Subchronic toxicity of fish oil concentrates in male and female rats

There are an overwhelming number of reports indicating the beneficial effects of fish oil supplements in human and animal nutrition. The purpose of this study, second in a series, was to evaluate the effects, particularly those that may be harmful, of high-dose, long-term consumption of fish oil concentrates (FOC) using male and female rats. One hundred and twenty male and 120 female rats were gavaged daily with oils and oil mixtures in a volume equal to 0.5% body weight (5 mL/kg/d) for 13 weeks. The administered oils were corn oil, pure menhaden oil (MO), pure MaxEPA fish oil or different mixtures of corn oil with MO. The stability and the homogeneity of the dosing solutions were tested under study conditions. The animals received isocaloric and isonitrogenous diets throughout. Food and pure water were supplied ad libitum. At the end of the in-life phase of the study, the animals were anaesthetized with CO2 and humanely killed by exsanguination. Blood and other tissues were prepared for various clinical, histopathological and laboratory tests. Some beneficial effects of FOC, such as reduction in total serum cholesterol, in rats were confirmed. However, we also observed a significant reduction in absolute amount of serum HDL and a significant increase in relative liver and spleen weights in both sexes with the high dose of FOC. High doses of FOC (5 mL/kg/d) reduced serum iron and vitamin E concentrations. A reduction in osmotic fragility of RBC as well as an increase in RBC deformity were also observed in rats treated with high doses of FOC. These rats showed a significant overall increase in WBC count. We conclude that in rats, subchronic consumption of high levels of FOC can be beneficial but may also be harmful because of induction of clinical abnormalities including increased red cell deformity, increased relative liver and spleen weights, and reduced serum HDL, iron and vitamin E concentrations.     

The role of the plasminogen activation system in angiogenesis and metastasis

The urokinase plasminogen activator system (uPA) has been demonstrated to be required for the movement of cells through a matrix. These observations have been extended to the migration of endothelial cells during the process of angiogenesis, and recent data suggest that the uPA system is central to this process. uPA is a serine protease that is capable of initiating an extracellular cascade of proteolysis that involves the activation of plasminogen and matrix metalloproteases. These proteolytic cascades remodel extracellular matrix (ECM) and basement membrane (BM), allowing for the movement of cells across and through these barriers. In addition, these proteolytic cascades process and release various growth and differentiation factors that are sequestered on the cell surface or within the ECM, which contribute to the evolution of a migratory or invasive cell phenotype. uPA is also able to modulate signaling and cell adhesion through its specific cell surface receptor, uPAR. Recent data suggest that the nonproteolytic activities of the uPA system are coupled to adhesion, migration and signaling through various integrins. This article reviews the evidence for the role of this system in tumor angiogenesis and metastasis, which suggests that the uPA system initiates multiple cascades that contribute to these processes.     

Management of esophageal varices

Of the consequences of portal hypertension, varices carr the most sinister implications. During life, the risk of hemorrhage from varices hangs like a "sword of Damocles" over a cirrhotic’s head. Hemorrhage, when it occurs, expedites the patient’s demise, or often itself proves to be the terminal event. Compared with other causes of gastrointestinal bleeding, hemorrhage from varices is most severe, and the available therapies, over the long-term, are the least definitive.     

Induction of oral tolerance towards hepatitis B envelope antigens in a murine model

