Natural history of mild cognitive impairment in older persons

BACKGROUND

Cognitive abilities of older persons range from normal, to mild cognitive impairment, to dementia. Few large longitudinal studies have compared the natural history of mild cognitive impairment with similar persons without cognitive impairment.

METHODS

Participants were older Catholic clergy without dementia, 211 with mild cognitive impairment and 587 without cognitive impairment, who underwent annual clinical evaluation for AD and an assessment of different cognitive abilities. Cognitive performance tests were summarized to yield a composite measure of global cognitive function and separate summary measures of episodic memory, semantic memory, working memory, perceptual speed, and visuospatial ability. The authors compared the risk of death, risk of incident AD, and rates of change in global cognition and different cognitive domains among persons with mild cognitive impairment to those without cognitive impairment. All models controlled for age, sex, and education.

RESULTS

On average, persons with mild cognitive impairment had significantly lower scores at baseline in all cognitive domains. Over an average of 4.5 years of follow-up, 30% of persons with mild cognitive impairment died, a rate 1.7 times higher than those without cognitive impairment (95% CI, 1.2 to 2.5). In addition, 64 (34%) persons with mild cognitive impairment developed AD, a rate 3.1 times higher than those without cognitive impairment (95% CI, 2.1 to 4.5). Finally, persons with mild cognitive impairment declined significantly faster on measures of episodic memory, semantic memory, and perceptual speed, but not on measures of working memory or visuospatial ability, as compared with persons without cognitive impairment.

CONCLUSIONS

Mild cognitive impairment is associated with an increased risk of death and incident AD, and a greater rate of decline in selected cognitive abilities.

Hepatocyte nuclear factor 1 inactivation results in hepatic dysfunction, phenylketonuria, and renal Fanconi syndrome

HNF1 is a transcriptional activator of many hepatic genes including albumin, alpha1-antitrypsin, and alpha- and beta-fibrinogen. It is related to the homeobox gene family and is predominantly expressed in liver and kidney. Mice lacking HNF1 fail to thrive and die around weaning after a progressive wasting syndrome with a marked liver enlargement. The transcription rate of genes like albumin and alpha1-antitrypsin is reduced, while the gene coding for phenylalanine hydroxylase is totally silent, giving rise to phenylketonuria. Mutant mice also suffer from severe Fanconi syndrome caused by renal proximal tubular dysfunction. The resulting massive urinary glucose loss leads to energy and water wasting. HNF1-deficient mice may provide a model for human renal Fanconi syndrome.

Depressive symptoms, cognitive decline, and risk of AD in older persons

BACKGROUND

Cross-sectional and retrospective case-control studies suggest an association of depression symptoms with cognitive impairment and AD, but there have been few prospective studies and their results have been inconsistent.

METHODS

Participants are Catholic clergy members who were aged > or =65 years and who did not have clinical evidence of AD. During a 7-year period, they underwent annual clinical evaluations that included clinical classification of AD and detailed cognitive function testing from which global and specific measures of cognition were derived. Number of depressive symptoms was assessed at baseline with a modified, 10-item Center for Epidemiologic Studies Depression Scale (CES-D). The association of CES-D score with incident AD, using proportional hazards models, and cognitive decline, using random effects models, was examined.

RESULTS

At baseline, participants reported an average of about one depressive symptom on the CES-D scale (range, 0 to 8). During the 7 years of follow-up, 108 persons developed AD. In analyses that controlled for selected demographic and clinical variables including baseline level of cognitive function, CES-D score was associated with both risk of AD and rate of cognitive decline. For each depressive symptom, risk of developing AD increased by an average of 19%, and annual decline on a global cognitive measure increased by an average of 24%.

CONCLUSIONS

The results raise the possibility that depressive symptoms in older persons may be associated with risk of developing AD.

