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PubMed2000

Colonic food: pre- and probiotics.

The colonic mucosa is unable to nourish itself from the blood. Instead, its nutritive demand must be met from the lumen, where different nutrients, short-chain fatty acids, amino acids, polyamines, growth factors, vitamins, and antioxidants are produced by a nonpathogenic (commensal, so-called "protective" probiotic) flora. The substrates for the production of nutrients are usually referred to as prebiotics, which consist mainly of ingested fibers and complex proteins (colonic food), but may also include necrotic mucosal cells, mucus, gastrointestinal (GI) secretions, and bacteria (as well as yeasts broken down by the bacteria). A characteristic common to all foods destined for the colon--colonic foods-is that no enzymes in the small intestine are capable of breaking them down. It is recommended that a minimum of 10% of ingested calories and about 20% of the food volume should be colonic food. The probiotic flora is today often found deficient, especially in industrialized nations. Studies have shown that Lactobacillus plantarum can preserve key nutrients, vitamins, and antioxidants; eliminate toxic components from food; protect food from decay; and eradicate pathogens such as Enterobacteriaceae, S. aureus, and enterococci from fermented food. In addition, it has demonstrated effectiveness over other bacteria in the metabolism of semiresistant oligofructans. L. plantarum-fermented oat given to healthy volunteers significantly reduces the gut content of potentially pathogenic microorganisms (PPMs).

Animals↗
PubMed2002

Sources of pathogens causing pleuropulmonary infections after lung cancer resection.

OBJECTIVE: The source of pathogens responsible for pleuropulmonary complications after lung resection is not yet completely understood, yet knowing this source is very important for proper perioperative use of antibiotics in lung surgery. We studied prospectively the value of sputum samples -- collected 3 days before and 3 days after surgery -- and of intraoperative bronchial swabs in the diagnosis of infective pulmonary complications following lung cancer resection. METHODS: In a prospective trial, we studied 194 patients (18 women and 176 men, age range 34-79 years, mean 57 years) who were operated on for lung cancer. The infection screen consisted of intraoperative bronchial swabs, and sputum samples obtained prior to and 3 days after surgery. Before the operation, all patients were free of clinical signs of respiratory infection. In patients with postoperative infection, causative pathogens were identified from sputum, tracheal aspirate, thoracic puncture and thoracic drainage fluids. RESULTS: Thirty-four patients suffered from 32 pleuropulmonary infections, and two from wound infection. Pathogenic organisms were isolated from preoperative and postoperative sputum samples and from intraoperative bronchial swabs in 50, 64 and 27% of patients, respectively. Postoperative infective complications were caused by gram-negative bacteria and Candida albicans in 75% of patients. These potential pathogens were recovered from preoperative sputum samples and from intraoperative bronchial swabs in only 18 and 13% of cases, but from postoperative sputum samples in 63% of cases. A strong correlation in identified pathogens was found between the postoperative sputum samples and the samples collected for microbiological diagnosis of subsequent postoperative infective complications (P<0.01). CONCLUSIONS: Our results indicate that pathogens that cause pleuropulmonary infective complications are probably acquired postoperatively from the patient's oral cavity, pharynx and hypopharynx. Appropriate antibiotic prophylaxis is discussed.

Adult↗
PubMed2001

Beyond the specific plaque hypothesis: are highly leukotoxic strains of Actinobacillus actinomycetemcomitans a paradigm for periodontal pathogenesis?

Actinobacillus actinomycetemcomitans is a facultative anaerobe implicated in a variety of periodontal diseases. Its presence is most closely associated with localized juvenile periodontitis (LIP), although the exact role of the organism in this and other periodontal diseases is not entirely clear. While A. actinomycetemcomitans produces several different putative virulence factors, the most widely studied is the leukotoxin. The leukotoxin selectively kills polymorphonuclear leukocytes and macrophages in vitro, constituting the host's first line of defense. Interestingly, even though all strains of A. actinomycetemcomitans have the genes encoding the leukotoxin, there is variability in leukotoxin expression. Differences in the structure of the promoter region of the leukotoxin gene operon were shown to correlate directly with levels of leukotoxin production. Highly leukotoxic forms appear to exhibit increased pathogenic potential, as evidenced by recent studies that have shown a significant association between the prevalence of such strains and the occurrence of LIP in several different populations. This represents the first demonstration of an association between a particular subset of a pathogenic species and a specific periodontal disease. Early identification of A. actinomycetemcomitans by microbial and genetic assays to evaluate leukotoxicity may enhance the efficacy of preventive and/or therapeutic techniques. Future investigations should continue to evaluate pathogenic variations of additional virulence factors expressed in vivo, not only of A. actinomycetemcomitans, but also of other periodontal bacteria and infectious disease pathogens.

