hGH and GHR Expression in Large Cell Neuroendocrine Carcinoma of the Colon and Rectum

Large cell neuroendocrine carcinoma (LCNEC) is an aggressive neoplasm with a low frequency of occurrence in the digestive tract. We present a series of eight patients diagnosed with LCNEC of the colon and rectum. Grossly, tumors were presented as endophytic/ulcerative, annular and polypoid masses, with a gray-white color and necrosis in most cases. Histologically, they were high-grade tumors composed of large cells of organoid, nesting, trabecular, rosette-like and palisading patterns, with a high mitotic rate. Tumors were immunoreactive for neuroendocrine markers, including chromogranin A (2/8), synaptophysin (7/8), and neuron-specific enolase (8/8). Moreover, we analyzed the expression of growth hormone (hGH) and growth hormone receptor (GHR) in colorectal LCNECs and six tumors were immunoreactive for hGH, while five tumors were immunoreactive for GHR. To our knowledge hGH and GHR expression has not been previously analyzed in colorectal LCNEC. Their overexpression suggests a role of hGH and GHR in the development of colorectal LCNEC.     

Superoxide dismutase and lipid hydroperoxides in blood and endometrial tissue of patients with benign, hyperplastic and malignant endometrium

Epidemiological and experimental data point to involvement of oxygen derived radicals in the pathogenesis of gynecological disorders, as well as in cancer development. The objective of the present study was to examine changes in activities and levels of copper/zinc superoxide dismutase (CuZnSOD) and lipid hydroperoxides (LOOH) in blood and endometrial tissue of patients diagnosed with uterine myoma, endometrial polypus, hyperplasia simplex, hyperplasia complex and adenocarcinoma endometrii. The results of our study have shown decreased SOD activities and unchanged SOD protein level in blood of all examined patients in comparison to healthy subjects. Decrease of both SOD activity and level was found in endometrium of patients with hyperplasia simplex, hyperplasia complex and adenocarcinoma in comparison to women with polypus or myoma. LOOH level was elevated in both tissues of patients with hyperplasia or adenocarcinoma in comparison to healthy subjects or patients with benign diagnosis. Our findings suggest that the decrease in SOD activity and level, as well as the increase in LOOH level, in patients with gynecological disorders, render these patients more susceptible to oxidative damage caused by reactive oxygen species (ROS). An imbalance in ROS formation and SOD level may be important in the pathogenesis and/or perpetuation of tissue damage in gynecological patients. Since evidence suggests that SOD may be a therapy target for cancer treatment, our findings provide a basis for further research and options for clinical applications.     

Tissue factor and nitric oxide: a controversial relationship!

Tissue factor (TF) is the primary physiological initiator of blood coagulation. TF has a high-affinity for factor (F) VII resulting in the formation of (TF:FVII:FVIIa) bimolecular complex which, in the presence of Ca(2+), increases the enzymatic activity of FVIIa towards its natural substrates, FIX and FX, generating their active forms FIXa and FXa, respectively. This eventually leads to thrombin generation and a fibrin clot formation. Up-regulation of TF in injured blood vessels and atherosclerotic plaque can lead to undesirable vascular thrombosis. Nitric oxide (NO) is a free radical synthesized from L-arginine and molecular oxygen by nitric oxide synthases (NOS). NO participates in diverse physiological and pathophysiological process as an intra or extracellular messenger. A relationship between TF and NO has been proposed. Thus, models of TF regulation by NO has been studied in different cells and experimental animal models, but the results have been conflicting. The premise that NO donors can prevent TF expression in vivo has provided the foundation for a broad field of pharmacotherapeutics in vascular medicine. A new class of drugs combining a statin (inhibitors of coenzyme A reductase) with an NO-donating moiety has been described. The resulting drug, nitrostatin, has been suggested to increase the antithrombotic effects of native statin. However, it is questionable if NO release from these drugs had any significant role on TF inhibition. In summary, care must be taken in drawing conclusions about the relationship between NO and TF. Interpretation of NO studies must take several factors into consideration, including NO bioavailability, its half-life and inactivation, as well as the cell type and experimental model used.     

Effect of oral hormone replacement therapy on plasma homocysteine levels

BACKGROUND: Various inherited or acquired conditions can lead to mild or severe hyperhomocysteinemia, which has toxic effects on the vascular endothelium. It has been reported that hormone replacement therapy is associated with decreased homocysteine plasma levels, but this is still a controversial issue. PURPOSE: To compare homocysteine plasma levels in women before and after 3 months of oral hormone replacement therapy. METHODS: Twenty-four women were selected to take part in the study. Blood samples were collected immediately before hormone replacement therapy (cyclic association of 2 mg of estradiol valerate and 1 mg of cyproterone acetate) and three months after the beginning of hormone replacement therapy. Samples collected before hormone replacement therapy were used as controls. Plasma homocysteine levels and the presence of C677T mutation in the methylene tetrahydrofolate reductase gene were evaluated in all participants. RESULTS: The methylene tetrahydrofolate reductase gene mutation was detected in 8 women (33.3%) in heterozygosis, in 3 (12.5%) in homozygosis, and 13 women (54.2%) did not present the mutation. No significant differences were observed in homocysteine levels before and after three months of oral hormone replacement therapy, regardless of the C677T genotype. CONCLUSIONS: The results obtained indicate that homocysteine plasma levels are not affected after three months of oral hormone replacement therapy.     

