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E Haaskjold

Publications and source records attributed to E Haaskjold.

35 records · Page 2Linked to original sources
PubMed1994

Time dependency in the regenerative response to injury of the rat corneal epithelium.

In the present study a central corneal epithelial defect (diameter 3.5 mm) was made in both eyes at 12:00 h in one group of rats and at 24:00 h in another group to see if the regenerative proliferation is influenced by circadian rhythms. The labeling index and the mitotic rate were registered at 4-h intervals in the perilimbal conjunctiva, the limbal area, and different parts of the cornea from the following morning until noon the day after that. The most pronounced regenerative proliferation was seen in the midperipheral and peripheral cornea. The regenerative response occurred in both groups 24-28 h after the injury, but was highly influenced by the normal circadian rhythms, especially with regard to the mitotic rate. The results support the theory that even regeneration is influenced by a circadian proliferative factor.

Animals↗
PubMed1993

Apoptosis in the rat corneal epithelium during regeneration. A transmission electron microscopic study.

In the present transmission electron microscopic study, regenerating rat corneal epithelium is examined at three different time points after chemical abrasion. Four days after the initial injury classical signs of regeneration are observed. At day 6 regeneration is less pronounced and epithelial differentiation dominates the morphological picture. Many basal cells are swollen and single electron-dense basal cells have a shrunken morphology (dark cells). Intercellular cytoplasmic sacs are common and some appear to be phagocytosed. At day 8 there are no signs of regeneration and neither dark cells nor swollen cytoplasmic sacs are seen. No signs of intraepithelial inflammation are seen at any time. "Odland"-like granules, which possibly play a role in epithelial desquamation, occur suprabasally in large numbers at all time points. We believe the simultaneous presence of dark cells and phagocytosis at day 6, without signs of inflammation, indicates ongoing apoptosis. Intraepithelial cell loss might explain the discrepancy between an increased proliferation rate and the absence of hyperplasia which has been reported at this time point.

Animals↗
PubMed1993

Early cell kinetic effects of a single dose of narrow-banded ultraviolet B irradiation on the rat corneal epithelium.

The right eyes of 40 rats were exposed to a single erythemogenic dose of ultraviolet B irradiation (UVB) at 297 nm. The irradiation was directed perpendicular to the center of the cornea. The left eyes served as controls. The animals were randomly assigned into 10 groups. The labeling index (LI) after pulse labeling with tritiated thymidine and the mitotic rate (MR) after Colcemid administration were registered in the corneal epithelium at predetermined intervals up to 96 h after the irradiation. A mathematical method was used to correlate corresponding corneal areas from the different animals. In the central cornea the LI was considerably reduced up to 36 h after the irradiation. The LI increased toward the peripheral cornea and reached normal values at the limbal area. The MR was also reduced up to 36 h. However, this reduction was over the entire epithelium. The block in cell proliferation was followed by increased proliferation.

Animals↗
PubMed1993

Cataract surgery. Computer-based registration and analysis of data.

Consecutive registration, rapid retrieval and relevant analysis of information about cataract patients were obtained by applying a data form. The form was designed to be used with a statistical computer program (SPSS/PC). Data describing cataract cases, operations and postoperative controls were recorded. The information is contained in 76 variables, each with up to 10 alternative answers. The main advantages are the opportunity for quality control and clinical research. As an example, an analysis of the pre- and postoperative visual acuity is presented. Originally, the material consisted of 969 eyes, and of these, 948 eyes were available for follow-up. The postoperative corrected visual acuity was 5/5 or better in 57.2% of the eyes. In 80.4% of the eyes a visual acuity better than 5/10 was achieved. The main cause of postoperative visual acuity less than 5/8.5 was age-related macular degeneration (115 eyes). This maculopathy was recognized preoperatively in 76 eyes.

Cataract Extraction↗
PubMed1993

Secondary implantation of flexible open loop anterior chamber IOLs.

Secondary implantation of flexible, open loop anterior chamber IOLs was performed on 20 aphakic eyes between January 1990 and May 1992. In 3 cases anterior vitrectomy was necessary. No other complications were encountered during surgery. The patients were followed up for 4 months postoperatively. Seventeen eyes achieved a corrected visual acuity of 5/5 or better. Fourteen eyes achieved the same visual acuity as preoperatively, and 5 ended with an improved visual outcome. In one case the visual acuity became worse than preoperatively due to cystoid macular edema. No other serious postoperative complications occurred. The postoperative refraction was within 1 diopter of emmetropia in 16 eyes compared to the estimated (biometry) 19 eyes. We conclude that implantation of flexible open loop anterior chamber IOLs is a safe procedure in properly selected cases.

Adult↗
PubMed1993

The proliferative response during regeneration of a ringshaped defect in the corneal epithelium.

