[Life-threatening metabolic acidosis after ingestion of fire extinguisher powder]. / Lebensbedrohliche Acidose nach Ingestion von ABC-Löschpulver.

We present the case of a 31-year old male with ingestion of fire extinguisher powder in an attempted suicide. After consulting several poison information centres, the intoxication was initially classified as harmless; nevertheless, the patient was admitted to our intensive care unit for cardiopulmonary monitoring. Subsequently, due to the ingestion of ammonium sulphate and ammonium dihydrogen phosphate containing powder the patient developed severe metabolic acidosis with distinct electrolyte imbalance that required temporary haemodialysis.

Developmental suppression of schizophrenia-associated miR-137 alters sensorimotor function in zebrafish.

The neurodevelopmentally regulated microRNA miR-137 was strongly implicated as risk locus for schizophrenia in the most recent genome wide association study coordinated by the Psychiatric Genome Consortium (PGC). This molecule is highly conserved in vertebrates enabling the investigation of its function in the developing zebrafish. We utilized this model system to achieve overexpression and suppression of miR-137, both transiently and stably through transgenesis. While miR-137 overexpression was not associated with an observable specific phenotype, downregulation by antisense morpholino and/or transgenic expression of miR-sponge RNA induced significant impairment of both embryonic and larval touch-sensitivity without compromising overall anatomical development. We observed miR-137 expression and activity in sensory neurons including Rohon-Beard neurons and dorsal root ganglia, two neuronal cell types that confer touch-sensitivity in normal zebrafish, suggesting a role of these cell types in the observed phenotype. The lack of obvious anatomical or histological pathology in these cells, however, suggested that subtle axonal network defects or a change in synaptic function and neural connectivity might be responsible for the behavioral phenotype rather than a change in the cellular morphology or neuroanatomy.

CNBP mediates neural crest cell expansion by controlling cell proliferation and cell survival during rostral head development.

Striking conservation in various organisms suggests that cellular nucleic acid binding protein (CNBP) plays a fundamental biological role across different species. Recently, it was reported that CNBP is required for forebrain formation during chick and mouse embryogenesis. In this study, we have used the zebrafish model system to expand and contextualize the basic understanding of the molecular mechanisms of CNBP activity during vertebrate head development. We show that zebrafish cnbp is expressed in the anterior CNS in a similar fashion as has been observed in early chick and mouse embryos. Using antisense morpholino oligonucleotide knockdown assays, we show that CNBP depletion causes forebrain truncation while trunk development appears normal. A substantial reduction in cell proliferation and an increase in cell death were observed in the anterior regions of cnbp morphant embryos, mainly within the cnbp expression territory. In situ hybridization assays show that CNBP depletion does not affect CNS patterning while it does cause depletion of neural crest derivatives. Our data suggest an essential role for CNBP in mediating neural crest expansion by controlling proliferation and cell survival rather than via a cell fate switch during rostral head development. This possible role of CNBP may not only explain the craniofacial anomalies observed in zebrafish but also those reported for mice and chicken and, moreover, demonstrates that CNBP plays an essential and conserved role during vertebrate head development.

not really finished is crucial for development of the zebrafish outer retina and encodes a transcription factor highly homologous to human Nuclear Respiratory Factor-1 and avian Initiation Binding Repressor.

Not really finished (nrf), a larval-lethal mutation in zebrafish generated by retroviral insertion, causes specific retinal defects. Analysis of mutant retinae reveals an extensive loss of photoreceptors and their precursors around the onset of visual function. These neurons undergo apoptosis during differentiation, affecting all classes of photoreceptors, suggesting an essential function of nrf for the development of all types of photoreceptors. In the mutant, some photoreceptors escape cell death, are functional and, as judged by opsin expression, belong to at least three classes of cones and one class of rods. The protein encoded by nrf is a close homologue of human Nuclear Respiratory Factor 1 and avian Initiation Binding Repressor, transcriptional regulators binding the upstream consensus sequence RCGCRYGCGY. At 24 hours of development, prior to neuronal differentiation, nrf is expressed ubiquitously throughout the developing retina and central nervous system. At 48 hours of development, expression of nrf is detected in the ganglion cell layer, in the neurons of the inner nuclear layer, and in the optic nerve and optic tracts, and, at 72 hours of development, is no longer detectable by in situ hybridization. Mutants contain no detectable nrf mRNA and die within 2 weeks postfertilization as larvae with reduced brain size. On the basis of its similarity with NRF-1 and IBR, nrf is likely involved in transcriptional regulation of multiple target genes, including those that encode mitochondrial proteins, growth factor receptors and other transcription factors. This demonstrates the power of insertional mutagenesis as a means for characterizing novel genes necessary for vertebrate retinal development.

Cell proliferation in a peripheral target is required for the induction of central neurogenesis in the leech.

