PubMed Health⌕ Search

Biomedical subjects

H Brandl

Publications and source records attributed to H Brandl.

At least 19 recordsLinked to original sources
PubMed2005

Generation of bioaerosols during manual mail unpacking and sorting.

AIMS: The dynamics of bioaerosol generation in specific occupational environments where mail is manually unpacked and sorted was investigated. METHODS AND RESULTS: Total number of airborne particles was determined in four different size classes (0.3-0.5, 0.5-1, 1-5 and >5 microm) by laser particle counting. Time dependent formation of bioaerosols was monitored by culturing methods and by specific staining followed by flow cytometry. Besides handling of regular mail, specially prepared letters ('spiked letters') were added to the mailbags to deliberately release powdered materials from letters and to simulate high impact loads. These letters contained various dry powdered biological and nonbiological materials such as milk powder, mushrooms, herbs and cat litter. Regarding the four size classes, particulate aerosol composition before mail handling was determined as 83.2 +/- 1.0, 15.2 +/- 0.7, 1.7 +/- 0.4 and 0.04 +/- 0.02%, respectively, whereas the composition changed during sorting to 66.8 +/- 7.9, 22.3 +/- 3.6, 10.4 +/- 4.0 and 0.57 +/- 0.27%, respectively. Mail processing resulted in an increase in culturable airborne bacteria and fungi. Maximum concentrations of bacteria reached 450 CFU m(-3), whereas 270 CFU of fungi were detected. CONCLUSIONS: Indoor particle concentrations steadily increased during mail handling mostly associated with particles of diameters >1 microm. However, it was not possible to distinguish spiked letters from nonspiked by simple particle counting and CFU determinations. SIGNIFICANCE AND IMPACT OF STUDY: The dynamics of bioaerosol generation have to be addressed when monitoring specific occupational environments (such as mail sorting facilities) regarding the occurrence of biological particles.

Air Microbiology↗
PubMed2002

Effect of medium composition, flow rate, and signaling compounds on the formation of soluble extracellular materials by biofilms of Chromobacterium violaceum.

Biofilms of the homoserine-lactone-defective strain Chromobacterium violaceum CV026 were grown on silicone surfaces in a flow chamber. The effect of medium flow rate, different levels of N-butanoyl-homoserine lactone, and nutrients on biofilm activity was studied by quantifying the proteins and exopolysaccharides attached to the cells. To compare the effect of each of the three variables within a wide range, the experiments were designed as a full factorial search with three levels for each variable. Calculated contour plots demonstrated that N-acyl homoserine lactone is an important determinant of both the amount and the composition of the compounds excreted into the medium.

4-Butyrolactone↗
PubMed2002

[DRGs of musculoskeletal diseases: consequences for orthopaedics and accident surgery].

The introduction of the new prospective payment system for inpatient care entails considerable changes for hospitals in Germany. The Australian Refined Diagnosis Related Groups (AR-DRGs), which form the basis for the German system, give the chance to estimate the consequences and implications for the specialty of orthopaedic surgery in Germany. Our study aims at highlighting the most important musculoskeletal diagnoses and to provide an initial economic forecast for them. The comparison with Australian data gives hints for operative and conservative-rehabilitative orthopaedic departments in respect to potentials and focal points for the development of novel patient management tools. The success of orthopaedic departments will depend in the future much more than now on organisational and management issues.

Australia↗
PubMed1999

Heavy metal effects on beta-glucosidase activity influenced by pH and buffer systems.

Inhibition of beta-glucosidase activity by Cu(II), Zn(II) and Ni(II) was investigated as a function of pH and buffer type. Both factors were found to exert a strong effect on the activity of the enzyme. All three of the investigated heavy metals inhibited the enzyme activity in acetate buffer. At metal concentrations of 0.6 mM, Zn and Ni reduced the enzyme activity by 25-30% under optimal pH conditions (pH 5-5.2). Under the same conditions, Cu showed an even more pronounced inhibitory effect than Zn and Ni. In presence of 0.6 mM Cu, the enzyme activity was lowered by more than 90% in comparison to metal free systems. In contrast to these results, no enzyme inhibition was observed in citrate buffer, even in the presence of 1 mM Cu. The inhibition of beta-glucosidase activity by Cu increased with increasing pH. Inhibition by Zn and Ni was less pH-dependent in the observed pH range (pH 4-5.5). Copper caused a distinct shift in the pH optimum of enzyme activity, whereas this was not the case for Zn or Ni. The effects of buffer and pH on enzyme inhibition by Cu, Zn and Ni were successfully described using a chemical speciation model, based on the assumption that enzyme activity depends on the protonation of the amino acids at the reactive site and that enzyme activity is inhibited by complexation of the reactive sites by the heavy metal cations. The results show the importance of taking chemical conditions and speciation into account when investigating the effect of heavy metal cations on biological systems.