Aggregatibacter actinomycetemcomitans↗
PubMed2003

Functional analysis of an arthritogenic synovial fibroblast.

Increasing attention has been directed towards identifying non-T-cell mechanisms as potential therapeutic targets in rheumatoid arthritis. Synovial fibroblast (SF) activation, a hallmark of rheumatoid arthritis, results in inappropriate production of chemokines and matrix components, which in turn lead to bone and cartilage destruction. We have demonstrated that SFs have an autonomous pathogenic role in the development of the disease, by showing that they have the capacity to migrate throughout the body and cause pathology specifically to the joints. In order to decipher the pathogenic mechanisms that govern SF activation and pathogenic potential, we used the two most prominent methods of differential gene expression analysis, differential display and DNA microarrays, in a search for deregulated cellular pathways in the arthritogenic SF. Functional clustering of differentially expressed genes, validated by dedicated in vitro functional assays, implicated a number of cellular pathways in SF activation. Among them, diminished adhesion to the extracellular matrix was shown to correlate with increased proliferation and migration to this matrix. Our findings support an aggressive role for the SF in the development of the disease and reinforce the perspective of a transformed-like character of the SF.

Adjuvants, Immunologic↗
PubMed1991

Rhodococcus equi--an easily missed opportunistic pathogen.

Over the last 10 years Rhodococcus equi has been identified as an important, albeit very rare, opportunistic pathogen. As the number of patients immunocompromised from HIV infection grows, this microorganism will likely become of increasing clinical importance. Infection with R. equi is usually insidious, causing progressive pulmonary disease that is typically pleural based at the time of microbiological diagnosis. As in the case we present, the clinical and microbiological diagnoses may be significantly delayed, either by the common pitfalls encountered in the laboratory identification of R. equi, or by the failure to recognize the pathogenic potential of the isolate. R. equi infection should be suspected in immunocompromised patients with pneumonia, when a pure or predominant growth of aerobic, non-sporeforming gram-positive bacilli is found on cultures of bronchoalveolar lavage fluid and other pulmonary pathogens have been excluded.

Actinomycetales Infections↗
PubMedDate not supplied

The occurrence of Clostridium perfringens in the intestine of chicks.

Commercial broiler chicks brooded either on wire or on used or new litter demonstrated a 75% (62/75) incidence of recovery of "perfringens-like" colonies from the intestine during a 5-week period. Eleven Clostridium spp. were identified from among these "perfringens-like" organisms, which were cultured on SPS selective agar medium. Clostridium perfringens was positively identified only infrequently (five isolates) from among the "perfringens-like" colonies. In contrast, "perfringens-like" colonies were not recovered from the intestinal contents of specific-pathogen-free chicks reared in an isolation unit. However, C. perfringens was isolated from the yolk sac of one embryonated egg and from the intestine of a single 7-day-old chick, indicating the possibility of vertical transmission of this potential pathogen.

Animal Feed↗
PubMed1984

Characteristics of I and i antigen receptors on the membrane of erythrocytes in sickle cell anemia.

