Phase partitioning during fragmentation revealed by QEMSCAN Particle Mineralogical Analysis of volcanic ash.

Volcanic ash particle properties depend upon their genetic fragmentation processes. Here, we introduce QEMSCAN Particle Mineralogical Analysis (PMA) to quantify the phase distribution in ash samples collected during activity at Santiaguito, Guatemala and assess the fragmentation mechanisms. Volcanic ash from a vulcanian explosion and from a pyroclastic density current resulting from a dome collapse were selected. The ash particles resulting from both fragmentation modes are dense and blocky, typical of open-vent dome volcanoes and have a componentry consistent with their andesitic composition. We use image analysis to compare the fraction of each phase at particle boundaries compared to the total particle fraction. Our results show that the explosion-derived ash has an even distribution of plagioclase and glass, but boundaries enriched in pyroxene and amphibole. In contrast, the ash generated during dome collapse has an increased fraction of glass and decreased fraction of plagioclase at particle boundaries, suggesting that fractures preferentially propagate through glass during abrasion and milling in pyroclastic flows. This study presents QEMSCAN PMA as a new resource to identify generation mechanisms of volcanic ash, which is pertinent to volcanology, aviation, respiratory health and environmental hazards, and highlights the need for further experimental constraints on the fragmentation mechanism fingerprint.

Second intermediate host land snails and definitive host animals of Brachylaima cribbi in southern Australia.

This study of infection of southern Australian land snails with Brachylaima cribbi metacercariae has shown that all commonly encountered native and introduced snails are susceptible second intermediate hosts. The range of infected snails is extensive with metacercariae-infected snails being present in all districts across southern Australia. C. virgata has the highest average natural metacercarial infection intensity of 6.1 metacercariae per infected snail. The susceptibility of birds, mammals and reptiles to B. cribbi infection was studied in South Australia by capturing, dissecting and examining the intestinal tract contents of animals which commonly eat land snails as a food source. Indigenous Australian little ravens (Corvus mellori), which are a common scavenger bird, and two other passeriform birds, the black bird (Turdus merula) and the starling (Sturnus vulgaris), which are both introduced European birds, were found to have the highest infection rates of all animals examined. Other birds found infected with B. cribbi were an emu (Dromaius novaehollandiae), chickens (Gallus gallus) and a pigeon (Columba livia). Natural infections were also detected in field mice (Mus domesticus) and shingleback lizards (Tiliqua rugosa) although the intensity of infection was lower than that observed in birds. Susceptibility studies of laboratory mice, rats and ducks showed that mice developed patent infections which persisted for several weeks, rats developed a short-lived infection of three weeks' duration and ducks did not support infection. This study has shown for the first time that a brachylaimid can infect a wide host range of birds, mammals and reptiles in nature.

First report of the isolation of an adult worm of the genus Brachylaima (Digenea: Brachylaimidae), from the gastrointestinal tract of a human.

A 78-year-old woman presented with an 18-month history of intermittent diarrhoea. Examination of her stools revealed brachylaimid eggs, which were present in three separate specimens over a week. After treatment with praziquantel a degenerate adult Brachylaima species was recovered from her faeces. She lived in a rural area of South Australia and ate vegetables grown in her own garden which had been infested with helicid snails. In south Australia these introduced European helicid snails are commonly infected with brachylaimid intermediate larval stages and are considered to be the source of the human infection.

Coccidian/cyanobacterium-like body associated diarrhea in an Australian traveller returning from overseas.

Coccidian/cyanobacterium-like body (CLB) associated diarrhea occurred in a 42 yr old Australian woman returning from Bali, Indonesia. The patient had a diarrheal illness of 10 days duration with symptoms of explosive diarrhea, nausea, anorexia and fever. Fecal examination revealed CLBs which were detected in modified Ziehl-Neelsen stained fecal smears. No other bacterial or parasite pathogens were found. CLBs were variably acid fast, showed an intense blue auto-fluorescence under UV microscopy and appeared as non-refractile hyaline spheres in direct wet mounts, being 8-9 microns in diameter. The taxonomic status of CLBs has been unclear but recent evidence supports that they are a coccidian parasite of the genus Cyclospora, rather than cyanobacterium. There is no specific therapy for CLB enteritis and spontaneous recovery occurs after what may be a prolonged diarrheal illness. CLBs may be a previously unrecognized enteric pathogen although their role in the pathology of diarrheal illness is still undetermined. There is consistency in the clinical and laboratory findings amongst the reported cases and CLBs should be considered in persons with unexplained gastroenteritis, especially travellers returning from tropical regions.

