Biomedical subjects

U Ruotsalainen

Publications and source records attributed to U Ruotsalainen.

At least 55 records · Page 3Linked to original sources

PubMed1995

Presynaptic dopamine function in striatum of neuroleptic-naive schizophrenic patients.

Presynaptic dopamine function (6-[18F]-fluorodopa uptake) in the brains of seven neuroleptic-naive first-admission schizophrenic patients and eight healthy controls was studied with positron emission tomography. The fluorodopa influx constant (Ki) in putamen was higher in the patients than in controls (average mean: 0.0149 vs 0.0129, p = 0.034). The changes in caudate were smaller but significantly lateralised to the left caudate. There was one catatonic schizophrenic patient in our sample. This patient had lower striatal Ki than any control. Alterations in striatal presynaptic dopamine function may constitute a part of disrupted neural circuits that predispose to schizophrenic psychosis.

Adult↗

PubMed1995

Evaluation of response to radiotherapy in head and neck cancer by positron emission tomography and [11C]methionine.

PURPOSE: To evaluate the usefulness of positron emission tomography (PET) and L-[methyl-11C]methionine in assessing treatment response to radiotherapy in head and neck cancer. METHODS AND MATERIALS: Fifteen patients with head and neck cancer (13 with squamous cell carcinoma, 1 with adenocystic carcinoma, and 1 with paranasal plasmocytoma) underwent a PET study with [11C]-methionine both before and after preoperative radiotherapy to the total tumor dose of 61-73 Gy. Twelve primary and 12 metastatic tumor sites were within the field of view. Nineteen of the 24 tumor sites were surgically explored after radiotherapy, and the tumor standardized uptake values (SUVs) of [11C]methionine were compared with histological findings. RESULTS: All 24 malignant lesions were detectable in the pretreatment study. In all but one case, the tumor SUV decreased after radiotherapy. The median SUV of the tumor site was smaller (1.9, range, 1.3-3.1, n = 7) in cases with histologically verified complete response than in cases with persistent cancer (median 4.1, range, 2.8-7.6, n = 12, p = 0.0008). A complete histological response was verified in none of the 9 cases with a postirradiation SUV larger than the median (3.1), whereas 7 of the 10 cases with a SUV of 3.1 or smaller had complete response (p = 0.003). The preirradiation uptake of [11C]methionine in tumors did not have significant association with histological response (p = 0.45). The PET findings correlated well with follow-up data in five cases with unoperated tumor sites. The [11C]methionine uptake of the submandibular salivary glands decreased after radiotherapy (p = 0.04). CONCLUSION: PET with [11C]methionine as a tracer may be useful in assessing response to radiotherapy in head and neck cancer. High uptake of [11C]methionine in the postirradiation scan suggests the presence of persistent disease.

Adult↗

PubMed1995

PET examination of the monoamine transporter with [11C]beta-CIT and [11C]beta-CFT in early Parkinson's disease.

The monoamine transporter was studied in 4 healthy controls and 5 patients with early Parkinson's disease (PD), who had not received any antiparkinsonian medication, by means of positron emission tomography (PET) using two novel ligands, [11C]beta-CIT and [11C]beta-CFT. Both ligands showed highest uptake in the striatum. There was intermediate accumulation of activity in the thalamus and midbrain, which was more marked for [11C]beta-CIT than for [11C]beta-CFT. In the cortical areas, uptake of both ligands was not different from that seen in the cerebellum. In the controls, the putamen-to-cerebellum and caudate-to-cerebellum ratios for [11C]beta-CFT were higher than those for [11C]beta-CIT (putamen: 3.15 +/- 0.39 for [11C]beta-CFT, and 1.84 +/- 0.10 for [11C]beta-CIT; caudate: 3.15 +/- 0.31 for [11C]beta-CFT, and 1.95 +/- 0.17 for [11C]beta-CIT). Reduction from mean control value in PD patients was greater for [11C]beta-CFT (45% in the putamen contralateral to the predominant symptoms, P < 0.001) than for [11C]beta-CIT (20%, P > 0.05). [11C]beta-CFT uptake in the caudate nucleus was also diminished in PD patients (to 80% of the control mean, P < 0.05), whereas [11C]beta-CIT was within normal range (reduced to 90% of the control mean). These results indicate that both [11C]beta-CIT and [11C]beta-CFT are useful PET ligands to study brain monoamine transporter in healthy controls and in patients with PD. However, [11C]beta-CFT seems superior to [11C]beta-CIT in this respect.

