A study of the spore wall of Encephalitozoon hellem was performed on thin sections, freeze-fracture, and deep-etched samples to obtain information on spore wall organization and composition. Our observations demonstrate that the spore wall is formed by an inner 30-35 nm electron-lucent endospore and an outer 25-30 nm electron-dense exospore. The exospore is a complex of three layers: an outer spiny layer, an electron-lucent intermediate lamina and an inner fibrous layer. Freeze-fracture and deep-etching techniques reveal that the intermediate lamina and the inner fibrous layer result from the different spatial disposition of the same 4-nm thick fibrils. In thin sections the endospore reveals a scattered electron-dense material that appears in the form of trabecular structures when analyzed in deep-etched samples. The presence of chitin in the exospore is discussed.

Animals↗

PubMedDate not supplied

Extraintestinal microsporidiosis in AIDS patients: clinical features and advanced protocols for diagnosis and characterization of the isolates.

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AIDS-Related Opportunistic Infections↗

PubMedDate not supplied

Ultrastructural features of spindle microtubule organization during the nuclear division of Encephalitozoon hellem.

Ultrastructural studies were carried out to describe the nuclear division cycle of a strain of Encephalitozoon hellem isolated from an Italian AIDS patient. The nuclear division occurs during the proliferative vegetative phase and it is characterized by the intranuclear mitosis and by the lack of centrioles. The spindle termini are electron dense spindle plaques (ESPs), resembling to the spindle pole bodies (SPBs) of Saccharomycetes. The ESPs are bifacial organella forming microtubules on both nucleoplasic and cytoplasmic faces. In the outer layer of the spindle plaque are present vesicular elements lined by a double membrane of unknown function. The peculiar morphological features of E. hellem ESPs indicate that both intranuclear spindle and cytoplasmic microtubules are involved in the nuclear division.

AIDS-Related Opportunistic Infections↗

PubMedDate not supplied

Mechanisms of microsporidial cell division: ultrastructural study on Encephalitozoon hellem.

The mitotic process in microsporidian Encephalitozoon hellem, a known human pathogen, has been studied with the aim of elucidating some ultrastructural aspects of its nuclear division. The presence of a nuclear spindle, of "electrondense spindle plaques" associated with the nuclear envelope and of cytoplasmic double walled vesicles are reported. We suggest that these "electrondense spindle plaques" serve as foci for intranuclear and cytoplasmic microtubule arrangements, similar to the microtubule organizing centers within the centrosomes of animal cells. The extent to which the microsporidial division process is comparable with that of more familiar eukaryotes such as yeast cells is discussed.

AIDS-Related Opportunistic Infections↗

PubMedDate not supplied

Evidence of actin in the cytoskeleton of microsporidia.

Using transmission electron microscopy, immuno-electron microscopy, and biochemical techniques such as 2-D electrophoresis and immunoblotting, actin was found in all biological stages of the microsporidia Encephalitozoon hellem and Encephalitozoon cuniculi.

Actins↗

PubMedDate not supplied

Genetic diversity in the microsporidian Encephalitozoon hellem demonstrated by pulsed-field gel electrophoresis.

Encephalitozoon hellem is a microsporidian species responsible for opportunistic infections in AIDS patients. Use of a novel chitinase-based method allowed unsheared chromosomal DNA to be recovered from eleven E. hellem isolates derived from three geographic regions. All isolates were typed by 18S rDNA sequencing, which showed that they belonged to intemal transcribed spacer type 1. After ethidium bromide staining, pulsed-field gel electrophoresis (PFGE) analysis discriminated two new karyotypes comprising 7 and 8 chromosomal bands respectively, ranging in size from 205- to 272-kb pairs. Genomic size was estimated to be 2.39 Mb. Our data indicate PFGE is useful for typing E. hellem and confirms genetic diversity among E. hellem genotypes.

Animals↗

PubMedDate not supplied

Xenotransplantation rejection is antibody-mediated in both sensitized and nonsensitized recipients.

