Hippocampal-cortical interaction during periods of subcortical silence.

Hippocampal ripples, episodic high-frequency field-potential oscillations primarily occurring during sleep and calmness, have been described in mice, rats, rabbits, monkeys and humans, and so far they have been associated with retention of previously acquired awake experience. Although hippocampal ripples have been studied in detail using neurophysiological methods, the global effects of ripples on the entire brain remain elusive, primarily owing to a lack of methodologies permitting concurrent hippocampal recordings and whole-brain activity mapping. By combining electrophysiological recordings in hippocampus with ripple-triggered functional magnetic resonance imaging, here we show that most of the cerebral cortex is selectively activated during the ripples, whereas most diencephalic, midbrain and brainstem regions are strongly and consistently inhibited. Analysis of regional temporal response patterns indicates that thalamic activity suppression precedes the hippocampal population burst, which itself is temporally bounded by massive activations of association and primary cortical areas. These findings suggest that during off-line memory consolidation, synergistic thalamocortical activity may be orchestrating a privileged interaction state between hippocampus and cortex by silencing the output of subcortical centres involved in sensory processing or potentially mediating procedural learning. Such a mechanism would cause minimal interference, enabling consolidation of hippocampus-dependent memory.

Localization and controls of aromatase in the quail spinal cord.

In adult male and female Japanese quail, aromatase-immunoreactive cells were identified in the spinal dorsal horns from the upper cervical segments to the lower caudal area. These immunoreactive cells are located mostly in laminae I-III, with additional sparse cells being present in the medial part of lamina V and, at the cervical level exclusively, in lamina X around the central canal. Radioenzyme assays based on the measurement of tritiated water release confirmed the presence of substantial levels of aromatase activity throughout the rostrocaudal extent of the spinal cord. Contrary to what is observed in the brain, this enzyme activity and the number of aromatase-immunoreactive cells in five representative segments of the spinal cord are not different in sexually mature males or females and are not influenced in males by castration with or without testosterone treatment. The aromatase activity and the numbers of aromatase-immunoreactive cells per section are higher at the brachial and thoracic levels than in the cervical and lumbar segments. These experiments demonstrate for the first time the presence of local estrogen production in the spinal cord of a higher vertebrate. This production was localized in the sensory fields of the dorsal horn, where estrogen receptors have been identified previously in several avian and mammalian species, suggesting an implication of aromatase in the modulation of sensory (particularly nociceptive) processes.

Localization of oestrogen receptors in the sensory and motor areas of the spinal cord in Japanese quail (Coturnix japonica).

In Japanese quail, the presence of aromatase (oestrogen synthase) in the dorsal horn of the spinal cord suggests that spinal sensory processes might be controlled by local actions of oestrogens. This is supported by the presence of oestrogen receptors and aromatase in the dorsal horn of the spinal cord in rats, and by the alteration of sensitivity by oestrogens in various mammalian species and also in canaries. We investigated whether oestrogens that are locally produced in the quail spinal cord can bind to specific receptors in the vicinity of their site of synthesis. We demonstrate the presence of numerous oestrogen receptor alpha-immunoreactive (ERalpha-ir) cell nuclei, predominantly in laminae II and, to a lesser extent, I and III of the dorsal horn of the spinal cord (i.e. in the area where aromatase was previously identified). ERalpha-ir cells were also seen in various parts of the intermediate zone (laminae V-VII). This presence of ERalpha-ir cells in the dorsal horn and intermediate zone fits in well with the distribution of ERalpha-ir cells in homologous areas in mammals, including rats. Only a few labelled cells were found in the ventral horn in the cervical, brachial, thoracic and first lumbar segments, but a conspicuous dense group of large ERalpha-ir cells was identified in lamina IX of the ventral horn in synsacral segments 8-10, which contain the motoneurones innervating the muscles of the cloacal gland. The presence of ERalpha-ir cells in lamina IX of these synsacral segments in quail contrasts with the finding that motoneurones innervating penile muscles in rats contain androgen, but not oestrogen receptors, and are influenced by androgens rather than by oestrogens. Together, these data suggest that spinal actions of oestrogens may modulate the sensory and motor systems that participate in reproduction, as well as other nonreproductive functions in quail.

The assessment of nociceptive and non-nociceptive skin sensitivity in the Japanese quail (Coturnix japonica).

We evaluated the efficacy of two nociceptive tests, the hot water (HWT) and the foot pressure tests (FPT), and one non-nociceptive test (Semmes-Weinstein test, SWT) in assessing skin sensitivity in conscious Japanese quail. All stimuli elicited a reflex-like, strongly reproducible response. Responses in the HWT and FPT were identified as typical nocifensive flight-fight behavior. In untreated birds, these responses occurred at temperatures and forces described previously as noxious. In the SWT, two responses were observed: a slight ruffling of the cloacal gland feathers due to the stimulation of the cloacal gland, and a brief extension of the limbs due to the stimulation of the ilium or pectoral apterium. These reactions occurred at intensities recognized as innocuous. Morphine significantly altered the response latency and threshold in the HWT and FPT, but had no effect in the SWT. However, the SWT response threshold was significantly increased by local application of xylocaine. Taken together, the pattern of the responses, the intensities and the effects of morphine and xylocaine allowed to distinguish between nociceptive and non-nociceptive tests. They also demonstrate the efficacy of these tests to evaluate skin sensitivity in quail and to assess its modulation by chemical factors that affect somatosensory processes.

