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Biomedical subjects

C Thomsen

Publications and source records attributed to C Thomsen.

At least 163 records · Page 9Linked to original sources
PubMed1993

Increased water self-diffusion in chronic plaques and in apparently normal white matter in patients with multiple sclerosis.

A new method for measurement of water self-diffusion compensating for zeroth and first order movements was used to study the apparent diffusion coefficient (ADC) in 15 patients with chronic multiple sclerosis (MS) and in two patients with acute MS. Ten healthy volunteers served as controls. A significantly higher ADC was found within chronic plaques compared to the apparently normal white matter of the chronic patients. The ADC was higher in the acute plaques compared to the chronic plaques. The ADC in apparently normal white matter of the chronic patients were significantly higher than in white matter of healthy volunteers. We hypothesize that an increase of the ADC in plaques may be related to an increase in the extracellular space due to oedema and demyelination. The increased ADC in apparently normal white matter suggests that there may be a change in the composition of the white matter of chronic MS patients, perhaps related to oedema and expanded extracellular space.

Adult↗
PubMed1993

Effect of meal frequency on blood glucose, insulin, and free fatty acids in NIDDM subjects.

OBJECTIVE: We studied the effects of meal frequency on blood glucose, serum insulin, and FFAs in 12 NIDDM subjects. RESEARCH DESIGN AND METHODS: Subjects were assigned in random order to two 8-hr observation periods after an overnight fast. They received isocaloric diets with similar composition either as six small or as two large meals. At the end of each study period, an IVGTT was given. RESULTS: Two large meals induced an 84% greater maximum amplitude of glucose excursions than six small meals (6.1 +/- 0.5 vs. 3.3 +/- 0.5 mM, P < 0.005) and higher insulin responses (P < 0.03). The Kg response to an IVGTT did not differ in the two situations. The average FFA level was lowest in response to frequent meals (P < 0.02). CONCLUSIONS: A higher meal frequency acutely subdues glucose excursions and reduces insulin and FFA levels during the daytime in older NIDDM subjects.

Blood Glucose↗
PubMed1993

Effects on blood pressure, glucose, and lipid levels of a high-monounsaturated fat diet compared with a high-carbohydrate diet in NIDDM subjects.

OBJECTIVE: To compare the influence on blood pressure, glucose, and lipid levels of a diet rich in monounsaturated fatty acids with an isocaloric, high-carbohydrate diet in 15 NIDDM subjects. RESEARCH DESIGN AND METHODS: A crossover design with diet interventions and wash-out periods of 3 wk was applied. The patients were randomly assigned to a 3-wk treatment with a high-carbohydrate diet containing 50% of energy as carbohydrate and 30% of energy as fat (10% of energy as monounsaturated fatty acids) or an isocaloric diet with 30% of energy as carbohydrate and 50% of energy as fat (30% of energy as monounsaturated fatty acids). On the last day of the two diets, 24-h ambulatory blood pressure was measured and day profiles of glucose, hormones, and lipids were performed to a test menu rich in carbohydrates. RESULTS: The diet rich in monounsaturated fat reduced daytime systolic (131 +/- 3 vs. 137 +/- 3 mmHg, P < 0.04) and 24-h systolic blood pressure (126 +/- 8 vs. 130 +/- 10 mmHg, P < 0.03) as well as daytime diastolic (78 +/- 2 vs. 84 +/- 2 mmHg, P < 0.02) and diurnal diastolic blood pressure (75 +/- 6 vs. 78 +/- 5 mmHg, P < 0.03) as compared with the high-carbohydrate diet. Evidence of lowered blood glucose levels on the high-monounsaturated diet compared with the high-carbohydrate diet were found with lower fasting blood glucose (6.1 +/- 0.3 vs. 6.8 +/- 0.5 mM, P < 0.05), lower average blood glucose levels (7.4 +/- 0.5 vs. 8.2 +/- 0.6 mM, P < 0.04), and peak blood glucose responses (9.9 +/- 0.6 vs. 11.3 +/- 0.7 mM, P < 0.02). The two diets had the same impact on lipid levels. CONCLUSIONS: A diet rich in monounsaturated fat has beneficial effects on blood pressure and glucose metabolism, whereas no adverse effects on lipid composition in NIDDM subjects is detected.

Analysis of Variance↗
PubMed1993

Serine-O-phosphate has affinity for type IV, but not type I, metabotropic glutamate receptor.

