Ultrastructural analysis of posterior polar endocytic phagocytosis by leishmania amastigotes

Leishmania spp. go through a complex life cycle. Developmental forms alternate between elongated, flagellated, motile, extracellular-promastigote forms; and aflagellar, ovoid amastigote-bodies. Mechanisms for survival and procurement of nutrients differ according to stage-specific requirements. To present a mechanistic insight into phagocytosis by protists, and the developmental regulation of endocytosis, achieved by investigation of the ultrastructural interaction of two Leishmania isolates from Egypt, one cutaneous and one visceral, with their host cell cytoplasm. Two leishmanial strains were used. One isolate was from a patient's cutaneous lesion acquired in northern Sinai [SH], and the other obtained from pools of livers and spleens of stray dogs from Agamy resort in Alexandria [D3]. Isolation and maintenance of promastigote and amastigote stages was extracellularly in Offut's medium and intracellularly in laboratory out bred male Syrian hamsters. Culture pellets and biopsies 1 mm thick from various hamster tissues were fixed in cold 2.4% gluteraldehyde in 2% Ca cacodylate buffer [pH 7.2]. The specimens were processed for electron microscopy. Ultrathin sections were cut on a LBK Reichard ultra microtome and post stained with uranyl acetate in lead citrate solution. Sections were examined in a Zeiss EM 952 electron microscope. In amastigotes the subpellicular microtubules, which form the cytoskeleton support for the pellicular membrane, showed pronounced free endings at the posterior pole of the parasites, still covered by the plasma membrane. The posterior area deficient of microtubules formed a cup-like invagination of variable depths according to the parasite's endocytic activity. Evidence of phagocytosis by tissue forms of both isolates is exhibited by the similarity of homogenous bodies engulfed in the posterior invaginations and the host cell cytoplasm. The exhibition of endocytic phagocytosis by intracellular Leishmania supports the concept of a common origin of protists from a phagocytic cell ancestor, and is evidence that phagocytosis, as a criterion, is not secondarily lost in the genus

Counter immunoelectrophoresis, a modified technique for the identification of blood meals of sandflies collected from Qualyobia governorate, Egypt

Specificity and sensitivity are very important when investigating the blood meals of an insect vector, particularly those having different hosts. Several techniques are used for the identification of the blood meals. Counter immunoelectrophoresis is the technique of choice. The modification was to secure saving of time and least amount of materials. In this paper, a modified technique of the counter immunoelectrophoresis [CIEP] was used for the identification of the blood meal of wild Phlebotomus papatasi collected from different sites in Qalyoubia Governorate. Eight antisera were used. These were human, cat, dog, rat, sheep, goat, bovine, and avian. The results showed that 99.52% of 832 female P. papatasi contained human blood, 0.12% [one female] contained only avian blood, and 0.36% or three females each contained mixed blood of human together with dog blood [one], rat blood [one] or avian blood [one]. P. papatasi is an anthropophilic insect, but in rare cases, it is zoophilic

Assessment of the current serodiagnosis of human hydatid disease.

Broad evaluation of the diagnostic specificity of the IHAT for hydatidosis revealed the occurrence of cross seroreactivity especially in malignancy, liver diseases and mixed connective tissue disorders. Cases with liver involvement showed the highest frequency of non specific reactions as well as an increased frequency of high cross reacting titres. On a comparative assay using Elisa and crude protoscolices extract as an antigen, the non specific antibodies activity in most of the cross reacting heterologous sera was abolished. Comparing titres of known hydatid sera by Elisa and IHAT, a considerably higher antibodies activity was demonstrated by the former. By virtue of this great sensitivity, Elisa can substantially serve for the distinction of actual hydatid sera form reacting heterologous sera. It is also obvious that cross reactions can be diluted out. Hence, the test seems to be of value not only in seroepidemiological surveys but also for early diagnosis of the disease

