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Biomedical subjects

K A McClellan

Publications and source records attributed to K A McClellan.

At least 19 recordsLinked to original sources
PubMed1992

Nonabsorbable suture material in cataract surgery: a comparison of Novafil and nylon.

We compared the performance of 10-0 Novafil (polybutester, Davis & Geck, American Cyanamid Company, New South Wales, Australia.) with that of 10-0 nylon (Alcon) in 60 patients undergoing extracapsular cataract extraction and implantation of a posterior chamber intraocular lens. A standard technique was used, and the incision was closed with interrupted sutures of either 10-0 Novafil or 10-0 nylon. Length of follow up ranged from 6 to 26 months (average, 15 months). We assessed the intraoperative handling qualities of the suture materials, as well as their effect on wound healing and inflammation. We also compared the surgically-induced astigmatism in the two suture groups over the first 3 postoperative months and then in long-term follow up (average, 15 months). Sutures removed at long-term follow up were examined by scanning electron microscopy (SEM). Both suture materials handled easily at operation and were well tolerated by all patients. There was no significantly different surgically-induced astigmatism in the two suture groups after 12 weeks (P = .962) or during longer follow up (P = .401). SEM confirmed more advanced biodegradation of nylon as compared with Novafil sutures after they had been in place an average of 18 months.

Adult↗
PubMed1991

Long-term comparison of Novafil and nylon in corneoscleral sections.

To compare the long-term degradation of Novafil (polybutester, American Cyanamid Company) and nylon suture material, we examined corneoscleral sections of nine rabbits 23 months after the placement of sutures. Only two nylon sutures remained, one in each wound of two rabbits; all the Novafil sutures were still present. However, examination of the Novafil sutures with scanning electron microscopy revealed signs of disintegration.

Animals↗
PubMed1990

Vision-threatening thyroid orbital disease--the clinical features.

Thyroid orbital disease may threaten sight when acute proptosis causes corneal exposure or when enlarged extraocular muscles cause compressive optic neuropathy. The early clinical signs of thyroid optic neuropathy include loss of colour perception and visual field defects. The onset of thyroid optic neuropathy is difficult to predict and these clinical tests should be included in the routine examination of patients with thyroid orbital disease.

Exophthalmos↗
PubMed1989

Atypical mycobacterial keratitis.

A case of marginal corneal abscess and hypopyon due to Mycobacterium chelonae is presented. Its therapy is described, followed by a brief discussion of atypical mycobacterial keratitis.

Abscess↗
PubMed1989

Vogt-Koyanagi-Harada syndrome--isolation of cloned T cells with specificity for melanocytes and melanoma cells.

The pathogenesis of Vogt-Koyanagi-Harada syndrome is poorly understood. A unifying mechanism for its diverse clinical manifestations affecting central nervous system, eye, integument and auditory system has not been found, although many authors have suggested that the features of the disease are the result of autoimmune responses. We performed immunological studies on two patients with Vogt-Koyanagi-Harada syndrome. In one case antibodies to melanoma cells in cytotoxic assay were detected, which it was thought may indicate the presence of antibodies to melanocytes. In the second patient three clones of interleukin-2-dependent T cells were isolated which appeared to have specificity in both cytotoxic and proliferative assays to cultured normal melanocytes and to three allogeneic melanoma cells. These findings further support a role for autoimmunity to pigmented cells in the pathogenesis of Vogt-Koyanagi-Harada syndrome. However, the precise role of autoimmunity in this disease is yet to be established.

Adolescent↗
PubMed1989

Microbial investigations in keratitis at the Sydney Eye Hospital.

We investigated 107 cases of presumed microbial keratitis amongst patients presenting to the Sydney Eye Hospital between October 1986 and August 1988 to determine the frequency of infection, the common causative organisms and those factors that predispose to corneal infection. We found that 95% of culture-proven cases were caused by bacteria and that Staphylococcus epidermidis and Corynebacterium sp. accounted for 42.5% of these cases. All bacteria (except Staphylococcus epidermidis and Mycobacterium chelonae) were sensitive to gentamicin. In 62.6% of cases, cultures for bacteria and fungi were negative. Retrospective review of the clinical records of these patients showed that herpes simplex virus, contact lens wear, staphylococcal marginal keratitis and recurrent erosion were important causes of keratitis in this group.

Adolescent↗
PubMed1989

Transient corneal changes associated with the use of gold foil electrodes.

The corneas of 50 normal subjects were examined before and after electroretinography performed with gold foil electrodes. Examination included slit-lamp biomicroscopy and staining with sodium fluorescein. All corneas were normal on examination prior to electroretinography. Three types of transient corneal changes were observed--punctate epithelial keratitis, corneal erosions, and stromal thinning. Each cornea was assigned a numerical damage score based on a simple scoring system. Thirty one subjects (62%) had some degree of corneal change, and in three cases (6%) follow-up was required. Multiple regression analysis was performed to discover any risk factors. Both age of the subject and the use of local anaesthetic were strongly associated with corneal changes.