L-serine-O-phosphate (L-SOP) has been reported to antagonize phosphoinositide (PI) hydrolysis in slices of rat brain as stimulated by agonists of the metabotropic glutamate receptor (mGluR). In the present study, the affinity of L-SOP was examined in a baby hamster kidney (BHK) cells expressing subtype mGluR1 or mGluR4 of the mGluR family. L-SOP or D-SOP (3 mM) did not inhibit PI-hydrolysis as stimulated by 10 microM glutamate in BHK cells expressing mGluR1. However, L-SOP was a potent agonist at the mGluR4 subtype (IC50 = 4.4 +/- 1.4 microM), which is negatively coupled to adenylate cyclase, while D-SOP was weakly active (IC50 = 1260 +/- 190 microM).

Animals↗
PubMed1993

History of the Cancer Information Service.

The Cancer Information Service (CIS) was established on July 1, 1975, following the mandate of the National Cancer Act of 1971 giving the National Cancer Institute (NCI) new responsibilities for educating the public, patients, and health professionals. Funded under a contract mechanism, the CIS has become one of the longest-running community programs in NCI. The CIS has been able to set up and maintain high-quality service, giving accurate, up-to-date medical information to cancer patients and their families and friends, to health professionals, and to the general public. The CIS network, which has taken more than 5 million calls since its inception, has weathered many changes, both at the national and the local level. Its current call volume, in excess of 500,000 calls per year, makes it one of the most heavily utilized health-related telephone helplines in the country. Using a standardized Call Record Form, data on calls have been recorded consistently since 1983; the dataset now contains information on more than 4.2 million calls. An outreach component that acts as NCI's field arm has been part of the CIS since its inception. The CIS has matured into a stable system that has been reconfigured into 19 regional offices, covering the entire country. These offices run the telephone service and serve as NCI's outreach arm, working with intermediaries to carry out NCI information and education programs in local communities.

History, 20th Century↗
PubMed1993

Acute effects of graded alcohol intake on glucose, insulin and free fatty acid levels in non-insulin-dependent diabetic subjects.

Alcohol-induced hypoglycaemia is a well-known phenomenon in insulin-treated diabetic subjects. Less attention has been paid to the impact of alcohol on blood glucose and insulin responses in non-insulin dependent diabetic subjects. The aim of this study was to investigate the acute metabolic effects of different alcohol contents added to a non-alcohol beer in 10 non-insulin-dependent diabetes mellitus (NIDDM) subjects. The patients received 500 ml non-alcohol beer with an alcohol percentage (v/v) of 0 (A), 2.7 (B), and 5.4 (C), implying identical contents of ingredients except for alcohol. Blood glucose (mean +/- SE) responses were similar in the three situations (395 +/- 59, 365 +/- 86 and 261 +/- 26 mmol/l x 240 min). In contrast, the incremental insulin response areas increased dose dependently to alcohol (5430 +/- 1158, 9336 +/- 2172 and 12336 +/- 2922 pmol/l x 240 min) and showed a linear correlation (r = 0.39; P < 0.03). The average suppression of serum free fatty acid was similar in the three situations (72.4 +/- 4.4%, 76.3 +/- 6.0% and 68.2 +/- 6.3%). In conclusion, intake of small amounts of alcohol does not acutely deteriorate the glycaemic control in NIDDM. The fact that alcohol results in a dose-related elevation in insulin levels with unaltered blood glucose and free fatty acid responses in NIDDM points to an aggravation of insulin resistance.

Aged↗
PubMed1993

Normal left ventricular wall motion measured with two-dimensional myocardial tagging.

Using a myocardial tagging technique, normal left ventricular wall motion was studied in 3 true short axis views and a double oblique 4-chamber view in 14 and 11 volunteers, respectively. Three orthogonal directions of left ventricular motion were observed throughout the systole; a concentric contraction towards the center of the left ventricle, a motion of the base of the heart towards the apex, and a rotation of the left ventricle around its long axis. The direction of left ventricular rotation changed from early systole to late systole. The base and middle levels of the left ventricle rotated counterclockwise (CCW) at early systole and clockwise (CW) at late systole, whereas the apex of the heart rotated CW at early systole and CCW at late systole. The different directions of the rotation of base and apex resulted in a myocardial twisting that changed direction from early to late systole. We conclude that MR imaging with myocardial tagging is a method that can be used to study normal left ventricular wall motion, and that is promising for future use in patient groups.

Adult↗
PubMed1993

Functional MR imaging at 1.5 T. Initial results using photic and motoric stimulation.

A preliminary investigation of the effects of stimulation of the visual and the motor cortex was made on a conventional 1.5 T MR imaging scanner. Both types of activation gave a detectable change in the signal between rest and stimulation using a gradient echo sequence with an echo time of 60 ms. The observed effects were assumed to be caused by variation in the amount of paramagnetic deoxyhemoglobin between stimulation and rest due to local increase of capillary blood flow in the human brain during stimulation.

