Dual energy CT and research of the bone marrow edema: Comparison with MRI imaging

Aims

To evaluate the diagnostic accuracy of the Dual Energy Computed Tomography (DECT) in the research of the bone marrow edema.

Methods and Material

The MRI images of 100 patients with episodes of articular and or bone pains with or without traumatic lesion were prospectively evaluated during a period between March 2018 and February 2019. In the presence of bone marrow edema, a DECT was performed. The measurement of the density of the bone marrow edema in the DECT was compared with healthy bone in the same patient by two operators.

Result

The DECT and MRI images of 15 patients with bone marrow edema were compared. The mean of pathologic bone marrow edema was 1008.20 (Standard Deviation (SD) 23.00), for healthy bone marrow 947.53 (SD 16.42), and t = 11.75, with a statistical significance P < 0.05 (Statistical significance 95%). The agreement between the measurements of the two radiologists has a statistical significance (P < 0.05).

Conclusion

The DECT presents an excellent diagnostic accuracy to detect the bone marrow edema, comparable to MRI. The utility of these recent possibilities is maximum where access to MRI is still very difficult.

gyrA mutations in high-level fluoroquinolone-resistant clinical isolates of Escherichia coli

Double mutations in the quinolone resistance determining region of the gyrase A gene (gyrA) have recently been reported to be associated with high-level resistance to fluoroquinolones in clinical isolates of Escherichia coli. We examined the type and frequency of such mutations in a large number of clinical isolates that were obtained from ten different geographical locations and had been genotypically characterized by pulsed field gel electrophoresis (PFGE) of chromosomal DNA digests. Of 36 isolates with ofloxacin MICs > or = 4 mg/L that represented at least 24 distinct genotypes, 35 had double mutations at amino acid codons 83 and 87 of gyrA, while two isolates with ofloxacin MICs of 0.5 and 4 mg/L, respectively, each had a single mutation at codon 83. Mutations at codon Ser-83 were uniform, resulting in substitution by Leu. The additional mutations at amino acid codon 87 in the 35 double-mutants were diverse, resulting in Asp-87 substitutions by residues Asn (23 isolates), Gly (7 isolates), Tyr (4 isolates), or His (1 isolate) without a discernable correlation with fluoroquinolone MICs or with phenotypic resistance to chemically unrelated antibacterial agents. Maximal differences between MICs of double-mutants with the same amino acid substitution were eight-fold. The changes of amino acid residues at codon Asp-87 differed between individual patient isolates with the same genotype (and similar MICs), suggesting that the amino acid codon 87 mutations (and possibly the development of high-level fluoroquinolone resistance) might have occurred after the transmission and sharing of a precursor strain carrying the Ser-83-->Leu mutation.

Molecular epidemiology of fluoroquinolone-resistant Escherichia coli bloodstream isolates from patients admitted to European cancer centers

Previous reports have suggested an increasing incidence of highly fluoroquinolone-resistant Escherichia coli causing bacteremia among cancer patients on prophylactic therapy. We used genotyping by pulsed-field gel electrophoresis of chromosomal DNA digests and random amplified polymorphic DNA fingerprinting to study clonal relationships among such isolates obtained at 10 cancer centers located across Europe and the Middle East. Analysis by both methods indicated that isolates from different centers were genotypically unrelated to each other. There were five centers from which more than one individual patient isolate was available, and most demonstrated significant within-center genetic diversity of strains. Strains shared among patients could be identified at two centers. At the center with the largest number of bloodstream isolates from cancer patients available, fluoroquinolone-resistant control isolates from surgical patients and fluoroquinolone-susceptible control isolates from patients admitted to medical services during the same time period were unrelated to resistant cancer patient isolates and to each other as well. A substantial number of fluoroquinolone-resistant isolates (19 of 58) were nontypeable by pulsed-field gel electrophoresis. Fluoroquinolone resistance was commonly associated with multiple antibiotic resistance to chemically unrelated antibacterial agents irrespective of the origin of the isolates.

