Search PubMed⌕ Search

Biomedical subjects

L Olson

Publications and source records attributed to L Olson.

At least 379 records · Page 21Linked to original sources
PubMed1983

The neurological mutation staggerer is expressed in embryonic cerebellar transplants matured in the anterior eye chamber of normal mice.

Transplantation of embryonic day 11 cerebellar anlage to the anterior eye chamber of wildtype recipient mice was used to investigate the intrinsic character of the cerebellar mutation staggerer. One phenotypic expression of the staggerer gene in vivo is a postnatal degeneration of cerebellar granule cells. After 43 days of in oculo development cerebellar buds from homozygous staggerer embryos similarly develop into nervous tissues lacking granule cells. On the other hand, transplants of wildtype cerebellar anlagen contain a large population of granule cells. Both the staggerer and wildtype cerebellar transplants had a survival of large neurons, characteristic of Purkinje, Golgi and deep nuclei cells.

Animals↗
PubMed1983

The level of nerve growth factor (NGF) as a function of innervation. A correlation radio-immunoassay and bioassay study of the rat iris.

A two-site radio-immunoassay for beta NGF demonstrated 5-10 pg of NGF in the normal, adult rat iris. Ciliarectomy or sympathectomy did not significantly alter the amount of NGF after 10 days. However, denervation including all sensory axons (stereotactic lesion distal to the trigeminal ganglion) increased the level to about 100 pg of NGF. Total denervation resulting from homologous transplantation of the iris gave a similar increase after only 2 days. Fibre outgrowth responses evoked by corresponding iris explants in an NGF bioassay supported the results and suggested in addition that sympathetic denervation may cause a moderate transient increase in NGF after 3 days. It seems that sensory nerves in particular influence the level of NGF in a terminal field, either by a high capacity for uptake and removal of NGF or by exerting a negative feed-back on the production or processing of this growth factor.

Animals↗
PubMed1983

Catecholamine content of intracerebral adrenal medulla grafts.

The rotational behavior which is produced by substantia nigra lesions can be decreased by adrenal medulla grafts adjacent to the denervated striatum. Perhaps these grafts secrete dopamine that diffuses into the striatum. In the present study, we measured concentrations of catecholamines in adrenal medulla grafts as compared with the normal adrenal medulla. The grafts were found to have high but extremely variable concentrations of dopamine. In hosts with substantia nigra lesions, concentrations of dopamine in the adrenal medulla grafts were decreased. Substantia nigra lesions, however, tended to increase concentrations of epinephrine in the grafts, while norepinephrine and total catecholamine concentrations were not significantly affected. It is concluded that at least some adrenal medulla grafts contain concentrations of dopamine sufficient to account for their behavioral effects.

Adrenal Medulla↗
PubMed1983

The distribution of acidic coomassie blue-stained proteins from uninvolved human liver, hepatoma, normal colon, primary colon cancer, and colon metastases to the liver, determined by two-dimensional protein electrophoresis.

The distribution of Coomassie blue-stained proteins from uninvolved regions of 4 human livers, from 1 hepatocellular carcinoma, and from 4 samples each of uninvolved colon, primary adenocarcinoma of the colon, and colon cancer metastatic to the liver was analyzed by two-dimensional protein electrophoresis. From a comparison of acidic proteins between pI 3.5 and 6.5, we conclude (1) that the majority (66 of 82) of denoted acidic proteins from 4 normal liver samples were represented in the hepatocellular carcinoma. Fifty-one of 58 proteins denoted in the 4 colon samples were detected in each of the 4 primary colon cancers; (2) that the "normograms" of proteins from normal colon and normal liver differed in many details, and their dissimilar patterns identified the source of the sample; (3) that hepatoma and primary adenocarcinoma of the colon were easily distinguished by their distribution of proteins; (4) that colon cancer metastatic to the liver contained a majority (50/58) of acidic proteins enumerated in primary colon cancer. These results indicate that uninvolved liver and colon and their primary or secondary cancers can be identified by their distribution of electrophoresed acidic proteins.

Adenocarcinoma↗
PubMed1983

Hexachlorophene-induced degeneration of adrenergic nerves: application of quantitative image analysis to Falck-Hillarp fluorescence histochemistry.

