Marfan's syndrome and multiple extracranial aneurysms.

Dissecting aneurysms of the extracranial cervical arteries in Marfan's syndrome are most frequently caused by the extension of aortic dissection. Spontaneous and isolated aneurysms limited to the major extracranial cervical arteries have also been reported in Marfan's syndrome, although very rarely. In these cases, the aneurysms are usually asymptomatic or may present as a pulsatile mass. Transient ischemic attacks (TIAs) or strokes, associated with isolated extracranial aneurysms, have not been mentioned in Marfan's syndrome. We report a patient with Marfan's syndrome presenting with TIAs in whom we detected a saccular aneurysm of the vertebral artery as well as bilateral fusiform aneurysms of the internal carotid arteries.

Severe but reversible encephalopathy associated with cefepime.

In this study, a report has been made of 19 cases of severe encephalopathy in patients with renal impairment who were treated during the last three years for various infections with cefepime, a new parenteral cephalosporin antibiotic. All patients (aged 57 to 91 years) presented a prolonged confusional state associated with diffuse rhythmic non-reactive triphasic sharp waves on the EEG. All the electroclinical symptomatology disappeared within 24-48 hours after discontinuation of drug administration. A clear relation was found between encephalopathy and cefepime intake. These observations underline the fact that the cefepime dosage should be reduced in renally impaired patients.

Proximal myotonic myopathy: clinical, electrophysiological and pathological findings in a family.

Proximal myotonic myopathy (PROMM) is an autosomal dominant muscle disorder characterized by proximal weakness, myotonia, muscle pain and cataract. It resembles Steinert myotonic dystrophy (MD), but weakness is proximal, without facial muscle involvement, and the chromosome 19 CTG trinucleotide repeat expansion characteristic of MD is not present. We describe a further family with PROMM. Affected members complained of weakness of lower limbs or of myotonia. EMG revealed diffuse myotonic discharges. Muscle histology showed dystrophic abnormalities. The PROMM phenotype varies, even in the same pedigree, and may mimic MD or limb-girdle muscle dystrophy. EMG is particularly useful, since it may disclose myotonic discharges even in the absence of overt myotonia. Thus far it is not known whether PROMM is a single entity, or if it represents a heterogeneous group of disorders. This question will probably soon be settled through genetic analysis.

Synaptic transmission at nicotinic acetylcholine receptors in rat hippocampal organotypic cultures and slices.

1. Whole-cell clamp recordings of the compound synaptic current elicited by afferent stimulation of Schaffer collaterals showed that blockade of the NMDA, AMPA and GABAA receptor-mediated components by 6-nitro-7-sulphamoyl- benzo(f)quinoxaline-2,3-dione (NBQX), 3-((R)-2-carboxypiperazine-4-yl)propyl-1-phosphonate (R-CPP) and picrotoxin, respectively, left a small residual current in 39 out of 41 CA1 pyramidal neurones in organotypic cultures and 9 out of 16 CA1 cells in acutely prepared slices. 2. This current represented 2. 9 +/- 0.4 % of the compound evoked synaptic response in organoypic cultures and 1.4 +/- 0.5 % in slices. It was characterized by a slightly rectifying I-V curve and a reversal potential of 3.4 +/- 5. 1 mV. 3. This residual current was insensitive to blockers of GABAB, purinergic, muscarinic and 5-HT3 receptors, but it was essentially blocked by the nicotinic receptor antagonist d-tubocurarine (91 +/- 4 % blockade; 20 microM), and partly blocked by alpha-bungarotoxin (200 nM) and methyllycaconitine (10 nM), two antagonists with a higher selectivity for alpha7 subunit-containing nicotinic receptors (48 +/- 3 % and 55 +/- 11 % blockade, respectively). 4. The residual current was of synaptic origin, since it occurred after a small delay; its amplitude depended upon the stimulation intensity and it was calcium dependent and blocked by the sodium channel antagonist tetrodotoxin. 5. We conclude that afferent stimulation applied in the stratum radiatum evokes in some hippocampal neurones a small synaptic current mediated by activation of neuronal nicotinic receptors.

Heterosynaptic interactions between LTP and LTD in CA1 hippocampal slices.

Experiments in which several high and/or low frequency stimulation patterns were applied to different groups of afferents in CA1 hippocampal slices revealed the existence of heterosynaptic interactions between LTP and LTD. Specifically, we report that repeated induction of LTD on one input was associated with a heterosynaptic reversal of the LTP previously induced on a separate pathway. Reapplication of high frequency stimulation at the end of the experiment reinstated LTP. This heterosynaptic reversal occurred without modification of naive responses, and it was prevented by D-AP5, an NMDA receptor antagonist, or cyclosporin A, a calcineurin inhibitor. Similarly, induction of LTP on one input was found to reverse heterosynaptically the LTD previously induced on a separate pathway. This effect was also sensitive to D-AP5, it occurred without modification of naive pathways, and LTD could be reinstated by low frequency trains. These results indicate that repeated induction of LTP or LTD on one group of afferents can reset synaptic efficacy at other nonactivated synapses.