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Biomedical subjects

B Scott

Publications and source records attributed to B Scott.

At least 163 records · Page 9Linked 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↗
PubMed1978

Chest physiotherapy in the newborn: effect on secretions removed.

The amount of upper airway secretions removed by suction alone was compared to that removed after chest physiotherapy in six neonates with a clinically suspected problem of increased respiratory tract secretions. More secretions were removed after physiotherapy.

Humans↗
PubMed1975

Properties of protein-chlorophyll complexes from pea (Pisum sativum L.) leaves. The organization of chlorophyll.

Chlorophyll-protein-detergent complexes were prepared from pea chloroplasts by using sodium dodecylbenzenesulphonate and polyacrylamide-gel electrophoresis. Circular-dichroism spectra showed that complex CPI has a dimeric arrangement of chlorophyll a, with additional weaker interactions. Ellipticities were determined for both complexes and for purified chlorophylls in solution, and it is argued that the circular dichroism of complex CPII is derived from chlorophyll-protein interaction rather than from interaction between chlorophylls a and b. The detergent could be removed from the complexes by using urea and gel filtration, leaving the chlorophyll-protein in solution, although in each case a diminished ellipticity indicated some loss of organization. Three-peaked circular-dichroism spectra of chloroplast fragments before and after addition of detergent were compared with a curve obtained by summing graphically the spectra of complexes CPI, CPII and the free-pigment fraction. There was good correspondence at 650 nm, and the longer-wavelength peaks agreed in form and magnitude, but with discrepancies in position. It was concluded that complexes CPI and CPII pre-exist in the original material, but that there is an environmental effect which is destroyed when the complexes are extracted.

Benzenesulfonates↗
PubMed1975

Acute intravenous tolerance of etidocaine.

Etidocaine can be said to be midway between lidocaine and bupivacaine in respect to its toxicity. Its therapeutic ratio will depend on a more exact comparison of the clinical efficacy of the three agents.

Acetanilides↗
PubMedDate not supplied

Heterologous and homologous plasmid integration at a spore-pigment locus in Penicillium paxilli generates large deletions.

Mutations in a spore pigmentation locus (brs; brown spore) in Penicillium paxilli were isolated at a relatively-high frequency (0.17%) following integrative transformation of the hygromycin-resistance plasmid pAN7-1. A molecular analysis of four independently-isolated Brs- mutants showed that all contained pAN7-1 integrated at a single-site that was unique for each mutant. A previously-described Brs- mutant, YI-34 (Itoh et al. 1994), was a two-site integration. Three of the mutants had multiple copies of pAN7-1 arranged in head-to-tail tandem arrays. A 9.6-kb BamHI junction fragment was cloned from one of these, YI-33, by plasmid rescue and used to isolate two overlapping lambda clones, lambda WB33-1 and lambda WB33-2, that span about 30 kb in the region of the wild-type locus. When genomic digests of the five Brs- mutants were probed with these lambda clones all of them were found to contain an extensive deletion through a common region of the P. paxilli genome. Subsequent attempts to generate one-step gene replacements within a 4.5-kb EcoRI fragment at the wild-type locus resulted in the isolation of Brs- mutants at a frequency of 1.6%, but all mutants with this phenotype were also found to contain an extensive genomic deletion. Therefore, a common outcome of both heterologous and homologous plasmid integration at this locus is deletion formation.

Base Sequence↗