Buffers↗
PubMed1998

Development of a laboratory-scale leaching plant for metal extraction from fly ash by thiobacillus strains.

Semicontinuous biohydrometallurgical processing of fly ash from municipal waste incineration was performed in a laboratory-scale leaching plant (LSLP) by using a mixed culture of Thiobacillus thiooxidans and Thiobacillus ferrooxidans. The LSLP consisted of three serially connected reaction vessels, reservoirs for a fly ash suspension and a bacterial stock culture, and a vacuum filter unit. The LSLP was operated with an ash concentration of 50 g liter, and the mean residence time was 6 days (2 days in each reaction vessel). The leaching efficiencies (expressed as percentages of the amounts applied) obtained for the economically most interesting metal, Zn, were up to 81%, and the leaching efficiencies for Al were up to 52%. Highly toxic Cd was completely solubilized (100%), and the leaching efficiencies for Cu, Ni, and Cr were 89, 64, and 12%, respectively. The role of T. ferrooxidans in metal mobilization was examined in a series of shake flask experiments. The release of copper present in the fly ash as chalcocite (Cu(2)S) or cuprite (Cu(2)O) was dependent on the metabolic activity of T. ferrooxidans, whereas other metals, such as Al, Cd, Cr, Ni, and Zn, were solubilized by biotically formed sulfuric acid. Chemical leaching with 5 N H(2)SO(4) resulted in significantly increased solubilization only for Zn. The LSLP developed in this study is a promising first step toward a pilot plant with a high capacity to detoxify fly ash for reuse for construction purposes and economical recovery of valuable metals.

Journal Article↗
PubMed1996

A rapid method for the determination of metal toxicity to the biodegradation of water insoluble polymers.

A rapid and inexpensive test has been developed to investigate the influence of elevated heavy metal concentrations on the degradation of biodegradable plastics. Using an overlay agar technique it could be demonstrated that copper concentrations above 8 to 14 mg/L inhibit the degradation of powdered poly(3-hydroxybutyrate), (PHB), by Acidovorax delafieldii. This is the first study demonstrating the inhibiting influence of metals on the biodegradation of PHB.

Journal Article↗
PubMed1995

Biodegradation of cyclic and substituted linear oligomers of poly(3-hydroxybutyrate).

Cyclic oligo(3-hydroxybutyrate), oligo(3-HB), was synthesized and purified, resulting in oligolides that contained three to seven (R)-3-hydroxybutyrate units (triolides up to heptolides). In addition, linear 3-HB octamers obtained as either tert-butyl or methyl esters were substituted with different end groups at the hydroxy end. The hydroxy terminus was replaced by either a benzyloxy, trifluoroacetoxy, crotonyloxy (S)-3-hydroxybutyryloxy, or fluorenylmethylcarbonyloxy (FMOC) group. P(3-HB) hairpin loops occurred on the surface of certain regions of the polymer, especially of lamellar crystallites. Cyclic 3-HB oligomers provide a model system for these loops. It is assumed that they provide attachment points for the depolymerizing enzymes. All of the (R)-oligolides tested were degraded except the (R)-triolide. Triolides were not degraded, suggesting that enzymatic attack was prevented presumably by steric hindrance on the rigid ring system. Unsubstituted linear octamers were degraded. Biodegradation was prevented when the hydroxy terminus was protected by the FMOC group, but was not dependent on a free hydroxy terminal group; all other protecting groups did not prevent degradation. Substitution of the carboxy end of a methyl or tert-butyl ester group did not influence biodegradation.

Biodegradation, Environmental↗
PubMed1994

[Dependence of the sensitivity of the central visual field on hemoglobin-oxygen saturation].

Retinal function is very sensitive to changes in hemoglobin oxygen saturation. Characteristic ophthalmological symptoms of oxygen deficiency are: changes in color perception, visual field defect, eye flickering, reduction of visual acuity, seeing double images, defects in neural image interpretation. To test the dependency of changes in the central visual field sensitivity on different degrees of oxygen saturation, 48 probands (48 monocular tests) 20-50 years of age were examined in the altitude simulation chamber of the Aviation Medicine Institute of German Air Force at zero altitude (= 500 m) and at 10,000 ft (ca. 3,500 m height). Three types of experiments were performed: determination of abnormal quotient using a Heidelberg anomaloscope; determination of changes in color vision by saturated and disaturated panel D-15 test; determination of differences in light sensitivity for white, red, blue and green light by a threshold test using a Humphrey Field Analyzer (640) as perimeter. At zero level (500 m) hemoglobin-oxygen saturation was 97% +/- 1%. At 10,000 ft this value decreased to 83% +/- 3%. Hypoxic hypoxia caused neither significant AQ changes nor did it induce reproducible changes in color vision by the panel D-15 test. However, anoxia resulted in significant (P < 0.01) differences in light sensitivity in phototopic range.

