Stage conversion of Toxoplasma gondii RH parasites in mice by treatment with atovaquone and pyrrolidine dithiocarbamate.

The mouse-virulent RH strain of Toxoplasma gondii is generally considered to have lost its cyst-forming capacity, and conversion of RH tachyzoites into cysts in non-immune mice has previously been shown exclusively following early treatment with sulfadiazine (SDZ). We here describe the development of tissue cysts in mice infected with RH strain parasites and treated with atovaquone (ATO) combined with pyrrolidine dithiocarbamate (PDTC). Groups of Swiss-Webster mice infected intraperitoneally (i.p.) with 10(2) RH tachyzoites were treated with 5, 25 and 100 mg of ATO/kg per day alone or combined with PDTC at 250 mg/kg per day from day 1 postinfection (p.i.) for 14 days. A total of 19 mice survived the 6-week observation period. Of these, brain cysts were recovered in nine (47%), with burdens ranging from 50 to 3120 (mean +/- S.D. = 622 +/- 963). All cyst-harboring mice had high specific IgG antibody levels (1:10,240-1:40,960, corresponding to 500-2000 IU/ml), as did one mouse in which cysts were not demonstrated, which was therefore included in the group of mice with residual infection. Bioassay performed to test the infectivity of these cysts produced acute lethal toxoplasmosis following i.p. inoculation in all instances (100%), and importantly, following peroral inoculation in four (29%). The recovered tachyzoites were highly infectious. In addition, significantly elevated interferon gamma (IFN-gamma) in the treated mice which developed residual infection compared with any group of infection-free (treated or subinoculated) mice, indicates immunological control of the parasite in the latent form. In conclusion, early treatment of mice infected with T. gondii RH tachyzoites with ATO and PDTC induces conversion into tissue cysts, thus providing a new model for studying the mechanism(s) of T. gondii stage conversion.

[Alport's syndrome and benign familial haematuria: light and electron microscopic studies of the kidney].

INTRODUCTION: Hereditary nephropathy is clinically characterized by the familial occurrence in successive generations of progressive haematuric nephritis and neural hearing loss. Hereditary nephropathy of Alport's syndrome (AS) and benign familial (recurrent) haematuria (BFH) are morphologically characterized by specific and diagnostically important thickening and splitting of lamina densa of the glomerular basement membranes. Those lesions can be recognized only by electron microscopy. Hereditary nephritis is usually present clinically with haematuria, and new mutations without a family history of haematuria. It is therefore important to differentiate hereditary nephritis from BFH and no familial haematuria. Thus, electron microscopy is essential in diagnosis of haematuria. OBJECTIVE: The aim of this study was to describe, by light microscopy, constellation of renal alterations by which hereditary nephropathy can be recognized with high probability as well as to compare the diagnostic validity of the findings observed by light and electron microscopy in AS and BFH. METHOD: We examined 48 renal biopsies of the patients with hereditary nephoropathies by light and electron microscopy. Tissue samples were fixed in buffered paraformaldehyde and embedded in paraffin for long-term preservation. For the electron microscopy analysis, the following fixation in 4% glutaraldehyde tissue was postfixed in 1% osmium tetroxide. Thereafter, the following dehydration procedure tissue slices were embedded in epon. RESULTS: Our results demonstrated that the interstitial foam cells, foetal-like glomeruli, minimal glomerular abnormalities with stain less intense in basement membranes, mild irregular mesangial widening, focal thickening of Bowman's capsule, foci of dilatation tubules, tubular ectasia and atrophy, erythrocyte tubules casts were present in hereditary nephritis. Additionally, light microscopic biopsy findings in patients with BFH were either normal or revealed minor changes (e.g. increased mesangial matrix). All biopsies were reevaluated by electron microscopy and ultrastructural findings confirmed the diagnosis of hereditary nephropathies. CONCLUSION: The findings observed by light microscopy represent an important step that leads to a definitive diagnosis of AS and BFH.The definitive diagnosis, however, depends on electron microscopy.

[Value of urinary cytology findings in the diagnosis of acute renal graft rejection]. / Vrednost nalaza citoloskog pregleda urina u dijagnozi akutnog odbacivanja transplantovanog bubrega.

