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Biomedical subjects

R Negroni

Publications and source records attributed to R Negroni.

At least 109 records · Page 6Linked to original sources
PubMedDate not supplied

Experimental coccidioidomycosis in the immunosuppressed rat.

C. immitis inoculated rats are known to develop infection restricted to lung whereas cyclophosphamide (CY) treatment leads to widespread dissemination with considerable mortality. In this study, an attempt was made to elucidate the mechanisms involved in such behaviour. With this aim, spleen cells were transferred from infected CY-treated to infected untreated rats, achieving significant specific inhibition in footpad swelling to coccidioidin in recipients, attributable to a suppressor T cell subpopulation induced by greater fungal antigen concentration arising from widespread C. immitis dissemination in immunosuppressed animals. NK activity proved similar regardless of CY treatment. Lastly, chronically infected rats presented increased colony forming units count after several weekly doses of CY, as happens in immunosuppressed patients harbouring a previous infection.

Animals↗
PubMedDate not supplied

[Value of direct and indirect diagnostic methods in systemic mycoses associated with AIDS].

One hundred and seventeen patients suffering systemic mycosis and AIDS were studied during 5 years in the Muñiz Hospital of Buenos Aires City. Seventy four of them presented cryptococcosis, 39 histoplasmosis and 4 both mycoses. The following specimens were studied for the diagnosis: skin and mucous membrane scrapings, bone marrow aspirations, bronchial secretions, biopsies of different organs, cerebral spinal fluid and blood cultures. Sera were also collected for serologic tests. A total of 203 samples from patients with histoplasmosis were studied, 46.3% of them showed H. capsulatum in microscopic examinations or in cultures, skin scraping was the most sensitive diagnostic method (94.7% of positive results), followed by biopsies (80%) and bone marrow cultures (42.1%). Specific antibodies were detected in 45.4% of the patients with histoplasmosis, using 2 different antigens and 3 types of serologic reactions (complement fixation test, immunodiffusion and counterimmunoelectrophoresis). A total of 413 samples from patients with cryptococcosis were examined, 69% of them confirmed the diagnosis. The mycologic study of CSF was the most sensitive method of study, since it registered positive results in 89.5%, followed by blood cultures (61.2%), skin scrapings (42.9%), and urine cultures (41.7%). Polysaccharyde antigens from C. neoformans in organic fluids were detected in almost all the cases. The aim of this study is to compare all the suitable diagnostic methods which can be used in systemic mycosis associated with AIDS in order to find the most rapid way of diagnosis.

AIDS-Related Opportunistic Infections↗
PubMedDate not supplied

Flucytosine+fluconazole association in the treatment of a murine experimental model of cryptococcosis.

The efficacy of flucytosine (5-FC) and fluconazole (FLU) association in the treatment of a murine experimental model of cryptococcosis, was evaluated. Seven groups of 10 Balb C mice each, were intraperitoneally inoculated with 10(7) cells of Cryptococcus neoformans. Six groups were allocated to receive 5-FC (300 mg/kg) and FLU (16 mg/kg), either combined and individually, by daily gavage beginning 5 days after the infection, for 2 and 4 weeks. One group received distilled water and was used as control. The evaluation of treatments was based on: survival time; macroscopic examination of brain, lungs, liver and spleen at autopsy; presence of capsulated yeasts in microscopic examination of wet preparations of these organs and cultures of brain homogenate. 5-FC and FLU, individually or combined, significantly prolonged the survival time of the treated animals with respect to the control group (p < 0.01). Animals treated for 4 weeks survived significantly longer than those treated for 2 weeks (p < 0.01). No significant differences between the animals treated with 5-FC and FLU combined or separately were observed in the survival time and morphological parameters. The association of 5-FC and FLU does not seem to be more effective than 5-FC or FLU alone, in the treatment of this experimental model of cryptococcosis.

Animals↗
PubMedDate not supplied

Blood culture as a parameter of treatment effectiveness in experimental histoplasmosis of the hamster.

