African humid periods triggered the reactivation of a large river system in Western Sahara.

The Sahara experienced several humid episodes during the late Quaternary, associated with the development of vast fluvial networks and enhanced freshwater delivery to the surrounding ocean margins. In particular, marine sediment records off Western Sahara indicate deposition of river-borne material at those times, implying sustained fluvial discharges along the West African margin. Today, however, no major river exists in this area; therefore, the origin of these sediments remains unclear. Here, using orbital radar satellite imagery, we present geomorphological data that reveal the existence of a large buried paleodrainage network on the Mauritanian coast. On the basis of evidence from the literature, we propose that reactivation of this major paleoriver during past humid periods contributed to the delivery of sediments to the Tropical Atlantic margin. This finding provides new insights for the interpretation of terrigenous sediment records off Western Africa, with important implications for our understanding of the paleohydrological history of the Sahara.

Brain Pathology in Adult Rats Treated With Domoic Acid.

Domoic acid (DA) is a neurotoxin reported to produce damage to the hippocampus, which plays an important role in memory. The authors inoculated rats intraperitoneally with an effective toxic dose of DA to study the distribution of the toxin in major internal organs by using immunohistochemistry, as well as to evaluate the induced pathology by means of histopathologic and immunohistochemical methods at different time points after toxin administration (6, 10, and 24 hours; 5 and 54 days). DA was detected by immunohistochemistry exclusively in pyramidal neurons of the hippocampus at 6 and 10 hours after dosing. Lesions induced by DA were prominent at 5 days following treatment in selected regions of the brain: hippocampus, amygdala, piriform and perirhinal cortices, olfactory tubercle, septal nuclei, and thalamus. The authors found 2 types of lesions: delayed death of selective neurons and large areas of necrosis, both accompanied by astrocytosis and microgliosis. At 54 days after DA exposure, the pathology was characterized by still-distinguishable dying neurons, calcified lesions in the thalamus, persistent astrocytosis, and pronounced microgliosis. The expression of nitric oxide synthases suggests a role for nitric oxide in the pathogenesis of neuronal degeneration and chronic inflammation induced by DA in the brain.

Angioplastia coronaria sobre arteria descendente anterior con origen anómalo y arteria coronaria derecha / Coronary angioplasty on anterior descending artery with anomalous origin and right coronary artery

Se presenta el caso clínico de un paciente exfumador (sin otro antecedente), que después de una situación de estrés comenzó a experimentar, por más de 20 minutos, dolor precordial intenso, opresivo y retroesternal, irradiado hacia el hombro izquierdo, acompañado de diaforesis. Sobre la base de los resultados de la prueba de esfuerzo y ecografía, se realizó cateterismo cardíaco, lo cual permitió diagnosticar una anomalía en la arteria coronaria izquierda, dada por el nacimiento de la descendente anterior de la coronaria derecha. La obstrucción de ambas arterias fue eliminada exitosamente mediante angioplastia y colocación de una endoprótesis vascular(AU)

The case report of a former smoker is presented who (without any other history) after a stressful situation began to experience during more than 20 minutes a severe retrosternal and oppressive precordial pain irradiated to the left shoulder, accompanied by diaphoresis. Taking into account the results of the stress test and ultrasonography, cardiac catheterization was performed that allowed to diagnose an abnormality in the left coronary artery, which consisted in the birth of the anterior descending artery from right coronary artery. The obstruction of both arteries was successfully removed by angioplasty and vascular stent placement(AU)

Rosenthal fiber encephalopathy in a dog resembling Alexander disease in humans.

A young male Bernese mountain dog presented with neurologic abnormalities consisting of nonambulatory tetraparesis, generalized tremors, and depressed mental status. At necropsy only a mild enlargement of the lateral ventricles was seen. The histologic examination revealed the presence of eosinophilic deposits consistent with Rosenthal fibers (RFs) throughout the white matter of the central nervous system. There was also a marked proliferation of abnormally large astrocytes and limited myelin changes. RFs were most prominent in perivascular, subpial, and subependymal areas, where they were perpendicularly located, producing a pallisaded arrangement. Immunohistochemically, RFs were strongly positive for glial fibrillary acidic protein (GFAP), and when they were examined ultrastructurally they appeared as electron-dense amorphous masses located within the processes of astrocytes, most particularly in the perivascular feet. The histologic and immunohistochemical findings of this canine case were consistent with the published neuropathologic descriptions of Alexander disease in humans and in a few dogs, a rare condition that in humans has been shown to be caused by dominant mutations in the GFAP gene.

Ultrastructural characterization of gills in juveniles of the Argentinian Silverside, Odontesthes bonariensis (Valenciennes, 1835) (Teleostei: Atheriniformes).

