Biomedical subjects
A Alanen
Publications and source records attributed to A Alanen.
Sodium nitroprusside increases human skeletal muscle blood flow, but does not change flow distribution or glucose uptake.
1. The role of blood flow as a determinant of skeletal muscle glucose uptake is at present controversial and results of previous studies are confounded by possible direct effects of vasoactive agents on glucose uptake. Since increase in muscle blood flow can be due to increased flow velocity or recruitment of new capillaries, or both, it would be ideal to determine whether the vasoactive agent affects flow distribution or only increases the mean flow. 2. In the present study blood flow, flow distribution and glucose uptake were measured simultaneously in both legs of 10 healthy men (aged 29 +/- 1 years, body mass index 24 +/- 1 kg m-2) using positron emission tomography (PET) combined with [15O]H2O and [18F]fluoro-2-deoxy-D-glucose (FDG). The role of blood flow in muscle glucose uptake was studied by increasing blood flow in one leg with sodium nitroprusside (SNP) and measuring glucose uptake simultaneously in both legs during euglycaemic hyperinsulinaemia (insulin infusion 6 pmol kg-1 min-1). 3. SNP infusion increased skeletal muscle blood flow by 86 % (P < 0.01), but skeletal muscle flow distribution and insulin-stimulated glucose uptake (61.4 +/- 7. 5 vs. 67.0 +/- 7.5 micromol kg-1 min-1, control vs. SNP infused leg, not significant), as well as flow distribution between different tissues of the femoral region, remained unchanged. The effect of SNP infusion on blood flow and distribution were unchanged during infusion of physiological levels of insulin (duration, 150 min). 4. Despite a significant increase in mean blood flow induced by an intra-arterial infusion of SNP, glucose uptake and flow distribution remained unchanged in resting muscles of healthy subjects. These findings suggest that SNP, an endothelium-independent vasodilator, increases non-nutritive, but not nutritive flow or capillary recruitment.
Reduced brain creatine in gyrate atrophy of the choroid and retina with hyperornithinemia.
OBJECTIVE: To analyze in vivo brain creatine (Cr) content in gyrate atrophy of the choroid and retina with hyperornithinemia (GA). BACKGROUND: GA is caused by inherited deficiency of ornithine-delta-aminotransferase activity. Patients lose their vision by middle age and develop selective atrophy of type II skeletal muscle fibers. As demonstrated by MRS, the patients' skeletal muscles have diminished stores of high-energy Cr phosphate. Minor structural and electrophysiologic abnormalities in the brain of these patients also imply that the CNS may be affected. METHODS: The authors acquired proton MR spectra of the basal ganglia of 22 healthy control subjects and 20 GA patients. Nine patients received supplementary Cr or its precursors, and one child was on an arginine-restricted diet to normalize plasma ornithine concentration. The ratios of N-acetylaspartate (NAA) to Cr, NAA to choline (Cho), and Cho to Cr, and the ratios of NAA, Cho, and Cr to tissue water were calculated. RESULTS: NAA/Cr (Cho/Cr) in the untreated and treated patients and control subjects were (mean +/- SD) 3.3+/-0.4, 2.0+/-0.4, and 1.5+/-0.7 (1.9+/-0.3, 1.3+/-0.4, and 0.9+/-0.2), indicating that Cr content in untreated GA patients was proportionally and markedly diminished, and partially corrected by therapy (p < 0.0001). NAA/Cho was similar in all three groups. Cr/water in the untreated patients was only 46%, and increased to 75% of the control ratios in the treated patients (p < 0.0001). CONCLUSIONS: Hyperornithinemia-associated Cr deficiency in GA also affects the CNS, further supporting the possibility that Cr deficiency also has a pathogenetic role in the retina. The deficiency was partially corrected by Cr supplementation and an arginine-restricted diet.
Prediction of pre-eclampsia with maternal mid-trimester total renin, inhibin A, AFP and free beta-hCG levels.
