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Biomedical subjects

L Heiner

Publications and source records attributed to L Heiner.

At least 19 recordsLinked to original sources
PubMed2003

[Flat-screen detector systems in skeletal radiology].

Implementation of flat-panel detectors and digital integration of the technique instead of the use of conventional radiographs leads to a shortening of the work process. With flat-panel technology the image production process is shortened by more than 30%. Major advantages in the implementation of integrated RIS, PACS and flat-panel detector system are increases in quality because most mistakes in picture labeling can be avoided, easier handling without the need for cassettes, and the possibility of image post-processing. The diagnostic quality of the images in the field of musculoskeletal radiology is, in comparison to conventional radiographs, at least adequate and in most cases markedly improved with a marked reduction in radiation exposure of around 30-50%. With respect to the numerous advantages of the digital techniques and especially flat-panel technology there is a very high likelihood that conventional radiographs will be substituted in the coming years, even though the cost of the new technology is currently significantly higher compared to conventional systems.

Artifacts↗
PubMed2003

Diffusion-weighted MR imaging findings in a patient with herpes simplex encephalitis.

INTRODUCTION: Herpes simplex meningoencephalitis is one of the most common viral central nervous system infection in adults. Early diagnosis is essential for treatment. CASE REPORT: We present a case of a 68-year-old female patient with herpes simplex infection. On admission, she was in severe clinical condition. Diffusion-weighted (DW) magnetic resonance imaging detected brain involvement better than conventional sequences. After acyclovir therapy, the patient fully recovered. CONCLUSION: DW magnetic resonance imaging is expected to provide a more sensitive imaging in herpes simplex patients than conventional sequences.

Aged↗
PubMed2002

[Change in process management by implementing RIS, PACS and flat-panel detectors].

Implementation of radiological information systems (RIS) and picture archiving and communicating systems (PACS) results in significant changes of workflow in a radiological department. Additional connection with flat-panel detectors leads to a shortening of the work process. RIS and PACS implementation alone reduces the complete workflow by 21-80%. With flatpanel technology the image production process is further shortened by 25-30%. The workflow-steps are changed from original 17-12 with the implementation of RIS and PACS and to 5 with the integrated use of flatpanels. This clearly recognizable advantages in the workflow need an according financial investment. Several studies could show that the capitalisation-factor calculated over eight years is positive, with a gain range between 5-25%. Whether the additional implementation of flatpanel detectors results also in a positive capitalisation over the years, cannot be estimated exactly, at the moment, because the experiences are too short. Particularly critical are the interfaces, which needs a constant quality control. Our flatpanel detector-system is fixed, special images--as we have them in about 3-5% of all cases--need still conventional filmscreen or phosphorplate-systems. Full-spine and long-leg examinations cannot be performed with sufficient exactness. Without any questions implementation of integrated RIS, PACS and flatpanel detector-system needs excellent training of the employees, because of the changes in workflow etc. The main profits of such an integrated implementation are an increase in quality in image and report datas, easier handling--there are almost no more cassettes necessary--and excessive shortening of workflow.

Austria↗
PubMed1999

Diffusion-weighted MRI in sporadic Creutzfeldt-Jakob disease.

Diffusion-weighted MRI (DWI) was used in three patients with autopsy-proven sporadic Creutzfeldt-Jakob disease (CJD) to provide a rapid noninvasive way to make this sometimes confusing diagnosis. DWI prompted the diagnosis of CJD at an early stage and appears to be particularly useful for monitoring the progression of the disease. We suggest that patients with suspected CJD and no abnormalities on T2- and proton density-weighted images may have cortical involvement on DWI.