Adult↗

PubMed1995

Increased density of dopamine D2 receptors in the putamen, but not in the caudate nucleus in early Parkinson's disease: a PET study with [11C]raclopride.

Striatal dopamine D2 receptors were studied, using positron emission tomography (PET), in 10 patients with early Parkinson's disease without any antiparkinsonian medication and in 14 healthy controls. [11C]Raclopride was used as ligand and an equilibrium method was applied. The maximum count of receptors (Bmax) and their dissociation constant (Kd) were calculated according to the Scatchard principle. In parkinsonian patients, the Bmax of D2 receptors was increased in the putamen contralateral to the predominant symptoms, as compared to the opposite putamen, by 33% (p = 0.0008). In the caudate nucleus no significant side to side differences was noted. On comparison with age-matched healthy controls, Bmax values in the putamen (p = 0.0012) but not in the caudate nucleus contralateral to the side of predominant clinical symptoms were increased in PD patients. The Kd values were unchanged. The difference in putaminal Bmax values between the opposite hemispheres correlated with the difference in the severity of parkinsonian motor symptoms between the two body sides (r = 0.69, p = 0.03). The present results show that there is both a relative and absolute increase in the number of dopamine D2 receptors in the putamen, but not in the caudate nucleus in early Parkinson's disease.

Carbon Radioisotopes↗

PubMed1995

Head and neck cancer: detection of recurrence with PET and 2-[F-18]fluoro-2-deoxy-D-glucose.

PURPOSE: To evaluate positron emission tomography (PET) with 2-[fluorine-18]fluoro-2-deoxy-D-glucose (FDG) in detection of suspected recurrence of head and neck cancer, and to compare visual, static, and kinetic analyses of the tracer uptake. MATERIALS AND METHODS: Seventeen dynamic FDG PET studies were performed in 15 patients. The images were interpreted visually, and the uptake was quantitated as the standardized uptake value (SUV) and as the regional FDG metabolic rate. RESULTS: Sensitivity of blinded visual interpretation of the PET images for the presence of malignancy was 88% and specificity was 86%. Malignant lesions accumulated significantly more FDG than benign lesions (P = .008 for SUVs, P = .002 for regional metabolic rates). When maximum uptake of FDG in the benign lesions was used as a threshold, the sensitivity of SUV analysis for malignancy was 75% and that of regional metabolic rates was 86%. CONCLUSION: Detection of recurrent head and neck cancer is feasible with FDG PET. Quantitation of FDG uptake assists in correct interpretation of the PET images.

Deoxyglucose↗

PubMed1995

Insulin increases blood volume in human skeletal muscle: studies using [15O]CO and positron emission tomography.

High insulin concentrations increase blood flow in the leg, but it is unknown whether this effect is associated with a change in muscle blood volume. In the present study, we used positron emission tomography combined with inhalation of [15O]carbon monoxide to quantitate the effect of insulin on skeletal muscle blood volume in humans. The reproducibility of the method was determined from two consecutive measurements performed in the basal state in five normal subjects. The coefficient of variation of the repeated measurements was 3.0 +/- 1.8%. In 14 normal subjects [age 35 +/- 3 yr, body mass index 24.9 +/- 1.3 (SE) kg/m2], skeletal muscle blood volume was determined in the femoral region in the basal state and during euglycemic hyperinsulinemia (serum insulin 3,200 +/- 190 pmol/l). The mean muscle blood volume was 3.3 +/- 0.1 ml/0.1 kg muscle in the basal state. Insulin increased muscle blood volume by 9 +/- 2% to 3.6 +/- 0.2 ml/0.1 kg muscle (P < 0.01). The rate of whole body glucose uptake was 53 +/- 6 mumol.kg-1.min-1 and correlated with muscle blood volume during insulin stimulation (r = 0.65, P < 0.02). We conclude that high insulin concentrations exert a true vasodilatory effect in human skeletal muscle.

Adult↗

PubMed1995

Insulin action on heart and skeletal muscle glucose uptake in essential hypertension.

