Secreted human conjunctival mucus contains MUC5AC glycoforms.
(33/1498)
This study addresses the extent of variation in secreted end-product mucins in human conjunctival mucus. The aim was to determine whether the variety of mucin species found was encompassed by the mucin genes which have been cloned to date. Extraction into guanidine hydrochloride and separation of mucin constituents, by a combination of cesium chloride density gradient centrifugation, size separation on Sepharose CL-2B, MonoQ ion exchange chromatography and agarose gel electrophoresis, demonstrates a complex mixture of mucins. Sample size limitations precluded compositional amino acid analysis. MUC 5AC and MUC1, 2, and 4 are all detected in the buoyant density range 1.3-1.5 g/ml by antibody binding. The mucins vary in size from >40 x 10(6)to <97 x 10(3)Da. A wide range of molecular size was confirmed using rate zonal centrifugation. The presence of smaller species contrasts with other mucous secretions similarly studied. In each size range are low, medium, and high charge mucins. Sialylation predominates in the medium charge and sulfate in the high charge. Only MUC5AC cross-reactivity is maintained throughout the analysis. It is detected in large and medium sized mucins but accounts for only the least mobile mucins within copurified species of similar density, size, and charge resolved using agarose electrophoresis. MUC5AC cross-reactivity is also detected in both medium and high charge species, indicating the presence of glycoforms. (+info)
Alterations in the conjunctival bacterial flora following a single dose of azithromycin in a trachoma endemic area.
(34/1498)
BACKGROUND/AIMS: The World Health Organisation has recommended repeated mass treatment of children in trachoma endemic areas with oral azithromycin. While chlamydia, the causative agent of trachoma, remains universally sensitive to azithromycin, there is concern that large scale programmes may alter the bacterial flora and induce resistance in streptococcal species. In this study the effect of a single dose of azithromcyin on the prevalence, species distribution, and resistance of conjunctival bacterial flora was determined. METHODS: Baseline and 14 day follow up bacterial cultures were taken from the conjunctivae of 121 children who reside in a trachoma endemic area of Nepal. 91 children were treated with azithromycin at baseline and 31 children received deferred treatment at the 14 day follow up. RESULTS: Although the prevalence of bacterial pathogens decreased significantly with azithromycin treatment, a significant change in the distribution of specific bacterial pathogens could not be demonstrated. Streptococcal resistance to azithromycin was found significantly more frequently after treatment. No change in the prevalence, distribution, or resistance pattern was found in the untreated control group. CONCLUSION: Repeated mass treatment of trachoma endemic areas with oral azithromycin will have an effect on bacterial flora. However, further work needs to be done to determine if this will have any clinical relevance. (+info)
Antinociceptive effect of R-(+)-hyoscyamine on the conjunctival reflex test in rabbits.
(35/1498)
R-(+)-Hyoscyamine (1-10 microg/kg, s.c.) dose-dependently increased the local anesthetic effect of procaine (50 microg/ml) and lidocaine (50 microg/ml) in the conjunctival reflex test in the rabbit. This potentiating effect is completely prevented by the M1 antagonist dicyclomine (10 mg/kg, s.c.). The intensity of R-(+)-hyoscyamine antinociception was comparable to that induced by morphine (2 mg/kg, s.c.) and minaprine (15 mg/kg, s.c.), used as analgesic reference drugs. In the same experimental conditions, the S-(-)-enantiomer of atropine (0.1-10 microg/kg, s.c.), was completely ineffective. The present results confirm the ability of R-(+)-hyoscyamine to produce a paradoxical antinociceptive effect mediated by a cholinergic mechanism not only in rodents but also in the rabbit. (+info)
Mucocutaneous junction as the major source of replacement palpebral conjunctival epithelial cells.
