Computed anatomical modelling of the optic pathway and oculomotor system using magnetic resonance imaging.

This study presents a computer-based tool for three-dimensional (3D) visualization of the optic pathway and oculomotor system using 3D high-resolution magnetic resonance imaging (MRI) datasets from a healthy subject. The 3D models were built as wireframe grids co-registered with MRI sections. First, 3D anatomical models were generated of the visual pathway from the eyeball to the primary visual cortex and of the cranial oculomotor nerves from the brain stem to the extrinsic eye muscles. Second, a graphical user interface allowed individual and group visualization, translation, rotation and zooming of the 3D models in different spatial positions simultaneously with MRI orthogonal cut planes. Educational and clinical applications are also discussed.

[Recurrent acute liver toxicity from intravenous methylprednisolone]. / Toxicidad hepática recurrente secundaria a metilprednisolona intravenosa.

Adverse drug reactions (hepatotoxicity) are a frequent cause of acute liver injury with a wide clinical and histological spectrum. An early recognition of drug-related liver disease has been considered essential in clinical practice due to potential risks. In most cases exposure discontinuation improves the clinical picture.Steroids are used in a variety of clinical settings. However, intravenous steroids have rarely been associated with hepatotoxicity. We report the case of a middle-aged woman with multiple sclerosis who received a bolus of methylprednisolone on three occasions for the management of relapsing disease, with the development of repeated episodes of elevated liver enzymes after corticoid administration. In the third episode a liver biopsy was performed, which showed acute hepatitis with bridging necrosis; such histological picture has not been described before in patients treated with intravenous steroids.

[Identification of the allergenic taxa of pollen in patients with pollinosis to determine the risk season]. / Identificación de los taxones de pólenes alergénicos en pacientes polínicos para conocer la temporada de riesgo.

BACKGROUND: Determining the risk season for the presence of pollen in the atmosphere aids primary care physicians in the diagnosis and treatment of allergic diseases. Our objective was to identify the taxa of pollen that cause allergic rhinoconjunctivitis in a sample of patients from a health center who presented seasonal symptoms. METHODS: We designed an observational, cross-sectional, non-randomized study to be carried out in the Cazoña Health Center in Santander, Spain. We selected 30 volunteers of both sexes, aged between 13 and 69 year old, who suffered seasonal rhinoconjunctivitis symptoms and who had always lived in Santander. Patients underwent skin-prick tests with the 25 pollen extracts routinely used in Spain, house dust mite (HDM), cat dander and Alternaria extracts by means of the Prick-Film system. The test result was expressed as the percentage of the papule area caused by histamine. Measurement was performed by scanning the copied papule area with the Prick-Scan program for PC. RESULTS: All patients were positive to grass pollen, 26 % were sensitized to grass pollen only and 23 % were also sensitized to other non-pollen allergens. Twenty-seven percent tested positive to Plantago, 20 % to Quercus and 13 % to Morus; the remaining pollen extracts were positive in less than 10 %. Fifty-six percent of the patients were positive to HDM and 6 % to cat dander. CONCLUSIONS: A warning period for pollinosis patients in the city of Santander can be defined. In our case, the important period is the grass pollen season, since the remaining pollen taxa sensitized few patients. Most of our patients were also sensitized to HDM.

Dopaminergic modulation of nNOS expression in the pituitary gland of male rat.

Nitric oxide is an unconventional transmitter since it is not transported and released by exocytosis. In the pituitary gland, nitric oxide is locally synthesised by gonadotroph and folliculo-stellate cells. Dopamine, the principal central inhibitory signal in prolactin release, may exert its inhibitory effects by stimulation of nitric oxide production. However, the effects of dopaminergic modulation on nitric oxide-producing pituitary cells have not been analysed. Therefore, we examined the effects of intraventricular administration of the dopamine antagonist haloperidol (40 microg) on the pituitary expression of neuronal nitric oxide synthase (nNOS) in male adult rats. In untreated and control animals, nNOS-positive cells were very similar. Two types of nNOS-positive cells appeared in the pars distalis: round or polygonal cells and stellate cells. Although some isolated cells were found, the nNOS-positive cells commonly appeared grouped in clusters close to blood vessels. nNOS immunoreactivity appeared as a uniform staining throughout the cytoplasm, including cell prolongations. The number and size of nNOS-expressing cells in the pituitary gland decreased significantly after treatment with haloperidol (p<0.01). To evaluate the potential direct effect of dopamine on pituitary cells, pituitary monolayer cultures were treated with dopamine during a time-course of 12 h. Our in vitro studies revealed that dopamine increases the percentage of nNOS-positive cells and augments cellular area (p<0.05). These results demonstrate that: (1) treatment of rats in vivo with a dopamine antagonist significantly decreases expression of nNOS in the pituitary and (2) in vitro dopamine exerts a direct effect on pituitary cultures by increasing nNOS-positive cells. Thus, these findings suggest that dopamine may function as a physiological stimulator of nNOS expression in the rat pituitary gland.

