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J G Flannery

Publications and source records attributed to J G Flannery.

34 records · Page 2Linked to original sources
PubMed1988

A diurnal rhythm in opsin content of Rana pipiens rod inner segments.

Quantitative electron microscope immunocytochemistry, employing an antibody specific to opsin, was used to evaluate the amount and location of opsin in Rana pipiens rod photoreceptors throughout a 24 hr light/dark cycle. We found a distinct diurnal rhythm in the density of anti-opsin labeling of the rough endoplasmic reticulum (RER) and Golgi apparatus in the myoid region of the rod inner segment. Opsin labeling of these organelles was lowest at light onset, increasing thereafter by three- to four-fold, and remained high until 2 hr into the dark phase. A fall in labeling density occurred within the following 4 hr, and remained low for the remainder of the dark phase. Our finding of a diurnal rhythm regulating inner segment opsin transport in Rana pipiens contrasts with published observations on outer segment membrane turnover, since it has been shown that the rates of disc formation and disc shedding are governed by environmental lighting alone in this species. These results imply that there is opsin pooling in the inner segment during the first 14 hr of a 24 hr light/dark cycle; thereafter the loss of inner segment opsin due to mobilization of this protein from the Golgi exceeds the rate of formation of new opsin. There was no evidence of accumulation of opsin-containing vesicles near the cilium or in the ellipsoid just prior to light onset. At light onset, prominent opsin labeling was identified at the proximal portion of the outer segment in regions separate from the disc stack. In two separate experiments, additional groups of frogs were killed around the time of light onset and were examined by conventional transmission electron microscopy. Disordered disc membranes were seen at the base of the outer segment which were not in register with the disc stack. These disordered membranes were observed as early as 2 hr before light onset, and were no longer observed by 1 hr after light onset. We suggest that these disordered membranes reflect a step in the biogenesis of new discs, serving as a pool of membrane that forms during the later part of the dark cycle. It appears that light onset triggers the ordering of neatly registered discs from this new membrane, rather than assembly of new membrane from pooled transport vesicles in the inner segment.

Animals↗
PubMed1986

Membrane receptors for retinol-binding protein in cultured human retinal pigment epithelium.

The retinal pigment epithelium (RPE) is responsible for transport of retinol from the choroidal circulation to the photoreceptors. In the intact eye, this process is mediated by membrane receptors for plasma retinol binding protein (RBP) distributed basolaterally on the RPE cells. We have shown that cultured human RPE expresses this receptor. A binding curve exhibiting saturation was generated by incubating enzymatically detached epithelial sheets with increasing concentrations of 125I-labelled RBP. 125I-RBP binding experiments also show that the receptor is expressed at a high level in first passage subcultures, suggesting de novo synthesis, and that basally oriented receptors predominate over those associated with the apical surface, reflecting the polarization characteristic of RPE in vivo. Cultured RPE can internalize 3H-retinol carried by RBP, resulting in synthesis of labelled retinyl palmitate. Production of labelled retinyl ester is competitively inhibited when incubations include an excess of holo-RBP containing non-radioactive retinol. These results indicate that RBP not only binds to the receptor specifically, but also that this interaction is functional, effecting uptake of retinol by the RPE cells. The expression of this property of differentiated RPE favors the use of cultured RPE as a model system for studying vitamin A transport and metabolism.

Adolescent↗
PubMed1985

Distribution patterns of photoreceptors, protein, and cyclic nucleotides in the human retina.

The concentration of cGMP, cAMP, protein and the number of cone and rod photoreceptors have been measured in parallel arrays of punches, 3 mm in diameter, taken from each quadrant of normal human retinas. A separate punch containing the fovea and parafoveal region was also analyzed. Eyes were obtained from four male donors ranging in age from 35 to 67 yr. The retina thins considerably from the center to the periphery, and consequently the protein content forms a gradient in the same direction. Similar gradients were observed for cAMP and cGMP concentrations. In all eyes studied, the foveal-parafoveal region had higher levels of cAMP than cGMP. The data was analyzed with the aid of a computer in order to obtain three-dimensional maps of the patterns of distribution of the different parameters. A strong correlation between the areas of higher cone density, non-photoreceptor neurons, and cAMP, and an equally strong correlation between rod distribution and that of cGMP was observed. These maps will serve as baseline data in studies of pathological conditions such as retinitis pigmentosa.

Adult↗
PubMed1984

Circadian disc shedding in Xenopus retina in vitro.

To further examine the endogenous rhythm of disc shedding and phagocytosis observed in several species, adult Xenopus were entrained to a 12 hr light/12 hr dark cycle and then placed in constant darkness. At various times during a 3-day period of constant darkness, eyes were explanted and placed into culture medium, then processed for light and electron microscopy. A clear rhythmicity of disc shedding was observed, with pronounced peaks at the times light onset occurred in the original entrainment cycle. Modification of the HCO3- ion concentration in the medium was found to raise the amplitude of the peak of endogenous disc shedding. Explants maintained in culture medium containing deuterium oxide (a compound known to perturb circadian oscillators) were found to shed with a longer interval between peaks. The addition of the protein synthesis inhibitor, anisomycin, to this preparation suppressed the shedding rhythm. The action of anisomycin was investigated by autoradiographic examination of the pattern of 3H-leucine uptake and protein synthesis by the explant. The findings suggest the presence of a circadian oscillator for rhythmic disc shedding within the amphibian eye.

