Peripheral neuropathy in chronic obstructive pulmonary disease

Associations between spirometric impairments and microvascular complications in type 2 diabetes: a cross-sectional study

OBJECTIVE

Evidence shows that the conventional cardiometabolic risk factors do not fully explain the burden of microvascular complications in type 2 diabetes (T2D). One potential factor is the impact of pulmonary dysfunction on systemic microvascular injury. We assessed the associations between spirometric impairments and systemic microvascular complications in T2D.

DESIGN

Cross-sectional study.

SETTING

National Diabetes Management and Research Centre in Ghana.

PARTICIPANTS

The study included 464 Ghanaians aged ≥35 years with established diagnosis of T2D without primary myocardial disease or previous/current heart failure. Participants were excluded if they had primary lung disease including asthma or chronic obstructive pulmonary disease.

PRIMARY AND SECONDARY OUTCOME MEASURES

The associations of spirometric measures (forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC) and FEV1/FVC ratio) with microvascular complications (nephropathy (albumin-creatinine ratio ≥3 mg/g), neuropathy (vibration perception threshold ≥25 V and/or Diabetic Neuropathy Symptom score >1) and retinopathy (based on retinal photography)) were assessed using multivariable logistic regression models with adjustments for age, sex, diabetes duration, glycated haemoglobin concentration, suboptimal blood pressure control, smoking pack years and body mass index.

RESULTS

In age and sex-adjusted models, lower Z-score FEV1 was associated with higher odds of nephropathy (OR 1.55, 95% CI 1.19-2.02, p=0.001) and neuropathy (1.27 (1.01-1.65), 0.038) but not retinopathy (1.22 (0.87-1.70), 0.246). Similar observations were made for the associations of lower Z-score FVC with nephropathy (1.54 (1.19-2.01), 0.001), neuropathy (1.25 (1.01-1.54), 0.037) and retinopathy (1.19 (0.85-1.68), 0.318). In the fully adjusted model, the associations remained significant for only lower Z-score FEV1 with nephropathy (1.43 (1.09-1.87), 0.011) and neuropathy (1.34 (1.04-1.73), 0.024) and for lower Z-score FVC with nephropathy (1.45 (1.11-1.91), 0.007) and neuropathy (1.32 (1.03-1.69), 0.029). Lower Z-score FEV1/FVC ratio was not significantly associated with microvascular complications in age and sex and fully adjusted models.

CONCLUSION

Our study shows positive but varying strengths of associations between pulmonary dysfunction and microvascular complications in different circulations. Future studies could explore the mechanisms linking pulmonary dysfunction to microvascular complications in T2D.

Electroencephalogram based brain-computer interface: Applications, challenges, and opportunities

Brain-Computer Interfaces (BCI) is an exciting and emerging research area for researchers and scientists. It is a suitable combination of software and hardware to operate any device mentally. This review emphasizes the significant stages in the BCI domain, current problems, and state-of-the-art findings. This article also covers how current results can contribute to new knowledge about BCI, an overview of BCI from its early developments to recent advancements, BCI applications, challenges, and future directions. The authors pointed to unresolved issues and expressed how BCI is valuable for analyzing the human brain. Humans' dependence on machines has led humankind into a new future where BCI can play an essential role in improving this modern world.

Chronic Hypoxemia Triggers a Neuropathic Process in Chronic Obstructive Pulmonary Disease: Insight From In Vivo Neurophysiological Assessments

BACKGROUND AND PURPOSE

Peripheral neuropathies (PNs) are a common but poorly understood complication of chronic obstructive pulmonary disease (COPD). To clarify the initial trigger of a PN in COPD, we investigated the excitability of peripheral nerves in patients with COPD.

METHODS

The automated nerve excitability test (NET) using the threshold-tracking paradigm was applied to 20 COPD patients. The recording protocol calculated the strength-duration time constant, threshold electrotonus (TE), current-threshold relationship, and recovery cycle (RC). Each NET parameter was compared with two control groups: normal controls group (NC group) and smokers without COPD group (smoker group).

RESULTS

In the motor NETs, the change in the threshold in the mid-depolarizing phase of TE (40-60 ms) was smaller in the COPD group (50.7%±1.2%, mean±SEM; n=20) than in the NC group (54.5%±0.7%, n=25; p<0.01), as was the prominence of superexcitability in the RC (-22.6%±1.5% and -26.4%±1.1%, respectively; p=0.04). There were no significant differences in the sensory NETs. Comparisons between the COPD and smoker groups (n=25) also showed no differences in either the motor or sensory NETs.

