Ligneous Conjunctivitis Secondary to Viral Conjunctivitis.

ABSTRACT: Ligneous conjunctivitis is a rare cause of chronic conjunctivitis that may be triggered by ocular insults such as trauma or infections. We present an interesting case of ligneous conjunctivitis caused by a viral infection that responded well to conservative management. Topical cyclosporine and heparin are a good treatment regimen that caused resolution of lesions and prevented recurrences.

Germline retinoblastoma without inherited gene mutation: a case report.

Retinoblastoma is the most common primary ocular malignancy in childhood and can occur as a germline or somatic mutation. Recent studies have suggested a higher incidence of retinoblastoma in Hispanic children as compared to non-Hispanic white children of the same ages. We report the ocular findings of a 20 years old Hispanic male with a history of bilateral retinoblastoma. Although screening is currently performed with the red reflex test, analysis of current literature suggests the need to reassess screening recommendations for retinoblastoma.

Rb regulates fate choice and lineage commitment in vivo.

Mutation of the retinoblastoma gene (RB1) tumour suppressor occurs in one-third of all human tumours and is particularly associated with retinoblastoma and osteosarcoma. Numerous functions have been ascribed to the product of the human RB1 gene, the retinoblastoma protein (pRb). The best known is pRb's ability to promote cell-cycle exit through inhibition of the E2F transcription factors and the transcriptional repression of genes encoding cell-cycle regulators. In addition, pRb has been shown in vitro to regulate several transcription factors that are master differentiation inducers. Depending on the differentiation factor and cellular context, pRb can either suppress or promote their transcriptional activity. For example, pRb binds to Runx2 and potentiates its ability to promote osteogenic differentiation in vitro. In contrast, pRb acts with E2F to suppress peroxisome proliferator-activated receptor gamma subunit (PPAR-gamma), the master activator of adipogenesis. Because osteoblasts and adipocytes can both arise from mesenchymal stem cells, these observations suggest that pRb might play a role in the choice between these two fates. However, so far, there is no evidence for this in vivo. Here we use mouse models to address this hypothesis in mesenchymal tissue development and tumorigenesis. Our data show that Rb status plays a key role in establishing fate choice between bone and brown adipose tissue in vivo.