Role of preoperative carbohydrate loading: a systematic review

INTRODUCTION

Surgical stress in the presence of fasting worsens the catabolic state, causes insulin resistance and may delay recovery. Carbohydrate rich drinks given preoperatively may ameliorate these deleterious effects. A systematic review was undertaken to analyse the effect of preoperative carbohydrate loading on insulin resistance, gastric emptying, gastric acidity, patient wellbeing, immunity and nutrition following surgery.

METHODS

All studies identified through PubMed until September 2011 were included. References were cross-checked to ensure capture of cited pertinent articles.

RESULTS

Overall, 17 randomised controlled trials with a total of 1,445 patients who met the inclusion criteria were identified. Preoperative carbohydrate drinks significantly improved insulin resistance and indices of patient comfort following surgery, especially hunger, thirst, malaise, anxiety and nausea. No definite conclusions could be made regarding preservation of muscle mass. Following ingestion of carbohydrate drinks, no adverse events such as apparent or proven aspiration during or after surgery were reported.

CONCLUSIONS

Administration of oral carbohydrate drinks before surgery is probably safe and may have a positive influence on a wide range of perioperative markers of clinical outcome. Further studies are required to determine its cost effectiveness.     

Coronary calcification and its association with mortality in haemodialysis patients

Aim:   Coronary artery calcification (CAC) has been associated with higher mortality in chronic renal disease. The purpose of this study was to assess coronary artery calcium score (CaCs) in haemodialysis patients and to correlate calcium scores with clinical parameters and mortality.
Methods:   A cross-sectional study was conducted in 59 haemodialysis patients. CaCs was assessed by multidetector-row computed tomography and stratified as: CaCs of less than 10 Agatston units (U), no calcification; CaCs of 10–400 U, mild-to-moderate; and CaCs of more than 400 U, severe calcification. The effects of age, haemodialysis duration and biochemical and inflammatory markers on CaCs logarithm were evaluated by multiple linear regression analysis. Cox regression analysis was used to measure the impact of CaCs of more than 400 on 2-year mortality.
Results:   Coronary calcifications were detected in 64.5% of patients, and the median of CaCs was 31.7 U (0–589.7) with a range of 0–5790.0 U. Twenty-one (35.5%) patients had mild-to-moderate and 17 (29%) severe CaCs. Patients with severe CaCs were older and showed a higher prevalence of ischaemic heart disease and a higher body mass index ( P  = 0.04). A trend towards higher C-reactive protein levels was found in patients with severe CaCs. Advanced age was the only variable that influenced CaCs logarithm independently. The effect of severe CaCs on 2-year mortality did not persist after adjustment for other covariates.
Conclusion:   Coronary calcification was highly prevalent in these uraemic patients on chronic haemodialysis. A correlation was evidenced between CaCs and advanced age, but severity of the CAC score did not have an impact on 2-year mortality of this cohort.     

Chemoattractant-induced changes in surface expression and redistribution of a functional ligand for P-selectin on neutrophils

Adhesion between platelets and neutrophils is mediated through the interaction of P-selectin on activated platelets with a carbohydrate- containing structure on neutrophils, and occurs under both static and shear conditions. Recent studies using flow chambers have shown that neutrophils become activated after binding to surface-adherent platelets expressing P-selectin. The objective of the present study was to investigate the effect of such activation on the interactions of platelet P-selectin with its ligand on neutrophils. Flow cytometric analyses using P-selectin chimeras revealed that activation induced a rapid and marked reduction in chimera binding, with levels of binding decreased by 71% after 15 minutes of stimulation with the chemotactic agent, FMLP. Using a visual assay of platelet-neutrophil rosetting, we showed that the P-selectin ligand was translocated and clustered at the uropod of neutrophils following the shape changes and polarization induced by chemotactic stimulation. Activated neutrophils bound to surface-adherent platelets also displayed the clustering of P-selectin ligand at the uropod, and these neutrophils detached from the platelets when a shear stress (2 dynes/cm2) was applied through the adhesion chamber. These results indicate that chemotactic stimulation of neutrophils induces changes in the surface expression and distribution of a biologically relevant ligand for P-selectin, and that these changes might influence the adhesive interactions occurring between neutrophils and activated platelets.     

