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Biomedical subjects

W A Manschot

Publications and source records attributed to W A Manschot.

At least 19 recordsLinked to original sources
PubMed1992

Uveal melanoma: therapeutic consequences of doubling times and irradiation results; a review.

Thirty-six of 39 published calculated doubling times (Td's) of uveal melanomas appeared to be longer than 60 days. Metastatic death occurs 35-40 Td's after dissemination. The shortest interval between dissemination and metastatic death in individual patients may, therefore, be calculated as 35 x 60 days = 6 years; the interval may extend to 80 years. This suggests, that local therapy cannot influence the survival data within the first 7 post-therapeutic years, because almost all metastatic deaths within these 7 years are due to pretreatment dissemination. For that reason, the published comparative survival analyses after various therapies have within this period failed to show statistically significant death rates differences. Microscopically viable melanoma tissue has been noted in 215 of 231 histopathologically studied irradiated uveal melanomas. Observed mitotic figures 4-6 years after irradiation indicate retained reproductive integrity. This constitutes a--by enucleation avoidable--incremental risk for post-irradiation exponential growth and dissemination. The risk cannot become statistically manifest before a greater than or equal to 10-year follow-up period. Retained, generally poor, visual acuity in a small percentage of patients cannot balance the incremental risk/benefit ratio of irradiation. A few, at present justifiable, indications for radiotherapy on uveal melanomas are enumerated.

Brachytherapy↗
PubMed1990

Morning glory syndrome: a histopathological study.

The clinical and histopathological findings in a case of morning glory syndrome are described. Axial optic nerve retrodisplacement into a peripapillary scleral ectasia (staphyloma), absence of fibrous lamina cribrosa, and optic nerve atrophy were associated with various other, non-inherent ocular developmental anomalies. The uninterrupted lining of the inner wall of the staphyloma by one-layered, normal retinal pigment epithelium proves that the syndrome is not due to a neuroectodermal closure defect.

Anterior Eye Segment↗
PubMed1988

[Irradiation of choroid melanoma: justifiable therapy or medical experiment].

An analysis of published results of irradiation of choroidal melanomas shows that only two reports contain justified statistics. All other statistics are based on insufficiently long follow-up periods, and do not cover all patients irradiated so that artifacts of selection occur which cannot be checked. Arguments are adduced which show that the authors of the two relevant reports mentioned rightly changed their previously positive attitude towards irradiation of these tumors. With the exception of three circumscribed categories of patients, irradiation of choroidal melanomas is still an unjustifiable medical experiment.

Choroid Neoplasms↗
PubMed1987

Is irradiation a justifiable treatment of choroidal melanoma? Analysis of published results.

Analysis of the literature shows that dissemination of choroidal melanomas generally occurs after the 7 mm diameter stage, that doubling times of uveal melanomas vary from 30 to 365 days, and that death from metastases occurs 30-40 doubling times after dissemination. Tumour related death within three years after therapy is caused by pre-existing metastases. Survival rates for less than four years after therapy are therefore irrelevant in evaluating the efficacy of therapeutic regimens. Considerably higher postirradiation than postenucleation death rates after a mean 10-year follow-up period have been reported, and this difference can be explained by a reported mean clinical tumour regression rate of 31% two years after irradiation and histopathological studies which revealed that 42 out of 43 irradiated melanomas contained viable tumour, while only 50% showed necrosis. The doubtful value of preserving vision does not justify the high risk of avoidable death from metastases in irradiated patients.

Choroid Neoplasms↗
PubMed1986

Ligneous conjunctivitis.

The case history is given of a woman of 65 (in 1973) with a granulomatous conjunctival inflammation in the right eye and chronic recurrent polyps on the vocal cords. Several times, granulomatous tissue was removed from the conjunctiva of the right eye but the result was recurrences at shorter intervals. Seven years after the onset in the right eye the left eye became affected. Various treatments, both systemic and local, were tried without success. The histological diagnosis of ligneous conjunctivitis was not made until 1981. Treatment with the known remedies for ligneous conjunctivitis was not successful. At the end of 1984 treatment with Imuran (azathioprine) was started. Since that time the patient has been practically free of recurrent granulomatous tissue on the conjunctiva and vocal cords. The treatment of ligneous conjunctivitis with Imuran has not previously been reported in the literature.

Aged↗
PubMed1985

Optic disc drusen and central vein occlusion.

