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Biomedical subjects

D Krause

Publications and source records attributed to D Krause.

At least 109 records · Page 6Linked to original sources
PubMed1994

[Lumbar disk hernia. Excision of hernia with or without complementary diskectomy?].

The authors compare the limited removal of the ruptured disc to discectomy for lumbar disc herniation. Analysis of results during a four years period demonstrates a twice higher recurrence rate with limited removal than with discectomy and a more frequent residual low back pain, after limited removal of the ruptured disc. These data made then limit the indications of the simple ruptured disc removal technique, with the exception of some specific anatomical locations: the migrated disc situated anterior or posterior to the ligament, without an associated discal bulging.

Adult↗
PubMed1994

[Scaphoid fissure in algodystrophy: diagnostic value of MRI].

Stress fractures are exceptional in patients with reflex sympathetic dystrophy syndrome, even when bone loss is severe. We report a case of stress fracture of the navicular bone documented by magnetic resonance imaging. Recurrence of localized pain in patients with reflex sympathetic dystrophy syndrome suggests either a relapse of the syndrome or a bony fissure. Magnetic resonance imaging can provide early differentiation of these two conditions.

Fractures, Stress↗
PubMed1994

[Walking ability and independence in old age].

Physiological changes associated with aging and their influence on the activities of daily living (ADL) in old and very old persons are discussed. Degenerative diseases of the spine and of weight-bearing joints may affect the ability to walk and may thus endanger independent living. Treatment of orthopedic disease in the elderly should include efforts at rehabilitation aimed at enabling the patient to return home. For this, patients should be able to walk, or if this goal seems to be inaccessible, independence in ADL should be aimed for. Special aspects of rehabilitation are discussed for old patients following hip replacement or lower leg amputation.

Activities of Daily Living↗
PubMed1993

The role of coherence time in the effect of microwaves on ornithine decarboxylase activity.

Previously, we demonstrated the requirements for a minimum coherence time of an applied, small amplitude (10 microT) ELF magnetic field if the field were to produce an enhancement of ornithine decarboxylase activity in L929 fibroblasts. Further investigation has revealed a remarkably similar coherence time phenomenon for enhancement of ornithine decarboxylase activity by amplitude-modulated 915 MHz microwaves of large amplitude (SAR 2.5 W/kg). Microwave fields modulated at 55, 60, or 65 Hz approximately doubled ornithine decarboxylase activity after 8 h. Switching modulation frequencies from 55 to 65 Hz at coherence times of 1.0 s or less abolished enhancement, while times of 10 s or longer provided full enhancement. Our results show that the microwave coherence effects are remarkably similar to those observed with ELF fields.

Animals↗
PubMed1993

Biological, physical, and electrical parameters for in vitro studies with ELF magnetic and electric fields: a primer.

This paper presents material which is intended to assist researchers in identifying and controlling a range of biological, electrical, and other physical parameters that can affect the outcome of in vitro studies with extremely low frequency (ELF) magnetic and electric fields. Brief descriptions of power line magnetic and electric fields are provided and methods for the generation of 60 Hz as well as other ELF fields in the laboratory are surveyed. Methods for calculating and measuring exposure parameters in culture medium are also described. Relating in vitro and internal in vivo exposure conditions across different animal species is discussed to aid researchers in selecting levels of field exposure. The text is purposely elementary, and sometimes brief, with references provided to aid the interested reader in obtaining a fuller understanding of the many topics. Because the range of experimental parameters that can influence the outcome of in vitro studies with ELF fields is so broad, a multidisciplinary approach is normally required to carry out the research.

Animals↗
PubMed1993

A method for simultaneous determination of group-specific component (GC) and alpha 2HS-glycoprotein (AHSG) by ultrathin-layer isoelectric focusing and immunoblotting.

A method for simultaneous determination of group-specific component and alpha 2-HS-glycoprotein by ultrathin-layer isoelectric focusing and immunoblotting is described. The advantages of this combined technique are the saving of chemicals and time. The band patterns of both marker proteins were always reproducible.

Blood Proteins↗
PubMed1993

Low fluences of ultraviolet irradiation stimulate HeLa cell surface aminopeptidase and candidate "TGF alpha ase" activity.

