Mosquito midgut stem cell cellular defense response limits Plasmodium parasite infection

A novel cellular response of midgut progenitors (stem cells and enteroblasts) to Plasmodium berghei infection was investigated in Anopheles stephensi. The presence of developing oocysts triggers proliferation of midgut progenitors that is modulated by the Jak/STAT pathway and is proportional to the number of oocysts on individual midguts. The percentage of parasites in direct contact with enteroblasts increases over time, as progenitors proliferate. Silencing components of key signaling pathways through RNA interference (RNAi) that enhance proliferation of progenitor cells significantly decreased oocyst numbers, while limiting proliferation of progenitors increased oocyst survival. Live imaging revealed that enteroblasts interact directly with oocysts and eliminate them. Midgut progenitors sense the presence of Plasmodium oocysts and mount a cellular defense response that involves extensive proliferation and tissue remodeling, followed by oocysts lysis and phagocytosis of parasite remnants by enteroblasts.

Mosquito midgut stem cell cellular defense response limits Plasmodium parasite infection

A novel cellular response of midgut progenitors (stem cells and enteroblasts) to Plasmodium berghei infection was investigated in Anopheles stephensi. The presence of developing oocysts triggers proliferation of midgut progenitors that is modulated by the Jak/STAT pathway, and proportional to the number of oocysts on individual midguts. The percentage of parasites in direct contact with enteroblasts increases over time, as progenitors proliferate. Enhancing proliferation of progenitors significantly decreases oocyst numbers, while limiting proliferation increases oocyst survival. Live imaging revealed that enteroblasts interact directly with oocysts and eliminate them. Midgut progenitors sense the presence of Plasmodium oocysts and mount a cellular defense response that involves extensive proliferation and tissue remodeling, followed by oocysts lysis and phagocytosis of parasite remnants by enteroblasts.

Adaptation of the vacuum-assisted closure system for laparostomy

Background

Laparostomy is a useful treatment option in selective cases of severe peritonitis. However, owing to the size, massive secretion and intestinal fistulas, the granulation of this wound is a long and troublesome process.

Methods

From 1994 to 1999 the vacuum-assisted closure (VAC) system has been used as the wound dressing for laparostomies.

Results

The VAC system has the following advantages compared with conventional dressings: (1) efficient drainage of the wound; (2) rapid induction of a macroscopically healthy granulation; (3) little irritation of the surrounding skin; (4) possibility of kinetic therapy in patients with acute respiratory distress syndrome; and (5) less psychological distress of the patient, owing to the closed dressing of an otherwise massively secreting wound. The major side-effect observed was erosion-induced bleeding. Bleeding always ceased after a pause of the VAC system for 24 h. The major complication of the system was clogging by fibrinous secretions and thickened intestinal fluids. These occlusions could be prevented by adding a rinsing line with 0·9 per cent sodium chloride. Interestingly, there was no increase in bacterial colonization of the abdomen.

Conclusion

Owing to multiple variables in patients with laparostomy an objective assessment of the advantages of VAC treatment compared with conventional dressings is almost impossible. However, it appears that the VAC system is a rational approach for the treatment of these large wound surfaces.