The susceptibility of diverse species of cultured oligochaetes to the fish parasite Myxobolus pseudodispar Gorbunova (Myxozoa).

This study provides detailed information on the invertebrate hosts of Myxobolus pseudodispar (Myxozoa) and explores the susceptibility range of several species and analyses the relevance of the species composition of an oligochaete population. Our findings demonstrate that the oligochaete host range of M. pseudodispar is similarly wide as the number of vertebrate host species. Besides Tubifex tubifex and Limnodrilus hoffmeisteri, Psammoryctides barbatus and Psammoryctides moravicus were also found to be susceptible invertebrate hosts. The genetic characterization of the mitochondrial 16S rDNA of T. tubifex sensu lato revealed that lineages I, II and III are susceptible to M. pseudodispar, whereas T. tubifex lineage VI seems to be non-susceptible. T. tubifex lineage V and L. hoffmeisteri specimens were positive in a M. pseudodispar-specific PCR, but in most cases, the release of mature actinospores could not be detected. Hence, these non-susceptible oligochaetes likely serve as `biological filters` as they remove myxospores from the sediment without producing actinospores. Together with the phylogenetic analysis of the susceptible and non-susceptible oligochaete hosts on the basis of mt 16S rDNA sequences, the route of the development of M. pseudodispar in the oligochaete hosts was tracked by in situ hybridization. According to our findings, the gut epithelia seem to be a portal of entry of the sporoplasms, where the development of the parasite also takes place. The basal lamina seems to be involved in the migration of the parasite, and the worm's cellular immune response is activated by the infection.

Reduction of collagen VII anchoring fibrils in the airway basement membrane zone of infant rhesus monkeys exposed to house dust mite.

Collagen VII anchoring fibrils in the basement membrane zone (BMZ) are part of a supracellular anchoring network that attaches the epithelium to the BMZ. Sloughing of airway epithelium in asthmatics (creola bodies) is a pathology associated with the supracellular anchoring network. In a rhesus monkey model of house dust mite (HDM)-induced allergic asthma, we found increased deposition of collagen I in the BMZ. In this study, we determine whether HDM also affected deposition of collagen VII in the BMZ. In the developing airway of rhesus monkeys, the width of collagen VII anchoring fibrils in the BMZ was 0.02 +/- 0.04 microm at 1 mo of age. At 6 mo the width had increased to 1.28 +/- 0.34 microm and at 12 mo 2.15 +/- 0.13 microm. In animals treated with HDM, we found a 42.2% reduction in the width of collagen VII layer in the BMZ at 6 mo (0.74 +/- 0.15 microm; P < 0.05). During recovery, the rate of collagen VII deposition returned to normal. However, the amount of collagen VII lost was not recovered after 6 mo. We concluded that normal development of the collagen VII attachment between the epithelium and BMZ occurs in coordination with development of the BMZ. However, in HDM-treated animals, the collagen VII attachment with the epithelium was significantly reduced. Such a reduction in collagen VII may weaken the supracellular anchoring network and be associated with sloughing of the epithelium and formation of creola bodies in asthmatics.

Migration of African trypanosomes across the blood-brain barrier.

Subspecies of the extracellular parasite, Trypanosoma brucei, which are spread by the tsetse fly in sub-Saharan Africa, cause in humans Sleeping Sickness. In experimental rodent models the parasite can at a certain stage of disease pass through the blood-brain barrier across or between the endothelial cells and the vessel basement membranes. The laminin composition of the basement membranes determines whether they are permissive to parasite penetration. One cytokine, interferon-gamma, plays an important role in regulating the trypanosome trafficking into the brain. Treatment strategies aim at developing drugs that can impede penetration of trypanosomes into the brain and/or that can eliminate trypanosomes once they are inside the brain parenchyma, but have lower toxicity than the ones presently in use.

Analysis of fibronectin expression in the bilharzial granulomas and of laminin in the transformed urothelium in schistosoma haematobium infested patients.