CONCLUSIONS

The pattern of excitability in COPD revealed a membrane depolarization attributable to Na⁺-K⁺-ATPase failure in the axolemma of distal motor nerves. This finding suggests that chronic hypoxemia and adaptative process can alter axonal excitability and trigger a resultant neuropathic process that is antecedent to PN in COPD.

Peripheral neuropathy: A neglected cause of disability in COPD - A narrative review

Chronic obstructive pulmonary disease (COPD) is a chronic inflammatory syndrome with systemic involvement leading to various cardiovascular, metabolic, and neurological comorbidities. It is well known that conditions associated with oxygen deprivation and metabolic disturbance are associated with polyneuropathy, but current data regarding the relationship between COPD and peripheral nervous system pathology is limited. This review summarizes the available data on the association between COPD and polyneuropathy, including possible pathophysiological mechanisms such as the role of hypoxia, proinflammatory state, and smoking in nerve damage; the role of cardiovascular and metabolic comorbidities, as well as the diagnostic methods and screening tools for identifying polyneuropathy. Furthermore, it outlines the available options for managing and preventing polyneuropathy in COPD patients. Overall, current data suggest that optimal screening strategies to diagnose polyneuropathy early should be implemented in COPD patients due to their relatively common association and the additional burden of polyneuropathy on quality of life.

Serum interleukin-6 in chronic obstructive pulmonary disease patients and its relation to severity and acute exacerbation

Background and objectives

The role of interleukins in the severity and clinical profile of chronic obstructive pulmonary disease (COPD) is not known, but evidence supports the contribution of systemic inflammation to disease pathophysiology. This study evaluated the relationship of serum interleukin-6 (IL-6) to the severity and clinical parameters of COPD.

Aim of work

The aim of the work is to estimate the level of IL-6 in COPD patients and its relation to COPD severity and acute exacerbation.

Patients and method

We analyzed 45 COPD patients and 45 normal population as control. We estimate the IL-6 level by ELISA and correlate it with the severity and frequency of COPD exacerbation.

Results

In the current study, we noticed that IL-6 level was high in COPD patients and in those who experience frequent exacerbation. Also, IL-6 show a relation with the parameter of pulmonary function test; there is a statistically significant negative correlation with p-value < 0.05 between the level of IL-6 and the forced expired volume in 1 s/forced vital capacity (EFV1/FVC) among cases with COPD, which indicated that decrease in EFV/FVC will associate with the increase in IL-6 level.

Conclusions

The study revealed that serum IL-6 level elevated with increasing severity of airflow limitation in COPD patients, particularly in acute exacerbation phase. This increase was associated with a reduced quality of life and increased severity of hypoxemia.

Chronic axonal idiopathic polyneuropathy: is it really benign

PURPOSE OF REVIEW

Chronic idiopathic axonal polyneuropathy (CIAP), a common neurological condition, is considered to be a benign neurological condition with a small risk of disability. However, many studies have shown a reduced quality of life and a nonnegligible affection of daily activities in patients with CIAP. Here we summarize recent data about CIAP.

RECENT FINDINGS

We discuss some of the latest articles regarding risk factors, comorbidities, and possible pathogenic factors regarding CIAP. Patients with chronic polyneuropathy have impaired walking capacity, disturbed balance, and an increased risk of falls. Idiopathic polyneuropathy has a negative impact on activities of daily living. Patients with CIAP may develop plantar ulcers and neuropathic arthropathy. Small fiber involvement may occur, and two recent studies indicate that neuropathic pain is present in about two thirds of the CIAP group. Furthermore, patients with CIAP with neuropathic pain have increased fatigue and poorer emotional well being.

SUMMARY

Despite the relatively mild motor impairment seen in most patients with CIAP, the condition causes limitations in life with decreased mobility, pain, and affection of basal daily activities. Because the pathogenesis of CIAP in unclear, there is no disease modifying treatment. Further studies regarding pathogenesis, and randomized controlled clinical trials regarding possible treatment options are needed.

Quadriceps Strength and Mortality in Older Patients With Heart Failure

BACKGROUND

This study was performed to test the hypothesis that low quadriceps isometric strength (QIS) is associated with greater risk of mortality and has the additive prognostic significance to the severity of heart failure (HF) and gait speed in older patients with HF.

METHODS

A retrospective cohort study was performed in 1273 patients ≥ 60 years of age with HF (mean age 75 ± 8 years, 59.1% men); all of whom were evaluated during hospitalization for usual gait speed and maximal QIS. The QIS was expressed relative to body mass (% BM). The endpoint was all-cause mortality.

