Expression of cleaved caspase-3 in renal tubular cells in Plasmodium falciparum malaria patients.

AIM: In Plasmodium falciparum malaria, the clinical manifestation of acute kidney injury (AKI) is commonly associated with acute tubular necrosis (ATN) in the kidney tissues. Renal tubular cells often exhibit various degrees of cloudy swelling, cell degeneration, and frank necrosis. To study individual cell death, this study evaluates the degree of renal tubular necrosis in association with apoptosis in malarial kidneys. METHODS: Kidney tissues from P. falciparum malaria with AKI (10 cases), and without AKI (10 cases) were evaluated for tubular pathology. Normal kidney tissues from 10 cases served as controls. Tubular necrosis was assessed quantitatively in kidney tissues infected with P. falciparum malaria, based on histopathological evaluation. In addition, the occurrence of apoptosis was investigated using cleaved caspase-3 marker. Correlation between tubular necrosis and apoptosis was analyzed. RESULTS: Tubular necrosis was found to be highest in P. falciparum malaria patients with AKI (36.44% ± 3.21), compared to non-AKI (15.88% ± 1.63) and control groups (2.58% ± 0.39) (all p < 0.001). In the AKI group, the distal tubules showed a significantly higher degree of tubular necrosis than the proximal tubules (p = 0.021) and collecting tubules (p = 0.033). Tubular necrosis was significantly correlated with the level of serum creatinine (r = 0.596, p = 0.006), and the occurrence of apoptosis (r = 0.681, p = 0.001). CONCLUSION: In malarial AKI, the process of apoptosis occurs in ATN.

In vivo CNS infection model of Acanthamoeba genotype T4: the early stages of infection lack presence of host inflammatory response and are a slow and contact-dependent process.

This study was developed in order to describe the early morphological events observed during the invasion of two pathogenic strains of Acanthamoeba (genotype T4); A. castellanii and A. culbertsoni, at the olfactory meatus and cerebral, pulmonary, renal, hepatic and splenic tissues levels, an in vivo invasion study. Histological and immunohistochemical description of the events at 24, 48, 72, and 96 h postintranasal inoculations of BALB/c mice was performed. A. castellanii showed a higher invasion rate than A. culbertsoni, which was only able to reach lung and brain tissue in the in vivo model. The current study supports previous evidence of lack of inflammatory response during the early stages of infection. Acanthamoeba invasion of the CNS and other organs is a slow and contact-dependent process. The early morphological events during the invasion of amoebae include the penetration of trophozoites into different epithelia: olfactory, respiratory, alveolar space, and renal tubule, which resemble the process of amoebae invasion described in corneal tissue. The data suggest that after reaching the nasal epithelium, trophozoites continued invasion, separating and lifting the most superficial cells, then migrating and penetrating between the cell junctions without causing a cytolytic effect on adjacent cells. These results reaffirm the idea that contact-dependent mechanisms are relevant for amoebae of Acanthamoeba genus regardless of the invasion site.

Renal tubular dysfunction in patients with American cutaneous leishmaniasis.

Renal dysfunction seen in patients with American cutaneous leishmaniasis (ACL) has been attributed to the use of antimonials for treatment. To determine whether ACL itself causes tubular dysfunction, we measured renal function in 37 patients with ACL prior to their treatment and compared results to that in 10 healthy volunteers of similar mean age. None of the patients presented with glomerular dysfunction; however, 27 had a urinary concentrating defect. There was no statistical difference between groups in the pre- and post-desmopressin test of urine osmolality, but the post-test urine osmolality of the controls was significantly higher. Urinary AQP2 levels, determined by western blot of isolated exosomes, were found to be significantly lower in patients than in controls, whereas that of the cotransporter (NKCC2) was significantly higher. A urinary acidification defect (post-test pH greater than 5.50 following calcium chloride) was found in 15 patients. Pretest plasma bicarbonate was below normal in 12 patients as was the pretest plasma pH in 14. Expression of the Na/H exchanger (NHE3), H(+)-ATPase, and pendrin were all significantly higher in patients with ACL than in controls. A combined urinary concentration and acidification defect was found in 12 patients. Thus, the urinary concentrating defect of ACL may be caused by decreased AQP2, with increased NKCC2 compensatory. Pendrin upregulation may be related to the urinary acidification defect with increased NHE3 and H(+)-ATPase also compensatory. Hence, ACL can cause asymptomatic renal tubular dysfunction.

Interrenal disease in bluegills (Lepomis macrochirus) caused by a new genus and species of myxozoan.

