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Biomedical subjects

W Beier

Publications and source records attributed to W Beier.

At least 19 recordsLinked to original sources
PubMed2005

On maximum human life span: interdisciplinary approach about its limits.

BACKGROUND: This is a theoretical approach on the question on how much maximally may extend the life of human individual. The starting point of this work was the biological consideration of two changes in human characteristics which took place during the last century up to now, namely human beings lived remarkably longer and are becoming taller. METHODS: Demography data and Gompertz deduced mathematics, either related to growth or survival, were the two columns on which the basis of this study has been supported. Respective equations were adapted to the purpose searched applying parameters of. normal body growth and cell growth in vitro. Having individual age on the abscisse, that of its crossing point with ordinate value indicates the age in which no more cell activity should exist, either of proliferation or migration. RESULTS: Despite rising life expectancy, whose extrapolation leads to remarkable enhance for future values, life span calculations with the help of our mathematic models do not indicate an extent beyond the limit of 120 years. Nevertheless hypothetically there is the exception of prolonging life out of the mentioned limit when growth and ageing would be proportional interrelated. Furthermore, when proliferation results of in vitro smooth muscle cell cultures were related to age of donor, its linear regression crosses the x-axis at an age of 110.16 years (mean value of different procedures of measurement) . This limit is not far from that using other cell activity parameters as migration (117.7 years when cessation) or such state of senescent (98 years when all cells involved). Nevertheless with the help of Gompertz equation putting growth in the ordinate (proliferation activity) instead mortality and donor age in the x-axis, the follow up of the curve is similar to that known of survival up to the age of 80. But this procedure does not seem adequate to obtain information on the limit of life potential because of later this curve becomes very flat reaching the end at age around 180; this seems not to be real but due to an artefact. Finally IGF-1 prolongs the cessation ( x-axis crossing point) of cell growing activity up to donor age of around 126.4 years. CONCLUSIONS: Human life span seems to be limited up to around 120 years, but growth process modulating factors could theoretically enhance it.

Biomarkers↗
PubMed2000

Relationship between procalcitonin plasma levels and severity of injury, sepsis, organ failure, and mortality in injured patients.

OBJECTIVE: To compare procalcitonin (PCT) plasma levels of injured patients with the incidence and severity of systemic inflammatory response syndrome (SIRS), infection, and multiple organ dysfunction syndrome (MODS) and to assess the predictive value of PCT for these posttraumatic complications. DESIGN: Retrospective study comparing patients with mechanical trauma in terms of severity of injury, development of infectious complications, and organ dysfunctions. SETTING: Level I trauma center with emergency room, intensive care unit, and research laboratory. PATIENTS: Four hundred five injured patients with an Injury Severity Score of > or =9 points were enrolled in this study from January 1994 to February 1996. INTERVENTIONS: Blood samples were collected on the day of admission and on days 1, 3, 5, 7, 10, 14, and 21 thereafter. MEASUREMENTS AND MAIN RESULTS: We determined PCT serum levels using a specific immunoluminometric assay. We retrospectively evaluated the occurrence of SIRS, sepsis, and MODS using patients' charts. Mechanical trauma led to increased PCT plasma levels dependent on the severity of injury, with peak values on days 1 and 3 (p < .05) and a continuous decrease within 21 days after trauma. Patients who developed SIRS demonstrated a significant (p < .05) increase of peak PCT plasma levels compared with patients without SIRS. The highest PCT plasma concentrations early after injury were observed in patients with sepsis (6.9+/-2.5 ng/mL; day 1) or severe MODS (5.7+/-2.2 ng/mL; day 1) with a sustained increase (p < .05) for 14 days compared with patients with an uneventful posttraumatic course (1.1+/-0.2 ng/mL). Moreover, these increased PCT plasma levels during the first 3 days after trauma predicted (p < .0001; logistic regression analysis) severe SIRS, sepsis, and MODS. CONCLUSIONS: These data indicate that PCT represents a sensitive and predictive indicator of sepsis and severe MODS in injured patients. Routine analysis of PCT levels seems to aid early recognition of these posttraumatic complications. Thus, PCT may represent a useful marker to monitor the inflammatory status of injured patients at risk.

APACHE↗
PubMed1996

Molecular cloning and expression of mouse procalcitonin.

The nucleotide sequence for mouse calcitonin was determined from a cDNA obtained using a polymerase chain reaction (PCR) based method, the rapid amplification of cDNA ends (RACE)-PCR. Primers designed from highly conserved regions in the coding sequences of known rat and human calcitonin cDNAs were used to amplify calcitonin cDNA as 5'-end and 3'-end fragments from mouse thyroid RNA. The obtained cDNA is 850 bp in length most probably representing the entire mouse calcitonin mRNA. It contains an open reading frame coding for a 136 amino acid protein with a calculated M(r) of 15,143. Comparison of the deduced amino acid sequences of preprocalcitonin of mice with other species revealed highest homologies to the rat (93%) and human (77%) sequences. A recombinant form of mouse precalcitonin (rmPCT) of approximately 17 kDa was expressed as a fusion peptide in E.coli transformed with a PCR-cloned expression construct.