RESULTS

Over a median follow-up period of 1.59 years (interquartile range, 0.58 to 3.42 years), 224 patients died. The cutoff value based on the Youden index for the QIS discriminating those at high risk of mortality was 36.2% BM for overall, and we defined less than this cutoff point of QIS as low QIS. After adjustment for the HF risk score, the hazard ratio in low QIS was 1.55 for overall (95% confidence interval [CI], 1.17-2.06). The addition of low QIS to the HF risk score and gait speed was associated with significant increases in both net reclassification improvement (NRI, 0.239 for overall; 95% CI, 0.096-0.381) and integrated discrimination improvement (IDI, 0.004 for overall; 95% CI, 0.001-0.009) for all-cause mortality.

CONCLUSION

Low QIS was strongly associated with poor prognosis and showed complementary prognostic predictive capability to the HF risk score and gait speed in older patients with HF.

Association between tumor necrosis factor-α and chronic obstructive pulmonary disease: a systematic review and meta-analysis

Background:

Patients diagnosed with chronic obstructive pulmonary disease (COPD) have increased risks for a series of physical and mental illnesses. Tumor necrosis factor-α (TNF-α) has been reported to participate in the development of COPD and its complications. However, the values of blood TNF-α level used in the diagnosis of COPD remains controversial. In view of this, we performed a systematic review and meta-analysis to evaluate the correlation between TNF-α level and COPD.

Methods:

We searched PubMed, Web of Science, Embase and CNKI up to May 2018. The selection criteria were set according to the PICOS framework. A random-effects model was then applied to evaluate the overall effect sizes by calculating standard mean difference (SMD) and its 95% confidence intervals (CIs).

Results:

A total of 40 articles containing 4189 COPD patients and 1676 healthy controls were included in this meta-analysis. The results indicated a significant increase in TNF-α level in the COPD group compared with the control group (SMD: 1.24, 95% CI: 0.78–1.71, p < 0.00001). According to the subgroup analyses, we noted that TNF-α level was associated with predicted first second of forced expiration (FEV₁) (%) and study region. However, no association between TNF-α level and COPD was found when the participants were nonsmokers, and the mean age was less than 60 years.

Conclusions:

Our results indicated that TNF-α level was increased in COPD patients when compared with healthy controls. Illness progression and a diagnosis of COPD might contribute to higher TNF-α levels. However, the underlying mechanism still remains unknown and needs further investigation.

The reviews of this paper are available via the supplemental material section.

Specific motor cortex hypoexcitability and hypoactivation in COPD patients with peripheral muscle weakness

Background

Peripheral muscle weakness can be caused by both peripheral muscle and neural alterations. Although peripheral alterations cannot totally explain peripheral muscle weakness in COPD, the existence of an activation deficit remains controversial. The heterogeneity of muscle weakness (between 32 and 57% of COPD patients) is generally not controlled in studies and could explain this discrepancy. This study aimed to specifically compare voluntary and stimulated activation levels in COPD patients with and without muscle weakness.

Methods

Twenty-two patients with quadriceps weakness (COPD_MW), 18 patients with preserved quadriceps strength (COPD_NoMW) and 20 controls were recruited. Voluntary activation was measured through peripheral nerve (VA_peripheral) and transcranial magnetic (VA_cortical) stimulation. Corticospinal and spinal excitability (MEP/Mmax and Hmax/Mmax) and corticospinal inhibition (silent period duration) were assessed during maximal voluntary quadriceps contractions.

Results

COPD_MW exhibited lower VA_cortical and lower MEP/Mmax compared with COPD_NoMW (p < 0.05). Hmax/Mmax was not significantly different between groups (p = 0.25). Silent period duration was longer in the two groups of COPD patients compared with controls (p < 0.01). Interestingly, there were no significant differences between all COPD patients taken together and controls regarding VA_cortical and MEP/Mmax.

Conclusions

COPD patients with muscle weakness have reduced voluntary activation without altered spinal excitability. Corticospinal inhibition is higher in COPD regardless of muscle weakness. Therefore, reduced cortical excitability and a voluntary activation deficit from the motor cortex are the most likely cortical mechanisms implicated in COPD muscle weakness. The mechanisms responsible for cortical impairment and possible therapeutic interventions need to be addressed.

