Influence of HCV infection on insulin-like growth factor 1 and proinflammatory cytokines: association with risk for growth hormone resistance development

Communications between the endocrine, immune systems and the liver have been postulated. The liver is the central organ in growth hormone/insulin-like growth factor (GH-IGF) axis. Infection with hepatitis C virus (HCV) can lead to liver problems. Although proinflammatory cytokines are an integral part of inflammation in chronic liver diseases, their involvement in mediating hepatic GH resistance during HCV infection remains to be elucidated. To address this issue, our study aimed at evaluating the influence of HCV infection on serum profile of IGF-1, TNF-alpha and IL-6 to assess their possible relation to hepatic dysfunction and GH resistance development. Twenty-five chronic HCV patients were studied together with 15 healthy control subjects. Serum concentration of IGF-1, TNF-alpha and IL-6 was determined by ELISA. HCV viral load was assessed by Real-time polymerase chain reaction using TaqMan probe technology. Basal serum GH levels were determined by a chemiluminescence assay and serum aminotransferases' activities were also measured. TNF-alpha and IL-6 demonstrated higher serum levels, while IGF-1 levels were significantly lower in HCV patients compared to healthy controls. A statistically significant positive correlation was observed between GH and IL-6 levels (P<0.05), a similar trend was found between GH levels, GH/IGF-1 ratio and AST/ALT ratio (P<0.01, P<0.01, respectively). A significant negative correlation was observed between HCV viral load and GH levels (P<0.05). The progressive increase in HCV viral load matches the decrease in circulating IGF-1 levels but without reaching statistical significance. We conclude that the GH insensitivity could be induced by HCV infection and mediated by proinflammatory cytokines through their possible role in blunting the hepatic response to GH. This crosstalk between proinflammatory cytokines and GH-IGF-1 axis could be responsible for triggering impaired glucose metabolism and diabetes later on in chronic HCV infection.     

Neural respiratory drive in healthy subjects and in COPD

The aim of the present study was to use the diaphragm electromyogram (EMG(di)) to compare levels of neural respiratory drive (NRD) in a cohort of healthy subjects and chronic obstructive pulmonary disease (COPD) patients, and to investigate the relationship between NRD and pulmonary function in COPD. EMG(di) was recorded at rest and normalised to peak EMG(di) recorded during maximum inspiratory manoeuvres (EMG(di) % max) in 100 healthy subjects and 30 patients with COPD, using a multipair oesophageal electrode. EMG(di) was normalised to the amplitude of the diaphragm compound muscle action potential (CMAP(di,MS)) in 64 healthy subjects. The mean+/-sd EMG(di) % max was 9.0+/-3.4% in healthy subjects and 27.9+/-9.9% in COPD patients, and correlated with percentage predicted forced expiratory volume in one second, vital capacity and inspiratory capacity in patients. EMG(di) % max was higher in healthy subjects aged 51-80 yrs than in those aged 18-50 yrs (11.4+/-3.4 versus 8.2+/-2.9%, respectively). Observations in the healthy group were similar when peak EMG(di) or CMAP(di,MS) were used to normalise EMG(di). Levels of neural respiratory drive were higher in chronic obstructive pulmonary disease patients than healthy subjects, and related to disease severity. Diaphragm compound muscle action potential could be used to normalise diaphragm electromyogram if volitional inspiratory manoeuvres could not be performed, allowing translation of the technique to critically ill and ventilated patients.     

Computed tomography in sciatica

Lumber facet arthropathy and a herniated disk are two major causes of low back pain and sciatica. The authors evaluated the importance of computed tomography (CT) in 243 patients with low back pain and/or sciatica. Lumbar facet abnormalities were found in 139 patients (57%), and a herniated disk was found in 48 patients (20%). CT findings correlated precisely with surgical observations in cases involving a herniated disk and correlated well with the results of an intra-articular facet block in a small series of patients. CT can effectively diagnose and differentiate between lumbar facet arthropathy and a herniated disk.