Adult↗
PubMed1993

Indomethacin decreases viscosity of gallbladder bile in patients with cholesterol gallstone disease.

There is experimental evidence that inhibition of cyclooxygenase with nonsteroidal anti-inflammatory drugs may decrease cholesterol gallstone formation and mitigate biliary pain in gallstone patients. The mechanisms by which NSAIDs exert these effect are unclear. In a prospective, controlled clinical trial we examined the effects of oral indomethacin on the composition of human gallbladder bile. The study included 28 patients with symptomatic cholesterol or mixed gallstones. Of these, 8 were treated with 3 x 25 mg indomethacin daily for 7 days prior to elective cholecystectomy while 20 received no treatment and served as controls. Bile and tissue samples from the gallbladder were obtained during cholecystectomy. Indomethacin tissue levels in the gallbladder mucosa, as assessed by HPLC, were 1.05 +/- 0.4 ng/mg wet weight, a concentration known to inhibit effectively cyclooxygenase activity. Nevertheless, no differences between the treated and untreated groups were found in the concentrations of biliary mucus glycoprotein (0.94 +/- 0.27 versus 0.93 +/- 0.32 mg/ml) or total protein (5.8 +/- 0.9 versus 6.4 +/- 1.3 mg/ml), cholesterol saturation (1.3 +/- 0.2 versus 1.5 +/- 0.2), or nucleation time (2.0 +/- 3.0 versus 1.5 +/- 2.0 days). However, biliary viscosity, measured using a low-shear rotation viscosimeter, was significantly lower in patients receiving indomethacin treatment (2.9 +/- 0.6 versus 5.6 +/- 1.2 mPa.s; P < 0.02). In conclusion, in man oral indomethacin decreases bile viscosity without alteration of bile lithogenicity or biliary mucus glycoprotein content.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1993

[Extracapsular fluid dynamics and suction-irrigation cannulas. A model observation].

The ECCE technique often requires additional removal of lens residues remaining attached to the capsular bag after lens nucleus extraction. These residual lens substances in the form of a visco-elastic fluid are detached and removed by means of various types of irrigation-aspiration cannulas. During the aspiration process the elastic properties of the fluid are utilized. The aim of the investigations presented was modification and optimization of the geometric design of the irrigation-aspiration cannulas to improve the flow efficiency, facilitate the detachment and reduce the amount of rinsing fluid required. The fluid mechanic properties of various type of irrigation-aspiration cannulas were investigated and compared in an eye model. Some of the commercially available irrigation-aspiration cannulas give good results, being convenient to handle and functional. Our experimental data indicate that canalization of the rinsing fluids and the special location of the irrigation-aspiration openings will improve the flow-field. An adjustable valve has been developed, which enables safe aspiration/irrigation changeover if it should be necessary. Two models of the newly designed irrigation-aspiration probes are presented and discussed.

Biomechanical Phenomena↗
PubMed1991

[Vision test device: possibilities and limits of LCD technique].

An automatic visual acuity test examining visual acuity at 5 m distance is presented. An LCD screen with 400 x 640 pixel is used for graphic display. The Landolt rings are selected randomly. The test presented here complies well with the criteria of DIN 58220. Accuracy estimates for representation of the Landolt rings in raster graphics are discussed. With the method suggested, the testing of visual acuity, one of the most important tests in ophthalmological practice, is simplified and its reliability and results are improved. The method allows tests at short time intervals to trace the time dependency of visual acuity. Furthermore, the test may be delegated to support personnel.

Adolescent↗
PubMed1990

Plastics from bacteria and for bacteria: poly(beta-hydroxyalkanoates) as natural, biocompatible, and biodegradable polyesters.

Hence, PHB belongs to the family of poly(beta-hydroxyalkanoates), PHA, all of which are usually formed as intracellular inclusions under unbalanced growth conditions. Recently, it became of industrial interest to evaluate PHA polyesters as natural, biodegradable, and biocompatible plastics for a wide range of possible applications such as surgical sutures or packaging containers. For industrial applications, the controlled incorporation of repeating units with different chain lengths into a series of copolymers is desirable in order to produce polyesters with a range of material properties because physical and chemical characteristics depend strongly on the polymer composition. Such "tailormade" copolymers can be produced under controlled growth conditions, in that if a defined mixture of substrates for a certain type of microorganisms is supplied, a well defined and reproducible copolymer is formed.

Bacteria↗
PubMed1990

Different modulation of flash responses of fast and slow relay cells by aversive electrical brain stimulation.

