Observations on the development of the febrile response to pyrogen in newborn pigs

The febrile response of newborn pigs to exogenous pyrogen injection was investigated. Lipopolysacharides (LPS, E coli) were injected intravenously into the superior vena cava of 1-30-day-old piglets. All the experiments were carried out in littermates half of which were injected with pyrogen and half with pyrogen-free saline. Newborn pigs did not develop a febrile response from 1 to 4 days of age; however, when the animals were 5 days old exogenous pyrogen determined a typical monophasic febrile response. A second intravenous injection of pyrogen into newborn pigs (1 day old) 24 h after the first did not raise body temperature. It is suggested that newborn pigs behave like the newborn of other mammalian species regarding endotoxin-induced thermogenesis.

The development of a febrile response to pyrogen in the thyroid-deficient rabbit

The development of the febrile response to E. coli lipopolysaccharide (1.5 μg/kg, i.v.) in thyroid-deficient rabbits has been studied. Twenty-eight New Zealand White rabbits weighing 2.1-2.3 kg were used. Hypothyroidism was induced by treatment with propylthiouracil (100 or 200 mg/kg body wt./15 days). Thyroid-deficient animals showed a reduction in the febrile response to lipopolysaccharide, but the effect was significantly different (p<0.01) from the control only for rabbits treated with 200 mg/kg of propylthiouracil. Propranolol (2 mg/kg, i.p.) given 30 min before lipopolysaccharide also reduced (p<0.01) the fever response in control rabbits. The results of this experiment are consistent with the hypothesis that the reduction in the febrile response of thyroid-deficient rabbits is due to the reduced number of β-adrenergic receptors, or to a change in the availability of neurotransmitter in thermogenically active tissues, such as brown fat.

Influence of age on the febrile response to E. coli and S. typhimurium endotoxins in growing pullets.

1. The effect of bacterial endotoxin injection was studied in growing pullets of different ages. Commercial chicks were divided into 5 groups according to age. Bacterial endotoxins (E. coli and S. typhimurium) were injected intravenously and rectal temperature was measured over a period of 300 min. 2. The results showed no significant effect of age on the febrile response induced by bacterial endotoxins, but a slight tendency towards a reduced fever peak was observed with increasing age. The response latency also increased with age.

Radiographic and microbiologic evaluation of posttreatment apical and periapical repair of root canals of dogs' teeth with experimentally induced chronic lesion

The objective of the present study was to evaluate radiographically and bacteriologically apical and periapical repair in dogs' teeth with induced chronic periapical lesions with the use of two different operative techniques (techniques 1 and 2). The study was conducted on 40 root canals of upper and lower premolars from two dogs aged approximately 12 months. Periapical lesions were induced by leaving the root canals exposed to the oral environment for 5 days and then sealing them with zinc oxide-eugenol for 45 days. After this period, radiographic examination revealed the occurrence of a radiolucent lesion and endodontic treatment was started. The two techniques did not differ in terms of chemomechanical preparation, final filling, or type of cement, but differed in terms of irrigating solution and the presence of an antibacterial dressing. Thus 4% to 6% hypochlorite and hydrogen peroxide (10 volumes) were used in technique 1 during chemomechanical preparation and an antibacterial dressing based on calcium hydroxide was applied between sessions, whereas Dakin's fluid (0.5% sodium hypochlorite solution) and a final filling with no antibacterial dressing were used in technique 2. After chemomechanical preparation, the root canals were filled with gutta-percha cones and Sealapex (Sealapex-Sybron, Kerr, Sao Paulo, Brazil), and the animals were killed 270 days after the final filling. Blocks were cut into 6-μm sections and stained by the Brown and Brenn method. Radiographic, histomicrobiologic and statistical analysis permitted us to conclude the following: radiographically there was a marked reduction or even the disappearance of the radiolucent area present before treatment with greater success in the group treated with technique 1 (group I) than in the group treated with technique 2 (group II); the extent of bacterial invasion of dentinal tubules was greater and more intense in group II than in group I; and the amount of microorganisms detected in the ramifications of the apical delta and in the lumen of the root canal was intense in group II and mild or absent in group I. © 1994.

Papel da regiao AV3V no choque septico experimental em ratos tratados com NaCl 7,5%

The effect of intravenous infusion of hypertonic saline (HS) on the recovery of mean arterial pressure (MAP) during septic shock was studied in sham-operated rats and in rats with electrolytic lesion in the anteroventral third ventricle (AV3V) region. Our results show that intravenous HS infusion in rats treated with endotoxin (Etx) partially restores MAP, but when we have a severe shock produced by Etx, HS was not able to reverse the hypotension. We also show that the integrity of the AV3V region is essential for the protective action of HS in endotoxin shock. It is possible that NO production contributes to the deleterious effect of endotoxin. So, the unraveling of the release of NO by the vascular endothelium and their role as regulators of vascular tone is increasing our understanding of the physiology and pathophysiology of the cardiovascular system and will therefore enhance the possibilities of preventing and treating endotoxin shock.

