Status Epilepticus Causes Selective Regional Damage and Loss of GABAergic Neurons in the Rat Amygdaloid Complex

In human epilepsy, the amygdala is often a primary focus for seizures. To analyse the status epilepticus-induced alterations in the amygdaloid circuitries which may later underlie epileptogenesis, we studied the amygdaloid damage in kainic acid and perforant pathway stimulation models of status epilepticus in the rat. We also studied the damage to inhibitory GABAergic neurons. In both models, the medial division of the lateral nucleus, the parvicellular division of the basal nucleus and portions of the anterior cortical and medial nuclei were damaged. In the kainate model, where the seizure activity was more severe, the accessory basal nucleus, amygdalohippocampal area, posterior cortical nucleus and periamygdaloid cortex were also damaged. Two weeks after kainate-induced seizures, 56% of the GABA-immunoreactive neurons remained in the lateral nucleus ( P < 0.05) and 25% in the basal nucleus ( P < 0.01). Further analysis showed that one subpopulation of damaged GABAergic neurons was immunoreactive for somatostatin (48% remaining in the lateral nucleus, P < 0.01; 33% in the basal nucleus, P < 0.01). In the perforant pathway stimulation model, the damage to somatostatin neurons was milder. According to our data, the initial insult, such as status epilepticus, selectively damages amygdaloid nuclei. The loss of inhibition may underlie the spontaneous generation of seizures and epileptogenesis. On the other hand, many amygdaloid output nuclei (magnocellular and intermediate division of the basal nucleus, the central nucleus) remained relatively undamaged, providing pathways for seizure spread and generation of seizure-related behavioural manifestations such as motor convulsions and fear response.     

Bacterial diversity at surface water in three locations within the Baltic sea as revealed by culture-dependent molecular techniques

Diversity of culturable bacteria inhabiting the Baltic sea surface waters was studied in three separate locations. Based on electrophoretically separated whole cell proteins the number of operational taxonomic units (OTU) within each sampling location was high. Most of the OTUs were unique to single locations. Within each sampling location 8–22% of isolates belonged to a single OTU. Rarefaction analysis revealed that the bacterial community was more divergent at a polluted location than at clean areas. Also the most common OTUs were different in clean locations compared to the polluted site suggesting that both diversity and species composition of the bacterial community is greatly affected by pollution. The partial 16S rRNA gene sequences of the isolates of the most common OTUs are unique. Intragroup variation and an OTU-specific bacteriocin system was observed among the isolates of the second common OTU. The bacteriocin activity was linked to restriction fragment length polymorphism grouping, although additional variation correlating to geographic origin of isolates was observed.     

Biotransformation and bioconcentration of pyrene in Daphnia magna

Water fleas (Daphnia magna) were exposed to [14C]pyrene in the presence and absence of piperonyl butoxide (PBO), a general cytochrome P450 (CYP) inhibitor, in organic carbon-free artificial freshwater (AFW, DOC<0.2 mg l(-1)) and in natural lake water (DOC=19.9 mg l(-1)) for 24 h. The bioconcentration of total radioactivity after 24 h exposure was 50% lower in the natural lake water, indicating decreased bioavailability of pyrene by the dissolved organic matter. However, the proportions of parent compound were only ca. 12 and 19% of the total body burden in daphnids exposed in AFW and natural lake water, respectively. Therefore, the tissue concentration of the parent pyrene was not significantly different in the daphnids exposed in the two different waters. Due to extensive biotransformation the bioconcentration factor (BCF) of parent pyrene was only 16 and 23% of the BCF calculated on the basis of total radioactivity in the daphnids in AFW and natural lake water, respectively. The proportion of parent pyrene was significantly higher (over 60%) in the daphnids exposed simultaneously to PBO, which indicates the involvement of CYP monooxygenases in the biotransformation. Furthermore, increasing PBO concentration decreased the accumulation of total radioactivity in AFW but not in the natural lake water. The data demonstrate capability and importance of CYP monooxygenases in biotransformation of polycyclic aromatic hydrocarbons in D. magna.     

Binding kinetics and duration of in vivo action of novel prolyl oligopeptidase inhibitors

Prolyl oligopeptidase (POP) is a serine protease that specifically hydrolyses small peptides at the carboxyl end of the proline residue. POP has gained pharmaceutical interest, since its inhibitors have been shown to have antiamnesic properties in rat. We examined the effect of the 2(S)-substituents CN and COCH(2)OH at the P1 site of the parent inhibitors isophthalic acid 2(S)-(cyclopentanecarbonyl)pyrrolidine-l-prolyl-pyrrolidine amide and 4-phenylbutanoyl-l-prolyl-pyrrolidine and bulky 5-t-butyl group at the P2 site l-prolyl residue of the parent inhibitor 4-phenylbutanoyl-l-prolyl-pyrrolidine on the binding kinetics to the enzyme. In addition, we studied the duration of POP inhibition in the rat tissues in vivo after i.p. administration. CN and COCH(2)OH substituents at the P1 site pyrrolidine group were found to greatly increase the affinity of the inhibitor and the enzyme-inhibitor complex half-life. In addition, 5-t-butyl group at the P2 site l-prolyl residue increased the dissociation half-life of the enzyme-inhibitor complex, without much affecting the inhibitory potency. The duration of the inhibition in the rat tissues followed the inhibition kinetic properties in that the compounds with fast dissociation produced shorter inhibition in the rat tissues than the compounds with slow dissociation. The duration of POP inhibition of compounds was evidently not governed by their serum clearance. The fact that the in vivo pharmacodynamic behaviour of POP inhibitors can be predicted by their in vitro-properties may be of importance when designing therapeutically useful POP inhibitors.     

