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Results for “BARTONELLA INFECTIONS”

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At least 541 records · Page 30Linked to original sources
PubMed2003

Differential expression of the invasion-associated locus B (ialB) gene of Bartonella bacilliformis in response to environmental cues.

Bartonella bacilliformis is the causative agent of the biphasic human disease, Oroya fever. During the primary disease phase, up to 100% of the circulating erythrocytes can be parasitized and 80% lysed. During the secondary phase of this disease, bacterial invasion shifts to endothelial cells lining the vasculature. B. bacilliformis is transferred between human hosts by the sandfly, Lutzomyia verrucarum. To investigate the regulation of ialB by environmental cues signaling vector-to-host transmission; nuclease protection assays were performed to compare the amount of ialB mRNA in bacteria subjected to temperature shift, pH change, oxidative stress, or hemin limitation. The amount of ialB mRNA increased by 223-310% in acid-treated samples and decreased by 28-39% in base-treated samples as compared to bacteria kept at pH 7.2. B. bacilliformis samples showed a 56-63% and 74-80% decrease in ialB mRNA when shifted to 37 degrees C from growth temperatures of 20 and 30 degrees C, respectively. Oxidative stress (1 mM H(2)O(2)) and hemin limitation had no significant effect on mRNA levels. Determination of IalB protein amounts using SDS-PAGE and immunoblotting showed the greatest amounts of IalB under acidic conditions or at 20 degrees C. The least amount of IalB was synthesized under basic conditions or at 37 degrees C. The viability of wild-type B. bacilliformis under the various experimental culture conditions was determined and found not to affect ialB mRNA amounts in these experiments. Finally, we compared the survival of wild-type and ialB mutant B. bacilliformis and found no difference in the viability of these two strains, demonstrating that IalB does not aid bacterial survival under these conditions.

Acid Anhydride Hydrolases↗
PubMed2000

Bartonellosis. New and old.

The number of species that comprise the family of Bartonellaceae, genus Bartonella, has recently increased from one to 11 species, five of which have been associated with different diseases and syndromes in humans. The rapidly growing number of human pathogens has led several investigators to regard bartonellosis and other associated syndromes as important emerging infectious diseases. This article presents the history and epidemiology, clinical features, diagnosis, and treatment of bartonellosis and associated diseases, including Carrión's disease, trench fever, endocarditis and bacteremia, bacillary angiomatosis, and cat-scratch disease.

Bartonella↗
PubMed2001

TREM-1 amplifies inflammation and is a crucial mediator of septic shock.

Host innate responses to bacterial infections are primarily mediated by neutrophils and monocytes/macrophages. These cells express pattern recognition receptors (PRRs) that bind conserved molecular structures shared by groups of microorganisms. Stimulation of PRR signalling pathways initiates secretion of proinflammatory mediators, which promote the elimination of infectious agents and the induction of tissue repair. Excessive inflammation owing to bacterial infections can lead to tissue damage and septic shock. Here we show that inflammatory responses to microbial products are amplified by a pathway mediated by triggering receptor expressed on myeloid cells (TREM)-1. TREM-1 is an activating receptor expressed at high levels on neutrophils and monocytes that infiltrate human tissues infected with bacteria. Furthermore, it is upregulated on peritoneal neutrophils of patients with microbial sepsis and mice with experimental lipopolysaccaride (LPS)-induced shock. Notably, blockade of TREM-1 protects mice against LPS-induced shock, as well as microbial sepsis caused by live Escherichia coli or caecal ligation and puncture. These results demonstrate a critical function of TREM-1 in acute inflammatory responses to bacteria and implicate TREM-1 as a potential therapeutic target for septic shock.

Animals↗
PubMed1999

Microbes and sequestered substances as mechanisms for disease: Bartonella and L-forms as common global etiological agents.

The pathogenicity of microbes may be determined by substances sequestered from blood and bound to their constituent lipid. The brain may not perceive substances sequestered by microbes, to interfere with control to maintain normal levels. Pathological conditions can be induced as organisms exposed to antimicrobial substances/conditions and/or deprived of nutrients essential to cell wall synthesis, disintegrate to free lipid-bound compounds and produce L-forms that can deplete nutrients as they revert to bacteria. Microbes may act as active carriers for the continuing interaction of sequestered substances. Changes in the molecular structure of substances effected during sequesteration could cause them to be seen as substances 'synthesized' by an organism. In media that contain substances to inhibit 'contaminants', L-forms can be seen as mycoplasma. Elementary bodies of L-forms with a specific substance or tissue affinity may be seen as 'receptors'. Bartonella are global agents for disease--pleomorphic organisms (description suits Proteus)--and they can be seen as 'contaminants'.

