Tracking eolian dust with helium and thorium: Impacts of grain size and provenance

Reconstructions of the deposition rate of windblown mineral dust in ocean sediments offer an important means of tracking past climate changes and of assessing the radiative and biogeochemical impacts of dust in past climates. Dust flux estimates in ocean sediments have commonly been based on the operationally defined lithogenic fraction of sediment samples. More recently, dust fluxes have been estimated from measurements of helium and thorium, as rare isotopes of these elements (He-3 and Th-230) allow estimates of sediment flux, and the dominant isotopes (He-4 and Th-232) are uniquely associated with the lithogenic fraction of marine sediments. In order to improve the fidelity of dust flux reconstructions based on He and Th, we present a survey of He and Th concentrations in sediments from dust source areas in East Asia, Australia and South America. Our data show systematic relationships between He and Th concentrations and grain size, with He concentrations decreasing and Th concentrations increasing with decreasing grain size. We find consistent He and Th concentrations in the fine fraction (<5 μm) of samples from East Asia, Australia and Central South America (Puna-Central West Argentina), with Th concentrations averaging 14 μg/g and He concentrations averaging 2 μcc STP/g. We recommend use of these values for estimating dust fluxes in sediments where dust is dominantly fine-grained, and suggest that previous studies may have systematically overestimated Th-based dust fluxes by 30%. Source areas in Patagonia appear to have lower He and Th contents than other regions, as fine fraction concentrations average 0.8 μcc STP/g and 9 μg/g for 4He and 232Th, respectively. The impact of grain size on lithogenic He and Th concentrations should be taken into account in sediments proximal to dust sources where dust grain size may vary considerably. Our data also have important implications for the hosts of He in long-traveled dust and for the 3He/4He ratio used for terrigenous He in studies of extraterrestrial He in sediments and ice. We also investigate the use of He/Th ratios as a provenance tracer. Our results suggest differences in fine fraction He/Th ratios between East Asia, Australia, central South America and Patagonia, with ratios showing a positive relationship with the geological age of source rocks. He/Th ratios may thus provide useful provenance information, for example allowing separation of Patagonian sources from Puna-Central West Argentina or Australian dust sources. He/Th ratios in open-ocean marine sediments are similar to ratios in the fine fraction of upwind dust source areas. He/Th ratios in mid-latitude South Atlantic sediments suggest that dust in this region primarily derives from the Puna-Central West Argentina region (23–32°S) rather than Patagonia (>38°S). In the equatorial Pacific, He/Th ratios are much lower than in extratropical Pacific sediments or potential source areas measured as a part of this study (East Asia, South America, Australia) for reasons that are at present unclear, complicating their use as provenance tracers in this region.

Catch-up alveolarization in ex-preterm children: evidence from (3)He magnetic resonance

RATIONALE Histologic data from fatal cases suggest that extreme prematurity results in persisting alveolar damage. However, there is new evidence that human alveolarization might continue throughout childhood and could contribute to alveolar repair. OBJECTIVES To examine whether alveolar damage in extreme-preterm survivors persists into late childhood, we compared alveolar dimensions between schoolchildren born term and preterm, using hyperpolarized helium-3 magnetic resonance. METHODS We recruited schoolchildren aged 10-14 years stratified by gestational age at birth (weeks) to four groups: (1) term-born (37-42 wk; n = 61); (2) mild preterm (32-36 wk; n = 21); (3) extreme preterm (<32 wk, not oxygen dependent at 4 wk; n = 19); and (4) extreme preterm with chronic lung disease (<32 wk and oxygen dependent beyond 4 wk; n = 18). We measured lung function using spirometry and plethysmography. Apparent diffusion coefficient, a surrogate for average alveolar dimensions, was measured by helium-3 magnetic resonance. MEASUREMENTS AND MAIN RESULTS The two extreme preterm groups had a lower FEV1 (P = 0.017) compared with term-born and mild preterm children. Apparent diffusion coefficient was 0.092 cm(2)/second (95% confidence interval, 0.089-0.095) in the term group. Corresponding values were 0.096 (0.091-0.101), 0.090 (0085-0.095), and 0.089 (0.083-0.094) in the mild preterm and two extreme preterm groups, respectively, implying comparable alveolar dimensions across all groups. Results did not change after controlling for anthropometric variables and potential confounders. CONCLUSIONS Alveolar size at school age was similar in survivors of extreme prematurity and term-born children. Because extreme preterm birth is associated with deranged alveolar structure in infancy, the most likely explanation for our finding is catch-up alveolarization.