The aim of the present study was to investigate the regenerative ability of the central corneal epithelium in an in vivo situation, as previous studies have been contradictory regarding the proliferative potential of these cells. Paracentral ringshaped defects were made in rat corneal epithelium, using filter paper soaked in n-heptanol. Cell counts, labelling indices and mitotic rates were measured in sections from the corneal and the adjacent conjunctival epithelium 12 and 28 h after the injury. The cell counts indicated that also central corneal epithelial cells migrate in the early phase of wound healing. No proliferative response was seen in the central corneal epithelium after 12 h. At 28 h both the peripheral and central corneal cells showed an enhanced labelling index, while the mitotic rate only was increased in the periphery. Different cell cycle times and different levels of differentiation of the cell population across the cornea may explain the delayed proliferative response in the central cornea.

Alcohols↗
PubMed1993

Cell kinetics of normal and healing rat corneal epithelium during organ culture.

Local epithelial proliferation in corneal, limbal, and conjunctival rat epithelium was investigated during organ culture of corneo-scleral shells, by relating the number of tritium labelled cells to the total number of cells (labelling index). The changes in labelling index after a mechanically induced central corneal abrasion were also studied. Local labelling indices were measured 2 h, 1, 2, 4 and 7 days after incubation. The average labelling index increased in un-abraded specimens 4-fold after 4 days of incubation, while the total number of cells only decreased 30-50%. In eyes with a central corneal abrasion the labelling index increased 10-fold in the surrounding epithelial cells after 1 day. The labelling index of the limbal and conjunctival epithelial cells increased to the same extent after 2 days of incubation. The finding of a reduced total number of cells and an increased cell proliferation in un-abraded eyes may be explained by increased loss of mature cells normally producing growth-inhibitory substances (chalones). Alternatively, the culture medium may contain an excess of growth-stimulatory substances. The results also suggest that the proliferative response spreads in a centrifugal direction during in vitro healing of a central corneal abrasion.

Animals↗
PubMed1993

Pseudoexfoliation syndrome and extracapsular cataract extraction.

Extracapsular cataract extraction (ECCE) in 139 eyes with pseudoexfoliation syndrome was compared to 762 eyes without pseudoexfoliation syndrome in a consecutive study. Preoperative findings, operative procedure and problems were registered, stored and analyzed in a computer program package. Of the patients with pseudoexfoliation syndrome 88.5% were 70 years or older, compared to 67.2% of the patients without pseudoexfoliation syndrome (p < 0.001). Glaucoma occurred in 48.9% of eyes with pseudoexfoliation syndrome and in 6.8% of eyes without pseudoexfoliation syndrome, respectively. Poorly dilated pupil was demonstrated in 46.8% and in 5.8% of eyes with and without pseudoexfoliation syndrome, respectively. Capsule/zonulae tears (without vitreous loss) occurred in 4.3% of the pseudoexfoliation syndrome eyes, compared to 1.3% in eyes without pseudoexfoliation syndrome (p < 0.05). The incidence of vitreous loss was similar in both groups. We found no correlation between the pupil size and capsule/zonulae tears or vitreous loss in either group. In conclusion, when appropriate care is undertaken, ECCE with posterior chamber IOL implantation is a safe procedure in pseudoexfoliation syndrome eyes.

Aged↗
PubMed1993

Results and complications after extracapsular cataract extraction in eyes with pseudoexfoliation syndrome.

Postoperative results and complications in 136 eyes with pseudoexfoliation syndrome were compared to 744 eyes without pseudoexfoliation syndrome in a consecutive study. The patients were followed for 4 months postoperatively. Excluding cases with glaucoma, 81.4% of the pseudoexfoliation eyes and 83.0% of the eyes without pseudoexfoliation achieved a corrected visual acuity of 5/8.5 or better. IOL malposition was rare in both groups (1.5% in the pseudoexfoliation group and 1.6% in the group without pseudoexfoliation). IOP elevation the first day postoperatively occurred most often in the pseudoexfoliation eyes. In the pseudoexfoliation eyes, postoperative iritis and cellular precipitates were demonstrated in 16.2% and 11.0%, respectively, compared to 3.8% and 3.2% in the eyes without pseudoexfoliation (p < 0.001). The frequency of an inflammatory reaction was highly correlated to small pupil size during operation in both groups.

Cataract↗
PubMed1992

Cell kinetics of the rat corneal epithelium.

In the rat corneal epithelium the mitotic rate (MR) is almost equal throughout the epithelium in the morning (Haaskjold et al. 1988). The labelling index (LI) shows a marked reduction in the central cornea, which could suggest a lack of uptake of tritiated thymidine via the salvage pathway (Haaskjold et al. 1989). In the present study we have used [3H]deoxycytidine, and [3H]thymidine after prior treatment with a methotrexate regimen to elucidate this discrepancy. Deoxycytidine is incorporated into DNA independent of thymidine kinase, while methotrexate, which depletes the cells of reduced folates, makes the cells completely dependent on the salvage pathway. With both techniques the same pattern of labelling was observed, confirming that in the morning the ratio between the MR and the LI differs throughout the cornea. Based on previous observations, an analysis of the MR/LI ratio during 24 h was performed, showing that these parameters were strongly correlated. This suggests that there may be different circadian variations in the cell proliferation parameters throughout the corneal epithelium. The methotrexate regimen may be a useful tool to investigate the salvage pathway.