Aged↗
PubMed1992

[SPECT follow-up of cerebral blood circulation after stroke].

rCBF SPECT investigations with 99mTc-HMPAO were performed in 22 completed ischemic stroke patients on average 2.5, 16.8 and 38.0 days after stroke onset. As control group, 12 neurologically healthy volunteers were examined with the same method. The overall sensitivity of the rCBF SPECT method in the detection of cerebral blood flow abnormalities was 91%, with a specificity of 83% and an accuracy of 88%. The rCBF study was highly effective, particularly in the acute phase of the disease. Regional increased tracer uptake or a false normal 99mTc-HMPAO distribution due to the developing hyperemia mostly complicated the rCBF image interpretations in the subacute period. In the chronic phase, the spatial resolution of the SPECT system limited the detection of the continuously retracted stroke lesions.

Blood Flow Velocity↗
PubMed1985

The effect of di- and trivalent cations on the phosphorylation of the Ca2+-ATPase in sarcoplasmic reticulum vesicles.

The steady-state level of phosphorylated intermediate (EP) of (Mg2+ + Ca2+)-ATPase is influenced by magnesium and calcium concentration in the Ca2+-transporting system of sarcoplasmic reticulum vesicles. At micromolar [Ca2+], the level of EP is increased by Mg2+, depending on its concentration. The effect of Mg2+ is less pronounced at lower Ca2+ concentration. At low [Mg2+], the EP formation increases at millimolar concentrations of Ca2+, suggesting, in accordance with earlier results, that the substrate may also be CaATP instead of MgATP. LaCl3 (1 mM) enhanced the EP formation at low Mg2+ concentration. Surprisingly, 10 microM LaCl3 caused a marked decrease in EP formation at high [Mg2+] and had little or no effect on the level of EP at low Mg2+ concentration. The inducing effect of 1 mM LaCl3 on the EP formation at low [Mg2+] and the inhibitory effect of 10 microM LaCl3 at high Mg2+ concentration draw attention to the involvement of divalent cation-binding sites with different affinity in phosphorylation and to the particular role of Mg2+ in the EP formation and EP decomposition.

Animals↗
PubMed1984

Differences in calcium transport mechanism of the sarcoplasmic reticulum of the slow-twitch and fast-twitch muscle.

The Ca2+ uptake mechanism of sarcoplasmic reticulum (SR) was comparatively examined in fast-twitch and slow-twitch muscles. The competition of Mg2+ and Ca2+ at the binding sites is important in the function of the Mg2+-activated Ca2+-ATPase of the SR. The best ratio of divalent cations for Ca2+ uptake is not the same in the two kinds of muscle. The formation of the phosphorylated intermediate in more dependent on changes in the concentrations of the two divalent cations in the SR membrane of the fast-twitch than in that of the slow-twitch muscle. The requirement for Mg2+ to an efficient function of the transport ATPase and Ca2+ uptake of SR is greater in the latter than in the former.

Animals↗
PubMed1984

Role of the nervous system in regulation of the sarcoplasmic membrane function in different muscle fibres.

The influence of the nervous system on the Ca2+ uptake of sarcoplasmic reticulum (SR) of the slow-twitch and fast-twitch muscle was investigated by the application of denervation, immobilization and tenotomy. Denervation and immobilization produced an increase of Ca2+ uptake in SR of the slow-twitch muscle. No significant change could be observed in fast-twitch muscle. Inactivity atrophy induced by tenotomy had no effect on the Ca2+ uptake in SR of the slow muscle. The results suggest that the nervous system has a greater effect on SR function in the slow than in the fast-twitch muscle. The continuous effect of the nervous system characteristic of slow-twitch muscle fibres with tonic function plays a role in preservation of the low Ca2+ uptake capacity, in contrast to the fast-twitch muscle fibres with phasic function, which have a high Ca2+ uptake capacity.

Animals↗
PubMed1982

Proteases and proteinase inhibitors in experimental glucocorticosteroid myopathy.