BACKGROUND: Hepatitis B virus (HBV) is a non-cytopathic virus, and the hepatocellular injury that occurs as a consequence of HBV infection is mediated by the host antiviral immune response. Subjects with natural tolerance to HBV have minimal or no liver injury despite chronic viremia. We have shown that immune tolerance towards viruses can be induced by oral administration of viral proteins. AIMS: To test whether oral induction of tolerance can be induced towards HBV antigens, and whether oral tolerance induction downregulates preexisting anti-HBV immune response. METHODS: Oral tolerance was induced via feeding of five low oral doses of HBV proteins (HBsAg+preS1+preS2, BioHepB). This was followed by two inoculations with the BioHepB vaccine. Humoral immune tolerance was evaluated by measuring serum levels of anti-HBs antibody titers at monthly intervals. To determine if oral tolerance induction downregulates pre-existing anti-HBs immunity, mice were inoculated twice with the BioHepB vaccine, followed by feeding of BioHepB-HBV proteins. RESULTS: Feeding of HBV proteins markedly inhibited production of anti-HBs antibodies in naive mice. Anti-HBs titers were 45 versus 135 mIU/ml, in tolerized versus non-tolerized controls (P<0.005). Moreover, oral tolerance induction effectively down-regulated pre-existing immunity and reduced the anti-HBs titers in previously immunized mice to 112 versus 223 mIU/ml, in tolerized compared with non-tolerized controls (P<0.01). CONCLUSIONS: Induction of oral tolerance towards HBV proteins downregulates the antiviral humoral immune response in naive mice, and in the presence of preexisting anti-HBV immunity. This approach should be further investigated as a method for alleviation of antiviral-mediated liver injury in chronic HBV hepatitis.     

Discitis associated with pregnancy and spinal anesthesia.

Discitis (inflammation of the intervertebral disk) most commonly develops as a rare complication of bacterial infection or chemical or mechanical irritation during spine surgery (1) with a postoperative incidence of 1%-2.8% (2). It is also a complication of discography-the intradiscal injection of saline or contrast material (3). The incidence of postdiscography discitis is 1%-4% (3); no cases have been reported when prophylactic antibiotics have been used, supporting the theory of bacterial contamination (3). Although it is controversial whether discitis can be caused by an aseptic or infectious process, recent data suggest that persistent discitis is almost always bacterial (4). Honan et al. (5) reported 16 cases of spontaneous discitis and reviewed another 52 patients from the literature. In their series, patients tended to have one or more comorbid conditions, such as diabetes, vertebral fracture, or a preexisting spine injury. Spontaneous discitis has also been associated with advanced age, IV drug abuse, IV access contamination, urinary tract infection, and immunocompromised states (5,6). No cases of infectious discitis associated with pregnancy and spinal anesthesia have been reported in the English literature. Discitis presents as spasmodic pain in the back that may be referred to the hips or groin (7). The pain may radiate to the lower extremities. The erythrocyte sedimentation rate is usually increased. Radiological changes in discitis include narrowing of the intervertebral disk space, vertebral sclerosis, and erosion of the end plates. The best diagnostic measure may be magnetic resonance imaging (MRI) or a combination of bone and gallium scanning (2). The mainstay for discitis treatment is pain control and antibiotics; surgical intervention is usually not required. Complications of discitis include intervertebral fusion, epidural abscess, and paralysis. IMPLICATIONS: This is a case report of a disk infection (discitis) caused by the bacteria, Streptococcus bovis after spinal anesthesia for cesarean delivery. S. bovis rarely causes discitis, and spinal anesthesia for labor and delivery has not been reported as a cause of discitis.     

N-Chlorination and oxidation of procainamide by myeloperoxidase: toxicological implications.

In previous studies we had shown that procainamide is metabolized to reactive metabolites by activated leukocytes, and evidence pointed to involvement of myeloperoxidase (MPO). In this study we examine the metabolism of procainamide by MPO/H2O2, in the presence and absence of chloride ion. In the absence of chloride ion, the metabolism was very similar to that seen with activated leukocytes. The major metabolite was formed by oxidation of the arylamine group to a hydroxylamine. In the presence of chloride ion, a much greater degree of metabolism occurred, and the major product (40% of the starting procainamide) was a reactive species that could not be isolated. This metabolite spontaneously rearranged to 3-chloroprocainamide, and from its mass spectrum and chemical reactions, we deduce its structure to be N-chloroprocainamide. The N-chloroprocainamide metabolite reacted very rapidly with reducing agents, such as ascorbate, and also reacted with protein such as albumin, the major product in both cases being procainamide. This metabolite also chlorinated phenylbutazone. When radiolabeled procainamide was oxidized by MPO/H2O2 in the presence of albumin, covalent binding of the radiolabel to albumin occurred, and binding was greater under conditions in which N-chloroprocainamide was formed. It is probable that the failure to observe N-chloroprocainamide, when procainamide is oxidized by activated leukocytes, is due to its rapid reaction with the cells. We propose that modification of neutrophils (or neutrophil precursors in the bone marrow) by these reactive metabolites is responsible for procainamide-induced agranulocytosis. In a similar manner, procainamide-induced lupus could be due to modification of monocytes by monocyte-generated reactive metabolites.     

