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At least 163 records · Page 9Linked to original sources
PubMed1987

The role of gamma interferon in the generation of human macrophages cytotoxic for Entamoeba histolytica trophozoites.

Upon exposure to Entamoeba histolytica antigen, lymphocytes from patients treated for amebic liver abscess produce lymphokines which activate monocyte-derived macrophages to kill E. histolytica trophozoites. We now demonstrate that gamma interferon (IFN-gamma) is produced by these stimulated lymphocytes and is sufficient but not exclusively necessary to activate monocyte-derived macrophage amebicidal activity. Supernatants from mononuclear cells of 7 patients when stimulated with amebic antigen contained more IFN-gamma than comparable supernatants derived from control cells (1,862 U/ml vs. 174 U/ml geometric means, P less than 0.01); IFN-gamma levels were similar in patient and control supernatants following concanavalin A stimulation. Macrophages activated solely by partially purified IFN-gamma or recombinant human IFN-gamma (300 U/ml) killed 47% of virulent amebae by 6 hr at 37 degrees C. Monocyte-derived macrophages stimulated with lymphokines elicited by amebic antigen or concanavalin A killed 48% and 57% of axenic E. histolytica trophozoites, respectively, over 6 hr at 37 degrees C (P less than 0.001 for each compared to control). Macrophages incubated with the identical lymphokines, but in the presence of monoclonal antibody to IFN-gamma, were only able to kill 18% and 27% of amebae, respectively, at 6 hr (P less than 0.05 to control or when antibody to IFN-gamma was not present). If antibody to IFN-gamma was added to the stimulating lymphokine, more macrophages died during interaction with amebae (P less than 0.05). In summary, IFN-gamma has a major but not exclusive role in activating human monocyte-derived macrophages in vitro to kill virulent E. histolytica trophozoites.

Adult↗
PubMed1998

Acanthamoeba adherence to contact lenses, removal by rinsing procedures, and survival to some ophthalmic products.

Unworn soft and rigid gas-permeable contact lenses were inoculated with an Acanthamoeba keratitis strain to study the protozoon's ability to adhere. Furthermore, the efficacy of the rinsing in saline on acanthamoeba removal was evaluated, as well as the amebicidal activity of five commercial cleaning/disinfecting products: hydrogen peroxide, chlorhexidine, polyaminopropyl biguanide-poloxamine, thimerosal-polyquaternium, and thimerosal-chlorhexidine. Microscopic count of cells showed that Acanthamoeba trophozoites and cysts adhered to all types of contact lenses. A significantly greater adherence of trophozoites than cysts was recorded. The rinsing in saline using a flow-method was significantly more effective than the immersion-method, particularly in removing trophozoites from rigid gas-permeable lenses. The cleaning/disinfecting solutions tested were ineffective in removing or in affecting the viability of all Acanthamoeba trophozoites or cysts in the 17 hours allotted for the experiment. The need for a better care in mechanical and physical hygiene procedures is stressed.

Acanthamoeba↗
PubMedDate not supplied

[Percutaneous drainage of amebic hepatic abscess by guided ultraound. Preliminary results].

Amebic hepatic abscess (AHA) is the most frequent extraintestinal complication of amebiasis. Over time, its treatment has gone through some changes and at present is based on amebicides and in some cases, percutaneous drainage. The objective of this work is to present our experience with percutaneous drainage by means of guided ultrasound in patients with AHA. In this work, we include 170 patients admitted to the Gastroenterology Unit of the Hospital General de Zona No. 1, (IMSS) in Mexico City during a period of eight years (1990-1997). These cases included the following criteria: Failure to medical therapy, AHA of liquid matter greater than 5 cm determined by ultrasound; risk of rupture, prolonged incapacity with no data of toxico-infection, accessible drainage route; availability of operating room before risk of complication, and normal coagulation tests. A modified Seldinger's technique was utilized. A single punction was carried out in 131 patients, who had only one abscess. Thirty-nine patients required a second evacuation on presenting two abscesses, and in four cases, a third evacuation was required due to the presence of three or more abscesses. Only one case required an urgent surgical procedure due to abscess rupture to pleura. Five patients suffered complications, including the latter. The remaining four patients had a spontaneous resolution. All patients were released during the 24 hours following surgery, and no patient required hospitalization. For this reason, this can be considered a procedure that in the expert hands of interventionist radiologists, has less morbidity. This work will be carried out to 10 years.

