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Presence and possible significance of immunohistochemically
demonstrable metallothionein expression in pterygium versus
pinguecula and normal conjunctiva.Eye.
2001 Feb;15(Pt 1):89-96.
PURPOSE: To
investigate metallothionein (MT) expression in pterygium, pinguecula
and normal conjunctiva and define its possible significance in this
area of the eye. In order to further elucidate the mechanism of MT
expression we correlated it with lymphocyte subpopulations (T4, T8),
macrophages (CD68), Langerhans' cells (S100) and the
proliferation-associated indices (PCNA, Ki67). METHODS: Eighty-five
surgically excised pterygia, 15 pingueculae and 20 normal
conjunctivae were immunohistochemically studied by the avidin-biotin
(ABC) method. A monoclonal antibody (E9) against a conserved epitope
of I and II isoforms of MT was used on formalin-fixed,
paraffin-embedded tissues. Statistical analysis was performed using
the SPSS statistical package. RESULTS: Epithelial MT expression was
detected in all 120 cases examined and in most of them both nuclear
and cytoplasmic immunoreactivity was present. Nevertheless no
statistically significant difference of MT expression was found
between the three types of tissue. A statistically significant
positive correlation between MT expression and lymphocyte subsets,
macrophages and Langerhans' cells was found in pterygium. On the
contrary, we did not find any statistical correlation in pinguecula
and normal conjunctiva. In all three types of tissues MT expression
was also positively correlated with the proliferation-associated
indices. CONCLUSION: The data suggest that there is
immunohistochemically demonstrable MT expression in the epithelium
of pterygium, but also of normal conjunctiva and pinguecula. MT may
serve a photoprotective role in this region. In pterygium in
particular, the biochemical pathway of MT synthesis seems
interestingly to cross the pathways of cell proliferation,
inflammation and immune activation.
p53
expression and relation to human papillomavirus infection in
pingueculae, pterygia, and limbal tumors.Arch
Ophthalmol. 1999 Dec;117(12):1593-9.
BACKGROUND:
The tumor suppressor gene p53 is expressed without apoptosis in the
limbal basal stem cells of all pterygia and limbal tumors and most
pingueculae from which these growths seem to originate. Oncogenic
human papillomaviruses (HPVs) have been found in pterygia and limbal
tumors, and HPV and p53 overexpression commonly coexist in
oropharyngeal and penile carcinomas. OBJECTIVE: To search for HPV
DNA as a cofactor in the development of pingueculae, pterygia, and
limbal tumors. METHODS: We examined specimens--1 of pinguecula, 13
of pterygia (7 primary, 1 recurrent, 1 with dysplasia, and 4 primary
not tested for p53), and 10 of limbal tumors (2 with actinic
keratosis dysplasia, 1 with conjunctival intraepithelial neoplasia,
3 with carcinoma in situ, and 4 with squamous cell
carcinoma)-expressing p53. Specimens were tested for the presence of
HPV DNA by the polymerase chain reaction using degenerate consensus
primers for the highly conserved portion of the L1 region that
encodes a capsid protein of the virus. This assay has a wide
spectrum with capability of detecting essentially all known HPV
types. Nested polymerase chain reaction was performed on all
specimens. Primers of the cystic fibrosis gene were used to confirm
the presence of genomic DNA and to rule out inhibitors. Purified HPV
DNA type 11 was the positive control, and HPV-negative genomic DNA
was the negative control. RESULTS: Using consensus primers for the
highly conserved portion of the L1 region, all specimens of
pingueculae, pterygia, and limbal tumors studied were negative for
HPV DNA by nested polymerase chain reaction. CONCLUSIONS: Human
papillomavirus DNA is not required as a cofactor in the development
of pterygia and limbal tumors. These data support the theory that
increased p53 expression in the limbal epithelia of pingueculae,
pterygia, and limbal tumors indicates the probable existence of p53
mutations in these cells as an early event in their development,
which is consistent with UV irradiation causation. Thus, due to a
damaged p53-dependent programmed cell death mechanism, mutations in
other genes may be progressively acquired. This would allow for the
multistep development of pterygia and limbal tumor cells from
p53-mutated limbal epithelial basal stem cells overlying pingueculae.
P53
expression in altered limbal basal cells of pingueculae, pterygia,
and limbal tumors.Curr
Eye Res. 1997 Dec;16(12):1179-92.
PURPOSE: We
previously discovered that the pathogenesis of pterygia was due to a
vimentin-expressing, altered limbal epithelial basal cell, the
pterygium cell. Since UV radiation epidemiologically correlates as
the etiologic agent for pterygia and limbal tumors and is mutagenic
for the p53 gene, our goal was to search for p53 gene mutations
immunohistochemically in the altered limbal basal cells of these
growths and of pingueculae from which they seem to originate.
