Little is known about the life cycle and mode of transmission of Dientamoeba fragilis. Recently it was suggested that fecal–oral transmission of cysts may play a role in the transmission of D. fragilis. In order to establish an infection, D. fragilis is required to remain viable when exposed to the pH of the stomach. In this study, we investigated the ability of cultured trophozoites to withstand the extremes of pH. We provide evidence that trophozoites of D. fragilis are vulnerable to highly acidic conditions. We also investigated further the ultrastructure of D. fragilis cysts obtained from mice and rats by transmission electron microscopy. These studies of cysts showed a clear cyst wall surrounding an encysted parasite. The cyst wall was double layered with an outer fibrillar layer and an inner layer enclosing the parasite. Hydrogenosomes, endoplasmic reticulum and nuclei were present in the cysts. Pelta-axostyle structures, costa and axonemes were identifiable and internal flagellar axonemes were present. This study therefore provides additional novel details and knowledge of the ultrastructure of the cyst stage of D. fragilis.

Harmful algal blooms caused by raphidophyte species of the genus Chattonella (i.e. Chattonella antiqua, Chattonella marina and Chattonella ovata) have been documented in temperate coastal regions around the world. To understand the effects of physicochemical factors on bloom development of Chattonella spp., we investigated the variations of vegetative and resting cells (i.e. cysts) of Chattonella spp. and environmental variables in two coastal environments, Uranouchi Inlet (extremely closed) and Nomi Inlet (semi-closed), with contrasting enclosed natures. Although the vegetative cells and cysts of Chattonella spp. were distributed in both coastal regions, the densities were remarkably higher in Uranouchi Inlet than in Nomi Inlet. The mud content in the sediments of Uranouchi Inlet was also higher than that in the sediments of Nomi Inlet, meaning that fine particles such as cysts are likely to accumulate in the former region. Because of the extremely closed nature of Uranouchi Inlet, warm oceanic waters of the Kuroshio Current penetrate the inlet only infrequently. These results suggest that the closed nature of coastal regions is an important factor influencing either water exchange or the resultant accumulation of Chattonella cells in coastal environments.

Cardiac valve cysts are rare beyond infancy. The tricuspid and mitral valve are the most common sites, with few reported cases of pulmonary valve cysts in the literature. This case illustrates a pulmonary valve cyst mimicking a tumour in a child 13 years after cardiac surgery. Although these lesions are extremely rare, they could be considered in the differential diagnosis in patients presenting with valvular mass lesions.

Dental assessments are important before the commencement of radiotherapy to the head and neck area to assess the teeth and associated structures lying in the treatment field and to inform the patient of the effects of radiotherapy on the oral cavity. This case report documents an incidental radiographic finding of a mandibular cystic lesion and its impact on the radiotherapy planning and decision making to proceed with radiotherapy.

Several conditions that allow the preservation, storage and rapid, efficient recovery of viable Acanthamoeba castellanii organisms were investigated. The viability of trophozoites (as determined by time to confluence) significantly declined over a period of 12 months when stored at −70°C using dimethyl sulfoxide (DMSO; 5 or 10%) as cryopreservant. As A. castellanii are naturally capable of encystment, studies were undertaken to determine whether induced encystment might improve the viability of organisms under a number of storage conditions. A. castellanii cysts stored in the presence of Mg2+ at 4°C remained viable over the study period, although time to confluence was increased from approximately 8 days to approximately 24 days over the 12-month period. Storage of cysts at −70°C with DMSO (5 or 10%) or 40% glycerol, but not 80% glycerol as cryopreservants increased their viability over the 12-month study period compared with those stored at room temperature. Continued presence of Mg2+ in medium during storage had no adverse effects and generally improved recovery of viable organisms. The present study demonstrates that A. castellanii can be stored as a non-multiplicative form inexpensively, without a need for cryopreservation, for at least 12 months, but viability is increased by storage at −70°C.

Most thyroid cysts are benign; however, they require aspiration if symptomatic or atypical on ultrasound scanning, and ablation with ethanol injection if recurrent. We have systematically studied the use of new safety technologies for surgical procedures, which protect both the surgeon and the patient. Here, we describe the use of one such technology, the reciprocating procedure device, which enables simpler, safer, more efficient and less painful thyroid cyst aspiration and therapeutic ablation.

Generally, epiglottic cysts have been treated by the puncture technique or surgical resection. However, these techniques can result in accidental injury to the cyst wall. As a result, the contents of the cyst may spread throughout the larynx, trachea and pharyngeal cavity. The ideal treatment would involve complete resection without cyst perforation. We use a completely different approach for the resection of epiglottic cysts, with successful results, which we term the advanced phono-ultra-microsurgical technique. One difference between this method and previous techniques of surgical epiglottic cyst resection is that the cyst is sealed off before resection in order to prevent rupture and spread of its contents. To enable this, we have developed a special device to facilitate suturing of the vocal fold epithelium, utilising a knot-pusher. This suturing technique allows complete removal of epiglottic cysts. Our technique allows optimal prevention of cyst rupture and spread of contents.

