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Biomedical subjects

D Hahn

Publications and source records attributed to D Hahn.

At least 181 records · Page 10Linked to original sources
PubMed1994

Phylogenetic studies on uncultured Frankia populations in nodules of Datisca cannabina.

Part of the 16S rRNA gene was amplified directly from uncultured endophyte populations within the root nodules of Datisca cannabina and three strains isolated from nodules of Alnus glutinosa (AgKG'84/4), Coriaria nepalensis (Cn3), and D. cannabina (Dc2). Sequence comparison based on 930 nucleotides indicated that the endophyte of D. cannabina nodules belongs to the genus Frankia and is highly related to the endophyte of C. nepalensis root nodules. The relatedness of the endophytes of C. nepalensis and D. cannabina nodules was also reflected by closely related nifH sequences amplified from the nodules. 16S rRNA sequence analysis of the noninfective strains obtained from both D. cannabina (Dc2) and C. nepalensis (Cn3) nodules also revealed the close relationship of these strains to the genus Frankia.

Actinomycetaceae↗
PubMed1994

[Imaging methods in diagnosis of malignant lymphoma].

Modern diagnostic imaging has improved the evaluation of malignant lymphomas during the last years. Most of the invasive examinations were replaced by non-invasive tomographic imaging. The most important examinations for the evaluation of lymph nodes are nowadays ultrasound, computed tomography and magnetic resonance imaging. The sequence of their use is depending on the region of examination. The immediate use of the method of choice for a certain body region instead of a protracted step-for-step diagnostic has led to a distinct shortening of diagnostics, diminishing of radiation dose exposure and cost reduction.

Adult↗
PubMed1993

Whole-Cell Hybridization of Frankia Strains with Fluorescence- or Digoxigenin-Labeled, 16S rRNA-Targeted Oligonucleotide Probes.

Whole-cell hybridization with non-radioactively labeled oligonucleotide probes was used to detect and identify Frankia strains in pure cultures and in nodules. Digoxigenin-labeled probes, which were detected with antibody-alkaline phosphatase conjugates, were more suitable for in situ detection of Frankia strains than fluorescent probes since the sensitivity of the former was higher and problems arising from the autofluorescence of cells and plant material were avoided. Successful detection of Frankia strains in paraformaldehyde-fixed cell material with digoxigenin-labeled oligonucleotide probes depended on pretreatments to permeabilize the cells. Specific hybridization signals on vesicles were obtained after lysozyme pretreatment (1 mg ml for 30 min at 20 degrees C). Reliable penetration of the antibody-enzyme conjugate into hyphae required additional washing with the detergent Nonidet P-40 (0.1%) and toluene (1% in ethanol) after lysozyme treatment. Identification of Frankia vesicles in nodule homogenates was possible only after the removal of the polysaccharide capsule surrounding the vesicles. Incubation with H(2)O(2) (15% in water for 1 h at room temperature) before lysozyme and detergent treatments was found to facilitate specific hybridization. No filaments or spores could be detected in nodule homogenates. This technique should be a powerful tool in the identification of Frankia isolates, in the characterization of as-yet-uncultured nodule populations, and in the confirmation of the origin of unusual Frankia isolates.

Journal Article↗
PubMed1993

Detection of mRNA in streptomyces cells by whole-cell hybridization with digoxigenin-labeled probes.

Detection of mRNA of the thiostrepton resistance gene (tsr) harbored by plasmid pIJ673 in Streptomyces violacelatus was achieved by whole-cell hybridization with digoxigenin-labeled in vitro transcripts followed by an antibody-alkaline phosphatase detection of the digoxigenin reporter molecule. Prior to hybridization, the cells had to be permeabilized by lysozyme, the detergent Nonidet P-40, and toluene. The permeability of the S. violacelatus cells for probes and the antibody-alkaline phosphatase conjugate was demonstrated by hybridization with digoxigenin-labeled, 16S rRNA-targeted oligonucleotides.

Journal Article↗
PubMed1993

[Imaging procedures in diagnosis of large solitary highly differentiated hepatocellular cancer--is it useful?].

We report on a 62-year-old man from Ethiopia with a large solitary primary hepatocellular carcinoma. In spite of using modern imaging techniques (ultrasound, computed tomography, magnetic resonance imaging, hepatobiliary function scintigraphy) it was not possible to distinguish between hepatocellular carcinoma, focal nodular hyperplasia and adenoma. Surgery with histological examination was necessary to obtain the diagnosis of a hepatocellular carcinoma.

