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U Fischer

Publications and source records attributed to U Fischer.

At least 235 records · Page 13Linked to original sources
PubMed1992

[The tilted screen-cassette ("grid cut-off" effect). A problem of bedside thoracic diagnosis].

Tilting of a grid during portable radiography leads to uneven exposures, and errors greater than 3 degrees can lead to errors in interpretation. Differentiation from abnormal findings can be made by recognising exposure difference of extrathoracic comparable areas. The difficulties caused by tilting of the grid can be reduced by increasing the film focus distance and by using suitable grids. A new cassette holder with an integrated balance makes it possible to correct tilting of the grid rapidly and effectively. This results in improved image quality which can be applied not only to conventional exposure systems but is also of advantage when using digital methods.

Diagnostic Errors↗
PubMed1992

Artificial connection between glucose sensing and insulin delivery: implications of peritoneal administration.

The replacement of insulinogenic function in insulin-dependent diabetes has to restore the feedback between intracorporal glucose and insulin. This has been accomplished by the following approaches: (a) the so-called open-loop insulin treatment by means of injections or pumps, employing laboratory or other extracorporal analytical devices and closing the feedback at large intervals only; (b) transplantation of insulin producing tissue and the bioartificial pancreas, employing the natural beta-cell both for glucose sensing and insulin delivery; (c) implanted artificial drug delivery systems providing chemical feedback between intracorporal glucose and insulin release from a nonrefillable reservoir of limited capacity; (d) the intracorporal or paracorporal artificial beta-cell comprising a glucose sensor (electrochemical or other type) that permanently delivers the signal to the computer-controlled insulin pump. This artificial device works on the basis of an algorithm of glucose-dependent insulin provision, compensating for the lack of other regulators, for the site of insulin administration, which is usually posthepatic, and for the kinetic properties of sensing system, e.g., a subcutaneous inserted amperometric electrode. Present experimental studies show that the pharmacodynamics of peritoneally applied insulin may be implemented into a mathematical model of the overall glucose-insulin system. They include absorption nearly as fast as after intravenous application, predominant portal inflow and approximately 30% hepatic removal. Feedback-controlled peritoneal insulin administration by means of an artificial beta-cell working on peripheral-venous blood glucose monitoring results in normal glycemic profiles under basal conditions and during oral glucose loads, if the pharmacodynamic properties of the peritoneal route are implemented into the insulin dosage algorithm.

Algorithms↗
PubMed1992

[The value of digital luminescence radiography within the scope of traumatologic follow-up examinations].

At the present time we cannot unhesitatingly recommend the general use of digital luminescence radiography in traumatological follow-up examinations. Marked drawbacks of this method are, for example, sudden changes in contrast in the marginal areas of osteosynthesis material, occasional limitations in the detailed assessment of spongious structures and problems in respect of imaging geometry. By modifying the image processing parameters, increasing the image matrix and enlarging the format spectrum, however, these problems should be capable of being resolved in the future. Positive features, on the other hand, are even now the possibility of reducing the dosage to a marked degree in many traumatological follow-up examinations, especially in children and adolescents, and in case of conservatively treated fractures. In the long run we can foresee the routine use of digitalised examination methods on traumatology coupled with the possibility of storage in an image filing and communication system, although this is at present not yet feasible due to lack of requisite experience and the cost of the necessary equipment.

Computer Systems↗
PubMed1992

[The place of computed tomography and magnetic resonance tomography in the diagnosis of bone sequestra].

Conventional radiographs of 45 patients with chronic osteomyelitis, mostly of posttraumatic origin, were compared with computed tomography (CT) and operative findings. In addition, magnetic resonance imaging (MRI) was performed in 6 of these patients. In 28 patients (65%) bony sequestra were identified and in most cases histologically confirmed by surgical exploration. CT proved to be the method of choice for the preoperative diagnosis of sequestra in patients with chronic osteomyelitis. MRI provided no significant additional diagnostic information, its advantage appears to be a more detailed and accurate imaging of the extent of the intra- or extraosseous inflammation, thereby facilitating surgical planning.

Adult↗
PubMed1991

Electron transfer proteins of the purple phototrophic bacterium, Rhodopseudomonas rutila.

