According to Descartes, minds and bodies are distinct kinds of "substance", and they cannot have causal interactions. However, in neuroscience, the two-way interaction between the brain and peripheral organs is an emerging field of research. Several lines of evidence highlight the importance of such interactions. For example, the peripheral metabolic systems are overwhelmingly regulated by the mind (brain), and anxiety and depression greatly affect the functioning of these systems. Also, psychological stress can cause a variety of physical symptoms, such as bone loss. Moreover, the gut microbiota appears to play a key role in neuropsychiatric and neurodegenerative diseases. Mechanistically, as the command center of the body, the brain can regulate our internal organs and glands through the autonomic nervous system and neuroendocrine system, although it is generally considered to be outside the realm of voluntary control. The autonomic nervous system itself can be further subdivided into the sympathetic and parasympathetic systems. The sympathetic division functions a bit like the accelerator pedal on a car, and the parasympathetic division functions as the brake. The high center of the autonomic nervous system and the neuroendocrine system is the hypothalamus, which contains several subnuclei that control several basic physiological functions, such as the digestion of food and regulation of body temperature. Also, numerous peripheral signals contribute to the regulation of brain functions. Gastrointestinal (GI) hormones, insulin, and leptin are transported into the brain, where they regulate innate behaviors such as feeding, and they are also involved in emotional and cognitive functions. The brain can recognize peripheral inflammatory cytokines and induce a transient syndrome called sick behavior (SB), characterized by fatigue, reduced physical and social activity, and cognitive impairment. In summary, knowledge of the biological basis of the interactions between the central nervous system and peripheral organs will promote the full understanding of how our body works and the rational treatment of disorders. Thus, we summarize current development in our understanding of five types of central-peripheral interactions, including neural control of adipose tissues, energy expenditure, bone metabolism, feeding involving the brain-gut axis and gut microbiota. These interactions are essential for maintaining vital bodily functions, which result in homeostasis, i.e., a natural balance in the body's systems.

The microbiota-gut-brain axis plays an important role in the development of neurodegenerative diseases. Commensal and pathogenic enteric bacteria can influence brain and immune system function by the production of lipopolysaccharides and amyloid. Dysbiosis of the intestinal microbiome induces local and consecutively systemic immune-mediated inflammation. Proinflammatory cytokines then trigger neuroinflammation and finally neurodegeneration. Immune-mediated oxidative stress can lead to a deficiency of vitamins and essential micronutrients. Furthermore, the wrong composition of gut microbiota might impair the intake and metabolization of nutrients. In patients with Alzheimer's disease (AD) significant alterations of the gut microbiota have been demonstrated. Standard Western diet, infections, decreased physical activity and chronic stress impact the composition and diversity of gut microbiota. A higher abundancy of "pro-inflammatory" gut microbiota goes along with enhanced systemic inflammation and neuroinflammatory processes. Thus, AD beginning in the gut is closely related to the imbalance of gut microbiota. Modulation of gut microbiota by Mediterranean diet, probiotics and curcumin can slow down cognitive decline and alter the gut microbiome significantly. A multi-domain intervention approach addressing underlying causes of AD (inflammation, infections, metabolic alterations like insulin resistance and nutrient deficiency, stress) appears very promising to reduce or even reverse cognitive decline by exerting positive effects on the gut microbiota.

Probiotics are in use for physiological boosting, health supplement, and for treatment since historical time. Recently, the to-and-fro pathways linking the gut with the brain, explaining the indirect communication via modulation of immune function and levels of various neurotransmitters, have been discovered, but how precisely these modulations alter the levels of neurotransmitters contributing to the cognitive and other symptom improvements in patients with schizophrenia remains a new arena of research for psychiatry and psychology professionals. The germ-free mice experiments have been the game changer in the mechanistic exploration. The antimicrobial usage alters the local gut flora and hence is associated with psychiatric side effects that strengthen the association further. The changes in the genetics of these bacteria with different types of diet and its correlation with neurotransmitters production capacity and the psyche of the individual are indeed an emerging field for schizophrenia research. Redressal of issues such as manufacturing, the shelf life of probiotics, and stability of probiotics in the gut milieu, in the presence of food, secretions, and exact volume needed for particular age group will help in refining the dose duration of probiotic therapy. Clinical trials are underway for evaluating safety and efficacy in schizophrenia. The gut microorganism transplant and pharmacovigilance of probiotics are important areas yet to be addressed accurately. This paper elucidates the pathways, clinical studies, availability of probiotics in the Indian market with their composition, regulatory issues in India about the probiotic use, and future of probiotic research in schizophrenia.