Carcinoma, Hepatocellular↗
PubMed1992

Detection of micro-organisms in soil after in situ hybridization with rRNA-targeted, fluorescently labelled oligonucleotides.

rRNA sequences were used as targets for synthetic oligonucleotides labelled with the fluorescent dye tetramethylrhodamine isothiocyanate (Tritc) for in situ hybridizations to detect micro-organisms directly in soils that have different contents of soil minerals and organic material. Introduced Pseudomonas aeruginosa cells were directly fixed in soils and applied to slides after separation of large soil minerals only. Remaining soil minerals (clay minerals) and organic material (up to 8%) did not significantly interfere with signal expression after hybridization. Background signals were mainly caused by autofluorescence of organic material. Non-specific binding of labelled oligonucleotides to soil particles was not observed. In situ detection of introduced cells of Pseudomonas cepacia in a sandy loam spiked with a mixture of selected soil micro-organisms was possible after hybridization with a specific probe. Analysis of natural bacterial populations in soil, however, was not possible by in situ hybridization without activation of these micro-organisms by adding nutrients. Growing cells, e.g. Streptomyces scabies hyphae growing in amended soil, were easily detected.

Bacteria↗
PubMed1992

Innervation of pylorus in control of motility and gastric emptying.

The motility index (MI) and contractile frequency were determined for the gastric antrum, pylorus, and duodenum during digestive and interdigestive states in eight dogs before and after resection of the ramus pyloricus nervi vagi (NR) and after selective proximal vagotomy (SPV) subsequent to NR. Neither NR nor subsequent SPV altered the migrating motor complex in the interdigestive state. In the digestive state, NR decreased the MI in the antrum, pylorus, and duodenum. The MI did not further change after SPV subsequent to NR. The cholecystokinin antagonist L364,718 decreased MI in the antrum, pylorus, and duodenum. After NR, L364,718 caused a further reduction in the MI during administration. Gastric emptying was accelerated after NR. SPV subsequent to NR increased gastric emptying further. L364,718, in the absence of NR, accelerated gastric emptying but only during the initial period of emptying. After NR, L364,718 also decreased the time required for emptying of 50 and 100% of the meal. After SPV subsequent to NR, no additional acceleration of emptying occurred.

Animals↗
PubMed1992

[Osteoid osteoma of the elbow].

The osteoid osteoma is a rare, benign neoplasm of bone, most frequently located in the lower extremity (head of the tibia). Because of its rarity and its mostly rather unspecific clinical symptoms, diagnosis of the tumor is frequently problematic. Ideally, osteosclerosis surrounding a central focus (nidus) is revealed by radiology. Radiological imaging seems to be the most effective tool in reaching the correct diagnosis. Operative resection of the nidus is the only known curative therapy for osteoid osteoma.

Adult↗
PubMed1991

[Diffuse liver parenchymal diseases: the value of MRI compared to sonography and CT].

29 patients with diffuse liver disease were examined by ultrasound, CT and MRI. MRI imaging was performed using T1-and t2-weighted spin-echo-sequences and fast gradient-echo-sequences. The paramagnetic contrast agent Gd-DTPA was applied intravenously (0.1 mmol/kg). In all patients with hepatitis MRI enabled exact liver biopsy by delineation of inflammatory changes in cases of chronic or focal hepatitis. CT and ultrasound were superior to MRI in the detection of focal or diffuse fatty degeneration. However, MRI enabled an exact differentiation of fatty changes from neoplasm. In cases of fibrotic changes the most accurate findings could be shown by MRI. In patients suffering from hemochromatosis MRI supplied additional information compared to CT and ultrasound revealing significant reduction of signal intensity due to reinforced enhancement of iron. Concerning Wilson's disease MRI showed a characteristic pattern of parenchymal changes. The application of Gd-DTPA in cases of diffuse liver disease adds supplementary information about perfusion of liver parenchyma, but its value for diagnostic accuracy is only secondary.

Contrast Media↗
PubMed1990

Duplex sonography in the diagnosis of renovascular hypertension.

Duplex sonography (DS) has become a well established method for diagnosing peripheral vascular diseases. Technical developments (higher resolution of transducer and deeper penetration) have made also abdominal and retroperitoneal vessels, including renal arteries, accessible for duplex sonography. This method provides the opportunity to recognize renal artery stenoses causing renovascular hypertension without invasive procedures. We therefore examined 86 hypertensive patients with a high likelihood of renovascular hypertension. Due to technical problems (bowel gas, adipositas) we excluded 7 patients. 79 patients (17-79 years) were included in our study. Flow patterns of several renal vascular areas were evaluated while the renal artery was demonstrated on a B-scan. A spectrum analysis included the evaluation of the frequency pattern (widening of the frequency band and loss of a frequency free window below the systolic rise?), the sloping of the diastolic shoulder, and the calculation of different parameters like acceleration index, deceleration index, resistance index, acceleration time, and systolic peak velocity. The accuracy of DS in diagnosing renal artery stenoses was compared with arterial digital subtraction angiography (DSA). Renal artery stenoses was diagnosed in 21 out of 158 renal arteries (13%). Except for the systolic peak velocity no significant correlations could be found of any of the indices from spectrum analysis with hemodynamically significant stenoses (greater than 50%). However, the following 3 criteria proved to be valuable signs of a hemodynamically significant stenoses: 1) Maximal systolic acceleration greater than 3 m/s, 2) Steep sloping diastolic shoulder, and 3) Turbulence of all frequency ranges without a frequency free window below the systolic rise. Compared with DSA the sensitivity of DS was 84.0%, the specificity was 98.5%, and the predictive value 91% in significant stenoses.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1990