Electrical activity of single neurons of the dorsal lateral geniculate nucleus of rats was recorded from stereotactically fixed animals. The neurons were classified as fast or slow ones, according to their response latency to electrical stimulation of the chiasma opticum. After this, the responses to diffuse flashes, to aversive electrical stimulation of the brain (ESB) and to a combination of both, brain stimulation immediately followed by a flash, were recorded. One week prior to testing, bipolar nichrom electrodes had been implanted into the tectotegmental region for the ESB, and their effectiveness was tested behaviorally. Out of 78 neurons 56 fast and 22 slow ones were found. Fast neurons have a significantly higher background activity than slow neurons. Both classes show a modulation of flash evoked responses by the ESB, although the ESB has nearly no effect on the spontaneous discharge frequency in any of the neurons. The influence on the flash response differs according to the cell class: the class of fast neurons is predominantly facilitated up to 1100 ms after the flash application, whereas the class of slow neurons is inhibited during this period. Later on (up to 2260 ms after flash) fast cells show no clear net effect, and slow cells were still slightly inhibited.

Animals↗
PubMed1989

Ability of the phototrophic bacterium Rhodospirillum rubrum to produce various poly (beta-hydroxyalkanoates): potential sources for biodegradable polyesters.

Studies have been carried out in order to optimize growth and culture conditions for the intracellular formation of poly(beta-hydroxyalkanoates) (PHA) in the phototrophic, purple, non-sulphur bacterium Rhodospirilum rubrum. Its potential to produce novel copolymers was investigated. Recently, it has become of industrial interest to evaluate these polyesters as potentially biodegradable plastics for a wide range of possible applications. On an industrial scale, the use of photosynthetic bacteria could harness sunlight as an energy source for the production of these materials. R. rubrum was grown anaerobically in the light on different linear and branched beta-hydroxycarboxylic acids and various n-alkanoic acids. Under nitrogen-limiting conditions a PHA content of up to 45% of cellular dry weight was detected. When R. rubrum was grown on different concentrations of various n-alkanoic acids, intracellular PHA production was detected on all acids used. In most of the cases, the storage polymer contained beta-hydroxybutyrate (HB) and beta-hydroxyvalerate (HV) monomer units. Grown on n-alkanoic acids with a chain length of four carbon atoms and more, R. rubrum produced a copolymer containing the beta-hydroxyhexanoate (HC) repeating unit in addition to the HB and HV monomer. Using beta-hydroxyheptanoic acid as the carbon source, a polyester which contained HB, HV, HC, and beta-hydroxyheptanoate was formed. These copolyesters represent a novel class of biodegradable thermoplastics. The results demonstrate the metabolic flexibility of R. rubrum to form many different types of polyesters which might substitute plastics synthesized from petrochemicals.

Ammonia↗
PubMed1988

Pseudomonas oleovorans as a Source of Poly(beta-Hydroxyalkanoates) for Potential Applications as Biodegradable Polyesters.

Pseudomonas oleovorans was grown in homogeneous media containing n-alkanoic acids, from formate to decanoate, as the sole carbon sources. Formation of intracellular poly(beta-hydroxyalkanoates) was observed only for hexanoate and the higher n-alkanoic acids. The maximum isolated polymer yields were approximately 30% of the cellular dry weight with growth on either octanoate or nonanoate. In most cases, the major repeating unit in the polymer had the same chain length as the n-alkanoic acid used for growth, but units with two carbon atoms less or more than the acid used as a carbon source were also generally present in the polyesters formed. Indeed, copolymers containing as many as six different types of beta-hydroxyalkanoate units were formed. The weight average molecular weights of the poly(beta-hydroxyalkanoate) copolymers produced by P. oleovorans ranged from 90,000 to 370,000. In spite of the higher cell yields obtained with octanoate and nonanoate, the use of hexanoate and heptanoate yielded higher-molecular-weight polymers. These copolyesters represent an entirely new class of biodegradable thermoplastics.

Journal Article↗
PubMed1987

Classification of geniculo-cortical relay cells of albino rat dorsal lateral geniculate nucleus by means of multivariate analysis.

It was tested if responses of geniculo-cortical relay (GCR-) cells in rat dorsal lateral geniculate nucleus (dLGN) to diffuse light flashes contain features permitting a separation of the cell population into slow and fast cells like the response latency to stimulation of optic chiasm (OX-latency). The location of neurons within the dLGN found additional consideration. Using hierarchical cluster analysis two clusters were obtained for on- as well as off-like neurons, which reflected to a high degree the classification into slow and fast cells by OX-latency. Two subgroups were detected in the cluster of slow cells. Multivariate discriminance analysis made it possible to separate the cell population into two classes. The latency of primary excitation to flash (primary inhibition for off-cells), the number of impulses in the first excitation peak (duration of inhibitory period) and the location of the cells within the dLGN were suited for this separation differing in 11 up to 17% from that achieved by OX-latency classification.

Animals↗