In this study we employed two approaches in attempts to explain the increased expression of I and i antigens on the membrane surface of SS erythrocytes: immunoelectron microscopy and measurements of antigen-antibody affinity. AA and SS erythrocytes were first reacted with anti-I or anti-i antisera, and then with ferritin-conjugated anti-human IgM. With both antibodies, proportions of cells labeled and ferritin-cluster density on labeled cells were greater for SS erythrocytes at a high level of significance. Studies on the temperature dependence of agglutination by anti-I provided the association constants of agglutination, which were uniformly greater for SS erythrocytes. I and i antigen determinants are carried principally on band 3, the major transmembrane protein of the erythrocyte membrane. Therefore, for SS erythrocytes, the increased I (and i) antigen density and the increased association constant of agglutination by anti-I very likely both reflect the same phenomenon: a relatively greater exposure of I (and i) antigen determinant sites at the membrane surface. Any deviation from normal at the exterior surface of the erythrocyte membrane deserves to be suspect for potential pathogenicity, because this is the cell's region of intimate contact with other elements of the circulation. In addition to enhancing susceptibility of SS erythrocytes to cold agglutinins, an altered exposure of band 3 at the membrane outer surface has the potential for accelerating recognition and removal of SS erythrocytes from the circulation by mononuclear phagocytes.

Agglutination Tests↗
PubMed2006

Mutation, selection, and evolution of the Crohn disease susceptibility gene CARD15.

Three common mutations in the CARD15 (NOD2) gene are known to be associated with susceptibility to Crohn disease (CD), and genetic data suggest a gene dosage model with an increased risk of 2-4-fold in heterozygotes and 20-40-fold in homozygotes. However, the discovery of numerous rare variants of CARD15 indicates that some heterozygotes for the common mutations have a rare mutation on the other CARD15 allele, which would support a recessive model for CD. We addressed this issue by screening CARD15 for mutations in 100 CD patients who were heterozygous for one of the three common mutations. We also developed a strategy for evaluating potential disease susceptibility alleles (DSAs) that involves assessing the degree of evolutionary conservation of involved residues, predicted effects on protein structure and function, and genotyping in a large sample of cases and controls. The evolutionary analysis was aided by sequencing the entire coding region of CARD15 in three primates (chimp, gibbon, and tamarin) and aligning the human sequence with these and orthologs from other species. We found that 11 of the 100 CD patients screened had a second potential pathogenic mutation within the exonic and periexonic sequences examined. Assuming that there are no additional pathogenic mutations in noncoding regions, our study suggests that most carriers of the common DSAs are true heterozygotes, and supports previous evidence for a gene dosage model. Four novel nonsynonymous mutations were detected, one of which would produce premature termination of translation c.2686C>T (p.Arg896X). Two potential DSAs--c.2107C>T (p.Arg703Cys) and g.2238T>A (c.74-7T>A)--were significantly associated with CD in the case control sample. Analysis of the evolution of CARD15 revealed strong conservation of the encoded protein, with identity to the human sequence ranging from 99.1% in the chimp to 44.5% in fugu. Higher primates possess an open reading frame (ORF) upstream of the putative initiation site in other species that encodes a further 27 N-terminal amino acids, while four regions of high conservation are observed outside of the known domains of CARD15, indicative of additional residues of functional importance. The strategy developed here may have general application to the assessment of mutation pathogenicity and genetic models in other complex disorders.

Alleles↗
PubMed2001

Survival and characterization of Escherichia coli strains in a typical Mexican acid-fermented food.

In this study, the presence and pathogenic characteristics of Escherichia coli strains in pozol, an acid-fermented maize beverage consumed in South-eastern Mexico, were determined. Seventy-three E. coli strains were isolated at early and late times (6 and 48 h) during the pozol fermentation process, when pH values of the doughs were 6.7-4.7 (6 h) and 4.7-3.7 (48 h). Serotypes that belong to diarrheagenic E. coli serogroups O18, O88, O8, O11, O20, O173 were identified. HEp-2 cell adherence in vitro assays showed localized, diffuse and aggregative adherence patterns among some of these strains. A DNA colony hybridization analysis with different probes showed the presence of virulence genes related to diarrheal pathogenesis. Thirty-three percent of the E. coli strains were tetracycline-resistant and 95% had a 20 kb plasmid. The presence and survival of potentially pathogenic E. coli in acid-fermented pozol suggest that such foods may be a potential source of foodborne outbreaks.

Bacterial Adhesion↗
PubMed1995

The utility of annual surveillance bronchoscopy in heart-lung transplant recipients.

