In an attempt to investigate the apparent absolute selectivity of the synaptic vesicle L-glutamate carrier, L- and D-enantiomers of excitatory sulphur-containing amino acid (SAA) transmitter candidates (which are close structural analogues of L-glutamate) were tested for their capacity to compete for vesicular L-[3H]-glutamate uptake. All SAAs inhibited, to varying degrees (52-86%), the vesicular uptake of L-[3H]-glutamate. A similar level of inhibition was exerted by SAAs with either a shorter or equal carbon chain length to L-glutamate. Moreover, inhibition was stereospecific in favour of the D-enantiomers. These studies indicate an appreciable interaction of the SAAs with the recognition site of the vesicular L-glutamate carrier. Further investigations are required to establish the substrate potential of the SAAs.

Animals↗

PubMed1991

Stimulation of gamma-[3H]aminobutyric acid release from cultured mouse cerebral cortex neurons by sulphur-containing excitatory amino acid transmitter candidates: receptor activation mediates two distinct mechanisms of release.

In primary cultures of mouse cerebral cortex neurons, sulphur-containing excitatory amino acids (SAAs; namely, L-cysteine sulphinate, L-cysteate, L-homocysteine sulphinate, L-homocysteate, S-sulphocysteine) at concentrations ranging from 0.1 microM to 1 mM evoked a saturable release of gamma-[3H]aminobutyric acid ([3H]GABA) in the absence of any other depolarizing agent. All SAAs exhibited essentially similar potency (EC50, 100-150 microM) in releasing [3H]GABA although a variable profile of maximal stimulatory effect was observed when compared with basal release. The intracellular accumulation of the lipophilic cation, [3H]tetraphenylphosphonium, was significantly reduced in the presence of all SAAs, thus verifying a depolarization of the neuronal plasma membrane. SAA-stimulated release of [3H]GABA was shown to comprise two distinct components, calcium-dependent and calcium-independent, which occur after activation of N-methyl-D-aspartate (NMDA) and non-NMDA receptors. Thus, all SAA-evoked responses were antagonized by the selective, competitive NMDA-receptor antagonist, 3-[(+/-)-2-carboxypiperazin-4-yl]propyl-1-phosphonic acid (IC50 range, greater than 50 microM) and the non-NMDA-receptor antagonist, 6,7-dinitroquinoxalinedione (IC50 range, 5-50 microM). Removal of magnesium ions from the superfusion medium caused a significant potentiation of SAA-evoked responses without having any effect on basal levels of [3H]GABA efflux, a result consistent with an involvement of NMDA-receptor activation. Calcium-independent release (i.e., that release remaining in the presence of 1 mM cobalt ions) was a distinct component but of smaller magnitude. Using 500 microM excitatory amino acid agonist concentrations, this component of release was (1) markedly attenuated by 15 microM SKF-89976-A, a non-transportable inhibitor of the GABA carrier, and (2) abolished when choline ions replaced sodium ions in the superfusion medium or when in the presence of excitatory amino acid receptor antagonists. These observations are clearly consistent with a receptor-mediated, depolarization-induced reversal of the GABA carrier.

Amino Acids↗

PubMed1991

A quality assurance audit of Illawarra PADP Scheme home glucose meters and evaluation of their use by patients.

A total of 187 home glucose meters have been issued to Illawarra residents by the Program of Aids for Disabled Patients (PADP) Scheme operating out of Port Kembla District Hospital in a 5-year period ending 31 December 1989. These meters, representing a valuable health resource, have been loaned to patients without audit or follow up. Sixteen per cent of meters were unable to be located and 33.2% could not be located using existing PADP records. Of those meters which could be tested, 16.4% were inaccurate; the recipient's technique was inadequate for accurate results in 36.1% of instances. This survey has revealed a significant loss of health resources in addition to inadequate clinical assessment and supervision.

Adolescent↗

PubMed1990

Care is the key.

Explore the source record for details and available documents.

Appointments and Schedules↗

PubMed1990

A novel avian W chromosome DNA repeat sequence in the lesser black-backed gull (Larus fuscus).

The phenol emulsion reassociation technique was used to isolate and clone a female specific, repetitive DNA sequence from Larus fuscus. The repeat, designated P2000-17, is restricted to the W chromosome, although related sequences occur elsewhere in the genome of L. fuscus. Similar sequences were detected in the genome of six other bird species from outside the genus Laridae, but the sequence occurs less frequently and to a similar extent in both sexes. The 298 bp DNA sequence of P2000-17 was determined and found to have extensive sequence identity to the rabbit dihydropyridine (DHP) receptor calcium channel. P2000-17 is represented once within a larger 8.6 kb tandem repeat (LfW-1), which has a complex internal DNA sequence. LfW-1 is highly conserved between repeat motifs and may comprise 3% of the female genome. The possible evolutionary origin of LfW-1 is discussed in relation to the repeat types found on the W and Y chromosomes of other species.

Animals↗

PubMed1990