Characterization of GFAP expression and cell proliferation in the rat median eminence following hypophysectomy.

To analyze whether the reorganization of the rat median eminence after hypophysectomy might be related to changes in glial fibrillary acidic protein (GFAP)- and cellular proliferation, the distribution of cells immunoreactive for GFAP and the proliferation rate of such cells were analyzed at 20, 40 and 60 days posthypophysectomy. For this study, four rostro-caudal regions of the median eminence were differentiated: the retrochiasmatic, preinfundibular, infundibular and postinfundibular regions. In each of these regions, three layers were studied: the ependymal, the internal and the external. At 20 and 40 days after hypophysectomy, significant increases in cellular proliferation affecting all three layers studied in the preinfundibular and infundibular regions were found. At the same time points, increases in GFAP expression were also observed. However, after 60 days, GFAP and proliferative cellular nuclear antigen (PCNA) expression decreased. Although variations of PCNA and GFAP levels were evident, no colocalisation of PCNA and GFAP was found in the cells of the median eminence in untreated or hypophysectomized rats when sections were analyzed by double immunohistochemical staining. Our results suggest that reorganization of median eminence involves alterations (or modulation) of GFAP-immunoreactive cells together with a proliferation of cells that are not GFAP-immunoreactive. This study also demonstrates that this reorganization is completed within the first two months after hypophysectomy.

Crystalloid architecture of a sialolith in a minor salivary gland.

A sialolith from a minor salivary gland of the mucosa of the upper lip was studied morphologically and analytically. Under stereoscopic microscopic visualisation, no core or any concentric laminar structure was found in the sialolith and it had a transparent glassy appearance. Scanning electron microscopy revealed differences between the internal structure of the sialolith and its external structure. No microbes were observed but some mineralized inclusion bodies were seen. X-ray diffraction indicated the absence of inorganic crystals in the sialolith, while energy dispersive x-ray microanalysis revealed a high content of S followed by Ca, Si and Na and little and scarce P on the fracture surface, with S, Na, Ca and P being distributed throughout the external coating of the sialolith. The results suggest that the sialolith was young and consisted of a crystalloid body with an incipient coating undergoing calcification.

Cell proliferation and apoptosis of thyroid follicular cells are involved in the involution of experimental non-tumoral hyperplastic goiter.

To assess the involvement of cellular inhibition and the appearance of apoptosis in regression of the hyperplastic thyroid gland towards normality, an experimental design was used to elicit non-toxic goiter by inducing hyperplastic goiter in rats by treatment with methimazole. We performed a morphological and PCNA immunocytochemical study together with in situ end labelling with bromodeoxyuridine in thyroid glands of rats receiving methimazole in their drinking water over 21 days after which they were allowed a recovery period of 0, 12, 24, 36, 48 and 72 h and 7, 14, 21 and 44 days. Serum T3 and T4 levels were found to be very low in the methimazole-treated animals although they increased after the goitrogenic compound had been withdrawn. Inhibition of cell proliferation and the burst of apoptosis play important roles in the regression of hyperplastic goiter in rats. Cell proliferation, which was strongly stimulated during goiter, fell significantly at 24 h, thereafter decreasing gradually as the recovery period progressed. Isolated cases of thyrocyte necrosis were observed ultrastructurally. Light and transmission electron microscopy revealed the existence of thyroid apoptosis with respect to the development of the study over time. Most apoptotic thyrocytes became detached from the follicular epithelium and later underwent cellular degeneration in the follicular lumen. The remaining apoptotic cells retracted their cytoplasm, lost contact with the follicular lumen and became located at the base of the follicles. The percentage of apoptosis showed that during the first week of thyroid involution apoptosis was already present but with low percentages while maximum values were attained at 21 days of survival. Our results suggest that, in the rat, during the return of thyroid follicular cells to normality after methimazole-induced hyperplastic goiter a balance arises between proliferation and cell death and that this balance is due to the inhibition of cellular proliferation and, secondarily, to the appearance of apoptosis, which becomes particularly evident towards the end of the first week after withdrawing the goitrogenic agent.

Coexistence of NADPH-diaphorase with tyrosine hydroxylase in hypothalamic magnocellular neurons of the rat.

