Endotoxin Production Research Articles

Development of a Low Cost Bioprocess for Endotoxin Production by Bacillus thuringiensis var israelensis Intended for Biological Control of Aedes aegypti

Aedes aegypti is the vector of Dengue disease, responsible for 20,000 deaths/year worldwide. Bacillus thuringiensis var israelensis - Bti releases selective and effective toxins (crystal proteins) against A. aegypti larvae. We present a low cost bioprocess for toxin production, accomplished by a selected Brazilian strain Bti (BR-LPB01) and employment of low cost substrates. Soybean meal and sugarcane molasses lead to high toxic effectiveness after 2L bioreactor fermentation (LD50=26ng/mL), near to the reference strain IPS82 (LD50=17.3 ng/mL). The pH ranged between 5.8 and 7.0 during the exponential growth period and between 7.0 and 8.4 during the stationary phase, with low activity. Thus, control of foam and pH 7.0 were started and proved to be crucial for high activity. It was verified that the fermentation could be discontinued after 20 hours, when the highest activity was present.

BIOLOGICAL PESTICIDE PRODUCTION BY BACILLUS THURINGIENSIS USING WASTES OF STARCH INDUSTRY

Some wastes especially wastes of food industries need to be treated in order to recover some value-added products. One of these valuable products is biological pesticides. Today, the most successful biological pesticides are produced by Gram-positive, rod-shape bacteria, the genus Bacillus that produces crystalline endotoxin proteins during spore formation. These toxins will be activated when they enter the insect intestine under alkaline condition and will damage the cell membrane and make holes in the membrane which result in lysing of epithelial cells. In this research, the waste of starch producing industry was inoculated with Bacillus thuringiensis var. kurstaki and then the crystalline protein with MW of 65 KDa was produced during fermentation. The larvaes of Galleria melonella were treated to this protein and the rate of mortality was assessed after 24 and 48 h, and its effect was compared with that of control. Researches showed that the production of delta endotoxin has direct correlation with sporulation. The most toxicity of these bacterial proteins occurs at the highest number of spores. Thus, the number of total bacteria and their spores were enumerated using PCA during fermentation that was 12.5×108 and 48×107 cfu/ml, respectively. Key words: Microbial pesticide, Starch producing industry wastewater, Endotoxin, Bacillus thuringiensis var. kurstaki

Endotoxin and biogenic amine levels in Atlantic mackerel (Scomber scombrus), sardine (Sardina pilchardus) and Mediterranean hake (Merluccius merluccius) stored at 22 °C

Whole Atlantic mackerel (Scomber scombrus), sardine (Sardina pilchardus) and Mediterranean hake (Merluccius merluccius) from the Croatian Adriatic were stored at 22 °C and changes in histamine, putrescine, tyramine and cadaverine levels were monitored in relation to bacterial endotoxin. After 12 h, histamine levels in sardine were above the legal limit of 50 mg kg−1, set by the US Food and Drug Administration, and an increase in putrescine content preceded the increase in histamine. After 24 h, histamine contents in mackerel and sardine reached 1090 ± 101 and 577 ± 275 mg kg−1, respectively, which exceeded the toxic threshold of 500 mg kg−1. At the same time, the putrescine content was also high in both fish (353–420 mg kg−1). The time-course of endotoxin production was similar in all fish species stored at 22 °C. A high correlation was found between endotoxin and histamine, and between endotoxin and putrescine in mackerel and sardine. On the other hand, high endotoxin levels in hake, after 24 h, were associated with the low histamine and putrescine content (40–60 mg kg−1).

Subacute ruminal acidosis in dairy cows: The physiological causes, incidence and consequences

During subacute ruminal acidosis (SARA) rumen pH is depressed for several hours per day due to accumulation of volatile fatty acids and insufficient rumen buffering. Surveys suggested an incidence of SARA of between 19% and 26% in early and mid-lactation dairy cows. Causes of SARA include feeding excessive amounts of non-structural carbohydrates and highly fermentable forages, and insufficient dietary coarse fiber. Consequences of SARA include feed intake depression, reduced fiber digestion, milk fat depression, diarrhea, laminitis, liver abscesses, increased production of bacterial endotoxin and inflammation characterized by increases in acute phase proteins. The increase in endotoxin is similar among methods for SARA induction, but depends on the diet fed before induction. Increases in acute phase proteins vary among methods of SARA induction, even when the methods result in similar rumen pH depressions. This suggests that the inflammatory response might not be solely due to bacterial endotoxin in the rumen.

