Life Sciences Commons^™

Rapid Actions Of 1,25-Dihydroxyvitamin D3 On Phosphate Uptake In Isolated Chick Intestinal Cells, Bin Zhao

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

1,25-dihydroxyvitamin D₃ [1,25(OH)₂D₃] has been shown to promote phosphate transport rapidly in the perfused duodenal loop, relative to controls, reaching treated/av basal at T = 40 min = 1.82 ± 0.42 and 1.11 ± 0.21, respectively.

By using isolated chick enterocytes, studies were undertaken to determine whether 1,25(OH)₂D₃ has a direct effect on isolated intestinal cells that is manifested by either enhanced uptake or extrusion of phosphate.

In time course studies, with 4- to 8-wk-old chicks, ³²P uptake in enterocytes at 10 min after addition of test substance was 0%, 130%, …

Direct And Indirect Excitation Of Laterodorsal Tegmental Neurons By Hypocretin/Orexin Peptides: Implications For Wakefulness And Narcolepsy, Sophie Burlet, Christopher Tyler, Christopher S. Leonard

NYMC Faculty Publications

Compelling evidence links the recently discovered hypothalamic peptides Hypocretin/Orexin (Hcrt/Orx) to rapid eye movement sleep (REM) control and the sleep disorder narcolepsy, yet how they influence sleep-related systems is not well understood. We investigated the action of Hcrt/Orx on mesopontine cholinergic (MPCh) neurons of the laterodorsal tegmental nucleus (LDT), a target group whose function is altered in canine narcolepsy and appears pivotal for normal REM and wakefulness. Extracellular recordings from mouse brainstem slices revealed that Hcrt/Orx evoked prolonged firing of LDT neurons. Whole-cell recordings revealed that Hcrt/Orx had actions on both presynaptic neurons and at postsynaptic sites. Hcrt/Orx produced an …

Mechanisms Of Calcium Wave Initiation And Propagation In Astrocytes, Charles Emmet Stout

Loma Linda University Electronic Theses, Dissertations & Projects

Glial cells display propagated waves of cytoplasmic calcium (Ca²⁺) mobilization that spread outward from an initiating cell to involve hundreds to thousands of surrounding cells. This intercellular communication system is thought to initiate and coordinate Ca²⁺ dependent processes associated with vascular control, gut motility, uterine contraction, and synaptic plasticity. Not surprisingly, aberrant Ca signaling is thought to play a featured role in the pathophysiologies associated with dysfunction of these processes. This suggests that elucidation of the mechanism of Ca²⁺ waves will lead to rational therapeutic modalities for a variety of clinically significant entities.

Early studies revealed …

Molecular Basis Of An Inherited Epilepsy, Christoph Lossin, T. H. Rhodes, C. Vanoye, D. Wang, Alfred L. George

Christoph Lossin, Ph.D.

Mutations in SCN1A, the gene encoding the brain voltage-gated sodium channel alpha1 subunit (NaV1.1), are associated with at least two forms of epilepsy, generalized epilepsy with febrile seizures plus (GEFS+) and severe myoclonic epilepsy of infancy (SMEI). We examined the functional properties of four GEFS+ alleles and one SMEI allele using whole-cell patch-clamp analysis of heterologously expressed recombinant human SCN1A. One previously reported GEFS+ mutation (I1656M) and an additional novel allele (R1657C), both affecting residues in a voltage-sensing S4 segment, exhibited a similar depolarizing shift in the voltage dependence of activation. Additionally, R1657C showed a 50% reduction in current density …