The aim of this study was to determine the value of blood culture as a parameter of treatment effectiveness in experimental histoplasmosis. A total of thirty five hamsters, weighing approximately 120g, were inoculated intracardially with 0.1 ml of a suspension containing 4 x 10(7) cells/ml of the yeast phase of H. capsulatum. Treatments were started one week after the infection and lasted for 3 weeks. The azoles, (itraconazole, saperconazole and fluconazole) were administered once a day by gavage, at a dose of 8 mg/kg; Amphotericin B was given intraperitoneally every other day at a dose of 6mg/kg. Blood samples (1 ml) were obtained by heart punction from the 4th day after infection and were seeded in Sabouraud honey-agar and BHI-agar. The hamsters that survived were killed one week after treatment completion and the following criteria were considered for treatment evaluation: 1) rate of spontaneous death, at the end of the experience; 2) microscopic examination of Giemsa smears from liver and spleen and 3) determination of CFU in spleen cultures. Amphotericin B was the most effective drug, with negative blood cultures at day 20, negative spleen cultures in all cases and all the animals survived until the end of the study. Fluconazole was the less effective drug, blood cultures were positive during the whole experience, spleen cultures showed a similar average of CFU when compared with the control animals and 42.8% of these animals died. Saperconazole and itraconazole showed a similar activity, with survival of all hamsters and negative blood cultures at 23 and 26 days respectively. Blood culture seems to be valuable parameter for treatments' evaluation in experimental histoplasmosis of the hamster.

Amphotericin B↗
PubMedDate not supplied

Cyclophosphamide effect on paracoccidioidomycosis in the rat.

Paracoccidioidomycosis is an endemic fungal disease widely distributed throughout Latin America. The potent immunosuppressor cyclophosphamide (CY) has been used to modulate host immune response to Paracoccidioides brasiliensis in an experimental model. Inbred male Buffalo/Sim rats weighing 250-300 g were inoculated with 5 x 10(6) P. brasiliensis cells of the yeast phase form by intracardiac route. One group of animals was treated with 20 mg/kg body weight at days +4, +5, +6, +7, +11 and +12 post-infection (pi.), while a control group was infected alone. No mortality was recorded in either group. Treated rats presented: a) a decrease in granuloma size, which contained less fungal cells; b) a lack of specific antibodies up to 35 days pi., and c) a significant increase in the footpad swelling test (DTH) against paracoccidioidin. Splenic cell transfer from CY-treated P. brasiliensis-infected donors to recipients infected alone led to a significant increase in DTH response in the latter versus untreated infected controls. Likewise, in treated infected recipients transferred with untreated infected donor spleen cells, footpad swelling proved greater than in controls. Thus, it would seem that each successive suppressor T lymphocyte subset belonging to the respective cascade may be sensitive to repeated CY doses administered up to 12 days pi.. Alternatively, such CY schedule may induce the appearance of a T cell population capable of amplifying DTH response.

Animals↗
PubMedDate not supplied

Detection of Cryptococcus neoformans capsular polysaccharide antigen in asymptomatic HIV-infected patients.

Serum samples from 242 HIV-positive persons were studied for the detection of capsular polysaccharide antigen of Cryptococcus neoformans; 193 of these patients presented less than 300 CD4+ cells/microliters of blood and 49 patients had more than 300 CD4+ cells/microliters. None of them had symptoms or signs characteristic of cryptococcosis. The capsular antigen of C. neofarmans was detected by latex agglutination technique with pronase pretreatment (IMMY, Crypto-Latex Antigen Detection System, Immunomycologics Inc., OK, USA); in 61% of the samples, ELISA technique was also used (Premier, Cryptococcal Antigen, Meridian Diagnostic Inc., Cincinnati, Oh, USA). The comparative study of both methods showed that the results obtained were similar in 96.9% of the cases. The capsular antigen was detected in 13 out of 193 (6.7%) patients with less than 300 CD4+ cells/microliters. Cryptococcosis was confirmed mycologically in 3 of these 13 cases (23%) by the isolation of C. neoformans in CSF or blood cultures. Three patients, who had presented negative results of both tests for capsular antigen, suffered disseminated cryptococcosis 4 to 8 months later. The predictive diagnostic value of capsular antigen detection of C. neoformans seems to be low and we believe that it should not be done routinely in asymptomatic HIV-positive persons.

