PubMed Health⌕ Search

Biomedical subjects

J Enderlein

Publications and source records attributed to J Enderlein.

6 recordsLinked to original sources
PubMed2000

Forbidden light detection from single molecules

We present a new concept for ultrasensitive detection of surface-generated fluorescence which is made possible by a new optical module. The detection method leads to an enhancement in fluorescence collection efficiency to more than 65% of the total of emitted light, whereas high-aperture microscope objectives are able to collect 44% at best. Moreover, by employing this new optical module, the detection volume can be restricted to approximately 10(-17) L. This allows for an exceptional discrimination of bulk-generated against surface-generated fluorescence, which may be of great value when surface-binding processes are monitored. We demonstrate the performance of the new detection system by detecting single fluorescent molecules and by determining antigen concentrations down to 5 fmol.

Journal Article↗
PubMed2000

A theoretical investigation of single-molecule fluorescence detection on thin metallic layers.

In the present paper, the excitation and detection of single-molecule fluorescence over thin metallic films is studied theoretically within the framework of classical electrodynamics. The model takes into account the specific conditions of surface plasmon-assisted optical excitation, fluorescence quenching by the metal film, and detection geometry. Extensive numerical results are presented for gold, silver, and aluminum films, showing the detectable fluorescence intensities and their dependence on film thickness and the fluorescent molecule's position under optimal excitation conditions.

Aluminum↗
PubMed1999

Theoretical investigation of aspects of single-molecule fluorescence detection in microcapillaries.

In the present report, the results of a theoretical investigation of two aspects of single-molecule detection by laser-induced fluorescence in microcapillaries are presented. The two issues studied are the scattering of the exciting laser beam on the microcapillary and the change of the fluorescence lifetime of the molecule due to the electrodynamic interaction between its fluorescence emission and the confining capillary. Numerical results for experimentally relevant conditions are provided.

Fluorescence↗
PubMed1987

Substance P in human essential hypertension.

Substance P (SP) plays an important role in central nervous and peripheral blood pressure regulation. Its effects include modulating influence on the adrenergic system and inhibition of stress-induced plasma noradrenaline increase in animal studies. In patients with essential hypertension (n = 45, WHO stages 1 and 2) the SP-like immunoreactivity (SPLIR) was found significantly (p less than 0.01) lower (1.36 +/- 0.23 pg/100 microliters) than in 24 normotensive subjects (4.54 +/- 0.72 pg/100 microliters). Furthermore, the influence of a mental stress test on SPLIR was investigated in patients with essential hypertension (n = 11, WHO stage 1) and compared with nine normotensive subjects. Whereas in normotensive subjects plasma SP increased under a standardized mental arithmetic test (4.03 +/- 0.48 to 4.74 +/- 0.56 pg/100 microliters), in hypertensive patients a decrease of SP from lower baseline levels (2.85 +/- 0.54 to 2.57 +/- 0.54 pg/100 microliters) was demonstrated. The significantly different changes of plasma SP in normotensive and hypertensive subjects under mental stress conditions had the opposite direction in comparison with the adrenergic reaction [higher and prolonged increase of plasma noradrenaline (NA) in the hypertensive group]. Under antihypertensive drug treatment with prazosin (4.5 mg/day, n = 10) or with captopril (450 mg/day, n = 10) an increase of plasma SP was registered. The results support the participation of SP in the pathogenesis of human hypertension and in therapeutic mechanisms. Lower plasma levels and decreased responsiveness of SP possibly represent the enhanced stress sensitivity in primary hypertension.

Adult↗
PubMed1987

[The blood pressure-regulating role of the renin-angiotensin system in essential hypertension before and after emotional stress].

The aim of the study was to prove the correlations between systolic and diastolic blood pressure (BP), heart rate (HR) and plasma renin activity (PRA) under mental arithmetic stress without and with beta-blockade. 22 male hypertensive patients (aged 19-39 years) were examined, divided into a group treated with d, 1-propranolol (Obsidan) and a control group receiving placebo. Under arithmetic stress the kinetics of systolic BP showed no differences even after beta-blockade. In contrast, the increases of HR and PRA before, during and after mental arithmetic were either significantly reduced (HR) or completely blocked (PRA) under beta-blockade. However, these suppressions of HR and PRA did not prevent the stress-induced elevations of systolic and diastolic BP under beta-blockade.

Adult↗