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Biomedical subjects

H Pettersson

Publications and source records attributed to H Pettersson.

At least 19 recordsLinked to original sources
PubMed1997

A high ratio of insulin-like growth factor II/insulin-like growth factor binding protein 2 messenger RNA as a marker for anaplasia in meningiomas.

Insulin-like growth factors (IGFs) I and II have been implicated as autocrine or paracrine growth promoters. These growth factors bind to specific receptors, and the response is modulated by interaction with IGF-binding proteins (IGFBPs). We observed a strong correlation between anaplastic/atypical histopathology and a high IGF-II/IGFBP-2 mRNA ratio in a set of 68 sporadic meningiomas. A strong correlation was also found between clinical outcome and IGF-II/IGFBP-2 ratio, whereas previously used histochemical markers were less correlated to outcome. We suggest that a high IGF-II/IGFBP-2 mRNA ratio may be a sign of biologically aggressive behavior in meningiomas that can influence treatment strategies. We propose that low IGFBP-2 levels in combination with increased levels of IGF-II would result in more free IGF-II and consequently greater stimulation of proliferation.

Adult↗
PubMed1997

Haemophilia prophylaxis in young patients--a long-term follow-up.

OBJECTIVES: To review long-term prophylactic factor treatment in young patients with severe haemophilia A and B, focusing on the orthopaedic and radiological outcome. DESIGN: We received 34 patients with severe haemophilia A (n = 29) and B (n = 5), aged 7-22 years. Age at start of treatment was 1-4.5 years. Dosages of factor concentrate (F VIII and F IX, respectively) were 25-40 IU/kg body weight, three times a week for haemophilia A and twice a week for haemophilia B. The patients had been checked annually over a 5-year period (1990-95). Orthopaedic and radiological joint scores were evaluated according to recommendations by the World Federation of Haemophilia. SETTING: All results were obtained at the Department for Coagulation Disorders, University of Lund, Malmö University Hospital, Malmö, Sweden. RESULTS: Orthopaedic and radiological joint scores were found to have remained unchanged during follow-up in almost all patients and to be still zero (i.e. no unaffected joints) in 79% (n = 27) of the patients. CONCLUSION: There is a growing international consensus haemophilic arthropathy can be prevented by administering early high-dose prophylaxis. The results of the present investigation strongly support this opinion.

Adolescent↗
PubMed1997

Time-resolved white light transillumination for optical imaging.

PURPOSE: To describe a new breast-imaging method with the potential of multi-spectral optical transillumination based on a time-resolved technique. MATERIAL AND METHODS: A breast phantom was irradiated with ultra-short laser pulses of white light generated by self-phase modulation of an incident high-power laser pulse in water. Time-resolved detection of the transmitted light was performed. Contrast resolution was studied using different absorbers located inside the breast phantom. RESULTS AND CONCLUSION: The results showed that simultaneous, multi-spectral transillumination is possible. The technique can also be used for measurements of optical properties in tissue.

Breast↗
PubMed1997

Absorption and metabolism of nivalenol in pigs.

The absorption and metabolism of nivalenol (NIV) were studied in pigs fed 0.05 mg NIV/kg BW, twice daily. Blood samples were taken during the first and third day, through catheters in the hepatic portal vein and peripheral mesenteric artery. Nivalenol was detected in most of the earliest blood samples, taken twenty minutes after the start of feeding. During 7.5 hrs after feeding, 11-43% of the NIV dose was absorbed. The systemic peak concentrations were 3-6 ng NIV/ml, mostly occurring 2.5-4.5 h after feeding. Sixteen hours after feeding, NIV was still being absorbed from the intestine, and the systemic concentrations were 1-3 ng NIV/ml. Nivalenol was mainly excreted in faeces, which contained concentrations up to 3.2 mg NIV/kg. No metabolites of NIV were found in plasma, urine, and faeces, either as glucuronic acid or sulphate conjugates, or as de-epoxy-NIV, indicating a lack of metabolism. The feeding of NIV did not cause feed refusal, and measured clinical plasma parameters were within the normal ranges.

