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Biomedical subjects

M Sieber

Publications and source records attributed to M Sieber.

101 records · Page 6Linked to original sources
PubMed1981

[Trampers in India - Description of a population (author's transl)].

50 trampers in India and Sri Lanka were studied in a semistructured interview by a questionnaire for socio-demographic data, for their medical and psychiatric history and their drug-experience. The MPI (Eysenck) and SSS (Zuckermann) were applied as tests for describing personality. Most of the trampers are around 25 years, stem from medium economical strata, have an education of high school or university. Nearly all of them are experienced drug-users (mainly hashish), most of them for long time without increase of intake and without bodily or mental or social deterioration. In the MPI the score for extraversion and neuroticism is within the (English) norm rage. Female probands showed a higher score of neuroticism than males. The total score in the SSS was significantly higher than in the standard population, mainly due to significantly elevated scores in the scale for disinhibition and boredom susceptibility.

Adult↗
PubMed1979

[Development of narcotics consumption in adolescents 19 and 20 years old. A comparison in the canton of Zurich 1971, 1974 and 1978].

In 1971, 1974 and 1978 representative samples of 19/20-year-old males and females in the Canton of Zurich (Switzerland) answered identical questionnaires on consumption of alcohol, tobacco and drugs. It was thus possible to analyze changes in consumption habits for alcohol, tobacco and drugs by young adults. Consumption patterns changed differently for males and females, with a tendency for females to approach the same levels as males. The number of persons who had been drunk at least once nearly doubled; among men to 68% (as compared to 41% in 1971) and among females to 44% (21%). However, the number of heavy alcohol consumers did not change greatly. The number of cigarette smoking males decreased markedly to 42% (compared to 55%) and is now similar to that of females (43%/41%). The consumption of drugs did not change strikingly. The number of females consuming marijuana increased slightly from 13% to 17%, whereas that of males decreased slightly to 20% (23%). This can be explained by the lower proportion of males with only 1--10 marijuana experiences. The social context of drug consumption shows greater changes than the mere number of consumers: the age of the first drug experience is now considerably lower while differences in drug contact by region or by social strata show a tendency to disappear, with the sole exception of persons without occupational training who now show extremely high drug experiences. It is therefore assumed that drug consumption is no longer a means of self-experience but rather a form of evasive behavior.

Adolescent↗
PubMed1979

[Risk factors for heavy cigarette smoking in young men: a longitudinal study].

In a three-year follow-up on 841 males questioned at the age of 19 and 22 years, an attempt has been made to determine the characteristics of social situation and personality which are correlated with constant heavy cigarette consumption, and what other risk factors are also involved. Bivariate analyses, multiple regression, and path analysis revealed the following influencing factors: personality traits such as nervousness and extraversion, low social integration, low assessment of the subject's own health situation, loose ties with parents, lower school level, increased alcohol and cannabis consumption. No correlation was found with religion, social status of parents, masculinity, blood group or rhesus factor.

Adult↗
PubMed1977

[The epidemiology of drug, cigarette and alcohol consumption in young men].

In view of the recent rise in drug consumption, a 3-year longitudinal study of 19-year-old men was conducted to investigate development of consumption behavior. Consumption of cigarettes and alcohol was also considered. The aim was to obtain information about the development of consumption by 19-year-old men (increase, decrease, etc). The follow-up sample consisted of 841 men in the Canton of Zurich who had been selected from a complete survey of men born in 1952. They answered a questionnaire at the age of 19 and again three years later. The results show that drug, cigarette and alcohol show a different development of consumption in the ages between 19 and 22 years. The percentage of drug consumers had decreased from 23.3 percent to 14.8 percent. In approximately 4 percent there is a high risk of dependence in addition to absence of social integration. The percentage of cigarette smokers did not change (approximately 53 percent), but the number of cigarettes smoked per day increased. For alcohol there is a general increase in consumption. For all three substances, heavy consumption at the age of 19 increases the risk of heavy consumption at the age of 22.

Adult↗
PubMed1976

[Development of drug, alcohol and tobacco consumption. Comparison between 2 studies from 1971 and 1974 in the canton Zurich].

Consumption of drugs, alcohol and tobacco has been compared in two populations of 19-year-old men, of 1971 (2785) and 1974 (1617), drawn from three different geographical regions of the Canton of Zurich. The hypothesis that the percentage of drug users has risen over the last three years was not confirmed: as previously, 25% have had experience of drugs. As expected, however, there was more regular and heavy drug users in 1974 than in 1971. Also, there is a more marked trend towards extension of drug consumption to rural areas than in 1971. The percentage of cigarette smokers has remained stable, but per capita cigarette consumption has increased. Contrary to expectation, alcohol consumption showed the sharpest rise in all three regions. The study suggests that drug consumption is not to be considered in isolation but in conjunction with the use of alcohol and tobacco.

Adolescent↗
PubMedDate not supplied

Pulmonary surfactant protein C containing lipid films at the air-water interface as a model for the surface of lung alveoli.

