Relative frequency of congenital muscular dystrophy subtypes: analysis of the UK diagnostic service 2001-2008.

The Dubowitz Neuromuscular Centre is the UK National Commissioning Group referral centre for congenital muscular dystrophy (CMD). This retrospective review reports the diagnostic outcome of 214 UK patients referred to the centre for assessment of 'possible CMD' between 2001 and 2008 with a view to commenting on the variety of disorders seen and the relative frequency of CMD subtypes in this patient population. A genetic diagnosis was reached in 53 of 116 patients fulfilling a strict criteria for the diagnosis of CMD. Within this group the most common diagnoses were collagen VI related disorders (19%), dystroglycanopathy (12%) and merosin deficient congenital muscular dystrophy (10%). Among the patients referred as 'possible CMD' that did not meet our inclusion criteria, congenital myopathies and congenital myasthenic syndromes were the most common diagnoses. In this large study on CMD the diagnostic outcomes compared favourably with other CMD population studies, indicating the importance of an integrated clinical and pathological assessment of this group of patients.

Simultaneous measurement of zolmitriptan and its major metabolites N-desmethylzolmitriptan and zolmitriptan N-oxide in human plasma by high-performance liquid chromatography with coulometric detection.

Zolmitriptan, N-desmethylzolmitriptan, zolmitriptan N-oxide and an internal standard (an analogue of zolmitriptan) were extracted from plasma by a solid-phase extraction (SPE). Chromatography was performed using isocratic reversed-phase high-performance liquid chromatography (HPLC) with coulometric end-point detection. The standard curves were linear over the range 2-20 ng/ml for zolmitriptan and its metabolites in plasma. The mean inter- and intra-assay coefficients of variation over the range of the standard curves were less than 11%. The absolute recovery averaged 87, 58 and 77% for zolmitriptan. N-desmethylzolmitriptan and zolmitriptan N-oxide, respectively. The assay sensitivity was 0.5 ng for each analyte.

Investigation of the presynaptic effects of quinine and quinidine on the release and uptake of monoamines in rat brain tissue.

Quinine and quinidine are reported to potentiate the behavioural effects of serotonergic agents and monoamine uptake inhibitors. We have therefore investigated the presynaptic actions of quinine and quinidine on monoamine uptake and release in rat brain tissue in vitro. Quinidine evoked the release of [3H]5-HT, [3H]noradrenaline and [3H]dopamine from pre-loaded rat brain slices in a concentration dependent manner with EC50 values of 175, 486 and 150 microM, respectively. Quinine induced [3H]monoamine release with similar potencies. Both quinine and quinidine also inhibited the active uptake of [3H]5-HT, [3H]noradrenaline and [3H]dopamine into rat brain synaptosomes with IC50 values in the range 0.13-12.4 microM. The potency of each drug to inhibit [3H]5-HT uptake was significantly higher than that for [3H]noradrenaline or [3H]dopamine. The relative potency of quinidine compared to quinine was more marked in the case of [3H]5-HT (58-fold) than for [3H]noradrenaline (3-fold) or [3H]dopamine (4-fold). The inhibition of [3H]5-HT uptake by quinine and quinidine was competitive in nature and corresponded with the potencies of these drugs to inhibit [3H]paroxetine binding. No correlation was observed between the potencies of quinine and quinidine to induce the release of [3H]monoamines and to inhibit their uptake, suggesting that these effects are mediated by two distinct mechanisms. We conclude that the presynaptic actions of quinine and quinidine on monoamine uptake and release may be implicated in their potentiation of the effects of serotonergic agents and uptake blockers.

Simultaneous measurement of venlafaxine and its major metabolite, oxydesmethylvenlafaxine, in human plasma by high-performance liquid chromatography with coulometric detection and utilisation of solid-phase extraction.