Essential hypertension is characterized by skeletal muscle insulin resistance but it is unknown whether insulin resistance also affects heart glucose uptake. We quantitated whole body (euglycemic insulin clamp) and heart and skeletal muscle (positron emission tomography and 18F-fluoro-2-deoxy-D-glucose) glucose uptake rates in 10 mild essential hypertensive (age 33 +/- 1 yr, body mass index 23.7 +/- 0.8 kg/m2, blood pressure 146 +/- 3/97 +/- 3 mmHg, VO2max 37 +/- 3 ml/kg per min) and 14 normal subjects (29 +/- 2 yr, 22.5 +/- 0.5 kg/m2, 118 +/- 4/69 +/- 3 mmHg, 43 +/- 2 ml/kg per min). Left ventricular mass was similar in the hypertensive (155 +/- 15 g) and the normotensive (164 +/- 13 g) subjects. In the hypertensives, both whole body (28 +/- 3 vs 44 +/- 3 mumol/kg per min, P < 0.01) and femoral (64 +/- 11 vs 94 +/- 8 mumol/kg muscle per min, P < 0.05) glucose uptake rates were decreased compared to the controls. In contrast, heart glucose uptake was 33% increased in the hypertensives (939 +/- 51 vs 707 +/- 46 mumol/kg muscle per min, P < 0.005), and correlated with systolic blood pressure (r = 0.66, P < 0.001) and the minute work index (r = 0.48, P < 0.05). We conclude that insulin-stimulated glucose uptake is decreased in skeletal muscle but increased in proportion to cardiac work in essential hypertension. The increase in heart glucose uptake in mild essential hypertensives with a normal left ventricular mass may reflect increased oxygen consumption and represent an early signal which precedes the development of left ventricular hypertrophy.

Adult↗

PubMed1995

Positron emission tomography study of human narcolepsy: no increase in striatal dopamine D2 receptors.

We investigated dopamine D2 receptors in the caudate nucleus and putamen with positron emission tomography in seven patients with narcolepsy and seven healthy controls by using [11C]raclopride as a ligand. We applied an equilibrium method and Scatchard principle to give a quantitative estimation of the number (Bmax) and dissociation constant (Kd) of the receptors. Both the Bmax and Kd were within the normal range in the caudate nucleus and putamen in narcoleptic patients. We found no evidence for increased D2 receptor binding in narcolepsy.

Adolescent↗

PubMed1995

Gender and insulin sensitivity in the heart and in skeletal muscles. Studies using positron emission tomography.

Good insulin sensitivity is independently associated with a low risk for coronary heart disease, but it is unclear whether this risk factor differs between men and women. We compared insulin sensitivity of glucose uptake directly in muscle and heart tissues between healthy women (age 29 +/- 2 years, body mass index [BMI] 22 +/- 1 kg/m2, VO2max 39 +/- 4 ml.kg-1.min-1) and men matched for age (31 +/- 2 years), BMI (23 +/- 1 kg/m2), and VO2max (44 +/- 3 ml.kg-1.min-1) using [18F]fluoro-2-deoxy-D-glucose and positron emission tomography under hyperinsulinemic (insulin infusion rate 1 mU.kg-1.min-1) normoglycemic conditions. Whole body insulin sensitivity was 41% greater in women (52 +/- 6 mumol.kg body wt-1.min-1) than in men (37 +/- 3 mumol.kg body wt-1.min-1, P < 0.05). This difference was explained by a 47% greater rate of glucose uptake by femoral muscles (113 +/- 10 vs. 77 +/- 7 mumol.kg muscle-1.min-1, women vs. men, P < 0.01). Insulin-stimulated glucose uptake rates in the heart were similar in women (738 +/- 58) and men (749 +/- 62 mumol.kg muscle-1.min-1). Femoral muscle insulin sensitivity was closely correlated with whole body insulin sensitivity (r = 0.84, P < 0.001). Gender and VO2max together explained 68% of the variation in femoral muscle glucose uptake. We conclude that women are more sensitive to insulin than equally fit men because of enhanced muscle but not heart insulin sensitivity.

Adult↗

PubMed1995

Carbon-11-methionine PET imaging of malignant melanoma.

