Academic literature on the topic 'External mucus'

Fish mucus layers are the main surface of exchange between fish and the environment, and they possess important biological and ecological functions. Fish mucus research is increasing rapidly, along with the development of high-throughput techniques, which allow the simultaneous study of numerous genes and molecules, enabling a deeper understanding of the fish mucus composition and its functions. Fish mucus plays a major role against fish infections, and research has mostly focused on the study of fish mucus bioactive molecules (e.g., antimicrobial peptides and immune-related molecules) and associated microbiota due to their potential in aquaculture and human medicine. However, external fish mucus surfaces also play important roles in social relationships between conspecifics (fish shoaling, spawning synchronisation, suitable habitat finding, or alarm signals) and in interspecific interactions such as prey-predator relationships, parasite–host interactions, and symbiosis. This article reviews the biological and ecological roles of external (gills and skin) fish mucus, discussing its importance in fish protection against pathogens and in intra and interspecific interactions. We also discuss the advances that “omics” sciences are bringing into the fish mucus research and their importance in studying the fish mucus composition and functions.

The mucus layer covers all the internal surfaces of the body. The surfaces communicate with the external environment. The functions of the mucus layer are determined by its components, including glycoproteins that provide physical and chemical protection to the epithelium. The glycoproteins also perform the exchange function with the external environment. Even at the dawn of evolution, glycoproteins were exteriorly organized to protect the first multicellular animals from external microorganisms, pathogens, and toxins. It is interesting to note that the structure of the glycoproteins has similarities with the structure of antibodies, especially in terms of the relatively constant polypeptide chain and its glycosylated sections, containing oligosaccharide chains with different variants of monosaccharides. The review discusses modern concepts of the mucus layer evolution, the structure of glycoproteins, the peculiarities of its synthesis, degradation, and under-researched functions of the mucus layer. It is assumed that the mucus layer has virucidal and bactericidal capabilities due to circulating enzymes of the digestive tract, which can accumulate in the mucus layer and degrade any microorganisms, regardless of their variation, mutations, and recombination. Therefore, the normal production of digestive tract enzymes can provide non-specific protection from external pathogens entering through open systems of the body. Understanding these processes can significantly limit the spread of existing and new infections.

Airway surface liquid (ASL), a mixture of periciliary fluid and submucosal gland secretions, was collected from the ferret isolated trachea in vitro. The trachea was closed, without possibility of evaporation. The collected ASL was hyperosmolar (310-350 mosmol.kg-1) compared with Krebs-Henseleit solution (280 mosmol.kg-1). Compared with surrounding Krebs-Henseleit solution, the ASL had higher sodium and chloride contents, and considerably higher potassium and calcium contents. The ASL was acid (pH about 7.00) compared with Krebs-Henseleit solution (pH 7.40). Applying methacholine and salbutamol to the preparation significantly changed most of the electrolyte concentrations, and reduced pH. The pH was not significantly changed by bubbling the surrounding buffer with 0-20% CO2, with corresponding buffer changes in pH of 6.95-8.05. Adding labelled albumin to the external buffer resulted in lumenal concentrations that, in the presence of salbutamol, were higher than outside. This and other evidence suggested that albumin could be actively secreted into the lumen, a process enhanced by salbutamol. Thus ASL is hyperosmolar, of different electrolyte composition from interstitial fluid, and of low pH which is homeostatically regulated. The epithelium can actively secrete albumin into the lumen.

Maintaining intestinal health requires clear segregation between epithelial cells and luminal microbes. The intestinal mucus layer, produced by goblet cells (GCs), is a key element in maintaining the functional protection of the epithelium. The importance of the gut mucus barrier is highlighted in mice lacking Muc2, the major form of secreted mucins. These mice show closer bacterial residence to epithelial cells, develop spontaneous colitis and became moribund when infected with the attaching and effacing pathogen, Citrobacter rodentium. Furthermore, numerous observations have associated GCs and mucus layer dysfunction to the pathogenesis of inflammatory bowel disease (IBD). However, the molecular mechanisms that regulate the physiology of GCs and the mucus layer remain obscured. In this review, we consider novel findings describing divergent functionality and expression profiles of GCs subtypes within intestinal crypts. We also discuss internal (host) and external (diets and bacteria) factors that modulate different aspects of the mucus layer as well as the contribution of an altered mucus barrier to the onset of IBD.