Melanin binds reversibly to thermostable DNA polymerase and inhibits its activity

We found that both RNA and cDNA preparations derived from melanocytes contain a RT-PCR inhibitor that copurified with nucleic acids. Investigation of the candidate inhibitor melanin revealed that it potently blocks PCR at concentrations below 200 ng/ml, whereas 100 microg/ml melanin was required to inhibit reverse transcription. Melanin and thermostable DNA polymerase preferentially formed a distinct complex with reduced migration velocity as compared to pure polymerase in nondenaturating polyacrylamide gel electrophoresis. The inhibition of the enzyme by melanin could be reversed by diluting solutions of preformed complexes or by adding excess amounts of other proteins such as bovine serum albumin or dry milk. Our findings demonstrate that melanin is a potent inhibitor of thermostable DNA polymerase in vitro and that the inhibitory effect is conferred by a direct and reversible polymerase-melanin interaction.

The treatment of scoliosis in Duchenne muscular dystrophy

There are not, as yet, clear indications for the surgical management of scoliosis in Duchenne muscular dystrophy (DMD), taking into account the varying severity of the clinical course. Monitoring the vital capacity can be most important for the indication and timing of surgery. In some cases, delaying surgical intervention with conservative management using spinal braces and wheelchair inserts can permit the restrictive lung syndrome to advance to the point that surgery will be contraindicated. Ten such patients conservatively treated for an average of 5 years exhibited perhaps a slower progression but ultimately an advanced deformity. From a second group of five carefully selected and surgically treated patients, indications for spinal surgery were reviewed. Surgical intervention should be prophylactically undertaken when there is high risk of a rapidly evolving curve with a severe restrictive lung syndrome.

Effects of solvent/detergent-treated plasma and fresh-frozen plasma on haemostasis and fibrinolysis in complex coagulopathy following open-heart surgery

BACKGROUND AND OBJECTIVES

Solvent/detergent-treated plasma (SDP) contains markedly lower protein S (PS) and plasmin inhibitor (PI) activity than standard fresh-frozen plasma (FFP). It has also been reported that SDP contains no alpha(1)-antitrypsin. Despite the lack of clinical data, it is suspected that SDP may be less effective than FFP in the treatment of complex coagulopathies. We therefore conducted a prospective trial to study the impact of SDP and FFP on haemostasis and fibrinolysis in complex coagulopathy after open-heart surgery.

MATERIALS AND METHODS

Patients received either 600 ml of SDP (n = 36) or 600 ml of FFP (n = 31) at an infusion rate of 30 ml/min. The following parameters were measured before treatment and 60 min after termination of plasma infusion: prothrombin time (PT), activated partial thromboplastin time (APTT), fibrinogen, factor VIII, antithrombin, protein C (PC), free PS and PS activity, prothrombin fragments F1+2 (F1+2), D-dimers (DD), fibrinogen degradation products (FDP), plasmin-plasmin inhibitor complexes (PPI), plasminogen, PI and alpha(1)-antitrypsin.

RESULTS

The rise in fibrinogen, factor VIII, antithrombin, PC, free PS, alpha(1)-antitrypsin and plasminogen, and the decrease in PT and APTT, did not significantly differ between the two study arms. However, PS activity did not increase after SDP infusion but did show a significant elevation after infusion with FFP. PI declined significantly after SDP and remained uninfluenced by FFP. Neither SDP nor FFP had any significant influence on F1+2, DD or FDP. However, a significant decrease in PPI levels caused by both types of plasma indicated a reduction in hyperfibrinolysis. Clinical haemostasis evaluation revealed no significant difference between the two treatment regimens. No adverse reactions were observed.

CONCLUSION

With the exception of PS and PI, SDP and FFP improved haemostasis and fibrinolysis to a similar degree. The clinical significance of these findings has to be determined in patients with severe acquired PS and PI deficiency requiring plasma transfusions.