Several days after the completion of the early phase of cell proliferation that generates most of the leech central nervous system, the pair of "sex ganglia" in the two reproductive segments of the midbody undergo a second period of neurogenesis that gives rise to several hundred peripherally induced central (PIC) neurons. This proliferative phase, which begins on embryonic day 17 (E17), is induced by the interaction of a few specific neurons in the sex ganglia with a peripheral target, the male genitalia, during a critical period that extends from E13 to E16. The central nervous system (CNS) determines the critical period, since the male genitalia have the capacity to induce PIC neurons beginning on E10 and continuing throughout embryogenesis. Here we first show, by injecting hydroxyurea into staged embryos to ablate dividing cells, that PIC neuron precursors begin to divide at a low rate before E17, during the critical period. Then, through a series of homochronic and heterochronic male organ transplantations combined with hydroxyurea treatment of hosts and/or donors, we show that cell proliferation is required in the target itself for it to be competent to induce PIC neurons. These observations demonstrate that a nerve connection can couple cell proliferation in a peripheral target to cell proliferation in the CNS, providing a novel means for size adjustment of a central neuronal population relative to a peripheral target.

Identified central neurons convey a mitogenic signal from a peripheral target to the CNS.

Regulation of central neurogenesis by a peripheral target has been previously demonstrated in the ventral nerve cord of the leech Hirudo medicinalis (Baptista, C. A., Gershon, T. R. and Macagno, E. R. (1990). Nature 346, 855-858) Specifically, innervation of the male genitalia by the fifth and sixth segmental ganglia (the sex ganglia) was shown to trigger the birth of several hundred central neurons (PIC neurons) in these ganglia. As reported here, removal of the target early during induction shows that PIC neurons can be independently induced in each side of a ganglion, indicating that the inductive signal is both highly localized and conveyed to each hemiganglion independently. Further, since recent observations (Becker, T., Berliner, A. J., Nitabach, M. N., Gan, W.-B. and Macagno, E. R. (1995). Development, 121, 359-369) had indicated that efferent projections are probably involved in this phenomenon, we individually ablated all possible candidates, which led to the identification of two central neurons that appear to play significant roles in conveying the inductive signal to the CNS. Ablation of a single ML neuron reduced cell proliferation in its own hemiganglion by nearly 50%, on the average. In contrast, proliferation on the opposite side of the ganglion increased by about 25%, suggesting the possibility of a compensatory response by the remaining contralateral ML neuron. Simultaneous ablation of both ML neurons in a sex ganglion caused similar reductions in cell proliferation in each hemiganglion. Deletion of a single AL neuron produced a weaker (7%) but nonetheless reproducible reduction. Ablation of the other nine central neurons that might have been involved in PIC neuron induction had no detectable effect. Both ML and AL neurons exhibit ipsilateral peripheral projections, and both arborize mostly in the hemiganglion where they reside. Thus, we conclude that peripheral regulation of central neurogenesis is mediated in the leech by inductive signals conveyed retrogradely to each hemiganglion by specific central neurons that innervate this target and the hemiganglion they affect.

Reversible visual loss due to impacted lateral orbital wall fractures.

Impaction of the sharp medial edge of the orbital plate of the greater sphenoid wing into the orbital apex is a unique type of lateral orbital wall fracture that can produce a potentially reversible optic neuropathy. Two patients in whom the lateral or temporal approach to the orbit was used to reduce this type of fracture will be presented. In both patients, improvement in vision appeared to be related to removal of a bone fragment compressing the optic nerve in the orbital apex.

Injuries of the nasofrontal orifices in frontal sinus fractures.

Disruption of the nasofrontal ostia or ducts is an important factor in the development of immediate and delayed complications following frontal sinus fractures. Thorough evaluation of 50 consecutive patients with frontal sinus injuries caused by blunt trauma revealed several fracture patterns that frequently include injury to the drainage system. Anterior table fractures, even when displaced, do not produce such injuries unless associated with a fracture of the supraorbital rim or nasoethmoidal complex. Combined fractures of the anterior and posterior tables are almost always accompanied by injuries to the orifices. Severity of these injuries is variable but can be predicted from the sinus wall fracture patterns. Although CT scanning is incapable of directly imaging involvement of the ostia or ducts, it will give sufficient information to allow for accurate prediction of disruption of the drainage system.

Electrical stimulation of the auditory system in children deafened by meningitis.

Twenty-five children deafened by meningitis were compared with 10 congenitally deaf children on cochlear implant performance. All subjects had met the audiologic criterion of profound deafness as required for implant surgery. Twenty subjects in the meningitis group had some degree of ossification at the round window, and drilling was required for electrode insertion into the scala tympani. In six of these subjects, bone completely filled the scala. There was a significant relationship between extensive ossification and the etiologic pathogen Diplococcus pneumoniae, as determined by radiologic and surgical reports. Postoperative results revealed that all subjects could be electrically stimulated, except for one with extensive bone formation. On implant performance, the meningitis group demonstrated sound-field thresholds comparable to those of the group with congenital deafness but required significantly higher voltage settings. These findings suggest that even with extensive labyrinthine ossification caused by meningitic deafness, neural elements are present and can be stimulated if enough power can be safely provided.

Labyrinthine ossification secondary to childhood bacterial meningitis: implications for cochlear implant surgery.

