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Biomedical subjects

C R Dawson

Publications and source records attributed to C R Dawson.

14 recordsLinked to original sources
PubMed1979

Is trachoma an ocular component of a more generalised chlamydial infection?

In industrialised countries, inclusion conjunctivitis of the newborn is now known to be just one manifestation of a more generalised infection with Chlamydia trachomatis. Pneumonia and enteric infection can develop in perinatally infected infants. It is possible that trachoma in developing countries may reflect extraocular infection that may contribute to the high frequency of pneumonia and diarrhoea in infants in these countries. If true, this would explain the short-term effects of topical treatment, since children could reinfect their eyes by autoinoculation from other sites. Thus systemic treatment with macrolides would result in benefits beyond the temporary suppression of eye disease.

Administration, Oral↗
PubMed1979

Herpetic eye disease in rabbits after inoculation of autonomic ganglia.

Since herpes simplex virus (HSV) can cause persistent infection of autonomic ganglia of both humans and experimentally infected animals, we followed the pattern of eye disease and viral growth after HSV inoculation of one superior cervical ganglion in rabbits. Of 27 inoculated animals, eye disease or detectable virus developed in 18. Anterior uveitis was the most common clinical manifestation (94%), but conjunctivitis and dendritic keratitis were also frequent (60%). All 12 uveal-retinal specimens tested and five of seven ipsilateral superior cervical ganglia had detectable virus. If recurrent herpetic iritis in humans is associated with persistent infection of the superior cervical ganglion, autonomic mediators might trigger episodes of virus shedding. In patients with herpetic iritis, then, the use of epinephrine and other adrenergic agonists or antagonists should be avoided.

Animals↗
PubMed1979

Purulent ocular discharge in neonates: significance of Chlamydia trachomatis.

We obtained cultures for bacteria and chlamydiae from 100 infants with conjunctivitis that began during the first month of life. Sixty-nine infants were evaluated during well-child visits (group A); 31 were seen specifically for the ocular discharge (group B). Potentially pathogenic bacteria, predominantly Staphylococcus aureus, were cultured from one third of the infants in each group. Chlamydia trachomatis was recovered from three infants (4%) in group A and from ten (32%) in group B. Three infants with chlamydial conjunctivitis (two in group A, one in group B) had only mild inflammation. Initial treatment with topical antibiotics was unsuccessful in eliminating the organism from seven of 11 infants.

Conjunctivitis↗
PubMed1978

The use of cycloheximide-treated cells for isolating trachoma agents under field conditions.

Standard procedures for the isolation of Chlamydia trachomatis require pretreatment of the tissue culture cells. We evaluated the use of cycloheximide, an antimetabolite that can be added to the cells with the inoculum. Cycloheximide-treated cells provided a sensitive system for isolating trachoma agents. This system was applicable to field studies as requirements for equipment were minimal and the cells were 2 weeks old when inoculated.

Chlamydia trachomatis↗
PubMed1977

Herpesvirus in sensory and autonomic ganglia after eye infection.

In herpesvirus hominis (HVH) infections, virus harbored in the sensory ganglia is now thought to be the main source of recurrent infection at peripheral sites. Experimental HVH infection of the external eye in rabbits produces an acute infection and then latent infection of the trigeminal ganglion. In this study, acute infection of the automatic ganglia serving the eye (superior cervical and ciliary) as well as trigeminal ganglia occurred after HVH inoculation of rabbits' corneas with a herpes type 1 strain (RE). Latent virus infection was detected in the trigeminal ganglion of one of five animals tested six months after initial infection. Since the superior cervical and other autonomic ganglia serving the eye become infected during acute herpes simplex virus infection of the external eye in rabbits, it is possible that these ganglia are also sources of reinfection in recurrent herpetic disease of the eye. Following the initial eye disease with this virus strain, HVH shedding could not be demonstrated even after induction attempts by topically applied epinephrine or systemic use of cyclophosphamide. Thus, establishment of latent HVH infection in the ganglia and chronic shedding of virus into the external eye is not a constant feature of this animal model, but may depend on the specific strain of herpesvirus used.

Animals↗
PubMed1975

Cytology as a guide to the presence of chlamydial inclusions in Giemsa-stained conjunctival smears in severe endemic trachoma.

Microscopical examination of 927 Giemsa-stained conjunctival smears from children with chronic trachoma in southern Tunisia showed 93 (10 per cent.) with typical trachoma (chlamydial) inclusions in epithelial cells. The accompanying cytological features were a useful indicator for inclusions. Inclusions were found only in slides with numerous polymorphonuclear neutrophils (PMNs) and separation of the epithelial cells. When these two features alone were present, 3 per cent. of the smears were inclusion-positive; when many lymphocytes were present also, 25 per cent. were inclusion positive; when other cytological features (plasma cells, macrophages, blastoid, and stem cells) were present as well, 70 per cent. of the smears were inclusion-positive. The occurrence of these sets of cytological features can be a useful guide for selecting smears for intensive examination for chlamydial inclusions. Immunofluorescent (FA) staining and Giemsa staining of 527 pairs of matched smears detected trachoma agent in 67 (13 per cent.); in thirty by both methods, in thirteen by Giemsa staining alone, and in 24 by FA alone. The examination of Giemsa-stained smears for chlamydial inclusions is a useful technique for the diagnosis of trachoma or inclusion conjunctivitis by laboratories that do not have the specialized facilities for the identification of these chlamydial infections by the technically more complex procedures of immunofluorescent staining or isolation in embryonated eggs or tissue cultures.

Bacteria↗
PubMedDate not supplied

Oculogenital transmission of type 2 herpes simplex virus in adults.

Type 2 (genital) herpes simplex virus (HSV-2) was isolated from three patients (two adults and an 11-year-old girl) with acute ocular infections. Two of these patients had acute blepharoconjunctivitis and one had acute keratoconjunctivitis. Genital herpes infections had preceded the eye infections in the two adults. This was not the case in the 11-year-old, but she had been in close contact with her sister who had apparently had the genital disease. The study strongly suggests transmission of HSV-2 from the genital site to the eye.

Adolescent↗