Association between Beta2-Adrenergic Receptor Agonists and the Risk of Vascular Complications in Diabetic Patients: A Population-Based Cohort Study

Beta2-adrenergic receptor (β2AR) agonists can have protective effects targeting macrophage activation, but research on human subjects has not been done. This study was designed to assess the relationship between the use of β2AR agonists and diabetic vascular complications. Using data from the Korean National Health Insurance Service, adults first diagnosed with diabetes in 2004 (n = 249,222) were followed up until 31 December 2015. Propensity score matching was performed between case and control groups (n = 5179 in each), and multivariate analysis was conducted. The β2AR agonist group was divided into quartiles according to the duration of β2AR agonist use. During the follow-up, the incidence of vascular complications gradually decreased as the duration of β2AR agonist administration increased. Multivariate analysis revealed that the hazard ratio for all composite vascular complications was 0.80 (95% CI, 0.75–0.86, p < 0.001) in the longest quartile of β2AR agonist use as compared with the control group after adjusting for confounding variables. The association between the duration of β2AR agonist use and the risk of each vascular complication including cerebrovascular, peripheral vascular, peripheral neural, renal, and ophthalmic complications was consistent, and the risks were significantly lower in the longest users than the control group. Long-term use of β2AR agonists may exert a protective effect against diabetic vascular complications.

Retinal oximetry and systemic arterial oxygen levels

PURPOSE

Continuous peripheral pulse oximetry for monitoring adequacy of oxygenation is probably the most important technological advance for patients' monitoring and safety in the last decades. Pulse oximetry has the disadvantage of measuring the peripheral circulation, and the only mean to measure oxygen content of the central circulation is by invasive technology. Determination of blood oxyhaemoglobin saturation in the retinal vessels of the eye can be achieved noninvasively through spectrophotometric retinal oximetry which provides access to the central nervous system circulation. The aim of the thesis was to determine whether retinal oximetry technique can be applied for estimation of the central nervous system circulation which until now has only been possible invasively. This was achieved by measuring oxyhaemoglobin saturation in three adult subject study groups: in people with central retinal vein occlusion (CRVO) to observe local tissue hypoxia, in patients with severe chronic obstructive pulmonary disease (COPD) on long-term oxygen therapy to observe systemic hypoxaemia and in healthy subjects during hyperoxic breathing to observe systemic hyperoxemia. In addition, the fourth study that is mentioned was performed to test whether retinal oximetry is feasible for neonates.

METHODS

Retinal oximetry in central retinal vein occlusion: Sixteen subjects with central retinal vein occlusion participated in the study. The oxyhaemoglobin saturation of the central retinal vein occlusion affected eye was compared with the fellow unaffected eye. Retinal oximetry in healthy people under hyperoxia: Thirty healthy subjects participated in the study, and the oxyhaemoglobin saturation of retinal arterioles and venules was compared between normoxic and hyperoxic breathing. Retinal oximetry in severe chronic obstructive pulmonary disease: Eleven patients with severe chronic obstructive pulmonary disease participated in the study. Retinal oximetry measurements were made with and without their daily supplemental oxygen therapy. Retinal arteriolar oxyhaemoglobin saturation when inspiring ambient air was compared with blood samples from the radial artery and finger pulse oximetry and healthy controls. The healthy control group was assembled from our database for comparison of oxyhaemoglobin saturation of retinal arterioles and venules during the ambient air breathing. The retinal oximeter is based on a conventional fundus camera and a specialized software. A beam splitter coupled with two high-resolution digital cameras allows for simultaneous acquisition of retinal images at separative wavelengths for calculation of oxyhaemoglobin saturation. In addition, retinal images of 28 full-term healthy neonates were obtained with scanning laser ophthalmoscope combined with modified Oxymap analysis software for calculation of the optical density ratio and vessel diameter RESULTS: Retinal oximetry in central retinal vein occlusion: Mean retinal venous oxyhaemoglobin saturation was 31 ± 12% in CRVO eyes and 52 ± 11% in unaffected fellow eyes (mean ± SD, n = 14, p < 0.0001). The arteriovenous oxygen difference (AV-difference) was 63 ± 11% in CRVO eyes and 43 ± 7% in fellow eyes (p < 0.0001). The variability of retinal venous oxyhaemoglobin saturation was considerable within and between eyes affected by CRVO. There was no difference in oxyhaemoglobin saturation of retinal arterioles between the CRVO eyes and the unaffected eyes (p = 0.49). Retinal oximetry in healthy people under hyperoxia: During hyperoxic breathing, the oxyhaemoglobin saturation in retinal arterioles increased to 94.5 ± 3.8% as compared with 92.0 ± 3.7% at baseline (n = 30, p < 0.0001). In venules, the mean oxyhaemoglobin saturation increased to 76.2 ± 8.0% from 51.3 ± 5.6% (p < 0.0001) at baseline. The AV-difference was markedly lower during hyperoxic breathing as compared with the normoxic breathing (18.3 ± 9.0% versus 40.7 ± 5.7%, p < 0.0001). Retinal oximetry in severe chronic obstructive pulmonary disease: During ambient air breathing, chronic obstructive pulmonary disease subjects had significantly lower oxyhaemoglobin saturation than healthy controls in both retinal arterioles (87.2 ± 4.9% versus 93.4 ± 4.3%, p = 0.02, n = 11) and venules (45.0 ± 10.3% versus 55.2 ± 5.5%, p = 0.01) but the AV-difference was not markedly different (p = 0.17). Administration of their prescribed oxygen therapy significantly increased the oxyhaemoglobin saturation in retinal arterioles (87.2 ± 4.9% to 89.5 ± 6.0%, p = 0.02) but not in venules (45.0 ± 10.3% to 46.7 ± 12.8%, p = 0.3). Retinal oximetry values were slightly lower than finger pulse oximetry (mean percentage points difference = -3.1 ± 5.5) and radial artery blood values (-5.0 ± 5.4). Retinal oximetry study in neonates: The modified version of the retinal oximetry instrument estimated the optical density ratio in retinal arterioles to be 0.256 ± 0.041 that was significantly different from the 0.421 ± 0.089 in venules (n = 28, p < 0.001, paired t-test). The vascular diameter of retinal arterioles was markedly narrower than of venules (14.1 ± 2.7 and 19.7 ± 3.7 pixels, p < 0.001).

