Search PubMed⌕ Search

Biomedical subjects

K Huber

Publications and source records attributed to K Huber.

At least 19 recordsLinked to original sources

Respiratory burst as a biomarker for stress responses.

A module for the detection of immunotoxic events within the test system Triple-Lux to be used during spaceflights was developed. It is based on the production of reactive oxygen species within the respiratory burst during phagocytosis or after stimulation of the phagocytes with phorbol 12-myristate 13-acetate (PMA). For this purpose, luminol-dependent chemiluminescence was measured. The assays were carried out with polymorphonuclear leukocytes purified from sheep peripheral blood. The influence of hydrocortisone and Cd2+ on the respiratory burst in polymorphonuclear leukocytes was assayed. Hydrocortisone in concentrations between 10(-4) and 10(-9) mol/liter showed an immunostimulating effect after PMA treatment. An immunosuppressive effect was observed for Cd2+ in concentrations between 10(-4) and 10(-7) mol/liter. Cryoconservation, which has often been critical for primary cells, can be accomplished without any subsequent loss of function by freezing the cells in dimethyl sulfoxide-containing medium.

Animals↗

Shrinking of anionic polyacrylate coils induced by Ca2+, Sr2+ and Ba2+: a combined light scattering and ASAXS study.

Anionic polyacrylate chains (NaPA) form precipitates if alkaline earth cations are added in stoichiometric amounts. Accordingly, precipitation thresholds were established for three different alkaline earth cations Ca(2+), Sr(2+) and Ba(2+). Close to the precipitation threshold, the NaPA chains significantly decrease in size. This shrinking process was followed by means of combined static and dynamic light scattering. Intermediates were generated by varying the ratio [MCl(2)]/[NaPA] with M denoting the respective alkaline earth cation. All experiments were performed at an inert salt level of 0.01M NaCl. Similar coil-to-sphere transitions could be observed with all three alkaline earth cations Ca(2+), Sr(2+) and Ba(2+). Based on these findings, supplementary conventional and anomalous small-angle X-ray scattering experiments using selected intermediates close to the precipitation threshold of SrPA were performed. The distribution of Sr counterions around the polyacrylate chains in aqueous solution provided the desired scattering contrast. Energy-dependent scattering experiments enabled successful separation of the pure-resonant terms, which solely stem from the counterions. The Sr(2+) scattering roughly reflects the monomer distribution of the polyacrylate chains. Different ratios of the concentrations of [ SrCl(2)]/[NaPA] revealed dramatic changes in the scattering curves. The scattering curve at the lowest ratio indicated an almost coil-like behaviour, while at the higher ratios the scattering curves supported the model of highly contracted polymer chains. Most of X-ray scattering experiments on intermediate states revealed compact structural elements which were significantly smaller than the respective overall size of the NaPA particles.

Acrylic Resins↗

The effects of dietary phosphorus deficiency on surface pH and membrane composition of the mucosa epithelium in caprine jejunum.

In ruminants, the uptake of inorganic phosphate (P(i)) across the intestinal mucosa epithelium by Na-dependent and Na-independent mechanisms is a main regulatory factor in P homeostasis. The aim of the study was to elucidate to which extent Na-independent mechanisms, including pH effects or composition of mucosal brush-border membranes, could be involved in positive stimulation of P(i) absorptive processes seen under the P deficient condition. Therefore, luminal, surface and intracellular pH of the jejunal epithelial cells in control and P depleted goats were compared and biochemical analyses of membrane phospholipids in the apical membrane of the jejunal epithelium were performed. Dietary P depletion resulted in decreased plasma P(i) levels. While pH in jejunal ingesta was not significantly changed, P depletion resulted in a significantly lower surface pH in the crypt region compared to control animals (7.62 +/- 0.02 vs. 7.77 +/- 0.04, n = 4, P < 0.01). Inhibition of apical Na(+)/H(+)-exchange resulted in an increase of the jejunal surface pH in P depleted animals by 0.07 +/- 0.01 (n = 6, P < 0.01) and 0.05 +/- 0.01 (n = 6, P < 0.01) for the villus and the crypt region, respectively. This increase were inversely correlated with the initial surface pH prior to inhibition. In contrast to surface pH, intracellular pH of the jejunal epithelium and the phospholipid composition of the apical jejunal membrane were not affected by P depletion. Although the data suggest the existence of a Na(+)/H(+)-exchange mechanism at the luminal surface of goat jejunum they do not support the hypothesis that adaptational processes of active P(i) absorption from goat jejunum in response to low dietary P could be based on "non P(i) transporter events".