Characterization of coagulase-negative staphylococci causing nosocomial infections in preterm infants

The species spectrum, antibiotic susceptibility, and genomic profile of coagulase-negative staphylococci (CNS) isolated from infected preterm infants were compared with those obtained in CNS from nursery personnel. Staphylococcus epidermidis was the predominant species in the 66 investigated preterm infants (171 isolates), accounting for 64% of all isolates. A high proportion of Staphylococcus haemolyticus (32%) could be detected. In contrast to the results in patients, the spectrum in nursery personnel was broad and included more species of CNS. All isolates of CNS from preterm infants demonstrated a low rate of susceptibility to the beta-lactam antibiotics (2% sensitivity to penicillin and 6% sensitivity to oxacillin). Sensitivity to gentamicin (9%) was also rare. An unexpected observation was susceptibility to teicoplanin in only 70% of all CNS isolated from patients due to the high proportion of Staphylococcus haemolyticus. Analysis of the genomic profile of 33 isolates of Staphylococcus haemolyticus by pulsed-field gel electrophoresis revealed a relationship between the strains. An outbreak of one particular strain of Staphylococcus haemolyticus in the neonatal intensive care unit investigated can therefore not be excluded.

Terminal redundancy and circular permutation of mycoplasma virus L3 DNA

This communication reports the physical map of mycoplasma virus L3 (MV-L3) DNA derived from restriction patterns obtained by digestion with seven different restriction endonucleases. The length of the restriction map is 36,200 bp in contrast to the contour length of native MV-L3 DNA molecules which is 39,400 bp as determined by electron microscopy. The difference in length of 3,200 bp (corresponding to 8.1% of the native viral DNA contour length) is explained by terminal redundancy. It was possible to clone all fragments from particular restriction patterns into Escherichia coli vector pAT153, an indication of circular permutation within a population of MV-L3 DNA. However clear evidence has been obtained from the molar ratios of fragments and from hybridization experiments. We suppose that viral DNA is packaged from a concatemeric precursor molecule starting at a specific site called pac.

Release of mycoplasmavirus L1 upon transfection of Acholeplasma laidlawii with homologous and heterologous viral DNA

This communication reports on the release of Mycoplasmavirus L1 after infection of Acholeplasma laidlawii with purified L3 virus. Release also occurred after transfection with certain restriction fragments from MV-L3 and MV-L1 genomes. Since circular molecules are efficiently taken up in polyethylene glycol-mediated transfection, inducing fragments were applied cloned in E. coli plasmids. Release was also observed after electroporation of cells incubated with MV-L1 replicative intermediate DNA and linear MV-L3 DNA isolated from virus particles, respectively. Released MV-L1 viruses were identified after virus plaque formation on indicator lawns according to plaque morphology and hybridization with labeled viral DNA probes as well as by DNA restriction analysis. Uninfected and untransfected cells from six laboratory strains of A. laidlawii (including a MV-L1 resistant one) were examined for the presence of MV-L1 DNA. They all bear MV-L1 DNA integrated in their genomes.

Electroporation-mediated transfection of Acholeplasma laidlawii with mycoplasma virus L1 and L3 DNA

In contrast to mycoplasma virus L1 and L2 circular DNA, mycoplasma virus L3 linear DNA is not biologically active in polyethylene glycol-mediated transfection. Electroporation of Acholeplasma laidlawii, however, leads to plaque formation after incubation with L3 DNA. The efficiency of electroporation-mediated transfection is 1/10 that of polyethylene glycol-mediated transfection as estimated with L1 DNA. Trypsin treatment of cells before DNA addition increases the efficiency of DNA uptake.

Increased amounts of small polydisperse circular DNA (spcDNA) in angiofibroma-derived cell cultures from patients with tuberous sclerosis (TS)

Much greater amounts of small polydisperse circular DNA (spcDNA) have been detected, in cell cultures derived from angiofibromas of six patients with tuberous sclerosis (TS) than in those from the skin of these patients or from the skin of 11 healthy donors. This observation could be confirmed by spreading the DNA of appropriate fractions from CsCl density gradients. The findings suggest the existence of a relationship between the chromosomal instability observed in angiofibroma cultures and the mobilization of spcDNA.

Recognition of covalent insulin-receptor complexes on viable adipocytes by anti-insulin antibodies

Isolated rat adipocytes were photo-affinity-labelled with B2-(4-azido-2-nitrophenylacetyl)-des-PheB1-insulin or B29-(4-azido-2-nitrophenylacetyl)insulin. Four anti-insulin antibodies (3 monoclonal, 1 polyclonal) were tested for their ability to inhibit the persistent stimulation of lipogenesis caused by the covalently bound insulin [Brandenburg et al. (1980) Nature (London) 286, 821-822]. The polyclonal and 2 monoclonal antibodies, directed against the C-terminus of the B-chain, gave a significant depression, while one antibody, directed against the region A(8-10), was without effect. Under reversible conditions, without irradiation, all antibodies completely inhibited lipogenesis. For the polyclonal antibody this is shown in a dose-dependent way. It is concluded that the effective antibodies can recognize their epitope because it is accessible on the surface of the complex and does not represent part of the receptor-binding surface of insulin. This binding leads to interference with the generation and/or transmittance of the biological signal.

