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Biomedical subjects

J Stieber

Publications and source records attributed to J Stieber.

At least 19 recordsLinked to original sources
PubMed2003

Induced abnormality in Mir- and Earth grown Super Dwarf wheat.

Super-dwarf wheat grown on the Mir space station using the Svet "Greenhouse" exhibited morphological, metabolic and reproductive abnormalities compared with Earth-grown wheat. Of prominent importance were the abnormalities associated with reproductive ontogeny and the total absence of seed formation on Mir. Changes in the apical meristem associated with transition from the vegetative phase to floral initiation and development of the reproductive spike were all typical of 'Super-Dwarf' wheat up to the point of anthesis. Observation of ruptured anthers from the Mir-grown plants revealed what appeared to be normally developed pollen. These pollen gains, however, contained only one nuclei, while normal viable pollen is tri-nucleate. A potentially important difference in the flight experiment, compared with ground reference studies, was the presence of a high level of atmospheric ethylene (1,200 ppb). Ground studies conducted by exposing 'Super-Dwarf' wheat to ethylene just prior to anthesis resulted in manifestation of the same abnormalities observed in the space flight samples.

Environment, Controlled↗
PubMed2002

[Epidemiology of limb fractures].

To analyze age- and sex-specific frequencies of peripheral fractures, we used data from the third MONICA-Augsburg Survey (1994/95). The study comprises 2404 male and 2450 female participants (age 25 to 74 years) who were questioned regarding fracture history. We investigated fracture prevalence, age-specific incidence rates, and the circumstances under which the fractures occurred. The age-standardized, cumulative fracture prevalence among men (m) 25 to 74 years of age was 45% and among women (w) of the same age 31%. Fracture prevalence among women was more than 10% lower than among men in the younger age groups (age 25 to 64 years), but after an significant increase in the 65 to 74-year-olds the fracture prevalence corresponded to that of men (m: 42%, w: 40%). A peak of incidence rates was found among men at age 15-24 (overall incidence rate: 2017 fractures/100,000 person-years) and at age 45-54 (overall incidence rate: 1640 fractures/100,000 PY), respectively, and among women at age 65-74 (overall incidence rate: 3214 fractures/100,000 PY). The prevalence of self-reported osteoporosis (age 25 to 74 years) was higher in women (7%) than in men (1%). Falls caused 43% (w: 59%, m: 33%) of all fractures, external violence 40% (m: 47%, w: 29%), and sports activities 15% (m: 18%, w: 10%). Further investigation of risk factors related to fractures can contribute to the development of specific preventive measures in that field. In the future, the prevention and efficient treatment of an existing or an often undiagnosed osteoporosis and also the prevention of falls in elderly persons should be an important public health concern.

Adolescent↗
PubMed2002

Do siblings of myocardial infarction patients have a specific management of hypertension?

The aim of this study was to determine whether the management of hypertension differs between siblings of myocardial infarction patients and the general population. Siblings aged 35 to 74 years, unaffected by myocardial infarction, were drawn from the Augsburg Family Heart Study, conducted in 1996-1997 in southern Germany (n = 524). The reference group consisted of participants of the third MONICA population-based survey conducted in 1994-1995 in the same area, who were aged 35 to 74 years and also unaffected by myocardial infarction (n = 3802). Prevalence, awareness, treatment and control of hypertension (defined by blood pressure > or = 140/90 mm Hg or use of antihypertensive medication) were compared between the two groups. The result was that the prevalence of hypertension was higher in the siblings (men: age-adjusted OR = 1.31, 95% CI: 0.99-1.75; women: age-adjusted OR = 1.83, 95% CI: 1.39-2.41). Male hypertensive siblings were more often aware and treated for hypertension than male hypertensives of the reference group whereas the level of awareness and treatment was comparable between female hypertensives of the two groups. In both genders, no difference in the degree of control was shown between hypertensives of the two groups. In conclusion the siblings and their physicians should pay more attention to the family history of myocardial infarction in order to improve the management of hypertension in this high risk group.

Adult↗
PubMed2001

[Ten-year trend of analgesic drug use (1984 to 1995): results of three MONICA-based surveys in Augsburg)].