A myxozoan species not matching with any described genus was encountered in a survey of fish parasites of freshwater fishes in New York. The parasite was observed in the kidney tubules of bluegill sunfish Lepomis macrochirus. A new genus is described to accommodate Acauda hoffmani n. gen., n. sp., which exhibits pyriform spores with longitudinal ridges and polar capsules perpendicular to the sutural plane. Spores measure 17.9-21.8 µm long and 6.9-11.0 µm wide, with spore valves each with 11-12 ridges. Two polar capsules measure 9.4-12.5 µm long by 2.9-4.0 µm wide and contain a filament coiled 10-15 times. Phylogenetic analysis places A. hoffmani n. gen., n. sp. as a sister to a Myxobilatus and a Hoferellus species. The clustering of these 3 similar genera in the larger 'freshwater' clade of myxozoans does not support their inclusion in the Sphaerosporidae but instead supports the distinct status of the Myxobilatidae Shulman 1953.

Renal infection by a new coccidian genus in big brown bats (Eptesicus fuscus).

A novel coccidian parasite from the kidney of big brown bats (Eptesicus fuscus) is described. This coccidian (Nephroisospora eptesici nov. gen., n. sp.) was associated with a generally mild, focal or multifocal, well-demarcated cortical renal lesion less than 1 mm in diameter. The lesion represented cystic, dilated tubules with hypertrophied tubular epithelial cells and was present in the kidneys of 29 of 590 bats. Numerous coccidian parasites in various stages of development were present within the tubular epithelial cells and within the cyst lumina. Oocysts were collected from cystic dilated tubules. Thin-walled, sporulated ellipsoidal oocysts measuring an average of 18.9 x 20.8 microm were present in kidney tissue. The oocysts contained 2 sporocysts with 4 sporozoites. A polar body and a prominent oocyst residuum were present in the oocysts, but no micropyle, sporocyst residuum, or Stieda bodies were detected. Analysis of the 18S rRNA gene sequence put the parasite in the Sarcocystidae. The parasite is closely related to Besnoitia, Hammondia, Neospora, and Toxoplasma. Ultrastructural features, such as the presence of an apical complex in merozoites, support the identification of a coccidian. A new genus and species, Nephroisospora eptesicii, is proposed for this unusual coccidian in which the entire cycle is completed in the kidney of a single host; it has a membrane-like oocyst wall, sporogony occurs in the host rather than in the abiotic environment, and the positioning of the parasite by nucleic acid sequence indicates it to be closely allied to Sarcocystis and Besnoitia.

Experimental transmission of malacosporean parasites from bryozoans to common carp ( Cyprinus carpio) and minnow ( Phoxinus phoxinus).

To address whether a fish host is involved in the life cycles of malacosporeans of the genus Buddenbrockia, cohabitation experiments with different bryozoan and fish species were conducted. Samples were analysed by malacosporean-specific PCR, partial sequencing of the 18S rDNA, and light and electron microscopy. Co-habitation challenges with bryozoans resulted in malacosporean infections detected mainly in the kidney of common carp (Cyprinus carpio) and minnow (Phoxinus phoxinus). Sequences of the minnow parasite and of worm-like Buddenbrockia stages in Plumatella repens were identical and showed 99.5% similarity to Buddenbrockia plumatellae and 96.3% similarity to the sequence obtained from carp. One sample, comprising 4-5 zooids of statoblast-raised bryozoans cohabitated with infected carp was PCR-positive, but no overt infection could be observed in the remaining colony. Light and electron-microscopy of kidney samples of infected minnows revealed single cells within kidney tubules, whereas in carp, sporogonic stages were found in kidney tubules. Phylogenetic analysis of the Buddenbrockia spp. known to date placed the carp-infecting species at the base of the B. plumatellae clade, but low posterior probability makes this node questionable. The present study showed that Buddenbrockia spp. were able to infect cyprinid fish, showing stages in kidney-tubules strikingly similar to those of T. bryosalmonae.

Myxidium scripta n. sp. identified in urinary and biliary tract of Louisiana-farmed red-eared slider turtles Trachemys scripta elegans.