The blind and painful right eye of a 34-year-old woman with the Sturge-Weber syndrome had to be enucleated on account of keratitis e lagophthalmo. Histopathological examination revealed drusen of the optic disc, which had caused central retinal vein occlusion.

Adult↗
PubMed1985

Development of retinal neovascularisation in vascular occlusive disease.

Retinal neovascularisation in 80 non-diabetic patients with occlusive retinal vascular disease appeared to be related at least as frequently to arterial as to venous occlusive disease. Intraretinal, preretinal and prepapillary neovascularisation had developed in 76 per cent, 47 per cent and 49 per cent respectively of the specimens. Neovascularisation in the adult retina is thought to develop in the following sequence of histopathologic features: plasmatic insudation and transudation of the vessel walls (100 per cent of the specimens), endothelial cell proliferation (97 per cent) and capillary formation (76 per cent). Intramural newly-formed capillaries in thickened hyalinized vessels were observed in 68 per cent of the specimens. Not only retinal vein occlusion but also slowly progressive arterial and arteriolar occlusive diseases may produce retinal neovascularisation, originating from arterioles, venules and capillaries which are involved in a hypoxic degenerative endothelial process which gives rise to endothelial proliferation.

Aged↗
PubMed1984

Retinal neovascularisation arising from hyalinised blood vessels.

In a retrospective histopathological study of 75 eyes with occlusive retinal vascular disease, intraretinal, preretinal and prepapillary neovascularisation was observed in 76%, 48% and 48%, respectively. The central retinal vein, artery and branch arteries were shown to be occluded in 48, 46 and 6 cases, respectively. Generalised obliterative arteriolovenular sclerosis was observed on 24 occasions; combined stem occlusions of the central retinal vein and artery was found in 33 specimens. A most significant finding was the presence of intramural capillaries within hyalinised retinal vessels in 51 cases (68%). These newly formed capillaries originated from proliferating vascular endothelium; their lumina communicated with the vascular lumen and continued in many instances into congeries of newly formed intra- and preretinal capillaries. The diseased parent vessels showed evidence of plasmatic insudation and transudation (100%) and endothelial proliferation (97%). These phenomena constitute the first stage of a type of retinal neovascularisation which has not hitherto been adequately described.

Aged↗
PubMed1979

Pinealoblastoma with retinoblastomatous differentiation.

A case of primitive neuroectodermal tumour originating from pineal parenchymal cells in a 2 1/2-year-old boy is described. The tumour exhibited divergent lines of differentiation including neuroblastic and photoreceptor differentiation, thus aligning it with neuroblastomas and with retinoblastomas. The tumour recalls the function of the pineal as a photoreceptor organ at an earlier stage of its phylogenesis.

Brain Neoplasms↗
PubMed1978

Mechanism of fixation of two-loop iridocapsular lenses.

I used seven eyes obtained postmortem to study the mechanism of fixation of a Binkhorst two-loop iridocapsular lens. During the first postoperative weeks, vitreous pressure and traction on the posterior lens capsule exerted by the zonular fibers pushed the loops of the iridocapsular lens against the iris. The zonular traction maintained the posterior capsule taut so that the vitreous pressure was distributed equally over the entire surface of the capsular diaphragm. Lens epithelial cells proliferated around the margin of the capsular breaks and defects and formed plaques or masses of spindle-shaped cells. This pseudofibrous tissue bridged and sealed capsular defects and caused adhesions between the anterior and posterior lens capsule and between the anterior capsule and the iris pigment epithelium. Fixation of the lenses may be reinforced by proliferation of the iris pigment epithlium and of the fibrous tissue arising from the iris stroma.

Humans↗
PubMed1978

Senile scleral plaques and senile scleromalacia.

A case of senile scleral plaques is reported in which expulsion of a calcified plaque anterior to the insertion of the medial horizontal rectus muscle gave rise to senile scleromalacia. Histopathological examination revealed a second calcified plaque at the site of the contralateral senile scleral plaque in this eye. This case indicates that senile scleromalacia is a scleral disease sui generis which occurs by expulsion of a calcified plaque in advanced cases of senile scleral plaques. Senile scleromalacia has not previously been described as a clinical entity.

Age Factors↗
PubMed1978

Intravitreal silicone injection.

A clinico-pathological report is presented of a case of intravitreal silicone injection in which the eye had to be enucleated 7 years later. Numbers of highly refractile silicone particles of various size were found in all the ocular tissues except the sclera. A great number of silicone cavities were present in most tissues, and many contained silicone globules. The presence of silicone within the lens was confirmed by electron microscopy.

Adult↗