groups (all P>0.05). No significant difference was found in postoperative AOFAS, KAFS and VAS scores between the two groups (all P>0.05), while postoperative Tegner score in the NI group was significantly higher than that in the BI group [6.0(5.0, 6.0) vs 5.0(4.0, 6.0), P=0.026]. Imaging evaluation of all patients showed that the reconstructed ligament was clearly visible, and the intraarticular injuries existing before surgery showed obvious signs of healing. Conclusion: Ankle lateral collateral ligament reconstruction for CAI with or without anterior bony impingement results in similar outcomes in ankle function, stability and pain levels.

[Correlation between serum CD147 and carotid intraplaque hemorrhage]

Objective: Intraplaque hemorrhage (IPH) is one of the most important causes of ischemic stroke. The purpose of this study was to explore the association between carotid IPH and CD147, which may be the serum marker related to IPH. Methods: Serum samples were collected from 68 patients with carotid artery stenosis from April to September 2004. 3.0T MRI with the 8 channel surface coil was used to scan carotid artery. Images was processed by MRI-PlaqueView. The integrity of lipid, IPH, calcified components and fibrous cap in the plaque was analysed qualitatively and quantitatively. The correlation and difference analysis among serum CD147 and plaque components were carried out. Results: Serum CD147 level in IPH positive was higher than that in IPH negative, 5 510.1 vs 4 648.0 (P=0.04). There was no significant correlation among serum CD147 and the quantitative parameters of lipid, IPH and calcification in carotid plaque and fibrous cap rupture. Serum CD147 in patients using statins was lower than that in patients not using statins, 4 914.0 vs 5 926.7 (P<0.01). Serum total cholesterol and LDL were positively correlated with serum CD147. In patients without statin, serum CD147 had a better diagnostic value for carotid IPH (AUC=0.81, P=0.04, 95% CI 0.62-0.99). Conclusion: Serum CD147 would probably be one biomarker of IPH and shows good diagnostic value of carotid IPH in the specific population.

Role of iron in lung injury-induced by hyperoxia

Iron is essential to life due to its unusual flexibility in serving as both an electron donor and acceptor. However, free iron can damage tissues by catalyzing the conversion of hydrogen peroxide to free-radical ions that attack lipids, proteins and DNA. Hyperoxia-induced lung injury (HILI) occurs when breathing elevated partial pressure of oxygen (usually > 0.5 atmospheres absolute) for extended periods. A few studies have shown that iron and proteins related to iron metabolism are closely related to HILI, and iron chelation may exert protective effects on HILI. As a rate-limiting enzyme in the degradation of heme, heme oxygenases (HOs) play a crucial role in the iron metabolism. Although some studies have been conducted to investigate the role of HOs in the pathogenesis of HILI, findings still conflict, and HOs of different isoforms may function differently in the pathogenesis of HILI. On the available findings, there might be a beneficial threshold of HO-1 expression in HILI. More studies are required to confirm the above findings and to provide evidence for the clinical treatment of HILI by iron chelation.

Current status of decompression illness in China: analysis of studies from 2001-2011

OBJECTIVE

To analyze the studies on decompression illness (DCI) in China in the past 10 years.

METHODS

We searched three Chinese databases and collected studies on DCI for further analysis. On the basis of findings, we proposed the issues on DCI in China.

RESULTS

There are more than 50,000 active divers in China, the majority of whom are fishing divers. Among them, the incidence of DCI is still at a high level because they have little or no knowledge of diving and diving medicine, the quality of diving equipment is poor, and divers generally do not follow the regulations of diving. There are few dive physicians in China, and the general clinicians have poor knowledge about, or pay little attention to, dive medicine. This might be the major cause of the poor quality of studies on DCI. There is no consensus in the classification of DCI and treatment tables for DCI treatment. These are factors affecting systemic review and further meta-analysis of available studies on DCI.

CONCLUSION

It is imperative to generalize knowledge in not only divers and diving-related practitioners but general practitioners as well.