Bronchoscopy with transbronchial biopsy (TBBx) and bronchoalveolar lavage (BAL) has an appreciable yield in detecting asymptomatic abnormalities in heart-lung transplant recipients (HLTR) during the early postoperative period. The utility of annual surveillance procedures has not been critically evaluated. We reviewed all annual bronchoscopies performed on 29 HLTR to determine the frequency of asymptomatic abnormalities. Surveillance bronchoscopies (SB) were performed on asymptomatic subjects with unchanged lung function compared with baseline. Surveillance/clinical bronchoscopies (SCB) were those performed in patients with stable decrements in lung function. Nineteen patients underwent 48 SB and 8 had 18 SCB. Five of 15 (33%) SB performed at one year yielded an abnormal TBBx (1 grade 2 acute rejection [AR], 1 grade 1 AR, 1 grade 1 AR with obliterative bronchiolitis [OB] and 2 Pneumocystis carinii pneumonia). At 2 or more years, TBBx was abnormal in 2 of 33 (6%, p = 0.024 compared with first year TBBx) (1 grade 1 AR, 1 lymphocytic bronchiolitis). Pathogens were identified in BAL in 19 (40%) SB. Fourteen (78%) SCB were abnormal. Nine (50%) revealed an abnormal TBBx (all OB), but only 2 (11%) of these altered patient management. Seven (39%) demonstrated pathogens in BAL. We conclude that in HLTR (1) surveillance TBBx rarely yields positive findings 2 or more years posttransplant, (2) surveillance TBBx seldom alters management in patients with stable decrements in lung function, and (3) BAL is useful to screen for potential pathogens.

Adolescent↗
PubMed1999

Canine coronavirus infections in Japan: virological and epidemiological aspects.

Ten strains, eight field and two reference laboratory strains, of canine coronavirus (CCV) were comparatively examined with respect to antigenic relationships and pathogenic potential in dogs. With monoclonal antibodies and hyperimmune antisera to feline coronavirus and CCV, respectively, varying degrees of antigenic diversities were found among the strains by neutralization and immunofluorescence assays, but it was felt that they belong to one serotype. Specific-pathogen-free puppies experimentally inoculated with some CCV strains manifested clinical symptoms, but there was a difference in their virulence. In order to elucidate the prevalence of CCV infections in dogs in Japan, we tested for neutralizing antibodies to CCV in 467 field dogs, and found a prevalence of 44.1%. Moreover, by using nested reverse transcriptase-polymerase chain reaction on rectal swabs of 100 diarrheic dogs recently presented in veterinary clinics, evidence of CCV in 16% of these specimens was found. The results suggested that CCV infection is more widespread than expected in dogs, and that CCV is a significant etiologic factor in canine diarrhea also in Japan.

Animals↗
PubMed2006

Yersinia enterocolitica isolates of differing biotypes from humans and animals are adherent, invasive and persist in macrophages, but differ in cytokine secretion profiles in vitro.

Previous epidemiological studies have demonstrated a potential link between the serotypes of Yersinia enterocolitica recovered from cattle, sheep and pigs and those isolated from human disease cases. Further studies utilizing amplified fragment length polymorphisms have shown a relationship at the genetic level between strains of biotypes 3 and 4 from humans and livestock, and also suggested that some biotype 1A isolates, classically defined as non-pathogenic, are closely related to biotype 3 and 4 isolates. This study sought to understand further the pathogenic potential of Y. enterocolitica isolates from livestock in Great Britain. A range of surrogate in vitro models, such as invasion of epithelial tissue cultures, survival in cultured macrophages and cytokine secretion response, was employed to assess the pathogenicity of 88 strains. The results suggested that all isolates examined were capable of adhering to and invading epithelial cells and of surviving within macrophages. However, the inflammatory response of the infected macrophages differed with the infecting Y. enterocolitica subtype, with the response to pathogenic biotype 3 and 4 isolates different to that observed with biotype 1A isolates, and with the biotype 3 O : 5,27 isolates recovered exclusively from animals. Infections of porcine tissue also suggested the possibility of host-tissue tropism within Y. enterocolitica subtypes.

Animals↗
PubMed1998

A pathogenic threshold of virus load defined in simian immunodeficiency virus- or simian-human immunodeficiency virus-infected macaques.

