Averaging improves strain images of the biceps brachii using quasi-static ultrasound elastography.

OBJECTIVE: Quasi-static ultrasound elastography is a technique for measuring tissue deformation (strain) under externally applied loading and can be used to identify the presence of abnormalities. The objective of this study was to demonstrate the efficacy of averaging strain images from repeated compression cycles in mitigating user-induced error using quasi-static ultrasound elastography. METHODS: Freehand compressions were performed with an ultrasound transducer on the biceps brachii of nine participants (five males and four females), as well as with a custom automated compression system. Sets of strain images from the freehand techniques were averaged to create single representative images and compared against strain images from the automated compressions using both qualitative and quantitative metrics. RESULTS: Significant improvements in intra-operator repeatability and interoperator reproducibility can be achieved by averaging strain images from four to eight repeated compressions. The resulting strain images did not lose significant image data compared with strain images from single automated compressions. CONCLUSION: Averaging is introduced as a feasible and appropriate technique to improve strain image quality without sacrificing important image data. ADVANCES IN KNOWLEDGE: Simple averaging of multiple freehand elastography measures can achieve a similar degree of accuracy, repeatability and reproducibility as that of more awkward and expensive automated methods. The resulting elastograms can be used to obtain a more accurate and complete diagnosis without additional cost to the doctor or the patient.

Antimicrobial effects of murine mesenchymal stromal cells directed against Toxoplasma gondii and Neospora caninum: role of immunity-related GTPases (IRGs) and guanylate-binding proteins (GBPs).

Mesenchymal stromal cells (MSCs) have a multilineage differentiation potential and provide immunosuppressive and antimicrobial functions. Murine as well as human MSCs restrict the proliferation of T cells. However, species-specific differences in the underlying molecular mechanisms have been described. Here, we analyzed the antiparasitic effector mechanisms active in murine MSCs. Murine MSCs, in contrast to human MSCs, could not restrict the growth of a highly virulent strain of Toxoplasma gondii (BK) after stimulation with IFN-γ. However, the growth of a type II strain of T. gondii (ME49) was strongly inhibited by IFN-γ-activated murine MSCs. Immunity-related GTPases (IRGs) as well as guanylate-binding proteins (GBPs) contributed to this antiparasitic effect. Further analysis showed that IFN-γ-activated mMSCs also inhibit the growth of Neospora caninum, a parasite belonging to the apicomplexan group as well. Detailed studies with murine IFN-γ-activated MSC indicated an involvement in IRGs like Irga6, Irgb6 and Irgd in the inhibition of N. caninum. Additional data showed that, furthermore, GBPs like mGBP1 and mGBP2 could have played a role in the anti-N. caninum effect of murine MSCs. These data underline that MSCs, in addition to their regenerative and immunosuppressive activity, function as antiparasitic effector cells as well. However, IRGs are not present in the human genome, indicating a species-specific difference in anti-T. gondii and anti-N. caninum effect between human and murine MSCs.

Suicide in a society in transition.

In Greenland, the rapid socio-cultural change of the last 50 years has been paralleled by an increasing number of suicides. The suicide rates in Greenland are now among the highest in the world. Especially among men aged 15-24 suicide rates are dramatically high. In the present study, information on the psycho-social background of suicides is provided based on a review of death certificates and police reports for the period 1993-95. Dysfunctional social networks seem to play a predominant role among suicides. Being disconnected from community and family ties seems to increase the vulnerability of young people in Greenland. In addition, temporal trends of suicide rates are described for the different regions of Greenland. The findings are discussed in relation to the societal and cultural transition of the society.

The effect of a change in ambient temperature on blood pressure in normotensives.

The aim of this study was to investigate the influence of ambient temperature on blood pressure (BP). BP measurements were taken in 20 normotensive volunteers who stayed in Greenland for a 6-week period. Measurements of systolic (SBP), diastolic (DBP) and heart rate (HR) were taken before (3 sessions), during (7-8 sessions) and after the journey (3 sessions). Each session consisted of five BP measurements in the supine position after at least 5 min rest. All five readings were averaged. Temperature data (mean +/- s.d.), collected from meteorological services, before, during and after Greenland were 15.7 +/- 0.6, 0.5 +/- 1.5 and 8.2 +/- 0.8 degrees C. SBP values were 116 +/- 7.0, 122 +/- 7.6 and 116 +/- 7.4 and DBP 63 +/- 5.2, 66 +/- 5.8 and 65 +/- 6.5 mm Hg, respectively. HR amounted to 58 +/- 7.4, 61 +/- 6.7 and 60 +/- 7.4 bpm. Significant differences existed between, before and during for SBP and DBP and between, during and after for SBP. Readings were grouped in four categories based on the temperature at the time of reading. For SBP as well as DBP a clear dose-response relationship was demonstrated between low temperature and high BP, although for DBP only a few correlations were statistically significant. Mean correlation coefficients for SBP and DBP against temperature were -0.44 (P < 0.001) and -0.27 (P < 0.005), respectively. our results are in favour of a moderate, but both significant and relevant increase in sbp and dbp when moving from higher to lower ambient temperature.

