The gut microbiota and its correlations with the central nervous system disorders.

A mutual impact of gastrointestinal tract (GIT) and central nervous system (CNS) functions has been recognized since the mid-twentieth century. It is accepted that the so-called gut-brain axis provides a two-way homeostatic communication, through immunological, hormonal and neuronal signals. A dysfunction of this axis has been associated with the pathogenesis of some diseases both within and outside the GIT, that have shown an increase in incidence over the last decades. Studies comparing germ-free animals and animals exposed to pathogenic bacterial infections, probiotics or antibiotics suggest the participation of the microbiota in this communication and a role in host defense, regulation of immunity and autoimmune disease appearance. The GIT could represent a vulnerable area through which pathogens influence all aspects of physiology and even induce CNS neuro-inflammation. All those concepts may suggest the modulation of the gut microbiota as an achievable strategy for innovative therapies in complex disorders. Moving from this background, the present review discusses the relationship between intestinal microbiota and CNS and the effects in health and disease. We particularly look at how the commensal gut microbiota influences systemic immune response in some neurological disorders, highlighting its impact on pain and cognition in multiple sclerosis, Guillain-Barrè Syndrome, neurodevelopmental and behavioral disorders and Alzheimer's disease. In this review we discuss recent studies showing that the potential microbiota-gut-brain dialogue is implicated in neurodegenerative diseases. Gaining a better understanding of the relationship between microbiota and CNS could provide an insight on the pathogenesis and therapeutic strategies of these disorders.

Irritable bowel syndrome: new findings in pathophysiological and therapeutic field.

Irritable bowel syndrome (IBS) is a high prevalence disease, whose symptoms are reported by a large number of young adults with significant effects on quality of life and social costs. Traditionally, IBS has been treated with dietary and lifestyle modification, fiber supplementation, psychological and pharmacological therapy. Since its complex and multifactorial etiopathogenesis is only partially known, therapeutic choices may be difficult and not always effective. New research efforts focused on the role of relationship between central nervous system and gut disorders (brain-gut axis), altered composition of gut microbiota (e.g. an eight times increased risk for IBS after Salmonella infection), immune activation with an increased number of T lymphocytes and mast cells associated with mucosa as well as an increased level of pro-inflammatory cytokines (IL-10 and IL-12, suggesting Th1 polarization), visceral hypersensitivity causing perception of pain even for minimal abdominal distension. Based on these findings, new possibilities of treatment are emerging with encouraging outcomes. Attention is directed to drugs that showed good tolerability profile and poor systemic absorption, which may make them suitable for repeated or long term treatments, as frequently required in patients with IBS. They have been successfully used drugs such as tachykinin receptors antagonists, tryptophan hydroxylase inhibitors, bile acid sequestrants, µ agonist and δ antagonist opioid receptors. Recent studies are discussed in this review, focusing both on new therapeutic approaches and innovative adaptation of previously available treatments.

[The ventilation-perfusion ratio, with special reference to muscular exercise]. / Il rapporto ventilazione/perfusione, con particolare riguardo al lavoro muscolare

The values of VA/Q obtained at rest in 12 normal subjects undergoing cardiac catheterization in a supine position were between 0.63 and 1.695, with a mean of 1.142 +/- 0.295. The VA/Q values obtained in another 10 healthy subjects tested in a sitting position with a rebreathing method for calculating Q. were somewhat less scattered (between 0.77 and 1.50), and also lower (mean 0.975 +/- 0.210). A highly significant correlation was demonstrated during muscular exercise on the bicycle ergometer (sitting position), both between oxygen consumption and alveolar ventilation and between oxygen consumption and cardiac output. However, since at various submaximal work loads cardiac output increased much less than alveolar ventilation, the overall VA/Q ratio showed a progressive increment with increasing oxygen consumption.