UNLABELLED: The bilharzial granulomas and urothelial transformation are common findings in Schistosoma haematobium infested patients. We hypothesize that the distribution of extrinsic (fibronectin, FN) and intrinsic basement membrane (BM) proteins (laminin, LN) is altered during the evolution of these lesions. METHODS: To test this hypothesis, 70 cystectomy specimens, entailing variable associations of normal and dysplastic urothelium (all cases), and bilharzial granulomas were examined for FN and LN protein expression. RESULTS: The biharzial granulomas were formed of admixture of CD3+T cells, CD68+histiocytes and CD220B cells. The CD3+T cells and and CD68+histiocytes were the predominant cell populations. Increased deposition of FN occurred with the evolution from cellular (loose fibrillary network, 20 cases) to fibrocellualr (dense fibrillary network, 30 cases) to fibrotic (tight conglomerates, 20 cases) granulomas. Alternatively, BM staining for LN was linear and continuous underlying normal and metaplastic urothelium. In dysplastic urothelium (20 cases), it showed breaks in continuity. CONCLUSIONS: Alterations of FN and LN occur during the development of the bilharzial granuloma and urothelial transformation.

Human cerebral malaria: a pathological study.

The following report using light and electron microscopic and immunological techniques is based on a series of 19 Burmese patients who died of cerebral malaria. The principal change was blockage of cerebral capillaries by Plasmodium falciparum-infected erythrocytes. Ring hemorrhages and segmental necrosis of cerebral capillaries were common. Cerebral edema was variable in these cases. Electron-dense knobs, 40 X 80 nm in size, which protruded from the membrane of infected erythrocytes, formed focal junctions between endothelial cells and erythrocytes. These junctions resulted in the entrapment of erythrocytes and caused blockage in the capillary lumen. Immunoperoxidase study revealed that P. falciparum antigens and IgG deposits in the capillary basement membrane. This implies that damage to the cerebral capillary could be related to immune mechanisms.

Localization of Borrelia burgdorferi in murine Lyme borreliosis by electron microscopy.

Lyme borreliosis is a newly recognized systemic infection with protean clinical manifestations. Because the localization of the causative spirochete (Borrelia burgdorferi) in infected tissues is unknown, we used electron microscopy to find spirochetes in the hearts of chronically infected mice. There were three predominant locations for the spirochete in the hearts. In mice infected for one month or less, the spirochetes were mostly in or around blood vessels. They were either in the lumen or in the perivascular space. Mice infected for more than one month had B. burgdorferi in cardiac myocytes as well, often with clear spaces around them. The third area in which spirochetes were common was collagen fibers; the borreliae were wrapped around fibers with their long axis parallel to the fibers. The number of spirochetes was relatively low, but there was no appreciable decrease in numbers of spirochetes with increasing time postinfection. Inflammatory infiltrates were primarily in the endocardium and pericardium, but spirochetes were generally not in or near areas of inflammation. These data are consistent with previously published information that have identified the heart as a site of chronic infection and inflammation in the mouse. The studies extend our understanding of the behavior of the spirochete in vivo by identifying common locations of B. burgdorferi and by noting the disparity between infection and inflammation.

Knob antigen deposition in cerebral malaria.

Plasmodium falciparum-infected erythrocytes attach to the endothelial cells via electron-dense knobs and this attachment has been suggested as one of the contributing factors in the development of cerebral malaria. Monoclonal antibodies against an 80-95 Kd knob protein were prepared and applied to brain tissue from cerebral malaria patients. The deposition of the 80-95 Kd knob protein antibodies was observed in the basement membrane of cerebral capillaries by the peroxidase anti-peroxidase method. This result indicates involvement of knob protein deposition in the pathogenesis of cerebral malaria.

Invasive amebiasis in naturally infected New World and Old World monkeys with and without clinical disease.

Histopathological preparations of cecum and colon from monkeys naturally infected with invasive Entamoeba histolytica were examined to determine the distribution of amebae in the tissues and the types of lesions, if any, associated with them. Infections were studied in 3 New World species (10 Callicebus moloch, 1 C. torquatus, and 2 Aotus trivirgatus) and 3 Old World species (8 Macaca mulatta, 6 Erythrocebus patas, and 1 Cercopithecus aethiops). Amebiasis was recorded as the principal or a contributing cause of death of all of the 13 New World monkeys and in 6 of the 15 Old World monkeys; amebiasis was detected in the rest of the monkeys only after tissues were re-examined specifically for amebae. Amebae causing no apparent damage were found in the lamina propriae, mainly at the muscularis mucosae. Most frequent were colonies or aggregates of amebae in the crypts between the epithelium and basement membrane, causing either no evident necrosis or changes ranging from necrosis and disarrangement of adjacent cells to complete destruction of the epithelium and reduction of the cells to pyknotic bodies. A lesion interpreted as possibly characteristic of carrier-state invasive amebiasis was destruction of the epithelium in patches of mucosal crypts, not leading to ulceration. Uncommon but present in both New and Old World monkeys were typical areas of surface erosion and classical flask-shaped ulcers. The observations show that in some species of Old World monkeys amebiasis can be invasive without causing clinical disease.