This study analyzes the mechanisms involved in xenotransplantation rejection between closely related species. Hamster hearts were transplanted heterotopically into both normal rats and rats previously sensitized by the transfusion of donor blood. Sequential ultrastructural and immunohistochemical analyses were performed on the grafts, spleens, and sera. The data obtained support the view that induced antibodies directed against the xenograft endothelium play a very important role in producing graft damage. Moreover, the demonstration of antibodies against myocyte determinants suggests that it is possible, in this particular model, that the antiendothelial antibodies are not the only ones involved in the injury process.

Animals↗

PubMedDate not supplied

Biotechnologies and acute hepatic failure.

Orthotopic liver transplantation survival for patients with acute liver failure is poor (50%). Mortality on the waiting list is high due to the lack of donors. For these reasons, the possibility of sustaining hepatic function by extra-corporeal liver perfusion must be considered. In this experimental research, two groups of pigs have been submitted to total de-vascularisation of the liver causing acute hepatic failure. In the first group (4 pigs) no extra-corporeal assistance has been used after total de-vascularisation. All pigs died between 16 and 33 hours after the acute hepatic failure was induced. In the second group (8 pigs) after complete hepatic de-vascularisation an extra-corporeal hepatic support by continuous allo-perfusion of isolated liver was performed using the Abouna-Costa extra-corporeal circuit. All pigs were observed during the acute hepatic failure which lasted from 6.30 to 7.30 hours. The data that were more positively influenced by the extra-corporeal assistance were ammonia and lactates that improved after the application of hepatic assistance.

Animals↗

PubMedDate not supplied

New rapid staining methods of Cryptosporidium oocysts in stools.

Two new extemporaneous negative-staining methods are proposed to detect Cryptosporidium oocysts in stools, using light-green and merbromine in 1% and 2% aqueous solution, respectively. A Ziehl-Neelsen stain as modified by Henriksen and Polhenz was used as a reference technique. A comparison between these two new stains and the reference, a modified Ziehl-Neelsen mod. method gave almost identical sensitivity and specificity. We propose their use in routine diagnosis for enteric cryptosporidiosis.

Acquired Immunodeficiency Syndrome↗

PubMedDate not supplied

Cryptosporidium parvum life cycle in suckling mice: a Nomarski interference-contrast study of a human-derived strain.

Cryptosporidiosis has emerged as one of the life-threatening opportunistic enteric infections in HIV-infected persons. To date, Cryptosporidium parvum is known to infect man via person-to-person or zoonotic transmission. We studied the sequential stages of the life cycle of C. parvum by Normarski interference-contrast microscopy in fresh gut specimens of newborn mice, infected with a strain derived from an AIDS patient with cryptosporidial diarrheal enteritis. Many 4- to 5-day-old suckling BALB/C mice were orally inoculated with 1 x 10(6) oocysts, obtained by acid flocculation of the patient's stools. The animals were sacrificed from 4 to 96 h post-infection and the ileum was examined microscopically. All stages of the asexual life cycle of C. parvum, from excysted sporozoites in the intestinal lumen through the development of type II mature meronts, 12- to 72-h post-infection, were documented by extemporaneous microscopic evaluation of fresh gut samples. The sexual cycle, characterized by the appearance of micro- and macrogametocytes, followed by a zygote developing into a sporulated oocyst, was documented as early 48-h post-infection. Our Nomarski interference-contrast observations on the life cycle of C. parvum yielded data comparable with those originally published by Current and Reese, and confirm the results of previous electron microscopic studies performed by several other authors.

Acquired Immunodeficiency Syndrome↗

PubMedDate not supplied

Influence of chronic osteomyelitis on skeletal growth: analysis at maturity of 26 cases affected during childhood.

Twenty-six patients who had suffered from chronic osteomyelitis since childhood were followed after skeletal growth. The follow-up ranged from 11 to 41 years, with an average of 23.4 years. At the end of growth, 22 of our 26 patients did not show any deformity of the involved limb. At follow-up, four of 26 patients showed shortening and angular deformity of the affected limb. Irreversible damage of the growth plate, due either to the extreme virulence of the pathogen or to inappropriate surgical treatment, was responsible for the deformities.

Adolescent↗