Related Experiment Videos
Group B streptococcus promotes oxygen radical-dependent thromboxane accumulation in young piglets
L A Shook1, T H Pauly, S L Marple
1University of Kentucky A.B. Chandler Medical Center, College of Medicine, Department of Pediatrics, Lexington.
Pediatric Research
|April 1, 1990
Summary
Group B Streptococcus (GBS) causes pulmonary hypertension in piglets by increasing thromboxane A2 via oxygen radicals. An oxygen radical scavenger prevented this effect, indicating a key mechanism in GBS-induced lung issues.
Area of Science:
- Neonatal physiology
- Pulmonary medicine
- Microbiology
Background:
- Group B Streptococcus (GBS) is a significant cause of neonatal infections.
- GBS infection can lead to severe complications, including pulmonary hypertension.
- The precise mechanisms underlying GBS-induced pulmonary hypertension are not fully understood.
Purpose of the Study:
- To investigate the role of oxygen-derived free radicals and thromboxane A2 in GBS-induced pulmonary hypertension in piglets.
- To test the hypothesis that GBS promotes oxygen radical-dependent thromboxane accumulation and pulmonary hypertension.
Main Methods:
- Infant piglets (4-12 days old) were used to assess pulmonary arterial pressure and arterial blood gases.
- GBS was administered to induce pulmonary hypertension.
- Dimethylthiourea (DMTU), an oxygen radical scavenger, was administered to a subset of piglets.
- Thromboxane B2 levels were measured using radioimmunoassay.
- Experiments involving arachidonic acid and a thromboxane mimetic (U44069) were conducted to elucidate DMTU's mechanism of action.
Main Results:
- GBS significantly increased pulmonary artery pressure and decreased arterial PO2 in control piglets.
- Thromboxane B2 levels were markedly elevated in GBS-infected piglets.
- Treatment with DMTU attenuated the GBS-induced increase in pulmonary artery pressure and decrease in PO2.
- DMTU treatment prevented the rise in thromboxane B2 levels in GBS-infected piglets.
- DMTU did not affect pulmonary hypertension induced by arachidonic acid or U44069, ruling out direct cyclooxygenase inhibition or thromboxane receptor antagonism.
Conclusions:
- Group B Streptococcus promotes thromboxane A2 accumulation and pulmonary hypertension through an oxygen radical-dependent pathway in infant piglets.
- Oxygen radicals play a critical role in the pathogenesis of GBS-induced pulmonary hypertension.
- Targeting oxygen radical production may be a potential therapeutic strategy for GBS-related lung injury.