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Biomedical subjects

M I Qamar

Publications and source records attributed to M I Qamar.

9 recordsLinked to original sources
PubMed1991

Fasting and post-prandial splanchnic blood flow is reduced by a somatostatin analogue (octreotide) in man.

1. The effects of the subcutaneous administration of a long-acting somatostatin analogue (octreotide) or of placebo on the splanchnic blood flow response to a mixed solid meal has been examined in eight normal subjects by using a transcutaneous Doppler ultrasound technique. Each subject was studied on two occasions more than 1 week apart. 2. On the control day, feeding had a pronounced effect on both superior mesenteric artery and portal venous blood flows, causing a peak rise of 82% in superior mesenteric artery blood flow at 15 min and of 75% in portal venous blood flow at 30 min post-prandially (P less than 0.001). Blood flows remained elevated 2 h after the meal. Pulse and blood pressure showed no significant changes from baseline. 3. Octreotide reduced fasting superior mesenteric artery blood flow by 59% (P less than 0.05) and portal venous blood flow by 49% (P less than 0.01) and blunted the normal post-prandial rise. Pulse and blood pressure did not change in response to either the injection or the ingestion of the meal. 4. Octreotide suppressed the release of insulin, glucagon and pancreatic polypeptide in response to feeding and resulted in post-prandial hyperglycaemia. 5. The mechanism of action of octreotide on splanchnic blood flow is uncertain. It may be mediated via a direct vascular effect or it may act via suppression of vasoactive intestinal hormones.

Adult↗
PubMed1988

Effects of ingestion of carbohydrate, fat, protein, and water on the mesenteric blood flow in man.

Transcutaneous Doppler ultrasound was used to measure superior mesenteric artery blood flow in 12 healthy volunteers in the fasting state and serially for 1 h after the ingestion of isocaloric and isovolaemic carbohydrate, fat, and protein liquid meals. The superior mesenteric artery blood flow increased significantly within 5 min of the end of each meal. The maximal responses were not significantly different but were reached at different times: carbohydrate, 64% at 15 min; fat, 60% at 30 min; and protein, 57% at 45 min. The response to the fat meal was significantly slower than the response to the carbohydrate, and the response to protein was slowest of all. In a further group of 20 fasted normal subjects no significant change in superior mesenteric artery blood flow occurred after drinking 400 ml of distilled water at room temperature. In seven of these subjects, drinking 400 ml of distilled water at 4 degrees C also did not affect mesenteric blood flow. These results indicate that the chemical nature of the meal and not the volume per se is a significant factor determining postprandial mesenteric hyperaemia.

Adult↗
PubMed1987

Effects of exercise on mesenteric blood flow in man.

Transcutaneous Doppler ultrasound was used to assess the effects of exercise on both fasting and postprandial superior mesenteric artery blood flow. After treadmill exercise (speed 5 km/h, gradient 20%, duration 15 min) in 16 subjects, superior mesenteric artery blood flow decreased by 43% immediately after the end of the exercise and by 29% at five minutes and 24% at 10 minutes postexercise. The superior mesenteric artery blood flow response to a combination of a treadmill exercise and a liquid meal in 15 volunteers was significantly smaller at five minutes from the end of the stimuli, than the response to the meal alone (15 controls) (635 +/- 51 ml/min v 846 +/- 72 ml/min) (p less than 0.025), but not different at any other time. Thus exercise reduces mesenteric blood flow in both the fasting and postprandial state in normal subjects.

Adult↗
PubMed1986

Pulsatility index of superior mesenteric artery blood velocity waveforms.

A transcutaneous Doppler ultrasound technique was used to investigate superior mesenteric artery blood velocity waveforms in normal subjects. The shape of the waveforms was quantified by means of the pulsatility index (PI). The mean value +/- standard error of the mean of the PI measured in 82 normal subjects in the resting and fasting state was 3.57 +/- 0.11. There was no difference in the PI between sexes nor correlation between the PI and age. Following the ingestion of a meal in a group of 15 subjects the PI decreased by 46% (p less than 0.001). A significant fall persisted over the next two hours.

