Plasticity of circadian clocks and consequences for metabolism.

The increased prevalence of metabolic disorders and obesity in modern society, together with the widespread use of artificial light at night, have led researchers to investigate whether altered patterns of light exposure contribute to metabolic disorders. This article discusses the experimental evidence that perturbed environmental cycles induce rhythm disorders in the circadian system, thus leading to metabolic disorders. This notion is generally supported by animal studies. Distorted environmental cycles, including continuous exposure to light, affect the neuronal organization of the central circadian pacemaker in the suprachiasmatic nucleus (SCN), its waveform and amplitude of the rhythm in electrical activity. Moreover, repeated exposure to a shifted light cycle or the application of dim light at night are environmental cues that cause a change in SCN function. The effects on the SCN waveform are the result of changes in synchronization among the SCN's neuronal cell population, which lead consistently to metabolic disturbances. Furthermore, we discuss the effects of sleep deprivation and the time of feeding on metabolism, as these factors are associated with exposure to disturbed environmental cycles. Finally, we suggest that these experimental studies reveal a causal relationship between the rhythm disorders and the metabolic disorders observed in epidemiological studies performed in humans.

FSGS tip lesion in polyautoimmunity including Sjögren's syndrome.

We present a case with five auto-immune phenomena, including Sjögren's syndrome, for which we also diagnosed a tip lesion of focal segmental glomerulosclerosis (FSGS).v About one-third of Sjögren's syndrome patients have renal involvement, but FSGS is rarely reported. FSGS is thought to involve T-cell dysfunction and in this patient with multiple auto-immune phenomena, it may reflect a severe dysregulation of cellular immunity.

Pancreatitis as the presenting symptom of abdominal sarcoidosis.

We present a 60-year-old woman with non-pulmonary sarcoidosis manifesting as acute pancreatitis, possibly due to hypercalcaemia. Pancreatitis in sarcoidosis is rare, particularly as a presenting symptom. This case demonstrates that sarcoidosis should be included in the differential diagnosis of pancreatitis with hypercalcaemia, even without pulmonary signs of sarcoidosis.