Brain Region–Specific Alterations in the Gene Expression of Cytokines,Immune Cell Markers and Cholinergic System Components during Peripheral Endotoxin–Induced Inflammation

Inflammatory conditions characterized by excessive peripheral immune responses are associated with diverse alterations in brain function, and brain-derived neural pathways regulate peripheral inflammation. Important aspects of this bidirectional peripheral immune–brain communication, including the impact of peripheral inflammation on brain region–specific cytokine responses, and brain cholinergic signaling (which plays a role in controlling peripheral cytokine levels), remain unclear. To provide insight, we studied gene expression of cytokines, immune cell markers and brain cholinergic system components in the cortex, cerebellum, brainstem, hippocampus, hypothalamus, striatum and thalamus in mice after an intraperitoneal lipopolysaccharide injection. Endotoxemia was accompanied by elevated serum levels of interleukin (IL)-1β, IL-6 and other cytokines and brain region–specific increases in Il1b (the highest increase, relative to basal level, was in cortex; the lowest increase was in cerebellum) and Il6 (highest increase in cerebellum; lowest increase in striatum) mRNA expression. Gene expression of brain Gfap (astrocyte marker) was also differentially increased. However, Iba1 (microglia marker) mRNA expression was decreased in the cortex, hippocampus and other brain regions in parallel with morphological changes, indicating microglia activation. Brain choline acetyltransferase (Chat ) mRNA expression was decreased in the striatum, acetylcholinesterase (Ache) mRNA expression was decreased in the cortex and increased in the hippocampus, and M1 muscarinic acetylcholine receptor (Chrm1) mRNA expression was decreased in the cortex and the brainstem. These results reveal a previously unrecognized regional specificity in brain immunoregulatory and cholinergic system gene expression in the context of peripheral inflammation and are of interest for designing future antiinflammatory approaches.     

Balancing selection,sexual selection and geographic structure in MHC genes of Great Snipe

Signatures of balancing selection are often found when investigating the extremely polymorphic regions of major histocompatibility complex (MHC) genes, and it is generally accepted that selective forces maintain this polymorphism. However, the exact nature of the selection is controversial. Theoretical studies have mainly focused on overdominance and/or frequency dependent selection while laboratory studies have emphasised the role of mate choice. Empirical field data, on the other hand, have been relatively scarce. Previously we have found that geographic structure in MHC class II genes of the Great Snipe (Gallinago media) is too pronounced to be explained by neutral forces alone. Here we test the hypothesis that sexual selection on MHC alleles may be influencing this geographic structure between mountain and lowland populations. We found evidence of balancing selection acting on MHC genes in the form of a higher rate of amino-acid changing substitutions compared to silent substitutions in the peptide binding regions. Not only natural selection but also sexual selection may influence MHC polymorphism in this bird because certain MHC alleles have been found to be associated with higher male mating success. Contrary to predictions from negative frequency dependent selection, males carrying locally rare alleles did not have a mating advantage. Instead, the mating success of alleles in a mountain population was positively correlated to their relative frequency in the mountains compared to the lowlands, implying that locally adapted MHC alleles may also be favoured by sexual selection.     

A monoclonal antibody against PDGF B-chain inhibits PDGF-induced DNA synthesis in C3H fibroblasts and prevents binding of PDGF to its receptor

A monoclonal antibody (MAb 6D11) against platelet-derived growth factor (PDGF) was studied. We found that the MAb 6D11 in concentrations equimolar to PDGF blocked the [3H]thymidine incorporation in C3H/10T1/2 C18 fibroblasts stimulated by PDGF B-B and PDGF A-B. This inhibition was overcome by high doses of PDGF. The [3H]thymidine incorporation stimulated by other growth factors (aFGF, bFGF and bombesin) was not inhibited by the antibody. The MAb 6D11 blocked receptor binding of PDGF B-B, but not PDGF A-A. These findings suggest that the MAb 6D11 abolishes PDGF-induced DNA synthesis by blocking PDGF receptor binding. In this communication we demonstrate an isoform-specific monoclonal antibody against PDGF.     

The chemokine and scavenger receptor CXCL16/SR-PSOX is expressed in human vascular smooth muscle cells and is induced by interferon gamma

Atherosclerosis is an inflammatory disease that is characterised by the involvement of chemokines that are important for the recruitment of leukocytes and scavenger receptors that mediate foam cell formation. Several cytokines are involved in the regulation of chemokines and scavenger receptors in atherosclerosis. CXCL16 is a chemokine and scavenger receptor and found in macrophages in human atherosclerotic lesions. Using double-labelled immunohistochemistry, we identified that smooth muscle cells in human lesions express CXCL16. We then analysed the effects of IFN-gamma, TNF-alpha, IL-12, IL-15, IL-18, and LPS on CXCL16 expression in cultured aortic smooth muscle cells. IFN-gamma was the most potent CXCL16 inducer and increased mRNA, soluble form, membrane form, and total cellular levels of CXCL16. The IFN-gamma induction of CXCL16 was also associated with increased uptake of oxLDL into these cells. Taken together, smooth muscle cells express CXCL16 in atherosclerotic lesions, which may play a role in the attraction of T cells to atherosclerotic lesions and contribute to the cellular internalisation of modified LDL.     