METHODS: Longitudinal serial sections through six pingueculae, 14
primary and five recurrent pterygia, and five limbal tumors were
studied immunohistochemically with p53 monoclonal antibody DO-1 and,
in some specimens, with antivimentin antibody. RESULTS: P53
expression was found in the limbal cells of all pterygia, limbal
tumors, and Stage II pingueculae, but not in normal limbal-corneal
epithelial cells. However, when the same specimens were examined
with a TUNEL assay, few if any apoptotic cells were found. A finding
of increased nuclear p53 gene product with little or no apoptosis is
consistent with an activating mutation of the p53 gene, resulting in
increased steady-state levels of the protein. CONCLUSIONS: The
finding of increased nuclear p53 in the limbal epithelium of
pterygia, limbal tumors, and most pingueculae indicates the probable
existence of p53 mutations in these cells as an early event in their
development, which is consistent with their causation by UV
radiation causation. In addition, due to a damaged p53-dependent
programmed cell death mechanism, mutations in other genes are
progressively acquired which allows the multi-step development of
pterygia and limbal tumor cells from p53 positive cells overlying a
Stage II pinguecula. Similarly, a pterygium dysplasia could arise
from a pterygium cell. A classification for limbal basal cell tumors
is proposed, and the different stromal changes in pingueculae,
pterygia, and limbal tumors are identified. Two cell types were also
identified: a p53-positive pinguecula limbal epithelial cell (a
pinguecula II cell) and a p53-positive pterygium dysplasia cell (pterygium
dysplasia cell).
Pingueculae
and pterygia in motorcycle policemen.Ind
Health. 1997 Jul;35(3):325-9.
PURPOSE:
Pinguecula and pterygium are speculated to be associated with
corneal and conjunctival microtrauma from exposure to sunlight
and/or dust. Occupational motorcycle driving is suspected to be
associated with such exposure, so we investigated the prevalence of
pingueculae and pterygia in motorcycle policemen. METHOD: Silt lamp
finding obtained by periodic eye checkup for policemen (783
motorcycle policemen and 207 control indoor workers) together with
questionnaire were used for analyses. All pingueculae and pterygia
were diagnosed under the definite criteria. RESULTS: The overall
prevalence of pingueculae was 590/1,566 eyes (37.7%) among
motorcycle policemen against 127/414 eyes (30.6%) among the indoor
workers (p < 0.01). Besides, with increasing age, the prevalence of
pingueculae in the motorcycle policemen clearly exceeded those among
the indoor controls. The prevalence of pterygia were very small to
be analysed. CONCLUSION: Our results exhibited a significant
relationship between occupational motorcycle driving and the
prevalence of pingueculae. Thus it is strongly suggested that they
should wear eye protection equipment (goggles, face shield and so
on) to prevent from developing these lesions.
Elastic
fiber components and protease inhibitors in pinguecula.Invest
Ophthalmol Vis Sci. 1991
Apr;32(5):1573-85.
The nature
of the abnormal elastotic materials seen in pingueculae and their
insensitivity to elastase are poorly understood. The authors
investigated their composition by immunoelectron microscopy using
antibodies to elastic fiber components, serum and tissue components
known to be associated with elastosis in other sites. The abnormal
elastic fibers showed labeling for elastin, microfibrillar protein,
and amyloid P where these components never co-localize normally,
indicating the fibers are not simply immature but aberrant in
organization. There was mild positivity for the serum protease
inhibitor alpha-1 antitrypsin at the edges of the abnormal elastic
tissue and marked positivity for lysozyme. The more superficial
region of pingueculae had similar elastic constituents but no fiber
formation and a paucity of elastic microfibrils. The subepithelial
dense concretions showed strong staining for lysozyme, the first
component to be identified in these aggregates. Amyloid P and
lysozyme are characteristic components of dermal elastosis,
postulated to have an inhibitory effect on elastolytic processes,
indirectly affecting the control of elastogenesis. The greater
prominence of nonfiber-forming aggregates in pingueculae may be
related to their marked deficiency of elastic microfibrils compared
with dermal elastoses. This difference speaks for more severe
actinic cellular damage in the poorly protected conjunctival tissue.
Pingueculae
and pterygia.Surv
Ophthalmol. 1988 Jul-Aug;33(1):41-9.
Pingueculae
and pterygia are benign peribulbar lesions composed of degenerated
basophilic subepithelial tissue. Pingueculae do not affect vision,
and minor irritation can usually be managed with artificial tears.
Pterygia may affect the visual axis and require surgical and
adjunctive treatment. The various therapeutic strategies are
reviewed. A conservative approach is advocated, as surgical removal
of primary pterygia may result in recurrent ptergyia that are more
difficult to manage than the primary lesions.
The
pathology of pingueculae in Gaucher's disease.Ophthalmic
Paediatr Genet. 1984 Apr;4(1):7-11.
Several
reports have noted an apparent association between pingueculae and
Gaucher's disease and suggested that the yellow coloring of these
lesions is attributable to Gaucher cells. The authors biopsied
pingueculae from ten patients with this disorder and examined them
by serial light microscopy and electron microscopy. They failed to
find Gaucher cells in any specimen, but, as typical for pingueculae,
the elastosis observed histologically could account for their yellow
hue.
Pinguecula
and pterygium: histologic and electron microscopic study.Virchows
Arch A Pathol Anat Histol. 1978 Oct
3;379(4):321-33.
Two
pingueculae combined with pterygia were studied by light and
electron microscopy. Hyaline degeneration of the collagen, dark
staining granular, von Kossa negative concretions and elastotic
material were observed in both conditions together with marked
changes in the fibroblasts, endothelial cells, pericytes and the
basement membrane of conjunctival capillaries and small veins. The
elastotic material is similar to that observed in solar elastosis,
where the collagen fibers are less severely damaged. Chronic sun
exposure of the pericorneal conjunctiva may damage endothelial cells
primarily and disturb vascular exchanges. This would result in
accelerated degeneration and regeneration of endothelial cells, in
thickening of the basement membrane and, secondarily, disturbed
metabolism of fibroblasts with alterations of the collagen and
elastic fibers.
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