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Results for “pathogenic mechanisms”

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At least 19 recordsLinked to original sources
PubMed1975

Pathogenic mechanisms not operating in Eimeria necatrix infections.

Having investigated certain aspects of Eimeria necatrix coccidiosis in chickens, workers of the Hannover Veterinary School postulated "that death following a single inoculation of a large number of oocysts is due to an alarm reaction and not a specific pathogenic action of the parasites". Because this hypothesis is somewhat revolutionary in its consept, several pieces of evidence on which it is based and several logical deductions which can be made from it have been examined. It has been confirmed that injection of chichens with cysteamine or 5-hydroxytryptamine 30 min before inoculation of the birds with a lethal dose of E. necatrix oocysts reduces subsequent mortality; the reason for this, however, appears not to be the neutralisation of the proposed shock reaction, but rather an inhibition of the excystation process, brought about indirectly through the host. Inoculation of chickens with a non-lethal dose of E. necatrix oocysts 30 min before inoculation with a lethal dose of oocysts was followed by increased mortality rather than the decreased mortality which the hypothesis would predict. Treatment of chickens with sulphadimidine starting 48 h after inoculation resulted in survival of the birds rather than death which would ensue if in fact mortality was due to a shock reaction irreversibly initiated at the time of inoculation. A direct effect of sulphadimidine on the parasite has been shown both in vivo and in vitro.

Adrenocorticotropic Hormone↗
PubMed1977

[Glucide intolerance and its pathogenic mechanisms during parenteral feeding].

Hyperglycaemia during parenteral alimentation occurs either as a result of an error in the supplies provided or as a result of diminished carbohydrate tolerance. The circumstances surrounding the development of carbohydrate intolerance are essentially : severe infections, major catabolic states, renal insufficiency, extensive burns, pancreatic problems and diabetes. From a pathogenic standpoint, there are two dominant elements : disturbances in hepatic gluconeogenesis and changes in insulin secretion and in resistance to insulin. The physiopathology is dominated by the risk of hyperosmolarity. Hypoglycaemia occurs most frequently as the result of a manit fest error : too sudded interruption of carbohydrate supplies or two high dosage of exogenous insulin.

Blood Glucose↗
PubMed2026

Glial Connexin-43 Is a Pathogenic Mechanism Promoting Gut Inflammation in Postoperative Ileus Induced by Gut Surgical Manipulation With Potential Relevance to Humans.

BACKGROUND & AIMS: Abdominal surgery often precipitates postoperative ileus (POI), a frequent and severe gastrointestinal (GI) motility disorder, through mechanisms that involve intestinal inflammation. Emerging data show that enteric glia acquire a reactive phenotype that aggravates POI, but how glia exert this effect remains unclear. Enteric glia express connexin-43 hemichannels (gCx43), which are implicated in neurological and inflammatory disorders. Thus, we aimed to decipher contributions of glial connexin-43 (Cx43) in the pathophysiology of POI. METHODS: We induced POI in mice using in vivo intestinal manipulation and used glial Cx43cKO (Sox10CreERT2;Cx43fl/fl) or RiboTag (Sox10CreERT2/Rpl22HA/+) mice to evaluate Cx43-dependent signaling. Human enteric glial cultures (hEGC) and muscularis externa obtained during intestinal surgery translated findings to patients. Transcriptome analysis, immunofluorescence co-labeling, Western blots, and Cx43 hemichannel activation were used for quantitative analysis. RESULTS: Cx43 is the highest expressed connexin in enteric glia in mice and humans. Up-regulation of Cx43 occurs in various disease models linked to POI, GI surgical trauma, inflammation, immune cell activation, and enteric gliosis. In the mouse POI model, glial Cx43-deletion reduces glial reactivity, pro-inflammatory signals, upregulates host protection genes, regulates immune cell activation, and prevents enteric neuropathy. In hEGCs, interleukin (IL)-1β induction opens Cx43 and stimulates release of IL-6 and C-C motif ligand 2 (CCL2). The Cx43 peptide inhibitor, 43Gap26, inhibits glial Cx43 activation, reduces IL-6 release, and blocks upregulation of macrophage activation factors and immune cell regulation factors. Surgical intestinal trauma in patients upregulates Cx43 during inflammation and enteric gliosis in mouse POI. CONCLUSIONS: Glial Cx43 signaling promotes enteric gliosis, immune cell activation, inflammation, and enteric neuropathy in mice with potential translatability to humans after intestinal surgical trauma and mechanical stress in POI. Interventions that block glial Cx43 activation may be protective against POI development.

