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S L Semple-Rowland

Publications and source records attributed to S L Semple-Rowland.

29 records · Page 2Linked to original sources
PubMed1993

Loss of serotonin uptake sites and immunoreactivity in rat cortex after dexfenfluramine occur without parallel glial cell reactions.

The frontal cortices of rats which received either D,L- or D-fenfluramine (DFEN) for 4 days were examined 18 h to 2 weeks following treatment for changes in synaptosomal uptake of serotonin (5HT), paroxetine binding, 5HT-immunoreactivity (5HT-IR), and both astrocytic (GFAP) and microglial markers. Additional rats received intracerebroventricular injections of the neurotoxin 5,7-dihydroxytryptamine (DHT). Consistent with previous reports, D,L- and DFEN produced dose-dependent losses of both 5HT uptake and paroxetine binding, and loss of 5HT-IR which coincided with an abnormal or 'swollen' appearance of immunoreactive axon processes. Recovery of these serotonergic indices was greatest following the lowest doses of DFEN, but was absent after 5,7-DHT treatment. No evidence for an increase in GFAP synthesis or microglial activation was observed in frontal cortices of rats treated with either DFEN or 5,7-DHT. We conclude that the presence of swollen 5HT-IR axons in the cortices of both the 5,7-DHT and DFEN groups is insufficient to trigger the glial responses often associated with neuronal degeneration. Thus, it remains to be determined if swollen 5HT-IR axons are a prelude to neurodegeneration, or whether they represent reversible changes in axonal immunochemistry associated with decreases in 5HT levels. The implications of the data for the clinical safety of DFEN are briefly discussed.

Administration, Oral↗
PubMed1992

Visinin: biochemical and molecular comparisons in normal and rd chick retina.

Western, northern and DNA sequence analyses were used to determine if the retinal protein, visinin, is defective in the chicken retinal degeneration mutant, rd. A 22kDa band, corresponding to purified visinin, was stained with equal intensity on Western blots of +/+, +/rd and rd/rd retinal protein probed with a visinin polyclonal antibody. Hybridization of a northern blot of +/+, +/rd and rd/rd poly(A)+ RNA with a random-primer labelled visinin cDNA probe showed a single, equally labelled 1-Kbp band in each of the samples. Finally, no differences were found between the nucleic acid sequences of the 579 bp cDNAs encoding +/+ and rd/rd visinin. We did, however, find one significant difference between our visinin DNA sequence and the previously published chick visinin DNA sequence. We consistently observed a C at position 118 rather than the published T which changes the amino acid residue at position 40 from serine to proline. Based on the results of this study, we conclude that visinin is not defective in the rd chick model of hereditary retinal degeneration.

Amino Acid Sequence↗
PubMed1991

Expression of glial fibrillary acidic protein by Müller cells in rd chick retina.

Accumulation of glial fibrillary acidic protein (GFAP) in Müller cells has been observed in retinas of several mammalian species secondary to genetically induced degeneration and neuronal injury. In the present series of experiments, I have examined the effects of the rd (retinal degeneration) mutation on the expression of GFAP in retinas of chicks homozygous for the mutation (rd/rd) prior to and following the onset of photoreceptor degeneration, which first appears approximately 7 days posthatch (7 dph). Carrier (+/rd) and wild-type (+/+) retinas served as controls. Retinas taken from 1, 7, 21, and 33 dph rd/rd, +/rd, and +/+ chicks were analyzed for the presence of GFAP by immunocytochemical and SDS-PAGE/Western blot techniques. The following immunocytochemical observations were made: (1) GFAP immunostaining was limited to and located throughout the Müller cells. (2) The intensity of GFAP immunostaining increased with age in all three retina types in tissue sections, as well as on immunoblots. (3) The distribution of GFAP staining within rd/rd Müller cells following the onset of degeneration was slightly different from that observed in +/+ and +/rd retinas and was distinguished by increased staining of the cell bodies and the cell processes forming the outer limiting membrane. The results of these experiments show that Müller cells in chick retina contain GFAP. In addition, they suggest that, in contrast to Müller cells in degenerating mammalian retina, Müller cells in rd chick retina do not accumulate large amounts of GFAP in response to degeneration.

Animals↗
PubMed1991

A reliable two-dimensional gel electrophoresis procedure for separating neural proteins.

A facile two-dimensional gel electrophoresis procedure has been developed for the analysis of neural tissue proteins which eliminates the serious problems associated with protein insolubility at the point of sample application onto polymerized first-dimension isoelectric focusing gels. This was accomplished by combining the methods of two previously published procedures. Our procedure provides an alternative method to the complex gel systems often employed for less soluble proteins, and yields very reproducible, high resolution separations. This procedure, which is in routine use in our laboratories for the analysis of total proteins extracted from retina and brain, produces protein patterns that are easily compared using both visual and computer-assisted image analysis techniques. Presented here are the results of a set of experiments designed to identify proteins unique to retina. This procedure should be useful to investigators studying protein changes resulting from genetic mutation, development, drug treatment or disease, in neural tissue as well as in virtually all other tissues.

Animals↗
PubMed1989

Analysis of proteins in developing rd (retinal degeneration) chick retina using two-dimensional gel electrophoresis.