Effects of the fungicide prochloraz on xenobiotic metabolism in rainbow trout: inhibition in vitro and time course of induction in vivo

1. Interactions between the fungicide prochloraz and the hepatic cytochrome P-450 of rainbow trout were studied by determination of enzymic activities in vitro using the microsomal fraction, and by kinetic studies. 2. Prochloraz inhibited 7-ethoxyresorufin-O-deethylase (EROD) in vitro. This inhibition was partially non-competitive: the enzyme-substrate-inhibitor (ESI) complex was catalytically active (68% of the activity of the enzyme-substrate complex). 3. Prochloraz in vitro inhibited aldrin epoxidase (AE) by a linear mixed-type mechanism. This inhibition might be high because of high affinity for prochloraz and lack of catalytic activity of the ESI complex. 4. Effects of prochloraz in vivo were studied as a function of time after intraperitoneal injection. Total cytochrome P-450 increased for more than 21 days. 5. EROD increased slightly at day 4 and then returned to control level. Kinetics showed an increase in apparent Km and Vmax. AE was strongly inhibited at day 4 (large increase in apparent Km) and then returned to control level in 21 days. 6. Spectral interactions with aniline showed strong inhibition and recovery to an activated level at day 21.

The hydroxyanilide fenhexamid, a new sterol biosynthesis inhibitor fungicide efficient against the plant pathogenic fungus Botryotinia fuckeliana (Botrytis cinerea)

Fenhexamid, a recently developed botryticide, is shown here to inhibit sterol biosynthesis. When the fungus Botryotinia fuckeliana was grown in the presence of fenhexamid, the ergosterol content was reduced, and three 3-keto compounds, 4 alpha-methylfecosterone, fecosterone and episterone, accumulated, suggesting an inhibition of the 3-keto reductase involved in C-4 demethylation. Thus, fenhexamid belongs to a new, promising class of sterol biosynthesis inhibitors not previously used in agriculture or in medicine.

Coagulation factor XII (FXII) activity, activated FXII, distribution of FXII C46T gene polymorphism and coronary risk

BACKGROUND

Whether factor XII (FXII) activity, its 46C>T polymorphism and activated FXII (FXIIa) are associated with coronary heart disease (CHD) remains to be determined.

METHODS

FXII, FXIIa and the FXII 46C>T polymorphism were determined in a hospital-based cohort of 2615 patients undergoing coronary angiography.

RESULTS

Fifty-seven per cent of the participants were identified as wild-type (46CC), 38% as heterozygous (46CT) and 5% as homozygous (46TT) for FXII 46C>T. FXII and FXIIa levels were significantly lower in carriers of the T-allele: 132 (97-151) U dL(-1) FXII in 46CC, 87 (77-99) U dL(-1) FXII in 46CT and 53 (42-67) U dL(-1) FXII in 46TT carriers (P < 0.001), and 2.8 (2.3-3.5) microg L(-1) FXIIa in CC, 2.1 (1.6-2.6) microg L(-1) FXIIa in CT and 1.2 (0.9-1.5) microg L(-1) FXIIa in TT carriers (P < 0.001; medians, lower and upper quartiles). Patients with stable CHD (n = 935), a history of myocardial infarction (n = 785) or who were suffering from acute coronary syndromes (ACS; n = 323) had significantly lower FXII levels than controls (n = 572). The differences remained statistically significant after adjustments for age, sex, diabetes mellitus, smoking, hypercholesterolemia and hypertension. Significantly reduced FXIIa levels in ACS patients lost significance once adjusted for covariates. FXII genotype was not associated with any clinical phenotype.

CONCLUSION

Lower FXII activity represents an independent risk for CHD and ACS. This is not the case for FXIIa levels or the FXII 46C>T variation.

Rat models of autosomal dominant polycystic kidney disease

Several rat models of polycystic kidney disease (PKD) have been published. The only rat model of autosomal dominant polycystic kidney disease currently used is the so-called Hannover rat (Han:SPRD cy/+). This model is characterized by a slow progression of uraemia, proteinuria and hyperlipidaemia. Histological changes clearly resemble those seen is human PKD. The localization of Na+/K(+)-ATPase correlating with the phenotype of the cysts--basal in moderately expanded and apical in highly expanded cysts--suggests that the mislocation of the Na+/K(+)-ATPase is involved in the mechanism of cyst expansion rather than formation, and a consequence of cell dedifferentiation rather than an initial event. Of note is a considerable gender difference in disease severity. Disease anticipation or genetic imprinting does not occur. In addition to gender, a number of interventions influence the progression rate: acceleration is noted after unilateral nephrectomy, the induction of acidosis, chloride feeding or an increased protein intake; slowing down of the course occurs after the induction of alkalosis and castration, and after treatment with lovastatin and methylprednisolone. Thus the Han:SPRD cy/+ rat represents the only well-documented rat model of autosomal dominant PKD resembling a number of features of the human disease.