Brain↗
PubMed1992

L-2-amino-4-phosphonobutyrate (L-AP4) is an agonist at the type IV metabotropic glutamate receptor which is negatively coupled to adenylate cyclase.

Glutamate and L-AP4 inhibited forskolin-stimulated cyclic AMP (cAMP) production in baby hamster kidney (BHK) cells transfected with the type IV metabotropic receptor (mGluR4). In situ hybridization revealed a high level of mRNA for the mGluR4 in the entorhinal cortex, but not in the dentate gyrus. These data demonstrate that mGluR4 receptors are negatively coupled to the cAMP cascade, and suggest that the mGluR4 receptor may be the previously described presynaptic L-AP4 receptor.

Adenylyl Cyclases↗
PubMed1992

Pulsatile brain movement and associated hydrodynamics studied by magnetic resonance phase imaging. The Monro-Kellie doctrine revisited.

Brain tissue movements were studied in axial, sagittal and coronal planes in 15 healthy volunteers, using a gated spin echo MRI sequence. All movements had characteristics different from those of perfusion and diffusion. The highest velocities occurred during systole in the basal ganglia (maximum 1.0 mm/s) and brain stem (maximum 1.5 mm/s). The movements were directed caudally, medially and posteriorly in the basal ganglia, and caudally-anteriorly in the pons. Caudad and anterior motion increased towards the foramen magnum and towards the midline. The resultant movement occurred in a funnel-shaped fashion as if the brain were pulled by the spinal cord. This may be explained by venting of brain and cerebrospinal fluid (CSF) through the tentorial notch and foramen magnum. The intracranial volume is assumed to be always constant by the Monro-Kellie doctrine. The intracranial dynamics can be viewed as an interplay between the spatial requirements of four main components: arterial blood, capillary blood (brain volume), venous blood and CSF. These components could be characterized, and the expansion of the arteries and the brain differentiated, by applying the Monro-Kellie doctrine to every moment of the cardiac cycle. The arterial expansion causes a re-moulding of the brain that enables its piston-like action. The arterial expansion creates the prerequisites for the expansion of the brain by venting CSF to the spinal canal. The expansion of the brain is, in turn, responsible for compression of the ventricular system and hence for the intraventricular flow of CSF.

Adult↗
PubMed1992

Simultaneous electromyography and 31P nuclear magnetic resonance spectroscopy--with application to muscle fatigue.

The electromyogram (EMG) is often used to study human muscle fatigue, but the changes in the electromyographic signals during muscle contraction are not well understood in relation to muscle metabolism. The 31P NMR spectroscopy is a semi-quantitative non-invasive method for studying the metabolic changes in human muscle. The aim of this study was to develop a method by which EMG and NMR spectroscopy measurements could be performed simultaneously. All measurements were performed in a whole body 1.5 Tesla NMR scanner. A calf muscle ergometer, designed for use in a whole body NMR scanner, was used. The subject had the left foot strapped to the ergometer. The anterior tibial EMG was recorded by bipolar surface electrodes. A surface coil was strapped to the anterior tibial muscle next to the EMG electrodes. Simultaneous measurements of surface EMG and surface coil 31P NMR spectroscopy were performed in the scanner during an isometric submaximal voluntary contraction until exhaustion, in 6 normal volunteers. Concentrations of phosphocreatine (PCr), inorganic phosphate (P(i)) and pH were analysed together with root mean square (RMS) and median frequency of the EMG. The fatiguing contractions (endured 5-13 min) produced a rapid decline in PCr and pH accompanied by a rapid rise in P(i). The RMS was approximately constant until the normalized PCr concentration declined below 0.6-0.7 and the pH declined below 6.75-6.85; exceeding these metabolic limits was associated with a rapidly increasing RMS value (2-3 times the previous level by exhaustion). The median frequency declined linearly with time and was found to be highly linearly correlated with the pH value (r = 0.82).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

In vivo magnetic resonance diffusion measurement in the brain of patients with multiple sclerosis.

Measurement of water self-diffusion in the brain in 25 patients with multiple sclerosis was performed by magnetic resonance imaging. Quantitative diffusion measurements were obtained using single spin-echo pulse sequences with pulsed magnetic field gradients of different magnitude. Twenty-two of these patients also underwent measurement of the transverse relaxation time (T2). Only one plaque was evaluated in each patient. Based on prior knowledge, 12 plaques were classified as being 3 mo or less in age, and 7 plaques were classified as being more than 3 mo old. In all 25 plaques, water self-diffusion was found to be higher than in apparently normal white matter. Furthermore, water self-diffusion was found to be higher in acute plaques compared with chronic plaques. Finally, a slight tendency toward a relationship between the diffusion capability and T2 was found. We believe that an increased diffusion capability signifies an increase of the extracellular water space, which probably is related to the degree of demyelination. Thus, measurement of water self-diffusion in multiple sclerosis plaques may contribute to the study of pathogenesis of demyelination.

