Comparison of preparation techniques of mixed samples (fungi–helminth eggs) for scanning electron microscopy by critical point drying

We compared three preparation techniques for critical point drying of fungus Paecilomyces lilacinus (Thom) Samson with Toxocara canis (Werner) Johnston and Taenia hydatigena Linneo eggs by scanning electron microscopy. We evaluated filtration (first), centrifugation (second), and phytoplankton network (third) in critical point drying methods. The first and third methods were advantageous for T. canis eggs because they preserved the quantity and quality of samples to obtain better images definition. The best technique for T. hydatigena eggs was the addition of phytoplankton network in critical point drying which preserved these helminth eggs.

Modelling and estimation of physical parameters in a sludge drying system

In this paper is presented the study of a Sludge Drying System used to kill pathogenic organisms living in sludge. The system is modeled and the physical parameters thermal capacity, thermal resistance and thermal time constant are estimated using conventional estimation methods.

Cysticercosis in laboratory rabbits

There are no data on the current incidence of Taenia pisiformis in laboratory rabbits. Two cases of cysticercosis most likely due to T. pisiformis in laboratory rabbits (intermediate host) are presented. Both rabbits had no contact with dogs (final host); their caretakers did not work with dogs, and these caretakers changed into facility scrubs and wore gloves when working with the rabbits. Rabbit 1 may have been infected after being fed hay at our facility. In light of the life cycle of the parasite and the history of rabbit 2, it potentially could have been infected prior to arrival at our facility. There have been only three cases of tapeworm cysts in rabbits in our facility (average daily census, 250) during the last 10 years (incidence, < 1%). This report indicates that although cysticercosis is rare in laboratory rabbits, one should always be aware of such incidental findings. Although it may not produce overt illness in the rabbit, hepatic migration could adversely affect the outcome of some experimental procedures

Cysticercosis in Nepal: a histopathologic study of sixty-two cases

Human cysticercosis, an infection caused by larvae of Taenia solium, is a major public health problem in many developing countries. Sixty-two of 23,402 biopsy cases have been detected as cysticercosis in the last 5 years in Patan Hospital. Most (82%) of the patients presented with solitary skin nodules, another 10% with nodules in the oral mucosa, and 8% in the breast. Forty cases were identified from the Kathmandu valley and the rest from outside Kathmandu. Most patients were younger than 30 years of age (mean, 21+/-11 years). Statistically, there was no difference between males (0.28%) and females (0.24%). The average size of cysticercosis was 19 mm in diameter, and the histology of cysticercosis showed fibrous walled cysts covered by several layered epithelioid cells with a few Langhans' giant cells and infiltration of eosinophils without caseous necrosis. These cysticercosis findings from an endemic area will be helpful for doctors who examine immigrant patients in nonendemic areas.

Orbital cysticercosis

BACKGROUND

We report on a case of orbital cysticercosis in a 27-year-old Burmese man who presented with an orbital swelling 7 months after arriving in Australia.

METHODS

The presenting history and findings are reviewed and treatment options are discussed. A brief review of the life cycle of the tapeworm Taenia solium is provided.

RESULTS

The orbital lesion was successfully treated by surgical excision.

CONCLUSION

Cysticercosis should not be forgotten as a possible cause of unusual orbital lesions.

Autoradiographic analysis of the germinative tissue in evaginated Taenia solium metacestodes

Evaginated Taenia solium metacestodes dissected from infected pork meat were incubated in vitro in RPMI 1640 medium with tritiated thymidine, washed, and further incubated for various chase periods. Worms were fixed and embedded in Poly/Bed and sections were processed for autoradiography. Results showed that all longitudinal sections had a germinative region located 500-700 mm posterior to the apex of the scolex with tegumentary cytons arranged in staggered columns perpendicular to the tegument. After 6-hr pulse and 0-12-hr chase periods, a large number of labeled cells were found in the parenchyma and tegumentary wall, included were myocytons, calcareous corpuscle cells, flame cells, osmoregulatory channel cells, and, in the medullary parenchyma, labeled undifferentiated round cells with a large nucleus, prominent nucleolus, abundant ribosomes, and no cytoplasmic organelles. These undifferentiated cells were not labeled after 24-hr and 48-hr chase periods, an observation that strongly suggests these cells divide and migrate toward the tegument in a pattern similar to that described for other cestodes. The morphology and localization of these cells support the view that they are stem cells that give rise to the various cell types of the tegumentary wall. The results indicate that T. solium contains a germinative tissue similar to that described in other cestodes, in which stem cells proliferate continuously, differentiate, and migrate to the tegument, constituting the main process by which these worms develop from metacestode to the adult stage.