Amino Acid Sequence↗
PubMed1993

[Hypertension and disorders of cognitive function].

In the treatment of hypertension, the aspect of cognitive function is now becoming ever more important. In recent years, the influence of hypertension itself--as well as that of anti-hypertensive treatment--on cognitive functioning has repeatedly been investigated. The results obtained differ too widely to permit any final statement to be made on the relationships involved. The reasons for these differences seem to be due in particular to differences in the methods of investigation and random sampling involved in the studies. More recent studies, however, seem to support a relationship between hypertension and decreased cognitive performance. Improved investigations are expected to produce more detailed results in the future.

Antihypertensive Agents↗
PubMed1992

[Interactions of theophylline and H2 receptor antagonists. Interaction modes--clinical relevance].

UNLABELLED: Basic considerations: peptic ulcers and obstructive diseases occur jointly, since cigarette smoking is an important causal factor in both diseases. Major topics: The interaction possibilities of theophylline and H2-receptor antagonists on the various levels from absorption to elimination of the two drugs are discussed, with emphasis being attached to oxidative breakdown in the liver. The clinical relevance of such interactions arises from the limited therapeutic spectrum of theophylline. CONCLUSIONS: Treatment with both drugs should take account of the varying tendency of the individual H2-receptor antagonists to interact.

Drug Interactions↗
PubMed1992

Opponent colour coding is a universal strategy to evaluate the photoreceptor inputs in Hymenoptera.

Behavioural tests were carried out with 9 hymenopteran insect species, which ranked certain sets of coloured stimuli according to their subjective similarity to a previously memorized stimulus. Kendall's tau co-efficient is employed for the analysis of correlation between these similarity rankings and the colour distance rankings predicted by various models of neural colour computation. The models are based on the measured spectral sensitivities of photoreceptor colour types and use a variety of simple colour coding systems to derive hypothetical colour distances. The correlation between the predictions of the models and the behavioural results serves as a measure for the likelihood of existence of a colour coding system. In all species, the similarity rankings can be best explained by assuming that colour is coded on a perceptual level by two colour opponent mechanisms. Brightness differences are ignored, indicating that an intensity-coding sub-system is not used in colour discrimination by the insects investigated. The weighting factors of the colour opponent mechanisms differ between species in detail, but not in the principles involved. It is thus possible to employ a standard measure of perceptual colour distance (colour hexagon distance) to predict the capacities of colour discrimination adequately in all the tested insects.

Agonistic Behavior↗
PubMed1987

Absolute bioavailability of theophylline from a sustained-release formulation using different intravenous reference infusions.

The effect of different intravenous infusions on the absolute bioavailability of theophylline from a sustained-release formulation has been investigated. Oral administration of 750 mg theophylline (2 capsules Euphylong 375) was referenced to intravenous aminophylline infusions corresponding to 506 mg theophylline over 8 h (63 mg.h-1) in Study 1, and to 749 mg theophylline over 14 h in Study 2. A reduction in the infusion rate from 69 to 33 mg.h-1 was made in Study 2 after 8 h in order to mimic the concentration/time profile of the oral formulation as closely as possible. The absolute bioavailability was 100 (89, 115)% in Study 1 and 88 (73, 105)% in Study 2. The lower clearance values and, as a consequence, the lower bioavailability ratios observed with the higher intravenous dose, although not significant, indicate that the absolute bioavailability of theophylline might appear to depend on the choice of the intravenous reference standard.

Adult↗
PubMed1987

Theophylline steady-state pharmacokinetics: recent concepts and their application in chronotherapy of reactive airway diseases.

With the introduction of sustained-release theophylline formulations for once-daily dosing or for unequally divided twice-daily dosing, comparison with conventional equally divided twice-daily dosing has been focused on nocturnal serum theophylline concentrations (STCs), plateau properties and peak-trough fluctuation. The merits of various steady-state characteristics such as nocturnal excess, plateau time, residual concentration, peak-trough fluctuation, swing and AUC fluctuation are illustrated by 15 data sets from 7 multiple-dose studies, each including either 10-12 healthy volunteers or 12-20 COPD-patients. In all of the studies, STCs were determined at least every 2 hr over a 24-hr period in steady-state. Included in the studies were 7 sustained-release theophylline formulations which were administered either once daily (in the morning or in the evening), or twice daily (either equally divided, or unequally divided with one-third of the dose being given in the morning and two-thirds in the evening.