Animals↗

Statins decrease TNF-alpha-induced osteoprotegerin production by endothelial cells and smooth muscle cells in vitro.

Recent reports have implicated osteoprotegerin (OPG) in cardiovascular disease processes. Endothelial and smooth muscle cells produce OPG and its expression in these cells is upregulated by inflammatory mediators. Statins, which besides their lipid lowering properties have various vasculoprotective effects, have been shown to regulate OPG expression in osteoblasts. We investigated whether statins affect the expression of OPG in human endothelial and smooth muscle cells. Using an ELISA we could demonstrate that statins reduce tumor necrosis factor-alpha (TNF-alpha)-induced OPG production in cultured human endothelial cells and smooth muscle cells. Atorvastatin also downregulated interleukin-1alpha (IL-1alpha)-induced OPG production in endothelial cells. A significant reduction of TNF-alpha-induced OPG was seen when statins were used in the nanomolar range. These results were confirmed at the level of specific mRNA expression by real-time-PCR. Using LDH leakage as a marker of cell damage we show that cell viability was not affected by statins at concentrations used in our study. The effect of statins on TNF-alpha-induced OPG production was reversed by mevalonate and geranyl-geranyl pyrophosphate at the level of protein production and at the level of mRNA expression, suggesting that it was brought about by inhibition of the mevalonic acid pathway and protein prenylation. Through our results we have added OPG to the list of molecules whose TNF-alpha-induced upregulation is counteracted by statins. If such an effect is also operative in the in vivo setting, one could postulate a role for statins in the modulation of cardiovascular disease processes possibly regulated by OPG.

Base Sequence↗

Nuclear electric quadrupole moments of Rb from the hyperfine spectrum of RbF.

The molecular beam electric resonance technique has been used to examine the hyperfine spectrum of RbF. The Rb nuclear electric quadrupole interaction, the spin-rotation interactions, and tensor and scalar spin-spin interactions have been measured for both Rb isotopes, including their dependence on vibrational and rotational states. Transition frequencies have been determined to a precision of better than 1 Hz in many cases. The magnetic interactions in the two isotopomers are consistent with what is expected from the known masses and magnetic dipole moments. In the case of the Rb nuclear electric quadrupole interaction, adjustments have been made for a small isotopomer shift, and for the ratio of the effective nuclear electric quadrupole moments, Q(87Rb)Q(85Rb) = 0.483 830 1+/-0.000 001 8. The effective quadrupole interaction includes a pseudoquadrupole interaction that may be significant at this level of precision, but cannot be distinguished experimentally.

Journal Article↗

Two-year evaluation of a new nano-ceramic restorative material.

The purpose of this prospective study was to evaluate the clinical performance of a new restorative material (Ceram.X) in combination with a new primer-adhesive (K-0127). One operator placed two Class I or II restorations in molars of 43 patients. One molar was restored with Ceram.X/K-0127, the other one with Tetric Ceram/Syntac Classic. At baseline, after 1 and 2 years, the restorations were evaluated by one evaluator using modified Ryge's criteria. After 2 years, 31 patients were examined. One Ceram.X-restoration had to be removed for root canal treatment due to pulpitis. Thus, failure rate of Ceram.X was 3.2% and of Tetric Ceram, 0%. In both groups, no sensitivity, no recurrent caries, and no changes in surface texture were recorded after 2 years. One restoration in each group showed slight changes in color stability (score B). Marginal discoloration (score B) was found concerning three Ceram.X-restorations (10.0%) and two Tetric Ceram-restoration (6.5%). Marginal integrity was score B for four Ceram.X-restorations (13.3%) and for four Tetric Ceram-restorations (12.9%). No statistically significant differences were found (p>0.05). After 2 years of clinical service, 96.8% of Ceram.X/K-0127 and 100% of Tetric Ceram/Syntac Classic restorations were in place and performed clinically well.

Ceramics↗

No evidence for a direct role of Helicobacter pylori and Mycoplasma pneumoniae in carotid artery atherosclerosis.