Cholesterol lowering action of HOE 402 in the normolipidemic and hypercholesterolemic golden Syrian hamster.

The potent hypolipidemic activity of HOE 402 (4-amino-2-(4, 4-dimethyl-2-oxo-1-imidazolidinyl)pyrimidine-5-N-(trifluoromethyl-phenyl ) carboxamide monohydrochloride), which was previously demonstrated in rat and rabbit, was investigated in noncholesterol and cholesterol fed male hamsters. In normolipidemic hamsters fed a low cholesterol chow diet containing 0.10% or 0.15% HOE 402 for 3 weeks, the plasma total cholesterol level fell by 13% and 20% respectively, but no effect on hepatic total cholesterol content was detected. Hepatic sterol synthesis was increased 3-fold in hamsters fed 0.15% HOE 402. In hamsters fed a chow diet containing 0.25% cholesterol for 3 weeks, the plasma cholesterol level increased to 226 mg/dl (compared to 123 mg/dl in their chow fed controls) and the liver cholesterol content was 26.2 mg/g compared to 2.3 mg/g in the control group. However, 0.15% HOE 402 led to a 48% reduction and 0.20% HOE 402 to a 80% reduction, in total hepatic cholesterol concentration. There was a 43% fall in plasma cholesterol level being observed with the higher HOE 402 dose. Using the dual isotope plasma ratio method, no inhibition of intestinal cholesterol absorption by HOE 402 was found, either in the noncholesterol fed or in the cholesterol fed hamsters. Cholesterol feeding diminished the whole LDL animal clearance to 393 +/- 17 microliters/h per 100 g animal (control 666 +/- 81 microliters/h per 100 g). When treated with 0.20% HOE 402, the whole animal LDL clearance rate was enhanced 2.3-fold to 824 +/- 66 microliters/h per 100 g. In the hamsters fed 0.25% cholesterol alone whole liver LDL receptor activity was suppressed to 63 +/- 5%, compared to that in the untreated controls (100%). The addition of 0.20% HOE 402 to the cholesterol enriched diet not only reversed this suppression, but resulted in a marked stimulation of liver receptor activity to 165 +/- 15% (whole body LDL receptor activity 141 +/- 10%). These results indicate that HOE 402 exerts its lipid lowering effect by a more direct activation on hepatic LDL receptor activity rather than by an indirect intestinal effect on cholesterol absorption.

Hypolipidemic activity of HOE-402 is mediated by stimulation of the LDL receptor pathway.

HOE-402 (4-amino-2-[4,4-dimethyl-2-oxo-1-imidazolidinyl]-pyrimidine-5-N- [trifluoromethylphenyl]-carboxamide-monohydrochloride) has been shown to exhibit hypolipidemic action in heterozygous Watanabe heritable hyperlipidemic rabbits. In all animals, elevated cholesterol levels were reduced to normal (from 3.0 to 1.5 mmol/L) after 3 weeks of HOE-402 treatment. This was due entirely to reduction of low density lipoprotein (LDL) cholesterol and was paralleled by accelerated removal of plasma 125I-LDL. This reduction of LDL levels was not found in homozygous LDL receptor-defective animals, emphasizing the necessity of a functional LDL receptor system for the hypolipidemic action. The effect of HOE-402 on LDL receptor activity in the cultured hepatoma cell line HepG2 was also determined. When cells were incubated with plasma from treated animals (containing cholesterol 1.5 mmol/L and HOE-402 80 ng/mL), high-affinity cell-surface binding sites for LDL were induced more than threefold, as shown by Scatchard analysis of cell-surface binding data. Induction of the LDL receptor was detectable after 6 hours and was 300% after 18 hours. This induction was specific for LDL, as 125I-transferrin and [59Fe]transferrin were internalized normally in HOE-402-treated cells. The increase of LDL receptor protein was related to induced LDL receptor mRNA levels (400%), as shown by quantification of Northern blotting experiments. These findings suggest that HOE-402 mediated its hypolipidemic action mainly via the LDL receptor pathway. It enhanced mRNA levels for LDL receptor, hence increasing its synthesis, which subsequently resulted in reduced plasma LDL levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Unexpected translation initiation within the coding region of eukaryotic genes expressed in Escherichia coli.

