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Biomedical subjects

M Nilsson

Publications and source records attributed to M Nilsson.

294 records · Page 17Linked to original sources
PubMedDate not supplied

Expression of Vitreoscilla hemoglobin in Escherichia coli enhances ribosome and tRNA levels: a flow field-flow fractionation study.

Asymmetrical flow field-flow fractionation (FFF) was used to separate and quantitate 70S ribosomes, the 30S and 50S subunits, and tRNA in one single analytical procedure. The method was applied to an investigation of the effect of Vitreoscilla hemoglobin (VHb) on the translational machinery of the recombinant Escherichia coli cells. The number of active 70S ribosomes per cell increased dramatically, more than 2-fold, as did also the tRNA levels for the VHb-expressing strain relative to VHb-negative control at the end of a 30-h fed-batch cultivation. This was accompanied by a corresponding 61% increase of a cloned marker enzyme activity. The results clearly indicate that VHb promotes the level of translational components. There should be many other cases in bioengineering where it is important to relate the protein production level in a bioreactor to the ribosome and tRNA levels.

Aerobiosis↗
PubMedDate not supplied

Rheological properties of an apatitic bone cement during initial setting.

One scientific and technological aspect of main importance to the medical profession is to develop injectable calcium phosphate cements (CPCs) to be used through minimally invasive surgery techniques with still suitable mechanical and biodegradable properties. The objective of this research was to study the influence of several technological factors on the injectability of CPCs. This was performed by studying the rheological behavior of the cement pastes during their initial setting. Cement rheology was approached by looking at the creep response of apatitic cements as a function of the shear stress, the liquid-to-solid (L/S) ratio, the temperature and the addition of organic admixtures. Results showed creep experiments to be a finer method to detect characteristic setting times than other established subjective procedures. However, of all transition times detected none but the dough time seems to be of relevant importance when injectability of cement is concerned. Creep experiments also showed that the addition of organic admixtures such as citric acid increased injectability by retarding the hydration time.

Journal Article↗
PubMedDate not supplied

Teletransmission of radiographic images. Preliminary report.

A digital system for transmission of images over telephone lines using a 256 X 256 X 6 bits matrix provided for communication between a county hospital and a university hospital is presented. During a three-month period radiologic diagnostic problems encountered in 62 patients (computed tomography in 46 and conventional radiography in 16) were referred by transmitting selected images from each examination. Transmission of computed tomograms was performed without significant degradation of image quality and there was no loss of diagnostic information. Deterioration of image quality was noticed when conventional films especially those of the chest, were digitized and transmitted, though in no instance were they non-diagnostic. The consultations gave valuable information to the transmitting radiologist in approximately 50 per cent of the cases. Review by the consulted radiologists of all original films in each of the examinations 6 months later did not improve the diagnostic results. Thus, a few carefully selected images, digitized and transmitted over telephone lines, may be sufficient for adequate consultation.

Electronics, Medical↗
PubMedDate not supplied

Quantitative computed tomography in measurement of vertebral trabecular bone mass. A modified method.

Measurement of bone mineral concentration (BMC) can be done by several modalities. Quantitative computed tomography (QCT) can be used for measurements at different sites and with different types of bone (trabecular-cortical). This study presents a modified method reducing the influence of fat. Determination of BMC was made from measurements with single-energy computed tomography (CT) of the mean Hounsfield number in the trabecular part of the L1 vertebra. The method takes into account the age-dependent composition of the trabecular part of the vertebra. As the amount of intravertebral fat increases with age, the effective atomic number for these parts decreases. This results in a non-linear calibration curve for single-energy CT. Comparison of BMC values using the non-linear calibration curve or the traditional linear calibration with those obtained with a pixel-by-pixel based electron density calculation method (theoretically better) showed results clearly in favor of the non-linear method. The material consisted of 327 patients aged 6 to 91 years, of whom 197 were considered normal. The normal data show a sharp decrease in trabecular bone after the age of 50 in women. In men a slower decrease was found. The vertebrae were larger in men than in women.

Adolescent↗