BACKGROUND: That infections with certain pathogens, by initiating an inflammatory response, may contribute to the development of atherosclerosis is suggested by clinical and experimental evidence. AIM: To analyse atherosclerotic plaques of the carotid artery, samples of apparently healthy greater saphenous veins and circulating leucocytes from the same individual patients for the presence of Helicobacter pylori and Mycoplasma pneumoniae. METHODS: Samples from 36 patients undergoing carotid endarterectomy for symptomatic carotid artery stenosis were analysed by polymerase chain reaction for the presence of DNA specific for H. pylori and M. pneumoniae. IgG antibody titres against H. pylori and M pneumoniae and plasma levels of soluble E-selectin, soluble intercellular adhesion molecule-1 and soluble vascular cell adhesion molecule-1 were determined. RESULTS: M. pneumoniae-specific DNA was detected in the atherosclerotic plaques of 13 of 36 (36.1%) patients, in the saphenous veins of 9 of 36 (25%) patients and in the leucocytes of 27 of 36 (75%) patients. No salient association was observed between the presence of M. pneumoniae-specific DNA in leucocytes and atherosclerotic plaques or veins. A marked correlation between the presence of M. pneumoniae in the respective specimens and the studied inflammatory markers or the presence of anti-M. pneumoniae antibodies was not observed. H. pylori-specific DNA could not be detected in the specimens tested. CONCLUSIONS: The absence of H. pylori and the random distribution of M. pneumoniae in tissue samples obtained from patients with symptomatic carotid artery stenosis do not support a role for these pathogens in the development of atherosclerosis due to a direct interaction of the bacteria with the vasculature.

Aged↗

Plant development scores from fixed-date photographs: the influence of weather variables and recorder experience.

In 1944, John Willis produced a summary of his meticulous record keeping of weather and plants over the 30 years 1913-1942. This publication contains fixed-date, fixed-subject photography taken on the 1st of each month from January to May, using as subjects snowdrop Galanthus nivalis, daffodil Narcissus pseudo-narcissus, horse chestnut Aesculus hippocastanum and beech Fagus sylvatica. We asked 38 colleagues to assess rapidly the plant development in each of these photographs according to a supplied five-point score. The mean scores from this exercise were assessed in relation to mean monthly weather variables preceding the date of the photograph and the consistency of scoring was examined according to the experience of the recorders. Plant development was more strongly correlated with mean temperature than with minimum or maximum temperatures or sunshine. No significant correlations with rainfall were detected. Whilst mean scores were very similar, botanists were more consistent in their scoring of developmental stages than non-botanists. However, there was no overall pattern for senior staff to be more consistent in scoring than junior staff. These results suggest that scoring of plant development stages on fixed dates could be a viable method of assessing the progress of the season. We discuss whether such recording could be more efficient than traditional phenology, especially in those sites that are not visited regularly and hence are less amenable to frequent or continuous observation to assess when a plant reaches a particular growth stage.

Climate↗

Adaptation of epithelial sodium-dependent phosphate transport in jejunum and kidney of hens to variations in dietary phosphorus intake.

The objective of this study was to explore the homeostatic response of jejunal and renal epithelia regarding the inorganic phosphate (P(i)) transport capacities to variations in dietary total phosphorus (tP) supply in hens. Adaptive processes were determined by quantitative measures of intake and excretion, P(i) transport studies across brush border membranes, and semiquantitative detection of sodium-dependent phosphate transporters (NaPi II) based on mRNA expression in the jejunum and kidney. Twelve hens (4/group) were adapted to 3 tP feeding levels in a pair-fed manner (60 g/d): low P diet with 0.073% tP, medium P diet with 0.204% tP, and high P diet with 0.343% tP. Excretion was measured during the last 5 d of a 16-d feeding period. After slaughtering, jejunal mucosa and renal cortex were removed. Tissues were used for (32)P uptake studies in brush-border membrane vesicles by rapid filtration technique and NaPi II mRNA expression studies by northern analyses. Plasma P(i) concentrations were additionally measured. The NaPi II transporter mRNA could specifically be detected in chicken jejunum and kidney. Functional parameters of Na(+)-dependent P(i) transport indicated that these transporters were involved in chicken P(i) transport across the apical membranes of jejunal and renal epithelia. Increased tP intake resulted in an increased overall tP excretion. Correlating individual data from all animals by linear regression highlighted that the adaptive decrease of renal P(i) transport capacity and NaPi IIa mRNA expression was associated with an increase in plasma P(i) levels and resulted in a higher tP excretion. Jejunal P(i) transport capacity and NaPi IIb mRNA expression did not react to variations in dietary tP supply. In conclusion, the homeostatic response was mainly based on the adaptive capacity of the kidney in hens.