The soluble electron transfer protein content of Rhodopseudomonas rutila was found to consist of two basic cytochromes and a (4Fe-4S) ferredoxin. Cytochrome c' was easily identified by its characteristic high spin absorption spectra. The native molecular weight is 29,000 and the subunit is 14,000. Cytochrome c-550 has low spin absorption spectra and a high redox potential (376 mV) typical of cytochromes c2. The molecular weight is about 14,000. The ferredoxin is apparently a dimer (43,000) of approximately 18,000 Da subunits. There are 1.3 to 1.5 iron-sulfur clusters per monomer of 18- to 21-kDa protein. The N-terminal amino acid sequence is like the (7Fe-8S) ferredoxins of Rhodobacter capsulatus and Azotobacter vinelandii. Remarkably, there are only 2 or 3 out of 25 amino acid substitutions. Difference absorption spectra of Rps. rutila membranes indicate that there is not tetraheme reaction center cytochrome c, such as is characteristic of Rps. viridis. However, there are a high potential cytochrome c and a low potential cytochrome b in the membrane, which are suggestive of a cytochrome bc1 complex. Rps. rutila is most similar to Rps. palustris in microbiological properties, yet it does not have the cytochromes c-556, c-554, and c-551 in addition to c2 and c', which are characteristic of Rps. palustris. Furthermore, the Rps. rutila cytochrome c' is dimeric, whereas the same protein from Rps. palustris is the only one known to be monomeric. The cytochrome pattern is more like that of Rhodospirillum rubrum and Rb. capsulatus, which are apparently only able to make cytochromes c2 and c'.

Cytochrome c Group↗
PubMed1991

[Splenogonadal fusion].

Explore the source record for details and available documents.

Angiography, Digital Subtraction↗
PubMed1991

Diversity in the signals required for nuclear accumulation of U snRNPs and variety in the pathways of nuclear transport.

The requirements for nuclear targeting of a number of U snRNAs have been studied by analyzing the behavior of in vitro-generated transcripts after microinjection into the cytoplasm of Xenopus oocytes. Like the previously studied U1 snRNA, U2 snRNA is excluded from the nucleus when it does not have the 2,2,7mGpppN cap structure typical of the RNA polymerase II (pol II)-transcribed U snRNAs. Surprisingly, two other pol II-transcribed U snRNAs, U4 and U5, have a much less stringent requirement for the trimethyl cap structure. The gamma-monomethyl triphosphate cap structure of the RNA polymerase III-transcribed U6 snRNA, on the other hand, is shown not to play a role in nuclear targeting. Wheat germ agglutinin, which is known to prevent the import of many proteins into the nucleus, inhibits nuclear uptake of U6, but not of U1 or U5 snRNAs. Conversely, a 2,2,7mGpppG dinucleotide analogue of the trimethyl cap structure inhibits transport of the pol II U snRNAs, but does not detectably affect the transport of either U6 snRNA or a karyophilic protein. From these results it can be deduced that U6 enters the nucleus by a pathway similar or identical to that used by karyophilic proteins. The composite nuclear localization signals of the trimethyl cap-containing U snRNPs, however, do not function in the same way as previously defined nuclear targeting signals.

Animals↗
PubMed1991

Successful treatment of severe premenstrual syndrome by combined use of gonadotropin-releasing hormone agonist and estrogen/progestin.

Although abolishment of ovarian cyclicity by the use of a long-acting GnRH agonist (GnRH-a) provides effective treatment for premenstrual syndrome (PMS), its use is limited by sequellae of the resultant hypoestrogenism. In this study the effects of estrogen/progestin replacement on the symptomatic improvement afforded by GnRH-a were evaluated in eight women with severe PMS. The 8-month study design included 2 months of control, 2 months of GnRH-a alone, and 4 further months in which the exogenous steroids were replaced in randomized, double blind, placebo-controlled cross-over fashion using 1 month each of 1) conjugated equine estrogen (CEE) on days 1-25, 2) 10 mg medroxyprogesterone acetate (MPA) on days 16-25, 3) CEE (days 1-25) plus MPA (days 16-25), and 4) placebo alone. Mood and physical symptoms were measured daily on a valid and reliable instrument, the Calendar of Premenstrual Experiences. As expected, administration of GnRH-a alone resulted in a 75% improvement in luteal phase symptom scores (17.8 +/- 4.8 vs. 4.2 +/- 1.6; P less than 0.01). Combined sequential administration of CEE and MPA in addition to GnRH-a was effective in maintaining the reduced symptom scores seen after GnRH-a alone and was superior to the addition of CEE alone, MPA alone, or placebo. This combination of CEE and MPA resulted in a 60% improvement (P less than 0.05) compared to the luteal phase of control months in both behavioral (14.1 +/- 3.9 vs. 4.2 +/- 0.8) and total (17.8 +/- 4.8 vs. 6.5 +/- 1.8) symptoms. We conclude that the undesirable consequence of ovarian steroid deficiency in the treatment of PMS by GnRH-a can be overcome by the addition of sequential estrogen and progestogen replacements without significantly reducing the effectiveness of GnRH-a in this disorder.

