The holistic back care model.
Explore the source record for details and available documents.
Back Injuries↗
Biomedical subjects
L Howe
Publications and source records attributed to L Howe.
Transcriptionally active Xenopus laevis somatic 5 S ribosomal RNA genes are packaged with hyperacetylated histone H4, whereas transcriptionally silent oocyte genes are not.
The relationship between histone acetylation and transcription of the Xenopus laevis oocyte and somatic 5 S ribosomal RNA genes was investigated. Chromatin fragments from a X. laevis kidney cell line were immunoprecipitated with an antibody specific for hyperacetylated histone H4. The DNA from the hyperacetylated chromatin was probed with both oocyte- and somatic gene-specific sequences, and the results showed that the upstream, nontranscribed region of the transcriptionally active somatic genes is packaged with acetylated histone H4. In contrast, the corresponding region of the transcriptionally silent oocyte genes is packaged with hypoacetylated histone H4 in this cells line. Further study also showed that this region of the oocyte genes was less sensitive to digestion with the enzyme, micrococcal nuclease. Together these results suggest that, as described for both RNA polymerase I and II transcribed genes, there is a correlation between histone acetylation and transcription of the RNA polymerase III transcribed 5 S ribosomal RNA genes in X. laevis.
Acetylation↗
Histone H1 binding does not inhibit transcription of nucleosomal Xenopus laevis somatic 5S rRNA templates.
It has long been proposed that selective binding of histone H1 is, in part, responsible for the differential developmental regulation of the oocyte and somatic 5S rRNA genes in Xenopus laevis. In this study we show that histone H1 binds both oocyte and somatic genes equally after reconstitution into mononucleosomes or oligonucleosome arrays. Furthermore, we show that the binding of histone H1 selectively represses only oocyte gene transcription and that an RNA polymerase III transcription complex is able to initiate transcription of nucleosomal somatic templates regardless of whether histone H1 is present. These results support a model in which the differential regulation of the 5S rRNA genes is not simply due to the prevention of histone H1 binding by transcription complexes on the somatic genes, but rather to a difference in the histone H1 interaction with the somatic and oocyte genes.
Acetylation↗
Folding of chromatin in the presence of heterogeneous histone H1 binding to nucleosomes.
We have reconstituted oligonucleosome complexes containing histone H1 starting from a synthetic DNA template, consisting of 12 tandemly arranged 208-base pair fragments of the 5 S rRNA gene, purified HeLa histone octamers, and histone H1. A ratio of histone H1 per histone octamer used in the reconstitution (0.8-0.9 mol of histone H1/mol of histone octamer) similar to that observed in vivo was used. The reconstituted chromatin complexes exhibit a salt-dependent folding, which is almost indistinguishable from that exhibited by chromatin fragments obtained from nuclease digestion of native chromatin. The folding of this reconstituted chromatin complex seems to be rather independent of the symmetrical or asymmetrical position occupied by H1 in the individual nucleosomes. Binding of histone H1 to the oligonucleosome complexes, under the stoichiometric binding conditions used, had no inhibitory effect on the transcriptional potential of these complexes.
Animals↗
The histone binding protein nucleoplasmin does not facilitate binding of transcription factor IIIA to nucleosomal Xenopus laevis 5S rRNA genes.
In an attempt to understand the mechanism by which transcription factors compete with histone octamers for cognate binding sites in chromatin, the effect of the histone binding protein nucleoplasmin on the binding of TFIIIA to nucleosomal 5S rRNA genes was tested. In this study, it was shown that, despite the previously reported nucleosome remodeling ability of nucleoplasmin, the binding of TFIIIA to nucleosomal DNA cannot be facilitated by this protein. Furthermore, it was demonstrated that nucleoplasmin cannot overcome nucleosome mediated repression of transcription of reconstituted 5S rRNA genes. In contrast to earlier work, this study used a homologous system composed of the 5S rRNA gene, nucleoplasmin, and TFIIIA from Xenopus laevis.
Animals↗
Leukocyte trafficking in experimental autoimmune uveitis in vivo.
Leukocyte trafficking from blood into tissue is a fundamental process in immune surveillance and the immune response to stimuli. Experimental autoimmune uveitis (EAU) is an animal model for posterior uveitis and is mediated by T lymphocytes and macrophages that infiltrate the posterior segment of the eye. To analyze leukocyte migration into retinal tissue during the course of EAU, labeled cells were identified in vivo by scanning laser ophthalmoscopy and in retinal flatmounts by confocal microscopy. Adhesion of blood leukocytes to retinal endothelial cells in vivo was significantly raised 48 h before the appearance of clinical disease, and this correlated with the increased expression of CD54 on retinal vessels. Mitogen-activated spleen cells and CD4+ T cells only entered into retinal tissue in animals with clinical disease and not naive recipients. The disease status of the donor animal had no effect on leukocyte trafficking. These results, which identify leukocyte-endothelial cell interactions in vivo, suggest that the activation of the retinal endothelium is a prerequisite to leukocyte adhesion and extravasation into ocular tissue during EAU.
Animals↗
Indocyanine green angiography in inflammatory eye disease.
