Ethnicity and self-reported experiences of stigma in adults with intellectual disability in Cape Town, South Africa.

BACKGROUND: Studies have shown that individuals with intellectual disability (ID) are aware of stigma and are able to describe experiences of being treated negatively. However, there have been no cross-cultural studies examining whether self-reported experiences of stigma vary between ethnic groups. METHOD: Participants with mild and moderate ID were recruited from a number of different settings in Cape Town, South Africa. Self-reported experiences of stigma in three ethnic groups were measured using the South African version of the Perceived Stigma of Intellectual Disability tool, developed by the authors. One-way anova was used to test whether there were differences in the total stigma score between the ethnic groups. Regression analysis was performed to identify factors associated with stigma. RESULTS: A total of 191 participants agreed to take part; 53 were Black, 70 were of mixed ethnicity and 68 were Caucasian. There were no differences in the levels of stigma reported by the three groups but the Black African ethnic group were more likely to report being physically attacked and being stared at, but were also more likely to report that they thought they were 'the same as other people'. There was an interaction effect between ethnicity and level of ID, with participants with mild ID from the Black African group reporting higher levels of stigma compared with those with moderate ID. Younger age was the only factor that was associated with stigma but there was a trend towards ethnicity, additional disability and socio-economic status being related to stigma. CONCLUSION: Interventions should target the Black African community in South Africa and should include the reduction of both public stigma and self-reported stigma.

Genetic origin of mutations predisposing to retinoblastoma.

Retinoblastoma is one of several human tumors to which predisposition can be inherited. Molecular genetic analysis of several nonheritable cases has led to the hypothesis that this tumor develops after the occurrence of specific mitotic events involving human chromosome 13. These events reveal initial predisposing recessive mutations. Evidence is presented that similar chromosomal events occur in tumors from heritable cases. The chromosome 13 found in the tumors was the one carrying the predisposing germline mutation and not the homolog containing the wild-type allele at the Rb-1 locus. These results suggest a new approach for identifying recessive mutant genes that lead to cancer and a conceptual basis for accurate prenatal predictions of cancer predisposition.

MICRODOSIMETRIC MEASUREMENT OF SECONDARY RADIATION IN THE PASSIVE SCATTERED PROTON THERAPY ROOM OF iTHEMBA LABS USING A TISSUE-EQUIVALENT PROPORTIONAL COUNTER.

Measurements of the dose equivalent at different distances from the isocenter of the proton therapy center at iThemba LABS were previously performed with a tissue-equivalent proportional counter (TEPC). These measurements showed that the scattered radiation levels were one or two orders of magnitude higher in comparison to other passive scattering delivery systems. In order to reduce these radiation levels, additional shielding was installed shortly after the measurements were done. Therefore, the aim of this work is to quantify and assess the reduction of the secondary doses delivered in the proton therapy room at iThemba LABS after the installation of the additional shielding. This has been performed by measuring microdosimetric spectra with a TEPC at 11 locations around the isocenter when a clinical modulated beam of 200 MeV proton was impinging onto a water phantom placed at the isocenter.

SOI microdosimetry and modified MKM for evaluation of relative biological effectiveness for a passive proton therapy radiation field.

With more patients receiving external beam radiation therapy with protons, it becomes increasingly important to refine the clinical understanding of the relative biological effectiveness (RBE) for dose delivered during treatment. Treatment planning systems used in clinics typically implement a constant RBE of 1.1 for proton fields irrespective of their highly heterogeneous linear energy transfer (LET). Quality assurance tools that can measure beam characteristics and quantify or be indicative of biological outcomes become necessary in the transition towards more sophisticated RBE weighted treatment planning and for verification of the Monte Carlo and analytical based models they use. In this study the RBE for the CHO-K1 cell line in a passively delivered clinical proton spread out Bragg peak (SOBP) is determined both in vitro and using a silicon-on-insulator (SOI) microdosimetry method paired with the modified microdosimetric kinetic model. The RBE along the central axis of a SOBP with 2 Gy delivered at the middle of the treatment field was found to vary between 1.11-1.98 and the RBE for 10% cell survival between 1.07-1.58 with a 250 kVp x-ray reference radiation and between 1.19-2.34 and 0.95-1.41, respectively, for a Co60 reference. Good agreement was found between RBE values calculated from the SOI-microdosimetry-MKM approach and in vitro. A strong correlation between proton lineal energy and RBE was observed particularly in the distal end and falloff of the SOBP.

