Membrane conjunctival

The eyes are particularly susceptible to Hquids, gases, and some soHds. The conjunctival membrane surrounding the eye is easily irritated. Alkaline materials, eg, hydroxides and amines, destroy the eye tissues rapidly, frequently causiug partial or complete loss of vision. 

Diphtheria is a bacterial respiratory infection characterized by membranous pharyngitis. The membrane may cover the pharynx, tonsillar areas, soft palate, and uvula. Diphtheria may also cause anal, cutaneous, vaginal, and conjunctival infections. The impact of diphtheria is not from the causative bacteria, Corynebacterium diphtheriae, but rather from complications attributed to its exotoxin, such as myocarditis and peripheral... 

Basic hydrodynamic phenomena govern the duration of exposure of corneal and conjunctival membranes to the therapeutic agents. Rapid clearance provides a temporal barrier to drug delivery. 

The permselectivity of the corneal and conjunctival paracellular routes was investigated by Huang et al. [159] in an attempt to show that nutrients can be extracted from the blood by the conjunctiva. Neither the blood vessels supplying the conjunctiva nor its basement membrane are rate-limiting to the transport of horseradish peroxidase. This 40 kDa tracer is restricted underneath the conjuncti-... 

Glanders occurs in both acute and chronic forms. The acute form is inhaled and affects the upper respiratory tract. In nature, the acute form kills infected animals in 3 to 4 weeks. The acute form infects the nasal, oral, and conjunctival mucous membranes, causing blood-streaked discharges from the nose along with nodules and ulcerations. The chronic form affects the joints and lymph as multiple skin nodules begin to ulcerate and are filled with pus. Other symptoms include fever, sweats, myalgia, headache, enlarged spleen, and chest pain. Sometimes pneumonia is present. As few as 1 to 10 bacteria delivered to animals by aerosol can be lethal.3... 

Infection of nasal, oral, or conjunctival mucous membranes Blood-streaked discharge from the nose, nodules, and ulcerations Chronic form ... 

IgE-mediated allergic reactions (p. 72) involve mast cell release of histamine (p. 114) and production of other mediators (such as leukotrienes, p. 196). Resultant responses include relaxation of vascular smooth muscle, as evidenced locally by vasodilation (e.g., conjunctival congestion) or systemically by hypotension (as in anaphylactic shock) enhanced capillary permeability with transudation of fluid into tissues— swelling of conjunctiva and mucous membranes of the upper airways ( hay fever ), cutaneous wheal formation contraction of bronchial smooth muscle-bronchial asthma stimulation of intestinal smooth musde—diarrhea. 

Several species of animals exposed to 3500 ppm suffered marked irritation of the mucous membranes and became incoordinated after 15 minutes of exposure and prostrate after 30 minutes. Conjunctival irritation, lacrimation, salivation, and lethargy were observed in rabbits exposed to 1822 ppm 6 hours/day for 3 weeks. Exposure of mice to 450 ppm for an unspecified time period resulted in severe irritation of the eyes and respiratory tract. ... 

Colic. Pertaining to the colon acute abdominal pain characteristically, intermittent visceral pain with fluctuations corresponding to smooth muscle peristalsis. Conjunctivitis. Inflammation of the delicate membrane that lines the eyelids and covers the exposed surface of the sclera (conjunctiva), generally consisting of conjunctival hyperemia associated with a discharge. 

Natural alkaloids and most tertiary antimuscarinic drugs are well absorbed from the gut and conjunctival membranes. When applied in a suitable vehicle, some (eg, scopolamine) are even absorbed across the skin (transdermal route). In contrast, only 10-30% of a dose of a quaternary antimuscarinic drug is absorbed after oral administration, reflecting the decreased lipid solubility of the charged molecule. 

Phenylephrine is an effective mydriatic agent frequently used to facilitate examination of the retina. It is also a useful decongestant for minor allergic hyperemia and itching of the conjunctival membranes. Sympathomimetics administered as ophthalmic drops are also useful in localizing the lesion in Horner s syndrome. (See An Application of Basic Pharmacology to a Clinical Problem.)... 

Located on the edge of the transparent cornea, it maintains the junction with the opaque sclera. On the level of the epithelium, it is the transition between a multilayer scale-like corneal epithelium and a cylindrical conjunctival epithelium with two cellular bases, with continuity of the basement membranes. At the epithelial level, the cells of the comeal epithelium are gradually replaced by a conjunctival epithelium made of two layers of cylindrical cells accompanied by calyciform cells. 

This technique facilitates the scleral cicatrization and prevents the formation of scleral ulcers but it does not enable the covering of the comeal surface with a normal phenotype comeal epithelium [8]. It does not completely avoid the development of a conjunctival fibrosis or of symblepharons. The formation of sym-blepharons, 28% in Kuckelkom series, is most often recorded within the first three months. This situation may require the realization of a new Tenon s plastics or of a transplant of conjunctiva, nose, or mouth mucous membrane. 

The superficial two to three cell layers of the corneal and conjunctival epithelium are the main barrier for the permeation of topically applied compounds. In this rate-limiting cell layer, the transcellular permeation is dictated by the lipophilicity of the cell membrane whereas the paracellular permeation is limited by the paracellular pore size and density. Vesicular penetration (e.g., receptor- or endocytosis-mediated) of macromolecules across surface epithelium is possible [33], However, the proposed mechanism is energy consuming (e.g., incorporation into pinocytotic vesicles and phagosomes) and thus more feasible in cell lines with abundant intracellular energy sources like corneal endothelium and RPE [34-37]. 

Effect of Absorption Promoters on Conjunctival Membranes and Its Significance. .. 541... 

EFFECT OF ABSORPTION PROMOTERS ON CONJUNCTIVAL MEMBRANES AND ITS SIGNIFICANCE... 

An absorption promoter can control the extent and pathway of the ocular and systemic absorption of instilled drug solution by altering not only the corneal but also the conjunctival drug penetration. Most of the agents discussed above show different effects on the corneal and conjunctival membranes. The different response of corneal and conjunctival barriers to absorption promoters can be exploited and used to control the extent and pathway of the ocular and systemic absorption of drugs instilled into the eye. The mechanism of action of absorption promoters and the barrier properties of membranes are the two factors that define drug permeability. 

Bullous keratopathy is a major complication of cataract surgery. In the past, penetrating keratoplasty was considered the most effective therapy for the symptomatic stage of the disease. Other surgical options have included conjunctival flaps, enucleation (reserved for blind, painful eyes) and, more recently, deep phototherapeutic keratectomy and amniotic membrane transplantation. Medical therapy of bullous keratopathy using hypertonic saline (Nad 5%) has been of marginal benefit due to its relatively weak osmotic effect. 

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