CONCLUSION

The results of this thesis indicate that spectrophotometric retinal oximetry is sensitive to both local and systemic changes in oxyhaemoglobin saturation. Retinal oxyhaemoglobin saturation values are slightly lower than radial artery blood sample and finger pulse oximetry values. The discrepancies between the different modalities are expected to derive from countercurrent exchange between central retinal artery and vein within the optic nerve but calibration issues cannot be excluded as contributing to this difference. Despite these differences, the findings indicate the potential of retinal oximetry for noninvasive real-time measurements of oxyhaemoglobin saturation in central nervous system vessels. Following calibration upgrade and technological improvement, verification retinal oximetry may potentially be applied to critically ill and anaesthesia care patients. The study on combined scanning laser ophthalmoscope and retinal oximetry supports the feasibility of the technique for oximetry analysis in newly born babies.

Insulin-Like Growth Factor-1 Signaling in Lung Development and Inflammatory Lung Diseases

Insulin-like growth factor-1 (IGF-1) was firstly identified as a hormone that mediates the biological effects of growth hormone. Accumulating data have indicated the role of IGF-1 signaling pathway in lung development and diseases such as congenital disorders, cancers, inflammation, and fibrosis. IGF-1 signaling modulates the development and differentiation of many types of lung cells, including airway basal cells, club cells, alveolar epithelial cells, and fibroblasts. IGF-1 signaling deficiency results in alveolar hyperplasia in humans and disrupted lung architecture in animal models. The components of IGF-1 signaling pathways are potentiated as biomarkers as they are dysregulated locally or systemically in lung diseases, whereas data may be inconsistent or even paradoxical among different studies. The usage of IGF-1-based therapeutic agents urges for more researches in developmental disorders and inflammatory lung diseases, as the majority of current data are collected from limited number of animal experiments and are generally less exuberant than those in lung cancer. Elucidation of these questions by further bench-to-bedside researches may provide us with rational clinical diagnostic approaches and agents concerning IGF-1 signaling in lung diseases.

Evaluation of central and peripheral neuropathy in patients with chronic obstructive pulmonary disease

Background

The aim of the study was to investigate the frequency and characteristics of peripheral nervous system (PNS) and central nervous system (CNS) involvement in COPD.

Methods

The study included 41 COPD patients and 41 healthy volunteers. Electrophysiological studies were carried out: electromyography (EMG) and visual evoked potentials (VEPs). The median nerve, ulnar nerve, common peroneal nerve, and tibial nerve were evaluated for latency, amplitude, and conduction velocity.