Combined effects of intravenous perfluorocarbon emulsion and oxygen breathing on decompression-induced spinal cord injury in rats

The spinal cord is one of the most commonly affected sites in decompression sickness (DCS). Alternative methods have long been sought to protect against DCS spinal cord dysfunction, especially when hyperbaric treatment is unavailable. Use of perfluorocarbon (PFC) emulsion with or without oxygen breathing has shown survival benefits in DCS animal models. The effectiveness of intravenous PFC emulsion with oxygen breathing on spinal cord function was studied. Somatosensory-evoked potentials (SSEPs) and histologic examination were chosen to serve as measures. After fast decompression (203 kPa/minute) from 709 kPa (for 60 minutes), male Sprague-Dawley rats randomly received: 1) air and saline; 2) oxygen (O2) and saline; 3) O2 and PFC emulsion. The incidence and average number of abnormal SSEP waves in survival animals that received O2 and PFC emulsion were significantly reduced (P < 0.05). Foci of demyelination, necrosis and round non-staining defects in white matter regions of the spinal cord could be found in severe DCS rats. We concluded that administration of PFC emulsion combined with oxygen breathing was beneficial for DCS spinal conductive dysfunction in rats.

Hydrogen Therapy may be a Novel and Effective Treatment for COPD

The protective effect of hydrogen (H(2)) on ROS-induced diseases has been proved by many researches, which demonstrated that through eliminating •OH and •ONOO-, H(2) could effectively attenuate lipid and DNA peroxidation, improve cellular antioxidant capacity, and then protect cells against oxidant damage. Most of free radicals in human body are ROS, including O(2)•-,•OH, H(2)O(2), NO•,•ONOO-, and so on. Under normal circumstances cells are able to maintain an adequate homeostasis between the formation and removal of ROS through particular enzymatic pathways or antioxidants. But under some pathological conditions, the balance is disturbed, leading to oxidative stress and various diseases, such as chronic obstructive pulmonary disease (COPD). Studies have shown that ROS played a pivotal role in the development of COPD and some antioxidants were effective in the protection against the damaging effects of oxidative stress. Therefore, we hypothesize that owing to its peculiarity to eliminate toxic ROS, hydrogen therapy may be a novel and effective treatment for COPD.

Hyperbaric oxygen preconditioning reduces the incidence of decompression sickness in rats via nitric oxide

Divers are at risk of decompression sickness (DCS) when the ambient pressure decrease exceeds a critical threshold. Hyperbaric oxygen (HBO2) preconditioning has been used to prevent various injuries, but the protective effect on DCS has not been well explored. To investigate the prophylactic effect of HBO2 on DCS, rats were pretreated with HBO2 (250 kPa-60 minutes) (all the pressures described here are absolute pressure) for 18 hours before a simulated air dive (700 kPa-100 minutes) with fast decompression to the surface at the rate of 200 kPa/min (n=33). During the following 30 minutes, the rats walked in a 3 m/minute rotating cage and were monitored for signs of DCS. The control rats were pretreated with normobaric air (n=30), normoxic hyperbaric nitrox (250 kPa, 8.4% O2) (n=13), or N(G)-nitro-L-arginine methyl ester (L-NAME) 30 minutes before HBO2 exposure (n=13). Nitric oxide (NO) levels were recorded immediately and 18 hours after HBO2 exposure in the brain and spinal cord. The incidence of DCS in rats pretreated with HBO2 was 30.3%, which was significantly lower than those treated with normobaric air (63.3%) (p<0.05) or hyperbaric nitrox (61.5%) (p<0.05). The onset time of DCS of the rats pretreated with HBO2 was significantly delayed compared with those treated with air (p<0.05). L-NAME nullified the HBO2 preconditioning effect. HBO2 increased NO level in the rat brain and spinal cord right after exposure; this effect was inhibited by L-NAME. Taken together, HBO2 preconditioning reduced the incidence of DCS in rats, and NO was involved in the prophylactic effect.