PURPOSE: The choroid plays an integral role in the evolution of a number of inflammatory eye diseases but only limited information is provided on the choroidal vasculature by fluorescein angiography. METHODS: This study used indocyanine green (ICG) videoangiography to assess the degree of choroidal vascular involvement in inflammatory eye diseases and the results obtained were compared with fluorescein angiography. RESULTS: A total of 34 patients were examined: 6 with retinal vasculitis and 28 with chorioretinitis of various aetiologies. Areas of active involvement of the choroid were seen as areas of hypofluorescence on ICG angiography, representing areas of inflammatory infiltrate and/or choroidal hypoperfusion. No leakage of ICG occurred from large choroidal vessels at any stage in any disease. In contrast to sodium fluorescein, there was no leakage of ICG from retinal vessels in active inflammation. An inflammatory choroidal neovascular membrane leaked fluorescein and fluoresced late with ICG. CONCLUSION: ICG videoangiography provides useful information on the degree of choroidal involvement in inflammatory eye disease and is a valuable adjunct to fluorescein angiography.
Adult↗
Nucleosome translational position, not histone acetylation, determines TFIIIA binding to nucleosomal Xenopus laevis 5S rRNA genes.
We sought to study the binding constraints placed on the nine-zinc-finger protein transcription factor IIIA (TFIIIA) by a histone octamer. To this end, five overlapping fragments of the Xenopus laevis oocyte and somatic 5S rRNA genes were reconstituted into nucleosomes, and it was subsequently shown that nucleosome translational positioning is a major determinant of the binding of TFIIIA to the 5S rRNA genes. Furthermore, it was found that histone acetylation cannot override the TFIIIA binding constraints imposed by unfavorable translational positions.
Acetylation↗
CSF, plasma viral load and HIV associated dementia.
Plasma viral burden has proven valuable in predicting the future course of systemic HIV related disease and the response to treatment. It is not known whether plasma or cerebrospinal fluid (CSF) viral burden can be used to predict onset of or response to treatment of nervous system disease. We propose a model of viral load mediated neurotoxicity underlying peripheral and central HIV associated neurological disease. The objective of this preliminary study was to assess the relationship of HIV associated neurological disease to quantitative viral load in plasma and CSF. 47 subjects (HIV- = 10, HIV+ = 37) participated in the study. Plasma and CSF samples were collected within a 3 h window. RT-PCR (Roche Amplicor Monitor) was utilized to assess HIV-1 RNA viral load in both plasma and cell free (centrifuged) CSF. Subjects underwent concurrent comprehensive neurological and neuropsychological evaluations. In general, systemic viral load, as measured in plasma, was greater than that found in cell free CSF. Cell free CSF HIV RNA viral load was significantly correlated with neurological dysfunction, whereas plasma viral load was not. The sole subject with an elevated CSF viral load (> 5 Log 10), had HIV associated dementia (HAD) on clinical examination.
AIDS Dementia Complex↗
The effect of biological substrates on the ultrafast excited-state dynamics of zinc phthalocyanine tetrasulfonate in solution.
Zinc phthalocyanine tetrasulfonate (ZnPcS4), a potential photosensitizer for photodynamic therapy (PDT), has been studied using femtosecond laser spectroscopy. The excited-state dynamics in water have been found to be fast (< 80 ps) and dominated by intermolecular aggregation. Since the proposed mechanism for PDT is energy transfer from the triplet excited state of the photosensitizer to triplet O2 creating singlet O2, the short lifetime is expected to be unfavorable for producing singlet O2. This leads to the suggestion that the presence of biological substrates may have an effect on the excited-state dynamics. To test this hypothesis, the lifetimes of the excited states of ZnPcS4 have been directly measured in the presence of a model membrane, n-hexadecyltrimethylammonium bromide (CTAB). The excited-state dynamics of ZnPcS4 in buffer solutions and with human serum albumin (HSA) have also been measured. The presence of HSA and CTAB increases the excited-state lifetime significantly relative to that observed in water. The longer lifetime of ZnPcS4 in CTAB (> 1 ns) indicates that the micellar surface favors monomer formation. By increasing the excited-state lifetime, the surface substantially increases the photosensitizing potential of ZnPcS4.
Blood Proteins↗
Dental twinning.
Dental twinning anomalies influence tooth alignment and interdigitation, arch symmetry, appearance, and associated periodontal tissues. This case report presents a patient with twinning defects involving the maxillary central incisors. The aetiology of dental twinning using traditional nomenclature is also reviewed.
Adolescent↗
Uveitis and systemic lupus erythematosus.
Explore the source record for details and available documents.
Humans↗
The use of a caries detector dye in cavity preparation.
The aim of this study was to compare the conventional visual and tactile method of detecting carious dentine during cavity preparation using a mirror, probe and excavator with a visual method enhanced by a dye. The dye, 1% acid red in propylene glycol, was used on 100 cavities prepared by dental students and passed as clinically satisfactory by their teachers. Results showed dye stain at the enamel-dentine junction in 57 cavities (57%) which had been assessed as caries-free in this area using conventional visual and tactile means. Subsequent laboratory work on extracted carious teeth confirmed histologically that the dye stains demineralised dentine. If clinicians consider it important to render the enamel-dentine junction caries-free, it might be prudent to use the dye as an aid to diagnosis in this area.
Coloring Agents↗
Stability of amylase in serum from patients with pancreatitis.
Explore the source record for details and available documents.
Amylases↗
A Plea for the Establishment of Schools of Ophthalmology.
Explore the source record for details and available documents.
Journal Article↗
Concerning a Law to Lessen Hereditary Blindness.
Explore the source record for details and available documents.
Journal Article↗
Variations in the Primary Insertions of the Ocular Muscles.
Explore the source record for details and available documents.
Journal Article↗