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Biomedical subjects

J Friend

Publications and source records attributed to J Friend.

At least 73 records · Page 4Linked to original sources
PubMed1983

Goblet cell density in ocular surface disease. A better indicator than tear mucin.

Mucinlike glycoprotein from tears and conjunctival goblet cell densities were determined in normal subjects and in patients. The results indicated that although there was a statistically significant decrease, a substantial amount of mucinlike glycoprotein was present in tears from patients with ocular cicatricial pemphigoid (OCP), radiation keratitis, and corneal anesthesia. In the same patients, the goblet cell count was profoundly decreased in OCP and radiation keratitis, well out of proportion to the modest fall in mucinlike glycoprotein. This indicated that the tear mucin content shows minimal variation over a great variation in goblet cell density, suggesting that while moderate mucin deficiency may be associated with surface abnormalities, such mucin deficiency may not be the only cause of the ocular surface epithelial problems characteristic of these diseases. In addition, it is proposed that the goblet cell content of the conjunctiva is a sensitive indicator of primary ocular surface disease.

Cell Count↗
PubMed1983

Keratin-like proteins in corneal and conjunctival epithelium are different.

Using SDS polyacrylamide slab-gel electrophoresis, water-insoluble (keratin-like) proteins in normal and regenerated ocular surface epithelium from rabbits were studied. The results indicated that keratin-like proteins from corneal and conjunctival epithelia in vivo distinctly different. Regenerated epithelia from either source retained their original keratin characteristics for at least 10 days after healing over the cornea, but at very early stages of healing migrating and regenerated epithelia showed either an extra band or a prominent band in addition to the original keratin-like proteins. Three months after healing, however, regenerated conjunctival epithelium on the cornea had changed its keratin characteristics, and resembled, but was not identical to, corneal epithelium.

Animals↗
PubMed1983

Glycogen and DNA content of corneal epithelium: comparison of preparation methods.

Three methods of corneal epithelial preparation for subsequent analysis of epithelial glycogen and DNA content were compared: scraping, lamellar stripping, and in situ freezing. All three methods gave good recovery of these substances. However, there was incomplete recovery of the sample using the in situ freezing method and significant contamination of epithelial samples by stroma in the lamellar stripping method. Thus, scraping is the most reliable method of collecting pure epithelial samples for glycogen or DNA analysis.

Animals↗
PubMed1983

Conjunctival goblet cell frequency after alkali injury is not accurately reflected by aqueous tear mucin content.

Goblet cell counts have been used to evaluate the suitability of conjunctiva as a source of ocular surface epithelial cells. However, since tear mucin content can be determined without tissue excision, it seemed that the concentration of those compounds might be a useful indicator of conjunctival vitality. To test the extent to which aqueous tear composition reflects conjunctival goblet cell frequency, goblet cell frequency and aqueous tear mucin content were measured after alkali injury in rabbits. Mild alkali injury (0.1 N NaOH for 30 sec) caused a transient but substantial decrease in goblet cells (to 25% of normal at day 7) with a return to normal by six weeks. Tear mucin content was decreased to a lesser degree, from a normal value of 6.4 +/- 0.47 nmol oligosaccharide per microliter (n = 10) to a minimal value of 4.7 +/- 0.64 (n = 7) (73% of normal) at day 7, returning to normal 4 weeks after injury. Thus, the direction of the change was the same, but the magnitudes were quite different. These results suggest that conjunctival goblet cell frequency is not accurately reflected by aqueous tear mucin content, and therefore, that tear mucin content cannot be used directly as an indicator of conjunctival health.

Animals↗
PubMed1982

Corneal epithelial changes in diabetic rats.

Electron microscopy of streptozotocin diabetic rat eyes showed increased intracellular levels of tonofilaments and glycogen, thickenings and infoldings of subepithelial basement membrane and basal cell degeneration after 8 months. Glycogen, glucose, sorbitol, and fructose were measured in corneal epithelium from short- and long-term diabetic rats. The small increase in sorbitol pathway products which were found after 8 months of diabetes (less than 1.0 mosm/1 tissue water) confirmed similar findings in rabbits and humans. Thus, the morphologic changes occur in the absence of significant accumulation of sorbitol pathway products. Osmotic damage secondary to corneal epithelial cell accumulation of sorbitol is probably not a significant factor in corneal epithelial diabetic disease.

Animals↗
PubMed1982

Corneal epithelial cell cultures on stromal carriers.

Exposure of denuded rabbit corneal stromal carriers for 24 hr at 37 degrees C to suspensions of rabbit corneal epithelial cells grown in tissue culture resulted in the establishment of a cell layer on the carriers. The cell layers persisted for at least 1 week of incubation and were one to three cells thick. They consisted of healthy-appearing cells with normal intracellular organelles and intercellular desmosomal connections. After 2 to 7 days of incubation the cells were still capable of DNA replication and produced hemidesmosomes and basement membrane. This system is useful for in vitro studies of substrate requirements for hemidesmosome and basement-membrane formation by corneal epithelial cells.

Animals↗
PubMed1982

Limbal epithelium in ocular surface wound healing.