Adult↗
PubMed1992

Quantification of complex flow using MR phase imaging--a study of parameters influencing the phase/velocity relation.

In this study, we describe how motion-induced phase angle is affected by different flow models and imaging parameters when using the MR flow phase mapping technique. In a phantom with straight as well as constricted tubes, simulating healthy and stenotic vessels, nonpulsatile flow in the velocity range 0-1 m/sec was maintained. The phase/velocity relation was studied for various degrees of complex flow caused by the constriction, and regions with a breakdown in linearity were determined. Further studies in these regions were made regarding the influence of pulse sequence parameters on the phase/velocity relation. The results showed that in poststenotic areas characterized by so-called separated flow, the phase/velocity relation became nonlinear due to dephasing effects. In regions with fully developed turbulent flow in straight tubes, however, no breakdown in linearity was observed. Parameters seen to have a substantial influence on the phase/velocity relation were first- and second-order velocity encoding and voxel size. Finally, a pilot in vivo demonstration of complex flow was done using a sequence designed to be robust with respect to linearity of the phase/velocity relation. The results indicate that the MR phase mapping technique can be used to measure flow quantitatively in regions with complex flow. This opens possibilities for future clinical use of the technique in the study of areas of complex flow such as valvular heart disease.

Aortic Valve Stenosis↗
PubMed1992

Identification of patients with hereditary haemochromatosis by magnetic resonance imaging and spectroscopic relaxation time measurements.

A total of 4302 healthy blood donors were screened for elevated serum ferritin and transferrin saturation. Fifteen had increased serum ferritin at a follow-up examination. Five relatives of these donors also entered the study. Eleven patients had elevated liver iron concentrations, while five had normal liver iron concentrations. The R2 relaxation rate in the liver was first measured with a conventional multi-spin-echo imaging sequence, and then by a volume-selective spectroscopic multi-spin-echo sequence, in order to achieve a minimum echo time of 4 msec. No correlation was found between the relaxation rate R2 and the liver iron concentration, when R2 was calculated from the imaging data. Multi-exponential transverse relaxation could be resolved when the spectroscopic sequence was used. A strong correlation between the initial slope of the relaxation curve and the liver iron concentration was found (r = 0.90, p < 0.001). Signal intensity ratios between liver and muscle were calculated from the first three echoes in the multi-echo imaging sequence, and from a gradient echo sequence. A strong correlation between the logarithm of the signal intensity ratios and the liver iron concentration was found. Although both spectroscopic T2 relaxation time measurements and signal intensity ratios could be used to quantify liver iron concentration, the gradient echo imaging seemed to be the best choice. Gradient echo imaging could be performed during a single breath hold, so motion artifacts could be avoided. The accuracy of liver iron concentration estimates from signal intensity ratios in the gradient echo images was about 35%.

Biopsy↗
PubMed1992

The impact of abdominal computerized tomography on the pretreatment staging and prognosis of small cell lung cancer.

One hundred six patients with small cell lung cancer (SCLC) were prospectively evaluated with regard to the prognostic impact of abdominal CT-scan in the pretreatment staging when compared to ultrasonography of the abdomen. Staging based on abdominal ultrasonography (US) plus bilateral bone marrow examinations gave as a result that 47 patients had extensive disease (ED) (44%). Seventeen patients with proven ED at time of referral were not included in this study. Abdominal CT-scan was performed in 76 of the 106 patients. Thirty patients of these 76 patients (39%) were classified as having ED after staging including US, but abdominal metastases were disclosed in another ten patients at the subsequent CT-scan. Liver metastases seen in two patients at ultrasonography were overlooked on the CT-scans. Median survival of the 36 patients classified as having limited disease (LD) after both procedures was 458 days, which was significantly better compared to 330 days for the ten patients with stage migration from LD to ED based on CT-scan, (p less than 0.05) and compared to 242 days in the 30 patients with ED demonstrated by both US and CT-scans (p less than 0.05). The prognostic impact of the CT-scan was further investigated in a multivariate analysis (Cox). Stage disease, performance status, LDH and alkaline phosphatase were significant prognostic factors in a proportional hazards model based on the original 106 patients. Patients in the best prognostic group were characterized by LD, good performance status (0-1) and normal LDH and alkaline phosphatase serum values. This group consisted of 22 patients (21%).(ABSTRACT TRUNCATED AT 250 WORDS)

Abdominal Neoplasms↗