We wanted to study if maternal serum mid-trimester total renin, inhibin A, AFP or free beta-hCG levels predict the development of pre-eclampsia. Maternal serum alpha-fetoprotein (AFP) and human chorion gonadotrophin (beta-hCG) were evaluated in the screening programme for Down syndrome in 4356 patients prospectively. Data on pregnancy outcome were available in 1242 women. Pregnancy-induced hypertension (PIH) developed in 69 women, 282 women with uneventful pregnancy outcome were selected for controls. Serum total renin and inhibin A levels were measured retrospectively in the trisomy screening samples of 69 and 30 patients who later developed PIH, and in 282 and 7 patients, respectively, who had an uneventful pregnancy outcome. No significant differences were found in the levels of maternal mid-trimester serum total renin, inhibin A or free beta-hCG levels between PIH and healthy women. The multiples of the median (MoM) of AFP values were significantly higher in the subgroup of patients who later developed severe pre-eclampsia than in patients with mild pre-eclampsia or gestational hypertension and healthy pregnant women. Maternal mid-trimester serum levels of total renin, inhibin A and free beta-hCG are not predictive for development of PIH. High mid-trimester serum AFP values may help in the prediction of severe pre-eclampsia.
Central nervous system involvement in gyrate atrophy of the choroid and retina with hyperornithinaemia.
In gyrate atrophy of the choroid and retina with hyperornithinaemia (GA), a genetically determined deficiency of ornithine delta-aminotransferase activity leads to high ornithine concentrations in body fluids. GA is characterized by centripetally progressing retinal and choroidal destruction and selective atrophy with tubular aggregates in type II skeletal muscle fibres. These findings have been suggested to be mediated by hyperornithinaemia-induced deficiency of high-energy creatine phosphate. As abnormal brain magnetic resonance images and electroencephalograms are found in another disorder of creatine metabolism, guanidinoacetate methyltransferase deficiency, we investigated the central nervous system involvement in GA, which seems to be associated with a milder degree of phosphocreatine deficiency. We compared 23 untreated GA patients with age-matched healthy controls, and with 9 patients who had received creatine or creatine precursor supplementation daily for several years. The mean age of the patients (32 +/- 18 years) was similar to that of the controls (36 +/- 22 years). The MRI or EEG findings of the patients on creatine supplementation did not differ from those of the untreated group. Brain MRI revealed degenerative lesions in the white matter in 50% of the GA patients, and 70% of the patients had premature atrophic changes, with a striking increase in the number of Virchow's spaces. Of the patients whose EEG was recorded, 58% had abnormal slow background activity, focal lesions or high-amplitude beta rhythm (> 50 microV). The EEG findings were not associated with the MRI changes or with the age or the sex of the patients. Early degenerative and atrophic brain changes and abnormal EEG are thus features of GA, in addition to the well-characterized eye and muscle manifestations.
Muscle creatine phosphate in gyrate atrophy of the choroid and retina with hyperornithinaemia--clues to pathogenesis.
BACKGROUND: In gyrate atrophy of the choroid and retina with hyperornithinaemia (GA), inherited deficiency of ornithine-o-aminotransferase leads to progressive fundus destruction and atrophy of type II skeletal muscle fibres. Because high ornithine concentrations inhibit creatine biosynthesis, the ensuing deficiency of high-energy creatine phosphate may mediate the pathogenesis. MATERIALS AND METHODS: Relative concentrations of inorganic phosphate (Pi), creatine phosphate (PCr) and ATP in resting calf muscle were recorded in 23 GA patients and 33 control subjects using 31P-magnetic resonance spectroscopy (MRS). Eight patients with autosomal recessive retinitis pigmentosa with matched control subjects constituted an additional reference group. RESULTS: The PCr/Pi and PCr/ATP ratios (means +/- SD) were lower for the GA patients than for healthy control subjects [4.66 +/- 0.37 vs. 9.75 +/- 2.17 (P < 0.0001) and 2.85 +/- 0.37 vs. 3.70 +/- 0.50 (P < 0.05) respectively]. In retinitis pigmentosa the respective values were 9.12 +/- 2.57 and 4.25 +/- 0.45. Age and stage of the disease had no effect. CONCLUSION: Muscle 31P-MRS spectra were markedly abnormal in all GA patients.
Creatine corrects muscle 31P spectrum in gyrate atrophy with hyperornithinaemia.