Clinical efficacy of cefonicid in the treatment of staphylococcal infections.

Cefonicid is a parenteral cephalosporin with a half-life of 4.5 hours, which permits once-daily dosing. The efficacy of cefonicid in the treatment of established staphylococcal infections was reviewed in all patients with infections due to staphylococci who were treated with cefonicid during the US clinical development program. Two hundred evaluable cases were identified, of which 95 had other pathogens as well. Cefonicid was clinically effective in 92% of skin and soft tissue infections, 74% of bone and joint infections, 83% of respiratory tract infections, and 95% of urinary tract infections. None of the three evaluable patients with Staphylococcus aureus endocarditis responded to cefonicid. Thus, based on current evidence, cefonicid is not effective in the treatment of established staphylococcal endocarditis. However, for the treatment of staphylococcal infections at other sites, cefonicid is comparable to other cephalosporins, most of which must be administered more frequently than cefonicid and thus are less cost-effective.

[Microsurgery and carpal tunnel]. / Microchirurgie et canal carpien.

In the surgical treatment of the carpal tunnel syndrome, the best way to take out the compression of the fibers of the median nerve is to do: --an epinevrotomy, --an intraneural neurolysis according to the extent of the lesions, --a clearing of the branches of the nerve trunk. It is to say that to achieve the goal the help of an operating microscope is necessary. To sustain their opinion the authors give a review of 50 cases.

External fixation in child traumatology.

The authors present their experience of Hoffmann® external fixation in pediatric traumatology. Fractures of the lower limb are the most frequent (47 tibias, 13 femurs); a few fractures involved the upper extremity. The Hoffmann device constituted the complete treatment, using a light configuration frame in order to obtain elastic fixation and periosteal healing. Pin reactions are more frequent where the pin tract penetrates large soft tissue structures, as at the proximal femur. Only one refracture occurred after healing. Transient impairment of range of motion may be expected. Use of the Hoffmann fixator is recommended in children with open fractures or fractures associated with soft tissue lesions, in children with head injury with resultant increased motor tone, and in polytrauma patients to facilitate patient care and transport for reassessment and therapeutic procedures.

[Treatment of fractures of the carpal scaphoid with Herbert's bone screw. Review of 21 clinical cases]. / Traitement des fractures du scaphoïde carpien par vis de Herbert. Revue de 21 cas cliniques.

Twenty-one patients with scaphoid fractures treated by internal fixation with the Herbert screw are reviewed. Nine patients presented acute fractures and twelve had fractures with delayed or non-union. The results of these two kinds of lesions are analyzed following the criteria established by Herbert and Fisher in 1984. This type of internal fixation gives excellent results in isolated lesions of the scaphoid provided it is correctly executed.

Aromatization of androgens into estrogens reduces response latency to a noxious thermal stimulus in male quail.

We recently demonstrated the presence of estrogen synthase (aromatase) and of estrogen receptors in the dorsal horn (laminae I-II) throughout the rostrocaudal extent of the spinal cord in male and female Japanese quail. The spinal laminae I-II receive and process abundant sensory information elicited, among others, by acute noxious stimulation of the skin and resulting in rapid, reflex-like withdrawal behavior. In the present study, we demonstrate that systemic treatment with estradiol or testosterone markedly decreases the latency of the foot withdrawal in the hot water test. A simultaneous treatment with an aromatase inhibitor blocks the effects of testosterone demonstrating, hence, that they are mediated by a conversion of testosterone into an estrogen by aromatase. Furthermore, the testosterone- or estradiol-induced decrease in foot withdrawal latency is blocked by a treatment with the estradiol receptor antagonist, tamoxifen, indicating that the effects are largely mediated by the interaction of estradiol with estrogen receptors. Together, these data suggest that sex steroids modulate sensitivity to noxious stimuli possibly by a direct action at the level of the dorsal horn of the spinal cord.

Study on the external fixator in the treatment of the fractures of the inferior end of the two bones of the adult's forearm. Report of fifty-five cases.

The authors report 55 cases of fracture with significant displacement of the distal end of the radius. In 30 cases, there were, moreover, lesions of adjacent bones and in 18 cases, lesions of the soft tissues. The fractures were treated by Hoffmann external fixator placed either immediately or later on, after the failure of conservative treatment. Thirty-four cases, reexamined within a period of at least six months, were used to show the results according to the criteria of Castaing. The overall results show 3 perfect results, 23 satisfactory ones and 8 quite satisfactory. The main complication of this series is frequent algodystrophy in the first cases. This has practically disappeared since much less traction is applied to the fracture site.

[Semilunar disease]. / La maladie du semi-lunaire.

In a multicenter study involving the five Orthopaedic Services of the COC, 57 patients with Kienböck's disease were reviewed 90% were treated surgically. The most common operations were ulna lengthening (30 cases) and lunate resection (11 cases). The most frequent indications or surgery were pain and stiffness of the wrist. Radiological changes are classified according to Decoulx. For evaluating post-operative radiological changes, however, the authors use different criteria ulna lengthening and lunate resection improved pain and mobility in 75% of cases. This study shows that lunate resection is a valid operation in the treatment of Kienböck's disease.