UNLABELLED: The purpose of the study was to assess the feasibility of PET and L-[methyl-11C]methionine (11C-methionine) in the detection of malignant melanoma. METHODS: Ten patients diagnosed with malignant melanoma (two with primary melanoma and eight with metastatic melanoma of the skin) but had no liver metastases underwent a PET study before starting cancer therapy. Dynamic scanning was performed for 40 min in seven patients and 10-20 min in three patients 25-45 min postinjection. RESULTS: Carbon-11-methionine PET detected all melanoma lesions greater than 1.5 cm (n = 22) in diameter, whereas five smaller pulmonary lesions were not detected. The average standardized uptake value of the untreated lesions was 6.3 +/- 2.1 (n = 19) and the uptake rate (influx constant) was 0.085 +/- 0.041 min-1 (n = 16). CONCLUSION: PET imaging with 11C-methionine is an effective method for visualizing melanoma. It may also be useful in measuring tumor metabolic activity in vivo.

Adult↗

PubMed1995

FDG-PET in early infancy: simplified quantification methods to measure cerebral glucose utilization.

UNLABELLED: For further insight into the physiology and pathogenesis of the developing brain, quantification of the cerebral glucose metabolism is needed. Arterial blood sampling or sampling of great volumes of blood is not justified for the purpose of PET studies in children. Therefore, we have developed simplified PET approaches to analyze brain FDG examinations during infancy. METHODS: The study consisted of 18 FDG-PET examinations chosen from our research protocols concerning hypoxicischemic encephalopathy and severe neonatal hypoglycemia. The input function for graphical analysis according to Patlak was derived in two ways: (1) a combined time-activity curve derived from the left ventricular activity concentration (first 7-17 min of the study) and radioactivity concentration in venous whole-blood samples and; (2) activity concentration measured in whole-blood venous blood samples (arterial plasma in one case). As an alternative for semiquantitation, the standardized uptake values (SUV) were calculated and correlated to local cerebral metabolic rates for glucose (LCMRGlc). RESULTS: The influx rate constants (Ki) and LCMRGlc values obtained using the combined curve versus venous curve did not differ statistically (p > 0.05). There was a good correlation between the SUV and LCMRGlc values (r = 0.83, p < 0.001). CONCLUSION: Local cerebral metabolic rates for glucose can be accurately calculated by using the combined curve (left ventricular activity concentration during first 5 min of the study and 2-3 venous whole-blood samples at the end of the study) for even the smallest pediatric patients. When blood samples cannot be obtained, SUV values provide an alternative for estimation of the cerebral glucose uptake and interindividual comparison of the patients.

Brain↗

PubMed1995

Metabolic imaging of ovarian tumors with carbon-11-methionine: a PET study.

UNLABELLED: This study examines the potential of 11C-methionine as a PET tracer in metabolic imaging of benign and malignant ovarian tumors. METHODS: Four patients with one or two benign ovarian tumors (endometriomas or cystadenomas), two patients with a tumor of borderline malignancy and seven patients with ovarian cancer were studied with 11C-methionine and PET before laparotomy. CT or MRI were performed as a reference. Tracer uptake was quantitated by calculating tracer standardized uptake values (SUVs) and the kinetic influx constants (Ki values). RESULTS: Benign or borderline malignant tumors did not accumulate 11C-methionine, whereas all carcinomas had significant uptake. The mean SUV of the primary carcinomas was 7.0 (s.d., 2.2) and the mean Ki was 0.14 min-1 (s.d., 0.1 min-1), but the distribution of tracer uptake was highly heterogenous in four of six tumors. CONCLUSION: Ovarian cancer can be imaged with 11C-methionine and PET. This method also may be of value in the differential diagnosis between benign and malignant ovarian neoplasms. Due to physiological accumulations and methodological limitations, the value of 11C-methionine PET in the staging of ovarian cancer appears to be limited.

Adenocarcinoma, Clear Cell↗

PubMed1994

In vivo effects of insulin on tumor and skeletal muscle glucose metabolism in patients with lymphoma.