To determine if a specific pathogenic threshold of plasma viral RNA could be defined irrespective of virus strain, RNA levels in the plasma of more than 50 infected rhesus macaques (Macaca mulatta) were measured. Animals were inoculated intravenously with either simian immunodeficiency virus (SIV) or simian-human immunodeficiency virus (SHIV) strains of known pathogenic potential (SIV8980, SIVsmm-3, SIVmac32H/J5, SIVmac32H/1XC, reverse transcriptase-SHIV, SHIV89.6p) or with attenuated strains (SHIVW6.1D, SHIVsf13, SHIVhan-2, SIVmacDeltanef, SHIVsf33). In animals inoculated with nonpathogenic strains, shortly after the primary peak of viremia viral RNA levels declined and remained below 10(4) RNA equivalents/ml of plasma between 6 and 12 weeks postinoculation. Animals infected with documented pathogenic strains maintained viral RNA levels higher than 10(5) RNA equivalents/ml of plasma. In animals infected with strains with low virulence, a decline in plasma RNA levels was observed, but with notable individual variation. Our results demonstrate that the disease-causing potential was predicted and determined by a threshold plasma virus load which remained greater than 10(5) RNA equivalents/ml of plasma 6 to 12 weeks after inoculation. A threshold virus load value which remained below 10(4) RNA equivalents/ml of plasma was indicative of a nonpathogenic course of infection.

Animals↗
PubMed2006

Mycological assessment of sediments in Ligurian beaches in the Northwestern Mediterranean: pathogens and opportunistic pathogens.

Sediments of five Ligurian beaches in compliance with European Union bathing water regulations were studied based on the characteristics of the fungal assemblage during the tourism season. Among the 179 taxa of filamentous fungi isolated, 120 were opportunistic pathogens, such as Acremonium sp., and the genus Penicillium was also present as the pathogenic species P. citrinum. Furthermore, 5% of the total filamentous fungi belonged to the dermatophyte genus Microsporum, whose species can cause mycoses. Beach sediments showed elevated densities of opportunistic pathogens, of pathogenic filamentous fungi, and of yeasts during the tourism season. Although monitoring of beach sediments for microbiological contamination is not mandatory, and disease transmission from sediments has not yet been demonstrated, our study suggests that beach sediments may act as a reservoir of potential pathogens, including fungi. In addition, the mycoflora displayed high sensitivity to critical environmental situations in the beaches studied. Therefore, the fungal community can be a useful tool for assessing the quality of sandy beaches in terms of sanitary and environmental quality.

Analysis of Variance↗
PubMed1985

Controversies in the pathophysiology and fluid management of postoperative adult respiratory distress syndrome.

Physiologic changes that lead to the development of ARDS begin with the precipitating shock syndrome. Hypovolemia, pulmonary vasoconstriction, reduced myocardial performance, and diminished O2 transport typically precede the development of clinical ARDS after hemorrhage, trauma, postoperative conditions, and sepsis. Since shock lung is a complication of shock, it is not surprising that the antecedent clinical and physiologic events that characterize the shock state may be determinants of both the genesis and the outcome of ARDS. Postoperative ARDS follows unrecognized or inadequately treated hypovolemia and hypoxia during an antecedent period of preoperative or intraoperative shock. Hypovolemia and hypoxia increase cardiac and ventilatory drive and stimulate neurohumoral mechanisms to increase pulmonary vasoconstriction. The last-named, when extensive and uneven, produces maldistribution of flow and reduces DO2 and VO2. Subsequently, mediator-induced pulmonary vasoconstriction increases the problem. When sufficiently extensive, these antecedent physiologic alterations culminate in ARDS. With impaired flow and O2 transport, pathogenic mechanisms of ARDS and acute renal failure may be set in motion; further, the naturally occurring immune mechanisms may be impaired and may lead to associated infection. There are at least six redistributions that are major pathophysiologic influences in ARDS. They are uneven ventilation throughout the lung; redistribution of regional pulmonary blood flow between zones due to gravity; nonuniform pulmonary blood flow between individual metarteriolar-capillary networks because of local vasoconstriction; uneven systemic blood flow between organs; irregular systemic blood flow at the microcirculatory level, producing inadequate nutritional flow to the tissues; and redistribution of body water, leading particularly to fluid accumulation in the extracellular compartment, with expanded interstitial space and contracted plasma volume (hypovolemia). Pathogenic roles have been implicated for capillary leak, surfactant synthesis, erythrocyte and platelet aggregation, leukocyte margination in the pulmonary circulation, complement and kinin cascades, neurohumoral responses, histamine, serotonin, vasoactive peptides, and the metabolic products of arachidonic acid breakdown in pulmonary vessels. However, these potential pathogenic influences have yet to be described in terms of their temporal relationships to the natural physiologic history of ARDS; nor have their roles been evaluated in terms of mechanistic interrelationships.(ABSTRACT TRUNCATED AT 400 WORDS)