When expressing several eukaryotic genes in Escherichia coli, we observed N-terminally truncated proteins which were attributed to translation initiation at downstream AUG codons. These AUG codons are located between 4 and 20 nucleotides 3' from sequences resembling bacterial SD elements. Although the presence of such downstream SD sequences is not sufficient for downstream initiation to occur, in two cases their removal abolishes synthesis of the truncated proteins. In one construct, a potential hairpin-loop structure is likely to inhibit translation initiation at the correct site and favor downstream initiation.

The nucleotide sequence of cDNA coding for preproinsulin from the primate Macaca fascicularis.

DNA complementary to preproinsulin messenger RNA from the primate Macaca fascicularis has been cloned into the PstI endonuclease site of the plasmid pBR322. One clone contains the entire preproinsulin coding region as well as 59 nucleotides of the 5'-untranslated region. The results predict an amino acid sequence for the Macaca fascicularis preproinsulin and establish for the first time that the primary structures of human and primate insulins are identical. The two amino acid exchanges between human and primate preproinsulins are restricted to the pre- and the C-peptide, respectively.

Site-specific mutagenesis on cloned DNAs: generation of a mutant of Escherichia coli tyrosine suppressor tRNA in which the sequence G-T-T-C corresponding to the universal G-T-pseudouracil-C sequence of tRNAs is changed to G-A-T-C.

We have cloned the Escherichia coli tyrosine-inserting amber suppressor tRNA gene into the recombinant single-strand phage M12mp3. By using the M13mp3SuIII+ recombinant phage DNA as template and an oligonucleotide bearing a mismatch as primer, we have synthesized in vitro an M13mp3SuIII heteroduplex DNA that has a single mismatch at a predetermined site in the tRNA gene. Transformation of E. coli with the heteroduplex DNA yielded M13 recombinant phages carrying a mutant suppressor tRNA gene in which the sequence G-T-T-C, corresponding to the universal G-T-pseudouracil-C sequence in E. coli tRNAs, is changed to G-A-T-C. The mutant DNA has been characterized by restriction mapping and by sequence analysis. In contrast to results with the wild-type suppressor tRNA gene, cells transformed with recombinant plasmids carrying the mutant tRNA gene are phenotypically Su-. Thus, the single nucleotide change introduced has inactivated the function of the tRNA gene. By using E. coli minicells for studying the expression in vivo of cloned tRNA genes, we have found that cells transformed with recombinant plasmids carrying the mutant tRNA gene contain very little, if any, mature mutant suppressor tRNA. In contrast, the predominant low molecular weight RNA in cells transformed with recombinant plasmids carrying the wild-type suppressor tRNA gene is the mature tyrosine suppressor tRNA. Thus, while our results imply an important role for the G-T-pseudouracil-C sequence common to all E. coli tRNAs, whether this sequence is essential for tRNA biosynthesis, tRNA stability in vivo, or tRNA function remains to be determined. The procedures used to generate the mutant should be of general application toward site-specific mutagenesis on cloned DNAs, including regions that possess high degrees of secondary structure. In addition, the frequency of mutants among the progeny is high enough to enable one to identify and isolate site-specific mutants on any cloned DNA without requiring phenotypic selection.

Comparison of tRNA nucleotidyltransferase from Escherichia coli and Lactobacillus acidophilus.

Purification of tRNa nucleotidyltransferase from Lactobacillus acidophilus ATCC 4963 and Escherichia coli MRE 600 by preparative polyacrylamide gel electrophoresis is described. Both enzymes gave a single band on analytical polyacrylamide-gel electroesis and sodium dodecylsulfate gels. Chromatography of the high speed supernatant from Lactobacillus at low salt concentrations gave three enzyme fractions of molecular weights about 45 000, 90 000, and 120 000. At 1M NaCl only the first enzyme fraction was found. Kinetic data for both enzymes are given.

Purification of RNAase II by preparative polyacrylamide gel electrophoresis.

Purification of RNAase II to electrophoretic homogeneity is described. The exonuclease is activated by K+ and Mg2+ and hydrolyses poly(A) to 5'-AMP, exclusively as described by Nossal and Singer (1968, J. Biol. Chem. 243, 913--922). To separate RNAase II from ribosomes, DEAE-cellulose chromatography was used. Two additional chromatographic steps give a preparation that yields 10 bands after analytical polyacrylamide gel electrophoresis. Preparative polyacrylamide gel electrophoresis resulted in a final preparation which on analytical polyacrylamide gels gives a single band. A molecular weight of 76 000 +/- 4000 was obtained from Sephadex G-200 chromatography, with three bands from sodium dodecyl sulfate (SDS) denaturation and SDS gel electrophoresis. The subunits have a molecular weight of 40 000 +/- 2000, 33 000 +/- 2000, and 26 000 +/- 1000. The enzyme thus appears to consist of three dissimilar subunits.