Circadian Rhythm↗
PubMed1987

Effect of drug intake prior to or after meals on serum theophylline concentrations: single-dose studies with Euphylong.

Three separate single-dose, randomized, cross-over studies in normal, healthy volunteers were performed to investigate the possible influence of drug intake in relation to concomitant food intake and of different dietary habits such as cold and hot evening meals on the bioavailability of theophylline from Euphylong. Euphylong is a new, pH- and rpm-independent theophylline formulation designed for once-daily administration in the evening. The results obtained show that the timing of drug intake, in relation to concomitant food intake, has no influence on the bioavailability of Euphylong. Under equicaloric conditions, a 10% decrease in AUC and a 20% decrease in Cmax is observed when Euphylong is administered after a hot evening meal compared with a cold evening meal. Viewed against the dramatic changes in bioavailability of up to 100%, which have been observed for certain other sustained-release theophylline formulations, these minor changes for Euphylong are negligible and without clinical relevance.

Adult↗
PubMed1986

Once daily theophylline: multiple-dose comparison of an encapsulated micro-osmotic system (Euphylong) with a tablet (Uniphyllin).

In a randomized, multiple-dose, cross-over study, serum theophylline concentrations (STC) were compared in 12 healthy volunteers for 24 hours after the first and seventh administration of two sustained-release formulations. The preparations tested were the new encapsulated micro-osmotic system Euphylong (E) and the tablet Uniphyllin (U). Daily doses of 800 mg were administered at 7 p.m., half an hour after a standardized evening meal. The relative bioavailability of E with respect to U under steady-state conditions is 93 (83-105)%. In contrast to U, E markedly truncates the high peak concentrations and leads to a sustained, plateau-like concentration throughout the night. Therefore prediction of individual maximum serum levels becomes possible for E on the basis of one blood sample taken in the morning. The significantly improved in vivo performance of E in comparison with U is reflected in a 50% reduction of the swing, a 60% increase in the plateau time, and a substantial reduction of theophylline-specific side effects such as nausea, palpitations and increased diuresis.

Biological Availability↗
PubMed1984

[Oral theophylline therapy for dyspnea].

With regard to special situations in severe dyspnea 10 patients with reversible airway obstruction were studied to verify the effect of oral and systemic application of 193,2 mg Theophyllinmonohydrat and 46,8 mg Aethylendiamin as customary in the trade injection fluid (Euphyllin) on blood levels. In comparison both medications are bioaquivalent . The oral application yields with duration serum concentrations of theophylline higher than 5 mg/l but less than the postulated therapeutic levels from 10--20 mg/l.

Administration, Oral↗
PubMed1984

Mechanical and biochemical alterations in guinea-pig tracheae caused by sensitisation.

In order to test the hypothesis of beta-adrenergic receptor blockade in asthma bronchiale directly at the site of the asthmatic reaction, the tracheobronchial tree, we searched for mechanical and biochemical differences between isolated tracheae of actively sensitized and normal guinea pigs. The dose-response curves of terbutaline on isolated tracheae of actively sensitized guinea pigs were significantly shifted to the right in comparison with control trachea (ED50 11.8 X 10(-8) and 5.2 X 10(-8) M respectively). The sensitized organs dilated significantly slower than did controls (0.186 and 0.350 cm H2O/s, respectively) after addition of terbutaline, whereas the dilation velocity after addition of theophylline did not differ. The stimulation with fenoterol led to significantly lower amounts of cAMP in sensitized than in control tracheae (24.3 and 33.2 pmol/mg protein, respectively). The Km1 and Km2 of cAMP-phosphodiesterases of tracheal homogenates did not differ in both groups. Beta-adrenergic receptor binding studies with 3H-dihydro-alprenolol did not reveal a remarkable difference between sensitized and normal tracheae. The results indicate, that sensitization led to a partial blockade of the beta-adrenergic receptor adenylatecyclase system. However, the exact site of this effect remains obscure.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1980

On a mathematical relationship between growth rate and life span.

Using the Principles of Similitude a relation between the life span of an organism and its growth rate, ageing rate and initial weight is derived. It is shown that considerations based only on dimensional homogeneity allow us to make non-trivial assertions about the form of the equation of state. Closely related to these considerations is the specification of dimensionless numbers which we defined in the Concept of Vitality.

Animals↗
PubMed1980

[System theoretical aspects of senescence (author's transl)].

If senescence is identified with system failure, then we must consider the possibility that there exist modes of failure which do not arise from local subsystem failures. We show that any system manifesting a feed forward mode of control will in general exhibit senescence. Together with the concept of vitality a number of results are drawn from this argument especially for the calculation of the biological age.

Adolescent↗