Modulating the modulators: parasites,neuromodulators and host behavioral change

Neuromodulators can resculpt neural circuits, giving an animal the behavioral flexibility it needs to survive in a complex changing world. This ability, however, provides parasites with a potential mechanism for manipulating host behavior. This paper reviews three invertebrate host-parasite systems to examine whether parasites can change host behavior by secreting neuromodulators. The parasitic wasp, Cotesia congregata, suppresses host feeding partly by inducing the host (Manduca sexta) to increase the octopamine concentration in its hemolymph. The increased octopamine concentration disrupts the motor pattern produced by the frontal ganglion, preventing the ingestion of food. Polymorphus paradoxus (Acanthocephalan) alters the escape behavior of its host, Gammarus lacustris (Crustacea), possibly through an effect on the host's serotonergic system. The trematode Trichobilharzia ocellata inhibits egg-laying in its snail host (Lymnaea stagnalis), partly by inducing the host to secrete schistosomin. Schistosomin decreases electrical excitability of the caudodorsal cells. The parasite also alters gene expression for some neuromodulators within the host's central nervous system. In at least two of these three examples, it appears that the host, not the parasite, produces the neuromodulators that alter host behavior. Producing physiologically potent concentrations of neuromodulators may be energetically expensive for many parasites. Parasites may exploit indirect less energetically expensive methods of altering host behavior. For example, parasites may induce the host's immune system to produce the appropriate neuromodulators. In many parasites, the ability to manipulate host behavior may have evolved from adaptations designed to circumvent the host's immune system. Immune-neural-behavioral connections may be pre-adapted for parasitic manipulation.     

Polymorphism of vitamin D receptor gene start codon in patients with calcium kidney stones

BACKGROUND: A linkage has been detected between vitamin D receptor (VDR) locus and calcium kidney stone disease. In order to assess the eventual role of VDR gene start codon polymorphisms in stone production, we analyzed the genotype-phenotype association in a group of patients with calcium kidney stones. METHODS: One hundred and fifty-five patients were studied. VDR genotypes were characterized at the translation start site by restriction fragment length polymorphism analysis, using endonuclease FokI. Phenotypes of calcium-phosphate metabolism were compared in patients with different genotypes: strontium enteral absorption (used as a surrogate marker for calcium absorption), bone mineral density (BMD), calcium and phosphate excretion were measured. RESULTS: Genotype distribution was not different in hypercalciuric and normocalciuric stone formers. Enteral strontium absorption, calcium excretion and BMD did not vary with the patient's genotype. Serum concentrations of phosphate (p=0.022) and renal threshold for phosphate excretion (p=0.026) were lower in patients with genotype FF (homozygous for the absence of the FokI site) than in those with genotype ff (homozygous for the presence of the FokI site). The lower phosphatemia was confirmed in FF hypercalciuric patients, but not in normocalciuric ones. Serum concentrations of phosphate and calcitriol in the group of hypercalciuric patients were inversely correlated with the genotype FF. CONCLUSIONS: The FokI genotype does not appear to be involved in the causes of idiopathic hypercalciuria and kidney stones. Hypercalciuric patients with FF genotype may be a subgroup with low plasma concentrations of phosphate, predisposed to tubular leakage of phosphate.     

Lactacystin, a specific inhibitor of the proteasome, induces apoptosis and activates caspase-3 in cultured cerebellar granule cells

The multicatalytic protease complex or proteasome is a fundamental nonlysosomal tool that the cell uses to process or degrade proteins at a fast rate through the ubiquitin and ATP-dependent proteolytic pathway. Examples of these important proteins include the tumor suppressor protein p53, various cyclins, the cyclin-dependent kinase inhibitor p27, NFkappaB, IkappaB, c-fos, and c-jun. The activation of proteolytic enzymes, including certain cystein-proteases of the ced-3/ICE (interleukin-1beta-converting enzyme) family, is a characteristic feature of the apoptotic program. However, the role of the multicatalytic protease complex in apoptosis is not well known. In order to obtain further information regarding the participation of the ubiquitin-mediated pathway in the decision of the cell to execute the cell death program, we have used a specific inhibitor of the multicatalytic protease complex, lactacystin, in cultured cerebellar granule cells. Cells were obtained from the cerebellum of 6- to 8-day-old Wistar rats and cultured in Neurobasal medium supplemented with B-27. Addition of lactacystin to the cultures induced apoptosis of the granule cells in a time-dependent fashion. The morphological changes produced by the proteasome inhibitor included nuclear condensation and DNA fragmentation measured by the diphenylamine test, as well as a positive labeling by the TUNEL (terminal deoxynucleotidyltransferase mediated-dUTP nick end labeling) assay, all of them typical features of apoptosis. Concomitant with apoptosis, there were changes in the expression of the ubiquitin mRNA, a progressive depletion in the free ubiquitin pool, and an increase in the high molecular weight ubiquitin-protein conjugates. Caspase-3, a member of the ced-3/ICE family of cystein-proteases, showed a marked increase in activity in the lactacystin-treated cells. In flow cytometry studies, the amount of cells in the S phase of the cell cycle was smaller in the lactacystin-treated cells than in controls, suggesting that apoptosis could be due, in part, to an alteration of the cell cycle.     

