Baroreceptor reflex response in paraplegia during head-up tilt position.

Paraplegia is one of the most common spinal cord lesions seen in spinal cord injury patients below 4th thoracic vertebra and is associated with autonomic loss below the level of lesion with intact vagal cardiac nerves. It occurs due to lesion of spinal cord at an appropriate level. i.e., sparing superior extremities and involving inferior extremities. The common causes of paraplegia are accidents such as gunshot injuries, spinal cord injuries, autonomic injuries and dislocation of spine. The degree of cardiovascular control impairment is related to the level and severity of the lesion. This study was to investigate the autonomic control of cardio vascular functions in paraplegia patients in response to head up tilt following spinal cord injury. The parameter studies were in head up tilt response on resting heart rate and blood pressure changes in paraplegic subjects. The results show an abnormal response to head – up tilt in paraplegia patients with decrease in diastolic blood pressure but the heart rate showed normal response. Thus, in patients of paraplegia, sympathetic reflexes below the level of the lesion induce vasoconstriction. These results indicate that increased sympathetic activity in controls during Head up tilt and decreased sympathetic activity in paraplegia. This suggests that patients with paraplegia maintain cardiovascular homeostasis during Head up tilt without increase in sympathetic activity.

Central obesity and lipid profile in North Indian Males.

Obesity is a known risk factor for metabolic syndrome in adults. Metabolic syndrome includes a group of cardiovascular disease risk factors namely impaired glucose tolerance, dyslipidaemia and hypertension. Central fat distribution, particularly intra-abdominal fat, is a greater risk factor than peripheral fat distribution. Anthropometric indices used to measure fat distribution have been shown to be associated with altered lipid profile. The objective of the present study was to compare the serum lipid profile levels in obese and non-obese males according to their Waist Circumference (WC) and Waist-Hip Ratio (WHR). A total of 60 males (aged 18-56 years, Mean age 31.00+11.81 years) were included in the study. WC and Hip Circumference (HC) were measured and WHR was calculated. An overnight fasting venous blood sample was drawn for lipid profile. Central obesity was defined as WC > 90 cm or WHR > 0.9. When compared according to WC and WHR, High Density Lipoprotein Cholesterol (HDL-C) was significantly decreased in obese compared to non-obese, while no significant change in Total Cholesterol (TC), Triglycerides (TG) and Low Density Lipoprotein Cholesterol (LDL-C) levels was observed. Both WC and WHR were positively correlated with TG, TC and LDL-C and negatively with HDL-C. The correlations with HDL-C were statistically significant. Thus, it can be concluded from our study that obesity measured either as WC or WHR is associated with altered lipid profile in the form of low HDL-C. In obese individuals the accompanying hyperinsulinaemia due to insulin resistance may be responsible for changes in lipid and lipoprotein concentration.

Comparision of potency of different types Neuro-Muscular Junction (NMJ) blockers on isolated rectus abdominis muscle of rana tigrina.

The most important use of neuromuscular blockers is as adjuvant to general anaesthesia where adequate muscle relaxation can be achieved at lighter plane. They also reduce reflex muscle contraction in the region undergoing surgery and assist maintenance of controlled ventilation during anaesthesia. They are particularly helpful in abdominal and thoracic surgery, intubations and endoscopies, orthopedic manipulation, etc. Thus, the risk of respiratory and cardiovascular depression is minimized, and post anesthetic recovery is shortened. The potency ratio of two commonly used neuromuscular agents depolarizing succinylcholine and non depolarizing pancuronium. Double pith a frog and fasten it to a frog board with ventral side up. The sternum was cut through just above the xiphisternum at its base and a pair of muscle attached to it were dissected out and transferred to a dish containing frog Ringer solution at room temperature. All the drug containing solutions were freshly prepared before the experiments Succinyl choline, Pancuronium (1,10,100mg/ml and 1mg/dl) respectively Acetyl choline (10,100mg/ml and 1mg/dl). Acetylcholine solution in various strength were prepared starting from 0.1% to 0.0001%.NMJ blocker Pancuronium was added to the biophase in addition to selected dose (128mg or 256mg) and the contraction of muscle till the 70-80% of inhibition is produced and the difference from sub maximal contractions. The median ED50 was interpolated from the figure taking 50%of inhibition from Height of contraction in mm. The ‘t’ test was performed to compare the ED50 value were interpolated from the regression line to find out the ED50 of the drug. The median doses (ED50) of both of them were calculated graphically and compared. The mean ED50 value of succinylcholine was found to be 1.59 ± 0.08μg (95% confidential limit was from 1.53 to 1.66μg). The ED50 of pancuronium was found to be 0.52 ± 0.10μg with 95% confidence limit being from 0.44 to 0.60μg. The ED50 value of the two drugs was very significantly different (P < 0.001). The potency ratio of pancuronium to succinylcholine was 0.32.

Comparison of common clinically used local anesthetics on animal models.

The animal models used in this study were Plexus anesthesia in frogs, Infiltration anesthesia in guinea pigs, Surface anesthesia in rabbits. The drugs were diluted with normal saline. Lignocaine2%: xylocaine hydrochloride injection IP, Bupivacaine 0.5%: Bupivacaine hydrochloride injections IP were prepared. Plexus anesthesia: Frog was pithed and spinal cord was destroyed up to the 3 vertebra. The abdominal pouch was filled with local anesthetic solution. Reflex activity was tested by immersing both feet of the frog every two minutes for not longer than 10 seconds into N/10 Hydrochloric acid. The time was noted. Surface anesthesia: Albino rabbits of either sex weighing 2.5 – 3.0kg ware selected. The conjunctival sac of one eye was held open, thus formed a pouch. 0.5ml of solution of the anesthetic was applied into the conjunctival sac for 30 sec. Infiltration anesthesia: Preparation of guinea pig: Guinea pigs (either sex) weighing 250-300grams were used. Lignocaine produced rapid onset of plexus anesthesia in Frogs in comparison to the bupivacaine at concentration of 0.1% & 0.2% which is statistically significant. Bupivacaine is more potent than the lignocaine as a surface anesthetic agent in the Rabbit, where as lignocaine could produce surface anesthesia at concentration of 0.5% or 0.1% or both. Both bupivacaine and lignocaine produced infiltration anesthesia on intradermal injection in guinea pigs but the duration of infiltration anesthesia produced by bupivacaine is more prolonged which is statistically significant in comparison to the lignocaine at all the three concentrations tested i.e. 0.05%, 0.1% & 0.2%.