Animals↗
PubMed1977

Blood pressure control in end-stage renal disease in man: indirect evidence of a complex pathogenic mechanism besides renin or blood volume.

1. In twenty-three uraemic patients on regular dialysis, plasma renin activity and blood volume were measured before and after a single dialysis. Three groups were identified; the first had a low or normal plasma renin activity and a high or normal blood volume, the second had a high plasma renin activity and a low blood volume and the third had both variables above normal. 2. In spite of these differences, diastolic blood pressure before and after dialysis was the same in the three groups and multiple regression analyses failed to demonstrate any dependence of blood pressure on plasma renin activity, blood volume or body weight taken separately or together. 3. We conclude that other factors besides plasma renin activity and blood volume are important in maintaining arterial hypertension in terminal renal failure.

Adult↗
PubMed1979

Relationship between superoxide dismutase and pathogenic mechanisms of Listeria monocytogenes.

Listeria monocytogenes was examined for superoxide dismutase(SOD) activity. Two catalase-negative strains possessed at least twofold greater SOD activities than the catalase-positive L. monocytogenes strains examined. Growth conditions such as aeration and iron concentration influenced the specific activity of SOD obtained from cells cultured in defined media. L. monocytogenes SOD from crude extracts and after partial purification was analyzed by polyacrylamide gel electrophoresis. Iron was associated with the single band of SOD activity detected in the gels. SOD activity appeared to be primarily extracytoplasmic. Survival of organisms in a superoxide-generating medium was studied, with photoactivation of riboflavin used as the source of free radical formation. Virulent, catalase-positive L. monocytogenes strains were relatively resistant to killing in a pH 7 superoxide-containing medium. An intact-cell assay for SOD was developed, which used the superoxide-generating system and employed the superoxide-dependent oxidation of sulfite, added to the medium, and inhibition of this oxidation by SOD. Maximal SOD activites of intact cells were observed when 100 to 400 micrograms (dry weight) of viable Listeria cells per ml was added to the medium. A possible role for SOD in the pathogenesis of listeric infection is discussed.

Fungal Proteins↗
PubMed1976

Pathogenic mechanisms in pulmonary fibrosis: collagen-induced migration inhibition factor production and cytotoxicity mediated by lymphocytes.

The universal features of the histopathology of fibrotic lung disease are derangement of parenchymal collagen and infiltration of the parenchyma with chronic inflammatory cells. To determine if this cellular reaction might be associated with autoimmunity to a consitituent of the alveolar interstitium, peripheral blood lymphocytes were exposed to human type I collagen in vitro and evaluated for the production of migration inhibition factor and cytotoxicity. Data from 18 patients with idiopathic pulmonary fibrosis, 8 patients with pulmonary fibrosis other than idiopathic pulmonary fibrosis, 12 patients with nonfibrotic lung disease, and 9 normals demonstrated that circulating lymphocytes from more than 94% of patients with fibrotic lung disease take part in processes where the recognition of collagen results in migration inhibition factor production and lysis of collagen-coated sheep red blood cells. These collagen-induced cell-mediated phenomena are obviated with human T-lymphocyte antiserum. Collagen-induced migration inhibition factor production and cytotoxicity were found in less than 20% of patients with nonfibrotic disease and were not found in normals. Qualitatively, there was no organ (lung, skin) or species (human, rabbit) collagen specificity in these assays, but human lung alpha 2 chains were recognized more often than alpha 1(I) chains. Circulating lymphocytes from patients with fibrotic disease are present in a normal T to B ratio. These lymphocytes did not incorporate [3H]thymidine when exposed to collagen but did when exposed to T-cell mitogens. These in vitro observations suggest that circulating T-lymphocytes and lung collagen may be intimately associated in the pathogenesis of human fibrotic lung disease.