[Bone pain in adults as the first symptom of late congenital syphilis].

A 20-year-old woman developed multifocal bone pain. Diagnostic radiology revealed thickened periosteum, and syphilis serology was positive (T. pallidum haemagglutination test 1:5120). She also had discrete signs of congenital syphilis, with retinitis pigmentosa and Hutchinson's incisors. Skeletal scintigraphy demonstrated increased uptake even in radiologically unremarkable bones. The bone pain decreased after four-week administration of 1 M units of penicillin G daily. Scintigraphy one year later showed regression of the increased uptake, skeletal radiology did not reveal significant changes. This case shows that late manifestations of congenital syphilis still occur today. The stigmata of such an infection can be minute and easily missed. Skeletal scintigraphy is better for demonstrating active bone involvement than conventional radiology.

Adult↗
PubMed1990

Extraction of ribosomal RNA from soil for detection of Frankia with oligonucleotide probes.

Sequences of 16S rRNA of the nitrogen-fixing Frankia strain Ag45/Mut15 and the ineffective Frankia strain AgB1.9 were used to design a genus-specific oligonucleotide probe. Hybridization experiments of this Frankia probe and a second probe, specific for Nif+-Frankia strains only, were used to detect Frankia specific target sequences in RNA isolations from soil. A method is described for direct isolation of RNA from a loamy soil and a peat. Yields of about 10 ng RNA/g wet soil are obtained without detectable contamination with humic acids. Isolation of RNA after initial extraction of bacteria from soil resulted in significantly lower RNA yields, compared to the direct isolation procedure. Hybridization with both probes against rRNA isolations from Frankia-containing soil could detect target sequences within RNA isolations from 1 g wet soil with an estimated detection limit of 10(4) cells.

Actinomycetales↗
PubMed1990

Intermittent GnRH antagonist plus progestin contraception conserving tonic ovarian estrogen secretion and reducing progestin exposure.

The present study was designed to evaluate the effectiveness of a once-weekly regimen of GnRH antagonist followed by a progestin as a potential new contraceptive method. On menstrual cycle days 2, 9, 16, and 23 (onset of menses = Day 1) monkeys were divided into two groups: 1) those injected sc with 0.1 mg/kg Nal-Glu GnRH antagonist in saline and those given only vehicle (control). On cycle days 15 to 26, each treated female was administered 25 micrograms norgestimate/day orally. This was continued for three treatment cycles (84 days). Weekly injections of Nal-Glu GnRH antagonist effectively blocked completion of folliculogenesis, ovulation, and corpus luteum function as judged by serum LH, E2, and P levels. Serum progesterone was undetectable (less than 0.1 ng/ml) during the treatment cycles. Importantly, serum estradiol levels during GnRH antagonist plus norgestimate treatments were maintained at 35 +/- 7 pg/ml. Upon the cessation of norgestimate treatment on day 26 in each cycle, menses uniformly began within 2 or 3 days. Regarding recovery, apparently normal and presumably ovulatory menstrual cycles, as judged by timely estradiol elevations, midcycle LH surges, and luteal phase progesterone patterns, were manifest immediately following termination of the final GnRH antagonist plus norgestimate treatment cycle. Endometrial biopsies removed on day 26 of control cycles, and on day 26 of the third treatment cycle revealed appropriate late secretory phase endometrium having tortuous endometrial glands and superficial stromal edema. Histological sections of ovaries removed at the end of the GnRH antagonist plus norgestimate treatment revealed multiple small and medium-sized developing and atretic follicles, having maintained serial ablation of the potentially maturing follicles.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

[Magnetic resonance tomography of scaphoid pseudarthrosis: clinical and x-ray aspects].

37 patients with non-unions of fractures of the carpal scaphoid were examined with MRI and the results compared with conventional radiographs. Advantages of MRI are the documentation of concomitant soft tissue changes in the region of the pseudarthrosis, and the early detection of osteonecrosis of one of the fragments. Advantages of conventional radiographs are the exact documentation of cancellous bone morphology and the position of the fragments.

Adolescent↗