Quantitative single-voxel spectroscopy: the reciprocity principle for receive-only head coils

PURPOSE: To correct MR spectra for local changes in the coil sensitivity for a widely used coil setup, consisting of a transmitting body coil and a receive-only head coil. MATERIALS AND METHODS: The method relies on the reciprocity principle for the body coil and a correction factor for signal amplitudes between body coil and head coil. The correction is based either on the local flip angle dependence of the stimulated echo acquisition mode signal (TFC) or on the automatic RF calibration (RFC). Water phantoms of different volumes were used to simulate variable coil loads, and B1 field inhomogeneities were assessed by varying the voxel position. Furthermore, the correction was tested by longitudinal measurements in one volunteer. RESULTS: The correction in vitro yields a reduction of the variation coefficient of the water signal by about 77% (TFC) and 66% (RFC) for different coil loads, as well as 55% (TFC) for variable voxel positions. Slightly lower reductions were assessed for the variation coefficients of the metabolite signals in vivo. CONCLUSION: This approach adequately compensates for local changes in coil sensitivity, when acquiring MR spectra with a receive-only head coil.     

Multidrug-resistant tuberculosis detection, Latvia

To improve multidrug-resistant tuberculosis (MDR-TB) detection, we successfully introduced the rpoB gene mutation line probe assay into the national laboratory in Latvia, a country with epidemic MDR-TB. The assay detected rifampin resistance with 91% sensitivity and 96% specificity within 1 to 5 days (vs. 12-47 days for BACTEC).     

Does electroconvulsive therapy (ECT) affect cognitive components of auditory evoked P300?

Electroconvulsive therapy (ECT), as a treatment tool for psychiatric disorders, is believed to be safe and effective. Nevertheless, it has a negative impact on cognitive functioning, especially on memory, causing both retrograde and anterograde amnesia. However, ECT effects on more subtle stages of information processing are not studied enough. Event-related potentials, and especially P300, are thought to reflect physiology of cognition. Thus, we aimed to evaluate the effects of ECT treatment on parameters of endogenous components (N2, P3) of the P300 potential. Seventeen patients suffering from schizophrenia, schizoaffective disorder and recurrent depressive disorder participated at the study. After the course of ECT, significant increase of N2 amplitude in parietal midline region and prolongation of P3 latency in frontal midline region, of which the magnitude positively correlated with the number of ECT procedures, have been obtained.     

Effects of psycho-social stress during pregnancy on neuroendocrine and behavioural parameters in lactation depend on the genetically determined stress vulnerability

The neuroendocrine consequences of repeated exposure of the pregnant mother to relevant stressors have been studied in the offspring, but not in the mothers. As these stress effects might depend on the genetically determined stress susceptibility of the dams, here, we investigated the effects of daily exposure to psycho-social stressors (maternal defeat by an aggressive lactating resident and restraint) between pregnancy days 4 and 18 in female rats selectively and bidirectionally bred for high (HAB) or low (LAB) anxiety-related behaviour. ACTH and corticosterone secretory responses to a mild stressor were found to be low in unstressed lactating HAB and LAB dams (day 8 of lactation) indicating an intact physiological attenuation of the HPA axis at this time. Pregnancy stress significantly increased the reactivity of the hypothalamo-pituitary-adrenal (HPA) axis in lactating HAB, but not LAB rats, reflecting impaired attenuation of the HPA axis selectively in pregnancy-stressed HAB dams. The high and low anxiety phenotypes were consistent in lactation and not significantly altered by pregnancy stress, despite an elevated level of arousal in pregnancy-stressed HAB dams. In general, HAB dams showed signs of a more protective maternal behaviour compared to LAB dams: (i) in the home cage, HAB dams spent more time in direct pup contact (day 1 of lactation), (ii) during two forms of the pup retrieval test, differing in the level of challenging the dam, HAB dams retrieved the pups faster, and (iii) during the maternal defence test, they were more aggressive towards a virgin intruder compared to LAB and NAB dams. Pregnancy stress did not alter any of these behavioural measures, except an increase in the speed of pup collection in a novel environment in HAB dams and increased maternal aggression in LAB dams. The results indicate a robust behavioural phenotype of HAB and LAB dams with respect to anxiety and maternal behaviour which was found to be almost unchanged by exposure to pregnancy stress. However, the finding of differential effects of pregnancy stress on the attenuation of the reactivity of the HPA axis in lactation makes HAB and LAB rats a potential animal model for studying genetically determined differences in stress vulnerability and stress-induced maladaptation of the HPA axis post-partum.     

Plasminogen activities and concentrations in patients with sporadic Creutzfeldt-Jakob disease

Human plasminogen has been shown to interact with the abnormal disease-specific prion protein. Till now, no data are available for patients with Creutzfeldt-Jakob disease (CJD). Therefore, we compared plasminogen concentrations and plasminogen activities in patients with sporadic CJD and controls with other dementia, which were collected in the framework of the German CJD Surveillance study. Patients with CJD had significantly higher plasminogen concentrations than patients with other forms of dementia and plasminogen specific activities were lower in CJD patients. The reasons for these abnormalities are not clear at the moment. The results may reflect a disease-specific prion protein and plasminogen interaction in patients with CJD. Other possible explanations are plasminogen polymorphisms and genotypes with distinct plasminogen activity levels in CJD than in controls, which should be a subject for further studies.     

