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Biomedical subjects

H Meier

Publications and source records attributed to H Meier.

At least 37 records · Page 2Linked to original sources
PubMed1996

Population analysis in a denitrifying sand filter: conventional and in situ identification of Paracoccus spp. in methanol-fed biofilms.

The microbial community of a denitrifying sand filter in a municipal wastewater treatment plant was examined by conventional and molecular techniques to identify the bacteria actively involved in the removal of nitrate. In this system, denitrification is carried out as the last step of water treatment by biofilms growing on quartz grains with methanol as a supplemented carbon source. The biofilms are quite irregular, having a median thickness of 13 to 20 microns. Fatty acid analysis of 56 denitrifying isolates indicated the occurrence of Paracoccus spp. in the sand filter. 16S rRNA-targeted probes were designed for this genus and the species cluster Paracoccus denitrificans-Paracoccus versutus and tested for specificity by whole-cell hybridization. Stringency requirements for the probes were adjusted by use of a formamide concentration gradient to achieve complete discrimination of even highly similar target sequences. Whole-cell hybridization confirmed that members of the genus Paracoccus were abundant among the isolates. Twenty-seven of the 56 isolates hybridized with the genus-specific probes. In situ hybridization identified dense aggregates of paracocci in detached biofilms. Probes complementary to the type strains of P. denitrificans and P. versutus did not hybridize to cells in the biofilms, suggesting the presence of a new Paracoccus species in the sand filter. Analysis using confocal laser scanning microscopy detected spherical aggregates of morphologically identical cells exhibiting a uniform fluorescence. Cell quantification was performed after thorough disruption of the biofilms and filtration onto polycarbonate filters. An average of 3.5% of total cell counts corresponded to a Paracoccus sp., whereas in a parallel sand filter with no supplemented methanol, and no measurable denitrification, only very few paracocci (0.07% of cells stained with 4',6-diamidino-2-phenylindole) could be detected. Hyphomicrobium spp. constituted approximately 2% of all cells in the denitrifying unit and could not be detected in the regular sand filter. This clear link between in situ abundance and denitrification suggests an active participation of paracocci and hyphomicrobia in the process. Possible selective advantages favoring the paracocci in this habitat are discussed.

Biofilms↗
PubMed1993

[The effect of flavomycin on digestion in fattening bulls].

Three friesian bulls (Genotype 31) were fitted with re-entrant cannulas at the duodenum to investigate the influence of a flavomycin supplement of the digestion in the forestomachs and the other parts of the digestive tract. The supplement of flavomycin increased the total digestibility of the organic matter. The digestibility of starch and sugar was between 97% and 98%. The balance of the nutrients in the digestive tract shows, that by flavomycin supplementation the degradation of organic matter and crude protein in the fore stomach was decreased and the amount of the organic matter and crude protein in the gut was increased. The balance of the amino acids in the gut showed that after flavomycin ca. 30 g more amino acids were found in the gut. The synthesis of bacterial protein in the forestomachs was, after flavomycin application, slightly reduced as was the degradation rate of the feed protein.

Amino Acids↗
PubMed1991

[Mounting devices for screening blocks on the linear accelerator--the drawbacks and modifications].

Block mounting devices for linacs--drawbacks and modifications: Shielding blocks are often used in radiotherapy. They are fixed on the linac's head by means of standard accessory mounting devices. The disadvantages of these parts are discussed and two modifications are presented: One device with adjustable focus-support distance for standard lead blocks and another with gliding planes to insert easily the heavy individually formed shielding blocks. Errors in mounting of all these devices are very dangerous, so we developed a simple locking lever providing a high security.

Equipment Design↗
PubMed1990

[Special aspects of abdominal adhesions in children].

Relaparotomy in children was necessary in 2.6% of 4902 cases because of adhesions (80% within 2 years). Adhesions can be differentiated histologically by the number of blood vessels. In the highly vascular adhesions arteries and veins are united in a common cord of connective tissue. Whereas the less vascular characteristically have a dense connective tissue rich in collagen. The number of capillaries distributed within the connective tissue varies. Some adhesions have a mixed tissue type of both tissues rich and poor in blood vessels. All adhesions are peripherally delimited by a different number of fibrous layers.

Abdomen↗
PubMed1989

[Standard diagnosis and therapy of pheochromocytoma in children].

Phaeochromocytomas are rare in childhood. Only 5 to 10% of these neoplasms become manifest during the first two decades of life. Before puberty the incidence of phaeochromocytoma in boys is twice than in girls. Phaeochromocytoma is successfully treated only by surgery. A standardised concept of therapy is important; it should comprise the following points: 1. Diagnosis as early as ever possible. 2. Improved diagnosis of localisation via ultrasound, scintigraphy and computed tomography. 3. Standardised perioperative drug therapy in cooperation by the paediatric surgeon with the anaesthesiologist and paediatrician. If these guidelines are observed, the prospects of cure are 95-100% in case of chromaffin tumours.

