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Biomedical subjects

E Jorgensen

Publications and source records attributed to E Jorgensen.

17 recordsLinked to original sources
PubMed2004

Induction of H2AX phosphorylation in pulmonary cells by tobacco smoke: a new assay for carcinogens.

DNA double strand breaks (DSBs) are potentially carcinogenic lesions. The induction of DSBs triggers phosphorylation of histone H2AX. Phosphorylated H2AX, denoted p-H2AX, may be detected immunocytochemically and the intensity of p-H2AX immunofluorescence (IF) reveals the frequency of DSBs. Using this assay we tested whether the exposure of A549 human pulmonary adenocarcinoma cells to tobacco smoke, and normal human bronchial epithelial cells (NHBE) to tobacco smoke condensate, induces DSBs. Cellular p-H2AX IF and DAPI fluorescence of individual cells were measured by laser scanning cytometry (LSC). Exposure of A549 cells to tobacco smoke and NHBE cells to smoke condensate led to H2AX phosphorylation in both a time and dose dependent manner. The maximal rate of H2AX phosphorylation was seen during the initial 4h of cell treatment. At high doses (50 microg/ml of smoke condensate), H2AX phosphorylation continued to increase for up to 24h. No differences in the level of H2AX phosphorylation were apparent between cells in G(1) vs S vs G(2)/M phase of the cell cycle in response to treatment with smoke condensate. The data provide strong evidence that exposure of A549 cells to tobacco smoke or NHBE cells to smoke condensate rapidly induces DSBs in these cells. The present assay to detect and measure DSBs induced by tobacco products complements other mutagenicity assays and may be applied to test potential carcinogens in other products.

Adenocarcinoma↗
PubMed1999

The Caenorhabditis elegans gene unc-25 encodes glutamic acid decarboxylase and is required for synaptic transmission but not synaptic development.

The neurotransmitter GABA has been proposed to play a role during nervous system development. We show that the Caenorhabditis elegans gene unc-25 encodes glutamic acid decarboxylase (GAD), the GABA biosynthetic enzyme. unc-25 is expressed specifically in GABAergic neurons. Null mutations in unc-25 eliminate the UNC-25 protein or alter amino acids conserved in all known GADs, result in a complete lack of GABA, and cause defects in all GABA-mediated behaviors. In unc-25 mutants the GABAergic neurons have normal axonal trajectories and synaptic connectivity, and the size and shape of synaptic vesicles are normal. The number of synaptic vesicles at GABAergic neuromuscular junctions is slightly increased. Cholinergic ventral nerve cord neurons, which innervate the same muscles as GABAergic ventral cord neurons, have normal morphology, connectivity, and synaptic vesicles. We conclude that GAD activity and GABA are not necessary for the development or maintenance of neuromuscular junctions in C. elegans.

Amino Acid Sequence↗
PubMed1993

Genes required for GABA function in Caenorhabditis elegans.

gamma-Aminobutyric acid (GABA) neurotransmission is widespread in vertebrate and invertebrate nervous systems. Here we use a genetic approach to identify molecules specific to GABA function. On the basis of the known in vivo roles of GABAergic neurons in controlling behaviour of the nematode Caenorhabditis elegans, we identified mutants defective in GABA-mediated behaviours. Five genes are necessary either for GABAergic neuronal differentiation or for pre- or postsynaptic GABAergic function. The gene unc-30 is required for the differentiation of a specific type of GABAergic neuron, the type-D inhibitory motor neuron. The gene unc-25 is necessary for GABA expression and probably encodes the GABA biosynthetic enzyme glutamic acid decarboxylase. The genes unc-46 and unc-47 seem to be required for normal GABA release. Finally, the gene unc-49 is apparently necessary postsynaptically for the inhibitory effect of GABA on the body muscles and might encode a protein needed for the function of a GABAA-like receptor. Some of these genes are likely to encode previously unidentified proteins required for GABA function.

Animals↗
PubMed1993

The GABAergic nervous system of Caenorhabditis elegans.

gamma-Aminobutyric acid (GABA) is the most abundant inhibitory neurotransmitter in vertebrates and invertebrates. GABA receptors are the target of anxiolytic, antiepileptic and antispasmodic drugs, as well as of commonly used insecticides. How does a specific neurotransmitter such as GABA control animal behaviour? To answer this question, we identified all neurons that react with antisera raised against the neurotransmitter GABA in the nervous system of the nematode Caenorhabditis elegans. We determined the in vivo functions of 25 of the 26 GABAergic neurons by killing these cells with a laser microbeam in living animals and by characterizing a mutant defective in GABA expression. On the basis of the ultrastructurally defined connectivity of the C. elegans nervous system, we deduced how these GABAergic neurons act to control the body and enteric muscles necessary for different behaviours. Our findings provide evidence that GABA functions as an excitatory as well as an inhibitory neurotransmitter.