Specimens of six scleractinian species were gathered during the austral spring (October–November) 1994 on the external slope of the barrier reef of Arue, Tahiti, and in the lagoon of Arutua, a Tuamotu island. Mucus of each specimen was collected and the optical density and volume excreted were measured. After treatment, mucus was analysed for mycosporine-like amino acids (MAAs) by high-performance liquid chromatography (HPLC). Nine UV-absorbing compounds were present in coral mucus at concentrations between 1 and 500 ng g-1 mucus. Palythine and mycosporine–gly were found in all mucus studied. Mycosporine–2glycine was recovered in 71% of specimens and shinorine in 28%. Porphyra-334 and palythinol were identified as minor MAAs. Three recently identified MAAs, palythine–serine, mycosporine–methylamine:serine and mycosporine–methylamine:threonine, were also found in mucus from Pocillopora. Within a genus, there was a qualitative similarity in MAAs determined by HPLC, irrespective of locality. Values for optical density of the mucus showed the ability of MAAs to protect the animal host and endosymbiotic algae from UV-solar flux and, as inferred from the recent literature, from oxidative forms of oxygen (HO2 . , O 2 - , HO.) derived from photosynthesis.

Abstract Hydrogel plays an important role in the composition of biological tissue. Muscle, cell membrane, blood vessel wall, hair and cartilage in human body can be regarded as hydrogel. The mucus on the surface of natural living organisms such as loach, andrias davidianus and earthworm is natural hydrogel. This kind of mucus with peculiar smell is produced by living organisms due to external stimulation of body surface stress response. It is a kind of self-protection. And this mucus has certain effects of antibacterial, antifatigue and enhancing immunity. The main component of mucus is collagen with shorter molecular structure and molecular weight is relatively small, and the content of collagen can reach about 40 ∼ 60 % in mucus. It has a certain bonding effect on skin surface damage, and plays the function of quickly closing wounds and killing bacteria. Hyaluronic acid (HA), active structure in oligosaccharide peptide and collagen peptide extracted from mucus, particularly type II collagen, play important roles in skin repair. This function of this natural hydrogel may open a new approach for the development of secondary functions of such organisms.

Diabetes mellitus (DM) can cause gastric ulcers (GU), duodenal ulcers (DU), and gastroesophageal reflux disease (GERD). Mucus-secreting cells secrete mucus, which aids in the neutralization of HCl and inhibits bacteria. DM can alter mucus-secreting cells. Due to a lack of mucosal defense, external stimuli such as bacteria or ethanol can lead to the development of GU, DU, and GERD. This research study used a STZ-induced diabetic rat model to examine the short- and long-term histopathology and ultrastructural alterations in mucus-secreting cells in the cardia, body, and pyloric regions of the stomach. Quantitative analysis was also employed in this study to examine the distribution of mucin granules across all three locations. Twenty-four male adult Sprague-Dawley rats were utilized. Rats were divided into the control (n = 12) and DM (n = 12) groups. Each was separated into short-term (4 weeks) and long-term (24 weeks) rats. For DM induction, streptozotocin (STZ) can selectively destroy the beta cells of the pancreas. The DM was injected with STZ in citrate buffer at 60 mg/kg body weight. The control group was injected with citrate buffer. Histopathology was examined by Alcian blue-Periodic Acid Schiff staining under a light microscope. Image analysis was applied to quantify mucin accumulation. The ultrastructure was explored using transmission electron microscopy. In short-term and long-term DM, there was superficial erosion of the gastric epithelium and a significant decrease in the percentage of mucin granule accumulations in both surface mucous cells (SMCs) and mucous neck cells (MNCs). In short-term DM, SMCs were degenerated with vacuolation, disrupted cristae of mitochondria, and dilated rough endoplasmic reticulum (rER). MNCs were swollen with destroyed organelles. In long-term DM, degenerative nuclei and electron-lucent regions with unidentified structures of SMCs were observed. Nuclear chromatin condensation and the disappearance of mucin granules were present in MNCs. In conclusion, under both LM and TEM, STZ-induced diabetic rats demonstrated both short- and long-term damage to the gastric mucosa and gastric gland structures.