Venlafaxine, oxydesmethylvenlafaxine and an internal standard (paroxetine) were extracted from plasma by a solid-phase extraction technique. Chromatography was performed using isocratic reversed-phase high-performance liquid chromatography (HPLC) with coulometric endpoint detection. The standard curves were linear over the range 0-200 ng/ml for both venlafaxine and oxydesmethylvenlafaxine in plasma. The mean inter- and intra-assay coefficients of variation over the range of the standard curves were less than 10%. The absolute recovery averaged 74% for venlafaxine and 67% for oxydesmethylvenlafaxine. The sensitivity was 0.5 ng for both the analytes. Plasma profiles of the analytes following oral administration of venlafaxine, are presented.

Effect of venlafaxine on pineal melatonin and noradrenaline in the male rat.

Studies in vitro indicate that the antidepressant drug, venlafaxine (VEN), inhibits the reuptake of both serotonin (5-hydroxytryptamine, 5-HT) and noradrenaline (NA) but has little activity on other neurotransmitter receptors. There are, however, few studies on the effects of VEN on monoamine neurotransmission in vivo. In the present study we examined the effect of VEN treatment on the melatonin content of the rat pineal gland because the synthesis of melatonin is regulated by the release of NA onto pinealocyte beta-adrenoceptors. Acute treatment with higher doses (15 mg/kg) of VEN significantly increased pineal melatonin and NA but this effect was attenuated by subchronic treatment. These data are consistent with in vitro data suggesting that VEN increases NA neurotransmission at higher doses and that repeated treatment can desensitize pinealocyte beta-adrenoceptors.

Determination of sumatriptan succinate in human plasma by high-performance liquid chromatography with coulometric detection and utilization of solid-phase extraction.

Sumatriptan succinate (the analyte) and naloxone (the internal standard) were extracted from plasma with a solid-phase extraction technique. Chromatography and detection were performed by isocratic reversed-phase high-performance liquid chromatography with coulometric end-point detection. The standard curve was linear over the range 0-100 ng/ml of sumatriptan succinate in plasma. The reproducibility (as defined by the coefficient of variation, C.V.) over the range of the standard curve was 4.9-7.3%. The recovery averaged 83%. The sensitivity was 0.25 ng of sumatriptan on column (allowing a concentration of 0.5 ng/ml to be determined from a 1-ml plasma sample volume). Plasma profiles of the analyte following subcutaneous (s.c.) administration in eight normal male volunteers, are presented.

Central adrenergic activity in the mediobasal hypothalamus is temporally related to surge outputs of gonadotrophins in oestrogen-stimulated infant female rats.

In the mediobasal hypothalamus (MBH) of pro-oestrous rats or acutely ovariectomized oestrogen-treated adults a marked but short-lived increase in adrenergic activity occurs at 16.00 h, 2 h before the oestrogen-dependent surge of gonadotrophins at 18.00 h. In this study oestrogen-stimulated (noon on day 1) 22-day-old female rats were used which are known to produce surge levels of prolactin at 18.00 h on day 2 and surges of both prolactin and LH at 18.00 h on day 3; although similar treatment of 18-day-old animals or oil-treated 22-day-old rats failed to produce these effects. Radioenzymatic assays of adrenaline concentrations and of the activity of its synthesizing enzyme (phenylethanolamine-N-methyl transferase; PNMT, EC 2.1.1.28) in the MBH of oestrogen-treated 22-day-old rats showed significant (P less than 0.05-0.01) increases in both parameters at 16.00 h (i.e. 2 h before surge levels of gonadotrophins) on days 2 and 3 when compared with other times of day. Such effects were not seen in oil-treated 22-day-old animals or in oestrogen-treated 16-day-old rats. Noradrenaline and dopamine concentrations in the MBH of oestrogen-treated 22-day-old rats remained at baseline levels on days 2 and 3 with the exception of noradrenaline at 17.00 h on day 3 when levels appeared higher (P less than 0.05) than at either 15.00 or 16.00 h.(ABSTRACT TRUNCATED AT 250 WORDS)

Changes in concentrations and rate of decline of adrenaline in the medial preoptic area and mediobasal hypothalamus of acutely ovariectomized steroid-treated rats.