Acquired Immunodeficiency Syndrome↗
PubMedDate not supplied

Interferon gamma increases survival in murine experimental cryptococcosis.

Systemic disease by Cryptococcus neoformans (C. neoformans) is a common opportunistic infection in immunodeficient patients. Cellular immunity seems to be the most important determinant of resistance. The aim of this study was to assess the effect of recombinant rat interferon gamma (IFN-gamma) in murine cryptococcosis (Balb/c mice infected by IP route with the Rivas strain of C. neoformans), evaluating survival time, macroscopic and microscopic examination of the organs, and massive seeding of brain homogenate. IFN-gamma treatment, at a daily dose of 10,000 IU, did not modify significantly these variables when mice were challenged with a high inoculum (10(7) yeasts) and treatment was delayed to 5 days after infection (median survival 21 days in control mice vs. 23 days in IFN-treated). Another set of experiments suggested that IFN-gamma treatment, at a dose of 10,000 IU/day, begun at the moment of infection could be useful (it prolonged survival from 20 to 28 days, although the difference did not achieve statistical signification). When used simultaneously with infection by 3.5 x 10(5) yeasts, IFN-gamma at 10,000 IU/day for 15 days significantly prolonged survival of mice (p = 0.004). These results suggest that, depending on the experimental conditions, IFN-gamma can improve survival of mice infected with a lethal dose of C. neoformans.

Animals↗
PubMedDate not supplied

Acute disseminated histoplasmosis and endocarditis.

Acute disseminated histoplasmosis is a frequent condition in HIV carriers. Thirty-five cases of endocarditis caused by Histoplasma capsulatum have been reported in international literature, and all these descriptions correspond to a context of subacute disseminated histoplasmosis. This paper presents the case of a HIV-positive patient with fever, dyspnea, weight loss, vomiting and polyadenopathies to whom histoplasmosis was diagnosed following blood-cultures and isolation of the agent responsible for cutaneous lesions, and in whom aortic-valve vegetations were found during an echocardiogram. The patient was treated with amphotericin B and had a good outcome; subsequent echocardiograms showed no vegetations. Literature on the subject is reviewed, with special emphasis on diagnosis and treatment of previously described cases.

Acquired Immunodeficiency Syndrome↗
PubMedDate not supplied

[A cutaneous ulcer induced by fungi of the genus Fusarium].

A case of cutaneous hyalohyphomycosis, due to Fusarium oxysporum, in a 40 years old man is presented. The patient came from Paraguay where he worked in a tropical rural area. His disease had begun 2 months before his admission as a skin ulcer located in the left leg. Clinical characteristics, diagnosis methods, differential diagnosis with other ulcers of the legs in tropical areas as well as therapeutic measures are discussed in this presentation.

Adult↗
PubMedDate not supplied

[Immunodiffusion tests in gel media with the addition of polyethyleneglycol 6000 for the serodiagnosis of mycoses].

Different immunodiffusion techniques with and without the addition of polyetilenglycol 6000 (PEG), were studied to determine its effect on the sensitivity of these reactions. One hundred thirteen sera from patients who suffered or had suffered deep mycoses (paracoccidioidomycosis: 49, histoplasmosis: 25, aspergillosis: 25, candidiasis: 8 and coccidioidomycosis: 6) were examined by the quantitative Ouchterlony's immunodiffusion procedure. Regular medium and media with 2% and 4% PEG were used. Eighty two out of the one hundred thirteen sera were positive for the regular medium and 91 for the medium containing 2% of PEG; furthermore, an increase of 1 or 2 two fold dilutions in the titers was observed in 40% of the sera, for the later media. Twenty one sera from aspergillosis cases were examined by agarose gel immunoelectrophoresis, 80% had more precipitin bands in the medium with 2% of PEG. Thirty four serum samples of patients suffering aspergillosis, paracoccidioidomycosis and histoplasmosis were studied using the agarose electroosmophoresis with the secondary immunodiffusion test. An increase in the number of the anodic bands were observed in 55% while 64% presented more catodic bands, when the PEG medium was used. This results would indicate that the addition of 2% PEG 6000 to the regular medium improves the sensitivity of the immunodiffusion tests for mycoses.

Antigens↗
PubMedDate not supplied

[Comparative study of the Candida albicans genotypes isolated from immunocompromised patients and health carriers].