BACKGROUND AND OBJECTIVE: Use of drugs, especially analgesics, is thought to be responsible for the rising cost of the health system in Germany, but there are no published population data for analgesic intake in Germany. Data derived from the three MONICA surveys (Monitoring of Trends and Determinants of Cardiovascular Diseases) in Augsburg and its adjacent districts were analysed for the prevalence of analgesic usage between 1984 and 1995 (the first such survey for Germany). PATIENTS AND METHODS: A total of 5,899 males and 6,005 females (aged 25-64 years), representative of the population, were selected and examined in 1984/85, 1989/90 and 1994/95 (participation rate of those selected, 75-79%). Using a standardized protocol, all analgesic drugs taken during the previous 7 days were recorded and classified. The analysis was standardized for age and classified according to sex. RESULTS: Strong analgesics were not significantly used under the ambulatory conditions of this survey and were therefore excluded from the analysis. Intake prevalence of mild to moderately strong analgesics varied from 5.9-8.9% in males and 9.9-13.4% in females. Prevalence was significantly at its lowest in 1989/90, but similar at the beginning and end of the 10-year period. Changes in prevalence of analgesic usage were similar to those of on-demand medication. Salicylic acid preparations containing higher dosages of the active ingredient were the drugs most commonly used, followed by aniline preparations, heteroaryl- as well as aryl-acetate and propionic acid derivates, pyrazole derivates, oxicam and anthranylic acid derivates. CONCLUSION: The prevalence of taking mild of moderately strong analgesics was at a similar low level at the beginning and end of the 10-year period.

Analgesia↗
PubMed2001

Assessing hypertension management in the community: trends of prevalence, detection, treatment, and control of hypertension in the MONICA Project, Augsburg 1984-1995.

OBJECTIVE: To assess trends in prevalence and detection, treatment and control of hypertension in a German population between 1984 and 1995. SETTING AND PARTICIPANTS: Independent random samples of the population were examined in cross-sectional surveys with identical methods in 1984/85 (age range 25 to 64 years, n = 4022 participants), 1989/90 (age range 25 to 74 years, n = 4940) and 1994/95 (age range 25 to 74 years, n = 4856). MAIN OUTCOME MEASURES: Prevalence of hypertension and proportions of hypertensives detected, treated and controlled. Hypertension was defined as blood pressure above 140/90 mm Hg or taking antihypertensive medication. RESULTS: The prevalence of hypertension did not change significantly over the 10 years (25--64 years, age-standardised 1984/85: 37.8% in men and 24.6% in women; 1994/95: 39.3% and 24.8%, respectively). Rates of detection, treatment and control of hypertension did not change much either. Of all hypertensives in 1994/95, 54% were detected in men and 64% in women, the treatment rates were 23% and 32%, and the proportions of those with controlled hypertension (below 140/90 mm Hg with treatment) were as low as 7% and 13%, respectively. Rates were higher in the older age groups, however, control rates never exceeded 20% at any age. CONCLUSIONS: Despite considerable changes in the pharmacological treatment of hypertension there was a disappointing stagnation with regard to the management of this important risk factor in the community. The reasons for this unfavourable trend need clarification and appropriate public health action. Journal of Human Hypertension (2001) 15, 27-36

Adult↗
PubMed2001

Microalbuminuria, central adiposity and hypertension in the non-diabetic urban population of the MONICA Augsburg survey 1994/95.

OBJECTIVE: Microalbuminuria is a renal marker of general vascular endothelial damage and early atherosclerosis with adverse prognostic implications. Microalbuminuria is associated with diabetes, insulin resistance, central adiposity and hypertension. We evaluated the degree of the association of components of the metabolic syndrome with microalbuminuria in a subsample of a non-diabetic study population. DESIGN: Men and women aged 25-74 living in the city of Augsburg, Germany, were interviewed and examined in a standardised manner at a population-based survey conducted in 1994/95. Persons with a history of diabetes or HbA1c level > or = 7% were excluded. OUTCOME: Albumin and creatinine were determined quantitatively in a spot urine and defined as microalbuminuria via an albumin/creatinine ratio between 30 and 299 mg/g. RESULTS: Among 920 men and 879 women, the age- standardised prevalence of microalbuminuria was 8.0% and 7.5%, respectively. While a graded, positive increase in prevalence of microalbuminuria across quintiles of waist-to-hip (WHR) was observed in non-hypertensive men and women, microalbuminuria was uniformly high among hypertensives. Multivariate logistic regression models showed that central adiposity (OR 3.3) or hypertension (OR 4.0) alone significantly increased the odds of microalbuminuria while their joint presence (OR 3.6) did not add to the occurrence of microalbuminuria. While obesity was not associated with microalbuminuria once central adiposity was taken into account, elevated percent body fat remained associated with microalbuminuria. CONCLUSIONS: Signs of early endothelial dysfunction as manifested as microalbuminuria are strongly and independently associated with central adiposity and should be considered in the context of the metabolic or insulin resistance syndrome.

Adult↗
PubMed2001

Cellular expression and functional characterization of four hyperpolarization-activated pacemaker channels in cardiac and neuronal tissues.