Adolescent↗
PubMed1999

[Keratitis caused by Acanthamoeba in patients with contact lenses].

BACKGROUND: Keratitis by Acanthamoeba is a severe infectious complication which may be derived from the use and bad preservation of contact lens. This disease la increasingly more frequent and rapid diagnosis and treatment condition the posterior evolution of the disease. PATIENTS AND METHODS: The cases of 2 contact lens waters who developed keratitis by Acanthamoeba are presented. The diagnostic methods and treatment are commented upon. RESULTS: Keratitis by Acanthamoeba was diagnosed in 2 patients following analysis of corneal scrapings and of the saline solution used for lens maintenance. Trophozoites and cystes of this parasite were observed in all the samples processed. The evolution was good in the patient treated at 15 days after initiation of the symptoms. However, the evolution was very bad in the patient who delayed in initiating the amebicide treatment. Penetrating keratoplasty was performed in both patients. CONCLUSIONS: Specific treatment with derivates of propamidine implemented early may avoid severe ocular complications. As prophylaxis for contact lens users, it is recommended that the contact lens be maintained clean and correctly care for, and the use of home-made saline solutions which are easily contaminated by Acanthamoeba, should be avoided.

Acanthamoeba Keratitis↗
PubMed2001

Effect of steroids on Acanthamoeba cysts and trophozoites.

PURPOSE: Topical steroids are frequently used to control corneal inflammation and uveitis or is administered after surgery, to prevent corneal graft rejection. This study was undertaken to determine whether steroids could affect the pathogenicity of Acanthamoeba castellanii. METHODS: The effect of dexamethasone phosphate on excystment, proliferation, and encystment of trophozoites and cysts of A. castellanii was examined in vitro. Cytolysis capacity of steroid-treated Acanthamoeba was quantified by a spectrophotometric assay, and plasminogen activators were measured by a fibrinolysis assay. The influence of steroid treatment on corneal infection in a Chinese hamster model of Acanthamoeba keratitis was examined in vivo. RESULTS: Treatment of Acanthamoeba cysts with dexamethasone induced 4- to 10-fold increases in the number of trophozoites compared with untreated control cultures. Acceleration of trophozoite proliferation was observed when trophozoites were treated with dexamethasone. However, dexamethasone treatment did not affect encystment of Acanthamoeba trophozoites. Dexamethasone-treated trophozoites or cysts induced a significant cytopathic effect on corneal epithelial cells compared with untreated organisms. Supernatants collected from either dexamethasone-treated or untreated organisms failed to lyse corneal epithelial cells. Treatment of organisms with dexamethasone had no effect on production of plasminogen activators by Acanthamoeba trophozoites. Intramuscular injection of dexamethasone had a profound effect on the incidence, severity, and chronicity of keratitis. Keratitis in dexamethasone-treated hamsters was significantly more severe at all time points than in untreated animals (P < 0.05). CONCLUSIONS: These findings indicate that exposure of Acanthamoeba trophozoites and cysts to dexamethasone increases the pathogenicity of the organisms. The results emphasize the importance of maintaining adequate amebicidal therapy if a topical steroid is used in the management of Acanthamoeba keratitis.

Acanthamoeba↗
PubMedDate not supplied

Complex network of cytokines activating murine microglial cell activity against Acanthamoeba castellani.

In the central nervous system, cytokine-primed microglia play a pivotal role in host defence against Acanthamoeba castellani infections. In this study, the effect of rIL-1beta, rIL-6 or rTNF-alpha, combined or not with rIFN-gamma, on A. castellani infection of murine microglia was examined. Priming of microglial cells with either rIL-1beta or rIL-6, in the presence or absence of rIFN-gamma, triggered amebastatic activity, while the treatment of microglia with rTNF-alpha plus rIFN-gamma additively triggered, in a dose-dependent fashion, amebicidal activity. Inasmuch as NGMA affected cytokine-triggered anti-parasitic activity during the priming process, the NO-dependent pathway itself appears not to be directly involved in the anti-amebic capacities. These data suggest that the proinflammatory cytokines IL-1beta, IL-6 or TNF-alpha could trigger anti-microbial activity against A. castellani infection in the brain.

Acanthamoeba↗
PubMed1978

Bioassay of emetine for possible carcinogenicity.