The aim of this study is to compare Candida albicans strain genotype isolates from oral cavity of immunocompromised patients due to different immunologic impairments with apparently normal carriers. Four populations were studied: 1) HIV positive hospitalized patients, 2) HIV negative immunocompromised patients (leukemia, lymphoma, organ transplant recipients), 3) drug addicts prior to AIDS pandemia in Argentina, 4) apparently normal carriers. DNA extracted was digested with the enzyme Eco RI, electrophoresed, transferred to nitrocellulose membrane and hybridized with the 27A probe labelled with 32P. The comparison between the profiles obtained permitted the differentiation of 16 genotypes. The distribution of the strains led to the conclusion that: a) all the isolated strains from AIDS patients were closely related and distributed in only three genotypes (1, 3, 11); b) a major genetic relationship between the isolates from AIDS patients and HIV negative immunocompromised patients was observed; c) strains from carriers showed a minor genetic similarity with those obtained from AIDS patients; d) characteristic profiles belonging to any of the studied groups were not found; e) significant genomic changes have not been observed during the last twenty years.

Argentina↗
PubMedDate not supplied

[Nocardia isolated from the respiratory tract].

Twelve strains of Nocardia isolated from sputa, bronchial washings and pleural fluids, were studied. The classification was based on the following characteristics: a) acid-fastness; 2) ability to disolve crystals of tyrosine and xantine; 3) hydrolysis of casein; 4) growth in dilute gelatin medium (0.4%) and 5) galactose acidification. Direct cultivation of the clinical material in Czapek liquid culture medium without carbon source and containing a paraffin rod (pariffin-bait technic), as well as the routin T.B. sputum digestion and concentration with NaOH solution followed by its cultivation in Loewenstein's medium, were employed for the isolation of Nocardia. The sensitivity of the strains to tuberculostatic drugs was investigated using the Canetti's method, as was the ability to growth in Sabouraud and lactrimel culture media supplemented with 100 mug/ml of rifamycin. Finally the pathogenicity test was carried out by intraperitoneal and intramuscular inoculation in guinea-pigs. All the strains were classified as Nocardia asteroides. Seven starins were isolated from patiens with lung conditions of no nocardial etiology. The diagnosis of nocardiosis of the lung was demonstrated in the remaining five patiens by microscopical observation of Nocardia in clinical specimens, by the repeated cultures obtained from these materials and, finally, by the fact that an improvement of the clinical symptomatology was obtained by sulfa administration.

Anti-Bacterial Agents↗
PubMedDate not supplied

[Disseminated cryptococcosis in patients with AIDS. Clinical, microbiological, and immunological analysis of 51 patients].

In the context of HIV infection, cryptococcal meningitis is the most common mycosis threatening the patient's life. We conducted a retrospective evaluation to determine the epidemiological, microbiological, immunological and clinical characteristics of disseminated cryptococcosis in 51 hospitalised HIV seropositive patients. All the individuals (n = 51) presented reactive serology for HIV (ELISA and/or Western blot) and none fulfilled strict HAART treatment, previous to the opportunistic infection. CD4+ lymphocyte T counts showed levels between 361 and 0 cells/microliter (mean = 45). All patients but one had counts lower than 100 cells/microliter. Cryptococcosis presented as unique episode in 35 patients (68.6%) and in 16 as relapse (31.3%). In all of them we detected central nervous system involvement. The induction treatment was carried out with amphotericin B (AMB), continued with maintenance therapy with fluconazole. Lethality rate was 36.7%, slightly superior among patients in relapse (40%) compared to those who presented a first episode of the mycosis (35.2%). In those individuals for whom data were available, 65.2% of blood cultures, 94.1% of CSF cultures and 79.06% of microscopic CSF examination with India ink were positive. Titers of Cryptococcus neoformans capsular antigen in CSF > or = 1/1000 were found in 36.1% and > or = 1/1000 in 73.6% of serum samples. In conclusion, manifestations and severity of disseminated cryptococcosis continue maintaining the characteristics of half a decade behind, in those patients who are not treated with HAART. Neurological involvement existed in all patients of this cohort. Treatment is not able to modify the parameters of mortality seen in previous communications. Diagnostic methods applied in this study are in accordance with those in the bibliography.

