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Biomedical subjects

H Kiefer

Publications and source records attributed to H Kiefer.

16 recordsLinked to original sources
PubMed1991

Improvement of flow cytometry analysis and sorting of bull spermatozoa by optical monitoring of cell orientation as evaluated by DNA specific probing.

Flow cytometry is a potential method for the separation of X and Y bearing spermatozoa, on the basis of their relative DNA content evaluated by the fluorescence emission intensity due to specific fluorochrome DNA staining. However, spermatozoa DNA is highly condensed and nuclei exhibit flat non spherical shape, which can produce artefacts impeding accurate analysis. In order to avoid these limitations, decondensation of DNA performed by enzymatic treatment and a modification of the flow cytometer that orients the spermatozoa relative to the laser beam are generally used. In this work, we describe alternative methods and materials for selection of 1) decondensed and thus dead spermatozoa without orientation, sorted on the basis of only the 10% spermatozoa containing the least DNA (expected Y) and the 10% spermatozoa containing the more DNA (expected X), or 2) native spermatozoa homogeneously oriented using a simultaneous measurement of Axial light loss (extinction) and Forward angle light scatter. For testing enrichment of each selected fraction we have worked out a molecular hybridization procedure using X and Y specific DNA probes. We analyse and sort bull spermatozoa on these basis: the purity obtained for these fractions is 80% without orientation after enzymatic treatment, and 70% on live spermatozoa "optically" oriented.

Animals↗
PubMed1991

Biosensors based on membrane transport proteins.

We propose a novel class of biosensors based on membrane bound receptors or transport proteins as the sensing element. The protein is incorporated in a planar lipid bilayer which covers the transducer. The transducer may detect an electric current, a voltage, or a change in fluorescence. A prototype lactose sensor is presented which consists of a quartz slide covered by a lipid membrane containing the protein lactose permease from Escherichia coli. This protein is a lactose/H+ cotransporter, hence lactose in the external medium initiates lactose/H+ cotransport across the lipid membrane. This leads to a rise in proton concentration in the small volume between the lipid membrane and the quartz surface which can be detected by a pH-sensitive fluorescence dye.

Arylsulfonates↗
PubMed1991

[A complex forearm injury caused by skateboarding].

Conservative treatment of forearm fractures in children is preferred. However, in a few cases an open reduction and internal fixation are required. The case of a 15-year-old boy with a complex forearm injury following a skateboard accident is reported. The surgical treatment of these injuries is presented and the indications for open reduction and internal fixation of forearm fractures in children are discussed.

Adolescent↗
PubMed1979

Radiochemical synthesis and photochemical properties of the uncoupler 2-azido-4-nitrophenol, a versatile photoaffinity labeling reagent.

2-Amino-4-nitrophenol was tritiated in an acid-catalyzed hydrogen exchange reaction. Radioactive 2-azido-4-nitrophenol with a specific radioactivity up to 21 mCi/mmol was synthesized from 2-amino-4-nitrophenol by diazotization and azide coupling. The photochemical properties of the uncoupler, 2-azido-4-nitrophenol, were studied as free solute and as ligand bound to uncoupler binding sites in bovine serum albumin and mitochondria. Based on product analyses, irradiation of free or bound 2-azido-4-nitrophenolate with visible light results in the formation of nitrene intermediates with a singlet to triplet ratio of 6:1 to 9:1. 2-Azido-4-nitrophenolate and bovine serum albumin form a strong 1:1 complex (KD = 0.7 micron) which can be converted into a photoproduct with a covalent bond between the label and the protein. The acid dissociation constant of the protein-bound 2-amino-4-nitrophenol moiety is strongly pH dependent. Photoaffinity labeling of mitochondria by 2-azido-4-nitrophenolate follows a pattern expected from equilibrium binding studies using normal and lipid-depleted particles: polypeptides were found to bear 90-95% of the radioactive label, and 5-10% of the latter was bound to phospholipids. Two polypeptides (approximately 56 000 and 31 000 daltons) were associated with 60% of the label, indicating a high degree of specific photochemical labeling.

Affinity Labels↗
PubMed1979

[Sonography and pharmacoangiography of the pancreas (author's transl)].

Real-Time-Sonography and pharmacoangiography with vasodilating drugs was performed in 63 patients with suspected pancreatic disease. Confirmation of the pancreatic lesion could be obtained in 41 cases by the symptomatology, pancreatic function test, autopsy, operation, laparoscopy with fine-needle-biopsy and by the roentgenologic visualization of pancreatic calcifications. Considering the relatively advanced disease of pancreatic carcinoma in our six patients the sonographic diagnosis was correct in all of them and with pharmacoangiography we failed on one case. In chronic pancreatitis correct diagnostic results with pharmacoangiography could be obtained in 8 of 18 cases and with sonography in 14 of 18 patients. In this study sonography showed certain advantages in comparison with angiography, but both methods were complementary and a better result in the differential diagnosis between chronic pancreatitis and pancreatic carcinoma could be achieved.

Chronic Disease↗
PubMed1979

[Uricemia in broilers].

Explore the source record for details and available documents.

Animal Nutritional Physiological Phenomena↗
PubMed1979

[Pharmacoangiography of the pancreas in cases of chronic pancreatitis and carcinoma of the pancreas (author's transl)].

Pancreatic angiography was performed in 246 patients using various vasodilating drugs. A pancreatographic effect could be found in 79% of all cases; Tolazolin was particularly efficient, since the effect could be found in 91% of the cases receiving the drug. The diagnostic value of different parameters was assessed in patients with chronic pancreatitis and in patients with carcinoma of the pancreas, in particular concerning the presence or absence of the pancreatographic effect, and the structure, width and contours of this organ. Evaluating the pancreatographic effect and vascular changes a correct diagnosis could be obtained in 69% of all cases with chronic pancreatitis and in 78% of all cases with carcinoma of the pancreas. The pancreatographic effect was diagnostically essential in 26% of all cases, and turned out to be rather useful in patients with chronic pancreatitis, whereas its diagnostic value was less in patients with carcinoma. The diagnostic value of angiography can be improved by the superselective technique and by applying the vasodilator Tolazolin, which is well tolerated and gives an excellent pancreatographic effect.

Adenocarcinoma↗
PubMed1977

[Mammography with minimal radiation dosage. Comparative studies on various imaging systems].

Using an MR-film-screen combination for mammography, only 8% of the usual radiation dose was found to be necessary. This corresponds with an average skin dose of 0.55 R per exposure. The new technique resulted in visible improvement of contrast. Some loss of detail affected in particular the recognition of macrocalcification. As the sole method for the early diagnosis of occult carcinomas of the breast, it will therefore be necessary to improve image quality. The system is suitable for control examinations and investigation of special problems. The use of the MR system with non-screen film in two planes is discussed in relation to dose reduction.

Breast Neoplasms↗
PubMed1976

[Supra-renal venography in patients with suspected endocrine hypertension (author's transl)].

In forty patients suspected clinically of having an endocrine cause for hypertension, an adrenal cortical adenoma was confirmed histologically in five. Hyperaldosteronism with enlarged or normal adrenals was demonstrated in three patients. The diagnosis in a further eight patients with an abnormal hormone pattern and/or an abnormal venogram has not yet been confirmed. Adrenal glands show considerable variation in their size, shape and localisation on venography.

Adenoma↗