The surface structures and mucus layers that form an interface between the epithelial layer of organisms and their external environment were studied in the bloom-forming moon jellyfish (Aurelia solida, Scyphozoa) from the northern Adriatic. The surface of the polyps revealed epithelial ciliated cells and numerous nematocysts, both non-discharged and discharged. Cilia were also the most prominent features on the surface of adult medusa, protruding from the epidermal cells and with microvilli surrounding the base. Histochemical methods and various microscopy techniques (light/epifluorescence and electron microscopy) confirmed the presence of abundant mucus around polyps and on the surfaces of adult medusa, and that the mucus contained acidic and neutral mucins. The observed mucus secretions on the exumbrella surface of the medusae were in the form of granules, flocs, and sheets. Scanning electron microscopy and transmission electron microscopy analyses confirmed the presence of various microbes in the mucus samples, but not on the epithelial surfaces of the polyps or the exumbrella of the medusae.

Skin mucus is a non-lethal and low-invasive matrix appropriate to assess fish welfare as it contributes to their defence against external aggressions and reflects changes in fish health status. However, more information on the response of this matrix to specific stressors is needed. In this study, rainbow trout (Oncorhynchus mykiss) specimens were subjected to an acute stress by air exposure and sampled after 1, 6, and 24 h post-stress. Blood and skin mucus were collected, and a battery of biochemical biomarkers were measured in both matrices. Cortisol and glucose values showed the expected classical stress response in plasma, increasing after the acute stress. The same pattern was observed in skin mucus, corroborating previous data in fish, and allowing us to confirm that skin mucus can be a useful complementary matrix for stress assessment in fish. The results showed sensitivity to hypoxic stress in skin mucus for cortisol, glucose, alkaline phosphatase (ALP), aspartate transaminase (AST), alanine aminotransferase (ALT), creatinine kinase (CK), and calcium. From the 15 parameters evaluated, 12 did not show statistically significant changes between plasma and mucus; therefore, using skin mucus cannot replace the use of plasma. Finally, the principal component analysis in skin mucus revealed a complete separation between the two experimental groups, being ALP, AST, glucose, cortisol, and CK, the biomarkers that contributed the most to this separation.