Hyperpolarization-activated cation currents (I(h)) have been identified in cardiac pacemaker cells and a variety of central and peripheral neurons. Four members of a gene family encoding hyperpolarization-activated, cyclic nucleotide-gated cation channels (HCN1--4) have been cloned recently. Native I(h) currents recorded from different cell types exhibit distinct activation kinetics. To determine if this diversity of I(h) currents may be caused by differential expression of HCN channel isoforms, we investigated the cellular distribution of the transcripts of HCN1--4 in the murine sinoatrial node, retina and dorsal root ganglion (DRG) by in situ hybridization. In the sinoatrial node, the most prominently expressed HCN channel is HCN4, whereas HCN2 and HCN1 are detected there at moderate and low levels, respectively. Retinal photoreceptors express high levels of HCN1, whereas HCN2, 3 and 4 were not found in these cells. In DRG neurons, the dominant HCN transcript is HCN1, followed by HCN2. We next determined the functional properties of recombinant HCN1--4 channels expressed in HEK293 cells. All four channel types gave rise to I(h) currents but displayed marked differences in their activation kinetics. Our results suggest that the heterogeneity of native I(h) currents is generated, at least in part, by the tissue-specific expression of HCN channel genes.

Animals↗
PubMed2001

Comparative floral development of Mir-grown and ethylene-treated, earth-grown Super Dwarf wheat.

To study plant growth in microgravity, we grew Super Dwarf wheat (Triticum aestivum L.) in the Svet growth chamber onboard the orbiting Russian space station, Mir, and in identical ground control units at the Institute of BioMedical Problems in Moscow, Russia. Seedling emergence was 56% and 73% in the two root-module compartments on Mir and 75% and 90% on earth. Growth was vigorous (produced ca. 1 kg dry mass), and individual plants produced 5 to 8 tillers on Mir compared with 3 to 5 on earth-grown controls. Upon harvest in space and return to earth, however, all inflorescences of the flight-grown plants were sterile. To ascertain if Super Dwarf wheat responded to the 1.1 to 1.7 micromoles mol-1 atmospheric levels of ethylene measured on the Mir prior to and during flowering, plants on earth were exposed to 0, 1, 3, 10, and 20 micromoles mol-1 of ethylene gas and 1200 micromoles mol-1 CO2 from 7 d after emergence to maturity. As in our Mir wheat, plant height, awn length, and the flag leaf were significantly shorter in the ethylene-exposed plants than in controls; inflorescences also exhibited 100% sterility. Scanning-electron-microscopic (SEM) examination of florets from Mir-grown and ethylene-treated, earth-grown plants showed that development ceased prior to anthesis, and the anthers did not dehisce. Laser scanning confocal microscopic (LSCM) examination of pollen grains from Mir and ethylene-treated plants on earth exhibited zero, one, and occasionally two, but rarely three nuclei; pollen produced in the absence of ethylene was always trinucleate, the normal condition. The scarcity of trinucleate pollen, abrupt cessation of floret development prior to anthesis, and excess tillering in wheat plants on Mir and in ethylene-containing atmospheres on earth build a strong case for the ethylene on Mir as the agent for the induced male sterility and other symptoms, rather than microgravity.

Carbon Dioxide↗
PubMed2001

Effects of air pollution on blood pressure: a population-based approach.

OBJECTIVES: This analysis assessed the association between blood pressure, meteorology, and air pollution in a random population sample. METHODS: Blood pressure measurements of 2607 men and women aged 25 to 64 years who participated in the Augsburg Monitoring of Trends and Determinants in Cardiovascular Disease survey were analyzed in association with 24-hour mean concentrations of air pollutants. RESULTS: During the air pollution episode in Europe in January 1985, an association between blood pressure and air pollution was observed, which disappeared after adjustment for meteorology. Continuous concentrations of total suspended particulates and sulfur dioxide were associated with an increase in systolic blood pressure of 1.79 mm Hg (95% confidence interval [CI] = 0.63, 2.95) per 90 micrograms/m3 total suspended particulates and 0.74 mm Hg (95% CI = 0.08, 1.40) per 80 micrograms/m3 sulfur dioxide. In subgroups with high plasma viscosity levels and increased heart rates, systolic blood pressure increased by 6.93 mm Hg (95% CI = 4.31, 9.75) and 7.76 mm Hg (95% CI = 5.70, 9.82) in association with total suspended particulates. CONCLUSIONS: The observed increase in systolic blood pressure associated with ambient air pollution could be related to a change in cardiovascular autonomic control.