An ultrastructural study was performed on the gills of juvenile Argentinian silverside, Odontesthes bonariensis. The gills are composed of two sets of four holobranchs and, in turn, each holobranch consists of a gill arch and two rows of caudolaterally projecting branchial filaments. From the dorsal and ventral surfaces of each filament, branchial lamellae radiate out as foldings of the epithelial layer. Gill rakers are present on each of the gill arches, on the anteromedial side of the arch opposite to the filaments. Gill rakers, gill arches and branchial filaments are covered by a stratified epithelium, whereas branchial lamellae essentially consist of a thin epithelial envelope containing capillaries. In the stratified epithelium, mucous cells, rodlet cells, granular cells, pavement epithelial cells and mitochondria-rich cells are identified. The thin epithelium that lines the lamellae comprises two cell types, outer and inner epithelial cells, and the capillary walls on the inside of the epithelial envelope are defined by pillar cells. The ultrastructure of all these cell types is described and our findings are discussed in light of the existing data on fish gill morphology. In the gills of juvenile Argentinian silverside is of particular interest the characteristics showed by mitochondria-rich cells, such as their arrangement in clusters of 2-3 cells and their small and depressed surface in contact with the aquatic milieu, features which strongly resemble those of euryhaline species.

Temporary inhibition of neuronal apoptosis in Aujeszky's disease virus-infected swine.

Previous studies have shown that during acute infection of the porcine trigeminal ganglia (TG), Aujeszky's disease virus (ADV)-infected neurons are protected from apoptosis induced by the virus itself and by cells of the immune system. However, TG neurons productively infected by ADV finally die and are phagocytosed by adjacent cells, a fact that leads us to speculate that the inhibition of neuronal apoptosis by ADV may be temporary rather than absolute. To address this issue we used TG and brain stem from pigs during acute infection by ADV. Infected cells were detected by immunohistochemical staining of viral antigens, whereas apoptotic cells were identified with an anti-active caspase-3 antibody, the TUNEL assay and by transmission electron microscopy. The results obtained in this study support the contention that the inhibition of neuronal apoptosis by ADV is temporary, since activation of caspase-3 could be detected in infected neurons at late stages in infection and because foci of advanced neuronophagia contained neurons exhibiting typical ultrastructural features of apoptosis.

Hemangiomatosis associated with osteolysis of the mandible in a dog resembling Gorham-Stout disease in humans.

A 6-month-old female German Shepherd Dog died as a result of profuse oral bleeding. At postmortem examination, the oral cavity showed visible roots of the right mandibular fourth premolar and first molar teeth and, in addition, they were very mobile and compressible. Radiographs showed a generalized radiolucency in the body of the right mandible, with evidence of resorption of the affected alveolar bone. Histologically, the lesion of the right mandible was characterized by the lysis of bony structures and a non-malignant proliferation of blood-filled vascular spaces lined by a single layer of well-differentiated endothelial cells. The clinical, radiographic, and histologic presentation of this dog is consistent with that associated with Gorham-Stout disease, a rare bone disorder in humans.

Squamous cell carcinoma of the oropharynx and esophagus in a Japanese bantam rooster.

Squamous cell carcinoma of the oropharynx and esophagus was diagnosed in an adult Japanese bantam rooster. Grossly, a cauliflowerlike mass with irregular edges was found involving the ventrolateral surfaces of the caudal portion of the oropharynx and cervical portion of the esophagus. The large volume of the mass almost occluded the lumen of the alimentary passage. Histologically, the tumor consisted of irregular cords of pleomorphic epithelial cells that showed a disorganized pattern of growth and invaded the adjacent tissues. Keratinized epithelial cells and moderate numbers of keratin pearls were readily observed. The mitotic index was low, and, although the tumor was locally invasive, we found no evidence of vascular invasion or metastasis.

Morphological changes in the mink area postrema during growth and under different stages of sexual activity.

The histological features of the area postrema (AP) of mink brains of both sexes were investigated at different ages and physiological conditions with light and electron microscopy. The mink AP was a twin-winged structure located at the dorsal surface of the medulla oblongata and consisted of neurons, glial cells, and both continuous and fenestrated capillaries enmeshed in a rich neuropil. The ventricular surface of the mink AP was covered by a single layer of tanycytes except at its most caudal part that was covered by a basal membrane derived from the pia mater. Supraependymal cells and intraventricular axons were also a common finding over the apical poles of tanycytes. However, our study demonstrates that the mink AP acquires the above general features at an advanced postnatal time and that, once fully developed, it undergoes morphological changes that can be directly linked to the aging process and sexual activity of the animals.

Canine distemper in a genet (Gennetta gennetta), associated with endogenous lipid pneumonia.