Alors que les poissons téléostéens représentent les deux tiers des vertébrés marins, l'interaction entre leur microbiote externe et leur environnement reste peu étudié, en particulier chez les populations sauvages. Ainsi, le lien entre le microbiote et les ectoparasites n'est pas bien compris. Le microbiote peut agir comme une barrière protectrice contre les pathogènes et/ou être impliqué dans la reconnaissance de l'hôte par les parasites. Les associations hôte-parasite devraient désormais être considérées comme des interactions tripartites où le microbiote façonne le phénotype de l'hôte et sa relation avec les parasites. Ces interactions ont déjà été décrites chez certaines espèces de téléostéens qui peuvent être parasitées par des monogènes (Plathelminthes) qui sont des ectoparasites à cycle de vie direct que l'on trouve couramment sur leur peau et leurs branchies. Leurs larves nagent activement, s'orientent et repèrent leur hôte grâce à des stimuli chimiques. Les communautés bactériennes sont soupçonnées de contribuer à la production de ces signaux et pourraient donc jouer un rôle important dans les mécanismes de spécificité parasitaire.L'objectif de cette thèse était d'explorer les mécanismes qui sous-tendent la spécificité des monogènes pour leur(s) hôte(s) en caractérisant le microbiote, la composition chimique du mucus externe des téléostéens (peau et branchies), et en développant des approches expérimentales pour mieux caractériser le rôle des stades précoces des Lamellodiscus dans cette spécificité. Nous nous sommes concentrés sur l'association entre les Sparidae, une famille de poissons retrouvée en Méditerranée, et les monogènes du genre Lamellodiscus qui présentent des profils de spécificité variés pour leurs hôtes.Au cours de cette thèse, nous avons tout d'abord (i) étudié l'évolution des communautés bactériennes du mucus externe de deux espèces sauvages de sparidés présentant des charges parasitaires en Lamellodiscus contrastées. Nous avons ensuite (ii) caractérisé les communautés bactériennes et la composition chimique du mucus externe de quatre espèces de sparidés sauvages et étudié l'influence de différents facteurs sur leur variabilité (environnementaux ou propres à l'hôte). Nous nous sommes ensuite concentrés sur une espèce qui n'est jamais parasitée par les monogènes du genre Lamellodiscus. Nous avons exploré si cette espèce se distinguait des trois autres par une signature bactérienne et chimique particulière qui pourrait expliquer sa protection vis à vis des Lamellodiscus. Enfin, l'objectif de la dernière partie (iii) était de développer des approches expérimentales pour comprendre quels facteurs sont susceptibles de favoriser l'établissement et le maintien des différents stades de vie du parasite sur son hôte. Un système non-invasif de collecte d'œufs de Lamellodiscus a d'abord été développé. À partir de là, nous avons pu établir des conditions optimales de maintien in vitro d'œuf de Lamellodiscus pour favoriser leur éclosion. Nous avons, alors, réalisé une première caractérisation morphologique des stades de vie précoces d'une espèce de Lamellodiscus à l'aide de microscopie optique et électronique à balayage. En parallèle, nous avons développé une méthode pour, à terme, étudier le comportement et la préférence larvaire pour des mucus de différentes espèces de sparidés
While teleost fishes represent two-third of all marine vertebrates, the interaction between their external microbiota and their environment remains poorly studied, especially for wild populations. Hence, the role of their microbiota in relationship with ectoparasites is largely unknown. Microbiota can act as a protective barrier against pathogens, and/or be involved in host recognition by parasites, and host-parasite associations should be considered as a tripartite interplay where the microbiota shapes the host phenotype and its relation to parasites. These interactions have already been described in some teleost species that can be parasitized by Monogeneans (Platyhelminthes) which are direct life cycle ectoparasites commonly found on their skin and gills. Their larvae actively swim towards their host based on chemical stimuli. Bacterial communities are suspected to contribute to these cues and could play a significant role in host-parasite specificity mechanisms.The objective of this thesis was to explore the mechanisms involved in the specificity of monogenean for their host(s) through the characterization of wild teleost external mucus (skin and gills) microbiota and metabolite production and the development of experimental approaches to better characterize the role of early life stages of Lamellodiscus in host specificity. We used as biological model a well-known association formed by Sparidae, a fish family found in Mediterranean Sea, and Lamellodiscus monogeneans, a species-rich genus that exhibits various patterns of host specificity.During this thesis, we first (i) studied the evolution of bacterial communities in the external mucus of two wild sparid species with contrasting Lamellodiscus monogeneans parasitic loads. We have then (ii) characterized the bacterial communities and chemical composition of the external mucus of four wild sparid species and studied the influence of different environmental or host-specific factors on their variability. One of these species, never parasitized by the Lamellodiscus monogeneans, was especially studied to determine whether it has a distinct bacterial and chemical signature that could explain its protection against Lamellodiscus. The objective of the last part (iii) was to develop experimental approaches to investigate the factors that promote the establishment and maintenance of different life stages of monogeneans on their host. A non-invasive system was developed for collecting Lamellodiscus eggs in aquariums. From there, we cultured larvae in vitro by establishing optimal conditions to maintain Lamellodiscus eggs and induce their hatching. We conducted an initial morphological characterization of the early stages of a Lamellodiscus species using light and scanning electron microscopy. We have, in parallel, developed a method to ultimately study in vitro oncomiracidia behavior and preference for mucus from different sparid species

Masters of Science
There is a need for defined models of human nutritional disorders partly because serious misconceptions about models are common amongst researchers. Historically a large variety of species has been used including primates, pigs, rats, lagomorphs. Advantages various small carnivores and and disadvantages are not well known and availability is a major factor. In 1753 John Hunter used pigs to study bone growth in one of the first scientifically controlled nutrition experiments (Kobler 1960). Rats were most likely the first animals to be bred specifically for scientific purposes and there is evidence that they were used in nutrition experiments during the late eighteenth century (Kobler 1960). Experience with carcinogenesis in animals has shown the great diversity of results which may possibly be obtained from different species (Lave et al. 1988). This is pertinent to nutritional research as there is an established link between diet and cancer. The selection of a suitable substitute to attempt to model possible human response to a variety of procedures is dependent upon criteria among which the following are possibly the more important. Availability; this is of great importance in Southern Africa where the cost of importation of exotic species. must be taken into account. Du Plessis (1981) referred to the fact that our indigenous primates were a valuable resource. A second consideration must be the cost the selected animal in a scientifically acceptable environment. Keeping animals of maintaining and ethically for research purposes in an uncontrolled environment could well lead to erroneous conclusions being made. Thirdly the cost of a research program in which animals are used may be increased if there is insufficient knowledge of the model selected. A paucity of knowledge available about an animal may affect the viability of an experiment. The need for precise information regarding the effects of extended term dietary supplementation of experimental animals has been noted by Fincham et. al. (1987) . Additionally the selected animal should preferably have similar dietary requirements to man, and have a life span which will enable extended term investigations.