Bartonella↗
PubMed2001

Excessive tumor-elaborated VEGF and its neutralization define a lethal paraneoplastic syndrome.

Vascular endothelial growth factor (VEGF) is a potent endothelial cell mitogen and key regulator of both physiologic and pathologic (e.g., tumor) angiogenesis. In the course of studies designed to assess the ability of constitutive VEGF to block tumor regression in an inducible RAS melanoma model, mice implanted with VEGF-expressing tumors sustained high morbidity and mortality that were out of proportion to the tumor burden. Documented elevated serum levels of VEGF were associated with a lethal hepatic syndrome characterized by massive sinusoidal dilation and endothelial cell proliferation and apoptosis. Systemic levels of VEGF correlated with the severity of liver pathology and overall clinical compromise. A striking reversal of VEGF-induced liver pathology and prolonged survival were achieved by surgical excision of VEGF-secreting tumor or by systemic administration of a potent VEGF antagonist (VEGF-TRAP(R1R2)), thus defining a paraneoplastic syndrome caused by excessive VEGF activity. Moreover, this VEGF-induced syndrome resembles peliosis hepatis, a rare human condition that is encountered in the setting of advanced malignancies, high-dose androgen therapy, and Bartonella henselae infection. Thus, our findings in the mouse have suggested an etiologic role for VEGF in this disease and may lead to diagnostic and therapeutic options for this debilitating condition in humans.

Animals↗
PubMed2002

Prevalence of antibodies to Bartonella henselae, B. elizabethae and B. quintana in Swedish domestic cats.

Sera from 292 cats were analyzed by means of indirect immunofluorescence for antibodies to Bartonella henselae, B. quintana and B. elizabethae. The sera were sent to the Swedish National Institute of Veterinary Medicine for health monitoring and were tested retrospectively for antibodies to Bartonella. The most prevalent antibodies (25%) reacted with the B. elizabethae antigen. Cats with such antibodies were older than those without antibodies. The prevalence of antibodies to B. elizabethae was higher in the south of Sweden than in the north, with the highest prevalence (46%) being found in cats living in the Stockholm region. There was no difference in sex distribution. A low prevalence (1%) of antibodies to B. henselae was found and no sera reacted with B. quintana. The high prevalence of antibodies to B. elizabethae is consistent with previous findings in Swedish patients. The small number of cats with B. henselae antibodies observed in this study could be due to the cold climate and the low occurrence of cat fleas in Sweden.

Aging↗
PubMed2001

Serological and epidemiological analysis of the prevalence of Bartonella spp. antibodies in Swedish elite orienteers 1992-93.

The emergence of the popular, physically demanding and highly nature-interactive sport of orienteering was marked in Sweden by an elevated rate of sudden unexpected cardiac deaths in young competitors during the years 1979-92, with a common underlying cause or causes suspected. Subsequently, sera were collected during 1992-93 from the elite segment of orienteers holding a nationally ranked position, and a survey compiling various epidemiological data was performed. In this study, a total of 1136 sera were analyzed by indirect-fluorescent antibody assay for the presence of IgG antibodies against 3 Bartonella spp.: B. henselae, B. elizabethae and B. quintana. In total, 31% (355/1136) were seropositive for at least 1 species of Bartonella, with titers ranging up to 1/512; 350/1136 (31%) had antibodies against B. elizabethae, 34/1136 (3.0%) against B. henselae and 16/1136 (1.4%) against B. quintana. Males and females showed equal rates of 31% seropositisity to Bartonella spp. (males 241/766; females 114/370). In comparison, 322 time-matched sera from healthy blood donors had antibodies to Bartonella spp. in 6.8% of cases (p < 0.001). The observed high prevalence of Bartonella spp. antibodies found in Swedish elite orienteers may be indicative of a connection with risk factors for the development of myocarditis and sudden unexpected cardiac death.

Adolescent↗
PubMed2004

Lack of Bartonella sp. in 167 Ixodes ricinus ticks collected in central Sweden.

Sudden death in Swedish orienteers was demonstrated to be significantly associated with antibodies to Bartonella sp. To test if these antibodies could be related with tick exposure, we searched Bartonella sp. in Ixodes ricinus ticks using specific PCR amplification and culture. No Bartonella sp. was detected in 167 ticks tested.

Animals↗