(36/1498)
PURPOSE: The conjunctival epithelium performs an important role in the homeostasis and integrity of the eye. To protect the integrity of the ocular surface, these cells must be replaced from locally concentrated or randomly distributed foci of stem cells. These slow-cycling stem cells produce transient amplifying cells that undergo further divisions before becoming mature conjunctival epithelial cells. In the current study, the source of palpebral conjunctival cells was determined. METHODS: Adult rabbits were injected intraperitoneally with bromodeoxyuridine (BrdU) at a dose of 50 mg/kg body weight and killed after 1, 3, 5, and 7 days and 2 months. The orbital contents and eyelids were exenterated en bloc, frozen to maintain the orientation between the eyelids and globe, and sectioned in a parasagittal plane. Random midglobe sections were stained for the presence of proliferating cell nuclear antigen (PCNA). Additional sections were immunostained to detect BrdU-labeled conjunctival epithelial cells. BrdU-positive cells were counted in a series of 0.4-mm zones from the mucocutaneous junction of the eyelid, through the fornix and bulbar conjunctiva. A second set of rabbits received daily injections of BrdU for 2 or 4 weeks followed by a 2-month BrdU-free period before death and processing. RESULTS: In all eyelid sections examined, there was a focus of PCNA-positive cells in the mucocutaneous junction and a few scattered PCNA-positive cells along the length of the palpebral conjunctiva toward the fornix. In both the upper and lower eyelids, the peak concentration of BrdU-labeled cells/0.4-mm zone was located at progressively greater distances from the mucocutaneous junction in the animals killed at 1, 3, and 5 days respectively and was unidentifiable by 7 days. A focus of BrdU-labeled conjunctival cells remained within 1 to 2 mm of the mucocutaneous junction at all postinjection intervals. These were always found within one cell height of the basement membrane in the basal layer of the epithelium. In the long-term studies, BrdU-labeled nuclei were retained at the mucocutaneous junction. CONCLUSIONS: The mucocutaneous junction of the conjunctival epithelium is a source of actively dividing transient amplifying cells that migrate toward the fornix at a rate of approximately 1.7 mm/d with a transit time of approximately 6 days. Long-term retention of label at the mucocutaneous junction indicates that slow-cycling stem cells are present at this location. It appears that most palpebral conjunctival epithelial stem cells are located near the mucocutaneous junction. These results are not necessarily at variance with previous studies, but they diminish the relative importance of the forniceal region in palpebral conjunctival homeostasis. The mucocutaneous junction may provide a therapeutically significant source of replacement conjunctival cells. (+info)
Tear secretion and tear film function in insulin dependent diabetics.
(37/1498)
BACKGROUND: Diabetic patients often complain of dry eye symptoms, such as burning and/or foreign body sensation. The aim of the present study was to investigate whether diabetes mellitus is correlated with tear film dysfunction and/or tear hyposecretion. METHODS: In 86 consecutive insulin dependent diabetics with retinopathy and 84 non-diabetic controls (age and sex matched) we performed fluorophotometry of tear secretion, the Schirmer test, and impression cytology of the conjunctival epithelium and determined the tear film break up time. RESULTS: When compared with the healthy control group diabetics showed decreased Schirmer test readings (-37%, p <0.001) and significantly more frequent and pronounced signs of conjunctival metaplasia. None of the other values differed between groups. CONCLUSION: In insulin dependent diabetics, reflex tearing was demonstrated to be significantly decreased. In contrast, unstimulated basal tear flow and tear film break up time were found to be normal. However, a majority of insulin dependent diabetics shows distinct signs of conjunctival surface disease. (+info)
Identification of androgen receptor protein and 5alpha-reductase mRNA in human ocular tissues.