Structure of viroid replicative intermediates: physico-chemical studies on SP6 transcripts of cloned oligomeric potato spindle tuber viroid

The structure and structural transitions of transcripts of cloned oligomeric viroid were studied in physico-chemical experiments and stability calculations. Transcripts of (+) and (-) polarity, from unit up to sixfold length, were synthesized from DNA clones of the potato spindle tuber viroid (PSTV) with the SP6 transcription system. Their structural properties were investigated by optical denaturation curves, high performance liquid chromatography (HPLC), electron microscopy, sedimentation-diffusion equilibrium and velocity sedimentation. Secondary structures of the RNAs and theoretical denaturation curves were calculated using an energy optimization program. The secondary structure of lowest free energy for unit length and oligomeric transcripts is a rod-like structure similar to that of the mature circular viroids. When this structure is used as a model for calculations, there is a large degree of agreement between the theoretical and the experimental denaturation curves. At high temperatures, however, (+) strand transcripts exhibited a transition which was more stable than expected from the calculations or than was known from curves of mature viroids. This transition arises from a rearrangement of the central conserved region of viroids to a helical region of 28 stable base pairs either intermolecularly leading to bimolecular complexes, or intramolecularly giving rise to a branched secondary structure. The rearrangement could be detected by electron microscopy, HPLC, and analytical ultracentrifugation. The helical region serves to divide up the oligomeric (+) strand into structural units which may be recognized by cleavage and ligation enzymes which process the oligomeric intermediates to circular mature viroids.

Biological action and fate of photoaffinity-labelled insulin-receptor complexes

Covalent linking of two photoactivatable insulin derivatives, B2-(2-nitro,4-azidophenylacetyl)-des-PheB1-insulin and B29-(2-nitro,4-azidophenylacetyl)-insulin to viable rat adipocytes gives a system, which contains a fixed stoichiometry between hormone and receptor. The biological signal of prolonged lipogenesis has been used to study several aspects of insulin binding and action: the role of the site of the crosslink between insulin and receptor, recognition of bound photoinsulin by anti-insulin antibodies, the half-life of the biologically active complex, the pH-dependence of the biological signal, and the possible role of internalization. Furthermore, the effect of trypsin on the insulin receptor, as well as the insulin-receptor complex, has been investigated and a refined model of the receptor is presented.

Viroid replication: equilibrium association constant and comparative activity measurements for the viroid-polymerase interaction

The binding and replication of purified potato spindle tuber viroid (PSTV) by DNA-dependent RNA polymerase II from wheat germ was studied in analytical ultracentrifugation experiments and in vitro transcription assays. The equilibrium association constant for the viroid-polymerase interaction is 1.9 X 10(7) M-1. Both ultraviolet and fluorescent monitoring during the sedimentation experiments showed two distinguishable viroid-polymerase complexes. These are interpreted as resulting from a 1:1 and 2:1 enzyme-to-viroid binding stoichiometry. A265/A280 ratios across the sedimenting boundaries, the sedimentation velocity of the complexes, as well as electron microscopic data support this interpretation. The role of viroid secondary structure in enzyme binding and polymerization is discussed in the light of these results and compared with binding and polymerization data for virusoid RNA, single- and double-stranded RNA, and double-stranded DNA.

The biological potency of covalent insulin-receptor complexes. Dependence on site of cross-linkage

A radioactive photosensitive insulin analogue, 125I-N epsilon B29-(4-azido-2-nitrophenyl-acetyl)insulin, was covalently bound to the receptors of isolated rat adipocytes by irradiation with UV light. This caused a stimulation of lipogenesis. The relative potency of the covalent complexes to that of normal reversible complexes was calculated by comparing the amounts of radioactivity required to be covalently or reversibly bound by adipocytes to cause the same levels of stimulation. For several different occupancies , this relative potency was constant at 50 +/- 3%. Previous studies had shown that the relative potency of covalently bound 125I-N alpha B2-(4-azido-2- nitrophenylacetyl )des- PheB1 -insulin was only 25 +/- 4% under identical conditions. This demonstrates that the sites of crosslinking have a marked effect on the potency of the covalent hormone-receptor complex. It appears that attachment through the C-terminus of the B-chain leads to a better stabilization of the biologically active form than linking through the more flexible N-terminus.