Blood Transfusion, Autologous↗
PubMed1991

Enhanced siderophore production and mouse kidney pathogenicity in Escherichia coli grown in urine.

Fifteen siderophore producing urinary isolates of Escherichia coli were compared for aerobactin and enterochelin production in trypticase soy broth and pooled normal human urine. Significant increase in siderophore production (both phenolate and hydroxamate) was observed when organisms were grown in urine. Mouse kidney pathogenic potential of the strains grown in urine was compared with that of bacteria grown in trypticase soy broth in an ascending model of pyelonephritis in female Swiss Webster mice. Organisms grown in urine and instilled into a mouse bladder demonstrated markedly enhanced renal pathogenicity (p less than 0.01). Further information about the influence of urinary constituents on siderophore production could help in understanding the pathogenesis of pyelonephritis.

Animals↗
PubMed2000

Oligandrin. A proteinaceous molecule produced by the mycoparasite Pythium oligandrum induces resistance to Phytophthora parasitica infection in tomato plants.

A low-molecular weight protein, termed oligandrin, was purified to homogeneity from the culture filtrate of the mycoparasitic fungus Pythium oligandrum. When applied to decapitated tomato (Lycopersicon esculentum Mill. var. Prisca) plants, this protein displayed the ability to induce plant defense reactions that contributed to restrict stem cell invasion by the pathogenic fungus Phytophthora parasitica. According to its N-terminal sequence, low-molecular weight, acidic isoelectric point, ultraviolet spectrum, and migration profile, the P. oligandrum-produced oligandrin was found to share some similarities with several elicitins from other Phytophthora spp. and Pythium spp. However, oligandrin did not induce hypersensitive reactions. A significant decrease in disease incidence was monitored in oligandrin-treated plants as compared with water-treated plants. Ultrastructural investigations of the infected tomato stem tissues from non-treated plants showed a rapid colonization of all tissues associated with a marked host cell disorganization. In stems from oligandrin-treated plants, restriction of fungal growth to the outermost tissues and decrease in pathogen viability were the main features of the host-pathogen interaction. Invading fungal cells were markedly damaged at a time when the cellulose component of their cell walls was quite well preserved. Host reactions included the plugging of intercellular spaces as well as the occasional formation of wall appositions at sites of potential pathogen entry. In addition, pathogen ingress in the epidermis was associated with the deposition of an electron-opaque material in most invaded intercellular spaces. This material, lining the primary walls, usually extended toward the inside to form deposits that frequently interacted with the wall of invading hyphae. In the absence of fungal challenge, host reactions were not detected.

Algal Proteins↗
PubMed1966

Studies on natural gastric flora. I. Bacterial flora of fasting human subjects.

The presence and survival of ingested micro-organisms, both pathogenic and commensal, is of practical interest because the stomach is one of the principal portals of entry of bacteria in humans. A study of the environmental factors governing the survival of indigenous flora in the gastric lumen will assist in determining whether potentially pathogenic organisms will survive in the stomach and pass on. The authors set out to determine the significance of gastric mucin in such survival, with the ultimate objective of learning what factors provide optimal bactericidal conditions.Samples of gastric juice were aspirated from 149 fasting individuals; samples of saliva, nose and throat swabs were also obtained. Positive gastric cultures were found in 82%. The study of the effects of gastric pH demonstrated an increase in the number of samples showing growth above pH 2.0 and a concomitant increase in total bacterial growth. At a pH lower than 2.0, certain organisms are selected out. It appears that even minor changes in gastrointestinal physiology disrupt the normal clearing of the flora.

Adolescent↗