Animals↗
PubMed1992

The early cell kinetic response during healing of corneal epithelial wounds.

The labeling index and the mitotic rate were measured at 4-hour intervals during the first 24 hours after a central abrasion had been made in the corneal epithelium of six groups of four rats each. The proliferative response was noted in the conjunctival, the limbal, and the corneal epithelium. After 24 hours, the density of epithelial cells was equal throughout the corneal epithelium, but there was only half the normal number of cells. Physiological mechanisms seem strongly to regulate the total number of cells per square unit throughout the healing corneal epithelium, but the nature of these mechanisms is unknown.

Animals↗
PubMed1991

Regeneration of the rat corneal epithelium after injury. A cell kinetic study comparing the reaction after abrasions made mechanically and with n-heptanol.

Central corneal epithelial defects with diameter 3.5 mm were made with n-heptanol in the right eyes of rats. Erosions of the same size were made by mechanical scraping in the left eyes of the same animals. All the erosions were covered by epithelium after one day. After one day the mitotic rate and the labelling index were higher in the n-heptanol treated corneas compared to the mechanically abraded ones. Both methods produced similar mitotic rates and labelling indexes after 3 and 12 days. The results from wound healing studies using n-heptanol or mechanical scraping are therefore not entirely comparable because of the different regenerative responses after one day. However, the n-heptanol method is easier to perform and to standardize, and is therefore preferable.

Alcohols↗
PubMed1991

Outgrowth of cells from human conjunctival explants onto cornea in vitro.

The epithelium was removed from human corneas, and samples of conjunctival tissue were cultured as explants on the denuded corneal surface for 1 and 2 weeks. Cells migrating from the conjunctival explants onto the corneal surface produced a multilayer where cells on the surface generally showed a flattened appearance. The apical membrane of these cells demonstrated villi as well as microplicae. Surface projections were also detected on cells in the deeper layers of the epithelium. Neighbouring cells were connected by junctional complexes. After 2 weeks, however, a lack of intercellular junctions in some areas resulted in the formation of intraepithelial cystoid spaces. Basal cells were connected to the underlying basement membrane by hemidesmosomes. Although transdifferentiation of the cells into a corneal epithelium was not observed within the 2 weeks, the present system provides a tool for studies on factors affecting reepithelialization of corneal epithelial defects by conjunctival cells.

Adolescent↗
PubMed1991

Morphology and proliferation of human corneal epithelium in organ culture.

Organ cultures of central and peripheral human corneal epithelium were maintained for 1 and 2 weeks in Hams F10 medium supplemented with 20% foetal bovine serum, and in medium conditioned by conjunctival epithelial cells. Light microscopy and scanning electron microscopy showed no obvious differences in morphology and survival between central and peripheral explants, or between explants cultured in conditioned and non-conditioned medium. Live cells and areas with confluent growth were seen in all types of explants. The results demonstrate that differences between growth of central and peripheral corneal epithelium in vitro do not necessarily reflect different proliferative potential in vivo. The previously reported lack of survival of central corneal epithelium in culture may reflect an insufficient in vitro system.

Aged↗
PubMed1989

DNA synthesis in human retinal pigment epithelium in organ culture.

Retinal pigment epithelium from human eyes was maintained in organ culture, and DNA synthesis was visualized by autoradiography of cultures exposed to labelled thymidine. In Ham's F10 medium, labelling of cells was observed after 7 as well as after 14 days in vitro. At both stages the labelled cells were characteristically located adjacent to areas of epithelial damage. Cells remote from such areas did not incorporate thymidine, This pattern was observed in epithelia removed from the posterior pole as well as from the periphery of the fundus. Several types of routine media and media with human as well as foetal bovine serum (FBS) were found to support DNA synthesis in the cultured epithelium, labelled cells were not observed in epithelium maintained in Ham's F10 without serum, or with low serum concentration. Our study demonstrates, that DNA synthesis does take place in organ cultured human retinal pigment epithelium when the appropriate culture conditions are used. Our findings indicate that induction of DNA synthesis in the cells is not promoted by an indiscriminate effect of the medium but related to the presence of epithelial damage.

Culture Media↗
PubMed1988

The labelling index is not always reliable. Discrepancies between the labelling index and the mitotic rate in the rat corneal epithelium after intraperitoneal and topical administration of tritiated thymidine and colcemid.

Many cell kinetic studies are based on the assumption that tritiated thymidine injected into an animal is available for incorporation into DNA for only a short time, and that it labels all cells in the S phase. The present study indicates that this is not the fact for the rat corneal epithelium. The labelling index (LI) declines considerably from the limbal area to the central cornea, while the mitotic rate is almost constant all over the corneal epithelium. The LI should therefore not be used as the only criterion in the assessment of proliferation rate.

Administration, Topical↗