Objective: Nasolabial cysts are rare, nonodontogenic, soft-tissue, developmental cysts occurring inferior to the nasal alar region. They are thought to arise from remnants of the nasolacrimal ducts and they are frequently asymptomatic. We report a rare case of bilateral nasolabial cysts accompanied by bilateral chronic dacryocystitis.

Case report: A 48-year-old woman suffering from bilateral chronic dacryocystitis was referred to our department for endonasal dacryocystorhinostomy. She had undergone external dacryocystorhinostomy on the left side a few years earlier. Physical examination and computed tomography scan revealed nasolabial cysts bilaterally inferior to the nasal alar region. The cysts were removed via a sublabial approach and endoscopic dacryocystorhinostomy was performed on the right side. Ten months after surgery, the patient was asymptomatic.

Conclusion: There may be a correlation, due to embryological reasons, between the presence of nasolabial cysts and the presence of chronic dacryocystitis. Both can be corrected surgically, under the same anaesthesia, without visible scar formation.

Viable diatom and dinoflagellate resting stages were recovered from sediments in Koljö Fjord on the west coast of Sweden. To determine the maximum survival time of buried resting stages, samples from sediment depths down to 50 cm were incubated at temperatures of 3, 10 and 18 °C. Sediment cores were dated by 210Pb and the age of samples containing viable resting stages was determined using the constant rate of supply model. Dilution cultures of surface sediments allowed semiquantitative estimates of the potential seed bank. Dinoflagellate cysts from species such as Diplopsalis sp., Gymnodinium nolleri, Oblea rotunda and Protoceratium reticulatum were viable down to 15 cm depth, or 37 years old. Spores and resting cells of the diatoms Chaetoceros spp., Detonula confervacea and Skeletonema costatum were viable to over 40 cm depth, and may have been buried for many decades. The seed bank of living resting stages in surficial sediments was found to be rich (c. 57000 diatom resting stages g−1 wet weight and c. 200 dinoflagellate cysts g−1 wet weight), and the percentage of viable resting stages was higher for spore- and cyst-forming species. The oxygen-deficient sediments in Koljö Fjord appear to be a natural conservator of cell viability, a condition not easily simulated in laboratory studies. These results are ecologically important since spores and cysts are a repository of genetic material able to repopulate waters if resuspended and exposed to suitable light, temperature and nutrients.

We present a case of a 38-year-old man who was referred to us with a right-sided quinsy. However he was found to have a large lympho-epithelial cyst in his right parapharynx mimicking the signs of a quinsy to the unsuspecting eye. We describe this case to illustrate an unusual cause of a swelling of the lateral pharyngeal wall.

We have studied the activity of the polyether ionophorous antibiotic monensin against the cyst form (bradyzoite) of Toxoplasma gondii. The experiments were conducted in vitro using 2 methods; cysts produced either in mice or in cell culture were exposed to monensin in vitro, and the infectivity of the parasites was then assessed in vivo or in vitro. The data obtained from these 2 systems of evaluation showed that monensin inhibits the infectivity and the viability of the bradyzoites. Its activity was time and concentration dependent. The first effects were observed at very low drug concentrations (i.e. 0·0001 μg/ml). Immunofluorescence and electron microscopy analysis showed significant cytological alterations of the monensin-treated bradyzoites: they were swollen, had a large number of vacuoles in their cytoplasm and were found lysed at higher concentrations in ionophore.

Energy dispersive X-ray microanalysis (XRMA) in a scanning electron microscope (SEM) was used as a method to measure elemental silicon (Si) and phosphorus (P) in dinoflagellate cysts. Cysts were prepared by quick deep freezing and then freeze-drying, thereby avoiding the addition of preservatives. Cysts of Ceratium hirundinella collected from Lake Erken, Sweden and Esthwaite Water, UK, and Ceratium furcoides collected from Esthwaite Water, were analysed and compared. The hypothesis that cysts are able to assimilate P during dormancy was tested in the laboratory by incubating newly collected cysts of C. hirundinella in medium with and without phosphate. The analyses showed that there was no difference in P content between C. hirundinella and C. furcoides, suggesting that P content reflects differences in physiological status rather than species. C. hirundinella had a significantly higher Si content than C. furcoides, which agrees with earlier studies. Comparison of cysts of C. hirundinella from different years – 1995 (stored for 1 year), 1996 and 1997 – showed that the P content in cysts from 1995 was higher than that in cysts from the following 2 years, which indicates either that P was higher during encystment in 1995 or that cysts accumulated P during dormancy. The P uptake experiment showed a very slightly, but significantly, higher, P content in cysts incubated in P-rich medium.

Congenital laryngeal cysts are a rare cause of neonatal upper airway obstruction which may lead to serious morbidity and mortality if diagnosis and treatment are delayed. We reviewed our experience with nine patients over a six-year period. The annual incidence of this condition was 1.82 per 100,000 live births. The diagnosis can be confirmed safely by flexible laryngoscopy before definitive surgery is contemplated. Contrary to other studies, we found that endoscopic removal of cysts can achieve an effective cure without recurrence. Endoscopic deroofing is as effective as endoscopic excision but is technically simpler and thus is recommended as the treatment of choice.