Results

The mean age of patients with COPD was 61.8 years and disease duration 10.3 years. There was no difference between patient and control groups in terms of age, BMI, smoking status, or biochemical parameters. Upon VEP examination, latencies were significantly prolonged and amplitudes shortened in the patient group compared to the control group. In EMG measurements, conduction velocity and amplitudes in all nerves were low in the patient group. Similarly, latencies in all nerves were higher in patients with COPD.

Conclusion

Central and peripheral nervous system involvement could develop in patients with moderate-severe COPD, and these patients should be monitored for neuropathic changes in combination with neurological examination.

Microangiopathy-A Potential Contributing Factor to Idiopathic Polyneuropathy: A Mini Review

Chronic idiopathic axonal polyneuropathy (CIAP) is a slowly progressive predominantly sensory axonal polyneuropathy. The prevalence of CIAP increases with age. The pathogenic cause of CIAP is unknown although there are several prevailing etiological hypotheses. In this mini review, we focus on the hypothesis of disturbed microcirculation in the vasa nervorum of peripheral nerves as a pathogenic cause of CIAP. There is an association between CIAP and metabolic risk factors. Furthermore, the phenotype of CIAP resembles diabetic neuropathy both clinically and electrophysiologically. In sural nerve biopsies from patients with diabetes mellitus, structural abnormalities indicating microangiopathy in the endoneurial microvessels are well documented. Similarly, sural microvessel abnormalities have been shown in patients with atherosclerotic non-diabetic peripheral vascular disease. However, the reported histopathological alterations of microvasculature in sural nerves of CIAP patients are inconsistent. Two studies report microangiopathic changes in CIAP sural nerves comparable with those found in patients with diabetic neuropathy. Conversely, another recent study showed no significant differences in the microangiopathic parameters in the endoneurial microvessels in the sural nerve biopsies from CIAP patients compared to controls without polyneuropathy. However, this CIAP patient group was younger compared to the patient groups in the other two studies. A general limitation with the published morphological studies are that different methods have been used in the assessment of microangiopathy, and there is also a risk of subjectivity in the results. Immunohistochemistry studies of sural nerves with verification of microangiopathy using specific biomarkers would be of great interest to develop.

Computed Biological Relations among Five Select Treatment-Related Organ/Tissue Toxicities

Drug toxicity presents a major challenge in drug development and patient care. We set to build upon previous works regarding select drug-induced toxicities to find common patterns in the mode of action of the drugs associated with these toxicities. In particular, we focused on five disparate organ toxicities, peripheral neuropathy (PN), rhabdomyolysis (RM), Stevens-Johnson syndrome/toxic epidermal necrosis (SJS/TEN), lung injury (LI), and heart contraction-related cardiotoxicity (CT), and identified biological commonalities between and among the toxicities in terms of pharmacological targets and nearest neighbors (indirect effects) using the hyper-geometric test and a distance metric of Spearman correlation. There were 20 significant protein targets associated with two toxicities and 0 protein targets associated with three or more toxicities. Per Spearman distance, PN was closest to SJS/TEN compared to other pairs, whereas the pairs involving RM were more different than others excluding RM. The significant targets associated with RM outnumbered those associated with every one of the other four toxicities. Enrichment analysis of drug targets that are expressed in corresponding organ/tissues determined proteins that should be avoided in drug discovery. The identified biological patterns emerging from the mode of action of these drugs are statistically associated with these serious toxicities and could potentially be used as predictors for new drug candidates. The predictive power and usefulness of these biological patterns will increase with the database of these five toxicities. Furthermore, extension of our approach to all severe adverse reactions will produce useful biological commonalities for reference in drug discovery and development.

Association between serum interleukin-6 concentrations and chronic obstructive pulmonary disease: a systematic review and meta-analysis

Background. Interleukin-6 (IL-6) is an important pro-inflammatory cytokine and has been implicated to play a role in the systemic inflammation of patients with chronic obstructive pulmonary disease (COPD). We conducted this meta-analysis to assess the association between serum IL-6 concentrations and COPD.

Methods. PubMed and Embase were searched for eligible studies. Data were extracted by two investigators (Wei J, Xiong XF) independently and analyzed using Review Manager 5.3 and STATA 12.0 software. Standard mean differences (SMDs) and 95% confidence intervals (CI) were calculated.