BACKGROUND: Acute rejection of allograft is one of the most serious complications of renal transplantation that requires fast and precise diagnostic approach. In this paper our experience in cytologic urinalysis as a diagnostic method of the acute renal allograft rejection was reviewed. METHODS: The study group included 20 of 56 patients with transplanted kidneys who were assumed for the acute allograft rejection according to allograft dysfunction and/or urine cytology findings. Histological findings confirmed allograft rejection in 4 patients. Urine sediment obtained in cytocentrifuge was air-dried and stained with May-Grunwald-Giemsa. Acute allograft rejection was suspected if in 10 fields under high magnification 15 or more lymphocytes with renal tubular cells were found. RESULTS: Acute transplant rejection occurred in 32.1% patients. In 15 patients clinical findings of the acute renal allograft rejection corresponded with cytological and histological findings (in the cases in which it was performed). Three patients with clinical signs of the acute allograft rejection were without cytological confirmation, and in 2 patients cytological findings pointed to the acute rejection, but allograft dysfunction was of different etiology (acute tubular necrosis, cyclosporine nephrotoxicity). In patients with clinical, cytological and histological findings of the acute allograft rejection urine finding consisted of 58% lymphocytes, 34% neutrophilic leucocytes and 8% monocytes/macrophages on the average. The accuracy of cytologic urinalysis related to clinical and histological finding was 75%. CONCLUSION: Urine cytology as the reliable, noninvasive, fast and simple method is appropriate as the a first diagnostic line of renal allograft dysfunction, as well as for monitoring of the graft function.

[Importance of cytologic examination of urine in the diagnosis of renal transplant function disorders]. / Znacaj citoloskog pregleda urina u dijagnostici poremecaja funkcije transplantovanog bubrega.

BACKGROUND: This paper presents our experience with cytologic examination of urine in diagnosing renal allograft dysfunction. METHODS: The study group included 23 patients with renal allograft dysfunction, selected from 56 patients who underwent renal transplantation. Etiologic diagnosis was made according to the clinical picture, histological findings during allograft biopsy, and cytologic examination of urine. Urine sediment was obtained in cytocentrifuge and was air dried and stained with May Grunwald Giemsa. RESULTS: Out of 23 patients with allograft dysfunction in 18 (78.3%) patient it was caused by acute rejection, and in 5 (8.9%) patients by allograft infarction, cyclosporine nephrotoxicity, acute tubular necrosis and chronic nephropathy. In eighteen patients (78.3%) cytologic examination of urine was pathologic, while in 16 (70%) clinical and histology findings coincided with urine cytology findings. Out of 18 patients with acute allograft rejection in 15 patients cytologic examination of urine coincided with acute rejection. Out of 7 patients with expressed cyclosporine nephrotoxicity, in 5 cytologic examination of urine confirmed the cause of allograft dysfunction, as well as in one of 2 patients with acute tubular necrosis. Cytologic examination of urine indicated parenchymal damage in 2 patients with recurrent disease (membranoproliferative and focal sclerosing glomerulonephritis). In 4 of 5 patients suffering from chronic rejection in a year's monitoring period, urine sediment periodically consisted of lymphocytes, neutrophilic leucocytes, monocyte/macrophages, tubular cells and cylindres, without the predominance of any cell type. In 3 patients allograft dysfunction was caused by infective agents (bacteria, fungus, cytomegalovirus). CONCLUSION: Cytologic examination of urine might be an alternative to histological in diagnosing acute allograft rejection and acute tubular necrosis or nephrototoxicity. Also it might indicate parenchymal disease while the importance of urine cytology in chronic allograft nephropathy needs to be investigated further.

Lupus nephritis: histopathologic features, classification and histologic scoring in renal biopsy.

Lupus nephritis (LN) is one of the most significant manifestations in systemic lupus erythematosus (SLE), although in some cases there is no direct correlation among clinical, serologic and histologic findings. Therefore, renal biopsy and histopathologic classification by the activity and chronicity assessment of LN are considered necessary before the initiation of the treatment. In this paper 311 renal biopsies in patients with LN were analyzed and classified according to the WHO Classification published in 1974. Renal biopsy specimens were routinely processed for standard analysis by light microscopy (LM), immunofluorescent (IF), and electron microscopy (EM). Biopsy findings were compared with the common clinical symptoms. It is important to recognize that histopathologic lesions in the analyzed tissue might precede the symptoms and clinical manifestations, and therefore are an important factor in the appropriate therapeutic approach. Histopathological assessment of the class of LN represents an important predictor in most patients because the lesions of LN class I and class II most often have no progression and consequently do not require an aggressive treatment. Diffuse proliferative glomerulonephritis (class IV) as a severe form of renal lesion requires the application of high doses of corticosteroids and cytotoxic medicaments. The established quantitive indexes have significant predictive value. Activity index (AI) evaluates the presence of fresh inflammatory and potentially reversible lesions and chronicity index (CI) evaluate the presence of irreversible glomerular lesions such as sclerosis, tubular atrophy, interstitial fibrosis, etc. High AI and low CI, particularly in the class IV of LN, suggest the necessity of an aggressive treatment of the inflammatory process aiming to preserve the renal function. High CI and low AI characterize irreversible sclerosing lesions, where an aggressive treatment is considered unnecessary. Our experience suggests the necessity of introducing the new morphologic elements into the activity and chronicity scoring system which would correlate better the clinical symptoms. This should provide higher reliability of scoring, since it evaluates important elements in clinical-morphologic diagnosis of LN.