阿魏酸钠对花生四烯酸代谢的影响

利用放射薄层方法测定兔血小板花生四烯酸代谢产物TXB₂,PGE₂和PGF_2α。用放射免疫法测定兔血小板TXB₂及主动脉6-keto-PGF_1α。阿魏酸钠(SF,0.1～3.2 mmol/L),抑制¹⁴C-花生四烯酸转化为TXB₂,呈剂量效应关系,IC₅₀为0.762 mmol/L。SF在较高浓度(0.8～3.2mmol/L)时亦抑制PGE₂,PGF_2α的生成。用放免法观察到,SF对血小板TXB₂和动脉壁6-keto-PGF_1α的生成均有抑制作用,对TXB₂的作用较强。结果提示,SF可抑制兔血小板和动脉壁环氧酶活性。     

TREK-1 channels do not mediate nitrergic neurotransmission in circular smooth muscle from the lower oesophageal sphincter

Background and purpose:

The ionic mechanisms underlying nitrergic inhibitory junction potentials (IJPs) in gut smooth muscle remain a matter of debate. Recently, it has been reported that opening of TWIK-related K⁺ channel 1 (TREK-1) K⁺ channels contributes to the nitrergic IJP in colonic smooth muscle. We investigated the effects of TREK-1 channel blockers on nitrergic neurotransmission in mouse and opossum lower oesophageal sphincter (LOS) circular smooth muscle (CSM).

Experimental approach:

The effects of TREK-1 channel blockers were characterized pharmacologically in murine and opossum gut smooth muscle using conventional intracellular and tension recordings.

Key results:

In LOS, L-methionine depolarized the resting membrane potential (RMP) but did not inhibit the nitrergic IJP. Cumulative application of theophylline hyperpolarized the RMP and inhibited the nitrergic IJP concentration dependently. The induced membrane hyperpolarization was prevented by pre-application of caffeine, but not by 1H-[1,2,4]oxadiazolo-[4,3-a]quinoxalin-1-one. 8-Br-cAMP significantly hyperpolarized membrane potential and increased the amplitude of the nitrergic IJP. In opossum LOS muscle strips, L-methionine increased resting tone but had no effect on nerve-mediated LOS relaxation. On the other hand, theophylline markedly inhibited tone. In CSM from mouse proximal colon, L-methionine caused modest inhibition of nitrergic IJPs.

Conclusions and implications:

TREK-1 channels were not involved in the nitrergic IJP in LOS CSM. Not only does L-methionine have no effect on the nitrergic IJP or LOS relaxation, but the effect of theophylline appears to be due to interruption of Ca²⁺-releasing pathways (i.e. caffeine-like effect) rather than via blockade of TREK-1 channels.     

Vacuum-assisted closure as a surgical assistant in life-threatening necrotizing fasciitis in children

Necrotizing fasciitis is a severe soft tissue infection that can involve skin, subcutaneous fat, fascia and muscle. It can result in devastating sequelae including tissue necrosis, sepsis, toxic shock syndrome, cardiopulmonary collapse and death. To control rapidly spreading necrosis, early diagnosis and aggressive surgical treatment with extensive radical debridement of the affected areas is necessary, as well as systemic administration of broad-spectrum antimicrobials and, very often, intensive care support.The subatmospheric negative pressure dressing has been previously used in acute and complex wounds management. The concept of using vacuum-assisted closure dressing as another management component is presented in the current article.     

Midfoot and Hindfoot Bone Marrow Edema Identified By Magnetic Resonance Imaging in Feet of Subjects With Diabetes and Neuropathic Ulceration Is Common but of Unknown Clinical Significance

OBJECTIVE

We conducted a retrospective cohort study assessing the prevalence and clinical and radiological outcome of remote areas of bone marrow edema on magnetic resonance imaging (MRI) in the feet of subjects with diabetes and neuropathic foot ulceration.