Several forms of perturbation result in the release of bioactive molecules into the microenvironment of injured cells to mediate the inflammatory or reparative reactions which restore normal tissue structure and function. Amongst other products, ultraviolet irradiation (UV) causes the release of the growth factor TGF alpha from a variety of epithelial cell sources, apparently by a post-translational mechanism. Here we have explored the hypothesis that UV results in the activation of cell surface proteases which may then be capable of excising mature TGF alpha from its plasma membrane-bound precursor. Using a recently described, sensitive assay of peptidase activity tailored to the substrate requirements for cleavage of the scissile bonds in proTGF alpha, we have found that nonlethal fluences of UV (< 12 Jm-2) to HeLa cell cultures are followed by large increases in cell surface proteolytic activities. Amongst these, endopeptidase activity produces a similar product profile from the nonapeptide substrate to that of human leukocyte elastase, an enzyme previously shown to be capable of releasing a bioactive, mature form of TGF alpha from its cell-bound precursor. However, in addition to this candidate "TGFase" activity, cell surface aminopeptidase activity was also very significantly increased. The increase in the two classes of peptidase function differed in the timing of their responses. Aminopeptidase activation occurred immediately following UV, peaking after some 15-20 h, whereas the increase in endopeptidase activity lagged 6 h behind, cresting after 20-24 h. No evidence for a role for aminopeptidase in the activation of the endopeptidase could be found. Also, there was no increase in the total proteolytic activity demonstratable in cell extracts following UV. Attempts to interrupt the UV peptidase activation by inhibiting protein synthesis with cycloheximide were unsuccessful; rather, the inhibitor itself caused an increase in both classes of peptidase activity during the first 20 h. Unlike the UV response, both the aminopeptidase and endopeptidase ectoactivities increased simultaneously within a few hours of introducing cycloheximide into the medium of unirradiated cultures. The cycloheximide induced activity peaked after 20 h. Interestingly, cycloheximide alone has previously been shown to potentiate TGF alpha release from a cell line producing its precursor constitutively. These data suggest that both UV and cycloheximide can initiate reactions in HeLa cells which result in ectopeptidase activation of a global nature. Since both agents result in rapid interruption of DNA synthesis, it is possible that this cell surface proteolytic response may be analogous to, or part of, the "mammalian genetic stress response".(ABSTRACT TRUNCATED AT 400 WORDS)

Amino Acid Sequence↗
PubMed1993

Tissue-related and species-specific differences in the 2-5A oligomer size requirement for activation of 2-5A-dependent RNase.

2',5'-Oligoadenylate (2-5A)-dependent RNase (L or F) is the final enzyme in the 2-5A pathway and a key component in the molecular mechanism of interferon (IFN) action. Here we demonstrate differences in the 2-5A oligomer size requirement between rabbit 2-5A-dependent RNase from reticulocytes and from cultured kidney cells. The rabbit reticulocyte enzyme was activated by tetramer 2-5A, whereas the ribonuclease from rabbit kidney cells required only trimer 2-5A. Interestingly, in contrast to the 2-5A-dependent RNase from rabbit reticulocytes, that from murine reticulocytes could be activated by trimer 2-5A. Partial proteolysis of affinity-labeled, 80-kD 2-5A-dependent RNase from rabbit reticulocytes and rabbit kidney cells resulted in the same pattern of labeled peptides. However, the affinity labeling reaction with a 32P-labeled 2-5A analog did produce some different labeled polypeptides in rabbit kidney cell extract and rabbit reticulocyte lysate. These results could indicate specialized functions for the 2-5A system in different organ systems.

Adenine Nucleotides↗
PubMed1993

Gene-specific modulation of RNA synthesis and degradation by extremely low frequency electromagnetic fields.

Pulse-labeling studies from our laboratory and others have shown that extremely low frequency (ELF) electromagnetic fields can produce a transient increase in gene transcription. In this study, the synthesis, degradation and processing, and steady state levels of specific RNA species during exposure to ELF radiation were determined in human leukemia HL-60 cells. The overall steady state RNA levels, assessed by continuous and equilibrium labeling with 3H-uridine, were not affected by ELF exposure. Northern blot analysis using probes specific for c-myc, beta-actin, and 45S ribosomal RNA gene products revealed that ELF did not alter the steady state levels of these RNAs. Examination of gene-specific transcription by a novel nuclease protection assay revealed that while ELF did not substantially alter the transcription rates for c-myc and beta-actin, transcription of the 45S ribosomal RNA gene was increased by 40-50%. To explain the observed increase in the synthesis of 45S ribosomal RNA without an associated increase in its steady state level, the degradation and processing of the ribosomal gene transcript in the presence and absence of an ELF field were followed by pulse-chase 3H-uridine labeling. This revealed that ELF radiation accelerated both the processing and degradation of the ribosomal RNA transcript. During ELF exposure, the half-life of the 45S ribosomal RNA was decreased from 115 min. to 85 min. These results show that ELF can selectively affect RNA levels by modulating either the transcription rate and/or RNA post-transcriptional processing and turnover.

Actins↗
PubMed1993

Cervical nucleolysis: indications, technique, results. 190 patients.