Mechanism of ischemic tolerance induced by hyperbaric oxygen preconditioning involves upregulation of hypoxia-inducible factor-1α and erythropoietin in rats

We studied the effect of hyperbaric oxygen (HBO) preconditioning on the molecular mechanisms of neuroprotection in a rat focal cerebral ischemic model. Seventy-two male Sprague-Dawley rats were pretreated with HBO (100% O2, 2 atmospheres absolute, 1 h once every other day for 5 sessions) or with room air. In experiment 1, HBO-preconditioned rats and matched room air controls were subjected to focal cerebral ischemia or sham surgery. Postinjury motor parameters and infarction volumes of HBO-preconditioned rats were compared with those of controls. In experiment 2, HBO-preconditioned rats and matched room air controls were killed at different time points. Brain levels of hypoxia-inducible factor-1α (HIF-1α) and its downstream target gene erythropoietin (EPO) analyzed by Western blotting and RT-PCR as well as HIF-1α DNA-binding and transcriptional activities were determined in the ipsilateral hemisphere. HBO induced a marked increase in the protein expressions of HIF-1α and EPO and the activity of HIF-1α, as well as the expression of EPO mRNA. HBO preconditioning dramatically improved the neurobehavioral outcome at all time points (3.0 ± 2.1 vs. 5.6 ± 1.5 at 4 h, 5.0 ± 1.8 vs. 8.8 ± 1.4 at 8 h, 6.4 ± 1.8 vs. 9.7 ± 1.3 at 24 h; P < 0.01, respectively) and reduced infarction volumes (20.7 ± 4.5 vs. 12.5 ± 3.6%, 2,3,5-Triphenyltetrazolium chloride staining) after cerebral ischemia. This observation indicates that the neuroprotection induced by HBO preconditioning may be mediated by an upregulation of HIF-1α and its target gene EPO.

Therapeutic effects of hyperbaric oxygen in a rat model of endothelin-1-induced focal cerebral ischemia

It has been established that hyperbaric oxygen (HBO) treatment reduces brain edema, decreases infarct volume, contributes to neurological functional recovery and suppresses apoptosis in suture-induced focal cerebral ischemic animal models. In the present study, we evaluated the therapeutic effect of HBO in an endothelin-1-induced focal cerebral ischemia in rats and explored the associated mechanisms of HBO-induced brain protection. One hundred twenty male Sprague-Dawley rats (280 to 320 g) were randomly assigned to sham, focal cerebral ischemia and focal cerebral ischemia treated with HBO groups. Brain water content, neurological function, morphology and molecular biological markers were assessed. HBO (100% O2, 2.5 atmosphere absolute for 2 h) was initiated at 1 h after focal cerebral ischemia. Rats were killed at 24 h to harvest tissues for Western blot or for histology. In HBO-treated animals, an enhanced ratio of Bcl-2 and Bax and a reduced expression of hypoxia-inducible factor-1alpha (HIF-1alpha) in the hippocampus after focal cerebral ischemia were observed. These results indicate that HBO provides brain protection that is probably associated with the inhibition of HIF-1alpha and the elevation of Bcl-2.

Immune function in rats following repetitive exposures to 7 ATA air

INTRODUCTION

The precise action of the immunological effects associated with hyperbaric exposure is poorly understood. This study's goal was to clarify the effects and etiology of deep air dives on the immune response.

METHODS

Sprague-Dawley rats were exposed to 7-ATA air for 60 min twice daily for 3 consecutive days. Several markers of immune function, the degree of stress, and oxidative stress following or during the exposures were determined. Rats exposed to 1.47-ATA oxygen or 7-ATA nitrox (0.21-ATA oxygen + 6.79-ATA nitrogen) were taken as controls.

RESULTS

Peripheral lymphocytes and CD3+ and CD4+CD3+ subsets in peripheral blood and spleen, plasma interleukin-2 level, and the responses of splenic lymphocytes to concanavalin A all decreased, antioxidant enzyme activities and the concentration of reduced glutathione both decreased, while the level of malondialdehyde increased following hyperbaric air exposures. All changes returned to normal in 3-5 d. Similar changes were observed following exposures to 1.47-ATA oxygen, but not to normoxic nitrox. Plasma levels of adrenocorticotropic hormone and corticosterone increased after one exposure and recovered to normal levels after three exposures in rats treated with either hyperbaric or normobaric air. Pretreatment of the animals with N-acetylcysteine, a potent free radical scavenger and antioxidant attenuated the effects of hyperbaric air on immune and antioxidant systems.