Role of nuclear medicine in the treatment of malignant gliomas: the locoregional radioimmunotherapy approach

The high-grade malignant gliomas (anaplastic astrocytomas and glioblastoma) have a very bad prognosis since the available methods of treatment (surgery, radiotherapy and chemotherapy) are unable to control the progression of the disease for long. The use of specific monoclonal antibodies labelled with a suitable isotope (iodine-131 or yttrium-90) represents an effective approach to hamper tumour regrowth. Some authors have injected the antibodies intravenously, or have tried to increase the tumour/background ratio with the avidin/biotin system. In many cases the labelled monoclonal antibodies were injected directly into the tumoral bed after the operation. The authors' experiences concern a quite large locoregional radioimmunotherapy study which was performed by using antitenascin antibodies labelled initially with 131I and more recently with 90Y. The clinical results demonstrate the ability of this technique to control, for a long time, the growth of these tumours. The glioblastoma median survival was prolonged to 25 months (131I group) or 31 months (90Y group). The response rate (which comprises PR, CR and NED) was 47.1% (glioblastoma 131I group) or 40% ( glioblastoma 90Y group). In many cases a significant tumour shrinking effect was radiologically demonstrated. The use of 90Y proved more favourable in bulky lesions, and reduced the radioprotection problems.     

Modulation of 5-fluorouracil as adjuvant systemic chemotherapy in colorectal cancer: the IGCS-COL multicentre, randomised, phase III study

The aims of this multicentre, randomised phase III trial were to evaluate: (1) the role of levamisol (LEV); and (2) the role of folinic acid (FA), added to 5-fluorouracil (5FU) in the adjuvant treatment of colorectal cancer. Patients with histologically proven, radically resected stage II or III colon or rectal cancer were eligible. The study had a 2x2 factorial design with four treatment arms: (a) 5FU alone, (b) 5FU+LEV, (c) 5FU+FA, (d) 5FU+LEV+FA, and two planned comparisons, testing the role of LEV and of FA, respectively. From March 1991, to September 1998, 1327 patients were randomised. None of the two comparisons resulted in a significant disease-free (DFS) or overall (OAS) survival advantage. The hazard ratio (HR) of relapse was 0.89 (95% confidence intervals (CI): 0.73-1.09) for patients receiving FA and 0.99 (95% CI 0.80-1.21) for those receiving LEV; corresponding HRs of death were 1.02 (95% CI: 0.80-1.30) and 0.94 (95% CI 0.73-1.20). Nonhaematological toxicity (all grade vomiting, diarrhoea, mucositis, congiuntivitis, skin, fever and fatigue) was significantly worse with FA, while all other toxicities were similar. In the present trial, there was no evidence that the addition of FA or LEV significantly prolongs DFS and OAS of radically resected colorectal cancer patients.     

Pseudomonas aeruginosa flagella activate airway epithelial cells through asialoGM1 and toll-like receptor 2 as well as toll-like receptor 5

The distribution of specific toll-like receptors and components of the signaling pathways activated by Pseudomonas aeruginosa flagella were studied in airway epithelial cells. Initially flagella bound to the apical surface of polarized epithelial cells, where they prominently colocalized with asialoGM1. By 4 h of exposure to flagella, toll-like receptor (TLR)5 expression was induced, mobilized to the apical surface of the cells, and colocalized with superficial flagella. Interleukin-8 expression in airway cells was activated by flagella through induction of Ca(2+) fluxes, Src, Ras, and extracellular signal-regulated kinase 1/2 mitogen-activated protein kinase and nuclear factor-kappaB activation, a pathway previously associated with asialoGM1-mediated stimuli. There was evidence for participation of asialoGM1 and TLR2 as well as TLR5 in the response to flagella, and increased asialoGM1 correlated directly with increased signaling. TLR2 DN or TLR5 DN mutations inhibited interleukin-8 induction by 78% and 35%, respectively (P < 0.001 for each). The participation of TLR2 as well as TLR5 was confirmed in Chinese hamster ovary cells transfected with either human TLR2 or TLR5 in which flagella activated a nuclear factor-kappaB-luciferase reporter to the same extent. Flagella signaling in airway cells can be initiated by interactions with asialoGM1 and TLR2 as well as by activation of TLR5. The availability of exposed receptors on the apical surface of polarized airway epithelial cells is a major factor in the activation of signaling pathways by flagella.     

Madelung's disease: case report and discussion of treatment options

Madelung's disease was first described in 1846. Since then, approximately 200 patients have been reported in the literature. Its three main characteristics-typical location of the lesions, symmetry, and the diffusive nature of the fat-are more often found in men of Mediterranean descent. A clear association with alcohol abuse is reported, but the etiology remains uncertain. Patients usually complain of their cosmetic appearance, but treatment can be rendered for decreased neck motion and/or aerodigestive problems. Given the benign nature of the lesion, surgical debulking is the treatment of choice, with liposuction reserved for smaller lesions. A standard facelift pattern can be used for skin incisions and removal, with good cosmetic results.