Antioxidant and glutathione-related enzymatic activities in rat sciatic nerve

The present work tries to establish the antioxidant capacity of the peripheral nervous tissue of the rat, in terms of the enzymatic activities present in this tissue that either prevent the formation of activated species as the semiquinone radical (DT-diaphorase), protect against activated oxygen species (superoxide dismutase, glutathione peroxidase), conjugate natural toxic products or xenobiotics (glutathione S-transferases, especially the activity conjugating 4-hydroxy-nonenal), or complete the glutathione system metabolism (glutathione disulfide reductase, γ-glutamyl transpeptidase). All the activities studied are lower in this tissue than they are in liver, except for γ-glutamyl transpeptidase. The relevance of the results obtained and its possible relationship with different neuropathies is discussed. It is concluded that the peripheral nervous tissue is by far less protected than the liver against oxidative damage.     

Immunology

A selection of interesting papers that were published in the two months before our press date in major journals most likely to report significant results in immunology.     

Improved intracranial lesion characterization by tissue segmentation based on a 3D feature map

Our aim was to develop an accurate multispectral tissue segmentation method based on 3D feature maps. We utilized proton density (PD), T₂-weighted fast spin-echo (FSE), and T₁-weighted spin-echo images as inputs for segmentation. Phantom constructs, cadaver brains, an animal brain tumor model and both normal human brains and those from patients with either multiple sclerosis (MS) or primary brain tumors were analyzed with this technique. Initially, misregistration, RF inhomogeneity and image noise problems were addressed. Next, a qualified observer identified samples representing the tissues of interest. Finally, k-nearest neighbor algorithm (k-NN) was utilized to create a stack of color-coded segmented images. The inclusion of T₁ based images, as a third input, produced significant improvement in the delineation of tissues. In MS, our 3D technique was found to be far superior to that based on any combination of 2D feature maps (P < 0.001). We identified at least two distinctly different classes of lesions within the same MS plaque, representing different stages of the disease process. Further, we obtained the regional distribution of MS lesion burden and followed its changes over time. Neuropsychological aberrations were the clinical counterpart of the structural changes detected in segmentation. We could also delineate the margins of benign brain tumors. In malignant tumors, up to four abnormal tissues were identified: 1) a solid tumor core, 2) a cystic component, 3) edema in the white matter, and 4) areas of necrosis and hemorrhage. Subsequent neurosurgical exploration confirmed the distribution of tissues as predicted by this analysis.     

The Organization of the Venous Spaces of the Cavernous Sinus

The study of the venous channels in the cavernous sinus in 48 sphenoid bones was performed. Thirty-eight bones were electrolyticly decalcified, subsequently embedded in gelatin, and cut in 1 mm thick slices. Microdissection of the other ten specimens complemented the analysis. Every specimen had the venous structure arranged as a plexus, however, although the channels were variable in number, form, and diameter, the two sides were quite symmetrical. Channels of smaller diameter predominated anteriorly. There was no demonstrable muscular layer in these vessels; the endothelial lining was easily visualized. Fatty tissue separated the venous channels from each other and from arteries and nerves. The distance from the carotid artery and the lateral wall increased anteriorly, but there were significant veins between these two structures in only 35% of the cases. In about one third of specimens the oculomotor nerve was placed over the carotid artery. The abducens nerve was found to be intimately related to the lateral wall without any venous channels between them in 92% of the specimens.     

Ancillary Community Pharmacy Services Provided to Older People in A Largely Rural and Ethnically Diverse Region: A Survey of Consumers in West Texas

Little is known about the quality of pharmacy services provided to the rural elderly population. This exploratory study examines rural/urban and ethnic differences in perceived access to ancillary pharmacy services among elderly people. Two telephone surveys were conducted using directory listings in West Texas to generate a longitudinal sample. Persons aged 65 years and older who were not cognitively impaired were asked to complete the survey. The number of participants in both rounds of the survey was 3,689. Seven ancillary pharmacy services were examined: delivery of medications, medication counseling, written medication information, blood pressure monitoring, blood glucose monitoring, osteoporosis screening, and immunization. The sample was stratified by county of residence (urban, rural, or frontier) and racial/ethnic background. Chi-square tests were performed to detect rural/urban and racial/ethnic differences in access to the seven ancillary services. The association between proficiency in English and access to the services was also examined. Rural residents were more likely than urban residents to report that their pharmacies provide delivery of medications, medication counseling, and immunization services, but they were less likely than their urban counterparts to report that their pharmacies provide blood pressure monitoring. Access to ancillary pharmacy services was reported as poorer by older Hispanic people compared with non-Hispanics. Deficiency in English was significantly related to inequality in reported access to ancillary pharmacy services. It is essential to consider the special needs of rural and Hispanic elderly people to ensure equitable access to ancillary pharmacy services.     

Rapadilino syndrome

We report on a boy with severe radial hypoplasia, absent thumbs and patellae, short stature, persistent diarrhea, slender nose and normal intelligence as another example of the RAPADILINO syndrome. © 1992 Wiley-Liss, Inc.     

Fetal dexamethasone exposure affects basal ornithine decarboxylase activity in developing rat brain regions and alters acute responses to hypoxia and maternal separation

Although glucocorticoids are widely used to stimulate fetal/neonatal lung function, they also interfere with cellular development in the central nervous system. Dexamethasone was administered to pregnant rats in late gestation at a dose (0.8 mg/kg) that lies just above the threshold for stimulation of lung surfactant synthesis, and the impact on ornithine decarboxylase (ODC) was evaluated in three brain regions. Dexamethasone treatment produced an initial inhibition of basal ODC activity followed by postnatal elevations, a pattern known to be associated with delays in cell replication and differentiation. Dexamethasone also interfered with the ability of the 1-day-old neonate to turn off ODC acutely in response to a 2-h period of maternal separation; as this response conserves energy in the absence of the dam, the effect of dexamethasone is maladaptive. Additionally, dexamethasone sensitized the neonatal brain to hypoxia: the acute increase of ODC associated with a 2-h exposure to 7% O2 was exacerbated in 8-day-old rats exposed to dexamethasone prenatally. These results suggest that administration of dexamethasone, in doses that promote respiratory competence, delays cell development in the central nervous system and renders the brain more vulnerable to adverse neonatal conditions, such as maternal separation or hypoxia.     

CRITERIA ADOPTED BY DENTISTS TO INDICATE THE EXTRACTION OF PERIODONTALLY INVOLVED TEETH

When dealing with patients with periodontal disease of variable severities, dentists must often choose between treating and restoring the involved tooth or indicating its extraction. Different criteria have been adopted in this decision-making process. The purpose of this study was to evaluate the criteria adopted by dentists to indicate the extraction of teeth with periodontitis. Dentists were interviewed at their private practices in three cities of the state of Rio Grande do Sul, Brazil. The evaluated criteria included severity of attachment loss, tooth mobility, furcation involvement, prosthetic planning, periodontal-endodontic lesion, possible systemic involvement due to the presence of periodontitis, referral to a periodontist for evaluation, radiographic bone loss greater than 50%, presence of extensive caries, socio-economic and cultural status of the patient, among others. The most often adopted criteria to indicate the extraction of periodontally affected teeth were the presence of mobility (37.5%), severity of attachment loss (24.3%) and radiographic bone loss greater than 50% (21.2%). The results of the present study demonstrated the difficulties faced by dentists to indicate the extraction of teeth with severe attachment loss, in addition to the establishment of an adequate prognosis. Aspects associated with the past disease were still the most often reported to indicate the extraction of teeth for periodontal reasons.