Leaching of Trace Elements from Biological Tissue by Formalin Fixation

In studies of trace elements in biological tissue, it is imperative that sample handling does not substantially change element concentrations. In many cases, fresh tissue is not available for study, but formalin-fixed tissue is. Formalin fixation has the potential to leach elements from the tissue, but few studies have been published in this area. The concentrations of 19 elements were determined by high-resolution inductively coupled plasma mass spectrometry in formalin in which human and rat brain samples had been stored for different time durations ranging from weeks up to several years. Additional analysis was carried out in fixed brain samples. There was substantial leaching of elements from the tissue into the formalin, and the leaching varied considerably between different elements. For example, formalin concentrations of As, Cd, Mg, Rb, and Sb increased more than 100-fold upon long-term (years) storage, while for Ni and Cr, the leaching was negligible. The degree of leaching was strongly time-dependent. In conclusion, formalin fixation and storage of biological tissue has the potential to leach substantial fractions of several trace elements from the tissue. The potential of leaching must be critically considered when using formalin-fixed biological tissue in trace metal analysis.     

Piscivory by brown trout Salmo trutta L. and Arctic charr Salvelinus alpinus (L.) in Norwegian lakes

Size and frequency of occurrence of prey of brown trout Salmo trutta L. and Arctic charr Salvelinus alpinus (L.) were recorded in 13 Norwegian lakes during 1973–1990. Piscivores usually comprised less than 5% of the total population. Arctic charr were less piscivorous than brown trout. Trout and charr became piscivorous at 13 and 16 cm length, respectively. These size thresholds were similar to those of other facultative piscivorous freshwater fish species. When present, three-spined sticklebacks, Gasterosteus aculeatus (L.), were preferred by all length groups of piscivorous brown trout and Arctic charr. Length of prey increased with increasing predator length, and the mean body length of prey was about 33 and 25% of predator length for trout and charr, respectively. Yearlings of charr were not recorded as prey.     

Adenosine deaminase activity is a sensitive marker for the diagnosis of tuberculous pleuritis in patients with very low CD4 counts

Background

Adenosine Deaminase Activity (ADA) is a commonly used marker for the diagnosis of tuberculous pleural effusion. There has been concern about its usefulness in immunocompromised patients, especially HIV positive patients with very low CD4 counts. The objective of this study was to evaluate the sensitivity of ADA in pleural fluid in patients with low CD4 counts.

Materials and Methods

This was a retrospective case control study. Medical files of patients with tuberculous pleuritis and non-tuberculous pleuritis were reviewed. Clinical characteristics, CD4 cell counts in blood and biochemical markers in pleural fluid, including ADA were recorded.

Results

One ninety seven tuberculous pleuritis and 40 non- tuberculous pleuritis patients were evaluated. Using the cut-off value of 30 U/L, the overall sensitivity, specificity, positive likelihood ratio, and negative likelihood ratio of ADA was 94%, 95%, 19, and 0.06 respectively. The mean CD4 cell counts among TB pleuritis patients was 29 and 153 cells/microL in patients with CD4 <50 cells/microL and >50 cells/microL, (p<0.05) respectively. The corresponding mean ADA values for these patients were 76 U/L and 72 U/L respectively (p>0.5). There was no correlation between ADA values and CD4 cell counts (r = −0.120, p = 0.369).

Conclusion

ADA analysis is a sensitive marker of tuberculous pleuritis even in HIV patients with very low CD4 counts in a high TB endemic region. The ADA assay is inexpensive, rapid, and simple to perform and is of great value for the immediate diagnosis of tuberculous pleuritis while waiting for culture result and this has a positive impact on patient outcome.     

Enterotoxin production at refrigeration temperature byYersinia enterocolitica andYersinia enterocolitica-like bacteria

Enterotoxin production after cultivation for 7 days in a refrigerator (3–6°C) was indicated for 4 of 20 strains ofYersinia enterocolitica andY. enterocolitica-like bacteria, by use of the infant mouse assay. These four strains were isolated from wild-living small mammals and water. Three of these isolates (Y. kristensenii, serogroups 11 and 28) were enterotoxigenic at 22 and 37°C as well as at refrigeration temperature. The remaining strain (Y. enterocolitica sensu stricto, serogroup 6) produced enterotoxin only at refrigeration temperature and at 22°C. The results indicate thatY. enterocolitica andY. enterocolitica-like bacteria may be capable of causing food intoxication after food storage at refrigeration temperature. A potential clinical significance of theY. enterocolitica enterotoxin in cold-blooded animals such as fish is suggested.     

Observational evidence of risk-sensitive reproductive allocation in a long-lived mammal

Organisms should adopt a risk-sensitive reproductive allocation when summer reproductive allocation competes with survival in the coming winter. This trade off is shown through autumn female body mass, which acts as an insurance against unpredictable winter environmental conditions. We tested this hypothesis on female reindeer in a population that has experienced a time period of dramatic increase in abundance. Environmental conditions during winter were fairly stable (with the exception of 1 year). We conclude that increased population abundance (perhaps in interaction with winter environmental conditions) could have represented a worsening of winter environmental conditions as both autumn offspring and spring female body mass decreased during the course of the study. Moreover, we found that the cost of reproduction was related to environmental conditions as: (1) autumn body mass was larger for barren than for lactating females, and this difference was temporally highly variable; (2) lactating females produced smaller offspring than barren ones in the following year; and (3) reproductive output (offspring size) decreased over time. We also found evidence of quality effects as lactating females had a higher reproductive success in the following year. In sum, a worsening of winter conditions lead to: (1) decreased reproductive output; (2) lowered autumn body mass for lactating females; and (3) increased body mass for barren females. Since females reduce their reproductive allocation as winter conditions becomes more severe, we conclude that reindeer have adopted a risk-sensitive reproductive allocation.