The Advia 120 red blood cells and reticulocyte indices are useful in diagnosis of iron-deficiency anemia

We have investigated the red blood cell (RBC) and reticulocyte indices of the Advia 120 hematology system in assessment of body iron stores as well as in diagnostics of iron-deficiency anemia in two separate study populations. The first study population consisted of a total of 34 apparently healthy females who were found to be anemic (Hb<125gL1) in a screening test. The anemic subjects were classified on the basis of plasma transferrin receptor (TfR) concentration into an iron-deficiency anemia group (TfR concentration 2.4mgL1, n=14) and an adequate iron stores group (TfR concentration <2.4mgL1, n=20). Another study population consisted of 95 hospital patients of whom 31 had depleted iron stores according to TfR concentration. The same population was classified further on the basis of hemoglobin value (Hb<125gL1 for females, Hb<135gL1 for males) into patients with iron-deficiency anemia (n=21) and those with anemia together with adequate iron stores (n=44). In the population of young anemic female students the percentage of hypochromic RBC (%HYPOm) had a remarkably high ROC AUC of 0.98 when evaluating the diagnostic accuracy for the distinction between the patients with iron-deficiency anemia and those with anemia and adequate iron stores. Also, among the hospitalized patients %HYPOm had the highest ROC AUC of 0.77. The diagnostic efficiency provided by the red blood cell and reticulocyte indices was considerably lower in the heterogeneous group of hospitalized patients than in the group of female students. Nevertheless, the advanced RBC and reticulocyte indices may prove to be useful tools in the evaluation of iron status and diagnosis of iron-deficiency anemia.     

Chemical crosslinking of bacteriophage phi 6 nucleocapsid proteins

phi 6 is a lipid-containing dsRNA bacteriophage of Pseudomonas syringae. Its nucleocapsid (NC) has common features with Reoviridae core particles. We report here the crosslinking of phi 6 NC proteins with cleavable 12-A span chemical crosslinker, dithiobis(succinimidyl propionate). The crosslinked complexes were analyzed in two-dimensional polyacrylamide gels or by using monoclonal antibodies to uncleaved protein complexes in one-dimensional protein gels. The NC surface protein (P8) forms a series of multimeric homopolymers. The phi 6 lytic enzyme, protein P5, is associated with P8 on the NC surface. The interior NC proteins P1 and P4, associated with the virus polymerase activity, are also in contact with the P8 shell. A P1 + P4 complex is also formed. Only one of the NC proteins (P7) did not easily form complexes with the other NC proteins. These results indicate a very closely packed P8 surface lattice with specific contacts to the internal NC proteins.     

Factor XIIIa-positive dendrocytes are increased in number and size in recurrent aphthous ulcers (RAU)

The factor XIIIa-positive (FXIIIa+) cell is a potent antigen-presenting cell, which has been described as increasing in numbers in various chronic inflammatory conditions. The purpose of this study was to investigate the distribution and frequency of FXIIIa+ cells in acute recurrent aphthous ulcer (RAU) lesions compared with induced traumatic ulcer (TU) lesions and with clinically healthy oral mucosa. Samples were labeled with polyclonal rabbit anti-human FXIIIa antibodies in avidin-biotin-peroxidase complex (ABC) staining. Most of the FXIIIa-immunoreactive cells in TUs and normal mucosa were spindle-shaped, whereas a relatively large, dendritic-like cell was predominant in RAU lesions. FXIIIa+ cells were quite frequent within mononuclear cell-rich inflammatory cell infiltrates and in perivascular areas in RAU lesions. In contrast, FXIIIa+ cells were not found in mucosal epithelium or in the neutrophil-rich areas. RAU mononuclear cell-rich inflammatory cell infiltrates appeared to have greater numbers of positively stained cells than the TU-inflammatory cell infiltrates (199±67 vs 110±31 cells/mm² p < 0.001). Overall, FXIIIa+ dendrocytes were increased in numbers, and apparently also in size, in RAU lesions (274±68/mm²) as compared lo controls (177±74/mm², p < 0.01), and to TU lesions (183±50 mm², P < 0.01). Interestingly, relatively high numbers of FXIIIa+ dendrocytes were also found in deep connective tissue in RAU sections compared with TUs (281 ±80 vs 166±57, p < 0.01). The characteristic changes in the size and shape of individual FXIIIa+ cells, their typical distribution and increase in frequency in RAU lesions indicate active involvement in the local pathogenic mechanisms. Localization to perivascular areas/inflammatory cell infiltrates would be compatible with a role in antigen presentation.