Clinical and pathological findings in three dogs with a corneocentric presentation of nodular granulomatous episcleritis.

PURPOSE: To describe the clinical signs, management, histopathologic findings, and outcome of three dogs with a corneocentric presentation of nodular granulomatous episcleritis (NGE). METHODS: Three dogs of varying breeds were presented for a unilateral, nonpainful, and infiltrative corneal lesion in the dorsal aspect of the eye. Clinical response to symptomatic topical treatment directed at a presumed inflammatory or immune-mediated cause was poor. Due to this, and concerns of neoplasia, ultrasonography (n = 1), incisional biopsy (n = 2), and/or enucleation (n = 2) were performed. RESULTS: The inflammatory infiltrate observed on histopathology was identical to that seen in nodular granulomatous episcleritis in all three cases. However, atypically the inflammation was confined to the cornea and limbus, without episcleral or conjunctival involvement. Inflammation of the cornea was full thickness to Descemet's membrane. Following enucleation (n = 2), there were no postoperative complications, and no reported ophthalmic disease in the remaining eye. Currently, the single non-enucleated case remains controlled with systemic and topical immunosuppression. CONCLUSION: To the best of the authors' knowledge, this is the first report of an NGE condition purely affecting the full thickness of the cornea, without episcleral or conjunctival involvement. The authors propose this to represent an atypical corneocentric variant of NGE. This clinical presentation can resemble neoplasia; incisional biopsy is recommended for a definitive diagnosis. Further research into the optimal treatment strategies for this variant of NGE is required.

Calcium-accumulating cells in the meristematic region of grapevine root apices.

Apical roots of grapevines were examined by cryo-SEM (scanning electron microscopy) and the intracellular distribution of Ca was demonstrated by X-ray microanalysis in different regions of the primary root. We show that large amounts of Ca are accumulated as raphide crystals in the vacuoles of specialised cortical cells (idioblast cells) of the root apex. These crystal idioblast cells appeared to form a discontinuous cone of cells in the outer region of the root meristem. The raphide crystals within these cells were less apparent in older regions of the root, 10-12 mm basipetal to the root tip. We suggest that the raphide crystals could initially act as another Ca sink involved in the regulation of Ca levels in root apices. In older regions of the root these cells are spaced at intervals around the periphery of the cortex and the subsequent disappearance of the raphides may be indicative of remobilisation, perhaps in the zone of elongation where cell wall synthesis occurs and Ca demand is high. Calcium-accumulating cells were also observed in the older regions of the root, forming endodermal protrusions extending into the cortex. These cells may play a part in regulating Ca delivery to the xylem stream by sequestration of Ca from the radial flow of water at the endodermis. The observed distribution of Ca in root apices was different from the other major cations (e.g. K) and anions (e.g. Cl) because high concentrations were localised to specific cells. We interpret the results in the context of a model of the dynamics of grapevine root growth and cell differentiation, and the temporal balance of solute supply from the protophloem and the external medium.

Merlin Pryce (1902-1976) and penicillin: an abiding mystery.

In the scientific and medical pantheon few have received more adulation and honour than Sir Alexander Fleming. Even so it is abundantly clear that his triumphant discovery of penicillin owed much to the work of others, especially Florey and Chain, who accomplished the difficult task of taking penicillin from the test tube to patient. This essay does not attempt a detailed re-examination of that discovery. Rather the present study suggests that even the initial observation on that critical day in September 1928 and its subsequent ramifications were even more complex and perplexing than the accepted version. It is likely that Professor Daniel Merlin Pryce, a somewhat unconventional but gifted son of the Welsh mining valleys played an important, quite possibly a crucial, role in the original observation. However one which, except for a very few occasions, he himself sought to downplay, even virtually to deny.