Animals↗
PubMed1979

Psychiatric implications of the mitral valve prolapse syndrome (MVPS).

The mitral valve prolapse syndrome (MVPS) is an infrequent outcome of mitral valve prolapse, a common and usually benign structural abnormality. Psychiatric patients often present with symptoms indistinguishable from MVPS, knowledge of which is thus essential for differential diagnosis. Even when prolapse of the mitral valve is detected, the symptoms may be variously determined by both physical and emotional factors. Four illustrative case histories are presented.

Adult↗
PubMed1979

Light-triggered rod disc shedding in Xenopus retina in vitro.

The present study was designed to determine whether light-induced rod outer segment disc shedding occurs when the eye is isolated from the rest of the organism. Whole eye explants of Xenopus laevis were maintained in vitro and either exposed to 5 min of light or kept in darkness. In both the in vitro eyes and in vivo controls exposed to the same conditions, a significant degree of disc shedding occurred within 1 hr of the light stimulus. The disc shedding response was larger in the explanted eyes than in the intact animals. In explants exposed to [3H]leucine for 24 hr, a radioactive band formed at the base of rod outer segments. Thus both light-stimulated disc shedding and disc synthesis occur in the eye kept in vitro. The results of this study are compatible with other recently reported results suggesting that rod disc shedding is initiated within the eye.

Animals↗
PubMed1979

Dimensions of a single word-association in the analyst's reverie.

The reverie, an apparently random series of events occurring in the analyst's consciousness when his attention is evenly suspended, is examined through the expansion of one of its elements, a single word-association. When this expansion is compared with other data in the analysis, the reverie appears to be both continuous and self similar.

Adult↗
PubMed1978

Alexithymia. II. The association with unexplained physical distress.

Unexplained physical distress, when associated with alexithymia, becomes a diagnostic puzzle leading to prolonged investigation, ineffective treatment, and psychiatric referral. The persistent, often almost indescribable quality of the distress suggests a central disturbance of the mechanism of pain experience involving the limbic system and the endogenous opiates.

Communication↗
PubMedDate not supplied

Characterization of aldehyde dehydrogenase-positive amacrine cells restricted in distribution to the dorsal retina.

A class 1 aldehyde dehydrogenase (ALDH) catalyzes oxidation of retinaldehyde to retinoic acid in bovine retina. We used immunocytochemistry and in situ hybridization to localize this enzyme in adult and fetal bovine retinas. Specific ALDH immunoreactivity was present in the cytoplasm of wide-field amacrine cells restricted in distribution to the dorsal part of the adult retina. The somata diameters ranged from approximately 8 microns to approximately 15 microns, and the cells increased in density from approximately 125 cells/mm2 near the horizontal meridian to approximately 425 cells/mm2 in the superior far periphery. The ALDH-positive cells had somata on both sides of the inner plexiform layer (IPL) and processes in two IPL strata. The majority of ALDH-positive cells were unreactive with antibodies against known amacrine cell enzymes and neurotransmitters, including GABA and glycine. The ALDH-positive amacrine cells also did not react with anti-cellular retinoic acid-binding protein, which was present in a subset of GABA-positive amacrine cells. In flat-mounted retinas processed by in situ hybridization, the larger ALDH-positive amacrine cells tended to be more heavily labeled. In addition to amacrine cells, Müller cell processes in the inner retina were weakly immunoreactive for ALDH; however, these glial cells did not contain ALDH mRNA. The pattern of ALDH expression in fetal bovine retinas was documented by immunocytochemistry. No ALDH reactivity was found before 5.5 months; for the remainder of the fetal period, ALDH immunoreactivity was present in amacrine cells similar to those in adult retina. The ALDH-positive amacrine cells in bovine retina are novel, being limited in distribution to the dorsal retina and unlabeled with other amacrine cell-specific markers. Identification of ALDH in amacrine cells provides additional evidence that cells of the inner retina are involved in retinoid metabolism.

Aging↗
PubMedDate not supplied

Voltage-gated Na+ channel EOIII-segment-like immunoreactivity in fish retinal ganglion cells.

Although single-channel and whole-cell patch-clamp recordings have demonstrated the presence of Na+ currents in retinal ganglion cell somata, it has not previously been reported that an anti-Na+-channel antiserum stains both retinal ganglion cell somata and proteins with molecular weights corresponding to complexes of alpha and beta subunits. We probed adult goldfish retinas for Na+ channel-like immunoreactivity with a polyclonal antibody directed against the EOIII segment of vertebrate voltage-gated Na+ channels. In vertical sections and whole mounts, this antibody consistently stained the somata, axons, and proximal dendrites of retinal ganglion cells. Some somata in the proximal third of the inner nuclear layer were also stained. In Western blots, this antibody specifically stained multiple protein bands from retina and optic nerve, all with apparent molecular weights between 200 and 315 kDa. The largest of these molecular weights agrees with that reported previously for complexes of alpha and beta subunits in mammalian neurons, including retinal ganglion cells. The intermediate and lowest molecular weights are consistent with the presence of multiple Na+ channel alpha subunits, either in individual proximal retinal neurons or in different morphological subtypes.

Animals↗