RESEARCH DESIGN AND METHODS

MRIs performed over 6 years looking for osteomyelitis associated with neuropathic lesions were assessed for remote areas of signal change.

RESULTS

Seventy MRI studies were assessed. Remote areas of signal change were present in 21 (30%) subjects, involved midfoot or hindfoot in 20 subjects, were associated with younger age and renal replacement therapy, and did not predict future Charcot neuroarthropathy or infection at that site. Repeat MRIs in 11 subjects with such areas found that none had progressed, six had improved, and two had resolved; in 29 subjects without such areas, five had developed new areas.

CONCLUSIONS

Bone marrow edema in the midfoot and hindfoot of subjects with diabetes and neuropathic lesions is common, often transient, and of unknown significance.We have previously described the value of magnetic resonance imaging (MRI) to assess for osteomyelitis in association with neuropathic foot lesions in subjects with diabetes whereby the MRI criteria for diagnosis require bone signal change to be in direct contiguity with signal change in the soft tissue adjacent to the area of ulceration (1). We have often incidentally observed hyperintensity on T2-weighted images, consistent with bone marrow edema, remote from the area of neuropathic ulceration (Fig. 1) that often involves the midfoot and hindfoot and is usually not associated with adjacent clinical or radiological signs of infection, clinical signs suggesting acute Charcot neuroarthropathy, or pain. We performed a retrospective cohort study to assess the prevalence of such remote areas of signal change and their subsequent clinical and radiological outcome.Open in a separate windowFigure 1Sagittal T2 fat-saturated magnetic resonance image shows remote areas of signal change in the talus and calcaneum (arrows).     

Withdrawing intra-aortic balloon pump support paradoxically improves microvascular flow

Introduction

The Intra-Aortic Balloon Pump (IABP) is frequently used to mechanically support the heart. There is evidence that IABP improves microvascular flow during cardiogenic shock but its influence on the human microcirculation in patients deemed ready for discontinuing IABP support has not yet been studied. Therefore we used sidestream dark field imaging (SDF) to test our hypothesis that human microcirculation remains unaltered with or without IABP support in patients clinically ready for discontinuation of mechanical support.

Methods

We studied 15 ICU patients on IABP therapy. Measurements were performed after the clinical decision was made to remove the balloon catheter. We recorded global hemodynamic parameters and performed venous oximetry during maximal IABP support (1:1) and 10 minutes after temporarily stopping the IABP therapy. At both time points, we also recorded video clips of the sublingual microcirculation. From these we determined indices of microvascular perfusion including perfused vessel density (PVD) and microvascular flow index (MFI).

Results

Ceasing IABP support lowered mean arterial pressure (74 ± 8 to 71 ± 10 mmHg; P = 0.048) and increased diastolic pressure (43 ± 10 to 53 ± 9 mmHg; P = 0.0002). However, at the level of the microcirculation we found an increase of PVD of small vessels <20 μm (5.47 ± 1.76 to 6.63 ± 1.90; P = 0.0039). PVD for vessels >20 μm and MFI for both small and large vessels were unaltered. During the procedure global oxygenation parameters (ScvO₂/SvO₂) remained unchanged.

Conclusions

In patients deemed ready for discontinuing IABP support according to current practice, SDF imaging showed an increase of microcirculatory flow of small vessels after ceasing IABP therapy. This observation may indicate that IABP impairs microvascular perfusion in recovered patients, although this warrants confirmation.     

MOTOR RESTLESSNESS

Motor restlessness, characterised by an irresistible urge to move about, can be a manifestation of many underlying disorders. Unfortunately, it is often poorly recognised and underdiagnosed in clinical practice, possibly because patients do not seek medical attention, or their complaints were thought to be secondary to anxiety. While the two major conditions to consider are restless legs syndrome and neuroleptic-induced akathisia, there are many other differential diagnoses. We provide a concise review of the clinical features and diagnostic pitfalls of these conditions. A proper detailed clinical history and examination can often help clinch the diagnosis, as most of these conditions have their unique clinical features.