The presence of adrenaline within the central nervous system appears to be essential for the occurrence of an oestrogen-stimulated surge of LH in both pro-oestrous and ovariectomized rats. Previous measurements of adrenergic activity based on the rate of decline of adrenaline (RDA) 2 h after injection of a synthesis inhibitor (SKF 64139) suggested that adrenergic activity increases in both the medial preoptic area (MPOA) and the mediobasal hypothalamus (MBH) at the start of the LH surge (15.00-17.00 h). The purpose of the present studies was to see whether oestrogen and progesterone affected this increase in adrenergic activity at the sites of the cell bodies (MPOA) and axon terminals (MBH) of the gonadotrophin-releasing hormone-synthesizing neurone. Rats ovariectomized at dioestrus showed a reduction in both plasma LH concentrations and RDA (P less than 0.01) in the MBH between 15.00 and 17.00 h on the day of expected pro-oestrus. Oestrogen replacement at operation restored LH levels and the RDA to values found in intact rats. Injection of an antioestrogen (Cl-628), with or without oestrogen, also reduced plasma LH levels and the RDA (P less than 0.01) in the MBH. Removal or replacement of oestrogen apparently had little effect on the RDA in the MPOA. In ovariectomized oestrogen-primed rats an injection of progesterone on the morning of expected pro-oestrus advanced and enhanced not only the LH surge but also the RDA in the MBH (P less than 0.001). Moreover, concentrations of adrenaline in the MBH (but not the MPOA) decreased (P less than 0.001) consistently over a 2-h period following injection of progesterone.(ABSTRACT TRUNCATED AT 250 WORDS)

Hypothalamic adrenergic activity precedes the preovulatory luteinizing hormone surge in the rat.

A preovulatory surge of luteinizing hormone (LH) is stimulated by an increase in plasma oestrogen (E2) and a proestrous neural signal which occurs during the 'critical period' (CP). Adrenergic activity during the CP in brain areas concerned with LH release and receiving adrenergic nerve terminals, increased in the arcuate nucleus-median eminence area (AN-ME) during the CP (14.30-16.30 h), but not in the adjacent perifornical area. Pentobarbital injected prior to the CP inhibited the effect as did ovariectomy, while E2 replacement restored it. Thus increased adrenergic activity in the AN-ME may represent the neural signal that triggers the preovulatory LH surge [5].

Possible resolution of a paradox concerning the use of p-chlorophenylalanine and 5-hydroxytryptophan: evidence for a mode of action involving adrenaline in manipulating the surge of luteinizing hormone in rats.

Various functions involving the central nervous system can be manipulated by the sequential administration of p-chlorophenylalanine and 5-hydroxytryptophan, compounds which respectively inhibit and restore the synthesis of 5-hydroxytryptamine in the brain. An involvement of 5-hydroxytryptamine in the control of a particular function has been considered established when the effect of p-chlorophenylalanine on that function can be overcome by treatment with 5-hydroxytryptophan. This assumption is not, however, invariably substantiated when the functional consequences of other methods of depleting 5-hydroxytryptamine are considered; studies on the control of the daily surge of luteinizing hormone in oestrogen-treated ovariectomized rats present such a paradox. The surge can be prevented by p-chlorophenylalanine and restored by 5-hydroxytryptophan. Nevertheless, neurotoxin-induced lesions of the 5-hydroxytryptamine projections from the raphe nuclei are compatible with a normal occurrence of the surge. We have therefore examined the effects of p-chlorophenylalanine and 5-hydroxytryptophan on hypothalamic monoamines in oestrogen-treated ovariectomized rats and find that the drugs respectively suppress and elevate the concentration of adrenaline in addition to that of 5-hydroxytryptamine. Phenylethanolamine N-methyltransferase, the enzyme responsible for converting noradrenaline to adrenaline, is shown to be inhibited in vivo by p-chlorophenylalanine and in vitro by its metabolite, p-chlorophenylethylamine. The reciprocal effects of p-chlorophenylalanine and 5-hydroxytryptophan on the concentration of adrenaline are of particular interest since drugs which inhibit adrenaline synthesis can block the luteinizing hormone surge. It is proposed that when the 5-hydroxytryptophan-reversible effects of treatment with p-chlorophenylalanine are not reproduced by other procedures which deplete 5-hydroxytryptamine, the significant action of these compounds may involve adrenaline.