Saliva

Saliva (commonly referred to as spit) is an extracellular fluid produced and secreted by salivary glands in the mouth. In humans, saliva is around 99% water, plus electrolytes, mucus, white blood cells, epithelial cells (from which DNA can be extracted), enzymes (such as lipase and amylase), antimicrobial agents (such as secretory IgA, and lysozymes). The enzymes found in saliva are essential in beginning the process of digestion of dietary starches and fats. These enzymes also play a role in breaking down food particles entrapped within dental crevices, thus protecting teeth from bacterial decay. Saliva also performs a lubricating function, wetting food and permitting the initiation of swallowing, and protecting the oral mucosa from drying out. Various animal species have special uses for saliva that go beyond predigestion. Some swifts use their gummy saliva to build nests. Aerodramus nests form the basis of bird's nest soup. Cobras, vipers, and certain other members of the venom clade hunt with venomous saliva injected by fangs. Some caterpillars produce silk fiber from silk proteins stored in modified salivary glands (which are unrelated to the vertebrate ones). Produced in salivary glands, human saliva comprises 99.5% water, but also contains many important substances, including electrolytes, mucus, antibacterial compounds and various enzymes. Medically, constituents of saliva can noninvasively provide important diagnostic information related to oral and systemic diseases. Water: 99.5% Electrolytes: 2–21 mmol/L sodium (lower than blood plasma) 10–36 mmol/L potassium (higher than plasma) 1.2–2.8 mmol/L calcium (similar to plasma) 0.08–0.5 mmol/L magnesium 5–40 mmol/L chloride (lower than plasma) 25 mmol/L bicarbonate (higher than plasma) 1.4–39 mmol/L phosphate Iodine (mmol/L concentration is usually higher than plasma, but dependent variable according to dietary iodine intake) Mucus (mucus in saliva mainly consists of mucopolysaccharides and glycoproteins) Antibacterial compounds (thiocyanate, hydrogen peroxide, and secretory immunoglobulin A) Epidermal growth factor (EGF) Saliva eliminates caesium, which can substitute for potassium in the cells.

On the durability of surgical masks after simulated handling and wear

Jian Wang, Véronique Michaud, Vincent Marc Varanges, Baris Çaglar, Yann Albert Gérard Lebaupin, René M. Rossi

After the spread of COVID-19, surgical masks became highly recommended to the public. They tend to be handled and used multiple times, which may impact their performance. To evaluate this risk, surgical masks of Type IIR were submitted to four simulated tr ...

2022

Microfluidic devices for automated analysis of ingested bacteria in the Caenorhabditis elegans intestine

On the durability of surgical masks after simulated handling and wear

Microfluidic devices for automated analysis of ingested bacteria in the Caenorhabditis elegans intestine

On the durability of surgical masks after simulated handling and wear