Immunomodulation of experimental colitis: the role of NK1.1 liver lymphocytes and surrogate antigens--bystander effect.

The imbalance between Th1 pro-inflammatory and Th2 anti-inflammatory cytokine-producing cells plays a major role in the pathogenesis of inflammatory bowel disease (IBD). Induction of oral tolerance to colitis-extracted proteins was previously shown to down-regulate the anti-colon immune response, thereby alleviating experimental colitis. Immune bystander effect and liver-associated lymphocytes expressing the NK1.1 marker (NK1.1(+) LAL) have been suggested as being important in tolerance induction. The aims of the present study were to determine whether oral administration of inflammatory and non-inflammatory colon-extracted proteins of different species can induce peripheral immune tolerance and alleviate experimental colitis; and to examine the role of NK1.1(+) LAL in oral tolerance induction. Colitis was induced in C57/B6 mice by intracolonic instillation of trinitrobenzene sulphonic acid (TNBS). Mice received six oral doses of colonic proteins extracted from TNBS-colitis colonic wall, or normal colonic wall, from four different species. Standard clinical, macroscopic, and microscopic scores were used for colitis assessment. Serum interferon gamma (IFNgamma) and interleukin 10 (IL10) levels were measured by ELISA. To evaluate the role of NK1.1(+) LAL in maintaining the balance between immunogenic and tolerogenic subsets of cells, their cytotoxicity functions were tested in tolerized and non-tolerized-mice. The administration of mouse-derived colitis-extracted proteins, or of surrogate proteins extracted from normal mouse colon, or from rat or human inflammatory colons, was found to alleviate experimental colitis. Tolerized mice had less diarrhoea; showed a marked reduction of colonic ulceration, intestinal and peritoneal adhesions, wall thickness, and oedema; and demonstrated a significant improvement of all microscopic parameters for colitis. Induction of tolerance led to an increase in IL10 and a decrease in IFNgamma serum levels. NK1.1(+) LAL cytotoxicity function increased markedly in tolerized mice. In contrast, mice fed with proteins extracted from normal rat, rabbit, and human colon, or from rabbit inflammatory colon, developed severe colitis, with a marked increase in IFNgamma and a decrease in IL10 serum levels, and down-regulation of NK1.1(+) LAL function. This study has shown that oral tolerance can be induced in experimental colitis by means of the feeding of surrogate antigens; this alleviates experimental colitis. NK1.1(+) LAL cytotoxicity function is associated with peripheral tolerance induction and may help to maintain the Th1/Th2 immune balance.     

Selective osteoblast mitogens can be extracted from prostatic tissue

Extracts of human prostatic carcinoma and of human benign prostatic hyperplasia were found to exhibit mitogenic activity in freshly isolated rat osteoblasts, rat fibroblasts, and osteoblast-derived osteosarcoma cells. This activity was markedly reduced by tryptic digestion of extracts, indicating its protein nature. Results of bioassay studies suggested that the prostatic material was different from a number of known growth factors. Analysis by reversed-phase high performance liquid chromatography revealed that extracts contained mitogenic activity for osteoblasts that was distinct from fibroblast-stimulating activity. Such osteoblast growth factors could form the basis of the skeletal osteogenic response to metastatic prostatic adenocarcinoma.