The presence and distribution of NADPH-diaphorase (ND) neurons as well as tyrosine hydroxylase-immunoreactive (TH) neurons in the hypothalamus are well established. Previous studies have shown the coexistence of ND with neuroactive substances such as calbindin, somatostatin, vasopressin and oxytocin in neurons of this region of the brain. As the tópographical patterns of distribution of ND and TH coincide in many cases, the aim of this study was to determine the possible coexistence of both substances in the main hypothalamic magnocellular nuclei of the albino rat. Histochemical-immunocytochemical double labelling was employed on the same sections as well as a morphometric study. NADPH-diaphorase and tyrosine hydroxylase neurons were observed in all the nuclei under study (supraoptic, paraventricular and accessory nuclei), although most neurons showing the coexistence of both substances were mainly located in the supraoptic nucleus, isolated neurons with double labelling being found in the magnocellular parts of the paraventricular nucleus and in some of the accessory nuclei. Although both substances have previously been shown to be modified in hypothalamic neurons after osmotic stimuli, the range of functions of ND in the CNS is only beginning to be understood. Further studies are needed to elucidate the functional role that ND/TH neurons play in the nervous system.

A three-dimensional virtual model of the head generated from digitalized CT or MR images for anatomical-radiological and neurosurgical evaluations.

A computer-generated virtual model has been developed that reconstructs the head in three dimensions from digitalized images obtained with magnetic resonance and computerized tomography. Through programming and the use of commercial graphic animation software, we have developed the whole process of the rotation of the head on different spatial planes. The procedure permits multidirectional anatomical sections to be made on the structure of the head, providing a true dynamic and user-friendly anatomical-radiological atlas. The system serves as a virtual model for the localization of an ideal surgical approach to any lesion thus avoiding possible neurological lesions.

Morphological findings of an interrelationship among the neurosecretory axons of the neural lobe of the hypophysis.

In order to establish whether osmotic stimuli induce variations in the contact regions among neurosecretory axons of the neural lobe of the hypophysis, adult Sprague-Dawley rats of both sexes were treated with furosemide, a diuretic drug. Contacts between adjacent membranes with no condensations of the axolemma but increase in their osmiophilia were observed. After treatment with furosemide interaxonal contacts were significantly increased (p < 0.01, in relation to control animals). Additionally, following treatment with furosemide, axo-axonic synapses among the axons of the neural lobe were found. These findings suggest the existence of interactions among activated neurosecretory axons of the neural lobe of the adult rat.

Changes in the neurosecretory axons of the neural lobe of the hypophysis of rats treated with met-enkephalin. An ultrastructural study.

Following administration of met-enkephalin into the third ventricle of rats of both sexes, an ultrastructural-morphometric study was carried out of the neural lobe of the hypophysis, comparing the results with those obtained in untreated animals, controls (injected intraventricularly with distilled water) and animals previously receiving naloxone intraperitoneally. In the untreated and control animals, both males and females, there was a high percentage (about 70%) of neurosecretory axons considered to have a normal morphology; after met-enkephalin administration, this percentage decreased and was accompanied by a rise (slightly more pronounced in the females) in the percentage of degranulated axons and a slight rise in axons with a morphology indicative of regenerative and degenerative phases. Previous administration of the opiate antagonist naloxone led to a rise in the number of axons in the degenerative phase with respect to the other groups of animals; this occurred in both sexes.

Repercussion of craniopharyngioma on the morphology of the rostral wall of the III ventricle. A combined TEM and SEM study.

Using a combined scanning and electron microscope technique, the repercussion on the rostral wall of the III ventricle in a patient affected with a retrochiasmatic craniopharyngioma with growth in the ventricular direction were analysed. The apical surface of the ependymocytes was found to be free of cilia, although there were numerous microvilli. The most striking finding appreciated with the scanning electron microscope was the presence of bulbous protrusions towards the lumen of the ventricle; these were formed of cells with shapes, sizes and surface characteristics different from the rest of the ependyma, which appeared flattened. The ultrastructural study revealed the presence of large numbers of filaments and junction complexes both in the ependymal and subependymal cells. Additionally, the protruded zones corresponded to areas showing different degrees of cellular disorganization.

Immunohistochemical-morphometric study of the LH-adenohypophyseal cells following chronic treatment with met-enkephalin.

In order to test the possible effect of chronic treatment with met-enkephalin upon the LH-adenohypophyseal cells, an immunohistochemical-morphometric study was carried out in rats of both sexes receiving a daily dose of 40 micrograms of met-enkephalin intramuscularly over 15 days. Following the administration of the opioid, a drastic decrease in the cellular, cytoplasmic and nuclear areas when compared to the normal and control animals was detected. Morphologically, the main finding in males was the appearance of irregularly-shaped pseudovacuolated cells. On the other hand, in females a decrease in the intensity of reaction was found. These results strongly suggest a decrease in the activity of the LH-adenohypophyseal cells following chronic administration of met-enkephalin.

Topographic distribution and quantitative analysis of retrograde-labelled cells in the substantia nigra following administration of fluoro gold in the caudate putamen nucleus.