The ventricular ependyma of mice infected with Trypanosoma brucei.

The fine structure of ependymal cells lining the cerebral ventricles of normal mice and of mice infected with Trypanosoma brucei was examined by transmission electron microscopy. Most of the ependymal cells had been stripped from the ventricular surface of the brain in infected animals but some of the remaining ependymal cells contained intracellular trypomastigotes. The same process of stripping had occurred in a single human brain that was included in the series, but intracellular forms were not found. The significance of the intracellular forms and the implication of the stripping of ventricular ependymal cells are discussed in relation to the pathogenesis of sleeping sickness.

Immunohistochemistry of parasitic subepidermal vesiculobullous disease in American badgers (Taxidea taxus).

Some populations of free-ranging American badgers (Taxidea taxus) develop a distinctive seasonal dermatitis due to the subcutaneous filariid Filaria taxideae. Subepidermal vesicles that contain filarial ova develop in thinly haired skin of the inguinal area, proximal thigh, and ventral abdomen. The purpose of this study was to establish by immunohistochemistry whether basement membrane components colocalized with the roof or floor of vesicles and to confirm that filarial ova occur in intradermal vessels. Samples of skin with characteristic F. taxideae-induced subepidermal vesicles were collected from 10 adult male (n = 8) and female (n = 2) badgers. Samples were fixed in formalin for 1-4 days and processed routinely into paraffin wax. Immunohistochemical staining for basement membrane was attempted with anti-collagen IV antibodies (AM168-5M, AR079-5R, AB748) and antilaminin antibodies (MA078-5C, AR078-5R, L-9393). Optimal results in skin from badgers were obtained using a biotin-streptavidin technique and AR079-5R (anti-human collagen IV) and AR078-5R (anti-murine laminin). There was positive staining of the floor of vesicles in 5 of 6 badgers tested with antibodies to laminin and collagen IV. In 5/10 badgers, filarial ova and first stage F. taxideae larvae were found in dilated vascular channels of the upper dermis, and these vessels stained positively for factor VIII-related antigen. The results suggest that F. taxideae-induced subepidermal separation occurs consistently in the lamina lucida portion of the basal lamina and that filarial ova occur in dermal vessels.

Kidney ultrastructural lesions in dogs experimentally infected with Dirofilaria immitis (Leidy, 1856).

Kidneys of 16 beagles with experimentally induced heartworm (Dirofilaria immitis) infections and 4 heartworm-nai;ve dogs were studied by light and electron microscopy. The infections were induced either by subcutaneous injection of infective larvae or by the transplantation of adult parasites, and infection periods varied from 111 to 818 days and 365 to 923 days, respectively. One control group of heartworm-naïve dogs and four groups of heartworm-infected dogs, which were divided according to the type and the length of infection, were used. In the infected dogs, thickening of the glomerular basement membrane (GBM), the presence of dense deposits in the GBM, and foot process effacement were the most frequent lesions observed. In some dogs, electron dense deposits were seen in the GBM and the mesangium and/or enlargement of the mesangial matrix could be characterized. The longer the infection period, the thicker the GBM and the more common the occurrence of foot process effacement. In general, these alterations were more evident in animals that had been infected for more than 1 year, had high microfilaremia, and had 14 or more parasites in the main pulmonary artery and its branches. The presence of dense deposits suggests that the pathogenesis of kidney disease in dirofilariasis is associated with deposits of immune complexes in the membrane. The finding of ultrastructural changes in dogs with early prepatent infections suggests that immature heartworms, as well as microfilariae and possibly adult worms, contribute to the glomerulonephropathy.

Invasion of chicken caecal and intestinal lamina propria by crypt epithelial cells infected with coccidia.