During a necropsy investigation of a mortality event occurring at a turtle farm in Assumption Parish, Louisiana, spores of a myxozoan were identified in the renal tubules in 3 of 6, the gall bladder lumen in 2 of 6, and the bile ductule in 1 of 6 red eared slider turtles Trachemys scripta elegans. In total, myxozoa were identified in 4 of 6 turtles. In 1 turtle, renal tubules contained numerous mature spores, had epithelial hyperplasia, granulomatous transformation, compression of adjacent tubules and interstitial lymphocytic nephritis. The genus of myxozoan was Myxidium, based on spore morphology in cytological preparations, in histologic section, and by electron microscopy. In cytological preparation the spores had mean dimensions of 18.8 x 5.1 microm and a mean polar capsule dimension of 6.6 x 3.5 microm. Electron microscopy showed renal tubules contained plasmodia with disporoblasts with spores in various stages of maturation. Ultrastructure of mature spores demonstrated a capsule containing 2 asymmetrical overlapping valves and polar capsules containing a polar filament coiled 6 to 8 times and surrounded by a membrane composed of a double layer wall. The small subunit rDNA gene sequence was distinct from all other Myxidium species for which sequences are available. Additionally, this is the first Myxidium species recovered from a North American chelonian to receive genetic analysis. Although T. s. elegans is listed as a host for Myxidium chelonarum, this newly described species of Myxidium possessed larger spores with tapered ends; thus, we described it as a new species, Myxidium scripta n. sp. This report documents a clinically significant nephropathy and genetic sequence from a Myxidium parasite affecting a freshwater turtle species in North America.

Sporogony of Tetracapsuloides bryosalmonae in the brown trout Salmo trutta and the role of the tertiary cell during the vertebrate phase of myxozoan life cycles.

Tetracapsuloides bryosalmonae is the myxozoan that causes the commercially and ecologically important proliferative kidney disease of salmonid fish species. Immunohistochemistry and electron microscopy were used to examine the development of this parasite within the kidney of the brown trout Salmo trutta. The main replicative phase of T. bryosalmonae is a cell doublet composed of a primary cell and a single secondary cell. Engulfment of one secondary cell by another to form a secondary-tertiary doublet (S-T doublet) heralded the onset of sporogony whereupon the parasite migrated to the kidney tubule lumen. Within the tubule, the parasite transformed into a pseudoplasmodium and anchored to the tubule epithelial cells via pseudopodial extensions. Within each pseudoplasmodium developed a single spore, composed of 4 valve cells, 2 polar capsules and 1 sporoplasm. The pseudoplasmodia formed clusters suggesting that large numbers of spores develop within the fish. This examination of T. bryosalmonae suggests that the main replicative phase of freshwater myxozoans within vertebrates is via direct replication of cell doublets rather than through the rupturing of extrasporogonic stages, while tertiary cell formation relates only to sporogony. Taken in conjunction with existing phylogenetic data, 5 distinct sporogonial sequences are identified for the Myxozoa.

Parvicapsula bicornis n. sp. and P. limandae n. sp. (Myxozoa, Parvicapsulidae) in Pleuronectidae (Teleostei, Heterosomata) from Denmark.

Two species of Parvicapsula were found in the kidney tubules and the urinary bladder of 2 pleuronectid fish from the northern Oresund, Denmark. The coelozoic, spherical, disporic trophozoites of both species are 10 to 12 pm in diameter. The myxospores of both species are elongate, asymmetrical and slightly curved, and have spherical polar capsules. Parvicapsula bicornis n. sp. (6-8 x 5-6 microm, polar capsule 2.5 microm in diameter) occurs in Pleuronectes platessa. The polar capsules of P. bicornis are arranged symmetrically on either side of the longitudinal axis and its spores differ from other species of Parvicapsula in having two 2-3 microm long posterior processes of different length. Parvicapsula limandae n. sp. (8-11 x 4-5 pm, polar capsule 1.6 microm in diameter) is found in Limanda limanda. The polar capsules are arranged along the longitudinal axis. It differs from Parvicapsula unicornis Kabata, 1962, recorded from L. limanda, in the arrangement of the polar capsules and in the absence of a posterior horn-like projection. The phylogenetic relationship between P. bicornis n. sp., P. limandae n. sp. and other Parvicapsula spp. was examined with their partial small subunit rDNA (SSU rDNA) sequences. P. limandae n. sp. and P. asymmetrica appear to be closely related, while P. bicornis n. sp. and P. minibicornis are the most divergent members of the genus.

Parvicapsula spinachiae n.sp. (Myxozoa, Parvicapsulidae) in Spinachia spinachia (L.) (Teleostei, Gasterosteidae) from Denmark.

Parvicapsula spinachiae sp. nov. is described from Spinachia spinachia (L.) (Teleostei, Gasterosteidae) from the northern Øresund, Denmark. The subspherical disporous plasmodia occur in the renal tubules and urinary bladder; the myxospores were found only in the urinary bladder. The myxospores are ovoid when viewed frontally and curved when viewed laterally. Mean maximum length is 10 microm and mean maximum width 5 microm. They have two spherical polar capsules in the apex and irregular thickenings at the posterior end. The newly described species is compared with the ten known species of Parvicapsula. It is most similar to Parvicapsula unicornis Kabata, 1962 but differs from this species by lacking the prominent suture and the posterior horn-like projection.