Up-regulation of somatostatin receptor density on rat CA20948 tumors escaped from low dose [(177)Lu-DOTA(0),Tyr(3)]octreotate therapy

AIM: Peptide receptor radionuclide therapy using the somatostatin analogue [(177)Lu-DOTA(0),Tyr(3)]octreotate is a convincing treatment modality for metastasized neuroendocrine tumors. Therapeutic doses are administered in 4 cycles with 6-10 week intervals. A high somatostatin receptor density on tumor cells is a prerequisite at every administration to enable effective therapy. In this study, the density of the somatostatin receptor subtype 2 (sst2) was investigated in the rat CA20948 pancreatic tumor model after low dose [(177)Lu-DOTA(0), Tyr(3)]octreotate administration resulting in approximately 20 Gy tumor radiation absorbed dose, whereas 60 Gy is needed to induce complete tumor regression in these and the majority of tumors. METHODS: Sixteen days after inoculation of the CA20948 tumor, male Lewis rats were injected with 185 MBq [(177)Lu-DOTA(0),Tyr(3)]octreotate to initiate a decline in tumor size. Approximately 40 days after injection, tumors re-grew progressively after initial response. Quantification of sst2 expression was performed using in vitro autoradiography on frozen sections of three groups: control (not-treated) tumors, tumors in regression and tumors in re-growth. Histology and proliferation were determined using HE- and anti-Ki-67-staining. RESULTS: The sst2 expression on CA20948 tumor cells decreased significantly after therapy to 5% of control level. However, tumors escaping from therapy showed an up-regulated sst2 level of 2-5 times higher sst2 density compared to control tumors. CONCLUSION: After a suboptimal therapeutic dose of [(177)Lu-DOTA(0),Tyr(3)]octreotate, escape of tumors is likely to occur. Since these cells show an up-regulated sst2 receptor density, a next therapeutic administration of radiolabelled sst2 analogue can be expected to be highly effective.

Differential effectiveness of integrated cognitive remediation therapy for schizophrenbia outpatients: The impact oft he duration of illness

Background Nowadays there is extensive evidence available showing the efficacy of cognitive remediation (CR). To date, only limited evidence is available about the impact of the duration of illness on CR effects. The Integrated Neurocognitive Therapy (INT) represents a new developed CR approach. It is a manualized group therapy targeting all 11 NIMH-MATRICS domains. Methods In an international multicenter study, 166 schizophrenia outpatients (DSM-IV-TR) were randomly assigned either to INT or to Treatment-As-Usual (TAU). 60 patients were defined as Early Course group (EC) characterized by less than 5 years of illness, 40 patients were in the Long-Term group (LT) characterized by more than 15 years of illness, and 76 patients were in the Medium-Long-Term group (MLT) characterized by an illness of 5-15 years. Treatment comprised of 15 biweekly sessions. Assessments were conducted before and after treatment and at follow up (1 year). Multivariate General Linear Models (GLM) examined our hypothesis, whether EC, LT, and MLT groups differ under INT and TAU from each other in outcome. Results First of all, the attendance rate of 65% was significantly lower and the drop out rate of 18.5% during therapy was higher in the EC group compared to the other groups. Interaction effects regarding proximal outcome showed that the duration of illness has a strong impact on neurocognitive functioning in speed of processing (F>2.4) and attention (F>2.8). But INT intervention compared to TAU only had a significant effect in more chronically ill patients of MLT and LT, but not in younger patients in EC. In social cognitive domains, only the EC group showed a significant change in attribution (hostility; F>2.5), LT and MLT groups did not. However, no differences between the 3 groups were evident in memory, problem solving, and emotion perception. Regarding more distal outcome, LT patients had more symptoms compared to EC (F>4.4). Finally, EC patients showed higher improvements in psychosocial functioning compared to LT and MLT (F=1.8). Conclusions Against common expectations, long-term, more chronically ill patients showed higher effects in basal cognitive functions compared to younger patients and patients without any active therapy (TAU). On the other hand, early-course patients had a greater potential to change in attribution, symptoms and psychosocial functioning. Consequently, more integrated therapy offers are also recommended for long-term course schizophrenia patients.