Effects of the fungicide prochloraz on xenobiotic metabolism in rainbow trout: in vivo induction

1. Rainbow trout were dosed with prochloraz by i.p. injection of sprayed food pellets. Cytochrome P-450, two P-450-dependent activities, and two conjugase activities were measured in vitro in microsomal or cytosolic fractions. 2. Prochloraz increased cytochrome P-450 in liver, intestine, and pyloric caeca: maximum response occurred at 30-100 mg/kg i.p. In cold conditions, this increase persisted for more than 8 days after injection. 3. Hepatic 7-ethoxycoumarin-O-dealkylase (ECOD) and 7-ethoxyresorufin-O-dealkylase (EROD) were inhibited by prochloraz except in one assay in warm water where they increased. In intestine and pyloric caeca, ECOD and EROD were not detected, even when cytochrome P-450 was increased. 4. UDP-glucuronosyltransferase (1-naphthol as substrate) was unchanged or inhibited after prochloraz dosing. 5. Glutathione-S-transferase (o-dinitrobenzene as substrate), was unchanged or inhibited by prochloraz. 6. The measured level of enzymic activities was the result of induction and inhibition by prochloraz residues. Variations in basal activities and perhaps in prochloraz interactions were due to temperature acclimatization.

Alternative splicing of caspase-8 mRNA during differentiation of human leukocytes

Caspase-8 is a key initiator of death receptor-induced apoptosis. Here we provide evidence that caspase-8 expression is subject to posttranscriptional regulation in human leukocytes. Resting peripheral blood lymphocytes preferentially use a distant splice donor site at the 3'-end of caspase-8 exon 8 to generate mRNAs with a truncated open reading frame. When lymphocytes were activated, the expression of caspase-8 variants was shifted to caspase-8/a and b which lack the extension of exon 8. The opposite change of the splicing pattern was found in a neutrophil differentiation model. Promyelocytic HL-60 cells mainly expressed caspase-8 mRNAs with the normal exon 8, but the splicing pattern was changed to the distant exon 8 splice site during DMSO-induced differentiation of HL-60 cells. In spite of the presence of these novel mRNAs, the corresponding translation products were not detectable in either cell type. Our findings suggest that leukocyte differentiation and alternative splicing of caspase-8 pre-mRNA are inter-dependent processes.

Radio Frequency Signals in Jupiter's Atmosphere

During the Galileo probe's descent through Jupiter's atmosphere, under the ionosphere, the lightning and radio emission detector measured radio frequency signals at levels significantly above the probe's electromagnetic noise. The signal strengths at 3 and 15 kilohertz were relatively large at the beginning of the descent, decreased with depth to a pressure level of about 5 bars, and then increased slowly until the end of the mission. The 15-kilohertz signals show arrival direction anisotropies. Measurements of radio frequency wave forms show that the probe passed through an atmospheric region that did not support lightning within at least 100 kilometers and more likely a few thousand kilometers of the descent trajectory. The apparent opacity of the jovian atmosphere increases sharply at pressures greater than about 4 bars.

Coagulation factor XII (FXII) activity, activated FXII, distribution of FXII C46T gene polymorphism and coronary risk

BACKGROUND

Whether factor XII (FXII) activity, its 46C>T polymorphism and activated FXII (FXIIa) are associated with coronary heart disease (CHD) remains to be determined.

METHODS

FXII, FXIIa and the FXII 46C>T polymorphism were determined in a hospital-based cohort of 2615 patients undergoing coronary angiography.