Peak oxygen uptake and ventilatory anaerobic threshold in fibromyalgia

OBJECTIVE: To compare maximum oxygen uptake and anaerobic threshold in patients with fibromyalgia (FM) and healthy sedentary controls matched by sex, age, weight, and body mass index. METHODS: Fifty women with FM aged 18-60 years and 50 healthy sedentary controls were studied. All were submitted to a maximum treadmill incremental test. Expired gas, ventilatory anaerobic threshold, and maximum oxygen uptake (VO2max) were evaluated. The influence of FM on quality of life was evaluated by questionnaires: the Fibromyalgia Impact Questionnaire and the Medical Outcomes Study Short-Form (SF-36). RESULTS: In patients with FM, the anaerobic threshold and peak oxygen uptake were significantly reduced. Maximum heartbeat rate was significantly lower in FM, indicating submaximum effort. Linear regression data showed a correlation between peak VO2 and the "Role-physical" domain of the SF-36. No such correlations were noted with anaerobic threshold. CONCLUSION: These results confirm the hypothesis of lower physical fitness in patients with FM. Considering that patients with FM do not achieve a maximum effort, ventilatory anaerobic threshold should be considered as a better fitness index than VO2max.     

Erythropoietin-specific cell cycle progression in erythroid subclones of the interleukin-3-dependent cell line 32D [published erratum appears in Blood 1993 Jun 1;81(11):3168]

Recently, a variety of growth factor-dependent subclones of the murine interleukin-3 (IL-3)-dependent cell line 32D have been isolated. These subclones include those dependent for growth on erythropoietin (Epo) (32D Epo), granulocyte-macrophage colony-stimulating factor (GM-CSF) (32D GM), or granulocyte colony-stimulating factor (G-CSF) (32D G). 32D Epo1.1 is a revertant of 32D Epo and is capable of growing in IL-3. These cell lines express the differentiation program appropriate to the specific growth factor and depend on the growth factors not only for proliferation but also for survival. To determine how the signal for proliferation is triggered by various growth factors, we examined the DNA histograms and the expression of cell cycle-specific genes in the different cell lines. The cell cycle-specific genes analyzed were myc (early G1), myb (late G1), and the structural genes for the calcium- binding protein 2A9 (middle G1) and histone H3 (G1-S boundary). The DNA histogram analysis of cells in the logarithmic phase of growth showed that approximately 40% of 32D, 32D GM, 32D G, and 32D Epo1.1 (growing in IL-3) were cells with a 2N DNA content (and therefore in G0/G1), and another 40% have a DNA content intermediate between 2N and 4N (in S phase). In contrast, 32D Epo and 32D Epo1.1 (growing in Epo) had fewer cells in the G0/G1 phase of the cell cycle compared with the number of cells that were in the S phase (19% to 31% v 69% to 78%, respectively). Because all the cell lines have comparable doubling times (15 to 18 hours), the cell distribution among the phases of the cell cycle is proportional to the length of the phase. Therefore, cells growing in IL- 3 (32D and 32D Epo1.1), GM-CSF (32D GM), or G-CSF (32D G) progress along the cycle in a manner typical of previously reported nontransformed cell lines. In contrast, cells growing in Epo (32D Epo or 32D Epo1.1) spend relatively less time in G0/G1 and correspondingly more time in S. These data were confirmed by the analysis of the tritiated thymidine (3H-TdR) suicide rate and of the expression of cell cycle-specific genes. The 32D and 32D Epo1.1 cells growing in IL-3 had a suicide rate of congruent to 50%, whereas the suicide rate of 32D Epo and 32D Epo1.1 growing in Epo was higher than 75%.(ABSTRACT TRUNCATED AT 400 WORDS)     

Proline at the P2 position in protein C is important for calcium- mediated regulation of protein C activation and secretion

