Parasitic dinoflagellate Hematodinium in marine decapod crustaceans: a review on current knowledge and future perspectives.

Parasitic dinoflagellates of the genus Hematodinium are known to infect various marine crustaceans worldwide, especially crabs and several species of shrimp and lobster. Some of these species are new host species and components of commercial fishery products. These parasitic species are predominantly found in the hemolymph of the host and cause pathological changes and functional damage to organs and tissues, leading to death. In recent years, these parasites have infected important commercially valuable species, particularly in European waters, US waters, Australian waters, and recently in Shandong Peninsula in China. These Hematodinium pathogens were also reported to affect wild shrimp in Chinese waters and in the English North Sea. These rapid spreads affect crustacean aquaculture industries, where they are indeed a significant threat to the sustainability of the aquaculture of important crustaceans. The fishery products industries are also under pressure from the invasion of this pathogen, as the crab meat produced has a bitter taste, which may reduce its marketability. In response to these threats, this review was aimed at providing a broader understanding of the development of parasite distribution and ecological aspects of Hematodinium. In addition, the interaction of these pathogens with their hosts, the environmental drivers of Hematodinium disease, and future research perspectives were discussed.

Histopathological Alterations in Gills, Liver and Kidney of African Catfish (Clarias gariepinus, Burchell 1822) Exposed to Melaleuca cajuputi Extract.

This study evaluated the histopathological changes in the gill, liver and kidney of African catfish (Clarias gariepinus) intoxicated with a sub-lethal dose of Melaleuca cajuputi leaves extract (MCLE) for 96 h. The acute toxicity test has been determined previously with a value of 96-h LC50 = 127 mg/L, hence the selection of sub-lethal ranges from 60 mg/L to 160 mg/L of MCLE. Degenerative alterations were prominent in all tested organs, particularly after exposure to a high concentration of MCLE. Gill exhibited haemorrhage, epithelial lifting, lamellar disorganisation, and necrosis after exposure to a high MCLE concentration. Alterations in the liver include congestion, hydropic degeneration, and vacuolation, whereas lesions in the kidney were pyknosis, vacuolation, hydropic degeneration, and tubular necrosis. The obtained data showed that the organs experienced severe changes proportional to the increase in MCLE concentration. In addition, fish exposed to higher concentrations than the LC50 value experienced irreversible lesions. The present study suggests that the use of MCLE below the LC50 is recommended to avoid severe alterations to organs, particularly in African catfish. This study demonstrated that the use of MCLE above the LC50 promotes severe damage to the gills, liver and kidney of African catfish. However, further investigations are needed to define the causing-mechanisms underlying these effects.

Facilitating Exercise Engagement among Community Dwelling Stroke Survivors: Is a once Per Week Group Session Sufficient?

Although exercise is proven as an effective strategy to combat post-stroke complications and the risk of stroke recurrence, many stroke survivors fail to engage in this activity following rehabilitation. In this study, we assessed the feasibility and usefulness of a low-frequency group exercise to determine its suitability as an approach to facilitate exercise engagement among stroke survivors. Forty-one stroke survivors, mean (SD) age 59.34 (10.02) years, mean time post-stroke 17.13 (17.58) months, completed a 90 minute, once per week, group exercise supervised by therapists for 12 weeks. The exercise outcomes were measured using standardized clinical tests. We observed improvement in the group's physical performance; balance score by 3 units (Z = -3.88, p < 0.001), speed of repetitive sit to stand by 3.4 s (Z = -4.69, p < 0.001), and walking speed by 8.22 m/min (Z = -3.25, p < 0.001). Scores of seven out of 14 Berg's balance scale items increased significantly, indicating better balance ability among the survivors. In conclusion, a 12-week, once per week group exercise session seems feasible and sufficient to improve the physical performance of community dwelling stroke survivors. This exercise arrangement may be offered to stroke survivors to facilitate exercise practice following rehabilitation.