Experimental epiretinal membranes induced by intravitreal carbon particles.

We injected 20-nm carbon particles into the vitreous of 14 young rabbits that were killed eight to ten weeks later. Histologic examination showed partial posterior vitreous detachments, epiretinal cellular proliferation, and membranes in all eyes and retinal detachments in five eyes. Electron microscopy disclosed that the epiretinal membranes were formed mainly by Müller cell expansions, astrocytes, and macrophages. Müller cells penetrated the internal limiting membrane and removed carbon particles from the vitreous by endocytosis. The experiments indicated that gaps are produced in the internal limiting membrane by glial cells and macrophages that invade the vitreous in an attempt to remove foreign material. The experimental epiretinal membranes resembled idiopathic preretinal gliosis or macular pucker.

Two cases of primary bilateral malignant melanoma of the choroid.

The first two Swedish cases of primary bilateral malignant melanoma of the choroid are presented. In one case bilateral histological confirmation was obtained as both eyes were enucleated. In the other case one eye was enucleated and the other irradiated with an episcleral ruthenium plaque. Sweden has a population of 8.38 millions, so that bilateral choroidal melanomas may be less rare than previously thought.

[A study of children with retinoblastoma. Diagnosis is often delayed]. / Studie av barn med retinoblastom. Ofta fördröjd diagnos.

Retinoblastoma is an uncommon but highly malignant ocular tumour of the early childhood. The delay in diagnosis following presentation at a health care facility was studied for 22 consecutive cases derived from the National Retinoblastoma Center in Sweden. Four of the children were regularly examined owing to a family history of retinoblastoma, but among the remaining 18 children the delay in diagnosis exceeded one month in five cases (including all children presenting with squint). However, there was no appreciable delay once appropriate fundus examination had been performed, thus stressing the need of early ophthalmological assessment in all cases of children manifesting signs consistent with retinoblastoma.

Evidence for an enhanced fibrinolytic capacity in cirrhosis as measured with two different global fibrinolysis tests.

BACKGROUND AND OBJECTIVES: It has been known for a long time that cirrhosis is associated with hyperfibrinolysis, which might contribute to an increased risk and severity of bleeding. However, recent papers have questioned the presence of a hyperfibrinolytic state in cirrhotic patients and postulated a rebalanced system owing to concomitant changes in both pro- and anti-fibrinolytic factors. Therefore we re-investigated the fibrinolytic state of cirrhotic patients using two different overall tests including a recently developed test for global fibrinolytic capacity (GFC) using whole blood. PATIENTS AND METHODS: Blood was collected from 30 healthy controls and 75 patients with cirrhosis of varying severity (34 Child-Pugh A, 28 Child-Pugh B and 13 Child-Pugh C). The plasma clot lysis time (CLT), which is inversely correlated with fibrinolysis, was determined as well as the GFC. RESULTS: The mean CLT was 74.5 min in the controls and decreased significantly to 66.9 min in Child-Pugh class A patients, 59.3 min in class B patients and 61.0 min in class C patients, and hyperfibrinolysis existed in 40% of the patients. The median GFC was 1.7 µg mL(-1) in the controls and increased significantly to 4.0 µg mL(-1) in Child-Pugh class A patients, 11.1 µg mL(-1) in class B patients and 22.5 µg mL(-1) in class C patients, and hyperfibrinolysis existed in 43% of the patients. Taken together, 60% of the patients showed hyperfibrinolysis in at least one of the two global assays. CONCLUSION: A rebalanced fibrinolytic system may occur, but hyperfibrinolysis is found in the majority of patients with cirrhosis.