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Evolutionary Biology of Parasitism
Published in Eric S. Loker, Bruce V. Hofkin, Parasitology, 2023
Eric S. Loker, Bruce V. Hofkin
Among the myriads of organisms living in close association with other organisms, there are several organisms that straddle the boundaries with parasitism. Many organisms are harmless commensals unless and until the host becomes debilitated in some way, after which they assume the status of facultative parasites. This phenomenon is particularly true of ciliate protists living on the surface of fishes. For example, Brooklynella hostilis normally glides over the surface of the gills of fish feeding harmlessly on sloughing gill epithelium. If the fish becomes stressed, as in captivity, the ciliate can attack the gills and denude them of cells, killing the fish in the process. A transition for such an organism to obligatory parasitism is easy to envision. Mites in particular provide many examples of species that are trending toward parasitic lifestyles, and multiple origins of parasitism in mites from predatory ancestors are likely. The mite Kennethiella trisetosa is phoretic on a wasp parasitoid (Ancistrocerus antilope) that lays its eggs on caterpillars (Figure 7.30). At the time of the wasp’s oviposition, the mite disembarks and not only feeds from the caterpillar but also extracts hemolymph from the larvae of the wasp developing in the caterpillar. Examples like this demonstrate that the paths to parasitism are many and often potentially devious in their course.
Gynecologic Cancers and Lifestyle Medicine
Published in Michelle Tollefson, Nancy Eriksen, Neha Pathak, Improving Women's Health Across the Lifespan, 2021
Nathalie D. McKenzie, Nnamdi I. Gwacham, Sarfraz Ahmad
The human microbiome refers to the microorganisms that live mostly symbiotically within the human host. They can be commensal and pathogenic microorganisms. Human cells have evolved out of certain functions due to the diverse gene products offered to us by the organisms in our body, including the gut, oral cavity, lung, urogenital tract, and skin. It has been estimated there are 3×1013 microbes in the human body, roughly equal to the total number of human somatic cells.60 The composition of the microbiome appears to be individually unique. It is mostly established in early life and plays a very important role in lifelong health.61–65 It is also subject to alterations because of both intrinsic and extrinsic factors (Figure 21.2).
Commensal Flora
Published in Firza Alexander Gronthoud, Practical Clinical Microbiology and Infectious Diseases, 2020
The commensal flora in the oropharynx consists mainly of anaerobes and streptococci. Coliforms can be transient colonizers, mainly in hospitalized patients. The most common anaerobes are Actinomyces, Bacteroides, Prevotella, Fusobacterium, Corynebacterium, Veillonella, Rothia and Capnocytophaga. Other members of the commensal flora are streptococci, Gemella and Granulicatella, Neisseria spp. and Haemophilus spp. Infections with oropharyngeal flora are seen in periodontal diseases, endocarditis and aspiration pneumonia. Oropharyngeal flora associated with endocarditis are viridans streptococci, Haemophilus spp. and members belonging to the HACEK group. Periodontal infections, perioral abscesses, sinusitis and mastoiditis may involve predominantly P. melaninogenica, Fusobacterium spp. and Peptostreptococcus spp. Aspiration of saliva may result in necrotizing pneumonia, lung abscess and empyema. Streptococcus mutans plays a particularly important role in dental plaques and caries. Eikenella corrodens is an important pathogen in human bites.
Diet Influences Immunotherapy Outcomes in Cancer Patients: A Literature Review
Published in Nutrition and Cancer, 2023
Naghmeh Kian, Sadra Behrouzieh, Sepideh Razi, Nima Rezaei
The critical role of the gut microbiota in maintaining body homeostasis is well known. Many components of the immune system rely on these commensal microorganisms to function normally. According to Bachem et al. development of memory CD8+ T cells, in part, is dependent on gut microbiota. They transferred antigen-activated CD8+ T cells into germ-free mice and observed transcriptional impairment within these immune cell and failure in transition to memory cells; however, providing mice with the microbiota-derived short-chain fatty acid (SCFA) butyrate promoted CD8+ T cell function (83). Despite the numerous beneficial roles of microbiomes, some studies have also discovered carcinogenic roles for them. Mechanistically, microbiomes are involved in the production of multiple pro-inflammatory cytokines such as tumor necrosis factor-alpha (TNF-a) and IL-1 and subsequent activation of a transcription factor called nuclear factor-κB (NF-κB), resulting in carcinogenesis (84). In addition, gut microbiota might be responsible for some cancer-inducing genetic alterations, as well. An In Vitro study showed that purified B. fragilis toxin upregulates spermine oxidase in colonic epithelial cells, generates ROS and induces γ-H2A.x, a marker of DNA damage (85).
TangNaiKang, herbal formulation, alleviates obesity in diabetic SHR/cp rats through modulation of gut microbiota and related metabolic functions
Published in Pharmaceutical Biology, 2022
Peng Tian, Lili Wu, Maya Kudo, Misa Hayashi, Lingling Qin, Ming Gao, Anlong Xu, Tonghua Liu
Obesity is one of the major public health problems the world is facing today. Multiple factors, including genetics, environment, and an imbalance in energy intake and expenditure, determine the risk of developing obesity. Over time, individuals with obesity show pathological changes in multiple organs, e.g., liver, muscle, and even the brain. Studies have shown that obesity is closely associated with metabolic disorders, including hyperglycaemia, insulin resistance, dyslipidemia, hypertension (Bays and Dujovne 2006), and chronic inflammation (Saltiel and Olefsky 2017). Thus, obesity is a complex disease involving multiple signalling pathways with no clear prognosis. With the advent of 16S rDNA sequencing, an increasing number of studies have reported the correlation between gut microbiota and obesity (Clooney et al. 2016). Commensal bacteria can affect their host by various mechanisms including the production or consumption of metabolites. Therefore, the gut microbiota has become an important mechanism affecting obesity.
Is it time to reconsider prophylactic antimicrobial use for hematopoietic stem cell transplantation? a narrative review of antimicrobials in stem cell transplantation
Published in Expert Review of Anti-infective Therapy, 2021
Dilshad Jahan, Ed Peile, Md Arif Sheikh, Salequl Islam, Sharlene Parasnath, Paras Sharma, Katia Iskandar, Sameer Dhingra, Jaykaran Charan, Timothy Craig Hardcastle, Nandeeta Samad, Tajkera Sultana Chowdhury, Siddhartha Dutta, Mainul Haque
Andermann and colleagues from Stanford speculate about ‘precision’ probiotics including the possibility that they could be engineered to support GM and also have the qualities of a biological ‘off-switch’ activating at the first suspicion of bacteremia. The possibility of specially designed nonpathogenic microbiota could be even more useful even in exceedingly immunocompromised patients enduring HSCT [189]. Probiotics are live beneficial bacteria and yeasts used as complementary nutritional supplements that have proposed health benefits in helping to reinstate GI commensal microflora. When added into the diet, probiotics’ potential health benefits have been documented in the management (treatment and prevention) of CDI, antibiotic-associated diarrhea, and inflammatory bowel disease [246,247]. These reports question whether probiotics possess similar health benefits among patients with hematological malignancies and HSCT’s need. These patients often suffer from substantial GI-related complications because of cancer chemotherapy: extensive mucositis, GI GVHD, CDI, and immune destruction. These events provoke disturbed microbial multiplicity of GI microbiota, injure healthy mucosal physiology, and damage mucosal immunity, resulting in septicemia and other life-threatening pathological issues post-Allo-HSCT.