Adult↗
PubMed2000

A single histidine residue determines the pH sensitivity of the pacemaker channel HCN2.

Hyperpolarization-activated cyclic nucleotide-gated (HCN) cation channels control the rhythmic activity of heart and neuronal networks. The activation of these channels is regulated in a complex manner by hormones and neurotransmitters. In addition it was suggested that the channels may be controlled by the pH of the cytosol. Here we demonstrate that HCN2, a member of the HCN channel family, is directly modulated by the intracellular pH in the physiological range. Protons inhibit HCN2 channels by shifting the voltage dependence of channel activation to more negative voltages. By using site-directed mutagenesis, we have identified a single histidine residue (His-321) localized at the boundary between the voltage-sensing S4 helix and the cytoplasmic S4-S5 linker of the channel that is a major determinant of pH sensitivity. Replacement of His-321 by either arginine, glutamine, or glutamate results in channels that are no longer sensitive to shifts in intracellular pH. In contrast, cAMP-mediated modulation is completely intact in mutant channels indicating that His-321 is not involved in the molecular mechanism that controls modulation of HCN channel activity by cyclic nucleotides. Because His-321 is conserved in all four HCN channels known so far, regulation by intracellular pH is likely to constitute a general feature of both cardiac and neuronal pacemaker channels.

Cell Line↗
PubMed2000

Mutations in the S4 domain of a pacemaker channel alter its voltage dependence.

In an attempt to study the functional role of the positively charged amino acids present in the S4 segment of hyperpolarization-activated cyclic nucleotide-gated cation (HCN) channels, we have introduced single and sequential amino acid replacements throughout this domain in the mouse type 2 HCN channel (mHCN2). Sequential neutralization of the first three positively charged amino acids resulted in cumulative shifts of the midpoint voltage activation constant towards more hyperpolarizing potentials. The contribution of each amino acid substitution was approximately -20 mV. Amino acid replacements to neutralize either the first (K291Q) or fourth (R300Q) positively charged amino acid resulted in the same shift (about 20 mV) towards more hyperpolarized potentials. Replacing the first positively charged amino acid with the negatively charged glutamic acid (K291E) produced a shift of approximately -50 mV in the same direction. None of the above amino acid substitutions had any measurable effect on the time course of channel activation. This suggests that the S4 domain of HCN channels critically controls the voltage dependence of channel opening but is not involved in regulating activation kinetics. No channel activity was detected in mutants with neutralization of the last six positively charged amino acids from the S4 domain, suggesting that these amino acids cannot be altered without impairing channel function.

Amino Acid Sequence↗
PubMed1999

Increases in heart rate during an air pollution episode.

This paper assesses whether air pollution increases resting heart rates in 2,681 men and women aged 25-64 years who participated in the MONICA (monitoring of trends and determinants in cardiovascular disease) Augsburg cohort. Increases in heart rate were observed during the air pollution episode in January 1985 compared with non-episode days adjusted for cardiovascular risk factors and meteorologic parameters. Consistently, heart rates were also elevated at high concentrations of sulfur dioxide, total suspended particulates, or carbon monoxide. Acceleration in heart rates indicates an altered autonomic control of the heart in association with air pollution, which may contribute to the observed health effects in association with air pollution.

Adult↗
PubMed1999

Two pacemaker channels from human heart with profoundly different activation kinetics.

Cardiac pacemaking is produced by the slow diastolic depolarization phase of the action potential. The hyperpolarization-activated cation current (If) forms an important part of the pacemaker depolarization and consists of two kinetic components (fast and slow). Recently, three full-length cDNAs encoding hyperpolarization-activated and cyclic nucleotide-gated cation channels (HCN1-3) have been cloned from mouse brain. To elucidate the molecular identity of cardiac pacemaker channels, we screened a human heart cDNA library using a highly conserved neuronal HCN channel segment and identified two cDNAs encoding HCN channels. The hHCN2 cDNA codes for a protein of 889 amino acids. The HCN2 gene is localized on human chromosome 19p13.3 and contains eight exons spanning approximately 27 kb. The second cDNA, designated hHCN4, codes for a protein of 1203 amino acids. Northern blot and PCR analyses showed that both hHCN2 and hHCN4 are expressed in heart ventricle and atrium. When expressed in HEK 293 cells, either cDNA gives rise to hyperpolarization-activated cation currents with the hallmark features of native If. hHCN2 and hHCN4 currents differ profoundly from each other in their activation kinetics, being fast and slow, respectively. We thus conclude that hHCN2 and hHCN4 may underlie the fast and slow component of cardiac If, respectively.

Biological Clocks↗
PubMed1999

Population trends in antihypertensive drug use: results from the MONICA Augsburg Project 1984 to 1995.