CONCLUSIONS

These results are consistent with the hypothesis that repetitive exposure to 7-ATA air has a temporary immunosuppressive effect on rats, which is related to oxidative stress induced by the high partial pressure of oxygen in breathing gas.

Papulonecrotic tuberculid--a rare skin manifestation in a patient with pulmonary tuberculosis

Papulonecrotic tuberculid (PNT), a cutaneous manifestation of tuberculosis, is rare even in areas endemic for tuberculosis such as Taiwan. Concomitant pulmonary tuberculosis is uncommon in patients with PNT. We describe a patient with rare skin manifestations and simultaneous pulmonary tuberculosis. This 48-year-old woman had suffered from productive cough for 4 months, and pea-sized papules with central umbilication were noted over the extensor surface of her four extremities and lower abdomen 1 month prior to admission to our hospital. Chest roentgenography showed reticulonodular lesions with small cavitation over the lower right lung field, and sputum culture yielded Mycobacterium tuberculosis complex. PNT was diagnosed using the skin biopsy results and the papules healed with scar formation after antituberculous therapy.

Diaphragm mechanics in dogs with unilateral emphysema

We studied dogs with unilateral papain-induced emphysema to answer two questions: (1) Do emphysema lung-apposed hemidiaphragm (DiE) and normal lung-apposed hemidiaphragm (DiN) have equal capacities for lowering lung surface pressure? and (2) Are side-to-side differences in intrathoracic pressure the result of unequal force outputs by DiE and DiN or are they caused by differences in their mechanical efficiency as pressure generators? After the airways of the emphysematous and normal lungs were intubated with a dual lumen endotracheal tube, both phrenic nerves were maximally stimulated at rates between 1 and 50 Hz and the changes in airway occlusion pressure (delta PaoE,N) and diaphragm length (sonomicrometry) were recorded. In all animals, delta PaoN exceeded delta PaoE. Differences in pressure ranged from 1.2 +/- 0.6 cm H2O during a twitch to 6.0 +/- 2.9 cm H2O during a 50-Hz tetanus. Midcostal bundles of DiE shortened less than corresponding bundles of DiN, but both reached the same active length relative to their optimal lengths, which were measured in vitro. There was no significant difference in fiber type distribution, fiber cross-sectional area, or maximal isometric tetanic tensions among midcostal regions of DiE and DiN. We conclude that unilateral hyperinflation impairs the mechanical efficiency of the apposing hemidiaphragm as a pressure generator.

[Changes of Leu-enkephalin in striatum and hypothalamus of rats during hyperbaric oxygen exposure]

The purpose of this study is to investigate the changes of Leu-Enkephalin (L-Enk) content in striatum and hypothalamus of rats during hyperbaric (HBO) oxygen exposure. Thirty-two male rats in the experiment were randomly divided into four groups: normobaric air group, normoxic hyperbaric nitrox group, nonconvulsion HBO group and convulsion HBO group. L-Enk content in striatum and hypothalamus was determined by radioimmunoassay. The results show that L-Enk content in the striatum and hypothalamus of rats exposed to hyperbaric oxygen environment were markedly higher than that of rats exposed to normobaric air and normoxic hyperbaric nitrox. The experimental results suggest that the elevation of L-Enk content in striatum and hypothalamus shows a positive relationship with the HBO exposure duration of animals and that there was no marked relationship with normoxic hyperbaric nitrox environment and compression-decompression method.

Predictability of ventilatory muscle optimal length based on excised dimensions

The purpose of the present study was to assess the relationship between excised length (unstressed length of excised muscle; Lex) and optimal force-generating length (Lo) in a variety of respiratory muscles, with the goal of establishing a reliable method whereby Lo could be rapidly and easily estimated with a high level of accuracy. Experiments were conducted on 111 muscle bundles obtained from 18 mongrel dogs. Segments of costal diaphragm, parasternal intercostal, scalene, sternomastoid, triangularis sterni, rectus abdominis, external oblique, and transversus abdominis muscles were studied. We noted a linear relationship between the distance measured between two fixed points in excised bundles (Lex) and at the muscles' Lo. Correlation coefficients ranged from 0.83 (P less than 0.01) for the transversus abdominis to 0.92 (P less than 0.01) for the triangularis sterni and external oblique muscles. Pooled Lex for all muscles averaged 61.4 +/- 6.3% (SD) Lo, with specific values ranging from 55.5 +/- 3.9% Lo for triangularis sterni bundles to 63.0 +/- 5.1% Lo for external oblique bundles. In three additional dogs, we verified the usefulness of this relationship and prospectively estimated Lo from excised length in 10 costal diaphragm bundles and 10 transversus abdominis bundles and then measured Lo directly. Predicted Lo averaged 100.0 +/- 6.0% Lo for diaphragm and 97.6 +/- 5.9% Lo for transversus abdominis muscle. We conclude that Lo can be conveniently and accurately estimated from excised dimensions. This rapid estimation technique should prove valuable for future studies in respiratory muscle physiology.