Alanine Transaminase↗
PubMed1997

Transformation of nivalenol by gastrointestinal microbes.

The capacity of the gastrointestinal microflora of pig, cow, and chicken to metabolize nivalenol (NIV) and deoxynivalenol (DON) was studied both in vivo and in vitro. Before feeding NIV to pigs, no metabolites of NIV or DON were formed in anaerobic incubates of the toxins with the pigs feces. However, after one week on a diet containing 2.5 or 5 ppm NIV, nearly all excreted NIV in feces had been de-epoxidated in five of six pigs. After three weeks on the NIV diet also the sixth pig had acquired this ability. Deoxynivalenol was also de-epoxidated when incubated in vitro with the microorganisms that formed de-epoxy-NIV in vivo. Anaerobic incubation of NIV and DON with cow rumen fluid produced de-epoxides of both toxins in a high proportion. No de-epoxide of NIV, but another unidentified metabolite was found in feces from chicken fed 2.5 or 5 ppm NIV for three weeks.

Animals↗
PubMed1997

Contrast-enhanced radiography by differential absorption, using a laser-produced x-ray source.

RATIONALE AND OBJECTIVES: The authors evaluate the feasibility of differential imaging of contrast media, with division of individual pixel values obtained from digital images generated by characteristic radiation from a laser-produced plasma, bridging the K-absorption edge of the contrast agent. METHODS: Laser pulses from an ultrashort-pulse terawatt laser system were focused onto gadolinium and tantalum targets, creating a plasma from which characteristic radiation and Bremsstrahlung was emitted. The elements of the target were selected so the characteristic emission lines of one of the elements were below the K edge of the contrast agent and the emission lines of the other element above. A phantom with gadolinium and other elements in various concentrations was examined. One radiographic exposure was made using a gadolinium target source and a subsequent exposure using a tantalum source. Both images were recorded digitally and the transmission ratios calculated by division of the individual pixel values. RESULTS: When viewed separately, the two images of the test phantom appeared similar. In the differential image, only the gadolinium solutions were bright, reflecting a difference in attenuation between the two exposures. CONCLUSIONS: Element-specific radiographs can be obtained by differential imaging. When fully explored, the technique may allow for contrast-enhanced radiography with increased sensitivity and decreased contrast dose.

Animals↗
PubMed1996

Laser transillumination of breast tissue phantoms using time-resolved techniques.

The objective of this study was to evaluate a pulsed laser transillumination technique based on time-resolved detection on breast-tissue-like phantoms. Experiments have been performed on tissue-like plastic phantoms with different scattering characteristics. The effects of time-gate width, size, localisation and refractive index of hidden objects have been scrutinised. Our study showed that the shorter the time-gate the higher the contrast. The contrast is very dependent on the size of the hole, whereas the full width half maximum is not. Furthermore, the investigation showed that the changes of early detected light in an experimental setting is due to scattering, and not to a higher speed of the transmitted light.

Breast↗
PubMed1996

Optical aspects of a fibre-optic sensor for respiratory rate monitoring.

A new sensor for respiratory rate monitoring is described. The sensor uses an optical fibre that detects the evaporated humidity from the mouth and/or nose at each exhalation. The condensed humidity substantially alters the coupling of light from the optical fibre to the surrounding medium, which can be monitored by a photo-detector. The sensing principle is evaluated using ray-tracing simulation and scattering measurements.

Computer Simulation↗
PubMed1996

A new single-fibre laser Doppler flowmeter based on digital signal processing.