The global spread of antibiotic-resistant pathogens threatens to increase the mortality of cancer patients significantly. We propose that chemotherapy contributes to the emergence of antibiotic-resistant bacteria within the gut and, in combination with antibiotics, drives pathogen overgrowth and translocation into the bloodstream. In our model, these processes are mediated by the effects of chemotherapy on bacterial mutagenesis and horizontal gene transfer, the disruption of commensal gut microbiology, and alterations to host physiology. Clinically, this model manifests as a cycle of recurrent sepsis, with each episode involving ever more resistant organisms and requiring increasingly broad-spectrum antimicrobial therapy. Therapies that restore the gut microbiota following chemotherapy or antibiotics could provide a means to break this cycle of infection and treatment failure.

The human body hosts an enormous abundance and diversity of microbes, which perform a range of essential and beneficial functions. Our appreciation of the importance of these microbial communities to many aspects of human physiology has grown dramatically in recent years. We know, for example, that animals raised in a germ-free environment exhibit substantially altered immune and metabolic function, while the disruption of commensal microbiota in humans is associated with the development of a growing number of diseases. Evidence is now emerging that, through interactions with the gut-brain axis, the bidirectional communication system between the central nervous system and the gastrointestinal tract, the gut microbiome can also influence neural development, cognition and behaviour, with recent evidence that changes in behaviour alter gut microbiota composition, while modifications of the microbiome can induce depressive-like behaviours. Although an association between enteropathy and certain psychiatric conditions has long been recognized, it now appears that gut microbes represent direct mediators of psychopathology. Here, we examine roles of gut microbiome in shaping brain development and neurological function, and the mechanisms by which it can contribute to mental illness. Further, we discuss how the insight provided by this new and exciting field of research can inform care and provide a basis for the design of novel, microbiota-targeted, therapies.

Clostridium difficile infection (CDI) is a costly result of antibiotic use, responsible for an estimated 14,000 deaths annually in the USA according to the Centers for Disease Control and Prevention. Annual costs attributable to CDI are in excess of $US 1 billion. This review summarizes appropriate utilization of prevention and treatment methods for CDI that have the potential to reduce the economic and humanistic costs of the disease. Some cost-effective strategies to prevent CDI include screening and isolation of hospital admissions based on C. difficile carriage to reduce transmission in the inpatient setting, and probiotics, which are potentially efficacious in preventing CDI in the appropriate patient population. The most extensively studied agents for treatment of CDI are metronidazole, vancomycin, and fidaxomicin. Most economic comparisons between metronidazole and vancomycin favor vancomycin, especially with the emergence of metronidazole-resistant C. difficile strains. Metronidazole can only be recommended for mild disease. Moderate to severe CDI should be treated with vancomycin, preferably the compounded oral solution, which provides the most cost-effective therapeutic option. Fidaxomicin offers a clinically effective and potentially cost-effective alternative for treating moderate CDI in patients who do not have the NAP1/BI/027 strain of C. difficile. Probiotics and fecal microbiota transplant have variable efficacy and the US FDA does not currently regulate the content; the potential economic advantages of these treatment modalities are currently unknown.

Fecal microbiota transplantation (FMT) is an emerging experimental therapy for treatment of recurrent Clostridium difficile infection. In the future, FMT has the potential to be a treatment modality in other diseases that involve gut dysbiosis. As use of FMT is likely to expand, pediatric nurses need a clear understanding of FMT to provide appropriate education, assessment, and care for these patients. Pediatric research and clinical nurses are a resource to help children and parents understand the procedure. Important topics include donor screening, patient assessment before, during, and after treatment; routes of administration and positioning; preparation for discharge and followup evaluation.