Trends in antihypertensive drug use were assessed among 25- to 64-year-old participants of three independent surveys of the MONICA Augsburg region in 1984/85, 1989/90, and in 1994/95. Despite constant prevalences of hypertension, the percentage of hypertensives taking medication increased over the study period. The latter was mainly due to significant rises in antihypertensive monotherapy. By contrast, the use of combination treatments with two or more agents remained constant; however, although combinations composed of only two drugs were taken more often in 1995, those with three or more agents and fixed-dose preparations decreased substantially. Beta-blockers were most frequently, and with a rising tendency, taken as antihypertensive monotherapy. Newer drug classes like calcium channel blockers and ACE-inhibitors were introduced as monotherapy more hesitantly. Diuretics persisted as the basis of antihypertensive combination therapy. The use of combination therapies containing obsolete drugs, like reserpine, declined significantly with corresponding increases in drug combinations of, in particular, calcium channel blockers or ACE-inhibitors. We conclude that monotherapies account for most of the rising antihypertensive treatment rates and probably reflect intensified therapy of borderline hypertensives. The trends in antihypertensive drug classes and treatment regimens reflect a less rapid adoption of novel therapeutic concepts but a fairly close adherence to national and international guidelines.

Adult↗
PubMed1998

Ultraflexible vesicles, Transfersomes, have an extremely low pore penetration resistance and transport therapeutic amounts of insulin across the intact mammalian skin.

New vehicles for the non-invasive delivery of agents are introduced. These carriers can transport pharmacological agents, including large polypeptides, through the permeability barriers, such as the intact skin. This capability depends on the self-regulating carrier deformability which exceeds that of the related but not optimized lipid aggregates by several orders of magnitude. Conventional lipid suspensions, such as standard liposomes or mixed lipid micelles, do not mediate a systemic biological effect upon epicutaneous applications. In contrast to this, the properly devised adaptable carriers, when administered on the intact skin, transport therapeutic amounts of biogenic molecules into the body. This process can be nearly as efficient as an injection needle, as seen from the results of experiments in mice and humans with the insulin-carrying vesicles. The carrier-mediated transcutaneous insulin delivery is unlikely to involve shunts, lesions or other types of skin damage. Rather than this, insulin is inferred to be transported into the body between the intact skin cells with a bio-efficiency of at least 50% of the s.c. dose action.

Administration, Cutaneous↗
PubMed1998

[Family status and social integration as predictors of mortality: a 5-year follow-up study of 55- to 74-year-old men and women in the Augsburg area].

The relation between marital status, social integration and the mortality from all causes was examined in a population based cohort study. The 5-year-cohort consisted of 1,030 men and 957 women, aged 55-74 years who participated in the second MONICA Survey Augsburg, F.R.G., 1989/90 (MONICA = Monitoring of trends and determinants of cardiovascular disease). They were followed for mortality until 1995. Altogether 120 men and 45 women had died. Social integration was measured by an index of social ties. The index of social ties examined in these analyses includes (a) presence of a spouse, (b) number of close friends and relatives, (c) reported contact with close friends and relatives. Age standardized mortality rates (per 10,000 person years) were computed for men and women. Sex-specific Cox-proportional hazard models were used and hazard rate ratios (HRR) were calculated adjusting for age, hypertension, cigarette smoking, cholesterol, drinking alcohol, number of chronic diseases and self-reported health. Mortality rates were higher for men who were living alone (437.3) than for married men (235.3). Respectively in women the rates were 121.6 compared to 80.7. After controlling for age and self-reported health a HRR of 1.5 (95% CI: 1.0-2.4) was observed for single, divorced or widowed men and a HRR of 1.6 (95% CI: 0.8-3.0) for women living alone. Low mortality rates were observed in people with many social ties (men: 180.1, women: 29.9). Mortality rates of people who gave no informations about social ties (men: 349.5, women: 124.9) were similar to those who had only few social ties (men: 321.1, women: 132.5). The findings showed that people with few social ties were more likely to die in the follow-up period than those with more extensive contacts. After adjusting for age and self-reported health the HRR for those with few ties compared to those with many social ties were 1.6 (95% CI: 1.1-2.5) for men and 2.7 (95% CI: 1.1-6.6) for women. Similar results were found for people who gave no informations about their social ties (men: HRR = 1.4, 95% CI: 0.9-2.3; women: HRR = 2.6, 95% CI: 1.0-6.9). Social relationships were shown to be important predictors of mortality in elderly women and men. These findings confirm the need for further research, which enables to take steps against high mortality of the social isolated elderly.

Aged↗