Search PubMed⌕ Search

Biomedical subjects

H J Beijer

Publications and source records attributed to H J Beijer.

26 records · Page 2Linked to original sources
PubMed1978

Motor effects of graded doses of pentagastrin on the gut of the anesthetized dog.

Gastrointestinal motor activity of the anesthetized dog was assessed by strain gage force transducers on longitudinal and transverse muscle of the gastric body and antrum, duodenum, jejunum, ileum, and colon. Dose-dependent effects of pentagastrin (1-8192 ng/kg, i.v.) were only seen on the stomach: increases in gastric body tone, antral contractile force and contractile frequency of the gastric phasic activity. Body tone and antral force were more sensitive to pentagastrin than was contractile frequency. Supra-maximal doses and repetition of the dose-response protocol gave smaller increments for body tone and antral force, while the increase in contractile frequency remained unaffected. The different responses to pentagastrin of force and frequency indicate that pentagastrin acts on 2 different receptor-effector systems.

Animals↗
PubMed1976

Hemodynamic effects of norepinephrine and isoprenaline in various regions of the canine splanchnic area.

Responses to norepinephrine (NE) and isoprenaline (ISO) (1-1024 ng/kg i.v.) were assessed by electromagnetic flowmetry on 18 arteries of the splanchnic region in anesthetized dogs. Measurements were judged according to the 2 criteria: 1. direction of effect; 2.sensitivity of vascular areas to catecholamines, expressed as D50 (i.e. the calculated dose inducing 50% of the maximum effect). NE decreased flow in all arteries (40-80%), but caused additionally an increase in the celiac, splenic and splenic artery proper. Thus changes in the spleen are responsible for the increase with NE. Flow reduction in the pancreatic branch of the cranial mesenteric artery was small. All flow reductions induced by NE had a similar D50 (about 30 ng/kg), except that in the hepatic artery (100 ng/kg).

Animals↗
PubMed1976

Norepinephrine and isoprenaline induced changes of peripheral blood flow acceleration caused by changes of cardiac inotropy.

In anesthetized dogs the norepinephrine (NE) and isoprenaline (ISO) (1--1024 ng/kg i.v.)--induced increase of maximum peripheral flow acceleration (celiac artery, cranial mesenteric artery, renal artery; and femoral artery) and the changes of the maximum first derivative of arterial pressure were compared with the increases of maximum ascending aortic flow acceleration and maximum first derivative of left ventricle pressure (LV dP/dt max). The maximum effect of each dose on maximum acceleration of flows (dF/dt max) and maximum first derivative of pressures (dP/dt max) occurred simultaneously for all v56--512 ng/kg) and for ISO (D50:128--256) ng/kg). We demonstrated that other varure) played only a minor role in the increases of LV dP/dt max in our studies. In contrast with the uniform response of dF/dt max and dP/dt max, the reaction of peripheral vascular resistance varied. In particular in the gastrointestinal tract the resistance could either be increased (NE, D50:115 ng/kg) or decreases (ISO, D50:15 ng/kg). Gastrointestinal resistance was a more sensitive variable for catecholamine stimulation than dF/dt max and dP/dt max. The data show that under the present experimental conditions induced by NE and ISO is due to increase of cardiac inotropy.

Animals↗
PubMed1976

Lysine-vasopressin: hemodynamic effects in the anesthetized dog.

Vasopressin (ADH) is known to reduce secretin-stimulated pancreatic exocrine secretion. The present study attempts to relate this inhibitory effect to the vasoconstrictive potency of ADH. Regional blood flow in most of the vascular areas. The greatest reduction in blood flow was seen in the gastrointestinal area especially in the left gastric artery, cranial and caudal pancreaticoduodenal arteries, as well as the cranial and caudal mesenteric arteries. Renal blood flow was not altered by those concentrations of ADH that reduced gastrointestinal blood flow. ADH reduced pancreaticoduodenal blood flow in concentrations comparable to those concentrations that reduced pancreatic secretory flow. The reduction of gastrointestinal blood flow was due to increased impedance and not to diminished cardiac inotropy.

Animals↗
PubMedDate not supplied

Furosemide vasodilates the canine gastrointestinal tract.

The ability of furosemide to induce vasodilation in the canine gastrointestinal system was studied by quantitative flowmetry. Blood flow and conductance increased maximally by 60 per cent in the stomach and duodenum and by 80 per cent in the small and large intestine. Vasodilation was evident at 2.4 mg/kg furosemide and higher. The onset of vasodilation occurred at 24 to 30 seconds and was maximal at 36 seconds in the stomach, at 66 seconds in the duodenum, at 78 to 84 seconds in the small intestine, and at 90 seconds in the large intestine. Hepatic arterial, splenic, and renal blood flows were unchanged. Simultaneous arteriovenous sampling from the small intestine indicated that the increased blood flow was not associated with increased O2 consumption. However, CO2 addition to the venous effluent decreased by 70 per cent. These data indicate that furosemide has a vasodilatory action on the gastrointestinal tract due either to a delayed effect on the vascular smooth muscle cell or on anaerobic bowel wall metabolism. The CO2 data are compatible with, but do not prove, stimulation of secretion of HCO3- by the intestinal mucosa.

Animals↗
PubMedDate not supplied

No relation between general laxity and atlantoaxial instability in children with Down syndrome.

Atlantoaxial instability in children with Down syndrome (DS) may be caused by laxity of the transverse ligament. We tested the hypothesis that general laxity might predict atlantoaxial instability. General laxity and the atlantoaxial distance were assessed in 172 children with DS (aged 6-17 years; 45% girls, 55% boys). No significant correlation was noted between these two measures with either univariate or multivariate methods of statistical analysis.

Adolescent↗
PubMedDate not supplied

Injuries in high-risk persons and high-risk sports. A longitudinal study of 1818 school children.

In this Dutch population-based study we attempted to determine the incidence and severity of sports injuries occurring during different kind of sports in a longitudinal way. The study included 1818 school children aged 8 to 17 years. Over a period of 7 months, 399 sports injuries were reported in 324 youngsters. The most common types of injuries were contusions (43%) and sprains (21%). Medical attention was needed in 25% of all cases. Young basketball, handball and korfball players had a nearly 100% chance of suffering one sports injury per year. Volleyball especially had a high incidence rate in practice (6.7 in 1000 hours). Although physical education classes had a low incidence rate, there were significantly more fractures on the upper limb. Etiologically, sports-related factors were much more important than personal-bound factors. The injured youths spent more time in practice than the noninjured ones, both in organized and nonorganized sports (P less than 0.001). High-risk sports were characterized by contact, a high jump rate, and indoor activities. These three factors explained 78% of the total variance. The contact versus noncontact factor accounted for 48% of the medically treated injuries. An additional goal of this study was to explore the seasonal influence as an extrinsic environmental factor. We found that the duration of injury was increased in the spring (P less than 0.05). Specific preventive measures were formulated in order to reduce the number of new and recurring injuries and a proposal was made to implement injury prevention in school curriculums.

Adolescent↗