The perineuronal net in the fastigial nucleus of the rat cerebellum. A Golgi and quantitative study

Summary The morphological study of the rat fastigial nucleus with the Golgi-Rio Hortega method showed the presence of glial perineuronal nets surrounding the large neurons, but not the small ones. This perineuronal net appeared as a mesh of tenuous glial processes which covers the neuronal perikarya and proximal dendrites. The small alveolate compartments in this mesh seem to correspond to the holes for the synaptic boutons. Our results also indicate that the perineuronal net is derived from interneuronal protoplasmic and velate astrocytes.Using camera lucida drawings of this perineuronal net we have made a quantitative estimation of the size and density of synaptic boutons on these large neurons. The average numerical density of synaptic boutons was about 19 per 100 m² of the neuronal surface, the mean area of the synaptic holes being 2.5 m². Furthermore, the quantitative data evidence that about 52.5% of the neuronal surface is presumably occupied by synaptic boutons whereas the remaining 47.5% is covered by the glial processes of the perineuronal net.Semithin sections prepared from thick Golgi sections were used for the cytological study of the neurons surrounded by this glial pericellular network. The possible functional significance of the perineuronal net in the regulation of synaptic transmission in the fastigial cerebellar nucleus is briefly discussed.     

Involvement of clusterin and the aggresome in abnormal protein deposits in myofibrillar myopathies and inclusion body myositis

Myofibrillar myopathies (MM) are characterized morphologically by the presence of non-hyaline structures corresponding to foci of dissolution of myofibrils, and hyaline lesions composed of aggregates of compacted and degraded myofibrillar elements. Inclusion body myositis (IBM) is characterized by the presence of rimmed vacuoles, eosinophilic inclusions in the cytoplasm, rare intranuclear inclusions, and by the accumulation of several abnormal proteins. Recent studies have demonstrated impaired proteasomal expression and activity in MM and IBM, thus accounting, in part, for the abnormal protein accumulation in these diseases. The present study examines other factors involved in protein aggregation in MM and IBM. Clusterin is a multiple-function protein which participates in Abeta-amyloid, PrP(res) and a-synuclein aggregation in Alzheimer disease, prionopathies and a-synucleinopathies, respectively. gamma-Tubulin is present in the centrosome and is an intracellular marker of the aggresome. Moderate or strong clusterin immunoreactivity has been found in association with abnormal protein deposits, as revealed by immunohistochemistry, single and double-labeling immunofluorescence and confocal microscopy, in MM and IBM, and in target structures in denervation atrophy. Gamma-Tubulin has also been observed in association with abnormal protein deposits in MM, IBM, and in target fibers in denervation atrophy. These morphological findings are accompanied by increased expression of clusterin and gamma-tubulin in muscle homogenates of MM and IBM cases, as revealed by gel electrophoresis and Western blots. Together, these observations demonstrate involvement of clusterin in protein aggregates, and increased expression of aggresome markers in association with abnormal protein inclusions in MM and IBM and in targets, as crucial events related to the pathogenesis of abnormal protein accumulation and degradation in these muscular diseases.     

Effects of hypothermia and gender on survival and behavior after perinatal asphyxia in rats

Previous studies in rats have demonstrated that perinatal asphyxia (PA) produces long-term morphological alterations, particularly affecting hippocampus. neostriatum, and cerebral cortex. These changes were prevented by applying hypothermia during the asphyctic insult. Because these cerebral areas are involved in cognitive and motor functions, the aim of the present study was to determine whether periods of PA during normothermia or hypothermia produces long-term behavioral impairments in rats of both sexes. The cognitive and motor functions were studied using the spatial Morris water maze (MWM) task at 1.5 months, and the open field at 5 months, respectively. The present study revealed that female rats had a higher survival rate than males after PA in normothermic conditions (p < 0.014). and that hypothermia drastically prolonged the time of survival in both sexes (p < 0.001). There were no differences in learning and memory functions between groups or male and female rats when tested with MWM. Rats subjected to hypothermia treatment did not show differences in the MWM compared to controls. A lower locomotor activity in the open field test was only observed in male rats that suffered 15 and 20 min of PA in normothermia (p < 0.05). Hypothermia treatment prevented this hypoactivity. PA in females, even if severe, did not affect the motor activity. The data of both behavioral tests showed differences between sexes, i.e., the female rats learned the MWM task slower, and were more active in the open field. This work lends further support for the hypothesis that hypothermia can prevent mortality as well as long-term sequelae induced by PA.     

Occupational rhinoconjunctivitis and bronchial asthma due to Phoenix canariensis pollen allergy

We report a case of occupational bronchial asthma and rhinoconjunctivitis caused by Phoenix canariensis (PC) pollen. The canary palm is a type of palm tree, belonging to the Arecaceae family, which is widely distributed in frost-free regions as an ornamental tree. Our patient was referred because he suffered symptoms of bronchial asthma, rhinoconjunctivitis, and contact urticaria when pruning dried leaves from PC during the pollination months. The skin prick test (SPT) with a PC pollen extract was positive, as was the specific IgE to PC pollen determined by Phadezym RAST, indicating an IgE-mediated sensitization. The nonspecific bronchial provocation test (BPT) performed with methacholine disclosed a mild bronchial hyperreactivity, and specific BPT with PC pollen elicited an immediate fall of 25% in FEV₁ with respect to baseline. On RAST inhibition studies, a significant cross-reactivity was found between PC pollen and date palm ( P. dactylifera ) pollen. These results suggest that PC pollen could be a potential allergen in PC-growing areas.     