Ultrastructural study of neurosecretory cells in the nervous system in the cestode (Taenia hydatigena)

The neurosecretory cells in nervous system of the Taenia hydatigena was studied light- and electron-microscopically. On the basis of the cytological structure they were divided into two types: type I neurosecretory cells, which containing large dense-cored vesicles, small elongated mitochondria and a large amount of free ribosomes, were located mainly in the central and peripheral nervous system; type II neurosecretory cells were characterized by their moderate amount of free ribosomes, endoplasmic reticulum which contacted with the membranes of perikarya, large ovoid mitochondria, large dense-cored vesicles and their localization in the musculature near serve profiles. The synaptic and nonsynaptic contacts i.e. omega figure and exocytosis release sites were seen in the neuropile, musculature and excretory ducts. The present findings suggest that neurosecretory cells in nervous system may play an important integrative roles of both neuronal and endocrine in the flatworm.

Critical intracellular Ca2+ concentration for all-or-none Ca2+ spiking in single smooth muscle cells

Neurotransmitters induce contractions of smooth muscle cells initially by mobilizing Ca2+ from intracellular Ca2+ stores through inositol 1,4,5-trisphosphate (InsP3) receptors. Here we studied roles of the molecules involved in Ca2+ mobilization in single smooth muscle cells. A slow rise in cytoplasmic Ca2+ ([Ca2+]i) in agonist-stimulated smooth muscle cells was followed by a wave of rapid regenerative Ca2+ release as the local [Ca2+]i reached a critical concentration of approximately 160 nM. Neither feedback regulation of phospholipase C nor caffeine-sensitive Ca(2+)-induced Ca2+ release was found to be required in the regenerative Ca2+ release. These results indicate that Ca(2+)-dependent feedback control of InsP3-induced Ca2+ release plays a dominant role in the generation of the regenerative Ca2+ release. The resulting Ca2+ release in a whole cell was an all-or-none event, i.e. constant peak [Ca2+]i was attained with agonist concentrations above the threshold value. This finding suggests a possible digital mode involved in the neural control of smooth muscle contraction.

In vitro uptake and autoradiographic localization of tritiated gossypol in Taenia taeniaeformis metacestodes

Gossypol, a natural polyphenolic compound, induces growth-inhibitory and antiparasitic effects in Taenia taeniaeformis metacestodes in vivo and in vitro. We investigated the uptake and localization of [3H]-gossypol in this parasite. Metacestodes were incubated in 10(-5) M [3H]-gossypol at 37 degrees C. Parasites steadily took up tritium activity over the first 3 h of incubation, after which a plateau was maintained for the duration of the experiment. Tissue: medium radioactivity ratios revealed that intralarval tritium activity matched extralarval activity within 30 min of incubation and continued to increase with time. Reverse-phase high-performance liquid chromatographic (HPLC) analysis confirmed tissue incorporation of tritium activity that manifested as a single radioactive species. Autoradiography localized [3H]-gossypol to the tegument, calcareous corpuscles, and parenchyma over the first 2 h of incubation. By 6 h, parenchymal radioactivity had disappeared. T. taeniaeformis metacestodes rapidly take up and accumulate [3H]-gossypol in vitro. This accumulation is apparently selective for specific sites, which may have implications for gossypol's metacestocidal action.

The survival of parasite eggs throughout the soil profile

An experiment using lysimeters suggested that the eggs of Taenia saginata and Ascaris lumbricoides survive for only a short time when applied to pasture in sewage sludge. However, a subsequent experiment which followed the survival of eggs throughout the soil profile demonstrated that some T. saginata eggs could still be found at 200 days on the soil surface, and that survival increased down the profile. Rainfall is shown to be able to wash eggs into the soil where they may be afforded protection from radiation and desiccation; this may have little epidemiological significance.

On the histology and ultrasturcture of Cysticercus longicollis, the cysticercus of Taenia crassiceps Zeder, 1800, (Cestoda, Cyclophyllidea)

Studies with both the light and electron microscope on the bladder wall ofCysticercus longicollishave revealed details of its structure and shown that it contains structures comparable with those of adult cestodes. The structure of the everted scolex of the fully developed cysticercus has also been studied. Development of the scolex and rostellum has been briefly considered and is similar to that ofC. fasciolarisandC. pisiformis. The importance of the tegument in both bladder wall and scolex is emphasised.

The rostellar hooks appear first as small cones to which a base is added after some growth has occurred. Mature and immature hooks probably contain keratin. Results of histochemical tests on this and other parts of the cysticercus have been given.

Thanks are due to Dr L. G. Goodwin, Director of the Nuffield Institute of Comparative Medicine, London Zoo, for allowing the author to use the EM 6 B and photographic facilities. Dr J. Mahon of Imperial College, London, kindly read the script, gave advice on it and provided photomicrographic facilities. The author is grateful to the Principal and Governors of West Ham College of Technology for general and financial support of the project.