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H A Burgess

Publications and source records attributed to H A Burgess.

16 recordsLinked to original sources
PubMed2001

Cleavage of doublecortin-like kinase by calpain releases an active kinase fragment from a microtubule anchorage domain.

Doublecortin-like kinase (DCLK) is widely expressed in postmitotic neurons throughout the embryonic nervous system. DCLK consists of an N-terminal doublecortin domain, responsible for its localization to microtubules, and a C-terminal serine-threonine kinase domain. Here we report that DCLK is a physiological substrate for the cysteine protease calpain. Cleavage of DCLK by calpain severs the kinase domain from its microtubule anchorage domain and releases it into the cytoplasm. The isolated kinase domain retains catalytic activity and is structurally similar to CPG16, a second product of the DCLK gene expressed in the adult brain that lacks the doublecortin domain. We propose that in neurons cleavage of DCLK by calpain represents a calcium responsive mechanism to regulate localization of the DCLK kinase domain.

Animals↗
PubMed2000

Doublecortin mutations cluster in evolutionarily conserved functional domains.

Mutations in the X-linked gene doublecortin ( DCX ) result in lissencephaly in males or subcortical laminar heterotopia ('double cortex') in females. Various types of mutation were identified and the sequence differences included nonsense, splice site and missense mutations throughout the gene. Recently, we and others have demonstrated that DCX interacts and stabilizes microtubules. Here, we performed a detailed sequence analysis of DCX and DCX-like proteins from various organisms and defined an evolutionarily conserved Doublecortin (DC) domain. The domain typically appears in the N-terminus of proteins and consists of two tandemly repeated 80 amino acid regions. In the large majority of patients, missense mutations in DCX fall within the conserved regions. We hypothesized that these repeats may be important for microtubule binding. We expressed DCX or DCLK (KIAA0369) repeats in vitro and in vivo. Our results suggest that the first repeat binds tubulin but not microtubules and enhances microtubule polymerization. To study the functional consequences of DCX mutations, we overexpressed seven of the reported mutations in COS7 cells and examined their effect on the microtubule cytoskeleton. The results demonstrate that some of the mutations disrupt microtubules. The most severe effect was observed with a tyrosine to histidine mutation at amino acid 125 (Y125H). Produced as a recombinant protein, this mutation disrupts microtubules in vitro at high molar concentration. The positions of the different mutations are discussed according to the evolutionarily defined DC-repeat motif. The results from this study emphasize the importance of DCX-microtubule interaction during normal and abnormal brain development.

Amino Acid Sequence↗
PubMed2000

Doublecortin-like kinase is associated with microtubules in neuronal growth cones.

Doublecortin-like kinase (DCLK) shares sequence similarity to Doublecortin (DCX) in its N-terminal region. It contains the evolutionary conserved DC repeat motif as well a C-terminal kinase domain. Ectopic expression of DCLK in COS cells results in colocalization with microtubules, and phosphorylated DCLK copurifies with microtubules during assembly from embryonic brain extract. During brain development DCLK is expressed mainly in postmigratory neurons in a similar pattern to DCX. We demonstrate that DCLK is a microtubule-associated active protein kinase expressed in growth cones of postmitotic neurons.

Animals↗
PubMed1999

KIAA0369, doublecortin-like kinase, is expressed during brain development.

During embryonic development, the cerebral cortex attains its characteristic adult laminated structure. The finding that X-linked lissencephaly patients harbor mutations in the doublecortin gene implicated this gene product in the process of corticogenesis. An autosomal human gene, KIAA0369, with a high level of similarity to doublecortin, has been cloned from human adult brain. This gene product contains a kinase domain in addition to a doublecortin-like domain. In order to evaluate whether this doublecortin-like kinase also plays a role during brain development, we cloned and studied the expression pattern of the mouse homolog. Three cDNA products of this gene were cloned: one, doublecortin-like kinase, the second containing only the doublecortin-like region, and the third containing only the kinase domain, a homolog of the previously cloned rat CPG16 gene. We studied doublecortin-like kinase expression in mouse using Northern blot analysis, in situ hybridization, and Western blot analysis, and conclude that doublecortin-like kinase is expressed in multiple regions of embryonic brain including the developing cerebral cortex.

Amino Acid Sequence↗
PubMed1999

Analysis of lissencephaly-causing LIS1 mutations.

Mutations in the LIS1 gene may result in severe abnormalities of brain cortical layering known as lissencephaly. Most lissencephaly-causing LIS1 mutations are deletions that encompass the entire gene, therefore the mechanism of the disease is regarded as haploinsufficiency. So far, 13 different intragenic mutations have been reported: one point mutation, H149R; deletion of exon 9, which results in deleted acids Delta301-334; deletion of exon 4, which results in deleted amino acids Delta40-64; 10 mutations resulting in truncated proteins and one predicted to result in extra amino acids. We studied the consequences of the point mutation, deletion mutation and one of the reported truncations. In order to study LIS1 structure function, we introduced an additional point mutation and other truncations in different regions of the protein. The consequences of these mutations to protein folding were studied by gel filtration, sucrose density gradient centrifugation and measuring resistance to trypsin cleavage. On the basis of our results, we suggest that all truncation mutations and lissencephaly-causing point mutations or internal deletion result in a reduction in the amount of correctly folded LIS1 protein.

1-Alkyl-2-acetylglycerophosphocholine Esterase↗
PubMed1991

Parameters of normotensive women and women with pregnancy induced hypertension (PIH) in Lusaka.

This paper reports results of a survey of mean arterial pressures (MAP) in a population of 125 control patients and 30 cases who developed pregnancy induced hypertension. The investigation was carried out to see if MAP would be a useful addition to methods used to screen for PIH. More of the cases had elevated MAP than did the controls, suggesting that use of this easily obtainable information may be helpful in identifying patients at risk for pregnancy--induced hypertension. Addition baseline information on the 155 patients and their pregnancy outcome is also presented.

Adolescent↗
PubMed1987

Into the Sudan.

Explore the source record for details and available documents.

Child↗
PubMed1985

The relative bioavailability of paracetamol after rectal administration of suppositories containing a mixture of paracetamol, codeine phosphate and buclizine hydrochloride in healthy volunteers.

'New' and 'old' suppositories (6 months and 30 months since manufacture) containing 800 mg paracetamol, 16 mg codeine phosphate and 12.5 mg buclizine hydrochloride in an identical base were administered to 10 normal volunteers at an interval of 2 weeks. Blood samples were taken at intervals up to 300 minutes after administration for estimation of paracetamol plasma concentrations using high pressure liquid chromatography. Mean peak concentrations were obtained of 4.75 +/- 0.74 mg/ml at 1.75 hours with the new suppositories and of 4.6 +/- 0.67 mg/ml at 2.0 hours with the old suppositories. The difference was not significant. Mean elimination half-life was 4.4 +/- 0.42 hours and 3.73 +/- 0.28 hours, respectively. Again, the difference was not significant, indicating that the absorption characteristics for the suppositories did not appear to deteriorate with ageing for 24 months. Bioavailability data for paracetamol derived from the results were similar to those reported by other workers who studied suppositories containing paracetamol as the only active ingredient. This indicates that the inclusion of codeine phosphate and buclizine hydrochloride in the suppository formulation investigated in the present study did not affect adversely the absorption of paracetamol.

Acetaminophen↗