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Biomedical subjects

H Lane

Publications and source records attributed to H Lane.

48 records · Page 3Linked to original sources
PubMed1978

Demonstration of saturation kinetics in the intestinal absorption of vitamin C in man and the guinea pig.

Intestinal absorption of ascorbic acid is believed to be mediated through a sodium-dependent active transport process in man and in the guinea pig, both species having a nutritional requirement for the vitamin. Vitamin C transport was studied in man and in the guinea pig by in vivo intestinal perfusion of concentrations of vitamin C ranging from physiologic to clearly pharmacologic levels. Triple lumen intestinal perfusion of seven human volunteers with vitamin C concentrations ranging from 0.85 to 11.36 mM demonstrated saturation kinetics of absorption with a Km = 5.44 mM. Net secretion of water was observed in three of seven humans with the highest (11.36 mM) concentration of vitamin C. Perfusion of isolated segments of guinea pig intestines with intact blood supply also revealed saturation kinetics (Km = 5.54 mM) in the range of 1.42 to 56.8 mM vitamin C but linear absorption below this range. The phenomenon of decreased water absorption noted with incremental vitamin C dose in human volunteers could not be reproduced in the guinea pig, nor were the intestinal tissue levels of cyclic AMP and GMP increased by high-dose vitamin C in this species. This study suggests that "megavitamin" doses of vitamin C (greater than 1 Gm) are probably not as efficiently absorbed as smaller multiple doses of the vitamin. Intestinal secretion of water may contribute to the diarrhea which is the most common side effect of large doses of vitamin C. The guinea pig is a useful but limited model for vitamin C absorption in man.

Adult↗
PubMed1976

How the listener integrates the components of speaking rate.

The rate of speaking in words per minute is a function of three independent variables, namely, articulation rate and the number and durations of pauses. The present study varies each of these components separately in a factorial design in order to determine how the listener combines them into a global impression of speech rate. A model was obtained by direct scaling and linear regression that accounts reasonably well for the estimates of apparent rate obtained in this and several other studies. It provides for a trading relation between articulation rate and pause rate in which the former is much more influential in determining the listener's perception of speech rate.

Acoustic Stimulation↗
PubMed1976

Comparative human intestinal bioavailability of vitamin B-6 from a synthetic and a natural source.

Intraluminal perfusion of human jejunum has not been previously reported to demonstrate differences in bioavailability of vitamins from a food product. In this report, a triple lumen tube with a 30 cm study segment was used to study water soluble vitamin absorption in 15 normal subjects serving as their own controls. The intestinal uptake of vitamin B-6 from organ juice (O) and from a synthetic solution (S) perfused at 7.6 ml/minute were compared. In a separate series of perfusions in six subjects, the absorption of a mixture pf pyridoxine, pyridoxal, and pyridoxamine from O and S solutions with and without glucose were compared. Mean vitamin B-6 absorption was significantly greater from S (65% uptake, transport rate 0.71 mug/cm/hour) than from 9 (30% uptake, transport rate 0.40 mug/cm/hour, p less than 0.05). The addition of glucose to S enhanced this difference. Triple lumen intestinal perfusion can be used to discriminate difference in bioavailability of water soluble vitamins from natural and synthetic sources.

Biological Availability↗
PubMedDate not supplied

The osteogenic potential of extracorporeal shock wave therapy. an in-vivo study.

We studied the effects of extracorporeal shock wave therapy (ESWT) on the healing potential of osteotomies in rabbit radii. The results of sequential low dose shock wave therapy were compared prospectively with natural healing in the radii of New Zealand white rabbits. Our results suggest that ESWT causes new bone formation locally. However such exuberant callus formation does not equate with accelerated fracture healing and in fact implies a delay in the remodelling process.

Animals↗
PubMedDate not supplied

Ossifying fibromyxoid tumour of soft parts.

Ossifying fibromyxoid tumour of soft parts (OFMT) is a recently described soft tissue tumour. Although rare it deserves recognition as a locally invasive but essentially benign neoplasm. Prior to its description in 1989 by Enzinger, ossifying fibromyxoid tumours of soft parts were classified as a wide variety of lesions, ranging from nodular fasciitis to osteosarcoma. We report a typical case of such a tumour and review current knowledge of this distinct neoplasm.

Aged↗
PubMedDate not supplied

Uptake and localization of selenium-75 in mammary epithelial cell lines in vitro.

The uptake and subcellular localization of selenium-75 was examined in 3 established mammary cell lines in vitro. Previous studies had demonstrated that cell line YN-4 exhibited a biphasic growth response to selenium, whereas cell lines CL-S1 and WAZ-2t exhibited only an inhibition of growth. All 3 cell lines incorporated selenium-75 readily over a 48-h incubation period and the concentration of selenium-dependent glutathione peroxidase was correlated with the level of selenium-75 uptake. However, neither of these 2 parameters could be related to the unique biphasic growth response exhibited by cell line YN-4. The intracellular localization of selenium-75 was similar in lines CL-S1 and YN-4 with the label incorporated primarily in the cytosol and secondarily in the mitochondria. Although the unique growth response of line YN-4 could not be attributed to the incorporation parameters examined herein, the stable incorporation of selenium-75 at high levels should make these lines useful for further studies on the subcellular localization of selenium into organelles and macromolecules.

Animals↗