Biological potency of covalently linked insulin-receptor in rat adipocytes. Comparison with the potency of reversible complexes

Irradiation of photoreactive insulin derivatives in the presence of isolated rat adipocytes produces a prolonged stimulation of lipogenesis in the cells even after exogenous and reversibly bound derivative has been removed by extensive washing. The quantitative nature of this response has now been studied using 125I-B2(2-nitro-4-azidophenylacetyl)des-PheB1-insulin. This derivative possesses nearly full biological potency and binding affinity prior to irradiation. After covalent linkage to adipocytes the efficacy of the derivative is reduced to 25 +/- 4% of the reversibly bound derivative, viz. 4-times as much needs to be covalently associated as reversibly bound to induce the same level of stimulation of lipogenesis. This reduced relative molar potency is due to a reduced ability of specific covalent insulin-receptor complexes to trigger a response.

Biological activity of covalently-linked insulin-receptor complexes in rat adipocytes. Effect of pH

The relative molar potencies of covalently and reversibly-bound insulin-receptor complexes were studied as a function of pH. The insulin derivatives used were 125I-B2 (2-nitro-4-azidophenylacetyl)des-PheB1-insulin and 125I-B29(2-nitro-4-azidophenylacetyl)des-PheB1-insulin. The potencies of both types of reversible complexes were effectively identical and constant between pH 7 and 8. The relative potency of the covalent B2-complex increased from 25 to 75%, and of the covalent B29 complex from 30 to nearly 100%. This indicates that the covalently linked partners in the complex are able to flex about the cross-linkages. Variations in the potency are due to variations in the number of correctly associated, reversibly or covalently bound insulin-receptor complexes. The form of the pH dependance suggests that an ionizable group, possibly an amino group, must be deprotonated to allow effective interaction.

An unusual symmetric recombinant between adenovirus type 12 DNA and human cell DNA

On purification of human adenovirus type 12 (Ad12) by equilibrium sedimentation in CsCl density gradients, two bands of particles, Ad12-3 and Ad12-3a, are observed. The particles from band Ad12-3a contain a recombinant of human host cell DNA and of Ad12 DNA. The human cell DNA sequences contain repetitive DNA recurring 200 to 500 times in cellular DNA. Ad12 DNA and the recombinant genomes exhibit the same or similar lengths. This finding suggests that a constant amount of DNA is packaged into complete Ad12 particles. On cleavage of KB cellular DNA with EcoRI, BamHI, HinfI, Msp I, Mbo I Pst I, or Bgl II, the (32)P-labeled cellular DNA from Ad12-3a particles hybridizes on Southern blots to distinct bands of KB DNA. There is also less-specific background hybridization that is not observed in the control. The cellular DNA from Ad12-3a particles is not methylated, whereas the same cellular sequences in KB cell DNA appear to be extensively methylated. On denaturation and renaturation, the recombinant DNA molecules are converted to molecules half as long as Ad12 DNA, as determined by gel electrophoresis and electron microscopy. The recombinant DNA molecules were terminally labeled by exonuclease III treatment and subsequent refilling of the depleted segments with [(32)P]dNTPs by using DNA polymerase I (Klenow fragment). When these molecules were cleaved with EcoRI, BamHI, Msp I, or Pst I, only one terminal DNA fragment was found to be labeled. The results of partial digestion experiments using Msp I, HinfI, or Mbo I are consistent with a model in which 700-1150 base pairs from the left terminus of Ad12 DNA are linked to host cell DNA containing repetitious sequences, and this structure is symmetrically duplicated as a large inverted repeat of the type ABCDD'C'B'A'. The Ad12 DNA sequences are flanking the entire molecule, which consists mainly of human KB cell DNA. The recombinants appear to be stable on serial passage of the virus preparation for many years, although variations in the sequence of the recombinants occur. These symmetric recombinant (SYREC) molecules suggest a way to use adenovirus DNA as a eukaryotic vector. Their occurrence provides further evidence for the generation of virus-host DNA recombinants and may help elucidate the role this interaction may have in adenovirus replication and oncogenesis.