OPTIMIZATION OF A CULTURE MEDIUM FOR BIOMASS AND δ-ENDOTOXIN PRODUCTION BY A RECOMBINANT ESCHERICHIA COLI STRAIN

A recombinant strain of Escherichia coli harboring a plasmid containing the Bacillus thuringiensis δ-endotoxin synthesis gene, was tested for its efficacy to synthesize δ-endotoxin, in a complex medium containing sucrose and yeast extract. Also, the recombinant E. coli strain was tested for its efficacy against the 2nd instars of Spodoptera littoralis. The recombinant strain of E. coli showed a good activity against the 2nd instars of S. littoralis, the mortality was 70 % after 7 days at room temperature. A high cell biomass (8.8gL-1) and δ-endotoxin concentration (6.8 mg L-1), were obtained by the shake flask culture (100 ml medium/250 ml flask, at 200 rpm), of the recombinant E. coli in modified MR medium containing sucrose (20g/L), as carbon source and yeast extract as nitrogen source, in the presence of CaCO3, K2HPO4, MgSO4, FeSO4 and ZnSO4 as mineral salts. The best pH values for cell biomass production and endotoxin production were 7.0 and 7.5, respectively. The corresponding figures for the best temperature were 37oC and 30oC, respectively. The use of some byproducts such as black-strap molasses, corn-steep liquor and cheese whey, as an alternative for carbon and nitrogen sources of medium, were found to enhance the cell growth but showed no effect on endotoxin production.

Bacterial Contamination and Endotoxin Production in the Water Treatment System for Hemodialysis

Bacterial Contamination and Endotoxin Production in the Water Treatment System for Hemodialysis

Zooplankton interactions with toxic phytoplankton: Some implications for food web studies and algal defence strategies of feeding selectivity behaviour, toxin dilution and phytoplankton population diversity

Abstract This study focuses on the interactions between toxic phytoplankton and zooplankton grazers. The experimental conditions used are an attempt to simulate situations that have, so far, received little attention. We presume the phytoplankton community to be a set of species where a population of a toxic species is intrinsically diverse by the presence of coexisting strains with different toxic properties. The other species in the community may not always be high-quality food for herbivorous zooplankton. Zooplankton populations may have developed adaptive responses to sympatric toxic phytoplankton species. Zooplankton grazers may perform a specific feeding behaviour and its consequences on fitness will depend on the species ingested, the effect of toxins, and the presence of mechanisms of toxin dilution and compensatory feeding. Our target species are a strain of the dinoflagellate Alexandrium minutum and a sympatric population of the copepod Acartia clausi . Mixed diets were used with two kinds of A. minutum cells: non-toxic and toxic. The flagellate Rhodomonas baltica and the non-toxic dinoflagellate Alexandrium tamarense were added as accompanying species. The effect of each alga was studied in separate diets. The toxic A. minutum cells were shown to have negative effects on egg production, hatching success and total reproductive output, while, in terms of its effect on fitness, the non-toxic A. minutum was the best quality food offered. R. baltica and A. tamarense were in intermediate positions. In the mixed diets, copepods showed a strong preference for toxic A. minutum cells and a weaker one for A. tamarense cells, while non-toxic A. minutum was slightly negatively selected and R. baltica strongly negatively selected. Although the level of toxins accumulated by copepods was very similar, in both the diet with only toxic A. minutum cells and in the mixed diet, the negative effects on fitness in the mixed diet could be offset by toxin dilution mechanisms. The implications of these findings are the fact that mesozooplankton may not play an important role in phytoplankton blooms development. Phytoplankton endotoxin production does not seem to be an evolutionary stable strategy as a defence against some herbivores.

The 20-kDa Protein of Bacillus thuringiensis subsp. israelensis Enhances Bacillus sphaericus 2362 Bin Toxin Synthesis

Improving the amount of protein endotoxins synthesized by Bacillus thuringiensis and B. sphaericus per unit of culture medium is important because higher yields typically correlate with higher insecticidal activity per unit weight of spore/toxin mixtures. Higher levels of synthesis can also result in larger crystals that could persist for longer periods in the environment. Improving endotoxin production in B. thuringiensis can be achieved by manipulating genetic elements that regulate protein synthesis at the transcriptional, translational, and even posttranslational levels. In the present study, we used a combination of genetic elements to improve yields of B. sphaericus 2362 binary toxin (Bin) in B. thuringiensis. Our results show that a 20-kDa chaperone-like protein, which occurs as the third open-reading frame in the cry11Aa operon, improves Bin yields when expression of the genes encoding this binary toxin is driven by the native bin promoter, cyt1A promoters, or a novel cyt1A-p/STAB-SD expression system, the latter of which yields maximal levels of Bin synthesis. The 20-kDa helper protein increased Bin toxin levels in B. thuringiensis by as much as 53% and concomitant toxicity by at least 90% when Bin was produced using the cyt1A promoters.

