Muscle atonia index during multiple sleep latency test: A possible marker to differentiate narcolepsy from other hypersomnias

OBJECTIVE

The complexity and delay of the diagnosis of narcolepsy require several diagnostic tests and invasive procedures such as lumbar puncture. Our study aimed to determine the changes in muscle tone (atonia index, AI) at different levels of vigilance during the entire multiple sleep latency test (MSLT) and each nap in people with narcolepsy type 1 (NT1) and 2 (NT2) compared with other hypersomnias and its potential diagnostic value.

METHODS

Twenty-nine patients with NT1 (11 M 18F, mean age 34.9 years, SD 16.8) and sixteen with NT2 (10 M 6F, mean age 39 years, SD 11.8) and 20 controls with other hypersomnias (10 M, 10F mean age 45.1 years, SD 15.1) were recruited. AI was evaluated at different levels of vigilance (Wake and REM sleep) in each nap and throughout the MSLT of each group. The validity of AI in identifying patients with narcolepsy (NT1 and NT2) was analyzed using receiver operating characteristic (ROC) curves.

RESULTS

AI during wakefulness (WAI) was significantly higher in the narcolepsy groups (NT1 and NT2 p < 0.001) compared to the hypersomniac group. AI during REM sleep (RAI) (p = 0.03) and WAI in nap with sudden onsets of REM sleep periods (SOREMP) (p = 0.001) were lower in NT1 than in NT2. The ROC curves showed high AUC values for WAI (NT1 0.88; Best Cut-off > 0.57, Sensitivity 79.3 % Specificity 90 %; NT2 0.89 Best Cut-off > 0.67 Sensitivity 87.5 % Specificity 95 %; NT1 and NT2 0.88 Best Cut-off > 0.57 Sensitivity 82.2 % Specificity 90 %) in discriminating subjects suffering from other hypersomnias. RAI and WAI in nap with SOREMP showed a poor AUC value (RAI AUC: 0.7 Best cutoff 0.7 Sensitivity 50 % Specificity 87.5 %; WAI in nap before SOREMP AUC: 0.66, Best cut-off < 0.82 sensitivity 61.9 % and specificity 67.35 %) differentiating NT1 and NT2.

CONCLUSIONS

WAI may represent an encouraging electrophysiological marker of narcolepsy and suggests a vulnerable tendency to dissociative wake / sleep dysregulation lacking in other forms of hypersomnia.

SIGNIFICANCE

AI during wakefulness may help distinguish between narcolepsy and other hypersomnias.

Obstructive sleep apnoea and Alzheimer's disease: In search of shared pathomechanisms

Alzheimer's disease (AD) is a significant public health concern. The incidence continues to rise, and it is set to be over one million in the UK by 2025. The processes involved in the pathogenesis of AD have been shown to overlap with those found in cognitive decline in patients with Obstructive Sleep Apnoea (OSA). Currently, the standard treatment for OSA is Continuous Positive Airway Pressure. Adherence to treatment can, however, be an issue, especially in patients with dementia. Also, not all patients respond adequately, necessitating the use of additional treatments. Based on the body of data, we here suggest that excessive and prolonged neuronal activity might contribute to genesis and acceleration of both AD and OSA in the absence of appropriately structured sleep. Further, we argue that external factors, including systemic inflammation and obesity, are likely to interfere with immunological processes of the brain, and further promote disease progression. If this hypothesis is proven in future studies, it could have far-reaching clinical translational implications, as well as implications for future treatment strategies in OSA.

Obstructive sleep apnoea and Alzheimer's disease: In search of shared pathomechanisms

Alzheimer's disease (AD) is a significant public health concern. The incidence continues to rise, and it is set to be over one million in the UK by 2025. The processes involved in the pathogenesis of AD have been shown to overlap with those found in cognitive decline in patients with Obstructive Sleep Apnoea (OSA). Currently, the standard treatment for OSA is Continuous Positive Airway Pressure. Adherence to treatment can, however, be an issue, especially in patients with dementia. Also, not all patients respond adequately, necessitating the use of additional treatments. Based on the body of data, we here suggest that excessive and prolonged neuronal activity might contribute to genesis and acceleration of both AD and OSA in the absence of appropriately structured sleep. Further, we argue that external factors, including systemic inflammation and obesity, are likely to interfere with immunological processes of the brain, and further promote disease progression. If this hypothesis is proven in future studies, it could have far-reaching clinical translational implications, as well as implications for future treatment strategies in OSA.