Urinary ANP, ADH, and electrolyte excretion during saturation-excursion diving to pressures equivalent to 250 and 300 m

Four male divers were exposed to an environment of 26 and 31 atm abs He-O2 for 2 days. Urine was collected during the day (0700-1900 h) and at night (1900-0700 h) before (predive 1 atm abs air), during, and after (decompression and postdive 1 atm abs air) the exposure. Urine flow increased markedly and was mostly attributable to the urine flow during 1900-0700 h. The secretion of atrial natriuretic polypeptide (ANP) increased only at night during hyperbaria. On the other hand, the secretion of antidiuretic hormone (ADH) was suppressed, but increased during compression and the early phase of hyperbaric exposure before it decreased. Linear regression analysis showed that urinary excretion of ANP was correlated significantly with urine flow (r = 0.88, P less than 0.01) and that excretion of ADH negatively correlated with urine flow (r = -0.61, P less than 0.01). Urinary excretion of Na, Cl, Ca, and Mg increased significantly at night during hyperbaria, whereas there was no consistent change in the excretion of K and P. These results suggest that both stimulated ANP secretion and suppressed ADH secretion correlate with the increase of urine and that nocturia is mostly attributable to stimulated ANP secretion. We observed that urinary excretion of ANP increased significantly as early as during the compression phase, which suggested that ANP plays a decisive role in the early diuresis.

Mechanics of acutely shortened canine diaphragm muscle in vitro

Acute changes in lung volume, as might be seen in an airway-obstructed patient, may lead to different amounts of shortening of the various inspiratory muscles, of which the diaphragm is the most important. The purpose of this study is to investigate the twitch and contractile characteristics of acutely shortened canine diaphragm muscle in vitro during isometric contraction. We found that with diaphragmatic muscle shortening from Lo (optimal length, defined as being that length at which peak twitch tension was generated) to 70% Lo, the time-to-peak tension, half relaxation time and twitch tension were significantly reduced. The force-frequency curves, obtained from different muscle lengths, disclosed that shorter muscles generate disproportionately less force during low-frequency stimulation. These factors may, at least in part, contribute to the vulnerability to fatigue of those with shorter diaphragmatic muscle length.

Mechanical role of expiratory muscle recruitment during eupnea in supine anesthetized dogs

To assess the mechanical role of the expiratory musculature during eupnea, we recorded the electromyographic (EMG) activity of the triangularis sterni, the external oblique, and the transversus abdominis in eight supine lightly anesthetized dogs and have measured the volume generated by the phasic activation of the expiratory muscles. Activation of the expiratory muscles was invariably associated with a decrease in lung volume below the relaxed position of the respiratory system, a volume equal to 41.3 +/- 8.4 ml. This volume represented roughly 20% of tidal volume generated during spontaneous breathing. The fractional expiratory contribution to the tidal volume was unrelated to the size of the animal. Traction on the forelimbs (limb extension), however, tended to enhance the phasic expiratory activation of both the triangularis sterni and the transversus abdominis in the majority of animals. Moreover, after limb extension, the fractional contribution of tidal volume attributed to the phasic activation of the expiratory muscles increased in all but one animal. During spontaneous breathing with the forelimbs extended, roughly 25% of tidal volume was found to be due directly to phasic expiratory muscle contraction. The present observations firmly establish that in supine lightly anesthetized dogs breathing at rest the expiratory component of tidal volume represents a substantial contribution.