Possible toxic effects of hexachlorophene (HCP) on sympathetic adrenergic nerves were studied using Falck-Hillarp fluorescence histochemistry on whole-mounts of albino rat irides. HCP dissolved in 5 microliters DMSO, or DMSO alone, was injected into the anterior chamber of the eye. HCP caused a dose-dependent degeneration of adrenergic nerves, first observable after 7 micrograms and profound after 21 micrograms. One and 3 days after 35 micrograms of HCP there was an almost total loss of adrenergic nerves. Regeneration from remaining non-terminal axons led to an almost complete reformation of the adrenergic nerve plexus after 18 days. The results demonstrate a new aspect of hexachlorophene neurotoxicity, degeneration of peripheral adrenergic nerve terminals and suggest that neurotoxic actions on thin unmyelinated fiber systems should be looked for also in the central nervous system (CNS).

Animals↗
PubMed1983

Attachment and extracellular matrix differences between tendon and synovial fibroblastic cells.

Fibroblasts of the synovium of sheathed tendons were isolated, and their biochemical properties were compared with those of the fibroblasts of the remaining tendon. The synovial cells had a lower attachment efficiency than did the tendon cells. On the day of cell isolation the synovial cells synthesized collagen as 10% of their total protein, whereas the tendon cells synthesized 30% collagen. After growth in fetal bovine serum (FBS), the percentage of collagen synthesized by both populations decreased; however, the synovial cells still made less collagen than did the tendon cells (5 versus 11%). On the basis of cyanogen bromide peptide analysis, the synovial cells were found to synthesize Types I and III collagen in primary culture, whereas the tendon cells synthesized only Type I. The synovial cells also synthesized two to three times less sulfated glycosaminoglycans in culture than did the tendon cells. Thus, the two cell populations differed in attachment efficiency and in their biosynthesis of collagen and sulfated glycosaminoglycans. These differences reflect extracellular matrix differences that have been observed in the tendon in vivo. In addition, the results augment existing data showing that not all fibroblasts have identical phenotypes.

Animals↗
PubMed1983

Postnatal lead exposure alters spontaneous cerebellar Purkinje neuron discharge.

The effects of early postnatal lead administration on the spontaneous activity of cerebellar Purkinje neurons were studied electrophysiologically in adult male Sprague-Dawley rats. Newborn rat litters were divided into three groups and injected daily from Day 1 to Day 20 after birth with 8 mg NaAc/kg, 1 mg PbAc/kg, or 8 mg PbAc/kg intraperitoneally. Purkinje neurons in all three groups showed regular and sustained discharge. However, the mean spontaneous firing rate was significantly lower in the 8-mg PbAc/kg group (26.13 +/- 1.28 Hz) compared to the NaAc controls (32.39 +/- 1.93, P greater than 0.01). Furthermore, the distribution of the firing rates of the Purkinje cells were different in the two groups, with an obvious loss of faster firing cells in the 8-mg PbAc/kg group. No differences were seen between the 1-mg PbAc/kg group and the NaAc controls. As the 8-mg PbAc/kg group weighed significantly less than the NaAc group, malnourished animals were produced by using oversized litters, to control for any changes caused by the lower body weight. However, when compared to concomitantly raised controls, no changes could be seen in Purkinje cell discharge in the malnourished animals. It is concluded that neonatal exposure to lead can cause permanent changes in spontaneous Purkinje cell discharge.

Action Potentials↗
PubMed1983

A lymphocyte-specific cellular enhancer is located downstream of the joining region in immunoglobulin heavy chain genes.

Transcriptional enhancers, originally discovered in viral genomes, are short, cis-acting, regulatory sequences that strongly stimulate transcription from promoters of nearby genes. We demonstrate the existence of an enhancer within a mouse immunoglobulin heavy chain gene. A DNA fragment located between the joining region and the switch recombination region in the intron upstream of the immunoglobulin mu constant region has been linked, in both orientations, to genes coding for rabbit beta-globin or SV40 T antigen. This element enhances the number of correct beta-globin gene transcripts by at least two orders of magnitude and also stimulates production of T antigen. It acts from several hundred to several thousand base pairs up or downstream of a promoter without amplifying template copy number. Of the various cell lines tested, the immunoglobulin gene enhancer functions only in lymphocyte-derived (myeloma) cells. We propose that this tissue-specific enhancer contributes to the activation of somatically rearranged immunoglobulin variable region genes and possibly to abnormal expression of other genes (e.g. c-myc) that become translocated to its domain of influence.

