Chemistries of Chemical Warfare Agents
Brian J. Lukey, James A. Romano, Salem Harry in Chemical Warfare Agents, 2019
The first large-scale development, manufacture, and use of CWAs was during World War I. During the war, the chemicals were deliberately released on the battlefield as slow-moving poisonous gas clouds toward entrenched adversary troops to facilitate their demoralization, injury, and death. The types of weapons employed ranged from disabling chemicals, such as tear agents, to lethal agents, such as phosgene, chlorine, and sulfur mustard. The chemistries of seven such chemical weapons are detailed in this section and are ordered according to their intended military-specific use as choking, blood, blister, or tear agents. Choking or pulmonary agents are substances designed to impede a victim’s ability to breathe by causing a build-up of fluids in the lungs, which then leads to suffocation. Blood agents are compounds that are absorbed into the blood and inhibit the ability of blood cells to use and transfer oxygen, ultimately leading to suffocation as with choking agents. Blister agents, or vesicants, cause severe chemical burns, resulting in large, painful water blisters at the affected area. The inhalation of blister agents can lead to blister formation in the respiratory tract, which in extensive cases, can also result in death by suffocation. Finally, tear agents, or lachrymators, are compounds that cause severe eye, respiratory, and skin irritation, pain, bleeding, and even blindness. In the eyes, tear agents stimulate the nerves of the lacrimal gland to produce tears. Today, these agents are sometimes used as riot control agents.
Head and Neck
Rui Diogo, Drew M. Noden, Christopher M. Smith, Julia Molnar, Julia C. Boughner, Claudia Barrocas, Joana Bruno in Understanding Human Anatomy and Pathology, 2018
The oculomotor nerve (CN III) (Plates 3.15 and 3.33; described in detail in Section 3.3.1.3) carries with it preganglionic parasympathetic fibers. These fibers synapse on cells in the ciliary ganglion, which is found between the optic nerve (CN II) and the lateral rectus muscle. The postganglionic fibers connect to the eyeball via short ciliary nerves and project to the smooth muscles of the sphincter pupillae and the ciliary body (Plate 3.20). Some sensory fibers from the nasociliary nerve and some postganglionic sympathetic fibers also pass through the ciliary ganglion on their way to the eyeball, but they do not synapse there. The lacrimal nerve also carries with it some parasympathetic fibers, but these are postganglionic fibers from the pterygopalatine ganglion, which receives input from the greater petrosal branch of the facial nerve. These fibers activate the lacrimal gland to produce tears.
Lacrimal Disorders in Children
John C Watkinson, Raymond W Clarke, Christopher P Aldren, Doris-Eva Bamiou, Raymond W Clarke, Richard M Irving, Haytham Kubba, Shakeel R Saeed in Paediatrics, The Ear, Skull Base, 2018
The lacrimal system consists of a secretory portion and a drainage system. The secretory portion is made up of the lacrimal and accessory lacrimal glands which, together with the Meibomian glands and the goblet cells, secrete the components of the tear ï¬lm. The accessory lacrimal glands produce basal tear secretion, and the lacrimal gland is largely responsible for reflex tearing in response to noxious or emotional stimuli. The drainage system consists of the lacrimal puncta, canaliculi, lacrimal sac and nasolacrimal duct (Figure 25.1). This active system pumps tears from the conjunctival sac into the inferior meatus of the nose. Clinical problems with the lacrimal system in children usually relate to the reduced drainage of tears. The underproduction of tears, causing dry eyes, is rare but more serious due to the potential for sight-threatening consequences.
Radiation-induced damage to lacrimal glands: an ultrastructural study in Sprague Dawley rats
Published in Ultrastructural Pathology, 2018
Refaat A. Eid, Mubarak Al-Shraim, Yahya Al-Falki, Ahmed Al-Emam, Nasser A. Alsabaani, Khaled Radad
Lacrimal glands develop from an outpouching of the conjunctiva and locate superotemporally in the orbits within the lacrimal fossae of the frontal bone. They are exocrine glands of serous type that release their secretion directly onto the eyeball. Lacrimal glands contribute many components in the tear film that are important to the ocular surface health including: (i) aqueous fluid that keeps the ocular surface moist, maintains an important component of light refraction in the air-water-corneal interface, and dilutes proteins within the tears,1 (ii) soluble mucin that acts to clear debris and hold fluid on the eye surface,2,3 (iii) growth factors that promote proliferation and migration of epithelial cells following disruption of corneal epithelium,4 (iv) a vitamin A derivative, retinol, which is beneficial in maintaining conjunctival goblet cells and in controlling corneal epithelial desquamation, keratinization, and metaplasia,5 (v) several bactericidal (phospholipase A2) and fungicidal (lysozymes, perioxidase, psoriasin, and lactoferin) agents,6,7 and (vi) IgA by the secretory plasma cells residing within the lacrimal gland.1
Towards Lacrimal Gland Regeneration: Current Concepts and Experimental Approaches
Published in Current Eye Research, 2020
Jana Dietrich, Stefan Schrader
Another idea is the administration of eye drops that stimulate/increase tear secretion of the remaining functional lacrimal gland tissue to circumvent complex tissue regeneration. Although this concept does not aim at the regeneration of lacrimal gland, it could be beneficial as it fulfills the most of the other postulated requirements for a promising therapy (see above) and provides interesting results. The administration of pituitary adenylate cyclase-activating polypeptide (PACAP) containing eye drops increased the tear secretion in wild type and PACAP-null mice in a time-dependent manner.54 It was shown that PACAP induces the trafficking of aquaporin 5 from the cytosol to the apical membrane of acinar cells and thereby increase fluid secretion. When eye drops were administered twice daily for three weeks ocular surface damage was attenuated in APCAP-null mice. However, whether PACAP eye drops would also be beneficial in established ADDE mouse models needs to be investigated.
Bio-chemical markers of chronic, non-infectious disease in the human tear film
Published in Clinical and Experimental Optometry, 2022
Sultan Alotaibi, Maria Markoulli, Jerome Ozkan, Eric Papas
At a biochemical level, tears contain over 1800 proteins, metabolites, and electrolytes, which are mainly secreted by the lacrimal gland and conjunctival epithelium.1 In addition, various cell types, for example, neutrophils and sloughed epithelial cells, may be present, as well as residues from cellular activity, such as cytokines and ribonucleic acid (RNA). Many of these components can become up- or down-regulated during inflammation and disease2,3 leading to the idea that monitoring changes in the tear film may offer insights into underlying ocular or systemic conditions. Certainly, tears have an advantage over several other bodily fluids, such as serum or cerebrospinal fluid assay, in that they can be repeatedly and non-invasively collected using low-cost, painless and readily available methods.4,5
Related Knowledge Centers
- Dacryoadenitis
- Exocrine Gland
- Eye
- Eyelid
- Lacrimal Punctum
- Lacrimal Sac
- Nasolacrimal Duct
- Tears
- Orbit
- Fossa For Lacrimal Gland