Results. Thirty-three studies were included in this meta-analysis. The serum IL-6 concentrations were higher in patients with stable COPD than healthy controls (SMD = 0.65, 95% CI [0.51–0.79]). COPD patients without major comorbidities also showed higher IL-6 levels than healthy controls (SMD = 0.74, 95% CI [0.56–0.91]). COPD patients with an forced expiratory volume in one second (FEV₁) of either <50% predicted or >50% predicted had increased IL-6 concentrations compared to healthy controls (SMD = 0.77, 95% CI [0.48–1.05], SMD = 1.01, 95% CI [0.43–1.59], respectively). The serum IL-6 concentrations between mild-moderate and severe-very severe COPD patient groups were not found to be significant (SMD = −0.1, 95% CI [−0.65–0.44]).

Conclusions. This meta-analysis indicated that patients with stable COPD had higher serum IL-6 concentrations than healthy controls. No evidence showing positive or negative association between IL-6 concentrations and the severity of pulmonary function impairment was found. The correlation between IL-6 levels and pulmonary function was weak in different severities of stable COPD patients.

Correlation between optic nerve involvement and chronic obstructive pulmonary disease

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is a major public health problem worldwide. The aim of this study was to evaluate the rate of optic neuropathy in COPD patients.

METHODS

Forty patients diagnosed with COPD and 60 healthy subjects as control group enrolled. After examination by a pulmonary subspecialist, patients were ranked by Global initiative for chronic Obstructive Lung Disease (GOLD) criteria, and patients with zero grades on GOLD criteria were excluded. Visual evoked potential by checkerboard (raster background) method with a frequency of 2 Hz were done for all participants. P-values less than 0.05 were considered as significant.

RESULTS

Fifty-five percent of COPD patients had visual evoked potential abnormalities. Mean P100 latency in both eyes was significantly longer in COPD patients. Average P100/N140 amplitude in both eyes were insignificantly higher in COPD.

CONCLUSION

Higher P100 latency in COPD patients shows demyelinating type of optic nerve involvement; however, further investigation in this area is needed.

Cortical implication in lower voluntary muscle force production in non-hypoxemic COPD patients

Recent studies have shown that muscle alterations cannot totally explain peripheral muscle weakness in COPD. Cerebral abnormalities in COPD are well documented but have never been implicated in muscle torque production. The purpose of this study was to assess the neural correlates of quadriceps torque control in COPD patients. Fifteen patients (FEV1 54.1±3.6% predicted) and 15 age- and sex-matched healthy controls performed maximal (MVCs) and submaximal (SVCs) voluntary contractions at 10, 30 and 50% of the maximal voluntary torque of the knee extensors. Neural activity was quantified with changes in functional near-infrared spectroscopy oxyhemoglobin (fNIRS-HbO) over the contralateral primary motor (M1), primary somatosensory (S1), premotor (PMC) and prefrontal (PFC) cortical areas. In parallel to the lower muscle torque, the COPD patients showed lower increase in HbO than healthy controls over the M1 (p<0.05), PMC (p<0.05) and PFC areas (p<0.01) during MVCs. In addition, they exhibited lower HbO changes over the M1 (p<0.01), S1 (p<0.05) and PMC (p<0.01) areas during SVCs at 50% of maximal torque and altered motor control characterized by higher torque fluctuations around the target. The results show that low muscle force production is found in a context of reduced motor cortex activity, which is consistent with central nervous system involvement in COPD muscle weakness.

Neuromuscular transmission in hypoxemic patients with chronic obstructive pulmonary disease

Many studies have focused on the systemic effects of chronic obstructive pulmonary disease (COPD), but none has examined neuromuscular junction transmission (NMT). We evaluated NMT dysfunction using single-fiber electromyography (SFEMG) in patients with COPD. Twenty patients with COPD and 20 age-matched healthy controls were included in the study. All patients and controls underwent SFEMG. Abnormal NMT was found in seven of 20 patients (35%), but in none of the control subjects. The COPD patients were subgrouped according to the presence of hypoxemia. The patients with normoxemia were classified as Group 1, and the patients with hypoxemia were classified as Group 2. Abnormal NMT was found in six patients in Group 2 and in one in Group 1. While there was significant difference in terms of abnormal NMT between Group 2 and the controls, there was none between Group 1 and the controls. Our results show that NMT abnormalities can be present in hypoxemic patients with COPD.

Obstructive sleep apnea and diabetic neuropathy: a novel association in patients with type 2 diabetes

RATIONALE

Diabetic peripheral neuropathy is common and causes significant morbidity. Obstructive sleep apnea (OSA) is also common in patients with type 2 diabetes. Because OSA is associated with inflammation and oxidative stress, we hypothesized that OSA is associated with peripheral neuropathy in type 2 diabetes.

OBJECTIVES

To assess the relationship between OSA and peripheral neuropathy in patients with type 2 diabetes.