Risk factors for bacteriuria due to Pseudomonas aeruginosa or Enterococcus spp in patients hospitalized via the emergency department

To determine the incidence and risk factors related to isolation of Pseudomonas aeruginosa or Enterococcus spp from urine cultures obtained from patients in the emergency department (ED), a 1-year prospective study was conducted of all urine specimens collected in the ED of a general hospital. Specimens from which one of these organisms was isolated at a concentration of >or=10(5) cfu/ml were included. Of 744 positive urine cultures, 39 (5%) were P. aeruginosa and 28 (4%) Enterococcus spp. Comparison with a control cohort of 80 patients with Escherichia coli bacteriuria revealed several univariate indicators for P. aeruginosa bacteriuria, including male sex, indwelling catheter, past prostatectomy, hospitalization in the previous 2 months and pregnancy; multivariate indicators were indwelling catheter (p<0.001) and male sex (p<0.001). Enterococcus and P. aeruginosa were significantly more often associated with asymptomatic bacteriuria. These data will help clinicians select appropriate antibiotic treatment for patients with urinary tract infections.

Tumor necrosis factor-alpha inhibits store-mediated Ca2+ entry in the human hepatocellular carcinoma cell line HepG2

Tumor necrosis factor-alpha (TNF-alpha) is an important component of the early signaling pathways leading to liver regeneration and proliferation, but it is also responsible for several hepatotoxic effects. We have investigated the effect of TNF-alpha on thapsigargin (TG)-induced store-mediated Ca2+ entry (SMCE) in the human hepatocellular carcinoma cell line HepG2. In these cells, short-term (10 min) exposure to TNF-alpha slightly increased SMCE. In contrast, long-term (12 h) exposure to TNF-alpha significantly reduced SMCE. This effect was reversed by coincubation with atrial natriuretic peptide (ANP), which itself had no effect on SMCE. Cytochalasin D and latrunculin A, inhibitors of actin polymerization, abolished SMCE. Long-term exposure of HepG2 cells to TNF-alpha abolished TG-induced actin polymerization and membrane association of Ras proteins. When TNF-alpha was added in combination with ANP, these effects were reduced. These findings suggest that in HepG2 cells, TNF-alpha inhibits SMCE by affecting reorganization of the actin cytoskeleton, probably by interfering with the activation of Ras proteins, and that ANP protects against these inhibitory effects of TNF-alpha.

Activation of arcuate nucleus neurons by systemic administration of leptin and growth hormone-releasing peptide-6 in normal and fasted rats

Both leptin and growth hormone secretagogues are believed to have stimulatory effects on the hypothalamic growth hormone pulse generator, though whether these are achieved through the same pathway is unknown. Systemic administration of a normally maximal effective dose of the growth hormone secretagogue GHRP-6 to male rats causes the induction of c-Fos protein in the ventromedial aspect of the hypothalamic arcuate nucleus. The effect of the same dose of GHRP-6 is, however, much greater in animals that have been fasted for 48 h, suggesting that in the food-replete rat, arcuate neurons either show reduced sensitivity to endogenous growth hormone secretagogues or they are under the tonic inhibitory influences of other factors. The major populations of arcuate neurons activated by GHRP-6 have been shown to contain neuropeptide Y or growth hormone-releasing factor, while leptin is thought to be inhibitory to neuropeptide Y neurons. Leptin did not alter the response of the rats to GHRP-6. However, it was able by itself to induce c-Fos protein immunoreactivity in the ventral, including the ventrolateral, arcuate nucleus of fasted rats. This is a clear demonstration of the acute activation of arcuate neurons in the rat following systemic leptin injection and suggests that GHRP-6 and leptin act on the growth hormone axis via different pathways.