Animals↗
PubMed1990

Discrimination between bacteriophage T3 and T7 promoters by the T3 and T7 RNA polymerases depends primarily upon a three base-pair region located 10 to 12 base-pairs upstream from the start site.

The bacteriophage T3 and T7 RNA polymerases are closely related, yet are highly specific for their own promoter sequences. To understand the basis of this specificity, T7 promoter variant that contain substitutions of T3-specific base-pairs at one or more positions within the T7 promoter consensus sequence were synthesized and cloned. Template competition assays between variant and consensus promoters demonstrate that the primary determinants of promoter specificity are located in the region from -10 to -12, and that the base-pair at -11 is of particular importance. Changing this base-pair from G.C, which is normally present in T7 promoters, to C.G, which is found at this position in T3 promoters, prevented utilization by the T7 RNA polymerase and simultaneously enabled transcription from the variant T7 promoter by the T3 enzyme. Substitution of T7 base-pairs with T3 base-pairs at other positions where the two consensus sequences diverge affected the overall efficiency with which the variant promoter was utilized by the T7 RNA polymerase, but these changes were not sufficient to permit recognition by the T3 RNA polymerase. Switching the -11 base-pair in the T3 promoter consensus to the T7 base-pair prevented utilization by the T3 RNA polymerase, but did not allow the T3 variant promoter to be utilized by the T7 RNA polymerase. This probably reflects a greater specificity of the T7 RNA polymerase for base-pairs at other positions where the promoter sequences differ, most notably at -15. The magnitude of the effects of base substitutions in the T7 promoter on promoter strength (-11C much greater than -10C greater than -12A) correlates with the affinity of the T7 polymerase for the promoter variants, suggesting that the discrimination of the phage RNA polymerases for their promoters is mediated primarily at the level of DNA binding, rather than at the level of initiation.

Base Composition↗
PubMed1990

The status of periodontal health and oral hygiene of Miraa (catha edulis) chewers.

Two hundred and thirty one miraa chewers and 199 non miraa chewers were assessed for gingivitis, loss of attachment and oral hygiene status. The mean gingivitis score among miraa chewers was 1.6 and 1.7 among non miraa chewers (P less than 0.05). The mean facial gingivitis score among miraa chewers was 1.5 and 1.6 among non miraa chewers (P greater than 0.05). The mean distal gingivitis score among miraa chewers was 1.5 and 1.7 among non miraa chewers (P less than 0.05). The mean lingual gingivitis score among miraa chewers was lower than that of non miraa chewers (P less than 0.05). The means of loss of attachment of the teeth of miraa chewers were equal to those of non miraa chewers. Although the mean surface plaque scores of miraa chewers were generally lower than those of non miraa chewers, only the mean lingual plaque score of miraa chewers was found to be significantly lower than that of non miraa chewers (P less than 0.05). It is concluded that the oral hygiene status of miraa chewers was generally better than that of non miraa chewers and there was no evidence to show that chewing miraa is detrimental to periodontal health.

Adult↗
PubMed1987

Pantethine lipomodulation: evidence for cysteamine mediation in vitro and in vivo.

Recent human studies suggest rapid in vivo hydrolysis of the lipid-lowering drug, pantethine, to the vitamin pantothenic acid and the small aminothiol compound, cysteamine. To test whether the active agent is a hydrolysis product, we repeated three experimental models of pantethine's effect with pantothenate and cysteamine. In vitro experiments with human fetal fibroblasts showed equivalent modulation of cholesterol and methyl sterol synthesis by pantethine, cysteamine, or cystamine (the disulfide of cysteamine), but pantothenate had no effect. Similarly, in vivo experiments with 0.5% cholesterol-fed rabbits showed oral pantethine or equimolar cystamine significantly lowered plasma cholesterol, while pantothenate, cystine, and 2-hydroxyethyl disulfide did not. Lastly, diabetic male rats (40 mg/kg streptozotocin) fed 0.1% pantethine and lower plasma free fatty acids after 2 weeks than controls, an effect not seen with pantothenate and largely duplicated by cystamine. The efficacy of pantethine has previously been attributed to altered vitamin metabolism and increased coenzyme A concentration. Pantethine did increase CoA levels 45% in rat liver homogenates while equivalent amounts of cystamine or pantothenate did not. However, a causal relationship between CoA levels and pantethine's action as a hypolipemic agent has never been shown. At least in 3 independent experimental models, the lipomodulating effect of pantethine appears instead to be mediated by the hydrolysis product cysteamine.

Animals↗
PubMed1976

Locked twins. An unusual method of delivery.

This report concerns a case of locked twins encountered at the Mayo Clinic. The method of delivery is unusual, and the fact that both infants survived is also worthy of reporting.

Abnormalities, Multiple↗