Urticaria is an inflammatory complaint characterized by short-lived skin swellings termed ‘wheals’ or ‘hives’. It can be divided into acute urticaria, where the disease has an abrupt onset, and chronic urticaria, where wheals have occurred on a regular basis for over 6 weeks. Physical urticaria is a subgroup of chronic urticaria where an underlying external/physical trigger can be identified, while contact urticaria arises from contact with a chemical substance on the skin or mucous membranes. Angiooedema represents a similar process affecting the deeper dermal tissue and has a predilection for the skin around the eyes and mouth. It may occur in association with urticaria or as an isolated complaint.

Abstract Normally, for conception to occur in vivo spermatozoa must be deposited at the site of insemination around the external cervical os at a time when the cervical mucus is receptive to penetration by spermatozoa. This initial process of sperm-cervical mucus interaction is an essential first step in the complex series of events that take place in the relatively inaccessible female tract resulting in the production of a zygote which, hopefully, will implant and develop into a new individual. Consequently, its assessment is an integral part of the diagnostic workup of an infertile couple, and the various techniques available are described in this chapter.

The nasal cavity is the entrance to the respiratory tract. Its functions are to clean, warm, and humidify air as it is inhaled. Respiratory mucosa covered by pseudostratified ciliated epithelium and goblet cells, as described in Chapter 5 and illustrated in Figure 5.2B, lines the majority of the nasal cavity. The cilia and mucus trap particles, thus cleaning the air; the mucus also humidifies the air and warming is achieved through heat exchange from blood in the very vascular mucosa. The efficiency of all these processes is increased by expanding the surface of the nasal cavity by folds of bone. The nasal cavity also houses the olfactory mucosa for the special sense of olfaction although the olfactory mucosa occupies a very small proportion of the surface of the nasal cavity. The nasal cavity extends from the nostrils on the lower aspect of the external nose to the two posterior nasal apertures between the medial pterygoid plates where it is in continuation with the nasopharynx. Bear in mind that in dried or model skulls, the nasal cavity is smaller from front to back and the anterior nasal apertures seem extremely large because the cartilaginous skeleton of the external nose is lost during preparation of dried skulls. As you can see in Figure 27.1 , the nasal cavity extends vertically from the cribriform plate of the ethmoid at about the level of the orbital roof above to the palate, separating it from the oral cavity below. Figure 27.1 also shows that the nasal cavity is relatively narrow from side to side, especially in its upper part between the two orbits and widens where it sits between the right and left sides of the upper jaw below the orbits. The nasal cavity is completely divided into right and left compartments by the nasal septum . From the anterior view seen in Figure 27.1 , you can see that the surface area of lateral walls of the nasal cavity are extended by the three folds of bone, the nasal conchae. The skeleton of the external nose shown in Figure 27.2 comprises the nasal bones, the upper and lower nasal cartilages, the septal cartilage, and the cartilaginous part of the nasal septum.

The external nose is pyramidal and consists of a bony cartilaginous framework. The root/radix is continuous with the forehead an inferiorly terminates at the nasal tip. The dorsum of the nose is formed by two lateral surfaces that converge in the midline. The cartilaginous structure of the nose is formed by paired upper (lateral) cartilages that contribute to the internal nasal valve with the nasal bones, and lower lateral cartilages, combined with additional minor nasal cartilages that surround the ala. The nasal septum relies upon anastomoses from five vessels: two from the ophthalmic, two from the maxillary and one from the facial. Collectively, they form Kieselbach’s plexus. The paranasal sinuses are the frontal, sphenoidal, ethmoidal and maxillary – located within the bones of the same name. They are paired structures lined with mucosa that is continuous with the lateral nasal side wall into which they drain, facilitating clearance of mucus by way of the mucociliary escalator.