Structural and biological properties of mycoplasmavirus MVL3: an unusual virus-procaryote interaction

The kinetics of adsorption and growth of mycoplasmavirus MVL3 in Acholeplasma laidlawii 1305/68 host cells have been studied with one-step growth, premature lysis, and single-burst experiments. The virus was found to kill infected host cells. Virus release starts 90 min after infection and continues for about 10 to 15 h. Hence, virus production is unlike the classical lytic bacteriophages and instead resembles nonlytic cytocidal animal viruses. Structural details of the virus are described, and the molecular weight of the viral linear DNA has beenfound to be 26 x 10(6).

Viroids are single-stranded covalently closed circular RNA molecules existing as highly base-paired rod-like structures

Viroids are uncoated infectious RNA molecules pathogenic to certain higher plants. Four different highly purified viroids were studied. By ultracentrifugation, thermal denaturation, electron microscopy, and end group analysis the following features were established: (i) the molecular weight of cucumber pale fruit viroid from tomato is 110,000, of citrus exocortis viroid from Gynura 119,000, of citrus exocortis viroid from tomato 119,000 and of potato spindle tuber viroid from tomato 127,000. (ii) Viroids are single-stranded molecules. (iii) Virods exhibit high thermal stability, cooperativity, and self-complementarity resulting in a rod-like native structure. (iv) Viroids are covalently closed circular RNA molecules.

Restriction and modification in B. subtilis. The biochemical basis of modification against endo R. Bsu R restriction

The content of 5-methylcytosine (5MC) and 6-methyladenine (6MA) in modified and nonmodified DNAs from B. subtilis and B. subtilis phage SPP1 were determined. Non-modified SPP1-O DNA contains about 15 5MC residues/molecule. Each modified SPP1-R DNA molecule carries 190 modification specific methyl groups. This number is sufficient to account for modification of the 80 restriction sites in SPP1 DNA (Bron and Murray, 1975) against endo R-Bsu R, assuming each modified site contains two 5MC residues. Resistance of SPO1 DNA against endo R-Bsu R restriction both in vivo and in vitro is probably not due to methylation of endo R-Bsu R recognition sites.

Studies on bacteriophage T7 DNA synthesis in vitro. II. Reconstitution of the T7 replication system using purified proteins

DNA synthesis in vitro using intact duplex T7 DNA as template is dependent on a novel group of three phage T7-induced proteins: DNA-priming protein (activity which complements a cell extract lacking the T7 gene 4-protein), T7 DNA polymerase (gene 5-protein plus host factor), and T7 DNA-binding protein. The reaction requires, in addition to the four deoxyribonucleoside triphosphates, all four ribonucleoside triphosphates and is inhibited by low concentrations of actinomycin D. Evidence is presented that the priming protein serves as a novel RNA polymerase to form a priming segment which is subsequently extended by T7 DNA polymerase. T7 RNA polymerase (gene 1-protein) can only partially substitute for the DNA-priming protein. At 30 degrees C, deoxyribonucleotide incorporation proceeds for more than 2 hours and the amount of newly synthesized DNA can exceed the amount of template DNA by 10-fold. The products of synthesis are not covalently attached to the template and sediment as short (12S) DNA chains in alkaline sucrose gradients. Sealing of these fragments into DNA of higher molecular weight requires the presence of E.coli DNA polymerase I and T7 ligase. Examination of the products in the electron microscope reveals many large, forked molecules and a few "eye"-shaped structures resembling the early replicative intermediates normally observed in vivo.

A quantitative theory of transfection in B. subtilis

A theory of transfection is developed which describes three different types of experiments in transfection: The concentration dependence of transfection, transfection with marker rescue, and the mapping function in transfection crosses. The theory is applicable to transfection systems exhibiting quadratic or higher order dose response (APP1, AP50, SP82). It pictures the essential process in transfection as follows: transfecting DNA molecules, having suffered inactivating events during uptake or intracellularly, have to recombine prior to replication under elimination of these lesions. The probability for recombination, successful in this sense, is calculated as a function of the number of DNA molecules within the competent cell, the mean number of inactivating events per DNA molecule, and the crossover probability per nucleotide. Under the assumption of random distribution of inactivating events over the population of DNA molecules and homogeneous crossover probabilities the theory explains on a quantitative basis a number of experimental observations in transfection, as for instance the relative efficiencies of different helper phage in transfection with marker rescue, the third order concentration dependence in SP50 transfection, and the high recombination frequencies observed in transfection crosses.