RESULTS

Fifty-seven per cent of the participants were identified as wild-type (46CC), 38% as heterozygous (46CT) and 5% as homozygous (46TT) for FXII 46C>T. FXII and FXIIa levels were significantly lower in carriers of the T-allele: 132 (97-151) U dL(-1) FXII in 46CC, 87 (77-99) U dL(-1) FXII in 46CT and 53 (42-67) U dL(-1) FXII in 46TT carriers (P < 0.001), and 2.8 (2.3-3.5) microg L(-1) FXIIa in CC, 2.1 (1.6-2.6) microg L(-1) FXIIa in CT and 1.2 (0.9-1.5) microg L(-1) FXIIa in TT carriers (P < 0.001; medians, lower and upper quartiles). Patients with stable CHD (n = 935), a history of myocardial infarction (n = 785) or who were suffering from acute coronary syndromes (ACS; n = 323) had significantly lower FXII levels than controls (n = 572). The differences remained statistically significant after adjustments for age, sex, diabetes mellitus, smoking, hypercholesterolemia and hypertension. Significantly reduced FXIIa levels in ACS patients lost significance once adjusted for covariates. FXII genotype was not associated with any clinical phenotype.

CONCLUSION

Lower FXII activity represents an independent risk for CHD and ACS. This is not the case for FXIIa levels or the FXII 46C>T variation.

Murine models of polycystic kidney disease

The current knowledge of human polycystic kidney disease (PKD)--its morphology as well as the current biochemical and molecular understanding of the disease- has been enormously aided by the existence of a variety of animal models. In mice, several spontaneous mutations have been identified that give rise to PKD. Furthermore, it has been possible to create experimental models of renal cystic disease by genetic manipulation. All these different models have been very informative in studying the role of growth hormones, cell differentiation and hyperplasia, ionic transport, oncogene expression and changes in extracellular matrix (ECM) composition during the development of PKD. Furthermore, they have allowed investigators to test different therapeutic approaches in vivo. This article will review the characteristics of the most common murine models of PKD, some of their current uses and the future role of these animal models in the understanding of human renal cystic disease.

Michigan BioTrust for Health: public support for using residual dried blood spot samples for health research

PURPOSE

Focus groups were utilized as a mechanism to solicit input from the public in developing the Michigan BioTrust for Health, a program of the Michigan Department of Community Health to improve storage conditions and promote use of residual newborn screening dried blood spots in health research.

METHODS

In 2008-2009, 10 diverse communities representative of the general public that might have special concerns as stakeholders in the BioTrust were identified, and 4 discussion questions were developed for use with a standard agenda. Focus group discussions were audio-recorded and transcribed by department staff. Qualitative conclusions resulting from the group discussions were compared with written, quantitative pre- and post-survey responses completed by individual participants.

RESULTS

Overall, there was considerable concurrence of opinion across the focus groups. Participants were generally positive about the BioTrust; a sentiment that held true across different demographic populations with over 85% of participants stating they would support use of residual dried blood spots in health research.

CONCLUSION

The focus group process and findings played an important role for public health policy makers in affirming the importance of engaging and informing the public and led to concrete steps to foster community support.

The impact of the intensity of serial automated plasmapheresis and the speed of deep-freezing on the quality of plasma

BACKGROUND

Data are lacking on the impact that the intensity of serial donor plasmapheresis has on the quality of source plasma. A study was conducted to examine the quality of source plasma produced by intensive plasmapheresis and slow deep-freezing and to compare it to source plasma manufactured by moderate plasmapheresis and rapid freezing.

STUDY DESIGN AND METHODS

Seventy-five plasma samples from intensive plasmapheresis programs (Group 1) and 75 plasma units from moderate plasmapheresis programs (Group 2) were examined. The plasma had been deep-frozen either slowly at -30 degrees C in walk-in freezers (Group 1) or rapidly within 1 hour to a core temperature below -30 degrees C (Group 2). Determinations were made of the plasma levels of citrate; total protein; albumin; IgG; fibrinogen; factors II, V, VII, VIII, and IX; vWF; antithrombin; protein C; D-dimers; and prothrombin fragments 1+ 2.