(38/1498)
BACKGROUND/AIMS: Androgens have been reported to influence the structural organisation, functional activity, and/or pathological features of many ocular tissues. In addition, these hormones have been proposed as a topical therapy for such conditions as dry eye syndromes, corneal wound healing, and high intraocular pressure. To advance our understanding of androgen action in the eye, the purpose of the present study was twofold: firstly, to determine whether tissues of the anterior and posterior segments contain androgen receptor protein, which might make them susceptible to hormone effects following topical application; and, secondly, to examine whether these tissues contain the mRNA for types 1 and/or 2 5alpha-reductase, an enzyme that converts testosterone to the very potent metabolite, dihydrotestosterone. METHODS: Human ocular tissues and cells were obtained and processed for histochemical and molecular biological procedures. Androgen receptor protein was identified by utilising specific immunoperoxidase techniques. The analysis of type 1 and type 2 5alpha-reductase mRNAs was performed by the use of RT-PCR, agarose gel electrophoresis, and DNA sequence analysis. All immunohistochemical evaluations and PCR amplifications included positive and negative controls. RESULTS: These findings show that androgen receptor protein exists in the human lacrimal gland, meibomian gland, cornea, bulbar and forniceal conjunctivae, lens epithelial cells, and retinal pigment epithelial cells. In addition, our results demonstrate that the mRNAs for types 1 and 2 5alpha-reductase occur in the human lacrimal gland, meibomian gland, bulbar conjunctiva, cornea, and RPE cells. CONCLUSION: These combined results indicate that multiple ocular tissues may be target sites for androgen action. (+info)
Sponge delivery variables and tissue levels of 5-fluorouracil.
(39/1498)
AIM: To study how the delivery of 5-fluorouracil (5-FU) to ocular tissues is affected by altering delivery variables. METHOD: Sponge(s) soaked in radiolabelled 5-FU were placed between the conjunctiva and sclera of pig eyes. Application time, sponge size, sponge make (Altomed, Weck, Merocel), and 5-FU concentration were varied. Conjunctival and scleral tissue levels were determined in samples taken from the application site. RESULTS: Dose-response curves for scleral and conjunctival 5-FU levels against application time showed increasing tissue levels that reached a plateau after 2-3 minutes. Application beyond 3 minutes did not increase tissue levels. There was no difference in tissue levels between 7x4 and 3. 5x2 mm sponges. Altomed sponges produced 5-FU tissue levels that were twice as high as those obtained with Weck-cell (p<0.01) or Merocel (p<0.02) sponges. Changing the 5-FU concentration from 25 mg/ml to 6.25 mg/ml reduced the conjunctival concentration by a factor of 3.5 (p<0.003). CONCLUSION: Application time up to 3 minutes, sponge make, and 5-FU concentration can have a large effect on the tissue delivery of 5-FU. Application time beyond 3 minutes, using 3.5x2 mm or 7x4 mm sponges, and replacing sponges every minute did not have a significant effect on tissue levels. This study models the effect that different variables can have on the ocular tissue levels of an antimetabolite applied intraoperatively. (+info)
Expression of a single pair of desmosomal glycoproteins renders the corneal epithelium unique amongst stratified epithelia.
(40/1498)
PURPOSE: To determine desmosomal glycoprotein isoform expression in bovine corneal, limbal, and conjunctival epithelium and desmosomal profile and distribution during corneal re-epithelialization. METHODS: Immunofluorescence (IF) for desmosomal components on cryostat sections of fresh epithelia was supported by immunoblot analysis of tissue lysates. Wounded corneas maintained in organ culture were examined by IF at times up to full re-epithelialization (96 hours). RESULT: Immunofluorescence for desmoplakin confirmed desmosome presence throughout all three epithelia. Plakoglobin was also ubiquitous. Of the desmosomal glycoproteins, desmocollin 2 (Dsc2) and desmoglein 2 (Dsg2) were expressed throughout, but Dsc3 and Dsg3 were confined to the limbus and conjunctiva, and Dscl and Dsgl were absent. Dsc2 and Dsg2 IFs were stronger in superficial layers, but Dsc3 and Dsg3 were stronger basally, fading suprabasally. Glycoprotein expression in cornea and conjunctiva was confirmed by immunoblot analysis. No change in glycoprotein expression occurred during re-epithelialization. CONCLUSIONS: Uniquely among stratified epithelia, cornea expresses only a single pair of desmosomal glycoproteins, Dsc2 and Dsg2. Expression of Dsc3 and Dsg3 in limbus and conjunctiva coincides with their association with cell proliferation in other epithelia, but corneal epithelial cells did not express Dsc3 or Dsg3 during re-epithelialization. Absence of Dscl and Dsgl correlates with lack of keratinization in ocular epithelia. These expression patterns may have significance for the specific properties and differentiation patterns of the epithelia. Presence of desmosomes throughout re-epithelialization raises the question of how migrating cells mutually re-position. (+info)