Multimeric and trimeric subunit SP-D are interconvertible structures with distinct ligand interaction

Surfactant protein-D (SP-D) is a calcium dependent lectin in the innate immune system that facilitates clearance of microbes. The protein is associated with mucosal surfaces, and also found in bronchoalveolar lavage, serum and amniotic fluid. Human SP-D includes trimeric subunits and multimeric assemblies of trimeric subunits, which are stabilized by N-terminal interchain disulfide crosslinks. An N-terminal structural polymorphism (Met11Thr) and associated O-glycosylation are previously shown accompanied by incomplete multimerization and with a relative low proportion of multimeric Thr11 SP-D compared to Met11 SP-D. Multimerization has proven important for enhancement of microbial phagocytosis.In the present study defined multimeric forms of Met11Thr SP-D were isolated from human amniotic fluid. Implementation of ManNAc-affinity chromatography allowed high recovery of natural trimeric SP-D subunits. However, affinity chromatography increased the relative proportion of multimers at the expense of natural trimeric subunits. Multimeric SP-D partially disassembled to form trimeric subunits. The resulting distribution of structural forms was independent of the Met11Thr genotype. Trimeric and multimeric SP-D appeared with distinct patterns of disulphide crosslinking, which partly changed according to interconversion between the structural forms. Solid phase assays demonstrated that trimeric SP-D subunits showed greater binding to LPS and PGN, but lower binding to mannan and LTA, than SP-D multimers. Trimeric SP-D subunits also showed greater binding to endogenous lipoproteins: LDL, oxLDL, and HDL, than multimeric SP-D. In conclusion, purified trimeric and multimeric SP-D represent separate and only partly interconvertible molecular populations with distinct biochemical properties.     

Cochlear ossification in patients with profound hearing loss following bacterial meningitis

The suitability of an air-exposed culture model consisting of a collagen matrix was investigated for constructing an advancing front (AF) of human middle ear epithelium (MEE) and meatal epidermis (ME). Three different culture settings were used: ( i ) MEE; ( ii ) ME; and ( iii ) AF (MEE+ME). Small tissue biopsies were placed on a fibroblast-populated collagen matrix and grown at the air-liquid interface. After 3 weeks of culture, the MEE and ME outgrowth was differentiated. Light, scanning electron and transmission electron microscopy showed no visible differences compared to native MEE and ME. Cytokeratin 8 and cytokeratin 10 expressions were comparable to the expression seen in the native MEE and ME tissues. Proliferation, which was demonstrated by the expression of Ki-67, was present in the basal layers of cultured MEE and ME. A double layer of cells in which the ME covered the MEE formed the AF. In the AF, the MEE and ME showed the same morphological and immunohistochemical characteristics as in their native tissues. The results of the study show that this in vitro system is a well-defined model system offering the possibility to study the effects of external stimuli on the different epithelia of the AF involved in the pathogenesis of cholesteatoma.     

Expression of glutamine synthetase and glutamate dehydrogenase in the latent phase and chronic phase in the kainate model of temporal lobe epilepsy

It has been suggested that astrocytic glutamate release or perturbed glutamate metabolism contributes to the proneness to epileptic seizures. Here we investigated whether astrocytic contents of the major glutamate degrading enzymes glutamine synthetase (GS) and glutamate dehydrogenase (GDH) decreases on moving from the latent phase (prior to seizures) to the chronic phase (after onset of seizures) in the kainate (KA) model of temporal lobe epilepsy. Western blotting and immunogold analysis of hippocampal formation indicated similar levels of GDH in the latent and chronic phases of KA injected rats and in corresponding controls. In contrast, the level of GS was increased in the latent phase compared with controls, as assessed by Western blots of whole hippocampal formation and subregions. The increase in GS paralleled that of glial fibrillary acidic protein (GFAP). Compared with the latent phase, the chronic phase revealed a lower level of GS (approaching control levels) but an unchanged GFAP content. The decrease in GS from latent to chronic phase was significant in whole hippocampal formation, dentate gyrus and CA3. It is concluded that kainate treated rats show an initial increase in GS, pari passu with the increase in GFAP, and a secondary decrease in GS that is not accompanied by a similar loss of GFAP. In a situation where glutamate catabolism is in high demand the secondary reduction in GS level may be sufficient to contribute to the seizure proneness that develops between the latent and chronic phases.     

Cross-reactivity pattern of rash from current aromatic antiepileptic drugs

We have investigated cross-reactivity of rash among the current aromatic antiepileptic drugs, particularly between the new and the traditional compounds. A retrospective survey of medical records concerning all aromatic antiepileptic drug (AED) treatment in consecutive adult patients with epilepsy was performed. Altogether 663 patients were included comprising 2567 exposures to AEDs. Skin reactions occurred in 93 patients and sequential rashes related to aromatic drugs in 17. Phenytoin (PHT), carbamazepine (CBZ) and oxcarbazepine (OXC) caused rashes in the range of 27-35% in patients with a history of another AED-related rash, whereas lamotrigine (LTG) caused another rash in 17%. A history of an AED-related rash was significantly associated with reactions to PHT, CBZ, and OXC (p<0.001). The association was only borderline significant for LTG (p=0.05). Nevertheless, the occurrence was consistently increased in all subgroups with reactions to other AEDs. A CBZ rash was not significantly associated with an LTG reaction, and vice versa, but the number of patients was limited. Less than one third of patients with a CBZ rash also reacted to OXC. No evidence for increased severity of sequential rashes was found. Clinicians should be aware of the cross-reactivity of the aromatic AEDs regarding cutaneous adverse events, as well as their differences in this respect. LTG appears to be involved in cross-reactions less often than CBZ, OXC and PHT.     

Assessment of cognitive function,structural brain changes and fatigue 6 months after treatment of neuroborreliosis

Journal of Neurology - Complete recovery after adequately treated neuroborreliosis is common, but studies report that some patients experience persistent symptoms like self-reported cognitive...     

Olanzapine, but not aripiprazole, weight-independently elevates serum triglycerides and activates lipogenic gene expression in female rats

Metabolic adverse effects such as weight gain and dyslipidaemia represent a major concern in treatment with several antipsychotic drugs, including olanzapine. It remains unclear whether such metabolic side-effects fully depend on appetite-stimulating actions, or whether some dysmetabolic features induced by antipsychotics may arise through direct perturbation of metabolic pathways in relevant peripheral tissues. Recent clinical and preclinical studies indicate that dyslipidaemia could occur independently of weight gain. Using a rat model, we showed that subchronic treatment with olanzapine induces weight gain and increases adipose tissue mass in rats with free access to food. This effect was also observed for aripiprazole, considered metabolically neutral in the clinical setting. In pair-fed rats with limited food access, neither olanzapine nor aripiprazole induced weight gain. Interestingly, olanzapine, but not aripiprazole, induced weight-independent elevation of serum triglycerides, accompanied by up-regulation of several genes involved in lipid biosynthesis, both in liver and in adipose tissues. Our findings support the existence of tissue-specific, weight-independent direct effects of olanzapine on lipid metabolism.