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Biomedical subjects

K Bergström

Publications and source records attributed to K Bergström.

266 records · Page 15Linked to original sources
PubMedDate not supplied

Amino acid distribution and metabolism in pituitary adenomas using positron emission tomography with D-[11C]methionine and L-[11C]methionine.

Four patients with hormonally inactive pituitary adenomas were examined with positron emission tomography (PET) after injection, during different examinations, of L-[methyl-11C]methionine and D-[methyl-11C]methionine, respectively. After the rapid distribution phase, the enantiomer L-[11C]methionine, which is metabolically active, showed a considerable continuous irreversible trapping attributed to amino acid metabolism. The stereoisomer D-[11C]methionine, which does not participate in protein synthesis, showed a rapid distribution within the whole adenoma tissue, with a distribution space on the order of 100%. A minimal irreversible trapping was observed which could be explained by technical factors. It is concluded that PET using the two enantiomers allows a separation of passive distribution and metabolism, and that L-[11C]methionine can be used for in vivo quantitative studies of amino acid metabolism of pituitary adenomas.

Adenoma↗
PubMedDate not supplied

Rapid decrease in amino acid metabolism in prolactin-secreting pituitary adenomas after bromocriptine treatment: a PET study.

Four patients with prolactin-secreting pituitary adenomas were examined with positron emission tomography using L-[11C]methionine to monitor the effect of dopamine agonist treatment on the amino acid metabolism in the tumors. Within the first few hours after intramuscular injection of bromocriptine retard (50 mg) the amino acid metabolism decreased by 40%. Two of the patients were reexamined 7 and 9 days later and showed a 70% reduction in the metabolism of the adenomas. This metabolic effect was later accompanied by significant tumor shrinkage in all adenomas. It is suggested that bromocriptine has a general and rapid effect on the protein synthesis of the prolactin-secreting pituitary adenoma cells.

Adenoma↗
PubMedDate not supplied

Ischemic edema in stroke. A parallel study with computed tomography and cerebrospinal fluid markers of disturbed brain cell metabolism.

Thirteen patients with stroke and one with TIA had repeated examinations with computed tomography (CT) of the head, examination of the cerebrospinal fluid (CSF) for adenylate kinase, glutathione, lactate, and albumin and clinical evaluations during the first fortnight after onset. In 9 patients with cerebral infarction edema shown on the CT scans was maximal on days 2--5, after which it diminished. In 2 patients with intracerebral hemorrhage the edema appeared early as a zone of low-attenuation around the high-attenuation area. Most patients with large lesions deteriorated clinically during development of the edema. In 3 patients the CT scans were inconclusive, probably because the lesion was too small. Adenylate kinase activity was present in all CSF samples during the period 6 hours-5 days, while glutathione was occasionally present in the CSF in 12 of the 14 patients. These findings are believed to indicate cell swelling and a leak in the plasma membrane. Based on these observations, it is suggested that initial ischemic edema is intracellular in patients with cerebral infarction, and that adenylate kinase in CSF is a sensitive marker for this type of edema.

Adenylate Kinase↗
PubMedDate not supplied

Lactoferrin, lysozyme, and beta 2-microglobulin in cerebrospinal fluid. Elevated levels in patients with acute cerebrovascular lesions as indices of inflammation.

Serial determinations of beta 2-microglobulin, lactoferrin and lysozyme in CSF were performed in 14 patients with acute cerebrovascular lesions. Marked elevations were noted in patients with cerebral bleeding or hemorrhagic infarction. Patients with infarction without signs of bleeding or with cerebrovascular lesions undetectable by computed tomography also had an increase in these proteins. The increases in CSF of beta 2-microglobulin, lactoferrin and lysozyme could not be explained by a damaged blood-brain barrier but was believed to be a local product of the central nervous system. Peak levels of lactoferrin and lysozyme were noted on day 2-3 after onset of symptoms. Lactoferrin then declined while lysozyme remained elevated for another few days. beta 2-microglobulin gradually increased reaching peak levels on day 4-5 and remained elevated even 2 weeks after the onset of symptoms. We suggest that the increases of lactoferrin, lysozyme and beta 2-microglobulin reflect various inflammatory reactions mediated by granulocytes, macrophages and lymphocytes, respectively.