A new laser Doppler flowmeter, based on a personal computer with a digital signal processor for detecting the blood perfusion in skeletal muscle, was designed and evaluated. An infrared laser diode (750 nm) fed a single optical fibre, 400 microns in diameter, which was introduced into the muscle. A PC equipped with a digital processing unit was used for emulation of the laser Doppler algorithm and for presentation of the measurement results. The Doppler signal power spectral density and corresponding flow values were visualized on the computer screen continuously in real-time, and could also be saved on the hard disk for off-line analyses. The graphic-user interface supported by Labwindows software made the system easy to use. It is possible to alter in the software the signal processing and the ways in which the signals and results are presented. The new system was evaluated by using a flow model as well as a mechanical model. The model studies showed linear relationships between particle velocity and flow in the range of 0-5 mm s-1. The system was also tested in measurements of the blood flow in the brachioradial muscle, and was found to have advantages over our previously used systems.

Algorithms↗
PubMed1996

Radiation dose reduction in computed skeletal radiography. Effect on image quality.

PURPOSE: To evaluate the effect of radiation dose reduction on image ++quality in computed musculoskeletal radiography and determine optimal exposure range. MATERIAL AND METHODS: In 11 corpses, 1 hand and 1 hip were examined with film-screen radiography, and a series of computed radiographs was obtained using exactly the same technique except for the exposure, which was 100, 50, 25, 12.5, 6.25, and 1.56% of the mAs numbers used for the film-screen images. The computed hip radiographs were processed in 2 different ways, one simulating the film-screen images and one using contrast enhancement. Four radiologists reviewed the images regarding the following parameters: cortical bone, trabecular bone, joint space, and soft tissue, giving each a diagnostic quality rating on a scale from 1 to 5. The median and mean values were found for the pooled results. RESULTS: For the hands, the computed radiographs were ranked inferior to the film-screen images for all parameters except soft tissue, where the computed radiographs scored higher. The computed images with 50 and 25% exposure were ranked equal to the 100% ones. The quality rating slowly declined with lower exposures. For the hips, the 100 and 50% computed radiographs were generally similar to or slightly better than the film-screen images. The decline was somewhat faster than for the hands. The contrast-enhanced hip images scored less than the nonenhanced images at any given exposure for all parameters except soft tissue, where the contrast-enhanced images scored better at all exposures. The difference between nonenhanced and enhanced images became less at the lower exposures. CONCLUSION: Lowering the exposure in computed musculoskeletal radioagrphy below the level of film-screen radiography is feasible, especially in the peripheral skeleton. Contrast enhancement seems to be valuable only in the evaluation of soft-tissue structures.

Bone and Bones↗
PubMed1996

Spatial resolution requirements in digital radiography of scaphoid fractures. An ROC analysis.

PURPOSE: To investigate the spatial resolution requirements in digital radiography of scaphoid fractures. MATERIAL AND METHODS: Included in the study were 60 scaphoid radiographs with and 60 without fractures of the scaphoid bone. The film-screen images were digitized using pixel sizes of 115, 170, and 340 microns along with 170 microns with a 10:1 wavelet compression. The digital images were displayed on a 1280 x 1024 x 8 bits monitor, and 5 observers evaluated the images in 5 randomized sessions. The results for each pixel size were then compared to the film-screen images by ROC analysis. RESULTS: The mean area under the ROC curves was larger for the film-screen images than for the digital images at all resolutions. However, this difference was not significant when the areas under the ROC curves for the film-screen images were compared to the digital images of 115, 170, and 170 microns with 10:1 compression. There was a significant difference for the 340-microns pixel size in favour of the film-screen images. The mean ROC curves for the digital images were very similar for the 115 and 170 microns pixel sizes, although slightly better for 115 microns. At 170 microns, the compression seemed to have a relatively small negative effect on the diagnostic performance; the deterioration was greater when the pixel size was increased to 340 microns. There was no obvious correlation between diagnostic performance and the experience of the observers in using work-stations. CONCLUSIONS: The pixel size of 170 microns is adequate for the detection of subtle fractures, even after wavelet compression by a ratio of 10:1.

Angiography, Digital Subtraction↗
PubMed1995

Effects of feeding nivalenol-contaminated diets to male broiler chickens.

