PubMed Health⌕ Search

Biomedical subjects

P Jowell

Publications and source records attributed to P Jowell.

6 recordsLinked to original sources
PubMed1991

Use of computer graphics simulation for teaching of flexible sigmoidoscopy.

The concept of simulation training in endoscopy is now well-established. The systems currently under development employ either computer graphics simulation or interactive video technology; each has its strengths and weaknesses. A flexible sigmoidoscopy training device has been designed which uses graphic routines--such as object oriented programming and double buffering--in entirely new ways. These programming techniques compensate for the limitations of currently available desk-top microcomputers. By boosting existing computer 'horsepower' with next generation coprocessors and sophisticated graphics tools such as intensity interpolation (Gouraud shading), the realism of computer simulation of flexible sigmoidoscopy is being greatly enhanced. The computer program has teaching and scoring capabilities, making it a truly interactive system. Use has been made of this ability to record, grade and store each trainee encounter in computer memory as part of a multi-center, prospective trial of simulation training being conducted currently in the USA. A new input device, a dummy endoscope, has been designed that allows application of variable resistance to the insertion tube. This greatly enhances tactile feedback, such as resistance during looping. If carefully designed trials show that computer simulation is an attractive and effective training tool, it is expected that this technology will evolve rapidly and be made widely available to trainee endoscopists.

Computer Graphics↗
PubMed1990

The effect of high-dose salmon calcitonin on bone mineral metabolism in the normal rat.

The paucity of information on the effect of long-term high-dose salmon calcitonin administration on normal bone mineral metabolism and histology prompted an investigation of the influence of high-dose synthetic calcitonin in the rat. Serum ionized calcium, osteocalcin or BGP (bone gla protein), and immunoreactive PTH were measured serially during calcitonin administration and bone histomorphometry analyzed at 6 weeks (after sacrifice). Daily injections of salmon calcitonin, 0.4 IU/100 g (group B) and 2 IU/100 g (group C), resulted in significant hypocalcemia at 4 hours for both experimental groups (P less than 0.004). Serum iPTH was significantly higher over the study period for both groups administered calcitonin. Serum BGP levels were significantly lower than controls during the study in group C (P less than 0.002) and to a lesser extent in group B (P less than 0.05). In group C, bone histomorphometry revealed increased resorption (osteoclast count), decreased trabecular bone volume, and decreased double-labeled tetracycline surface (bone formation). In group B an increase in osteoclast count but no alteration in bone formation was observed. To assess the role of PTH in the above findings, high-dose calcitonin was administered to parathyroidectomized rats. All of the above changes in bone histomorphometry were not observed in this group of animals. In conclusion, high doses of calcitonin promote hypocalcemia, secondary hyperparathyroidism, and osteoclastosis in the normal rat in a dose-dependent manner with very high-dose calcitonin impairing bone formation.

Animals↗
PubMed1990

The response of circulating parameters of bone mineral metabolism to ethanol- and EDTA-induced hypocalcemia in the rat.

The mechanism of the acute hypocalcemia that follows acute ethanol administration has not been established. Measurements of parathyroid hormone (PTH) performed during this hypocalcemia reveal conflicting results. We compared the response of ionized calcium (Ca2+), immunoreactive PTH and bone Gla protein (BGP) after ethanol- and EDTA-induced hypocalcemia. 103 male Sprague Dawley rats each weighing approximately 300 g received ethanol and 100 rats of similar weight received EDTA. In each of these studies the animals were divided into experimental and control groups. The ethanol-treated rats received ethanol, 2 g/kg body weight, by ip injection and the EDTA-treated rats received 100 mg EDTA/kg body weight by im injection. Controls received normal saline by the corresponding route of administration. Rats were sacrificed at 0, 30, 60, 90, 180 and 360 min for the measurement of the above parameters. In both experimental groups Ca2+ levels were significantly reduced to the same degree by 30 min with return to control values by 360 min. There was no significant difference in immunoreactive PTH, and BGP between control and ethanol-treated groups. In the EDTA-treated rats, however, PTH values were significantly increased at 30 (P less than 0.005) and BGP at 60 and 90 minutes (P less than 0.005) vs. control. Therefore acute ethanol administration appears to blunt the PTH response to hypocalcemia. A direct inhibitory effect of ethanol on osteoblast function ie BGP production cannot be excluded. In addition, PTH may stimulate BGP.

Animals↗