Systemic Warming as an Adjunct to Resuscitation in Peritonitis: A Pilot, Randomized Controlled Trial

Background: Bacterial peritonitis is accompanied by a high risk of sepsis and endotoxin production resulting in physiological derangements and a high mortality rate. Localized and systemic warming improves tissue perfusion, oxygen tension, and outcomes after surgery. The purpose of this study was to examine the effectiveness of systemic warming as an adjunct to standard antibiotic and fluid resuscitation in patients with peritonitis. Methods: In this pilot randomized controlled trial, patients presenting with an acute abdomen were randomized into control and warmed groups using sequential envelopes. Local Ethics Committee approval was obtained. Systemic warming was delivered using the Inditherm warming mattress set at 40°C. Standard oxygen, fluid resuscitation, and antibiotics were delivered simultaneously. Acute Physiology and Chronic Health Evaluation (APACHE) II scores were recorded on admission and 24 h later or just prior to surgery, whichever was earlier. Results: Thirty-three patients were recruited. The APACHE II scores on admission were comparable (median 9.0 [range 2–23] and 9.0 [0–20], respectively, for the control and warmed groups (p = 0.70; Mann-Whitney U test)). No patient showed any adverse effects of warming. There were statistically significant improvements in APACHE II scores (p = 0.028; Wilcoxon signed ranks test) and the magnitude of its change (p = 0.048; Mann-Whitney U test) in the warmed group compared with the control group. Conclusions: Systemic warming may reduce physiological derangements and improve the prognosis in patients with intra-abdominal crisis. The technique may be used safely as an adjunct to standard resuscitation in peritonitis.

Systemic Warming as an Adjunct to Resuscitation in Peritonitis: A Pilot, Randomized Controlled Trial

Bacterial peritonitis is accompanied by a high risk of sepsis and endotoxin production resulting in physiological derangements and a high mortality rate. Localized and systemic warming improves tissue perfusion, oxygen tension, and outcomes after surgery. The purpose of this study was to examine the effectiveness of systemic warming as an adjunct to standard antibiotic and fluid resuscitation in patients with peritonitis. In this pilot randomized controlled trial, patients presenting with an acute abdomen were randomized into control and warmed groups using sequential envelopes. Local Ethics Committee approval was obtained. Systemic warming was delivered using the Inditherm warming mattress set at 40 degrees C. Standard oxygen, fluid resuscitation, and antibiotics were delivered simultaneously. Acute Physiology and Chronic Health Evaluation (APACHE) II scores were recorded on admission and 24 h later or just prior to surgery, whichever was earlier. Thirty-three patients were recruited. The APACHE II scores on admission were comparable (median 9.0 [range 2-23] and 9.0 [0-20], respectively, for the control and warmed groups (p = 0.70; Mann-Whitney U test)). No patient showed any adverse effects of warming. There were statistically significant improvements in APACHE II scores (p = 0.028; Wilcoxon signed ranks test) and the magnitude of its change (p = 0.048; Mann-Whitney U test) in the warmed group compared with the control group. Systemic warming may reduce physiological derangements and improve the prognosis in patients with intra-abdominal crisis. The technique may be used safely as an adjunct to standard resuscitation in peritonitis.

Biofilms in Ear, Nose, and Throat Infections: How Important are They?

Biofilms present a new challenging concept in sustaining chronic, common antibiotic-resistant ear, nose, and throat (ENT) infections. They are communities of sessile bacteria embedded in a matrix of extracellular polymeric substances of their own synthesis that adhere to a foreign body or a mucosal surface with impaired host defense. The aim of this paper is to review the literature on ENT diseases that can be attributed to biofilm formation and to discuss options for future treatment. Literature review from Medline and database sources. Electronic links and related books were also included. Controlled clinical trials, animal models, ex vivo models, laboratory studies, retrospective studies, and systematic reviews. Biofilm formation is a dynamic five-step process guided by interbacterial communicating systems. Bacteria in biofilms express different genes and have markedly different phenotypes from their planktonic counterparts. Detachment of cells, production of endotoxin, increased resistance to the host immune system, and provision of a niche for the generation of resistant organisms are biofilm processes that could initiate the infection process. Effective prevention and management strategies include interruption of quorum sensing, inhibition of related genes, disruption of the protective extrapolymer matrix, macrolides (clarithromycin and erythromycin), and mechanical debridement of the biofilm-bearing tissues. With regard to medical indwelling devices, surface treatment of fluoroplastic grommets and redesign of cochlear implants could minimize initial microbial colonization. As the role of biofilms in human infection becomes better defined, ENT surgeons should be prepared to deal with their unique and tenacious nature.