Light and electron microscopic observations of Leptotheca koreana n. sp. (Myxosporea) in the kidney of cultured rockfish Sebastes schlegeli.

The structure and sporogenesis of Leptotheca koreana n. sp. from cultured rockfish Sebastes schlegeli from South Korea were studied by light and transmission electron microscopy. Broadly oval spores and disporous pseudoplasmodia were observed in the lumen of renal tubules. Spores were 8.59 +/- 1.25 microm in length, 13.42 +/- 1.0 microm in width in sutural view and 8.13 +/- 0.52 pm in thickness in the plane perpendicular to the suture. The width of each valve was always smaller than spore length. Two spherical polar capsules were equal in size (3.86 +/- 0.45 microm in diameter) containing a polar filament with 6 to 7 turns, opening at the anterior end of the spore. Two uninucleate sporoplasms filled the spore cavity. The asynchronous division of secondary and tertiary cells and asynchronous development in spore formation of the present Leptotheca koreana resembled the disporous sphaerosporids. Cytoplasmic projections of pseudoplamodia were considered to be rhizoids, as they seem to strengthen the attachment to the epithelial cells of the renal tubules. The capsulogenic cells in early sporoblast had large amounts of rough endoplasmic reticulum but had a few Golgi apparatus.

Cytopathological observations on renal tubule epithelium cells in common carp Cyprinus carpio under Trypanoplasma borreli (Protozoa: Kinetoplastida) infection.

Cytological alterations in renal tubule epithelium cells of carp Cyprinus carpio infected with the blood flagellate Trypanoplasma borreli Laveran & Mesnil, 1901 were investigated during the course of a laboratory infection of a highly susceptible carp line. With the development of the parasitaemia, a hyperplasia of the interstitial renal tissue was induced, which resulted in a tubulus necrosis. Cytological changes were already seen in tubulus epithelium cells on Day 7 post injection (PI) of the parasite. The basilar invaginations of the cells fragmented and a swelling of mitochondria was noted. With increasing parasitaemia, on Days 14 and 21 PI, these changes progressed up to the loss of the basilar invagination and high amplitude swellings of mitochondria and deterioration of their internal membrane structures. Cells of the distal tubule segment reacted earlier and more rapidly than cells of the proximal tubule. The cytological alterations suggested a loss of function of the epithelum cells, which most likely resulted in impaired ionic and osmotic regulation of T. borreli-infected fishes. Our findings indicate that in response to the proliferation of the interstitial renal tissue cell structures of the renal tubule cells are altered quickly and in a progressive manner.

Parvicapsula minibicornis n. sp. (Myxozoa, Myxosporea) from the kidney of sockeye salmon (Oncorhynchus nerka) from British Columbia, Canada.

A new species of Myxosporea Parvicapsula minibicornis is described from the kidney of adult sockeye salmon (Oncorhynchus nerka) that had recently returned from the Pacific Ocean to Weaver Creek, a tributary of the Fraser River, British Columbia, Canada. Spores are ovoid, symmetrical, with 2 pyriform polar capsules at the anterior pole. The posterior pole has 2 small, pointed projections. Mean spore dimensions are length 11.0 microm, thickness (perpendicular to suture plane) 6.8 microm, and width (in sutural plane) 7.5 microm. This myxozoan is compared to other described Parvicapsula species and a Parvicapsula sp. from netpen-reared coho salmon (Oncorhynchus kisutch).

Protozoan parasites and pathological findings in Hydromys chrysogaster (Muridae: Hydromyinae) from Queensland.

Tissues from 23 Australian water rats (Hydromys chrysogaster) collected from five localities in central and northern Queensland, Australia, between February 1992 and May 1993, were examined for protozoan parasites and additional pathological changes. We found Klossiella hydromyos in the kidneys, Toxoplasma gondii in the brain and skeletal muscles and Sarcocystis sp. in the somatic musculature. Other pathological findings, including interstitial nephritis, interstitial pneumonia and a tongue abscess, as well as helminth-induced lesions in the lungs, mesenteries, stomach wall and cecal wall were also noted.

Donkey klossiellosis in Kenya.