RESULTS

Plasma units of Group 2 contained substantially greater levels of citrate, IgG, FVIII, and FV than samples of Group 1 (p<0.0001). Plasma levels of total protein, albumin, and fibrinogen also were higher in Group 2 (p<0.0001, p = 0.007, and p = 0.006, respectively). Neither plasmapheresis intensity nor freezing procedure had any influence on the levels of factors II, VII, and IX, antithrombin, or protein C. There was no evidence of substantial coagulation activation in the plasma units of either group. However, higher FVIII clotting activity/chromogenic substrate activity ratios in rapidly frozen plasmas and a significant correlation between these ratios and prothrombin fragment 1+ 2 levels suggest that rapid freezing yields both more native FVIII and greater partial activation of FVIII.

CONCLUSION

Source plasma collected from donors undergoing intensified plasmapheresis contains markedly lower levels of IgG than plasma units produced by moderate serial plasmapheresis. The combination of intensified plasmapheresis and slower freezing of source plasma results in substantially lower levels of FV and FVIII than does moderate plasmapheresis with rapid freezing. Prospective studies should establish the optimum conditions required for the safe and economic production of source plasma for fractionation.

Invited article: Coherent imaging using seeded free-electron laser pulses with variable polarization: first results and research opportunities

FERMI@Elettra, the first vacuum ultraviolet and soft X-ray free-electron laser (FEL) using by default a "seeded" scheme, became operational in 2011 and has been opened to users since December 2012. The parameters of the seeded FERMI FEL pulses and, in particular, the superior control of emitted radiation in terms of spectral purity and stability meet the stringent requirements for single-shot and resonant coherent diffraction imaging (CDI) experiments. The advantages of the intense seeded FERMI pulses with variable polarization have been demonstrated with the first experiments performed using the multipurpose experimental station operated at the diffraction and projection imaging (DiProI) beamline. The results reported here were obtained with fixed non-periodic targets during the commissioning period in 2012 using 20-32 nm wavelength range. They demonstrate that the performance of the FERMI FEL source and the experimental station meets the requirements of CDI, holography, and resonant magnetic scattering in both multi- and single-shot modes. Moreover, we present the first magnetic scattering experiments employing the fully circularly polarized FERMI pulses. The ongoing developments aim at pushing the lateral resolution by using shorter wavelengths provided by double-stage cascaded FERMI FEL-2 and probing ultrafast dynamic processes using different pump-probe schemes, including jitter-free seed laser pump or FEL-pump∕FEL-probe with two color FEL pulses generated by the same electron bunch.

Canine awake head-out plethysmography (HOP): Characterization of external resistive loading and spontaneous laryngeal paralysis

We applied a novel head-out plethysmographic (HOP) method to study awake canine responses to external resistive loading and natural laryngeal paralysis. Measurements of inspiratory and expiratory specific airway resistance (sRaw(insp), sRaw(exp)) were obtained before and after uni- and bidirectional loading (R(add) = 5 cmH(2)O/L/s) in large-breed dogs (n = 9). Mean sRaw(insp) after inspiratory, and sRaw(exp) after expiratory loading were 31.4 and 33.3 cmH(2)Os, respectively. Bidirectional loads induced a significantly greater rise in both sRaw(insp) and sRaw(exp) (55.1 and 61.3 cmH(2)Os) compared to unidirectional loading (P < 0.001). Yet, type of loading did not affect flow-volume indices. The mean R(aw) of dogs was 4.81 cmH(2)O/L/s. Expiratory loading resulted in a significant 8.8% increase in functional-residual-capacity (FRC), compared to FRC(baseline) (76.7 ml/kg). Dogs (n = 5) with laryngeal paralysis demonstrated a significant increase in sR(aw) and R(aw) compared to controls without changes in FRC. In conclusion, HOP precisely characterized sR(aw) in response to external resistive loading. Hence, we could accurately quantify airway obstruction in awake dogs with laryngeal paralysis.