Human 3β-hydroxysteroid dehydrogenase deficiency seems to affect fertility but may not harbor a tumor risk: lesson from an experiment of nature.

CONTEXT 3β-hydroxysteroid dehydrogenase deficiency (3βHSD) is a rare disorder of sexual development and steroidogenesis. There are two isozymes of 3βHSD, HSD3B1 and HSD3B2. Human mutations are known for the HSD3B2 gene which is expressed in the gonads and the adrenals. Little is known about testis histology, fertility and malignancy risk. OBJECTIVE To describe the molecular genetics, the steroid biochemistry, the (immuno-)histochemistry and the clinical implications of a loss-of-function HSD3B2 mutation. METHODS Biochemical, genetic and immunohistochemical investigations on human biomaterials. RESULTS A 46,XY boy presented at birth with severe undervirilization of the external genitalia. Steroid profiling showed low steroid production for mineralocorticoids, glucocorticoids and sex steroids with typical precursor metabolites for HSD3B2 deficiency. The genetic analysis of the HSD3B2 gene revealed a homozygous c.687del27 deletion. At pubertal age, he showed some virilization of the external genitalia and some sex steroid metabolites appeared likely through conversion of precursors secreted by the testis and converted by unaffected HSD3B1 in peripheral tissues. However, he also developed enlarged breasts through production of estrogens in the periphery. Testis histology in late puberty revealed primarily a Sertoli-cell-only pattern and only few tubules with arrested spermatogenesis, presence of few Leydig cells in stroma, but no neoplastic changes. CONCLUSIONS The testis with HSD3B2 deficiency due to the c.687del27 deletion does not express the defective protein. This patient is unlikely to be fertile and his risk for gonadal malignancy is low. Further studies are needed to obtain firm knowledge on malignancy risk for gonads harboring defects of androgen biosynthesis.

The Interstellar Neutral He haze in the heliosphere: what can we learn?

Neutral interstellar helium has been observed by the Interstellar Boundary Explorer (IBEX) since 2009, with a signal-to-noise ratio well above 1000. Because of the geometry of the observations, the signal observed from January to March each year is the easiest to identify. However, as we show via simulations, the portion of the signal in the range of intensities from 10(-3) to 10(-2) of the peak value, previously mostly left out from the analysis, may provide important information about the details of the distribution function of interstellar He gas in front of the heliosphere. In particular, these observations may inform us about possible departures of the parent interstellar He population from equilibrium. We compare the expected distribution of the signal for the canonical assumption of a single Maxwell-Boltzmann population with the distributions for a superposition of the Maxwell-Boltzmann primary population and the recently discovered Warm Breeze, and for a single primary population given by a kappa function. We identify the regions on the sky where the differences between those cases are expected to be the most visible against the background. We discuss the diagnostic potential of the fall peak of the interstellar signal, reduced by a factor of 50 due to the Compton-Getting effect but still above the detection limit of IBEX. We point out the strong energy dependence of the fall signal and suggest that searching for this signal in the data could bring an independent assessment of the low-energy measurement threshold of the IBEX-Lo sensor.