For many years now percutaneous techniques have proved effective in the curative treatment of lumbar disc herniation, mostly in young subjects. This technique, however, is seldom indicated, let alone performed, in the cervical spine for a variety of reasons: a) the neck contains several closely arranged structures such as the vasculo-nervous bundles, the airway-digestive tract and the cervical spine around the spinal cord; b) the disc is approached by the anterior route, in contrast with the lumbo-sacral spine where the approach is posterolateral; c) the manufacturers insist on restrictions in the use of chymopapain in view of the potential risk of spinal cord damage, either by possible breaks in the meninges of by accidental diffusion of the enzyme into perimedullary epidural structures which support a particularly developed venous plexus; d) legal protection may be denied to operators who perform cervical chemonucleolysis, since the product has not yet been officially authorized, in France and perhaps elsewhere*, for treatment of cervical disc herniation. Several years of experience in the practice of cervical nucleolysis have convinced the authors that this method is remarkably effective and can be used in the treatment of cervicobrachial neuralgia (CBN) occurring in young subjects. Radiculalgia is essentially due to a disc fragment being positioned within the vertebral canal or a foramen, thereby compressing the nerve roots. During several years microsurgery of the disc has been effective in the treatment of refractory radiculalgia, and to compete with this procedure familiar to neurosurgeons cervical nucleolysis must convincingly demonstrate that its therapeutic value is at least as good as that of surgery. Finally, the vast majority of cervical disc herniations is made up of free disc fragments located within the meshes of the posterior longitudinal ligament of the spine (transligamentous fragment). Cervical nucleolysis was introduced in France by Bonafe and Lazorthes made enthusiastic by their first studies, and the idea of this procedure, developed by a radio-neurosurgical team, has gradually been gaining ground. The decision to intervene is made when the radiculalgia is recurrent or resistant to a well-conducted medical treatment of several weeks duration. Therefore all disc herniations that would have been treated surgically can be treated by injection of an enzyme. This point is very important, and in fact the well-codified and effective surgical procedure has progressively been abandoned by the operators, in view of the simplicity of nucleolysis and the rapid pain relief it procures.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1992

Pattern of glucose transporter (Glut 1) expression in embryonic brains is related to maturation of blood-brain barrier tightness.

A constant supply of blood-borne glucose is vital to cerebral metabolism. Although transport of glucose into the nervous tissue, effectively separated from the blood by a functional barrier (the blood-brain barrier, BBB), is one of the essential properties of the cerebral endothelium, little is known about its metabolic regulation and developmental expression in the BBB. In this study we provide evidence by immunocytochemistry that the pattern of the brain endothelial glucose transporter in rat brains (BBB-GT), immunologically homologous with the human hepatoma (G2), human erythrocyte transporter (Glut 1), changes with BBB maturation. While the neuroepithelium at embryonic days 12 and 13 shows a high incidence of immuno-detectable BBB-GT, vascularisation of the cerebral anlage and subsequent development of vascular tightness, as evidenced by intravascularly applied horseradish peroxidase and fluorescinated dextrans, is accompanied by a significant reduction of BBB-GT expression in neuroepithelial cells and confinement of BBB-GT expression to the cerebral endothelium. Immunoblots and Northern blots of embryonic brain homogenates corroborate this change in BBB-GT expression in the brain anlage at the time of BBB maturation. However, low molecular weight glucose transporters, presumed to be of non-endothelial origin, are less dramatically reduced. The development of BBB tightness, therefore, seems to play a pivotal role in the pattern of BBB-GT expression during brain differentiation.

Animals↗
PubMed1992

Development of a sensitive peptidase assay: in search of cell associated proteases responsible for the cleavage of preproTGF alpha.

A radiometric assay has been developed for the detection of proteolytic activity capable of releasing transforming growth factor alpha (TGF alpha) from its membrane bound precursor. The assay is dependent upon the separation by thin layer chromatography of hydrolytic products of a nonapeptide substrate containing a radioactive iodinated tyrosine residue as a reporting group N-terminal to an octapeptide which is cognate to the N-terminal cleavage sequence of TGF alpha. We describe the selectivity of the peptidase assay with commercially purified proteases and with cell-associated peptidases, its exquisite sensitivity, and its applicability to defining peptidase activity, which may be responsible for the processing of the membrane-bound prepro TGF alpha. The activity of two different elastases had different profiles which thus may be of use in characterizing them. The characteristics of the intact and extracted HeLa cell assay with respect to time, cell density, and peptidase concentration are defined, as are conditions needed to remove endogenous, confounding, proteolytic activity from the serum used to support cell culture. Intact HeLa cell cultures exhibit both exo- and endo-peptidase activity at approximately equal levels in both sparse and dense monolayer culture without relationship to cell density, and at a level equal to 1-2% of total cell activity of these enzyme classes.

Amino Acid Sequence↗