Metalloprotease activity in a small heat shock protein of the human malaria parasite Plasmodium vivax

The malaria parasite affects millions of people each year, lives and multiplies in two different hosts, and synthesizes a large number of proteases and heat shock proteins (HSPs) for its survival. We describe here the characterization of a metalloprotease activity which resides in the small HSP (PVHSP28) of the common but noncultivable human malaria parasite Plasmodium vivax. The protein is expressed by erythrocytic stages of the parasite. It is expressed as a approximately 55-kDa polypeptide which is then processed to the 28-kDa mature protein. The latter was found to be an active protease in gelatin zymography. This protease showed its optimal activity at 37 degrees C (pH 7.6). It also retained its proteolytic activity at higher temperatures of up to 55 degrees C. The enzyme belongs to the metalloprotease class, as its proteolytic activity was most effectively blocked by 1,10-phenanthroline and was restored to a maximal level by the addition of zinc metal ions. Inhibitors for the cysteine, serine, and aspartate classes of proteases were ineffective against this enzyme. A homology search indicates that PVHSP28 probably belongs to a new class of HSPs which possess the metalloprotease signature sequence.     

Polymerase chain reaction for detection of Mycobacterium tuberculosis in epiretinal membrane in Eales' disease

PURPOSE: Tuberculous etiology has been suggested in Eales' disease. Because epiretinal membrane (ERM) is formed on the inner surface of the retina in Eales' disease, it could be the most appropriate intraocular specimen for investigation. Therefore, a nested polymerase chain reaction (nPCR), which detects MPB64 gene of Mycobacterium tuberculosis on the archival specimens of ERM of well-documented Eales' and non-Eales' patients, was applied and the results compared. METHODS: nPCR technique was standardized, and the sensitivity and specificity of the primers were determined. nPCR technique was applied to tissue sections obtained from formalin-fixed and paraffin-embedded tissues of ERM from 23 patients with Eales' disease and 27 noninfective and non-Eales' disease patients as controls. RESULTS: nPCR technique was specific for M. tuberculosis genome and sensitive enough to detect 0.25 fg (corresponding to the presence of a single bacillus). Eleven (47.8%) ERM of 23 Eales' disease and 3 (11.1%) of 27 controls were positive for M. tuberculosis genome. The difference between the two groups was statistically significant (P = 0.001), indicating association of this bacterium with Eales' disease. CONCLUSIONS: The demonstration of the presence of M. tuberculosis DNA by nPCR technique in significant number of ERM of Eales' disease compared with the controls further emphasizes the probable role of this bacterium in the pathogenesis of this enigmatic clinical condition.     

Conjunctival rhinosporidiosis associated with scleral melting and staphyloma formation: diagnosis and management

PURPOSE: Although conjunctival rhinosporidiosis is endemic in India, associated scleral melting and staphyloma formation are quite rare. We report clinical features and management in three patients with this unusual presentation. METHODS: Retrospective review of case records of three patients with conjunctival rhinosporidiosis. RESULTS: Infection occurred in young, healthy adults and was localized to the forniceal conjunctiva in all patients. The affected conjunctiva had numerous grey-white spherules, but a polyp-like lesion was not present in any patient. Diagnosis was based on clinical features and examination of scrapings from the involved conjunctiva. Treatment was surgical, with excision of infected conjunctival tissues and staphyloma repair with homologous sclera or autogenous periosteum. Failure to recognize the conjunctival pathology in one patient resulted in recurrence of the staphyloma. CONCLUSION: Conjunctival rhinosporidiosis can be associated with scleral staphyloma in young, healthy, adults. Differentiating this entity from idiopathic scleral ectasia requires knowledge of the clinical features of conjunctival rhinosporidiosis and a high index of clinical suspicion.     