Adolescent↗
PubMed1989

Penetration of ticarcillin/clavulanate into cartilage.

The penetration of ticarcillin and clavulanate into cartilage was investigated in 20 subjects undergoing funnel chest correction. Cartilage samples, obtained 120 or 180 min after administration of ticarcillin/clavulanate (mean dose: ticarcillin 70.0 mg/kg, clavulanate 4.7 mg/kg), were divided into core samples and outer covering portions. After 120 min, the mean ticarcillin in the outer portion was 11.0 mg/kg and that in the core sample was 0.81 mg/kg; at 180 min the mean concentration in the outer portion was 6.47 mg/kg and ticarcillin was undetectable in all but two core samples. Clavulanate was shown to decline with time in spiked cartilage preparations and the results in this investigation may underestimate penetration. Clavulanate was undetectable in most core samples. In the outer portion the mean concentration was 1.30 mg/kg at 120 min and 0.62 mg/kg at 180 min. The penetration gradient requires further elucidation and should be considered when chemotherapy for infection in cartilage is discussed.

Adolescent↗
PubMed1989

[Individual fixation during irradiation following breast-conserving surgery. Methodology and clinical results in 50 patients].

From February, 1986 through October, 1987, fifty patients with mammary carcinomas of the stages T1N0M0, T2N0M0, T1N1M0 and T2N1M0 were irradiated after breast-preserving surgery. The irradiation conditions were standardized with cobalt-60 gamma radiation or photons emitted by a linear accelerator and fixed oblique position in a specially manufactured, individual rigid foam bed. The position was checked every week at the therapy simulator with an analog tomographic attachment. The method, positioning in a 30 degrees oblique position and immobilization in an individually moulded rigid foam bed is described, and the necessity of regular tomographic controls in treatment position is underlined. Because of the short follow-up time of eight months, clinical results can only be presented with regard to early side effects and cosmetic results. A final assessment of this method is therefore not yet possible.

Adult↗
PubMed1989

[Artifacts in ultrasonic diagnosis].

Due to facts of the wave theory, to properties of ultrasound-systems and to peculiarities of the examined organs and tissues artifacts may influence the image-formation in diagnostic sonography. In diagnostic ultrasound five types of artifacts are common: --Displaying of nonstructural echo signals (reverberation and reflection) --Removal of real structural echo signals from the display (tissue-attenuation and acoustic shadowing) --Displacement of echo signals on the display (refraction and beamwidth-artifact) --Distortion of echo signals (shape distortion-artifact, bands, gray-scale-contouring and blobby dots) --Distortion of the organ dynamics on the display (reverberation or "ring-around" and "herbie") The understanding of the mechanisms behind their production allows recognition of artifacts and avoids misinterpretations and incorrect diagnoses. Moreover, it helps to prevent the production of artifacts, e.g. by proper gain-control-setting, adjusted focussing, etc.; it also may, if properly evaluated, reveal further information which can be used for diagnostic purposes (e.g. nature and geometry of interfaces, content of cysts, etc.).

Animals↗
PubMed1988

Concentration of azlocillin in human chondral tissue.

The concentration of azlocillin was determined using high performance liquid chromatography in serum and chondral tissue after intravenous infusion of azlocillin (75 mg/kg body weight). In serum the levels of ten patients (2 to 27 years of age, body weight 12 to 69 kg) decreased from 478 (30 min post infusion) to 120 micrograms/ml (120 min). In contrast, the concentrations in chondral tissue ranged between 24 and 35 mg/g tissue at the corresponding times. Although the mean levels suggest a remarkable penetration of azlocillin into chondral tissue, the high individual differences observed in the tissue levels (2.1 to 138 micrograms/g tissue) require a higher dosage to ensure sufficient antimicrobial therapy in all patients.

Adolescent↗
PubMed1987

[Modified Rehbein surgical procedure using a surgical staple--progress in the treatment of Hirschsprung disease in children].

The particular advantage of using the intraluminal stapler in Rehbein's operation for Hirschsprung's disease is that we are able to achieve very low and safe anastomoses 2-3 cm above the anal verge. Use of the intraluminal stapler has successfully overcome the difficulties of a very low handsewn anastomoses in children. In this way the aganglionosic segment can be resected completely. In 16 infants we can demonstrate the safety and reliability of colorectal anastomoses using the smallest intraluminal circular stapler, 21 mm in diameter. Endoscopic and manometric investigations demonstrate no stenosis or stricture.

Anastomosis, Surgical↗