The development of second generation schizonts of Eimeria necatrix and E. tenella was studied with the electron microscope. Invasion of the crypt epithelial cells by merozoites of the first generation schizonts caused changes in the morphology of the infected cells and stimulated their migration into the lamina propria through breaks which appeared in the basement membrane of the crypts. Second generation schizonts developed in the lamina propria within these crypt cells whose epithelial origin was confirmed by their interconnection by desmosomes and tight junctions and by their possession of characteristic microvilli. A comparison is made between this invasion of the lamina propria by parasitized cells and invasion of connective tissue by malignant epithelial cells; the possible mechanisms involved are discussed.

Penetration of the mosquito midgut wall by the ookinetes of Plasmodium yoelii nigeriensis.

The penetration route of ookinetes of Plasmodium yoelii nigeriensis in the midgut of a mosquito, Anopheles omorii, was investigated by electron microscopy. Within 15-18 h after an infective blood meal, ookinetes could be seen in the midgut lumen, in the process of entering the midgut wall, or lodged between the basement membrane and the basal lamina. The morphology of the ookinetes and their transformation into early oocysts were found to be similar to those previously reported. Ookinetes penetrated the midgut wall by the intercellular route; however, the intracellular occurrence of the parasite was also observed. Vacuoles appeared around the penetrating ookinetes during the penetration process, but no change in the electron density of the rhoptry-microneme complex was noted.

Persistent indocyanine green (ICG) fluorescence 6 weeks after intraocular ICG administration for macular hole surgery.

BACKGROUND: Macular hole surgery including vitrectomy and peeling of epiretinal membranes and the internal limiting membrane (ILM) has become a standard procedure in retinal surgery. Poor visualization of epiretinal membranes and the ILM is an obstacle to successful surgery. Recently, indocyanine green (ICG) has been reported to be a helpful intraocular substance in identifying these membranes. METHODS: In a case of stage IV macular hole, epiretinal membranes and ILM were intraoperatively stained with three drops of 1:9 diluted ICG. After 1 min incubation the vitreous cavity was rinsed with Ringer's lactate solution, and the membranes were peeled. Autologous thrombocytes were applied to the macular hole, and the eye was endotamponaded with 20% SF6 gas. Six weeks postoperatively, visual acuity was measured and fundus photographs and autofluorescence images, as well as a multifocal ERG, were obtained. RESULTS: Intraoperatively, the ILM could be nicely visualized by ICG, which allowed immediate peeling. Six weeks after surgery, the visual acuity had improved from 0.1 to 0.7 and the macular hole was closed. Autofluorescence imaging at 795 nm revealed a strong signal. Multifocal ERG recording showed regular amplitudes. CONCLUSION: ICG as an intraocular tool for staining of the ILM is helpful in macular hole surgery. We did not observe any negative effect on retinal function; however, we were surprised to identify traces of ICG in retinal fluorescein angiography images 6 weeks postoperatively.

Interaction of Plasmodium gallinaceum ookinetes and oocysts with extracellular matrix proteins.

Plasmodium ookinetes are elongate, motile and invasive while inside the mosquito gut but promptly metamorphose into spherical immobile oocysts upon coming in contact with the basement membrane surrounding the midgut. There they begin a prolonged growth period characterized by massive DNA synthesis for the production of sporozoites. Living Plasmodium gallinaceum ookinetes attached avidly to the murine extracellular matrix proteins, laminin and collagen type IV. In ELISA-type assays, the main ookinete surface protein, Pgs28 was implicated as a mediator of parasite attachment to these basement membrane constituents. Laminin and collagen IV adhered to ookinete and oocyst lysates spotted onto nitrocellulose membranes. Receptor-ligand blot assays demonstrated that Pgs28 and an oocyst-specific antigen recognized by the mAb 10D6 interact with murine collagen IV and laminin. 10D6 antigen was also recognized by monospecific antiserum against the human epidermal growth factor receptor. Mosquito-derived laminin was incorporated into oocyst capsules of P. gallinaceum growing in Aedes aegypti. We hypothesize that contact with the mosquito basement membrane triggers the transformation of ookinetes into oocysts. Coalescence of basement membrane proteins onto the capsules masks developing oocysts from the mosquito's immune system and facilitates their prolonged extracellular development in the mosquito body cavity.