Of 20 children who underwent cochlear implantation for profound sensorineural hearing loss secondary to bacterial meningitis, 14 had round-window and cochlear ossification at surgery. Preoperative polytomography demonstrated ossification in 11 of these. The incidence of ossification was highest after meningitis secondary to pneumococcal pneumonia. In only one of four children with severe ossification of the labyrinth was implant surgery unsuccessful. Preliminary results indicate that mild labyrinthine ossification is not a contraindication to cochlear implantation.

Computed tomography with gas cisternography for detection of small acoustic tumors. A study of five false-positive results.

Cranial computed tomography (CT) with gas cisternography is reported to be the most accurate method of detection of small acoustic tumors. However, five false-positive CT results experienced in three years are now reported. This is a false-positive rate of 22% for tumors with less than 5-mm protrusion into the cerebellopontine angle, and a false-positive rate of 50% for tumors with less than 2-mm protrusion. A false-positive result is suspected if no mass protrudes at the porus or if gas enters the lateral internal auditory canal.

Normal CT anatomy of the paranasal sinuses.

The role and technique of CT in the evaluation of the paranasal sinuses are discussed. CT scans of normal patients in axial and coronal planes are presented. A brief discussion of the normal morphology and development of the paranasal sinuses is included.

The vestibular aqueduct in congenital deafness: evaluation by the axial projection.

Thirty-two patients with congenital neurosensory hearing loss demonstrated dilatation of the peripheral limb of the vestibular aqueduct as visualized on pluridirectional tomograms. Multiple additional anomalies involving most frequently the cochlea (15 patients) but also the ossicles (three patients) or vestibule (one patient) were associated. The axial-pyramidal (Poschl) projection was of great value in evaluation of the vestibular aqueduct and cochlea. The technique, clinical correlation, and surgical implications are discussed.

Computed tomography of posterior fossa ependymomas in childhood.

In reviewing 10 children with surgically proven posterior fossa ependymomas, various computed tomographic representations were seen. Calcification, seen in 50% of the cases, was the single most important finding suggesting the diagnosis of ependymoma. The appearance of two of our ependymomas mimicked the "typical" appearance of medulloblastomas. A case of calcified brainstem ependymoma is presented, to our knowledge, the first such case studied with computed tomography.

Scleroma (Rhinoscleroma). A histologic immunohistochemical study with bacteriologic correlates.

Scleroma was diagnosed in nine of 30 Spanish-surnamed patients who had inflammatory lesions of the nose, pharynx, and larynx during the two-year period from Jan 1, 1978, through Dec 31, 1979. A total of 19 biopsy specimens were taken from these nine patients. In six of the 19 specimens, a histologic diagnosis of scleroma was not possible. Seventeen of the specimens with characteristic histologic findings stained with the peroxidase-antiperoxidase method for detection of Klebsiella capsular antigen III, although in 11 of these specimens, simultaneous cultures failed to reveal the characteristic Klebsiella rhinoscleromatis. These specimens showed the features of one of the three histopathologic forms of scleroma: ozena, granuloma, or scleroma. A range of tissue reactions was identified: histiocyte and plasma cell nodules, vasculitis, acute inflammation, pseudoepitheliomatous hyperplasia, ulceration, and submucosal keratin cyst. Comparison with histochemical bacterial stains revealed that the PAS and Hotchkiss-McManus stains gave unequivocal positive results less frequently than the immunoperoxidase method, and were less specific. Methenamine silver, Giemsa, Deiterle, Brown and Brenn, and Brown and Hopps were unreliable for the detection of the organism. The immunoperoxidase method can be appropriately used when the spectrum of histopathologic findings suggests a differential diagnosis of scleroma.

Computed tomography of carotid-cavernous fistula.

Fourteen patients with angiographically-proven carotid-cavernous fistulas were evaluated by computed tomography (CT). Unilateral or bilateral exophthalmos was noted in 12 patients. Slight blurring of the margin of the globe was present in two, presumably due to pulsations of the globe or conjunctival edema. Superior ophthalmic veins were prominent in 12 patients and were often larger on the side of the fistula. Irregularity or absence of contrast enhancement of the superior ophthalmic vein may indicate partial or complete thrombosis. Focal bulging or diffuse distention of the cavernous sinus was noted in nine patients. Enlargement of the extraocular muscles was observed in seven with swelling of the eyelids and edema of the conjunctiva in eight patients. The pattern of venous drainage, type of fistula, and time intervals between trauma, commencement of fistula, and CT scan may affect the CT manifestations of carotid-cavernous fistulas.

Inconsistent venous opacification: a pitfall of epidural venography.

The lumbar epidural venograms of 45 consecutive patients with prior normal or equivocal myelographic examinations were reviewed. Each venographic injection was performed using transfemoral double-catheter technique, abdominal compression, Valsalva maneuver, and serial filming for 12 sec. There was a 30% incidence of false "occlusions" of epidural veins suggestive of compression by a herniated intervertebral disk. These false venous occlusions were demonstrated to be such by both subsequent opacification of previously nonopacified veins and lack of opacification of previously opacified veins during repeat venography. In view of the significant incidence of spurious venous occlusions in this series, It is recommended that epidural venography with single injection should be interpreted with caution except for normal studies.