Urinalysis simply means analysis of urine. It is an easily performed investigation that can detect a wide variety of abnormalities within a few minutes at low cost. Urinalysis is an investigation which all nurses should be competent to perform and is identified by the NMC (2007) as being an example of an essential skill nurse students should be competent to perform before entering their branch programme. Urinalysis may be performed in a wide variety of clinical settings. It should be performed on every patient entering the acute care setting. Additionally, the National Confidential Enquiry into Patient Outcome and Death (NCEPOD (2009), stresses the need for urinalysis to be performed on all emergency admissions to an acute hospital. It may also be performed in outpatient and general practice clinics, and community areas. To obtain the most accurate information from the test, students need to know how to obtain and assess a sample of urine and be aware of factors that may influence the reliability of the investigation. Urine may be tested in three different ways. ● Macroscopic urinalysis, ● Microscopic urinalysis, ● Chemical analysis. Macroscopic and chemical analysis are the investigations performed in the clinical setting which may be tested by OSCE. Microscopic investigation requires samples to be sent to a laboratory. Macroscopic analysis is the analysis of the urine by the naked eye. Chemical analysis may be performed by use of a plastic diagnostic reagent strip or ‘dipstick’ which contains small pads of chemicals which react to substances that may be found in urine. For purposes of testing urine at random, clients are asked to urinate into a clean but not sterile dry container with no precautions regarding contamination. In females in particular this may result in samples being contaminated by vaginal fluids, such as blood or mucus. Due to the risk of contamination a mid-stream specimen of urine may be required if an abnormality is found in a random sample. A mid-stream specimen requires cleaning of the external urethral meatus prior to urination, passing the first half of the bladder contents into the lavatory, and passing the second part of the urine flow into a sterile container.

The delicate yet definitive deflections of the pinna (wing/fin) of the external ear contribute to the collection of sound. The external acoustic meatus is responsible for the transmission of sounds to the tympanic membrane, which in turn separates the external ear from the middle ear. The middle ear is an air filled (from the nasopharynx via the eustachian tube), mucous membrane lined space in the petrous temporal bone. It is separated from the inner ear by the medial wall of the tympanic cavity – bridged by the trio of ossicles. The inner ear refers to the bony and membranous labyrinth and their respective contents. The osseus labyrinth lies within the petrous temporal bone. It consists of the cochlea anteriorly, semicircular canals posterosuperiorly and intervening vestibule – the entrance hall to the inner ear whose lateral wall bears the oval window occupied by the stapes footplate.

Abstract Most recently, the physiology of the salivary glands has especially foregrounded, within their functioning, certain phenomena which are usually called psychic. The latest research on the salivary glands by Glinski?, Vul’fson, Henri and Malloizel, and Borisov has revealed a most perfect adaptability of these glands to external stimulations, as had already been anticipated by Claude Bernard. In response to food that gets into the mouth and is hard and dry, the salivary glands release great quantities of saliva, and mixing with it allows such food to realize its chemical properties and helps its mechanical processing, thus aiding its passage through the esophagus into the stomach. In contrast, saliva is produced in much smaller quantities when the food contains a lot of free water, and less saliva is produced the higher the water content. To be sure, milk causes a decent amount of saliva to flow, but it should be kept in mind that the addition of mucous saliva to milk prevents, by virtue of the mucous layering, the formation in the stomach of a large compact curd mass, and by this it facilitates the digestive effect of gastric juice on the milk. In response to water or to a physiological saline solution, no salivation occurs at all, as saliva is of no use to them. When strong chemical irritants are introduced into the mouth, saliva always flows in quantities strictly proportional to the irritating strength of these substances.