Urokinase and plasminogen activator-inhibitor (PAI-1) status in primary ovarian carcinomas and ovarian metastases compared to benign ovarian tumors as a function of histopathological parameters

Ninety-eight patients with histologically confirmed ovarian tumors (77 primary ovarian carcinomas of stages T1 to T3 according to the postoperative histopathological classification pTNM classification, 14 ovarian metastases of various origins and seven benign ovarian tumors) were investigated with regard to the concentration of urokinase-type plasminogen activator (uPA) and plasminogen activator inhibitor (PAI-1) in membrane extracts of tumors. The results were correlated with the clinical course and with histopathological findings. With more advanced stage of primary ovarian carcinomas, there was a highly significant rise in the membrane concentrations of both uPA and PAI-1. However, increasing dedifferentiation of the tumors correlated only with uPA, but not with PAI-1. There was no correlation between the number of steroid receptors for estradiol and progesterone and the content of uPA or PAI-1 in the primary ovarian carcinomas. In the 14 ovarian metastases of different origins incluced in the study, the contents of uPA and PAI-1 were comparable to those of primary ovarian carcinomas. Compared with the malignant ovarian tumors, the median uPA and PAI-1 concentrations in the membrane fraction were 2.5-6 fold lower (highly significant) in the group of seven benign tumors. A cut-off value of 4.8ng/mg pellet protein for a prognostically favorable (< 4.8) or unfavorable course (> 4.8) could be determined for uPA (p = 0.0392) but not for PAI-1 on the basis of the Kaplan and Meier survival curves in the malignant primary ovarian carcinomas.

Radon levels in groundwaters and natural radioactivity in soils of the volcanic region of La Garrotxa, Spain

Groundwater radon level and soil radionuclide concentration have been measured in the volcanic region of La Garrotxa (Catalonia, Spain) to further research on the origin and dynamics of high radon levels over volcanic materials found in this region. Water samples from different aquifers have been collected from wells and springs and the water radon levels obtained have been lower than 30 Bq l(-1). Soil samples have been collected from different geological formations (volcanic and non-volcanic), being Quaternary sedimentary deposits those that have presented the highest mean values of (40)K, (226)Ra and (232)Th concentrations (448 ± 70 Bq kg(-1), 35 ± 5 Bq kg(-1) and 38 ± 5 Bq kg(-1), respectively). Additionally, indoor/outdoor terrestrial radiation absorbed dose rate in air have been measured to better characterize the region from the radiological point of view. Terrestrial radiation absorbed dose rates measurement points have been chosen on the basis of geological and demographical considerations and the results obtained, from 27 to 91 nGy h(-1), show a clear relation with geological formation materials. The highest terrestrial gamma absorbed dose rate is observed over Quaternary sedimentary deposits as well. All these results help to better understand previous surveys related with indoor and outdoor radon levels and to reinforce the hypotheses of a radon transport through the fissure network.

Functional magnetic resonance imaging of the ascending stages of the auditory system in dogs

Background

Functional magnetic resonance imaging (fMRI) is a technique able to localize neural activity in the brain by detecting associated changes in blood flow. It is an essential tool for studying human functional neuroanatomy including the auditory system. There are only a few studies, however, using fMRI to study canine brain functions. In the current study ten anesthetized dogs were scanned during auditory stimulation. Two functional sequences, each in combination with a suitable stimulation paradigm, were used in each subject. Sequence 1 provided periods of silence during which acoustic stimuli could be presented unmasked by scanner noise (sparse temporal sampling) whereas in sequence 2 the scanner noise was present throughout the entire session (continuous imaging). The results obtained with the two different functional sequences were compared.

Results

This study shows that with the proper experimental setup it is possible to detect neural activity in the auditory system of dogs. In contrast to human fMRI studies the strongest activity was found in the subcortical parts of the auditory pathways. Especially sequence 1 showed a high reliability in detecting activated voxels in brain regions associated with the auditory system.

Conclusion

These results indicate that fMRI is applicable for studying the canine auditory system and could become an additional method for the clinical evaluation of the auditory function of dogs. Additionally, fMRI is an interesting technique for future studies concerned with canine functional neuroanatomy.