Acclimatization↗

Histomonas meleagridis in turkeys: dissemination kinetics in host tissues after cloacal infection.

Histomonas meleagridis is a flagellated protozoa causing histomoniasis, a disease of gallinaceous fowl. This disease is characterized by necrotic typhlitis, hepatitis, and high mortality, especially in turkeys. In an attempt to detect the progression of H. meleagridis in the turkey, birds were infected via the cloaca. Between d 0 and 19, a group of 4 turkeys was killed and autopsied every 3 d. Cecal and hepatic lesion scores were used to measure severity of infection. For each turkey, 15 tissue samples were taken. Another group of 3 infected turkeys were placed separately, and samples of cecal and intestinal stool were collected every 3 d. Samples were analyzed by PCR. For samples of cecal droppings, cecum, cecal content, rectum, proventriculus, and bursa of Fabricius, the number of birds detected as positive by PCR followed the evolution of the lesion scores. Within the liver, the parasite DNA was detected only in some severe lesions. The parasite DNA was also detected in duodenum, jejuno-ileum, spleen, heart, lungs, and brain samples. The parasite DNA was not detected in the blood, kidneys, pancreas, or muscle of the thigh. Results of the PCR were in agreement with the evolution of the clinical signs and of the cecal and liver lesions.

Animals↗

Fibrinolytic dysfunction in insulin-resistant women with previous gestational diabetes.

BACKGROUND: Women with a history of gestational diabetes (p-GDM) are at increased risk of developing type 2 diabetes mellitus (DM2) later in life, and therefore at increased risk for future cardiovascular disease. MATERIALS AND METHODS: Three months after delivery we investigated the plasma levels of plasminogen activator inhibitor type 1 (PAI-1), tissue plasminogen activator (t-PA), fibrinogen and von Willebrand factor (vWF) in 74 women with p-GDM and 20 healthy females with normal glucose tolerance during and after pregnancy, as well as the relation of fibrinolytic parameters to insulin resistance and glycaemic control. All women underwent an oral (OGTT) as well as an intravenous glucose tolerance test (FSIGT). Mathematical model analysis disclosed that 50% (n=37 each) of the p-GDM subjects had normal (NIS) or impaired (IIS) insulin sensitivity. Parameters of interest were determined using commercially available test systems. RESULTS: Women with p-GDM and IIS had significantly increased body fat mass (BFM) (P<or=0.001) compared with women with p-GDM and NIS and controls, whereas the waist to hip ratio (WHR) was similar in both p-GDM groups but was higher compared with the controls (P<or=0.001). Mean PAI-1 and t-PA as well as fasting and stimulated plasma concentrations of proinsulin, C-peptide and insulin were elevated, whereas the disposition index was lower in women with p-GDM and IIS compared with women with p-GDM and NIS and the controls (P<0.001). Plasma levels of fibrinogen and vWF did not differ between the groups. Obese women with IIS had higher PAI-1 levels than lean women with IIS (P<or=0.001). PAI-1 inversely correlated with the insulin sensitivity index (SI) but only in women with IIS (P<0.0001). On regression analysis, only fasting proinsulin and WHR remained significant independent predictors of PAI-1 elevation in IIS (P<or=0.0001 and P<or=0.001). The PAI-1/SI ratio was elevated in women with IIS independently of their glucose tolerance status (P<0.001 vs. NIS and controls). CONCLUSIONS: Plasminogen activator inhibitor type 1 is elevated in p-GDM women with IIS and depends on plasma proinsulin and abdominal obesity. An increase of the PAI-1/SI ratio further characterizes obese insulin-resistant p-GDM women who may be at risk for diabetes and angiopathy.

Adult↗

The complement component C5a induces the expression of plasminogen activator inhibitor-1 in human macrophages via NF-kappaB activation.