Animals↗
PubMed1983

Astrocytic development in fetal parietal cortex grafted to cerebral and cerebellar cortex of immature rats.

Pieces of cortex cerebri anlage were dissected out from 16- to 17-day-old fetuses and transplanted to the cortical and cerebellar regions of 5- to 6-day-old rat pups. Twelve animals with grafts in the cortical region and 5 animals with grafts in the cerebellar region were studied 1.5-4 months later. Cresyl violet stained sections revealed no gross difference in either cell morphology, cell density or cell distribution between grafts in the two locations. A molecular layer-like zone was present on all free surfaces of the grafts, whether facing a ventricle or the meninges. The astrocytic development was studied using immunohistochemistry with antibodies against glial fibrillary acidic protein, (GFA), and the S-100 protein. Both antibodies visualized starshaped astrocytes and perivascular membranes surrounding blood vessels. Semi-quantitative measurements as well as computerized image analysis showed that the total amount of GFA-like immunoreactivity was much higher in both types of grafts than in corresponding host cortex cerebri. No differences in amount of S-100-like immunoreactivity could be demonstrated. As S-100 is thought to be a more general astrocytic marker than GFA, this suggests that the difference in GFA-like immunoreactivity is due mainly to an increased amount of GFA within the individual astrocytes. It is concluded that grafts of fetal cortex cerebri pieces to the CNS of young hosts develop a profound astrocytic reaction characterized by an increased amount of GFA-like immunoreactivity.

Animals↗
PubMed1983

Trophic effects of brain areas on the developing cerebral cortex: I. Growth and histological organization of intraocular grafts.

Trophic interactions during development of brain regions were examined in rats using intraocular grafts of central nervous tissue. The increase in volume of transplanted fetal parietal cerebral cortex, as measured through the cornea, was markedly augmented by the presence of several different previously grafted CNS areas such as locus coeruleus, tectum, or cerebral cortex. DNA measurements and histological examinations suggested that this increased volume was due both to hyperplasia and hypertrophy. Previous grafts of iris, in contrast, did not significantly alter the final size of subsequently grafted cortex pieces. Contact between the two transplants was found to be critical in eliciting the trophic response. Growth-stimulated cortical grafts had a better organized cyto-architecture with larger neurons, including typical pyramidal cells, more neuropil, a lower cell density, and a more organotypic distribution of the cell bodies than non-stimulated controls. The experiments thus demonstrate a profound effect of adjacent neural tissue on development of neocortex. It is concluded that trophic interactions upon brain development can be revealed by sequential intraocular grafting.

Animals↗
PubMed1983

Trophic effects of brain areas on the developing cerebral cortex: II. Electrophysiology of intraocular grafts.

Electrophysiological correlates of locus coeruleus-induced growth stimulation in rat cortical grafts homologously transplanted to the anterior chamber of the eye were studied. Neurons in growth-stimulated grafts manifested a slow sustained spontaneous discharge similar to that found in rat cortex in situ. Local administration of glutamate markedly augmented this discharge. In contrast, neurons from nonstimulated grafts fired in high frequency bursts separated by long pauses, and this discharge was comparatively insensitive to glutamate. Poststimulus inhibition after local stimulation of the transplant surface was readily observed in the growth-stimulated grafts, but absent in all non-stimulated grafts tested. Moreover, superfusion of picrotoxin, which antagonizes GABA-mediated inhibitory pathways, reversibly converted the growth-stimulated graft discharge pattern into one characteristic of non-stimulated grafts. Taken together with the data in the preceding paper, the results demonstrate the importance of extrinsic inputs for functional development of neuronal circuits within neocortex.

Acetylcholine↗
PubMed1983

Survival and growth of neurons with enkephalin-like immunoreactivity in fetal brain areas grafted to the anterior chamber of the eye.