This report describes the histological and immunohistochemical findings in an adult male genet (Gennetta gennetta) which died a few hours after being found lying in a forest in Lugo (north-western Spain). Subpleural, yellowish, firm foci were found in the lung. Histopathological examination confirmed a diagnosis of endogenous lipid pneumonia. Microscopical lesions that gave rise to a suspicion of canine distemper virus (CDV) infection included lymphoid depletion, non-suppurative encephalitis and demyelination in the central nervous system, and the presence of inclusion bodies in renal tubules. Immunohistochemical examination was performed with the streptavidin-biotin-complex method and a monoclonal antibody against the nucleocapsid protein (NP) of CDV. Antigen was detected in epithelial, nervous and lymphoid cells in several organs. This would appear to be the first report of distemper-like infection in a genet.

Induction and inhibition of apoptosis by pseudorabies virus in the trigeminal ganglion during acute infection of swine.

We examined the ability of pseudorabies virus (PRV) to induce and suppress apoptosis in the trigeminal ganglion during acute infection of its natural host. Eight pigs were intranasally inoculated with a virulent field strain of PRV, and at various early times after inoculation, the trigeminal ganglia were assessed histologically. PRV-infected cells were detected by use of immunohistochemistry and in situ hybridization, and apoptosis was identified by in situ terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling. Light and electron microscopy was also used for morphological studies. Apoptosis was readily detected among infiltrating immune cells that were located surrounding PRV-infected neurons. The majority of PRV-infected neurons did not show morphological or histochemical evidence of apoptosis, even including those neurons that were surrounded by numerous inflammatory cells and exhibited profound pathological changes. However, neuronal virus-induced apoptosis also occurred but at a sporadic low level. These findings suggest that PRV is able to block apoptosis of infected trigeminal ganglionic neurons during acute infection of swine. Furthermore, our results also suggest that apoptosis of infiltrating inflammatory cells may represent an important viral mechanism of immune evasion.

Diagnosis of atoxoplasmosis in a canary (Serinus canarius) by histopathologic and ultrastructural examination.

Our paper describes pathologic and ultrastructural features of a canary (Serinus canarius) infected by Atoxoplasma sp. Histologically, numerous mononuclear cells were observed in intestinal mucosa, liver, and spleen. Most of these cells contained a variable number of protozoal-like organisms. These organisms were identified as Atoxoplasma sp. by ultrastructural examination of reprocessed paraffin-embedded tissues.

[Epidemiology of neurosensorial deafness in the Foral Community of Navarra]. / Epidemiología de la hipoacusia neurosensorial en la Comunidad Foral de Navarra.

Congenital deafness is a relatively frequent disorder that shows a heterogeneous aetiology. Knowledge and the control of some risk factors have decreased the incidence of acquired deafness and increased the relative importance of genetic cause. In an attempt to investigate the clinical relevance of congenital deafness and the mechanisms of prevention in our population, a clinical and genetic study of cases with neurosensorial deafness born in Navarra between 1975 and 1990 was carried out. A total of eighty-one cases were identified, giving an incidence of 0.8 per thousand. Thirty per cent of the cases showed deafness associated with defects. Cause of deafness was identified in seventy per cent of the cases with whom a detailed clinical and genetic study could be performed (n=50). Genetic factors were responsible for the disorder in more than half of these cases. The most frequent hereditary factor was of the autosomic recessive type. This was associated with a more severe form of hearing loss.

Changes of the basement membrane and type IV collagen in human skin during aging.

OBJECTIVES: To determine the relationship between skin collagen IV and basement membrane changes during aging, a total of 35 women who had been admitted for surgery, were studied. METHODS: Subjects were arranged into six age-groups (from 35 to 60 years). Skin biopsies were performed in all patients and the samples were taken from a site 6 cm above the pubic symphysis. The collagen IV content and the epithelial basement membrane were analyzed by using immunohistochemical, transmission electron microscopy and computer-assisted image analysis methods. The skin collagen IV content was measured by an image analysis program and expressed in arbitrary units of integrate optical density, and, the basement membrane thickness was expressed in nanometers. RESULTS: Type IV collagen content decreased with age after 35 years (r = -0.9561). The epithelial basement membrane thickness increased significantly with age (r = 0.98192; P < 0.01) and there is an inverse correlation between these two parameters (r = -0.990502). CONCLUSIONS: Although type IV collagen is a basement membrane component and declines with aging, the total thickness of this membrane increases, which suggests a reduction in tissue turnover.

El puente fijo realizado en el servicio protésico no especializado / Fixed bridge developed at a non-specialized prosthetic service

Se presenta un método fácil, económico y rápido de construir un puente fijo en el sector anterior, sin emplear metales preciosos y utilizando las instalaciones corrientes de un laboratorio de prótesis para acrílico(AU)