Rapid Screening Tests for Determining In Vitro Susceptibility of Herpes Simplex Virus Clinical Isolates

The susceptibility of human herpes simplex virus (HSV) to acyclovir (ACV) was determined with the use of a single dose of the drug (1 and 2 μg of ACV per ml for HSV-1 and HSV-2, respectively) in two rapid assays: a rapid cytopathic effect inhibitory assay (Rapid CIA) and a rapid dye uptake assay (Rapid DUA). These tests allow the simultaneous determination of virus titer and susceptibility to ACV at a determined viral concentration (100 50% tissue culture infective doses and 100 50% dye uptake units). These tests were compared with a conventional susceptibility assay (dye uptake assay) and showed similar results. Indeterminate results with the Rapid CIA appeared in 3 of 30 samples. With the use of both Rapid CIA and Rapid DUA, we were able to determine the susceptibility of 100% of the isolates. The rapid tests, unlike conventional assays, are able to provide susceptibility results within 3 days after the virus has been isolated from a clinical specimen and could thus play a direct role in therapeutic decisions.     

Genetic linkage of the tricho-dento-osseous syndrome to chromosome 17q21

Tricho-dento-osseous syndrome (TDO), MIM# 190320, is transmitted as a highly penetrant autosomal dominant trait that is characterized by variable clinical expression. The principal clinical features include kinky/curly hair in infancy, enamel hypoplasia, taurodontism, as well as increased thickness and density of cranial bones. Possible genetic linkage has been reported for TDO with the ABO blood group locus, but the gene defect remains unknown. We have identified four multiplex families (n = 63, 39 affected, 24 unaffected) from North Carolina segregating TDO. We previously have excluded a major locus for TDO in the ABO region for these families. Utilizing a genome-wide search strategy, we obtained conclusive evidence for linkage of the TDO syndrome locus to markers on chromosome 17q21 (D17S791, Z max = 10.54, Theta = 0.00) with no indication of genetic heterogeneity. Multipoint analysis suggests the TDO locus is located in a 7 cM chromosomal segment flanked by D17S932 and D17S941. This finding represents the first step towards isolation and cloning of the TDO gene. Identification of this gene has important implications for understanding normal and abnormal craniofacial development of hair, teeth and bone.      

Antimicrobial resistance of Shiga toxin (verotoxin)-producing Escherichia coli O157:H7 and non-O157 strains isolated from humans, cattle, sheep and food in Spain

A total of 722 Shiga toxin-producing Escherichia coli (STEC) isolates recovered from humans, cattle, ovines and food during the period from 1992 to 1999 in Spain were examined to determine antimicrobial resistance profiles and their association with serotypes, phage types and virulence genes. Fifty-eight (41%) out of 141 STEC O157:H7 strains and 240 (41%) out of 581 non-O157 STEC strains showed resistance to at least one of the 26 antimicrobial agents tested. STEC O157:H7 showed a higher percentage of resistant strains recovered from bovine (53%) and beef meat (57%) than from human (23%) and ovine (20%) sources, whereas the highest prevalence of antimicrobial resistance in non-O157 STEC was found among isolates recovered from beef meat (55%) and human patients (47%). Sulfisoxazole (36%) had the most common antimicrobial resistance, followed by tetracycline (32%), streptomycin (29%), ampicillin (10%), trimethoprim (8%), cotrimoxazole (8%), chloramphenicol (7%), kanamycin (7%), piperacillin (6%), and neomycin (5%). The multiple resistance pattern most often observed was that of streptomycin, sulfisoxazole, and tetracycline. Ten (7%) STEC O157:H7 and 71 (12%) non-O157 strains were resistant to five or more antimicrobial agents. Most strains showing resistance to five or more antimicrobial agents belonged to serotypes O4:H4 (4 strains), O8:H21 (3 strains), O20:H19 (6 strains), O26:H11 (8 strains eae-beta1), O111:H- (3 strains eae-gamma2), O118:H- (2 strains eae-beta1), O118:H16 (5 strains eae-beta1), O128:H- (2 strains), O145:H8 or O145:H- (2 strains eae-gamma1), O157:H7 (10 strains eae-gamma1), O171:H25 (3 strains), O177:H11 (5 strains eae-beta1), ONT:H- (3 strains/1 eae-beta1) and ONT:H21 (2 strains). Interestingly, most of these serotypes, i.e., those indicated in bold) were found among human STEC strains isolated from patients with hemolytic uremic-syndrome (HUS) reported in previous studies. We also detected, among non-O157 strains, an association between a higher level of multiple resistance to antibiotics and the presence of the virulence genes eae and stx(1). Moreover, STEC O157:H7, showed an association between certain phage types, PT21/28 (90%), PT23 (75%), PT34 (75%), and PT2 (54%), with a higher number of resistant strains. We conclude that the high prevalence of antimicrobial resistance detected in our study is a source of concern, and cautious use of antibiotics in animals is highly recommended.