Pathophysiology of in-vitro induced filaments, spheroplasts and rod-shaped bacteria in neutropenic mice

This study compared the in-vitro properties and in-vivo effects of Escherichia coli filaments, spheroplasts and normal cells in a murine thigh infection model. E. coli was exposed to ceftazidime, meropenem or saline to obtain filaments, spheroplasts or normal bacilli, which were then injected into neutropenic mice. After 24 h, morphology, CFUs, local and circulating endotoxin levels, cytokine levels and mortality were recorded, and correlations between bacterial and host parameters of infection were investigated. Filaments and spheroplasts contained more endotoxin/CFU than controls. Histological studies showed that morphologically altered bacteria changed into rod-shaped cells in the absence of antibiotics. Bacterial spread to the liver was significantly higher in mice challenged with rod-shaped cells, compared with antibiotic-exposed bacteria (p 0.007). Muscle endotoxin levels correlated significantly with circulating interleukin (IL)-6 and tumour necrosis factor (TNF)-alpha, and both pro-inflammatory cytokines were correlated significantly (p 0.011). Despite a tendency toward higher local and systemic concentrations of endotoxin in the filament group, inflammatory responses and survival did not differ between groups. It was concluded that morphologically altered bacteria contain more endotoxin and can regain a rod shape after withdrawal of antibiotics, while non-antibiotic-exposed bacteria show greater spread to the liver. There was a clear intra-individual relationship between local endotoxin, systemic endotoxin, TNF-alpha and IL-6 production, but these parameters did not differ among groups.

Nitrogen Fertility and Planting Date Effects on Lint Yield and Cry1Ac (Bt) Endotoxin Production

Early planted cotton (Gossypium hirsutum L.) and varieties expressing the Bacillus thuringiensis (Bt) gene offer improved yield potential. It is not clear whether the current N recommendations remain appropriate for these new production options. The objectives were to determine how varying rates, application timing, and sources of N affected cotton dry matter partitioning, leaf chlorophyll (Chl) concentration, leaf Bt (Cry1Ac) endotoxin concentration, lint yield, and fiber quality. Four N treatments (112 kg N ha−1 anhydrous; 112 kg N ha−1 liquid; 112/56 kg N ha−1 split; 56/56 kg N ha−1 split) were applied to three cotton varieties (PM 1218BR, STV 4691B, and FM 832) planted on either an early or normal planting date from 2001 through 2004. The N response was consistent across planting dates and varieties for all data collected as shown by the lack of any interactions with these variables. Although N treatments had no effect on lint yield or any dry matter partitioning components, plants receiving the 112/56 kg N ha−1 split application treatment exhibited 14% greater leaf Cry1Ac concentration and a 3% greater leaf Chl concentration than the other N treatments. Early planted cotton had 5% greater leaf Chl concentration but a 12% lower leaf Cry1Ac concentration than normal planted cotton. Lower Cry1Ac levels may reflect enhanced remobilization of the leaf protein to feed the faster developing boll load of the early planted cotton. Early planted cotton yielded 10% more than normal planted cotton because it produced 9% more bolls. Current N recommendations for normal planted cotton also appear sufficient for early planted cotton.

Influence of pH Control Agents on Entomotoxicity Potency of Bacillus thuringiensis using Different Raw Materials

In this investigation, ammonium hydroxide and acetic acid were used as pH control agents during Bacillus thuringiensis (Bt) fermentation in a pilot scale fermentor (150-l) employing two secondary wastewater sludges from two different wastewater treatment plants (CUQS and JQS) and semi-synthetic soybean meal medium as raw materials. Regardless of the cultivation medium, a substantial increase in total cell count, spore count, protease activity and entomotoxicity was achieved when the pH of the culture was controlled using NH4OH/CH3COOH. At harvest, total cell count increased by almost 17%, 33% and 25%; protease activity was enhanced by 12%, 33% and 53% and maximal spore count augmented by almost 28%, 48% and 33% in CUQS, JQS and soybean medium, respectively. Entomotoxicity potency was improved by 22%, 21% and 14% in CUQS, JQS and soybean medium, respectively compared to results obtained with NaOH/H2SO4 as pH control agents. A higher entomotoxicity was also observed using sludge compared to the soybean medium. This improvement of the Bt process performance was a consequence of the addition of rapidly utilizable carbon and nitrogen source through pH control, which stimulated endotoxin production in the crystal and enhanced sporulation.

