Detection of A2058G and A2059G on the 23S rRNA Gene by Multiplex Nested PCR to Identify Treponema pallidum Resistance to Azithromycin in Indonesia.

Azithromycin is an antibiotic used to treat syphilis, especially in the context of penicillin allergy. Although resistance to azithromycin has been widely reported to be associated with one- and/or two-point mutations on the 23S rRNA gene, it has yet to be described in Indonesia. Specimens were collected from 220 patients diagnosed with secondary syphilis. A multiplex nested polymerase chain reaction (PCR) testing system using the 23S rRNA target gene of Treponema pallidum was designed using three primer pairs. The first step involved the use of PCR primer pairs to detect T. pallidum. In the second step, two PCR primer pairs were constructed to identify azithromycin-resistant T. pallidum based on A2058G and A2059G point mutations. T. pallidum detected in samples from Jakarta or Bandung were not resistant to azithromycin. However, azithromycin-resistant T. pallidum were found in samples from Makassar, Medan, and Bali. Specimens from heterosexual males and patients with HIV accounted for the majority of azithromycin resistance noted in the study. This study demonstrated that the azithromycin-resistant T. pallidum detected in Indonesia appear to be a novel variant of resistance, containing both the A2058G and A2059G mutations found in Medan and Makassar.

The CGP7930 analogue 2,6-di-tert-butyl-4-(3-hydroxy-2-spiropentylpropyl)-phenol (BSPP) potentiates baclofen action at GABA(B) autoreceptors.

The pharmacological actions of 2,6-di-tert-butyl-4-(3-hydroxy-2-spiropentylpropyl)-phenol (BSPP), a putative presynaptic GABA(B) receptor modulator, were examined in electrically stimulated rat neocortical brain slices preloaded with [3H]-GABA or [3H]-glutamic acid. At 10 mmol/L, BSPP inhibited the release of [3H]-GABA in the presence of baclofen, but not that of [3H]-glutamic acid. This effect was sensitive to the GABA(B) receptor antagonist (+)-(S)-5,5-dimethylmorpholinyl-2-acetic acid (Sch 50911). Alone, BSPP had no effect on the release of [3H]-GABA or [3H]-glutamic acid. It is concluded that BSPP selectively potentiates the action of baclofen at GABA(B) autoreceptors, but not heteroreceptors and may be a useful ligand to discriminate between presynaptic GABA(B) receptor subtypes.

3-Chloro,4-methoxyfendiline is a potent GABA(B) receptor potentiator in rat neocortical slices.

Using grease-gap recording from rat neocortical slices, the GABA(B) receptor agonist baclofen elicited reversible and concentration-dependent hyperpolarizing responses (EC50=18+/-2.3 microM). The hyperpolarizations were antagonised by the GABA(B) receptor antagonist Sch 50911 [(+)-(S)-5,5-dimethylmorpholinyl-2-acetic acid). (+)-N-1-(3-chloro-4-methoxyphenyl)ethyl-3,3-diphenylpropylamine (3-chloro,4-methoxyfendiline; 3-Cl,4-MeO-fendiline) reversibly potentiated baclofen-induced hyperpolarizing responses, which were reduced by Sch 50911, producing leftward shifts of the baclofen concentration-response curves, with a marked increase in the maximal hyperpolarization (EC50=2+/-0.5 microM). In slices preincubated with either [3H]GABA or [3H]glutamic acid, 3-Cl,4-MeO-fendiline (1 microM) potentiated the inhibitory effect of baclofen (2 microM) on the electrically evoked release of [3H]GABA and had a similar effect on the release of [3H]glutamic acid at a concentration of 0.5 microM, without affecting the basal release. These effects were blocked by Sch 50911 (10 microM). Our findings suggest that 3-Cl,4-MeO-fendiline is a potent potentiator of pre- and postsynaptic GABA(B) receptor-mediated functions.

Arylalkylamines are a novel class of positive allosteric modulators at GABA(B) receptors in rat neocortex.

Using grease-gap recording from rat neocortical slices, the gamma-aminobutyric acid(B) (GABA(B)) receptor agonists baclofen (3-100 microM) and SKF 97541 (3-aminopropyl-methylphosphinic acid) (1-30 microM) elicited reversible and concentration-dependent hyperpolarizing responses, with EC(50) values of 10 and 3 microM, respectively. The hyperpolarizations were antagonised by the GABA(B) receptor antagonist Sch 50911 ((+)-(S)-5,5-dimethylmorpholinyl-2-acetic acid) (1, 5 and 10 microM). Fendiline (N-[3,3-diphenylpropyl)-alpha-methylbenzylamine) (5-50 microM) and its congeners, prenylamine (N-[3,3-diphenylpropyl)-alpha-methylphenylethylamine) (10-100 microM) and F551 (N-[3,3-diphenylpropyl)-alpha-methyl-3-methoxybenzylamine) (1-30 microM) reversibly enhanced hyperpolarizing responses to the agonists; such effects were reduced by Sch 50911. These arylalkylamines produced leftward shifts of the concentration-response curves, with a marked increase in the maximal hyperpolarization obtained, compared with the agonists alone, F551 being the most potent. These findings suggest that these arylalkylamines represent a new class of positive modulators of GABA(B) receptor-mediated function.