BACKGROUND: Atherosclerosis is considered to be a chronic inflammatory disorder. Activation of the complement cascade is a major aspect of chronic inflammatory diseases. Complement components were identified in atherosclerotic plaques, and a correlation between adverse events and C5a plasma levels was found. These findings support the notion that complement activation contributes to development and progression of atherosclerotic lesions. OBJECTIVES: We investigated whether complement components C3a and C5a regulate plasminogen activator inhibitor (PAI-1) in human macrophages. METHODS: Human monocyte-derived macrophages (MDM) and human plaque macrophages were cultured and incubated with the complement component C5a. RESULTS: C5a increased PAI-1 up to 11-fold in human MDM and up to 2.7-fold in human plaque macrophages. These results were confirmed at the mRNA level using real time-polymerase chain reaction. Pertussis toxin or anti-C5aR/CD88 antibody completely abolished the effect of recombinant human C5a on PAI-1 production, suggesting a role of the C5a receptor. Experiments with antitumor necrosis factor (TNF)-alpha antibodies and tiron showed that the effect of C5a was not mediated by TNF-alpha or oxidative burst. Furthermore C5a induced NF-kappaB binding to the cis element in human macrophages and the C5a-induced increase in PAI-1 was completely abolished by an NF-kappaB inhibitor. CONCLUSIONS: We conclude that C5a upregulates PAI-1 in macrophages via NF-kappaB activation. We hypothesize that - if operative in vivo- this effect could favor thrombus development and thrombus stabilization in the lesion area. On the other hand one could speculate that C5a-induced upregulation of PAI-1 in plaque macrophages could act as a defense mechanism against plaque destabilization and rupture.

Cells, Cultured↗

Relation between vascular risk factors and cognition at age 75.

OBJECTIVE: Recent trends in dementia research emphasize that not only cerebrovascular events but also vascular risk factors induce, favour or cause cognitive impairment and Alzheimer's disease. MATERIAL AND METHODS: We evaluated vascular risk factors (blood pressure, LDL cholesterol, HDL cholesterol, triglycerides, HbA1c, homocysteine, lipoprotein(a), fibrinogen, C-reactive protein and smoking habits) in a community-based cohort of 75-year-old individuals of two districts in Vienna (247 men, 359 women) and correlated these risk factors with overall cognition. RESULTS: Pathological vascular risk factors were found frequently in the age cohort. However, the expected associations between the Mini-Mental State Examination and any cardiovascular risk factors were missing. Only individuals with a positive history of smoking showed lower cognitive capacities. CONCLUSIONS: We assume that cognitive dysfunction in old age is connected to factors other than the known classical and novel risk factors for the development of cardiovascular disease.

Aged↗

Effect of barley and its amylopectin content on ruminal fermentation and nitrogen utilization in lactating dairy cows.

The effect of type of grain (corn vs. barley) and amylopectin content of barley grain (normal vs. waxy) on ruminal fermentation, digestibility, and utilization of ruminal ammonia nitrogen for milk protein synthesis was studied in a replicated 3 x 3 Latin square design trial with 6 lactating dairy cows. The experimental treatments were (proportion of dietary dry matter): CORN, 40% corn grain, NBAR, 30% normal Baronesse barley:10% corn grain, and WBAR, 30% high-amylopectin (waxy) Baronesse barley:10% corn grain. All grains were steam-rolled and fed as part of a total mixed ration. The NBAR and WBAR diets resulted in increased ruminal ammonia concentrations compared with CORN (8.2, 7.4, and 5.6 mM, respectively), but other ruminal fermentation parameters were not affected. Ruminal digestibility of dietary nutrients and microbial protein synthesis in the rumen were also not affected by diet. Corn grain had greater in situ effective ruminal dry matter degradability (62.8%) than the barley grains (58.2 and 50.7%, respectively), and degradability of the normal barley starch was greater than that of the waxy barley (69.3 and 58.9%, respectively). A greater percentage of relative starch crystallinity was observed for the waxy compared with the normal barley grain. Total tract apparent digestibility of dry matter and organic matter were decreased by WBAR compared with CORN and NBAR. Total tract starch digestibility was greater and milk urea nitrogen content was lower for CORN compared with the 2 barley diets. In this study, the extent of processing of the grain component of the diet was most likely the factor that determined the diet responses. Minimal processing of barley grain (processing indexes of 79.2 to 87.9%) reduced its total tract digestibility of starch compared with steam-rolled corn (processing index of 58.8%). As a result of the increased ammonia concentration and reduced degradability of barley dry matter in the rumen, the utilization of ruminal ammonia nitrogen for microbial protein synthesis was decreased with the barley diets compared with the corn-based diet. In this study, waxy Baronesse barley was less degradable in the rumen and the total digestive tract than its normal counterpart. The most likely reasons for these effects were the differences in starch characteristics and chemical composition, and perhaps the different response to processing between the 2 barleys.