Bacillus thuringiensis development from 1971 to 1996: Cases of a research group in Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Transference of a crystal protein gene from bacillus thuringiensis and its expression in bradyrhizobium sp. cells

The plasmid pHT409 that harbours the cryIA(a) gene for the production of a δ-endotoxin (crystal protein) from Bacillus thuringiensis was transferred into Bradyrhizobium sp. A conjugal transfer system aiming to introduce the plasmid into the Bradyrhizobium sp. host from colonies of an Escherichia coli donor strain (DH5α

Effect of nωnla, an inhibitor of No-synthase, on the release of tissue-plasminogem activator from rat aorta

Alterations in the synthesis or enhanced inactivation of nitric oxide (NO) and increase in fibrin deposition in the vascular bed lead to an imbalance that can induced intravascular coagulation. NO is produced through L-arginine pathway by constitutive and inducible nitric oxide synthase (NOS). The inducible isoform can be activated by cytokines such as tumor necrosis factor alfa. We evaluated NO-induced tissue-plasminogen activator (t-PA) release from isolated aortic segments of Wistar rats measuring the fibrinolytic activity in the fibrin plate. Inhibition of NO biossynthesis with Nω-nitro-L-arginine (NωNLA) significantly attenuated the fibrinolytic activity (FA) evoked by aortic segments of this group (GII) compared to the saline group (GI). The administration of L-arginine produced restoration of FA in this group (GIII) treated with NωNLA suggesting that t-PA arising from segments of rat aorta is influenced by NO.

Contribuição ao entendimento da patogenia da sepse

The most frequent cause of vasodilatory shockis outcome from sepsis, a systemic inflammatory response to infection, characterized by hypotension, hyporeactivity to the catecholamines and disseminated intravascular coagulation. The commonest cause of sepsis has reported to be infection with Gram-negative bacteria, typically E. coli, resulting in the release of lipopolysaccharide (endotoxin) from the bacterial outer membrane during autolysis or death of these microorganisms, with the involvement of many mediators, including nitric oxide. Later it was found that plasma levels of vasopressin in sepsis patients were abnormally low and observed that some patients with advanced septic shock were extremely sensitive to the activity actions of exogenous vasopressin.

Gastrointestinal changes associated to heart failure

Over the last decade, several studies were conducted on the gastrointestinal changes associated to chronic heart failure. This article presents a literature review on the physiopathology and clinical consequences of pathological digestive changes of heart failure patients. Structural and functional abnormalities of the gastrointestinal tract, such as edema of absorptive mucosa and intestinal bacterial overgrowth, have been leading to serious clinical consequences. Some of these consequences are cardiac cachexia, systemic inflammatory activation and anemia. These conditions, alone or in combination, may lead to worsening of the pre-existing ventricular dysfunction. Although currently there is no therapy specifically earmarked for gastrointestinal changes associated to heart failure, the understanding of digestive abnormalities is germane for the prevention and management of systemic consequences.

Effectiveness of castor oil extract on Escherichia coli and its endotoxins in root canals

The results of the present study showed a significant decrease in the number of E. coli in root canals (first collection) after irrigation with castor oil extract during biomechanical preparation. All medications tested in this study were able to eliminate E. coli in root canals; however, they could not neutralize endotoxins completely.

Anti-inflammatory mechanisms of the annexin A1 protein and its mimetic peptide Ac2-26 in models of ocular inflammation in vivo and in vitro

Annexin A1 (AnxA1) is a protein that displays potent anti-inflammatory properties, but its expression in eye tissue and its role in ocular inflammatory diseases have not been well studied. We investigated the mechanism of action and potential uses of AnxA1 and its mimetic peptide (Ac2-26) in the endotoxin-induced uveitis (EIU) rodent model and in human ARPE-19 cells activated by LPS. In rats, analysis of untreated EIU after 24 and 48 h or EIU treated with topical applications or with a single s.c. injection of Ac2-26 revealed the anti-inflammatory actions of Ac2-26 on leukocyte infiltration and on the release of inflammatory mediators; the systemic administration of Boc2, a formylated peptide receptor (fpr) antagonist, abrogated the peptide's protective effects. Moreover, AnxA1-/- mice exhibited exacerbated EIU compared with wild-type animals. Immunohistochemical studies of ocular tissue showed a specific AnxA1 posttranslational modification in EIU and indicated that the fpr2 receptor mediated the anti-inflammatory actions of AnxA1. In vitro studies confirmed the roles of AnxA1 and fpr2 and the protective effects of Ac2-26 on the release of chemical mediators in ARPE-19 cells. Molecular analysis of NF-κB translocation and IL-6, IL-8, and cyclooxygenase-2 gene expression indicated that the protective effects of AnxA1 occur independently of the NF-κB signaling pathway and possibly in a posttranscriptional manner. Together, our data highlight the role of AnxA1 in ocular inflammation, especially uveitis, and suggest the use of AnxA1 or its mimetic peptide Ac2-26 as a therapeutic approach. Copyright © 2013 by The American Association of Immunologists, Inc.