Out of eight donkeys examined, two had gametogonic and sporogonic stages of Klossiella equi in their kidneys. Gametogonic stages included microgametocytes and macrogametocytes, some of them in syzygy. They were found in enlarged parasitophorous vacuoles situated in epithelial cells of the renal tubules. Sporonts were seen in the epithelial cells protruding into the tubular lumen while sporoblasts, sporocysts and sporozoites were found freely in the tubular lumen. Entire sporocysts were rarely encountered but sporozoites liberated from the ruptured sporocysts could be seen. No inflammatory reaction could be attributed to the presence of these parasites.

Arrested development in a freshwater myxosporean, Myxidium salvelini, following transfer of its host, the sockeye salmon (Oncorhynchus nerka), to sea water.

The duration of infections with Myxidium salvelini, a freshwater myxosporean, in the kidneys of anadromous sockeye salmon (Oncorhynchus nerka) smolts from Cultus Lake, Fraser River system, British Columbia, was followed both in fresh water (FW) and in sea water (SW). The smolts were collected at the outlet of the lake as they migrated seaward, were subsequently held captive in M. salvelini-free FW or SW, and were sampled for presence of the parasite biweekly. Initial prevalence of infection was 80% or higher. In FW-held fish, spores were detectable over the 28-wk period of sampling, but the prevalence of infection with spores and prespore forms declined sharply after 22 wk. Nine weeks after the fish were transferred to SW, spores no longer were present but prespore forms continued to be present at high prevalences for up to 25 wk. SW-held fish were reacclimated to FW 4 wk after the last detection of spores. Spore production was resumed in this group of fish within 8 wk and continued for the next 5 wk, when the study was terminated. This indicates that M. salvelini persisted in an arrested prespore form during the SW holding period. This is the first report of arrested development in a prespore stage of a myxosporean. The physiological changes in the kidney that accompany migration of anadromous salmon from fresh to sea water likely inhibit spore production in M. salvelini. In FW salmonids, M. salvelini appears to have an annual life cycle.

A coccidian (Apicomplexa: Eimeriidae) with extracytoplasmally located stages in the kidney tubules of golden carp (Carassius auratus gibelio L.) (Cyprinidae).

Numerous coccidian stages were found in the kidney tubules of the golden carp (Carassius auratus gibelio). The merogonial and gamogonial stages were localized extracytoplasmally in the microvillous region of the epithelial cells. The host-parasite interface consisted of i) a large area where the parasite was separated from the host cytoplasm by the parasitophorous vacuole membrane only, and ii) a zone of multiple fusions of the host cell membrane investing the parasite to the neighbouring microvilli. The taxonomic status of the extracytoplasmic stages is not clear, however, their possible appurtenance to Eimeria scardinii, which was frequently found in the kidneys of golden carps in the same population, is discussed.

[Coincidental appearance of PKD and Sphaerospora sp. (Myxosporidia) in stock of Salmo gairdneri (Osteichthyes)]. / Koinzidentes Auftreten von PKX und Sphaerospora sp. (Myxosporidia) in Beständen von Salmo gairdneri (Osteichthyes).

For the first time in Europe simultaneous occurrence of PKX and Sphaerospora sp. is recorded in Salmo gairdneri. Myxosporidian (?) forms hitherto not described have been observed in the kidney interstitium and the epithelium of the renal tubules, sporadically also in the swimbladder wall and the intestinal wall, besides the typical PKX organism in the kidney interstitium. Sporogonic stages and spores of a Sphaerospora species have been found in the lumen of the renal tubules. Neither the exact identification of the Sphaerospora species has been possible, nor the final proof, whether the luminal form, the hitherto undescribed extraluminal forms and PKX belong to one another.

Use of cultured renal tubular cells in the study of cell injury.

The use of various types of cultured mammalian renal tubular epithelial cells in the study of cell injury has been reviewed. Permanent cell lines, primary explant cultures, monolayers from individually microdissected tubules, isolated cells and organ cultures have been used. In the majority of studies, cultured cells of normal tissue origin have been treated with a noxious agent and alterations in growth, morphology, biochemical and immunological properties studied. Earliest studies examined infection by parasites and bacteria and the effects of plant and bacterial toxins, carcinogens, metabolic and transport inhibitors, cytoskeletal perturbants, general inhibitors of protein, glycoprotein, DNA and RNA synthesis. More recent studies have concentrated on the effects of specific nephrotoxins, such as heavy metals and aminoglycoside antibiotics and of ischemia which have bearing on the pathogenesis of acute renal failure. An additional approach has been to culture diseased renal epithelia of cystic, diabetic or tumor origin and compare their properties with those of normal cultured tubular epithelia. Future studies using cultured renal tubular cells will be valuable in elucidating the cellular and subcellular mechanisms of renal epithelial cell injury in disease.