Amylopectin↗

Cholinergic differentiation occurs early in mouse sympathetic neurons and requires Phox2b.

The generation of neurotransmitter identity in the autonomic nervous system is a classical model system to study the development of neuronal diversity. Analysis of the expression of genes coding for enzymes of noradrenaline biosynthesis in the sympathoadrenal system allowed the characterization of factors involved in the differentiation of the noradrenergic transmitter phenotype. The development of cholinergic properties in the autonomic system is less well understood. Here we show that expression of mRNAs for choline acetyltransferase (ChAT) and the vesicular acetylcholine transporter (VAChT), both encoded by the cholinergic gene locus, is induced in mouse sympathetic ganglia at embryonic day 11 (E11). Positive cells amount to more than 50% of Phox2b-positive sympathetic cells at cervical levels. The proportion declines caudally, decreasing to approximately 20% of Phox2b-positive cells at lower thoracic levels. In the adrenal anlage, ChAT and VAChT mRNA are largely undetectable at E11 and E13. In mice homozygous for a mutational inactivation of the transcription factor Phox2b, ChAT and VAChT mRNA expression is absent from sympathetic ganglia. The data show that expression from the cholinergic gene locus is regulated differently in sympathetic neurons and adrenal chromaffin cells. Phox2b is required for development of cholinergic neurons but does not suffice to support cholinergic properties in chromaffin cells.

Animals↗

13N-ammonia rest/stress PET: folic acid improves global coronary vasoreactivity in coronary artery disease patients with normal or elevated homocysteine levels.

AIM: Hyperhomocysteinaemia (Hhcy) is known to be an independent risk factor for vascular disease. Coronary flow reserve (CFR) measured by positron emission tomography (PET) is a sensitive method to monitor the effects of pharmacologic interventions in Hhcy. We assessed coronary vascular reactivity by PET in patients with coronary artery disease (CAD) dependent on their homocysteine (Hcy) levels before and under high dose folic acid supplementation therapy (FAST). PATIENTS, METHODS: Twelve patients with CAD underwent rest/adenosine (13) N-ammonia PET for quantification of myocardial blood flow (MBF) and CFR before and after nine weeks FAST (10 mg/day). RESULTS: Folate levels increased from 21 +/- 6 to 210 +/- 34 microg/l (+900%, p < 0.0001) while Hcy levels decreased from 12.1 +/- 3.6 to 9.1 +/- 3.1 micromol/l ( - 25%; p < 0.01). Global resting MBF remained nearly unchanged after FAST, while stress MBF (from 2.61 +/- 0.93 to 3.25 +/- 1.15 ml/g/min; p = 0.05) and CFR (from 3.00 +/- 0.76 to 3.72 +/- 0.93 ml/g/min; p < 0.05; +24%) significantly increased in patients with normal and elevated Hcy levels (cut off 12 micromol/l). An inverse relation was found between Hcy and CFR (R = - 0.53; p = 0.08) and between Hcy and MBF at rest (R = - 0.62; p < 0.05) at baseline conditions, not persisting after FAST. CONCLUSION: Coronary vascular reactivity can be improved by FAST in patients with CAD and normal or elevated Hcy levels. FAST might lower an increased cardiovascular risk in CAD patients possibly by mechanisms that are not related to Hcy.

Aged↗

An anomaly in the isotopomer shift of the hyperfine spectrum of LiI.

A high-precision examination of the hyperfine spectrum of 6LiI in comparison with 7LiI shows a shift in the iodine nuclear electric quadrupole moment that cannot be accounted for by a model in which the electric field gradient at the iodine site is assumed to depend only upon the internuclear distance between Li and I. The other hyperfine interactions are consistent between the two isotopomers, including the previously reported electric hexadecapole interaction of the iodine nucleus.

Journal Article↗