Adult↗
PubMed2025

Proteomic insights into platelet dysregulation and pathogenic mechanisms of chronic thromboembolic pulmonary hypertension.

BACKGROUND: Undissolved thrombus blocks the pulmonary arteries in chronic thromboembolic pulmonary hypertension (CTEPH), a potentially fatal illness that raises pulmonary resistance, causes right heart failure, and even results in death. Although platelets are linked to vascular dysfunction and thrombus formation, it is yet unknown what precise proteome alterations and mechanistic roles they play in CTEPH. METHODS: We extracted platelet-rich plasma from peripheral blood and separated the plasma to obtain enriched platelet pellet (EPP). Quantitative proteomics was used to examine EPP from CTEPH patients and healthy controls using mass spectrometry. The relationship between protein levels and clinical markers of right heart function was examined. Platelet activity, morphology, and interactions with other blood components were evaluated using transmission electron microscopy, immunofluorescence, and flow cytometry. RESULTS: The proteomic investigation found that 179 proteins were differentially expressed in CTEPH patients. The analysis revealed that these proteins were involved in crucial processes such as complement and coagulation cascades, phagosome, and neutrophil extracellular trap (NET) formation. Elevated proteins, specifically NOX2, PAD4, ITGB2, and HMGB1, have been associated to platelet-neutrophil aggregates and NET formation. In addition, enhanced P-selectin expression in platelets and plasma confirmed greater platelet activation in CTEPH patients. Notably, PAD4 and NOX2 levels showed a substantial correlation with hemodynamic parameters and right heart dysfunction. MPO-DNA, a NET marker associated with P-selectin and ITGB2 expression, was discovered in higher concentrations in CTEPH patients' plasmas. CONCLUSION: Platelet aggregation and activation in CTEPH encourage the formation of NETs, which advances the disease and prolongs thrombus. Right heart insufficiency and hemodynamic markers had a strong correlation with PAD4 and NOX2 levels, indicating that these biomarkers may be employed to assess the severity and prognosis of CTEPH disease and offer a fresh approach to targeted treatment. The results highlight the need for additional study to elucidate platelet-mediated pathways and create therapies for CTEPH that target platelets.

Humans↗
PubMed1978

Chronic inhibition of brain protein synthesis after portacaval shunting. A possible pathogenic mechanism in chronic hepatic encephalopathy in the rat.

We investigated the effects of chronic portacaval shunting, with or without additional ammonia loading, on brain protein synthesis in unanesthetized rats by continuous intravenous infusion of 3H-lysine (10 mumoles per gram, 0.2 muCi/mumole). Lysine was incorporated into forebrain proteins at a rate of 1.6 nanomoles/mg protein per hour in sham-operated controls, but at a rate of only 0.83 nanomoles/mg protein per hour (p less than 0.001) in paired rats 6 to 8 weeks after construction of a portacaval shunt. An acute load of ammonium acetate in portacaval-shunted animals further decreased the rate of lysine incorporation into forebrain proteins. Chronic inhibition of protein synthesis may play a role in the pathogenesis of chronic portacaval encephalopathy.

Ammonia↗
PubMed1979

[Clinical and angiographic study and pathogenic mechanism of Prinzmetal's angina. Apropos of 31 cases].

31 patients presenting with Prinzmetal variant angina were divided into three groups according to their angiographic appearances. Group I comprised 9 patients with normal or coronary arteries with lesions less than 50% narrowing. Group II comprised 12 patients with single vessel disease. Group III comprised the other 10 patients with significant lesions on two or all three principal arteries. No clinical or electrocardiographical differences were found between the groups as to age, sex or the clinicapresentation of the chest pain. Most patients with normal or nearly normal coronary arteries had normal electrol cardiogrammes between attacjs (8 out of 9) and electrical changes mainly over the inferior wall (8 out of 9). Exercise electrocardiography reproduced ST elevation in 4 of the 9 patients but, in contrast to the patients in the other two groups, never ST depression. However, these features are not specific for patients in Group I as they were observed in 4 patients in the other two groups. Spontaneous or induced coronary spasm were observed in 27 patients, confirming its role as the mechanism of Prinzmetal angina, whatever the anatomical appearance of the coronary tree.

Adult↗