Outbreak of staphylococcal bullous impetigo in a maternity ward linked to an asymptomatic healthcare worker.

An outbreak of staphylococcal bullous impetigo occurred over a period of five months in a maternity ward involving seven infected and two colonised neonates. The skin lesions were due to epidermolytic toxin A-producing Staphylococcus aureus. Infection control measures were implemented and a retrospective case-control study performed. Contact with an auxiliary nurse was the only risk factor for cases of bullous impetigo (P<0.01). The nurse cared for all seven cases and was an asymptomatic nasal carrier of the epidemic strain. Repeated courses of decontamination treatment failed to eradicate carriage. Nine months after the last case, another neonate developed a more severe form of bullous impetigo and the auxiliary nurse was reassigned to an adult ward.

Simultaneous visualization of aortic and [3H]5-hydroxytryptamine-accumulating cell bodies in the nodose ganglion of the cat.

1. Single- and double-tracer experiments were performed in cats to investigate the relationship between the aortic cells and the cell bodies accumulating 5-hydroxytryptamine (5-HT) in the nodose ganglion. In one series of experiments, horseradish peroxidase (HRP) was applied to the central end of the aortic nerve, anterogradely transported and accumulated in ganglionar perikarya. The distribution of HRP-positive neurones was reconstructed in serial sections through the nodose ganglion. In a second series of experiments, the distribution of [(3)H]5-HT-accumulating cell bodies was assessed following incubation of the nodose ganglion in [(3)H]5-HT. The third series of experiments combined the treatments of the preceding ones: anterograde transport of HRP in the aortic nerve followed by incubation of the nodose ganglion in [(3)H]5-HT.2. The results from these experiments provide more information with regard to (i) the topographical relationship between the aortic and [(3)H]5-HT-accumulating cell bodies in the same ganglion and (ii) the distribution and number of double-labelled neurones, giving further indications about histochemical components of the aortic nerve.3. The HRP experiments demonstrated that HRP-positive cells show a preferential pattern of topographical organization. They were mostly located in the medial border of the ganglion where the laryngeal and aortic nerves enter. On the other hand, [(3)H]5-HT-accumulating neurones were scattered throughout the ganglion.4. In double-tracer experiments, three populations of labelled cell bodies were distinguished in the same nodose ganglion: (1) single HRP-cells; (2) single [(3)H]5-HT-accumulating cells and (3) double-labelled cells. The distribution of the latter population exhibited no preferential localization. Quantitative estimates indicated that double-labelled neurones constituted 65-85% of the population of HRP-positive cell bodies.5. These results show that most aortic neurones are able to take up exogenous serotonin and may be serotonergic neurones. They suggest that serotonin may be involved in physiological effects mediated via the aortic nerves.

Selective retrograde transport of 3H-serotonin in vagal afferents.

A new serotonergic afferent vagal component has been demonstrated in the cat by radioautography. Twenty-four hours after a bilateral injection of tritiated serotonin (3H-5-HT) into the area of the nucleus of the solitary tract (NST), heavily and lightly labelled cell bodies were observed in the nodose ganglia. After unilateral injections of 3H-5-HT into the same area, labelled ganglionar cell bodies were found in the ipsilateral nodose ganglion. Some were also found in the contralateral one, suggesting a serotonergic crossed fibers component. Dense clusters of silver grains, depicting typical labelling of neuronal varicosities, were observed in the NST. After destruction of the serotonergic terminals with 5,7-dihydroxytryptamine, followed by injection of 3H-5-HT, the number of labelled cell bodies decreased dramatically in the ipsilateral nodose ganglia and the clusters of silver grains disappeared in the NST. After ligature or section of the supranodose vagal nerve, following injection of 3H-5-HT into the NST, no radioautographic reaction was observed in the homolateral nodose ganglia. The present study demonstrates the existence of a peripheral serotonergic system in vagal afferents. The physiological implications of this new serotonergic visceral pathway remain to be studied.

Serotoninergic mechanisms and sleep.

Serotoninergic neurons play a critical role in the sleep mechanism. This is supported by a lot of converging experiments and has provided the basis for a great deal of research. A critical analysis is first developed, supported by more recent data which are not in complete agreement with the theory that raphe nuclei are actively implied in slow wave sleep. On the other hand, numerous experimental evidences were collected during the sixties on the EEG synchronizing influence of the lower brain stem and preoptic area. Recent data showed that serotonin could also play here a crucial role in the induction of sleep. Nevertheless, at the moment, it is difficult to make a critical examination of the interaction and regulation of these putative 5-HT-related areas of the brain, but we can postulate that the occurrence of true physiological sleep-waking continuum necessitates their successive or conjoint activation.

Efferent projections of the area postrema demonstrated by autoradiography.

The efferents connections of the area postrema (AP) have been studied autoradiographically following iontophoretic injections of 3H-glycine or 3H-leucine into the area postrema. Precise control of the diffusion of the labelled amino acids injected iontophorectically into the AP was made using the technique of sectioning with a cryostat. AP projects to a great number of structures. Projections to nucleus tractus solitarius (NFS), dorsal vagal nucleus, nucleus intercalatus, nucleus praepositus hypoglossi, nucleus hypoglossal, the mesencephalic nucleus of V nerve, locus coeruleus and superior and inferior colliculi are shown bilaterally. The density of the efferents was greatest to the NFS and the LC. Corelations are suggested with functional mechanisms of cardiovascular regulation.

Afferent and efferent connections of the area postrema demonstrated by the horseradish peroxidase method.

The previous autoradiographic study of the efferent connections of the arca postrema have been completed by using horseradish peroxidase (H.R.P.) as a marking agent. These two labelling techniques have made it possible to determine two categories of structures connected with A.P.: those with afferent connections (Nucleus ambiguus), or efferent connections (mesencephalic nucleus of V, Locus coeruleus, griseum centrale and inferior and superior colliculi) and those having both types of connections (Nucleus tractus solitarii (N.F.S.), Dorsal vagal nucleus, nucleus intercalatus, hypoglossal nucleus). The afferent and efferent pathways of the A.P. identified with H.R.P. coincide with the catecholaminergic pathways demonstrated in the rat by Lindvall and Björklund (1974).

Localization of aortic cells in the nodose ganglion by HRP retrograde transport in the cat.

Localization of the aortic cells in the nodose ganglion was attempted in the cat using retrograde axonal transport of horseradish peroxidase (HRP). Following dissection of the aortic nerve from the vago-aortic trunk, the cut ends of the aortic fibers were immersed in a HRP solution for 23--46 h. Labelled cells were found in the nodose ganglion and were located mainly in the medial border of the ganglion.