BACKGROUND: Eye fundus destruction and type II muscle fiber atrophy in gyrate atrophy of the choroid and retina with hyperornithinaemia (GA) may be mediated by elevated ornithine concentrations which strongly inhibit creatine biosynthesis. This results in deficiency of creatine phosphate (PCr), a key intracellular energy source, as we have demonstrated in skeletal muscle of the patients by 31P magnetic resonance spectroscopy (31P MRS). MATERIALS AND METHODS: Possible correction of the relative PCr deficiency by long-term daily exogenous supplementation of creatine or its precursors was investigated in four GA patients receiving creatine and in five patients treated with guanidinoacetic acid-methionine combination. The relative PCr concentration, expressed as PCr/Pi (Pi; inorganic phosphate) or as PCr/ATP ratios, was compared with the values of untreated GA patients, and matched healthy volunteers. RESULTS: Muscle PCr/Pi ratios (mean +/- SD) of the untreated and creatine supplemented GA patients and controls were 4.9 +/- 1.4, 7.9 +/- 0.4 and 8.4 +/- 1.3. Guanidinoacetate-methionine combination was similarly effective (respective PCr/Pi ratios: 4.9 +/- 0.7, 6.3 +/- 1.1 and 10.7 +/- 2.8). CONCLUSION: Supplementation with creatine or creatine precursors almost normalised low muscle PCr/Pi ratios of patients with GA.
Second-trimester abortion caused by Capnocytophaga sputigena: case report.
Intra-amniotic infection is often the cause of a second-trimester abortion. The bacterial species involved include bacteria with low pathogenicity like Ureaplasma urealyticum and various Mycoplasma species. In this case we describe an intra-amniotic infection caused by Capnocytophaga sputigena, often found in the normal bacterial flora of the oral cavity, but not in the vagina. Oral sex during pregnancy was the most probable source of the infection. The aborted fetus showed signs of pneumonia upon histologic examination. The bacterial species was identified using broad-spectrum 16S rDNA polymerase chain reaction (PCR) directly from the amniotic fluid and after bacterial culture. Amniotic fluid glucose was below detection level, confirming the presence of an intra-amniotic infection.
Magnetic resonance imaging and proton MR spectroscopy in Wilson's disease.
MRI of the brain and liver using T2 relaxation time measurements and proton spectroscopy (1H-MRS) of the brain was performed in four siblings with Wilson's disease (one with clinical disease and three asymptomatic) as well as age- and sex-matched control subjects. The T2 values of the liver were correlated with liver biopsy results. 1H-MRS of the left and right globus pallidus was obtained. The patient with clinical disease was examined three times, and two of three asymptomatic siblings twice. MR images of the brain were abnormal in all four patients. High signal intensity areas in the posterior thalamus, general atrophy and pontine myelinolysis were present in the patient with clinical manifestations. The T2 measurements of these areas confirmed the results of image analysis. Apart from general brain atrophy, the changes in the patient with clinical disease were largely reversible. The T2 values were significantly different from those of the control subjects only in the globus pallidus. The NAA/Cho, NAA/Cr and Cho/Cr ratios from the 1H-MR spectra of globus pallidus showed no significant difference between patients and control subjects. The mean values of NAA/Cho and NAA/Cr were lower in patients with Wilson's disease than in the control subjects. One of the patients had hepatic steatosis, but the liver T2 values were no different to those of the control subjects. In conclusion, the MRI findings reflect the success of the specific therapy in patients. MRI thus seems to be useful in the follow-up of Wilson's disease.
Sinusitis in the common cold.
BACKGROUND: Acute community-acquired sinusitis is considered a bacterial complication of the common cold. Radiologic abnormalities in sinuses occur, however, in most patients with upper respiratory virus infections. OBJECTIVE: Assessment of the occurrence, clinical profile, laboratory findings, and outcome of radiologically confirmed sinusitis was carried out as part of a common cold study in young adults. METHODS: Clinical examinations and radiography of the paranasal sinuses were carried out on days 1, 7, and 21 in 197 patients with the common cold. The symptoms were recorded on diary cards on days 1 to 20. Ten viruses and 5 bacteria were studied as etiologic agents of common cold as reported earlier. Serum C reactive protein concentrations, erythrocyte sedimentation rates, and total white blood cell counts with differentials were determined in 40 randomized subjects on day 7. The effect of 6 days of intranasal fluticasone propionate treatment of the common cold in the prevention of sinusitis was analyzed. RESULTS: On day 7, 39% of patients with the common cold in the placebo group (n = 98) had sinusitis, which we would prefer to call viral sinusitis. The symptoms of patients with sinusitis and those without it were not clinically distinguishable. Viral infection was detected in 81.6% of patients with sinusitis. No significantly increased levels of antibodies to bacteria were detected. Serum C reactive protein concentrations, erythrocyte sedimentation rates, and white blood cell counts were low in patients with sinusitis. All patients made a clinical recovery within 21 days without antibiotic treatment. Fluticasone propionate treatment tended to prevent paranasal sinusitis, especially in rhinovirus-positive subjects. CONCLUSION: Viral sinusitis frequently occurs in the early days of the common cold, but it is a self-limited illness. The sinuses should not be imaged in patients with the common cold if the signs and symptoms of illness gradually become less severe and no specific signs suggestive of bacterial sinusitis occur.