Microbiological analyses of water from hemodialysis services in São Luís, Maranhão, Brazil

Rigorous control of water quality in hemodialysis services is extremely important in order to guarantee a better quality of life of the patients submitted to this treatment. The lack of adequate water monitoring has caused the death of various patients in the past. The objective of the present study was to determine the physicochemical and bacteriological characteristics of water used by hemodialysis services in hospitals of the city of Sao Luis, Maranhao, Brazil. Bacteriological analyses included the membrane filter method for the determination of total coliform bacteria, the Cult-Dipcombi-TTC-agar method for heterotrophic bacteria and the limulus amebocyte lysate method for the determination of endotoxins. Eighteen water samples obtained from three hospital units, six samples per hemodialysis service, collected directly at the pre- and post-treatment points, were analyzed. Microorganisms were detected in the water used by the hemodialysis services in two of the three hospital units (B and C) studied. No contamination with heterotrophic bacteria was observed in pretreatment samples, while endotoxin production was detected in 100% of the samples. In post-treatment samples, heterotrophic bacteria were detected in 66.6% of the samples and endotoxins in 33.3%. The microorganisms identified in unit B were Burkholderia cepacia, Alcaligenes xylosoxidans,Pseudomonas aeruginosa and Stenotrophomonas maltophilia In unit C Flavimonas oryzihabitans,Ralstonia pickettii and Burkholderia cepacia were identified. A significant correlation was observed between the presence of endotoxins and the physicochemical characteristics of water such as turbidity and conductivity. These data indicate that two of the three hospital units studied should revise the control of their hemodialysis water system.

Role of different dietary fatty acids in the pathogenesis of experimental alcoholic liver disease

Both dietary fatty acids and alcohol play an important role in the pathogenesis of alcoholic liver disease. Findings of studies in rats show a steatogenic role for dietary fat. A role for polyunsaturated fatty acids in alcoholic liver disease is supported by results of studies, which show that pathologic changes occur only in rats fed ethanol with polyunsaturated fatty acids. The mechanisms through which the fatty acids promote alcoholic liver disease include enhanced oxidative stress, production of endotoxin, and increased expression of proinflammatory cytokines.

Platelet-Activating Factor Concentration in the Stool of Human Newborns: Effects of Enteral Feeding and Neonatal Necrotizing Enterocolitis

Epidemiologic studies have identified enteral feedings as a risk factor for necrotizing enterocolitis (NEC). Enteral feedings provide the substrate for colonization of the newborn gut with gram-negative bacteria with endotoxin production, which may trigger the production of endogenous inflammatory mediators, including platelet-activating factor (PAF). In this prospective study, we examined the effect of enteral feeding on PAF concentration in the stool of preterm and full-term human newborns. The concentration of PAF levels in stool was measured at the following times: at passage of first meconium, within 24 h prior to the onset of feedings, at the 3rd and 14th day of feeding and at any time confirmed NEC developed. Stool samples also were analyzed for levels of acetylhydrolase, the PAF breakdown enzyme. Stool PAF concentration rose significantly following the start of enteral feedings. The mean PAF concentration for day 14 samples was significantly higher than the mean concentration of meconium samples (4.90 ± 1.03 vs. 1.81 ± 0.38 ng/g, p < 0.05) and day 0 samples (4.90 ± 1.03 vs. 1.79 ± 0.39 ng/g, p < 0.05). For the 7 patients diagnosed with definite NEC, the mean stool PAF concentration was 12.42 ± 0.77 ng/g, significantly elevated compared to the mean PAF levels in stool from healthy infants at all sampling times (p < 0.01). There was no significant change in acetylhydrolase activity at any of the sampling times. Stool PAF concentration increases with the provision of enteral feedings and rises further with the development of NEC. Since stool acetylhydrolase activity remained unchanged, we speculate the increase of PAF in stool likely represents increased PAF production at the local level following the provision of enteral feedings or the development of neonatal necrotizing enterocolitis.

HPA axis activation and neurochemical responses to bacterial translocation from the gastrointestinal tract.

