Kinetics of Trypanosoma cruzi destruction in the mouse spleen

Massive destruction of parasitized splenic macrophages was histologically observed at the height of a virulent infection caused by Trypanosoma cruzi (Y strain) in the mouse. This was coincident with a sudden drop in parasitemic curve. Most of the animals died at this point, probably due to the liberation of toxic products, such as TNF, following the massive destruction of parasitized cells. However, parasitized-cell destruction indicated the transition from susceptibility to resistance. Although it has been extensively studied in vitro, this study contributes with the morphological counterpart observed in vivo by optical and electron microscopy. When infected animals were specifically treated during early infection transition to chronic phase was immediately observed without splenic parasitism. Animals that apparently recovered from massive cell-destruction in the spleen showed evidences of a rapid restoration of splenic architecture.

Invasive aspergillosis in a user of inhaled cocaine: rhinosinusitis with bone and cartilage destruction

Aspergillosis is an infection caused by saprophytic fungi of the genus Aspergillus, which typically occurs in immunosuppressed individuals, but has also been reported in immunocompetent patients. The main routes of entry are the respiratory tract, skin, cornea, and ear, and the infection may be localized or disseminated by contiguity or vascular invasion. We report a severe case of rhinosinusitis with cutaneous involvement, caused by invasive aspergillosis, in an immunocompetent user of inhaled cocaine. Invasive aspergillosis related to cocaine abuse has not yet been reported in the literature. After itraconazole treatment and surgical debridement, complete clinical remission was achieved. Nasal reconstruction with a skin graft over a silicone prosthesis resulted in a satisfactory esthetic outcome.

Host tissue destruction by Entamoeba histolytica: molecules mediating adhesion, cytolysis, and proteolysis

Entamoeba histolytica, the protozoan parasite causing human amoebisis, has recently been found to comprise two genetically distinct forms, potentially pathogenic and constitutively nonpathogenic ones. Host tissue destruction by pathogenic forms is belived to result from cell functions mediaed by a lectin-type adherence receptor, a pore-forming peptide involved in host cell lysis, and abundant expression of cysteine proteinase(s). Isolation and molecular cloning of these amoeba products have provided the tools for structural analyses and manipulations of cell functions including comparisons between pathogenic and nonpathogenic forms.

Selective destruction of nigrostriatal dopaminergic neurons does not alter [3H]-ryanodine binding in rat striatum

Dopamine nigrostriatal neurons are important for motor control and may contain a particularly dense population of ryanodine receptors involved in the control of dopamine release. To test this hypothesis, we used a classical model of unilateral selective lesion of these neurons in rats based on 6-hydroxydopamine (6-OHDA) injection into the substantia nigra. Binding of [3H]-GBR 12935, used as a presynaptic marker since it labels specifically the dopamine uptake complex, was dramatically decreased by 83-100% in striatum homogenates after 6-OHDA lesion. On the contrary, no reduction of [3H]-ryanodine binding was observed. The present data indicate that [3H]-ryanodine binding sites present in rat striatum are not preferentially localized in dopaminergic terminals.

Secondary prevention of type 1 diabetes mellitus: stopping immune destruction and promoting ß-cell regeneration

Type 1 diabetes mellitus results from a cell-mediated autoimmune attack against pancreatic ß-cells. Traditional treatments involve numerous daily insulin dosages/injections and rigorous glucose control. Many efforts toward the identification of ß-cell precursors have been made not only with the aim of understanding the physiology of islet regeneration, but also as an alternative way to produce ß-cells to be used in protocols of islet transplantation. In this review, we summarize the most recent studies related to precursor cells implicated in the regeneration process. These include embryonic stem cells, pancreas-derived multipotent precursors, pancreatic ductal cells, hematopoietic stem cells, mesenchymal stem cells, hepatic oval cells, and mature ß-cells. There is controversial evidence of the potential of these cell sources to regenerate ß-cell mass in diabetic patients. However, clinical trials using embryonic stem cells, umbilical cord blood or adult bone marrow stem cells are under way. The results of various immunosuppressive regimens aiming at blocking autoimmunity against pancreatic ß-cells and promoting ß-cell preservation are also analyzed. Most of these regimens provide transient and partial effect on insulin requirements, but new regimens are beginning to be tested. Our own clinical trial combines a high dose immunosuppression with mobilized peripheral blood hematopoietic stem cell transplantation in early-onset type 1 diabetes mellitus.