The unknown enzymatic mechanism of enhanced protein breakdown in steroid myopathy was studied in functionally and biochemically different muscles of rabbits treated with dexamethasone for three weeks. After glucocorticoid administration the fast-twitch glycolytic semimembraneous muscle of treated animals was atrophied, whereas the weight of the slow-twitch oxidative soleus muscle was not altered. The specific activity of the lysosomal endo- and exopeptidases (cathepsin D, E, B and L, lysosomal carboxypeptidase A and dipeptidylpeptidase I) was increased about 2-fold in the atrophied white muscle. The activity of the cytosol enzyme Ca++-activated neutral proteinase was also elevated, whereas that of the other cytosol endopeptidase, chymotrypsin-like enzyme, was unaltered. The level of alanine aminopeptidase was only slightly increased. On the other hand, there were no unequivocal changes in protease activity in the soleus muscle. These findings are in agreement with the known differences in glucocorticoid-sensitivity of the various muscles. Our results suggest that the lysosomal proteolytic system and the Ca++-activated neutral proteinase may play an important role in the glucocorticoid-induced intracellular protein catabolism in muscle. The inhibitor capacities of cathepsin B and trypsin detectable in muscle cytosol were not altered after steroid treatment. Consequently, the increase in cathepsin B activity was not due to the loss of its inhibitor.

Animals↗
PubMed1980

Calcium-dependent potassium transport in progressive muscular dystrophy.

The rates of calcium-dependent potassium efflux of red blood cells in 9 Duchenne muscular dystrophic patients were measured. A significant decrease was revealed in the Ca-provoked K transport when compared with the rates observed in healthy controls. Results are discussed on the basis of the theory of generalized membrane defect in progressive muscular dystrophies.

Adolescent↗
PubMed1980

Changes in the contractile proteins of skeletal muscles induced by steroid myopathy.

The effect of chronic dexamethasone treatment was investigated on the myofibriller proteins of slow (soleus) and fast (semimembranous) muscles. The relative quantities of actin, protein C and protein M increased, while the myosin, troponin inhibitor and calcium binding components showed a relative decrease in both muscle types. The amount of troponin regulatory component and alpha-actinin decreased only in the fast muscle, while tropomyosin decreased significantly in the slow muscle. The isoenzyme pattern of fast muscle myosin was altered as a consequence of decreased myosin (LC-3 subunit.

Animals↗
PubMed1980

Changes in the sarcoplasmic proteins of skeletal muscles induced by experimental steroid myopathy.

The protein content and the relative distribution of cell compartments was investigated after 14 days of dexamethasone treatment in rabbits. The cell fractions were further analysed by SDS-PAGE. It was found that the loss of myofibrillar fraction was greater than that of the sarcoplasmic one. The susceptibility of fast-twitch fibres to steroid myopathy was more marked compared to the slow fibres. The sarcoplasmic proteins showed the following changes: myoglobin and myokinase decreased, while alpha-GPDH and LDH increased in both muscle types. On the other hand, the alterations of TPI, PGK, PGI, PK, ADA, phosphorylase kinase and phosphorylase b, were opposite in the two types of muscle. The results are in agreement with observations of others indicating that glucocorticoid treatment causes a shift in the equilibrium of synthesis and degradation of myofibrillar and sarcoplasmic proteins. The different susceptibility of fast versus slow muscles to steroid myopathy could be due to the activity-dependent regulatory mechanism of metabolic pathways.

Animals↗
PubMed1975

Subcellular distribution of phospholipids in different types of skeletal muscle.

Subcellular distribution of choline and non-choline phosphatides has been studied in tetanic (fast-twitch) and tonic (slow-twitch) muscles of rabbits. The choline phosphatide content of the subcellular fraction including the sarcolemma was greater in the tetanic than in the tonic muscle. On the other hand, the choline phosphatide content of the mitochondria-free sarcoplasmic fraction was greater in the tonic than in the tetanic muscle. A greater amount of non-choline phosphatide was found in each subcellular fraction of the tonic muscle as compared with those of the tetanic one. There was more fatty aldehyde in the non-choline phosphatides of each subcellular fraction of the tetanic muscle, than in those of the tonic one, of this type being much smaller in the tetanic muscle. There is not such an expressed difference in the fatty aldehyde contents of choline phosphatides of the subcellular fractions between the two kinds of muscle.

Aldehydes↗