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Biomedical subjects

M Hartley

Publications and source records attributed to M Hartley.

At least 19 recordsLinked to original sources
PubMed1992

Epidural pethidine and bupivacaine in labour.

A double-blind randomised study was performed to assess the value of the addition of pethidine 50 mg to the initial dose of bupivacaine given for epidural analgesia in labour. Forty-nine patients received either 1 ml of saline (n = 24), or 50 mg of pethidine (n = 25), added to 9 ml of 0.25% bupivacaine as an initial injection for intrapartum epidural analgesia. There was a significant increase in the mean duration of analgesia in the pethidine group. However, pethidine did not increase the speed of onset of analgesia, or improve the quality of analgesia.

Adult↗
PubMed1991

Ca2+ permeability of KA-AMPA--gated glutamate receptor channels depends on subunit composition.

NMDA (N-methyl-D-aspartate) receptors and non-NMDA receptors represent the two major classes of ion channel-linked glutamate receptors. Unlike the NMDA receptor channels, non-NMDA receptor channels have usually been thought to conduct monovalent cations only. Non-NMDA receptor ion channels that can be gated by kainic acid (KA) and alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) are formed by the glutamate receptor subunits GluR1, GluR2, and GluR3. These subunits were expressed in various combinations in Xenopus oocytes so that their permeability to divalent cations could be studied. At physiological resting potentials, KA and AMPA elicited inward calcium currents in oocytes expressing GluR1, GluR3, and GluR1 plus GluR3. In contrast, oocytes expressing GluR1 plus GluR2 or GluR3 plus GluR2 showed no such permeability. Thus, in neurons expressing certain KA-AMPA receptor subunits, glutamate may trigger calcium-dependent intracellular events by activating non-NMDA receptors.

Animals↗
PubMed1991

The nicotinic receptor genes.

The causative factor(s) of Alzheimer's disease (AD) are presently unknown. However, it has been shown that the number as well as the fraction of high- to low-affinity nicotine binding sites is altered in patients suffering from this disease. This finding, along with the identification of seven genes which code for nicotinic receptors expressed in the mammalian brain, has led to the idea that one nicotinic receptor subtype may be specifically altered in AD. The present article reviews how, through a molecular genetic approach, a family of genes coding for nicotinic acetylcholine receptor subtypes was uncovered. Also discussed is the use of in situ hybridization to determine the distribution of expression of the mRNA encoding for each receptor subtype and the patch clamp technique to characterize their biophysical properties. Determination of the promoters of these genes, as well as the properties of the expressed receptor subtypes, may make it possible to design new specific nicotinic receptor subtype drugs that will treat not only the symptoms of AD but the progression of the disease process as well.

Alzheimer Disease↗
PubMed1990

Molecular cloning and functional expression of glutamate receptor subunit genes.

Three closely related genes, GluR1, GluR2, and GluR3, encode receptor subunits for the excitatory neurotransmitter glutamate. The proteins encoded by the individual genes form homomeric ion channels in Xenopus oocytes that are sensitive to glutamatergic agonists such as kainate and quisqualate but not to N-methyl-D-aspartate, indicating that binding sites for kainate and quisqualate exist on single receptor polypeptides. In addition, kainate-evoked conductances are potentiated in oocytes expressing two or more of the cloned receptor subunits. Electrophysiological responses obtained with certain subunit combinations show agonist profiles and current-voltage relations that are similar to those obtained in vivo. Finally, in situ hybridization histochemistry reveals that these genes are transcribed in shared neuroanatomical loci. Thus, as with gamma-aminobutyric acid, glycine, and nicotinic acetylcholine receptors, native kainate-quisqualate-sensitive glutamate receptors form a family of heteromeric proteins.

Amino Acid Sequence↗
PubMed1988

A modular spinal rod linkage system to provide rotational stability.

The effect of cross linkage on the in vitro stability of paired Harrington distraction rods was studied in an unstable fracture model using calf spine segments. Cross linkage used in conjunction with sublaminar wires significantly improved torsional stability, improved lateral bending stability, and had no adverse affect on stability for axial, forward flexion, or extension loading compared to rods alone, rods with bridges, and wired rods.

Equipment Design↗