Biomedical subjects

P Teubner

Publications and source records attributed to P Teubner.

6 recordsLinked to original sources

PubMed2001

Changes of AT(2) receptor levels in the rat adrenal cortex and medulla induced by bilateral nephrectomy and its modulation by circulating ANG II.

We studied regulation of the AT(2) receptor by investigating the effect of bilateral nephrectomy (bNX) in Sprague-Dawley rats. The expression of aldosterone synthase (CYP11B2) and AT(2) receptor mRNA was detected by nonradioactive in situ hybridization. AT(2) receptor mRNA was detected in cells of the first two or three subcapsular cell layers of the zona glomerulosa (ZG) and in the medulla of sham-operated animals. After bNX, the number and area of distribution of AT(2) receptor-positive cells increased in the ZG. This was associated with an enlargement of the steroidogenic active ZG and with reduced proliferation rate (sham 5.9 +/- 0.9%; bNX 2.4 +/- 0.2%; p<0.02). Infusion of angiotensin II (ANG II; 200 ng/kg/min SC for 56 hr) to bNX rats did not reverse the effect of nephrectomy on the distribution of AT(2) receptor expression, although mRNA levels per cell were reduced compared to NX alone. ANG II infusion decreased proliferation rate further (0.4 +/- 0.07%; p<0.001). In the adrenal medulla after bNX, decreased expression of the AT(2) receptor was associated with increased proliferation (2.6 +/- 0.2% vs 6.6 +/- 0.5%). These results demonstrate differential regulation of the AT(2) receptor in the adrenal gland and suggest that expression of the AT(2) receptor is involved in regulating proliferation and differentiation in the ZG and medulla. (J Histochem Cytochem 49:649-656, 2001)

Adrenal Cortex↗

PubMed1999

Odor structure-activity relationships compared in human and nonhuman primates.

The ability of 4 squirrel monkeys to distinguish between members of 3 homologous series of substances (aliphatic alcohols, aldehydes, and ketones) was investigated, and their performance was compared with that of a group of 10 human participants. With all 3 substance classes, and in both species, a significant negative correlation was found between discrimination performance and structural similarity of odorants in terms of differences in carbon chain length. These findings suggest carbon chain length of aliphatic odorants to be one of presumably several determinants of the interaction between stimulus molecule and olfactory receptor and support the assumption that human and nonhuman primates may share common mechanisms of odor quality perception.

Adult↗

PubMed1999

Olfactory discrimination ability of human subjects for ten pairs of enantiomers.

We tested the ability of human subjects to distinguish between enantiomers, i.e. odorants which are identical except for chirality. In a forced-choice triangular test procedure 20 subjects were repeatedly presented with 10 enantiomeric odor pairs and asked to identify the bottle containing the odd stimulus. We found (i) that as a group, the subjects were only able to significantly discriminate the optical isomers of alpha-pinene, carvone and limonene, whereas they failed to distinguish between the (+)- and (-)-forms of menthol, fenchone, rose oxide, camphor, alpha-terpineol, beta-citronellol and 2-butanol; (ii) marked individual differences in discrimination performance, ranging from subjects who were able to significantly discriminate between 6 of the 10 odor pairs to subjects who failed to do so with 9 of the 10 tasks; (iii) that with none of the 10 odor pairs were the antipodes reported to differ significantly in subjective intensity when presented at equal concentrations; and (iv) that error rates were quite stable and did not differ significantly between sessions, and thus, we observed a lack of learning or training effects. Additional tests of the degree of trigeminality and threshold measurements of the optical isomers of alpha-pinene, carvone and limonene suggest that the discriminability of these three enantiomeric odor pairs is indeed due to differences in odor quality. These findings support the assumption that enantioselective molecular odor receptors may only exist for some but not all volatile enantiomers and thus that chiral recognition of odorants may not be a general phenomenon but is restricted to some substances.

Adult↗

PubMed1999

Olfactory discrimination ability for homologous series of aliphatic alcohols and aldehydes.

We tested the ability of human subjects to distinguish between members of homologous series of aliphatic alcohols (ethanol to n-octanol) and aldehydes (n-butanal to n-decanal). In a forced-choice triangular test procedure 20 subjects per series were repeatedly presented with all 21 binary combinations of the seven stimuli and asked to identify the bottle containing the odd stimulus. We found (i) that as a group, the subjects performed significantly above chance level in all tasks but two with the alcohols and all tasks but four with the aldehydes, and thus were clearly able to discriminate between most of the odor pairs presented; (ii) marked interindividual differences in discrimination performance, ranging from subjects who were able to significantly distinguish between all 21 odor pairs of a series to subjects who failed to do so with the majority of tasks; and (iii) a significant negative correlation between discrimination performance and structural similarity of odorants in terms of differences in carbon chain length for both homologous series. This suggests that carbon chain length may be one of presumably several determinants of the interaction between stimulus molecule and receptor, and thus may be a molecular property affecting odor quality of aliphatic alcohols and aldehydes.

Adult↗

PubMed1999

Enantioselectivity of odor perception in squirrel monkeys and humans.

With use of a conditioning paradigm, the ability of six squirrel monkeys to distinguish between 10 pairs of enantiomers, i.e., odorants that are identical except for chirality, was investigated. As a group, the animals were only able to discriminate between the optical isomers of alpha-pinene, carvone, limonene, and fenchone, whereas they failed to distinguish between the (+) and (-) forms of beta-citronellol, menthol, rose oxide, 2-butanol, alpha-terpineol, and camphor. With use of a triple forced-choice procedure, 10 human subjects were tested for their ability to discriminate between the same enantiomeric odor pairs in parallel and, with the exception of fenchone, showed a very similar pattern of performance compared with the squirrel monkeys. These findings support the assumption that human and nonhuman primates may share common principles of odor quality perception. Furthermore, the results suggest that, in both species, enantioselective molecular odor receptors may only exist for some, but not all volatile enantiomers and thus that chiral recognition of odorants is not a general phenomenon, but may be restricted to some substances.

Adult↗

PubMed1998

Odor structure-activity relationships of carboxylic acids correspond between squirrel monkeys and humans.

With use of a conditioning paradigm, the ability of four squirrel monkeys to distinguish n-valeric acid from n-forms and isoforms of other carboxylic acids (acetic acid to octanoic acid) was investigated. All four animals were clearly able to discriminate between all odor pairs tested and showed a significant negative correlation between discrimination performance and structural similarity of odorants in terms of differences in carbon chain length of the carboxylic acids. Branching of the carbon chain was also found to affect odorant quality because all animals performed better in discriminating n-valeric acid from isoforms of other carboxylic acids compared with the corresponding n-forms of these substances. With use of a triple forced-choice procedure, 10 human subjects were tested on the same tasks in parallel and showed a very similar pattern of discrimination performance compared with the squirrel monkeys. Thus the results of this study provide evidence of well-developed olfactory discrimination ability in squirrel monkeys for carboxylic acids and support the assumption that human and nonhuman primates may share common principles of odor quality perception.

Adult↗