Acute Disease↗
PubMedDate not supplied

Structure enhancement by subtraction in magnetic resonance imaging.

Two patients with tumours in the pituitary gland and the liver, respectively, were studied with MRI. Regions of different transverse relaxation times were found in the tumours. Subtraction of images recorded with different echo times demonstrated the tumour regions better than the original images although these were recorded with 2 repetition times and double and multiple echo sequences. Subtraction techniques may thus aid diagnosis in MRI.

Adenoma, Islet Cell↗
PubMedDate not supplied

Eye lens dose in cranial computed tomography with reference to the technical development of CT scanners.

The continuous technical development of cranial CT and the accumulation of clinical experience with this method, have resulted in the use of an increasing number of scan protocols for different clinical situations. An investigation was undertaken to find out how this change has influenced the dose delivered to the patient. The eye lens dose was measured at CT examinations in 245 patients, with appropriate scan protocols, and also at corresponding examinations in an anthropomorphic head phantom. One CT scanner of early (EMI CT 1010) and one of modern design (Siemens Somatom DR2) were investigated. The range of the eye lens dose was wide, namely 4 to 206 mGy for EMI CT 1010 and 6 to 124 mGy for Somatom DR2. In patient groups with comparable scan protocols the mean eye lens dose was higher with the Somatom DR2, mostly on account of a different spatial distribution of the dose in the scan plane. The dose varied less with this scanner, however, mainly because of the possibilities for more accurate positioning.

Humans↗
PubMedDate not supplied

An educational programme for persistent life-style changes in patients with chronic renal disease.

The aim of this study was to produce positive life-style changes in patients with chronic renal disease through a residential education programme about the medical aspects of chronic renal failure and the various treatment options in order to increase their physical capacity, emotional stability and general well-being. The programme was available to all categories of patients with chronic renal disease irrespective of treatment modality. Comparison of data pre and post course demonstrated improvements in physical activity, mental well-being and nutritional awareness.

Activities of Daily Living↗
PubMedDate not supplied

Macroprolactinomas: serial MR imaging in long-term bromocriptine therapy.

PURPOSE: To study the changes in macroprolactinomas during long-term bromocriptine therapy by means of serial MR imaging, and to correlate the findings to the serum prolactin (S-PRL) levels. PATIENTS AND METHODS: Thirteen patients with macroprolactinomas were studied before and during bromocriptine therapy; six to 11 MR examinations were performed with a duration of follow-up of 22 to 74 months. Tumor size, extension, relationship to adjacent structures, and signal intensity patterns were evaluated. Signal intensity ratios and T2 values were calculated in areas of apparently solid tumor tissue. RESULTS: Bromocriptine effectively reduced the size of all tumors; the size reduction was already significant at 1 week, but often continued for several years. Reenlargement during therapy was seen in three cases. The development of chiasmal herniation parallel to increasing cisternal invagination into the sella was a common finding, but was not correlated to visual symptoms. Signal intensity patterns corresponding to hemorrhage, cysts or necrosis were frequently observed, and transitions from one pattern to another were common. Hemorrhage occurred mainly in tumors corresponding to high initial serum prolactin levels. After 1 year of therapy, there was a significant increase in T2 values, indicating an increased water content in residual solid tumor tissue. CONCLUSIONS: MR is valuable for follow-up in bromocriptine therapy of macroprolactinomas, and provides new information on the tumor size changes, the inner structure of the tumors, and the optic chiasm.

Bromocriptine↗
PubMedDate not supplied

Attenuation values, volume changes and artifacts in tissue due to freezing.