Antibodies to citrullinated peptides are not associated with the rate of joint destruction in patients with a well-established diagnosis of rheumatoid arthritis

Antibodies to citrullinated peptides are highly specific for rheumatoid arthritis (RA) and represent a significant risk factor for undifferentiated polyarthritis. This prognostic ability may be related to the very diagnostic performance of these autoantibodies, since RA is a more erosive disease than other forms of arthritis. The present study evaluated an association of antibodies to citrullinated peptides and the rate of joint destruction in patients with a well-established diagnosis of RA. Seventy-one patients with RA were evaluated in 1994 and again in 2002 (functional class, joint count, Health Assessment Questionnaire score, hands X-ray). Autoantibodies (rheumatoid factor (RF), anti-perinuclear factor, anti-cyclic citrullinated peptide (CCP) antibodies) and Sharp's index were analyzed blindly. Delta Sharp was calculated as the difference in Sharp's index obtained in 1994 and 2002. During the follow-up the Health Assessment Questionnaire score increased from 0.91 ± 0.74 to 1.39 ± 0.72 (P < 0.001). Similarly, the number of swollen joints increased from 4.6 ± 5.71 to 6.4 ± 4.1 (P = 0.002). The frequency of autoantibodies and anti-CCP titer remained stable; however, serum RF concentration increased from 202.8 ± 357.6 to 416.6 ± 636.5 IU/mL (P = 0.003). Sharp's index increased from 56.7 ± 62.1 to 92.4 ± 80.9 (P < 0.001). No correlation was observed between Delta Sharp and the presence of RF, anti-perinuclear factor, and anti-CCP antibodies at baseline. Antibodies to citrullinated epitopes are specific and early markers for the diagnosis of RA but do not seem to be associated with the rate of joint destruction in patients with a well-established diagnosis of RA.

Thrombocytopenia and leptospirosis

The present study has intended to contribute to the elucidation of the pathogenic mechanisms, involved in the thrombocytopenia and in the bleeding diathesis seen in the course of Leptospirosis. The group of cases included in the present prospective study consisted of 30 patients with Leptospirosis, admitted to the Infectious and Parasitic Diseases Ward, Hospital das Clínicas, Faculty of Medicine, University of São Paulo. The following possible mechanisms of thrombocytopenia have been considered and therefore investigated: platelet consumption, due to disseminated intravascular coagulation; immune-mediated platelet destruction, due to platelet-associated antibodies and an inhibited platelet production in the bone marrow. Thrombocytopenia occurred in 86.6% of 30 patients and did not seem to be immune-mediated by platelet-associated antibodies. Furthermore it did not seem to be due to a disseminated intravascular coagulation consumption. Although there was a statistically-significant correlation between bone marrow platelet production and platelet counts we think that the static microscopic examination of a bone marrow aspirate cannot accurately depict the dynamic mechanisms of platelet production when these cells are being consumed in peripheral blood. Vasculitis should be considered as the most important factor for the pathogenesis of the bleeding disturbances in Leptospirosis. However, we believe that thrombocytopenia, uremia and coagulation disorders, individually or as a group, should be included among the contributing factors that lead to and worsen bleeding episodes, which represent the leading cause of death in this disease.

Pathology of periportal fibrosis involution in human schistosomiasis

Optical and electron microscopical evidences of focal matrix degradation were frequently seen in liver sections of periportal fibrosis caused by schistosomiasis mansoni in man. The material came from 14 wedge hepatic biopsies taken from patients with chronic advanced hepatosplenic disease and undergoing operations for the relief of portal hypertension. Besides the presence of focal areas of rarefaction, fragmentation and dispersion of collagen fibers, the enlarged portal spaces also showed hyperplasia of elastic tissue and disarray of smooth muscle fibers following destruction of portal vein branches. Eggs were scanty in the tissue sections, and matrix degradation probably represented involuting changes related to the progressive diminution of parasite-related aggression, which occurs spontaneously with age or after cure by chemotherapy. The changes indicative of matrix degradation now described are probably the basic morphological counterpart of periportal fibrosis involution currently being documented by ultrasonography in hepatosplenic patients submitted to curative chemotherapy.