BACKGROUND: The anabolic properties of insulin have been suggested for use to reverse malnutrition associated with cancer. The host and tumor sensitivities to insulin are critical for such treatments, which aim to improve patient nutrition. The authors studied insulin effects on tumor and skeletal muscle metabolism with 2-[18F]-fluoro-2-deoxy-D-glucose ([18F]FDG) and positron emission tomography (PET). METHODS: Six patients with lymphoma twice underwent [18F]FDG-PET imaging: once after fasting overnight and once during euglycemic hyperinsulinemic clamp. The dynamic uptake of the glucose analogue [18F]FDG was measured in diseased nodes and upper arm skeletal muscle in both metabolic states. The [18F]FDG uptake in muscle and the whole body glucose use during euglycemic hyperinsulinemic clamp were compared with those of weight-matched healthy subjects studied under similar circumstances. RESULTS: In lymphomatous tissue, [18F]FDG uptake rates were similar in overnight fasting and euglycemic hyperinsulinemic clamp (38 +/- 10 versus 41 +/- 9 mumol/100 g/minute, not significant), whereas glucose uptake in skeletal muscle was increased by insulin (1.7 +/- 0.2 versus 3.8 +/- 0.5 mumol/100 g/minute, P = 0.012). Both basal (2.3 +/- 0.2 mumol/100 g/minute, P = 0.061) and insulin-stimulated (8.5 +/- 1.9 mumol/100 g/minute, P = 0.055) skeletal arm muscle glucose uptake rates were higher in control subjects than in patients. Whole body glucose use was 55% lower in patients than in control subjects (17 +/- 3 mumol/kg/minute versus 38 +/- 3 mumol/kg/minute, P = 0.002), consistent with insulin resistance in cancer. CONCLUSIONS: We found that insulin does not induce major changes in glucose uptake of lymphomatous tissue. Although insulin sensitivity of skeletal muscle was also reduced in patients with lymphoma, the net insulin effect may counteract imbalance between glucose uptake of tumor and muscle, offering a potential means to circumvent at least some metabolic abnormalities found in cancer.

Adult↗

PubMed1994

Striatal D2 dopamine receptor characteristics in neuroleptic-naive schizophrenic patients studied with positron emission tomography.

BACKGROUND: According to the D2 dopamine receptor hypothesis of schizophrenia, there is an increased number of D2 receptors in the brains of schizophrenic patients than in those of healthy controls. We tested this hypothesis in 13 newly admitted neuroleptic-naive schizophrenic patients and 10 healthy volunteers using positron emission tomography. METHOD: The quantification of striatal D2 dopamine receptor density (Bmax) and affinity (Kd) was done using an equilibrium model described for raclopride labeled with carbon 11. RESULTS: No statistically significant alterations were found in D2 receptor densities or affinities between the patient and control groups. However, a subgroup of four patients with a relatively high striatal D2 dopamine density was identified. Two patients, especially, had D2 dopamine densities almost twice as high as the mean control Bmax value. The Kd values also tended to be higher in this subset of patients than in the controls. No consistent striatal D2 dopamine receptor laterality was observed in schizophrenic patients or controls. However, an association of high D2 dopamine density in the left striatum and the mass of raclopride injected in the scan with low-specific radioactivity was observed in patients but not in controls. CONCLUSIONS: There are no general changes in D2 dopamine receptor Bmax or Kd values in neuroleptic-naive schizophrenics, but there may be a subgroup of patients with aberrant striatal D2 dopamine receptor characteristics in vivo.

Adult↗

PubMed1994

Striatal D2 dopamine receptor binding characteristics in vivo in patients with alcohol dependence.

Striatal D2 dopamine receptor characteristics of nine male patients with alcohol dependence abstinent for 1-68 weeks and eight healthy male volunteers were studied in vivo with positron emission tomography. The selective D2 receptor ligand [11C]raclopride and equilibrium model was used for D2 receptor density (Bmax) and affinity (Kd) measurements. A trend for a decreased striatal D2 receptor density and for reduced D2 receptor affinity was observed in patients with alcohol dependence. These parameters were not statistically significantly different between alcoholics and controls, but the ratio between D2 receptor density and affinity (Bmax/Kd or the striatum/cerebellum ratio from the high specific activity scan) was highly significantly lower in alcoholics than that of controls. In conclusion, the low D2 dopamine receptor Bmax/Kd ratio (striatum/cerebellum ratio) indicates that specific aspects of striatal [11C]raclopride binding in vivo are deviant in alcoholics compared to controls. The result is compatible with a reduced avidity of striatal dopamine D2 receptors in alcoholics, which is in line with the idea that D2 dopaminergic mechanisms are involved in the biology of alcohol dependence in man.