AIDS-Related Opportunistic Infections↗
PubMedDate not supplied

[The epidemiological characteristics of 105 cases of cryptococcosis diagnosed in the Republic of Argentina between 1981-1990].

Some epidemiological characteristics of 105 cases of cryptococcosis diagnosed in Argentina, between 1981-1990, were studied. Until 1987, the annual number of cases was 4-8. It has increased since 1988 by AIDS influence and reached 35 cases in 1990. The annual number of cases non associated with AIDS has remained in 3-7 cases. The age median of the all patients, AIDS and non AIDS associated cases was 30, 30 and 45 years old, respectively. The 20-39 years old group was the most affected and the age distribution was different in AIDS and non AIDS population. Masculine predominance was more evident in AIDS than in non AIDS associated cases. The predisposing factor was AIDS in 57 patients, another different factor in 20 and unknown in 28 cases. The indirect estimation of the percentage of AIDS cases with cryptococcosis was > or = 6.19% (57 cases in 920 HIV+) during 1981-1990 this period. Cryptococcus neoformans variety neoformans was isolated from 101 cases and the gattii variety (serotype B) from only 4. The obtained data are similar to those observed in Europe and United States.

AIDS-Related Opportunistic Infections↗
PubMedDate not supplied

[Successful discontinuation of antifungal secondary prophylaxis in AIDS-related cryptococcosis].

The clinical and laboratory data of 22 patients with AIDS related cryptococcosis who were able to interrupt antifungal secondary prophylaxis after HAART administration, are presented. They were 14 males and 8 females, between 15 and 50 years old (X: 34 years old). All patients presented fever and severe deterioration of their general health status, and 19 exhibited a meningeal syndrome. At the start of antifungal treatment, 59% of the cases presented < 50 CD4+ cells/microl, the median viral burden was 134,804 RNA copies/ml and the median titer of serum cryptococcal antigen was 1/3,000. Amphotericin B by intravenous route, (0.7 mg/kg/day) or fluconazole (600 to 800 mg/day) were given as a treatment of the initial episode, up to CSF cultures negativization. Oral fluconazole (200 mg/day) or intravenous amphotericin B, 50 mg twice a week, were given as a secondary prophylaxis. The secondary prophylaxis was interrupted when the patients had received HAART for an average lapse of 19 months (6 to 36 months) and the median CD4+ cell count was 249/microl. The follow up after secondary prophylaxis discontinuation lasted for a median lapse of 22 months. These data seem to show that secondary prophylaxis is not necessary when the patient are clinically asymptomatic and the CD4+ cell counts are above 150/microl.

AIDS-Related Opportunistic Infections↗
PubMedDate not supplied

[Clinical and microbiological study of mycetomas at the Muñiz hospital of Buenos Aires between 1989 and 2004].

This work presents clinical, microbiological and outcome data collected from 76 patients with mycetomas at the Muñiz Hospital from 1989 to 2004. Forty-nine patients were male and 27 female; the mean age was 43.4 years. The majority of the patients acquired the infection in Argentina: the most affected provinces were Santiago del Estero with 31 cases, and Chaco with 11; 8 cases came from other countries (Bolivia 6 and Paraguay 2). The mean evolution of the disease was 9.2 years. The most frequently observed sites were: feet 63 cases, ankles 3, and knees 2. Forty-eight patients had bone lesions and 5, adenomegalies. The following etiological agents were identified: Madurella grisea 29 cases, Actinomadura madurae 26, Scedosporium apiospermum 5, Nocardia brasiliensis 5, Acremonium spp. 4 (Acremonium falciforme 2, Acremonium kiliense 1, Acremonium recifei 1), Madurella mycetomatis 3, Fusarium solani 2, Nocardia asteroides 1 and Streptomyces somaliensis 1. The main drugs used in the treatments were ketoconazole and itraconazole for maduromycotic mycetomas, and cotrimoxazole associated with ciprofloxacin or amikacin for actinomycetic mycetoma. Six patients had to undergo amputation, 25 cases achieved complete clinical remission and 34 showed remarkable improvement.

Actinomycetales↗