Acute panuveitis with haemorrhagic hypopyon as a presenting feature of acquired immunodeficiency syndrome (AIDS)

Anterior uveitis is a known clinical entity in herpes zoster ophthalmicus associated with AIDS. However, reports of acute haemorrhagic hypopyon uveitis in such cases are lacking. Herein we describe a young male patient presenting with acute panuveitis with haemorrhagic hypopyon, who was found HIV positive on investigation.     

Eales disease--an update

Eales disease, first described by Henry Eales in 1880, remains an enigma. The disease, observed more commonly in the Indian subcontinent than in the rest of the world, occurs in young healthy adult males, initially presenting as retinal periphlebitis and later as retinal ischemia that may lead to vascular alterations and neovascularization. Recurrent vitreous hemorrhage with or without retinal detachment is the common sequelae. In recent years, immunological, molecular biological, and biochemical studies have indicated the role of human leukocyte antigen, retinal autoimmunity, mycobacterium tuberculosis genome, and free radical mediated damage in the etiopathogenesis of this disease. However, its etiology appears to be multifactorial. The management depends on the stage of the disease and consists of medical treatment with oral corticosteroids in the active inflammatory stage and laser photocoagulation in the advanced retinal ischemia and neovascularization stages. The results of vitreoretinal surgery have been found to be satisfactory in case of vitreous hemorrhage with or without retinal detachment.     

Oncocytoma of the caruncle

A rare case of oncocytoma of the caruncle in a 75-year-old female is reported. Clinical differential diagnosis and histopathologic features are discussed.     

Clinical profile and immunological status of cytomegalovirus retinitis in organ transplant recipients

PURPOSE: Cytomegalovirus retinitis (CMV) is the most common ocular opportunistic infection in transplant recipients. This retrospective study attempts to report the differences in occurrence of cytomegalovirus retinetis in transplant recipients from those reported in patients with acquired immunodeficiency syndrome (AIDS). METHODS: 25 eyes of 15 transplant recipients (14 renal and one cardiac) with cytomegalovirus retinitis were retrospectively reviewed. Immunological profile included CD4+ and CD8+ T lymphocyte counts, CD4+/CD8+ cell ratio (5 cases) and serology for the viral antibodies (8 cases). RESULTS: A predominantly bilateral presentation (60%) was noted. Active cytomegalovirus retinitis (72%) in zone 2 (92%) of the inferotemporal quadrant (68%) was noted. The average cell counts were within normal limits (mean CD4 cell count-711/microliter), unlike in late stages of AIDS with cytomegalovirus retinitis (CD4 count < 50/microliter). Serology revealed an IgM positivity of 53%. Retinal detachment (52%) was the most common complication occurring after an average of 5.4 months. CONCLUSION: CMV retinitis in organ transplant recipients appears to differ from that in AIDS patients. CMV retinitis presents early and has different immunological profile, probably owing to differences in pathogenesis.     

Cytopathology of explanted intraocular lenses and the clinical correlation

PURPOSE: To study the cytopathological features of explanted intraocular lenses (IOLs) and correlate the features with their clinical presentation. SETTING: Ocular Pathology Department, Medical and Vision Research Foundation, Sankara Nethralaya, Chennai, India. METHODS: The study comprised 61 explanted IOLs (48 posterior chamber IOLs and 13 anterior chamber IOLs) removed for the following reasons: pseudophakic bullous keratopathy (36), recalcitrant uveitis (7), retinal detachment (10), endophthalmitis (5), uveitis (7), IOL subluxation (2), and painful blind eye (1). The IOLs were stained with hematoxylin and eosin using a simple cytological technique. The cytopathological features were studied and correlated with the clinical presentations. RESULTS: The mean time of IOL explantation was 10.1 months after surgery. Twenty-one IOLs had granulomatous and nongranulomatous inflammations and 4, nongranulomatous inflammations. One IOL had fungal filaments on the surface. CONCLUSIONS: Intraocular lenses can produce both granulomatous and nongranulomatous inflammation. Granulomatous inflammation was the most common in this series. The surface of IOLs explanted because of intraocular infection may show infective agents.