The pulmonary surfactant lines as a complex monolayer of lipids and proteins the alveolar epithelial surface. The monolayer dynamically adapts the surface tension of this interface to the varying surface areas during inhalation and exhalation. Its presence in the alveoli is thus a prerequisite for a proper lung function. The lipid moiety represents about 90% of the surfactant and contains mainly dipalmitoylphosphatidylcholine (DPPC) and phosphatidylglycerol (PG). The surfactant proteins involved in the surface tension adaption are called SP-A, SP-B and SP-C. The aim of the present investigation is to analyse the properties of monolayer films made from pure SP-C and from mixtures of DPPC, DPPG and SP-C in order to mimic the surfactant monolayer with minimal compositional requirement. Pressure-area diagrams were taken. Ellipsometric measurements at the air-water interface of a Langmuir film balance allowed measurement of the changes in monolayer thickness upon compression. Isotherms of pure SP-C monolayers exhibit a plateau between 22 and 25 mN/m. A further plateau is reached at higher compression. Structures of the monolayer formed during compression are reversible during expansion. Together with ellipsometric data which show a stepwise increase in film thickness (coverage) during compression, we conclude that pure SP-C films rearrange reversibly into multilayers of homogenous thickness. Lipid monolayers collapse locally and irreversibly if films are compressed to approximately 0.4 nm2/molecule. In contrast, mixed DPPG/SP-C monolayers with less than 5 mol% protein collapse in a controlled and reversible way. The pressure-area diagrams exhibit a plateau at 20 mN/m, indicating partial demixing of SP-C and DPPG.(ABSTRACT TRUNCATED AT 250 WORDS)

Air↗
PubMedDate not supplied

Idiotype vaccine against Hodgkin's lymphoma: generation and characterization of an anti-idiotypic monoclonal antibody against the Hodgkin-associated (anti-CD 30) monoclonal antibody HRS-3.

The murine monoclonal antibody HRS-3 (Ab1; isotype IgG1-Kappa), that defines the CD30 antigen (m.w. 120,000) expressed by Hodgkin-Reed Sternberg cells was used to generate monoclonal anti-idiotype antibodies (Ab2) in syngeneic BALB/c mice. Ab2 were selected on the basis of their binding to HRS-3 immunoglobulin and F(ab')2 fragments and lack of reactivity with the whole immunoglobulin or F(ab')2 fragments of unrelated monoclonal antibodies of the same isotype and allotype. Such a putative anti-idiotypic Ab2, was designated antibody 12D3 and further characterized. 12D3 bound to the paratope of HRS-3, as determined by a 85% inhibition of binding of biotinylated HRS-3 to the cell surface of the CD30 positive Hodgkin cell line L450, and to semipurified CD30 positive cell lysates thereof at a concentration as low as 50 ng/well. These results demonstrate that 12D3 binds at or near the binding site of HRS-3 to the CD30 antigen. Purified 12D3 was coupled to keyhole limpet hemocyanine and used to immunize BALB/c mice and rabbits in order to obtain an Ab3 which binds to the CD30 antigen. These immune sera inhibited the binding of biotinylated 12D3 with HRS-3. Moreover, they showed binding activity with the CD30 positive L540 Hodgkin cell line as well as with the L540 cell lysates, indicating that an anti-anti-idiotopic antibody (Ab3) shares idiotopes with Ab1 (HRS-3). These data suggest that antibody 12D3 may be useful in the generation of an anti-idiotype vaccine against Hodgkin's lymphomas.

Animals↗
PubMedDate not supplied

Marked interspecies differences between humans and pigs in cyclosporine and prednisolone disposition.

Pigs have been used extensively in various transplantation protocols. Immunosuppressive therapy is usually performed by steroids and cyclosporine A (CyA). For rational dosage of these xenobiotics, their pharmacokinetics should be characterized. Therefore, we investigated the kinetics of prednisolone, an immunobiologically active steroid, after oral and iv administration, and of CyA, after oral and iv dosing, in seven pigs and compared these results with those obtained in 20 renal transplant patients. The mean area under the blood concentration versus time curve of CyA (HPLC measurements) was lower in pigs than in humans after oral (67 +/- 31 micrograms/ml x min vs. 296 +/- 101 micrograms/ml x min) and after iv (358 +/- 71 micrograms/ml x min vs. 858 +/- 292 micrograms/ml x min) doses of CyA. Compared to humans, pigs had lower concentrations of total prednisolone--assessed by HPLC--after oral prednisone (7.1 +/- 4.3 micrograms/ml x min vs. 297.9 +/- 75.6 micrograms/ml x min) and after iv prednisolone (26.8 +/- 9.5 micrograms/ml x min vs. 373.3 +/- 77.7 micrograms/ml x min). The plasma concentrations of both agents, lower in pigs than in humans, were attributable to an increased volume of distribution, an increased clearance, and more of a diminished systemic availability in pigs than in humans. Thus, to obtain the same target concentrations of CyA and prednisolone in both species, pigs require about 2 to 4 times higher iv or oral doses of CyA and 10 to 30 times higher iv or oral doses of steroids.

Administration, Oral↗