Adult↗
PubMed1991

[Effect of molsidomine infusion on thrombocyte function in acute myocardial infarct].

In 10 patients with acute myocardial infarction i.v. molsidomine was given over 48 h and a number of platelet functions was evaluated before and 3, 24, and 48 h after therapy. There was a significant prolongation of template bleeding time from 290 s to 400 s. The amplitude of spontaneous and induced platelet aggregation remained unchanged. In four of the 10 patients initially high plasma concentrations of beta-TG and PF4, and high serum concentrations of TxB2, decreased, indicating an effect of molsidomine in states of hyperreactive platelets.

Aged↗
PubMed1991

Implantable glucose sensors: comparison between in vitro and in vivo kinetics.

This study was aimed at validating the in vitro estimated response characteristics of implanted glucose oxidase/H2O2 electrodes with respect to their in vivo function. Monoexponential non-linear regression analysis of sensor current vs. time curves in response to square alterations in glucose concentration gave response times T95 of between 1 and 5 min. Non-primed glucose infusions were applied to dogs with these electrodes implanted subcutaneously. The simultaneously monitored in vivo data were subjected to non-linear regression analysis. The time constants T of increases or decreases after starting or ending the glucose load were (mean +/- SEM) 53 +/- 10 and 26 +/- 4 min (significant difference, p less than 0.05) in sensor current, 28 +/- 8 and 15 +/- 2 min (NS) in whole blood, and 26 +/- 5 and 18 +/- 2 min (NS) in plasma. The in vivo kinetic patterns of sensors were not related to their in vitro response times. Non-linear regression analysis of in vitro responses of glucose sensors under clearly defined conditions is recommended as a basis for further studies. The physiological delay in the subcutaneous glucose system needs more attention in this field of research.

Animals↗
PubMed1991

[Cystic space-occupying lesions in the femoral trigone].

The differential diagnosis of cystic tumours in the region of the so-called Trigonum femorale is presented and discussed. In this context the topography of this area is demonstrated. In addition to the clinical findings sonography and computed tomography are the method of choice in finding the right diagnosis. Invasive methods such as angiography and lymphography are indicated in only few cases. US-guided fine-needle-aspiration should be preferred instead, if it is of any therapeutic relevance.

Aneurysm↗
PubMed1990

An essential signaling role for the m3G cap in the transport of U1 snRNP to the nucleus.

The major small nuclear ribonucleoprotein particles (snRNPs) U1, U2, U4 + U6, and U5 have to be transported from the cytoplasm, where they are synthesized, to the nucleus, where they splice pre-messenger RNAs. Since the free core snRNP proteins in the cytoplasm do not enter the nucleus on their own, the nuclear location signal must either reside on the snRNA or be created as a result of snRNA-protein interaction. Here the involvement by the 5'-terminal cap of snRNA molecules in the nucleo-cytoplasmic transport of UsnRNPs has been studied by microinjection of synthetic U1 RNA molecules into frog oocytes; the U1 RNA bore either the normal cap (m3G) or a chemical derivative. Antibodies in the cytoplasm against the m3G cap inhibited the nuclear uptake of U1 snRNP. U1 RNA that was uncapped or contained an unnatural ApppG cap did not enter the nucleus, even though it carried a normal complement of protein molecules. When the ribose ring of the m3G cap was oxidized with periodate, nuclear transport of U1 snRNPs was severely inhibited. Finally, microinjection of m3G cap alone (but not m7G cap) into oocytes severely inhibited the transport of U1 snRNPs to the nucleus. These data suggest that one step in the nuclear uptake of U1 snRNPs involves the m3G cap structure.

Animals↗