Stress can cause migration of indigenous bacterial flora from the gut to the peritoneum, a phenomenon known as bacterial translocation. Destruction of the cell walls of gram-negative bacteria can result in the production of endotoxin (lipopolysaccharide, LPS), which is the likely cause of sepsis. Exogenously administered LPS can activate the hypothalamo-pituitary-adrenal (HPA) axis as well as brain noradrenergic and indoleaminergic systems. Thus, it is possible that activations of these systems associated with laboratory stressors in rats and mice could be attributed to bacterial translocation and LPS production. To test this hypothesis we conducted experiments on the time course of bacterial translocation in response to restraint in mice, while measuring HPA and neurochemical responses. These experiments failed to show good correlations between the occurrence of bacterial translocation and HPA and neurochemical activations, suggesting that the later responses were not linked to bacterial translocation. This conclusion was supported by the observation of normal neurochemical responses to restraint in germ-free mice. In further experiments, translocation of Salmonella typhimurium, a bacterium that readily translocates in unstressed animals, was associated with HPA activation and noradrenergic and indoleaminergic responses, indicating that bacterial translocation can indeed activate the HPA axis and brain amines. However, the above experiments suggest that this is not the mechanism by which restraint activates these systems.

Water Treatment in the Home Hemodialysis Setting: Use of Recirculators Decrease Bacteria and Endotoxin Contamination

Water for home hemodialysis is treated using carbon filtration and a series of deionization (DI) tanks. These systems are practical and insure quality product water. The main drawback is susceptibility to bacterial contamination and growth. In an effort to control bacterial growth and endotoxin production in our training rooms and patient homes, our DI systems are being equipped with recirculators consisting of a pump and a flow switch. The pump maintains water in constant recirculation through the DI tanks and lines. This pump was selected to prevent overheating of the water in the system during recirculation, thus helping to prevent bacterial growth. The flow switch is a safety device that stops the pump if the flow rate drops below a preset value while also preventing the pump from overheating should the system develop a leak. The plumbing of this system prevents untreated water from bypassing the DI tanks, while the water quality remains monitored at the product port. We began using recirculators in March of this year in our training rooms. Our results have improved from 7 sets of cultures requiring an action, per AAMI standards, in 8 patient months prior to recirculator installation, to the need to re-sanitize one system, one time since recircultor installation during the ensuing 11 patient months. We currently have 3 recirculator systems (out of 8 DI home systems) in patient homes. One patient on rural water had AAMI action levels with 8 sets of cultures since January, 2002, prior to recirculator installation. He has experienced no action level needs since installation in early August. Aside from home installation problems with the initial patient, recircultors have resulted in no AAMI action levels over the past 6 patient months.

Relationship between endotoxin and prostaglandin (PGE 2 and PGFM) concentrations and ovarian function in dairy cows with puerperal endometritis

Blood concentrations of progesterone, 13,14-dihydro-15-keto-prostaglandin F2alpha (PGFM) and endotoxin, and uterine fluid concentrations of prostaglandin E 2 (PGE 2), PGFM and endotoxin were evaluated in 14 dairy cows with puerperal endometritis (mild ( n=6) and heavy ( n=8)). Endotoxin was measured using a quantitative kinetic assay. Cows with heavy endometritis had significantly higher concentrations of plasma PGFM ( P<0.01) and uterine fluid PGE 2 and endotoxin ( P<0.05) than cows with mild endometritis. Concentrations of PGFM in plasma and uterine fluid, of PGFM and PGE 2, and PGE 2 and endotoxin in uterine fluid were positively and significantly ( P<0.05) correlated. The presence of endotoxin in plasma was detected in one out of six mild and in eight out of eight heavy endometritis cows. Peak plasma endotoxin concentrations (0.08–9.14 endotoxin units/ml (EU/ml) were observed between 1 and 12 days postpartum (pp) and thereafter amounts generally remained below 0.1 EU/ml (last day of detection: Day 27 pp). Abnormal ovarian function was observed in six cows (four with prolonged anoestrus and two with long luteal phase after the first postpartum ovulation). Plasma endotoxin concentrations were detected in the anoestric cows. The results suggest that: (i) concentrations of uterine fluid endotoxin and PGE 2 and of plasma PGFM are related to the degree of endometritis; (ii) absorption of endotoxin from the uterus to the bloodstream occurs, mainly in heavy endometritis cows; and (iii) there is a relationship between uterine infection, endotoxin production and resumption of pp ovarian activity.