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D Meller

Publications and source records attributed to D Meller.

41 records · Page 3Linked to original sources
PubMed1992

Immunohistochemical changes of neuronal calcium-binding proteins parvalbumin and calbindin-D-28k following unilateral deafferentation in the rat visual system.

The neuron-specific calcium-binding proteins, parvalbumin and calbindin-D-28k, were studied in the subcortical visual system of normal and unilaterally deafferented albino rats. Immunohistochemistry with monoclonal antibodies was used on vibratome sections through optic tract (OT), dorsal lateral geniculate nucleus (dLGN), olivary pretectal nucleus (OPN), and superior colliculus (SC). In controls, OT stained strongly for parvalbumin and weakly for calbindin-D-28k. The dLGN contained a plexus of parvalbumin-positive fibers. In dLGN, calbindin-D-28k-antibodies showed strong labeling of some neurons with long dendrites and weak staining of the cytoplasm in other neurons. In OPN, parvalbumin stained a ring of neurons and terminals in the shell region, whereas calbindin-D-28k was contained in medial cell populations. In SC, parvalbumin was contained in fibers, terminals, and neurons throughout the visual layer. Calbindin-D-28k showed a laminar distribution of neurons with a predominance in deep portions of superficial grey matter and in ventral portions of stratum opticum. Following unilateral deafferentation induced by optic nerve section, retinal axons showed immunohistochemical changes related to Wallerian degeneration and target neurons reacted by changes of calcium-binding proteins. Parvalbumin and calbindin-D-28k immunostaining decreased during Wallerian degeneration of OT. In the deafferented dLGN, immunohistochemical labeling for calbindin-D-28k declined in strongly stained neurons from 4 to 21 days after lesion. Measurement of dendritic length per number of cells or per area of dLGN showed a significant decline for the contralateral side at 4, 8, and 21 days (ANOVA, P less than 0.05). In deafferented OPN, terminal-like staining for parvalbumin decreased and neuronal labeling was enhanced. In deafferented SC, the neuronal and dendritic staining for parvalbumin increased beginning from Day 1 on and persisting at Day 21, whereas fibers and terminal-like elements decreased in staining. Measurement of parvalbumin-positive neurons per area of SC showed a significant increase of labeling in the contralateral side from Day 1 to Day 21 (ANOVA, P less than 0.05). These studies show that cellular responses to deafferentation of visual neurons involve a regulation of calcium-binding proteins. The decline in staining for calbindin-D-28k in dLGN may relate to reduced retinal afferent activity. The progressive cellular changes in parvalbumin staining may be related to unmasking of intrinsic neurons after removal of parvalbumin-containing, afferent fibers and terminals. Additionally, the changes of parvalbumin labeling in SC neurons may reflect a plastic reorganization of local circuits known to occur in rat SC in response to deafferentation.

Afferent Pathways↗
PubMed1988

Characterisation of theophylline metabolism by human liver microsomes. Inhibition and immunochemical studies.

Anti-human NADPH-cytochrome P-450 reductase inhibited all theophylline metabolic pathways confirming the involvement of cytochrome P-450 isozymes in the metabolism of theophylline. Tolbutamide, debrisoquine, mephenytoin, theobromine, phenylbutazone, sulphaphenazole and sulphinpyrazone did not inhibit theophylline metabolism by human liver microsomes. Verapamil and dextropropoxyphene were non-selective competitive inhibitors of theophylline metabolism. Cimetidine and caffeine selectively inhibited the two demethylations as Ki values for these two pathways were lower than for the 8-hydroxylation pathway. The effects of nifedipine, propranolol and alpha-naphthoflavone were atypical. The degree of inhibition by propranolol reached a plateau, which was greater for the two demethylations than for the 8-hydroxylation. Alpha-naphthoflavone (ANF) at low concentrations inhibited the demethylations to a greater extent than the 8-hydroxylation. At higher concentrations ANF activated all pathways, with this effect being most marked for the 8-hydroxylation. Nifedipine inhibited the theophylline demethylations but not the 8-hydroxylation. In some livers the 8-hydroxylation was markedly activated. The results confirm that there are at least two distinct cytochrome P-450 isozymes involved in theophylline metabolism, one isozyme being involved with the demethylations and a different isozyme involved in the 8-hydroxylation pathway. Preliminary correlation studies suggest that the human orthologue to the rabbit polycyclic hydrocarbon inducible P-450 Form 4 may be involved in the N-demethylations of theophylline.

Adult↗
PubMedDate not supplied

Conjunctivochalasis: literature review and possible pathophysiology.

Conjunctivochalasis, defined as a redundant conjunctiva typically located between the globe and the lower eyelid, is not uncommon. However, it is often overlooked, as it may be considered a normal senile change. Conjunctivochalasis can cause a spectrum of symptoms, ranging from aggravation of a dry eye at the mild stage, to disturbance of tear outflow at the moderate stage, and exposure problems at the severe stage. Clinical recognition of its pathogenic role helps differentiate conjunctivochalasis from other diseases that may generate similar symptoms. For symptomatic patients, topical lubricants can be tried, but they are frequently unsuccessful, and surgical excision may be required. To guide future investigation into the clinical significance of conjunctivochalasis, a comprehensive grading system and a hypothetical pathophysiology are proposed. Special attention is given to the relationship of conjunctivochalasis to tear dynamics.

Conjunctival Diseases↗
PubMedDate not supplied

Corneal epithelial dots following excimer laser photorefractive keratectomy.

BACKGROUND: Map-dot-fingerprint epithelial changes of the cornea have been reported to occur as a consequence of trauma or surgical procedures, such as radial keratotomy. METHODS: We describe a case of dot-like changes in the corneal epithelium following excimer laser photorefractive keratectomy for the correction of myopia. Because the lesions were located centrally, possibly reducing visual acuity, the epithelium was removed mechanically. RESULTS: Dot-like changes recurred in the same areas 4 weeks after epithelial debridement. Best spectacle-corrected visual acuity improved from 20/200 to 20/100 and remained stable thereafter. CONCLUSIONS: Photorefractive keratectomy can lead to abnormal regeneration of epithelium basement membrane, possibly resulting in dot-like changes of corneal epithelium.

Adult↗