Alphonse E. Leure-Dupree

Immunoelectron microscopic localization of the opioid growth factor receptor (OGFr) and OGF in the cornea.

This study was conducted to determine the cellular and subcellular location(s) of the opioid growth factor receptor (OGFr), and the opioid growth factor (OGF), [Met(5)]-enkephalin, in the corneal epithelium. Laser scanning confocal microscopy analysis revealed that both OGFr and OGF were colocalized in the paranuclear cytoplasm and cell nuclei in basal, as well as suprabasal, cells of adult rat corneal epithelium. Using a postembedding immunogold procedure for immunoelectron microscopy that included embedding in Unicryl, both single- and double-face labeling studies were performed. Immunogold labeling of OGFr was detected on the outer nuclear envelope, in the paranuclear cytoplasm proximal to the nuclear envelope, perpendicular to the nuclear envelope in a putative nuclear pore complex, and within the nucleus adjacent to heterochromatin. Immunoreactivity for OGF was noted in locations similar to that for OGFr. In addition, aggregates of staining for OGF were found throughout the cytoplasm, including subjacent to the plasma membrane. Double labeling experiments revealed that complexes of OGF-OGFr were colocalized on the outer nuclear envelope, in the paranuclear cytoplasm, extending across the nuclear pore complex, and in the nucleus. Anti-OGFr IgG by itself, but not anti-OGF IgG alone, was associated with the outer nuclear envelope, and uncomplexed OGF immunoreactivity was detected in the cytoplasm in dual labeling experiments. These results based on complementary approaches of confocal microscopy and immunoelectron microscopy, suggest that: (i) OGFr resides on the outer nuclear envelope, (ii) OGF interacts with OGFr at the outer nuclear envelope, (iii) the colocalized receptor and peptide translocates between the cytoplasm and the nucleus at the nuclear pore, and (iv) signal transduction for modulation of cell proliferation necessitates a peptide-receptor complex that interfaces with chromatin in the nucleus.

Pathophysiology and Electron Microscopy of Melanomalytic Glaucoma

We examined an eye with melanomalytic glaucoma by quantitative aqueous perfusion, light and electron microscopy. Facility of outflow was markedly diminished from normal in vivo and in vitro. The trabecular meshwork was heavily laden on its surface and in the intertrabecular spaces with macrophages. Many of these cells appeared to be wandering macrophages, while some appeared to be detached, phagocytic trabecular endothelial cells.

Effects of zinc deficiency on protein synthesis and expression of specific mRNAs in rat liver

The effects of zinc deficiency on protein synthesis and expression of specific mRNAs were assessed in rat liver. Zinc deficiency had no apparent effect on liver weight, protein content, or RNA content when these properties were compared with values obtained using pair-fed rats. However, zinc deficiency resulted in a lower rate of hepatic protein synthesis. The decreased rate of protein synthesis was due to a decrease in the rate of synthesis of proteins retained in the liver, with no apparent change in the synthesis of secreted proteins. Analysis of expression of specific gene products, as assessed by in vitro translation of total RNA followed by two-dimensional gel analysis, showed that the expression of only a few mRNAs was altered by zinc deficiency. The patterns of change in gene expression resulting from zinc deficiency varied from almost complete repression to full expression. In additional studies, cDNA clones to serum retinol-binding protein and transthyretin were used to examine the effect of zinc deficiency on the relative abundance of mRNA for these two proteins. The relative abundance of mRNA for transthyretin was specifically elevated as a result of zinc deficiency. In contrast, the relative abundance of mRNA for hepatic serum retinol-binding protein was increased in both zinc-deficient and pair-fed rats. Therefore, the observed change in mRNA for serum retinol-binding protein was apparently at least in part due to the inanition that accompanies zinc deficiency. Overall, the results suggest that zinc can regulate the synthesis of specific proteins in rat liver through changes in the relative abundance of specific mRNAs.

Ependymal Alterations in Hydrocephalus

The brain is a hollow organ. Its cavities, the cerebral ventricles, are filled with cerebrospinal fluid (CSF), which resembles brain extracellular fluid.18, 60a Ventricular CSF has two sources. The primary site of ventricular fluid formation is the choroid plexus.12 At this site, CSF is actively secreted by choroid plexus cells into the ventricular cavities.12, 18, 94, 98 A second source of ventricular CSF is the brain extracellular space. Extracellular fluid reaches the ependymal lining by diffusion and by bulk flow, and it passes between adjacent ependymal cells to enter the ventricular cavities.11, 30 Ventricular CSF is actively pumped by arterial pulsations within the choroid plexus4 and moves by bulk flow from the lateral ventricles to the third ventricle (where more CSF may be added), through the aqueduct of Sylvius, to the fourth ventricle, and thence into the subarachnoid space 14, 23 CSF is then carried over the cerebral hemispheres and resorbed through arachnoid villi lying in the convexity dura.14 As is the case with any hollow viscus (for example, the intestine or bladder), obstruction of the flow of its contents is accompanied by proximal dilatation of its lumen.15 In the brain, this condition is termed hydrocephalus.

Zinc deficiency affects the composition of the rat adrenal gland.

The response of the adrenal gland to zinc deficiency was examined in male weanling rats. In comparison with decapsulated adrenals from ad libitum fed controls, glands from zinc deficient rats had greater relative weight (mg/g body wt), DNA concentration, and total lipid and cholesterol concentrations as well as a smaller protein/DNA ratio. Several of these differences (protein/DNA and cholesterol concentration) could be attributed to the inanition accompanying zinc deficiency, as zinc deficient values were similar to those of pair fed controls. Values for total DNA and protein concentration were similar for all groups. Electron micrographs of the zona fasciculata showed a small number of lipid droplets in the adrenals from ad libitum fed controls, an increase in lipid droplets from pair fed controls, and an even more striking increase in lipid droplets from the zinc deficient adrenals. The increased adrenal lipid composition in the zinc deficient group may be secondary to enhanced steroidogenesis or a zinc deficiency-induced defect of lipid metabolism.