Low field T1rho imaging of myositis.
The purpose of this study was to evaluate 1/T1rho in relation to 1/T1 and 1/T2 in characterizing normal and diseased muscle. We measured the muscle relaxation rates 1/T1 and 1/T2 at 0.1 T and 1/T1rho at on-resonance locking fields B1 between 10 and 160 microT in myositis patients and normal volunteers. 1/T2 and 1/T1rho of muscle were lower in the patients than in the volunteers, whereas there was no difference in the 1/T1 values. The lower relaxation rates 1/T2 and 1/T1rho in the diseased muscle may be due to fat and connective tissue infiltrations and edema. 1/T1rho contrast between muscle and subcutaneous fat was higher than 1/T2 and 1/T1 contrast. This may be explained by the different B1 dispersion behavior of these two tissue types. 1/T1rho of fat is B1 field independent, whereas 1/T1rho of muscle decreases clearly with increasing B1 field. In conclusion, 1/T1rho provides a useful tool in manipulating contrast in magnetic resonance imaging of diseased muscle.
MR and magnetisation transfer imaging in cirrhotic and fatty livers.
PURPOSE: To determine whether low-field MR fat/water separation and magnetisation transfer (MT) techniques are useful in studying the livers of patients with parenchymal liver diseases in vivo. MATERIAL AND METHODS: MR and MT imaging of the liver in 33 patients (14 with primary biliary cirrhosis, 15 with alcohol-induced liver disease, and 4 with fatty liver) was performed by means of the fat/water separation technique at 0.1 T. The relaxation time T1 and the MT contrast (MTC) parameter of liver and spleen tissue were measured, and the relative proton density fat content N(%) and MTC of the liver were calculated from the separate fat and water images. The value of N(%) was also compared with the percentage of fatty hepatocytes at histology. RESULTS: The relaxation rate R1 of liver measured from the magnitude image, and the difference in the value of MTC measured from the water image compared with the one measured from the fat and water magnitude image, both depended linearly on the value of N(%). The value of N(%) correlated significantly with the percentage of the fatty hepatocytes. In in vivo fatty tissue, fat infiltration increased both the observed relaxation rate R1 and the measured magnetisation ratio (the steady state magnetisation MS divided by the equilibrium magnetisation MO, MS/MO) and consequently decreased the MT efficiency measured in a magnitude MR image. The amount of liver fibrosis did not correlate with the value of MTC measured after fat separation. CONCLUSION: Our results in studying fatty livers with MR imaging and the MT method show that the fat/water separation gives more reliable parametric results. Characterisation of liver cirrhosis by means of the MTC parameter is not reliable, even after fat separation.
Polymerase chain reaction in the detection of microbes in amniotic fluid.
Intra-amniotic infection during pregnancy can be caused by bacteria, viruses or protozoa, Toxoplasma gondii for example. Bacterial intrauterine infections are connected with premature birth, premature rupture of fetal membranes, and infective complications of both the mother and the newborn. Viral infections and Toxoplasma gondii can cause fetal malformations and illness with serious sequelae to the infant or fetal death in utero. Determining the causative agent is important and often greatly affects the prognosis of the newborn. Amniotic fluid is in most cases easily and safely obtainable during the second and third trimester and can be used in several microbiological assays. These include bacterial and viral cultures, Gram staining, quantitative assays for immunoglobulins or cytokines, and polymerase chain reaction (PCR) for detecting microbial DNA. This review concentrates on broad-spectrum or universal bacterial PCR for detection of bacterial DNA in amniotic fluid and on PCR assays for certain clinically important viruses and for Toxoplasma gondii.