Periodontal aspects of the juvenile form of paracoccidioidomycosis

Three cases of the juvenile form of paracoccidioidomycosis are reported. Emphasis has been given to the oral manifestations, particularly the periodontal involvement. The main periodontal findings were: generalized and progressive alveolar bone destruction leading to gingival recession with exposure of the tooth roots, and spontaneous tooth losses. The gingival mucosa was predominantly smooth, erithematous and slightly swollen. These aspects, although rare, may be the earliest signs of the disease and sometimes its only manifestation.

Quantitative analysis of cardiac lesions in chronic canine chagasic cardiomyopathy

Lesions observed in chronic chagasic cardiopathy frequently produce electrocardiographic alterations and affect cardiac function. Through a computerized morphometrical analysis we quantified the areas occupied by cardiac muscle, connective and adipose tissues in the right atrium of dogs experimentally infected with Trypanosoma cruzi. All of the infected dogs showed chronic myocarditis with variable reduction levels of cardiac muscle, fibrosis and adipose tissue replacement. In the atrial myocardium of dogs infected with Be78 and Be62 cardiac muscle represented 34 and 50%, fibrosis 28 and 32% and adipose tissue 38 and 18%, respectively. The fibrosis observed was both diffuse and focal and mostly intrafascicular, either partially or completely interrupting the path of muscle bundles. Such histological alterations probably contributed to the appearance of electrocardiographic disturbances verified in 10 out 11 dogs which are also common in human chronic chagasic cardiopathy. Fibrosis was the most important microscopic occurrence found since it produces rearrangements of collagen fibers in relation to myocardiocytes which causes changes in anatomical physiognomy and mechanical behavior of the myocardium. These abnormalities can contribute to the appearance of cardiac malfunction, arrythmias and congestive cardiac insufficiency as observed in two of the analyzed dogs. Strain Be78 caused destruction of atrial cardiac muscle higher than that induced by strain Be62.

Rat hepatocyte invasion by Listeria monocytogenes and analysis of TNF-alpha role in apoptosis

Listeria monocytogenes, etiological agent of severe human foodborne infection, uses sophisticated mechanisms of entry into host cytoplasm and manipulation of the cellular cytoskeleton, resulting in cell death. The host cells and bacteria interaction may result in cytokine production as Tumor Necrosis Factor (TNF) alpha. Hepatocytes have potential to produce pro-inflammatory cytokines as TNF-alpha when invaded by bacteria. In the present work we showed the behavior of hepatocytes invaded by L. monocytogenes by microscopic analysis, determination of TNF-alpha production by bioassay and analysis of the apoptosis through TUNEL technique. The presence of bacterium, in ratios that ranged from 5 to 50,000 bacteria per cell, induced the rupture of cellular monolayers. We observed the presence of internalized bacteria in the first hour of incubation by electronic microscopy. The levels of TNF-alpha increased from first hour of incubation to sixth hour, ranging from 0 to 3749 pg/mL. After seven and eight hours of incubation non-significant TNF-alpha levels decrease occurred, indicating possible saturation of cellular receptors. Thus, the quantity of TNF-alpha produced by hepatocytes was dependent of the incubation time, as well as of the proportion between bacteria and cells. The apoptosis rate increased in direct form with the incubation time (1 h to 8 + 24 h), ranging from 0 to 43%, as well as with the bacteria : cells ratio. These results show the ability of hepatocyte invasion by non-hemolytic L. monocytogenes, and the main consequences of this phenomenon were the release of TNF-alpha by hepatocytes and the induction of apoptosis. We speculate that hepatocytes use apoptosis induced by TNF-alpha for release bacteria to extracellular medium. This phenomenon may facilitate the bacteria destruction by the immune system.