Field prevalence and laboratory susceptibility of southern Australian land snails to Brachylaima cribbi sporocyst infection.

Brachylaima cribbi is a terrestrial trematode of birds and mammals with helicid and hygromiid land snails reported as first and second intermediate hosts. However, reports describing the first intermediate host range of B. cribbi have been limited to those snail species present in a small number of geographical locations in South Australia. The natural first intermediate host range, distribution and prevalence of B. cribbi in land snails in southern Australia were determined. A total of 6,432 introduced and native land snails were collected from eight geographical districts across 3,000 km of southern Australia and examined microscopically for B. cribbi sporocysts. Four introduced European snails, Theba pisana, Cernuella virgata, Cochlicella acuta and Cochlicella barbara were natural first intermediate hosts. Sporocyst-infected snails were detected in all districts from Victoria to the west coast of South Australia, a distance of over 1,300 km. Natural sporocyst infection was not observed in introduced European snails Microxeromagna armillata and Helix aspersa or in native Australian land snails Succinea australis and Strangesta gawleri. Egg feeding experiments in the laboratory with B. cribbi confirmed the susceptibility of those species of snails found to be natural first intermediate hosts. Of those species not found to be infected in nature, only M. armillata could be infected in the laboratory. Although this study has shown that five different species of European land snails are suitable first intermediate hosts for B. cribbi there are as yet no reports of B. cribbi from these snails in Europe or from other countries where they have been introduced. Further investigations are needed in Europe to clarify the origins of this parasite.

Electropalatographic and cephalometric assessment of myofunctional therapy in open-bite subjects.

Myofunctional therapy (MFT) is often prescribed to correct tongue-thrust swallowing, with the expectation that anterior open bite (AOB) will reduce spontaneously if a more posterior tongue posture is learned. However, MFT has not been subjected to systematic evaluation. Electropalatography (EPG), which is used in speech pathology to measure dynamic tongue function for diagnostic, therapeutic and research purposes, is a suitable technique for the evaluation of MFT. This prospective clinical study assessed the effect of tongue re-education therapy on tongue function and dento-facial form in AOB patients. Electropalatography recordings of speech and swallowing, and lateral head cephalometric radiographs were obtained from eight 10-year-old boys with tongue-thrust swallowing behavior and AOB before and after a course of tongue re-education therapy. Although differences in cephalometric measurements before and after therapy were small, there was some evidence of a trend for upper and lower incisor eruption, with concomitant reduction of the AOB. Analysis of the EPG speech data was inconclusive, but the swallowing data showed trends for more consistent and more anterior patterns of EPG contact after therapy. Comparison of pre- and post-therapy EPG data with data from a parallel study using a group of age-matched controls indicated that some "normalisation" of swallowing behaviour had occurred. The results of this research imply that the therapy was partially successful in improving tongue function during swallowing and in reducing AOB. Further research on a larger sample over a longer observation period is required for more accurate assessment of soft and hard tissue changes.

Survival of bacteria on the ocular surface following double application of povidone-iodine before cataract surgery.

AIMS: This study assessed the effectiveness of one vs two applications of povidone-iodine in decontaminating the eye before cataract surgery. METHODS: This was a prospective, interventional study of 52 patients having elective unilateral phacoemulsification cataract surgery in a tertiary care centre. Each patient had two applications of povidone-iodine before phacoemulsification cataract surgery, separated by 10 min. Conjunctival swabs were taken before and after each application and cultured in 5% CO(2) and anaerobically. Statistical analysis was performed using McNemar's test for correlated proportions. RESULTS: In all, 15 of 52 (29%) patients had positive cultures before the first application and 21 of 52 (40%) patients had positive cultures after it. This was not statistically significant (P=0.239). A total of 25 of 52 (48%) patients were culture positive before the second application. This was not statistically significantly different from 10 min earlier (P=0.423). Six of 52 (12%) patients were positive after the second application (P<0.001). CONCLUSIONS: We conclude that the initial application of povidone-iodine was not effective in decontaminating the eye. Recontamination did not take place between applications. The difference in the proportion of patients with positive results before and after the second application of povidone-iodine was statistically significant. We infer from this that double application of povidone-iodine before cataract surgery is advisable.

Description of the life-cycle stages of Brachylaima cribbi n. sp. (Digenea: Brachylaimidae) derived from eggs recovered from human faeces in Australia.