Freezing of animal and human tissue may change their shape, size and other physical properties such as attenuation of roentgen rays. In correlative radiologic-anatomic studies such artifacts are potential sources of inaccuracy. In fluid phantoms changes of computed tomography (CT) numbers and volume were measured before and after freezing. Frozen saline decreased in attenuation by 80 Hounsfield units (HU) and increased in volume by 9 per cent. Pure soy oil increased in attenuation by 40 HU after freezing and shrank in volume by 4 per cent. Emulsions of 10, 20 and 30 per cent lipid expanded in inverse relationship to the changes in attenuation. In animal and human tissue, changes in CT number of -80 to +55 HU were measured and changes in volume of -6 to +9 per cent were calculated. The attenuation of the vitreous body in the eye decreased by 80 HU and its volume was calculated to increase by 8 to 9 per cent. In the muscle and spinal cord the attenuation decreased by 40 to 60 HU, corresponding to the increase in volume of 4 to 6 per cent. Attenuation of fat was increased by 55 HU after freezing and a decrease in volume of 5 to 6 per cent was calculated. Deformation of soft tissue and herniation of the cerebellar tonsils into the foramen magnum were observed. Most anatomic, freezing artifacts can be avoided by careful preparation.

Adipose Tissue↗
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Dynamic study of supratentorial gliomas with L-methyl-11C-methionine and positron emission tomography.

The regional kinetics of intravenously injected L-methyl-11C-methionine (11C-L-methionine) in the brain was investigated by positron emission tomography (PET) in 14 patients with gliomas. In both tumor and unaffected brain the tracer uptake reached a nearly constant level in 5 min or less. The ratio between the uptake of 11C-L-methionine by high-grade tumors and the uptake by unaffected brain was 1.9-4.8. In two cases of low-grade astrocytoma the ratio was 0.8-1.0. High uptakes of 11C-L-methionine occurred in gliomas even in the absence of blood-brain barrier defects as observed by other methods. This indicates that besides active transport of amino acid, a larger extracellular space in tumor as compared with unaffected brain tissue may also contribute to the increased uptake of 11C-L-methionine--derived radioactivity. In some patients delineation of the tumors was improved by use of PET with 11C-L-methionine as compared with computed tomography, angiography, and, in some instances, PET with 68Ga-EDTA. PET with 11C-L-methionine permits better evaluation of the tumor extent and may affect preoperative grading.

Adult↗
PubMedDate not supplied

MR imaging of syringohydromyelia and Chiari malformations in myelomeningocele patients with scoliosis.

The brain and spinal cord were examined with MR imaging in 30 myelomeningocele patients 3-32 years old to study the prevalence of syringohydromyelia and Chiari malformations and to correlate these conditions with developmental scoliosis and spontaneously arrested hydrocephalus. Twelve patients had neurologic deficits above the level of the myelomeningocele and 10 had spontaneously arrested hydrocephalus. MR visualized syringohydromyelia in four patients with widened or focally bulging spinal cords and in eight patients with atrophic spinal cords. All patients had Chiari malformations, 28 of type II and two of type I. Syringohydromyelia was not correlated with type of scoliosis, result of ventriculoperitoneal shunting procedures, radiologic level of the myelomeningocele, or extent of the Chiari malformation. The two patients with the most rapid progression of thoracic scoliosis had the most extensive syringohydromyelia and radiologically low lumbar levels. Neurologic deterioration due to syringohydromyelia and Chiari malformations is probably more common in myelomeningocele than has been recognized previously and may cause developmental scoliosis, loss of ambulation, impaired extremity function, and progressive cranial nerve paralysis.

Adolescent↗
PubMedDate not supplied

Multiplanar spinal anatomy: comparison of CT and cryomicrotomy in postmortem specimens.

Good anatomic knowledge is a prerequisite for correct interpretation of computed tomographic (CT) scans. To elucidate the complex CT anatomy of the spine, autopsy specimens from various spinal regions were frozen in situ to preserve the undistorted topographic anatomy. The frozen specimens were examined by CT in axial, sagittal, and coronal planes and sectioned by cryomicrotomy along the scanning planes. Photography of the section surfaces yielded detailed anatomic images that were accurately correlated with the CT scans.

Adult↗