Disseminated nocardiosis due to Nocardia farcinica: diagnosis by thyroid abscess culture

A previously healthy 75-year-old white male dentist presented with a 6-month history of low-back pain treated with chronic steroid therapy had a Nocardia farcinica infection diagnosed by aspirate of thyroid abscess and six blood cultures. Despite the treatment with parenteral combination of trimethoprim/sulfamethoxazole, the patient failed to respond and died after two days of therapy. Autopsy revealed disseminated nocardiosis, involving lungs with pleural purulent exudate in both sides, heart, thyroid, kidneys, brain, bones, and lumbosacral soft tissue with destruction of L2-L4.

Pathogenicity of Entamoeba dispar under xenic and monoxenic cultivation compared to a virulent E. histolytica

Two xenic isolates and cloned cultures of Entamoeba dispar were submitted to monoxenization using Crithidia fasciculata as the associated organism. Growth in monoxenic cultivation and ability of xenic and monoxenic trophozoites to destroy VERO cells and produce lesions in hamster livers were compared to those of a virulent E. histolytica. Parental and cloned E. dispar under monoxenic cultivation showed a remarkable lower growth than the monoxenic E. histolytica and were avirulent in both in vivo and in vitro tests. When xenically cultured, trophozoites of E. dispar showed a moderate lytic activity against VERO cells (1.5 to 41.8% of destruction) but caused severe hepatic lesions in hamsters as those caused by the virulent E. histolytica (29 to 100% in prevalence and 0.86 to 4.00 in lesion degree). Although E. dispar has not been associated with invasive disease in men, the ability of xenic trophozoites to produce prominent tissue damage in experimental conditions has indicated that some strains have a considerable pathogenic potential when in presence of bacteria.

SURVEY OF SANDFLY FAUNA (DIPTERA: PSYCHODIDAE) IN UBERLÂNDIA, MINAS GERAIS STATE, BRAZIL, 2003-2004

We analyzed the sandflies around houses and domestic animal shelters located in residences close to forests in localities on the banks of the Araguari River, Uberlândia, MG, from February 2003 to November 2004. The phlebotomines were captured in the peridomiciliary area, where Shannon traps were utilized in the peridomicile and CDC traps in animal shelters. 2,783 specimens of sandflies were captured, 2,140 females (76.9%) and 643 males (23.1%), distributed between 17 species. The most abundant species was Nyssomyia neivai (88.1%), followed by Nyssomyia whitmani (3.1%). The presence of Lutzomyia longipalpis was also confirmed, it is the main vector of Leishmania (L.) infantum chagasi which causes visceral leishmaniasis. The presence of species involved in the transmission of leishmaniases in the municipality of Uberlândia is cause for concern. The presence of L. longipalpis indicates that its urbanization may not have been aleatory and instead occurred through the destruction of wild ecotopes. More studies of their occupation in anthropic environments need to be made.

THE SUSCEPTIBILITY OF RECENT ISOLATES OF Schistosoma mansoni TO PRAZIQUANTEL

Introduction: Schistosomiasis is a chronic disease caused by trematode flatworms of the genus Schistosoma and its control is dependent on a single drug, praziquantel (PZQ), but concerns over PZQ resistance have renewed interest in evaluating the in vitro susceptibility of recent isolates of Schistosoma mansoni to PZQ in comparison with well-established strains in the laboratory. Material and methods: The in vitro activity of PZQ (6.5-0.003 µg/mL) was evaluated in terms of mortality, reduced motor activity and ultrastructural alterations against S. mansoni. Results: After 3 h of incubation, PZQ, at 6.5 µg/mL, caused 100% mortality of all adult worms in the three types of recent isolates, while PZQ was inactive at concentrations of 0.08-0.003 µg/mL after 3 h of incubation. The results show that the SLM and Sotave isolates basically presented the same pattern of susceptibility, differing only in the concentration of 6.5 µg/mL, where deaths occurred from the range of 1.5 h in Sotave and just in the 3 h range of SLM. Additionally, this article presents ultrastructural evidence of rapid severe PZQ-induced surface membrane damage in S. mansoni after treatment with the drug, such as disintegration, sloughing, and erosion of the surface. Conclusion: According to these results, PZQ is very effective to induce tegument destruction of recent isolates of S. mansoni.