In two feeding trials the effect of nivalenol (NIV) on male broiler chickens was studied. A commercial starter diet was provided for ad libitum consumption throughout the whole experiment. The NIV was added to the feed when the birds were 7 d old. Growth and feed consumption were thereafter registered every 5th d during 20 d. In the first trial birds were offered feed containing 0, .5, 2.5, or 5 ppm NIV. The only variable that significantly differed from the control was the concentration of uric acid in plasma, which was increased by 94 and 66%, respectively, in treatment groups 2.5 and 5 ppm. In the second trial, NIV-concentrations of 0, 3, 6, and 12 ppm were used. The weight gain for the 20-d period was decreased by 11% with 6 and 12 ppm. During this period these birds showed a decrease of about 6% in feed consumption and feed conversion efficiency. Gizzard erosions were found in 33% of the birds fed 12 ppm NIV and in 8% of those fed 3 or 6 ppm. No such erosions were found in the control birds. Relatively, the liver weights in the 12 ppm group were reduced more than total body weights. No effects on relative organ weights were found when bursa, spleen, and gizzard were compared to control. In the blood, no change compared to control was found in hematocrit or in the plasma concentration of glucose, calcium, cholesterol, triglycerides, and uric acid, or in the plasma activity of aspartate amino transferase, alanine amino transferase, or gamma glutamyl transpeptidase.

Animals↗
PubMed1995

Computed radiography in scoliosis. Diagnostic information and radiation dose.

The diagnostic information and radiation dose in scoliosis examinations performed with air-gap technique using stimulable phosphor imaging plates were determined in a prospective study. Overlapping p.a. images of the thoracic and lumbar spine in 9 patients were obtained with 4 different exposure settings according to patient size. Equal exposure settings were used for the 2 images. Two images of 18 were judged inferior in depicting the landmarks of scoliosis measurement, requiring re-exposure. Sixteen images were judged of adequate or good quality. The mean entrance doses in the central beam for the 4 patient groups were in the interval of 0.05 to 0.12 mGy for both images. The skin doses on the breasts were in the range of 0.00 to 0.03 mGy. The presented technique thus results in a low radiation dose with sufficient diagnostic information in radiography of scoliosis.

Adolescent↗
PubMed1995

Computed vs. film-screen magnification radiography of fingers in hyperparathyroidism. An ROC analysis.

One hundred randomly selected patients with suspected or known hyperparathyroidism were examined in a prospective study of the 2nd and 3rd fingers with film-screen and digital luminescence radiographs using magnification technique. The digital images were displayed on a work-station and printed as hard-copies. Two radiologists evaluated the film-screen images regarding subperiosteal and intracortical resorption and their results were defined as "gold standard" regarding the absence or presence of these changes. Four radiologists evaluated these changes in the 3 image forms and an ROC analysis was performed. Comparing the areas under the ROC curves no significant difference was found between the film-screen images and the 2 digital display forms. These results suggest that currently available digital systems provide adequate diagnostic accuracy for evaluation of subtle skeletal changes.

Adolescent↗
PubMed1995

Patients with rheumatoid arthritis benefit from early 2nd line therapy: 5 year followup of a prospective double blind placebo controlled study.

OBJECTIVE: To compare 2 treatment strategies in a prospective 5 year study of patients with rheumatoid arthritis (RA): early treatment with slow acting antirheumatic drugs (SAARD) versus a "wait and see" attitude. METHODS: One hundred thirty-seven patients with RA of < 2 years' duration entered a double blind placebo controlled study: patients in the "early" (E) group were treated with auranofin within one year of diagnosis of RA, and SAARD treatment in the initially placebo treated group was delayed 8 months compared with the former group. [The results after 2 years clearly favored early treatment (Borg G, Allander E, Lund B, et al: J Rheumatol 1988; 15:1747-54)]. RESULTS: After a total observation period of 5 years in 75 representative patients, continued improvement in the E group was demonstrated, and differences between the 2 groups were maintained with regard to clinical variables, outcome measures, and radiographic evaluation. CONCLUSION: The results indicate the existence of a therapeutic window in RA within the first 2 years of the disease.

Adult↗