Polymorphism in the methylenetetrahydrofolate reductase (C677T) gene and homocysteine levels: a comparison in Brazilian patients with coronary arterial disease, ischemic stroke and peripheral arterial obstructive disease

This study aimed to compare plasma levels of total homocysteine (tHcy) in different arterial events as well as to investigate an association between homocysteine levels and C677T polymorphism in Brazilian patients. A total of 145 subjects were enrolled in this study including 43 patients with coronary arterial disease (CAD), 21 with ischemic stroke (IS), 44 with peripheral arterial obstructive disease (PAOD) and 37 control subjects. A preliminary analysis showed significant difference for tHcy plasma levels between patients with CAD (P = 0.003) or PAOD (P = 0.03) compared to controls. However, after adjustment for sex, age, total cholesterol, LDL, diabetes, tabagism or C677T polymorphism, no significant differences were detected in tHcy levels among patients groups and controls. No significant correlation was demonstrated for C677T polymorphism and homocysteine levels. These results indicate that increased Hcy levels may not be considered an independent risk factor for atherothrombotic diseases in Brazilian patients.     

Interaction of pyridinium oximes with acetylcholinesterase and their effect on organophosphate-poisoned mice

The progressive inhibition of acetylcholinesterase (AChE [EC 3.1.1.7]) by organophosphates (OPs), such as the nerve agents tabun and soman, is due to phosphorylation of the active center serine characterized by the formation of conjugates and inactivation of this essential enzyme involved in neurotransmission. Presently, a combination of an antimuscarinic agent, e.g., atropine, and an AChE reactivator, oxime, is used for the treatment of organophosphorus compound poisoning. The increased concern about terrorist use of nerve agents prompted us to search for new, more effective oximes against tabun and soman poisoning. We investigated the interactions of five bispyridinium oximes with human erythrocyte AChE and their effects on tabun- and soman-poisoned mice.     

Antidotal efficacy of pyridinium chloride derivatives against soman poisoning

Acetylcholinesterase (AChE; EC 3.1.1.7.) is an extremely active enzyme necessary for terminating the action of acetylcholine in cholinergic synapses. The aim of this study was to evaluate the efficacy of four mono-pyridinium compounds 1-phenacylpyridinium chloride (I), 1-phenacyl-2-methylpyiridinium chloride (II), 1-benzoylethylpyridinium chloride (III), and 1-benzoylethylpyridinium-4-aldoxime chloride (IV) in the therapy of soman poisoning. Their effect was compared with HI-6 and TMB-4 oximes. The inhibitory potency (IC50) of compounds as well as reactivating (%R) and protective potency (P50) with respect to soman-inhibited AChE were determined for each of the compounds. Their acute intraperitoneal toxicity (LD50 with 95% confidence limits) was tested in mice and observed for 24 hr. The therapeutic effect was expressed as the protective index and as the therapeutic dose. The tested compounds were found to be reversible inhibitors of AChE. In vivo results show that the tested compounds are relatively toxic (their LD50 was from 74.9 to 210.0 mg/kg body weight). The best antidotal efficacy was obtained with compound II, which had the highest affinity for AChE (IC50 was 1.9 x 10(-5) mol l(-1)) and seems to be an adequate antidote in soman poisoning (its protective index and therapeutic dose were 2.8 and 2, respectively). Our results indicate that its antidotal effect is related to the reactivation or protection of AChE. The type of the substituent in the pyridinium ring generally has a significant influence on toxicity in vitro and in vivo, and on the antidotal efficacy of all new tested compounds.     

Imprinting of BALB/c mice with low Leishmania infantum parasite dose markedly protects spleen against high-dose challenge

In this study, we investigated in the BALB/c model, the dose-dependent protective potential of previous infection with Leishmania infantum parasites, against a high-dose challenge and showed for the first time that low-dose imprinting conferred substantial spleen resistance. Mice were immunized for 1 month or 5 months by IV route with parasite inocula ranging from 10(4) to 10(7) and from 10(3) to 10(5), respectively, and challenged for 1 month with 3 x 10(7) parasites. Liver protection was directly proportional to the parasite dose used for infection and reached 90-95% whereas, only low doses (< or =10(5)) protected spleen. Maximal spleen resistance (80%) was reached in mice infected for 5 months with 10(5) parasites. In most cases, protection was accompanied in spleen, by restored in vitro responses to Leishmania antigens. Analysis of anti L. infantum isotype responses and in vitro antigen-induced cytokine production, indicated that the acquired protection was irrespective of a Th1/Th2 imbalance.     

Transepithelial immunomodulation by cholera toxin and non-toxic derivatives

Comparative analyses of murine dendritic cells (DC) isolated from the skin and from the intestinal mucosa after exposure to cholera toxin and its non-toxic B subunit disclose striking differences regarding the migratory and functional behaviour of these cells. The nature of the epithelial microenvironment, especially locally produced cytokines and chemokines, appears to influence the functional ability of skin and mucosal DCs to convey immunogenic as opposed to tolerogenic signals and hence to regulate immune responsiveness at skin and at mucosal sites.