There are three paired major salivary glands of the head and neck, all named according to their location and each contributing to saliva and enzyme production via their respective ducts to assist with mastication and digestion. At rest, the lion’s share (60%) of saliva production is from the submandibular glands. On stimulation, the parotid contribution increases from 20% to 50%. There are up to 1000 minor salivary glands found within the submucosa of the oral cavity – 1-2mm in size and predominantly mucous in nature. The parotid glands are irregular shaped masses of lobulated tissue situated on the side of the face, reaching from the zygomatic arch superiorly to the upper part of the neck inferiorly where they overly the posterior belly of digastric and upper sternocleidomastoid muscle. Anteriorly, the gland lies between the posterior border of the mandibular ramus before continuing below the external acoustic meatus towards the mastoid process posteriorly.

Abstract Lohmann (1898, 1899, 1909a, 1933) was the first investigator to recognize the true function of the appendicularian house, which is to concentrate and collect particulate matter from the sea for feeding. He examined the gut contents of Oikopleura albicans and in this way identified an entirely new size class of plankton in the sea, which he called ‘nanoplankton’ (Lohmann, 1909a). The structure of the house is described in detail in Chapter 6; it is remarkably complex and its operation is only well understood in detail in a few oikopleurid species, and less well in a single fritillariid. Essentially, there are in oikopleurids usually three filters involved in food collection; their structure determining the size class of particles a given species can feed upon. The inhalent flow produced by oscillation of the tail draws water into the house via an external relatively coarse filter, then a food collecting filter or trap concentrates particulate material, which is drawn along a short tube to the mouth by the action of spiracular cilia. After entering the pharynx, the particles are trapped on a mucous filter and they enter the oesophagus.

Normal physiologic mechanisms of the upper eyelid are essential for preservation of the eye. Normal function and good cosmesis usually go hand in hand, but preservation of function is the more important of the two priorities. The general considerations in choosing a reconstruction technique include the restoration of: 1. A smooth conjunctival surface to line the eyelid and protect the cornea 2. Structural support of the tarsal plate 3. A smooth, nonabrasive lid margin 4. Normal vertical eyelid movement without ptosis or lagophthalmos 5. Normal horizontal tension with normal medial and lateral canthal tendon positions To cover small defects, the conjunctival lining may be rotated or advanced. For larger defects, the lining may be replaced with a buccal mucous membrane graft or a contralateral conjunctival graft. The tarsal plate usually requires 4 mm of vertical height to provide adequate eyelid support. If the 4 mm is unavailable, it may be replaced with lower lid tarsus, a free tarsal graft from the opposite lid, a free cartilage graft, a polytetrafluoroethylene graft, or a preserved sclera graft. The eyelid margin must be free of trichiasis or surface epithelium, which might abrade the cornea. When levator function is preserved following traumatic or surgical defects of the eyelid, ptosis can usually be avoided or corrected. The levator aponeurosis separates the orbital and palpebral portions of the lacrimal gland, and lacrimal tissue should be preserved when dissecting in the lateral canthal, lateral levator, and lateral anterior orbital areas. Lagophthalmos of the upper eyelid is usually due either to adhesion of the orbital septum to the tarsal plate or to external vertical skin shortage. Proper horizontal tension can be achieved by measuring full-thickness defects while gently pulling the edges of the defect toward each other. Careful measurement reduces the risk of excessive or deficient horizontal length following reconstruction. Skin grafts in the upper eyelids should be covered with a moderate pressure dressing for 4 to 6 days to prevent buckling or subgraft hematoma. Full-thickness skin grafts are preferred to split-thickness grafts for optimal tissue match and coloration. Upper eyelid sutures may be permanent or absorbable. Most external permanent sutures are 7-0 caliber.