A bioassay of emetine, an amebicide and anticancer drug, for possible carcinogenicity was conducted by administering the test material by intraperitoneal injection to Sprague-Dawley rats and B6C3F1 mice. Groups of 35 rats of each sex were administered emetine at one of two doses, either 0.5 or 1 mg/kg body weight, three times per week for 52 weeks, and then observed for an additional 31 or 32 weeks. Control groups of each sex consisted of 10 untreated rats (untreated controls) and 10 rats injected with buffered saline (vehicle controls). Pooled-control groups, used for statistical evaluation, consisted of the vehicle-control rats of each sex for this study combined with 15 vehicle-control rats of each sex from a similar bioassay of another test chemical. All surviving rats were killed at 83 or 84 weeks. Initially, groups of 35 mice of each sex were administered emetine at one of two doses, either 3.2 or 6.4 mg/kg body weight (mid- and high-dose), three times per week. Control groups of each sex consisted of 15 untreated mice (untreated controls) and 15 mice injected with buffered saline (vehicle controls). Due to high mortality rates in the initial treated groups, additional groups of 35 mice of each sex were later put on study at 1.6 mg/kg (low-dose), together with 10 untreated-control and 10 vehicle-control mice of each sex. The high-dose males were treated for 28 weeks and the mid- and high-dose females for 40 and 33 weeks, respectively. Mid- and low-dose male mice and low-dose female mice were treated for 52 weeks, and then observed for an additional 20 or 26 weeks. All surviving mice were killed at 78-83 weeks. Emetine was toxic to male rats at the high dose, to both sexes of mice at the high and mid doses and to a lesser extent at the low dose, as shown by the low survival in these groups. Twenty-six percent of the high-dose male rats and 69% of the high-dose female rats, but none of the high- and mid-dose mice of either sex, survived to the end of the study. In the low-dose mice, 30/35 males and 21/35 females lived at least 1 year, and the median time on study was 72 weeks for males and 59 weeks for females. No tumors occurred at a statistically significant incidence in treated rats or mice compared with controls; however, it should be noted that in this study, treatment of both species was stopped at week 52 and the studies were terminated by week 83, which is earlier than in current bioassays where animals are treated until termination of the studies at 2 years. In addition, there was poor survival among the treated mice. It is concluded that the results of this study do not allow evaluation of the possible carcinogenicity of emetine.

Journal Article↗
PubMed1992

Macrophage colony-stimulating factor enhances the respiratory burst of human monocytes in response to Entamoeba histolytica.

Mononuclear phagocytes (MP) are probably the most capable effector cells of the body in the defense against virulent strains of E. histolytica. Killing of E. histolytica by MP appears to involve both oxidative and non-oxidative mechanisms. Thus, in this study we have investigated whether trophozoites of an axenic virulent strain E. histolytica HM1:IMSS (EH) were capable of eliciting an oxidative response in pure populations of freshly isolated human monocytes. Using a luminol-enhanced chemiluminescence assay we demonstrate that these cells produce a strong respiratory burst when challenged with live amebas over a wide range of MP:EH ratios. Furthermore, pre-incubation of monocytes with recombinant Macrophage Colony Stimulating Factor (M-CSF) could further increase the oxidative metabolism of MP in response to E. histolytica. Our results indicate that, in contrast to what occurs with polymorphonuclear leukocytes, the interaction of E. histolytica with MP leads to the production of reactive oxygen intermediates by this cells. The enhancement of this potent microbicidal mechanism by inflammatory cytokines may further increase the amebicidal capacity of human mononuclear phagocytes.

Adult↗
PubMed2003

Effect of antifungal drugs on pathogenic Naegleria spp isolated from natural water sources.

UNLABELLED: Five of 16 strains of pathogenic Naegleria spp isolated from 350 natural water sources in Taling Chan District, Bangkok had similar molecular weights and zymogram patterns to those of Naegleria fowleri CDCVO 3081 and Thai strain. The in vitro effects of antifungal drugs (amphotericin B, ketoconazole, fluconazole and itraconazole) were tested at the following concentrations: amphotericin B 0.01-0.55 microg/ml, ketoconazole 0.01-0.3 microg/ml, fluconazole 0.75-3.5 mg/ml and itraconazole 4-12 mg/ml respectively. Aliquots (15,000 cells/ml) of the amoebae were placed in the cells of the microtiter plate and incubated at 37 degrees C. Amoebae from each treatment sample were exposed to one of the four antifungal drugs. Statistical analysis was done by dependent t-test. The sensitivity of the antifungal drugs (MIC50) was as follows: amphotericin B 0.03-0.035 microg/ml ketoconazole 0.05-0.15 microg/ml fluconazole 1.75 mg/ml and itraconazole 8-9 mg/ml respectively (p < 0.005). CONCLUSION: Amphotericin B and ketoconazole are more active against Naegleria fowleri in vitro. The results of the present study should be used as an in vitro screening test for drugs that have potential amebicidal activity.