Adult↗
PubMed1989

Thermal and water source effects upon the stability of enteroviruses in surface freshwaters.

The long-term survival of three human enterovirus serotypes, Coxsackievirus B3, echovirus 7, and poliovirus 1 was examined in samples of surface freshwater collected from five sites of physically different character. These were an artificial lake created by damming a creek, a small groundwater outlet pond, both a large- and a medium-sized river, and a small suburban creek. Survival was studied at temperatures of -20, 1, and 22 degrees C. The average amount of viral inactivation was 6.5-7.0 log10 units over 8 weeks at 22 degrees C, 4-5 log10 units over 12 weeks at 1 degree C, and 0.4-0.8 log10 units over 12 weeks at -20 degrees C. The effect of incubation temperature upon viral inactivation rate was statistically significant (p less than 0.00001). As determined by pairing tests, survival was also significantly related to both viral serotype and water source at each of the three incubation temperatures (p less than or equal to 0.05). Efforts were made to determine whether the rate of viral inactivation observed at the different incubation temperatures was related to characteristics inherent to the water that was collected from the different locations. The characteristics examined included physical and chemical parameters, indigenous bacterial counts, and the amount of bacterial growth that the waters would support (measured as the maximum number of generations which seeded bacteria could undergo after being placed into either pasteurized or sterile-filtered water samples). Analysis of viral inactivation rate versus these characteristics revealed three apparent effectors of viral persistence.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1989

Late development of localized band keratopathy in relation to a Molteno tube.

We report a case in which, 6.5 years postoperatively, localized band keratopathy developed in relation to a Molteno tube. At no stage had direct contact been noted between the tip of the tube and the corneal endothelium. The mechanisms of development of corneal opacities in relation to anterior chamber drainage tubes are discussed and the implications for the placement of such tubes are examined.

Anterior Chamber↗
PubMed1989

Traumatic hyphaema. Outcome and management.

The files of 206 patients who had sustained a hyphaema as a result of a contusion injury and had been admitted to Sydney Eye Hospital between January 1979 and December 1981 were reviewed. Most hyphaemas were small (189 or 91.7 per cent), occupying less than one-third of the volume of the anterior chamber. Fifteen patients had a secondary haemorrhage while in hospital and nine of these had a small hyphaema.

Adolescent↗
PubMed1989

Nonabsorbable suture material in corneoscleral sections--a comparison of novafil and nylon.

We compared a newly available nonabsorbable monofilament ophthalmic suture, 9/0 Novafil (Davis & Geck), with 10/0 nylon (Alcon), currently the most popular suture for closure of corneoscleral sections. Surgery was performed on nine rats and ten rabbits. In each case a 120 degrees corneoscleral section was made in each eye and closed with interrupted sutures of 9/0 Novafil in one eye and 10/0 nylon in the other. We compared their handling qualities during surgery, as well as their effect on postoperative wound inflammation. In addition we examined the suture material from each eye of the rats by scanning electron microscopy (SEM) after 3 months, and we compared the surgically induced astigmatism in the rabbits in the two suture groups. Both suture materials were easy to handle and well tolerated. Nylon sutures from six of the eight rat eyes studied showed SEM evidence of surface disintegration after 3 months, whereas all the Novafil sutures remained intact.

Absorption↗
PubMed1988

Suppression of viral replication by guanidine: a comparison of human adenoviruses and enteroviruses.

A comparison was made between the relative sensitivities of laboratory strain human adenoviruses and enteroviruses, and recently isolated human enteroviruses, to the presence of guanidine hydrochloride in cell culture media. The concentration of guanidine hydrochloride used was 100 micrograms per ml. Representatives of all six human Adenovirus subgenera were unaffected in their replication at this concentration of guanidine. The different human Enterovirus types examined varied in their sensitivity, with suppression ranging from less than 1 to 3 log10 units for laboratory strains, and from 2 to 7 log10 units for recently isolated viruses. The findings suggest a novel role for antiviral drugs; serving as an adjunct in facilitating selective isolation of specific virus groups which may be present as part of mixed viral populations.

Adenoviruses, Human↗
PubMed1988

Suppurative keratitis: a late complication of radial keratotomy.

A 21-year-old man who had radial keratotomy performed two years previously presented with a painful, red right eye. Suppurative keratitis was found in one of the eight radial incisions and Staphylococcus epidermidis was isolated by culture. Lack of stromal healing of the infected incision and the presence of epithelial cysts in four other incisions in the same eye suggest that the cause of the corneal infection was loss of the epithelial barrier function because of epithelial breakdown.

Adult↗