Pollution is the adverse alteration of the physical, chemical, and/or biological characteristics of air, water, or soil brought on by the presence of an excessive amount of different contaminants known as pollutants. Pollutants are dangerous substances that can be either foreign chemicals, energies, or contaminants that occur naturally. Both substances and energies can be considered forms of pollution. Air pollutants are separated into primary and secondary categories depending on whether they are directly released from the source or are formed by the reaction of primary pollutants with other species. They can be generated as the result of various human activities or natural events, and the same is true for water pollution. Many of the anthropogenic activities like transportation, and the various vehicles - autos and buses- by-products released are carbon monoxide, oxides of nitrogen, and particulate matter that can pollute the air. Natural processes can also release their specific contaminant like volcanic eruption (SO2, CO, Fine PM), biogenic emissions (VOCs, terpenes, isoprenes, pollen) and cause air as well as other types of pollution. The second classification is based on the physical characteristics of the pollutant; the first in this are gases such as carbon monoxide, ozone, nitrogen oxides, and sulphur; the second includes particulate matter (PM), such as carbon black, and heavier hydrocarbons which are in form of aerosols, suspensions of liquid and solid particles in the atmosphere. Numerous antigens with a proteinaceous nature that are mostly airborne and known as aeroallergens are also pollutants that might result in allergic responses. They can be produced by household dust, pets, medications, food, pollens, fungi, and mite products. Additionally, these goods contain the antigens absorbed and transported by organic or inorganic dust particles. The concentration of pollutants in the natural environment is increasing at alarming rates, which is not good for both human and animal health. Both internal and external bodily parts may be impacted by them. This could eventually lead to the slow deterioration of these organs. Proper maintenance on a regular basis must be carried out in order to maintain the proper health of the body's external parts. The pollutants may get deposit filth on the skin, and some chemicals may even reach the deeper layers of the skin. Human skin's protective barriers may be reduced as a result of their presence. This can also result in issues of the skin like pigmentation, tone patches, dullness, and wrinkle development, leading to premature aging of the skin. The water contains some extra pollutants also namely pathogens, poisonous minerals, and dead and decomposing things present in greater amounts and can therefore have a more impact if they come into touch with skin. The penetration of air pollutants through the epidermis and pores is more prominent due to the majority of these components being in liquid form. Various cosmetic preparations can be used for this purpose. According to EU Regulation 1223/2009, “Cosmetic product means any substance or mixture intended to be placed in contact with the external parts of the human body (epidermis, hair system, nail, lips, and external genital organs) or with the teeth and the mucous membranes of the oral cavity with the view exclusively or mainly to cleaning them, perfuming them, changing their appearance, protecting them, keeping them in good condition or correcting body odours”. Cosmetic products are classified as leave-on or wash-off products. The products containing natural ingredients available now are superior to fully synthetic products. Thus, switching from chemicals to natural products that contain some inert components can be can help effectively achieve the goal. Several patents have also been granted for cosmetic products of natural origin. The main strategy should be to deep clean, provide complete protection, protect against attacks and restore proper function. A better understanding of pollutants and their mechanisms of action on the body has led to the development of better products

Colorectal cancer (CRC) is nowadays one of the deadliest cancer but the high surviving rate is achievable if the disease is diagnosticated and treated at the early stage. However, the standard procedure represents a discomfortable treatment for many patients at the point that many are discouraged in undergoing routine screening program. In fact, the clinician has to insert and guide by hand a semi-flexible tubular colonoscope and might apply significant forces and torques on the colon walls, with the complications of creating loops in the intestine, tissue damage or even perforation. For this reason, research in capsule robotic colonoscopy is in high demand [1]; the main objective of robotics in this field is to design a system capable of navigating inside the large intestine in order to provide visual inspection of the lumen, possibly, carrying surgical tools required in the colonoscopy procedure, i.e. polypectomy, without the creation of large pushing forces and loops. Human colon is about 130 cm long and composed by 4 consecutive tracts, joint at different angles, named sigmoid, descending, transverse and ascending colon. The diameter the tubular organ can changes from 25 mm to 70 mm, reaching up to 80 mm if insufflated with CO2 gas, often adopted in colonoscopy. Nonetheless, colon wall is a multilayers membrane that consists of four main layers (mucosa, submucosa, muscularis externa and serosa) which makes the membrane very compliant to large deformation and very slippery, being the internal wall of the colon characterized by continuous secretion of mucus Due to both the morphology and the frictional behaviour of the colon, the design of robots that are able to crawl the intestine and perform the screening of the organ is a challenge. Various locomotion strategies for micro robotic devices have been explored, such active capsules inspired by bio-mimetic locomotion strategies, such insect or caterpillar, or by use of locomoting members to self- propel once inside the colon such wheels or tracks [2]. Nonetheless, current robotic solutions are still far away to replace the standard colonoscopy due to the challenges in integrating reliable locomotion strategy in small size robots able to face the complex environment represented by the colon. In this work, we discuss the design and the features of the SOFTScreen system [3], discussing the testing of its locomotion capability inside a silicone phantom resembling the colon surface.