Iron status in 2-year-old Icelandic children and associations with dietary intake and growth

OBJECTIVE: To investigate the effects of food and nutrient intake at 2 y and growth from birth on iron status at 2 y in a population with high birth weight. DESIGN: In a cross-sectional study, children's food consumption and body size measurements were recorded and blood samples taken. Weighed 3-day food records were used to analyse food and nutrient intake. SETTING: Children were recruited from across Iceland from the Icelandic National Registry by the University of Iceland, Computing Services. The children in the sample were born over a 1-y period. SUBJECTS: Parents of randomly selected 2-year-old children (n=130) were contacted, and 72% (n=94) participated. Blood samples were analysed in 76% (n=71) of participating children. RESULTS: In total, 9% of the children were iron-deficient (serum ferritin (SF)<12 microg/l and mean corpuscular volume (MCV) <74 fl) and 1.4% were also anaemic (Hb<105 g/l), while 27% of children were iron-depleted (SF<12 microg/l). Iron status indices were negatively associated with cow's milk consumption. Half of children consuming>500 g cow's milk/day (n=10) were iron-deficient, while one child in 58 consuming<500 g cow's milk/day had iron deficiency (P<0.001). In multiple regression analyses, also biscuits and crackers consumption was positively associated with MCV. Weight gain from birth to 2 y was negatively associated with SF (adjusted R(2)=0.15; P=0.002; n=58). Iron-depleted children were heavier than children not iron-depleted (14.7+/-1.3 vs 13.8+/-1.7 kg; P=0.043), had higher BMI (17.7+/-1.5 vs 16.7+/-1.4 kg/m(2); P=0.028) and gained more weight from birth (11.2+/-1.3 vs. 10.0+/-1.6 kg; P=0.011). CONCLUSIONS: The results suggest that cow's milk consumption above 500 g/day should be avoided at the age of 2 y for better iron status. Iron depletion at 2 y is associated with faster growth from birth.     

Akt activity in Alzheimer's disease and other neurodegenerative disorders

Enzyme activities of the serine/threonine kinase Akt were compared in mid-temporal and mid-frontal cortices from Alzheimer's disease cases and matched controls. Activities (GSK-3alpha/beta fusion protein phosphorylation by immunoprecipitated Akt) were significantly increased in temporal cortex soluble fractions from Alzheimer's disease compared with non-disease controls and positive disease controls with another neurodegenerative disease. Temporal cortex soluble fraction Akt activities positively correlated with Braak staging for neurofibrillary changes. Frontal cortex soluble fraction activities were significantly reduced in positive disease compared with Alzheimer's disease cases and non-disease controls. Strong Ser Akt immunoreactivity was seen in Alzheimer's disease pyramidal neurons likely undergoing degeneration and in reactive astroglia. Non-disease and positive disease controls showed moderate Ser Akt immunostaining of occasional pyramidal neurons.     

The pattern of sesame sensitivity among infants and children

Recently, we found sesame to be a major cause of severe IgE-mediated food allergic reactions among infants and young children in Israel. The purpose of this study was to describe the different patterns of sesame sensitivity. We have identified three subgroups among our patients (n = 32). Group I (n = 23, M/F; 14/9) consisted of cases with IgE-mediated sesame allergy. The mean age of the first allergic reaction was 11.7 months. Although the main clinical manifestation was urticaria/angiedema (n = 14, 60%), anaphylaxis was the presenting symptom in seven (30%) patients; all of them were younger than 1 year. Sixteen (70%) were found to be allergic to other foods, and other atopic diseases were identified in 18 (78%) patients. Three patients 'outgrew' their allergy within 1–2 years. Group II (n = 2) included cases in whom sesame allergy was ruled out based on a negative skin prick test (SPT) together with a negative open oral challenge. Group III (n = 7) consisted of patients that were found to be SPT positive for sesame as part of a screening for other food allergies. Although sesame products have become fashionable in westernized countries, early exposure may cause sesame to share eventually the same 'noteriety and fate' as peanut – a major cause of severe food allergic reactions.     

Low levels of mannose-binding lectin do not affect occurrence of severe infections or duration of fever in acute myeloid leukaemia during remission induction therapy

PURPOSE: To estimate the clinical significance of low serum concentrations of mannose-binding lectin (MBL) in patients with acute myeloid leukaemia (AML) during initial cancer chemotherapy. PATIENTS AND METHODS: 80 consecutive, newly diagnosed, and unselected AML patients (age 18-77 yr) undergoing remission induction chemotherapy. The patients were examined for 28 d. MAIN FINDINGS: Low levels of serum MBL (<1,000 microg/L) were found in 16/80 patients at diagnosis. This frequency is similar to what is found in the general population. In the remaining 64 patients, MBL concentrations were significantly higher than in controls and showed only a slight rise during the period of antineoplastic chemotherapy with its associated infectious complications. Low levels of MBL did not affect overall survival or morbidity in terms of incidence or duration of fever, or occurrence of septicaemia or pneumonia. Long-term survival was likewise independent of MBL concentration. CONCLUSION: MBL levels have no discernible influence on the occurrence or course of infections in AML patients during the initial hospitalisation. The predominant immunodeficiency during this phase is the profound granulocytopenia, which also compromises important effector functions of MBL. The finding in most AML patients of elevated MBL concentrations on admission is most likely because of the role of MBL as an acute phase reactant.