Adult↗

PubMed1994

Head and neck cancer: effect of food ingestion on uptake of C-11 methionine.

PURPOSE: To determine the influence of a standardized meal on tumor uptake measured with positron emission tomography (PET) and L-(methyl-carbon-11) methionine. MATERIALS AND METHODS: Five patients with untreated squamous cell cancer of the head and neck underwent PET, first in a fasting state and then 6-7 days later after ingesting a liquid meal. RESULTS: All tumors were seen on PET scans, and image quality remained good after food ingestion. The standardized uptake values of the tumors were 3.7-11.4 in the fasting state but decreased after the meal (range, 3.3-10.0; P < .04). No substantial change was measured in tumor C-11 methionine influx constants (Ki values). CONCLUSION: Although cancer imaging with PET and C-11 methionine can be performed even in the patient has not fasted, a standardized meal may decrease tumor C-11 methionine uptake.

Aged↗

PubMed1994

Effect of antilipolysis on heart and skeletal muscle glucose uptake in overnight fasted humans.

We quantitated how lowering of free fatty acid (FFA) by an antilipolytic agent (acipimox) in the fasting state changes glucose uptake in heart and skeletal muscles. Glucose uptake in these tissues was measured two times in seven normal subjects, once after acipimox and once after placebo, using positron emission tomography-derived [18F]fluoro-2-deoxy-D-glucose kinetics. Plasma glucose and insulin remained at their fasting concentrations in both studies. Fasting FFA concentrations were 60% lower after acipimox (238 +/- 39) than placebo (645 +/- 78 mumol/l, P < 0.001). Glucose uptake increased 6 +/- 2-fold in the heart by acipimox (344 +/- 49 vs. 108 +/- 40 mumol.kg muscle-1.min-1, P < 0.002) and 1.5-fold in arm muscles (27.7 +/- 2.6 vs. 18.6 +/- 1.2 mumol.kg muscle-1.min-1, P < 0.02). Heart (r = -0.93, P < 0.001) and arm (r = -0.82, P < 0.001) glucose uptakes were inversely related to serum FFA. We conclude that serum FFA are inversely related to glucose uptake in heart and arm skeletal muscles after an overnight fast. These data indicate that compensatory glycogenolysis, although it may occur, does not prevent operation of the glucose-FFA cycle under fasting conditions.

Adult↗

PubMed1994

Different alterations in the insulin-stimulated glucose uptake in the athlete's heart and skeletal muscle.

Physical training increases skeletal muscle insulin sensitivity. Since training also causes functional and structural changes in the myocardium, we compared glucose uptake rates in the heart and skeletal muscles of trained and untrained individuals. Seven male endurance athletes (VO2max 72 +/- 2 ml/kg/min) and seven sedentary subjects matched for characteristics other than VO2max (43 +/- 2 ml/kg/min) were studied. Whole body glucose uptake was determined with a 2-h euglycemic hyperinsulinemic clamp, and regional glucose uptake in femoral and arm muscles, and myocardium using 18F-fluoro-2-deoxy-D-glucose and positron emission tomography. Glucose uptake in the athletes was increased by 68% in whole body (P < 0.0001), by 99% in the femoral muscles (P < 0.01), and by 62% in arm muscles (P = 0.06), but it was decreased by 33% in the heart muscle (P < 0.05) as compared with the sedentary subjects. The total glucose uptake rate in the heart was similar in the athletes and control subjects. Left ventricular mass in the athletes was 79% greater (P < 0.001) and the meridional wall stress smaller (P < 0.001) as estimated by echocardiography. VO2max correlated directly with left ventricular mass (r = 0.87, P < 0.001) and inversely with left ventricular wall stress (r = -0.86, P < 0.001). Myocardial glucose uptake correlated directly with the rate-pressure product (r = 0.75, P < 0.02) and inversely with left ventricular mass (r = -0.60, P < 0.05) or with the whole body glucose disposal (r = -0.68, P < 0.01). Thus, in athletes, (a) insulin-stimulated glucose uptake is enhanced in the whole body and skeletal muscles, (b) whereas myocardial glucose uptake per muscle mass is reduced possibly due to decreased wall stress and energy requirements or the use of alternative fuels, or both.

Adult↗