The life-cycle of Brachylaima cribbi n. sp. was established in the laboratory. Asymmetrical brachylaimid eggs, measuring 26-32 microm (29.1 microm) long and 16 -17.5 microm (16.6 microm) wide, were recovered from human faeces and fed to the helicid land snail Theba pisana as the first intermediate host. Sporocysts and cercariae were recovered from the T. pisana eight weeks after infection. The cercariae were used to infect the helicid land snails Cernuella virgata and Helix aspersa as second intermediate hosts. Metacercariae were recovered from the kidneys of these snails and used to infect mice. Adults of Brachylaima cribbi n. sp. were recovered from the small intestine of the mice. The differential features of B. cribbi n. sp. are the specificity for helicid snails as first and second intermediate hosts; characteristic ventral sucker and body cercarial chaetotaxy; and a long slender adult worm with equal size suckers in the first quarter of the worm, the ventral sucker occupying 41% of the body width, the uterus extending anterior to the ventral sucker and the vitelline follicles falling short of the posterior margin of the ventral sucker. No other known Brachylaima species exhibits all of these features. B. cribbi n. sp. is the first brachylaimid known to have infected humans and is probably of European origin, as the intermediate host snails were all introduced into Australia from Europe.

Electropalatographic and cephalometric assessment of tongue function in open bite and non-open bite subjects.

Anterior open bite (AOB) and tongue thrust swallowing are frequently associated, but the relationship between the two remains unclear. Electropalatography (EPG), which is used in speech pathology to measure dynamic tongue function for diagnostic, therapeutic, and research purposes, is a suitable technique for the investigation of this relationship. The present clinical study examined the dentofacial pattern and tongue function in AOB and non-open bite children. EPG recordings of speech and swallowing, and lateral head radiographs were obtained from eight 10-year-old boys with tongue thrust swallowing behaviour and AOB, and from eight age-matched non-open bite controls. Analysis of data from the two groups indicated that although differences were small, the open bite children displayed trends for longer face morphology and greater upper incisor proclination, less consistent production of closures during speech, a more posterior pattern of EPG contact, and relatively sparse EPG contact during swallowing. The discovery of differing patterns of contact for the /d[symbol: see text]/ and /t[symbol: see text]/ phonemes indicates that these should be included when speech is used to test for the presence of fronted tongue behaviour.

Brachylaima cribbi (Digenea: Brachylaimidae): scanning electron microscopical observations of the life-cycle stages.

Brachylaima cribbi is a recently described species of terrestrial trematode that infects mammals and birds with helicid land snails as its first and second intermediate hosts. The adult worm is 2.5-6.0 mm long by 0.5-0.8 mm wide being a long slender cylindrical worm with oral and ventral suckers in the anterior quarter and genital pore in the posterior quarter. Scanning electron microscopy shows that there is a dense covering of tegumental spines at the anterior end which diminishes towards the posterior extremities of the worm. Development of spines was observed in juvenile and mature adult worms. In young worms 1-3 weeks post infection (wpi) spines appear as buds with a serrated edge each having 1-4 spikes per spine. As the worm ages the spines broaden and by 5 wpi the number of spikes per spine increases to an average of 8.1. The serial development of oral sucker papillae in the cercaria, metacercaria and adult worm was observed with the finding of an elongated papilla with a bifurcated tip on the cercaria becoming a shorter and thicker elongated papilla with a large central stoma on the metacercaria. In the adult worm, this papilla becomes dome-shaped with a small central stoma. For some of these papillae a cilium could be seen extended from the central stoma. Other life-cycle stages illustrated were the hatched egg with an extruded egg membrane minus an operculum and a portion of the branched sporocyst dissected from the digestive gland of the land snail Theba pisana showing a terminal birth pore. Scanning electron microscopy morphological features of the adult worm observed for the first time in a Brachylaima were the unarmed cirrus extended from the genital pore with released sperm present and the Laurer's canal opening visible in tegumental folds on the dorsal surface approximately 300 microm posterior to the genital pore.

Locally acquired Brachylaima sp. (Digenea: Brachylaimidae) intestinal fluke infection in two South Australian infants.

Eggs of a small intestinal trematode were found in the faeces of two 21-month-old children from the same rural district of South Australia who presented 18 months apart with mild abdominal pain and diarrhoea. Treatment with praziquantel resulted in egg clearance and resolution of gastrointestinal symptoms. A brachylaimid intestinal trematode involving the common house mouse, poultry and introduced European helicid snails is well established in South Australia. Both infants had been seen eating raw snails, and snails from their environment were found to be infected with metacercariae of a brachylaimid trematode.