METHODS

A cross-sectional study of adults with type 2 diabetes recruited randomly from the diabetes clinic of two UK hospitals.

MEASUREMENTS AND MAIN RESULTS

Peripheral neuropathy was diagnosed using the Michigan Neuropathy Screening Instrument. OSA (apnea-hypopnea index ≥ 5 events/h) was assessed using home-based, multichannel respiratory monitoring. Serum nitrotyrosine was measured by ELISA, lipid peroxide by spectrophotometer, and microvascular function by laser speckle contrast imaging. Two hundred thirty-four patients (mean [SD] age, 57 [12] yr) were analyzed. OSA prevalence was 65% (median apnea-hypopnea index, 7.2; range, 0-93), 40% of which were moderate to severe. Neuropathy prevalence was higher in patients with OSA than those without (60% vs. 27%, P < 0.001). After adjustment for possible confounders, OSA remained independently associated with diabetic neuropathy (odds ratio, 2.82; 95% confidence interval, 1.44-5.52; P = 0.0034). Nitrotyrosine and lipid peroxide levels (n = 102, 74 with OSA) were higher in OSA and correlated with hypoxemia severity. Cutaneous microvascular function (n = 71, 47 with OSA) was impaired in OSA.

CONCLUSIONS

We describe a novel independent association between diabetic peripheral neuropathy and OSA. We identified increased nitrosative/oxidative stress and impaired microvascular regulation as potential mechanisms. Prospective and interventional studies are needed to assess the impact of OSA and its treatment on peripheral neuropathy development and progression in patients with type 2 diabetes.

Effects of peripheral neuropathy on exercise capacity and quality of life in patients with chronic obstructive pulmonary diseases

INTRODUCTION

Chronic obstructive pulmonary diseases (COPD) have some systemic effects including systemic inflammation, nutritional abnormalities, skeletal muscle dysfunction, and cardiovascular, skeletal and neurological disorders. Some studies have reported the presence of peripheral neuropathy (PNP) at an incidence of 28-94% in patients with COPD. Our study aimed to identify whether PNP affects exercise performance and quality of life in COPD patients.

MATERIAL AND METHODS

Thirty mild-very severe patients with COPD (male/female = 29/1, mean age = 64 ±10 years) and 14 normal subjects (male/female = 11/5, mean age = 61 ±8 years) were included in the present study. All subjects underwent pulmonary function testing (PFT), cardiopulmonary exercise testing, electroneuromyography and short form 36 (SF-36).

RESULTS

Peak oxygen uptake (PeakVO(2)) was lower in COPD patients (1.15 ±0.53 l/min) than healthy subjects (2.02 ±0.46 l/min) (p = 0.0001). There was no PNP in healthy subjects while 16 (53%) of the COPD patients had PNP. Forced expiratory volume in 1 s (FEV(1)) and PeakVO(2) were significantly different between patients with PNP and those without (p = 0.009, p = 0.03 respectively). Quality of life of patients with PNP was lower than that of patients without PNP (p < 0.05).

CONCLUSIONS

The present study demonstrates the exercise limitation in COPD patients with PNP. Thus, presence of PNP has a poor effect on exercise capacity and quality of life in patients with COPD. Furthermore, treatment modalities for PNP can be recommended to these patients in order to improve exercise capacity and quality of life.

Lack of the T cell-specific alternative p38 activation pathway reduces autoimmunity and inflammation

Stimulation via the T-cell receptor (TCR) activates p38α and p38β by phosphorylation of p38 Tyr-323 (p38(Y323)). Here we characterize knockin mice in which p38α and/or β Tyr-323 has been replaced with Phe. We find that p38α accounts for two-thirds and p38β the remainder of TCR-induced p38 activation. T cells from double knockin mice (p38αβ(Y323F)) had defects in TCR-mediated proliferation and Th1 and Th17 skewing, the former corresponding with an inability to sustain T-bet expression. Introduction of p38α(Y323F) into Gadd45α-deficient mice, in which the alternative p38 pathway is constitutively active, reversed T-cell hyperproliferation and autoimmunity. Furthermore, p38αβ(Y323F) mice had delayed onset and reduced severity of the inflammatory autoimmune diseases collagen-induced arthritis and experimental autoimmune encephalomyelitis. Thus, T cell-specific alternative activation of p38 is an important pathway in T-cell proliferation, Th skewing, and inflammatory autoimmunity, and may be an attractive tissue-specific target for intervention in these processes.