The organization of the efferent projections of the substantia nigra following the injection of 0.4 microliters of 2% Fluoro Gold into the caudate-putamen nucleus of rats of both sexes was studied. After a survival period of 72 h, the greatest number of labelled cells was visualized in the substantia nigra, with lower numbers in adjacent structures (ventral tegmental area, zona incerta and medial lemniscus). The cells featured an intensely fluorescent gold-coloured soma and were varied in shape (round or oval); short sinuous projections arose out of them, corresponding to the dendrites and axons of the neurons. In the statistical study, no significant differences were observed between males and females. A similar pattern of distribution was found ranging from the rostral to the caudal regions of the substantia nigra, occupying the whole of the extent of the substantia nigra; this distribution was most predominant in the rostro-caudal transition of the pars compacta of the substantia nigra.

Morphometric analysis of the hypoactivity of FSH-immunoreactive cells in estrogen-primed male rats.

In order to evaluate the repercussions of estradiol treatment on the morphology and activity of FSH-producing cells, an immunocytochemical and morphometric study was carried out in male rats treated chronically with estradiol, relating those findings to serum FSH levels at the time of sacrifice. Chronic administration of estradiol led to a decrease (p < 0.01) in serum hormone levels that was accompanied by a marked decrease in cellular size (p < 0.01) due to a decrease in nuclear and cytoplasmic area. Our findings suggest for the adult male rat an inhibitory effect on the synthesis and release of FSH following testicular atrophy induced by treatment with estradiol.

Combined TEM and SEM analysis of the rostral wall of the human III ventricle.

A combined morphological study using transmission and scanning electron microscopy was carried out on the central zone of the rostral wall of the III ventricle from a sample taken during the operation of a patient with a retrochiasmatic craniopharyngioma. Under the scanning electron microscope, the apical cell wall of the ependymocytes generally appeared folded and lack in cilia, but with numerous microvilli developed to different extents. The flat surface cells were scarce and were polygonal in shape and limited by 3-7 prominent edges. Ultrastructural analysis revealed the existence of several types of ependymocytes and subependymal epithelial cells arranged in different layers; in both layers the presence of abundant neurofilaments and intercellular junctions was striking.

Ultrastructural and morphometric changes in somatotropic cells following intraventricular administration of Met-enkephalin to rats.

An ultrastructural and morphometric study of Kurosumi et al. (1986) on type 1 GH cells in adult Sprague-Dawley rats, after the intraventricular administration of Met-enkephalin, with or without prior intraperitoneal administration of naloxone, was carried out and then compared to the same cellular type of untreated animals and of animals intraventricularly treated with distilled water, used as controls. The study demonstrated an increase of cellular (p < 0.05) and nuclear (p < 0.05) areas, an enlargement and dilation of the cisternae of the Golgi complex, with an increase in the Golgi area (p < 0.01) and the immature granules (p < 0.01); a greater development of the rough endoplasmic reticulum and an increase in the number of exocytosis (p < 0.01) and, only in male rats, an increase in the mature secretory granules (p < 0.01). The prior administration of naloxone prevented the appearance of these changes and also produced an increase (p < 0.01) of the organelles involved in the crinophagic phenomenon. These results suggest that the opioids play a modulating role, stimulating the synthesis and secretion of GH, which affects the ultrastructural features of the hypophyseal GH cells.

Morphometric changes in GH-immunoreactive adenohypophyseal cells induced by intraventricular administration of colchicine to adult rats.

In order to elucidate whether the gender differences observed in the somatotropic cells of adult rats are mediated by hypothalamic neuropeptides, a morphometric analysis was made of the GH-immunoreactive cells of adult rats treated intraventricularly with colchicine. The morphometric and morphological findings obtained were correlated to the basal serum levels of GH at the time of sacrifice. Treatment with colchicine was seen to increase serum GH levels; this increase was accompanied by an increase in the intensity of the reaction of the GH-cells and, morphometrically, an increase in their size due to an increase in the nuclear area, but with no significant changes in the cytoplasmic area. The results suggest that in the absence of somatostatin and GRF the basal release of GH is elevated in a similar fashion in both sexes, in turn suggesting that gonadal steroids might act at hypothalamic level on the release of somatostatin and, indirectly, on the intracellular pool of GH and hormonal secretion.

Sex-specific response of the vasopressin-reacting neurons of the paraventricular nucleus of the rat hypothalamus following chronic administration of met-enkephalin.

Using the peroxidase-antiperoxidase immunocytochemical technique, a morphometric study of the magnocellular neurons of the Paraventricular nucleus of the rat hypothalamus, reactive to specific anti-vasopressin rabbit serum, was made. Following systemic and chronic administration of met-enkephalin the number of immunoreactive neurons was higher, especially in females. Additionally, in the females, it was possible to observe an increase in the immunoreactivity and the presence of well-stained fibres. These findings suggest, especially in females, a blockage in the release of vasopressin, facilitating its immunocytochemical visualization.