Adult↗
PubMed1986

Transcutaneous Doppler ultrasound measurement of superior mesenteric artery blood flow in man.

A duplex scanner which consists of a real time two dimensional scanner and a pulsed Doppler flowmeter was used to measure superior mesenteric blood flow in 70 healthy subjects. By processing the Doppler shift signals, the instantaneous average Doppler shift frequency and then the instantaneous average velocity of the flow rate were calculated. Both diameter of the vessel and angle between vessel and beam were measured from real time imaging. The mean (+/- standard error of the mean) of the superior mesenteric blood flow was 517 +/- 19 ml/min. There was neither significant difference in flow between sexes, nor correlation between flow and age (r = 0.042). The mean of coefficients of variability were 6.8% over the short term, and 8.2% in long term studies.

Adult↗
PubMed1986

Increased superior mesenteric artery blood flow after glucose but not lactulose ingestion.

A transcutaneous Doppler ultrasound method was used to measure the superior mesenteric artery blood flow in nine healthy volunteers in the fasting state and serially for 1 h after the ingestion of 400 ml of an isotonic glucose solution. These measurements were repeated on a second occasion following the ingestion of 400 ml of an isotonic lactulose solution. Superior mesenteric artery blood flow increased by 53 per cent (p less than 0.05) 5 min after the end of ingestion of the glucose solution. The increase persisted at 10 min and declined to 47 per cent at 15 min and to 23 per cent at 30 min. No significant change in blood flow was found following the ingestion of the lactulose solution. Significant differences between the two responses were found at 5, 10 and 15 min (p less than 0.05). The increase in blood flow after a glucose solution and not after lactulose suggests therefore that the process of absorption is an important factor governing postprandial superior mesenteric artery blood flow.

Adult↗
PubMed1985

Increased flow in the superior mesenteric artery in dumping syndrome.

Transcutaneous Doppler ultrasound was used to measure resting and postprandial blood flow in the superior mesenteric artery (SMABF) in nine patients with dumping syndrome and in ten normal volunteers of matching age and sex. All nine patients experienced signs and symptoms of dumping during the investigation, but none of the controls did so. At rest, SMABF in the dumping patients (567 +/- 47 ml/min) (mean +/- s.e.m.) did not significantly differ from that of the normal volunteers (493 +/- 72 ml/min). Five minutes from the end of a balanced liquid meal, flow had approximately doubled in each group (1232 +/- 140 and 941 +/- 128 ml/min). Compared with controls, increased SMABF was observed in patients with dumping syndrome at 10 min (76 per cent), 15 min (66 per cent), 30 min (55 per cent) and 45 min (42 per cent) (P = 0.05-0.01). Splanchnic pooling and abnormal redistribution of blood probably contribute to the pathogenesis of the early dumping syndrome.

Adult↗
PubMed1985

Transcutaneous Doppler ultrasound measurement of coeliac axis blood flow in man.

Transcutaneous Doppler ultrasound was used to measure coeliac axis blood flow in 42 normal subjects in the fasting state and in 10 subjects following a liquid meal. A Duplex scanner was used and coeliac axis blood flow was estimated by calculating the instantaneous average velocity of blood flow over the cardiac cycle. Both the diameter of the vessel and the angle between the vessel and the beam were measured from real time imaging. The mean (+/- s.e.m.) of coeliac axis blood flow was 703 +/- 24 ml/min. There was no difference in the results between the sexes nor any correlation between flow and age. The mean coefficient of variability was 7.8 per cent in a 1 day test and 9.2 per cent in a 2 day test. Coeliac axis blood flow increased by 38 per cent immediately after the end of ingestion of the meal and declined to 29 per cent 5 min and 24 per cent 10 min later.

Adult↗