Assessment of sarcocystis infection in patients with soft tissue rheumatism: preliminary evaluation of the diagnostic reliability of the IFAT in human

In preface to investigate patients with soft tissue rheumatism [myositis] for a probable underlying aetiology of Sarcocystis infection, the IFAT was standardized and evaluated. The specificity of Sarcocystis antigen prepared from a S. fusiformis strain isolated from the oesophagus of naturally infected cattle was tested against sera with +ve rheumatoid, +ve antinuclear and +ve anti - DNA factors, which are most likely to occur in patients with connective or mixed connective tissue diseases who may also present with myositis as well as sera from Toxoplasma infected individuals since both parasites are phylogenetically closely related and antibodies incidence in patients with connective tissue diseases as an opportunistic infection. The results showed absolute preclusion of false positive reactions. For sensitively, patients with different muscle complaints were examined. Three cases out of twenty showed specific antibodies. The present issues obviously indicate the validity of the IFAT for the serodiagnosis of sarcocystosis in human cases. The approach is much promising in clinical applications. By revealing the infection as an aetiology of some cases, which may be misdiagnosed, much hazards of inappropriate treatment will be presumably avoided

Morphogenesis of the flagellum and its associated structures in leishmania

Electron microscopic study of the flagellar apparatus of promastigote and amastigote forms of Leishmania revealed major differences. Promastigotes were characterized by possessing a paraxial rod with a well developed lattice-like complex alongside the emerging axoneme enclosed within the flagellar sheath. The latter was anchored to the protozoan plasma membrane by focal or spot-like macular desmosomes at the emergence site. With cytodifferentiation to amastigotes there was a notable reduction in the axonemal size and its microtubular elements, absence of paraxial rod and a remarkable binding of the endocellular flagellum to its pocket through dense zonular desmosomal adhesions

Ultrastructure of the cyst wall of S Lindemanni with pathological correlations

Electron microscopy of skeletal muscle biopsy from a case of human sarcocystosis revealed a new cyst type of S. lindemanni. The sarcocyst appeared large having a thick cyst wall with evident septa extending into the cyst and, characteristically, broad branched cauliflower like protrusions extending into the pericystic zone. This cyst type appeared to be highly pathogenic. In addition to the complete myofibrillar lysis of the infected muscle fibre there were delamination of the neighbouring myofibres, disruption of the sarcomeric orientation with diarrangement and bending of the Z bands and loss of the T and L-myofibrillar pattern in the pericystic zone. Features of myositis such as the presence of abundant lysosomal structures, myofibrillar disarray and glycogen formations were detected. These cytopathogenic signs were obviously attributed to the structural criterion of the cyst wall. The findings not only invalidate the concept that pathological conditions associated with human sarcocytosis are accidental, but also stress: the value of electron microscopy in inducing relevant typing of sarcocysts on basis of their morphologically expressed pathogenic properties

Effect of dexamethasone on the development of pneumocystosis in rats

Dexamethasone proved an active agent in the provocation of experimental Pneumocystis pneumonia in rats. Different treatment regimens were associated with changes in the prepatent period, survival time of the animals, intensity of infection and lung reactions. The findings clearly indicate that opportunistic pneumocystosis tends to occur more frequently when synthetic steroid derivatives are used as substitutes in clinical practice

Scanning electron microscopy of trichomonas vaginalis

By scanning electron microscopy [SEM], T. vaginalis surface appeared pleated with crater-like depressions. All the flagella appeared to start off in a single bundle from a shallow depression with a prominent rim. The side carrying the undulating membrane is extensively ruffled having a mulberry-like appearance to which flocculent material was frequently adherent. T. vaginalis nutrition appeared to proceed through pseudopodia-like extensions and phagocytosis by a constant deep invagination at the anterior pole which seems to be a cytostome. The mulberry-like surface may serve adhesion of T. vaginalis to the host cells and probably increases the surface area for exchange of nutrients, metabolites and parasite derived factors