The regenerated epithelium derived from limbal epithelium was histologically and biochemically compared with epithelia regenerated from corneal and bulbar conjunctival epithelia. The histologic results indicated that regenerated epithelium of limbal origin increased in thickness with time after healing and showed no goblet cell appearance on the cornea. This suggests that regenerated epithelium from the limbus is more like regenerated epithelium of corneal origin than that of bulbar conjunctival origin. However, the glycogen content and protein pattern profile showed that regenerated epithelium of limbal origin had characteristics intermediate between those of corneal and bulbar conjunctival origin. Thus it is proposed that there are three distinct types of ocular surface epithelia--corneal, bulbar conjunctival, and limbal--and that limbal epithelium behaves differently from corneal and conjunctival epithelia in ocular surface wound healing.

Animals↗
PubMed1981

Sex chromatin of donor corneal epithelium in rabbits.

The survival of donor corneal epithelium was investigated in rabbits after they received unilateral 8 mm diameter lamellar keratoplasties with living donor tissue of a different sex from the host. Three weeks, 6 weeks, and 12 weeks postoperatively, cultured corneal epithelia, grown from 5 mm diameter central buttons, the adjacent 0.75 mm wide donor rings, the peripheral 10 to 13 mm diameter rings, and 5 mm diameter central host buttons were used for sex-chromatin analysis. The results indicated that some of the donor corneal epithelium survived up to 12 weeks postoperatively. Even in the absence of overt epithelial rejection, however, a time-dependent decrease of donor corneal epithelium and simultaneous invasion of host corneal epithelium were demonstrated.

Animals↗
PubMed1981

Corneal re-epithelialization from the conjunctiva.

After debridement of the entire corneal epithelium, epithelial cells of conjunctival origin cover the exposed corneal surface. Four to five weeks later, these cells undergo a morphologic transformation to normal-appearing corneal epithelium. To study this transformation the entire corneal epithelium was removed from rabbits with the use of n-heptanol, after which the histologic appearance of and the number of goblet cells in the regenerated epithelium were noted. Five stages of transformation were seen. Immediately after healing, the epithelium consisted of one to two squamous cell layers with no goblet cells apparent at the light microscope level (stage 1). In the following weeks goblet cells appeared at the limbal edge of the cornea (stage 2), reached a uniform distribution across the cornea (stage 3), and subsequently receded toward the limbus (stage 4), leaving an epithelium with normal corneal morphologic appearance (stage 5). To see if there was an ongoing centripetal cell migration from the conjunctiva across the cornea after initial healing, the central corneal epithelium was isolated from the periphery by a ring of glue. Such isolation resulted in a thinning of the central epithelium and a thickening of the peripheral epithelium. These studies suggest that (1) the transformation into corneal epithelium lags behind defect closure by 4 to 5 weeks, (2) goblet cells do not initially migrate as recognizable cells, and (3) there is a continuous centripetal cell motion even after the initial defect closure is accomplished.

Animals↗
PubMed1981

Diabetes mellitus and the rabbit corneal epithelium.

Diabetes mellitus has been shown to be a factor in the development of corneal epithelial abnormalities in stressed human eyes, but the biochemical basis for this is not known. To see if sorbitol pathway activation might be involved, ocular surface epithelial healing rates and metabolites of the glycolytic and sorbitol pathways were measured in alloxan-diabetic rabbits. As in humans, corneal epithelial healing rates were not decreased in the diabetic rabbits, suggesting that the rabbit may be an appropriate model for human disease. Increased levels of glucose, glycogen, and sorbitol were found in the diabetic corneal epithelium compared with normal. However, the sorbitol accumulation only mounted to 1.0 mOsm/L of tissue water, which implies that osmotic damage secondary to corneal epithelial cell sorbitol accumulation might not be a significant factor in corneal epithelial abnormalities of diabetes.

Animals↗
PubMed1980

Insulin sensitivity and sorbitol production of the normal rabbit corneal epithelium in vitro.

Insulin-depleted, normal rabbit corneal epithelium was incubated in vitro in tissue culture medium containing high concentrations of glucose (35 mM). These short-term incubations showed that the epithelium took up glucose equally whether or not insulin had been added to the medium, indicating that corneal epithelium is an insulin-insensitive tissue. Sorbitol accumulation showed that the normal corneal epithelium has a sorbitol pathway which can be activated in the presence of high intracellular glucose. The low level of sorbitol accumulation in these normal epithelia is probably not osmotically significant.

Animals↗
PubMed1979

Ocular surface epithelium and corneal vascularization in rabbits. I. The role of wounding.

A new model for rabbit corneal vascularization, created by making a penetrating wound in corneas with epithelium of conjunctival origin, is described. Obligate resurfacing of the cornea from conjunctival epithelium usually leads to a small, but consistent peripheral superficial corneal vascularization. Subsequent penetrating wounds elicit, in 75% of cases, a marked vascular ingrowth. Normal eyes and eyes resurfaced by peripheral corneal epithelial cells do not vascularize after such wounds. The vessels are located in the anterior corneal stroma, and the regenerated epithelium has a conjunctival appearance. Although increased hydration plays a role in this vascularization, the extent of vascularization was much greater in the presence of regenerated epithelium of conjunctival origin than in the presence of regenerated epithelium of corneal origin.

Animals↗