Protein C is a vitamin K-dependent plasma serine protease zymogen, which upon activation, functions as an anticoagulant. Protein C activation is catalyzed by a complex of thrombin (T) with thrombomodulin (TM). This activation is Ca(2+)-dependent, but Ca2+ inhibits protein C activation by thrombin alone. In most proteases, specificity is determined primarily by the residues that lie near the scissile bond. In protein C, the P2 position is Pro, whereas in the fibrinogen A chain, P2 is Val. We have expressed a Pro-->Val mutant of protein C (P168V) in mammalian cells. At saturating Ca2+, the P168V and wild-type proteins were activated by the T-TM complex equivalently, but half maximal rates of activation were obtained at 50 mumol/L Ca2+ for wild type and approximately 5 mmol/L Ca2+ for the P168V mutant. In the absence of TM, Ca2+ no longer inhibited the activation of the P168V mutant. These results indicate that Pro168 influences the Ca(2+)- dependent conformational changes in protein C that control activation. Recently, a patient with thrombotic complications has been identified with a Pro168-->Leu substitution. Both the P168V and the P168L mutation lead to impaired secretion caused by retention within the cell.     

Facial nerve injury during temporal artery biopsy

Temporal artery biopsy is considered the gold standard investigation of giant cell arteritis and is recommended in suspected cases despite a sensitivity of 81–91%. This review highlights the potential risk of facial nerve injury during temporal artery biopsy and introduces recent advances in the emerging role of imaging modalities. When these non-invasive techniques are used in conjunction with American College of Rheumatology scoring, which includes clinical features and biochemical test results, temporal artery biopsy may be avoided in selected cases.     

Serology and ultrasound for diagnosis of choledocholithiasis

Introduction

Magnetic resonance cholangiopancreatography (MRCP) is not a routine investigation to exclude choledocholithiasis unless there is clinical or biochemical suspicion of common bile duct (CBD) stones. This study attempted to determine which radiological or serological parameters best predicted CBD stones.

Methods

All patients undergoing MRCP from 2005 to 2011 were selected. Patients with pancreatitis were excluded. Liver function tests (LFTs) at admission and prior to MRCP were recorded, as was abdominal ultrasonography and MRCP results. Parameters measured routinely on LFTs included alkaline phosphatase (ALP), alanine transaminase (ALT) and bilirubin. Receiver operating characteristic curve area analysis (area under the curve [AUC]) and chi-squared analysis were undertaken.

Results

Overall, 195 patients were identified, 71 of whom had CBD stones on MRCP. Raised ALP levels on admission demonstrated a correlation with CBD stones (AUC: 0.619, odds ratio [OR]: 3.16, p=0.06). At ultrasonography, a dilated CBD (OR: 3.76, p<0.001) and intrahepatic duct dilation (OR: 5.56, p<0.001) were highly significant predictors. However, only 37% of patients had a dilated CBD on ultrasonography. Ongoing elevation of LFT parameters, particularly ALP (AUC: 0.707, OR: 4.64, p<0.001) and ALT (AUC: 0.646, OR: 5.40, p<0.001), displayed a significant correlation with CBD stones.

Conclusions

Ongoing (even if minor) elevations of liver function test parameters should prompt the need to exclude CBD stones even in the presence of a normal CBD diameter on ultrasonography.     

Thrombin causes subsecond changes in protein phosphorylation of platelets

We have developed a general quenched-flow approach to study platelet function as early as 0.3 seconds after stimulation. Phosphorylation of 20- and 40-kd proteins has been analyzed during the first five seconds of platelet response to thrombin from 0.1 to 5.0 U/mL and compared with the progress of aggregation and serotonin secretion. The onset time for aggregation and phosphorylation of both proteins was less than one second, although with lowest (less than 0.5 U/mL) thrombin levels, a lag of up to 0.6 seconds occurred before 40K phosphorylation increased. The thrombin sensitivity of aggregation and 20K phosphorylation was approximately twice that of 40K phosphorylation, with Ka values of 0.51 and 0.53 v 1.10 U/mL, respectively. External calcium was necessary for maximal 20K phosphorylation, since EDTA inhibited this by 30%. The 40K phosphorylation was not affected by EDTA. Platelet activation by thrombin thus induced biochemical changes well before one second. The quenched-flow approach may help to reveal relationships between phospholipase activation, calcium fluxes, and protein phosphorylation during these early periods of platelet function.