Amphotericin B↗
PubMed1990

Pleuropulmonary manifestations of hepatic amebiasis.

Pleuropulmonary manifestations of hepatic amebiasis occurred in 30 patients; 18 (60%) presented with at least 1 pulmonary complaint and 10 (33%) had multiple pulmonary symptoms. In 14 patients (47%), abnormalities were found on examination of the chest. In 16 chest roentgenograms (53%), there was at least 1 abnormality: right-sided pleural effusion (9 patients) and elevated right hemidiaphragm (8 patients) were the most common. All patients were treated with metronidazole (Flagyl) and had resolution of the amebic liver abscess and pulmonary disease. Pleuropulmonary disease is a common complication of amebic liver abscess. The clinical presentation and chest roentgenograms are virtually diagnostic and obviate the need for invasive procedures to confirm the diagnosis. Pleuropulmonary disease resolves with amebicidal treatment of the hepatic abscess.

Abdominal Pain↗
PubMedDate not supplied

[The value of metronidazole in the indications for appendicectomy in a tropical environment. Apropos of 183 cases].

This work was carried out consequently to three observations followed up by regrettable consequences: one right hemicolectomy about acute perforated typhlitis, two post-operative fistulae about clinical feature of pseudo-appendicitis. A study was undertaken on 183 patients; 160 patients complained of chronic in right iliac fossa, 23 of acute or subacute pain. Out of the 160 chronic patients, treated by metronidazole did not show symptoms anymore. Out of the 23 acute patients, 14 were cured thanks to the amebicide test-treatment and the 9 others showed during surgical intervention: 4 phlegmonous appendicitis, 3 appendicitis with inflammation of the mucous membrane, 2 appendicitis with abscess. In the acute cases, the duration of the therapeutic test was 10 ho. In the operated chronic cases (37 out of 160), histology substantiated surgery in revealing typical lesions of chronic appendicitis sometimes associated to anatomical deformity such as diverticulum. The authors strongly suggest such a test-treatment by metronidazole. It is well accepted and has enabled to get rid of post-operative morbidity of appendicectomy in tropical milieu.

Adult↗
PubMed1987

[UltrastructuraL analysis of the action of levorin on Entamoeba].

The paper is concerned with investigation of the nature of ultrastructural alterations in Entamoeba moshkovski under the levorin effect. The studies showed that under the effect of levorin there appeared in the Entamoeba cultures diverse types of cells having chiefly the following ultrastructural alterations: a higher number and size of cytoplasmic vacuoles, lower density of the cytoplasm granular component, not intact nuclear and plasmatic membranes and cell cytolysis. Analysis of the experimental results suggested that the amebicidal effect of levorin on Entamoeba was mainly associated with its membranotropic properties.

Animals↗
PubMed1987

[Therapeutic effectiveness of CT-controlled drainage puncture in amebic abscesses of the liver].

Amebic liver abscesses are the most frequent clinical manifestations of the extra-intestinal amebiasis and have to be considered as a serious complication in the course of disease. The abscesses have by their risk of rupturing and bacterial superinfection quoad vitam an unfavourable prognosis. CT-guided relief punctures can, as it is demonstrated by two cases of critical amebic abscesses, effectively improve the therapy with systemic amebicides, prevent imminent rupture and contribute to the healing of the abscesses. Thus a surgical treatment of the abscess was not necessary.

Drainage↗
PubMed1978

[Amebiasis--retrospective analysis of 453 cases in the Zürich region].

In a retrospective study 453 cases of amebiasis were analyzed with regard to duration, purpose, and location of the patients' stay abroad. Diarrhea and abdominal complaints were the predominating features of the history, but occasionally constipation was the only symptom. The patients usually had chronic intestinal amebiasis which was intermittently slightly dysenteric, rather than non-dysenteric as defined by the WHO. There were two cases each of ameboma and colonic stricture and three liver abscesses, one of which proved fatal after complicating peritonitis. Therapy with a tissue and a lumenal amebicide proved to be the most efficient combination, with a success rate exceeding 94% in the controlled cases.