The rd (retinal degeneration) chick possesses an autosomal recessive mutation which results in behavioral and electrophysiological blindness at hatch. Using the technique of two-dimensional gel electrophoresis, we have identified two groups of proteins whose expression in the retina/pigment epithelium/choroid (RET/PE/CH) of +/+, +/rd and rd/rd chicks is related to genotype. The two proteins within Group 1 had an apparent mass (Mr) of 63 kDa and isoelectric points (pI) of 6.48 and 6.55. The four proteins in Group 2 had an apparent Mr of 98 kDa and pI values ranging from 6.08 to 6.25. Quantities of the Group 1 proteins in RET/PE/CH of each of the three types of animals were found to be related to genotype; the amounts of each did not change with development. The expression of the Group 2 proteins in PET/PE/CH was found to change during retinal development. Proteins P98-6.08 (Mr-pI) and P98-6.13 were found in all rd/rd and +/rd RET/PE/CH and in most +/+ embryonic tissues. Proteins P98-6.19 and P98-6.25, which were present in the majority of +/+ embryonic and in all +/+ E21 (hatch RET/PE/CH, did not appear in +/rd tissues until hatch. P98-6.19 and P98-6.25 were never observed in rd/rd RET/PE/CH.

Animals↗
PubMed1987

Cyclic light intensity threshold for retinal damage in albino rats raised under 6 lx.

This study determined the minimum cyclic (12L:12D) light intensity which produces retinal damage in albino (Sprague-Dawley) rats raised from birth to 15 weeks of age under 6 lx (12L:12D). Four experimental light intensities were tested, viz. 1345, 270, 130 and 65 lx. Control animals remained under 6 lx. After various durations of exposure to one of the intensities tested, the retinas of groups of six rats were evaluated for physiological and morphological evidence of light damage. The indices of damage were: (1) histological and morphometric changes in the retina, and (2) changes in the amplitude and latency of the b-wave of the electroretinogram. Light intensities of 1345- or 270 lx severely damage retinas of albino rats raised from birth under 6 lx within 3-7 days of the initiation of light exposure. Exposure to 130- or 65 lx produced much less dramatic changes in the responsiveness and morphology of the retina that did not appear to be permanent. Based on these results, a reasonable estimate for the threshold cyclic-light intensity which produces damage to retinas of albino rats raised under 6 lx lies between 65- and 130 lx, or slightly more than 1 log unit above the light intensity under which the animals were raised. The effects of an animal's light history on retinal susceptibility to light damage are discussed.

Animals↗
PubMed1987

Retinal cyclic light damage threshold for albino rats.

This study determined the minimum cyclic [12L:12D] light intensity which produces retinal damage in albino (Sprague-Dawley) rats raised from birth to 15 weeks of age under a cyclic light intensity of 6 lux. Four experimental light intensities were tested, including: 1345, 270, 130 and 65 lux. Control animals remained under 6 lux. For each of the intensities tested, the retinas of groups of six rats were evaluated after various durations of light exposure for physiological and morphological evidence of light damage. The indices of damage were (a) histological and morphometric changes in the retina and (b) changes in the amplitude of the b-wave of the electroretinogram. The data indicated that light intensities of 1345 or 270 lux severely damaged retinas of albino rats within 3-7 days of the initiation of light exposure. Exposure to 130 or 65 lux produced much less dramatic changes in the responsiveness and morphology of the retina which did not appear to be permanent. Based on these results, a reasonable estimate for the threshold cyclic light intensity which produces damage to retinas of albino rats raised under 6 lux lies between 130 and 270 lux, or approximately 1.3 log units above the light intensity under which the animals were raised.

Animals↗
PubMed1986

The effects of dim cyclic light on pigment epithelial function in the albino rat.

Most pathologies of the outer retina include physiological and morphological changes in the pigment epithelium. The question of pigment epithelial involvement in retinal light damage caused by low intensities of light is still unresolved. In the present study, we investigated the effects of low intensity cyclic light on pigment epithelial function in albino rats. The functioning of the pigment epithelium was assessed electrophysiologically from d.c. recordings of ERG c-waves and sodium azide induced changes in the resting potential. Responses obtained from albino rats raised under low intensity cyclic light (0.63 ft cd. 12:12 L:D) were compared to those obtained from albino rats raised under minimal light exposure conditions (dark-reared) and pigmented rats housed under low intensity cyclic light. We report, for the first time, that albino rats raised from birth under low intensity cyclic light possess c-waves. Their responses were comparable in amplitude and latency to those recorded from pigmented rats housed under similar conditions, but were significantly smaller than those recorded from dark-reared albino rats. The reduction in the amplitudes of the c-waves recorded from cyclic light-reared albino rats was probably not due to retinal light damage. Comparisons of the amplitudes and latencies of ERG b-waves recorded from cyclic light-reared and dark-reared albino rats did not suggest that the retinas of the cyclic light-reared albino rats had been damaged by light. Light microscopic examination of these retinas also provided no evidence for light damage. The transient, positive potential changes recorded from cyclic light-reared albino rats in response to bolus injections of sodium azide were significantly smaller than those recorded from either dark-reared albino rats or pigmented rats housed under low intensity cyclic light. The results of these experiments suggest that the pigment epithelium of albino rats is functionally altered by extremely low intensities of cyclic light.

Albinism↗
PubMed1984

Results from a simple laser color perimeter.

Stimulus size, chromaticity, adaptation, luminance and local adaptation are more easily controlled when laser light rapidly scans the appropriate portion(s) of the visual field. Adaptation of a Ferree-Rand perimeter to the use of He-Ne laser light gives chromatic and achromatic thresholds of relatively low variance.

Adaptation, Ocular↗