Areas of fetal rat brain and spinal cord known to contain enkephalin-like immunoreactive cell bodies and/or terminal fields were transplanted to the anterior chamber of the eye of adult rats. Enkephalin-like immunoreactive neurons survive and produce an enkephalin-like immunoreactive fiber network within grafts of spinal cord, ventral medulla oblongata, ventrolateral pons, tectum, locus coeruleus, substantia nigra and the areas containing columna fornicis and globus pallidus. Although single intraocular grafts of neocortex do not apparently contain enkephalin-like immunoreactive fibers, such grafts contain a variable amount of sparsely distributed enkephalin-like fibers when sequentially grafted in oculo with either locus coeruleus or spinal cord. Combinations of locus coeruleus and globus pallidus contained a rich enkephalin fiber network in the locus coeruleus part and a sparse innervation of the globus pallidus part. We conclude that enkephalin-like immunoreactive neurons in small areas of fetal rat brain can be successfully transplanted to the anterior chamber of the eye. They are able to survive and develop to maturity in complete isolation from the rest of the brain. In general, the enkephalin-like immunoreactive fiber density in the various single grafts approximated that of their brain counterparts in situ. Fiber formation can be reinitiated in mature enkephalin-like immunoreactive neurons by addition of new brain target areas. Thus, the technique permits establishment of isolated, defined enkephalin systems and pathways accessible to functional analysis.

Animals↗
PubMed1983

Pigment analysis of chloroplast pigment-protein complexes in wheat.

Pigment-protein complexes separated from wheat (Triticum aestivum L. selection ND96-25 by two gel electrophoresis techniques were analyzed by high-performance liquid chromatography for chlorophylls and carotenoids. The two techniques are compared, and pigment analyses are given for the major reaction centers and light-harvesting complexes. Reaction centers contain mostly chlorophyll a, carotene, and lutein, whereas light-harvesting complexes contain chlorophyll a, chlorophyll b, lutein, and neoxanthin. The amounts of violaxanthin are variable.

Journal Article↗
PubMed1983

Development of interscapular brown adipose tissue in the hamster. II - Differentiation of transplants in the anterior chamber of the eye: role of the sympathetic innervation.

The relationship between brown adipose tissue (BAT) and its sympathetic innervation during development was investigated by transplantation of undifferentiated (white fat-like) hamster BAT into the anterior eye chamber of adult hamsters. Such transplants are known to be revascularized and reinnervated by the vessels and the nerves of the host iris. The morphology of the BAT transplants was analysed during the post-operative weeks by light and electron microscopy, and the ingrowth of sympathetic nerve fibres from the iris was followed by radioautography. BAT appeared to differentiate in oculo, i.e. presented increasing amounts of adipocytes with multilocular fat deposits and abundant, well-developed mitochondria, but only after a delay of approx. 10 days, and remained much fatter than in situ. The establishment of the sympathetic innervation was not synchronous with the revascularization process. It occurred simultaneously with the morphological differentiation of the BAT transplants, and the nerve fibre density remained low. In the absence of sympathetic innervation, i.e. when the host irides were sympathectomized prior to transplantation, BAT still differentiated, but the process was further delayed and the proportion of differentiated brown adipocytes after 20 days in oculo was clearly lower than in control transplants. It is concluded that the sympathetic innervation in BAT is involved in the regulation of differentiating activity in the tissue, but is not obligatory for differentiation to occur.

Adipose Tissue, Brown↗
PubMed1983

Modulatory interactions between enkephalin and catecholamines: anatomical and physiological substrates.

The anatomical and electrophysiological basis of enkephalin-catecholamine interactions was studied in the central nervous system of the Sprague-Dawley rat. Sections of fetal rat brain were treated alternatively with antibodies raised against enkephalin or tyrosine hydroxylase (EC 1.14.16.2). Enkephalinergic fibers were found to innervate almost all brain areas known to contain catecholamine cell bodies or terminal fields. The possible electrophysiological correlates of such an overlap in enkephalin and catecholamine terminal fields was investigated in frontal neocortex. Parenteral administration of antipsychotic agents known to block catecholamine receptors, such as spiroperidol, alpha-flupenthixol, and (+)-butaclamol, reversibly antagonized enkephalin-induced depressions of neuronal activity. The biochemically inactive isomers of these antipsychotics, beta-flupenthixol and (-)-butaclamol, manifested no such activity. Unilateral lesions of the catecholaminergic projections to frontal cortex produced by interstitial injection of 6-hydroxydopamine resulted in an ipsilateral decrease in enkephalin efficacy and in an elimination of the antagonisms of enkephalin depressions by antipsychotic agents. It is hypothesized that catecholamines may act as modulators to augment responsiveness to peptides such as enkephalins.

Animals↗