Effect of fasting and food intake on magnetization transfer of human liver tissue.
Magnetization transfer (MT) technique is a promising method in differential diagnosis of diseases in parenchymal tissues. Basic knowledge about circumstances and elementary factors that influence MT and its parameters is still insufficient, however. Having a meal before the magnetic resonance (MR) examination could change liver MT parameters compared to fasting state through alteration in liver perfusion, blood flow, and content of portal blood (proteins and other derivates from a meal). If MT parameters can be altered by a meal, then MR liver studies should always be performed after fasting. Before MRI examinations we examined three healthy volunteers after a high-fat meal with Doppler ultrasound technique to find out duration and magnitude of changes in portal blood flow. Duration of > or = 50% increased peak-flow value compared to fasting state in portal vein was > 90 min, which is enough for our MR examination. With a low-field 0.1-T MR imager we examined 10 healthy volunteers after a short (range from 3 h 45 min to 17 h 30 min) fast and also immediately after a high-fat meal. Magnetization transfer parameters, magnetization transfer ratio (MTR) and magnetization transfer rate Rwm of liver tissue were determined. MTR changed significantly (Student paired two-tailed t-test, p = .0044) after a meal, but Rwm did not (p = .0952). We recommend a 4 h fast before MR examination that aims to determine the MTR of liver tissue.
Skeletal muscle of patients with gyrate atrophy of the choroid and retina and hyperornithinaemia in ultralow-field magnetic resonance imaging and computed tomography.
Gyrate atrophy of the choroid and retina with hyperornithinaemia (GA), an autosomal recessive disease, affects skeletal muscle in addition to the eye. Muscle biopsy samples show prominent type 2 muscle fibre atrophy. Atrophic fibres also contain accumulations of tubular aggregates in electron microscopy. To evaluate skeletal muscle involvement in detail, the thigh muscles of 7 patients with GA were examined using semi-open conchotome muscle biopsies, computed tomography (CT) and ultralow-field magnetic resonance imaging (MRI) at 0.02 T. In MRI, the T1 and T2 proton relaxation times were measured. Type 2 muscle fibre atrophy was found in all biopsy samples (100%) and tubular aggregates in 6 of the 7 samples studied (87%). The CT density of the muscle tissue was increased in the only child of the study, decreased in 3 elderly subjects, and normal in the remaining 3 patients. Mean T1 relaxation times of the patients were decreased (135 +/- 5 ms) as compared to those of 6 healthy controls (157 +/- 12 ms) (p = 0.002). The T2 relaxation time was slightly increased (40 +/- 3 ms) as compared to the controls (35 +/- 7 ms; not significant, p = 0.3). Our findings suggest that the thigh muscles of the patients with GA universally show changes in CT and MRI studies, but relaxation time measurements gave little additional information on the muscle metabolism.
Echogenicity of sonographic contrast media at variable shear rates and concentrations.
Explore the source record for details and available documents.
Bacterial 16S rDNA polymerase chain reaction in the detection of intra-amniotic infection.
OBJECTIVE: Bacterial polymerase chain reaction (PCR) was used to detect early subclinical intraamhiotic infection. We used universal primers which amplify a DNA fragment of 16S ribosomal DNA (rDNA) from all known bacteria and sequenced the positive samples to identify the bacterial species. DESIGN: Transabdominally obtained amniotic fluid samples from 20 pregnant women with prelabour rupture of the fetal membranes (PROM), showing no signs of clinical infection, and 16 control samples were analysed with universal bacterial PCR. In addition, routine bacterial culture and amniotic fluid glucose were studied. RESULTS: Out of 20 PROM patients, five were positive in the PCR. PCR detected Ureaplasma urealyticum in two cases, Haemophilus influenzae in one case, Streptococcus oralis in one case and Fusobacterium sp. in one case. Only two of these were positive in a routine bacterial culture. Both were multibacterial infections, which caused discrepancies between the PCR and culture results. Two patients developed infectious complications: both were identified with the PCR assay. Amniotic fluid glucose was lower in PCR positive patients compared with PCR negative patients. CONCLUSION: Bacterial 16S rDNA PCR, in properly controlled conditions, promises to be a fast and reliable test for early intra-amniotic infection especially concerning Ureaplasma urealyticum.