A rat model of septic shock using live Escherichia coli and response to Noradrenaline

Objectives: Popular animal models of septic shock involve injections of endotoxin (bacterial lipopolysaccharide). Other methods that induce sepsis are often time-consuming and require long-term monitoring facilities. Further, individual models using different bacterial strains can deepen our understanding of sepsis pathophysiology. Hence, our objective was to develop an acute and functional Wistar rat model of septic shock using live strains of Escherichia coli and then administer Noradrenaline, a known sympathomimetic drug, to study if the response is along expected lines. Materials and Methods: After random allocation to one of three groups (Group 1 – E. coli alone, n=7; Group 2 – E. coli followed by Noradrenaline, n = 7 and Group 3 – control (n = 4), which received saline injections), Wistar rats were anesthetised and intra-arterial pressure was recorded from carotid artery catheter. Live E. coli suspended in normal saline (5 Mcfarland concentration; dose – 650 uL/100 g body weight) was injected through the tail vein to induce sepsis. When mean arterial pressure dropped to 50% of its value before E. coli injection, Noradrenaline was injected in Group 2. Results: The average time (t1, n = 14) for the septic shock to set in was about 1.94 ± 0.97 h. Six out of seven rats (Group 1) died within 60 min without intervention. The addition of Noradrenaline after hypotension in Group 2 prolonged the time to death significantly by about 170 min. Conclusion: The rat septic shock model using E. coli described in the study is an acute, stable, and functional model to study various aspects of septic shock. Administration of Noradrenaline prolonged the animal’s life in septic shock as expected. Future studies using other common sepsis agents encountered in clinics can be undertaken similarly

Parental Pesticidal Exposure and Risk of Clefts in the Craniofacial Region: A Case-Control Study in South India.

Objective: The multifactorial etiology of cleft can be due to environmental factors or genetic factors or combination of both. Many studies were conducted to detect the epidemiology of the clefts and the genetic factors causing clefts. There is no or very less studies conducted in India to identify the risk of pesticidal exposure in occurrence of nonsyndromic clefts. The present study is to investigate the risk of parental pesticidal exposure in causing clefts in the craniofacial region. Methods: The case-control study included 179 cases of cleft in the craniofacial region and 200 healthy controls matched for age and gender. The data were collected in the proforma from the study group in the departments of plastic surgery, Obstetrics and Gynaecology, and Paediatrics of Vydehi Institute of Medical Sciences and Research Centre. Result: Majority (55.3%) of the parents from the cleft group were exposed to pesticides but only 4.5% parents of the control group were exposed which is statistically significant (p=0.001). Compared to other cleft group, more parents of cleft lip palate exposed to pesticides was also significant (p=0.041).The cleft cases which were exposed to pesticides (86%) were from the rural area and the controls which were not exposed (79%) were from the urban area and is statistically significant (p<0.001). Conclusion: Parental pesticidal exposure is a risk factor for clefts in the craniofacial region. Among all the clefts, the risk is increased for the cleft lip palate.

Aminopyridine-induced contracture in frog ventricle is due to calcium released from intracellular stores.

The aim of the study is to demonstrate the presence of intracellular calcium store in frog ventricle based on contractures induced by 4-aminopyridine in calcium-free media. Frog-ventricular strips were subjected to field stimulation at 0.2 Hz and the force of contraction was recorded after stabilization. The preparation was then kept quiescent for some time in solutions with different sodium concentrations, containing 0 or 1 mmol/L calcium. Caffeine, 4-aminopyridine (4-AP), or tetraethylammonium chloride was then added. Frog skeletal muscle preparations were used as positive controls for the caffeine experiments. Frog ventricular preparations did not develop contractures (sustained contractions) in the presence of caffeine (25 mmol/L), while frog skeletal muscle preparations developed caffeine-induced contractures. However, 4-AP (16 mmol/L) was able to induce contractures in quiescent frog ventricular preparations, even when they were superfused with calcium-free solution. 4-AP contractures in frog ventricle were seen in the presence of nifedipine also. Amplitude of 4-AP evoked contractures in frog ventricle were much larger in low sodium (30 mmol/L) and sodium-free (sodium substituted by lithium) solutions than in normal sodium solution, suggesting that the route of extrusion of the cytosolic calcium (released from intracellular stores by 4-AP) is the sodium calcium exchanger, which gets reversed in low sodium solutions. Tetraethylammonium chloride (TEA) was not able to induce contractures in frog ventricle suggesting that the contracture evoked by 4-AP is not due to its potassium channel blocking effect. In quiescent frog skeletal muscle preparations, caffeine as well as 4-AP induced contractures in calcium-free solutions. We therefore conclude that there is a caffeine-insensitive, 4-AP sensitive intracellular calcium store in the frog ventricle.