Adolescent↗
PubMed1980

[Derivatives of 2-phenothiazin-2'-yl-cinchoninic acid with analgesic and anti-inflammatory activity].

In order to investigate the effects of the overlapping of cinchophene and phenothiazine structures, connected with antiinflammatory and analgesic activities, several derivatives of 2-phenothiazin-2'-yl-cinchoninic acid were prepared through the condensation of isatin or 5-substituted isatins with 2-acetylphenothiazine or its 10-ter-aminoalkyl derivatives. Most of these compounds exhibit analgesic activity, but only a few, of those so far tested, show antiinflammatory activity. Compound (G) with R' = H, R" = C2H5 and R"' = dimethylaminoethyl shows analgesic activity corresponding to 88% of that of phenylbutazone. Moreover some compounds show signs of sympatholytic and vasodilatatory activities and also bactericidal and amebicidal properties in vitro, while some others demonstrate a modest neuroplegic activity.

Amphetamine↗
PubMed1980

Necrotizing amebic colitis with pseudomembrane formation.

We report a case of necrotizing amebic colitis with the sigmoidoscopic finding of a confluent, grayish pseudomembrane. The patient was referred from a chronic mental institution, which represents the patient population most susceptible to fulminant amebic dysentery in the United States. The pseudomembrane was a reflection of extensive mucosal necrosis and resolved with amebicidal therapy.

Colon↗
PubMedDate not supplied

Amebic liver abscess "a 5 year Mexican experience with a multimodality approach".

BACKGROUND/AIMS: Amebic liver abscess is a frequent problem in Mexico. The morbidity and mortality is reported to be high in different series. The aim of this study was to evaluate the morbidity and mortality of ALA in our center and evaluate our current management used. MATERIALS AND METHODS: Fifty patients were included in our study. Thirty-four (68%) were males, 16 (22%) were females. The age range was between 22 and 83 years (mean 50 years). The majority presented abdominal pain (95%), fever (82%) and hepatomegaly (72%). leukocytosis was observed in 72%, hypoalbuminaemia in 62%, thrombocytosis in 42%. The seroemeba reaction was positive in 90%. The diagnostic methods used were ultrasound in 42, computed tomography in 20 and isotope scan in 12. RESULTS: Medical treatment alone was used in 24 patients, 15 required percutaneous drainage and 11 surgery. Fifteen patients (38%) presented medical complications. The hospital stay raged between 5 and 44 days (mean 15 days). One patient died in a median follow up of 31.4 months. Multimodality management was liberally used in our patients. Amebicidal drugs were used initially and controlled the disease in 24 patients, 15 patients required percutaneous drainage because of lack of control of the disease or risk of complications and 11 patients required surgery to treat complications. CONCLUSION: With these approaches the morbidity and mortality of ALA in our center has remained low.

Adult↗
PubMed1996

Risk factors associated with fulminant amebic colitis.

Amebic colitis is associated with serious complications and a high fatality rate if it progresses to its fulminant form. The purpose of this retrospective study was to determine the risk factors associated with fulminant amebic colitis. From February 1978 to February 1993, 60 adults were diagnosed with intestinal amebiasis at Chang Gung Memorial Hospital. Sixteen patients with massive bloody diarrhea, persistent systemic toxicity or signs of peritonitis were classified as having fulminant colitis, five of whom progressed to fulminant colitis after admission to the hospital. Forty-four patients with good responses to amebicides and without complications were classified as having moderate colitis. There was no amebiasis-related mortality among patients with moderate colitis. In contrast, five patients with fulminant colitis died. Early diagnosis and surgical treatment significantly decreased mortality when compared with conservative treatment. Significant factors associated with the development of fulminant intestinal amebiasis in univariate analyses were being male, age over 60 years, having an associated liver abscess, progressive abdominal pain, signs of peritonitis, leukocytosis, hyponatremia, hypokalemia and hypoalbuminemia. Only the factors of being over 60 years of age and hypokalemia were important in multivariate analyses. We conclude that early and extensive surgical treatment is mandatory for patients with typical presentations of fulminant amebic colitis on admission to the hospital, such as progression to peritonitis, persistent systemic toxemia and explosive bloody diarrhea. For other patients, especially the elderly and those with low serum potassium levels, close monitoring and observation for signs of fulminant colitis is important.

Adult↗